Ji Ah Park

HLA-DPB1 and DPB2 are genetic loci for systemic sclerosis: A genome-wide association study in Koreans with replication in North Americans

OBJECTIVE To identify systemic sclerosis (SSc) susceptibility loci via a genome-wide association study. METHODS A genome-wide association study was performed in 137 patients with SSc and 564 controls from Korea using the Affymetrix Human SNP Array 5.0. After fine-mapping studies, the results were replicated in 1,107 SSc patients and 2,747 controls from a US Caucasian population. RESULTS The single-nucleotide polymorphisms (SNPs) (rs3128930, rs7763822, rs7764491, rs3117230, and rs3128965) of HLA-DPB1 and DPB2 on chromosome 6 formed a distinctive peak with log P values for association with SSc susceptibility (P=8.16x10(-13)). Subtyping analysis of HLA-DPB1 showed that DPB1*1301 (P=7.61x10(-8)) and DPB1*0901 (P=2.55x10(-5)) were the subtypes most susceptible to SSc in Korean subjects. In US Caucasians, 2 pairs of SNPs, rs7763822/rs7764491 and rs3117230/rs3128965, showed strong association with SSc patients who had either circulating anti-DNA topoisomerase I (P=7.58x10(-17)/4.84x10(-16)) or anticentromere autoantibodies (P=1.12x10(-3)/3.2x10(-5)), respectively. CONCLUSION The results of our genome-wide association study in Korean subjects indicate that the region of HLA-DPB1 and DPB2 contains the loci most susceptible to SSc in a Korean population. The confirmatory studies in US Caucasians indicate that specific SNPs of HLA-DPB1 and/or DPB2 are strongly associated with US Caucasian patients with SSc who are positive for anti-DNA topoisomerase I or anticentromere autoantibodies.

Genome-wide association study identifies GIMAP as a novel susceptibility locus for Behçet's disease

Objectives To identify non-major histocompatibility complex susceptible genes that might contribute to Behçets disease (BD). Methods We performed a genome-wide association study using DNA samples from a Korean population consisting of 379 BD patients and 800 controls. A replication study was performed in a Japanese population (363 BD patients and 272 controls). To evaluate the functional implication of the target single nucleotide polymorphisms (SNP), gene expression levels in peripheral T cells, allele-specific modulation of promoter activity and biological effect of mRNA knockdown were investigated. Results We found a novel association of BD to the GIMAP locus, mapped to chromosome 7q36.1 (rs1608157, p=6.01×10−8 in a minor allele dominant model; rs11769828, allele based p=1.60×10−6). A fine mapping study identified an association with four additional SNP: rs1522596 (OR=1.45, p=7.70×10−6) in GIMAP4; rs10266069 (OR=1.32, p=2.67×10−4) and rs10256482 (OR=1.27, p=5.27×10−4) in GIMAP2; and rs2286900 (OR=1.61, p=3.53×10−5) in GIMAP1 areas. Replication study using DNA samples from the Japanese population validated the significant association between BD and the GIMAP locus. The GIMAP4 promoter construct plasmid with the minor allele of rs1608157 displayed significantly lower activity than one with the major allele. Moreover, CD4 T cells from BD patients showed a lower level of GIMAP4 mRNA, and GIMAP4 knockdown was protective against Fas-mediated apoptosis. Conclusions These results suggest that a GIMAP cluster is a novel susceptibility locus for BD, which is involved in T-cell survival, and T-cell aberration can contribute to the development of BD.

Characterization of effector memory CD8+ T cells in the synovial fluid of rheumatoid arthritis.

Little is known about the cellular characteristics of CD8+ T cells in rheumatoid arthritis (RA). We addressed this by investigating whether the frequency of the CD8+ T cell subsets and their phenotypic characteristics are altered in the peripheral blood and synovial fluid (SF) from patients with RA. In this study, CD8+ T cells, mainly CD45RA– effector memory (EM) CD8+ T cells, were increased significantly in the SF, but not in the peripheral blood from RA patients, compared with healthy controls. The synovial EM CD8+ T cells were activated phenotypes with high levels of CD80, CD86, and PD-1, and had a proliferating signature in vivo upon Ki-67 staining, whereas the Fas-positive cells were prone to apoptosis. In addition, EM CD8+ T cells in the SF were less cytotoxic, as they expressed less perforin and granzyme B. In particular, the proportions of synovial fluid mononuclear cells that were CCR4+CD8+ T cells and IL-4-producing CD8+ T cells (i.e., Tc2 cells) were significantly higher than those in peripheral blood mononuclear cells of patients with RA and healthy controls. In addition, the number of IL-10-producing CD8+ suppressor T (Ts) cells increased significantly in the SF of RA patients. Especially, CD8+ T cells were inversely correlated with disease activity. These findings strongly suggest that EM CD8+ T cells in the SF are increased, likely because of inflammation, and they may be involved in modulating inflammation, thereby affecting the development and progression of RA.

