The protein tyrosine phosphatase PTPN22 controls forkhead box protein 3 T regulatory cell induction but is dispensable for T helper type 1 cell polarization.

Protein tyrosine phosphatases (PTPs) regulate T cell receptor (TCR) signalling and thus have a role in T cell differentiation. Here we tested whether the autoimmune predisposing gene PTPN22 encoding for a PTP that inhibits TCR signalling affects the generation of forkhead box protein 3 (FoxP3)(+) T regulatory (Treg ) cells and T helper type 1 (Th1) cells. Murine CD4(+) T cells isolated from Ptpn22 knock-out (Ptpn22(KO) ) mice cultured in Treg cell polarizing conditions showed increased sensitivity to TCR activation compared to wild-type (WT) cells, and subsequently reduced FoxP3 expression at optimal-to-high levels of activation. However, at lower levels of TCR activation, Ptpn22(KO) CD4(+) T cells showed enhanced expression of FoxP3. Similar experiments in humans revealed that at optimal levels of TCR activation PTPN22 knock-down by specific oligonucleotides compromises the differentiation of naive CD4(+) T cells into Treg cells. Notably, in vivo Treg cell conversion experiments in mice showed delayed kinetic but overall increased frequency and number of Treg cells in the absence of Ptpn22. In contrast, the in vitro and in vivo generation of Th1 cells was comparable between WT and Ptpn22(KO) mice, thus suggesting PTPN22 as a FoxP3-specific regulating factor. Together, these results propose PTPN22 as a key factor in setting the proper threshold for FoxP3(+) Treg cell differentiation.

A study of Adenosine-Deaminase genetic polymorphism in rheumatoid arthritis.

Recent investigations suggest that Adenosine Deaminase (ADA) could play a role in susceptibility to rheumatoid arthritis (RA). The purpose of our study is to investigate the possible role of genetic variability of ADA in the susceptibility to RA. We studied three intragenic ADA polymorphisms, ADA1, ADA2 and ADA6, in a sample of 91 subjects with RA and in 246 healthy subjects from the same Caucasian population and compared genotype and pairwise haplotype distributions between cases and controls. No statistically significant differences between RA and controls are observed for ADA genotypes. A border line difference for ADA1-ADA2 haplotype distribution is observed due to a decreased proportion of ADA1 *2/ADA2 *2 haplotype in RA compared to controls. Our data indicate a border line effect of ADA gene polymorphism on susceptibility to RA that need to be confirmed in other clinical settings.

A study of three polymorphic sites of the ADA gene in children with type 1 diabetes mellitus.

BACKGROUND: Adenosine deaminase is a polymorphic enzyme that has an important role in immune functions and in the regulation of intracellular and extracellular concentrations of adenosine and adenosine receptor activity. AIM: To search for possible association of type 1 diabetes mellitus (DM1) with three loci haplotypes (ADA1, ADA2, ADA6) of the adenosine deaminase gene. PATIENTS: One hundred and eighty-nine consecutive children with DM1 from Sassari, Sardinia, and a control sample of 239 children from the same area were studied. METHODS: ADA loci genotypes were determined by DNA analysis. RESULTS: Compared to controls, diabetic boys show a decrease of the 2(2)/6(1) haplotype while diabetic girls show an increase of the same haplotype. This association was replicated in an independent sample from Continental Italy. CONCLUSIONS: The 2(2)/6(1) haplotype may exert a protective action in males but may increase susceptibility to DM1 in females: OR = 0.398, 95% CI 0.16-0.96 for males, and OR = 2.31, 95% CI 1.32-4.06 for females.

rs2476601 T allele (R620W) defines high-risk PTPN22 type I diabetes-associated haplotypes with preliminary evidence for an additional protective haplotype.

