To test this hypothesis, we used a well-established murine model of chronic pyelonephritis induced by the UPEC strain IH11128 and C5aR1-deficient (C5aR1-/-) mice, as well as a C5aR1 antagonist, to determine the role of C5aR1 in chronic kidney infection (i.e., bacterial load, tissue inflammation, and tubulointerstitial fibrosis). This evidence concerns the gene C5AR1 and chronic pyelonephritis.