Association of PDCD1 polymorphism to systemic lupus erythematosus and rheumatoid arthritis susceptibility

OBJECTIVE

This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p≤0.05.

RESULTS

The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data.

CONCLUSION

There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

Expression of PD-1 Molecule on Regulatory T Lymphocytes in Patients with Insulin-Dependent Diabetes Mellitus

Type 1 diabetes is caused by autoreactive T cells that destroy pancreatic beta cells. Animal models suggested that a CD4⁺CD25⁺ population has a regulatory function capable of preventing activation and effector functions of autoreactive T cells. However, the role of CD4⁺CD25^high T cells in autoimmunity and their molecular mechanisms remain the subject of investigation. We therefore evaluated T regulatory cell frequencies and their PD-1 expression in the peripheral blood of long-standing diabetics under basal conditions and after CD3/CD28 stimulation. Under basal conditions, the percentages of T regulatory cells were significantly higher while that of T effector cells were significantly lower in patients than in controls. The ratio of regulatory to effector T cells was higher in patients than that in controls, suggesting that T regulatory cells were functional in patients. Percentages of total PD-1⁺, PD-1^low and PD-1^high expressing T regulatory cells did not change in patients and in controls. After stimulation, a defect in T regulatory cell proliferation was observed in diabetics and the percentages of total PD-1⁺, PD-1^low and PD-1^high expressing cells were lower in patients. Our data suggest a defective activation of T regulatory cells in long-standing diabetics due to a lower expression of PD-1 on their surface.

Association of genetic polymorphisms in CD8+ T cell inhibitory genes and susceptibility to and progression of chronic HBV infection

BACKGROUND

Previous studies have shown that multiple inhibitory genes play an important role in HBV-specific CD8+ T cell exhaustion and dysfunction in the setting of chronic HBV infection. Polymorphic variants of these genes are thought to be predisposing factors for HBV susceptibility, clearance, and disease progression. The aim of this retrospective study was to identify variants affecting chronic HBV infection in a Chinese Han population.

METHODS

We chose 28 tgSNPs from HapMap data on 5 key genes. They were genotyped on a total of 858 chronic HBV patients, 429 patients who underwent spontaneous recovery, and 239 healthy controls. We evaluated the correlation between the polymorphisms and HBV susceptibility, spontaneous clearance, and disease progression.

RESULTS

The association of rs3827537 of BIM genotype TA and allele A was significantly different (P=0.016, OR=2.049; P=0.031, OR=1.925) between HBV patients and healthy controls. The rs36084323 of PD-1, as well as rs3766377, rs485618, rs4656942 of CD244 showed significant associations with the risk for HBV-related cirrhosis and hepatocellular carcinoma (HCC) (P=0.009, OR=0.482; P=0.009, OR=4.573; P=0.015, OR=0.580; P=0.028, OR=2.855). MDR analysis revealed that the four SNPs (rs36084323, rs3766377, rs485618, rs4656942) modulated the predisposition to cirrhosis and HCC in patients with chronic HBV infection (P=0.006). Using a luciferase reporter assay, we demonstrated that various alleles of rs3766377 had differential effects, and rs3766377 and rs485618 might have interactive effects.

CONCLUSIONS

The present study reveals genetic associations among PD-1 and CD244 variants that may be involved in the development of cirrhosis and HCC in patients with chronic HBV infection. The BIM variant was associated with HBV susceptibility.

Association of PDCD1 polymorphism to Systemic Lupus Erythematosus and Rheumatoid Arthritis susceptibility

OBJECTIVE

This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population.

METHODS

Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg Equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p≤0.05.

RESULTS

The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data.

CONCLUSION

There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

Programmed cell death 1 and Helios distinguish TCR-αβ+ double-negative (CD4-CD8-) T cells that derive from self-reactive CD8 T cells

