Altered expression of the T cell receptor-CD3 complex in systemic lupus erythematosus

CD3Z polymorphisms and promoter hypermethylation in dermatomyositis - the role of cytosine-phosphate-guanine-related single nucleotide polymorphisms

Background: Decreased expression of the T cell receptor (TCR) ζ-chain has been reported in autoimmune diseases. Recent evidence suggests that this deficiency may be due to polymorphisms in the CD3Z (CD247) gene and/or due to promoter hypermethylation.Methods: Altogether 131 subjects - 36 with dermatomyositis (DM) and 95 healthy controls were genotyped for rs1052230 G > C and rs1052231 T > A polymorphisms using TaqMan assay. The rs840015 G > A polymorphism was analyzed by direct sequencing. The promoter methylation status was analyzed by Sanger sequencing of bisulfite converted DNA.Results: The rs1052230GC genotype and C allele and the rs1052231TA genotype and T allele were found to correlate with photosensitivity as well as the rs1052230C/rs1052231T haplotype. The rs1052231TA genotype was found to be associated with cutaneous disease. The rs840015GG genotype was found increased among patients with DM, leading to increased OR 2.4. On the contrary, the rs840015GA genotype appeared to be protective for the development of DM. From the 11 cytosine-phosphate-guanine (CpG) islands analyzed, only the 8th island showed a difference in its methylation due to the polymorphism rs840015 G > A within this island, as our results suggest. In this way the presence of AA genotype led to no methylation and the presence of the GG genotype was associated with hemimethylation.Conclusion: The CD247 rs1052230 G > C and rs1052231 T > A polymorphisms appeared to have a disease-modifying role. The rs840015GA genotype being associated with reduced methylation has a protective role for the development of dermatomyositis and our results suggest that CpG related single nucleotide polymorphisms may play an important role in autoimmunity.

Expression of membrane-bound human leucocyte antigen-G in systemic sclerosis and systemic lupus erythematosus

Human leucocyte antigen-G (HLA-G) is a nonclassical class I major histocompatibility complex (MHC) molecule characterized by complex immunoregulatory and tolerogenic functions. Membrane-bound HLA-G is expressed on the surface of different cell populations in both physiological and pathological conditions. Systemic sclerosis (SSc) is a multisystem autoimmune disease characterized by widespread tissue fibrosis, vascular lesions and immunological alterations. Systemic lupus erythematosus is the prototypic systemic autoimmune disease affecting virtually any organ system, such as skin, joints, central nervous system, or kidneys. In SSc and SLE patients, the membrane expression of HLA-G on monocytes (0.88 ± 1.54 and 0.43 ± 0.75, respectively), CD4+ (0.42 ± 0.78 and 0.63 ± 0.48, respectively), CD8+ (2.65 ± 3.47 and 1.29 ± 1.34, respectively) and CD4+ CD8+ double-positive cells (13.87 ± 15.97 and 3.79 ± 3.11, respectively) was significantly higher than in healthy controls (0.12 ± 0.07; 0.01 ± 0.01; 0.14 ± 0.20 and 0.32 ± 0.38, respectively) (p < 0.0001). Our results show that in SSc and SLE the membrane expression of HLA-G by different subpopulations of peripheral blood mononuclear cells (PBMC) is increased, suggesting a potential role of HLA-G molecules in the complex immunological pathogenesis of these two autoimmune disorders.

MiR-214 regulates CD3ζ expression in T cells

Introduction

T-cell activation requires the T-cell receptor (TCR)-CD3 complex, which integrates and transduces signals. CD3ζ plays a vital role in TCR signalling by mediating T-cell activation. Abnormal CD3ζ expression is a common characteristic of haematological malignancies with T-cell immune dysfunction or autoimmune diseases. Targeted regulation of CD3ζ expression by either direct or indirect approaches is important for regulating T-cell activation.

Aim of the study

In this study, we focused on identifying miRNAs that may regulate CD3ζ expression.

Material and methods

Three microRNA target search algorithms (TargetScan, PicTar, and microrna.org) were used to identify hypothetical miRNAs that target CD3ζ in T cells. Of the predicted miRNAs, miR-214 was chosen and validated to determine whether miR-214 directly binds to the CD3ζ 3’-UTR and regulates CD3ζ expression by luciferase reporter assays, real-time PCR, and Western blotting.

Results

The results indicate that miR-214 specifically binds the CD3ζ 3’-UTR, and miR-214 mimics remarkably reduce the expression of CD3ζ in MOLT-4 cells.

Conclusions

We identify for the first time that miR-214 targets expression in MOLT-4 cells, suggesting that miR-214 might negatively regulate T-cell activation by targeting CD3ζ.

CD3Z hypermethylation is associated with severe clinical manifestations in systemic lupus erythematosus and reduces CD3ζ-chain expression in T cells

Objective

The importance of hypomethylation in SLE is well recognized; however, the significance of hypermethylation has not been well characterized. We screened hypermethylated marks in SLE and investigated their possible implications.

