The Potential Impact of Selected Bacterial Strains on the Stress Response (original) (raw)
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Biological, environmental, and psychological stress and the human gut microbiome in healthy adults
Scientific Reports, 2025
Emerging research suggests that the gut microbiome plays a crucial role in stress. We assess stress microbiome associations in two samples of healthy adults across three stress domains (perceived stress, stressful life events, and biological stress /Respiratory Sinus Arrhythmia; RSA). Study 1 (n = 62; mean-age = 37.3 years; 68% female) and Study 2 (n = 74; mean-age = 41.6 years; female only) measured RSA during laboratory stressors and used 16S rRNA pyrosequencing to classify gut microbial composition from fecal samples. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States was used to predict functional pathways of metagenomes. Results showed differences in beta diversity between high and low stressful life events groups across both studies. Study 1 revealed differences in beta diversity between high and low RSA groups. In Study 1, the low perceived stress group was higher in alpha diversity than the high perceived stress group. Levels of Clostridium were negatively associated with RSA in Study 1 and levels Escherichia/Shigella were positively associated with perceived stress in Study 2. Associations between microbial functional pathways (L-lysine production and formaldehyde absorption) and RSA are discussed. Findings suggest that certain features of the gut microbiome are differentially associated with each stress domain.
Stress and the gut microbiota-brain axis
Behavioural Pharmacology, 2019
Stress is a nonspecific response of the body to any demand imposed upon it, disrupting the body homoeostasis and manifested with symptoms such as anxiety, depression or even headache. These responses are quite frequent in the present competitive world. The aim of this review is to explore the effect of stress on gut microbiota. First, we summarize evidence of where the microbiota composition has changed as a response to a stressful situation, and thereby the effect of the stress response. Likewise, we review different interventions that can modulate microbiota and could modulate the stress according to the underlying mechanisms whereby the gut–brain axis influences stress. Finally, we review both preclinical and clinical studies that provide evidence of the effect of gut modulation on stress. In conclusion, the influence of stress on gut microbiota and gut microbiota on stress modulation is clear for different stressors, but although the preclinical evidence is so extensive, the cli...
Handling stress may confound murine gut microbiota studies
PeerJ, 2017
Accumulating evidence indicates interactions between human milk composition, particularly sugars (human milk oligosaccharides or HMO), the gut microbiota of human infants, and behavioral effects. Some HMO secreted in human milk are unable to be endogenously digested by the human infant but are able to be metabolized by certain species of gut microbiota, including Bifidobacterium longum subsp. infantis (B. infantis), a species sensitive to host stress (Bailey & Coe, 2004). Exposure to gut bacteria like B. infantisduring critical neurodevelopment windows in early life appears to have behavioral consequences; however, environmental, physical, and social stress during this period can also have behavioral and microbial consequences. While rodent models are a useful method for determining causal relationships between HMO, gut microbiota, and behavior, murine studies of gut microbiota usually employ oral gavage, a technique stressful to the mouse. Our aim was to develop a less-invasive tec...
The Role of Microbiota and Probiotics in Stress-Induced Gastrointestinal Damage
Current Molecular Medicine, 2008
Stress has a major impact on gut physiology and may affect the clinical course of gastro-intestinal diseases. In this review, we focus on the interaction between commensal gut microbiota and intestinal mucosa during stress and discuss the possibilities to counteract the deleterious effects of stress with probiotics. Normally, commensal microbes and their hosts benefit from a symbiotic relationship. Stress does, however, reduce the number of Lactobacilli, while on the contrary, an increased growth, epithelial adherence and mucosal uptake of gram-negative pathogens, e.g. E. coli and Pseudomonas, are seen. Moreover, intestinal bacteria have the ability to sense a stressed host and up-regulate their virulence factors when opportunity knocks. Probiotics are "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host", and mainly represented by Lactic Acid Bacteria. Probiotics can counteract stress-induced changes in intestinal barrier function, visceral sensitivity and gut motility. These effects are strain specific and mediated by direct bacterial-host cell interaction and/or via soluble factors. Mechanisms of action include competition with pathogens for essential nutrients, induction of epithelial heat-shock proteins, restoring of tight junction protein structure, up-regulation of mucin genes, secretion of defensins, and regulation of the NF B signalling pathway. In addition, the reduction of intestinal pain perception was shown to be mediated via cannabinoid receptors. Based on the studies reviewed here there is clearly a rationale for probiotic treatment in patients with stressrelated intestinal disorders. We are however far from being able to choose the precise combination of strains or bacterial components for each clinical setting.
