Protective effect of clusterin against interleukin-1ß-induced apoptosis and inflammation in human knee osteoarthritis chondrocytes.

Chondrocyte apoptosis is recognized as one of the pathological features involved in cartilage degeneration driving the onset and progression of knee osteoarthritis (OA). This study aimed to determine the molecular mechanism underlying the effect of clusterin (CLU), anti-apoptotic molecule, in human knee OA chondrocytes. Primary knee OA chondrocytes were isolated from the cartilage of knee OA patients and divided into five groups: (1) the cells treated with interleukin (IL)-1ß, (2) CLU alone, (3) a combination of IL-1ß and CLU, (4) LY294002 (PI3K inhibitor) along with IL-1ß and CLU, and (5) the untreated cells. Production of apoptotic, inflammatory, anabolic, and catabolic mediators in knee OA chondrocytes was determined after treatment for 24 h. Our in vitro study uncovered that CLU significantly suppressed the production of inflammatory mediators [nitric oxide (NO), IL6, and tumor necrosis factor (TNF)-α] and apoptotic molecule (caspase-3, CASP3). CLU significantly upregulated messenger ribonucleic acid (mRNA) expressions of anabolic factors [SRY-box transcription factor-9 (SOX9) and aggrecan (ACAN)], but significantly downregulated mRNA expressions of IL6, nuclear factor kappa-B (NF-κB), CASP3, and matrix metalloproteinase-13 (MMP13). Anti-apoptotic and anti-inflammatory effects of CLU were mediated through activating PI3K/Akt signaling pathway. The findings suggest that CLU might have beneficial effects on knee OA chondrocytes by exerting anti-apoptotic and anti-inflammatory functions via PI3K/Akt pathway, making CLU a promising target for potential therapeutic interventions in knee OA.

Cartilage oligomeric matrix protein as a potential biomarker for knee osteoarthritis.

Aims: This study aimed to determine the expression and clinical significance of a cartilage protein, cartilage oligomeric matrix protein (COMP), in knee osteoarthritis (OA) patients. Methods: A total of 270 knee OA patients and 93 healthy controls were recruited. COMP messenger RNA (mRNA) and protein levels in serum, synovial fluid, synovial tissue, and fibroblast-like synoviocytes (FLSs) of knee OA patients were determined using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and immunohistochemistry. Results: COMP protein levels were significantly elevated in serum and synovial fluid of knee OA patients, especially those in the advanced stages of the disease. Serum COMP was significantly correlated with radiological severity as well as measures of body composition, physical performance, knee pain, and disability. Receiver operating characteristic curve analysis unveiled a diagnostic value of serum COMP as a biomarker of knee OA (41.64 ng/ml, area under the curve (AUC) = 1.00), with a sensitivity of 99.6% and a specificity of 100.0%. Further analysis uncovered that COMP mRNA expression was markedly upregulated in the inflamed synovium of knee OA, consistent with immunohistochemical staining revealing localization of COMP protein in the lining and sub-lining layers of knee OA inflamed synovium. Most notably, relative COMP mRNA expression in knee OA synovium was positively associated with its protein levels in serum and synovial fluid of knee OA patients. In human knee OA FLSs activated with tumour necrosis factor-alpha, COMP mRNA expression was considerably up-regulated in a time-dependent manner. Conclusion: All results indicate that COMP might serve as a supportive diagnostic marker for knee OA in conjunction with the standard diagnostic methods.

Effect of galectin-3 on synovial inflammation in knee osteoarthritis via stimulating phosphatidylinositol-3-kinase/Akt pathway.

Galectin-3 (Gal-3), a glycan-binding protein responsible for inflammation, has been reportedly implicated in inflammatory arthritis. This study aimed to determine clinical and pathological effects of Gal-3 on inflammation in knee osteoarthritis (OA). Gal-3 mRNA and protein levels in synoviocytes, synovium, synovial fluid, and plasma of knee OA patients were determined using real-time polymerase chain reaction, immunohistochemistry, and enzyme-linked immunosorbent assay. Signaling mechanism underlying inflammatory effect of Gal-3 was further elucidated in human knee OA synoviocytes. Clinical study uncovered significant increases in plasma and synovial fluid Gal-3 levels in knee OA patients, particularly those with advanced-stage. In knee OA patients, plasma Gal-3 was significantly associated with radiographic severity and indicators of body composition, physical performance, and knee pain and disability. In the inflamed synovium of knee OA patients, further analysis depicted a marked up-regulation of Gal-3 mRNA expression, consistent with immunohistochemical analysis showing localization of Gal-3 protein in the lining and sublining layers of the inflamed synovium. An in vitro study unveiled that aberrant Gal-3 mRNA expression was regulated by tumor necrosis factor (TNF)-α in knee OA synoviocytes. Gal-3 significantly enhanced production of NO and IL-6, up-regulated mRNA expressions of IL-6, NF-κB, and MMP-13, and down-regulated mRNA expressions of ACAN and SOX-9 via stimulating Akt phosphorylation in knee OA synoviocytes. Gal-3 exerted an inflammatory action, which might emerge as a possible mediator of synovitis and cartilage degeneration in knee OA.

Clusterin exacerbates interleukin-1ß-induced inflammation via suppressing PI3K/Akt pathway in human fibroblast-like synoviocytes of knee osteoarthritis.

