Yin Su

Genetic association of PRDM1-ATG5 intergenic region and autophagy with systemic lupus erythematosus in a Chinese population

Objective Recent genome-wide association studies suggested the PRDM1-ATG5 gene region as a systemic lupus erythematosus (SLE)-associated locus both in Caucasian and Chinese populations; however, the candidate gene was still obscure and the possible functional significance needed to be determined. Methods In this study, by a multistage integrative strategy, the authors first performed a case–control association study involving 1745 individuals in the Chinese population by genotyping nine single nucleotide polymorphisms within this region, and a meta-analysis was conducted. Correlation between associated genotypes and expression levels of messenger RNA in B-cell lines from 210 unrelated HapMap data was examined, and was validated in vitro. To determine the biological significance, a genetic association study was also checked in a pathway-based manner and the significant associations were validated in a second 844 Chinese cohort. Results A peak of association was found in the intergenic region (p=0.036–3.26×10−4). Meta-analysis consolidated the association between rs548234 and SLE (OR 1.254, p=1.28×10−16). Significant positive correlations with ATG5 expression were identified, suggesting ATG5 as a candidate gene in the region. Epstein–Barr virus B-cell-based downstream gene expression analysis supported a functional effect of rs548234 and rs6937876, and in-vitro experiments confirmed the regulatory effect of rs6937876 in B-cell populations. Finally, an autophagy pathway-based genetic association study identified ATG7 (p=1.12×10−4) and IRGM (p=0.015) as novel candidate genes, and gene–gene interactions were observed between ATG5, ATG7 and IRGM. Conclusion These data may demonstrate that autophagy is involved in the pathogenesis of SLE and imply a common biological pathway in autoimmunity.

Low-dose interleukin-2 treatment selectively modulates CD4 + T cell subsets in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a potentially life-threatening autoimmune disease characterized by altered balance of activity between effector and regulatory CD4+ T cells. The homeostasis of CD4+ T cell subsets is regulated by interleukin (IL)-2, and reduced production of IL-2 by T cells is observed in individuals with SLE. Here we report that treatment with low-dose recombinant human IL-2 selectively modulated the abundance of regulatory T (Treg) cells, follicular helper T (TFH) cells and IL-17-producing helper T (TH17) cells, but not TH1 or TH2 cells, accompanied by marked reductions of disease activity in patients with SLE.

Gene–gene interaction of BLK, TNFSF4, TRAF1, TNFAIP3, and REL in systemic lupus erythematosus

OBJECTIVE Although the number of convincingly established genetic associations with systemic lupus erythematosus (SLE) has increased sharply over the last few years, refinement of these associations is required, and their potential roles in gene-gene interactions need to be further investigated. Recent genome-wide association studies (GWAS) in SLE have produced renewed interest in B cell/T cell responses and the NF-κB signaling pathway. The aim of this study was to search for possible gene-gene interactions based on identified single-nucleotide polymorphisms (SNPs), in using an approach based on the role of signaling pathways. METHODS The SNPs in BLK, TNFSF4, TRAF1, TNFAIP3, and REL were replicated in order to evaluate genetic associations with SLE. TaqMan genotyping was conducted in 804 Chinese patients with SLE and 722 matched control subjects. A multiple logistic regression model was used to estimate the multiplicative interaction effect of the SNPs, and additive interactions were analyzed by 2×2 factorial designs. Data from a previously published GWAS conducted by the International Consortium on the Genetics of Systemic Lupus Erythematosus were derived for comparison and validation. RESULTS Single-marker analysis validated the association of BLK rs2736340 (P=4.25×10(-6)) as well as TNFSF4 rs2205960 (P=2.82×10(-5)) and TNFAIP3 rs5029939 (P=1.92×10(-3)) with SLE susceptibility in Chinese. Multiplicative interaction analysis indicated that BLK had an interactive effect with TNFSF4 in Chinese patients with SLE (P=6.57×10(-4)). Additive interaction analysis revealed interactions between TRAF1 and TNFAIP3 in both Chinese (P=2.18×10(-3)) and Caucasians (P=2.86×10(-4)). In addition, multiple tendencies toward interactions were observed, and an additive effect was observed as the number of risk genotypes increased. CONCLUSION The results of this study provide evidence of the possible gene-gene interactions of BLK, TNFSF4, TRAF1, TNFAIP3, and REL in SLE, which may represent a synergic effect of T cells and B cells through the NF-κB pathway in determining immunologic aberration.

