NOS2 and infection: Genes such as TNFα, IL10, TLR15, IL8L1 (CXCLi1), IL8L2 (CXCLi2), NOS2, ACOD1 and PTGS2 were upregulated with infection and microbiota, suggesting that macrophages may largely participate in the pro-inflammatory response described in caecal tissues [4, 5, 18, 34, 35].