TCR-αβ(+) double-negative (DN; CD4(-)CD8(-)) T cells represent a poorly understood cellular subset suggested to contribute to the pathogenesis of the autoimmune disease systemic lupus erythematosus. DN T cells have been proposed to derive from CD8(+) cells. However, the conditions that govern the loss of CD8 expression after Ag encounter are unknown. In this study, we tracked the fate of CD8 T cells from transgenic TCR mice exposed to their cognate Ags as self or in the context of infection. We demonstrate that CD8 T cells lose CD8 expression and become DN only when cognate Ag is sensed as self. This process is restricted to tissues where the Ag is present. We also show that DN T cells derived from self-reactive CD8 cells express the inhibitory molecules PD-1 and Helios. These molecules identify a subset of DN T cells in normal mice. A similar population expands when CD8 T cells from repertoires enriched in self-reactive cells (Aire-deficient) are transferred into cognate hosts. Collectively, our data suggest that a subset of DN T cells, identified by the expression of PD-1 and Helios, represent self-reactive cells. Our results provide an explanation for the origin of DN T cells and introduce CD8 loss as a process associated with self-Ag encounter.

T-bet regulates differentiation of forkhead box protein 3+ regulatory T cells in programmed cell death-1-deficient mice

Programmed cell death-1 (PD-1) plays an important role in peripheral T cell tolerance, but whether or not it affects the differentiation of helper T cell subsets remains elusive. Here we describe the importance of PD-1 in the control of T helper type 1 (Th1) cell activation and development of forkhead box protein 3 (FoxP3(+)) regulatory T cells (Tr(egs)). PD-1-deficient T cell-specific T-bet transgenic (P/T) mice showed growth retardation, and the majority died within 10 weeks. P/T mice showed T-bet over-expression, increased interferon (IFN)-γ production by CD4(+) T cells and significantly low FoxP3(+) T(reg) cell percentage. P/T mice developed systemic inflammation, which was probably induced by augmented Th1 response and low FoxP3(+) T(reg) count. The study identified a unique, previously undescribed role for PD-1 in Th1 and T(reg) differentiation, with potential implication in the development of Th1 cell-targeted therapy.

The PD-1/PD-Ls pathway and autoimmune diseases

The programmed death (PD)-1/PD-1 ligands (PD-Ls) pathway, is a new member of the B7/CD28 family, and consists of the PD-1 receptor and its ligands PD-L1 (B7-H1, CD274) and PD-L2 (B7-DC, CD273). Recently, it is reported that PD-1, PD-L1 and PD-L2 also have soluble forms aside from their membrane bound forms. The soluble forms increase the diversity and complexity of PD-1/PD-Ls pathway in both composition and function. The PD-1/PD-Ls pathway is broadly expressed and exerts a wider range of immunoregulatory roles in T-cell activation and tolerance compared with other B7/CD28 family members. Studies show that the PD-1/PD-Ls pathway regulates the induction and maintenance of peripheral tolerance and protects tissues from autoimmune attack in physiological conditions. In addition, it is also involved in various diseases mediated by T cells, such as autoimmunity, tumor immunity, chronic viral infections, and transplantation immunity. In this review, we will summarize the relevance of the soluble forms and the latest researches on the role of PD-1/PD-Ls pathway in autoimmune diseases.

Upregulated PD-1 Expression Is Associated with the Development of Systemic Lupus Erythematosus, but Not the PD-1.1 Allele of the PDCD1 Gene

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease with complicated genetic inheritance. Programmed death 1 (PD-1), a negative T cell regulator to maintain peripheral tolerance, induces negative signals to T cells during interaction with its ligands and is therefore a candidate gene in the development of SLE. In order to examine whether expression levels of PD-1 contribute to the pathogenesis of SLE, 30 patients with SLE and 30 controls were recruited and their PD-1 expression levels in peripheral blood mononuclear cells (PBMCs) were measured via flow cytometry and quantitative real-time-reverse transcription polymerase chain reaction (RT-PCR). Also, whether PD-1 expression levels are associated with the variant of the SNP rs36084323 and the SLE Disease Activity Index (SLEDAI) was studied in this work. The PD-1 expression levels of SLE patients were significantly increased compared with those of the healthy controls. The upregulated PD-1 expression levels in SLE patients were greatly associated with SLEDAI scores. No significant difference was found between PD-1 expression levels and SNP rs36084323. The results suggest that increased expression of PD-1 may correlate with the pathogenesis of SLE, upregulated PD-1 expression may be a biomarker for SLE diagnosis, and PD-1 inhibitor may be useful to SLE treatment.

