Abstract
Inflammatory bowel disease (IBD), which includes Crohn's Disease (CD) and ulcerative colitis (UC), is characterized by chronic inflammation of the gastrointestinal tract. A key component of the inflammatory pathway in IBD is interleukin 23 (IL-23), which promotes the differentiation and maintenance of Th17 cells. These cells are major contributors to intestinal inflammation and the release of pro-inflammatory cytokines. A dysregulated IL-23/Th17 axis can lead to excessive gut inflammation. Notably, IL-23 affects Th17 cell responses differently in UC and CD, fostering IL-17 production in UC and interferon-gamma (IFN-γ) production in CD. Genetic studies have pinpointed specific variants of the IL-23 receptor (IL23R) gene that confer protection against IBD. The R381Q (rs11209026) variant has been linked to a reduced risk of developing both CD and UC. Additionally, other variants, such as G149R (rs76418789) and V362I (rs41313262), inhibit IL23R function by disrupting intracellular trafficking and protein stability. This disruption results in decreased phosphorylation of downstream signal transducers, such as STAT3 and STAT4, and reduced IL23R expression on the cell surface, ultimately dampening the activation of pro-inflammatory pathways. The protective effects of these genetic variants underscore the IL-23/IL23R pathway as a significant therapeutic target in IBD management. Therapies designed to modulate this pathway have the potential to reduce pro-inflammatory cytokine production and enhance anti-inflammatory mechanisms. Ongoing research into the IL23R gene and its variants continues to provide valuable insights, paving the way for more targeted and effective treatments for IBD patients.