Dynamic landscape of immune cell-specific gene regulation in immune-mediated diseases.

Genetic studies have revealed many variant loci that are associated with immune-mediated diseases. To elucidate the disease pathogenesis, it is essential to understand the function of these variants, especially under disease-associated conditions. Here, we performed a large-scale immune cell gene-expression analysis, together with whole-genome sequence analysis. Our dataset consists of 28 distinct immune cell subsets from 337 patients diagnosed with 10 categories of immune-mediated diseases and 79 healthy volunteers. Our dataset captured distinctive gene-expression profiles across immune cell types and diseases. Expression quantitative trait loci (eQTL) analysis revealed dynamic variations of eQTL effects in the context of immunological conditions, as well as cell types. These cell-type-specific and context-dependent eQTLs showed significant enrichment in immune disease-associated genetic variants, and they implicated the disease-relevant cell types, genes, and environment. This atlas deepens our understanding of the immunogenetic functions of disease-associated variants under in vivo disease conditions.

Risk factors for serious infections and infection-related mortality in patients with microscopic polyangiitis: Multicentre REVEAL cohort study.

OBJECTIVE: Infections are a critical concern for patients with microscopic polyangiitis (MPA). This study aimed to identify the risk factors associated with serious infections (SIs) and infection-related mortality in patients with MPA, as well as the effect of glucocorticoid (GC) dose tapering on these outcomes. METHODS: This multicentre, retrospective, and observational study utilised data from a cohort of patients with MPA in Japan [Registry of Vasculitis Patients to Establish REAL World Evidence (REVEAL) cohort]. Patients were categorised based on the occurrence of SIs or infection-related deaths, and various characteristics were compared among the groups. RESULTS: Among 182 patients, 66 (36.2%) experienced 129 SIs and 27 (14.8%) developed infection-related deaths. Advanced age, elevated C-reactive protein (CRP) levels, and higher ratio of the GC dose at 3 months to the initial dose were identified as independent risk factors for SIs. Older age was also associated with infection-related deaths. Furthermore, the cumulative incidence of infection-related deaths was significantly higher in patients with a higher ratio of the GC dose at 24 months to the initial dose. CONCLUSION: Older age, elevated CRP levels, and slower GC dose tapering predispose patients to SIs and infection-related deaths. Strategies, such as rapid GC dose tapering, are anticipated to mitigate the risk of infections.

Pathogenicity of IgG-Fc desialylation and its association with Th17 cells in an animal model of systemic lupus erythematosus.

OBJECTIVES: Decreased sialylation of IgG-Fc glycans has been reported in autoimmune diseases, but its role in systemic lupus erythematosus (SLE) is not fully understood. In this study, we examined the pathogenicity of IgG desialylation and its association with Th17 in SLE using an animal model. METHODS: B6SKG mice, which develop lupus-like systemic autoimmunity due to the ZAP70 mutation, were used to investigate the pathogenicity of IgG desialylation. The proportion of sialylated IgG was compared between B6SKG and wild-type mice with or without ß-glucan treatment-induced Th17 expansion. Anti-interleukin (IL)-23 and anti-IL-17 antibodies were used to examine the role of Th17 cells in IgG glycosylation. Activation-induced cytidine deaminase-specific St6gal1 conditionally knockout (cKO) mice were generated to examine the direct effect of IgG desialylation. RESULTS: The proportions of sialylated IgG were similar between B6SKG and wild-type mice in the steady state. However, IgG desialylation was observed after ß-glucan-induced Th17 expansion, and nephropathy also worsened in B6SKG mice. Anti-IL-23/17 treatment suppressed IgG desialylation and nephropathy. Glomerular atrophy was observed in the cKO mice, suggesting that IgG desialylation is directly involved in disease exacerbation. CONCLUSIONS: IgG desialylation contributes to the progression of nephropathy, which is ameliorated by blocking IL-17A or IL-23 in an SLE mouse model.

Rheumatoid factor recognizes specific domains of the IgG heavy chain complexed with HLA class II molecules.

