Carine Smith | Stellenbosch University (original) (raw)

Papers by Carine Smith

Research paper thumbnail of The potential of zebrafish as drug discovery research tool in immune-mediated inflammatory disease

Inflammopharmacology, Jun 26, 2024

Research paper thumbnail of Exposure of Cryptococcus neoformans to low nitrogen levels enhances virulence

International microbiology, Mar 14, 2024

Previous studies have shown a correlation between nitrogen levels and Cryptococcus neoformans pat... more Previous studies have shown a correlation between nitrogen levels and Cryptococcus neoformans pathogenicity. Here we report on the in vivo effects of cryptococcal pre-exposure to ecologically relevant nitrogen levels. C. neoformans H99 was cultured in yeast carbon base (YCB) supplemented with 0.53 g/L NH 4 Cl and 0.21 g/L NH 4 Cl, respectively, and used to infect larvae of the Greater Wax moth, Galleria mellonella. Cells cultured in low nitrogen YCB (LN) were more virulent compared to cells cultured in high nitrogen YCB (HN). Microscopic examination of haemolymph collected from infected larvae revealed that cells cultured in LN were larger than cells cultured in HN, with the majority of LN cells exceeding 10 µm and possibly entering titanisation. Additionally, compared to HN-cultured cells, fewer LN-cultured cells were engulfed by macrophages. The enhanced virulence of LN-cultured cells was attributed to the increased cell size in vivo. In contrast, reduced macrophage uptake was attributed to increased capsule thickness of in vitro cells. Not only do these findings demonstrate the effects of culture conditions, specifically nitrogen levels, on C. neoformans virulence, but they also highlight the importance of isolate background in the cryptococcal-host interaction.

Research paper thumbnail of Translation of preclinical ethnomedicine data in LMICs: the example of rooibos

Frontiers in Pharmacology, Dec 18, 2023

All disease, but especially non-communicable diseases, are related to dysfunction of one or more ... more All disease, but especially non-communicable diseases, are related to dysfunction of one or more regulatory systems. In developing countries, long-term management of patients with chronic diseases has many challenges and is generally not financially viable, but Africa in particular, which is rich in diverse ethnomedicines presents a more feasible long-term therapeutic approach in this niche. However, despite comprehensive preclinical investigations on numerous plant-derived candidate medicines, only a small portion of these reach the patient as recognised medicines. In this review, we use the example of rooibos (Aspalathus linearis (Burm.f.) R. Dahlgren)-which is globally consumed as aromatic, caffeine-free tea-to illustrate the hurdles that need to be overcome in the low-to middle-income countries, before progression of ethnomedicines to official treatment regimens can be achieved. In terms of methodology, regulatory system focused rooibos papers indexed on PubMed for the past three decades (n = 112) were accessed. Papers reporting duplication of previous results were excluded, as well as review papers. Topics covered includes the high standard of ethnomedicine drug discovery and efficacy testing research performed in Africa (and South Africa in particular in the case of rooibos), the potential bias in terms of preclinical research focus, ethnomedicine ownership and the requirement for independent clinical trial coordination and/or management.

Research paper thumbnail of Dolutegravir quantification in wistar rat tissues following chronic administration

Research paper thumbnail of Corrigendum: A Review: The Fate of Bacteriocins in the Human Gastro-Intestinal Tract: Do They Cross the Gut–Blood Barrier?

Frontiers in Microbiology, Nov 30, 2018

Research paper thumbnail of Sceletium tortuosum may delay chronic disease progression via alkaloid-dependent antioxidant or anti-inflammatory action

Journal of Physiology and Biochemistry, Mar 9, 2018

The link between obesity-induced systemic inflammation and decreased insulin signalling is well-k... more The link between obesity-induced systemic inflammation and decreased insulin signalling is well-known. It is also known that peripherally produced inflammatory cytokines can cross the blood-brain barrier, resulting in the release of neurotoxins that can ultimately lead to the demise of central nervous system integrity. A high-mesembrine Sceletium tortuosum extract was recently shown to possess cytoprotective and mild anti-inflammatory properties in monocytes and to target specific p450 enzymes to reduce adrenal glucocorticoid synthesis. This is significant since the aetiology of both obesity and diabetes is linked to inflammation and excess glucocorticoid production. Given the interlinked nature of glucocorticoid action and inflammation, central immunomodulatory effects of two Sceletium tortuosum extracts prepared by different extraction methods were investigated. Human astrocytes were pre-treated for 30 min, before exposure to Escherichia coli lipopolysaccharide for 23.5 h (in the presence of treatment). Cytotoxicity, mitotoxicity and cytokine responses (basally and in response to inflammatory stimulus) were assessed. In addition, total polyphenol content, antioxidant capacity and selected neural enzyme inhibition capacity were assessed for both extracts. The high-mesembrine Sceletium extract exerted cytoprotective and anti-inflammatory effects. In contrast, the high delta7-mesembrenone extract, rich in polyphenols, exhibited potent antioxidant effect, although with relatively higher risk of adverse effects with overdose. We conclude that both Sceletium tortuosum extracts may be employed as either a preventative supplement or complimentary treatment in the context of obesity and diabetes; however, current data also highlights the impact that extraction methods can have on plant product mechanism of action.

Research paper thumbnail of Gender differences in metabolic risk factor prevalence in a South African student population

Cardiovascular Journal of Africa, May 1, 2009

We determined selected risk factors for the metabolic syndrome and assessed the metabolic risk st... more We determined selected risk factors for the metabolic syndrome and assessed the metabolic risk status (using IDF criteria) of third-year physiology students at Stellenbosch University (88 males and 178 females). Outcome measures included anthropometry [body mass index (BMI), waist circumference, waist-to-hip ratio], blood pressure (BP), resting pulse rate, and fasting blood glucose, total cholesterol and triglyceride levels. In addition, students completed a lifestyle questionnaire. A number of gender-based differences were found, with male students displaying a greater incidence of risk factors for the metabolic syndrome: 6% of males versus 3% of females displayed a cluster of three risk factors. Twenty-five per cent of female students (but only 14% of males) exhibited waist circumferences above the accepted range, which was positively correlated, for males and females, with both systolic and diastolic BP, and in females only, also with total cholesterol levels. Male students on average exercised more than their female counterparts, but also exhibited poorer eating habits. Average blood triglyceride levels for both male and female students exceeded the accepted threshold (1.85 ± 1.62 mmol/l and 2.15 ± 1.79 mmol/l, respectively). We concluded that metabolic risk factors were evident in a much younger population than commonly expected. Moreover, the gender-specific differences observed may impact on future risk assessment and preventative measures adopted.

