Replication of the association between the C8orf13–BLK region and systemic lupus erythematosus in a Japanese population

Objective

Recent genome‐wide association studies identified an association between single‐nucleotide polymorphisms (SNPs) in the C8orf13 region of BLK, the B lymphoid tyrosine kinase gene, with systemic lupus erythematosus (SLE) in Caucasians. The purpose of this study was to evaluate the significance of this region in the genetic background of Japanese patients with SLE.

Methods

Fourteen tag SNPs in the C8orf13–BLK region were genotyped in 327 Japanese patients with SLE and 322 healthy Japanese controls. The population‐attributable risk percentage (PAR%) of rs13277113 in Japanese was compared with that in Caucasians as well as with that of other SLE susceptibility genes in Japanese.

Results

As in Caucasians, rs13277113A demonstrated the strongest association in Japanese (P = 1.73 × 10^–6 for the genotype frequency, P = 4.75 × 10^–7 for the allele frequency, odds ratio [OR] 2.44 [95% confidence interval (95% CI) 1.43–4.16]). The association in Japanese was consistent with a recessive model (P = 2.74 × 10^–7, OR 2.27 [95% CI 1.66–3.11]). In contrast to the Caucasian population, this risk allele was the major allele in the Japanese population. Because both the risk allele frequency and the OR were higher in Japanese than in Caucasians, the PAR% of rs13277113 was estimated to be much higher in Japanese (35.4%) than in Caucasians (16.2%), and the second highest among the 6 confirmed SLE susceptibility genes in Japanese.

Conclusion

The association of the C8orf13–BLK region with SLE was replicated in a Japanese population. Contribution of this region to the genetic predisposition to SLE appeared to be greater in Japanese than in Caucasians.

     

BANK1 is a genetic risk factor for diffuse cutaneous systemic sclerosis and has additive effects with IRF5 and STAT4

Objective

To determine whether the functional BANK1 variants rs3733197 and rs10516487 are associated with systemic sclerosis (SSc) in 2 European Caucasian populations and to investigate the putative gene–gene interactions between BANK1 and IRF5 as well as STAT4.

Methods

BANK1 single‐nucleotide polymorphisms were genotyped in a total population of 2,432 individuals. The French cohort consisted of 874 SSc patients and 955 controls (previously genotyped for both IRF5 rs2004640 and STAT4 rs7574865). The German cohort consisted of 421 SSc patients and 182 controls.

Results

The BANK1 variants were found to be associated with diffuse cutaneous SSc (dcSSc) in both cohorts, providing an odds ratio (OR) of 0.77 for the rs10516487 T rare allele in the combined populations of dcSSc patients as compared with the combined populations of controls (95% confidence interval [95% CI] 0.64–0.93) and an OR of 0.73 (95% CI 0.61–0.87) for the rs3733197 A rare allele. BANK1 haplotype analysis found the A‐T haplotype to be protective in dcSSc patients (OR 0.70 [95% CI 0.57–0.86], P = 3.39 × 10⁻⁴) and the G‐C haplotype to be a risk factor (OR 1.25 [95% CI 1.06–1.47], P = 0.008). Significant differences were also observed when the limited cutaneous subset of SSc was compared with the dcSSc subset, both for the rare alleles and for the haplotypes. The BANK1, IRF5, and STAT4 risk alleles displayed a multiplicatively increased risk of dcSSc of 1.43‐fold.

Conclusion

Our results establish BANK1 as a new SSc genetic susceptibility factor and show that BANK1, IRF5, and STAT4 act with additive effects.

     

Interleukin‐13–producing CD8+ T cells mediate dermal fibrosis in patients with systemic sclerosis

Objective

Fibrosis is a major contributor to morbidity and mortality in systemic sclerosis (SSc). T cells are the predominant inflammatory infiltrate in affected tissue and are thought to produce cytokines that drive the synthesis of extracellular matrix (ECM) proteins by fibroblasts, resulting in excessive fibrosis. We have previously shown that aberrant interleukin‐13 (IL‐13) production by peripheral blood effector CD8+ T cells from SSc patients correlates with the extent of skin fibrosis. The present study was undertaken to investigate the role of IL‐13 production by CD8+ T cells in dermal fibrosis, an early and specific manifestation of SSc.

