Association of CTLA-4 but not CD28 gene polymorphisms with systemic lupus erythematosus in the Japanese population

Genetic interrogation for sequence and copy number variants in systemic lupus erythematosus

Early-onset systemic lupus erythematosus presents with a more severe disease and is associated with a greater genetic burden, especially in patients from Black, Asian or Hispanic ancestries. Next-generation sequencing techniques, notably whole exome sequencing, have been extensively used in genomic interrogation studies to identify causal disease variants that are increasingly implicated in the development of autoimmunity. This Review discusses the known casual variants of polygenic and monogenic systemic lupus erythematosus and its implications under certain genetic disparities while suggesting an age-based sequencing strategy to aid in clinical diagnostics and patient management for improved patient care.

Immune Checkpoint Inhibitors and Lupus Erythematosus

Immune checkpoint inhibitors (ICIs) are the standard of care for a growing number of malignancies. Unfortunately, they are associated with a broad range of unique toxicities that mimic the presentations of primary autoimmune conditions. These adverse events are termed immune-related adverse events (irAEs), of which ICI-lupus erythematosus (ICI-LE) constitutes a small percentage. Our review aims to describe the available literature on ICI-LE and ICI treatment for patients with pre-existing lupus. Most diagnoses of ICI-LE had findings of only cutaneous lupus; four diagnoses of ICI-LE had systemic lupus manifestations. Over 90% (27 of 29) of cases received anti-PD-1/PDL-1 monotherapy, 1 received combination therapy, and 1 received only anti-CTLA-4 treatment. About three-fourths (22 of 29 or 76%) of patients with ICI-lupus were managed with topical steroids, 13 (45%) received hydroxychloroquine, and 10 (34%) required oral corticosteroids. In our case series, none of the patients with pre-existing lupus receiving ICI therapy for cancer had a flare of their lupus, but few had de novo irAE manifestations, all of which were characterized as low-grade. The review of the literature yielded seven ICI-LE flares from a total of 27 patients with pre-existing lupus who received ICI. Most flares were manageable without need for ICI cessation.

Current understanding of CTLA-4: from mechanism to autoimmune diseases

Autoimmune diseases (ADs) are characterized by the production of autoreactive lymphocytes, immune responses to self-antigens, and inflammation in related tissues and organs. Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is majorly expressed in activated T cells and works as a critical regulator in the inflammatory response. In this review, we first describe the structure, expression, and how the signaling pathways of CTLA-4 participate in reducing effector T-cell activity and enhancing the immunomodulatory ability of regulatory T (Treg) cells to reduce immune response, maintain immune homeostasis, and maintain autoimmune silence. We then focused on the correlation between CTLA-4 and different ADs and how this molecule regulates the immune activity of the diseases and inhibits the onset, progression, and pathology of various ADs. Finally, we summarized the current progress of CTLA-4 as a therapeutic target for various ADs.

Cytotoxic T-lymphocyte associated protein 4 (CTLA4) polymorphisms are linked to systemic lupus erythematosus: an updated meta-analysis

Cytotoxic T-lymphocyte associated protein 4 (CTLA-4) molecule controls T cell immune response. Functional single nucleotide polymorphisms (SNPs) in the CTLA-4 gene have been associated with several autoimmune diseases, including systemic lupus erythematosus (SLE).  However, the genetic association of the CTLA-4 variants with vulnerability to SLE remained contradictory. We have conducted a current meta-analysis by combining the findings of prior published articles in order to make a conclusive statement. Various literature databases were screened with appropriate keywords to obtain relevant articles, and eligible reports were obtained using well-defined inclusion and exclusion criteria. Meta-analysis was performed by Comprehensive Meta-analysis V 3.3, and various statistical parameters such as odds ratio, 95% confidence interval, and probability values were computed. A total of 3847 SLE patients and 5278 healthy controls were considered in the present meta-analysis from 26 individual reports. A significant association of CTLA-4 +49 A/G (G vs. A: p=0.03, OR=1.47) and -1722 T/C (p=0.02, OR=0.87) polymorphisms were observed with susceptibility and resistance against the development of SLE, respectively. However, the other two SNPs in the CTLA-4 gene (-318 C/T and -1661 A/G) failed to establish a connection. Interestingly, subgroup analysis revealed an association of CTLA-4 +49 A/G with a predisposition to SLE only in the Asian population (G vs. A: p=0.04, OR=1.26, GG vs. AA: p=0.02, OR=1.84, AG vs AA: p=0.01, OR=1.44, GG+AG vs AA: p=0.01, OR=1.52) and not in Caucasians. The current meta-analysis suggests a significant CTLA-4 +49 A/G variant association with susceptibility to SLE development in overall and Asian populations. In contrast, the other variant, -1722 T/C, is linked with protection against SLE. However, further case-control studies in diverse ethnic populations are requisite.

Clinical and diagnostic potential of regulatory T cell markers: From bench to bedside

Regulatory T (Treg) cells are heterogeneous immune cell populations residing in the thymus and peripheral lymphatic tissues. This immune cell plays a central and critical role in maintaining immune tolerance against undesirable immune responses. Treg cells' phenotypic heterogeneity caused by different pathological conditions makes their identification and differentiation from non-suppressive T cells difficult. On the other hand, using nonspecific markers and variable isolation panels leads to undesirable outcomes. There are a variety of markers to identify functional Treg cells, including CD25, FOXP3, and CTLA-4, as well as the epigenetic signature of forkhead box P3 (FOXP3), which can be used for both natural and induced Treg cells. Phenotypic heterogeneity is a major concern in Treg purification when using nonspecific markers, which can be addressed by utilizing suitable isolation panels designed for different purposes. This review presents a clinical framework for Treg detection and isolation, focusing on Treg markers such as CD25, FOXP3, CTLA-4, CD127, GPA-33, and TSDR demethylation to design Treg isolation panels suitable for different Treg therapy purposes. The current review also highlights new reliable Treg markers applicable for different purposes.

CTLA-4 polymorphisms in Thai patients with rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis

AIMS

Studies on polymorphisms of the cytotoxic T lymphocytes associated antigen-4 (CTLA-4) genes in rheumatic disease patients are limited in Southeast Asia. This pilot study aimed to determine CTLA-4 polymorphisms in Thai patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SSc), and correlate them with serology.

METHOD

One-hundred RA, 70 SLE and 50 SSc patients, and 99 healthy controls (HCs) were included in this study. Polymorphisms of the CTLA-4 gene at +49A/G, -318C/T, -1661A/G and -1722T/C loci were determined by polymerase chain reaction restriction fragment length polymorphism methods. Patient serum samples were determined as follows: RA (rheumatoid factor [RF] and anticyclic citrullinated peptide [anti-CCP]), SLE (antinuclear antibodies [ANA], anti-double-stranded DNA [anti-dsDNA], anti-Smith [anti-Sm], anti-ribonucleoprotein [anti-RNP], and anti-Sjögren's syndrome antigen A [SSA]), and SSc (ANA, anti-RNP, anti-SSA, anti-topoisomerase-1 [anti-Scl70], and anti-centromere antibodies [ACA]).