Hypoxia and hypoxia-inducible factor-1α provoke toll-like receptor signalling-induced inflammation in rheumatoid arthritis

Objectives Hyperplasia of synovial fibroblasts, infiltration with lymphocytes and tissue hypoxia are major characteristics of rheumatoid arthritis (RA). Extensive data support a key role for toll-like receptors (TLRs) in RA. Little is known regarding the impact of hypoxia on TLR-induced inflammation in RA. The aim of this study was to reveal the effects of hypoxia and its regulator, hypoxia-inducible factor-1α (HIF-1α), on the inflammatory response of RA synovial fibroblasts (RASF) to TLR ligands. Methods Hypoxia was induced in RASF by incubation with Na2S2O4. TLR3 ligand polyIC, TLR2 ligand peptidoglycan, TLR4 ligand LPS and TLR9 ligand CpG were used to stimulate the cells. Effects of hypoxia on TLR-induced inflammatory mediators were determined by RT-PCR, qPCR and ELISA. Overexpression of HIF-1α as well as knocking-down its expression was used to reveal its fundamental role. RASF-induced inflammatory T cell expansion was determined by flow cytometry analysis of T helper (Th)1/Th17 cells, and IFN-γ/IL-17 production by ELISA after RASF/T cell coculture. Results Hypoxia potentiated the expression of inflammatory cytokines, metalloproteinases and VEGF in RASF stimulated by different TLR ligands, especially polyIC, a synthetic mimic of dsRNA from viruses or apoptotic cells. HIF-1α played a fundamental role in this synergy. Moreover, HIF-1α overexpression enhanced RASF-mediated expansion of inflammatory Th1 and Th17 cells, leading to proinflammatory IFN-γ and IL-17 production. Conclusions Our findings suggest that hypoxia and HIF-1α may function in conjunction with TLR-stimulated innate immune responses to drive inflammation in RA. This pathway may serve as a therapeutic target for the disease.

Anti‐histones antibodies in systemic lupus erythematosus: prevalence and frequency in neuropsychiatric lupus

To investigate the specificity, sensitivity, and concomitant presence of antibodies against histones (H), histone H1 (H1), and histone H3 (H3) in patients with systemic lupus erythematosus (SLE) and analyze their association with SLE. Serum IgG anti‐histones antibodies were detected by enzyme‐linked immunosorbent assay in 144 SLE patients consisting of 24 neuropsychiatric lupus (NPSLE), 65 lupus nephritis (LN), and 55 SLE, 100 other rheumatic diseases patients, as well as 40 healthy controls. Clinical and biological parameters of the patients were also evaluated. Anti‐H, anti‐H1, and anti‐H3 antibodies yielded a sensitivity of approximately 33% and a specificity of more than 93% for SLE, which was comparable to that found for anti‐double‐stranded DNA (anti‐dsDNa) antibodies. More significantly, anti‐histone antibody is found in approximately 50% of patients with NPSLE compared with LN. Moreover, the titers of anti‐histones antibodies of NPSLE patients were significantly higher than that of patients with SLE and LN. The sequential analysis revealed a close correlation of anti‐H and anti‐H1 antibodies with SLE disease activity. There was an approximate 30% positive rate of anti‐histones antibodies in 144 SLE patients lacking anti‐nucleosome, anti‐mDNA, anti‐Sm, and anti‐dsDNA antibodies. Antibodies to histones H1 and H3 are markers with high specificity of 93.6–96.4% for SLE. The anti‐histone antibody markers are prevalent in approximately 50% of NPSLE. Furthermore, there was a strong correlation with SLE disease activity index and levels of antibodies to histones and H1. J. Clin. Lab. Anal. 22:271–277, 2008.

Hypoxia-inducible factor-1α perpetuates synovial fibroblast interactions with T cells and B cells in rheumatoid arthritis.

