Targeting CD13/aminopeptidase N as a novel therapeutic approach for scleroderma fibrosis.

OBJECTIVE: Systemic sclerosis (SSc) is an autoimmune multisystem disease with poorly understood pathogenesis and ineffective treatment options. Soluble CD13 (sCD13), generated by cleavage of cell surface CD13 via matrix metalloproteinase 14 (MMP14), signals through the bradykinin receptor B1 (B1R) to elicit pro-inflammatory, pro-arthritic, and pro-angiogenic responses. In this study we explored the anti-fibrotic potential of targeting the sCD13-B1R axis in SSc. METHODS: The expression of CD13, B1R and MMP14 was examined in SSc skin and explanted dermal fibroblasts. The efficacy of B1R antagonists in the inhibition on fibrosis was determined in vitro and in vivo. RESULTS: Expression of the genes for CD13, B1R and MMP14 was elevated in skin biopsies from patients with diffuse cutaneous (dc)SSc. Notably, single cell analysis of SSc skin biopsies revealed the highest BDKRB1 expression in COL8A1-positive myofibroblasts, a population exclusively seen in SSc. TGF-ß induced the expression of BDKRB1 and production of sCD13 by dcSSc skin fibroblasts. Treatment of dcSSc fibroblasts with sCD13 promoted fibrotic gene expression, signaling, cell proliferation, migration, and gel contraction. The profibrotic sCD13 or TGFß responses were prevented by a B1R antagonist. Mice lacking Cd13 or Bdkrb1 were resistant to bleomycin-induced skin fibrosis and inflammation. Pharmacological B1R inhibition had a comparable antifibrotic effect. CONCLUSION: These results are the first to demonstrate a key role for sCD13 in SSc skin fibrosis, and suggest that targeting the sCD13-B1R signaling axis is a promising novel therapeutic approach for SSc.

Long-term effects of abatacept on atherosclerosis and arthritis in older vs. younger patients with rheumatoid arthritis: 3-year results of a prospective, multicenter, observational study.

BACKGROUND: We aimed to reveal the effect of abatacept (ABT) on atherosclerosis in rheumatoid arthritis (RA) patients, 3-year efficacy for arthritis, and safety in a population of older vs. younger patients. METHODS: In this open-label, prospective, observational study, patients were stratified into four groups: younger (20-64 years old) and older (≥ 65 years) patients taking ABT (AY and AO) and conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) (CY and CO). Primary endpoints were change from baseline in mean intima-media thickness (IMT) of the common carotid artery, IMT max (bulbus, bifurcation, and internal and common carotid artery), and plaque score at Week 156. Disease activity, retention rate, and adverse effects were also evaluated. RESULTS: The ABT group (AY + AO) tended to have smaller increases in mean IMT, max IMT, and plaque score than the csDMARD group (CY + CO) at Week 156, although the differences between groups were not statistically significant. Multivariate analysis showed significantly lower increases in plaque score with ABT than with csDMARDs, only when considering disease activity at 156 weeks (p = 0.0303). Proportions of patients with good or good/moderate European League Against Rheumatism response were higher in the ABT group, without significant difference between older and younger patients. No significant differences were observed in ABT retention rates between older and younger patients. Serious adverse effects, especially infection, tended to be more frequent with ABT than with csDMARDs, although no significant differences were found. CONCLUSIONS: ABT may decelerate atherosclerosis progression and may be useful for patients with high risk of cardiovascular disease, such as older patients. TRIAL REGISTRATION NUMBER: UMIN000014913.

Relationship Between the Lipidome Profile and Disease Activity in Patients with Rheumatoid Arthritis.

