Impact of chronological ageing on tight junction-related gene expression at the human gastrointestinal epithelium: An...

To explore the impact of chronological ageing on gene expression levels of tight junction-related genes in the human gastrointestinal (GI) epithelium.

Biopsies were collected from the epithelium of the stomach, the duodenum, the ascending colon, and the descending colon of adults and of older adults. Relative quantification of gene expression levels for claudin-2, occludin, ZO-1, and JAM-A was performed using real-time qPCR only in biopsies from individuals whose dietary habits, medical record, and endoscopic data did not indicate a potential impact on epithelial barrier function. Relative gene expression analysis was performed in gastric biopsies from 3 adults (39-44 years) and from 3 older adults (68-89 years), in duodenal biopsies from 11 adults (30-45 years) and from 12 older adults (66-89 years), and in paired biopsies from the ascending and descending colon of 6 adults (35-45 years) and 9 older adults (66-87 years).

Expression levels of all four investigated tight junction-related genes in the gastric epithelium, in the duodenal epithelium, and in the epithelium of the ascending and descending colon were not affected by chronological ageing. However, in older adults, the gene expression level of occludin was higher in the descending colon compared to the ascending colon.

Chronological healthy ageing does not appear to impact tight junction-related gene expression levels along the GI epithelium. It would be useful to investigate the barrier of descending vs. ascending colon in older adults with colitis, as the transport of 5-aminosalicylic acid, a frequently used anti-inflammatory agent, occurs, at least partly, via the paracellular pathway.