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

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.

Genetic Polymorphisms in Follicular Helper T Cell-Related Molecules Predispose Patients to De Novo Donor-Specific Antibody Formation After Kidney Transplantation

BACKGROUND

Risk prediction of de novo donor-specific antibody (dnDSA) formation is crucial for understanding the long-term prognostic impact of kidney transplantation (KT). Recently, follicular helper T (Tfh) cells, a subtype of CD4⁺ T cells, have been reported to play an important role in dnDSA formation after solid organ transplantation. Given the growing recognition of the importance of Tfh cells in generating a strong humoral immune response, we examined whether polymorphisms in Tfh cell-related molecules were associated with dnDSA formation after KT.

METHODS

Eighty-three patients who underwent living-donor KT between January 2013 and February 2020 at Hiroshima University Hospital were included in the study. Six Tfh cell-related molecules (BCL6, CXCR5, CXCL13, ICOS, CD40L, and IL21) that are important for Tfh cell differentiation and maturation in secondary lymphoid tissues were investigated. CTLA4, which is important for Tfh-cell activation, was also investigated. Single nucleotide polymorphisms (SNPs) in the genes for these molecules were detected using Taq Man SNP genotyping and evaluated for their association with dnDSA formation after KT.

RESULTS

Of the 83 KT recipients, 8 developed dnDSAs during the observation period. No statistically significant differences were observed in the baseline characteristics between patients with and without dnDSA formation, except for donor age. Among the 7 Tfh cell-related molecules, the incidence of dnDSA formation was associated with CXCR5 and CTLA4 SNPs. Furthermore, combining these 2 SNPs enabled more significant stratification of dnDSA formation.

CONCLUSION

Our findings indicate that genetic polymorphisms in Tfh cell-related molecules are predisposing factors for dnDSA formation after KT.

Polymorphisms in CTLA-4 predict de novo donor specific antibody formation after kidney transplantation

The post-transplant development of donor-specific antibodies (DSAs) initiates the antibody-mediated rejection, which is associated with an increased rate of graft loss. Therefore, risk prediction of de novo DSA (dnDSA) is important for understanding long-term prognostic implications for kidney transplantation outcomes. Cytotoxic T lymphocyte antigen-4 (CTLA-4), a cell surface molecule, suppresses T cell responses. Single-nucleotide polymorphisms (SNPs) in CTLA-4 are known to be associated with acute rejection; however, their association with dnDSA formation is not established. In the present study, we investigated the impact of CTLA-4 SNPs on dnDSA formation after kidney transplantation (KT) by analyzing three CTLA-4 SNPs (rs231775, rs3087243, and rs5742909) in 88 recipients. Patients with the GG genotype of CTLA-4 SNPs rs231775 and rs3087243 had higher rates of dnDSA formation than patients with the AA genotype or heterozygous genotypes. In conclusion, our findings indicate that CTLA-4 SNPs are predisposing factors for dnDSA formation after KT.

The Role of CTLA4 and Its Polymorphisms in Solid Organ and Haematopoietic Stem Cell Transplantation

HLA matching, transplantation technique, or underlying disease greatly influences the probability of long-term transplantation success. It has been hypothesised that genetic variation affecting antigen presentation also contributes to the outcomes of both solid organ transplantation and allogeneic haematopoietic stem cell transplantation (AHSCT). Those genes, along with those responsible for innate and adaptive immunity, have become targets of investigation. In this review, we focus on the role of CTLA4 in the process of acute graft rejection and summarise the progress in our understanding of its role in predicting the outcome. We present the results of the latest studies investigating the link between CTLA4 gene variability and AHSCT, as well as organ transplantation outcomes. While some studies found a link between +49 A/G and −318 C/T and transplantation outcomes, comprehensive meta-analyses have failed to present any association. The most recent field reviews suggest that the −1772 T/C (rs733618) CC genotype is weakly associated with a lower risk of acute graft rejection, while +49 A/G might be clinically meaningful when investigated in the context of combinations with other polymorphisms. Studies verifying associations between 12 CTLA4 gene SNPs and AHSCT outcomes present inexplicit results. Some of the most commonly studied polymorphisms in this context include +49 A/G (rs231775) and CT60 A/G (rs3087243). The results signify that, in order to understand the role of CTLA4 and its gene polymorphisms in transplantology, further studies must be conducted.

Genetic Susceptibility to Joint Occurrence of Polycystic Ovary Syndrome and Hashimoto's Thyroiditis: How Far Is Our Understanding?

Polycystic ovary syndrome (PCOS) and Hashimoto’s thyroiditis (HT) are endocrine disorders that commonly occur among young women. A higher prevalence of HT in women with PCOS, relative to healthy individuals, is observed consistently. Combined occurrence of both diseases is associated with a higher risk of severe metabolic and reproductive complications. Genetic factors strongly impact the pathogenesis of both PCOS and HT and several susceptibility loci associated with a higher risk of both disorders have been identified. Furthermore, some candidate gene polymorphisms are thought to be functionally relevant; however, few genetic variants are proposed to be causally associated with the incidence of both disorders together.