Lipid mediators have been suggested to play important roles in the pathogenesis of rheumatoid arthritis (RA). Lipidomics has recently allowed for the comprehensive analysis of lipids and has revealed the potential of lipids as biomarkers for the early diagnosis of RA and prediction of therapeutic responses. However, the relationship between disease activity and the lipid profile in RA remains unclear. In the present study, we performed a plasma lipidomic analysis of 278 patients with RA during treatment and examined relationships with disease activity using the Disease Activity Score in 28 joints (DAS28)-erythrocyte sedimentation rate (ESR). In all patients, five lipids positively correlated and seven lipids negatively correlated with DAS28-ESR. Stearic acid [FA(18:0)] (r = -0.45) and palmitic acid [FA(16:0)] (r = -0.38) showed strong negative correlations. After adjustments for age, body mass index (BMI), and medications, stearic acid, palmitic acid, bilirubin, and lysophosphatidylcholines negatively correlated with disease activity. Stearic acid inhibited osteoclast differentiation from peripheral blood monocytes in in vitro experiments, suggesting its contribution to RA disease activity by affecting bone metabolism. These results indicate that the lipid profile correlates with the disease activity of RA and also that some lipids may be involved in the pathogenesis of RA.

Activation of cytotoxic lymphocytes through CD6 enhances killing of cancer cells.

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft mouse models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8 + T cells. In particular, tumor-infiltrating cytotoxic lymphocytes from UMCD6-treated mice expressed higher levels of perforin and were found in higher proportions than those from IgG-treated mice. Moreover, RNA-seq analysis of human NK-92 cells treated with UMCD6 revealed that UMCD6 up-regulates the NKG2D-DAP10 receptor complex, important in NK cell activation, as well as its downstream target PI3K. Our results now describe the phenotypic changes that occur on immune cells upon treatment with UMCD6 and further confirm that the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Activation of Cytotoxic Lymphocytes Through CD6 Enhances Killing of Cancer Cells.

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8+ T cells. Tumor-infiltrating cytotoxic lymphocytes were found in higher proportions and were activated in UMCD6-treated mice compared to controls. Similar changes in gene expression were observed by RNA-seq analysis of NK cells treated with UMCD6. Particularly, UMCD6 up-regulated the NKG2D-DAP10 complex and activated PI3K. Thus, the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Clinical characteristics of COVID-19 patients with underlying rheumatic diseases in Japan: data from a multicenter observational study using the COVID-19 Global Rheumatology Alliance physician-reported registry.

INTRODUCTION: To describe clinical characteristics of patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic disease and examine the possible risk factors associated with severe COVID-19. METHODS: Adults with rheumatic disease and a COVID-19 diagnosis who were registered in the COVID-19 Global Rheumatology Alliance (C19-GRA) physician-reported registry from Japan between 15 May 2020 and 12 May 2021 were included. Multivariable logistic regression models were used to assess factors associated with severe COVID-19 progression, defined as death or requiring oxygen inhalation. RESULTS: In total, 222 patients were included in the study. Rheumatoid arthritis (48.2%), gout (14.4%), and systemic lupus erythematosus (8.1%) were the most common types of rheumatic disease, 55.1% of patients were in remission and 66.2% had comorbid disease. Most patients were hospitalised (86.9%) for COVID-19, 43.3% received oxygen, and 9.0% died. Older age (≥ 65 years), corticosteroid use, comorbid diabetes, and lung diseases are associated with higher risk for severe COVID-19 progression (odds ratio (OR) 3.52 [95% confidence interval (CI) 1.69-7.33], OR 2.68 [95% CI 1.23-5.83], OR 3.56 [95% CI 1.42-8.88], and OR 2.59 [95% CI 1.10-6.09], respectively). CONCLUSIONS: This study described clinical characteristics of COVID-19 patients with rheumatic diseases in Japan. Several possible risk factors for severe COVID-19 progression were suggested. Key points • Clinical characteristics of 222 adult patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic diseases were described. • Most patients were hospitalised (86.9%) for COVID-19 in Japan, 43.3% received oxygen, and 9.0% died. • The COVID-19 characteristics of patients with rheumatic diseases did not show any obvious different pattern from those of the general population in Japan. • In this study, older age (≥ 65 years), corticosteroid use, comorbid diabetes, and lung diseases are associated with higher risk for severe COVID-19 progression.