A Promoter Region Polymorphism in PDCD-1 Gene Is Associated with Risk of Rheumatoid Arthritis in the Han Chinese Population of Southeastern China

Objective. Programmed cell death 1 (PD-1) induces negative signals to T cells during interaction with its ligands and is therefore a candidate gene in the development of autoimmune diseases such as rheumatoid arthritis (RA). Herein, we investigate the association of PDCD-1 polymorphisms with the risk of RA among Chinese patients and healthy controls. Methods. Using the PCR-direct sequencing analysis, 4 PDCD-1 SNPs (rs36084323, rs11568821, rs2227982, and rs2227981) were genotyped in 320 RA patients and 309 matched healthy controls. Expression of PD-1 was determined in peripheral blood lymphocytes by flow cytometry and quantitative real-time reverse transcriptase polymerase chain reaction. Results. We observed that the GG genotype of rs36084323 was associated with a increased risk for developing RA (OR 1.70, 95% 1.11–2.61, P = 0.049). Patients carrying G/G genotype displayed an increased mRNA level of PD-1 (P = 0.04) compared with A/A genotype and healthy controls. Meanwhile, patients homozygous for rs36084323 had induced basal PD-1 expression on activated CD4+ T cells. Conclusion. The PDCD-1 polymorphism rs36084323 was significantly associated with RA risk in Han Chinese population. This SNP, which effectively influenced the expression of PD-1, may be a biomarker of early diagnosis of RA and a suitable indicator of utilizing PD-1 inhibitor for treatment of RA.

Systemic Lupus Erythematosus: Old and New Susceptibility Genes versus Clinical Manifestations

Systemic Lupus Erythematosus (SLE) is one of the most relevant world-wide autoimmune disorders. The formation of autoantibodies and the deposition of antibody-containing immune complexes in blood vessels throughout the body is the main pathogenic mechanism of SLE leading to heterogeneous clinical manifestations and target tissue damage. The complexity of etiology and pathogenesis in SLE, enclosing genetic and environmental factors, apparently is one of the greatest challenges for both researchers and clinicians. Strong indications for a genetic background in SLE come from studies in families as well as in monozygotic and dizygotic twins, discovering several SLE-associated loci and genes (e.g. IRF5, PTPN22, CTLA4, STAT4 and BANK1). As SLE has a complex genetic background, none of these genes is likely to be entirely responsible for triggering autoimmune response in SLE even if they disclosure a potentially novel molecular mechanisms in the pathogenesis' disease. The clinical manifestations and disease severity varies greatly among patients, thus several studies try to associate clinical heterogeneity and prognosis with specific genetic polymorphisms in SLE associated genes. The continue effort to describe new predisposing or modulating genes in SLE is justified by the limited knowledge about the pathogenesis, assorted clinical manifestation and the possible prevention strategies. In this review we describe newly discovered, as well as the most studied genes associated to SLE susceptibility, and relate them to clinical manifestations of the disease.

Increased percentages of PD-1 on CD4+ T cells is associated with higher INF-γ production and altered IL-17 production in patients with systemic lupus erythematosus

OBJECTIVES

Programmed death (PD)-1 is a cell death receptor that, upon stimulation, leads to apoptosis. Previous studies have shown alteration of PD-1 expression on T cells and PD-1 genes in patients with systemic lupus erythematosus (SLE). The aim of this study was to assess the expression of this receptor on effector T cells in patients with SLE.

METHOD

In this study we enrolled 32 SLE patients and 31 healthy controls. T cells from peripheral blood were analysed by flow cytometry for the expression of PD-1. Interferon (IFN)-γ and interleukin (IL)-17-producing cells were investigated for the expression of this co-stimulatory marker.

RESULTS

Percentages of CD4(+) T cells expressing PD-1 were significantly increased in patients with SLE compared to healthy controls. The percentage of PD-1 expression was correlated with the production of INF-γ (r = 0.83, p < 0.0001). We also investigated the production of IL-17 by PD-1(+) CD3(+) T cells. Inactive patients (3.2 ± 1.2% vs. 5.9 ± 3.5%, p = 0.002) and patients without lupus nephritis (LN) (3.2 ± 1.5% vs. 5.9 ± 3.5%, p = 0.005) showed lower levels of IL-17 compared to healthy controls.

CONCLUSION

We have demonstrated increased expression of PD-1 on CD4(+) T cells in SLE patients and an association between PD-1 expression on CD4(+) T cells and IFN-γ expression on CD3(+) T cells. We have also shown that there is an altered subset of PD-1(+) T cells in inactive patients and patients without LN producing lower amounts of IL-17.