Synovial fibroblast hyperplasia, T‐cell hyperactivity, B‐cell overactivation, and the self‐perpetuating interactions among these cell types are major characteristics of rheumatoid arthritis (RA). The inflamed joints of RA patients are hypoxic, with upregulated expression of hypoxia‐inducible factor‐1α (HIF‐1α) in RA synovial fibroblasts (RASFs). It remains unknown whether HIF‐1α regulates interactions between RASFs and T cells and B cells. We report here that HIF‐1α promotes the expression of inflammatory cytokines IL‐6, IL‐8, TNF‐α, and IL‐1β, and cell–cell contact mediators IL‐15, vascular cell adhesion molecule (VCAM)‐1, thrombospondin (TSP)‐1, and stromal cell‐derived factor (SDF)‐1 in RASFs. Furthermore, HIF‐1α perpetuates RASF‐mediated inflammatory Th1‐ and Th17‐cell expansion while differentially inhibiting regulatory B10 and innate‐like B cells, leading to increased IFN‐γ, IL‐17, and IgG production and decreased protective natural IgM secretion. Our findings suggest that HIF‐1α perpetuates the interactions between RASFs and T cells and B cells to induce inflammatory cytokine and autoantibody production, thus exacerbating the severity of RA. Targeting HIF‐1α may provide new therapeutic strategies for overcoming this persistent disease.

Different expression patterns and clinical significance of mAxl and sAxl in systemic lupus erythematosus

Axl is one of the TAM family members that downregulates activated immune responses to maintain immune homeostasis. We analyzed the expression and clinical relevance of Axl on the surface of CD14+ monocytes/macrophages (mAxl, membrane Axl) and in the plasma (sAxl, soluble Axl) from patients with systemic lupus erythematosus (SLE). Compared to healthy subjects, the concentrations of sAxl were significantly elevated in plasma from SLE patients, while the mAxl expression on CD14+ monocytes/macrophages from SLE patients was significantly downregulated. A series of severe disease clinical manifestations and laboratory features such as presence of autoantibodies, 24-hour proteinuria excretion or SLEDAI ≥10 were associated with decreased mAxl expression on monocytes/macrophages but elevated sAxl levels in plasma. The plasma level of Gas6, the main ligand of Axl, was slightly decreased in SLE patients, and was negatively correlated with anti-dsDNA antibodies and C-reactive protein. SLE patients with SLEDAI ≥10 showed significantly lower Gas6 levels. Our study suggests that abnormal mAxl and sAxl expression may be involved in the imbalance of immune regulation in SLE.

Societal Costs of Rheumatoid Arthritis in China: A Hospital-Based Cross-Sectional Study

To estimate the annual direct and indirect costs of rheumatoid arthritis (RA) in China and identify the predictors for cost of illness.

Total glucosides of paeony can reduce the hepatotoxicity caused by Methotrexate and Leflunomide combination treatment of active rheumatoid arthritis

OBJECTIVE Total glucosides of paeony (TGP) have been confirmed to exert anti-inflammatory and hepatoprotective effects. Methotrexate (MTX) and Leflunomide (LEF) combination has a better efficacy in the treatment of active rheumatoid arthritis (RA), but hepatotoxicity was observed. In this study, we investigated the effect of TGP on hepatic dysfunction caused by MTX and LEF in patients with active RA. METHODS A total of 268 patients with active RA (disease activity score in 28 joints, DAS28>3.2) were enrolled in this study. All patients were randomly assigned to two groups, the therapeutic group in which patients were treated with TGP (1.8 g/day) combined with MTX and LEF (MTX 10mg/week plus LEF 20mg/day) while in the control group, patients were treated without TGP up to 12 weeks. The efficacy and liver abnormalities were observed. RESULTS The incidence of abnormal liver function within 12 weeks in TGP group was significantly lower than that in control group (11.38% vs 23.26%, P=0.013). The proportion of patients with ALT/AST >3 times ULN (upper limits of normal) was significantly lower in TGP group than control group (1.63% vs 7.75%, P=0.022). More patients achieved remission, good and moderate response in TGP group than control group at 4, 8 and 12 weeks, but the difference was not significant (P>0.05). The proportions of all adverse events were comparable in the two groups except for diarrhea. CONCLUSIONS Our study demonstrates that TGP can significantly reduce the incidence and severity of liver damage caused by MTX+LEF in the treatment of active RA patients.

Association of STAT4 gene polymorphism with increased susceptibility of rheumatoid arthritis in a northern Chinese Han subpopulation

Several studies have reported STAT4 polymorphism is strongly associated with increased susceptibility to rheumatoid arthritis (RA). However, a study from China showed no association between STAT4 and RA susceptibility in a Chinese Han subpopulation. Since the northern Hans are known to be genetically different from the southern Hans, the aim of this study was to investigate the association of STAT4 polymorphism with RA in a large cohort of a northern Chinese Han subpopulation.