Soluble CD13 induces inflammatory arthritis by activating the bradykinin receptor B1.

CD13, an ectoenzyme on myeloid and stromal cells, also circulates as a shed, soluble protein (sCD13) with powerful chemoattractant, angiogenic, and arthritogenic properties, which require engagement of a G protein-coupled receptor (GPCR). Here we identify the GPCR that mediates sCD13 arthritogenic actions as the bradykinin receptor B1 (B1R). Immunofluorescence and immunoblotting verified high expression of B1R in rheumatoid arthritis (RA) synovial tissue and fibroblast-like synoviocytes (FLSs), and demonstrated binding of sCD13 to B1R. Chemotaxis, and phosphorylation of Erk1/2, induced by sCD13, were inhibited by B1R antagonists. In ex vivo RA synovial tissue organ cultures, a B1R antagonist reduced secretion of inflammatory cytokines. Several mouse arthritis models, including serum transfer, antigen-induced, and local innate immune stimulation arthritis models, were attenuated in Cd13-/- and B1R-/- mice and were alleviated by B1R antagonism. These results establish a CD13/B1R axis in the pathogenesis of inflammatory arthritis and identify B1R as a compelling therapeutic target in RA and potentially other inflammatory diseases.

Inhibition of bromodomain extraterminal histone readers alleviates skin fibrosis in experimental models of scleroderma.

Binding of the bromodomain and extraterminal domain proteins (BETs) to acetylated histone residues is critical for gene transcription. We sought to determine the antifibrotic efficacy and potential mechanisms of BET inhibition in systemic sclerosis (SSc). Blockade of BETs was done using a pan-BET inhibitor, JQ1; BRD2 inhibitor, BIC1; or BRD4 inhibitors AZD5153 or ARV825. BET inhibition, specifically BRD4 blockade, showed antifibrotic effects in an animal model of SSc and in patient-derived diffuse cutaneous SSc (dcSSc) fibroblasts. Transcriptome analysis of JQ1-treated dcSSc fibroblasts revealed differentially expressed genes related to extracellular matrix, cell cycle, and calcium (Ca2+) signaling. The antifibrotic effect of BRD4 inhibition was mediated at least in part by downregulation of Ca2+/calmodulin-dependent protein kinase II α and reduction of intracellular Ca2+ concentrations. On the basis of these results, we propose targeting Ca2+ pathways or BRD4 as potentially novel therapeutic approaches for progressive tissue fibrosis.

Abatacept is Efficacious in the Treatment of Older Patients with csDMARD-Refractory Rheumatoid Arthritis: A Prospective, Multicenter, Observational Study.

INTRODUCTION: Abatacept efficacy in older patients with rheumatoid arthritis (RA) has been primarily demonstrated via retrospective comparisons with younger patients. The objective of this study was to compare efficacy of abatacept in older vs. younger patients with RA, and efficacy of abatacept with that of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) in both age groups. METHODS: This prospective, multicenter, observational study (UMIN000014913) enrolled csDMARD-refractory patients without previous biological DMARD treatment. Abatacept (A) or csDMARDs (C) were administered at the treating physician's discretion to older (O, ≥ 65 years) and younger (Y, 20-64 years) patients, producing AO, AY, CO, and CY groups. Clinical efficacy after 24 weeks was evaluated using European League Against Rheumatism (EULAR) erythrocyte sedimentation rate response criteria. RESULTS: Overall, 202 patients were evaluated. Compared with the CO group, more patients in the AO group achieved a EULAR good or moderate response (p < 0.0001). Compared with the CY group, more patients in the AY group achieved a EULAR good or moderate response (p < 0.01). Similar proportions of patients in the AO and AY groups achieved a EULAR good response or a good or moderate response. Few adverse events were reported. CONCLUSIONS: This prospective study demonstrated that abatacept is efficacious and safe in older patients with RA and a history of being refractory to csDMARDs. Abatacept was shown to be more efficacious than adding or switching to a new csDMARD in both younger and older csDMARD-refractory patients with RA. TRIAL REGISTRATION: UMIN000014913.

