Distinct Colitis-Associated Macrophages Drive NOD2-Dependent Bacterial Sensing and Gut Homeostasis

In this study, to investigate the role of macrophage GIV in the colon, Katkar et al. employed a myeloid-specific GIV-KO (Ccdc88afl/fl/LysMCre) mouse model to analyze colon transcriptomic data from wild-type (WT) and macrophage-specific GIV-KO mice treated with dextran sulfate sodium (DSS) colitis, with or without muramyl dipeptide (MDP) treatment. To induce colitis, mice were fed with drinking water containing 2.5% dextran sulfate sodium (DSS, w/v) (MP Biomedicals, MW 36–50 kDa) for five days and then replaced normal drinking water as described. For treatment study, MDP (100 mg/mouse/day) was administered via intraperitoneal route in 100 ml total volume sterile saline every alternate day starting from day 0 of experiment. Mice were sacrificed on the 14th day, and colon length was assessed. Colon samples were collected for assessing gene expression the levels of mRNA (by qPCR). To induce colitis, 8–10-week-old mice were administered 2.5% (w/v) dextran sulfate sodium (DSS; MW 36,000–50,000) in drinking water for 5 consecutive days, followed by regular water for an additional 2 days. Control mice received regular drinking water throughout the experiment. Colonic tissues were harvested on day 7 for RNA extraction. Total RNA was isolated using TRIzol reagent (Life Technologies) and Quick-RNA MiniPrep Kit (Zymo Research, USA), and RNA integrity was assessed using a RNA ScreenTape (Agilent Technologies).