OBJECTIVE: We previously reported that RF recognized the IgG heavy chain (IgGH)/RA-susceptible HLA class II molecule complex. In the present study, we investigated the molecular mechanisms underlying HLA binding to and the RF recognition of IgGH. METHODS: We synthesized various types of IgGH segments, including VH, CH1, CH2 and CH3, and transfected them with or without HLA class II molecules into the Human Embryonic Kidney 293T cell line. IgGH single domains linked with the HLA-Cw3 peptide, which binds to the binding groove of the HLA class II molecule, were also synthesized. The expression of IgGH domains on the cell surface and their recognition by RF were examined using flow cytometry. RESULTS: Flag-tagged IgGH segments containing CH1 (CH1, VH-CH1, CH1-CH2, VH-CH1-CH2, CH1-CH2-CH3 and VH-CH1-CH2-CH3) were clearly presented on the cell surface by HLA-DR4, while segments without the CH1 domain were expressed at a low level, and the CH3 single domain was only weakly detected on the cell surface, even with HLA-DR4. We then transfected IgGH single domains linked to the Cw3 peptide together with HLA-DR4 and showed that RF-containing sera from RA patients only recognized the CH3 domain and none of the other single domains. When various segments without the Cw3 peptide were transfected with HLA-DR4, only the CH1-CH2-CH3 segment and full-length IgGH were detected by the sera of RA patients. CONCLUSION: The CH1 domain of IgGH binds to the RA-susceptible HLA-DR molecule and is expressed on the cell surface. RF specifically recognizes the CH3 domain of the IgGH/HLA-DR4 complex.

Comparisons of SLE-DAS and SLEDAI-2K and classification of disease activity based on the SLE-DAS with reference to patient-reported outcomes.

OBJECTIVES: Although the SLE Disease Activity Score (SLE-DAS) and its definitions to classify disease activity have been recently developed to overcome the drawbacks of the SLE Disease Activity Index 2000 (SLEDAI-2K), the performance of the SLE-DAS for patient-reported outcomes (PROs) has not been fully examined. We aimed to compare SLE-DAS with SLEDAI-2K and validate the classifications of disease activity based on SLE-DAS in terms of PROs. METHODS: We assessed generic quality of life (QoL) using the Medical Outcome Survey 36-Item Short-Form Health Survey (SF-36), disease-specific QoL using the lupus patient-reported outcome tool (LupusPRO), burden of symptoms using the SLE Symptom Checklist (SSC), patient global assessment (PtGA) and physician global assessment (PhGA). RESULTS: Of the 335 patients with SLE, the magnitudes of the mean absolute error, root mean square error, Akaike information criterion, and Bayesian information criterion were comparable for most PROs between the SLE-DAS and SLEDAI-2K. In contrast, SLEDAI-2K had a higher predictive value for health-related QoL of LupusPRO and PtGA than SLE-DAS. Low disease activity, Boolean and index-based remission and categories of disease activity (remission, mild and moderate/severe activity) were significantly associated with health-related QoL in LupusPRO, SSC and PhGA, but not SF-36 or PtGA. CONCLUSION: No clear differences were identified in the use of the SLE-DAS over the SLEDAI-2K in assessing PROs in patients with SLE. The classification of disease activity based on the SLE-DAS was validated against several PROs. SLE-DAS and its categories of disease activity effectively explain some of the PROs.

Clinical profile and outcome of large-vessel giant cell arteritis in Japanese patients: A single-centre retrospective cohort study.

OBJECTIVES: Recent advances in imaging revealed that giant cell arteritis (GCA) is frequently associated with large vessel involvement (LVI), but they may also contribute to earlier diagnosis and treatment of LV-GCA. We aimed to compare the clinical characteristics of GCA with or without LVI and evaluate its association with clinical outcomes. METHOD: We retrospectively reviewed the medical records of 36 patients with GCA in Kyoto University Hospital. RESULTS: Eighteen patients each were assigned to the LVI(+) and LVI(-) groups. Five-year survival rates in the LVI(+) group were better than in the LVI(-) group (p = .034), while five-year relapse-free survival rates were similar between the groups (p = .75). The LVI(+) group required lower doses of glucocorticoid at month 6 (p = .036). Disease activity evaluated with the Birmingham Vasculitis Activity Score at disease onset was higher in the LVI(-) group (p = .014), and the Vasculitis Damage Index score examined at the last visit was higher in the LVI(-) group (p = .011). CONCLUSION: GCA without LVI had more active disease, severer vascular damage, and worse survival, possibly because of ophthalmic complications and their greater glucocorticoid requirement. Our results revisit the impact of cranial manifestations on disease severity and morbidity.

Factors associated with osteoporosis and fractures in patients with systemic lupus erythematosus: Kyoto Lupus Cohort.

