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PTPN22 encodes a tyrosine phosphatase th at is expressed by haematopoietic ceils and functions as a key regulator of immune homeostasis by inhibiting T-cell receptor signalling and by selectively promoting type I interferon responses after activation of myeloid-cell pattern-recognition receptors. A single nucleotide polymorphism of PTPN22,1858C>T (rs2476601), disrupts an interaction motif in the protein, and is the most important non-HLA genetic risk factor for rheumatoid arthritis and the second most important for juvenile idiopathic arthritis. PTPN22 exemplifies a shared autoimmunity gene, affecting the pathogenesis of systemic lupus erythematosus, vasculitis and other autoimmune diseases. In this Review, we explore the role of PTPN22 in autoimmune connective tissue disease, with particular emphasis on candidate-gene and genome-wide association studies and clinical variability of disease. We also propose a number of PTP/V22-dependent functional models of the pathogenesis of autoimmune diseases. [ABSTRACT FROM AUTHOR]

Epigenetic anomalies are emerging as key pathogenic features of rheumatoid arthritis (RA). The effect of epigenetics in RA ranges from contributing to complex disease mechanisms to identifying biomarkers for early diagnosis and response to therapy. This review focuses on three key epigenetic areas in RA, namely DNA methylation, histone modification, and expression and/or function of microRNAs. Epigenomics studies of DNA methylation have identified alterations of genome-wide DNA methylation in cells from patients with rheumatoid arthritis. Histone modification studies have focused on histone acetylation, which tends to be increased in RA. Preclinical studies show that inhibitors of histone deacetylases are effective in cellular and animal models of RA. Genome-wide and candidate microRNA surveys identified increased or reduced expression of selected microRNAs in rheumatoid arthritis. These microRNA are either pro or anti-inflammatory in multiple cell types or affect osteoclast physiology and the pathogenesis of bone erosion. Defining epigenetic contributions to the pathogenesis of RA, especially in combination with understanding genetic associations, could lead to novel therapy and a clearer understanding of disease risk. [ABSTRACT FROM AUTHOR]