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is the third major locus affecting risk of type I diabetes (T1D), after HLA-DR/DQ and INS. The most associated single-nucleotide polymorphism (SNP), rs2476601, has a C->T variant and results in an arginine (R) to tryptophan (W) amino acid change at position 620. To assess whether this, or other specific variants, are responsible for T1D risk, the Type I Diabetes Genetics Consortium analyzed 28 PTPN22 SNPs in 2295 affected sib-pair (ASP) families. Transmission Disequilibrium Test analyses of haplotypes revealed that all three haplotypes with a T allele at rs2476601 were overtransmitted to affected children, and two of these three haplotypes showed statistically significant overtransmission (P=0.003 to P=5.9E-12). Another haplotype had decreased transmission to affected children (P=3.5E-05). All haplotypes containing the rs2476601 T allele were identical for all SNPs across PTPN22 and only varied at centromeric SNPs. When considering rs2476601 'C' founder chromosomes, a second haplotype (AGGGGC) centromeric of PTPN22 in the C1orf178 region was associated with protection from T1D (odds ratio=0.81, P=0.0005). This novel finding requires replication in independent populations. We conclude the major association of PTPN22 with T1D is likely due to the recognized non-synonymous SNP rs2476601 (R620W).

Association of PTPN22 gene functional variants with development of pulmonary tuberculosis in Moroccan population.

Mycobacterium tuberculosis, the causal agent of pulmonary tuberculosis (TB), remains a major health problem throughout the world causing high mortality in humans. Previous studies showed that several genes may play crucial roles in susceptibility to TB. The PTPN22 gene encodes the lymphoid tyrosine phosphatase that has an important regulatory effect on T- and B-cell activation in immune response. The purpose of this study was to investigate the role of two functional missense single nucleotide polymorphisms (SNPs) of the PTPN22 gene region (R620W and R263Q) in the susceptibility to TB in the Moroccan population. A case-control association study was performed including 123 pulmonary TB patients and 155 healthy controls. All subjects were genotyped by TaqMan SNP genotyping assays. Regarding the PTPN22 R620W (C1858T) SNP, we observed a statistically significant difference in the distribution of the PTPN22 1885T allele between pulmonary TB patients and healthy controls (0.41% vs 3.2%, P = 0.01, odds ratio (OR) = 0.14, 95% confidence interval (CI) = 0.01-0.93). With respect to the PTPN22 R263Q (G788A), we observed an increase of 788A allele frequencies in TB patients compared with those in healthy controls (3.65% vs 0.65%, P = 0.01, OR = 5.85, 95% CI = 1.17-39.55). These results suggest that PTPN22 gene variants may affect susceptibility to TB in the Moroccan population.

ACP1 genetic polymorphism and coronary artery disease: an association study.

OBJECTIVES: Assuming an immune component in the pathogenesis of atherosclerosis, we have investigated a possible association between coronary artery disease (CAD) and the acid phosphatase locus 1 (ACP1) genetic polymorphism, which has previously been found to be associated with immune disorders. METHODS: 226 subjects admitted to the hospital for CAD, 358 consecutive newborn infants, 279 adult subjects with type 2 diabetes without CAD and 137 adults without diabetes and without CAD from the Caucasian population of Rome were studied. The ACP1 genotype was determined by DNA analysis. Statistical analyses were performed using the SPSS package. RESULTS: CAD females showed an excess of ACP1 *A/*C and *B/*C genotypes and a deficiency of ACP1 *B/*B genotype compared to controls, while CAD males did not show significant differences. Among diabetic women the proportion of *C allele carriers was much greater in those with CAD than in those without CAD. This difference was much less evident in nondiabetic women. CONCLUSION: ACP1 may be involved in susceptibility to CAD. Since ACP1 has been found to be associated with immunological diseases, our observation reinforces the notion of an immune component in the pathogenesis of atherosclerosis.

Skin testing correlates negatively with high-activity ACP1 *B/*C genotype.

