Systematic search for single nucleotide polymorphisms in a lymphoid tyrosine phosphatase gene (PTPN22): association between a promoter polymorphism and type 1 diabetes in Asian populations

Genetic interactions and pleiotropy in metabolic diseases: Insights from a comprehensive GWAS analysis

This study offers insights into the genetic and biological connections between nine common metabolic diseases using data from genome-wide association studies. Our goal is to unravel the genetic interactions and biological pathways of these complex diseases, enhancing our understanding of their genetic architecture. We employed a range of advanced analytical techniques to explore the genetic correlations and shared genetic variants of these diseases. These methods include Linked Disequilibrium Score Regression, High-Definition Likelihood (HDL), genetic analysis combining multiplicity and annotation (GPA), two-sample Mendelian randomization analyses, analysis under the multiplicity-complex null hypothesis (PLACO), and Functional mapping and annotation of genetic associations (FUMA). Additionally, Bayesian co-localization analyses were used to examine associations of specific loci across traits. Our study discovered significant genomic correlations and shared loci, indicating complex genetic interactions among these metabolic diseases. We found several shared single nucleotide variants and risk loci, notably highlighting the role of the immune system and endocrine pathways in these diseases. Particularly, rs2476601 and its associated gene PTPN22 appear to play a crucial role in the connection between type 2 diabetes mellitus, hypothyroidism/mucous oedema and hypoglycaemia. These findings enhance our understanding of the genetic underpinnings of these diseases and open new potential avenues for targeted therapeutic and preventive strategies. The results underscore the importance of considering pleiotropic effects in deciphering the genetic architecture of complex diseases, especially metabolic ones.

Analysis of PTPN22 -1123 G>C, +788 G>A and +1858 C>T Polymorphisms in Patients with Primary Sjögren's Syndrome

BACKGROUND

Primary Sjögren's syndrome (pSS) is an autoimmune exocrinopathy characterized by lymphocytic infiltration, glandular dysfunction and systemic manifestations. Lyp protein is a negative regulator of the T cell receptor encoded by the tyrosine phosphatase nonreceptor-type 22 (PTPN22) gene. Multiple single-nucleotide polymorphisms (SNPs) in the PTPN22 gene have been associated with susceptibility to autoimmune diseases. This study aimed to investigate the association of PTPN22 SNPs rs2488457 (-1123 G>C), rs33996649 (+788 G>A), rs2476601 (+1858 C>T) with pSS susceptibility in Mexican mestizo subjects.

METHODS

One hundred fifty pSS patients and 180 healthy controls (HCs) were included. Genotypes of PTPN22 SNPs were identified by PCR-RFLP. PTPN22 expression was evaluated through RT-PCR analysis. Serum anti-SSA/Ro and anti-SSB/La levels were measured using an ELISA kit.

RESULTS

Allele and genotype frequencies for all SNPs studied were similar in both groups (p > 0.05). pSS patients showed 17-fold higher expression of PTNP22 than HCs, and mRNA levels correlated with SSDAI score (r² = 0.499, p = 0.008) and levels of anti-SSA/Ro and anti-SSB/La autoantibodies (r² = 0.200, p = 0.03 and r² = 0.175, p = 0.04, respectively). Positive anti-SSA/Ro pSS patients expressed higher PTPN22 mRNA levels (p = 0.008), with high focus scores by histopathology (p = 0.02). Moreover, PTPN22 expression had high diagnostic accuracy in pSS patients, with an AUC = 0.985.

CONCLUSIONS

Our findings demonstrate that the PTPN22 SNPs rs2488457 (-1123 G>C), rs33996649 (+788 G>A) and rs2476601 (+1858 C>T) are not associated with the disease susceptibility in the western Mexican population. Additionally, PTPN22 expression may be helpful as a diagnostic biomarker in pSS.

Genetic Polymorphism of PTPN22 in Autoimmune Diseases: A Comprehensive Review

It is known that the etiology and clinical outcomes of autoimmune diseases are associated with a combination of genetic and environmental factors. In the case of the genetic factor, the SNPs of the PTPN22 gene have shown strong associations with several diseases. The recent exploding numbers of genetic studies have made it possible to find these associations rapidly, and a variety of autoimmune diseases were found to be associated with PTPN22 polymorphisms. Proteins encoded by PTPN22 play a key role in the adaptative and immune systems by regulating both T and B cells. Gene variants, particularly SNPs, have been shown to significantly disrupt several immune functions. In this review, we summarize the mechanism of how PTPN22 and its genetic variants are involved in the pathophysiology of autoimmune diseases. In addition, we sum up the findings of studies reporting the genetic association of PTPN22 with different types of diseases, including type 1 diabetes mellitus, systemic lupus erythematosus, juvenile idiopathic arthritis, and several other diseases. By understanding these findings comprehensively, we can explain the complex etiology of autoimmunity and help to determine the criteria of disease diagnosis and prognosis, as well as medication developments.

Type 1 Diabetes and Autoimmune Thyroid Disease-The Genetic Link

Type 1 diabetes (T1D) and autoimmune thyroid disease (AITD) are the most frequent chronic autoimmune diseases worldwide. Several autoimmune endocrine and non-endocrine disorders tend to occur together. T1D and AITD often cluster in individuals and families, seen in the formation of autoimmune polyendocrinopathy (AP). The close relationship between these two diseases is largely explained by sharing a common genetic background. The HLA antigens DQ2 (DQA1*0501-DQB1*0201) and DQ8 (DQA1*0301-DQB1*0302), tightly linked with DR3 and DR4, are the major common genetic predisposition. Moreover, functional single nucleotide polymorphisms (or rare variants) of various genes, such as the cytotoxic T-lymphocyte- associated antigen (CTLA4), the protein tyrosine phosphatase non-receptor type 22 (PTPN22), the interleukin-2 Receptor (IL2Ra), the Vitamin D receptor (VDR), and the tumor-necrosis-factor-α (TNF) that are involved in immune regulation have been identified to confer susceptibility to both T1D and AITD. Other genes including cluster of differentiation 40 (CD40), the forkhead box P3 (FOXP3), the MHC Class I Polypeptide-Related Sequence A (MICA), insulin variable number of tandem repeats (INS-VNTR), the C-Type Lectin Domain Containing 16A (CLEC16A), the Erb-B2 Receptor Tyrosine Kinase 3 (ERBB3) gene, the interferon-induced helicase C domain-containing protein 1 (IFIH1), and various cytokine genes are also under suspicion to increase susceptibility to T1D and AITD. Further, BTB domain and CNC homolog 2 (BACH2), C-C motif chemokine receptor 5 (CCR5), SH2B adaptor protein 3 (SH2B3), and Rac family small GTPase 2 (RAC2) are found to be associated with T1D and AITD by various independent genome wide association studies and overlap in our list, indicating a strong common genetic link for T1D and AITD. As several susceptibility genes and environmental factors contribute to the disease aetiology of both T1D and AITD and/or AP subtype III variant (T1D+AITD) simultaneously, all patients with T1D should be screened for AITD, and vice versa.