RESULTS

Among the 4 loci studied (+49A/G, -318C/T, -1661A/G and -1722T/C) only the A allele frequency at the +49A/G was significantly higher in the RA patients than their HCs (47.25% vs 35.86%, P = .029, odds ratio [OR] 1.60; 95% CI 1.04-2.47). It also was significantly higher in the subgroup of RA patients with positive RF and anti-CCP than their HCs (47.50% vs 35.86%, P = .020, OR 1.62; 95% CI 1.06-2.47 and 48.89% vs 35.86%, P = .012, OR 1.71; 95% CI 1.11-2.64, respectively). No polymorphisms at these 4 loci were observed in SLE or SSc patients.

CONCLUSION

The A allele at +49A/G locus of the CTLA-4 gene was associated with RA in Thais.

Cytotoxic T Lymphocyte Antigen 4 Gene +49 A/G (rs231775) Polymorphism and Susceptibility to Systemic Lupus Erythematosus

AIM

To assess the probable role of +49AG polymorphism in susceptibility to SLE in an Egyptian population.

BACKGROUND

Systemic lupus erythematosus (SLE) is a compound inflammatory chronic disease distinguished through the release of autoantibodies. Cytotoxic T lymphocyte associated antigen-4 is a main down controller of T-cell response; its dysregulation could affect SLE pathogenesis by altered T cells activation to self-antigens.

OBJECTIVES

To evaluate the CTLA-4 +49AG allelic and genotype frequency in a sample of the Egyptian population and correlate them with disease susceptibility and clinical severity.

MATERIALS AND METHODS

Including 100 patients with SLE and 100 healthy controls (age and gender matched), CTLA-4 exon 1 49 A>G Genotyping was done using Real-Time PCR.

RESULTS

No difference was noticed in genotype or allele distributions of the studied polymorphism between both groups. Similar genotypes and allele frequencies were established for the 2 groups after their stratification by the age of disease onset, clinical course, or severity.

CONCLUSION

CTLA-4 +49AG gene polymorphism is not linked with the liability to develop SLE in the studied Egyptian population. Yet it is significantly related to disease severity.

Association of CTLA-4 (+49 A/G) polymorphism with susceptibility to autoimmune diseases: A meta-analysis with trial sequential analysis

OBJECTIVES

In recent years, more and more studies have been focusing on the association between Cytotoxic T lymphocyte antigen-4 (CTLA-4) (+49 A/G) gene polymorphism and autoimmune diseases. However, the results of previous studies are still controversial. The meta-analysis is aiming at determining the association in CTLA-4 (+49 A/G) gene rs231775 polymorphism and ankylosing spondylitis (AS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE).

METHODS

We searched PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Chinese Biomedical Database (CBM) up to November 2020, use random or fixed-effect models to perform meta-analysis to compare alleles and other genetic models, including homozygous, heterozygous, recessive and dominant models. The odds ratio (OR) with a 95% confidence interval (95% CI) was used to assess the correlation between CTLA-4 (+49 A/G) gene polymorphism and the genetic affectability of AS, RA, and SLE. Meanwhile, we used sequential trial analysis (TSA) to analyze the reliability of the results. Finally, we searched the relevant data of genome-wide association studies (GWAS) to further verify the accuracy of the experimental results.

RESULTS

47 studies with 11,893 cases and 12,032 healthy controls were included. The rs231775 G allele was relevant to high risk of autoimmune disease over all people (P < 0.05). The G allele of rs231775 was significantly related to RA susceptibility (P < 0.05), but not with AS or SLE. Subgroup analysis by ethnicity indicated that rs231775 G allele was closely related to RA in Caucasian populations and Mongolian populations (P < 0.05). A strong connection within rs231775 G allele and AS affectability was uncovered in Caucasian populations (P < 0.05). The analysis of the TSA shows that the meta-analysis can draw the conclusion.

CONCLUSION

CTLA-4 (+49 A/G) gene rs231775 G allele increases the risk of autoimmune diseases in Caucasian populations. And it also increases the risk of RA in Caucasian and Mongolian populations. More sample size and more elaborately designed studies are needed to elucidate the relationship in CTLA-4 (+49 A/G) gene rs231775 G allele and autoimmune diseases, especially AS, SLE.

Extracellular Vesicles and Immune System in Ageing and Immune Diseases

Immune system is essential for host homeostasis. Immune cells communicate with each other by binding to receptors or by releasing vesicles including chemokines and cytokines. Under healthy circumstances, immune cell-derived factors are critical for cellular growth, division and function, whereas under conditions such as ageing and inflammatory states, they can aggravate pathologies and cause disease. Cell-derived membranous extracellular vesicles mediate cell-to-cell communication and are implicated in various physiological and pathological processes involving ageing and age-related diseases. Extracellular vesicles are responsible for spreading detrimental factors to the surroundings and the propagation phase of inflammatory diseases. The regulation of extracellular vesicles is a putative target for treatment of inflammatory diseases. Moreover, their features are ideal for developing biomarkers and drug delivery systems modulated by bioengineering in inflammatory diseases. The present review summarizes the current understanding of extracellular vesicles in ageing and inflammatory diseases.

Association of AIRE (rs2075876), but not CTLA4 (rs231775) polymorphisms with systemic lupus erythematosus

BACKGROUND

The AIRE (rs2075876) and CTLA4 (rs231775) variants have a crucial function in controlling the negative selection and suppression of T lymphocytes. Numerous reports studied the association of AIRE and CTLA4 variants with different autoimmune disorders, but with inconclusive conclusions. The main purpose of this work is to evaluate the association of these two variants with SLE susceptibility among Egyptian patients.

SUBJECTS AND METHODS

A total of 247 participants (100 SLE patients and 147 healthy controls) were enrolled in this case-controlled study. The genomic DNA of these dual variants was genotyped using the TaqMan genotyping method.

RESULTS

The AIRE (rs2075876) variant conferred protection against developing SLE disease under allelic [A allele vs. G allele; OR = 0.16, 95%CI = 0.09-0.28], and dominant [GA + AA vs. GG; OR = 0.14, 95%CI = 0.05-0.34] models. Moreover, patients with AIRE rs2075876 (A/A) genotype revealed a statistically significant with lower levels of complement 3 (p-value = 0.007). Nonetheless, the CTLA4 (rs231775) variant was not associated with increased risk of SLE under all genetic association models (p-value > 0.05). However, CTLA4 rs231775 (G/G) genotype observed significant difference with recurrent infection and hematuria.

CONCLUSIONS

Our findings indicated that the AIRE (rs2075876) variant conferred protection against developing SLE disease, but not the CTLA4 (rs231775) variant.