From single nucleotide polymorphisms to constant immunosuppression: mesenchymal stem cell therapy for autoimmune diseases

The regenerative abilities and the immunosuppressive properties of mesenchymal stromal cells (MSCs) make them potentially the ideal cellular product of choice for treatment of autoimmune and other immune mediated disorders. Although the usefulness of MSCs for therapeutic applications is in early phases, their potential clinical use remains of great interest. Current clinical evidence of use of MSCs from both autologous and allogeneic sources to treat autoimmune disorders confers conflicting clinical benefit outcomes. These varied results may possibly be due to MSC use across wide range of autoimmune disorders with clinical heterogeneity or due to variability of the cellular product. In the light of recent genome wide association studies (GWAS), linking predisposition of autoimmune diseases to single nucleotide polymorphisms (SNPs) in the susceptible genetic loci, the clinical relevance of MSCs possessing SNPs in the critical effector molecules of immunosuppression is largely undiscussed. It is of further interest in the allogeneic setting, where SNPs in the target pathway of MSC's intervention may also modulate clinical outcome. In the present review, we have discussed the known critical SNPs predisposing to disease susceptibility in various autoimmune diseases and their significance in the immunomodulatory properties of MSCs.

Coexistence of systemic lupus erythematosus and multiple sclerosis: prevalence, clinical characteristics, and natural history

OBJECTIVES

The coexistence of systemic lupus erythematosus (SLE) and multiple sclerosis (MS) in the same individual has rarely been described. Our objective was to report on the prevalence, clinical characteristics, and prognosis of cases fulfilling the criteria for both SLE and MS.

METHODS

We utilized existing patient cohorts from the Departments of Rheumatology and Neurology, University of Crete, and screened patients diagnosed with either SLE (n = 728) or MS (n = 819) for features of both diseases. The clinical, laboratory, and neuroimaging findings were assessed.

RESULTS

We identified nine patients who fulfilled the diagnostic criteria for both SLE and MS, corresponding to a prevalence rate of 1.0-1.2% in each cohort. All patients were women, with an average age at SLE diagnosis of 42.1 years (range: 34-56 years). The diagnosis of SLE preceded the development of MS in five patients, with a time lag ≤ 5 years in four of them. Initial presentation of MS included spinal symptoms in seven patients. All patients had features of mild SLE with predominantly cutaneous, mucosal, and musculoskeletal manifestations. Accordingly, therapeutic decisions were mainly guided by the severity of the neurological syndrome. During the median follow-up of 4 years (range: 1-10 years), three patients remained stable and the remaining experienced gradual deterioration in their neurological status. SLE remained quiescent in all patients while on standard immunomodulatory MS therapy.

CONCLUSIONS

Occurrence of both diseases in the same individual is rare, corroborating data that suggest distinct molecular signatures. SLE and MS coexistence was not associated with a severe phenotype for either entity.

Recent insights into the role of the PD-1/PD-L1 pathway in immunological tolerance and 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 disorders. The relevance of T regulatory cells and of the PD-1/PD-L1 pathway in controlling immune responses has been highlighted. Recent studies have in particular elucidated the putative role of the PD-1/PD-L1 pathway in regulating T cell responses and its effects on immunological tolerance and immune-mediated tissue damage. The role of the PD-1/PD-L1 pathway in autoimmunity has been already investigated in vivo in several experimental animal models including insulin-dependent diabetes mellitus, systemic lupus erythematosus, myocarditis, encephalomyelitis, rheumatoid arthritis and inflammatory bowel diseases. With the advent of candidate gene and genome-wide association studies, single nucleotide polymorphisms (SNPs) in PD-1 gene in humans have demonstrated relevant associations with a higher risk of developing autoimmune diseases in certain ethnic groups. In this review we present recent insights into the role of the PD-1/PD-L1 pathway in regulating lymphocyte activation, promotion of T regulatory cell development and function, breakdown of tolerance and development of autoimmunity. We finally speculate on the possible development of novel therapeutic treatments in human autoimmunity by modulating the PD-1/PD-L1 pathway.

