TLR3 signaling-induced interferon-stimulated gene 56 plays a role in the pathogenesis of rheumatoid arthritis.

Rheumatoid fibroblast-like synoviocytes (RFLS) have an important role in the inflammatory pathogenesis of rheumatoid arthritis (RA). Toll-like receptor 3 (TLR3) is upregulated in RFLS; its activation leads to the production of interferon-ß (IFN-ß), a type I IFN. IFN-stimulated gene 56 (ISG56) is induced by IFN and is involved in innate immune responses; however, its role in RA remains unknown. Therefore, the purpose of this study was to investigate the role of TLR3-induced ISG56 in human RFLS. RFLS were treated with polyinosinic-polycytidylic acid (poly I:C), which served as a TLR3 ligand. ISG56, melanoma differentiation-associated gene 5 (MDA5), and C-X-C motif chemokine ligand 10 (CXCL10) expression were measured using quantitative reverse transcription-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay. Using immunohistochemistry, we found that ISG56 was expressed in synovial tissues of patients with RA and osteoarthritis. Under poly I:C treatment, ISG56 was upregulated in RFLS. In addition, we found that the type I IFN-neutralizing antibody mixture suppressed ISG56 expression. ISG56 knockdown decreased CXCL10 expression and MDA5 knockdown decreased ISG56 expression. In addition, we found that ISG56 was strongly expressed in the synovial cells of patients with RA. TLR3 signaling induced ISG56 expression in RFLS and type I IFN was involved in ISG56 expression. ISG56 was also found to be associated with CXCL10 expression, suggesting that ISG56 may be involved in TLR3/type I IFN/CXCL10 axis, and play a role in RA synovial inflammation.

Possible involvement of DExD/H box helicase 60 in synovial inflammation of rheumatoid arthritis: role of toll-like receptor 3 signaling.

BACKGROUND: Innate immunity is known to be implicated in the etiology of synovitis in rheumatoid arthritis (RA). However, details of the molecular mechanisms have not been fully clarified. DExD/H-box helicase 60 (DDX60), a putative RNA helicase, is of consequence in anti-viral innate immune reactions followed by inflammation. Although DDX60 is involved in the pathogenesis of autoimmune diseases such as systemic lupus nephritis, the role of DDX60 in RA has not been elucidated. The objective of this study was to examine the expression and the role of DDX60 in RA synovial inflammation. METHODS AND RESULTS: DDX60 protein expression was investigated by immunohistochemistry in synovial tissues resected from 4 RA and 4 osteoarthritis (OA) patients. We found that synovial DDX60 expression was more intense in RA than in OA. Treatment of human rheumatoid fibroblast-like synoviocytes in culture with polyinosinic-polycytidylic acid, a Toll-like receptor 3 (TLR3) ligand, increased DDX60 protein and mRNA expression. A knockdown experiment of DDX60 using RNA interference revealed a decrease in the expression of poly IC-induced C-X-C motif chemokine ligand 10 (CXCL10) which induces lymphocyte chemotaxis. CONCLUSIONS: The synovial DDX60 was more expressed in RA patients than in OA. In human RFLS, DDX60 stimulated by TLR3 signaling affected CXCL10 expression. DDX60 may contribute to synovial inflammation in RA.

Distinction between benign and malignant soft tissue tumors based on an ultrasonographic evaluation of vascularity and elasticity.

The initial diagnostic distinction between benign and malignant soft tissue tumors is critical for decisions regarding the appropriate course of treatment. The current study aimed to evaluate the vascularity and elasticity of soft tissue tumors by superb microvascular imaging and shear wave elastography using ultrasonography (US), to determine their usefulness in distinguishing malignant soft tissue tumors, and to further establish the diagnostic accuracy and usefulness of a scoring system (SS) based on these evaluations. The present study used 167 lesions of soft tissue tumors examined by US prior to biopsy, surgery and pathological tissue diagnosis. The vascularity index (VI) and the maximal shear velocity (MSV), as indices of vascularity and elasticity respectively, were evaluated using US. The tumor size and depth were also evaluated via magnetic resonance imaging (MRI). Based on the odds ratio of these parameters determined by multivariate logistic regression analysis, an original SS was established to identify the malignancy of soft tissue tumors. VI and MSV exhibited significantly high values for malignant tumors. Tumor size was also significantly larger for malignant than benign tumors. The areas under the curves (AUCs) of the receiver operating characteristic analysis for VI, MSV and tumor size were 0.75, 0.84 and 0.69, respectively, indicating that these methods were effective for the diagnosis of malignancy. An original SS consisting of VI, MSV and tumor size, excluding tumor depth, was established, and revealed an AUC value of 0.90, with 93.6% sensitivity and 79.2% specificity for malignancy distinction. US evaluation of vascularity and elasticity was an effective technique to distinguish malignant soft tissue tumors, and the current SS based on US evaluations including tumor size via MRI demonstrated a high diagnostic accuracy for malignant soft tissue tumors.

