Protein tyrosine phosphatases in T cell physiology

Cationic Polyethyleneimine (PEI)–Gold Nanocomposites Modulate Macrophage Activation and Reprogram Mouse Breast Triple-Negative MET-1 Tumor Immunological Microenvironment

Nanomedicines based on inorganic nanoparticles have grown in the last decades due to the nanosystems’ versatility in the coating, tuneability, and physical and chemical properties. Nonetheless, concerns have been raised regarding the immunotropic profile of nanoparticles and how metallic nanoparticles affect the immune system. Cationic polymer nanoparticles are widely used for cell transfection and proved to exert an adjuvant immunomodulatory effect that improves the efficiency of conventional vaccines against infection or cancer. Likewise, gold nanoparticles (AuNPs) also exhibit diverse effects on immune response depending on size or coatings. Photothermal or photodynamic therapy, radiosensitization, and drug or gene delivery systems take advantage of the unique properties of AuNPs to deeply modify the tumoral ecosystem. However, the collective effects that AuNPs combined with cationic polymers might exert on their own in the tumor immunological microenvironment remain elusive. The purpose of this study was to analyze the triple-negative breast tumor immunological microenvironment upon intratumoral injection of polyethyleneimine (PEI)–AuNP nanocomposites (named AuPEI) and elucidate how it might affect future immunotherapeutic approaches based on this nanosystem. AuPEI nanocomposites were synthesized through a one-pot synthesis method with PEI as both a reducing and capping agent, resulting in fractal assemblies of about 10 nm AuNPs. AuPEI induced an inflammatory profile in vitro in the mouse macrophage-like cells RAW264.7 as determined by the secretion of TNF-α and CCL5 while the immunosuppressor IL-10 was not increased. However, in vivo in the mouse breast MET-1 tumor model, AuPEI nanocomposites shifted the immunological tumor microenvironment toward an M2 phenotype with an immunosuppressive profile as determined by the infiltration of PD-1-positive lymphocytes. This dichotomy in AuPEI nanocomposites in vitro and in vivo might be attributed to the highly complex tumor microenvironment and highlights the importance of testing the immunogenicity of nanomaterials in vitro and more importantly in vivo in relevant immunocompetent mouse tumor models to better elucidate any adverse or unexpected effect.

Effect of PTPN22, FAS/FASL, IL2RA and CTLA4 genetic polymorphisms on the risk of developing alopecia areata: A systematic review of the literature and meta-analysis

Objectives

Genetic association studies on alopecia areata (AA) performed in various populations have shown heterogeneous results. The aim of the current review was to synthesize the results of said studies to estimate the impact of FAS, FASL, PTPN22, CTLA4 and IL2RA gene polymorphisms on AA susceptibility.

Design

A systematic literature search was conducted in the Medline, Web of Science, Scopus, EMBASE and LILACS databases. Studies published up to June 2020 were included. The results available in the grey literature including the Open Grey and Google Scholar databases were also used. The texts of potentially related studies were screened by individual reviewers. Evidence of publication bias was assessed using the Newcastle-Ottawa scale and the quality of evidence was assessed using the GRADE system. The quantitative synthesis was performed using the fixed effect model.

Results

Out of 1784 articles, we identified 18 relevant articles for the qualitative synthesis and 16 for the quantitative synthesis. In a study of rs2476601 polymorphism of PTPN22 gene, including 1292 cases and 1832 controls, a correlation was found with the risk of developing AA in the allelic model (OR1.49 [95% C:1.13–1.95]), the heterozygous codominant (OR1.44 [95% CI:1:19–1.76]) and dominant model (OR1.43 [95% CI:1.18–1.73]). No association was found between the presence of FASL, PTPN22, CTLA and IL2RA gene polymorphisms with AA susceptibility.

Conclusions

The results suggest that the T allele of the single nucleoid polymorphism (SNP) rs2476601 in PTPN22 gene is a risk factor for developing alopecia areata. However, more robust studies defining the ethnic background of the population of origin are required, so that the risk identified in the present study can be validated. Additionally, a greater number of studies is necessary to evaluate the role of the FAS, FASL, PTPN22, CTLA4 and IL2RA genetic variants, given the heterogenous results found in the literature.

Rare Variants of Putative Candidate Genes Associated With Sporadic Meniere's Disease in East Asian Population

Objectives: The cause of Meniere's disease (MD) is unclear but likely involves genetic and environmental factors. The aim of this study was to investigate the genetic basis underlying MD by screening putative candidate genes for MD.

Methods: Sixty-eight patients who met the diagnostic criteria for MD of the Barany Society were included. We performed targeted gene sequencing using next generation sequencing (NGS) panel composed of 45 MD-associated genes. We identified the rare variants causing non-synonymous amino acid changes, stop codons, and insertions/deletions in the coding regions, and excluded the common variants with minor allele frequency >0.01 in public databases. The pathogenicity of the identified variants was analyzed by various predictive tools and protein structural modeling.

Results: The average read depth for the targeted regions was 1446.3-fold, and 99.4% of the targeted regions were covered by 20 or more reads, achieving the high quality of the sequencing. After variant filtering, annotation, and interpretation, we identified a total of 15 rare heterozygous variants in 12 (17.6%) sporadic patients. Among them, four variants were detected in familial MD genes (DTNA, FAM136A, DPT), and the remaining 11 in MD-associated genes (PTPN22, NFKB1, CXCL10, TLR2, MTHFR, SLC44A2, NOS3, NOTCH2). Three patients had the variants in two or more genes. All variants were not detected in our healthy controls (n = 100). No significant differences were observed between patients with and without a genetic variant in terms of sex, mean age of onset, bilaterality, the type of MD, and hearing threshold at diagnosis.

Conclusions: Our study identified rare variants of putative candidate genes in some of MD patients. The genes were related to the formation of inner ear structures, the immune-associated process, or systemic hemostasis derangement, suggesting the multiple genetic predispositions in the development of MD.

Association of PTPN22 1858C/T Polymorphism with Autoimmune Diseases: A Systematic Review and Bayesian Approach

The 1858T allele in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) locus shows one of the strongest and most consistent genetic associations with autoimmune diseases. We synthesized all meta-analyses reporting a genetic association of the PTPN22 1858T C/T polymorphism with autoimmune diseases. This work examined their validity to discover false positive results under Bayesian methods. We conducted a PubMed search to identify relevant publications and extracted the respective results, published until 30 November 2018. In observational studies, the associations of 1858 C/T genetic variant were noteworthy for 12 autoimmune or autoimmunity-related diseases (rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, juvenile idiopathic arthritis, Crohn's disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, vitiligo, Graves' disease, myasthenia gravis, Addison's disease, giant cell arteritis, and endometriosis). In contrast, we could not confirm the noteworthiness for eight diseases (systemic sclerosis, psoriasis, Behçet's disease, autoimmune thyroid disease, alopecia areata, Sjögren's syndrome, inflammatory bowel disease, and ankylosing spondylitis). From the meta-analysis of genome-wide association studies (GWAS) with a p-value < 5 × 10^-8, findings verified noteworthiness for all autoimmune diseases (psoriatic arthritis, myasthenia gravis, juvenile idiopathic arthritis and rheumatoid arthritis). The results from meta-analysis of GWAS showing a p-value ranging between 0.05 and 5 × 10^-8 were noteworthy under both Bayesian approaches (ANCA-associated vasculitis, type 1 diabetes mellitus, giant cell arteritis and juvenile idiopathic arthritis). Re-analysis of observational studies and GWAS by Bayesian approaches revealed the noteworthiness of all significant associations observed by GWAS, but noteworthiness could not be confirmed for all associations found in observational studies.