Research paper thumbnail of The effect of a professional cricket match schedule on selected immune parameters

South African Journal of Sports Medicine, Dec 20, 2004

Objective. The impact of a professional cricket match schedule on white blood cell (WBC) distribu... more Objective. The impact of a professional cricket match schedule on white blood cell (WBC) distribution and lymphocyte activation (CD69 expression) was investigated. Methods. After a 3-month pre-season training period, physical and immune parameters were determined in 14 male cricketers before (B) and after (A) an intensive 5week match schedule. Results. Exercise test results were unchanged from B to A. Total WBC counts were similar, but total lymphocyte and lymphocyte subpopulation counts decreased significantly. The CD4:CD8 ratio did not change. After in vitro stimulation, percentage CD4+CD69+ cells increased (B: 54.4 ± 9.7%, A: 64.0 ± 8.5%, p < 0.01), but absolute CD4+CD69+ cell counts did not change from B to A. In contrast, both the %CD8+CD69+ cells and absolute CD8+CD69+ cell count remained similar. A strenuous, interregional, professional cricket match schedule resulted in a decreased number of lymphocytes, but relatively increased in vitro reactivity of CD4+ cells, thus maintaining the absolute capacity of the CD4+ cells to become activated on stimulation. In cricketers who suffered upper respiratory tract symptoms during the match schedule (N = 7), none of the immune parameters investigated differed significantly from the others at B or A.

Research paper thumbnail of Exercise, stress and immune system functional responses

Chroniese oefening-verwante stres beïnvloed beide the immuun-en endokriene sisteme, maar daar is ... more Chroniese oefening-verwante stres beïnvloed beide the immuun-en endokriene sisteme, maar daar is nog baie aspekte wat swak begryp word, veral m.b.t. die effekte van stres op die funksionele kapasiteit van immuunselle. Hierdie tesis het sommige van dié vraagpunte ondersoek deur gebruik te maak van fisiologiese en psigologiese stres. Beide oefening program-verwante stres en chroniese psigologiese stres in proefpersone het 'n op-regulering van spontane witbloedselreaktiwiteit in vitro tot gevolg gehad, wat d.m.v twee verskillende metodes aangetoon is, naamlik a) 'n perifere bloed mononukluêre selkultuur (PBMS-kultuur) bepaling van immuunsel reaktiwiteit en b) 'n relatief nuwe vloeisitometriese tegniek vir die assessering van aktiveringsstatus van selle, deur hul uitdrukking van die oppervlakmerker CD69, op 'n limfosiet subpopulasie-spesifieke wyse. 'n Opregulering van immuunselaktiwiteit in die afwesigheid van 'n addisionele stressor is geassosieer met 'n verlaagde kapsiteit om te reageer op 'n latere mitogeniese prikkel in vitro, na chroniese psigologiese stres en akute, erge oefeningstres. Nog 'n nuwe bevinding was dat kortisol hoog-respondeerders, in reaksie op chroniese psigologiese stres, 'n hoër spontane reaktiwiteit van beide CD4 + -and CD8 + -limfosiete toon in vergelyking met kortisol laagresopndeerders. Hierdie bevinding toon aan dat chroniese blootstelling aan kortisol die inhiberende effek daarvan op spontane reaktiwiteit van T-limfosiete verminder. Na optimalisering van 'n rotmodel van gematigde, psigologiese stres, het ons gedemonstreer (deur gebruik te maak van 'n IL-6 teenliggaam) dat IL-6 nodig is vir 'n volledige kortisolreaksie op chroniese, onderbroke, gematigde stres. Die resultate dui daarop dat IL-6 'n rol in die regulering van sy eie sekresie deur PBMSe in reaksie tot 'n stressor speel, deur die handhawing van produksie van IL-1β in die teenwoordigheid van stres. Basale serum kortisolkonsentrasie is as die belangrikste beslissende faktor in die omvang van mitogeengestimuleerde PBMS sekresie van IL-6 in vitro in die stresvrye kontroles aangedui. Na blokkering van IL-6 in vivo, is IL-1β egter as 'n belangrike reguleerder van IL-6 sekresie deur mitogeen-gestimuleerde PBMSe in vitro geïdentifiseer, onafhanklik van die teenwoordigheid of afwesigheid van stres. Die implikasie van hierdie nuwe bevindinge is dat proinflammatoriese sitokiene tydens gematigde stres sensitief gereguleer word. Die gemiddelde serum kortisolkonsentrasie in 'n rustende toestand was nie 'n gepaste instrument om chroniese oefeningstres na 'n oefenprogram-ingreep te assesseer nie. Na basislyn klassifikasie van atlete in twee groepe volgens hul rustende serum kortisolkonsentrasie, is twee afsonderlike patrone vir die reaksie van beide kortisol en die kortisol:testosteroon verhouding egter aangetoon. Hierdie studies rakende die effekte van chroniese stres op parameters van die endokriene stres-as en die immuunsisteem het tot die volgende vernaamste gevolgtrekkings gelei: a) chroniese blootstelling aan kortisol het 'n verlaagde inhibisie van spontane immuunselaktiwiteit tydens rustende toestande tot gevolg, b) hierdie verhoogde spontane aktivering van immuunselle tydens 'n rustende toestand word geassosieer met 'n onderdrukking van immuunkapasiteit om te reageer op 'n daaropvolgende prikkel, c) laasgenoemde bevinding is nie sigbaar tydens stresvrye toestande, wanneer kortisol IL-6 sekresie bevorder, nie en d) IL-1β en IL-6 is betrokke by die regulering van mekaar se sekresie.

Research paper thumbnail of Alterations to microbial secretome by estrogen may contribute to sex bias in irritable bowel syndrome

Inflammopharmacology, Jan 13, 2022

INTRODUCTION Irritable bowel syndrome (IBS) is a female predominant functional gastrointestinal d... more INTRODUCTION Irritable bowel syndrome (IBS) is a female predominant functional gastrointestinal disorder, underpinned by microbial dysbiosis and microinflammation. We suggest that changes in trace amine (TA) load and metabolism may link together diet, inflammation and sex in this context. METHODS The effect of E2 treatment on microbial growth and TA generation was assessed using liquid chromatography and tandem mass spectrometry methodology. To investigate the effects of TAs on the gut, WST-1, prostaglandin E2 and tight junction protein dynamics were investigated in TA treated (HT-29) colon epithelial monolayer cultures. RESULTS Differential E2-dependent alterations of the TA production capabilities of microbes were observed. Significantly, E2 treatment resulted in a 50% increase in tryptamine secretion from a probiotic microbe (p < 0.0001). Moreover, in vitro experiments indicated that TA treatment exerted type-specific effects in the gut, e.g., reducing mitochondrial functionality, even at low doses of tryptamine (p < 0.0001) and ρ-tyramine (p < 0.001). Additionally, prostaglandin E2 levels were significantly increased following ρ-tyramine and agmatine treatment (p < 0.05). In terms of functionality, all investigated TAs resulted in occludin redistribution and loss of zona occludens-1 and occludin co-localization. CONCLUSION Increases in the gastrointestinal TA load may contribute to a relatively pro-inflammatory outcome in the intestine, along with tight junction protein disruption. Additionally, fluctuating levels of endogenous E2 may modulate microbially-derived TA levels, potentially explaining exaggerating gastrointestinal symptomology in females during low E2 phases. Thus, current data warrants subsequent investigations in appropriate in vivo models to fully elucidate the role of the trace aminergic system in the sex bias observed in IBS.

