BDNF contributes to IBS-like colonic hypersensitivity via activating the enteroglia-nerve unit. Sci Rep. 2016;6:20320. [PMID: 26837784 PMCID: PMC4738267 DOI: 10.1038/srep20320]

Chemical and molecular factors in irritable bowel syndrome: current knowledge, challenges, and unanswered questions

Several chemical and molecular factors in the intestine are reported to be altered and to have a potentially significant role in irritable bowel syndrome (IBS), particularly in IBS with diarrhea. These include bile acids; short-chain fatty acids; mucosal barrier proteins; mast cell products such as histamine, proteases, and tryptase; enteroendocrine cell products; and mucosal mRNAs, proteins, and microRNAs. This article reviews the current knowledge and unanswered questions in the pathobiology of the chemical and molecular factors in IBS. Evidence continues to point to significant roles in pathogenesis of these chemical and molecular mechanisms, which may therefore constitute potential targets for future research and therapy. However, it is still necessary to address the interaction between these factors in the gut and to appraise how they may influence hypervigilance in the central nervous system in patients with IBS.

The acute inhibition of enteric glial metabolism with fluoroacetate alters calcium signaling, hemichannel function, and the expression of key proteins

Glia play key roles in the regulation of neurotransmission in the nervous system. Fluoroacetate (FA) is a metabolic poison widely used to study glial functions by disrupting the tricarboxylic acid cycle enzyme aconitase. Despite the widespread use of FA, the effects of FA on essential glial functions such as calcium (Ca²⁺) signaling and hemichannel function remain unknown. Therefore, our goal was to assess specifically the impact of FA on essential glial cell functions that are involved with neurotransmission in the enteric nervous system. To this end, we generated a new optogenetic mouse model to study specifically the effects of FA on enteric glial Ca²⁺ signaling by crossing PC::G5-tdTomato mice with Sox10::creER^T2 mice. FA did not change the peak glial Ca²⁺ response when averaged across all glia within a ganglion. However, FA decreased the percent of responding glia by 30% (P < 0.05) and increased the peak Ca²⁺ response of the glial cells that still exhibited a response by 26% (P < 0.01). Disruption of Ca²⁺ signaling with FA impaired the activity-dependent uptake of ethidium bromide through connexin-43 (Cx43) hemichannels (P < 0.05) but did not affect baseline Cx43-dependent dye uptake. FA did not cause overt glial or neurodegeneration, but glial cells significantly increased glial fibrillary acid protein by 56% (P < 0.05) following treatment with FA. Together, these data show that the acute impairment of glial metabolism with FA causes key changes in glial functions associated with their roles in neurotransmission and phenotypic changes indicative of reactive gliosis.

NEW & NOTEWORTHY

Our study shows that the acute impairment of enteric glial metabolism with fluoroacetate (FA) alters specific glial functions that are associated with the modification of neurotransmission in the gut. These include subtle changes to glial agonist-evoked calcium signaling, the subsequent disruption of connexin-43 hemichannels, and changes in protein expression that are consistent with a transition to reactive glia. These changes in glial function offer a mechanistic explanation for the effects of FA on peripheral neuronal networks.

Effects of plant fermentation extract on intestinal microbiota in patients with irritable bowel syndrome

AIM: To investigate the effect of plant fermentation extracts (PFE) on intestinal microbiota in patients with irritable bowel syndrome (IBS), using high-throughput sequencing.

METHODS: The feces were collected from IBS patients before (day 0) and 30 days (day 30) after consumption of PFE, respectively. The community structure and abundance of the intestinal microbiota were examined via analyzing 16S rRNA high throughput sequencing using an Illumima System.

RESULTS: The overall diversity of the intestinal microbiota had no significant change on day 30. At the phylum level, the abundance of Firmicutes was significantly decreased (P < 0.05), while that of Bacteroidetes was significantly increased (P < 0.05). The ratio of Bacteroidetes/Firmicutes was greatly elevated. At the family level, Campylobacteraceae, Cryomorphaceae, Erysipelotrichaceae and Fibrobacteraceae were detected after the PFE consumption, and their abundance all significantly increased (P < 0.05).

CONCLUSION: PFE improves the abundance of intestinal microbiota in IBS patients, which may be utilized as a type of dietary intervention of IBS.