Yong-Gil Kim

Advanced glycation end products increases matrix metalloproteinase-1, -3, and -13, and TNF-α in human osteoarthritic chondrocytes

We investigated the effects of advanced glycation end products (AGE) which accumulate in articular cartilage with age in human osteoarthritic chondrocytes. We found AGE‐BSA significantly increased MMP‐1, ‐3, and ‐13, and TNF‐α in a dose‐dependent manner. AGE‐BSA‐stimulated JNK, p38, and ERK and NF‐κB activity. The stimulatory effect of AGE‐BSA on MMP‐1, ‐3, and ‐13 were reversed by treatment with specific JNK, p38 inhibitors, suggesting JNK and p38 are involved in AGE‐BSA‐induced MMPs and TNF‐α. We also observed that NF‐κB is involved in AGE‐BSA‐induced TNF‐α. Pretreatment with soluble receptor for AGE (sRAGE) also reduced AGE‐stimulated MMPs and TNF‐α, implicating the involvement of receptor for AGE (RAGE). In conclusion, accumulation of AGE may have a role in the development of osteoarthritis by increasing MMP‐1, ‐3, and ‐13, and TNF‐α.

Interleukin-34 produced by human fibroblast-like synovial cells in rheumatoid arthritis supports osteoclastogenesis.

IntroductionInterleukin-34 (IL-34) is a recently defined cytokine, showing a functional overlap with macrophage colony stimulating factor (M-CSF). This study was undertaken to address the expression of IL-34 in rheumatoid arthritis (RA) patients and to investigate its regulation and pathogenic role in RA.MethodsIL-34 levels were determined in the RA synovium, synovial fluid (SF) and fibroblast-like synovial cells (FLS) by immunohistochemistry, real-time PCR, enzyme-linked immunosorbent assay and immunoblotting. RA activity was assessed using Disease Activity Score 28 (DAS28) activity in the plasma collected at baseline and one year after treatment. Conditioned media (CM) were prepared from RA FLS culture with tumor necrosis factor alpha (TNFα) for 24 hours and used for functional assay.ResultsIL-34 was expressed in the synovium, SF, and FLS from RA patients. The production of IL-34 in FLS was up-regulated by TNFα in RA samples compared with osteoarthritis (OA) patients. Importantly, the preferential induction of IL-34 rather than M-CSF by TNFα in RAFLS was mediated by the transcription factor nuclear factor kappa B (NF-κB) and activation of c-Jun N-terminal kinase (JNK). IL-34 elevation in plasma from RA patients was decreased after the administration of disease-modifying anti-rheumatic drugs (DMARDs) in accordance with a decrease in DAS28. CM from RAFLS cultured with TNFα promoted chemotactic migration of human peripheral blood mononuclear cells (PBMCs) and subsequent osteoclast (OC) formation, effects that were attenuated by an anti-IL-34 antibody.ConclusionsThese data provide novel information about the production of IL-34 in RA FLS and indicate that IL-34 is an additional osteoclastogenic factor regulated by TNFα in RA, suggesting a discrete role of IL-34 in inflammatory RA diseases.

Evaluation of disease activity using F-18 FDG PET-CT in patients with Takayasu arteritis.

