• Claudia Veltkamp, Matthias Anstaett, Kristin Wahl, Sarah Möller, Saskia Gangl, Oliver Bachmann, Matthias Hardtke-Wolenski, Florian Länger, Wolfgang Stremmel, Michael P Manns, Klaus Schulze-Osthoff, and Heike Bantel.
• Department of Gastroenterology, Hepatology and Infectious Diseases, Ruprecht-Karls-University, Heidelberg, Germany.
• Gut. 2011 Oct 1; 60 (10): 1345-53.

Background And AimsInappropriate immune responses contribute to the continuous stimulation of the intestinal immune system in chronic inflammatory bowel disease (IBD). Among several pathogenic factors, a numerical deficiency of regulatory T (Treg) cells has been suggested to lead to an insufficient compensation of chronically activated T lymphocytes. This study was conducted to investigate whether increased apoptosis contributes to Treg cell deficiency in IBD and whether successful treatment with antitumour necrosis factor α (TNFα) is achieved by reducing of Treg cell apoptosis.MethodsApoptosis of CD4(+)Foxp3(+) Treg cells in tissue sections of patients with active IBD was analysed by immunohistochemistry and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labelling) staining. Apoptosis of peripheral blood CD4(+)CD25(+)Foxp3(+) Treg cells was investigated by flow cytometry and annexin-V staining. In addition, caspase activity and apoptosis were measured in sera of patients with IBD treated with anti-TNFα by a luminometric caspase enzyme assay.ResultsIt is demonstrated that patients with active IBD revealed increased apoptosis of local CD4(+)Foxp3(+) Treg cells in the inflamed mucosa compared with non-inflamed control colon tissue. Moreover, in peripheral blood a reduced frequency and increased apoptosis of Treg cells were found and accompanied by elevated caspase activity in the serum. During anti-TNFα treatment, Treg cell apoptosis declined in close correlation with elevated peripheral Treg cell numbers and a decrease of caspase activation and disease activity.ConclusionsThese data suggest that increased apoptosis of Treg cells plays a potentially important role in the pathogenesis of IBD and can be reversed by anti-TNFα treatment. Measurement of Treg cell apoptosis and serum caspase activity might therefore represent promising tools for monitoring disease activity and treatment response in patients with IBD.

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