Genetic variations of PD1 and TIM3 are differentially and interactively associated with the development of cirrhosis and HCC in patients with chronic HBV infection

Cooperation or interaction of programmed cell death-1 (PD-1) and T cell immunoglobulin and mucin domain-containing molecule-3 (Tim-3) molecules is more relevant than either molecule alone to immune dysfunction in chronic viral infection and cancers. This study simultaneously investigated polymorphisms at PD1 +8669 and TIM3 -1516 loci in 845 hepatitis B virus (HBV) chronically infected patients [151 asymptomatic carriers, 202 chronic hepatitis, 221 cirrhosis and 271 hepatocellular carcinoma (HCC)], 141 HBV infection resolvers and 318 healthy controls. Multivariate analysis showed that, in addition to gender, age, ALT, albumin and HBV DNA, PD1 +8669 genotype AA was associated with cirrhosis compared with patients without cirrhosis (OR, 2.410; P=0.001). TIM3 -1516 genotypes GT+TT, together with gender, age, ALT, AST, direct bilirubin, albumin and HBeAg status, were associated with HCC compared with cirrhosis patients without HCC (OR, 2.142; P=0.011). The combined carriage of PD1 +8669 AA/TIM3 -1516 GT or TT was higher in cirrhosis and HCC pooled patients than in patients without cirrhosis (OR, 2.326; P=0.020) and in HCC patients than in cirrhosis patients (OR, 2.232; P=0.013). These data suggest that PD1 and TIM3 polymorphisms may differentially and interactively predispose cirrhosis and HCC in chronic HBV infection.

Aberrant expression of the negative costimulator PD-1 on T cells in granulomatosis with polyangiitis

OBJECTIVE

Persistent T-cell activation is frequently observed in granulomatosis with polyangiitis (GPA, formerly known as Wegener's granulomatosis). T-cell activation is usually balanced by negative costimulatory molecules. The negative costimulator programmed death receptor-1 (PD-1) and its relevance to T-cell immunity have not been studied so far in GPA. Thus it is the aim of the study to characterize the role of PD-1 in GPA.

METHODS

Thirty-two patients suffering from GPA and 19 age-matched healthy controls (HCs) were enrolled. T-lymphocyte subsets from peripheral blood were analysed by flow cytometry for the expression of PD-1. The frequency of memory T cells and T cells producing pro-inflammatory cytokines was determined. Renal biopsies from GPA patients were stained for CD3 and PD-1.

RESULTS

PD-1 expression was increased on T-helper cells (Th cells) from GPA patients as compared with HCs. In addition, parameters of persistent T-cell activation and production of pro-inflammatory cytokines were positively associated with numbers of PD-1(+) Th cells in patients but not in HCs. Latent infection with CMV seemed to enhance PD-1 expression on CD4(+) and CD4(+)CD25(-) T cells. Interestingly, expression of PD-1 on CD4(+)CD25(+)T cells was inversely correlated with relapse rate. Importantly, lesional T cells were mostly lacking PD-1.

CONCLUSIONS

The expression of the negative costimulator PD-1 is altered in GPA and might counterbalance persistent T-cell activation.

TNF-α and TGF-β counter-regulate PD-L1 expression on monocytes in systemic lupus erythematosus

Monocytes in patients with systemic lupus erythematosus (SLE) are hyperstimulatory for T lymphocytes. We previously found that the normal program for expression of a negative costimulatory molecule programmed death ligand-1 (PD-L1) is defective in SLE patients with active disease. Here, we investigated the mechanism for PD-L1 dysregulation on lupus monocytes. We found that PD-L1 expression on cultured SLE monocytes correlated with TNF-α expression. Exogenous TNF-α restored PD-L1 expression on lupus monocytes. Conversely, TGF-β inversely correlated with PD-L1 in SLE and suppressed expression of PD-L1 on healthy monocytes. Therefore, PD-L1 expression in monocytes is regulated by opposing actions of TNF-α and TGF-β. As PD-L1 functions to fine tune lymphocyte activation, dysregulation of cytokines resulting in reduced expression could lead to loss of peripheral T cell tolerance.