Novel human immunomodulatory T cell receptors and their double-edged potential in autoimmunity, cardiovascular disease and cancer

In the last decade, approaches based on T cells and their immunomodulatory receptors have emerged as a solid improvement in treatments for various types of cancer. However, the roles of these molecules in the therapeutic context of autoimmune and cardiovascular diseases are still relatively unexplored. Here, we review the best known and most commonly used immunomodulatory T cell receptors in clinical practice (PD-1 and CTLA-4), along with the rest of the receptors with known functions in animal models, which have great potential as modulators in human pathologies in the medium term. Among these other receptors is the receptor CD69, which has recently been described to be expressed in mouse and human T cells in autoimmune and cardiovascular diseases and cancer. However, inhibition of these receptors individually or in combination by drugs or monoclonal antibodies generates a loss of immunological tolerance and can trigger multiple autoimmune disorders in different organs and immune-related adverse effects. In the coming decades, knowledge on the functions of different immunomodulatory receptors will be pivotal for the development of new and better therapies with less harmful side effects. In this review, we discuss the roles of these receptors in the control of immunity from a perspective focused on therapeutic potential in not only cancer but also autoimmune diseases, such as systemic lupus erythematosus, autoimmune diabetes and rheumatoid arthritis, and cardiovascular diseases, such as atherosclerosis, acute myocardial infarction, and myocarditis.

Chromosome 2q33genetic polymorphisms in Tunisian endemic pemphigus foliaceus

Background

Several studies have suggested that polymorphisms within genes encoding T‐lymphocyte immune regulating molecules: CD28, CTLA‐4, and ICOS, may alter the signaling process and subsequently could be involved in susceptibility to a broad spectrum of autoimmune diseases.

Methods

This study aimed to replicate associations between common polymorphisms in the 2q33.2 cluster and susceptibility to pemphigus foliaceus (PF) in the Tunisian population. We investigated seven polymorphisms: rs3116496 and rs1879877 (CD28), rs231775, rs3087243, and (AT)_n repeat (CTLA4); rs11889031 and rs10932029 (ICOS) in a case–control study which enrolled 106 Tunisian PF patients and 205 matched healthy controls.

Results

We confirmed the associations with CTLA4((AT)₁₃, p = 0.00137, OR = 3.96 and (AT)₂₀, p = 0.008, OR = 5.22; respectively) and ICOS genes (rs10932029>CT, p = 0.034, OR = 2.12 and rs10932029>TT, p = 0.04 and OR = 0.41).

Conclusion

Our results indicate that susceptibility to PF is located in the proximal and the distal 3′ flanking region of the CTLA4/ICOS promoter. These findings may open avenues to the treatment of patients with biological drugs targeting CTLA4/ICOS molecules, in a personalized manner to achieve more effective treatment.

Serum/plasma homocysteine levels in patients with systemic lupus erythematosus: a systematic review and meta-analysis

Published studies have shown contradictory results in the association of serum/plasma levels of homocysteine (HCY) with systemic lupus erythematosus (SLE). This study is to systematically evaluate the association of serum/plasma HCY levels in SLE. A search was done using PubMed, Embase, Web of Science, and ScienceDirect databases up to 7 April 2019. Thirty-six articles including 2919 SLE patients and 3120 healthy controls were finally included in this meta-analysis. The HCY levels were significantly higher in SLE patients than in healthy controls (P < 0.001). The subgroup analysis revealed that Asian, African, Arab, Mixed, White and others as well as ages (< 35 and ≥ 35) had significant higher HCY levels in SLE patients than in the healthy controls. The study indicated that patients with disease activity index scores < 8 (P < 0.001) and ≥ 8 (P = 0.003) of SLE had significant higher HCY levels as compared with the healthy controls. It was also revealed that disease duration in SLE patients for < 10 and ≥ 10 years (P < 0.001) had significant higher HCY levels as compared with the healthy controls. A significant higher HCY level for body mass index (< 23 and ≥ 23) was found as well as measurement type in SLE patients than healthy controls. This meta-analysis demonstrated higher HCY levels in patients with SLE than healthy controls, suggesting a possible role of HCY in the disease.Key Points• Homocysteine (HCY) is closely related to the mechanisms of systemic lupus erythematosus (SLE).• This study reveals a significant correlation between HCY levels and the various indexes of disease activity.• This study reveals that medication may influence HCY levels in SLE.• This study also discovers that the subgroup analysis of all the factors influences the HCY levels in SLE patients.

Vitamin D Increases CTLA-4 Gene Expression in Patients with Mild to Moderate Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disorder of the large intestine. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a member of the immunoglobulin superfamily, which binds B7-1 and B7-2 on APCs (antigen-presenting cells), and induces APCs to produce an inhibitory signal to T cells. The aim of this study was to investigate the effect of vitamin D on CTLA-4 gene expression in whole blood samples of patients with UC.

METHODS

90 patients with mild to moderate UC were randomized to receive either a single injection of 7.5 mg vitamin D3 or 1 mL normal saline. 90 days following the intervention fold changes in CTLA-4 mRNA expression were determined and statistical comparisons between the two groups were performed.

RESULTS

Serum vitamin D increased significantly only in the vitamin D group. CTLA-4 fold changes were significantly higher in the vitamin D group compared with the placebo group (median ± IQR: 1.21 ± 2.3 vs. 1.00 ± 1.5, respectively; p = 0.007).

CONCLUSION

The results of this study revealed that vitamin D administration in patients with UC enhances the CTLA-4 gene expression.

Polymorphisms in the cytotoxic T lymphocyte-associated protein-4 immune regulatory gene and their impact on inhibitor development in patients with hemophilia A

Objective

The development of inhibitors against infused factor VIII represents the most severe complication of substitution therapy in hemophilia A (HA) patients. Data on risk factors for inhibitor formation in Iraqi Kurdish patients with HA are unavailable. This study aimed to evaluate the impact of two single nucleotide polymorphisms (SNPs) in an immune regulatory gene in the emergence of inhibitors.

Methods

We focused on 126 patients with either severe or mild/moderate HA presenting with and without inhibitors. We analyzed the frequency of two polymorphisms in the cytotoxic T lymphocyte-associated protein-4 gene (CTLA-4; CTLA-4-318C > T and CTLA-4 + 49A > G). Genotyping was performed using restriction fragment length polymorphism–PCR and direct sequencing.

Results

We found no significant correlation between the CTLA-4-318 C > T T allele and inhibitor development among patients with severe or mild/moderate HA. However, a significantly high inhibitor risk was detected for the CTLA-4 + 49 A > G G allele (odds ratio [OR] = 3.1, 95% confidence interval [CI] = 1.383–7.024) and (OR = 4, 95% CI = 1.719–9.437) among patients with severe and mild/moderate HA, respectively.

Conclusion

We conclude that the CTLA-4 +49 A > G SNP plays a substantial role as a potential risk determinant for inhibitor formation in Iraqi Kurdish patients with HA.

Role of CTLA4 A49G polymorphism in systemic lupus erythematosus and its geographical distribution

CTLA-4 (cytotoxic T-lymphocyte-associated protein-4) or CD152 is an inhibitory receptor expressed constitutively on CD4+ CD25+ T regulatory lymphocytes and transiently on activated CD4+ and CD8+ T lymphocytes. Its inhibitory function promotes long-lived anergy in immune cells and prevents autoimmunity. Therefore, it plays a crucial role in T cell-mediated autoimmunity, and thus in susceptibility to autoimmune diseases, including systemic lupus erythematosus (SLE). It is encoded by CTLA4 gene in humans. AtoG polymorphism at position +49 of CTLA4 gene is the only polymorphism which changes amino acid sequence from alanine to threonine in the leader sequence, which may affect the function of CTLA-4. Association of CTLA4 polymorphisms with SLE has been investigated in several reports in different ethnic populations from different countries, which have shown highly inconsistent findings. In this review, we have compiled previous studies which have reported the association of CTLA4 A49G polymorphism in SLE and its geographical distribution.

