Impaired distal colonic pH in adults with cystic fibrosis

Previous wireless motility capsule (WMC) studies demonstrated decreased small intestinal pH in people with CF (PwCF) however the data is lacking on the colonic pH profile. We re-analyzed previously published WMC data to determine colonic pH/bicarbonate concentration and single cell RNA sequencing (sc-RNAseq) to examine the normal expression of acid-base transporters in the colon/rectum.CF patients showed significantly lower pH and bicarbonate concentration values, particularly in the distal rectosigmoid region. There was no difference in colonic motility parameters between CF and non-CF subjects. SLC26A3 is highly expressed bicarbonate transporter in the colon and rectum, more so than CFTR. While dysmotility can alter intraluminal pH, observed changes likely originate from alterations in intestinal ion transport rather than colonic dysmotility. SLC26A3 is abundantly expressed in the human colon and rectum and may be a therapeutic target for restoration of bicarbonate transport. These findings may help better understand the gastrointestinal symptoms in PwCF.