Methods

ECM protein production by normal dermal fibroblasts cocultured with SSc CD8+ T cell supernatants was determined by quantitative polymerase chain reaction and Western blotting. Skin‐homing receptor expression and IL‐13 production by CD8+ T cells in the peripheral blood of SSc patients were measured by flow cytometry. IL‐13+ and CD8+ cells in sclerotic skin were identified by immunohistochemistry.

Results

IL‐13–producing circulating CD8+ T cells from patients with SSc expressed skin‐homing receptors and induced a profibrotic phenotype in normal dermal fibroblasts, which was inhibited by an anti–IL‐13 antibody. High numbers of CD8+ T cells and IL‐13+ cells were found in the skin lesions of SSc patients, particularly during the early inflammatory phase of the disease.

Conclusion

These findings show that IL‐13–producing CD8+ T cells are directly involved in modulating dermal fibrosis in SSc. The demonstration that CD8+ T cells homing to the skin early in the course of SSc are associated with accumulation of IL‐13 is an important mechanistic contribution to the understanding of the pathogenesis of dermal fibrosis in SSc and may represent a potential target for therapeutic intervention.

     

STAT4 is a genetic risk factor for systemic sclerosis having additive effects with IRF5 on disease susceptibility and related pulmonary fibrosis

Objective

Systemic sclerosis (SSc) belongs to the group of connective tissue disorders (CTDs), among which are several disorders characterized by a type I interferon (IFN) signature. The recent identification of an association between IRF5 and SSc further highlights a key role for IFN. STAT4, which encodes STAT‐4, contributes to IFN signaling, and its genetic variants were found to be associated with CTDs. The aim of this study was to determine whether the STAT4 rs7574865 single‐nucleotide polymorphism is associated with SSc, and whether it interacts with IRF5.

Methods

Both the STAT4 rs7574865 and IRF5 rs2004640 polymorphisms were genotyped in 1,855 individuals of French Caucasian origin comprising a discovery set of 440 patients with SSc and 485 control subjects and a replication set of 445 patients with SSc and an additional 485 control subjects.

Results

STAT4 rs7574865 was shown to be associated with SSc (P = 0.001, odds ratio [OR] 1.29, 95% confidence interval [95% CI] 1.11–1.51). This association was not restricted to a particular phenotype. An additive effect of the STAT4 rs7574865 T allele and the IRF5 rs2004640 T allele was observed, resulting in a multiplicatively increased 1.28‐fold risk of SSc. The OR for SSc was 2.72 (95% CI 1.86–3.99) for combinations of genotypes with ≥3 risk alleles. An additive effect was also detected for fibrosing alveolitis: carriage of at least 3 risk alleles appeared to be an independent risk factor (P = 2.2 × 10⁻⁴, OR 1.97, 95% CI 1.28–3.04).

Conclusion

Our results establish STAT4 rs7574865 as a new SSc genetic susceptibility factor. STAT4 and IRF5 act with additive effects in terms of susceptibility to both SSc and SSc‐related fibrosing alveolitis.

     

Relationship between IL‐10 gene −1082A/G and −592C/A polymorphisms and the risk of hepatitis C infection: a meta‐analysis

Increasing evidence suggests that interleukin‐10 (IL‐10) gene promoter polymorphisms may be associated with chronic hepatitis C virus (HCV) infection and HCV clearance. To more precisely estimate the association between these variants and the risk of HCV infection, we performed a meta‐analysis of 26 studies describing the IL‐10–1082A/G, –819C/T, –592C/A genotypes, including 4039 chronic HCV infection cases and 2902 controls. When compared with a healthy population, the –1082GG allele had a 43% increased risk of chronic HCV infection in combined populations (GG vs GA + AA: odds ratio (OR) = 1.433, 95% confidence interval (CI) = 1.052–1.952, P = 0.023). In subgroup analysis by ethnicity, a significant increased risk was associated with the ?1082GG genotype in the Caucasian population (GG vs AA: OR = 1.390, 95% CI: 1.108–1.744, P = 0.004; GG vs GA + AA: OR = 1.621, 95% CI: 1.267–2.075, P = 0.000). However, no significant association was found in Asian, African or Chinese populations. Moreover, a higher distribution of ?592A was found in the spontaneously recovered population (AA vs CC: OR = 0.585, 95% CI = 0.387–0.884, P = 0.011; AA + AC vs CC: OR = 0.738, 95% CI = 0.551–0.988, P = 0.041; AA vs AC + CC: OR = 0.788, 95% CI = 0.664–0.935, P = 0.006) than that in the chronic HCV infection population. In conclusion, the IL‐10–1082GG allele may increase the risk of chronic HCV infection in Caucasian population, and people carrying the IL‐10–592A allele are more likely to clear HCV spontaneously.     