This study aimed to examine, a multifaceted chaperon-like protein exerting anti-inflammatory action, clusterin (CLU), mRNA and protein levels in the systemic and local joint environment of knee osteoarthritis (OA) patients and to determine whether CLU inhibited interleukin (IL)-1ß-induced inflammation in knee OA fibroblast-like synoviocytes (FLSs) through modulating phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway. CLU protein and mRNA expressions in the synovium and its protein levels in plasma and synovial fluid of knee OA patients were measured using immunohistochemistry, real-time PCR, and ELISA, respectively. Anti-inflammatory effect of CLU was further elucidated in knee OA FLSs treated with IL-1ß in the absence or presence of CLU, CLU alone, or PI3K inhibitor (LY294002) along with IL-1ß and CLU. In a clinical study, compared with knee OA patients without synovitis, CLU protein and mRNA were expressed in the synovium of knee OA patients with synovitis, especially those with high-grade, consistent with analyses of its plasma and synovial fluid levels. CLU mRNA and protein levels were both associated with synovitis severity. An in vitro study uncovered that CLU significantly alleviated IL-1ß-induced overproduction of nitric oxide and IL-6 in knee OA FLSs. Furthermore, CLU significantly attenuated inflammation and extracellular matrix degradation induced by IL-1ß via down-regulating expressions of IL-6, nuclear factor kappa B, and matrix metalloproteinase-13. Mechanistically, CLU significantly impeded IL-1ß-induced Akt phosphorylation in knee OA FLSs, in line with addition of LY294002 along with IL-1ß and CLU. These findings suggest that CLU may have potential as a novel therapeutic target for synovitis and cartilage destruction in knee OA.

Systemic cytokine profiles in biliary atresia.

BACKGROUND: Inflammation and immune dysregulation persuade biliary duct injury in biliary atresia (BA), a leading cause of pediatric liver transplantation given lack of specific biomarkers. We aimed to determine associations between systemic cytokine profiles and clinical parameters in BA patients and to identify potential BA biomarkers. METHODS: Systemic levels of 27 cytokines were measured in 82 BA patients and 25 healthy controls using a multiplex immunoassay. Relative mRNA expressions of candidate cytokines in 20 BA livers and 5 non-BA livers were assessed using quantitative real-time PCR. RESULTS: Higher levels of 17 cytokines including IL-1ß, IL-6, IL-7, IL-8, IL-9, IL-2, IL-15, eotaxin, IP-10, MCP-1, MIP-1α, MIP-1ß, G-CSF, IL-1ra, IL-4, IL-5, and IL-10 and lower levels of IFN-α and PDGF were significantly associated with BA. In BA patients, increased levels of IL-7, eotaxin, IP-10, and IL-13 were significantly associated with unfavorable outcomes including jaundice, fibrosis, and portal hypertension. Indeed, systemic levels of those cytokines were significantly correlated with clinical parameters indicating jaundice, fibrosis, and hepatic dysfunction in BA patients. Out of 27 cytokines, 4 (IL-8, IP-10, MCP-1, and PDGF) had potential as sensitive and specific biomarkers of BA. Of these, higher IL-8 levels were significantly associated with reduced survival of BA. In BA livers, relative mRNA expressions of IL-8, IP-10, and MCP-1 were significantly up-regulated. CONCLUSIONS: Higher levels of several cytokines including inflammatory cytokines, immunomodulatory cytokines, chemokines, and anti-inflammatory cytokines and lower levels of growth factors would reflect inflammatory and immune responses related to BA development. Among 27 cytokines, plasma IL-8 might have great potential as a diagnostic and prognostic biomarker for BA.

Clusterin Is Associated with Systemic and Synovial Inflammation in Knee Osteoarthritis.

OBJECTIVES: This study aimed to determine possible associations between transcriptional and translational levels of clusterin (CLU) in the systemic and local joint environments with the severity of knee osteoarthritis (OA) and to investigate CLU mRNA expression in knee OA fibroblast-like synoviocytes (FLSs) stimulated with tumor necrosis factor-α. DESIGN: Circulating and synovial fluid CLU levels in 259 knee OA patients were quantified using an enzyme-linked immunosorbent assay. Relative CLU mRNA expression in 50 knee OA synovial tissues and 4 knee OA FLSs was determined using real-time polymerase chain reaction. RESULTS: Plasma CLU levels of knee OA patients were significantly higher than paired synovial fluid samples. Compared with early-stage knee OA patients, those with advanced-stage OA had considerably increased plasma and synovial fluid CLU levels. There were significant positive associations of plasma and synovial fluid CLU levels with radiographic severity of knee OA. Plasma CLU levels were directly correlated with its synovial fluid levels and high-sensitivity C-reactive protein levels in the patients. Receiver-operating characteristic curve analysis unveiled the potential utility of plasma CLU as a novel biomarker for knee OA severity (AUC = 0.80), with a sensitivity of 71.4% and a specificity of 73.3%. Marked upregulation of CLU mRNA expression was observed in both the inflamed synovial tissues and FLSs of knee OA. CONCLUSION: Increased CLU mRNA and protein levels in the systemic and local joint environments of knee OA might reflect knee OA severity, especially systemic and synovial inflammation.