Molecular Psychiatry
The impact of diet on the microbiota composition and the role of diet in supporting optimal mental health have received much attention in the last decade. However, whether whole dietary approaches can exert psychobiotic effects is largely understudied. Thus, we investigated the influence of a psychobiotic diet (high in prebiotic and fermented foods) on the microbial profile and function as well as on mental health outcomes in a healthy human population. Forty-five adults were randomized into either a psychobiotic (n = 24) or control (n = 21) diet for 4 weeks. Fecal microbiota composition and function was characterized using shotgun sequencing. Stress, overall health and diet were assessed using validated questionnaires. Metabolic profiling of plasma, urine and fecal samples was performed. Intervention with a psychobiotic diet resulted in reductions of perceived stress (32% in diet vs. 17% in control group), but not between groups. Similarly, biological marker of stress were not affe...
The Microbiome as a Novel Paradigm in Studying Stress and Mental Health
American Psychologist, 2017
At the intersection between neuroscience, microbiology, and psychiatry, the enteric micro-biome has potential to become a novel paradigm for studying the psychobiological underpinnings of mental illness. Several studies provide support for the view that the enteric microbiome influences behavior through the microbiota-gut-brain axis. Moreover, recent findings are suggestive of the possibility that dysregulation of the enteric microbiota (i.e., dysbiosis) and associated bacterial translocation across the intestinal epithelium may be involved in the pathophysiology of stress-related psychiatric disorders, particularly depression. The current article reviews preliminary evidence linking the enteric microbiota and its metabolites to psychiatric illness, along with separate lines of empirical inquiry on the potential involvement of psychosocial stressors, proinflammatory cytokines and neuroinflam-mation, the hypothalamic-pituitary-adrenal axis, and vagal nerve activation, respectively, in this relationship. Finally, and drawing on these independent lines of research, an integrative conceptual model is proposed in which stress-induced enteric dysbiosis and intestinal per-meability confer risk for negative mental health outcomes through immunoregulatory, endo-crinal, and neural pathways.
BMC microbiology, 2014
The microbiota of the mammalian gastrointestinal (GI) tract consists of diverse populations of commensal bacteria that interact with host physiological function. Dysregulating these populations, through exogenous means such as antibiotics or dietary changes, can have adverse consequences on the health of the host. Studies from laboratories such as ours have demonstrated that exposure to psychological stressors disrupts the population profile of intestinal microbiota. To date, such studies have primarily focused on prolonged stressors (repeated across several days) and have assessed fecal bacterial populations. It is not known whether shorter stressors can also impact the microbiota, and whether colonic mucosa-associated populations can also be affected. The mucosa-associated microbiota exist in close proximity to elements of the host immune system and the two are tightly interrelated. Therefore, alterations in these populations should be emphasized. Additionally, stressors can induc...
Gut, 2006
Background and aim: Chronic psychological stress, including water avoidance stress (WAS), induces intestinal mucosal barrier dysfunction and impairs mucosal defences against luminal bacteria. The aim of this study was to determine the ability of a defined probiotic regimen to prevent WAS induced intestinal pathophysiology. Methods: Male rats were subjected to either WAS or sham stress for one hour per day for 10 consecutive days. Additional animals received seven days of Lactobacillus helveticus and L rhamnosus in the drinking water prior to stress and remained on these probiotics for the duration of the study. Rats were then sacrificed, intestinal segments assessed in Ussing chambers, and mesenteric lymph nodes cultured to determine bacterial translocation. Results: All animals remained healthy for the duration of the study. Chronic WAS induced excess ion secretion (elevated baseline short circuit current) and barrier dysfunction (increased conductance) in both the ileum and colon, associated with increased bacterial adhesion and penetration into surface epithelial cells. Approximately 70% of rats subjected to WAS had bacterial translocation to mesenteric lymph nodes while there was no bacterial translocation in controls. Probiotic pretreatment alone had no effect on intestinal barrier function. However, WAS induced increased ileal short circuit current was reduced with probiotics whereas there was no impact on altered conductance. Pretreatment of animals with probiotics also completely abrogated WAS induced bacterial adhesion and prevented translocation of bacteria to mesenteric lymph nodes. Conclusion: These findings indicate that probiotics can prevent chronic stress induced intestinal abnormalities and, thereby, exert beneficial effects in the intestinal tract.