Association of CTLA-4 and CD28 Gene Polymorphisms with Type 1 Diabetes in South Indian Population

Each functional gene illustrates the complexity of genetic predisposition to disease; however, it is difficult to bring out these traits with reference to autoimmune diseases like type 1 diabetes (T1D). To find out the genetic contribution of CTLA-4 + 49A/G, CTLA-4 -318C/T and CD28 + 17T/C polymorphisms toward T1D, the present study was performed with 124 T1D patients, 54 siblings and 125 parents including 39 trios in South Indian population. The association and linkage of CTLA-4 + 49A/G, CTLA-4 -318C/T and CD28 + 17T/C polymorphisms with T1D were analyzed and transmission disequilibrium test was performed. CTLA-4 G allele carrying genotypes (GG+AG) showed a higher risk association and can be considered as susceptible to develop T1D among patients with age at diagnosis from 0 to 10 years as compared to siblings (OR = 2.9; p_c = 0.047) and parents (OR = 2.7; p_c = 0.036). On the other hand, a strong protection against the disease (age at diagnosis; 0-10 years) was observed with CTLA-4 + 49AA genotype (OR = 0.37; p_c = 0.036) and combined AA/CC genotype (OR = 0.31; p_c = 0.034) of CTLA-4 + 49A/G and CTLA-4 -318C/T polymorphisms. However, a significant association was not observed between CTLA-4 -318C/T and CD28 + 17T/C polymorphisms and T1D. This family-based study reports a strong association between possible genotypes of CTLA-4 gene polymorphism and T1D in South Indian population, particularly in younger individuals.

Association of CD28 and CTLA4 haplotypes with susceptibility to primary Sjögren's syndrome in Mexican population

BACKGROUND

Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by destruction of exocrine glands as a result of T and B cells infiltrated in glandular tissue. CD28 and CTLA-4 play a crucial role in T cell activation and inhibition. The aim of this study was to associate CD28 and CTLA4 haplotypes with susceptibility to pSS in patients from western Mexico.

METHODS

Polymerase chain reaction and restriction fragment length polymorphism were performed to identify CD28 and CTLA4 genotypes in 111 patients with pSS and 138 control subjects (CS). Haplotype analysis was carried out by SHEsis program. Soluble serum levels of CD28 (sCD28) and CTLA-4 (sCTLA-4) were quantified by ELISA kit.

RESULTS

The CD28 GC haplotype was associated with low risk to pSS (2.5-folds, P < 0.001). CTLA4 CAG and CGA were identified as genetic risk factor (P < 0.001;OR = 3.82[CI95%:2.022-7.296] and P < 0.001; OR = 11.38[CI95%:3.282-37.69] respectively). No difference in sCD28 and sCTLA-4 were found between patients and CS. However, pSS patients carriers of CD28 IVS3 + 17TC genotype showed high sCD28 (P = 0.039 vs TT carriers in CS). In regard to sCTLA-4, patient who carry CTLA4-319C>T, +49 A>G, and +6230 G>A, or their haplotypes did not show any difference.

CONCLUSION

Our findings suggest that CD28 GC, CTLA4 CAG, and CGA haplotypes are associated with susceptibility to pSS in patients from western Mexico. It seems that genetic control of CD28 and CTLA4 as well as local immune response in glandular tissue may regulate the impact of the gene expression in pSS. It is necessary to confirm this hypothesis in an integrative study.

Distribution of Cytotoxic T Lymphocyte-Associated Antigen-4 Promoter Polymorphisms in Taiwanese Patients with Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is associated with chronic inflammation, suggesting the metabolic abnormalities are originated from or exacerbated by cytokine overproduction. Cytokines and counter-regulatory molecules are crucial in keeping the balance of immune responses and, therefore, are potential candidates involved in T2DM etiology, development and complications. Our previous reports identify several significant associations between the genotypes of cytokine genes and T2DM and/or the clinical lipid parameters, which strongly suggest the participation of immune-regulatory molecules in lipid metabolism. The aim of this study is to determine the distribution of gene encoding cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), a T-cell negative regulator, in T2DM patients and health subjects. Genomic DNA was extracted from 287 Taiwanese T2DM patients and 278 ethnic- and age- matched healthy subjects, and two CTLA-4 polymorphisms (-318 C/T and +49 A/G) were analyzed by polymerase chain reaction-restriction fragment length polymorphism. Intriguingly, CTLA-4 -318 genotype was associated with circulatory triglycerides in T2DM subjects (P=0.019) although no significant association between CTLA-4 -318 (P=0.119) and +49 (P=0.2) genotypes with T2DM was identified. In addition, CTLA-4 +49 genotype was significantly associated with the ratio between total cholesterol and high-density lipoprotein (P=0.004) in control subjects. Our results suggest that CTLA-4 may be involved in lipid metabolism and affect T2DM disease progression and/or the development of diabetic complications although this gene does not represent a major risk factor for T2DM.

Expression and activity analyses of CTLA4 in peripheral blood lymphocytes in systemic lupus erythematosus patients

The objective of this study was to determine the expression and activity of CTLA4 in T-cells of systemic lupus erythematosus (SLE) patients. Expression of CTLA4 on freshly isolated peripheral blood T-cells was evaluated in 33 SLE patients and 25 controls using flow cytometry.The T-cells from 19 SLE patients and 22 controls were stimulated and cultured with Chinese hamster ovary cells expressing CD80 (CHO-CD80) or with CHO cells. T-cell proliferation was determined with [3H] thymidine incorporation (CPM), and the inhibitory effect of CTLA4 on T-cell proliferation was evaluated by the ratio of CPM for T-cells with CHO -CD80 cells to that of T-cells with CHO cells (the CHO -CD80/CHO ratio). IntracellularCTLA4 expressionin freshly isolated peripheral blood T-cells was significantly higher in SLE patients than the controls (P < 0.05), but there was no correlation with clinical features or disease activity. The CHO -CD80/CHO ratio of SLE patients was significantly higher than that of the controls(P < 0.05). Among SLE patients, the CHO -CD80/CHO ratio of patients with lupus nephritis was significantly higher than that of patients without lupus nephritis (P < 0.05). In conclusion, our data suggest that CTLA4 expression is not impaired in SLE patients, but there is a possibility of decreased inhibitory effect of CTLA4 involved in the pathogenesis of SLE.

CTLA-4 polymorphisms and haplotype correlate with survival in ALL after allogeneic stem cell transplantation from related HLA-haplotype-mismatched donor

Background

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been established as an effective treatment for patients with hematological malignancies. Disease relapse remains a major cause of transplant failure. T cell homeostasis is critical to determine the potency of the GVT effect. Recent studies have shown the association of the CTLA-4 polymorphisms with the outcome after HLA-identical sibling allogeneic HSCT.

