David Lappin | University of Glasgow (original) (raw)

Papers by David Lappin

PubMed, Nov 1, 1983

Anaphylatoxins C5a and C3a and their des Arg derivatives inhibited C2 production by mononuclear p... more Anaphylatoxins C5a and C3a and their des Arg derivatives inhibited C2 production by mononuclear phagocytes. C5a and C5adesArg which were approximately equipotent (IC50 = 10(-10) mol/l) were more effective than C3a (IC50 = 5 X 10(-8) mol/l) which was approximately 10-20-fold more potent than C3adesArg IC50 = 5 X 10(-6) mol/l). Inhibition of C2 production was only reversed slightly by the addition of either indomethacin or ETYA to the cultures. Intracellular levels of cAMP, were increased by anaphylatoxins. The level of cAMP showed a good inverse correlation with C2 levels in the culture supernatants. The data suggest that the reduction in C2 production produced by anaphylatoxins may be mediated by an increase in intracellular cAMP.

Animal, Feb 1, 2021

The work presented in this pilot study aimed to identify potential risk factors associated with b... more The work presented in this pilot study aimed to identify potential risk factors associated with bovine periodontitis development. Bovine periodontitis is a multifactorial polymicrobial infectious disease for which the aetiopathogenesis and risk factors are not fully understood. From cattle slaughtered in an abattoir in Scotland, 35 dental arcades with periodontal lesions and 40 periodontally healthy arcades were selected over seven visits for study. Multivariable logistic regression analysis was used to evaluate the association between periodontitis and the independent variables, gender, age and breed. For every increase in year of age, cattle were 1.5 times more likely to have periodontitis. A graphical analysis indicated that within the limits of this study, we could not detect any major influence of breed on the age-effect. Although logistic regression analysis demonstrated that periodontitis lesions are more prevalent with increasing age of cattle the underlying mechanisms remain unclear. It is likely that periodontitis is an important cause of oral pain in older cattle and can contribute to reduced productivity/performance. Further studies with a larger sample size are necessary to elucidate the associations between potential risk factors and periodontitis in cattle and to define its effects on animal welfare and productivity.

PubMed, Apr 1, 1989

Culture supernatants from mitogen- and antigen-stimulated human peripheral blood lymphocytes (PBL... more Culture supernatants from mitogen- and antigen-stimulated human peripheral blood lymphocytes (PBL), stimulated synthesis of the second complement component (C2) by human monocytes, but not as effectively as the stimulated PBL themselves, which adhered to the monocytes and caused marked spreading. In contrast to PBL, lymphocytes isolated from the synovial membranes (SML) of patients with rheumatoid arthritis and their culture supernatants were able to stimulate C2 synthesis without exposure to mitogens or antigens. Depletion of B and T populations showed that T cells were responsible for stimulation of C2 synthesis. Further studies of synthesis rates of C2, C3 factor B (B), C1 inhibitor, and properdin (P) were undertaken, and it was found that lymphocytes and their supernatants increased synthesis of C2, B and C1 inhibitor, and reduced synthesis of C3 and P. This profile of activity was identical to that produced by the addition of recombinant gamma-interferon (rIFN-gamma) to the cultures. Furthermore the addition of a monoclonal antibody to rIFN-gamma to cultures abrogated the effects of rIFN-gamma, and almost completely reversed the effects of lymphocytes and their supernatants. Thus it appears that gamma-interferon is the lymphocyte product which is responsible for the modulation of monocyte complement synthesis. The results of studies with synovial membrane lymphocytes raise the possibility that this process occurs in vivo. Monocyte C2 had a higher specific functional activity (SpFA) than serum C2 isolated from serum or C2 produced by HepG2 cells. Monocyte C2 formed a C3 convertase which had a longer half-life than that found with both serum C2 or HepG2 C2. Thus monocyte C2 behaves like oxidized C2. Monocytes exposed to rIFN-gamma, lymphocytes or lymphocyte-conditioned medium (LCM) produced C2 which had an even higher SpFA. Although antibody to IFN-gamma prevented any increase in C2 synthesis in monocyte cultures containing lymphocytes or LCM, C2 SpFA was still increased. Thus a second lymphocyte product is responsible for this 'oxidation' effect. This production of 'oxidized' C2 by monocytes and further 'oxidation' by the action of either lymphocytes or gamma-interferon might play a significant role in the perpetuation of complement activation at sites of inflammation.