Research paper thumbnail of Influence of lifestyle choices on metabolic risk has distinct gender and age differences

International journal of clinical and experimental physiology, 2014

Influence of lifestyle choices on metabolic risk has distinct gender and age differences than one... more Influence of lifestyle choices on metabolic risk has distinct gender and age differences than one cardiovascular risk factor, such as elevated blood pressure (BP) or central obesity. It is known that abdominal adipose tissue releases non-esterified fatty acids into circulation, which inhibits insulin-stimulated glucose uptake and may prompt pro-inflammatory cytokine secretion. This, along with the accumulation of inflammatory macrophages in adipose tissue is associated with increased low-grade chronic inflammation, a major contributor for development of diabetes and CVD. The burden of the metabolic syndrome has become global and the condition is manifesting more in younger populations, which has huge health and economic implications. We have recently reported that in a South African student population the diagnostic risk criteria for the metabolic syndrome as defined by the International Diabetes Federation (IDF), are present in an alarmingly high percentage in younger generations. Earlier awareness of these problems can possibly help to reduce the incidence of life-style-associated diseases. This can

Research paper thumbnail of In utero Exposure to Maternal Chronic Inflammation Transfers a Pro-Inflammatory Profile to Generation F2 via Sex-Specific Mechanisms

Frontiers in Immunology, Feb 13, 2020

Generational transfer of maladaptations in offspring have been reported to persist for multiple g... more Generational transfer of maladaptations in offspring have been reported to persist for multiple generations in conditions of chronic inflammation, metabolic and psychological stress. Thus, the current study aimed to expand our understanding of the nature, potential sex specificity, and transgenerational plasticity of inflammatory maladaptations resulting from maternal chronic inflammation. Briefly, F1 and F2 generations of offspring from C57/BL/6 dams exposed to a modified maternal periconception systemic inflammation (MSPI) protocol were profiled in terms of leukocyte and splenocyte counts and cytokine responses, as well as glucocorticoid sensitivity. Overall, F1 male and female LPS groups presented with glucocorticoid hypersensitivity (with elevated corticosterone and increased leukocyte glucocorticoid receptor levels) along with a pro-inflammatory phenotype, which carried over to the F2 generation. The transfer of inflammatory and glucocorticoid responsiveness from F1 to F2 is evident, with heritability of this phenotype in F2. The findings suggest that maternal (F0) perinatal chronic inflammation resulted in glucocorticoid dysregulation and a resultant pro-inflammatory phenotype, which is transferred in the maternal lineage but seems to affect male offspring to a greater extent. Of further interest, upregulation of IL-1β cytokine responses is reported in female offspring only. The cumulative maladaptation reported in F2 offspring when both F1 parents were affected by maternal LPS exposure is suggestive of immune senescence. Given the potential impact of current results and the lack of sex-specific investigations, more research in this context is urgently required.

Research paper thumbnail of Rheumatoid cachexia: the underappreciated role of myoblast, macrophage and fibroblast interplay in the skeletal muscle niche

Journal of Biomedical Science, Mar 3, 2021

Although rheumatoid arthritis affects 1% of the global population, the role of rheumatoid cachexi... more Although rheumatoid arthritis affects 1% of the global population, the role of rheumatoid cachexia, which occurs in up to a third of patients, is relatively neglected as research focus, despite its significant contribution to decreased quality of life in patients. A better understanding of the cellular and molecular processes involved in rheumatoid cachexia, as well as its potential treatment, is dependent on elucidation of the intricate interactions of the cells involved, such as myoblasts, fibroblasts and macrophages. Persistent RA-associated inflammation results in a relative depletion of the capacity for regeneration and repair in the satellite cell niche. The repair that does proceed is suboptimal due to dysregulated communication from the other cellular role players in this multi-cellular environment. This includes the incomplete switch in macrophage phenotype resulting in a lingering pro-inflammatory state within the tissues, as well as fibroblast-associated dysregulation of the dynamic control of the extracellular matrix. Additional to this endogenous dysregulation, some treatment strategies for RA may exacerbate muscle wasting and no multi-cell investigation has been done in this context. This review summarizes the most recent literature characterising clinical RA cachexia and links these features to the roles of and complex communication between multiple cellular contributors in the muscle niche, highlighting the importance of a targeted approach to therapeutic intervention.

Research paper thumbnail of Sutherlandia frutescens may exacerbate HIV-associated neuroinflammation

Journal of Negative Results in Biomedicine, Jul 18, 2015

Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disord... more Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disorders (HAND) that are prevalent in late stage AIDS. Anti-retroviral (ARV) treatments are rolled out relatively late in the context of neuroinflammatory changes, so that their usefulness in directly preventing HAND is probably limited. It is common practice for HIV+ individuals in developing countries to make use of traditional medicines. One such medicine is Sutherlandia frutescens -commonly consumed as a water infusion. Here its efficacy as an anti-inflammatory modality in this context was investigated in an in vitro co-culture model of the blood-brain barrier (BBB). Methods: Single cultures of human astrocytes (HA), HUVECs and primary human monocytes, as well as co-cultures (BBB), were stimulated with HIV-1 subtype B & C Tat protein and/or HL2/3 cell secretory proteins after pre-treatment with S.frutescens extract. Effects of this pre-treatment on pro-inflammatory cytokine secretion and monocyte migration across the BBB were assessed. Results: In accordance with others, B Tat was more pro-inflammatory than C Tat, validating our model. S.frutescens decreased IL-1β secretion significantly (P < 0.0001), but exacerbated both monocyte chemoattractant protein-1 (P < 0001)a major role player in HIV-associated neuroinflammationand CD14+ monocyte infiltration across the BBB (P < 0.01). Conclusions: Current data illustrates that the combined use of HL2/3 cells and the simulated BBB presents an accurate, physiologically relevant in vitro model with which to study neuroinflammation in the context of HIV/AIDS. In addition, our results caution against the use of S.frutescens as anti-inflammatory modality at any stage post-HIV infection.

Research paper thumbnail of Natural antioxidants in prevention of accelerated ageing: a departure from conventional paradigms required

Journal of Physiology and Biochemistry, Mar 14, 2018

The modern lifestyle is characterised by various factors that cause accelerating ageing by the up... more The modern lifestyle is characterised by various factors that cause accelerating ageing by the upregulation of oxidative stress and inflammation-two processes that are inextricably linked in an endless circle of self-propagation. Inflammation in particular is commonly accepted as aetiological factor in many chronic disease states, such as obesity, diabetes and depression. In terms of disease prevention or treatment, interventions aimed at changing dietary and/or exercise habits have had limited success in practise, mostly due to poor long-term compliance. Furthermore, other primary stimuli responsible for eliciting an oxidative stress or inflammatory response-e.g. psychological stress and anxiety-cannot always be easily addressed. Thus, preventive medicine aimed at countering the oxidative stress and/or inflammatory responses has become of interest. Especially in developing countries, such as South Africa, the option of development of effective strategies from plants warrants further investigation. A brief overview of the most relevant and promising South African plants which have been identified in the context of inflammation, oxidative stress and chronic disease is provided here. In addition, and more specifically, our group and others have shown considerable beneficial effects across many models, after treatment with products derived from grapes. Of particular interest, specific cellular mechanisms have been identified as therapeutic targets of grape-derived polyphenols in the context of inflammation and oxidative stress. The depth of these studies afforded some additional insights, related to methodological considerations pertaining to animal vs. human models in natural product research, which may address the current tendency for generally poor translation of positive animal model results into human in vivo models. The importance of considering individual data vs. group averages in this context is highlighted.

Research paper thumbnail of Polyphenol-associated oxidative stress and inflammation in a model of LPS-induced inflammation in glial cells: do we know enough for responsible compounding?