Methods

In this study, we focused on four CTLA-4 polymorphisms, and analyzed the impact of donor genotypes and haplotypes on the conditions of 152 acute leukemia patients (ALL 83) after related HLA-haplotype- mismatched transplantation. The four SNP genotypes (−1661, −318, CT60 and +49) were determined by TaqMan SNP genotyping assays.

Results

ALL recipients of donors with +49 GG showed significantly lower OS (67.7 vs. 90.3 %, P = 0.015) than those with GA+AA. Multivariate analyses showed that +49 GG was an independent risk factor for OS (HR: 0.306, 95 % CI 0.111–0.842, P = 0.022) .23 ALL patients receiving mDLI showed significantly lower OS with +49 GG donor than those with GA+AA (30.0 vs. 83.1 %, P = 0.003). The haplotype analysis revealed only three haplotypes in the donor population −1661/−318/CT60/+49 i.e., ACGG, ACAA and GTGA, the frequencies were 64.1, 19.4 and 16.5 %, respectively. Donors with and without the ACGG/ACGG haplotype had the same effect on transplant outcomes as those with +49 GG and +49 GA+AA.

Conclusion

In summary, the CTLA-4 +49 GG and the haplotype ACGG/ACGG reduced the overall survival in ALL after allo-HSCT from the related HLA-haplotype-mismatched donor, knowledge of the CTLA-4 polymorphism and haplotype may provide useful information for donor selection and individual application of immunosuppressive agents and immunotherapy.

Association of CTLA4 exon-1 polymorphism with the tumor necrosis factor-α in the risk of systemic lupus erythematosus among South Indians

Cytotoxic T lymphocyte associated-antigen (CTLA4) is a potential negative regulatory molecule of T-cells and associated with several autoimmune diseases. Several reports from different ethnic groups showed that the polymorphisms of the CTLA4 gene have been associated with autoimmune diseases including SLE. Therefore, we aimed to investigate the +49 A/G polymorphism in South Indian SLE patients and its association with disease aetiology and serological markers. A total of 534 samples were genotyped for the +49 A/G polymorphism in exon 1 of the CTLA-4 gene through PCR-RFLP method. We found significant association of genotype and allele frequencies with +49 A/G polymorphism in SLE patients. The frequency of the +49 A/G polymorphism rs231775 'GG' genotype was significantly higher in patients with SLE (12.32%) than those in healthy control subjects (4.6%) (OR: 1.797; 95% CI 1.264-2.554; p=0.001). The frequency of mutant allele 'G' also found to be significantly higher in cases (36.01%) than controls (24.92%) (OR: 1.695, 95% CI: 1.298-2.214, p<0.001). We observed significant increase in serum TNF-α, interferon-α, IL-10 and IL-12 in SLE cases compared to controls. We also found a significant association of serum TNF-α, interferon-α, IL-10 and IL-12 with SLE phenotypes. In addition there was a significant increase in serum TNF-α level in "GG" genotype SLE subjects suggesting that it might play a major role in the advancement of SLE disease.

CTLA-4 as a genetic determinant in autoimmune Addison's disease

In common with several other autoimmune diseases, autoimmune Addison's disease (AAD) is thought to be caused by a combination of deleterious susceptibility polymorphisms in several genes, together with undefined environmental factors and stochastic events. To date, the strongest genomic association with AAD has been with alleles at the HLA locus, DR3-DQ2 and DR4. The contribution of other genetic variants has been inconsistent. We have studied the association of 16 single-nucleotide polymorphisms (SNPs) within the CD28-CTLA-4-ICOS genomic locus, in a cohort comprising 691 AAD patients of Norwegian and UK origin with matched controls. We have also performed a meta-analysis including 1002 patients from European countries. The G-allele of SNP rs231775 in CTLA-4 is associated with AAD in Norwegian patients (odds ratio (OR)=1.35 (confidence interval (CI) 1.10-1.66), P=0.004), but not in UK patients. The same allele is associated with AAD in the total European population (OR=1.37 (CI 1.13-1.66), P=0.002). A three-marker haplotype, comprising PROMOTER_1661, rs231726 and rs1896286 was found to be associated with AAD in the Norwegian cohort only (OR 2.43 (CI 1.68-3.51), P=0.00013). This study points to the CTLA-4 gene as a susceptibility locus for the development of AAD, and refines its mapping within the wider genomic locus.

A deeper understanding of the association between CTLA4 +49A/G and acute rejection in renal transplantation: an updated meta-analysis

To reevaluate the association between the costimulatory molecule cytotoxic T lymphocyte-associated antigen4 (CTLA4) single nucleotide polymorphism (SNP) +49A/G and acute rejection (AR) in renal transplantation, nine studies published before June 2013 were analyzed. Meta-analysis and cumulative meta-analysis (metacum) were performed for each genotype in a random/fixed effect model. The combined odds ratios (OR) with 95% confidence intervals (CI) were calculated to estimate the strength of the association. In the sensitivity analysis, a single study involved in the meta-analysis was deleted each time to investigate the influence of the individual data sets on the pooled ORs. Meta-analysis regression was used for some influence factors, such as year of publication, total number in each group (AR group and control group), ethnicity, the ratio of GG to GA + AA, the ratio of G to A in CTLA4 +49A/G. Overall, a significant correlation was noted between the CTLA4 SNP (+49A/G) and the risk of AR (for GG vs. AG + AA: OR = 1.35, 95% CI = 1.05-1.73, p = 0.02; for G vs. A: OR = 1.21, 95% CI = 1.03-1.42, p = 0.02), especially in the Asian subgroup (for GG vs. AG + AA: OR = 1.79, 95% CI = 1.15-2.78, p = 0.009; for G vs. A: OR = 1.47, 95% CI = 1.04-2.07, p = 0.03). Of the influence factors, the ratio of GG to GA+AA (p = 0.046) and the ratio of G to A (p = 0.017) were significant factors. In conclusion, our results suggest that CTLA4 +49A/G contribute to the risk of AR following renal transplantation.

The CTLA4 +49 A/G (rs231775) polymorphism influences susceptibility to SLE in South Indian Tamils

Systemic lupus erythematosus (SLE) is a prototype autoimmune disease with complex etiology. Loss of immune tolerance and synthesis of autoantibodies against nuclear antigens contributes to the disease. Genetic aberrations disrupting the functions of immune regulatory receptors may facilitate the development of autoimmune diseases. Cytotoxic T-lymphocyte antigen 4 (CTLA4) is an inhibitory receptor for T cells and this study was carried out to analyze the influence of CTLA4 +49A/G (rs231775) polymorphism on susceptibility to SLE in ethnic Tamils. Three hundred SLE patients and 460 age and sex similar, ethnicity-matched controls were screened for the +49 A/G polymorphism by real time polymerase chain reaction (PCR). The wild allele (A) frequency in controls and cases was 63% and 47%, respectively. The presence of heterozygous (AG) and homozygous mutant (GG) genotype was associated with a significant risk to develop SLE (P = 0.0001, OR-2.29, 95% confidence interval (CI), 1.6-3.3) and (P = 0.0001, OR-4.3, 95% CI, 2.8-6.99). The frequency of mutant allele (G) in patients was also significantly associated with SLE (P = 0.0001, OR-1.9, 95% CI, 1.5-2.4). However, this polymorphism did not influence the clinical or serological phenotypes in our study. Therefore the CTLA4 +49 A/G polymorphism is a potential genetic risk factor for lupus susceptibility in South Indian Tamils, but does not appear to influence either the clinical or serological phenotype.