Veterinary Record, Dec 1, 2016

PubMed, Jul 1, 1986

The synthesis of C3, C2, factor B (B) C1-inhibitor and lysozyme has been studied in monocytes and... more The synthesis of C3, C2, factor B (B) C1-inhibitor and lysozyme has been studied in monocytes and macrophages isolated from the synovial fluids of patients with rheumatoid arthritis. Concentrations of all 5 proteins in culture supernatants were measured by the sandwich ELISA technique. Kinetic studies showed that only lysozyme and C3 could be detected in monocyte culture supernatants on the first day of culture, whereas C2, B and C1-inhibitor were not present until the third day. In contrast all 5 proteins could be detected in the supernatants of macrophage cultures on day 1. In both monocyte and macrophage cultures synthesis of lysozyme and C1-inhibitor continued throughout the culture period, whereas synthesis of C2, B and C3 appeared to be reduced after the fifth day in culture. Quantitative studies showed that the secretion rates of lysozyme (4,700 X 10(3) molecules/cell/hr) was similar in monocytes and macrophages. Synthesis rates for all 4 complement components in monocyte cultures were less than 0.2% of that for lysozyme. Although the synthetic rates were higher in macrophages, even then they constituted less than 2% of the rate for lysozyme. Synthetic rates for complement components, but not lysozyme, were increased by BSA-anti-BSA antigen-antibody complexes and reduced by serum-treated complexes. Although the functional activity of monocyte B was similar to that for serum, the activity of monocyte C2 was 5 times that of serum C2. As C42 formed with monocyte C2 had a half-life of 13.5 min at 30 degrees C, compared with 4.5 min for the enzyme formed with serum C2, it is probable that monocyte C2 is oxidized by the oxygen products of these cells.

PubMed, Sep 1, 1982

The addition of prostaglandins E2 (PGE2), PGD2, PGI2, 6-keto PGF1 alpha and thromboxane B2 (TXB2)... more The addition of prostaglandins E2 (PGE2), PGD2, PGI2, 6-keto PGF1 alpha and thromboxane B2 (TXB2) to human monocyte cultures, inhibited the production of the second component of complement (C2). PGF2 alpha did not significantly affect C2 production. As the former compounds, but not the latter increase intracellular cAMP, it was thought that the effect was mediated by this action. The addition of cyclo-oxygenase and lipoxygenase inhibitors to monocyte cultures enhanced the synthesis of complement components and other proteins in a dose-dependent fashion: cyclo-oxygenase inhibitors being more potent in this regard than lipoxygenase inhibitors. The enhancing effect of cyclo-oxygenase inhibitors paralleled their ability to inhibit cyclo-oxygenase activity. The enhancement of C2 synthesis by the addition of cyclo-oxygenase and lipoxygenase inhibitors was reversed by the addition of PGs to the cultures. It is concluded that the production of PG by monocytes could provide an endogenous mechanism to control the synthesis of complement components and other proteins.

PubMed, Sep 1, 1980

Histamine produced dose-dependent inhibition of the production of the second complement component... more Histamine produced dose-dependent inhibition of the production of the second complement component (C2) by monocytes in tissue culture. The effect was not associated with either cell death, as ascertained by trypan blue exclusion, or loss of cells from the monolayer, as determined by measuring their DNA content. The specificity of the response was shown by the failure of histidine or histamine metabolites to inhibit C2 production. Preincubation of histamine with histaminase also abrogated the histamine effect. The kinetics of the effect were extremely rapid and irreversible, most of the reduction being achieved during a 5-min exposure to histamine. The H2 receptor antagonist cimetidine was able to prevent the histamine response, whereas chlorpheniramine, the H1 receptor antagonist, had no effect. Dimaprit and 4-methyl histamine, H2 receptor agonists, simulated the effect of histamine whereas the H1 receptor agonist 2-(2-aminoethylthiazole) was ineffective, confirming that the effect of histamine on C2 production by monocytes is mediated by the H2 receptors. Thus histamine, released from basophils or mast cells by the C3 and C5 cleavage products C3a and C5a respectively, may exert a negative feedback on further C3 and C5 cleavage by limiting the formation of the C3 (C42) and C5 (C423b) convertases.