Purpose of the Report: To evaluate the usefulness of F-18 fluoro-fluorodeoxygulose positron emission tomography computed tomography (F-18 FDG PET-CT) in detecting clinically defined active disease in patients with Takayasu arteritis. Methods: F-18 FDG PET-CT was performed in 32 patients with Takayasu arteritis. Disease activity was assessed clinically by the National Institutes of Health (NIH) criteria. In 10 of the 32 patients, F-18 FDG PET-CT was performed while the patients were taking immunosuppressive drugs. Two nuclear physicians visually assessed the degree of F-18 FDG uptake in the walls of the aorta, its major branches and the pulmonary artery using a 4-point scale from grade 0 to III. F-18 FDG uptake greater than grade I in the thoracic aorta or greater than grade 0 in other areas were interpreted as active vasculitic lesions. Results: Ten patients had active lesions on F-18 FDG PET-CT. According to the NIH criteria, 9 patients had active disease and 23 had inactive disease. Compared with disease activity assessed by the NIH criteria, F-18 FDG PET-CT had a sensitivity of 78% and a specificity of 87%. The erythrocyte sedimentation rate and CRP levels were significantly higher in F-18 FDG PET-CT-positive than in F-18 FDG PET-CT-negative patients. There was no significant difference in the proportion of positive PET scans according to the use of glucocorticoids. Conclusions: The sensitivity of F-18 FDG PET-CT for detecting active disease was higher in patients with higher erythrocyte sedimentation rate values. Although the specificity of F-18 FDG PET-CT was high, owing to the low sensitivity of the NIH criteria in detecting active disease, further studies are needed.

Interleukin-33 stimulates formation of functional osteoclasts from human CD14(+) monocytes.

Interleukin (IL)-33 is a recently described pro-inflammatory cytokine. Here we demonstrate IL-33 as a regulator of functional osteoclasts (OCs) from human CD14+ monocytes. IL-33 stimulates formation of tartrate-resistant acid phosphatase (TRAP)+ multinuclear OCs from monocytes. This action was suppressed by anti-ST2 antibody, suggesting that IL-33 acts through its receptor ST2, but not by the receptor activator of NF-κB ligand (RANKL) decoy, osteoprotegerin, or anti-RANKL antibody. IL-33 stimulated activating phosphorylations of signaling molecules in monocytes that are critical for OC development. These included Syk, phospholipase Cγ2, Gab2, MAP kinases, TAK-1, and NF-κB. IL-33 also enhanced expression of OC differentiation factors including TNF-α receptor-associated factor 6 (TRAF6), nuclear factor of activated T cells cytoplasmic 1, c-Fos, c-Src, cathepsin K, and calcitonin receptor. IL-33 eventually induced bone resorption. This study suggests that the osteoclastogenic property of IL-33 is mediated through TRAF6 as well as the immunoreceptor tyrosine-based activation motif-dependent Syk/PLCγ pathway in human CD14+ monocytes.

Effect of interleukin‐32γ on differentiation of osteoclasts from CD14+ monocytes

OBJECTIVE Interleukin-32 (IL-32) induces various inflammatory molecules in human monocytes and differentiation of monocytes into macrophage-like cells. This study was undertaken to evaluate the effects of IL-32gamma, the most biologically active isoform, on the differentiation and activation of osteoclasts. METHODS CD14+ monocytes were obtained from healthy volunteers, and samples of synovial tissue and synovial fluid were obtained from patients with rheumatoid arthritis (RA) and patients with osteoarthritis (OA). The concentration and expression levels of IL-32gamma in RA and OA samples were evaluated by enzyme-linked immunosorbent assay and immunoblotting, respectively. To examine the osteoclastogenic effects and functional activities, isolated monocytes were treated with either IL-32gamma or IL-17 in the presence or absence of soluble RANKL (sRANKL) on a culture system and on Osteologic disks. The expression of RANKL and osteoprotegerin (OPG) messenger RNA (mRNA) in RA fibroblast-like synoviocytes (FLS) was measured using reverse transcription-polymerase chain reaction (PCR) and real-time PCR. RESULTS The concentration and expression levels of IL-32gamma were higher in the RA samples than in the OA samples. Upon costimulation with sRANKL, the osteoclast count and resorbed area increased more significantly in the IL-32gamma-stimulated cultures than in those stimulated with IL-17. In the IL-32gamma-treated group without sRANKL stimulation, osteoclasts were differentiated, but the cells displayed low resorption activity. In RA FLS, RANKL mRNA expression increased in the presence of both IL-32gamma and IL-17. However, transcription of OPG decreased following IL-32gamma stimulation, resulting in a significant increase in the RANKL:OPG ratio. CONCLUSION Our results suggest that IL-32gamma is a potent mediator of active osteoclast generation in the presence of sRANKL. Moreover, this novel cytokine creates more favorable conditions for osteoclastogenesis in the RA joint by increasing the RANKL:OPG ratio in FLS.