BACKGROUND: Previous studies have shown a negative association between ACP1 *B/*C genotype and total IgE level. ACP1 (acid phosphatase locus 1) is a polymorphic phosphotyrosine phosphatase that interacts with IL4-RA and is involved in T cell receptor signaling. METHODS: In the present paper, we have studied the relationship between *B/*C genotype which shows high ACP1 activity and skin testing in 300 adult subjects referred for allergic manifestations. ACP1 genotypes were determined by DNA analysis. RESULTS: There is a significant negative correlation between the intensity of skin test reaction and *B/*C genotype (p = 0.01). The proportion of *B/*C genotype is lower in allergic subjects with intense skin reaction than in allergic subjects with moderate skin reaction and in healthy controls. CONCLUSIONS: This new observation confirms by a different approach the relationship between ACP1 polymorphism and allergic manifestations, suggesting that high ACP1 activity protects against these manifestations.

Feto-maternal ACP1 activity ratio and intrauterine survival.

OBJECTIVE: Genetic differences in the activity of phosphotyrosine phosphatases between mother and embryo could result in a differential activation of signals induced by growth factors in the two sides of placenta. Previous observations suggest that this may have important effects on intrauterine development and survival. The aim of the present study is to confirm previous observations and show new data. STUDY DESIGN: We have studied 573 mother/newborn pairs, 169 wife/husband couples with repeated spontaneous abortion and 34 fertile wife/husband couples RESULTS: In mother/newborn pairs, the analysis of joint mother/infant ACP1 distribution has shown a deficit of pairs with the mother having low ACP1 S isoform concentration and the infant having high S isoform concentration, and an excess of pairs with the mother having high S isoform concentration and the infant having low S isoform concentration. In RSA couples there is an excess of couples in which the wife has low S isoform concentration and the husband has high S isoform concentration and a deficit of couples in which the wife has high S isoform concentration and the husband has low S isoform concentration. In fertile couples the pattern is reversed. CONCLUSION: The data suggest that when the mother to fetus S isoform concentration ratio is in favour of the mother, the probability of survival of the fetus is greater than in the opposite situation.

ACP1 and offspring sex ratio in smoking puerperae: a study at population level.

BACKGROUND: Data from previous study by our group suggest that in smoking women sex ratio of offspring is higher in newborns carrying ACP1C allele than in other ACP1 genotypes, suggesting that differences observed among human population concerning the effect of smoking may depend in part on this genetic factor. OBJECTIVES: In order to further explore this issue we have studied another population and have analysed the relationship between sex ratio and ACP1C gene frequency at population level. METHODS: The analysis includes 719 consecutive births from Central Italy considered in a previous paper and 5510 consecutive births from Sardinia. Data from English and Japanese populations have also been considered in the analysis. RESULTS: Among newborns not carrying ACP1C there is a decrease of SR among the offspring of smoking mothers, while among newborns carrying the ACP1C allele there is an increase of SR among the offspring of smoking mothers relative to non-smoking mothers. Considering Sardinian, Italian, English and Japanese population there is a linear positive relationship between C allele frequency and SR in smoking mothers. CONCLUSIONS: The present observation suggests an interaction between smoking and ACP1 regarding their effects on sex ratio, by which the presence of the ACP1C allele appears to counteract the effect of smoking. This suggests that genetic background may modify the effects of toxic environmental factors on gamete production and functionality and/or on intrauterine survival.

Protein tyrosine phosphatases.

The molecular mechanisms of signal transduction have been at the focus of increasingly intense scientific research. As a result, our understanding of protein tyrosine kinase-mediated signaling has advanced at an unprecedented pace during the past decade. In contrast, the study of protein tyrosine phosphatases has lagged behind, but is now gathering momentum and is predicted to become a "hot topic" in the field within the next few years. This review summarizes the current state-of-the art in our understanding of the structure, regulation and role of protein tyrosine phosphatases with emphasis on the lymphocyte system.

The genetics of signal transduction and the outcome of diagnostic tests in growth retardation.