PubMed, Aug 1, 1984

Adenosine inhibits C2 production by human monocytes. The use of synthetic analogues of adenosine ... more Adenosine inhibits C2 production by human monocytes. The use of synthetic analogues of adenosine suggested that the action was mediated by receptors of A2 type. EHNA which inhibits the enzyme adenosine deaminase and increases the concentration of intracellular adenosine also reduces C2 production. It is therefore possible that endogenous adenosine regulates C2 synthesis.

PubMed, Mar 1, 1982

The addition of adrenaline, noradrenaline or phenylephrine, but not isoprenaline to monocyte cult... more The addition of adrenaline, noradrenaline or phenylephrine, but not isoprenaline to monocyte cultures enhanced synthesis of the second complement component (C2). This effect was abrogated by the concomitant addition of the receptor antagonist, phentolamine, but not the beta receptor antagonist propranolol. Thus the receptor involved is an alpha adrenergic receptor. Further studies showed that the receptor was of the alpha 1 subclass as prazosin inhibited the action of adrenergic agonists. Pulse label studies using 3H-amino acids showed that the enhancement of synthesis of eight complement components (C2, C3, C4, C5, factor B, properdin, beta 1H and C3b inactivator) and total protein synthesis were also increased. The possible mechanisms underlying these changes are discussed.

Journal of Periodontology, Aug 1, 2017

Aim: This cross-sectional study assessed cytokine levels in peri-implant crevicular fluid (PICF)/... more Aim: This cross-sectional study assessed cytokine levels in peri-implant crevicular fluid (PICF)/ gingival crevicular fluid (GCF) and a selection of subgingival/submucosal plaque bacteria from clinically healthy or diseased sites in the same individuals. Material and Methods: Samples from 97 implants/teeth (58 implants: 19 healthy, 20 mucositis, 19 periimplantitis; 39 natural teeth: 19 healthy, 12 gingivitis, 8 periodontitis) in 15 systemically healthy patients were investigated by immunoassay, real-time PCR. Samples were obtained first and then probing depth, clinical attachment level, bleeding on probing, plaque index scores, keratinized tissue width were recorded. Data were analyzed by Wilcoxon, Mann-Whitney and permutation tests on dependent, independent, mixed dependent and independent samples and Spearman correlation. Results: Interleukin-1beta levels were significantly higher in PICF samples of healthy implants than in GCF samples of healthy teeth (p=0.003), soluble activator of nuclear factor Kappa-B (sRANKL) concentrations were significantly higher in gingivitis than mucositis group (p=0.004). The biomarker levels were similar in periimplantitis and periodontitis groups (p>0.05). Actinomyces naeslundi and Streptococcus oralis levels were significantly higher in healthy implant group than healthy teeth (p<0.05). Prevotella intermedia and Treponema denticola levels were lower in mucositis group than in gingivitis group (p<0.05). Prevotella oralis and S. oralis levels were significantly higher in the periodontitis group (p<0.05) and T. denticola levels were significantly higher in the peri-implantitis group (p<0.05). There were many similarities but crucially some differences in biomarker levels (IL-1β and sRANKL) and bacterial species between peri-implant and periodontal sites in the same individuals suggesting similar pathogenic mechanisms.

Journal of Periodontal Research, Jun 22, 2016

Background and Objective: Different bacteria differentially stimulate epithelial cells. Biofilm c... more Background and Objective: Different bacteria differentially stimulate epithelial cells. Biofilm composition and viability are likely to influence the epithelial response. In vitro model systems are commonly used to investigate periodontitisassociated bacteria and their interactions with the host; therefore, understanding factors that influence biofilm-cell interactions is essential. The present study aimed to develop in vitro monospecies and multispecies biofilms and investigate the epithelial response to these biofilms. Material and Methods: Bacterial biofilms were cultured in vitro and then either live or methanol-fixed biofilms were co-cultured with epithelial cells. Changes in epithelial cell viability, gene expression and cytokine content of culture supernatants were evaluated. Results: Bacterial viability was better preserved within mixed-species biofilm culture than within single-species biofilm culture. Both mixed-and single-species biofilms stimulated increased expression of mRNA for interleukin 8 (IL8), C-X-C motif chemokine ligand 3 (CXCL3), C-X-C motif chemokine ligand 1 (CXCL1), interleukin 1 (IL1), interleukin 6 (IL6), colony-stimulating factor 2 (CSF2) and tumour necrosis factor (TNF), and the response was greatest in response to mixed-species biofilms. Following co-culture, cytokines detected in the supernatants included IL-8, IL-6, granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, with the greatest release of cytokines found following co-culture with methanol-fixed, mixed-species biofilms. Conclusions: These data show that epithelial cells generate a distinct cytokine gene-and protein-expression signature in response to live or fixed, single-or multispecies biofilms.