Idiopathic Inflammatory Myopathy Associated with Malignancy: A Retrospective Cohort of 151 Korean Patients with Dermatomyositis and Polymyositis

Objective. To define the standardized incidence ratio (SIR) of malignancy and factors associated with malignancies in Korean patients with dermatomyositis (DM) and polymyositis (PM). Methods. The demographic, clinical, and laboratory features of 151 patients diagnosed with DM/PM were compared in patients with and without malignancies. Results. Malignancies were found in 23 of 98 patients with DM (23.5%) and in 2 of 53 with PM (3.8%). Lung cancer (8 patients) was the most common malignancy. Compared with the period-specific, sex-matched, and age-matched Korean population, the SIR for malignancy in patients with DM was 14.2 (95% CI 9.0–21.3). Univariate analysis showed that factors associated with malignancy included older age (p < 0.001), DM (p = 0.002), dysphagia (p < 0.001), the absence of interstitial lung disease (ILD; p = 0.001), and lower elevations in aspartate aminotransferase (p = 0.005) and lactate dehydrogenase concentrations (p < 0.001). Multivariate analysis showed that factors independently associated with malignancy included older age (per 10 years, OR 2.3, 95% CI 1.6–3.5, p < 0.001), DM (OR 5.9, 95% CI 1.3–26.2, p = 0.020), dysphagia (OR 2.6, 95% CI 1.2–6.6, p = 0.042), and the absence of ILD (OR 0.1, 95% CI 0.01–0.9, p = 0.040). Conclusion. DM was associated with a greater risk of concomitant malignancies, especially lung cancer, than PM. Independent factors associated with malignancies in patients with DM/PM were older age, the presence of dysphagia, and the absence of ILD.

Clinical features and outcomes of microscopic polyangiitis in Korea.

Microscopic polyangiitis (MPA) is a systemic vasculitis affecting small vessels. To determine the clinical features and outcomes of MPA in Korean patients, we retrospectively reviewed the medical records of patients diagnosed with MPA at a single medical center in Korea between 1989 and 2006. The 18 patients who met the Chapel Hill criteria for MPA had a mean (±SD) age at the time of diagnosis of 62.4±12.7 yr. Renal manifestations and general symptoms were the most common features of MPA, with lung involvement also very common. Antineutrophil cytoplasmic antibodies (ANCA) were present in 17 of the 18 patients (94%). Of 17 patients treated with steroids and cyclophosphamide, 11 (65%) had stable or improved course. One patient treated with steroids without cyclophosphamide showed disease progression. Ten of the 18 patients (56%) died at a median follow-up of 8 months. MPA in Korean patients was distinguished by a higher rate of lung involvement, especially alveolar hemorrhage, which was the leading cause of death in our patients. Korean patients were also older at MPA onset and were more likely positive for ANCA. Other overall clinical manifestations did not differ significantly.

Alpha-lipoic acid inhibits TNF-α induced NF-κB activation through blocking of MEKK1–MKK4–IKK signaling cascades