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.

Influence of cytotoxic T lymphocyte-associated antigen 4 polymorphisms on the outcomes of hepatitis B virus infection

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) regulates T-cell activation and Th1/Th2 cytokine production and is involved in the immune response against Hepatitis B virus (HBV) infection. To detect the association of the CTLA-4 gene polymorphisms with susceptibility to HBV infection a hospital-based case-control study was conducted. A total of 1,119 unrelated individuals were recruited. The CTLA-4 variants rs5742909, rs231775 and rs3087243 were genotyped via the TaqMan method in this cohort. A comparison with a chronic active hepatitis B group revealed that the SNP rs231775 exhibited significant susceptibility to HBV progression, with the highest odds ratio (OR) reaching 1.659 and P=0.009-0.049. Although an HBV clearance group was used as a control, results of the present study demonstrated an association of rs5742909 with viral persistence [OR=1.694, 95% confidence intervals (CI)=1.124-2.553 and P=0.012]. Subsequent analyses revealed risk haplotypes (C-A-A and T-A-G, for which the highest OR reached 1.865) compared with the protective haplotype C-G-G. Therefore, SNPs in the CTLA-4 gene may be associated with HBV progression and viral persistence which is consistent with its emerging role in the T regulatory cells in the pathogenesis of disease.

CTLA-4 polymorphisms and systemic lupus erythematosus (SLE): a meta-analysis

The aim of this study was to summarize results on the association of cytotoxic T-lymphocyte antigen-4 (CTLA-4) promoter exon-1 +49 and 1722T/C polymorphism with systemic lupus erythematosus (SLE) susceptibility by using the meta-analysis. We searched all the publications about the association between CTLA-4) promoter exon-1 +49 and 1722T/C polymorphism and SLE from PubMed, Elsevier Science Direct, Chinese Biomedical Literature Database (CBM), Chinese National Knowledge Infrastructure (CNKI), and Wanfang (Chinese). Previous CTLA-4 association studies with SLE, however, have produced inconsistent results. We have performed a meta-analysis to better assess the purported associations. A total of 17 independent studies (to June 2012) testing association between one or more CTLA-4 polymorphisms and SLE were used in this analysis. We have compared allele and genotype frequencies at two polymorphic sites found in exon-1 (at +49) and the promoter region (at -1722). The data demonstrate that the exon-1 +49 polymorphism is associated with SLE susceptibility in Asian population. The overall risk, measured by odds ratio (OR), stratification by ethnicity indicates the exon-1 +49 GG+GA genotype is associated with SLE, at least in Asians (OR = 0.85, 95 % CI = 0.73-0.99, P = 0.04 for GG+GA vs. AA; OR = 0.85, 95 % CI = 0.72-1.00, P = 0.05 for AG vs. AA). Similar trends are found in allele-specific risk estimates and disease association. Overall, there was significant association between the 1722T/C polymorphism and overall SLE risks (OR = 0.78, 95 % CI = 0.63-0.97, P = 0.04 for GG+GA vs. AA, OR = 0.87, 95 % CI = 0.76-0.99, P = 0.04 for G vs. A) in Asian population.In summary, this meta-analysis demonstrates that the CTLA-4 promoter +49A/G and promoter -1722C/T polymorphism may confer susceptibility to SLE, especially in Asian-derived population.

Association of cytotoxic T-lymphocyte antigen 4 genetic polymorphism, hepatitis C viral infection and B-cell non-Hodgkin lymphoma: an Egyptian study

Abstract Genetic and environmental factors are involved in the pathogenesis of non-Hodgkin lymphoma (NHL). The present study aimed to investigate the association between cytotoxic T-lymphocyte antigen 4 (CTLA-4) genetic polymorphism, hepatitis C virus (HCV) infection and B-cell NHL risk in Egypt. Genotyping of CTLA-4 single nucleotide polymorphisms (SNPs) was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay for 181 adult patients with B-NHL and 200 controls. Our study revealed that CTLA-4 + 49 A/G polymorphism conferred increased risk of B-NHL (odds ratio [OR] = 1.7, 95% confidence interval [CI] = 1.36-2.565). The prevalence of HCV infection in individuals harboring the mutant genotype + 49 A/G and - 318 C/T SNPs was higher in patients with B-NHL and was associated with increased risk of B-NHL (OR = 2.79, 95% CI = 1.24-6.93 for + 49 A/G and OR = 3.9, 95% CI = 1.01-15.98 for - 318 C/T). In conclusion, some SNPs of CTLA-4 are genetic risk factors for B-NHL. Moreover, this study identified an association of CTLA-4 + 49 A/G and - 318 C/T promoter polymorphisms with HCV infection.

Association of Hashimoto's thyroiditis with cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and inducible co-stimulator (ICOS) genes in a Kuwaiti population

Analysing two CTLA-4 markers [exon 1 A49G single nucleotide polymorphism (SNP) and exon 4 3'UTR (AT)n repeat] and the ICOS intron 4 (GT)n marker for their potential association with HT, and exploring the effect of the tested SNPs on the CTLA-4 isoform expression at the mRNA and protein levels. Total of 270 age-gender-ethnically matched subjects were genotyped by fluorescent-labelled restriction fragment length polymorphism, multiplex PCR, and fragment analysis. Sequencing was used to confirm the genotyping results. Expression of the full-length and soluble CTLA-4 mRNAs analysed using real-time PCR. Sera from subjects were screened for sCTLA-4 using ELISA. Tested subjects revealed ten alleles and sixteen genotypes of CTLA-4 3'UTR(AT)n. The 3'UTR(AT)n was significantly associated with HT: allele (AT)15 and genotype 15/15 were found to cause susceptibility to HT (P = 0.004, OR = 2.13, 95 % CI = 1.26-3.58 and P = 0.029, OR = 2.77, 95 % CI = 1.1-6.94, respectively), whereas allele (AT)6 and genotype 6/6 were found to be protective of HT (P = 0.00002, OR = 0.36, 95 % CI = 0.227-0.57 and P = 0.001, OR = 0.357, 95 % CI = 0.1980.64, respectively). SNP A49G and ICOS(GT)n revealed no significant association with HT (P > 0.05). The expression of sCTLA-4 was inversely proportional to the number of 3'UTR(AT)n repeats, with heterozygous and longer (AT)n repeats showing lower levels of sCTLA-4 mRNA than those with shorter alleles in HC and HT (P = 0.001 and P = 0.04, respectively). Significant increase in the serum level of sCTLA-4 was observed in HT patients compared with the HC (P = 0.0007). The novel finding in our study is that the CTLA-4 3'UTR(AT)n proven to be a key player in the pathogenesis of HT.