Inflammopharmacology, Dec 13, 2018

Cyanidin and chlorogenic acid are polyphenols from plant origin that are present in many common f... more Cyanidin and chlorogenic acid are polyphenols from plant origin that are present in many common fruits, particularly in berries. To corroborate the protective or detrimental effects of both compounds from a neuro-inflammatory perspective, in vitro experiments were carried out in human astrocytes (U-373). Astrocytes were pre-treated with a range of concentrations of either cyanidin, chlorogenic acid or a combined treatment for a period of 30 min, before exposure to Escherichia coli lipopolysaccharide (LPS) challenge for 23.5 h, after which cytotoxicity (propidium iodide exclusion assay), cytoprotective effects (XTT assay) and effects on functional capacity (secretion of pro-inflammatory cytokines IL-6 and MCP-1) were evaluated. No treatment resulted in cytotoxicity, but high dose (20 µg/mL) LPS significantly reduced mitochondrial reductive capacity (p < 0.001). This effect was prevented in a dose-dependent manner by both cyanidin and chlorogenic acid, as well as by the combination treatment. However, in the absence of LPS, IL-6 secretion was significantly increased in response to 2 µM of either cyanidin or chlorogenic acid (both p < 0.0001), as well as the combination treatment (p < 0.01). MCP-1 secretion followed a similar trend, but did not reach statistical significance. Although we acknowledge the requirement for in vivo investigations to validate our interpretations, current data highlight the potential risk for antioxidant toxicity that is linked to high dose supplementation with single compound antioxidants. Research focused at elucidating synergistic effects between different antioxidants is required to minimise risk of adverse effects.

Research paper thumbnail of Harnessing Macrophages for Controlled-Release Drug Delivery: Lessons From Microbes

Frontiers in Pharmacology, Jan 25, 2019

With the effectiveness of therapeutic agents ever decreasing and the increased incidence of multi... more With the effectiveness of therapeutic agents ever decreasing and the increased incidence of multi-drug resistant pathogens, there is a clear need for administration of more potent, potentially more toxic, drugs. Alternatively, biopharmaceuticals may hold potential but require specialized protection from premature in vivo degradation. Thus, a paralleled need for specialized drug delivery systems has arisen. Although cell-mediated drug delivery is not a completely novel concept, the few applications described to date are not yet ready for in vivo application, for various reasons such as drug-induced carrier cell death, limited control over the site and timing of drug release and/or drug degradation by the host immune system. Here, we present our hypothesis for a new drug delivery system, which aims to negate these limitations. We propose transport of nanoparticle-encapsulated drugs inside autologous macrophages polarized to M1 phenotype for high mobility and treated to induce transient phagosome maturation arrest. In addition, we propose a significant shift of existing paradigms in the study of host-microbe interactions, in order to study microbial host immune evasion and dissemination patterns for their therapeutic utilization in the context of drug delivery. We describe a system in which microbial strategies may be adopted to facilitate absolute control over drug delivery, and without sacrificing the host carrier cells. We provide a comprehensive summary of the lessons we can learn from microbes in the context of drug delivery and discuss their feasibility for in vivo therapeutic application. We then describe our proposed "synthetic microbe drug delivery system" in detail. In our opinion, this multidisciplinary approach may hold the solution to effective, controlled drug delivery.

Research paper thumbnail of Caffeine Improves Triathlon Performance: A Field Study in Males and Females

International Journal of Sport Nutrition and Exercise Metabolism, May 1, 2018

The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidat... more The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidate realistically the effect of caffeine on triathlon event performance using a field study design, while allowing investigation into potential mechanisms at play. A double-blind, randomized, crossover field trial was conducted. Twenty-six triathletes (14 males and 12 females; mean ± SD: age = 37.8 ± 10.6 years, habitual caffeine intake = 413 ± 505 mg/day, percentage body fat = 14.5 ± 7.2%, and training/week = 12.8 ± 4.5 hr) participated in this study. Microencapsulated caffeine (6 mg/kg body weight) was supplemented 60 min pretrial. Performance data included time to completion, rating of perceived exertion, and profile of mood states. Blood samples taken before, during, and postrace were analyzed for cortisol, testosterone, and full blood count. Capillary blood lactate concentrations were assessed prerace, during transitions, and 3, 6, 9, 12, and 15 min after triathlons. Caffeine supplementation resulted in a 3.7% reduction in swim time (33.5 ± 7.0 vs. 34.8 ± 8.1 min, p &lt; .05) and a 1.3% reduction in time to completion (149.6 ± 19.8 vs. 151.5 ± 18.6 min, p &lt; .05) for the whole group. Gender differences and individual responses are also presented. Caffeine did not alter the rating of perceived exertion significantly, but better performance after caffeine supplementation suggests a central effect resulting in greater overall exercise intensity at the same rating of perceived exertion. Caffeine supplementation was associated with higher postexercise cortisol levels (665 ± 200 vs. 543 ± 169 nmol/L, p &lt; .0001) and facilitated greater peak blood lactate accumulation (analysis of variance main effect, p &lt; .05). We recommend that triathlon athletes with relatively low habitual caffeine intake may ingest 6 mg/kg body weight caffeine, 45-60 min before the start of Olympic-distance triathlon to improve their performance.

Research paper thumbnail of Effects of Redox Disturbances on Motility, Contractility and Muscle Tissue Pathogenesis

Oxidative Medicine and Cellular Longevity, 2019

Research paper thumbnail of Anti-inflammatory cellular targets on neutrophils elucidated using a novel cell migration model and confocal microscopy: a clinical supplementation study

Journal of Inflammation, Jan 5, 2018

Background: In vivo studies have shown grape seed-derived polyphenols (GSP) to benefit in recover... more Background: In vivo studies have shown grape seed-derived polyphenols (GSP) to benefit in recovery from muscle injury by modulation of neutrophil infiltration into damaged tissue, thereby reducing secondary damage, as well as by facilitating an early anti-inflammatory macrophage phenotype shift. The current study aimed to provide data in this context from human models and to elucidate specific molecular targets of GSP. Using a placebo-controlled, double-blind study design, eighteen normally healthy volunteers between the ages of 18-35 years old (13 female and 5 male) were orally supplemented with 140 mg/day of GSP for 2 weeks. Blood samples (days 0 and 14) were comprehensively analysed for in vitro neutrophil chemokinetic capacity towards a chemotaxin (fMLP) using a novel neutrophil migration assay, in combination with live cell tracking, as well as immunostaining for neutrophil polarisation factors (ROCK, PI3K) at migration endpoint. Macrophage phenotype marker expression was assessed using flow cytometry. Results: fMLP induced significant chemokinesis (P < 0.01), validating our model. GSP did not exert a significant effect on neutrophil chemokinesis in this non-compromised population, but tended to decrease overall ROCK expression in fMLP-stimulated neutrophils (P = 0.06). Macrophage phenotype markers CD274 and MPOindicators of a pro-inflammatory M1 phenotypeseemed to be normalised relative to baseline expression levels after GSP treatment. Conclusions: Current data suggest that GSP may have a modulatory effect on the ROCK-PI3K-PTEN system, but results in this normal population is not conclusive and should be confirmed in a larger, more inflamed population. Potential modulation of macrophage phenotype by GSP should be investigated further.