Methods

DNA methylation marks were screened in SLE whole-blood DNA by microarray, and two marks ( CD3Z and VHL hypermethylations) were confirmed by a methylation single-base extension method in two independent ethnic cohorts consisting of 207 SLE patients and 151 controls. The correlation with clinical manifestations and the genetic influence on those epigenetic marks were analysed.

Results

Two epigenetic marks, CD3Z and VHL hypermethylation, were significantly correlated with SLE: CD3Z hypermethylation (odds ratio = 7.76; P = 1.71 × 10 -13 ) and VHL hypermethylation (odds ratio = 3.77; P = 3.20 × 10 -8 ), and the increased CD3Z methylation was correlated with downregulation of the CD3ζ-chain in SLE T cells. In addition, less genetic influence on CD3Z methylation relative to VHL methylation was found in analyses of longitudinal and twin samples. Furthermore, a higher CD3Z methylation level was significantly correlated with a higher SLE disease activity index and more severe clinical manifestations, such as proteinuria, haemolytic anaemia and thrombocytopenia, whereas VHL hypermethylation was not.

Conclusion

CD3Z hypermethylation is an SLE risk factor that can be modified by environmental factors and is associated with more severe SLE clinical manifestations, which are related to deranged T cell function by downregulating the CD3ζ-chain.

BLyS antagonists and peptide tolerance induction

The major impediment to drug development for systemic lupus erythematosus (SLE) is its heterogeneity. The unpredictable manner in which lupus targets different organs at varying intensity makes the study of new drugs and the optimization of their administration extremely difficult. With the advent of novel, targeted biologic agents for SLE, it can be hoped that more strategic, lupus-relevant immune modulation will lead to safer and more effective treatments. Two alternative new approaches to lupus treatment are reviewed. The first involves selective inhibition of a single protein (BLyS), which may play a central role in host defense and in the pathogenesis of SLE. Although this approach is finely targeted to the inhibition of a single protein which is known to be upregulated in SLE patients, the positioning of BLyS at a critical hub in the immune response suggests that more global adverse repercussions on immunity might still occur. The second strategy is the use of peptides designed to specifically induce tolerance in limited autoreactive immune responses. Immune repercussions might, at least in theory, be almost nonexistent with this kind of approach. Concerns that limited induction of tolerance might have equally limited impact on the complex immune disorder of SLE are not borne out in preliminary murine data. Specific development programs are ongoing using both of these strategies and have recently entered human trials.

Comprehensive analysis of polymorphisms in the HLA-G 5' upstream regulatory and 3' untranslated regions in Brazilian patients with systemic lupus erythematosus

This study aims to comprehensively analyze human leucocyte antigen (HLA)-G polymorphisms association with susceptibility to systemic lupus erythematosus (SLE) development and clinical manifestations. The HLA-G 5' upstream regulatory region (URR), 3' untranslated region (UTR) and a cytosine deletion at exon 3 (ΔC, HLA-G*0105N allele) were analyzed in 114 SLE patients and 128 healthy controls from North East Brazil. The +3003T>C (rs1707) C allele and the HG010101c extended HLA-G allele were significantly more frequent in SLE patients than healthy controls (+3003C allele frequency: 12% in SLE patients vs 6% in controls; odds ratio (OR), 2.10, 95% confidence interval (CI), 1.06-4.28, P = 0.026; HG010101c frequency: 11.8% in SLE patients and 6.3% in controls; OR, 2.14, 95% CI, 1.01-4.51, P = 0.046) and were associated with susceptibility for disease development. Other polymorphisms were associated with different clinical manifestations. Although HLA-G role in SLE disease is far from being elucidated yet, our association study results along with a systematic review and meta-analysis suggest that HLA-G might be able to slightly modulate the complex SLE phenotype (pooled OR, 1.14, 95% CI, 1.02-1.27, P = 0.021).

Association of CD247 polymorphisms with rheumatoid arthritis: a replication study and a meta-analysis

Given the role of CD247 in the response of the T cells, its entailment in autoimmune diseases and in order to better clarify the role of this gene in RA susceptibility, we aimed to analyze CD247 gene variants previously associated with other autoimmune diseases (rs1052237, rs2056626 and rs864537) in a large independent European Caucasian population. However, no evidence of association was found for the analyzed CD247 single-nucleotide polymorphisms (SNPs) with RA and with the presence/absence of anti-cyclic citrullinated polypeptide. We performed a meta-analysis including previously published GWAS data from the rs864537 variant, revealing an overall genome-wide significant association between this CD247 SNP and RA with anti-CCP (OR = 0.90, CI 95% = 0.87-0.93, Poverall = 2.1×10(-10)). Our results show for first time a GWAS-level association between this CD247 polymorphism and RA risk.