Protein tyrosine phosphatases in cardiac physiology and pathophysiology

More than any other organ, the heart is particularly sensitive to gene expression deregulation, often leading in the long run to impaired contractile performances and excessive fibrosis deposition progressing to heart failure. Recent investigations provide evidences that the protein phosphatases (PPs), as their counterpart protein kinases, are important regulators of cardiac physiology and development. Two main groups, the protein serine/threonine phosphatases and the protein tyrosine phosphatases (PTPs), constitute the PPs family. Here, we provide an overview of the role of PTP subfamily in the development of the heart and in cardiac pathophysiology. Based on recent in silico studies, we highlight the importance of PTPs as therapeutic targets for the development of new drugs to restore PTPs signaling in the early and late events of heart failure.

Novel missense mutation in PTPN22 in a Chinese pedigree with Hashimoto's thyroiditis

BACKGROUND

Hashimoto's thyroiditis is a complex autoimmune thyroid disease, the onset of which is associated with environmental exposures and specific susceptibility genes. Its incidence in females is higher than its incidence in males. Thus far, although some susceptibility loci have been elaborated, including PTPN22, FOXP3, and CD25, the aetiology and pathogenesis of Hashimoto's thyroiditis remains unclear.

METHODS

Four affected members from a Chinese family with Hashimoto's thyroiditis were selected for whole-exome sequencing. Missense, nonsense, frameshift, or splicing-site variants shared by all affected members were identified after frequency filtering against public and internal exome databases. Segregation analysis was performed by Sanger sequencing among all members with available DNA.

RESULTS

We identified a missense mutation in PTPN22 (NM_015967.5; c. 77A > G; p.Asn26Ser) using whole-exome sequencing. PTPN22 is a known susceptibility gene associated with increased risks of multiple autoimmune diseases. Cosegregation analysis confirmed that all patients in this family, all of whom were female, carried the mutation. All public and private databases showed that the missense mutation was extremely rare.

CONCLUSIONS

We found a missense mutation in PTPN22 in a Chinese HT pedigree using whole-exome sequencing. Our study, for the first time, linked a rare variant of PTPN22 to Hashimoto's thyroiditis, providing further evidence of the disease-causing or susceptibility role of PTPN22 in autoimmune thyroid disease. Functional studies regarding the effects of this variant on thyroid autoimmunity and thyroid function are warranted.

Evaluation of Beauveria bassiana infection in the hemolymph serum proteins of the housefly, Musca domestica L. (Diptera: Muscidae)

Beauveria bassiana plays a prominent role in biocontrol of houseflies, Musca domestica (L.). Thus, a deeper insight into immune response of M. domestica during B. bassiana infection was warranted to assist the production of more efficient mycoinsecticides. The present study investigates changes in protein profile of M. domestica hemolymph serum post B. bassiana infection using two-dimensional difference gel electrophoresis (2D-DIGE) followed by identification of selected proteins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The non-infected or control group of flies showed an expression of 54 proteins, while M. domestica infected with B. bassiana expressed a total of 68 hemolymph serum proteins. Thirty three proteins were expressed in both groups of houseflies, whereas 35 proteins were exclusively expressed in infected flies and 21 proteins were exclusively expressed in control flies. Among the 33 proteins which were expressed in both groups of houseflies, 17 proteins showed downregulation, while16 proteins were upregulated in the infected flies compared to the non-infected ones. The results from this study are expected to facilitate better understanding of insect's immune response mechanism.

The role of human leukocyte antigen DRB1-DQB1 haplotypes in the susceptibility to acquired idiopathic thrombotic thrombocytopenic purpura

The acquired form of idiopathic thrombotic thrombocytopenic purpura (TTP) is an autoimmune disease, in which the underlying ADAMTS13-deficiency is caused by inhibitory autoantibodies against the protease. Human leukocyte antigens (HLA), responsible for antigen presentation, play an important role in the development of antibodies. The loci coding HLA DR and DQ molecules are inherited in linkage as haplotypes. The c.1858C>T polymorphism of the PTPN22 gene, which codes a protein tyrosine phosphatase important in lymphocyte activation, predisposes to a number of autoimmune diseases. We determined the HLA-DRB1-DQB1 haplotypes and the PTPN22 c.1858C>T genotypes in 75 patients with acquired idiopathic TTP and in healthy controls, in order to assess the role of these genetic factors and their interactions in the susceptibility to TTP. We found that the carrier frequencies of the DRB1^∗11-DQB1^∗03 and DRB1^∗15-DQB1^∗06 haplotypes were higher, while those of the DRB1^∗07-DQB1^∗02 and DRB1^∗13-DQB1^∗06 haplotypes were lower in TTP patients. There was no difference in the overall frequency of the PTPN22 c.1858T allele between TTP patients and controls. In conclusion, we identified four HLA-DRB1-DQB1 haplotypes associated with an increased (DRB1^∗11-DQB1^∗03 and DRB1^∗15-DQB1^∗06) or a decreased (DRB1^∗07-DQB1^∗02 and DRB1^∗13-DQB1^∗06) susceptibility to acquired idiopathic TTP.

Intestine immune homeostasis after alcohol and burn injury

Traumatic injury remains one of the most prevalent reasons for patients to be hospitalized. Burn injury accounts for 40,000 hospitalizations in the United States annually, resulting in a large burden on both the health and economic system and costing millions of dollars every year. The complications associated with postburn care can quickly cause life-threatening conditions including sepsis and multiple organ dysfunction and failure. In addition, alcohol intoxication at the time of burn injury has been shown to exacerbate these problems. One of the biggest reasons for the onset of these complications is the global suppression of the host immune system and increased susceptibility to infection. It has been hypothesized that infections after burn and other traumatic injury may stem from pathogenic bacteria from within the host's gastrointestinal tract. The intestine is the major reservoir of bacteria within the host, and many studies have demonstrated perturbations of the intestinal barrier after burn injury. This article reviews the findings of these studies as they pertain to changes in the intestinal immune system after alcohol and burn injury.

Perspective: Tyrosine phosphatases as novel targets for antiplatelet therapy

Arterial thrombosis is the primary cause of most cases of myocardial infarction and stroke, the leading causes of death in the developed world. Platelets, highly specialized cells of the circulatory system, are key contributors to thrombotic events. Antiplatelet drugs, which prevent platelets from aggregating, have been very effective in reducing the mortality and morbidity of these conditions. However, approved antiplatelet therapies have adverse side effects, most notably the increased risk of bleeding. Moreover, there remains a considerable incidence of arterial thrombosis in a subset of patients receiving currently available drugs. Thus, there is a pressing medical need for novel antiplatelet agents with a more favorable safety profile and less patient resistance. The discovery of novel antiplatelet targets is the matter of intense ongoing research. Recent findings demonstrate the potential of targeting key signaling molecules, including kinases and phosphatases, to prevent platelet activation and aggregation. Here, we offer perspectives to targeting members of the protein tyrosine phosphatase (PTP) superfamily, a major class of enzymes in signal transduction. We give an overview of previously identified PTPs in platelet signaling, and discuss their potential as antiplatelet drug targets. We also introduce VHR (DUSP3), a PTP that we recently identified as a major player in platelet biology and thrombosis. We review our data on genetic deletion as well as pharmacological inhibition of VHR, providing proof-of-principle for a novel and potentially safer VHR-based antiplatelet therapy.