OBJECTIVES: Osteoporosis and compression fractures of the lumbar spine are some of the major adverse effects of glucocorticoid therapy in patients with systemic lupus erythematosus (SLE). This study examined the association between bone mineral density, bone turnover markers, presence of vertebral fractures, and Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index in SLE patients. METHODS: This was a cross-sectional study of 246 outpatients with SLE at the Kyoto University Hospital. Lumbar and femoral bone mineral density was measured with dual-energy X-ray absorptiometry, and the presence of vertebral fractures was determined using X-ray, computed tomography, or magnetic resonance imaging. RESULTS: On multiple regression analysis, both high lumbar and femoral T-scores were associated with the concomitant use of hydroxychloroquine (P = .018 and P = .037, respectively), no use of bisphosphonate or denosumab (P = .004 and P = .038, respectively), high body mass index (P < .001), and low bone-specific alkaline phosphatase level (P = .014 and P = .002, respectively). Vertebral fractures showed a significant association with Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index score (P < .001) and femoral T-score (P < .001). CONCLUSION: Vertebral fracture was associated with SLE-associated organ damage, and serum bone-specific alkaline phosphatase level is a potentially useful marker for osteoporosis monitoring in SLE patients.

Autoantibody profiles associated with morbidity and mortality in scleroderma renal crisis.

OBJECTIVE: The aim of this study was to investigate association of autoantibodies with scleroderma renal crisis (SRC) among Japanese patients. METHODS: The clinical characteristics and mortality of 330 patients with sytemic screlosis (SSc) at Kyoto University Hospital were retrospectively analysed, focusing on possible association with anti-topoisomerase I (anti-topo I), anti-centromere (ACA), anti-RNA polymerase III (RNAPIII) and/or anti-U1-RNP. Logistic regression analyses were performed to reveal any association of these autoantibodies with the development and mortality of SRC. RESULTS: SRC was observed in 24 out of 330 SSc patients, including patients with anti-topo I (n = 12/24, 50%), anti-RNAPIII (n = 7/24, 29%), anti-U1-RNP (n = 5/24, 21%) and ACA (n = 3/24, 13%). Anti-U1-RNP [odds ratio (95% CI), 3.63 (1.11, 10.2)], anti-topo I [3.22 (1.37, 7.57)] and anti-RNAPIII (3.29 [1.16, 8.70]) were associated with the development of SRC. Furthermore, anti-topo I [6.00 (1.11, 41.1)] was associated with 1-year mortality of SRC. The 1-year survival rate after the onset of SRC among all patients and among those positive for anti-topo I was 54% and 33%, respectively. In contrast, the survival rate in patients negative for anti-topo I was 75%, of which the survival rate of patients positive for anti-RNAPIII and ACA was 83% and 100%, respectively. CONCLUSION: Specific SSc-related autoantibodies were associated with the morbidity and mortality of SRC.

Neutrophil count reduction 1 month after initiating tocilizumab can predict clinical remission within 1 year in rheumatoid arthritis patients.

Neutropenia is a common adverse event of tocilizumab (TCZ) in rheumatoid arthritis (RA) patients; however, the association between the decrease in neutrophil counts and the TCZ clinical efficacy remains inconclusive. This study aimed to examine whether TCZ-induced neutrophil decrease at 1 month predicts clinical remission within 1 year. We reviewed medical records of RA patients initiating TCZ between May 2011 and September 2019 in our hospital. The Clinical Disease Activity Index (CDAI) was evaluated at baseline (before initiating TCZ) and 1, 3, 6, and 12 months after administration. Clinical remission was defined when CDAI decreased ≤ 2.8. The ratio of neutrophil counts 1 month after initiating TCZ to those at baseline (neutrophil ratio) was also calculated. Among 255 TCZ-treated patients, 169 with valid CDAI and neutrophil counts were enrolled (with median age of 60 years and 79% females). Rheumatoid factor and anti-cyclic citrullinated peptide antibody were positive in 75% and 83%, respectively, and 56% of the patients had concomitant methotrexate (median dose: 8 mg/week). Multivariate logistic regression analysis suggested baseline CDAI (odds ratio (OR) 0.96, p = 0.045), concomitant PSL (OR 0.42, p = 0.030), and the neutrophil ratio (OR 0.19, p = 0.011) as predictors of CDAI remission. Neutrophil ratio ≤ 0.8 was associated with achieving remission (Fisher's exact test, p = 0.02) with no apparent increase of severe infection. More than 20% reduction of neutrophil count 1 month after initiating TCZ predicts clinical remission within 1 year at an early treatment phase.