Objective The fibroblast-like synoviocytes (FLS) in the synovial intimal lining of the joint are key mediators of inflammation and joint destruction in rheumatoid arthritis (RA). In RA, these cells aggressively invade the extracellular matrix, producing cartilage-degrading proteases and inflammatory cytokines. The behavior of FLS is controlled by multiple interconnected signal transduction pathways involving reversible phosphorylation of proteins on tyrosine residues. However, little is known about the role of the protein tyrosine phosphatases (PTPs) in FLS function. This study was undertaken to explore the expression of all of the PTP genes (the PTPome) in FLS. Methods A comparative screening of the expression of the PTPome in FLS from patients with RA and patients with osteoarthritis (OA) was conducted. The functional effect on RA FLS of SH2 domain-containing phosphatase 2 (SHP-2), a PTP that was up-regulated in RA, was then analyzed by knockdown using cell-permeable antisense oligonucleotides. Results PTPN11 was overexpressed in RA FLS compared to OA FLS. Knockdown of PTPN11, which encodes SHP-2, reduced the invasion, migration, adhesion, spreading, and survival of RA FLS. Additionally, signaling in response to growth factors and inflammatory cytokines was impaired by SHP-2 knockdown. RA FLS that were deficient in SHP-2 exhibited decreased activation of focal adhesion kinase and mitogen-activated protein kinases. Conclusion These findings indicate that SHP-2 has a novel role in mediating human FLS function and suggest that it promotes the invasiveness and survival of RA FLS. Further investigation may reveal SHP-2 to be a candidate therapeutic target for RA. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is characterized by hyperplastic synovial pannus tissue, which mediates destruction of cartilage and bone. Fibroblast-like synoviocytes (FLS) are a key component of this invasive synovium and have a major role in the initiation and perpetuation of destructive joint inflammation. The pathogenic potential of FLS in RA stems from their ability to express immunomodulating cytokines and mediators as well as a wide array of adhesion molecule and matrix-modelling enzymes. FLS can be viewed as 'passive responders' to the immunoreactive process in RA, their activated phenotype reflecting the proinflammatory milieu. However, FLS from patients with RA also display unique aggressive features that are autonomous and vertically transmitted, and these cells can behave as primary promoters of inflammation. The molecular bases of this 'imprinted aggressor' phenotype are being clarified through genetic and epigenetic studies. The dual behaviour of FLS in RA suggests that FLS-directed therapies could become a complementary approach to immune-directed therapies in this disease. Pathophysiological characteristics of FLS in RA, as well as progress in targeting these cells, are reviewed in this manuscript. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Many cellular signaling events are regulated by tyrosine phosphorylation and mediated by the opposing actions of protein tyrosine kinases and phosphatases. Protein tyrosine phosphatases are emerging as drug targets, but poor cell permeability of inhibitors has limited the development of drugs targeting these enzymes [Tautz L, et al. (2006) Expert Opin Ther Targets 10:157-177]. Here we developed a method to monitor tyrosine phosphatase activity at the single-cell level and applied it to the identification of cell-permeable inhibitors. The method takes advantage of the fluorogenic properties of phosphorylated coumaryl amino propionic acid (pCAP), an analog of phosphotyrosine, which can be incorporated into peptides. Once delivered into cells, pCAP peptides were dephosphorylated by protein tyrosine phosphatases, and the resulting cell fluorescence could be monitored by flow cytometry and high-content imaging. The robustness and sensitivity of the assay was validated using peptides preferentially dephosphorylated by CD45 and T-cell tyrosine phosphatase and available inhibitors of these two enzymes. The assay was applied to high-throughput screening for inhibitors of CD45, an important target for autoimmunity and infectious diseases [Hermiston ML, et al. (2003) Annu Rev Immunol 21:107-137]. We identified four CD45 inhibitors that showed activity in T cells and macrophages. These results indicate that our assay can be applied to primary screening for inhibitors of CD45 and of other protein tyrosine phosphatases to increase the yield of biologically active inhibitors. [ABSTRACT FROM AUTHOR]

The article talks about the influence of PTPN22 R263Q polymorphism on the risk of rheumatoid arthritis (RA). Taq- Man 5'-allele discrimination assay was used to genotype the samples for the polymorphisms. The effect of the R263Q variant was analyzed with the effect of R620W, using Unphased and Stata 10 software. The study implied that the minor allele of the PTPN22 R263Q polymorphism had an additive effect on the risk of RA.

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. [ABSTRACT FROM AUTHOR]

Objective: To search for possible effects of two polymorphisms and of the solar cycle of illumination on reproductive success.Design: Study of haptoglobin (Hp) and ACP1 polymorphisms in consecutive puerperae and analysis of phenotype distribution in relation to time of conception.Setting: The Maternity Department of Penne Hospital, Penne, Italy.Patient(s): Three hundred sixty-eight consecutive healthy pueperae from the Caucasian population.Result(s): The distribution of Hp and ACP1 phenotypes depends on the phase of the solar cycle at conception. Women homozygous for Hp with low ACP1 activity are more likely to conceive in the first part of the year. Women heterozygous for Hp with medium-high ACP1 activity are more likely to conceive in the last part of the year.Conclusion(s): In the first months of the year there is a steady increase in solar illumination, and this phase corresponds to the best period for reproduction in most plants and animals. This period is also the coldest in the Italian latitudes. Although humans are not seasonal breeders, it is possible that women having a genetic background best adapted to the metabolic demand of the cold period of the year will respond better to reproductive stimuli, resulting in a higher probability of conceiving in the first part of the year. [ABSTRACT FROM AUTHOR]