Global analysis of serine/threonine and tyrosine protein phosphatase catalytic subunit genes in Neurospora crassa reveals interplay between phosphatases and the p38 mitogen-activated protein kinase

Protein phosphatases are integral components of the cellular signaling machinery in eukaryotes, regulating diverse aspects of growth and development. The genome of the filamentous fungus and model organism Neurospora crassa encodes catalytic subunits for 30 protein phosphatase genes. In this study, we have characterized 24 viable N. crassa phosphatase catalytic subunit knockout mutants for phenotypes during growth, asexual development, and sexual development. We found that 91% of the mutants had defects in at least one of these traits, whereas 29% possessed phenotypes in all three. Chemical sensitivity screens were conducted to reveal additional phenotypes for the mutants. This resulted in the identification of at least one chemical sensitivity phenotype for 17 phosphatase knockout mutants, including novel chemical sensitivities for two phosphatase mutants lacking a growth or developmental phenotype. Hence, chemical sensitivity or growth/developmental phenotype was observed for all 24 viable mutants. We investigated p38 mitogen-activated protein kinase (MAPK) phosphorylation profiles in the phosphatase mutants and identified nine potential candidates for regulators of the p38 MAPK. We demonstrated that the PP2C class phosphatase pph-8 (NCU04600) is an important regulator of female sexual development in N. crassa. In addition, we showed that the Δcsp-6 (ΔNCU08380) mutant exhibits a phenotype similar to the previously identified conidial separation mutants, Δcsp-1 and Δcsp-2, that lack transcription factors important for regulation of conidiation and the circadian clock.

SmLMWPTP, a teleost low molecular weight protein tyrosine phosphatase, inhibits the immune response of peripheral blood leukocytes in a manner that depends on the conserved P-loop

Protein tyrosine phosphatases (PTPs) are a family of enzymes that play a key role in cellular signal transduction. Low molecular weight PTPs (LMWPTPs) are a subfamily of PTPs that are characterized by the presence of a conserved phosphate-binding loop (P-loop) with the signature sequence of (V/I)CXGNXCRS. To date, very little study on teleost LMWPTPs has been documented, and, as a result, the function of LMWPTPs in fish is essentially unknown. In this study, we identified a LMWPTP from turbot (Scophthalmus maximus) and examined its biological activity and functionality. The turbot LMWPTP (SmLMWPTP) is composed of 158 residues and possesses a typical P-loop sequence in the form of (12)VCLGNICRS(20). Purified recombinant SmLMWPTP (rSmLMWPTP) exhibited apparent phosphatase activity, which was optimal at pH 5 and 50°C. The activity of SmLMWPTP was abolished when C13 and, in particular, R19 of the P-loop were mutated. SmLMWPTP expression was detected in a wide range of tissues and upregulated by bacterial and viral infection. Subcellular localization analysis showed that SmLMWPTP was secreted by peripheral blood leukocytes (PBL) into the extracellular milieu. When PBL were treated with rSmLMWPTP, the cells exhibited significant reductions in (i) proliferative and respiratory burst activity, (ii) expression levels of multiple immune relevant genes, and (iii) phagocytic activity. In contrast, the mutant SmLMWPTP bearing R19 mutation had no effect on PBL activity. Taken together, these results indicate that SmLMWPTP is a secreted PTP that exerts a negative regulatory effect on the innate immune response of PBL in a manner that depends on the structural integrity of the P-loop.

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.

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.

Evaluating effects of tyrosine phosphatase inhibitors on T cell receptor signaling

The importance of tyrosine phosphorylation in normal cell physiology is well established, highlighted by the many human diseases that stem from abnormalities in protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) function. Contrary to earlier assumptions, it is now clear that both PTKs and PTPs are highly specific, non-redundant, and tightly regulated enzymes. Hematopoietic cells express particularly high numbers of PTKs and PTPs, and aberrant function of these proteins have been linked to many hematopoietic disorders. While PTK inhibitors are among FDA approved drugs for the treatment of leukemia and other cancers, efforts to develop therapeutics that target specific PTPs are still in its infancy. Here, we describe methods on how to evaluate effects of PTP inhibitors on T cell receptor signaling. Moreover, we provide a comprehensive strategy for compound prioritization, applicable to any drug discovery project involving T cells. We present a testing funnel that starts with relatively high-throughput luciferase reporter assays, followed by immunoblot, calcium flux, flow cytometry, and proliferation assays, continues with cytokine bead arrays, and finishes with specificity assays that involve RNA interference. We provide protocols for experiments in the Jurkat T cell line, but more importantly give detailed instructions, paired with numerous tips, on how to prepare and work with primary human T cells.

Regulation of TCR signalling by tyrosine phosphatases: from immune homeostasis to autoimmunity

More than half of the known protein tyrosine phosphatases (PTPs) in the human genome are expressed in T cells, and significant progress has been made in elucidating the biology of these enzymes in T-cell development and function. Here we provide a systematic review of the current understanding of the roles of PTPs in T-cell activation, providing insight into their mechanisms of action and regulation in T-cell receptor signalling, the phenotypes of their genetically modified mice, and their possible involvement in T-cell-mediated autoimmune disease. Our projection is that the interest in PTPs as mediators of T-cell homeostasis will continue to rise with further functional analysis of these proteins, and PTPs will be increasingly considered as targets of immunomodulatory therapies.

Autoimmunity in primary antibody deficiency is associated with protein tyrosine phosphatase nonreceptor type 22 (PTPN22)

BACKGROUND

The 1858T allele of protein tyrosine phosphatase nonreceptor type 22 (PTPN22; R620W) exhibits one of the strongest and most consistent associations with sporadic autoimmune disease. Although autoimmunity is common in patients with primary antibody deficiency (PAD), it remains unknown whether its pathogenesis is similar when it arises in this context compared with in immunocompetent patients.

OBJECTIVE

We set out to determine whether the 1858T allele of PTPN22 was associated with PAD or with autoimmunity in the context of PAD.

METHODS

We genotyped rs2476601 (g.1858C>T), a single nucleotide polymorphism encoding substitution of arginine for tryptophan in PTPN22 (R620W), in 193 patients with PAD and 148 control subjects from an Australian cohort. We also performed a subgroup analysis according to the presence of autoimmunity and B-cell phenotypes.

RESULTS

C/T and T/T PTPN22 genotypes were more common in patients with PAD than in the matched control subjects (C/T, 18.1% vs 9.5%; T/T, 1.04% vs 0.6%). The T allele was associated with an increased risk of PAD relative to control subjects (odds ratio, 2.10; 95% CI, 1.11-4.00). The distribution of genotypes in control subjects was similar to those reported previously and did not deviate significantly from Hardy-Weinberg equilibrium. We found a strong association between the 1858T allele and PAD with coexistent autoimmune diseases. In patients with PAD and autoimmunity, 16 (43.2%) of 37 had at least one T allele of PTPN22 compared with 27 (17.3%) of 156 with the C/C genotype (P=.0014; odds ratio, 3.64; 95% CI, 1.68-7.88). We found no evidence that this effect was mediated by enrichment of CD21low B cells.