Amino acid signatures of HLA Class-I and II molecules are strongly associated with SLE susceptibility and autoantibody production in Eastern Asians.

Human leukocyte antigen (HLA) is a key genetic factor conferring risk of systemic lupus erythematosus (SLE), but precise independent localization of HLA effects is extremely challenging. As a result, the contribution of specific HLA alleles and amino-acid residues to the overall risk of SLE and to risk of specific autoantibodies are far from completely understood. Here, we dissected (a) overall SLE association signals across HLA, (b) HLA-peptide interaction, and (c) residue-autoantibody association. Classical alleles, SNPs, and amino-acid residues of eight HLA genes were imputed across 4,915 SLE cases and 13,513 controls from Eastern Asia. We performed association followed by conditional analysis across HLA, assessing both overall SLE risk and risk of autoantibody production. DR15 alleles HLA-DRB1*15:01 (P = 1.4x10-27, odds ratio (OR) = 1.57) and HLA-DQB1*06:02 (P = 7.4x10-23, OR = 1.55) formed the most significant haplotype (OR = 2.33). Conditioned protein-residue signals were stronger than allele signals and mapped predominantly to HLA-DRB1 residue 13 (P = 2.2x10-75) and its proxy position 11 (P = 1.1x10-67), followed by HLA-DRB1-37 (P = 4.5x10-24). After conditioning on HLA-DRB1, novel associations at HLA-A-70 (P = 1.4x10-8), HLA-DPB1-35 (P = 9.0x10-16), HLA-DQB1-37 (P = 2.7x10-14), and HLA-B-9 (P = 6.5x10-15) emerged. Together, these seven residues increased the proportion of explained heritability due to HLA to 2.6%. Risk residues for both overall disease and hallmark autoantibodies (i.e., nRNP: DRB1-11, P = 2.0x10-14; DRB1-13, P = 2.9x10-13; DRB1-30, P = 3.9x10-14) localized to the peptide-binding groove of HLA-DRB1. Enrichment for specific amino-acid characteristics in the peptide-binding groove correlated with overall SLE risk and with autoantibody presence. Risk residues were in primarily negatively charged side-chains, in contrast with rheumatoid arthritis. We identified novel SLE signals in HLA Class I loci (HLA-A, HLA-B), and localized primary Class II signals to five residues in HLA-DRB1, HLA-DPB1, and HLA-DQB1. These findings provide insights about the mechanisms by which the risk residues interact with each other to produce autoantibodies and are involved in SLE pathophysiology.

Phenotypic landscape of systemic lupus erythematosus: An analysis of the Kyoto Lupus Cohort.

OBJECTIVES: The present study aimed to clarify comprehensive relationships among the clinical variables of systemic lupus erythematosus (SLE). METHODS: We retrospectively surveyed 32 clinical variables in 581 patients and conducted comprehensive association studies among SLE clinical phenotypes. A univariate analysis of all possible combinations was performed, and the results of phenotypic correlations were reduced into two dimensions. We also created a regression formula using L1 regularisation (LASSO) to calculate the probability of exhibiting each phenotype. RESULTS: The univariate analysis identified 26 correlations, including multiple phenotypes with low complement. Some unpredicted correlations were identified, including fever and the anti-Sm antibody (odds ratio; OR = 2.3, p = 1.6 × 10-5) or thrombocytopenia and psychosis (OR = 3.7, p = 3.2 × 10-5). The multivariate analysis accurately estimated the probability of exhibiting each phenotype (area under the curve > 0.7) in 10 out of 20 phenotypes. CONCLUSIONS: The present results show the phenotypic architecture of SLE and represent a model for estimating the probability of exhibiting each phenotype. They also offer insights into the pathology of SLE and estimating the probability of the onset of new phenotypes in clinical practice.

Correlation between irreversible organ damage and the quality of life of patients with systemic lupus erythematosus: The Kyoto Lupus Cohort survey.

