Cells Suppress Innate Immune Pathology Through Cytokine-dependent Mechanisms

CD4 CD25 regulatory T (T R ) cells can inhibit a variety of autoimmune and inflammatory diseases, but the precise mechanisms by which they suppress immune responses in vivo remain unresolved. Here, we have used Helicobacter hepaticus infection of T cell–reconstituted recombination-activating gene (RAG) / mice as a model to study the ability of CD4 CD25 T R cells to inhibit bacterially triggered intestinal inflammation. H. hepaticus infection elicited both T cell-mediated and T cell–independent intestinal inflammation, both of which were inhibited by adoptively transferred CD4 CD25 T R cells. T cell–independent pathology was accompanied by activation of the innate immune system that was also inhibited by CD4 CD25 T R cells. Suppression of innate immune pathology was dependent on T cell–derived interleukin 10 and also on the production of transforming growth factor . Thus, CD4 CD25 T R cells do not only suppress adaptive T cell responses, but are also able to control pathology mediated by innate immune mechanisms.