Published online Sep 28, 2017. doi: 10.3748/wjg.v23.i36.6665
Peer-review started: June 12, 2017
First decision: July 27, 2017
Revised: August 27, 2017
Accepted: September 5, 2017
Article in press: September 5, 2017
Published online: September 28, 2017
Core tip: To explore which bacteria regulate the expression of toll-like receptors (TLRs) and thereby affect intestinal functions, we performed high-throughput pyrosequencing of the bacterial 16S rRNA gene, compared the microbial communities in the faeces and mucosa of Chinese patients with functional gastrointestinal disorders, and studied their association with the expression of colonic mucosal TLR2 and TLR4. Samples of luminal microbiota were different from those of mucosa-associated microbiota (MAM), and MAM samples were closely associated with TLR2/4 expression. The abundance of Faecallibacterium and Ruminococcus was lower in patients with gut disease, while the expression of TLRs is higher than in healthy controls. The presence of Faecallibacterium and Ruminococcus was significantly and negatively correlated with TLR4 expression, suggesting that these two bacteria, which colonize on the colonic mucosa, play a key role in gut diseases by regulating mucosal TLR4 expression. Granulicatella, which belongs to Carnobacteriaceae, and Streptococcus, which belongs to Streptococcaceae, were inversely correlated with TLR2 expression. Because the two genera contained not only pathogenic species but also probiotic species, it will be important to establish a better understanding of the relationship between TLRs and bacterial strains in future studies.