Pooled OR and 95% CI was used to assess the association between the allelic, dominant and recessive models of IL23Rrs11209026 and rs10889677 polymorphisms and UC and CD risk.
Th17 T<sub>EM</sub> cells (expressing <i>IL17A, IL17F, RORC</i>, and <i>STAT3</i>) displayed a higher pathogenic/cytotoxic (<i>IL23R, IL18RAP</i>, and <i>GZMB, CD160, PRF1</i>) gene signature in CD relative to UC, while non-pathogenic/regulatory genes (<i>IL9, FOXP3, CTLA4</i>) were more elevated in UC.
In addition, 9 genes previously associated with IBD contained SNPs with significant evidence for replication (P < 1.6 × 10<sup>-6</sup>): ADCY3, CXCR6, HLA-DRB1 to HLA-DQA1 (genome-wide significance on conditioning), IL12B,PTGER4, and TNC for IBD; IL23R, PTGER4, and SNX20 (in strong linkage disequilibrium with NOD2) for CD; and KCNQ2 (near TNFRSF6B) for UC.
Our study suggests that even after an established role of VA in inhibiting Th17 responses in mice models and humans, serum VA levels and disease activity do not correlate with FOXP3 and IL-23R expression in colonic mucosa of UC patients.
We confirmed the associations of 10 known UC risk loci in Koreans: rs76418789 in IL23R (combined P = 1.25 × 10), rs4728142 in IRF5 (combined P = 3.17 × 10), rs1830610 near JAK2 (combined P = 2.28 × 10), rs1555791 near TNFRSF14 (combined P = 1.62 × 10), rs880790 between IL10-IL19 (combined P = 3.73 × 10), rs10185424 between IL1R2-IL1R1 (combined P = 1.54 × 10), rs6478108 in TNFSF15 (combined P = 9.28 × 10), rs861857 between UBE2L3-YDJC (combined P = 3.05 × 10), rs1801274 in FCGR2A (discovery P = 1.54 × 10), and rs17085007 between GPR12-USP12 (discovery P = 3.64 × 10).
Specifically the G149R, V362I, and R381QIL23Rα chain variants are linked to protection against the development of Crohn disease and ulcerative colitis in humans.
In stratification analysis by ethnicity, we observed that the rs11209026 and rs7517847 polymorphism of IL-23R could protect against development of UC among Caucasian populations [rs11209026: dominant model (P=0.01, OR=0.69, 95%CI: 0.52-0.92); rs7517847: GG vs. TT (P=0.002, OR=0.69, 95%CI: 0.54-0.87); recessive model (P=0.004, OR=0.73, 95% CI: 0.59-0.90)]; the rs11209032 were associated with a greater risk for UC in Caucasian populations [dominant model (P=0.04, OR=1.13, 95%CI: 1.00-1.26)]; the rs1088967 were associated with a lower risk for UC among Asian populations [dominant model (P=0.04, OR=0.73, 95%CI: 0.54-0.99)].
The polymorphisms TLR2 (rs1816702), NFKB1 (rs28362491), TNFRSF1A (rs4149570), IL6R (rs4537545), IL23R (rs11209026) and PTPN22 (rs2476601) were associated with risk of CD and the polymorphisms TLR2 (rs1816702), TLR4 (rs1554973 and rs12377632), TLR9 (rs352139), LY96 (rs11465996), NFKBIA (rs696), TNFA (rs1800629), TNFRSF1A (rs4149570), IL10 (rs3024505), IL23R (rs11209026), PTPN22 (rs2476601) and PPARG (rs1801282) were associated with risk of UC.
In general, genes encoding cytokines are genetically polymorphic and polymorphisms in genes IL23R el IL17F were shown associated with susceptibility to Crohn's disease and ulcerative colitis which in their turn are considered as risk factors for developing colorectal cancer (CRC).
This study was performed in a group of patients with UC to test the possible role of IL23R SNPs in conferring susceptibility or protection against the disease.
Moreover, genome-wide association studies have revealed that variants of the gene encoding the IL-23 receptor, as well as the locus harboring the gene encoding the p40 chain, confer genetic risk for developing Crohn's disease (CD) and ulcerative colitis (UC).