Exon-1 polymorphism of ctla-4 gene is not associated with systemic sclerosis in Iranian patients

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.

The CTLA-4 and MCP-1 polymorphisms and susceptibility to systemic sclerosis: a meta-analysis

OBJECTIVE

The aim of this study was to explore whether cytotoxic T lymphocyte antigen-4 (CTLA-4) and monocyte chemoattractant protein-1 (MCP-1) polymorphisms confer susceptibility to systemic sclerosis (SSc).

METHODS

MEDLINE and manual search were utilized to identify available articles. A meta-analysis was conducted on the associations between the CTLA-4 +49 A/G, -318 C/T, -1661 A/G, and -1722 C/T, and MCP-1 -2518 A/G polymorphisms, using a fixed-effect or random-effect model based on between-study heterogeneity.

RESULTS

Eleven comparative studies involving 959 SSc patients and 1739 controls were included in the meta-analysis. No association was found between SSc and the CTLA-4 +49 A/G polymorphism (OR for the +49 G allele = 1.032, 95% CI = 0.830-1.283, p = 0.779). However, an association between SSc and the CTLA-4 -318 TT + TC genotype (OR = 1.642, 95% CI = 1.034-2.609, p = 0.036). Meta-analyses failed to reveal an association between SSc and CTLA-4 -1722 C/T, MCP-1 -2518 A/G polymorphisms.

CONCLUSIONS

This meta-analysis of published data shows that the CTLA-4 -318 C/T polymorphism confers susceptibility to SSc.

Elevated levels of CD4(+)CD25(+)FoxP3(+) T cells in systemic sclerosis patients contribute to the secretion of IL-17 and immunosuppression dysfunction

OBJECTIVE

Immune imbalance between regulatory T (Treg) and Th17 cells is a characteristic of systemic sclerosis (SSc). The functional heterogeneity among Treg can be elucidated by separating Treg into different subsets based on the expression of FoxP3 and CD45RA. The aim of this study was to investigate the role of Treg subsets in the immune imbalance in naïve SSc.

METHODS

Peripheral blood mononuclear cells (PBMCs) of 31 SSc patients and 33 healthy controls were analyzed for the expression of CD4, CD25, CD45RA, CTLA-4, FoxP3, and IL-17 using flow cytometry. Treg immunesuppression capacity was measured in co-culture experiments. The expression of FoxP3, CTLA-4, IL-17A, and RORC mRNA was measured by real-time PCR.

RESULTS

The frequency of CD4(+)CD25(+)FoxP3(+) Treg cells was significantly elevated in patients with SSc (3.62±1.14 vs 1.97±0.75, p<0.001) with diminished immunosuppression capacity. In SSc, the proportion of FoxP3(high)CD45RA(-) activated Treg cells (aTreg) was decreased, the proportion of FoxP3(low)CD45RA(-) T cells was increased, and the proportion of FoxP3(low)CD45RA(+) resting Treg cells (rTreg) was decreased. The immune suppression capacity of aTreg and rTreg was diminished, while FoxP3(low)CD45RA(-) T cells exhibited a lack of suppression capacity. The immune dysfunction of aTreg was accompanied by the abnormal expression of CTLA-4. Th17 cell numbers were elevated in SSc, FoxP3(low)CD45RA(-) T cells produced IL-17, confirming their Th17 potential, which was consistent with the elevated levels of FoxP3(+)IL-17(+) cells in SSc.

CONCLUSION

A decrease in aTreg levels, along with functional deficiency, and an increase in the proportion of FoxP3(low)CD45RA(-) T cells, was the reason for the increase in dysfunctional Treg in SSc patients, potentially causing the immune imbalance between Treg and Th17 cells.

A meta-analysis of the association between cytokine gene polymorphisms and systemic sclerosis

We conducted a comprehensive meta-analysis to quantitatively evaluate the association of cytokine gene polymorphisms with systemic sclerosis (SSc) susceptibility. Electronic databases were used to identify published studies before July 2011. In total, 23 case-control studies including 3524 SSc cases and 6086 healthy controls were included in the meta-analysis. We examined the relationship between five gene polymorphisms [cytotoxic T lymphocyte associated antigen 4 (CTLA-4) -1722T/C, CTLA-4 -318C/T, CTLA-4 +49A/G, angiotensin-converting enzyme I/D, STAT-4 rs7574865] and susceptibility to SSc. The combined odds ratio (OR) with 95% confidence interval (95% CI) was calculated to estimate the strength of the association in a fixed or random effect model. Heterogeneity and publication bias were also assessed. We found a significant association between SSc and STAT rs7574865 (TT vs. GG: OR 0.44, 95% CI 0.36-0.54; TT vs. TG + GG: OR 0.48, 95% CI 0.39-0.59; TT + TG vs. GG: OR 0.74, 95% CI 0.66-0.83; T vs. G: OR 0.72, 95% CI 0.66-0.79), but there were no other statistically significant associations with other gene polymorphisms. Our study suggested that SSc is associated with STAT gene rs7574865 polymorphism.

Association of -318 C/T and +49 A/G cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms with a clinical subset of Italian patients with systemic sclerosis

Systemic sclerosis (SSc) is a complex and heterogeneous autoimmune disorder with a multi-factorial pathogenesis. Like other autoimmune disorders, the possible role of specific cytotoxic T lymphocyte antigen-4 (CTLA-4) gene polymorphisms in predisposing to SSc has been hypothesized, but it remains controversial. CTLA-4 promoter (-318C/T) and exon 1 (+49 A/G) polymorphisms have been analysed in 43 Italian females with SSc and in 93 unrelated matched healthy controls by a newly designed tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) method. No significant association has been found with either polymorphisms.Nevertheless, SSc patients without concomitant Hashimoto's thyroiditis (HT) were carrying both the -318T allele (P = 0.031) and the +49 G allele (P = 0.076) more frequently than SSc patients with HT [defined by positivity for anti-thyroperoxidase (TPO) and anti-thyroglobulin (TGA) autoantibodies] than controls. Haplotype analysis confirms this association (P = 0.028), and suggests the predominant role of the -318T, whereas that of the +49 G, if any, seems weak. Thus, in Italian SSc patients the CTLA-4 -318C/T promoter polymorphism appears to be associated with the susceptibility to develop SSc without thyroid involvement. Larger studies are needed to confirm these findings and to clarify whether the -318C/T polymorphism is the functional responsible or whether it reflects the presence of another linked genetic element in the same chromosomal region.