Effects of Psychological, Environmental and Physical Stressors on the Gut Microbiota

Abstract

Stress, a ubiquitous part of daily human life, has varied biological effects which are increasingly recognized as including modulation of commensal microorganisms residing in the gastrointestinal tract, the gut microbiota. In turn, the gut microbiota influences the host stress response and associated sequelae, thereby implicating the gut microbiota as an important mediator of host health. This narrative review aims to summarize evidence concerning the impact of psychological, environmental, and physical stressors on gut microbiota composition and function. The stressors reviewed include psychological stress, circadian disruption, sleep deprivation, environmental extremes (high altitude, heat, and cold), environmental pathogens, toxicants, pollutants, and noise, physical activity, and diet (nutrient composition and food restriction). Stressors were selected for their direct relevance to military personnel, a population that is commonly exposed to these stressors, often at extremes, and in combination. However, the selected stressors are also common, alone or in combination, in some civilian populations. Evidence from preclinical studies collectively indicates that the reviewed stressors alter the composition, function and metabolic activity of the gut microbiota, but that effects vary across stressors, and can include effects that may be beneficial or detrimental to host health. Translation of these findings to humans is largely lacking at present. This gap precludes concluding with certainty that transient or cumulative exposures to psychological, environmental, and physical stressors have any consistent, meaningful impact on the human gut microbiota. However, provocative preclinical evidence highlights a need for translational research aiming to elucidate the impact of stressors on the human gut microbiota, and how the gut microbiota can be manipulated, for example by using nutrition, to mitigate adverse stress responses.

Perceived Stress in First-Year Medical Students and its Effect on Gut Microbiota

“…The Bacteriodetes:Firmicute ratio has been found as an important feature in body mass index, depression, ageing, and other physiological features (Ley et al, 2006;Mariat et al, 2009;Karl et al, 2018). What we found in this research was that the B:F ratio may also be a feature of stress resilience to chronic stressors.…”

“…It is through modulation of these ascending pathways which are closely associated with pain pathways that increased luminal microbiome activity is argued to downregulate pain perception in mammals (Mayer, 2011). Changes to microbiome taxonomic composition have the downstream effect of altering the translational profile of microbiome products (Karl et al, 2018). Thus, when taxonomic changes occur, regulatory feedback from the gut lumen to the myenteric plexus is altered and ultimately projections to the central nervous system are up or downregulated (Hyland and Cryan, 2010).…”

Probiotics Ameliorate Colon Epithelial Injury Induced by Ambient Ultrafine Particles Exposure

“…[8] The gut microbiota is critical for human health [9,10] and maintains intestinal epithelial homeostasis offering a level of protection against gut injury. [13] Animal models have demonstrated adverse intestinal effects following oral administration or pulmonary inhalation of PM. [13] Animal models have demonstrated adverse intestinal effects following oral administration or pulmonary inhalation of PM.…”

Recombinant Probiotics and Microbiota Modulation as a Good Therapy for Diseases Related to the GIT

“…To arrive at mucosa in sufficient quantities to exert their therapeutic effects, many LAB strains must survive, during their passage through the GIT, stressor factors such as pH, temperature, bile salt concentration, and the presence of antimicrobial peptides [170][171][172]. In this context, an interest approach was recently developed by Coelho-Rocha and colleagues [154] using an encapsulated recombinant strain (L. lactis pExu:mcherry) and tested it through the GIT at different times post-administration.…”