The well-known relationship between low birth weight and allergies prompted us to investigate a possible pleiotropic effect of ACP1 on these conditions. ACP1 is a polymorphic enzyme that affects signal transduction of insulin and other growth factors, T-cell receptor signaling, and the regulation of flavoenzyme activity. Our aim was to compare the relationship between ACP1 and allergy with the relationship between ACP1 and birth weight. We studied 299 subjects from the Caucasian population of England, 124 subjects from the Caucasian population of central Italy, and 302 healthy puerperae and their newborn babies from the same Caucasian populations. ACP1 phenotype was determined by starch gel electrophoresis on RBC hemolysate and by DNA analysis. Subjects with high ACP1 activity (ACP1 C,B phenotype) show a lower level of IgE compared to subjects with low ACP1 activity (p = 0.01). The proportion of infants with a birth weight below the first quartile is lower among infants born to mothers with high ACP1 activity than among infants born to mothers with medium-low activity (p = 0.01). The data suggest a protective effect of high-activity ACP1 C,B phenotype from low birth weight and from allergic manifestations after birth. [ABSTRACT FROM AUTHOR]

The discovery that a single-nucleotide polymorphism (SNP) in lymphoid tyrosine phosphatase (LYP), encoded by the PTPN22 gene, is associated with type 1 diabetes (T1D) has now been verified by numerous studies and has been expanded to rheumatoid arthritis, juvenile rheumatoid arthritis (JRA), systemic lupus erythematosus, Graves' disease, generalized vitiligo and other human autoimmune diseases. In this paper, we discuss the association of PTPN22 with autoimmunity, the biochemistry of the PTPN22-encoded phosphatase, and the molecular mechanism(s) by which the disease-predisposing allele contributes to the development of human disease. [ABSTRACT FROM AUTHOR]

Recent studies suggest that genetic polymorphism modulates immunoglobulin E (IgE)—mediated atopic reactions. Adenosine is an important local hormone influencing immune function and tissue reactivity; because adenosine concentration is regulated by adenosine deaminase (ADA), we have investigated the possible effect of ADA polymorphism on the relationship between IgE and positive prick test. A random sample of 160 schoolchildren from the population of Viterbo (Italy) were studied. Prick testing was performed with a panel of local allergens. Total IgE assay was performed according to standard clinical procedure. ADA phenotype was determined according to Spencer et al. A highly significant correlation between prick test and IgE was observed. However, the strength of correlation was moderate (η² = 0.16), indicating that positive prick testing depends on other variables besides IgE. The relationship between IgE and positive prick testing is stronger in carriers of ADA*2 allele than in ADA*1/*1 subjects. Also, sensitivity and predictive values are higher in ADA*2 carriers than in homozygous ADA*1/*1 children. The data suggest that the effect of IgE level on local reactivity is influenced by ADA polymorphism; at low level of IgE, the presence of the ADA*2 allele seems to protect from positive prick testing. [ABSTRACT FROM AUTHOR]

MEG2, a protein tyrosine phosphatase with a unique NH2-terminal lipid-binding domain, binds to and is modulated by the polyphosphoinositides PI(4,5)P2 and PI(3,4,5)P3. Recent data implicate MEG2 in vesicle fusion events in leukocytes. Through the genesis of Meg2-deficient mice, we demonstrate that Meg2-/- embryos manifest hemorrhages, neural tube defects including exencephaly and meningomyeloceles, cerebral infarctions, abnormal bone development, and >90% late embryonic lethality. T lymphocytes and platelets isolated from recombination activating gene 2-/- mice transplanted with Meg2-/- embryonic liver-derived hematopoietic progenitor cells showed profound defects in activation that, in T lymphocytes, was attributable to impaired interleukin 2 secretion. Ultrastructural analysis of these lymphocytes revealed near complete absence of mature secretory vesicles. Taken together, these observations suggest that MEG2-mediated modulation of secretory vesicle genesis and function plays an essential role in neural tube, vascular, and bone development as well as activation of mature platelets and lymphocytes. [ABSTRACT FROM AUTHOR]