Journal of Cystic Fibrosis, Jun 1, 2011

PubMed, Feb 1, 1983

Antigen-antibody complexes enhanced the synthesis of C2 and factor B by human monocytes and macro... more Antigen-antibody complexes enhanced the synthesis of C2 and factor B by human monocytes and macrophages, and C2 by guinea-pig macrophages. In contrast complexes that had been treated with serum inhibited the production of these components. The inhibitory effect of serum-treated complexes was abrogated by Fab fragments of anti-C3, anti-C3c and anti-C3d. It is therefore probable that inhibition was mediated by a C3 fragment bound to the complex. The enhancing effect of untreated complexes was reversible by serum-treated complexes, and the inhibitory action of serum-treated complexes was counteracted by untreated complexes. Such a system may be important in the regulation of the synthesis of complement components in response to local requirements.

PubMed, Jul 1, 1983

Heat or alkali-aggregated IgG was found to inhibit C2 production by monocytes, whereas chemically... more Heat or alkali-aggregated IgG was found to inhibit C2 production by monocytes, whereas chemically cross-linked IgG and antigen-antibody complexes stimulated C2 synthesis. Chemically cross-linked IgG was shown to inhibit monocyte EA-rosette formation presumably because it blocked monocyte Fc receptors. Furthermore stimulation of C2 synthesis was limited to polymers of the IgG1 and IgG3 subclasses. In contrast, heat-aggregated IgG failed to inhibit monocyte EA-rosette formation significantly, and all the heat-aggregated IgG subclasses inhibited C2 production. It therefore appears that physically aggregated IgG does not bind effectively to Fc receptors. As the effects of physically aggregated IgG C2 production are similar to those of the hydrophobic proteins casein and alkali-denatured human serum albumin (HSA), it is suggested that hydrophobic residues in the aggregates bind preferentially to the lipid component of the cell membrane.

Research in Veterinary Science, Dec 1, 2022

Journal of Periodontal Research, Apr 23, 2018

Aim: Determine the presence of mesenchymal stem cells (MSCs) in healthy periodontal tissue and pe... more Aim: Determine the presence of mesenchymal stem cells (MSCs) in healthy periodontal tissue and periodontal granulation tissue (GT) and explore associations between immunoregulatory molecules and select subgingival microorganisms. Methods: Mesenchymal stem cells were isolated, propagated and characterised by flow cytometry from a region of healthy gingival tissue and inflamed GT of 10 systemically healthy non-smokers with chronic periodontitis. Tissue levels of immunoregulatory molecules were determined by qPCR and Gingival Crevicular Fluid (GCF) levels by ELISA. Results: Cells with MSC-properties were isolated from both inflamed GT and healthy gingival (G) tissue. A pro-inflammatory process predominated in GT which was partly reflected in GCF and putative periodontal pathogens were higher at diseased sites. However, there was no significant difference in surface levels of mesenchymal (CD90, CD73, CD146, CD271, STRO-1), endothelial (CD105, CD106), hematopoietic (CD34, CD45) and embryonic (SSEA-4) stem cell markers between MSCs isolated from GT and G tissue. Discussion: Periodontal lesions, albeit inflamed, retain healing potential as inferred by the presence of MSC-like cells with similar immunophenotypic characteristics to those found in healthy periodontal tissue. Therefore, there might be merits for healing in preserving sufficient GT in-situ during periodontal surgery.

Inflammation Research, Dec 12, 2014

In the original publication, the first author's name was incorrectly published as Raja Azman. The... more In the original publication, the first author's name was incorrectly published as Raja Azman. The correct name should read as Raja Azman Awang.