Impact of the gut microbiota on the neuroendocrine and behavioural responses to stress in rodents
OCL, 2015
The gastro-intestinal tract hosts a complex microbial ecosystem, the gut microbiota, whose collective genome coding capacity exceeds that of the host genome. The gut microbiota is nowadays regarded as a full organ, likely to contribute to the development of pathologies when its dynamic balance is disrupted (dysbiosis). In the last decade, evidence emerged that the gut microbiota influences brain development and function. In particular, comparisons between germ-free and conventional laboratory rodents showed that the absence of the gut microbiota exacerbates the hypothalamic pituitary adrenal (HPA) system reactivity to stress and alters the anxiety-like behaviour. Furthermore, the dysfunctions observed in germ-free animals can be corrected if the gut microbiota is restored in early life but not in adulthood, suggesting a critical period for microbiota imprinting on the responsiveness to stress. The modes of action are still to be deciphered. They may involve transport of neuroactive bacterial metabolites to the brain through the bloodstream, stimulation of the vagus nerve or of entero-endocrine cells, or modulation of the immune system and, consequently, of the inflammatory status. The discovery that the gut microbiota regulates the neuroendocrine and behavioural responses to stress paves the way for the hypothesis that gut microbiota dysbioses could contribute to the pathophysiology of anxiety-related disorders. In this regard, treatments of anxiety-prone rodent strains with probiotics or antibiotics aimed at modifying their gut microbiota have shown an anxiolytic-like activity. Clinical trials are now needed to know if results obtained in preclinical studies can translate to humans. Keywords: Gut-brain axis / germ-free / probiotic / hypothalamic pituitary adrenal axis / anxiety Résumé-Effet du microbiote intestinal sur les réponses neuroendocrinienne et comportementale au stress. Le tractus gastro-intestinal héberge une communauté microbienne complexe appelée microbiote, dont le potentiel génétique excède celui de l'hôte en richesse et diversité. Le microbiote intestinal est considéré aujourd'hui comme un véritable organe, susceptible de contribuer au développement de pathologies si son équilibre est rompu (on parle alors de dysbiose). Au cours de la dernière décennie, des travaux ont commencé à mettre en évidence que le microbiote intestinal influençait le développement et le fonctionnement du cerveau. En particulier, des comparaisons entre rongeurs axéniques et conventionnels ont montré que l'absence de microbiote intestinal intensifiait la réponse au stress de l'axe corticotrope et modifiait le niveau d'anxiété. Ces anomalies ne peuvent être corrigées que si la restauration du microbiote chez les animaux axéniques intervient avant l'âge adulte. Ceci suggère l'existence d'une période critique du développement au cours de laquelle le microbiote influence la maturation des structures cérébrales impliquées dans la réponse au stress. Les mécanismes d'action ne sont pas encore complètement élucidés. Pourraient intervenir des métabolites microbiens neuro-actifs, atteignant le cerveau par voie sanguine, une stimulation des afférences intestinales du nerf vague, une stimulation des cellules endocrines de la paroi intestinale, ou une modulation du système immunitaire et, par conséquent, du statut inflammatoire de l'organisme. La découverte que le microbiote intestinal régule les réponses neuroendocrinienne et comportementale au stress conduit à l'hypothèse que des dysbioses du microbiote pourraient contribuer à la physiopathologie des troubles anxieux ou des troubles de l'humeur ayant une composante anxieuse. À cet égard, la modulation du microbiote intestinal avec des probiotiques ou des antibiotiques chez des lignées de rongeurs prédisposées à l'anxiété a un effet de type anxiolytique. Des essais cliniques sont maintenant nécessaires pour déterminer si ces résultats précliniques sont transposables à l'Homme.
Stress-induced alterations in intestinal microflora
Microbial Ecology in Health and Disease, 2004
Along with other endogenous and exogenous factors which may interfere in the regulation of various pathways that control the intestinal microflora, physical and psychological stress seem to play a crucial role. In order to estimate the influence of psychological stress on the intestinal microflora composition, repeated restraint stress was used as a stress paradigm. Faecal indicator bacteria (aerobic and anaerobic) were used to assess the microbiological profile of the intestinal flora. Faecal samples were collected from adult male Wistar rats (Kuo/Ioa/rr) before and after repeated restraint stress. Serial dilutions were performed in Ringer solution followed by spreading on MacConkey agar that had been incubated at 378C overnight. An aliquot of each solution was heated at 758C for 10 min, followed by spreading in lactose-sulfite (LS) broth. Numbers of Clostridium perfringens were estimated by performing decimal dilutions in the LS broth that had been incubated in a water bath at 468C overnight. Characteristic colonies of Escherichia coli were counted and identified using the API 20E System. Numbers of C. perfringens were estimated and compared to those of E. coli . Higher numbers of vegetative forms of the anaerobic bacterial indicator C. perfringens were found in stress-exposed animals as compared with controls and with pre-stress conditions. The end of the stress exposure found the numbers of C. perfringens back to initial levels or even below.