We hypothesized earlier that Single Nucleotide Polymorphisms (SNPs) in the negative regulators <i>Protein Tyrosine Phosphatase Non-receptor type 2 and 22</i> (<i>PTPN2/22)</i> lead to a dysregulated immune response, susceptibility to environmental triggers, and continued apoptosis as seen in chronic inflammation in RA and CD.
Non-coding single nucleotide polymorphisms that repress PTPN2 expression have been linked with the development of type 1 diabetes, rheumatoid arthritis and Crohn's disease.
The single nucleotide polymorphism (SNP) rs1893217 within the gene locus encoding protein tyrosine phosphatase non-receptor type 2 (PTPN2) results in a dysfunctional PTPN2 protein is associated with Crohn's disease (CD) and exists in perfect linkage disequilibrium with the CD- and ulcerative colitis (UC)-associated PTPN2 SNP rs2542151.
Our data demonstrate that dysfunction of PTPN2 results in aberrant T-cell differentiation and intestinal dysbiosis similar to those observed in human CD.
The PTPN2 gene mutation in T1D patients play a direct role in the destruction of beta cells while in Crohn's disease patients, it modulates the innate immune responses.
We confirmed 6 previously reported loci in Caucasian: GPR35 at 2q37 (rs3749172; P = 5.30 × 10, odds ratio [OR] = 1.45), ZNF365 at 10q21 (rs224143; P = 2.20 × 10, OR = 1.38), ZMIZ1 at 10q22 (rs1250569; P = 3.05 × 10, OR = 1.30), NKX2-3 at 10q24 (rs4409764; P = 7.93 × 10, OR = 1.32), PTPN2 at 18p11 (rs514000; P = 9.00 × 10, OR = 1.33), and USP25 at 21q11 (rs2823256; P = 2.49 × 10, OR = 1.35), bringing the number of known CD loci (including 3 in the HLA) in Koreans to 15.
In stage 3 we studied the relationship between PTPN2 protein expression and mucosal inflammation and carried out in silico analyses to study the functional characteristics of the PTPN2CD-associated SNPs.
Recent studies associated variants within the gene loci, encoding protein tyrosine phosphatase nonreceptor type 2 (PTPN2), and autophagy genes, such as autophagy-related 16-like 1 (ATG16L1), with chronic inflammatory disorders, such as Crohn's disease (CD).
These data identify an important functional role for PTPN2 as a protector of the intestinal epithelial barrier and provide clues as to how PTPN2 mutations may contribute to the pathophysiology of CD.
Epistasis analysis showed weak epistasis between the ATG16L1 SNP rs2241879 and PTPN2 SNP rs2542151 (p = 0.024) in CD and between ATG16L1 SNP rs4663396 and PTPN2 SNP rs7234029 (p = 4.68×10⁻³) in UC.
These results suggest that PTPN2 may have an important role in CD pathogenesis and may represent a potential diagnostic and therapeutic target for IBD.
The study indicates that IL23R-rs11805303 and PTPN2-rs2542151 might contribute to the development of UC and NOD2-P268S might be involved in the etiology of CD in the Chinese Han population.
Though samples from patients with active ulcerative colitis (UC) revealed more PTPN2 protein than non-IBD patients and patients with UC in remission, their PTPN2 expression was lower than in active CD.
Colon-only CD (n = 228) was compared with healthy controls: three of six UC SNPs (in MST1, HLA-DRA, and IL-23R) and 11 of 34 CD SNPs: in IRGM, NOD2 (rs2066845), CCNY, MST1, IL23R, PTPN22, C11orf30, ZNF365, PTPN2, PSMG1, and rs1456893 were significantly associated.
A meta-analysis of genome-wide association scans identifies IL18RAP, PTPN2, TAGAP, and PUS10 as shared risk loci for Crohn's disease and celiac disease.
In this sample, we were able to confirm an association between CD and PTPN2 (genotypic P = 0.019 and allelic P = 0.011), and phenotypic analysis showed an association of this SNP with late age at first diagnosis, inflammatory and penetrating CD behaviour, requirement of bowel resection and being a smoker at diagnosis.