Distinct HLA and non-HLA associations in different subtypes of ANCA-associated vasculitides in North India

AIM

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is an autoimmune disease characterized by necrotizing small vessel vasculitis that can affect various organs and present multiple symptoms. Susceptibility to AAV is multifactorial and most likely caused by an amalgamation of genetic and environmental factors. The aim of the present study was to explore the distribution of human leukocyte antigen (HLA)-DRB1/DQB1, protein tyrosine phosphatase non-receptor type 22 (PTPN22) and cytotoxic T-Lymphocyte-associated protein 4 (CTLA-4) polymorphisms in North Indian AAV patients and their associations with clinical and pathological characteristics associated with the disease.

METHODS

A total of 150 AAV patients and 150 healthy controls were recruited. The clinical classification showed 128 as granulomatosis with polyangiitis (GPA) and 21 as microscopic polyangiitis. Only 1 case of eosinophilic granulomatosis with polyangiitis was encountered, which was excluded from analysis. HLA-DRB1/DQB1 alleles were determined by polymerase chain reaction-sequence-specific primer (PCR-SSP) method and single nucleotide variant genotyping for CTLA-4 and PTPN22 was done by simple probe-based SNP arrays.

RESULTS

A significant predispositional association of DRB1*03 and DQB1*02 alleles, were confirmed in proteinase 3 (PR3)-AAV patients, whereas DRB1*10, DRB1*14 and DQB1*05 were protective alleles in AAV, PR3-AAV and GPA patients. GG genotype of CTLA-4 + 49A/G was increased in patients as compared to controls and showed an association with AAV, PR3-AAV and GPA patients.

CONCLUSION

The study indicated strong genetic associations were linked with PR3 antineutrophil cytoplasmic antibody specificity and it appears that PR3-AAV and MPO-AAV have distinct genetic backgrounds.

Thyroid Dysfunction and Diabetes Mellitus: Two Closely Associated Disorders

Thyroid dysfunction and diabetes mellitus are closely linked. Several studies have documented the increased prevalence of thyroid disorders in patients with diabetes mellitus and vice versa. This review critically discusses the different underlying mechanisms linking type 1 and 2 diabetes and thyroid dysfunction to demonstrate that the association of these two common disorders is unlikely a simple coincidence. We assess the current state of knowledge on the central and peripheral control of thyroid hormone on food intake and glucose and lipid metabolism in target tissues (such as liver, white and brown adipose tissue, pancreatic β cells, and skeletal muscle) to explain the mechanism linking overt and subclinical hypothyroidism to type 2 diabetes and metabolic syndrome. We also elucidate the common susceptibility genes and the pathogenetic mechanisms contributing to the autoimmune mechanism involved in the onset of type 1 diabetes mellitus and autoimmune thyroid disorders. An untreated thyroid dysfunction can impair the metabolic control of diabetic patients, and this association can have important repercussions on the outcome of both of these disorders. Therefore, we offer recommendations for the diagnosis, management, and screening of thyroid disorders in patients with diabetes mellitus, including the treatment of diabetic patients planning a pregnancy. We also discuss the major causes of failure to achieve an optimal management of thyroid dysfunction in diabetic patients and provide recommendations for assessing and treating these disorders during therapy with antidiabetic drugs. An algorithm for a correct approach of these disorders when linked is also provided.

Analysis of the rs2476601 polymorphism of PTPN22 in Mexican mestizo patients with leprosy

Leprosy, a human chronic granulomatous disease caused by Mycobacterium leprae (M. leprae), remains endemic in certain countries despite the use of multidrug therapy. Recently, several host genes modulating the immune responses to M. leprae infection have been suggested to influence the acquisition and clinical course of leprosy. Lymphoid protein tyrosine phosphatase, encoded by the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene, serves a negative regulatory role in T cell activation. The non-synonymous single-nucleotide polymorphism (SNP) rs2476601 (1858C>T) has been associated with autoimmune diseases. Here, the present study investigated if rs2476601 polymorphism was associated with leprosy in a Mexican mestizo population. Genotyping was performed in patients with leprosy (n=189) and control subjects (n=231) from regions with higher incidence of leprosy. Genotypic (P=0.44) and allelic frequencies (P=0.45) of the rs2476601 polymorphism were similar between patients and controls; genotypic frequencies were 91 vs. 94% for CC and 9 vs. 6% for CT, and the TT genotype was absent in both groups. Allelic frequencies were 96 vs. 97% for C, and 4 vs. 3% for T. In the same way, the genotypic (P=0.46) and allelic frequencies (P=0.47) from MB patients and controls were similar. In conclusion, there was a lack of association of the PTPN22 rs2476601 polymorphism with the development of leprosy, which suggests that this SNP was not a genetic risk factor for leprosy in the Mexican mestizo population studied.

Slowly Progressive Type 1 Diabetes Mellitus: Current Knowledge And Future Perspectives

Slowly progressive type 1 insulin-dependent diabetes mellitus (SPIDDM), sometimes referred to as latent autoimmune diabetes in adults (LADA), is a heterogeneous disease that is often confused with type 1 and type 2 diabetes. As a result, there were few diagnostic criteria for this disorder until 2012, when the Japan Diabetes Society established criteria that could be used in clinical practice. A primary question is whether pathologic markers for type 1 or type 2 diabetes are present in the pancreas of patients with SPIDDM, because the phenotype of SPIDDM is similar to both type 1 and type 2 diabetes. Recent studies clarified pathologic findings in the pancreas of patients with SPIDDM, which included T-cell-mediated insulitis, a marker of type 1 diabetes; pseudoatrophic islets (islets specifically devoid of beta cells), another hallmark of type 1 diabetes; and a lack of amylin (ie, islet amyloid polypeptide) deposition to the islet cells, a pathologic marker of type 2 diabetes. In terms of preventing the loss of beta-cell function in patients with SPIDDM, several studies have shown that some drugs, including dipeptidyl peptidase-4 inhibitors, are effective. There is an increased need for early diagnosis of SPIDDM to preserve beta-cell function. This review presents updated findings on the pathogenesis and immunologic findings of the affected pancreas, diagnostic markers, risk factors for progression of beta-cell dysfunction, epidemiology, clinical features, diagnostic strategies, prevention strategies, and clinical options for patients with SPIDDM.

Genetic differences between type 1 diabetes with and without other autoimmune diseases

BACKGROUND

Clusters of autoimmune diseases (ADs) are present in some people with type 1 diabetes. This clustering suggests the existence of common genetic backgrounds for abnormal autoimmunity in these individuals. However, the genetic differences between type 1 diabetes patients with and without other ADs are not well known.

METHODS

To investigate the clinical background and genetic differences between type 1 diabetes patients with and without other ADs, single nucleotide polymorphisms (SNPs) in the CTLA4, SUMO4, PTPN22, IRF5, STAT4, and BLK genes were analysed by using either a TaqMan assay or direct sequencing. The frequencies of alleles, genotypes of each gene, and the human leukocyte antigen (HLA) haplotype were analysed to investigate differences among 3 groups: type 1 diabetes with systemic ADs (group A), type 1 diabetes with other organ-specific ADs (group B), and type 1 diabetes without other ADs (group C).

RESULTS

The frequency of the C allele in the -1123G > C SNP in the PTPN22 gene promoter was significantly higher in groups A and B than in group C (P = .0258 and .0207, respectively). The allele frequencies of the other SNPs were comparable. The frequency of HLA DRB1*0405-DQB1*0401 was significantly higher in groups A and B than in group C (P = .021 and .0395, respectively).