Usefulness of serum hyaluronic acid levels as a predictor of incidence of hand osteoarthritis analyzed by longitudinal analysis from the Iwaki cohort.

The factors predicting hand osteoarthritis (HOA) in patients remain unknown. We aimed to investigate the usefulness of serum hyaluronic acid (sHA) levels in predicting HOA progression from a 6-year longitudinal epidemiological study. A total of 417 participants in the Iwaki cohort were followed-up over 6 years. Hand and knee radiographs taken at baseline and follow-up were scored according to Kellgren-Lawrence grades and Kallman score. Participants were classified into the HOA group and the non-HOA group. sHA levels at baseline were determined by ELISA. Correlations between sHA levels, the number of involved joints, and Kallman score were estimated. Factors related to the incidence or progression of HOA over 6 years were analyzed. The prevalence of HOA was 19.9% at baseline, and 3.6 ± 2.1 joints were involved. sHA levels in the HOA group at baseline were significantly higher than in the non-HOA group (p < 0.001) and correlated with the number of involved joints (r = 0.399, p < 0.001) and Kallman score (r = 0.540, p < 0.001). The incidence rate was 14.5%, and the progression rate was 46.1% over 6 years. Higher sHA levels at baseline were the risk factor of HOA incidence. Thus, sHA levels predicted the incidence of HOA over 6 years.

Role of MDA5 in regulating CXCL10 expression induced by TLR3 signaling in human rheumatoid fibroblast-like synoviocytes.

C-X-C motif chemokine 10 (CXCL10) is an inflammatory chemokine and a key molecule in the pathogenesis of rheumatoid arthritis (RA). Melanoma differentiation-associated gene 5 (MDA5) is an RNA helicase that plays a role in innate immune and inflammatory reactions. The details of the regulatory mechanisms of CXCL10 production and the precise role of MDA5 in RA synovitis have not been fully elucidated. The aim of this study was to examine the role of MDA5 in regulating CXCL10 expression in cultured human rheumatoid fibroblast-like synoviocytes (RFLS). RFLS was stimulated with Toll-like receptor 3 (TLR3) ligand polyinosinic:polycytidylic acid (poly I:C), a synthetic double-stranded RNA mimetic. Expression of interferon beta (IFN-ß), MDA5, and CXCL10 was measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting, and enzyme-linked immunosorbent assay. A neutralizing antibody of IFN-ß and siRNA-mediated MDA5 knockdown were used to determine the role of these molecules in regulating CXCL10 expression downstream of TLR3 signaling in RFLS. Poly I:C induced IFN-ß, MDA5, and CXCL10 expression in a concentration- and time-dependent manner. IFN-ß neutralizing antibody suppressed the expression of MDA5 and CXCL10, and knockdown of MDA5 decreased a part of CXCL10 expression (p < 0.001). The TLR3/IFN-ß/CXCL10 axis may play a crucial role in the inflammatory responses in RA synovium, and MDA5 may be partially involved in this axis.

Long-term survival rate of closing wedge high tibial osteotomy with high valgus correction: a 15-year follow-up study.

PURPOSE: The influence of closing wedge high tibial osteotomy (CW-HTO) with high valgus correction on its survival is unclear. This study aimed to conduct a 15-year follow-up cohort study to estimate the long-term survival rate of CW-HTO. Factors related to poor outcomes were investigated. METHODS: A total of 159 knees in 123 patients were followed up, and 120 knees in 96 patients were enrolled for statistical analysis. Femorotibial angles were measured by standing anterior-posterior radiographs of the knee. Clinical objective evaluation was performed by the Japanese orthopaedic association (JOA) score of the knee, and scores lower than 70 points defined the poor result (PR) group. The survival rate of OW-HTO was estimated. Logistic regression analyses were performed to determine the risk factors for PR and conversion to total knee arthroplasty (TKA). RESULTS: A total of 16 knees in 15 patients (13.3%) underwent TKA 14.0 ± 4.8 (4-20) years after CW-HTO. The 5-year survival rate was 99.2%, 10-year was 96.7%, 15-year was 92.5%, and 86.7% at final follow-up (17.9 years). Based on the JOA score, 44 patients (35.8%) belonged to the PR group, and their risk factors were obesity (p = 0.018), low femorotibial angle (p = 0.019), low JOA score (p = 0.040), low knee extension angle (p = 0.045), and low knee flexion angle (p = 0.046). CONCLUSIONS: The 15-year survival rate of CW-HTO was 92.5%. While higher scores of objective outcomes were kept over long-term follow-up, the risk factors for a worsening score or TKA conversion were obesity and severity of preoperative knee symptoms.