CX3CL1/fractalkine regulates the differentiation of human peripheral blood monocytes and monocyte-derived dendritic cells into osteoclasts.

Osteoclast differentiation is promoted under inflammatory conditions and osteoclasts play a major role in bone destruction in rheumatoid arthritis (RA). Chemokine (C-X3-C motif) ligand 1 (CX3CL1), also known as fractalkine, functions as a chemoattractant and adhesion molecule, and is involved in the pathogenesis of RA. The blockade of CX3CL1 inhibits the migration of macrophages and osteoclast precursor cells into the inflamed synovium. In the present study, we investigated the direct stimulatory effects of CX3CL1 on osteoclast differentiation from human peripheral blood monocytes and monocyte-derived dendritic cells. A stimulation with CX3CL1 significantly promoted osteoclast differentiation from CD16- monocytes and also monocyte-derived dendritic cells induced by macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL). On the other hand, CD16+ monocytes treated with M-CSF and RANKL did not differentiate into osteoclasts, even with CX3CL1. Calcium resorption was significantly increased by monocyte-derived osteoclasts, but not by dendritic cell-derived osteoclasts, following the addition of CX3CL1. The present results suggest that CX3CL1 directly regulates osteoclast differentiation. CX3CL1 may play important roles in the pathogenesis of RA, not only through the accumulation of inflammatory cells, but also through osteoclastogenesis.

Treatment with an Anti-CX3CL1 Antibody Suppresses M1 Macrophage Infiltration in Interstitial Lung Disease in SKG Mice.

CX3C Motif Chemokine Ligand 1 (CX3CL1; fractalkine) has been implicated in the pathogenesis of rheumatoid arthritis (RA) and its inhibition was found to attenuate arthritis in mice as well as in a clinical trial. Therefore, we investigated the effects of an anti-CX3CL1 monoclonal antibody (mAb) on immune-mediated interstitial lung disease (ILD) in SKG mice, which exhibit similar pathological and clinical features to human RA-ILD. CX3CL1 and CX3C chemokine receptor 1 (CX3CR1), the receptor for CX3CL1, were both expressed in the fibroblastic foci of lung tissue and the number of bronchoalveolar fluid (BALF) cells was elevated in ILD in SKG mice. No significant changes were observed in lung fibrosis or the number of BALF cells by the treatment with anti-CX3CL1 mAb. However, significantly greater reductions were observed in the number of M1 macrophages than in M2 macrophages in the BALF of treated mice. Furthermore, CX3CR1 expression levels were significantly higher in M1 macrophages than in M2 macrophages. These results suggest the stronger inhibitory effects of the anti-CX3CL1 mAb treatment against the alveolar infiltration of M1 macrophages than M2 macrophages in ILD in SKG mice. Thus, the CX3CL1-CX3CR1 axis may be involved in the infiltration of inflammatory M1 macrophages in RA-ILD.

New Assay System Elecsys Anti-p53 to Detect Serum Anti-p53 Antibodies in Esophageal Cancer Patients and Colorectal Cancer Patients: Multi-institutional Study.