The negative costimulatory molecule PD-1 modulates the balance between immunity and tolerance via miR-21

Disruption of the programmed death-1 (PD-1) pathway leads to breakdown of peripheral tolerance and initiation of autoimmunity. The molecular pathways that mediate this effect remain largely unknown. We report here that PD-1 knockout (PD-1(-/-) ) mice develop more severe and sustained Ag-induced arthritis (AIA) than WT animals, which is associated with increased T-cell proliferation and elevated levels of IFN-γ and IL-17 secretion. MicroRNA analysis of Ag-specific CD4(+) T cells revealed a significant upregulation of microRNA 21 (miR-21) in PD-1(-/-) T cells compared with WT controls. In addition, PD-1 inhibition, via siRNA, upregulated miR-21 expression and enhanced STAT5 binding in the miR-21 promoter area. Computational analysis confirmed that miR-21 targets directly the expression of programmed cell death 4 (PDCD4) and overexpression of miR-21 in cells harboring the 3'UTR of PDCD4 resulted in reduced transcription and PDCD4 protein expression. Importantly, in vitro delivery of antisense-miR-21 suppressed the Ag-specific proliferation and cytokine secretion by PD-1(-/-) T cells, whereas adoptive transfer of Ag-specific T cells, overexpressing miR-21, induced severe AIA. Collectively, our data demonstrate that breakdown of tolerance in PD-1(-/-) mice activates a signaling cascade mediated by STAT5, miR-21, and PDCD4 and establish their role in maintaining the balance between immune activation and tolerance.

Reproductive immunology: current status and future directions (part I)

Extensive research work over the past couple of decades has indicated a series of intricate relations between immune and reproductive systems. A range of reproductive immunology topics including the roles of adoptive and innate immunity in infertility and pregnancy, the immune system's role in induction of labor and preterm delivery, and immuno-modulatory effects of the female sex hormones will be discussed in this and the next issue of the Journal. The implications of this research on the development of novel therapeutic approaches are also addressed.

A functional polymorphism in B and T lymphocyte attenuator is associated with susceptibility to rheumatoid arthritis

Inhibitory coreceptors are thought to play important roles in maintaining immunological homeostasis, and a defect in the negative signals from inhibitory coreceptors may lead to the development of autoimmune diseases. We have recently identified B and T lymphocyte attenuator (BTLA), a new inhibitory coreceptor expressed on immune cells, and we suggest that BTLA may be involved in the development of autoimmune diseases using BTLA-deficient mice. However, the role of BTLA in the pathogenesis of autoimmune diseases in humans remains unknown. We, therefore, examined the possible association between BTLA and rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and Sjögren's syndrome (SS) by conducting a case-control genetic association study. We found that 590C single-nucleotide polymorphism (SNP) of BTLA gene was significantly associated with susceptibility to RA, but not to SLE or SS. Furthermore, RA patients bearing this 590C SNP developed the disease significantly earlier than the patients without this allele. We also found that BTLA with 590C allele lacked the inhibitory activity on concanavalin A- and anti-CD3 Ab-induced IL-2 production in Jurkat T cells. These results suggest that BTLA is an RA-susceptibility gene and is involved in the protection from autoimmunity in humans.

Program death 1 (PD1) haplotyping in patients with breast carcinoma

Located on chromosome 2q37.3, the programmed death 1 (PD1) gene encodes for PD-1 (also known as CD279), a negative co-stimulator in the immune system. PD-1 renders potent inhibitory effects on T and B lymphocytes as well as monocyte responses. Expression of PD-1 ligands by tumor cells has been reported to contribute in immune system evasion. We aimed, in current study, to investigate the association of two single nucleotide polymorphisms in PD1 gene, +7146 G to A (PD-1.3) and +7785 C to T (PD-1.5 or +872), with susceptibility and/or progression of breast carcinoma. Four hundred forty-three women with breast cancer and 328 age-sex match healthy donors were recruited in present study. Genotyping was performed using Nested polymerase chain reaction-restriction fragment length polymorphisms. Arlequin software package was used to check for the Hardy-Weinberg equilibration and to determine the haplotypes. Results revealed no significant differences in the frequencies of genotypes and alleles at PD-1.3 (P=0.252 and 0.279 for genotypes and alleles, respectively) and PD-1.5 positions (P=0.522 and 0.278 for genotypes and alleles, respectively). Four haplotypes were observed among populations with no differences in the frequency between patients and controls. Our results also revealed no association between PD1 genotypes and tumor stage, tumor size, tumor grade, lymph node involvement, vascular invasion, distant metastasis, and Nottingham prognostic index. Present data do not confirm association of PD-1.3 (+7146) G/A and PD-1.5 (+7785 or +872) C/T genetic markers with susceptibility of Iranians to breast cancer.

