High proteolytic activity in the faeces helps predict ulcerative colitis

There seems to be heightened faecal proteolytic activity that precedes the onset and diagnosis of ulcerative colitis (UC), a recent study has found. This proteolytic signature, along with associated microbiota changes, may represent a noninvasive marker for gut inflammation to monitor at-risk populations.

Using faecal samples from 13 UC patients and 48 matched healthy controls (HC), the researchers performed 16S rRNA gene sequencing, shotgun metagenomics, and various functional assays to determine microbial composition and activity. Faecal samples were obtained before and after UC onset.

Microbiota beta-diversity showed significantly different clustering post-UC as opposed to pre-UC and HC samples. Alpha diversity was also lower in post-UC samples, which showed relative enrichment of Actinobacillus taxa, along with a decrease in Bilophila and Adlercreutzia.

Shotgun metagenomics confirmed a reduction in Adlercreutzia equolifaciens and Bifidobacterium in post-UC samples vs HC. Notably, 29 taxa were exclusively detected in pre-UC faecal samples, but not in HC or post-UC specimens.

In addition, four pathways were found to be unique to pre-UC samples, along with 15 other pathways present in both UC samples, but absent in HC collections.

Subsequent analyses uncovered more than 22,000 bacterial gene families that were differentially expressed between pre-UC vs post-UC and HC samples. Of these, 237 unique families were connected with peptidases or proteases.

“Taken together, these data reveal an altered compositional and functional microbial profile related to protein and amino acid metabolism that precedes clinical UC,” the researchers said.