CONCLUSIONS

The -1123G > C SNP in the PTPN22 gene promoter and HLA DRB1*0405-DQB1*0401 might influence the concurrence of systemic and organ-specific ADs in patients with type 1 diabetes.

PTPN22 1858 C/T Exon Polymorphism is not Associated with Graves' Disease in Kashmiri population

Background

Graves' disease (GD) is a multifactorial autoimmune disease with contribution from both genetic and epigenetic factors in its causation. Association of genetic factors and GD has been extensively studied. Gene "protein tyrosine phosphatase nonreceptor 22" (PTPN22) is an important immunoregulatory gene preventing hyper responsiveness of T cells by negatively regulating their signal transduction. Association of single-nucleotide polymorphism (SNP) 1858 C/T within PTPN22 with some autoimmune diseases has been described.

Methods

We aimed to analyze whether 1858 C/T SNP of PTPN22 gene has any association with GD in Kashmiri population. Polymerase chain reaction-restriction fragment length polymorphism was performed for genotyping 1858 C/T SNP in 135 patients with GD and 150 age- and gender-matched healthy controls.

Results

Among the patients with GD, the frequencies of PTPN22 1858 CC, CT, and TT genotypes were 97.7, 2.2, and 0%, respectively, whereas in healthy controls the frequencies of CC, CT genotypes were 100 and 0%, respectively. No significant association was found between PTPN22 1858 C/T SNP and patients with GD.

Conclusion

GD is not associated with PTPN22 1858 C/T SNP in Kashmiri population. Furthermore, 1858 C/T SNP in PTPN22 gene could be a part of variation in different ethnic populations across the globe.

Association of protein tyrosine phosphatase non-receptor type 22 gene functional variant C1858T, HLA-DQ/DR genotypes and autoantibodies with susceptibility to type-1 diabetes mellitus in Kuwaiti Arabs

The incidence of type-1 Diabetes Mellitus (T1DM) has increased steadily in Kuwait during recent years and it is now considered amongst the high-incidence countries. An interaction between susceptibility genes, immune system mediators and environmental factors predispose susceptible individuals to T1DM. We have determined the prevalence of protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene functional variant (C1858T; R620W, rs2476601), HLA-DQ and DR alleles and three autoantibodies in Kuwaiti children with T1DM to evaluate their impact on genetic predisposition of the disease. This study included 253 Kuwaiti children with T1DM and 214 ethnically matched controls. The genotypes of PTPN22 gene functional variant C1858T (R620W; rs2476601) were detected by PCR-RFLP method and confirmed by DNA sequencing. HLA-DQ and DR alleles were determined by sequence-specific PCR. Three autoantibodies were detected in the T1DM patients using radio-immunoassays. A significant association was detected between the variant genotype of the PTPN22 gene (C1858T, rs2476601) and T1DM in Kuwaiti Arabs. HLA-DQ2 and DQ8 alleles showed a strong association with T1DM. In T1DM patients which carried the variant TT-genotype of the PTPN22 gene, 93% had at least one DQ2 allele and 60% carried either a DQ2 or a DQ8 allele. Amongst the DR alleles, the DR3-DRB5, DR3-3, DR3-4 and DR4-4 showed a strong association with T1DM. Majority of T1DM patients who carried homozygous variant (TT) genotype of the PTPN22 gene had either DR3-DRB5 or DRB3-DRB4 genotypes. In T1DM patients who co-inherited the high risk HLA DQ, DR alleles with the variant genotype of PTPN22 gene, the majority were positive for three autoantibodies. Our data demonstrate that the variant T-allele of the PTPN22 gene along with HLA-DQ2 and DQ8 alleles constitute significant determinants of genetic predisposition of T1DM in Kuwaiti children.

The Potential Role of PTPN-22 C1858T Gene Polymorphism in the Pathogenesis of Type 1 Diabetes in Saudi Population

BACKGROUND

Recent investigations have reported an association between protein tyrosine phosphatase non-receptor type-22 (PTPN-22) gene polymorphism and susceptibility to the development of type 1 diabetes (T1D) in some populations and not in others. In this study, we aimed to investigate the association of PTPN-22 C1858T polymorphism with T1D in Saudi children.

METHODS

A cohort of 372 type 1 diabetic children and 372 diabetes-free subjects was enrolled in the current investigation. The PTPN-22 C1858T polymorphism was identified using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Our data showed that the frequency of CT and TT genotypes of PTPN-22 C1858T was higher in T1D children (17.7% and 4.3%, respectively) compared to healthy controls (4.8% and 1.6%, respectively), and both genotypes were statistically associated with T1D patients (OR = 4.4, 95% CI: 2.55-7.58, p < 0.001; and OR = 3.2, 95% CI: 1.23-8.28, p = 0.017, respectively). Moreover, the 1858T allele was significantly associated with T1D patients compared to the C allele (OR = 3.2, 95% CI: 1.59-6.88, p < 0.001). In addition, the T allele was significantly associated with elevated levels of HbA1c, anti-GAD, and anti-insulin antibodies (p < 0.001) and a lower concentration of C-peptide (p < 0.001) in T1D children.

CONCLUSION

The data presented here suggests that the T allele of PTPN-22 C1858T polymorphism might be a risk factor for T1D development in Saudi children.

The Protein Tyrosine Phosphatase Nonreceptor 22 (PTPN22) R620W Functional Polymorphism in Psoriasis

Background:

Psoriasis is a complex autoimmune disease caused by the interaction of genetic and environmental factors. PTPN22 gene polymorphism has been reported to affect psoriasis susceptibility; however, no data are available for Middle Eastern populations.

Objective:

The aim of this study was to investigate the association of PTPN22 (1858C/T) R620W polymorphism with psoriasis in a Saudi cohort.

Methods:

Saudi subjects (n = 306) including patients with psoriasis (n = 106) and matched controls (n = 200) were studied for PTPN22 variants using tetra-primer amplification refractory mutation system-polymerase chain reaction method. The frequencies of alleles and genotypes of PTPN22 (1858C/T) polymorphism were compared between patients and controls.

Results:

The frequency of CT genotype of PTPN22 (1858C/T) polymorphism was significantly higher, whereas that of CC genotype was lower in patients with psoriasis than in controls (P < .001, relative risk [RR] = 7.151). The homozygous genotype TT was absent in both the patients and healthy controls. The frequency of allele T encoding tryptophan (W) was significantly increased (P < .001, RR = 5.76), whereas that of allele C encoding arginine (R) decreased in psoriasis cases as compared with controls (P < .001, RR = 0.173) indicating that individuals carrying allele T are more susceptible to psoriasis than noncarriers.

Conclusions:

PTPN22 (1858C/T) polymorphism is positively associated with susceptibility of psoriasis in Saudis and can be developed as biomarker for evaluating psoriasis risk. However, further studies on PTPN22 polymorphism in larger samples from different geographical areas and ethnicity are warranted.

