Characterization of chemokine and chemokine receptor expression during Pneumocystis infection in healthy and immunodeficient mice (part 3)

In wild-type mice, expression of chemokines that are ligands for Ccr2, Cxcr3, and Cxcr2 increased at days 32 to 41 post-infection, with a return to baseline by day 75. Concomitant increases were seen in Ccr2 and Cxcr3 but not in Cxcr2 expression. Induction of these same factors also occurred in CD40-ligand and CD40 knockout mice but only at a much later time-point, during uncontrolled Pneumocystis pneumonia (PCP). Expression of CD4 Th1 markers was increased in wild-type mice during clearance of infection. Ccr2 and Cx3cr1 knockout mice cleared Pneumocystis infection with kinetics similar to wild-type mice, and all animals developed anti-Pneumocystis antibodies. Upregulation of Ccr2 and Cxcr3 and their ligands supports an important role for T helper cells and mononuclear phagocytes in the clearance of Pneumocystis infection. However, based on the current and prior studies, no single chemokine receptor appears to be critical to the clearance of Pneumocystis.

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Bishop LR, Lionakis MS, Sassi M, Murphy PM, Hu X, Huang da W, Sherman B, Qiu J, Yang J, Lempicki RA, Kovacs JA