Overexpression and secretion of the soluble CTLA-4 splice variant in various autoimmune diseases and in cases with overlapping autoimmunity

AIM

To explore the potential genetic association of CTLA-4 Exon1 +49A/G and 3'UTR (AT)(n) to susceptibility to systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and overlapping (OP) autoimmunity; affected with more than one autoimmune disease. Expression of two major CTLA-4 isoforms; full length (mCTLA-4) and soluble (sCTLA-4) were explored in all subjects. A total of 680-age/gender/ethnically matched Kuwaitis were recruited and polymerase chain reaction (PCR)-fragment analysis was employed for genotyping both markers. mCTLA-4 and sCTLA-4 mRNA expression were analyzed using quantitative real time-PCR. The enzyme-linked immunosorbent assay (ELISA) was used to screen sCTLA-4 in all subjects' sera.

RESULTS

Only two CTLA-4 3'UTR (AT)(n) allelotypes; (AT)(15) and (AT)(6) were detected. The heterozygous (AT)(15/6) genotype confers protectivity rather than susceptibility to SLE (p=0.01, odds ratio=0.43, and confidence interval=0.21-0.86). No significant association was observed between Exon 1 +49A/G and any of the tested diseases. A consistently high serum sCTLA-4 level was observed in RA (6.8 ng/mL, p=0.005), SLE (6.34 ng/mL, p=0.007), and OP (8.75 ng/mL, p=0.012) compared to healthy control. A significant increase in the expression of sCTLA-4 mRNA was observed in OP (p=0.05) and SLE (p=0.047), while a significant increase in the expression of mCTLA-4 (p=0.01) was observed only in OP.

CONCLUSION

The present study is the first to report a statistically significant association between OP and serum sCTLA-4. The novelty of our study is the significance of CTLA-4 in the pathogenesis of OP besides SLE and RA.

CTLA-4 polymorphisms and systemic lupus erythematosus: a comprehensive meta-analysis

OBJECTIVE

The aim of this study was to determine whether the SNPs +49A/G and CT60A/G of the CTLA-4 gene are associated with susceptibility to systemic lupus erythematosus (SLE).

METHODS

The comprehensive meta-analysis for +49A/G included 1753 cases and 2279 controls, and for CT60A/G included 676 cases and 576 controls. Allelic and genotypic comparisons between cases and controls were evaluated. For +49A/G, we also subdivided it by population.

RESULTS

For +49A/G, statistically significant differences were not noted (fixed: odds ratio [OR]: 1.033, 95% confidence interval [95% CI]: 0.937-1.139; random: OR: 1.038, 95% CI: 0.907-1.188). When subdivided into Asia and Europe subgroups, it showed that this polymorphism is still not significantly associated with SLE [for Asia: (fixed: OR: 1.069, 95% CI: 0.932-1.227; random: OR: 1.055, 95% CI: 0.846-1.316); for Europe: (fixed: OR: 0.988, 95% CI: 0.842-1.161; random: OR: 1.015, 95% CI: 0.805-1.281)]. And CT60A/G also did not demonstrate significant differences with SLE (fixed: OR: 1.099, 95% CI: 0.922-1.31; random: OR: 0.918, 95% CI: 0.581-1.448).

CONCLUSION

The results suggest that the CLTA-4 gene was not associated with SLE. Further investigations are required to identify whether other at-risk polymorphisms within CTLA-4 confer a risk of SLE and to clarify the role of the CTLA-4 gene.

CTLA-4 exon 1 +49A/G polymorphism is associated with renal involvement in pediatric Henoch-Schönlein purpura

BACKGROUND

Henoch-Schönlein purpura (HSP) is a multisystemic vasculitis of unknown etiology. Cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and CD28 have been reported to be important candidate genes for conferring susceptibility to autoimmunity. In this study, we investigated the correlation of CTLA-4 and CD28 gene polymorphisms with HSP in children with and without renal involvement.

METHODS

The CTLA-4 exon 1 +49A/G, promoter -318C/T and CD28 IVS3 +17T/C single nucleotide polymorphisms (SNPs) were genotyped in 110 children with HSP and 90 ethnically matched healthy controls through restriction fragment-length polymorphism (RFLP).

RESULTS

The CTLA-4 (+49) GG genotype and G allele (GG + AG genotype) were more common in HSP patients with renal involvement (n = 52) than in HSP patients without renal involvement (n = 58) (P = 0.019 and 0.001, respectively). There were no significant differences in the prevalence of CTLA-4 (+49 A/G), (-318C/T) and CD28 IVS3 (+17 /T/C) polymorphisms between HSP patients and controls.

CONCLUSIONS

Our findings suggest that the CTLA-4 +49 GG genotype and G allele may contribute to increased risk for the development of renal damage in HSP patients.

Analysis of cytotoxic T lymphocyte antigen-4 (CTLA-4) promoter -318C/T and +49A/G gene polymorphisms in Turkish patients with familial Mediterranean fever

Either the role of the adaptive immune system or the interaction between innate and adaptive immune systems in familial Mediterranean fever (FMF) is not clear so far. So, we planned to search for the interaction between the innate and adaptive immune systems in the pathogenesis of FMF by investigating polymorphism for CTLA-4 gene, which plays a role in controlling antigen presentation to T cells. We also aimed to investigate whether there is an association between -318C/T and +49A/G polymorphisms in the CTLA-4 gene and the main clinical features of the disease. 75 FMF patients and 179 controls were studied. Polymorphism was detected by the PCR-RFLP technique. The CT genotype and T allele frequencies of the -318C/T polymorphism and the haplotype frequency for the -318T/+49A in the CTLA-4 gene were higher in the FMF (21.3, 21.3, and 10.7 %) when compared with the controls (10.6, 10.6, and 5.3 %; P = 0.029, 0.044, and 0.029). However, these differences did not reach a statistically significant level after the Bonferroni correction. A significant linkage disequilibrium was found between the -318C/T and +49A/G polymorphisms in the CTLA-4 gene (D' = 0.997, r(2) = 0.027, P = 0.0002). Genotype and carrier frequencies of the CTLA-4 gene +49A/G polymorphism were not significantly different between FMF patients and healthy controls. No association was found between the studied polymorphisms and the main clinical features of the disease. Our findings suggest that although not statistically significant, higher frequencies of CTLA-4 gene -318CT genotype, T allele, and -318T/+49A haplotype in FMF patients may be related to the non-autoimmune pathogenesis of FMF.

Correlations of CTLA-4 gene polymorphisms and hepatitis C chronic infection

BACKGROUND

Cytotoxic T lymphocyte-associated factor 4 (CTLA-4) functions as a negative regulator of T cell-mediated immune response. Molecular changes associated to CTLA-4 gene polymorphisms could reduce its ability to suppress and control lymphocyte proliferation.

AIMS

To evaluate the frequency of CTLA-4 gene polymorphisms in chronic hepatitis C virus (HCV) infected patients and correlate to clinical and histological findings.