BACKGROUND: Several recent studies suggest that serum anti-p53 antibodies (s-p53-Abs) may be combined with other markers to detect esophageal and colorectal cancer. In this study, we assessed the sensitivity and specificity of s-p53-Abs detection of a new electrochemiluminescence immunoassay (ECLIA; Elecsys anti-p53). METHODS: Elecsys anti-p53 assay was used to analyze the level of s-p53-Abs in blood sera from patients with esophageal or colorectal cancer taken before treatment. Control blood sera from healthy volunteers, patients with benign diseases, and patients with autoimmune diseases served as a reference. In addition, squamous cell carcinoma antigen (SCC-Ag) and cytokeratin 19 fragments (CYFRA21-1) were assessed in patients with esophageal cancer, and carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 were assessed in patients with colorectal cancer. RESULTS: Samples from 281 patients with esophageal cancer, 232 patients with colorectal cancer, and 532 controls were included in the study. The median value of s-p53-Abs in control samples was < 0.02 µg/mL (range < 0.02-29.2 µg/mL). Assuming 98% specificity, the cut-off value was determined as 0.05 µg/mL. s-p53-Abs were detected in 20% (57/281) of patients with esophageal cancer and 18% (42/232) of patients with colorectal cancer. In combination with SCC-Ag and CEA, respectively, s-p53-Abs detected 51% (144/281) of patients with esophageal and 53% (124/232) of patients with colorectal cancer. CONCLUSIONS: The new s-p53-Abs assay Elecsys anti-p53 was useful in detecting esophageal and colorectal cancers with high specificity. Adding s-p53-Abs to conventional markers significantly improved the overall detection rates.

Rationale for and clinical development of anti-fractalkine antibody in rheumatic diseases.

Introduction: Rheumatic diseases are inflammatory diseases that damage target organs via multiple subsets of immune cells. Fractalkine (FKN) acts as chemoattractant as well as adhesion molecule. It contributes to the pathogenesis of rheumatoid arthritis (RA) and other rheumatic diseases through multiple mechanisms: the migration of monocytes and cytotoxic effector T cells, the proliferation and activation of fibroblast-like synoviocytes, angiogenesis, and osteoclastogenesis. FKN has potential as a new therapeutic target, and clinical trials on anti-FKN monoclonal antibodies for RA are ongoing. FKN-targeted therapy has been developed and a humanized anti-FKN monoclonal antibody is currently being tested in phase 2 clinical trials. Areas covered: This review summarizes accumulated evidence on the involvement of FKN in RA and other rheumatic diseases, including systemic lupus erythematosus (SLE), systemic sclerosis, inflammatory myositis, Sjögren's syndrome (SS), osteoarthritis, and systemic vasculitis. Expert opinion: A phase 1/2a clinical trial on anti-FKN demonstrated its safety, tolerability, and clinical efficacy. Anti-FKN therapy has potential in the treatment of atherosclerosis and interstitial lung diseases associated with RA. Based on recent findings, other rheumatic diseases, including SLE, polymyositis/dermatomyositis, and SS, may also be treated using anti-FKN therapy.

Efficacy of mycophenolate mofetil in Japanese patients with systemic lupus erythematosus.

OBJECTIVES: To assess the renal and non-renal efficacy of mycophenolate mofetil (MMF) in Japanese patients with systemic lupus erythematosus (SLE). METHODS: We conducted a retrospective study to assess the renal and non-renal efficacies of MMF in Japanese patients with systemic lupus erythematosus (SLE). We analyzed 14 patients with lupus nephritis (LN) who were given MMF, and 13 patients who received monthly intravenous cyclophosphamide (IVCY) as induction therapy, and a further 19 patients without LN who were treated with MMF, and 13 patients who took tacrolimus (TAC) to reduce glucocorticoid dosages. We assessed the therapeutic effects of each therapeutic regime on renal and non-renal disease manifestations over a six-month period after treatment initiation. RESULTS: Median urine protein to creatinine ratios in the MMF and IVCY groups significantly decreased from 2.2 to 0.7 g/gCr and from 3.3 to 0.5 g/gCr, respectively. Significant improvements in serum immunological variables (serum complements C3 and C4 and the anti-double stranded DNA antibody) and reductions in the SLE disease activity index (SLEDAI) and daily prednisolone dosages were observed in each group with LN. MMF and TAC significantly improved SLEDAI and serum immunological variables and reduced daily prednisolone dosages in patients without LN. CONCLUSION: The present results demonstrated that MMF might be an effective treatment for renal and non-renal manifestations in Japanese patients with SLE and has potential as a good therapeutic alternative and steroid-sparing agent.