The effects of 'normal' genetic variability of signal transduction on endocrine function may be more evident during stimulation tests than is observed in basal states, thereby contributing to a greater understanding of the possible role of signal transduction genetics in the pathogenesis of endocrine disorders. In the present study, we have studied the outcome of growth hormone (GH) stimulation testing by insulin in growth-retarded children in relation to the genotype of ACP1 (acid phosphatase locus 1; also referred to as cLMWPTP, cytosolic low molecular weight phosphotyrosine phosphatase). ACP1 is an enzyme, expressed as two distinct isoforms designated F and S, that down-regulates insulin receptor signal transduction and which shows a genetic polymorphism with strong quantitative enzymatic differences among genotypes. In this study, we examined 116 growth-retarded children of which 101 were genotyped for ACP1. We found that the basal level of GH is higher in ACP1 genotypes with low concentrations of the S isoform than in genotypes with high S isoform concentrations (P<0.02). Additionally, during GH stimulation with insulin, the genotypes with low S isoform concentrations were found to perform better (P<0.005) and to react more promptly than the genotypes with high S isoform concentrations (P<0.05). These findings suggest that high S isoform ACP1 activity slows down the effect of insulin, resulting in a retardation of its metabolic effect.

The genetics of signal transduction and the feto-maternal relationship. A study of cytosolic low molecular weight phosphotyrosine phosphatase.

Intracellular kinases mediate positive signalling from surface receptors by phosphorylating critical target proteins whereas phosphatases inhibit this process. Differential phosphatase activity at the feto-maternal interface could determine the appropriate relative growth and development on each side of the placenta. The highly polymorphic cytosolic low molecular weight phosphotyrosine-phosphatase (ACP1-cLMWPTPase) has been studied in 170 women who had at least two consecutive spontaneous abortions along with their husbands and in 352 normal puerperae along with their newborn babies. Symmetry analysis of joint wife/husband and mother/infant distribution suggests that when ACP1 activity is lower in the mother than in either her aborted fetus or her child, the probability of abortion is higher and the survival to term is lower as compared to pairs in which the ACP1 activity is higher in the mother than in her fetus. Further analysis has shown that the effect is due to S isoform: i.e. a high mother/fetus S isoform ratio favours intrauterine survival. Analysis of gestational duration and birth weight suggests that a high ACP1 maternal activity coupled with a low or moderate fetal activity favour fetal growth and developmental maturation. The present data indicate that maternal-fetal genetic differences in signal transduction could contribute significantly to variability of intrauterine developmental parameters and to pathological manifestation of pregnancy.

Phosphotyrosine-protein-phosphatase and diabetic disorders. Further studies on the relationship between low molecular weight acid phosphatase genotype and degree of glycemic control.

We have studied a new sample of 276 NIDDM patients from the population of Penne (Italy). Comparison of the new data with those of 214 diabetic pregnant women from the population of Rome reported in a previous paper has shown that the pattern of association between low molecular weight acid phosphatase genotype and degree of glycemic control is similar in the two classes of diabetic patients. Among nonobese subjects the proportion of ACP1*A (the allele showing the lowest enzymatic activity) is lower in diabetic patients with high glycemic levels (mean value greater than 8.9 mmol/l) than in diabetic patients with a low glycemic level (mean value less than 8.9 mmol/l). Among obese subjects no significant association is observed between glycemic levels and ACP1. Among nonobese subjects the concentration of f isoform of ACP1 is higher in patients showing a high glycemic level than in patients showing a low glycemic level. No significant difference is observed for s isoform.

Inflammatory bowel disease: Are there gender differences in the genetics of signal transduction? A preliminary study of cytosolic low molecular weight protein tyrosine phosphatase.

The phenotype of cytosolic Low Molecular Weight Protein Tyrosine Phosphatase (cLMWPTP or ACP1), an enzyme involved in signal transduction of insulin, PDGF and T-cell receptors, has been determined in 71 patients with Crohn's Disease (CD: 37 males and 34 females), 49 patients with Ulcerative Colitis (UC: 27 males and 22 females) and 358 consecutive newborns (194 males and 164 females). cLMWPTP phenotypes showing a high concentration of F isoforms are associated with CD in females and with UC in males. Since PTPases counteract the effects of protein tyrosines kinases, a high concentration of F isoform of cLMWPTP may influence the mucosal response to pathogenic factors, increasing susceptibility to CD in females and to UC in males.

