IL-27 gut immunology: Mechanisms and potential value as a biomarker and therapeutic target in intestinal diseases.

Interleukin-27 (IL-27), an Interleukin-12 (IL-12) family heterodimeric cytokine, plays a central yet complex role in immunoregulation within the intestinal mucosa, where its context-dependent actions can promote both protective and pathogenic outcomes. Although its cellular sources, receptor structure (IL-27Rα/gp130 complex), and involvement in regulating key immune cells (e.g., T-cell subsets, macrophages, neutrophils) and epithelial functions are established, the precise mechanisms underlying its paradoxical effects-balancing homeostasis with inflammation-remain incompletely resolved. This review synthesizes current understanding of IL-27 biology to clarify its multifaceted role. Crucial insights into these dual functions have emerged from preclinical models, including murine colitis (e.g., DSS-, TNBS-induced), enteric infection (e.g., Toxoplasma gondii, Citrobacter rodentium), and colorectal cancer models. These studies demonstrate that IL-27 critically orchestrates gut immunity, maintaining homeostasis through antimicrobial defense and barrier enhancement while suppressing immunopathology. Conversely, its dysregulation drives chronic inflammation and carcinogenesis. Clinically, IL-27 expression correlates with disease activity in inflammatory bowel disease (IBD), colorectal cancer (CRC), and infections, highlighting its biomarker potential. Consequently, targeting the IL-27 pathway presents promising therapeutic avenues: augmenting signaling may mitigate IBD hyperinflammation, while inhibition could bolster antitumor immunity or resolve infection-driven pathology. Future research must prioritize defining context-specific IL-27 functions, optimizing delivery strategies, and integrating IL-27 targeting with existing biologics to translate its immunomodulatory potential into novel therapies for intestinal diseases.