Toll-like receptors are important immune receptors which recognize microbial motifs and TLR4 which recognizes LPS is important in chronic pyelonephritis induced tissue damage. E. coli, one of gram-negative bacteria family, is rich in LPS, so TLR4 might be activated and participated in the progress of pyelonephritis. The gene discussed is TLR4; the disease is pyelonephritis.