In recent years bacterial protein-tyrosine kinases have been found to phosphorylate a growing number of protein substrates, including RNA polymerase sigma factors, UDP-glucose dehydrogenases and single-stranded DNA-binding proteins. The activity of these protein substrates was affected by tyrosine phosphorylation, indicating that this post-translational modification could regulate physiological processes ranging from stress response and exopolysaccharide synthesis to DNA metabolism. Some interesting work in this field was done in Bacillus subtilis, and we here present the current state of knowledge on protein-tyrosine phosphorylation in this gram-positive model organism. With its two kinases, two kinase modulators, three phosphatases and at least four different tyrosine-phosphorylated substrates, B. subtilis is the bacterium with the highest number of presently known participants in the global network of protein-tyrosine phosphorylation. We discuss the approaches currently used to chart this network: ranging from studies of substrate specificity and the physiological role of tyrosine phosphorylation of individual enzymes to the global approaches at the level of systems biology. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Acid phosphatase locus 1 (ACP1) or cytosolic low molecular weight protein tyrosine phosphatase is a polymorphic enzyme that can hydrolyze phosphotyrosine-containing peptides of the human insulin receptor and of band 3 protein. High-activity ACP1 may favor an increase in serum glucose concentration through a depression of insulin action and through inactivation of aldolase, phosphofructokinase, and glyceraldehyde-3-phosphate dehydrogenase induced by dephosphorylation of band 3 protein. In diabetic subjects, we have previously reported lower serum glucose concentration in subjects with low-activity ACP1 A and AB phenotypes. We have now studied the relationship between serum glucose concentration and ACP1 genotype in a sample of 137 healthy adult workers of our university. In males, serum glucose concentration is significantly higher in medium-high– than in low-activity ACP1 genotypes. With advancing age in males, there is a progressive increase in glycemic differential between medium-high– and low-activity ACP1 genotypes. The data suggest that normal variability of ACP1 genotype influences serum glucose concentration in normal individuals. Such influence depends on sex and in males becomes more marked with advancing age. [Copyright &y& Elsevier]

Reversible tyrosine phosphorylation of proteins is a key regulatory mechanism for numerous important aspects of eukaryotic physiology and is catalysed by kinases and phosphatases. Together, cells of the immune system express at least half of the 107 protein tyrosine phosphatase (PTP) genes in the human genome, most of which encode multidomain proteins that contain protein- and phospholipid-interaction domains. Here, we discuss the diverse but specific, and important, roles that PTPs have in immune cells, focusing mainly on T and B cells, and we highlight recent evidence that even subtle alterations in PTPs can cause immune dysfunction and human disease. [ABSTRACT FROM AUTHOR]

Glucose-6-Phosphate Dehydrogenase has been studied in 5267 consecutivenewborn infants from Sardinian population during a four years period. The proportion of G-6-PD deficient female infants is much higher in thoseconceived in the winter-spring than among those conceived in summer-autumn,resulting in a lower sex ratio among G-6-PD deficient infants conceived inwinter-spring as compared to G-6-PD deficient infants conceived in the summer-autumn.The overall frequency of the gene for G-6-PD deficiency is much lower in infantsconceived in the summer period than in infants conceived in the other seasons. A greater reproductive efficiency of G-6-PD deficient males in the winter-springseason and/or some effect at post zygotic level favouring the survival ofheterozygous G-6-PD deficient females conceived in the winter-spring periodcould contribute to the pattern described. Fresh vegetables containing oxidativesubstances are more abundant in the spring time. These substances may interactwith seasonal reproductive cycles influencing reproduction efficiency of G-6-PDdeficient males and/or the relative survival rate of heterozygous female embryos. [ABSTRACT FROM AUTHOR]

Investigates the possible differential effects of A and B blood group materno-fetal incompatibility on human fertility. Comparative analysis of couples with recurrent spontaneous abortion and healthy mothers; Role of anti-B immunoglobulin against fetal loss in mother-infant ABO incompatibility.