Association Between Protein Tyrosine Phosphatase Non-Receptor Type 22 (PTPN22) Polymorphisms and Risk of Ankylosing Spondylitis: A Meta-analysis

Background

Ankylosing spondylitis (AS) is a chronic autoimmune disease that involves the imbalance of peripheral tolerance possibly caused by the negative signal of activated T cells. The polymorphisms in the human protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene have been pointed out to be related to the pathogenesis of AS, but conclusions over this issue remain contradictory. We attempted to give a more precise conclusion about the effects of PTPN22 polymorphisms on AS risk by means of a meta-analysis.

Material/Methods

PubMed, Embase, Wanfang, and Chinese National Knowledge Infrastructure (CNKI) were searched for relevant studies published in the English or Chinese language. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated with a fixed- or random-effects model to evaluate the correlation between PTPN22 rs2488457, rs1217414, and rs2476601 polymorphisms and AS susceptibility. Sensitivity analysis was also carried out to detect the stability of the results.

Results

The present meta-analysis showed a positive correlation of both PTPN22 rs2488457 and rs1217414 polymorphisms with AS risk under CC vs. GG, CC + GC vs. GG, CC vs. GC + GG, allele C vs. allele G (OR=1.39, 95% CI=1.04–1.85, P=0.646; OR=1.29, 95% CI=1.03–1.62, P=0.426; OR=1.26, 95% CI=1.02–1.56, P=0.971; OR=1.20, 95% CI=1.05–1.38, P=0.571), and TT vs. CC and TT vs. CT + CC models (OR=3.83, 95% CI=1.11–13.24, P=0.196; OR=3.83, 95% CI=1.09–13.42, P=0.244), respectively.

Conclusions

PTPN22 rs2488457 and rs1217414 polymorphisms may be risk factors for AS occurrence.

Associations between PTPN22 and TLR9 polymorphisms and systemic lupus erythematosus: a comprehensive meta-analysis

Previous studies have explored the relationship of PTPN22 and TLR9 polymorphisms with systemic lupus erythematosus (SLE). In consideration of the population stratification, conflicting results and updating data, we conducted a comprehensive meta-analysis, which consists of a total of 17 research articles (9120 cases and 11,724 controls) for PTPN22 and 20 articles (including up to 2808 cases and 3386 controls) for TLR9. Significant association was verified between PTPN22 rs2476601 and SLE in the overall population (OR = 1.511 per T allele, 95% CI 1.338-1.706, P = 2.931 × 10^-11) and under dominant model of T allele (TT+CT vs. CC: OR = 1.531, 95% CI 1.346-1.742, P = 9.17 × 10^-11). Analysis after stratification by ethnicity indicated that PTPN22 rs2476601 was related to SLE in Americans (OR = 2.566, 95% CI 1.796-3.665, P = 2.219 × 10^-7), Europeans (OR = 1.399, 95% CI 1.261-1.552, P = 2.153 × 10^-10), and Africans (OR = 4.14, 95% CI 1.753-9.775, P = 1.0 × 10^-3). We did not observe any association between TLR9 polymorphisms (rs187084, rs352140, rs5743836 and rs352139) and SLE under any model, after excluding the data that were inconsistent with Hardy-Weinberg equilibrium (HWE). In summary, PTPN22 rs2476601 was significantly interrelated with SLE and contributed to susceptibility and development of SLE in Americans, Europeans and Africans in this analysis, while their relationship needs to be validated in Africans by future research.

Association of STAT4 and PTPN22 polymorphisms and their interactions with type-1 autoimmune hepatitis susceptibility in Chinese Han children

AIMS

To investigate the impact of signal transducer and activator of transcription 4 (STAT4) and the protein tyrosine phosphatase N22 (PTPN22) gene single nucleotide polymorphisms (SNPs), gene-gene interactions and haplotype on type-1 Autoimmune Hepatitis (AIH) risk.

RESULTS

Logistic regression analysis showed that type 1 AIH was significantly higher in carriers of T allele of rs7574865 than those with GG genotype (P- value less than 0.001), higher in carriers of C allele of rs7582694 than those with GG genotype (P- value < 0.001), and lower in carriers of T allele of rs2476601 than those with CC genotype (P- value < 0.001). GMDR model indicated a significant two-locus model (p = 0.0100) involving rs7582694 and rs2476601. Participants with GC or CC of rs7582694 and CC of rs2476601 genotype have the highest type 1 AIH risk (P- value < 0.001), after covariates adjustment. Haplotype containing the rs7582694-C and rs7574865-T alleles were associated with a statistically increased type 1 AIH risk (P < 0.001).

MATERIALS AND METHODS

Logistic regression was performed to investigate association between SNPs within STAT4 and PTPN22 gene and susceptibility to type 1 AIH. Generalized multifactor dimensionality reduction (GMDR) was used to screen the best interaction combinations among the 4 SNPs.

CONCLUSIONS

We conclude that rs7574865 and rs7582694 in STAT4 gene minor alleles, interaction between rs7582694 and rs2476601, and haplotype containing the rs7582694-C and rs7574865-T alleles are associated with increased type 1 AIH risk, but rs2476601 in PTPN22 gene minor allele is associated with decreased type 1 AIH risk.

Association of PTPN22 Gene Polymorphisms with Susceptibility to Juvenile Idiopathic Arthritis in Iranian Population

Juvenile idiopathic arthritis (JIA), the most common cause of chronic arthritis in children, is a complex immune-mediated disease with considerable long-term morbidity and mortality. According to previous studies, PTPN22 gene has been associated with JIA in several populations. In the present study, we attempted to determine the association of PTPN22 single nucleotide polymorphisms (SNPs) with susceptibility to JIA in Iranian population. Using the Real-time PCR allelic discrimination method, samples consisting of 55 unrelated patients and 93 healthy controls were genotyped. Using Fisher exact test or Chi-square test, genotypic and allelic frequencies were estimated. The results of our study indicated a significantly decreased association of rs1310182 (OR = 0.59, 95% CI = 0.36 -0.97, p = 0.037) with JIA. This association may indicate a protective role for rs1310182 SNP against JIA. More research would be needed to elucidate the mechanistic role of this association.

Association of PTPN22 Haplotypes (-1123G>C/+1858C>T) with Rheumatoid Arthritis in Western Mexican Population

Rheumatoid arthritis (RA) is an autoimmune disease characterized by the presence of antibodies against cyclic citrullinated peptide (anti-CCP), a consequence of the breakdown of immune tolerance. The lymphoid tyrosine phosphatase (Lyp) protein has significant effects on maintenance of peripheral immune tolerance. Two polymorphic variants (-1123G>C and +1858C>T) at PTPN22 gene that encodes this protein have been associated with autoimmune disorders and found in strong linkage disequilibrium in Caucasian population. We evaluated whether PTPN22 haplotypes (-1123G>C/+1858C>T) are associated with anti-CCP antibodies, as well as susceptibility to RA in a Western Mexican population. A total of 315 RA patients and 315 control subjects (CS) were included. The polymorphisms were genotyped by PCR-RFLP and the anti-CCP antibodies were determined by ELISA. The PTPN22 polymorphisms were in strong linkage disequilibrium (D' = 1.00 in CS). The susceptibility haplotype CT was significantly more frequent in RA patients than in CS (OR 2.18, 95% CI 1.15-4.16, p = 0.01). No association between haplotypes and anti-CCP antibodies levels was observed. In conclusion, this study confirmed that -1123G>C and +1858C>T PTPN22 polymorphisms are in strong linkage disequilibrium and the CT haplotype is a susceptibility marker to RA in Western Mexico. However, the PTPN22 haplotypes are not associated with anti-CCP antibodies.

