(Boor et al., 2007; Li et al., 2017; Peng et al., 2019; Zhang et al., 2020) C5a signalling promotes disease progression in rodent experimental models of tubulointerstitial fibrosis, (Boor et al., 2007) acute and chronic pyelonephritis, (Choudhry et al., 2016; Li et al., 2017) renal ischaemia‐reperfusion injury, (Peng et al., 2019) and immune complex glomerulonephritis (Alexander et al., 2012). The gene discussed is C5AR1; the disease is chronic pyelonephritis.