Diabetic complications and the genetics of signal transduction. A study of retinopathy in NIDDM.

Cytosolic low molecular weight acid phosphatase (ACP1) is a high polymorphic phosphotyrosine-protein-phosphatase involved in signal transduction. In NIDDM subjects we have found that ACP1 genotype is a highly significant predictor of retinopathy, suggesting that genetic variability of signal transduction may have an important role in the susceptibility to this complication. Adenosine deaminase, ABO blood groups and several clinical variables have been also considered. The results point out the importance of interactions between genetic systems. Among non-genetic variables dislipidemia and treatment with insulin are significantly associated with retinopathy.

Type 2 diabetes and the genetics of signal transduction: a study of interaction between adenosine deaminase and acid phosphatase locus 1 polymorphisms.

Acid phosphatase locus 1 (ACP1) is a highly polymorphic enzyme that has an important role in flavoenzyme activity and in the control of insulin receptor activity and band 3 protein phosphorylation status. Adenosine deaminase (ADA) is a polymorphic enzyme that catalyses the irreversible deamination of adenosine to inosine and has an important role in regulating adenosine concentration. Based on the hypothesis that ACP1 counteracts insulin signaling by dephosphorylating the insulin receptor and that adenosine has an anti-insulin action, we reasoned that low ACP1 activity (low dephosphorylating action on insulin receptor) when associated with high ADA activity (low adenosine concentration) would result in a cumulative effect towards an increased glucose tolerance. On the contrary, high ACP1 activity when associated with low ADA activity would result in a cumulative effect towards a decreased glucose tolerance. A total of 280 adult subjects with type 2 diabetes from the population of Penne (Italy) were studied. There was a nonsignificant trend toward an increase in the proportion of subjects with the complex type with high ACP1 activity and low ADA activity (ie, *B/*B; *A/*C; *B/*C; *C/*C//ADA*1/*2 and *2/*2) in type 2 diabetes relative to that observed in newborn infants from the same population. High ACP1 activity/low ADA activity joint genotype was positively associated with high glycemic levels and with high body mass index (BMI) values. Low ACP1 activity/high ADA activity joint genotype was also positively associated with dyslipidemia. These findings suggest that both ACP1 and ADA contribute to the clinical manifestations of type 2 diabetes and probably also have a marginal influence on susceptibility to the disease. Both additive and epistatic interactions between the 2 systems seem to be operative.

Genotypes of cytosolic low-molecular-weight protein-tyrosine-phosphatase correlate with age at onset of type 1 diabetes in a sex-specific manner.

We investigated the possible role of cytosolic low-molecular-weight protein-tyrosine-phosphatase (cLMWPTP or acid phosphatase locus 1 [ACP1]) in the mediation of age at onset of type 1 diabetes. ACP1 is an enzyme involved in signal transduction of T-cell receptors, insulin, and other growth factor receptors. We studied acid phosphatase polymorphism in 189 consecutive children with type 1 diabetes admitted to the Pediatric Clinic of Sassari University (Sardinia) and in 86 adolescent patients with recently diagnosed type 1 diabetes from continental Italy. In both populations, females with medium-high activity acid phosphatase genotypes had onset of disease significantly earlier than males. The data suggest that acid phosphatase genotype affects the age of onset and probably also the sex ratio in type 1 diabetes. Sex hormones might modulate the susceptibility to autoimmune diseases, including type 1 diabetes, through the influence of signal transduction pathways involved in immune functions. Elucidation of the molecular basis for gender differences in the course and severity of type 1 diabetes could have important implications for treatment as well, because there might be gender-specific effects in the response to immunotherapy.

Haptoglobin genotype and natural fertility in humans.