C1858T Polymorphism of Protein Tyrosine Phosphatase Non-receptor Type 22 (PTPN22): an eligible target for prevention of type 1 diabetes?

INTRODUCTION

In type 1 diabetes (T1D), several genetic factors are associated to β-cell autoimmunity onset and clinical progression. HLA-genes play a major role in susceptibility and initiation of β-cell autoimmunity, whereas non-HLA genes may influence the destruction rate. Areas covered: Our review focuses on the possible role of the PTPN22 C1858 T variant as a prognostic factor, given its influence on disease variability. Moreover, we present the potential role of C1858 T as a target for tertiary prevention trials and new therapeutic strategies, such as the LYP inhibitors. We used PubMed for literature research; key words were 'PTPN22', 'C1858 T polymorphism', 'lymphoid-specific tyrosine phosphatase' and 'type 1 diabetes'. We selected publications between 2000 and 2016. Expert commentary: Current data suggest that PTPN22 can be a promising target for therapeutic interventions and identification of at-risk subjects in autoimmune diseases such as T1D.

Genetic Association of PTPN22 Polymorphisms with Autoimmune Hepatitis and Primary Biliary Cholangitis in Japan

Autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) are liver-specific autoimmune conditions that are characterized by chronic hepatic damage and often lead to cirrhosis and hepatic failure. Specifically, the protein tyrosine phosphatase N22 (PTPN22) gene encodes the lymphoid protein tyrosine phosphatase, which acts as a negative regulator of T-cell receptor signaling. A missense single nucleotide polymorphism (SNP) (rs2476601) in PTPN22 has been linked to numerous autoimmune diseases in Caucasians. In the present series, nine SNPs in the PTPN22 gene were analyzed in 166 patients with AIH, 262 patients with PBC, and 322 healthy controls in the Japanese population using TaqMan assays. Although the functional rs3996649 and rs2476601 were non-polymorphic in all subject groups, the frequencies of the minor alleles at rs1217412, rs1217388, rs1217407, and rs2488458 were significantly decreased in AIH patients as compared with controls (all Pc < 0.05). There were no significant relationships with PTPN22 SNPs in PBC patients. Interestingly, the AAGTCCC haplotype was significantly associated with resistance to both AIH (odds ratio [OR] = 0.58, P = 0.0067) and PBC (OR = 0.58, P = 0.0048). SNPs in the PTPN22 gene may therefore play key roles in the genetic resistance to autoimmune liver disease in the Japanese.

PTPN22 polymorphisms, but not R620W, were associated with the genetic susceptibility of systemic lupus erythematosus and rheumatoid arthritis in a Chinese Han population

OBJECTIVES

The present study aimed to detect a possible association between PTPN22 gene polymorphisms and rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in a Chinese Han population.

METHODS

7 PTPN22 SNPs were genotyped in 358 patients with RA and 713 patients with SLE, as well as 564 RA controls and 672 SLE controls by Restriction Fragment Length Polymorphism (RFLP). Association analyses were conducted on the whole data set. Significant relationships were also examined between clinical features and SNPs for both RA and SLE.

RESULTS

Rs2476601 was lack of polymorphism with a ⩽0.1% frequency in both SLE and RA patients and healthy controls in our study. The two SNPs rs1217414 and rs3811021 of PTPN22 shown strong association with both SLE (rs1217414T: padj = 6.07e-004, OR=0.57; rs3811021C: padj = 4.68e-005, OR=0.65) and RA (rs1217414T: padj = 2.01e-008, OR=0.26; rs3811021C: padj = 0.028, OR=0.70). And the rs3765598 revealed a strong risk factor for SLE (p=9.38e-009, padj = 6.57e-008, OR=1.93), but not for RA (p=0.48, OR=1.12). Moreover, protective haplotype ACTTC in RA (p=7.73e-016, padj = 5.51-015, OR[95%CI]=0.02[0.002-0.10]) and SLE (p=8.29e-018, padj = 5.80e-017, OR[95%CI]=0.11[0.06-0.21]) were observed. In addition, the distribution of risk haplotypes ACGTC and GCTTT in RA (ACGTC: p=0.0006, padj = 0.004, OR[95%CI]=1.85[1.29-2.63]; GCTTT: p=2.62e-005, padj = 1.85e-004, OR[95%CI]=2.40[1.57-3.65]) and SLE (ACGTC: p=0.0006, padj = 0.004, OR[95%CI]=1.85[1.29-2.63]; ACGTC: p=7.74e-011, padj = 6.81e-010, OR[95%CI]=2.21[1.12-3.34]; GCTTT: p=2.40[1.57-3.65], padj = 2.26e-006, OR[95%CI]=2.64[1.79-3.87]) were significant different from that in controls. Furthermore, significant association was observed between the PTPN22 rs3765598 and antinuclear antibodies 1 (ANA1) in SLE.

CONCLUSIONS

Our data provide strong evidence that the rs1217414 and rs3811021 in PTPN22 gene might be common protective factors contributed to SLE and RA susceptibility in the Chinese Han population. While, the rs3765598 might increase the genetic susceptibility of SLE, but not RA.

Association of PTPN22 gene polymorphisms with chronic hepatitis B virus infection in Chinese Han population

Lymphoid protein tyrosine phosphatase encoded by protein tyrosine phosphatase non-receptor 22 (PTPN22) gene plays an important regulatory role in T- and B-cell activation. This study investigated PTPN22 -1123G/C and intron 16 T/C polymorphisms in 372 patients with chronic hepatitis B virus (HBV) infection, 72 HBV infection resolvers and 273 healthy controls. Genotypic association tests between groups assuming codominant, dominant or log-additive genetic models were performed. In recessive model, PTPN22 -1123G/C genotype GG in healthy controls was more frequent than infection resolvers (P=0.037, OR=3.606, 95%CI=1.079-12.053) and this genotype in HBV patients was more frequent than resolvers although the difference was not significant (P=0.059). The PTPN22 intron 16 T/C genotype TC in cirrhosis patients was significantly higher than asymptomatic carriers (ASC) in codominant (P=0.028, OR=9.792, 95%CI=1.281-74.832) and overdominant (P=0.025, OR=10.142, 95%CI=1.332-77.214) models. This genotype in hepatocellular carcinoma (HCC) patients was significantly higher than ASC in codominant (P=0.034, OR=9.200, 95%CI=1.176-71.990) and overdominant (P=0.030, OR=9.677, 95%CI=1.241-75.442) models. These findings suggest that PTPN22 polymorphisms may predispose the chronicity or the development of cirrhosis and HCC in HBV infection.

Association between a gain-of-function variant of PTPN22 and rejection in liver transplantation

BACKGROUND

The protein tyrosine phosphatase nonreceptor 22 gene (PTPN22) encodes a strong T-cell regulator called lymphoid protein tyrosine phosphatase. Previously, PTPN22 was described as a susceptibility gene for autoimmunity because it contains single nucleotide polymorphisms (SNPs) associated with several autoimmune diseases. One SNP (rs2476601; 1858G>A) has emerged as a particularly potent risk factor for autoimmunity. We address the question whether PTPN22 polymorphisms are also associated with acute rejection after liver transplantation.

