The role of adenosine in helper T cell differentiation and function (840.1)

Abstract

Background and Aims: Extracellular signaling molecules, such as anti‐inflammatory adenosine, play a major role in restraining immune response and protecting tissue from inflammatory damage. Adenosine is generated from the ATP through the action of ectonucleoside triphosphate diphosphohydrolase 1 (CD39) that sequentially dephosphorylates ATP to ADP to 5’‐AMP, which is then catabolized to adenosine by ecto‐5'‐nucleotidase (CD73, Nt5e). The aim of this study was to investigate the role of extracellular adenosine in control of helper T cell (Th) cell differentiation and cellular function. Results: Adenosine levels were controlled with a pharmacological approach using the non‐hydrolysable adenosine analog, NECA. Naïve CD4+ T cells were differentiated in vitro in the presence or absence of NECA in selective culture conditions. The presence of NECA suppressed the production of IL‐17a in cells isolated from Th17 conditions. We then explored a genetic approach to control adenosine levels in vivo, using an adoptive transfer colitis model. According to the model, the transfer of CD4+CD45RBhi cells, a subset that contains largely T effector (Teff) cells, will induce colitis when transferred to Rag1‐/‐ mice. Colitis can be ameliorated with the co‐transfer of CD4+CD45RBlo, a cell population with a primarily regulatory phenotype. T cells were isolated from Nt5e‐/‐ mice to investigate the function of Th cells compromised in the ability to produce adenosine. In our adoptive transfer studies, CD73 on both Treg and T effector proved to be necessary for Treg to prevent Teff‐induced colitis. Conclusions: Adenosine signaling has the ability to restrain Th17 response during differentiation through the direct reduction of the production of the pro‐inflammatory cytokine IL‐17a. The ability to produce adenosine is essential for effective Treg activity and compromising the adenosine pool changes the differentiation patterns of Th cells causing excessive inflammatory activation and tissue damage.Grant Funding Source: Supported By: T32 Gastrointestinal Training Grant