Successful Treatment of IgA Vasculitis Complicated with Bowel Perforation and Crescentic Glomerulonephritis by Combination Therapy of Glucocorticoid, Cyclosporine and Factor XIII Replacement.

We report the findings of an 18-year-old boy with immunoglobulin A vasculitis (IgAV) complicated with bowel perforation and nephritis. He presented with abdominal pain, arthralgia and palpable purpura. Massive proteinuria developed during his clinical course. The patient was treated successfully using combination therapy of glucocorticoid (GC), cyclosporine (CYA) and factor XIII (F XIII) replacement. A standard treatment strategy for severe IgAV patients has not been established due to its rarity. Combination therapy using GC, CYA and F XIII replacement should be considered for severe IgAV patients.

Resistin upregulates chemokine production by fibroblast-like synoviocytes from patients with rheumatoid arthritis.

BACKGROUND: Adipokines are bioactive hormones secreted by adipose tissues. Resistin, an adipokine, plays important roles in the regulation of insulin resistance and inflammation. Resistin levels are known to be increased in the serum and synovial fluid of rheumatoid arthritis (RA) patients. However, the pathogenic role of resistin in RA has not yet been elucidated. METHODS: The expression of resistin and adenylate cyclase-associated protein 1 (CAP1), a receptor for resistin, was examined immunohistochemically in synovial tissue. CAP1 expression in in vitro cultured fibroblast-like synoviocytes (FLSs) was assessed with a reverse transcription-polymerase chain reaction (PCR) and western blotting. The gene expression of resistin-stimulated FLSs was evaluated by RNA sequencing (RNA-Seq) and quantitative real-time PCR. Concentrations of chemokine (C-X-C motif) ligand (CXCL) 8, chemokine (C-C motif) ligand (CCL) 2, interleukin (IL)-1ß, IL-6 and IL-32 in culture supernatants were measured by enzyme-linked immunosorbent assay. Small interfering RNA (siRNA) for CAP1 was transfected into FLSs in order to examine inhibitory effects. RESULTS: The expression of resistin and CAP1 in synovial tissue was stronger in RA than in osteoarthritis (OA). Resistin was expressed by macrophages in the RA synovium, while CAP1 was expressed by macrophages, FLSs and endothelial cells. In vitro cultured RA FLSs also expressed CAP1. RNA-Seq revealed that the expression levels of 18 molecules were more than twofold higher in resistin-stimulated FLSs than in unstimulated FLSs. Seven chemokines, CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL8, and CCL2, were included among the 18 molecules. Increases induced in the expression of CXCL1, CXCL8, and CCL2 by the resistin stimulation were confirmed by real-time PCR. The stimulation with resistin increased the protein levels of CXCL8 and CCL2 produced by RA FLSs, and the upregulated expression of CXCL8 was inhibited by the abrogation of CAP1 by siRNA for CAP1. Production of IL-6 by FLSs was also increased by resistin. Expression of IL-1ß and IL-32 was not detected by ELISA. CONCLUSIONS: Resistin contributes to the pathogenesis of RA by increasing chemokine production by FLSs via CAP1 in synovial tissue.

The growth factor midkine may play a pathophysiological role in rheumatoid arthritis.