HM71224, a novel Bruton’s tyrosine kinase inhibitor, suppresses B cell and monocyte activation and ameliorates arthritis in a mouse model: a potential drug for rheumatoid arthritis

BackgroundBruton’s tyrosine kinase (Btk) is critical for activation of B cells and myeloid cells. This study aimed to characterize the effects of HM71224, a novel Btk inhibitor, both in vitro and in a mouse model of experimental arthritis.MethodsThe kinase inhibition profile of HM71224 was analyzed. The in vitro effects of HM71224 on B cells and monocytes were analyzed by examining phosphorylation of Btk and its downstream signaling molecules, along with cytokine production and osteoclast formation. The in vivo effects of HM71224 were investigated in a mouse model of collagen-induced arthritis (CIA).ResultsHM71224 irreversibly bound to and inhibited Btk (IC50 = 1.95 nM). The compound also inhibited the phosphorylation of Btk and its downstream molecules such as PLCγ2, in activated Ramos B lymphoma cells and primary human B cells in a dose-dependent manner. Furthermore, HM71224 effectively inhibited the production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β by human monocytes, and osteoclast formation by human monocytes. Finally, HM71224 improved experimental arthritis and prevented joint destruction in a murine model of CIA.ConclusionsHM71224 inhibits Btk in B cells and monocytes and ameliorates experimental arthritis in a mouse model. Thus, HM71224 is a potential novel therapeutic agent for rheumatoid arthritis in humans.

CXCR3 polymorphism is associated with male gender and pleuritis in patients with systemic lupus erythematosus.

BACKGROUND Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease involving multiple organs. Chemokines and their receptors play an important role in the pathogenesis of SLE. Lymphocytes expressing CXCR3, chemokine receptors of CXCL4, 9, 10, and 11, increase in patients with SLE and animal models, particularly in those with skin manifestations and nephritis. We investigated CXCR3 genetic polymorphisms in patients with SLE and their association with clinical manifestations. METHODS A total of 346 patients with SLE and 540 healthy controls were investigated for CXCR3 intron 1 polymorphisms rs2280964 and rs34334103 by Taqman analysis. RESULTS rs2280964 and rs34334103 were not associated with all patients with SLE, but rs34334103 showed a significant association with male patients with SLE. Among the clinical manifestations, pleuritis was associated with the rs34334103 polymorphism. CONCLUSION The CXCR3 polymorphism rs34334103 was associated with male gender and pleuritis in patients with SLE.

SAT0065 Alpha-enolase facilitates migration of fibroblast-like synoviocytes in rheumatoid arthritis

Background Alpha-enolase (ENO1) is a multifunctional glycolytic enzyme ubiquitously expressed in the cytoplasm. Citrullinated ENO1 is reported to be a candidate autoantigen in rheumatoid arthritis (RA), yet its specific biologic function remains unknown. Histologic analysis indicates that ENO1 is expressed in fibroblast-like synoviocytes (FLS), monocytes, and endothelial cells in the synovium. In pro-inflammatory conditions, ENO1 is translocated to the cell surface where it activates plasminogen. Its expression in monocytes mediates migration of the cells into inflamed lung tissues in animal models. Objectives Our aim was to investigate the role of surface-expressed ENO1 in RA FLS, the key constituent of pannus in RA synovium. Methods FLS from RA synovial tissues were isolated and cultured in vitro. ENO1 expression on the cell surface was assessed by confocal microscopy. Cell surface-expressed ENO1 was treated with a mouse anti-human ENO1-stimulating monoclonal antibodyas well as an isotype control. Scratch test of cultured FLS and transwell experiments under platelet-derived growth factor (PDGF) were performed to assess FLS migration. Cytoskeletal rearrangement was analyzed after staining FLS with an anti-fillagrin antibody. Fluo-4 fluorophore was used for calcium-flux assays directly on discs plated with FLS. Results Cell surface ENO1 expression was low in (5∼6 passages) cultured FLSunder normal condtions. However, overnight TNF-alpha (as low as 0.1ng/ml)treatment induced ENO1 translocation to the cell surface, which peaked at 24 hours (figure). Stimulation of cell surface-expressed ENO1 induced faster repopulation of FLS in the scratch test assay, and increased PDGF-induced transwell migration. Cytoplasmic actin filament rearrangement in FLS was markedly enhanced with ENO1 stimulation. Moreover, ENO1 stimulation induced a positive calcium flux response in FLS under intravital confocal microscopy. Conclusions Translocation of cytoplasmic ENO1 to the cell surface in RA FLS is potentiated by TNF-alpha. Our results indicate that ENO1 can contribute to migration of RA FLS, especially under the pro-inflammatory milieu as in the RA synovium. Disclosure of Interest None Declared

Role of Stem Cell-Like Memory T Cells in Systemic Lupus Erythematosus

Stem cell–like memory T (Tscm) cells are long‐lived memory T cells that have multipotent capacity to differentiate into different subsets. However, the role of Tscm cells in autoimmune diseases remains unclear. Here, we performed phenotypic studies to identify Tscm cells in patients experiencing systemic lupus erythematosus (SLE).