Regulation of adaptive immune responses by the phagocyte-type NADPH oxidase in T cells and antigen presenting cells

Abstract

Absence of phagocyte NADPH oxidase (NOX2) activity causes chronic granulomatous disease (CGD), a primary immunodeficiency characterized by recurrent bacterial infections. In contradiction to this innate immune dysfunction, CGD patients or animal models of the disease display improved response to infectious agents such as Helicobacter pylori, influenza virus or Cryptococcus neoformans. These and other data imply an altered adaptive immune response in CGD. In addition to antigen presenting cells (APCs), NOX2 is expressed in T cells, and the goal was to determine if these differences are T cell inherent, or if NOX2-deficient APCs promote T-helper polarization. We hypothesize that NOX2 shapes both adaptive and innate immune responses in a T cell and APC-dependent fashion. In order to study T-helper polarization in vivo, wild type and NOX2-deficient (NOX2<super>(-/-)</super>) mice were immunized with OVA in CFA or Alum. Upon in vitro restimulation, lymph node cells from NOX2<super>(-/-)</super> mice had increased Th1 but decreased Th2 cytokine production. Adoptive transfer of OT-II T cells into wild type or NOX2<super>(-/-)</super> hosts followed by immunization also revealed increased IL-17 and IFN-γ, but decreased IL-4 after restimulation in vitro. NOX2<super>(-/-)</super> APCs (resident peritoneal cells and adherent splenocytes) displayed enhanced proinflammatory cytokine secretion in vitro, and stimulation of OT-II T cells with antigen-pulsed NOX2<super>(-/-)</super> APCs in vitro induced altered cytokine production, suggesting that NOX2 deficiency modifies APC function, resulting in T helper skewing. In addition to APC-induced changes, T cells from NOX2<super>(-/-)</super> mice were inherently skewed. Naïve T cells from NOX2<super>(-/-)</super>mice demonstrated Th1 skewed cytokine secretion as compared to their wild type counterparts, through increased IFN-γ, but decreased IL-4 in response to anti-CD3 and anti-CD28 stimulation. There were also selective decreases in GATA-3 and phosphorylated STAT5, with decreased Il4 gene expression, suggesting a mechanism for decreased Th2 responses. Finally, treatment with antioxidants recapitulated these selective changes in TCR-induced transcription factor activation. These findings indicate that TCR-induced reactive oxygen species generation from NOX2 activation selectively promotes STAT5 phosphorylation and downstream Th2 development in CD4+ T cells. Taken together, these findings suggest NOX2 affects cross talk between the innate and adaptive immune systems, resulting in changes in T helper differentiation.