What's new in paediatric SLE?

Although more commonly presenting in adulthood, approximately 15-20% of systemic lupus erythematosus (SLE) cases occur before age 16 years. Unfortunately, SLE is usually more severe when presenting in childhood, and frequently involves vital organs such as the kidney. Over the past several decades, mortality rates have dropped, largely due to earlier diagnosis, improved management of the SLE and improved general medical care to reduce infection. Treatment strategies for nephritis in children is largely adopted from experience in adults, and the recent advances in therapeutic options for adults have brought new treatment to children. However, determining efficacy is difficult due to the absence of clinical trial data. Furthermore, determination of safety in a developing child or adolescent cannot be extrapolated from adult studies. As survival has improved, numerous secondary complications have emerged, including early atherosclerosis. As for adults with SLE, it is generally accepted that atherogenesis in SLE results from both disease- and treatment-related factors. Most surprising is that persons with childhood-onset SLE can develop myocardial ischaemia as early as 20-30 years of age. Better understanding of the pathogenesis and development of preventative strategies is needed to ensure that these young people do not succumb to atherosclerosis instead of to SLE.

Role of PD-1 in regulating T-cell immunity

Programmed cell death-1 (PD-1) is a member of the CD28 superfamily that delivers negative signals upon interaction with its two ligands, PD-L1 or PD-L2. PD-1 and its ligands are broadly expressed and exert a wider range of immunoregulatory roles in T cells activation and tolerance compared with other CD28 members. Subsequent studies show that PD-1-PD-L interaction regulates the induction and maintenance of peripheral tolerance and protect tissues from autoimmune attack. PD-1 and its ligands are also involved in attenuating infectious immunity and tumor immunity, and facilitating chronic infection and tumor progression. The biological significance of PD-1 and its ligand suggests the therapeutic potential of manipulation of PD-1 pathway against various human diseases. In this review, we summarize our current understanding of PD-1 and its ligands ranging from discovery to clinical significance.

Apoptotic signaling activated by modulation of the F0F1-ATPase: implications for selective killing of autoimmune lymphocytes

7-Chloro-5-(4-hydroxyphenyl)-1-methyl-3-(napthalen-2-ylmetyl)-4,5,-dihydro-1H-benzo[b][1,4]diazepin-2(3H)-one (Bz-423) is a proapoptotic 1,4-benzodiazepine that potently suppresses disease in the murine model of lupus by selectively killing pathogenic lymphocytes. In MRL/MpJ-Fas(lpr) (MRL-lpr) mice, Bz-423 overcomes deficient expression of the Fas death receptor and hyperactivation of antiapoptotic phosphatidylinositol 3-kinase (PI3K)-Akt signaling to specifically kill pathogenic CD4(+) T cells. Bz-423 binds to the oligomycin-sensitivity-conferring protein component of the mitochondrial F(0)F(1)-ATPase, which modulates the enzyme leading to formation of superoxide by the mitochondrial respiratory chain. Scavenging this reactive oxygen species blocks all subsequent components of the apoptotic cascade. To gain insight into how apoptotic signaling activated by Bz-423-induced superoxide contributes to the selective depletion of MRL-lpr CD4(+) T cells, we characterized the death mechanism in a CD4(+) T cell leukemia line (Jurkat). Although Bz-423-induced superoxide indirectly inactivates Akt, this response is not required for T cell death. Apoptosis instead results from parallel increases in levels of the proapoptotic Bcl-2 proteins Noxa and Bak leading to specific activation of Bak, mitochondrial outer membrane permeabilization, and a commitment to apoptosis. By directly up-regulating proteins that trigger loss of mitochondrial outer membrane integrity, Bz-423 bypasses defective Fas function and antiapoptotic PI3K-Akt signaling in MRL-lpr CD4(+) T cells. Moreover, because disease-associated abnormalities should sensitize autoreactive CD4(+) T cells to transcriptional up-regulation of Noxa by redox signals and to Bak-dependent apoptosis, the apoptotic mechanism elucidated in Jurkat cells provides important clues into the cell-type- and disease-selective effects of Bz-423 in MRL-lpr mice.