METHODS

We investigated the influence of six PTPN22 SNPs on the susceptibility to acute liver allograft rejection. Consequently, we carried out a retrospective study genotyping 345 German liver recipients at six SNP loci, which include rs2488457 (-1123G>C), rs33996649 (788C>T), rs2476601 (1858G>A), rs1310182 (-852A>G), rs1217388 (-2200G>A), rs3789604 (64434T>G). Our study enrolled 165 recipients who did not develop rejection, 123 who showed one rejection episode, and 57 patients who suffered from multiple acute rejections after transplantation.

RESULTS

The 1858A allele containing genotypes (GA+AA) and the 1858A allele had a significantly higher frequency in the group of patients with multiple rejection episodes (35.1% and 18.4%) compared to rejection-free patients (15.8% and 7.9%; P=0.022 and 0.023). In contrast, we could not detect any association between rejection and the other tested SNPs. Additionally, we identified one haplotype contributing to risk of multiple rejections, however, exhibiting no stronger impact than the 1858A allele alone.

CONCLUSION

We conclude that the 1858G>A SNP may confer susceptibility to multiple acute liver transplant rejections in the German population.

STAT4 rs7574865 G/T and PTPN22 rs2488457 G/C polymorphisms influence the risk of developing juvenile idiopathic arthritis in Han Chinese patients

Juvenile idiopathic arthritis (JIA) is a common autoimmune disease characterized by environmental influences along with several predisposing genes in the pathogenesis. The protein tyrosine phosphatase nonreceptor 22 (PTPN22) and signal transducer and activator of transcription factor 4 (STAT4) have been recognized as susceptibility genes for numerous autoimmune diseases. Associations of STAT4 rs7574865 G/T and PTPN22 (rs2488457 G/C and rs2476601 C/T) polymorphisms with JIA have repeatedly been replicated in several Caucasian populations. The aim of this study was to investigate the influence of three polymorphisms mentioned above on the risk of developing JIA in Han Chinese patients. Genotyping was performed on a total of 137 Chinese patients with JIA (JIA group) and 150 sex and age frequency-matched healthy volunteers (Control group). The single-nucleotide polymorphisms (SNP) were determined by using direct sequencing of PCR-amplified products. There were significant differences of PTPN22 rs2488457 G/C and STAT4 rs7574865 G/T polymorphisms between both groups. However, no significant difference was observed in distribution frequencies of PTPN22 rs2476601 polymorphism. The association with the PTPN22 rs2488457 G/C polymorphism remained significant in the stratifications by age at onset, ANA status, splenomegaly, lymphadenectasis and involvement joints. As with the STAT4 rs7574865 G/T polymorphisms, the enthesitis-related arthritis and presence of hepatomegaly had strong effect on the association. Our data strengthen STAT4 rs7574865 G/T and PTPN22 rs2488457 G/C polymorphisms as susceptibility factors for JIA.

Type 1 diabetes and polyglandular autoimmune syndrome: A review

Type 1 diabetes (T1D) is an autoimmune disorder caused by inflammatory destruction of the pancreatic tissue. The etiopathogenesis and characteristics of the pathologic process of pancreatic destruction are well described. In addition, the putative susceptibility genes for T1D as a monoglandular disease and the relation to polyglandular autoimmune syndrome (PAS) have also been well explored. The incidence of T1D has steadily increased in most parts of the world, especially in industrialized nations. T1D is frequently associated with autoimmune endocrine and non-endocrine diseases and patients with T1D are at a higher risk for developing several glandular autoimmune diseases. Familial clustering is observed, which suggests that there is a genetic predisposition. Various hypotheses pertaining to viral- and bacterial-induced pancreatic autoimmunity have been proposed, however a definitive delineation of the autoimmune pathomechanism is still lacking. In patients with PAS, pancreatic and endocrine autoantigens either colocalize on one antigen-presenting cell or are expressed on two/various target cells sharing a common amino acid, which facilitates binding to and activation of T cells. The most prevalent PAS phenotype is the adult type 3 variant or PAS type III, which encompasses T1D and autoimmune thyroid disease. This review discusses the findings of recent studies showing noticeable differences in the genetic background and clinical phenotype of T1D either as an isolated autoimmune endocrinopathy or within the scope of polyglandular autoimmune syndrome.

Association of TCR/CD3, PTPN22, CD28 and ZAP70 gene polymorphisms with type 1 diabetes risk in Tunisian population: family based association study

Type 1 diabetes (T1D) is caused by an immune-mediated destruction of the insulin-producing β-cells. Several studies support the involvement of T cell activation molecules in the pathogenesis of T1D. In order to underline the role of the genes involved in this activation pathway, we investigated, using the Sequenom MassARRAY platform, 45 single-nucleotide polymorphisms (SNPs) belonging to TCR/CD3, CD28, ZAP70, and PTPN22 genes in 59 T1D Tunisian families. In the current study, we identified an association with rs706 (Z score=2.782; p=0.005) of TCRβ gene. We also demonstrated that rs10918706 in the intron of the CD3z gene was associated with increased risk of T1D (Z score 2.137; p=0.032). In the same region, rs2949655 (Z score=2.101; p=0.035) and rs1214611 (Z score=4.036; p=0.00005) showed a genotype association with the risk of T1D. When haplotypes were constructed, GAA haplotype displayed significant association with T1D (Z score=2.135; p=0.032), while GGA haplotype (Z score=-1.988; p=0.046) was negatively associated with the disease. We also identified an association with rs3181096 (Z score=2.177; p=0.029), rs17695937 (Z score =2.111; p=0.034) and rs2488457 (Z score=2.219; p=0.026), respectively of CD28, ZAP70 and PTPN22 genes. In addition, our results suggest a significant effect on T1D susceptibility for AC (Z score=2.30; p=0.02) and CTGGC (Z score=2.309, p=0.02) haplotypes of ZAP70 and PTPN22 genes, respectively. While, the GTCT (Z score=-2.114, p=0.034) and CTAGG (Z score=-2.121, p=0.033) haplotypes of CD28 and PTPN22 genes, may confer protection against T1D. These findings confirm the role of PTPN22 and CD28 involved in the T cell activation pathway in the development of T1D in Tunisian families. Interestingly, ZAP70 and TCRβ/CD3z seem to contribute to the susceptibility to the disease in our population. However, this finding has to be confirmed in further studies.