Humoral immunity relies on the efficient differentiation of memory B cells (MBCs) into antibody-secreting cells (ASCs). T helper (Th) signals upregulate B cell receptor (BCR) signaling by potentiating Src family kinases through increasing CD45 phosphatase activity (CD45 PA). In this study, we show that high CD45 PA in MBCs enhances BCR signaling and is essential for their effective ASC differentiation. Mechanistically, Th signals upregulate CD45 PA through intensifying the surface binding of a CD45 ligand, Galectin-1. CD45 PA works as a sensor of T cell help and defines high-affinity germinal center (GC) plasma cell (PC) precursors characterized by IRF4 expression in vivo. Increasing T cell help in vitro results in an incremental CD45 PA increase and enhances ASC differentiation by facilitating effective induction of the transcription factors IRF4 and BLIMP1. This study connects Th signals with BCR signaling through Galectin-1-dependent regulation of CD45 PA and provides a mechanism for efficient ASC differentiation of MBCs. [Display omitted] • Memory B cells (MBCs) have high CD45 phosphatase activity • CD45 phosphatase activity defines high-affinity plasma cell precursors • Effective ASC differentiation of MBCs depends on high CD45 phosphatase activity • CD40L upregulates CD45 phosphatase activity through surface binding of Galectin-1 Szodoray et al. demonstrate that T helper signals upregulate CD45 phosphatase activity in B cells through increased binding of Galectin-1 to CD45. High CD45 phosphatase activity in memory B cells controls their effective differentiation toward antibody-secreting cells in response to T cell help. [ABSTRACT FROM AUTHOR]

Objective: Rheumatoid arthritis (RA) is an autoimmune disease in which the joint lining or synovium becomes highly inflamed and majorly contributes to disease progression. Understanding pathogenic processes in RA synovium is critical for identifying therapeutic targets. We performed laser capture microscopy (LCM) followed by RNA sequencing (LCM‐RNAseq) to study regional transcriptomes throughout RA synovium. Methods: Synovial lining, sublining, and vessel samples were captured by LCM from seven patients with RA and seven patients with osteoarthritis (OA). RNAseq was performed on RNA extracted from captured tissue. Principal component analysis was performed on the sample set by disease state. Differential expression analysis was performed between disease states based on log2 fold change and q value parameters. Pathway analysis was performed using the Reactome Pathway Database on differentially expressed genes among disease states. Significantly enriched pathways in each synovial region were selected based on the false discovery rate. Results: RA and OA transcriptomes were distinguishable by principal component analysis. Pairwise comparisons of synovial lining, sublining, and vessel samples between RA and OA revealed substantial differences in transcriptional patterns throughout the synovium. Hierarchical clustering of pathways based on significance revealed a pattern of association between biologic function and synovial topology. Analysis of pathways uniquely enriched in each region revealed distinct phenotypic abnormalities. As examples, RA lining samples were marked by anomalous immune cell signaling, RA sublining samples were marked by aberrant cell cycle, and RA vessel samples were marked by alterations in heme scavenging. Conclusion: LCM‐RNAseq confirms reported transcriptional differences between the RA synovium and the OA synovium and provides evidence supporting a relationship between synovial topology and molecular anomalies in RA. [ABSTRACT FROM AUTHOR]