CONCLUSION

The 1858T PTPN22 allele is strongly associated with autoimmunity in patients with PAD.

Intrauterine growth restriction alters T-lymphocyte cell number and dual specificity phosphatase 1 levels in the thymus of newborn and juvenile rats

Intrauterine growth restricted (IUGR) infants have increased susceptibility to infection associated with higher risk of illness and death. Dual specificity phosphatase 1 (DUSP1), which is transcribed in the thymus, increases in quantity as T cells mature and differentiate into CD4+ cells. Little is known about how IUGR affects DUSP1 levels and T-cell subpopulations over time. We hypothesized that IUGR would decrease cell count, CD4+ and CD8+ subpopulations of T lymphocytes, and DUSP1 levels in IUGR rat thymus and spleen. Bilateral uterine artery ligation produced IUGR rats. Thymus and spleen were harvested at P0 and P21. Flow cytometry was used to compare CD4+ and CD8+ lymphocyte populations. Real-time RT-PCR and Western blotting were used to determine DUSP1 quantity. IUGR significantly decreased total cell count in P0 and P21 IUGR male and female thymus. IUGR significantly increased CD4+ cells in IUGR P0 males and females, significantly decreased CD4+ cells in P21 female thymus, and significantly altered DUSP1 levels in the IUGR female thymus at P0 and P21, although it is not yet known whether the change in DUSP1 levels is due to a change in the level per cell or to a change in cellular composition of the thymus.

Why is PTPN22 a good candidate susceptibility gene for autoimmune disease?

The PTPN22 locus is one of the strongest risk factors outside of the major histocompatability complex that associates with autoimmune diseases. PTPN22 encodes lymphoid protein tyrosine phosphatase (Lyp) which is expressed exclusively in immune cells. A single base change in the coding region of this gene resulting in an arginine to tryptophan amino acid substitution within a polyproline binding motif associates with type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosis, Hashimotos thyroiditis, Graves disease, Addison's disease, Myasthenia Gravis, vitiligo, systemic sclerosis juvenile idiopathic arthritis and psoriatic arthritis. Here, we review the current understanding of the PTPN22 locus from a genetic, geographical, biochemical and functional perspective.

Discovery of a novel series of inhibitors of lymphoid tyrosine phosphatase with activity in human T cells

The lymphoid tyrosine phosphatase LYP, encoded by the PTPN22 gene, is a critical regulator of signaling in T cells and recently emerged as a candidate target for therapy of autoimmune diseases. Here, by library screening, we identified a series of noncompetitive inhibitors of LYP that showed activity in primary T cells. Kinetic analysis confirmed that binding of the compounds to the phosphatase is nonmutually exclusive with respect to a known bidentate competitive inhibitor. The mechanism of action of the lead inhibitor compound 4e was studied by a combination of hydrogen/deuterium-exchange mass spectrometry and molecular modeling. The results suggest that the inhibitor interacts critically with a hydrophobic patch located outside the active site of the phosphatase. Targeting of secondary allosteric sites is viewed as a promising yet unexplored approach to develop pharmacological inhibitors of protein tyrosine phosphatases. Our novel scaffold could be a starting point to attempt development of "nonactive site" anti-LYP pharmacological agents.

Association of the protein tyrosine phosphatase nonreceptor 22 haplotypes with autoimmune thyroid disease in the Japanese population

BACKGROUND

A missence single-nucleotide polymorphism (SNP) in the protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene known as R620W (rs2476601) was recently reported to be associated with several autoimmune diseases including Graves' disease (GD). The association was repeatedly confirmed in the populations of North European ancestry. However, this amino acid was reported to be nonpolymorphic in the Asian populations. Since the gene confers an impact on autoimmune diseases, we attempt to explore an association between the PTPN22 gene and autoimmune thyroid disease (AITD) in a Japanese population without restricting to rs2476601. Previous investigations have also demonstrated that two intronic SNPs (rs706778 and rs3118470) in the interleukin-2 receptor-alpha (IL2RA) gene were associated with type 1 diabetes in the Japanese population.

PATIENTS AND METHODS

We genotyped the five SNPs (rs12760457, rs2797415, rs1310182, rs2476599, and rs3789604) of the PTPN22 and the two SNPs (rs706778 and rs3118470 in the IL2RA gene) in 456 Japanese patients with AITD (286 with GD, 170 with Hashimoto's thyroiditis) and 221 matched Japanese control subjects. Seven SNPs were analyzed by either the SNAPshot method or the high-resolution melting and unlabeled probe methods. Case-control association studies were performed using the chi(2) and Fisher's exact tests with Yates correction. Haplotype was conducted using the expectation-maximization algorithm.

RESULTS

No association was found between any of the individual SNPs of the PTPN22 gene and AITD. Permutation analysis revealed that the distribution of one haplotype is significantly different between patients with AITD and controls (p = 0.0036). A novel protective effect of a haplotype containing five SNPs was observed (p < 0.0001 for AITD, p < 0.0001 for GD, and p < 0.0001 for Hashimoto's thyroiditis, respectively). The GG allele of rs3118470 in the IL2RA gene was significantly associated with GD (p = 0.03), although the association was weak.

CONCLUSIONS

Significant difference in the distribution of the haplotype suggests that the PTPN22 gene rather than rs2476601 is involved in the development of AITD in the Japanese population.

Spatiotemporal control of cyclic AMP immunomodulation through the PKA-Csk inhibitory pathway is achieved by anchoring to an Ezrin-EBP50-PAG scaffold in effector T cells

A variety of immunoregulatory signals to effector T cells from monocytes, macrophages and regulatory T cells act through cyclic adenosine monophosphate. In the effector T cell, the protein kinase A (PKA) type I isoenzyme localizes to lipid rafts during T cell activation and modulates directly the proximal events that take place after engagement of the T cell receptor. The most proximal target for PKA phosphorylation is C-terminal Src kinase (Csk), which initiates a negative signal pathway that fine-tunes the T cell activation process. The A kinase anchoring protein Ezrin colocalizes PKA and Csk by forming a supramolecular signaling complex consisting of PKA, Ezrin, Ezrin/radixin/moesin (ERM) binding protein of 50 kDa (EBP50), phosphoprotein associated with glycosphingolipid-enriched membrane microdomains (GEMs) (PAG) and Csk.

PTPN2 but not PTPN22 is associated with Crohn's disease in a New Zealand population

Recent genome-wide association studies have provided evidence for the involvement of the genes PTPN2 and PTPN22 in the pathogenesis of Crohn's disease (CD). We investigated whether genetic variants in these genes were associated with CD in a New Zealand population. Single-nucleotide polymorphisms (SNPs) rs2542151 (PTPN2) and rs2476601 (PTPN22) were genotyped in 315 CD cases and 481 controls. 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. There was no evidence for an association with PTPN22.

Lymphoid tyrosine phosphatase and autoimmunity: human genetics rediscovers tyrosine phosphatases

A relatively large number of protein tyrosine phosphatases (PTPs) are known to regulate signaling through the T cell receptor (TCR). Recent human genetics studies have shown that several of these PTPs are encoded by major autoimmunity genes. Here, we will focus on the lymphoid tyrosine phosphatase (LYP), a critical negative modulator of TCR signaling encoded by the PTPN22 gene. The functional analysis of autoimmune-associated PTPN22 genetic variants suggests that genetic variability of TCR signal transduction contributes to the pathogenesis of autoimmunity in humans.

