SPP1 and nephrolithiasis: Numerous studies have shown that calcium oxalate stone formation is an inflammatory process.3, 4 The CaOx crystals in the kidney interstitium are always surrounded by numerous macrophages in specimens from stone patients and in animal models.3 When exposed to COM or oxalate (Ox), renal tubular epithelial cells secrete many inflammatory factors, such as osteopontin (OPN), monocyte chemotactic protein 1 (MCP‐1), CD44 and transforming growth factor‐β (TGF‐β), among others.4, 5 MCP‐1 is one of the well‐accepted and most important inflammatory factors in kidney stones.