Host immune and epithelial cell proteins

This term refers to the diverse set of proteins expressed by host immune and epithelial cells that mediate crucial functions in immunity, homeostasis, and barrier defense. Major members of this group include pattern recognition receptors like Toll-like receptors (TLRs), NOD-like receptors (NLRs), retinoic acid-inducible gene (RIG)-like receptors (RLRs), and C-type lectin receptors (CLRs), as well as MHC class II molecules for antigen presentation, antimicrobial peptides (e.g., defensins, Reg3 family), cytokines, chemokines, and adhesion molecules. These proteins govern pathogen sensing, signal transduction, antigen processing, inflammation, tissue repair, and the maintenance of mucosal barriers across organs such as the gut and airways. Their activities underpin both protective immune responses against infection and tolerance to commensals, and their dysregulation is implicated in numerous disease states. Given the above, "Host immune and epithelial cell proteins" should not be considered a canonical drug target, but rather a group heading or descriptor for review purposes. For structured information, individual proteins (e.g., "Toll-like receptor 4", "Major histocompatibility complex class II") should be specified and evaluated separately.