OBJECTIVE: To study the possible relation between human natural fertility and haptoglobin (Hp) genotype. DESIGN: Prospective study. SETTING: Maternity departments of local hospitals in two Italian localities. PATIENT(S): Healthy women who had just given birth in the maternity departments of two local hospitals (n = 679). INTERVENTION(S): Venous blood collection for determination of Hp genotype with the use of starch gel electrophoresis of hemoglobin-supplemented serum. MAIN OUTCOME MEASURE(S): Distribution of Hp genotypes in relation to age of puerperae. RESULT(S): In both populations, the proportion of young mothers was much higher among women who were homozygous for the Hp*1 allele (the Hp*1/*1 genotype) than among women who had other Hp genotypes. In addition, the proportion of multiparous women among the older mothers was higher among those with the Hp*1/*1 genotype than among those with other Hp genotypes. CONCLUSION(S): The data suggest that women with the Hp*1/*1 genotype reproduce at an earlier age and have higher natural fertility potential than women with other Hp genotypes.

Smoking and the genetics of signal transduction: an association study on retinopathy in type 1 diabetes.

BACKGROUND: Recent studies suggest a complex association between smoking and retinopathy that probably depends on the interaction between many variables. We have reported an association between ACP1 phenotype and retinopathy in type 1 diabetes. Additionally, the deleterious effects of smoking on intrauterine growth are dependent on ACP1, a low-molecular-weight tyrosine phosphatase that modifies signal transduction. We examine here the interaction between smoking and ACP1 as a mediator of susceptibility to diabetic retinopathy in a sample of puerperae with type 1 diabetes. SUBJECTS AND METHODS: Seventy-eight women who had just delivered live infants were studied. ACP1 phenotype was determined by starch gel electrophoresis. Three-way contingency tables were analyzed. RESULTS: There is a significant epistatic interaction between smoking and ACP1 phenotype concerning their effects on retinopathy. In subjects with low ACP1 activity, frequency of retinopathy was slightly higher in smokers than in nonsmokers. However, in subjects with medium-high ACP1 activity, frequency of retinopathy was significantly lower in smokers than in nonsmokers. A logistic regression analysis using retinopathy as the dependent variable revealed that smoking, ACP1, and ACP1 by smoking interaction, as well as the interaction between smoking and age of the women, are the most robust predictors of retinopathy. CONCLUSIONS: The effect of smoking on retinopathy in women with type 1 diabetes depends on many variables, which supports the hypothesis of complex interactions between smoking and other variables in the pathogenesis of this disease. Variability of genetic factors involved in signal transduction may affect endothelium proliferation through the regulation of growth factors and through regulation of glycemic levels. Because cigarette smoke influences signal transduction, its impact on diabetic retinopathy may be mediated by ACP1.

[Nanotubes and fullerenes: an overview of the possible environmental and biological impact of bio-nanotechnologies]. / Nanotubi e fullereni: attuali vedute sul possibile impatto ambientale e biologico delle bio-nanotecnologie.

BACKGROUND: Nanotechnology operates in a dimension that is invisible not only to the human eye but also to most highly sensitive instruments; this technology has made it possible to manufacture materials that have not existed in our environment before. In the medical sphere, many important applications in the diagnosis and treatment of diseases are foreseen. Up to now nanotechnology has evaded social, political and regulatory scrutiny concerning the safety of nano-particles in workplaces and in commercial products. OBJECTIVES: The present article reports the most important bio-medical applications of nanotechnology, followed by the results of research on the individual and environmental effects of nanomaterials and in particular of nanotubes, that are considered one of the most fascinating discoveries of the last millennium. METHODS: A report is given on the data presented at the 225th ACS National Meeting (March 23-27, 2003, New Orleans, LA), division of Industrial and Engineering Chemistry. RESULTS: Nanotubes and fullereness are recently discovered different forms of carbon-based materials which are widely applied in various technical fields. One of the main concerns regarding these structures is that they resemble asbestos fibers. CONCLUSIONS: Although preliminary studies suggest that these materials are not associated with any health risk, many researchers highlight the need to assess possible risks of such structures before they become ubiquitous in every aspect of life.