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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-1β 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-1β 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.

The therapeutic capacity of an antibody directed against the T cell receptor (anti-TCR) of the TCR/CD3 complex alone or in combination with fingolimod (FTY720) to reverse the diabetic metabolic state through suppression of autoimmunity and stimulation of β cell regeneration was analyzed in the LEW.1AR1-iddm (IDDM) rat, an animal model of human type 1 diabetes. Animals were treated with anti-TCR (0.5 mg/kg body weight for 5 days) monotherapy or in combination with fingolimod (1 mg/kg body weight for 40 days). Metabolic changes and β cell morphology were analyzed before, immediately after, and 60 days after end of therapy. Both therapies were started early after disease manifestation and led to normoglycemia in parallel with an increase of the C-peptide concentration. Combination therapy increased the β cell mass reaching a range of normoglycemic controls, decreased the apoptosis rate fivefold, and increased the proliferation rate threefold. Additionally, at 60 days after therapy, islets were virtually free of T cells, macrophages, and cytokine expression. In contrast, after anti-TCR monotherapy, β cell mass remained low with an activated immune cell infiltrate. A concomitant fivefold increased β cell apoptosis rate resulted in a complete loss of β cells. Only combination therapy yielded sustained normoglycemia with full reversal of islet infiltration and restoration of pancreatic β cell mass.Combination therapy of anti-TCR and fingolimod was effective in the reversal of T1D. Combination therapy increased the pancreatic β cell mass to normoglycemic control levels. Combination therapy leads to a full reversal of pancreatic islet infiltration. Anti-TCR monotherapy did not abolish islet infiltration. Combination therapy was successful only immediately after diabetes manifestation.