Chronic hepatitis C virus infection is associated with increased risk of preterm birth: a meta‐analysis of observational studies

Although several epidemiological studies reported that maternal chronic hepatitis C virus (HCV) infection had significantly increased risk of undergoing adverse obstetrical and perinatal outcomes, studies on the relationship between HCV infection and risk of preterm birth (PTB) have yielded inconclusive and inconsistent results. Therefore, we conducted a meta‐analysis to investigate the association between HCV infection and PTB. The electronic database was searched until 1 September 2014. Relevant studies reporting the association between HCV infection and the risk of PTB were included for further evaluation. Statistical analysis was performed using revmen 5.3 and stata 10.0. Nine studies involving 4186698 participants and 5218 HCV infection cases were included. A significant association between HCV infection and PTB was observed (odds ratio = 1.62, 95% CI 1.48–1.76, P < 0.001, fixed‐effects model). Stratification according to maternal smoking/alcohol abuse, maternal drug abuse or coinfected with HBV and/or HIV matched groups still demonstrated that women with HCV infection had a high risk for PTB. Findings from our meta‐analysis suggested that maternal HCV infection was significantly associated with an increased risk of PTB. In the future, pathophysiological studies are warranted to ascertain the causality and explore the possible biological mechanisms involved.     

JAK‐2 as a novel mediator of the profibrotic effects of transforming growth factor β in systemic sclerosis

Objective

To investigate whether JAK‐2 contributes to the pathologic activation of fibroblasts in patients with systemic sclerosis (SSc) and to evaluate the antifibrotic potential of JAK‐2 inhibition for the treatment of SSc.

Methods

Activation of JAK‐2 in human skin and in experimental fibrosis was determined by immunohistochemical analysis. JAK‐2 signaling was inhibited by the selective JAK‐2 inhibitor TG101209 or by small interfering RNA. Bleomycin‐induced dermal fibrosis in mice and TSK‐1 mice were used to evaluate the antifibrotic potential of specific JAK‐2 inhibition in vivo.

Results

Increased activation of JAK‐2 was detected in the skin of patients with SSc, particularly in fibroblasts. The activation of JAK‐2 was dependent on transforming growth factor β (TGFβ) and persisted in cultured SSc fibroblasts. Inhibition of JAK‐2 reduced basal collagen synthesis selectively in SSc fibroblasts but not in resting healthy dermal fibroblasts. Moreover, inhibition of JAK‐2 prevented the stimulatory effects of TGFβ on fibroblasts. Treatment with TG101209 not only prevented bleomycin‐induced fibrosis but also effectively reduced skin fibrosis in TSK‐1 mice.

Conclusion

We demonstrated that JAK‐2 is activated in a TGFβ‐dependent manner in SSc. Considering the potent antifibrotic effects of JAK‐2 inhibition, our study might have direct translational implications, because inhibitors of JAK‐2 are currently being evaluated in clinical trials for myeloproliferative disorders and would also be available for evaluation in patients with SSc.

     

Hormonal and reproductive risk factors for development of systemic lupus erythematosus: Results of a population‐based,case–control study

Objective

Estrogen and prolactin may accelerate the progression of murine systemic lupus erythematosus (SLE). In humans, 85% of lupus patients are women, which also suggests the importance of hormonal factors in disease pathogenesis. The purpose of this study was to examine hormonal and reproductive risk factors for lupus among women.

Methods

This population‐based, case–control study included 240 female SLE patients diagnosed between January 1, 1995 and July 31, 1999 who fulfilled the American College of Rheumatology classification criteria. Female controls (n = 321) were identified through driver's license records. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) as measures of association, adjusting for age, state, race, and education. Analyses were limited to exposures before diagnosis.

