During pyelonephritis, the medulla’s hyperosmotic environment promotes monocyte chemotactic protein - 1 (MCP - 1) production by nuclear factor activated T cell 5 (NFAT5) in renal tubular cells, recruiting CD14 + mononuclear phagocytes (MNP) to the medulla (Schwartz et al., 2023). This evidence concerns the gene NFAT5 and pyelonephritis.