OBJECTIVES: It is important to clarify the relationship between irreversible organ damage and the quality of life (QOL) by considering the unique factors of patients with systemic lupus erythematosus (SLE). We aimed to clarify their correlation using SLE-specific QOL assessment tools. We also aimed to identify which type of organ damage is adversely correlated with the QOL. METHODS: We conducted a questionnaire-based survey of outpatients with SLE at Kyoto University Hospital and evaluated irreversible organ damage using the SLICC/ACR damage index (SDI). LupusPRO and the SLE symptom checklist (SSC) were employed as SLE-specific QOL tools, and the SF-36v2 was used as a conventional QOL tool. Multiple linear regression analyses were performed to examine the correlations between the total SDI score and each QOL score, and between each SDI item/system score and each QOL score. RESULTS: We analyzed the data of 265 patients. The total SDI score was significantly correlated with physical (PCS) and role/social component summary (RCS) of the SF-36v2, health-related QOL (HRQOL) of LupusPRO, and SSC (p < 0.001). Among the SDI items, atrophy/weakness and osteoporosis with fracture/vertebral collapse were negatively correlated with PCS (ß = -0.40, p < 0.001/ß = -0.28, p < 0.001), RCS (ß = -0.30, p < 0.001/ß = -0.35, p < 0.001), and HRQOL (ß = -0.34, p < 0.001/ß = -0.31, p < 0.001), respectively. Among the SDI systems, musculoskeletal damage had higher negative correlations with PCS (ß = -0.51, p < 0.001), RCS (ß = -0.29, p < 0.001), and HRQOL (ß = -0.40, p < 0.001). CONCLUSION: We demonstrated the QOL of patients with SLE is negatively correlated with irreversible organ damage. We also revealed musculoskeletal damage is adversely correlated with the health-related QOL, especially the physical and role/social QOL.

Validation and verification of the Japanese version of the systemic lupus erythematosus symptom checklist for patient quality of life.

OBJECTIVE: The systemic lupus erythematosus (SLE) symptom checklist (SSC) is a patient-reported outcome measure consisting of 38 queries. We translated SSC into Japanese and attempted to validate its usefulness for evaluating the quality of life (QOL) of SLE patients and identify factors that affect QOL. METHODS: Data from the Medical Outcomes Study Short-form 36 questionnaire (SF-36), Japanese LupusPRO, the Japanese version of the SSC (SSC-J) questionnaire, SLEDAI-2k, and the physician global assessment (PGA) were obtained on the same day from 226 SLE outpatients of the Kyoto Lupus cohort at Kyoto University Hospital. Relationships between the total scores or each item of SSC-J and SF-36, Japanese LupusPRO, SLEDAI-2k, or PGA were analyzed by Spearman's rank test. RESULTS: The total scores of SSC-J correlated with the scores of SF-36 and Japanese LupusPRO. In each item of SSC-J, all 38 items correlated with the physical component summary and mental component summary of SF-36 as well as the Health-Related QOL (HRQOL) scores of Japanese LupusPRO, but not with the non-HRQOL of LupusPRO. SSC-J scores correlated with age, PGA, and corticosteroid doses, but not with SLEDAI-2k. CONCLUSIONS: SSC-J is suitable as a disease-specific QOL assessment tool for SLE.

Efficacy of plasma exchange in anti-MDA5-positive dermatomyositis with interstitial lung disease under combined immunosuppressive treatment.

OBJECTIVES: Rapidly progressive interstitial lung disease (RP-ILD) with poor prognosis often accompanies anti-melanoma differentiation-associated gene 5 (MDA5)-positive DM. Combined immunosuppressive therapy, including glucocorticoids, calcineurin inhibitors and intravenous cyclophosphamide (IVCY) is reportedly effective in DM with RP-ILD, but some patients remain resistant to therapy. We examined the utility of plasma exchange (PE) in such intractable cases and investigated the prognostic factors of the disease. METHODS: Thirty-eight anti-MDA5-positive DM-ILD patients who received the combined immunosuppressive therapy were retrospectively reviewed. Their serum cytokines were evaluated by multiplex assay before treatment. The patients were divided into two groups: those who achieved remission without exacerbation of respiratory dysfunction (n = 25, group A) and those who progressed to hypoxemia during the treatment (n = 13, group B). RESULTS: PE was carried out in eight group B patients, but none of group A. Five of the eight treated with PE survived, while the five untreated patients died (P =0.04). Higher neutrophil lymphocyte ratio, higher serum ferritin, hypoxemia, high-resolution computed tomography (HRCT) score before treatment and increase of Krebs von Lungen-6 (KL-6) in the first 4 weeks of the treatment were the prognostic factors for disease progression. Serum cytokines such as IL-1, IL-6, IL-8, IL-10, IL-12p70, IL-18 and sCD163 levels were higher in group B than group A. CONCLUSION: PE should be an effective adjuvant treatment in anti-MDA5-positive DM with RP-ILD. Assessment of basal laboratory tests or monocyte/macrophage-derived cytokines and the increase of KL-6, HRCT score and hypoxemia may help us to predict intractable cases and to make early treatment decisions regarding PE in anti-MDA5-positive DM.