Research paper thumbnail of The potential of zebrafish as drug discovery research tool in immune-mediated inflammatory disease

Inflammopharmacology, Jun 26, 2024

Research paper thumbnail of Exposure of Cryptococcus neoformans to low nitrogen levels enhances virulence

International microbiology, Mar 14, 2024

Previous studies have shown a correlation between nitrogen levels and Cryptococcus neoformans pat... more Previous studies have shown a correlation between nitrogen levels and Cryptococcus neoformans pathogenicity. Here we report on the in vivo effects of cryptococcal pre-exposure to ecologically relevant nitrogen levels. C. neoformans H99 was cultured in yeast carbon base (YCB) supplemented with 0.53 g/L NH 4 Cl and 0.21 g/L NH 4 Cl, respectively, and used to infect larvae of the Greater Wax moth, Galleria mellonella. Cells cultured in low nitrogen YCB (LN) were more virulent compared to cells cultured in high nitrogen YCB (HN). Microscopic examination of haemolymph collected from infected larvae revealed that cells cultured in LN were larger than cells cultured in HN, with the majority of LN cells exceeding 10 µm and possibly entering titanisation. Additionally, compared to HN-cultured cells, fewer LN-cultured cells were engulfed by macrophages. The enhanced virulence of LN-cultured cells was attributed to the increased cell size in vivo. In contrast, reduced macrophage uptake was attributed to increased capsule thickness of in vitro cells. Not only do these findings demonstrate the effects of culture conditions, specifically nitrogen levels, on C. neoformans virulence, but they also highlight the importance of isolate background in the cryptococcal-host interaction.

Research paper thumbnail of Translation of preclinical ethnomedicine data in LMICs: the example of rooibos

Frontiers in Pharmacology, Dec 18, 2023

All disease, but especially non-communicable diseases, are related to dysfunction of one or more ... more All disease, but especially non-communicable diseases, are related to dysfunction of one or more regulatory systems. In developing countries, long-term management of patients with chronic diseases has many challenges and is generally not financially viable, but Africa in particular, which is rich in diverse ethnomedicines presents a more feasible long-term therapeutic approach in this niche. However, despite comprehensive preclinical investigations on numerous plant-derived candidate medicines, only a small portion of these reach the patient as recognised medicines. In this review, we use the example of rooibos (Aspalathus linearis (Burm.f.) R. Dahlgren)-which is globally consumed as aromatic, caffeine-free tea-to illustrate the hurdles that need to be overcome in the low-to middle-income countries, before progression of ethnomedicines to official treatment regimens can be achieved. In terms of methodology, regulatory system focused rooibos papers indexed on PubMed for the past three decades (n = 112) were accessed. Papers reporting duplication of previous results were excluded, as well as review papers. Topics covered includes the high standard of ethnomedicine drug discovery and efficacy testing research performed in Africa (and South Africa in particular in the case of rooibos), the potential bias in terms of preclinical research focus, ethnomedicine ownership and the requirement for independent clinical trial coordination and/or management.

Research paper thumbnail of Dolutegravir quantification in wistar rat tissues following chronic administration

Research paper thumbnail of Corrigendum: A Review: The Fate of Bacteriocins in the Human Gastro-Intestinal Tract: Do They Cross the Gut–Blood Barrier?

Frontiers in Microbiology, Nov 30, 2018

Research paper thumbnail of Sceletium tortuosum may delay chronic disease progression via alkaloid-dependent antioxidant or anti-inflammatory action

Journal of Physiology and Biochemistry, Mar 9, 2018

The link between obesity-induced systemic inflammation and decreased insulin signalling is well-k... more The link between obesity-induced systemic inflammation and decreased insulin signalling is well-known. It is also known that peripherally produced inflammatory cytokines can cross the blood-brain barrier, resulting in the release of neurotoxins that can ultimately lead to the demise of central nervous system integrity. A high-mesembrine Sceletium tortuosum extract was recently shown to possess cytoprotective and mild anti-inflammatory properties in monocytes and to target specific p450 enzymes to reduce adrenal glucocorticoid synthesis. This is significant since the aetiology of both obesity and diabetes is linked to inflammation and excess glucocorticoid production. Given the interlinked nature of glucocorticoid action and inflammation, central immunomodulatory effects of two Sceletium tortuosum extracts prepared by different extraction methods were investigated. Human astrocytes were pre-treated for 30 min, before exposure to Escherichia coli lipopolysaccharide for 23.5 h (in the presence of treatment). Cytotoxicity, mitotoxicity and cytokine responses (basally and in response to inflammatory stimulus) were assessed. In addition, total polyphenol content, antioxidant capacity and selected neural enzyme inhibition capacity were assessed for both extracts. The high-mesembrine Sceletium extract exerted cytoprotective and anti-inflammatory effects. In contrast, the high delta7-mesembrenone extract, rich in polyphenols, exhibited potent antioxidant effect, although with relatively higher risk of adverse effects with overdose. We conclude that both Sceletium tortuosum extracts may be employed as either a preventative supplement or complimentary treatment in the context of obesity and diabetes; however, current data also highlights the impact that extraction methods can have on plant product mechanism of action.

Research paper thumbnail of Gender differences in metabolic risk factor prevalence in a South African student population

Cardiovascular Journal of Africa, May 1, 2009

We determined selected risk factors for the metabolic syndrome and assessed the metabolic risk st... more We determined selected risk factors for the metabolic syndrome and assessed the metabolic risk status (using IDF criteria) of third-year physiology students at Stellenbosch University (88 males and 178 females). Outcome measures included anthropometry [body mass index (BMI), waist circumference, waist-to-hip ratio], blood pressure (BP), resting pulse rate, and fasting blood glucose, total cholesterol and triglyceride levels. In addition, students completed a lifestyle questionnaire. A number of gender-based differences were found, with male students displaying a greater incidence of risk factors for the metabolic syndrome: 6% of males versus 3% of females displayed a cluster of three risk factors. Twenty-five per cent of female students (but only 14% of males) exhibited waist circumferences above the accepted range, which was positively correlated, for males and females, with both systolic and diastolic BP, and in females only, also with total cholesterol levels. Male students on average exercised more than their female counterparts, but also exhibited poorer eating habits. Average blood triglyceride levels for both male and female students exceeded the accepted threshold (1.85 ± 1.62 mmol/l and 2.15 ± 1.79 mmol/l, respectively). We concluded that metabolic risk factors were evident in a much younger population than commonly expected. Moreover, the gender-specific differences observed may impact on future risk assessment and preventative measures adopted.

Research paper thumbnail of The effect of a professional cricket match schedule on selected immune parameters

South African Journal of Sports Medicine, Dec 20, 2004

Objective. The impact of a professional cricket match schedule on white blood cell (WBC) distribu... more Objective. The impact of a professional cricket match schedule on white blood cell (WBC) distribution and lymphocyte activation (CD69 expression) was investigated. Methods. After a 3-month pre-season training period, physical and immune parameters were determined in 14 male cricketers before (B) and after (A) an intensive 5week match schedule. Results. Exercise test results were unchanged from B to A. Total WBC counts were similar, but total lymphocyte and lymphocyte subpopulation counts decreased significantly. The CD4:CD8 ratio did not change. After in vitro stimulation, percentage CD4+CD69+ cells increased (B: 54.4 ± 9.7%, A: 64.0 ± 8.5%, p < 0.01), but absolute CD4+CD69+ cell counts did not change from B to A. In contrast, both the %CD8+CD69+ cells and absolute CD8+CD69+ cell count remained similar. A strenuous, interregional, professional cricket match schedule resulted in a decreased number of lymphocytes, but relatively increased in vitro reactivity of CD4+ cells, thus maintaining the absolute capacity of the CD4+ cells to become activated on stimulation. In cricketers who suffered upper respiratory tract symptoms during the match schedule (N = 7), none of the immune parameters investigated differed significantly from the others at B or A.