Biochemical Journal, Jun 1, 1990

Interferons-a, -,8 and -y (IFNs -a, -fl and -y) stimulated the synthesis of the second complement... more Interferons-a, -,8 and -y (IFNs -a, -fl and -y) stimulated the synthesis of the second complement component (C2), Factor B (B) and Cl inhibitor (Cl-inh) by human monocytes in vitro. The degree of increase of the secretion rates of C2, B and Cl-inh was dose-dependent and proportional to increases in the abundances of their respective mRNAs. IFN-y was the most effective at stimulating monocyte Cl-inh synthesis, whereas IFN-ax and IFN-,f were marginally more effective at stimulating monocyte C2 and B synthesis. Kinetic studies showed that the effect of the IFNs was rapid, with maximum stimulation occurring within 1-2 h for all three proteins. After the removal of IFNs from cultures the Cl-inh mRNA abundance remained elevated for over 24 h in IFN-y-treated monocytes but returned to control levels within 8 h in IFNa-treated and IFN-fl-treated monocytes. The abundances of C2 mRNA and B mRNA also returned to basal values within 8 h after removal of any of the three cytokines from the cultures. Both IFN-a and IFN-,f acted synergistically with IFN- y to stimulate synthesis of C1-inh and B. This synergistic effect only occurred when the cytokines were present in the cultures simultaneously. The effects of IFN-y plus IFN-a or IFN-,f on C2 synthesis appeared to be additive rather than synergistic. IFN-y inhibited synthesis of C3 by monocytes, but IFN-a and IFN-fl had no effect on the synthesis of this protein. Furthermore, none of the three cytokines had any effect on the expression of actin mRNA in monocytes. 1.0 x 105 IRU/mg) and fibroblast interferon (IFN-fl; lot no. Abbreviations used: the nomenclature of complement components is that recommended by the World Health Organisation (1968, 1981); Cl-inh, Cl inhibitor; C2, second component of complement; C3, third component of complement; B, Factor B; IFN-a, lymphoblastoid interferon-a; IFN- ,B, fibroblast interferon-,8; IFN-y, recombinant interferon-y; ABS, human AB serum heat-inactivated for 2 h at 56 °C; RPMI, RPMI 1640/Hepes buffer; FCS, foetal-calf serum heat-inactivated for 2 h at 56 °C; RPMI/ABS, RPMI 1640 containing 10% (v/v) heat-inactivated human AB serum; RPMI/FCS, RPMI 1640 containing 20 % (v/v) heat-inactivated foetal-calf serum. t To whom correspondence should be addressed.

Biochemical Journal, Sep 1, 1984

The time courses of changes in cyclic nucleotide levels in monocytes have been studied. Histamine... more The time courses of changes in cyclic nucleotide levels in monocytes have been studied. Histamine and prostaglandin E2 (PGE2) produced a rapid rise in cyclic AMP (peak 15min) levels, which returned to normal within 4h, whereas cholera toxin, NaF and phosphodiesterase inhibitors produced slow sustained rises lasting over 24 h. With the exception of isobutylmethylxanthine (1O Mmolh1), none of these reagents altered cyclic GMP levels. oa -Adrenergic and nicotinic cholinergic receptor-ligand interactions and imidazole produced rapid and relatively short-lived falls in cyclic AMP, and rises in cyclic GMP. In contrast, prostaglandin synthetase inhibitors produced delayed but more sustained falls in cyclic AMP but no rises in cyclic GMP. Agents that increased cyclic AMP decreased complement-component- C2 production, and those that decreased cyclic AMP increased C2 production. Agents that increased cyclic GMP alone (ascorbate, nitroprusside and prostaglandin F2a) did not affect C2 production. Antigen-antibody complexes that stimulate C2 synthesis produced falls in cyclic AMP and rises in cyclic GMP similar to those produced by adrenergic and cholinergic ligands. Serum-treated complexes and anaphylatoxins, which inhibited C2 production, were associated with changes in cyclic AMP similar to those produced by histamine and PGE2. These data suggest that there are two transmembrane signals involved in the regulation of C2 production by monocytes. The inhibitory signal is adenylyl cyclase activation. The stimulatory signal is not so obvious, but may be Ca2 + influx, since the time courses of changes in cyclic nucleotides produced by agents that stimulate C2 synthesis are identical, and a, -adrenergic agonists cause the formation of Ca2 + channels.