CTLA-4 rs231775 and risk of acute renal graft rejection: an updated meta-analysis with trial sequential analysis

Contrasting results exist on the association between CTLA-4 rs231775 and acute rejection in kidney transplant recipients. We herein conducted an updated systematic review with meta-analysis and trial sequential analysis (TSA) to clarify this relationship and to establish whether the current evidence is sufficient to draw firm conclusions. In addition, noteworthiness of significant pooled odds ratios (ORs) was estimated by false positive report probability (FPRP). A comprehensive search was performed through PubMed, Web of Knowledge, Cochrane Library and Open Grey up to October 2019. Fifteen independent cohorts, including a total of 5,401 kidney transplant recipients, were identified through the systematic review. Overall, no association was detected with the allelic (OR 1.07, 95% CI 0.88-1.30, P = 0.49), dominant (OR 0.94, 95% CI 0.73-1.22, P = 0.66) or the recessive (OR 1.18, 95% CI 0.97-1.43, P = 0.096) model of CTLA-4 rs231775. In each genetic model, the cumulative Z-curve in TSA crossed the futility boundary and entered the futility area. In addition, none of the significant genetic comparisons detected in the subsequent and sensitivity analyses or in previously reported meta-analyses were found to be noteworthy by FPRP. In conclusion, this study provides strong evidence that CTLA-4 rs231775 is not a clinically-relevant genetic risk determinant of acute rejection after renal transplantation.

Association and gene-gene interaction analyses for polymorphic variants in CTLA-4 and FOXP3 genes: role in susceptibility to autoimmune thyroid disease

PURPOSE

Polymorphic variants of cytotoxic T-lymphocyte antigen-4 (CTLA-4) and forkhead box protein P3 (FOXP3) genes are implicated in dysregulated immune homeostasis and autoimmune disorders. We analyzed the association between CTLA-4 rs231775 and FOXP3 rs3761548, rs3761549 polymorphisms and predisposition to autoimmune thyroid disease (AITD), inclusive of Hashimoto's thyroiditis (HT) and Graves' disease (GD) in South-Indian population.

METHODS

A total of 355 AITD subjects (comprising 275 HT and 80 GD) and 285 randomly selected age- and sex-matched control subjects were genotyped for the aforementioned polymorphisms by PCR-RFLP method.

RESULTS

The rs231775 "G" allele was preponderant in HT and GD subjects when compared with controls and exerted a dominant influence on the susceptibility to HT (p = 0.009) and GD (p = 0.02), respectively. There was no allelic association of rs3761548 and rs3761549 polymorphisms with AITD susceptibility, albeit a significant difference in genotype distribution with respect to rs3761549. Haplotype analysis revealed an increased frequency of rs3761548 "C"-rs3761549 "T" in HT and GD subjects, thereby associating it with disease predisposition (p = 0.03). Epistatic interaction analysis by multifactor dimensionality reduction approach revealed redundancy between CTLA-4 and FOXP3 genes in influencing the susceptibility to AITD.

CONCLUSIONS

The genetic variation in CTLA-4 gene with reference to rs231775 polymorphism contributes to an increased predisposition to HT and GD. Also, in conjunction with FOXP3 gene variants it seems to influence the susceptibility to HT and GD respectively. The significance of these findings in combination with antithyroid antibody screening could plausibly contribute towards meticulous case-finding for effective treatment of HT and GD.

Association of CTLA-4 gene polymorphisms -318C/T and +49A/G and Hashimoto's thyroidits in Zahedan, Iran

Hashimoto's thyroiditis (HT) is a chronic inflammation of the thyroid gland and is known as the most common autoimmune disease. Development of autoimmune destruction of thyroid cells is a multi-step process involving convergence of genetic and environmental factors. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) has an important role in homeostasis and negative regulation of immune responses, and is therefore considered to be a key element in the development of autoimmune diseases. The present study evaluated the association of the CTLA-4 gene polymorphisms 318C/T (rs5742909) and +49A/G (rs231775) with HT in an Iranian population (including 82 patients with HT and 104 healthy controls who were referred for routine premarital blood screenings). Genotyping was performed using the tetra-primer amplification refractory mutation system polymerase chain reaction technique. No significant differences were observed in genotype and allele frequencies in the single nucleotide polymorphisms (SNPs) between cases and controls. In the cases as well as in the controls, the TT genotype in the -318C/T polymorphism was absent and the predominant genotype was CC, while the predominant genotype for the +49A/G SNP was AA. As only few studies in this field have assessed Iranian and even Middle Eastern populations, additional studies with a higher number of samples are recommended to further assess the impact of -318C/T (rs5742909) and +49A/G (rs231775) polymorphisms of CTLA-4 on HT.