Clinical associations of the genetic variants of CTLA-4, Tg, TSHR, PTPN22, PTPN12 and FCRL3 in patients with Graves' disease

OBJECTIVE

Graves' disease (GD) is an organ-specific autoimmune disorder. Both immune-modulating genes and thyroid-specific genes are involved in its genetic pathogenesis. It remains unclear, however, how the interactions of various susceptibility genes contribute to the pathogenesis and clinical severity of the disease. The purpose of this study was to investigate the relationships between GD and single nucleotide polymorphisms (SNPs) from CTLA-4, PTPN22, PTPN12, FCRL3 (general autoimmunity genes regulating T and B cells) and the TSHR and Tg genes (disease-specific genes). Furthermore, we evaluated the influences these SNPs have on the risk and severity of GD.

DESIGN AND METHODS

This cross-sectional clinical study was performed in 436 GD patients and 316 healthy, gender-matched individuals. Twenty-eight SNPs from CTLA-4, PTPN22, PTPN12, FCRL3, TSHR and Tg genes were genotyped and their associations with the risk and severity of GD were analysed.

RESULTS

The CTLA-4 rs231779, Tg rs2069550 and PTPN22 rs3789604 SNPs were associated with GD, with additive risk effects present in rs231779 and rs2069550. The ACACC and ACGCT haplotypes, composed of five SNPs in the CTLA-4 gene (rs4553808, rs5472909, rs231775, rs231777 and rs231779), were protective and risk haplotypes respectively. The AA genotype of PTPN22 rs3789604 and AA genotype of FCRL3 rs7528684 were correlated with a reduced risk of GD, while the CC genotype of TSHR rs2239610 was associated with higher serum concentrations of FT4 and TRAb. Logistic analysis confirmed the contribution of CTLA-4 rs231779 to the development of GD.

CONCLUSIONS

These preliminary results demonstrate that the immune-regulatory gene CTLA-4 and the thyroid-specific gene Tg contribute to the risk of Graves' disease with additive effects, while PTPN22 rs3789604 and FCRL3 rs7528684 polymorphisms are protective against the disease. In addition, the TSHR rs2239610 SNP is related to the severity of Graves' disease.

Association of a functional polymorphism of PTPN22 encoding a lymphoid protein phosphatase in bilateral Meniere's disease

OBJECTIVES/HYPOTHESIS

Bilateral Meniere's disease (BMD) is a severe disease that usually results in bilateral severe or profound sensorineural hearing loss and chronic disequilibrium with loss of vestibular function. We examined single nucleotide polymorphisms (SNPs) in the PTPN22 and CTLA4 genes in Caucasian patients with BMD to assess the possible association between these polymorphism and the predisposition and clinical expression of this disease.

STUDY DESIGN

A case control study.

METHODS

The functional protein tyrosine phosphatase type 22 (PTPN22) SNP (rs2476601, 1858C/T) and CTLA4 SNP (rs231775, 49A/G) were analyzed in 52 patients with BMD and 348 healthy controls by a TaqMan 5' allelic discrimination assay. Data were analyzed by a chi(2) test with Fisher exact test.

RESULTS

No association was found between the +49A/G CTLA4 genotype and BMD patients. However, the heterozygote PTPN22 1858C/T genotype was present at a significantly higher frequency in BMD patients than in controls (odds ratio = 2.25, 95% confidence interval: 1.09-4.62; P = .04).

CONCLUSIONS

These results suggest that the PTPN22 1858C/T genotype may confer differential susceptibility to BMD in the Spanish population and support an autoimmune etiology for BMD.

Gold(I) phosphine mediated selective inhibition of lymphoid tyrosine phosphatase

Selective protein tyrosine phosphatase (PTP) inhibition is often difficult to achieve owing to the high degree of similarity of the catalytic domains of this family of enzymes. Selective inhibitors of the lymphoid specific tyrosine phosphatase, LYP, are of great interest due to the involvement of LYP in several autoimmune disorders. This manuscript describes a study into the mechanistic details of selective LYP inhibition by a Au(I)-phosphine complex. The complex, [Au((CH(2)CH(2)CN)(2)PPh)Cl], selectively inhibits LYP activity both in vitro and in cells, but does not inhibit other T-cell derived PTPs including the highly homologous PTP-PEST. The mode of inhibition was probed by investigating inhibition of LYP, the LYP mutant C129/231S, and PTP-PEST. Inhibition of LYP and PTP-PEST was competitive, while the LYP double mutant appeared mixed. Wild-type LYP was inhibited more potently than LYP C129/231S, indicating an important role for at least one of these residues in Au(I) binding. Coordination of Au(I) by both the active site cysteine residue as well as either Cys129 or 231 is suggested as a potential mechanism for LYP selective inhibition.

Identifying potent, selective protein tyrosine phosphatase inhibitors from a library of Au(I) complexes

Therapeutic inhibition of protein tyrosine phosphatase activity is a compelling yet challenging approach to the treatment of human disease. Toward this end, a library of 40 gold complexes with the general formula R(3)P-Au-Cl was screened to identify novel inhibitors of PTP activity. The most promising inhibitor obtained for the lymphoid tyrosine phosphatase LYP, (2-pyridine)(Ph(2))P-Au-Cl, is one of the most potent and selective LYP inhibitors identified to date with an IC(50) of 1.5 +/- 0.3 microM, 10-fold selectivity for LYP over PTP-PEST, HePTP, and CD45 in vitro, and activity in cellular studies as well.

ERK and not p38 pathway is required for IL-12 restoration of T cell IL-2 and IFN-gamma in a rodent model of alcohol intoxication and burn injury

Previous studies from our laboratory have shown that acute alcohol/ethanol (EtOH) intoxication combined with burn injury suppresses T cell IL-2 and IFN-gamma production by inhibiting p38 and ERK activation. Because IL-12 plays a major role in Th1 differentiation and IFN-gamma production, we examined whether diminished IL-2 and IFN-gamma production after EtOH plus burn injury resulted from a decrease in IL-12. Furthermore, we investigated whether IL-12 utilizes the p38/ERK pathway to modulate T cell IL-2 and IFN-gamma production after EtOH and burn injury. Male rats ( approximately 250 g) were gavaged with 5 ml of 20% EtOH 4 h before approximately 12.5% total body surface area burn or sham injury. Rats were sacrificed on day 1 after injury, and mesenteric lymph node T cells were isolated. T cells were stimulated with anti-CD3 in the absence or presence of rIL-12 (10 ng/ml) for 5 min and lysed. Lysates were analyzed for p38/ERK protein and phosphorylation levels using specific Abs and Western blot. In some experiments, T cells were cultured for 48 h with or without the inhibitors of p38 (10 microM SB203580/SB202190) or ERK (50 microM PD98059) to delineate the role of p38 and ERK in IL-12-mediated restoration of IL-2 and IFN-gamma. Our findings indicate that IL-12 normalizes both p38 and ERK activation in T cells, but the results obtained using p38 and ERK inhibitors indicate that the restoration of ERK plays a predominant role in IL-12-mediated restoration of T cell IL-2 and IFN-gamma production after EtOH and burn injury.