Results

Breast‐feeding was associated with a decreased risk of developing SLE (OR 0.6, 95% CI 0.4–0.9), with a statistically significant trend for number of babies breast‐fed and total weeks of breast‐feeding. There were no associations with number of pregnancies or live births. Natural menopause occurred earlier in women with subsequent development of SLE compared with controls (P < 0.001). There was little association between SLE and current use or duration of use of hormone replacement therapy or oral contraceptives, and no association with previous use of fertility drugs.

Conclusion

We found little evidence that estrogen‐ or prolactin‐related exposures are associated with an increased risk of lupus. The reduced risk observed among women who had breast‐fed one or more babies should be examined in other studies. Early natural menopause, rather than decreasing risk of SLE because of reduced estrogen exposure, may be a marker of susceptibility to development of SLE.

     

N‐terminal pro–brain natriuretic peptide as a diagnostic marker of early pulmonary artery hypertension in patients with systemic sclerosis and effects of calcium‐channel blockers

Objective

To evaluate N‐terminal pro–brain natriuretic peptide (NT‐proBNP) as a marker of early pulmonary artery hypertension (PAH) and to study changes in the levels of this marker following treatment with dihydropyridine‐type calcium‐channel blocker (DTCCB) in patients with systemic sclerosis (SSc).

Methods

We evaluated 40 consecutive SSc patients who had been hospitalized for followup care (mean ± SD age 56 ± 11 years and mean ± SD duration of cutaneous disease 9 ± 9 years; 27 with limited cutaneous and 13 with diffuse cutaneous disease) but who had no clinical symptoms of heart failure and had a normal left ventricular ejection fraction. At baseline, 10 patients had PAH, defined as a systolic pulmonary artery pressure (sPAP) >40 mm Hg, as measured by echocardiography. Levels of NT‐proBNP were determined at baseline (after discontinuation of DTCCB treatment for 72 hours), after taking 3 doses of DTCCB following treatment reinitiation (assessment 1), and after 6–9 months of continuous DTCCB treatment (assessment 2) in the 20 patients who attended regular appointments (including the 10 patients with PAH at baseline).

Results

At baseline, 13 patients had high NT‐proBNP values for their ages. High NT‐proBNP levels identified patients with PAH with a sensitivity of 90%, a specificity of 90.3%, a positive predictive value of 69.2%, and a negative predictive value of 96%. The NT‐proBNP level correlated with the sPAP (r = 0.44; P = 0.006). By assessment 1, the number of patients with PAH and high levels of NT‐proBNP had decreased from 9 of 10 to 2 of 10 (P = 0.02). This decrease was partially sustained at assessment 2 (4 of 10 patients; P = 0.06).

Conclusion

NT‐proBNP is a useful biologic marker that can be used to diagnose early PAH in SSc patients without clinical heart failure. Measurement of NT‐proBNP may be valuable for the evaluation of treatment with DTCCB and vasodilators in patients with PAH.

     

Tumor necrosis factor promoter polymorphism TNF*‐857 is a risk allele for psoriatic arthritis independent of the PSORS1 locus

Objective

The strongest susceptibility locus of psoriatic arthritis (PsA) is within the major histocompatibility complex (MHC) region (psoriasis susceptibility region 1, or PSORS1), and HLA–Cw*06:02 has been reported as the PSORS1 susceptibility allele. Non‐HLA genes within the MHC region have also been implicated in PsA, but because of the strong linkage disequilibrium at chromosome 6p21, it is difficult to make a distinction between susceptibility alleles and linked markers. Recent studies have demonstrated that the association between PsA and the tumor necrosis factor (TNF) promoter polymorphism TNF*‐857 is independent of PSORS1. The aim of this study was to replicate the independent association of TNF*‐857 in patients with PsA.

Methods

A total of 909 patients with PsA and 1,315 healthy controls originating from the UK, Germany, and Italy were typed for TNF*‐857 and for the estimated risk alleles of HLA–Cw*06:02.

Results

Overall, the results of genotyping in these 3 case–control cohorts replicated the finding that the frequency of carriers of TNF*‐857 TT/CT who were negative for the PSORS1 risk allele was significantly higher among patients with PsA compared with control subjects (30% versus 21%; P = 9.17 × 10⁻⁵).

Conclusion

The results of this collaborative study indicate that TNF*‐857T is a susceptibility allele for PsA independent of the PSORS1 allele.