S100A9 and infection: Production of various antimicrobial peptides, such as psoriasin (S100A7), calgranulin-A (S100A8), calgranulin-B (S100A9), β-defensin-3 (mβD3), and lipocalin-2 serves as a key factor in the IL-22-mediated defense of epithelial cells against pathogenic infection (63).