Investigation of Cytotoxic T-lymphocyte antigen 4 Polymorphisms in Gastric Cardia Adenocarcinoma

To assess the potential effects of Cytotoxic T-lymphocyte antigen 4 (CTLA4) gene polymorphisms on susceptibility to gastric cardia adenocarcinoma (GCA), we genotyped four polymorphisms (rs733618 A>G, rs16840252 C>T, rs231775 G>A and rs3087243 G>A) in CTLA4 and calculated odds ratios (ORs) with the corresponding 95% confidence intervals (95% CIs) for the genotype and allele distributions between GCA cases and controls. The CTLA4 genotypes were determined by the polymerase chain reaction-ligase detection reaction (PCR-LDR) analysis in 330 GCA patients and 608 unrelated cancer-free controls. In this case-control study, there was no significant difference in the genotype and allele distributions of four CTLA4 polymorphisms between GCA patients and controls. However, haplotype association analysis indicated that compared with CTLA4 Grs733618 Crs16840252 Grs231775 Crs3087243 , CTLA4 Grs733618 Crs16840252 Ars231775 Grs3087243 and Ars733618 Crs16840252 Grs231775 Ars3087243 haplotypes conferred increased risks of GCA (OR = 6.46, 95% CI = 1.33-31.28; P = 0.012; both); however, CTLA4 Ars733618 Crs16840252 Ars231775 Grs3087243 and Ars733618 Trs16840252 Grs231775 Grs3087243 haplotypes conferred decreased risks of GCA (P = 0.001 and P = 0.011, respectively). These results highlight that the rare CTLA4 haplotypes may affect the development of GCA in the Chinese population.

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.

The possible role of CD4⁺CD25(high)Foxp3⁺/CD4⁺IL-17A⁺ cell imbalance in the autoimmunity of patients with Hashimoto thyroiditis

Hashimoto thyroiditis (HT) is a prototypic organ-specific autoimmune thyroid disease, for which the exact etiology remains unclear. The aim of this study was to investigate dynamic changes in regulatory T cell (Treg) and T helper 17 cell (Th17) populations in patients with HT at different stages of thyroid dysfunction, as well as to analyze the possible correlation between the Treg/Th17 cell axis and autoimmune status in HT. We assessed thyroid function and autoantibody serology both in HT patients and in healthy controls (HCs) and divided HT patients into three subgroups according to thyroid function. We then determined the percentages of Treg and Th17 cells in peripheral blood mononuclear cells and analyzed mRNA expression of the Treg and Th17 cell-defining transcription factors Foxp3 and RORγt. In addition, serum levels of TGF-β and IL-17A were assessed. We found that the percentage of Treg cells, Foxp3 mRNA levels, and the ratio of Treg/Th17 cells were all significantly lower in HT patients, while Th17 cell percentages and RORγt mRNA levels were significantly higher. Interestingly, we also observed significant differences in these measurements between HT patient subgroups. Serum IL-17A levels were markedly increased in HT patients, while serum concentrations of TGF-β were lower, compared to HCs. The ratio of Treg/Th17 cells was negatively correlated with the levels of serum thyroperoxidase antibody, thyroglobulin antibody, and thyrotropin (TSH) in HT patients. Taken together, our data suggest that the balance between Treg and Th17 cells shifts in favor of Th17 cells during clinical progression of HT, which is negatively correlated with levels of thyroid-specific autoantibodies and TSH, implying that Treg/Th17 cell imbalance may contribute to thyroid damage in HT.

Association between CTLA-4 genetic polymorphisms and susceptibility to osteosarcoma in Chinese Han population

Osteosarcoma (OS) is the most common malignant primary bone tumor in the world. The cytotoxic T-lymphocyte antigen-4 gene (CTLA-4) is an important candidate gene for influencing the development of OS. This study aimed to investigate the potential association of CTLA-4 genetic polymorphisms with OS risk in Chinese Han population. A total of 415 OS patients and 431 healthy controls were enrolled in this study. The created restriction site-polymerase chain reaction (CRS-PCR) and DNA sequencing methods were used to detect the genotyping of CTLA-4 c.75G[C and c.326G[A genetic polymorphisms. We observed that the genotypes/alleles of c.75G[C and c.326G[A genetic polymorphisms were statistically associated with the increased risk of OS (for c.75G[C, CC versus (vs.) GG: OR 1.72, 95% CI 1.09–2.74; C vs. G: OR 1.30, 95% CI 1.06–1.60; for c.326G[A, AA vs. GG: OR 2.12, 95% CI 1.31–3.42; A vs. G: OR 1.31, 95% CI 1.07–1.61). The allele-C/genotype-CC of c.75G[C and allele-A/genotype-AA of c.326G[A may contribute to OS susceptibility. These data indicate that CTLA-4 genetic polymorphisms are potentially related to OS risk in Chinese Han population, and might be used as molecular markers for evaluating the risk of OS.