Multiparameter phospho-flow analysis of lymphocytes in early rheumatoid arthritis: implications for diagnosis and monitoring drug therapy

Background

The precise mechanisms involved in the initiation and progression of rheumatoid arthritis (RA) are not known. Early stages of RA often have non-specific symptoms, delaying diagnosis and therapy. Additionally, there are currently no established means to predict clinical responsiveness to therapy. Immune cell activation is a critical component therefore we examined the cellular activation of peripheral blood mononuclear cells (PBMCs) in the early stages of RA, in order to develop a novel diagnostic modality.

Methods and Findings

PBMCs were isolated from individuals diagnosed with early RA (ERA) (n = 38), longstanding RA (n = 10), osteoarthritis (OA) (n = 19) and from healthy individuals (n = 10). PBMCs were examined for activation of 15 signaling effectors, using phosphorylation status as a measure of activation in immunophenotyped cells, by flow cytometry (phospho-flow). CD3+CD4+, CD3+CD8+ and CD20+ cells isolated from patients with ERA, RA and OA exhibited activation of multiple phospho-epitopes. ERA patient PBMCs showed a bias towards phosphorylation-activation in the CD4+ and CD20+ compartments compared to OA PBMCs, where phospho-activation was primarily observed in CD8+ cells. The ratio of phospho (p)-AKT/p-p38 was significantly elevated in patients with ERA and may have diagnostic potential. The mean fluorescent intensity (MFI) levels for p-AKT and p-H3 in CD4+, CD8+ and CD20+ T cells correlated directly with physician global assessment scores (MDGA) and DAS (disease activity score). Stratification by medications revealed that patients receiving leflunomide, systemic steroids or anti-TNF therapy had significant reductions in phospho-specific activation compared with patients not receiving these therapies. Correlative trends between medication-associated reductions in the levels of phosphorylation of specific signaling effectors and lower disease activity were observed.

Conclusions

Phospho-flow analysis identified phosphorylation-activation of specific signaling effectors in the PB from patients with ERA. Notably, phosphorylation of these signaling effectors did not distinguish ERA from late RA, suggesting that the activation status of discrete cell populations is already established early in disease. However, when the ratio of MFI values for p-AKT and p-p38 is >1.5, there is a high likelihood of having a diagnosis of RA. Our results suggest that longitudinal sampling of patients undergoing therapy may result in phospho-signatures that are predictive of drug responsiveness.

Regulation of lymphoid tyrosine phosphatase activity: inhibition of the catalytic domain by the proximal interdomain

The lymphoid tyrosine phosphatase LYP, encoded by the PTPN22 gene, recently emerged as a major player and candidate drug target for human autoimmunity. The enzyme includes a classical N-terminal protein tyrosine phosphatase catalytic domain and a C-terminal PEST-enriched domain, separated by an approximately 300-amino acid interdomain. Little is known about the regulation of LYP. Herein, by analysis of serial truncation mutants of LYP, we show that the phosphatase activity is strongly inhibited by protein regions C-terminal to the catalytic domain. We mapped the minimal inhibitory region to the proximal portion of the interdomain. We show that the activity of LYP is inhibited by an intramolecular mechanism, whereby the proximal portion of the interdomain directly interacts with the catalytic domain and reduces its activity.

Setaria cervi dual specific phosphatase: characterization and its effect on eosinophil degranulation

Setaria cervi, a bovine filarial parasite contains significant acid phosphatase (AcP) activity in its various life stages. Two forms of AcP were separated from somatic extract of adult female parasite using cation exchange, gel filtration and concavalin affinity chromatography. One form having a molecular mass of 79 kDa was characterized as dual specific protein tyrosine phosphatase (ScDSP) based on substrate specificity and inhibition studies. With various substrates tested, it showed significant activity in the order of phospho-L-tyrosine>pNPP>ADP>phospho-L-serine. Inhibition by orthovanadate, fluoride, molybdate, and zinc ions further confirms protein tyrosine phosphatase nature of the enzyme. Km and Vmax determined with various substrates were found to be 16.66 mM, 25.0 microM/ml/min with pNPP; 20.0 mM, 40.0 microM/ml/min with phospho-L-tyrosine and 27.0 mM, 25.0 microM/ml/min with phospho-L-serine. KI with pNPP and sodium orthovanadate (IC50 33.0 microM) was calculated to be 50.0 mM. Inhibition with pHMB, silver nitrate, DEPC and EDAC suggested the presence of cysteine, histidine and carboxylate residues at its active site. Cross-reactivity with W. bancrofti-infected sera was demonstrated by Western blotting. ScDSP showed elevated levels of IgE in chronic filarial sera using ELISA. Under in vitro conditions, ScDSP resulted in increased effector function of human eosinophils when stimulated by IgG, which showed a further decrease with increasing enzyme concentration. Results presented here suggest that S. cervi DSP should be further studied to determine its role in pathogenesis and the persistence of filarial parasite.

CD45 recruits adapter protein DOK-1 and negatively regulates JAK-STAT signaling in hematopoietic cells

It has been extensively documented that CD45 positively regulates T cell receptor-mediated signaling through the activation of Src-family kinases. The mechanism whereby CD45 negatively regulates the JAK/STAT pathway, however, has not been fully elucidated. Here we describe the mechanism by which CD45 negatively regulates the JAK/STAT pathway through the recruitment of the inhibitory molecule Downstream of Kinase 1 (DOK-1) in hematopoietic cells. We present evidences that CD45 recruits DOK-1 to associate with tyrosine-phosphorylated DOK-1, and that the DOK-1-Y296F mutant completely abrogates its interaction with CD45. Moreover, CD45 expression is required for DOK-1 targeting to the plasma membrane in response to anti-CD3 stimulation. Functional studies further showed that stable expression of DOK-1 in K562 cells markedly decreased both JAK-2 and STAT-3/5 phosphorylation following IL-3 and IFN-alpha stimulation. Likewise, stable expression of DOK-1 in Jurkat cells significantly decreased JAK-2 phosphorylation. Similarly, both IL-3 and IFN-alpha-induced JAK-2 phosphorylations were significantly increased in CD45 deficient Jurkat cells. Consistently, silencing of the DOK-1 gene resulted in rescue of MAP kinases and JAKs activities in CD45 positive Jurkat cells. Accordingly, CD45 recruits adaptor DOK-1 to the proximal plasma membrane to serve as a downstream effector, resulting in negative regulation of the JAK/STAT signaling pathway.

Hematopoietic protein tyrosine phosphatase mediates beta2-adrenergic receptor-induced regulation of p38 mitogen-activated protein kinase in B lymphocytes

Stimulation of the beta(2)-adrenergic receptor (beta(2)AR) on a CD40L/interleukin-4-activated B lymphocyte increases the level of immunoglobulin E (IgE) in a protein kinase A (PKA)- and p38 mitogen-activated protein kinase (MAPK)-dependent manner. However, the mechanism by which beta(2)AR stimulation mediates the increase in the level of p38 MAPK activation has remained unclear. Here we show that the beta(2)AR-induced increase in p38 MAPK activation occurred via a hematopoietic protein tyrosine phosphatase (HePTP)-mediated cross talk between PKA and p38 MAPK. beta(2)AR agonists, cAMP-elevating agents, and PKA inhibitors were used to show that beta(2)AR stimulation resulted in a PKA-dependent increase in p38 MAPK phosphorylation. Pharmacological agents and gene-deficient mice revealed that p38 MAPK phosphorylation was regulated by the G-stimulatory (Gs)/cAMP/PKA pathway independently of the G-inhibitory or beta-arrestin-2 pathways. Coimmunoprecipitation and Western blot analysis showed that HePTP was phosphorylated in a PKA-dependent manner, which inactivated HePTP and allowed for increased free p38 MAPK to be phosphorylated by the MAPK cascade that was activated by CD40L. HePTP short hairpin RNA confirmed that HePTP played a role in regulating the level of p38 MAPK phosphorylation in a B cell. Thus, beta(2)AR stimulation on a B cell phosphorylates and inactivates HePTP in a Gs/cAMP/PKA-dependent manner to release bound p38 MAPK, making more available for phosphorylation and subsequent IgE regulation.

