IL-12Rb2 Is Essential for the Development of Experimental Cerebral Malaria

A Th1 response is required for the development of Plasmodium berghei ANKA (PbA)-induced experimental cerebral malaria (ECM). The role of pro-Th1 IL-12 in malaria is complex and controversial. In this study, we addressed the role of IL-12Rb 2i n ECM development. C57BL/6 mice deficient for IL-12Rb2, IL-12p40, or IL-12p35 were analyzed for ECM development after blood-stage PbA infection in terms of ischemia and blood flow by noninvasive magnetic resonance imaging and angiography, T cell recruitment, and gene expression. Without IL-12Rb2, no neurologic sign of ECM developed upon PbA infection. Although wildtype mice developed distinct brain microvascular pathology, ECM-resistant, IL-12Rb2–deficient mice showed unaltered cerebral microcirculation and the absence of ischemia after PbA infection. In contrast, mice deficient for IL-12p40 or IL-12p35 were sensitive to ECM development. The resistance of IL-12Rb2–deficient mice to ECM correlated with reduced recruitment of activated T cells and impaired overexpression of lymphotoxin-a, TNF-a, and IFN-g in the brain after PbA infection. Therefore, IL-12Rb2 signaling is essential for ECM development but independent from IL-12p40 and IL-12p35. We document a novel link between IL-12Rb2 and lymphotoxin-a, TNF-a, and IFN-g expression, key cytokines for ECM pathogenesis. The Journal of Immunology, 2012, 188: 000–000.