The aim of this study was to investigate the association of TNFSF15 gene polymorphisms located in the promoter region, including rs6478108 (G/A -9706) and rs3810936 (G/A -15524) in Iranian patients with UC.
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).
Elevated levels of IL-4 (2.91-fold) and IL-13 (4.05-fold) mRNA were detected in the inflamed colon mucosa of patients with ulcerative colitis (UC), IFN-γ mRNA was upregulated (3.23-fold) in the inflamed colon mucosa of patients with Crohn's disease (CD), whereas upregulation of IL-17A and TL1A mRNA was present in the inflamed colon mucosa of patients with both CD and UC (IL-17A: 4.48-fold and 2.74-fold, TL1A: 3.19-fold and 3.22-fold, respectively) vs. control subjects.
The TNFSF15 gene has been associated with other inflammatory diseases affecting the colon such as medically refractory ulcerative colitis (UC), aggressive Crohn's disease (CD), and pouchitis after restorative proctocolectomy.
Focusing on TNFSF15instead of NOD2, we set out to evaluate whether combining serologic and genetic markers could distinguish between Crohn’s disease (CD) and ulcerative colitis (UC), and whether they could be used to stratify the disease behavior of Taiwanese CD patients.
We examined the association of seven single nucleotide polymorphisms (SNP) in the TNFSF15 gene with Crohn's disease (CD) and ulcerative colitis (UC) in the Indian population.
This meta-analysis indicated that most of the seven TNFSF15 polymorphisms (except for rs4263839) were risk factors contributed to CD and UC susceptibility.
Comparison of the MR-UC subjects with healthy controls confirmed the contribution of the major histocompatibility complex to severe UC (peak association: rs17207986, P = 1.4 × 10(-16)) and provided genome-wide suggestive association at the TNFSF15 (TL1A) locus (peak association: rs11554257, P = 1.4 × 10(-6)).
We identified multiple previously unreported or unconfirmed disease associations, including known CD loci (ICOSLG and TNFSF15) and T1D loci (TNFAIP3) that confer UC risk, known UC loci (HERC2 and IL26) that confer T1D risk and known UC loci (IL10 and CCNY) that confer CD risk.
Genome-wide association studies indicate that IL23R and five additional genes involved in Th17 differentiation (IL12B, JAK2, STAT3, CCR6 and TNFSF15) are associated with susceptibility to Crohn's disease and partly also to ulcerative colitis.
Of further interest, the haplotype frequency was in the opposite direction in our Jewish case-control panels (both CD and UC), leading us to conclude 1) that TNFSF15 is indeed an IBD susceptibility gene, and 2) the disease susceptibility is ethnic-specific.