Molecular cytogenetic characterization of two independent karyotypic anomalies in a patient with severe mental retardation and juvenile idiopathic arthritis

We report on a patient with severe mental retardation, dysmorphic features as well as juvenile idiopathic arthritis. G-banding indicated two independent karyotypic anomalies in this patient: an interstitial deletion del(X)(p21p22.3) and a rearrangement involving chromosomes 1 and 7, which represents a direct insertion, ins(7;1)(q36;p13.2p31.2). Non-random inactivation of the paternally derived del(X) chromosome was observed in blood lymphocytes and fibroblasts. High resolution analysis of the rearrangement involving chromosomes 1 and 7 subsequently revealed the additional submicroscopic deletion of at least 5 Mb at the 1p13.2 breakpoint. The deletion occurred on the paternal chromosome and encompasses the PTPN22 gene, already known to be associated with juvenile idiopathic arthritis. Our findings underline the importance of closely investigating the breakpoint regions of apparently balanced rearrangements in patients with abnormal phenotypes since complex chromosomal rearrangements (CCRs) may turn out to be unbalanced.

ret/PTC-1 expression alters the immunoprofile of thyroid follicular cells

Background

Hashimoto Thyroiditis (H.T.) is a destructive autoimmune thyroid condition whose precise molecular pathogenesis remains unclear. ret/PTC-1 is a chimeric transcript which has been described in autoimmune thyroid disease (AITD) and thyroid neoplasia. The purpose of this study was to observe the immunogenic effect exposure to H.T. and control lymphocyte supernatant would have on normal (Nthy-ori) and ret/PTC-1 (TPC-1) expressing thyroid cell line models.

Results

A 2 × 2 matrix comprising Nthy-ori and TPC-1 cell lines and H.T. and control lymphocyte supernatant was designed and utilised as follows; activated lymphocytic supernatant from a H.T. and normal control were co-cultured with a cell line derived from normal thyroid (Nthy-ori) and also a cell line derived from a papillary thyroid carcinoma that endogenously expresses ret/PTC-1 (TPC-1). The co-cultures were harvested at 0, 6 and 18 hour time points. Gene expression analysis was performed on RNA extracted from thyrocytes using TaqMan^® Immune profiling Low-Density Arrays (Applied Biosystems, CA, USA) comprising gene expression markers for 93 immune related targets plus 3 endogenous controls.

Stimulation of the normal thyroid cell line model with activated T cell supernatant from the H.T. donor yielded global up-regulation of immune targets when compared with control supernatant stimulation. In particular, a cohort of targets (granzyme B, CD3, CD25, CD152, CD45) associated with cytotoxic cell death; T cell receptor (TCR) and T cell signaling were up-regulated in the normal cell line model. When the ret/PTC-1 expressing thyroid cell line was co-cultured with H.T. lymphocyte supernatant, in comparison to control supernatant stimulation, down-regulation of the same subset of immune targets was seen.

Conclusion

Co-culturing H.T. lymphocyte supernatant with a normal thyroid cell line model leads to over-expression of a subset of targets which could contribute to the pathogenesis of H.T. via cytotoxic cell death and TCR signalling. Stimulation of the ret/PTC-1 positive cell line with the same stimulus led to a down-regulated shift in the gene expression pattern of the cohort of immune targets. We hypothesize that ret/PTC-1 activation may dampen immunogenic responses in the thyroid, which could possibly facilitate papillary thyroid carcinoma development.

Inhibition of protein tyrosine phosphatases prevents mesenteric lymph node T-cell suppression following alcohol intoxication and burn injury

Previously, we have shown that acute alcohol (EtOH) intoxication before burn injury potentiates the suppression of mesenteric lymph node T-cell effector responses. Moreover, the suppression in T-cell was accompanied with a decrease in p-38 and extracellular-signal-regulated kinase (ERK) activation. This study examined the role of protein tyrosine phosphatases (PTP) in suppressed T-cell p-38, ERK, and cytokine production after EtOH intoxication and burn injury. A blood EtOH level of approximately 100 mg/dl in male rats (approximately 250 g) was achieved by gavaging animals with 5 ml of 20% EtOH suspension 4 hours before burn or sham injury (approximately 12.5% or 25% total body surface area [TBSA]). One day after injury, rats were killed and mesenteric lymph node T-cell cytokine (IL-2/IFN-gamma) production, p-38, and ERK activation were measured. As compared with shams, there was a significant decrease in T-cell cytokine production after 25% and not 12.5% TBSA burn injury. However, T-cell IL-2/IFN-gamma levels were significantly decreased in rats receiving a combined insult of EtOH and burn injury regardless of the percentage of burn area. Furthermore, we found a significant decrease in p-38 and ERK-1/2 phosphorylation in T-cells of rats receiving a combined insult of EtOH and 12.5% TBSA burn compared with shams. Treatment of cells with PTP inhibitor pervanadate (10 muM) prevented T-cell p-38/ERK suppression. The suppression in IL-2/IFN-gamma production was also attenuated in T-cells cultured in the presence of pervanadate. These findings suggest that an increase in PTP activity may contribute to T-cell suppression after EtOH intoxication and burn injury.

Unifying electrostatic mechanism for phosphates and sulfates in cell signaling

Prior proposals suggested the importance of electrochemistry in signal transduction and receptor-ligand activity. Electrostatic fields associated with ions and dipoles were assigned important roles. Little is known concerning the precise mode of action in cell signaling by widespread phosphorylation. According to the hypothetical framework, molecular electrostatic potential associated with phosphate anion is a key element as a link in the communication grid, possibly inducing favorable energetics in the electron transfer process. Similar involvement appears plausible for the sulfate anion. Supporting evidence for the electrostatic mechanism is presented. Representative literature on phosphorylation in the biological domain is reviewed with emphasis on cell signaling. The treatment includes phosphates from protein, lipids, and other molecules, plus the role of reactive oxygen species. Protein sulfation is also discussed.

The requirement of reversible cysteine sulfenic acid formation for T cell activation and function

Reactive oxygen intermediates (ROI) generated in response to receptor stimulation play an important role in mediating cellular responses. We have examined the importance of reversible cysteine sulfenic acid formation in naive CD8(+) T cell activation and proliferation. We observed that, within minutes of T cell activation, naive CD8(+) T cells increased ROI levels in a manner dependent upon Ag concentration. Increased ROI resulted in elevated levels of cysteine sulfenic acid in the total proteome. Analysis of specific proteins revealed that the protein tyrosine phosphatases SHP-1 and SHP-2, as well as actin, underwent increased sulfenic acid modification following stimulation. To examine the contribution of reversible cysteine sulfenic acid formation to T cell activation, increasing concentrations of 5,5-dimethyl-1,3-cyclohexanedione (dimedone), which covalently binds to cysteine sulfenic acid, were added to cultures. Subsequent experiments demonstrated that the reversible formation of cysteine sulfenic acid was critical for ERK1/2 phosphorylation, calcium flux, cell growth, and proliferation of naive CD8(+) and CD4(+) T cells. We also found that TNF-alpha production by effector and memory CD8(+) T cells was more sensitive to the inhibition of reversible cysteine sulfenic acid formation than IFN-gamma. Together, these results demonstrate that reversible cysteine sulfenic acid formation is an important regulatory mechanism by which CD8(+) T cells are able to modulate signaling, proliferation, and function.