Activated neutrophil carbamylates albumin via the release of myeloperoxidase and reactive oxygen species regardless of NETosis.

Objective: An anti-carbamylated albumin antibody was detected in rheumatoid arthritis (RA) patients, and its presence was associated with serum myeloperoxidase (MPO) levels, as we reported previously. Since MPO is a key enzyme for carbamylation and is released by neutrophil extracellular traps (NETs), we aimed to demonstrate that NETosis induces carbamylation.Methods: Human neutrophils were isolated from a healthy donor, pre-treated with or without diphenyleneiodonium (DPI, an inhibitor for the generation of reactive oxygen species (ROS)), Cl-amidine (a peptidylarginine deiminase inhibitor), 4-aminobenzoic acid hydrazide (4-ABAH, an MPO inhibitor), or GW311616A (a neutrophil elastase (NE) inhibitor), and incubated for 8 h with or without phorbol 12-myristate 13-acetate (PMA). Proteins in the medium were collected and the carbamylation of albumin was evaluated by Western blotting.Results: The carbamylation of albumin was detected in the culture medium of activated neutrophils. NETosis was observed under the stimulation by PMA. DPI and 4-ABAH inhibited the carbamylation of albumin and NETosis. GW311616A inhibited NETosis, but not carbamylation. Neither carbamylation nor NETosis was inhibited by Cl-amidine.Conclusion: Activated neutrophils may carbamylate ambient albumin, and this is dependent on ROS and MPO, but does not require NETosis.

PLD4 is a genetic determinant to systemic lupus erythematosus and involved in murine autoimmune phenotypes.

OBJECTIVES: Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterised by autoantibody production and widespread inflammation damaging many organs. Previous genome-wide association studies (GWASs) have revealed over 80 genetic determinants of SLE, but they collectively explain a fraction of the heritability, and only a few were proven in vivo for the involvement in SLE. We conducted a meta-analysis of SLE GWAS in the Japanese population, followed by functional analyses of a susceptibility gene with use of mutant mice. METHODS: We conducted a meta-analysis of two GWASs comprising a total of 1363 cases and 5536 controls using the 1000 Genome Project data as an imputation reference. Enrichment analyses for functional annotations were conducted. We examined Phospholipase D4 (Pld4) mutant mice to assess functional involvement of a genetic determinant. RESULTS: We found a total of 14 significant loci, which included rs2582511 in AHNAK2/PLD4 recently reported in a Chinese study and a novel locus of rs143181706 in MAMLD1 (p=7.9×10-11 and 3.7×10-8, respectively). PLD4 risk allele was associated with anti-dsDNA antibody production. Enrichment analysis of genetic signals revealed involvement of a wide range of immune-related cells and pathways. Pld4 mutant mice revealed remarkably low body weight. The mice demonstrated autoimmune phenotypes compatible with SLE, including splenomegaly and lymphadenopathy, expansion of B cells and hypersecretion of BAFF and production of autoantibodies especially anti-nuclear antibody and anti-dsDNA antibody. CONCLUSIONS: We found a novel susceptibility gene to SLE. Pld4 mutant mice revealed autoimmune phenotypes suggesting functional involvement of PLD4 with the basics of SLE.

Suppressor of TCR signaling-2 (STS-2) suppresses arthritis development in mice.