Protein tyrosine phosphatase nonreceptor type 22 (PTPN22) is encoded by a major autoimmunity gene and is a known inhibitor of T cell receptor (TCR) signaling and drug target for cancer immunotherapy. However, little is known about PTPN22 posttranslational regulation. Here, we characterize a phosphorylation site at Ser325 situated C terminal to the catalytic domain of PTPN22 and its roles in altering protein function. In human T cells, Ser325 is phosphorylated by glycogen synthase kinase-3 (GSK3) following TCR stimulation, which promotes its TCR-inhibitory activity. Signaling through the major TCR-dependent pathway under PTPN22 control was enhanced by CRISPR/Cas9-mediated suppression of Ser325 phosphorylation and inhibited by mimicking it via glutamic acid substitution. Global phospho-mass spectrometry showed Ser325 phosphorylation state alters downstream transcriptional activity through enrichment of Swi3p, Rsc8p, and Moira domain binding proteins, and next-generation sequencing revealed it differentially regulates the expression of chemokines and T cell activation pathways. Moreover, in vitro kinetic data suggest the modulation of activity depends on a cellular context. Finally, we begin to address the structural and mechanistic basis for the influence of Ser325 phosphorylation on the protein’s properties by deuterium exchange mass spectrometry and NMR spectroscopy. In conclusion, this study explores the function of a novel phosphorylation site of PTPN22 that is involved in complex regulation of TCR signaling and provides details that might inform the future development of allosteric modulators of PTPN22. [ABSTRACT FROM AUTHOR]

Circadian rhythms mediated by both central and tissue-specific peripheral clocks allow for the synchronization of biological processes with diurnal cycles such as activity and rest. Disruption of these rhythms can be caused by altered sleep-awake patterns or by pathological conditions and can initiate or exacerbate human disease through mechanisms that are only partially understood. In this issue, Dudek et al. identify a chondrocyte-autonomous cartilage clock and demonstrate that expression of an important circadian pacemaker, BMAL1, decreases during osteoarthritis progression. They show that chondrocyte-specific deletion of BMAL1 leads to cartilage degradation and disruption of key pathways, shifting cartilage homeostasis toward a catabolic state. These findings provide insight into the interplay between circadian rhythm and cartilage in osteoarthritis. [ABSTRACT FROM AUTHOR]

The article discusses highlights of translational studies in rheumatology published from 2005 to 2015. Topics covered include the characteristics of interleukin 17-producing T helper cells, type I interferon as a drug target for systemic lupus erythematosus (SLE) and the identification of the transmembrane molecule cadherin-11 as a regulator of cartilage damage and synovial intimal lining formation.

Background We recently identified a human B-cell population that is naturally autoreactive and tolerized by functional anergy (B ND cells). Objective We sought to identify the molecular mechanism of how anergic autoreactive B ND cells escape functional anergy and whether this process is altered in patients with lupus. Methods Isolated peripheral blood naive and B ND cells were cultured with various stimuli, and their activation status was determined by using an intracellular Ca 2+ mobilization assay. Lyn kinase and Syk activities were assessed by using phospho-flow analysis. CD45 phosphatase activity was determined by using a novel flow-based assay, which takes advantage of the fluorogenic properties of phosphorylated coumaryl amino propionic acid, an analog of phosphotyrosine, which can be incorporated into peptides. Real-time quantitative PCR was used to quantitate LYN , SYK , and CD45 mRNA. Results T-helper signals reversed the state of anergy, allowing B ND cells to fully respond to antigenic stimulation by restoring signaling through the B-cell receptor (BCR). The mechanism was dependent on increased activity of the tyrosine phosphatase CD45 and CD45-dependent activation of Lyn and Syk. CD45 phosphatase activity was increased by T-cell help both in B ND and naive B cells. Furthermore, we found that B ND cells obtained from patients with systemic lupus erythematosus exhibited increased CD45 activity and BCR-signaling capacity, thus being less tolerized than B ND cells from healthy control subjects. Conclusion Our findings suggest that CD45 is a key regulator of BCR-signaling thresholds mediated by T-cell help. This raises the possibility that B ND cells could represent precursors of autoantibody-secreting plasma cells and suggests a role for these autoreactive B cells in contributing to autoimmunity if not properly controlled. [ABSTRACT FROM AUTHOR]