OBJECTIVES: Midkine (MK) is involved in cell proliferation, differentiation, migration, and survival. In this study, we measured serum MK levels in rheumatoid arthritis (RA) and investigated the correlation of serum MK with RA disease activity. Expression and effect of MK in RA synovial tissue were also examined. METHODS: Serum MK and production of inflammatory mediators by rheumatoid synovial fibroblasts (RSFs) were measured by enzyme-linked immunosorbent assay. MK expression in synovial tissue was examined by immunohistochemistry. MK receptor expression was analyzed by RT-PCR and Western blotting. RESULTS: RA patients had a significantly higher serum MK level than healthy controls. In RA patients, the MK level was correlated with DAS28-ESR, disability index of the Health Assessment Questionnaire, and rheumatoid factor level. The serum MK level tended to be decreased by anti-TNF therapy. MK was expressed by synovial lining cells in RA synovial tissues and it enhanced the production of IL-6, IL-8, and CCL2 by RSFs. RSFs expressed LDL receptor-related protein 1, candidate receptor for MK. CONCLUSIONS: The serum MK level could be a marker of disease activity in RA and an indicator of a poor prognosis. MK may have a role in the pathogenesis of RA via induction of inflammatory mediators.

Leptin stimulates interleukin-6 production via janus kinase 2/signal transducer and activator of transcription 3 in rheumatoid synovial fibroblasts.

OBJECTIVES: The aim of this study was to determine the influence of leptin on the production of proinflammatory cytokines by rheumatoid synovial fibroblasts (RSFs). METHODS: Synovial tissue was obtained from patients with rheumatoid arthritis (RA). Leptin receptor mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR). Productions of mRNA and protein of interleukin (IL)-1ß, tumour necrosis factor-α (TNF-α), and IL-6 in the culture medium were detected by real-time PCR and ELISA kit, respectively. Small interfering RNA (siRNA) was transfected into RSF to down-regulate the expression of leptin receptor. Effects of inhibitors of janus kinase 2 (JAK2), phosphatidylinositol 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK) on IL-6 production were evaluated. Phosphorylation of signal transducer and activator of transcription 3 (STAT3) in RSF were determined by Western blot analysis. RESULTS: We detected leptin receptor mRNAs in RSFs. Expression of IL-1ß and IL-6 mRNA was enhanced in a concentration-dependent manner by addition of leptin to RSFs. IL-6 secretion by RSFs showed an increase after leptin stimulation. Leptin-induced production of IL-6 by RSFs was decreased after exposure to siRNA targeting leptin receptor (Ob-Rb). A JAK2 inhibitor, but not PI3K and MAPK inhibitors, decreased leptin-induced IL-6 production. Enhanced phosphorylation of STAT3 was observed in RSFs after stimulation by leptin. CONCLUSIONS: Leptin may be one of the proinflammatory cytokines that up-regulates IL-6 production in RSFs via activation of JAK2/STAT3. Leptin and JAK/STAT pathway may represent a new alternative therapeutic target in the treatment of RA.

Systemic lupus erythematosus complicated by recurrent pneumothorax: Case report and literature review.

Pneumothorax is a rare pleuropulmonary manifestation of systemic lupus erythematosus. We encountered a 37-year-old Japanese woman who had systemic lupus erythematosus complicated by recurrent pneumothorax during treatment for recurrent serositis with glucocorticoid therapy. She was admitted for the third episode of lupus peritonitis in December 2005. Intravenous cyclophoshamide and increased dose of oral prednisolone were administered. In early January 2006, hemoptysis was observed and bronchofiberscopy revealed hemorrhage from the left lower lobe. After intravenous methylprednisolone pulse therapy and oral cyclosporine therapy were added, pleurisy and pulmonary hemorrhage improved. On February 22nd, she suddenly developed pneumothorax on the right side, followed by pneumothorax on the left side after 2 days. This pneumothorax on the left side did not improve despite chest tube drainage for over one month. She underwent thoracoscopic partial lobectomy of lower lobe of the left lung, and her symptoms improved. Review of the literature identified 10 case reports of systemic lupus erythematosus complicated by pneumothorax. All of the patients including our case had underlying pulmonary lesions, and 9/11 patients had pleurisy. Besides 10/11 patients received glucocorticoid therapy before the occurrence of pneumothorax. Tissue fragility caused by these factors might contribute to the complication of pneumothorax in patients with systemic lupus erythematosus.