Association between the CTLA-4 +49A/G polymorphism and Graves' disease: A meta-analysis

Association of cytotoxic T-lymphocyte antigen-4 (CTLA-4) single nucleotide polymorphism in donors with clinical outcome after allogeneic hematopoietic stem cell transplantation: a meta-analysis

OBJECTIVE

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) polymorphisms at positions of +49 and CT60 in donors have been reported to influence clinical outcome following allogeneic hematopoietic stem cell transplantation (allo-HSCT), such as overall survival (OS), disease free survival (DFS), relapse and the risk of graft versus host disease (GVHD). However, the results still remain controversial. Thus, we conducted the first meta-analysis to get a more accurate estimation of the relationship between CTLA-4 genotype and the above end points.

METHODS

PubMed, Embase, Web of science and Cochrane Library were searched to select eligible studies, data were extracted and then combined ORs/HRs together with the corresponding 95% confidence intervals (CIs) were calculated. Both the dominant and recessive models were employed to evaluate the associations between genetic variation in donor CTLA-4 and outcome after allo-HSCT.

RESULTS

A total of 15 studies were included the pooled results indicated that +49 GG homozygote in donors was significantly associated with increased risk of chronic GVHD (OR=1.701, 95% CI, 1.124-2.573, P=0.012, I²=34.7%). With regard to CT60 polymorphism, donors with G allele correlated with worse OS (HR = 1.422, 95% CI, 1.080-1.872, P=0.012, I²=0%) and lower susceptibility to severe acute GVHD (HR=0.619, 95% CI, 0.426-0.899, P=0.012, I²=0%). There was no significant association between CTLA-4 polymorphism and DFS or the incidence of relapse.

CONCLUSIONS

The present meta-analysis suggests that donors with CT60 G allele might be associated with worse OS but reduced severe aGVHD occurrence, while patients transplanted from donors with GG genotype at position of +49 are more likely to suffer from cGVHD.

Association of Cytotoxic T-Lymphocyte-Associated Protein 4 (CTLA4) Gene Polymorphisms with Autoimmune Thyroid Disease in Children and Adults: Case-Control Study

Autoimmune thyroid disease (AITD), including Graves disease (GD) and Hashimoto disease (HD), is an organ-specific autoimmune disease with a strong genetic component. Although the cytotoxic T-lymphocyte-associated protein 4 (CTLA4) polymorphism has been reported to be associated with AITD in adults, few studies have focused on children. The aim of our study was to investigate whether the CTLA4 polymorphisms, including -318C/T (rs5742909), +49A/G (rs231775), and CT60 (rs3087243), were associated with GD and HD in Han Chinese adults and children. We studied 289 adult GD, 265 pediatric GD, 229 pediatric HD patients, and 1058 healthy controls and then compared genotype, allele, carrier, and haplotype frequencies between patients and controls. We found that CTLA4 SNPs +49A/G and CT60 were associated with GD in adults and children. Allele G of +49A/G was significantly associated with GD in adults (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.21–1.84; corrected P value [Pc] < 0.001) and children (OR, 1.42; 95% CI, 1.15–1.77; Pc = 0.002). Allele G of CT60 also significantly increased risk of GD in adults (OR, 1.63; 95% CI, 1.27–2.09; Pc < 0.001) and GD in children (OR, 1.58; 95% CI, 1.22–2.04; Pc < 0.001). Significant linkage disequilibrium was found between +49A/G and CT60 in GD and control subjects (D’ = 0.92). Our results showed that CTLA4 was associated with both GD and HD and played an equivalent role in both adult and pediatric GD in Han Chinese population.

Impact of population admixture on the distribution of immune response co-stimulatory genes polymorphisms in a Brazilian population

Co-stimulatory molecules are essential in the orchestration of immune response and polymorphisms in their genes are associated with various diseases. However, in the case of variable allele frequencies among continental populations, this variation can lead to biases in genetic studies conducted in admixed populations such as those from Brazil. The aim of this study was to evaluate the influence of genomic ancestry on distributions of co-stimulatory genes polymorphisms in an admixed Brazilian population. A total of 273 individuals from the north of Brazil participated in this study. Nine single nucleotide polymorphisms in 7 genes (CD28, CTLA4, ICOS, CD86, CD40, CD40L and BLYS) were determined by polymerase chain reaction-restriction fragment length polymorphism. We also investigated 48 insertion/deletion ancestry markers to characterize individual African, European and Amerindian ancestry proportions in the samples. The analysis showed that the main contribution was European (43.9%) but also a significant contribution of African (31.6%) and Amerindian (24.5%) ancestry. ICOS, CD40L and CD86 polymorphisms were associated with genomic ancestry. However there were no significant differences in the proportions of ancestry for the other SNPs and haplotypes studied. Our findings reinforce the need to apply AIMs in genetic association studies involving these polymorphisms in the Brazilian population.