Research paper thumbnail of Exercise, stress and immune system functional responses

Chroniese oefening-verwante stres beïnvloed beide the immuun-en endokriene sisteme, maar daar is ... more Chroniese oefening-verwante stres beïnvloed beide the immuun-en endokriene sisteme, maar daar is nog baie aspekte wat swak begryp word, veral m.b.t. die effekte van stres op die funksionele kapasiteit van immuunselle. Hierdie tesis het sommige van dié vraagpunte ondersoek deur gebruik te maak van fisiologiese en psigologiese stres. Beide oefening program-verwante stres en chroniese psigologiese stres in proefpersone het 'n op-regulering van spontane witbloedselreaktiwiteit in vitro tot gevolg gehad, wat d.m.v twee verskillende metodes aangetoon is, naamlik a) 'n perifere bloed mononukluêre selkultuur (PBMS-kultuur) bepaling van immuunsel reaktiwiteit en b) 'n relatief nuwe vloeisitometriese tegniek vir die assessering van aktiveringsstatus van selle, deur hul uitdrukking van die oppervlakmerker CD69, op 'n limfosiet subpopulasie-spesifieke wyse. 'n Opregulering van immuunselaktiwiteit in die afwesigheid van 'n addisionele stressor is geassosieer met 'n verlaagde kapsiteit om te reageer op 'n latere mitogeniese prikkel in vitro, na chroniese psigologiese stres en akute, erge oefeningstres. Nog 'n nuwe bevinding was dat kortisol hoog-respondeerders, in reaksie op chroniese psigologiese stres, 'n hoër spontane reaktiwiteit van beide CD4 + -and CD8 + -limfosiete toon in vergelyking met kortisol laagresopndeerders. Hierdie bevinding toon aan dat chroniese blootstelling aan kortisol die inhiberende effek daarvan op spontane reaktiwiteit van T-limfosiete verminder. Na optimalisering van 'n rotmodel van gematigde, psigologiese stres, het ons gedemonstreer (deur gebruik te maak van 'n IL-6 teenliggaam) dat IL-6 nodig is vir 'n volledige kortisolreaksie op chroniese, onderbroke, gematigde stres. Die resultate dui daarop dat IL-6 'n rol in die regulering van sy eie sekresie deur PBMSe in reaksie tot 'n stressor speel, deur die handhawing van produksie van IL-1β in die teenwoordigheid van stres. Basale serum kortisolkonsentrasie is as die belangrikste beslissende faktor in die omvang van mitogeengestimuleerde PBMS sekresie van IL-6 in vitro in die stresvrye kontroles aangedui. Na blokkering van IL-6 in vivo, is IL-1β egter as 'n belangrike reguleerder van IL-6 sekresie deur mitogeen-gestimuleerde PBMSe in vitro geïdentifiseer, onafhanklik van die teenwoordigheid of afwesigheid van stres. Die implikasie van hierdie nuwe bevindinge is dat proinflammatoriese sitokiene tydens gematigde stres sensitief gereguleer word. Die gemiddelde serum kortisolkonsentrasie in 'n rustende toestand was nie 'n gepaste instrument om chroniese oefeningstres na 'n oefenprogram-ingreep te assesseer nie. Na basislyn klassifikasie van atlete in twee groepe volgens hul rustende serum kortisolkonsentrasie, is twee afsonderlike patrone vir die reaksie van beide kortisol en die kortisol:testosteroon verhouding egter aangetoon. Hierdie studies rakende die effekte van chroniese stres op parameters van die endokriene stres-as en die immuunsisteem het tot die volgende vernaamste gevolgtrekkings gelei: a) chroniese blootstelling aan kortisol het 'n verlaagde inhibisie van spontane immuunselaktiwiteit tydens rustende toestande tot gevolg, b) hierdie verhoogde spontane aktivering van immuunselle tydens 'n rustende toestand word geassosieer met 'n onderdrukking van immuunkapasiteit om te reageer op 'n daaropvolgende prikkel, c) laasgenoemde bevinding is nie sigbaar tydens stresvrye toestande, wanneer kortisol IL-6 sekresie bevorder, nie en d) IL-1β en IL-6 is betrokke by die regulering van mekaar se sekresie.

Research paper thumbnail of Alterations to microbial secretome by estrogen may contribute to sex bias in irritable bowel syndrome

Inflammopharmacology, Jan 13, 2022

INTRODUCTION Irritable bowel syndrome (IBS) is a female predominant functional gastrointestinal d... more INTRODUCTION Irritable bowel syndrome (IBS) is a female predominant functional gastrointestinal disorder, underpinned by microbial dysbiosis and microinflammation. We suggest that changes in trace amine (TA) load and metabolism may link together diet, inflammation and sex in this context. METHODS The effect of E2 treatment on microbial growth and TA generation was assessed using liquid chromatography and tandem mass spectrometry methodology. To investigate the effects of TAs on the gut, WST-1, prostaglandin E2 and tight junction protein dynamics were investigated in TA treated (HT-29) colon epithelial monolayer cultures. RESULTS Differential E2-dependent alterations of the TA production capabilities of microbes were observed. Significantly, E2 treatment resulted in a 50% increase in tryptamine secretion from a probiotic microbe (p < 0.0001). Moreover, in vitro experiments indicated that TA treatment exerted type-specific effects in the gut, e.g., reducing mitochondrial functionality, even at low doses of tryptamine (p < 0.0001) and ρ-tyramine (p < 0.001). Additionally, prostaglandin E2 levels were significantly increased following ρ-tyramine and agmatine treatment (p < 0.05). In terms of functionality, all investigated TAs resulted in occludin redistribution and loss of zona occludens-1 and occludin co-localization. CONCLUSION Increases in the gastrointestinal TA load may contribute to a relatively pro-inflammatory outcome in the intestine, along with tight junction protein disruption. Additionally, fluctuating levels of endogenous E2 may modulate microbially-derived TA levels, potentially explaining exaggerating gastrointestinal symptomology in females during low E2 phases. Thus, current data warrants subsequent investigations in appropriate in vivo models to fully elucidate the role of the trace aminergic system in the sex bias observed in IBS.