Association Between PTPN22 Polymorphisms and IgE Responses to Staphylococcal Superantigens in Chronic Urticaria

Protein tyrosine phosphatase-22 (PTPN22) gene encodes lymphoid-specific tyrosine phosphatase (Lyp), an inhibitor of T cell activation. A polymorphism of the PTPN22 gene has been found to be associated with chronic urticaria (CU). We investigated the associations between PTPN22 gene polymorphisms and CU characteristics, including serum specific IgE antibodies response to toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxin A (SEA). CU patients (n=409) and normal healthy controls (n=388) were enrolled in the present study. Serum specific IgE to TSST-1 and SEA were measured by ImmunoCAP®. Five PTPN22 single nucleotide polymorphisms, -1123G>C, 1858C>T, 13145A>G, 14943C>T, and 20628A>G, were genotyped. There were no significant differences in genotype or haplotype frequencies of these polymorphisms between the 2 groups. CU patients carrying the GG genotype at 20628A>G (P=0.035) or haplotype 3 [GGG] (P=0.047) had a significantly higher prevalence of serum specific IgE to TSST-1 compared to non-carriers. Similarly, CT/TT genotype at 14943C>T had a significantly higher prevalence of serum specific IgE to SEA (P=0.045). The findings suggest that the PTPN22 gene polymorphisms at 20628A>G and 14943C>T may enhance serum specific IgE responses to TSST-1 and SEA, which may contribute to CU pathogenesis.

Protein Tyrosine Phosphatase Non-receptor 22 Gene C1858T Polymorphism in Patients with Coexistent Type 2 Diabetes and Hashimoto's Thyroiditis

BACKGROUND

A protein tyrosine phosphatase non-receptor type 22 (PTPN22) C1858T gene polymorphism has been reported to be associated with both Type 2 diabetes mellitus (T2DM) and Hashimoto's thyroiditis (HT) separately. However, no study has been conducted to explore the C1858T polymorphism in T2DM and HT coexistent cases up to now.

AIMS

The study aimed to determine whether a relationship exists or not between the PTPN22 C1858T polymorphism and this coexistent patient group.

STUDY DESIGN

Case-control study.

METHODS

Peripheral blood samples from 135 T2DM patients, 102 patients with coexistent T2DM+HT, 71 HT patients and 135 healthy controls were collected into ethylenediaminetetraacetic acid (EDTA) anticoagulant tubes and genomic DNA was extracted. The PTPN22 C1858T polymorphism was analyzed using polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) methods.

RESULTS

Statistically significant differences were not observed between the patient and control groups. This study demonstrated a statistically significant association between both the CT genotype and the T allele in the female patient group with coexistent T2DM+HT (CT genotype: p=0.04; T allele: p=0.045) with a statistically significant association between the CT genotype and the mean values of body mass index (BMI) and free T3 levels (FT3) (BMI: p=0.044 and FT3: p=0.021) that was detected in the patient group with coexistent T2DM+HT. The minor genotype TT was observed in none of the groups in this study. The CT genotype frequency was [number (frequency): 5 (3.8%), 7 (6.86%), 5 (7.04%), 3 (2.22%), while the T allele frequency was 5 (1.86%), 7 (3.44%), 5 (3.53%) and 3 (1.12%)] in the T2DM, T2DM+HT, HT and control groups, respectively.

CONCLUSION

Our data suggest that the PTPN22 1858T allele and the CT genotype are associated with increased risk in female patients for coexistent T2DM+HT. The CT genotype was associated with high mean BMI and free T3 values in the patient group with coexistent T2DM+HT. These results demonstrate that T allele carriers were more often in the T2DM+HT group than in the T2DM group. Therefore, the combination of T2DM and HT with female gender may have higher T allele carriage in comparison to the T2DM only and male groups.

Genetics and pathogenesis of type 1 diabetes: prospects for prevention and intervention

Type 1 diabetes is etiologically a multifactorial disease caused by a complex interaction of genetic and environmental factors, with the former consisting of multiple susceptibility genes. Identification of genes conferring susceptibility to type 1 diabetes would clarify etiological pathways in the development and progression of type 1 diabetes, leading to the establishment of effective methods for prevention and intervention of the disease. Among multiple susceptibility genes, HLA and INS are particularly important because of their contribution to tissue specificity in the autoimmune process. DRB1*04:05-DQB1*04:01 is associated with autoimmune type 1 diabetes, idiopathic fulminant type 1 diabetes and anti-islet autoimmunity in autoimmune thyroid diseases, suggesting that this haplotype is associated with beta-cell specificity in autoimmune diseases. Genes involved in the expression of insulin in the thymus contribute to beta-cell-specific autoimmune mechanisms in type 1 diabetes. These genes and pathways are important targets for tissue-specific prevention and intervention of type 1 diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00176.x, 2011).

A functional variant of PTPN22 confers risk for Vogt-Koyanagi-Harada syndrome but not for ankylosing spondylitis

BACKGROUND

Protein tyrosine phosphatase non-receptor 22 (PTPN22) is a key negative regulator of T lymphocytes and has emerged as an important candidate susceptibility factor for a number of immune-related diseases. This study aimed to examine the predisposition of PTPN22 SNPs to Vogt-Koyanagi-Harada (VKH) syndrome and acute anterior uveitis (AAU) associated with ankylosing spondylitis (AS).

METHODS

A total of 1005 VKH syndrome, 302 AAU+AS+ patients and 2010 normal controls among the Chinese Han population were enrolled in the study. Genotyping, PTPN22 expression, cell proliferation, cytokine production and cell activation were examined by PCR-RFLP, Real-time PCR, CCK8, ELISA and Flow cytometry.

RESULTS

The results showed significantly increased frequencies of the rs2488457 CC genotype and C allele but a decreased frequency of the GG genotype in VKH syndrome patients (PBonferroni correction (Pc) = 3.47×10(-7), OR = 1.54; Pc = 3.83×10(-8), OR = 1.40; Pc = 6.35×10(-4), OR = 0.62; respectively). No significant association of the tested SNPs with AAU+AS+ patients was observed. Functional studies showed a decreased PTPN22 expression, impaired cell proliferation and lower production of IL-10 in rs2488457 CC cases compared to GG cases (Pc = 0.009, Pc = 0.015 and Pc = 0.048 respectively). No significant association was observed concerning T cell activation and rs2488457 genotype.

CONCLUSIONS

The study showed that a functional variant of PTPN22 confers risk for VKH syndrome but not for AAU+AS+ in a Chinese Han population, which may be due to a modulation of the PTPN22 expression, PBMC proliferation and IL-10 production.

A novel single nucleotide polymorphism in the protein tyrosine phosphatase N22 gene (PTPN22) is associated with Type 1 diabetes in a Chinese population

AIMS

To examine single nucleotide polymorphisms in the protein tyrosine phosphatase N22 gene (PTPN22) and to study their association with Type 1 diabetes in a Chinese cohort.

METHODS

Three hundred and sixty-four young patients with Type 1 diabetes and 719 healthy children were included in this case-controlled study. The genotypes of rs1217385, rs2488457 (-1123C>G), rs1217414, rs1217419, rs3765598 and rs2476601 (1858C>T) in the PTPN22 gene were determined using the SNaPshot method. Alleles, genotypes and haplotype frequencies were compared between patients with Type 1 diabetes and healthy control subjects. The association between single nucleotide polymorphisms and clinical traits/autoantibody status was also analysed.

RESULTS

The single nucleotide polymorphism, rs1217419, located in the second intron of the PTPN22 gene was associated with Type 1 diabetes (odds ratio 1.5, 95% CI 1.14-1.97, P = 0.003). An additional single nucleotide polymorphism, rs1217385, was also associated with Type 1 diabetes; however, the association was secondary to that of rs1217419. The previously reported single nucleotide polymorphism that is associated with Type 1 diabetes (-1123G>C) had only marginal association with Type 1 diabetes in our study. A marginal association was also identified between -1123G>C and glutamic acid decarboxylase autoantibody positivity in patients with Type 1 diabetes. There was no association between the single nucleotide polymorphism 1858C>T and Type 1 diabetes in our studied cohort.