Extracellular acidic environments induce phosphorylation of ZAP-70 in Jurkat T cells

In solid tumor and inflammation loci, low pH conditions have been observed as a consequence of either a lack of sufficient vascularization or excess activity of tumor cells, and T cells have been reported to infiltrate tumors and inflammation sites. However, it remains unclear how extracellular acidic environments affect immune cell function. A previous report proposed that a different signal transduction cascade might occur under low pH conditions in Jurkat T cells (Fukamachi T, Saito H, Kakegawa T, Kobayashi H. Different proteins are phosphorylated under acidic environments in Jurkat cells. Immunol Lett 2002;82:155-8). In this study, we investigated the protein phosphotyrosine level in Jurkat and Jurkat mutant cells under different pH conditions. The ZAP-70 phosphorylation level increased under acidic environments. P38 MAPK was more activated at acidic pH. The level of active p38 was low in mutant P116 deficient in ZAP-70, and interestingly the level remained consistently low at all pH values tested. The activation of ERK was not stimulated at low pH. These results suggest that extracellular low pH stimulates or enhances TCR signaling via ZAP-70 and p38.

Association study of PTPN22 C1858T polymorphism in Trypanosoma cruzi infection

In this study we investigated a possible role for the single nucleotide polymorphism C1858T of the PTPN22 (protein tyrosine phosphatase nonreceptor 22) gene in determining the susceptibility to Trypanosoma cruzi infection, as well as in development of chagasic heart disease. This study included 316 patients with Chagas' disease and 520 healthy individuals from Colombia and Peru. Genotyping of PTPN22 was performed by the real-time polymerase chain reaction technology, using the TaqMan 5' allelic discrimination assay. No statistically significant differences in the frequency of PTPN22 C1858T gene polymorphism between chagasic patients and controls or between asymptomatic and cardiomyopathic individuals were observed. Our findings suggest that the PTPN22 polymorphism analyzed does not play a major role in the development of Chagas' disease in the Colombian and Peruvian populations.

CD4-Positive Effector Memory T Cells Participate in Disease Expression in ANCA-Associated Vasculitis

Although the cause of ANCA-associated vasculitis (AAV) remains undetermined, the presence of lymphocytic infiltrates in inflammatory lesions of patients suggests that vascular damage is immune mediated. Studies over the past decade have implicated a role for T cells in the pathogenesis of AAV as altered T cell phenotype has been observed in this disorder. The distribution of T cell subpopulations has been analyzed most intensely in Wegener's granulomatosis (WG), where an expanded population of circulating CD4(+) effector memory T cells (CD4(+)T(EM)) was demonstrated. CD4(+)T(EM) cells play a major role in the pathogenesis of several autoimmune diseases. Specific suppression of CD4(+)T(EM) cells inhibits delayed-type hypersensitivity (DTH) and has therapeutic potential in autoimmune disease. Thus, CD4(+)T(EM) cells may act as inducers of tissue injury and participate in the development of AAV. Therapies that target CD4(+)T(EM), without impairing the activity of other lymphocyte subsets, may hold therapeutic promise for AAV.

Association of Protein-tyrosine Phosphatase MEG2 via Its Sec14p Homology Domain with Vesicle-trafficking Proteins

The protein-tyrosine phosphatase PTPMEG2 is located on the cytoplasmic face of the enclosing membrane of secretory vesicles, where it regulates vesicle size by promoting homotypic vesicle fusion by dephosphorylating N-ethylmaleimide-sensitive factor, a key regulator of vesicle fusion. Here we address the question of how PTPMEG2 is targeted to this subcellular location. Using a series of deletion mutants, we pinpointed the N-terminal Sec14p homology (SEC14) domain of PTPMEG2, residues 1-261, as the region containing the secretory vesicle targeting signal. This domain, alone or appended to a heterologous protein, was localized to intracellular vesicle membranes. Yeast two-hybrid screening identified a number of secretory vesicle proteins that interacted directly with the SEC14 domain of PTPMEG2, providing a mechanism for PTPMEG2 targeting to secretory vesicles. Two such proteins, mannose 6-phosphate receptor-interacting protein TIP47 and Arfaptin2, were found to alter PTPMEG2 localization when overexpressed, and elimination of TIP47 resulted in loss of PTPMEG2 function. We conclude that the N terminus of PTPMEG2 is necessary for the targeting of this phosphatase to the secretory vesicle compartment by association with other proteins involved in intracellular transport.

Nonreceptor Protein-Tyrosine Phosphatases in Immune Cell Signaling

Tyrosyl phosphorylation plays a critical role in multiple signaling pathways regulating innate and acquired immunity. Although tyrosyl phosphorylation is a reversible process, we know much more about the functions of protein-tyrosine kinases (PTKs) than about protein-tyrosine phosphatases (PTPs). Genome sequencing efforts have revealed a large and diverse superfamily of PTPs, which can be subdivided into receptor-like (RPTPs) and nonreceptor (NRPTPs). The role of the RPTP CD45 in immune cell signaling is well known, but those of most other PTPs remain poorly understood. Here, we review the mechanism of action, regulation, and physiological functions of NRPTPs in immune cell signaling. Such an analysis indicates that PTPs are as important as PTKs in regulating the immune system.

Association of PTPN22 haplotypes with Graves' disease

CONTEXT

A recent study reported associations of a series of single nucleotide polymorphisms (SNPs) within PTPN22, including rs2476601, with rheumatoid arthritis.

OBJECTIVE

Having previously reported significant association of the T allele of rs2476601 in a Graves' disease (GD) cohort, we sought to determine whether novel rheumatoid arthritis-associated SNPs were also contributing to susceptibility to GD.

DESIGN

Case control and family-based studies of five PTPN22 tag SNPs were performed.

SETTING

An United Kingdom academic department of medicine was the setting for the study.

PATIENTS OR OTHER PARTICIPANTS

A total of 768 GD patients, 768 control subjects, and 313 families with autoimmune thyroid disease participated.

MAIN OUTCOME MEASURE

Tests for association with disease were the main outcome measure.

RESULTS

No association with disease of any of the individual SNPs and no correlation between genotype and clinical phenotype were seen. However, haplotype analysis of the SNP markers with addition of rs2476601 did reveal a strong association of a haplotype containing the T allele, in both the case control (chi2 = 29.13; P = 6.77 x 10(-8)) and family data sets (chi2 = 5.24; P = 0.02). Furthermore, a novel protective effect of a haplotype containing all six SNPs was observed (chi2 = 17.02; P = 3.7 x 10(-5)).

CONCLUSIONS

These data suggest that the association of SNPs within the PTPN22 region differs between autoimmune diseases, occurring individually and/or as part of a haplotype, indicating that the mechanisms by which PTPN22 confers susceptibility to GD may, in part, be disease specific.