Research paper thumbnail of Influence of lifestyle choices on metabolic risk has distinct gender and age differences

International journal of clinical and experimental physiology, 2014

Influence of lifestyle choices on metabolic risk has distinct gender and age differences than one... more Influence of lifestyle choices on metabolic risk has distinct gender and age differences than one cardiovascular risk factor, such as elevated blood pressure (BP) or central obesity. It is known that abdominal adipose tissue releases non-esterified fatty acids into circulation, which inhibits insulin-stimulated glucose uptake and may prompt pro-inflammatory cytokine secretion. This, along with the accumulation of inflammatory macrophages in adipose tissue is associated with increased low-grade chronic inflammation, a major contributor for development of diabetes and CVD. The burden of the metabolic syndrome has become global and the condition is manifesting more in younger populations, which has huge health and economic implications. We have recently reported that in a South African student population the diagnostic risk criteria for the metabolic syndrome as defined by the International Diabetes Federation (IDF), are present in an alarmingly high percentage in younger generations. Earlier awareness of these problems can possibly help to reduce the incidence of life-style-associated diseases. This can

Research paper thumbnail of In utero Exposure to Maternal Chronic Inflammation Transfers a Pro-Inflammatory Profile to Generation F2 via Sex-Specific Mechanisms

Frontiers in Immunology, Feb 13, 2020

Generational transfer of maladaptations in offspring have been reported to persist for multiple g... more Generational transfer of maladaptations in offspring have been reported to persist for multiple generations in conditions of chronic inflammation, metabolic and psychological stress. Thus, the current study aimed to expand our understanding of the nature, potential sex specificity, and transgenerational plasticity of inflammatory maladaptations resulting from maternal chronic inflammation. Briefly, F1 and F2 generations of offspring from C57/BL/6 dams exposed to a modified maternal periconception systemic inflammation (MSPI) protocol were profiled in terms of leukocyte and splenocyte counts and cytokine responses, as well as glucocorticoid sensitivity. Overall, F1 male and female LPS groups presented with glucocorticoid hypersensitivity (with elevated corticosterone and increased leukocyte glucocorticoid receptor levels) along with a pro-inflammatory phenotype, which carried over to the F2 generation. The transfer of inflammatory and glucocorticoid responsiveness from F1 to F2 is evident, with heritability of this phenotype in F2. The findings suggest that maternal (F0) perinatal chronic inflammation resulted in glucocorticoid dysregulation and a resultant pro-inflammatory phenotype, which is transferred in the maternal lineage but seems to affect male offspring to a greater extent. Of further interest, upregulation of IL-1β cytokine responses is reported in female offspring only. The cumulative maladaptation reported in F2 offspring when both F1 parents were affected by maternal LPS exposure is suggestive of immune senescence. Given the potential impact of current results and the lack of sex-specific investigations, more research in this context is urgently required.

Research paper thumbnail of Rheumatoid cachexia: the underappreciated role of myoblast, macrophage and fibroblast interplay in the skeletal muscle niche

Journal of Biomedical Science, Mar 3, 2021

Although rheumatoid arthritis affects 1% of the global population, the role of rheumatoid cachexi... more Although rheumatoid arthritis affects 1% of the global population, the role of rheumatoid cachexia, which occurs in up to a third of patients, is relatively neglected as research focus, despite its significant contribution to decreased quality of life in patients. A better understanding of the cellular and molecular processes involved in rheumatoid cachexia, as well as its potential treatment, is dependent on elucidation of the intricate interactions of the cells involved, such as myoblasts, fibroblasts and macrophages. Persistent RA-associated inflammation results in a relative depletion of the capacity for regeneration and repair in the satellite cell niche. The repair that does proceed is suboptimal due to dysregulated communication from the other cellular role players in this multi-cellular environment. This includes the incomplete switch in macrophage phenotype resulting in a lingering pro-inflammatory state within the tissues, as well as fibroblast-associated dysregulation of the dynamic control of the extracellular matrix. Additional to this endogenous dysregulation, some treatment strategies for RA may exacerbate muscle wasting and no multi-cell investigation has been done in this context. This review summarizes the most recent literature characterising clinical RA cachexia and links these features to the roles of and complex communication between multiple cellular contributors in the muscle niche, highlighting the importance of a targeted approach to therapeutic intervention.

Research paper thumbnail of Sutherlandia frutescens may exacerbate HIV-associated neuroinflammation

Journal of Negative Results in Biomedicine, Jul 18, 2015

Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disord... more Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disorders (HAND) that are prevalent in late stage AIDS. Anti-retroviral (ARV) treatments are rolled out relatively late in the context of neuroinflammatory changes, so that their usefulness in directly preventing HAND is probably limited. It is common practice for HIV+ individuals in developing countries to make use of traditional medicines. One such medicine is Sutherlandia frutescens -commonly consumed as a water infusion. Here its efficacy as an anti-inflammatory modality in this context was investigated in an in vitro co-culture model of the blood-brain barrier (BBB). Methods: Single cultures of human astrocytes (HA), HUVECs and primary human monocytes, as well as co-cultures (BBB), were stimulated with HIV-1 subtype B & C Tat protein and/or HL2/3 cell secretory proteins after pre-treatment with S.frutescens extract. Effects of this pre-treatment on pro-inflammatory cytokine secretion and monocyte migration across the BBB were assessed. Results: In accordance with others, B Tat was more pro-inflammatory than C Tat, validating our model. S.frutescens decreased IL-1β secretion significantly (P < 0.0001), but exacerbated both monocyte chemoattractant protein-1 (P < 0001)a major role player in HIV-associated neuroinflammationand CD14+ monocyte infiltration across the BBB (P < 0.01). Conclusions: Current data illustrates that the combined use of HL2/3 cells and the simulated BBB presents an accurate, physiologically relevant in vitro model with which to study neuroinflammation in the context of HIV/AIDS. In addition, our results caution against the use of S.frutescens as anti-inflammatory modality at any stage post-HIV infection.

Research paper thumbnail of Natural antioxidants in prevention of accelerated ageing: a departure from conventional paradigms required

Journal of Physiology and Biochemistry, Mar 14, 2018

The modern lifestyle is characterised by various factors that cause accelerating ageing by the up... more The modern lifestyle is characterised by various factors that cause accelerating ageing by the upregulation of oxidative stress and inflammation-two processes that are inextricably linked in an endless circle of self-propagation. Inflammation in particular is commonly accepted as aetiological factor in many chronic disease states, such as obesity, diabetes and depression. In terms of disease prevention or treatment, interventions aimed at changing dietary and/or exercise habits have had limited success in practise, mostly due to poor long-term compliance. Furthermore, other primary stimuli responsible for eliciting an oxidative stress or inflammatory response-e.g. psychological stress and anxiety-cannot always be easily addressed. Thus, preventive medicine aimed at countering the oxidative stress and/or inflammatory responses has become of interest. Especially in developing countries, such as South Africa, the option of development of effective strategies from plants warrants further investigation. A brief overview of the most relevant and promising South African plants which have been identified in the context of inflammation, oxidative stress and chronic disease is provided here. In addition, and more specifically, our group and others have shown considerable beneficial effects across many models, after treatment with products derived from grapes. Of particular interest, specific cellular mechanisms have been identified as therapeutic targets of grape-derived polyphenols in the context of inflammation and oxidative stress. The depth of these studies afforded some additional insights, related to methodological considerations pertaining to animal vs. human models in natural product research, which may address the current tendency for generally poor translation of positive animal model results into human in vivo models. The importance of considering individual data vs. group averages in this context is highlighted.

Research paper thumbnail of Polyphenol-associated oxidative stress and inflammation in a model of LPS-induced inflammation in glial cells: do we know enough for responsible compounding?