CONCLUSIONS

Our study confirmed that PTPN22 is a gene that contributes to Type 1 diabetes susceptibility. The primary association occurs with single nucleotide polymorphism rs1217419 and there is clear heterogeneity of the association between PTPTN22 polymorphisms and Type 1 diabetes in a Chinese population compared with other populations.

Tyrosine phosphatase PTPN22: multifunctional regulator of immune signaling, development, and disease

Inheritance of a coding variant of the protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene is associated with increased susceptibility to autoimmunity and infection. Efforts to elucidate the mechanisms by which the PTPN22-C1858T variant modulates disease risk revealed that PTPN22 performs a signaling function in multiple biochemical pathways and cell types. Capable of both enzymatic activity and adaptor functions, PTPN22 modulates signaling through antigen and innate immune receptors. PTPN22 plays roles in lymphocyte development and activation, establishment of tolerance, and innate immune cell-mediated host defense and immunoregulation. The disease-associated PTPN22-R620W variant protein is likely involved in multiple stages of the pathogenesis of autoimmunity. Establishment of a tolerant B cell repertoire is disrupted by PTPN22-R620W action during immature B cell selection, and PTPN22-R620W alters mature T cell responsiveness. However, after autoimmune attack has initiated tissue injury, PTPN22-R620W may foster inflammation through modulating the balance of myeloid cell-produced cytokines.

Association of PTPN22 gene (rs2488457) polymorphism with ulcerative colitis and high levels of PTPN22 mRNA in ulcerative colitis

PURPOSE

Our aims were to evaluate protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene polymorphisms in ulcerative colitis (UC) and explore PTPN22 mRNA levels in colonic biopsies of UC patients in central China.

METHODS

A total of 165 Chinese UC patients and 300 healthy controls were enrolled in this study. PTPN22 -1123G/C, +1858C/T, and +788G/A polymorphisms were genotyped by PCR-restriction fragment length polymorphism method. PTPN22 mRNA expressions in colonic biopsies and serum C-reactive protein (CRP) levels were determined by quantitative PCR and immunonephelometry, respectively.

RESULTS

The frequency of C carrier was higher in UC patients than in healthy controls (66.7 vs. 53.3%, P = 0.005, odds ratios = 1.75, 95% CI 1.18-2.60) and associated with extensive colitis (P = 0.029). PTPN22 mRNA levels were elevated in UC patients than in healthy controls (P < 0.001). Among UC patients, PTPN22 mRNA expression levels were higher in biopsies of inflamed colonic tissue compared with noninflamed tissue (P < 0.001) and were correlated with CRP levels (r = 0.578, P < 0.001). PTPN22 mRNA expression levels were elevated in extensive colitis compared to proctitis (P = 0.008) and to left-sided colitis (P = 0.029) and were higher in moderate and severe disease than in mild disease (P = 0.005).

CONCLUSIONS

Our study showed the potential association between PTPN22 -1123G/C polymorphism and UC in central China. PTPN22 mRNA levels were highly expressed in UC, especially in active disease, and were correlated with CRP levels, disease location, and disease severity in UC patients.

PTPN22 gene polymorphism in Egyptian alopecia areata patients and its impact on response to diphencyprone immunotherapy

PTPN22 1858C>T gene polymorphism has been associated with several autoimmune disorders including alopecia areata. The aim of the current study was to investigate the effect of the inherited genetic polymorphism 1858C>T of PTPN22 gene on the predisposition to severe forms of alopecia areata and its effect on the response to DPC treatment. To achieve our aim, PTPN22 1858C>T genotyping was performed by PCR-based restricted fragment length polymorphism (PCR-RFLP) analysis. The study included 103 Egyptian patients with extensive alopecia areata treated by DPC. Hundred healthy age and sex matched blood donors were included in the current study as a control group. Results of genotyping showed that PTPN22 CT and TT mutant genotypes were significantly higher in AA patients compared to controls and conferred increase risk of AA (OR=2.601, 95% CI=1.081-6.255). Statistical comparison between AA patients with wild and mutant genotypes revealed that the duration of the illness was significantly longer in those harboring the mutant genotypes. Moreover, the association of other autoimmune diseases as atopy and diabetes mellitus was higher in patients with mutant genotypes. Furthermore, PTPN22 1858C>T genetic polymorphism did not affect the patients' response to DPC immunotherapy.

Association between the PTPN22 1858C/T gene polymorphism and tuberculosis resistance

Previous studies identified the functional polymorphism 1858C/T in the gene PTPN22 in association with several autoimmune diseases and with resistance to tuberculosis (TB). This study is the first to investigate the association between pulmonary TB and the PTPN22 1858C/T polymorphism in the Brazilian Amazon. We conducted a case-control study involving a group of 413 individuals, comprised of 208TB carriers and 205 controls. No significant association between the PTPN22 1858T allele frequency in controls (2.4%) and TB carriers (2.7%, p=0.982, odds ratio (OR)=0.89, 95% confidence interval=0.37-2.13) was identified in the Brazilian Amazon population. An additional evaluation by meta-analysis, however, suggested a protective role of the T allele in relation to TB (pooled OR=0.44, p=0.011). These results suggest that the PTPN22 1858T allele serves as a protective genetic factor for TB in those individuals who carry this minor allele.

The putative role of the C1858T polymorphism of protein tyrosine phosphatase PTPN22 gene in autoimmunity

Autoimmune diseases represent a heterogeneous group of conditions whose incidence is increasing worldwide. This has stimulated studies on their etiopathogenesis, derived from a complex interaction between genetic and environmental factors, in order to improve prevention and treatment of these diseases. An increasing amount of epidemiologic investigations has associated the presence of the C1858T polymorphism in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene to the onset of several autoimmune diseases including insulin-dependent diabetes mellitus (Type 1 diabetes). PTPN22 encodes for the lymphoid tyrosine phosphatase Lyp. This belongs to non-receptor-type protein tyrosine phosphatases involved in lymphocyte activation and differentiation. In humans, Lyp may have a role in the negative regulation of T cell receptor signaling. The single nucleotide polymorphism C1858T encodes for a more active phosphatase Lyp R620W. This has the ability to induce a higher negative regulation of T cell receptor signaling. Thus, C1858T could play an important role at the level of thymocyte polarization and escape of autoreactive T lymphocytes, through the positive selection of otherwise negatively selected autoimmune T cells. In this review we discuss the physiological role exerted by the PTPN22 gene and its encoded Lyp product in lymphocyte processes. We highlight the pathogenic significance of the C1858T PTPN22 polymorphism in human autoimmunity with special reference to Type 1 diabetes. Recently the genetic variation in PTPN22 was shown to induce altered function of T and B-lymphocytes. In particular BCR signaling defects and alterations in the B cell compartment were reported in T1D patients. We finally speculate on the possible development of novel therapeutic treatments in human autoimmunity aiming to selectively target the variant Lyp protein in autoreactive T and B lymphocytes.