METHODS

We evaluated 112 HCV-infected subjects prospectively selected and 183 healthy controls. Clinical and liver histological data were analysed. -318C > T, A49G and CT60 CTLA-4 single-nucleotide polymorphisms (SNPs) were studied by PCR-RFLP and AT(n) polymorphism by DNA fragment analysis by capillary electrophoresis in automatic sequencer.

RESULTS

Eight AT repetitions in 3'UTR region were more frequent in HCV-infected subjects. We found a positive association of -318C and + 49G with HCV genotype 3 (P = 0.008, OR 9.13, P = 0.004, OR 2.49 respectively) and an inverse association of both alleles with HCV genotype 1 (P = 0.020, OR 0.19, P = 0.002, OR 0.38 respectively). Allele + 49G was also associated to aminotransferases quotients > 3 (qALT, P = 0.034, qAST, P = 0.041). Allele G of CT60 SNP was also associated with qAST > 3 (P = 0.012). Increased number of AT repetitions was positively associated to severe necroinflammatory activity scores in liver biopsies (P = 0.045, OR 4.62).

CONCLUSION

CTLA-4 gene polymorphisms were associated to HCV-infection. Eight AT repetitions were more prevalent in HCV-infected subjects. -318C and + 49G alleles were associated to genotypes 1 and 3 infections and increased number of AT repetitions in 3'UTR region favoured severe necroinflammatory activity scores in liver biopsies.

Genetic polymorphisms and surface expression of CTLA-4 and PD-1 on T cells of silica-exposed workers

Exposure to silica dust has been examined as a possible risk factor for autoimmune diseases, including scleroderma, rheumatoid arthritis and systemic lupus erythematosus. Since CTLA-4 [CD152] and PD-1 [CD279] are important for the maintenance of peripheral tolerance by regulating T cell responsiveness, we evaluated the expression of these molecules on the surface of CD4 and CD8 T cells, as well as single nucleotide polymorphisms (SNP) in CTLA-4 and PDCD1 genes, of 70 silica-exposed workers and 30 non-exposed, age-, ethnically- and sex-matched controls. Expression of CTLA-4 was significantly (P<0.05) reduced in CD4 T cells of exposed individuals [median=0.1% and interquartile range, IQR 0.0-0.1% (exposed), median=0.20%, IQR 0.0-0.4% (control)]. Also the expression of PD-1 was significantly (P<0.0001) reduced in both CD4 [median=0.9%, IQR 0.4-2.3% (exposed), median=5.7%, IQR 1.4-13.3% (control)] and CD8 T cells [median=0.9%, IQR 0.3-1.9% (exposed), median=5.0%, IQR 3.4-8.9% (control)]. The study of polymorphisms demonstrated a lower frequency of the A allele in the analysis of the PD1.3 SNP in the exposed group, which might be associated with the lower expression of PD-1 on the surface of CD4 T cells. Our findings provide evidence for the association of silica exposure and the maintenance of self-tolerance, i.e., the susceptibility to autoimmune disorders.

CTLA-4 gene polymorphism and the risk of systemic lupus erythematosus in the Chinese population

Several variants of CTLA-4 have been reported to be associated with susceptibility systemic lupus erythematosus (SLE); however, findings have been inconsistent across different populations. Using a case-control study design, we have investigated the role of CTLA-4 polymorphism at positions −1661 and −1722 on SLE susceptibility in our Chinese SLE population in central China's Hubei province. Samples were collected from 148 SLE patients and 170 healthy controls. Polymerase chain reaction restriction fragments length polymorphism (PCR-RFLP) was used to analyze the genotypes of the two sites. Statistically significant difference was observed in genotypes for −1722, but not for −1661. The frequency of the T allele on the −1722 SNP was significantly increased in SLE patients: 57.8% versus 40.6% in controls (P < 0.001, OR = 2.002). While the detected C allele frequency in the controls was significantly elevated in comparison to that in the SLE patients (59.4% versus 42.2%). On the contrary, no association was found between SLE and CTLA-4 polymorphism at position −1661.

(AT) repeat in the 3' untranslated region of the CTLA-4 gene and susceptibility to acute allograft rejection in Tunisian renal transplantation

Allograft rejection is an immune response relying on the proliferation and the differentiation of T cells. CTLA-4 is a co-stimulatory molecule, expressed on activated T lymphocytes, which has been shown to play a crucial role in the down-regulation of T-cell activation. Herein, we have examined the impart of a genetic marker in the CTLA-4 gene on renal transplant outcomes. A cohort of 144 renal recipients and 100 healthy subjects were genotyped by the fragments analysis method using an automated sequencer. Patients were classified into two groups: Group I included 31 HLA-identical haplotype allograft recipients and Group II, 113 showing one or more HLA haplotype mismatches. Forty patients (27.78%) developed at least one acute rejection episode (ARE): 9 in Group I and 31 in Group II. Before transplantation, 20 patients were lymphocytotoxic antibodies (LCT) positive: 4 Group I, 2 of whom developed an ARE, and sixty in Group II, including 8 with an ARE. The occurrence of an ARE was associated with the presence of LCT before transplantation among the entire cohort of patients (P = .032) and among Group II (P = .037). The allelic frequencies of (AT)n polymorphism did not reveal significant differences between patients and controls. The most prevalent alleles were the 88 bp (51% in controls and 44.44% in patients) and the 106 bp (8% and 10.76%, respectively). We noticed an increase of the 120 bp allele frequency among patients who had undergone an ARE compared with those who did not display this complication (8.75% vs 3.85%). Likewise, among LCT-negative Group I, recipients the incidence of the 120 bp allele was higher in ARE than non-ARE patients. Although the differences were not statistically significant, we propose that the 120 bp allele of the CTLA-4 gene (AT)n microsatellite a predisposes to acute rejection episodes in renal transplantation.

Cytotoxic T-lymphocyte antigen 4 haplotype correlates with relapse and survival after allogeneic hematopoietic SCT

CTLA-4 is a negative regulator of activated T cells and the association of CTLA-4 polymorphisms with autoimmune diseases and transplant outcome has been reported. We evaluated the effect of donor CTLA-4 polymorphisms on outcome after allogeneic hematopoietic SCT (HSCT). We analyzed 147 Japanese HLA-matched sibling recipients and their donors who had undergone allogeneic HSCT. Genotyping of three single-nucleotide polymorphisms in CTLA-4 (-318, +49, CT60) was performed using TaqMan-PCR. According to the international HapMap database, only these three CTLA-4 haplotypes, classified as C-G-G, C-A-A and T-A-G, are present in the Japanese population. In this study, percentage expression of the C-G-G, C-A-A and T-A-G haplotypes was 59.5, 30.6 and 9.9%, respectively. Recipients of the C-A-A haplotype donor showed a significantly lower risk of relapse (HR: 0.54, 95% CI: 0.30-0.97, P=0.040) and a trend toward higher OS (HR: 0.61, 95% CI: 0.36-1.0, P=0.054) than did recipients of a donor without the C-A-A haplotype. The presence or absence of the C-A-A haplotype did not affect GVHD or non-relapse mortality. As the presence of the C-A-A haplotype reduced relapse risk and improved survival after allogeneic HSCT, this CTLA-4 haplotype may provide useful information for donor selection.