Gut Bacteria and Hydrogen Sulfide: The New Old Players in Circulatory System Homeostasis

Abstract

Accumulating evidence suggests that gut bacteria play a role in homeostasis of the circulatory system in mammals. First, gut bacteria may affect the nervous control of the circulatory system via the sensory fibres of the enteric nervous system. Second, gut bacteria-derived metabolites may cross the gut-blood barrier and target blood vessels, the heart and other organs involved in the regulation of the circulatory system. A number of studies have shown that hydrogen sulfide (H 2 S) is an important biological mediator in the circulatory system. Thus far, research has focused on the effects of H 2 S enzymatically produced by cardiovascular tissues. However, some recent evidence indicates that H 2 S released in the colon may also contribute to the control of arterial blood pressure. Incidentally, sulfate-reducing bacteria are ubiquitous in mammalian colon, and H 2 S is just one among a number of molecules produced by the gut flora. Other gut bacteria-derived compounds that may affect the circulatory system include methane, nitric oxide, carbon monoxide, trimethylamine or indole. In this paper, we review studies that imply a role of gut microbiota and their metabolites, such as H 2 S, in circulatory system homeostasis.

Probiotic Supplementation in a Clostridium difficile-Infected Gastrointestinal Model Is Associated with Restoring Metabolic Function of Microbiota

“…These levels appeared to be restored to the level found in the normal fecal samples when supplemented with each of the probiotic treatments ( Figure 4). The depletion of H 2 S observed in the C. difficile-infected fecal samples coincides with previous observations of inflammatory bowel conditions being associated with dysregulation of sulphate producing bacteria and disruption in some of the key functions of H 2 S such as colonic mucus production and maintenance of microbiota biofilm [79,80]. The ability of probiotic supplementation to increase and restore H 2 S levels in the C. difficile-infected fecal samples could be linked with the concurrent increased generation of acetate and butyrate.…”

“…High levels of NH 4 have been linked to cytotoxic effects on the gut lumen, contributing to the formation of colorectal cancer [77,78]. Similarly, H 2 S has been linked to a range of toxicity pathways [79,80]. The results from the present work show that NH 4 production in the GI model was within the normal range of NH 4 production in the human gut lumen [36,39].…”

Flavin-containing monooxygenases in aging and disease: Emerging roles for ancient enzymes

“…First, seafood rich in TMA and TMAO is widely thought to lower CVD risk (50). Second, as mentioned, an early study of TMAU patients found a high incidence of hypertension in the TMAUafflicted group (43).…”

Toll-like receptor-4 signaling pathway in aorta aging and diseases: “its double nature”

“…A very sophisticated control regulates its activity and contributes to maintaining a fine homeostasis. This regulation (similarly to that regulating the entire cardiovascular system) is dominated by the central nervous system (CNS) [151], the knowledge of which in the past 20 years has significantly evolved. This control is also supported, or rather induced by autonomic nervous system (ANS) [152], which completes the primary ring of homeostasis body's control along with the immune and endocrine systems.…”