Synergistic combined effect between CD40-1C>T and CTLA-4+6230G>A polymorphisms in Graves' disease

The aim of this study was to investigate whether a genetic combined effect exists between CD40-1C>T and CTLA-4+6230G>A (CT60) polymorphisms and whether the combined effect renders susceptibility to Graves' disease (GD). We recruited 260 patients with GD and 248 healthy controls. Single nucleotide polymorphisms were genotyped by polymerase chain reaction-high resolution melting. Genetic polymorphisms related to GD were identified, levels of thyroid stimulating hormone receptor antibodies (TRAb) were measured, and genetic interactions were assessed by logistic regression analysis. Significant difference in allele and genotype frequency of CD40-1C>T polymorphism was observed between the patients and control subjects (P<0.001, 0.002 respectively). As for CTLA-4+6230G>A polymorphism, significant difference was observed only in allele frequencies between the patient and control groups (P=0.014). Moreover, a significant combined effect was presented in CD40-1C>T and CTLA-4+6230G>A polymorphism (P=0.020), and all, but one, combination CC-genotype of CD40-1C>T and GG-genotype of CTLA-4+6230G>A polymorphism has 54% lower risk of GD development than subjects with the CC and GG genotypes (OR=0.46, 95% CI=0.25-0.84). In newly onset GD group, neither single SNP (CD40-1C>T or CTLA-4+6230G>A polymorphism) nor their combined effect was showed a significant association with TRAb concentration (all P>0.05). Our findings suggest a possible additive combined effect between CD40-1C>T and CTLA4+6230G>A polymorphisms in the development of GD.

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.

Cytotoxic T-lymphocyte associated antigen 4 polymorphism and Hashimoto's thyroiditis susceptibility: a meta-analysis

The association between cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) exon-1 +49 A/G polymorphism and Hashimoto's thyroiditis (HT) has been widely studied. The results, however, are mixed. This study provides a comprehensive evaluation of the relationship between the genetic risks of CTLA-4 +49 A/G polymorphism and HT. A meta-analysis was conducted in over 4,600 subjects included in 18 case-control studies that were published up to November 15th, 2012. Our meta-analysis indicated that the CTLA-4 genotype was associated with the risk of HT in the allele comparison, homozygote comparison, heterozygote comparison, the dominant genetic model and the recessive genetic model. In the dominant genetic model, variant G allele carriers (GG + GA) of CTLA-4 +49 A/G polymorphism increased the risk of HT comparing to the homozygote AA [odds ratio (OR) = 1.70, 95% confidence interval (CI) 1.37-2.12 for GG + AG vs. AA]. The analysis by ethnicity groups suggested that Asian population (OR = 2.13, 95% CI 1.48-3.07 for GG + AG vs. AA) and Caucasian population (OR = 1.47, 95% CI 1.13-1.91 for GG + AG vs. AA) had significant increased HT risks. The association remained significant after adjusting for publication bias using the trim and fill method. Sensitivity analysis showed that the results were less stable, suggesting that these results should be explained with caution. In summary, this meta-analysis suggested that CTLA-4 +49 A/G polymorphism may be a risk factor for HT.

CTLA-4 CT60 (rs3087243) polymorphism and autoimmune thyroid diseases susceptibility: a comprehensive meta-analysis

OBJECTIVE

To determine whether the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) CT60 polymorphism (rs3087243) confers susceptibility to autoimmune thyroid disease (AITDs).

METHODS

A meta-analysis was performed using: (1) allelic contrast, (2) recessive model and (3) dominant model. Electronic search of PubMed, Medline and Chinese National Knowledge Infrastructure (CNKI) was conducted to select studies.

RESULTS

Finally, a total of 20 separate studies were available for the current meta-analysis: Graves' disease (GD): 18 studies including 1 Iranian, 6 Caucasian and 11 Asian populations; Hashimoto's thyroiditis (HT): seven studies including one Iranian, three Caucasian and three Asian populations. A significant association was found between the CTLA-4 CT60 polymorphism (rs3087243) and GD, with regard to comparisons between allele and genotype frequencies (all p < 0.001). After stratification by ethnicity, significant relationships were consistently identified both in Caucasian and Asian populations. Furthermore, the association between this allelic variant and HT risk was also found in overall and Asian populations (OR: 1.26, 95% CI: 1.10-1.44; OR: 1.45, 95% CI: 1.19-1.76, respectively).

CONCLUSION

Taken together, our study suggested that the CT60 polymorphism (rs3087243) in CTLA-4 gene might confer susceptibility to the AITDs (GD/HT).

CTLA-4 and autoimmunity: new insights into the dual regulator of tolerance

Cytotoxic T-Lymphocye Antigen 4 (CTLA-4) or CD152 is an inhibitory molecule that plays a critical role in maintenance of tolerance to self-antigens. CTLA-4 is structurally as well as functionally related to CD28, since it shares 31% of homology and binds the B7 family molecules CD80 and CD86 with higher affinity. Nevertheless, CTLA-4 has opposing effects on T cell activation and current evidence shows that its inhibitory role goes beyond the ligand-binding interaction. CTLA-4 competes with CD28 in binding to B7, interacts within the immunological synapsis elements and with clathrin adaptor proteins and tyrosine phosphatases through its cytoplasmic domain to regulate cell trafficking and to set the activation threshold within T cells. Moreover, we have learned from the knock out model that CTLA-4 plays a key role in regulatory T cells and in central tolerance. Because of its importance in maintenance of peripheral tolerance, CTLA-4 has been implicated in several autoimmune diseases, such as systemic lupus erythematosus. Multiple single-nucleotide polymorphisms have been located to human Ctla-4 gene, and their association with autoimmune disease is still a matter of controversy. Despite the promising results of abatacept or CTLA-4-Ig in rheumatoid arthritis and murine lupus nephritis, more clinical randomized trials and standardization of outcomes are needed to prove its efficacy and safety in human lupus nephritis.