OBJECTIVES: Suppressor of TCR signaling-2 (STS-2) is one of the RA susceptibility genes identified in genome-wide association studies (GWAS). We tried to verify the involvement of STS-2 on the development of autoimmune arthritis in a mouse model. METHODS: STS-2 knock-out (KO) and wild type (WT) mice were immunized with chicken type II collagen (CII). For CD4+ helper T cell (Th) subset analysis, intracellular cytokines in splenocytes and lymph node cells were stained and analyzed by flow cytometry. Regulatory T cell (Treg) function was analyzed by co-culturing effector CD4+T cells and Tregs collected from non-immunized mice. RESULTS: CII-immunized STS-2 KO mice developed arthritis more frequently than WT mice. Although the T cell activation profile and Th subset in spleen and LNs were similar between STS-2 KO and WT mice, STS-2 KO mice showed increased IL-2-producing CD4+T cells in spleen when compared with WT mice. Accordingly, STS-2 KO CD4+T cells promoted IL-2 production by TCR stimulation. However, STS-2 KO Tregs normally suppressed T cell proliferation. CONCLUSION: We proved that STS-2 is involved in the arthritis development by collagen-induced arthritis. Higher IL-2 production from STS-2 KO T cells is suggested to have a main pathogenic role in arthritis development.

Cell-contact-dependent activation of CD4+ T cells by adhesion molecules on synovial fibroblasts.

OBJECTIVE: To determine how cell-cell contact with synovial fibroblasts (SF) influence on the proliferation and cytokine production of CD4+ T cells. METHODS: Naïve CD4+ T cells were cultured with SF from rheumatoid arthritis patients, stimulated by anti-CD3/28 antibody, and CD4+ T cell proliferation and IFN-γ/IL-17 production were analyzed. To study the role of adhesion molecules, cell contact was blocked by transwell plate or anti-intracellular adhesion molecule-1 (ICAM-1)/vascular cell adhesion molecule-1(VCAM-1) antibody. To study the direct role of adhesion molecules for CD4+ T cells, CD161+ or CD161- naïve CD4+ T cells were stimulated on plastic plates coated by recombinant ICAM-1 or VCAM-1, and the source of IFN-γ/IL-17 were analyzed. RESULTS: SF enhanced naïve CD4+ T cell proliferation and IFN-γ/IL-17 production in cell-contact and in part ICAM-1-/VCAM-1-dependent manner. Plate-coated ICAM-1 and VCAM-1 enhanced naïve CD4+ T cell proliferation and IFN-γ production, while VCAM-1 efficiently promoting IL-17 production. CD161+ naïve T cells upregulating LFA-1 and VLA-4 were the major source of IFN-γ/IL-17 upon interaction with ICAM-1/VCAM-1. CONCLUSION: CD4+ T cells rapidly expand and secrete IFN-γ/IL-17 upon cell-contact with SF via adhesion molecules. Interfering with ICAM-1-/VCAM-1 may be beneficial for inhibiting RA synovitis.

TAFRO syndrome is associated with anti-SSA/Ro60 antibodies, in contrast to idiopathic castleman disease.

TAFRO syndrome is an acute systemic inflammatory disease characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis/renal dysfunction, and organomegaly. There have been increasing reports that TAFRO is a disease distinct from idiopathic multicentric Castleman disease and that TAFRO patients may be positive for anti-SSA antibodies. To assess anti-SSA antibody positivity and the clinical characteristics of the two diseases, we retrospectively compared 7 TAFRO and 10 iMCD patients in our hospital. The mean age of onset of TAFRO and iMCD was 48.0 (interquartile range [IQR], 41-53) and 45.0 (IQR, 35-53) years, respectively. The TAFRO and iMCD groups had 6 (86%) and 4 (40%) male patients, respectively, and the following pretreatment laboratory values: platelet count, 3.8 (IQR, 2.2-6.4) and 35.5 (IQR, 22.2-42.8) × 104/µL, respectively; C-reactive protein, 10.2 (IQR, 6.8-21.4) and 9.5 (IQR, 6.2-13.6) mg/dL, respectively; IgG, 1431 (IQR, 1112-1815) and 4725 (IQR, 3755-5121) mg/dL, respectively. RNA immunoprecipitation (5 cases for anti-SSA) or protein array (5 cases for anti-SSA/Ro60) detected anti-SSA antibodies in six (86%) TAFRO patients but not in iMCD patients; it did not detect anti-SSB antibodies in any of the patients. None of the patients were diagnosed with Sjögren syndrome. All iMCD patients treated with tocilizumab (TCZ) responded well. Meanwhile, two of six TAFRO patients treated with TCZ showed inadequate responses; thus, both patients were switched to rituximab, following which they achieved remission. TAFRO and iMCD have different clinical features. TAFRO may be categorized as a severe phenotype of the anti-SSA antibody syndrome.