The therapeutic effects of alpha-lipoic acid (alpha-LA) via NF-kappa B down regulation were demonstrated on joint inflammation and erosion in an animal model. In this study, we investigated how alpha-LA inhibits the pathway of NF-kappa B activation by TNF-alpha via the mitogen-activated protein kinase (MAPK) pathway in rheumatoid arthritis (RA) fibroblast-like synovial cells (FLS). FLS were stimulated with TNF-alpha following pre-treatment with or without alpha-LA. Electrophoretic mobility shift assays (EMSA) revealed that TNF-alpha activates NF-kappa B in FLS. This was inhibited by alpha-LA at concentrations of 1 mM. TNF-alpha induced IKK mediated phosphorylation of GST-I kappa B and pre-treatment with alpha-LA inhibited this pathway. FLS constitutively express MEKK1, MEKK2, MEKK3, and TAK1 and that their levels are unaffected by TNF-alpha or alpha-LA. Immunoprecipitation using anti-MEKK1 antibody phosphorylated GST-I kappa B and pre-treating the cells with alpha-LA could abolish the reaction. FLS were immunoprecipitated using an antibody to MEKK1, and MKK4 was coprecipitated with MEKK1. In addition, immune complexes precipitated with anti-MKK4 antibody phosphorylated GST-I kappa B, and pre-treatment with alpha-LA inhibited the phosphorylation. Immunoprecipitation assay showed that MEKK1, MKK4, IKK-alpha, IKK-beta, I kappa B, and NF-kappa B comprised immunocomplex. It can be concluded that TNF-alpha activates NF-kappa B in FLS through MEKK1-MKK4-IKK signaling complex, and alpha-LA inhibits this signaling at the level of or upstream of IKK-alpha and IKK-beta.

The difference between lupus nephritis class IV-G and IV-S in Koreans: focus on the response to cyclophosphamide induction treatment

OBJECTIVES To evaluate the response to induction therapy with intravenous (i.v.) cyclophosphamide (CYC) in Korean patients with class IV-G (diffuse global proliferative glomerulonephritis) and class IV-S (diffuse segmental proliferative glomerulonephritis) lupus nephritis (LN) according to the classification system of the International Society of Nephrology/Renal Pathology Society (ISN/RPS). METHODS Of the 52 patients with biopsy-proven diffuse proliferative LN, who had been treated with i.v. CYC over a 10-yr period, 42 had been treated with i.v. CYC (equal to or more than 500 mg) for 6 consecutive months and had biopsy specimens containing more than nine glomeruli. The renal pathology of these 42 patients was reclassified according to the International Society of Nephrology and the Renal Pathology Society 2003 classification, and their renal response rates and laboratory indices after induction therapy were analysed. RESULTS Of the 42 patients assessed, 30 (71%) had IV-G and 12 (29%) had IV-S. Pre-treatment 24 h urinary protein was significantly higher and pre-treatment concentration of anti-dsDNA antibody was significantly lower in IV-G than in IV-S patients. Following induction therapy, complete remission rates were significantly higher in patients with IV-S (67%, 8/12) than in patients with IV-G (33%, 10/30) LN. CONCLUSIONS Class IV-G LN responded more poorly to induction therapy with i.v. CYC pulse than class IV-S LN.

Serum cholesterol in idiopathic and lupus-related protein-losing enteropathy.

Abstract The characteristics of protein-losing enteropathy were evaluated in patients with systemic lupus erythematosus. Among the patients with systemic lupus erythematosus (n = 380) in a tertiary hospital, we reviewed the records of seven patients with generalized edema, hypoalbuminemia without proteinuria and positive results on 99mTc-labelled human serum albumin scintigrams. Patient characteristics and laboratory findings were compared between these seven patients and patients with lupus enteritis (n = 15) or idiopathic protein-losing enteropathy (n = 11). Compared with the lupus enteritis patients, the erythrocyte sedimentation rate and serum total cholesterol levels were significantly increased in patients with systemic lupus erythematosus–related protein-losing enteropathy. Compared with idiopathic protein-losing enteropathy patients, the level of serum total cholesterol was significantly increased, but the level of serum albumin was decreased in patients with systemic lupus erythematosus–related protein-losing enteropathy. Among patients with systemic lupus erythematosus–related protein-losing enteropathy, four patients had high serum total cholesterol levels (≥248 mg/dL) and achieved complete remission after receiving high doses of steroid treatment. However, three patients who had low serum total cholesterol levels (≤219 mg/dL) responded poorly to the steroid-only treatment, and could achieve complete remission only after 3 months of cyclophosphamide pulse treatment with concurrent corticosteroid therapy. The levels of serum total cholesterol are intriguing feature in systemic lupus erythematosus–associated protein-losing enteropathy patients.