The MADCAM1 gene encodes Mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1), an endothelial cell adhesion molecule crucial for guiding leukocyte traffic. MAdCAM-1 is preferentially expressed on endothelial cells of gut-associated lymphoid tissues (GALT), such as Peyer's patches and mesenteric lymph nodes, and venules of the intestinal lamina propria ^[1]. Its expression is inducible by pro-inflammatory cytokines like TNF-α, and also influenced by cell-cell interactions and cellular density. The encoded protein is a member of the immunoglobulin superfamily, featuring two Ig-like domains, a mucin-like region, a transmembrane domain, and a cytoplasmic tail. MAdCAM-1 primarily functions by interacting with leukocyte α4β7 integrin (LPAM-1), L-selectin, and VLA-4 (α4β1) on myeloid cells, directing these immune cells into mucosal and inflamed tissues, playing a vital role in gut immune surveillance and lymphocyte homing ^[2]. Aberrant or upregulated MAdCAM-1 expression is strongly associated with various inflammatory diseases, particularly inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis, where its overexpression contributes to excessive lymphocyte accumulation and inflammation in the gut ^[3]. It is also implicated in other conditions such as primary sclerosing cholangitis, type 1 diabetes, and certain cancers where gut inflammation or lymphocyte trafficking is key ^[2-4]. The B6-hMADCAM1 mouse is a humanized model, constructed by replacing the sequences from exon 1 to a partial intron 4 of mouse Madcam1 with the sequences from the ATG start codon to the TGA stop codon of the human MADCAM1 gene, and the 3' UTR of mouse Madcam1-rBG pA cassette is inserted downstream of the TGA stop codon. B6-hMADCAM1 mice can be used for research into the pathogenesis of inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis, primary sclerosing cholangitis, type 1 diabetes, and certain cancers. They are also useful for the screening, development, and safety evaluation of MADCAM1-targeted drugs.

Or8b53 is located on chromosome 9 of mice. Nuclease Technology will be used to design sgRNA; Or8b53 knockout mice will be obtained by applying high-throughput electroporation of fertilized eggs. After sexual maturity, sperm were collected for cryopreservation.

Klhl6 is located on chromosome 16 of mice. SgRNA and ssDNA will be designed using Nuclease Technology; Klhl6 conditional knockout mice will be obtained by high-throughput electroporation of fertilized eggs. After sexual maturity, sperm will be collected for cryopreservation.