Expression and functional role of HLA-G in immune cells from patients with systemic lupus erythematosus

Human leukocyte antigen (HLA)-G is a class I non-classical HLA molecule with an important regulatory role on the immune response. The possible role of this molecule in the pathogenesis of SLE has not been explored. In this work, we evaluated the expression and function of HLA-G in SLE patients. We studied 37 SLE patients as well as 25 healthy donors. Peripheral blood monocytes and in vitro-generated dendritic cells (DCs) were analyzed for HLA-G expression by flow cytometry. We found that monocytes from SLE patients as well as mature CD83+ DCs showed a diminished expression of HLA-G compared with healthy controls. In addition, monocytes from SLE patients showed a diminished induction of HLA-G expression in response to stimulation with IL-10. Furthermore, functional assays showed that these monocytes pre-treated with IFN-γ exhibited a diminished capability to inhibit the proliferation of autologous lymphocytes. Finally, lymphocytes from SLE patients tended to display a lower acquisition of HLA-G (by trogocytosis) from autologous monocytes compared to controls. Our results might have implications for the immune abnormalities observed in patients with SLE.

T cell abnormalities in systemic lupus erythematosus

Because of the consensus that T cells play a central role in the pathogenesis of systemic lupus erythematosus (SLE), we explored the molecular basis of the defective function of SLE T cells for expression of signal transduction molecules, as well as surface structures such as adhesion molecules, by extensively testing peripheral blood T cells from SLE patients. Upregulated expression and function of adhesion molecules was observed in T cells from patients with active SLE who had specific clinical manifestations such as vasculitis, epithelitis and arthritis, but proximal signal transduction was defective. Comprehensive analysis to identify the molecules responsible for the defects showed the expression of the TCR zeta chain was attenuated, or absent in more than half of SLE patients. Moreover, the aberrant transcripts of the TCR zeta chain, including spliced variants lacking exon 7 and with a short 3' UTR, were detected in SLE T cells. Although attenuated expression of the TCR zeta chain is also observed in patients with cancers, infections and other autoimmune diseases, sustained attenuation of TCR zeta expression and aberrant transcripts are only observed in SLE. In this review we discuss the unique features of the TCR zeta defects in SLE.

Type I interferons inhibition of inflammatory T helper cell responses in systemic lupus erythematosus

T helper (Th) cells play a central role in systemic lupus erythematosus (SLE). Activated autoreactive Th cells provide the help required for autoreactive B cells to differentiate and produce pathogenic autoAbs. Both autoAb-containing immune complexes and direct effects of inflammatory Th cells promote tissue injury and organ damage. In SLE, triggering of plasmacytoid dendritic cell (pDC) Toll-like receptors by autoimmune complexes containing nucleic acid autoantigens stimulates pDC secretion of high levels of type I interferons (IFN-alpha/beta). Study of SLE patients and murine disease models implicate these type I IFNs as key disease effectors. However, the role of pDC-derived type I IFNs in regulating the inflammatory function of Th cells in SLE is unknown. Although, type I IFNs are classically considered to promote Th1-mediated inflammation, they can also act as potent inhibitors of both Th1 and Th17 inflammatory cell responses. Work of ourselves and others leads us to hypothesize that if initiated during stages of SLE when Th cell-mediated tissue inflammation is absent or minimal, such as early in the disease or during periods of remission, type I IFN neutralization will disrupt the cycle of systemic autoimmune induction and disease. However, if initiated during advanced stages of disease when there is substantial ongoing Th1 (and possibly Th17) cell-mediated inflammation, targeting type I IFNs will exacerbate the Th cell-mediated inflammatory disease and thus potentiate end-organ damage and destruction. This has important implications for the application of the numerous anti-type I IFN therapies currently under development for SLE treatment.

Analysis of expression and function of the inhibitory receptor ILT2 (CD85j/LILRB1/LIR-1) in peripheral blood mononuclear cells from patients with systemic lupus erythematosus (SLE)

The aim of this work was to study the expression and function of the inhibitory receptor ILT2/CD85j in peripheral blood mononuclear cells (PBMC) from patients with systemic lupus erythematosus (SLE). We studied 23 SLE patients as well as 17 patients with rheumatoid arthritis, 10 with fibromyalgia, and 23 healthy individuals. We found a variable level of expression of ILT2 in the PBMC from both SLE patients and controls, with no significant differences among them. However, when the expression of this receptor was assessed in cell subsets, significantly lower levels were detected in CD19+ lymphocytes from SLE patients compared with healthy controls. Functional assays performed in unfractionated PBMC, showed a significant diminished inhibitory activity of ILT2 in CD4+ and CD8+ cell subsets from SLE patients compared to either rheumatoid arthritis or fibromyalgia patients, and healthy individuals. Our results show that the PBMC from some patients with SLE show a defective expression of ILT2, and that most of them exhibit a poor function of this inhibitory receptor.

Challenges in bringing the bench to bedside in drug development for sle

It is now widely accepted that the current standard of care for systemic lupus erythematosus (SLE) patients is inadequate. There has not been a new medication approved for this disease in thirty years. Attempts to develop and test new drugs have been ongoing since the mid-1990s, but have encountered formidable obstacles. Current models for lupus pathogenesis have provided a theoretical framework for understanding how heterogeneous genetic defects might combine in various ways to increase susceptibility to SLE in different individuals, and could have important implications for new drug development. With the current burst of drug discovery and increased public awareness of SLE, the impetus to overcome these obstacles has never been greater.