Inflammopharmacology, Dec 13, 2018

Cyanidin and chlorogenic acid are polyphenols from plant origin that are present in many common f... more Cyanidin and chlorogenic acid are polyphenols from plant origin that are present in many common fruits, particularly in berries. To corroborate the protective or detrimental effects of both compounds from a neuro-inflammatory perspective, in vitro experiments were carried out in human astrocytes (U-373). Astrocytes were pre-treated with a range of concentrations of either cyanidin, chlorogenic acid or a combined treatment for a period of 30 min, before exposure to Escherichia coli lipopolysaccharide (LPS) challenge for 23.5 h, after which cytotoxicity (propidium iodide exclusion assay), cytoprotective effects (XTT assay) and effects on functional capacity (secretion of pro-inflammatory cytokines IL-6 and MCP-1) were evaluated. No treatment resulted in cytotoxicity, but high dose (20 µg/mL) LPS significantly reduced mitochondrial reductive capacity (p < 0.001). This effect was prevented in a dose-dependent manner by both cyanidin and chlorogenic acid, as well as by the combination treatment. However, in the absence of LPS, IL-6 secretion was significantly increased in response to 2 µM of either cyanidin or chlorogenic acid (both p < 0.0001), as well as the combination treatment (p < 0.01). MCP-1 secretion followed a similar trend, but did not reach statistical significance. Although we acknowledge the requirement for in vivo investigations to validate our interpretations, current data highlight the potential risk for antioxidant toxicity that is linked to high dose supplementation with single compound antioxidants. Research focused at elucidating synergistic effects between different antioxidants is required to minimise risk of adverse effects.

Research paper thumbnail of Harnessing Macrophages for Controlled-Release Drug Delivery: Lessons From Microbes

Frontiers in Pharmacology, Jan 25, 2019

With the effectiveness of therapeutic agents ever decreasing and the increased incidence of multi... more With the effectiveness of therapeutic agents ever decreasing and the increased incidence of multi-drug resistant pathogens, there is a clear need for administration of more potent, potentially more toxic, drugs. Alternatively, biopharmaceuticals may hold potential but require specialized protection from premature in vivo degradation. Thus, a paralleled need for specialized drug delivery systems has arisen. Although cell-mediated drug delivery is not a completely novel concept, the few applications described to date are not yet ready for in vivo application, for various reasons such as drug-induced carrier cell death, limited control over the site and timing of drug release and/or drug degradation by the host immune system. Here, we present our hypothesis for a new drug delivery system, which aims to negate these limitations. We propose transport of nanoparticle-encapsulated drugs inside autologous macrophages polarized to M1 phenotype for high mobility and treated to induce transient phagosome maturation arrest. In addition, we propose a significant shift of existing paradigms in the study of host-microbe interactions, in order to study microbial host immune evasion and dissemination patterns for their therapeutic utilization in the context of drug delivery. We describe a system in which microbial strategies may be adopted to facilitate absolute control over drug delivery, and without sacrificing the host carrier cells. We provide a comprehensive summary of the lessons we can learn from microbes in the context of drug delivery and discuss their feasibility for in vivo therapeutic application. We then describe our proposed "synthetic microbe drug delivery system" in detail. In our opinion, this multidisciplinary approach may hold the solution to effective, controlled drug delivery.

Research paper thumbnail of Caffeine Improves Triathlon Performance: A Field Study in Males and Females

International Journal of Sport Nutrition and Exercise Metabolism, May 1, 2018

The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidat... more The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidate realistically the effect of caffeine on triathlon event performance using a field study design, while allowing investigation into potential mechanisms at play. A double-blind, randomized, crossover field trial was conducted. Twenty-six triathletes (14 males and 12 females; mean ± SD: age = 37.8 ± 10.6 years, habitual caffeine intake = 413 ± 505 mg/day, percentage body fat = 14.5 ± 7.2%, and training/week = 12.8 ± 4.5 hr) participated in this study. Microencapsulated caffeine (6 mg/kg body weight) was supplemented 60 min pretrial. Performance data included time to completion, rating of perceived exertion, and profile of mood states. Blood samples taken before, during, and postrace were analyzed for cortisol, testosterone, and full blood count. Capillary blood lactate concentrations were assessed prerace, during transitions, and 3, 6, 9, 12, and 15 min after triathlons. Caffeine supplementation resulted in a 3.7% reduction in swim time (33.5 ± 7.0 vs. 34.8 ± 8.1 min, p &lt; .05) and a 1.3% reduction in time to completion (149.6 ± 19.8 vs. 151.5 ± 18.6 min, p &lt; .05) for the whole group. Gender differences and individual responses are also presented. Caffeine did not alter the rating of perceived exertion significantly, but better performance after caffeine supplementation suggests a central effect resulting in greater overall exercise intensity at the same rating of perceived exertion. Caffeine supplementation was associated with higher postexercise cortisol levels (665 ± 200 vs. 543 ± 169 nmol/L, p &lt; .0001) and facilitated greater peak blood lactate accumulation (analysis of variance main effect, p &lt; .05). We recommend that triathlon athletes with relatively low habitual caffeine intake may ingest 6 mg/kg body weight caffeine, 45-60 min before the start of Olympic-distance triathlon to improve their performance.

Research paper thumbnail of Effects of Redox Disturbances on Motility, Contractility and Muscle Tissue Pathogenesis

Oxidative Medicine and Cellular Longevity, 2019

Research paper thumbnail of Anti-inflammatory cellular targets on neutrophils elucidated using a novel cell migration model and confocal microscopy: a clinical supplementation study

Journal of Inflammation, Jan 5, 2018

Background: In vivo studies have shown grape seed-derived polyphenols (GSP) to benefit in recover... more Background: In vivo studies have shown grape seed-derived polyphenols (GSP) to benefit in recovery from muscle injury by modulation of neutrophil infiltration into damaged tissue, thereby reducing secondary damage, as well as by facilitating an early anti-inflammatory macrophage phenotype shift. The current study aimed to provide data in this context from human models and to elucidate specific molecular targets of GSP. Using a placebo-controlled, double-blind study design, eighteen normally healthy volunteers between the ages of 18-35 years old (13 female and 5 male) were orally supplemented with 140 mg/day of GSP for 2 weeks. Blood samples (days 0 and 14) were comprehensively analysed for in vitro neutrophil chemokinetic capacity towards a chemotaxin (fMLP) using a novel neutrophil migration assay, in combination with live cell tracking, as well as immunostaining for neutrophil polarisation factors (ROCK, PI3K) at migration endpoint. Macrophage phenotype marker expression was assessed using flow cytometry. Results: fMLP induced significant chemokinesis (P < 0.01), validating our model. GSP did not exert a significant effect on neutrophil chemokinesis in this non-compromised population, but tended to decrease overall ROCK expression in fMLP-stimulated neutrophils (P = 0.06). Macrophage phenotype markers CD274 and MPOindicators of a pro-inflammatory M1 phenotypeseemed to be normalised relative to baseline expression levels after GSP treatment. Conclusions: Current data suggest that GSP may have a modulatory effect on the ROCK-PI3K-PTEN system, but results in this normal population is not conclusive and should be confirmed in a larger, more inflamed population. Potential modulation of macrophage phenotype by GSP should be investigated further.