Cutting Edge: Activation of STING in T Cells Induces Type I IFN Responses and Cell Death.

Stimulator of interferon genes (STING) was initially described as a sensor of intracellular bacterial and viral DNA and a promising adjuvant target in innate immune cells; more recently STING has also been shown to detect endogenous DNA and play a role in tumor immunity and autoimmune disease development. Thus far STING has been studied in macrophages and dendritic cells. In this study, to our knowledge we provide the first evidence of STING activation in T cells, in which STING agonists not only provoke type I IFN production and IFN-stimulated gene expression, mirroring the response of innate cells, but are also capable of activating cell stress and death pathways.

CD209a expression on dendritic cells is critical for the development of pathogenic Th17 cell responses in murine schistosomiasis.

In murine schistosomiasis, immunopathology and cytokine production in response to parasite eggs are uneven and strain dependent. CBA/J (CBA) mice develop severe hepatic granulomatous inflammation associated with prominent Th17 cell responses driven by dendritic cell (DC)-derived IL-1β and IL-23. Such Th17 cells fail to develop in low-pathology C57BL/6 (BL/6) mice, and the reasons for these strain-specific differences in APC reactivity to eggs remain unclear.

Induction and regulation of pathogenic Th17 cell responses in schistosomiasis.

Schistosomiasis is a major tropical disease caused by trematode helminths in which the host mounts a pathogenic immune response against tissue-trapped parasite eggs. The immunopathology consists of egg antigen-specific CD4 T cell-mediated granulomatous inflammation that varies greatly in magnitude in humans and among mouse strains in an experimental model. New evidence, covered in this review, intimately ties the development of severe pathology to IL-17-producing CD4 T helper (Th17) cells, a finding that adds a new dimension to the traditional CD4 Th1 vs.

T-helper 17 cells are associated with pathology in human schistosomiasis.

Background: Schistosome infections are often clinically silent, but some individuals develop severe pathological reactions. In several disease processes, T-helper 17 (Th17) cells have been linked to tissue injuries, while regulatory T cells (Tregs) are thought to downmodulate inflammatory reactions. We assessed whether bladder pathology in human Schistosoma haematobium infection is related to the balance of Th17 cells and Tregs.

The pathogenic Th17 cell response to major schistosome egg antigen is sequentially dependent on IL-23 and IL-1β.

CBA/J mice infected with the helminth Schistosoma mansoni develop severe CD4 T cell-mediated hepatic granulomatous inflammation against parasite eggs associated with a robust Th17 cell response. We investigated the requisites for Th17 cell development using novel CD4 T cells expressing a transgenic TCR specific for the major Sm-p40 egg Ag, which produce IL-17 when stimulated with live schistosome eggs. Neutralization of IL-23 or blockade of the IL-1 receptor, but not IL-6 neutralization, abrogated egg-induced IL-17 secretion by transgenic T cells, whereas exogenous IL-23 or IL-1β reconstituted their ability to produce IL-17 when stimulated by syngeneic IL-12p40-deficient dendritic cells.