Restoration of mucosal integrity and epithelial transport function by concomitant anti-TNFα treatment in chronic DSS-induced colitis.

Impaired salt and water absorption is a hallmark of diarrhea in IBD. In the present study, the therapeutic effect of continuous anti-TNFα treatment on the progression of inflammation and colonic transport dysfunction during chronic dextran sulfate sodium (DSS)-induced colitis was investigated. Chronic colitis was induced by three DSS exposure cycles. Mice received TNFα monoclonal antibody treatment twice weekly after the end of the first 5-day DSS drinking period. Mice developed chronic DSS-induced colitis characterized by a typical immune cell infiltration composed of CD3+ T cells and CD68+ macrophages, both expressing high levels of the pro-inflammatory cytokines IL-1ß and TNFα, a loss of NHE3 and PDZK1 in the brush border region of the absorptive enterocyte and a decrease of colonic fluid absorption in vivo, measured by colonic single pass perfusion. Concomitant anti-TNFα treatment resulted in a significant reduction of mucosal immune cell infiltration and expression of the pro-inflammatory cytokines IL-1ß and TNFα. It also resulted in a normalization of NHE3-mediated fluid absorption and a restoration of NHE3 and PDZK1 location in the apical and subapical region of the enterocytes. Here, we show for the first time that in this chemically induced murine colitis model, anti-TNFα treatment significantly decreased inflammatory activity, improved mucosal integrity and restored transport function despite an ongoing inflammatory insult. Anti-TNFα treatment may therefore be beneficial in patients with IBD even in spite of an absence of complete mucosal healing. KEY MESSAGES: Chronic DSS treatment caused a loss of NHE3 and PDZK1 in the brush border region of the absorptive enterocyte and decreases colonic fluid absorption. In DSS-induced colitis, anti-TNFα treatment reduced mucosal immune cell infiltration and expression of the pro-inflammatory cytokines IL-1ß and TNFα. In DSS-induced colitis, anti-TNFα treatment normalized NHE3-mediated fluid absorption and restored NHE3 and PDZK1 location in the enterocytes. In DSS-induced colitis, anti-TNFα treatment decreased inflammatory activity, improved mucosal integrity, and restored transport function.