Response In Osteoarthritis Chondrocytes Research Articles

Knockdown of DAPK1 attenuates IL-1β-induced extracellular matrix degradation and inflammatory response in osteoarthritis chondrocytes via regulating the p38 MAPK-signaling pathway.

To reveal the possible effects of death-associated protein kinase 1 (DAPK1) on the progression of osteoarthritis (OA) and the potential underlying mechanism. : The expression of DAPK1 in OA and normal samples and interleukin (IL)-1β-stimulated chondrocytes was analyzed by quantitative real-time polymerase chain reaction and Immunoblot assay. Cell viability, proliferation, and apoptosis in DAPK1-knockdown cells stimulated with IL-1β were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) solution, 5-ethynyl-2β-deoxyuridine staining and flow cytometry. The chondrocyte degradation and inflammatory response in IL-1β-induced chondrocytes were investigated by Immunoblot analysis and enzyme-linked-immunosorbent serologic assay. In addition, the effect of DAPK1 on p38 mitogen-activated protein kinase (MAPK) activation was analyzed by immunoblot assay. : This study revealed that DAPK1 was highly expressed in OA patients and IL-1β-induced chondrocytes. Down-regulation of DAPK1 enhanced IL-1β-induced chondrocyte proliferation. DAPK1 knockdown inhibited IL-1β-induced chondrocyte degradation. In addition, DAPK1 depletion inhibited IL-1β-induced chondrocyte inflammation. Mechanically, it was revealed that down--regulation of DAPK1 could inhibit the p38 MAPK pathway, and therefore affected progression of OA. : DAPK1 knockdown attenuates IL-1β-induced extracellular matrix degradation and inflammatory response in OA chondrocytes by regulating the p38 MAPK pathway.

Hypoxia Inducible Factor-1α Is a Regulator of Autophagy in Osteoarthritic Chondrocytes.

To investigate the relationship between hypoxia inducible factor-1α (HIF-1α) and the autophagic response in osteoarthritic chondrocytes (OA), under inflammatory insult as represented by in vitro OA model. Human chondrocyte cell line C28/I2 was cultured in both normoxic and hypoxic conditions and treated with interleukin-1β (IL1β) to emulate OA inflammatory insult in vitro. Cellular HIF-1α expression was silenced using siRNA transfection and cellular autophagic (P62/LC3II) response and OA chondrocyte damage (COL2A1/MMP13) related proteins were examined using western blotting. Cellular mitophagic (BNIP3/PINK1/Parkin) and apoptotic (Caspase/Cleaved Caspase 3) were also evaluated to assess mitophagy-mediated cell death due to HIF-1α silencing. Chondrocyte basal autophagy levels were higher in a HIF-1α elevated environment and was more resistant to IL1β-induced inflammatory insult. Increase in autophagic proteins showed better chondrocyte repair, which resulted a lower level of reactive oxygen species production, and lesser damage to chondrocyte integrity. Silencing HIF-1α activates cellular PINK1/Parkin and BNIP3 mitophagic proteins, which leads to the activation of Caspase/Cleaved Caspase 3 apoptotic cascade. Our results show that chondrocyte autophagy is dependent on HIF-1α expression, showing the importance of HIF-1α in hypoxic chondrocyte function in OA. Dysregulation of HIF-1α expression results in the activation of mitophagy-mediated apoptosis.

TGFβ1-Induced Transglutaminase-2 Triggers Catabolic Response in Osteoarthritic Chondrocytes by Modulating MMP-13.

Transforming growth factor beta 1 (TGFβ1) plays an essential role in maintaining cartilage homeostasis. TGFβ1 is known to upregulate anabolic processes in articular cartilage, but the role of TGFβ1 in chondrocyte catabolism remains unclear. Thus, we examined whether TGFβ1 increases catabolic processes in the osteoarthritic joint via transglutaminase 2 (TG2). In this study, we investigated whether interplay between TGFβ1 and TG2 mediates chondrocyte catabolism and cartilage degeneration in osteoarthritis. To investigate the role of TGFβ1 and TG2 in osteoarthritis, we performed immunostaining to measure the levels of TGFβ1 and TG2 in 6 human non-osteoarthritic and 16 osteoarthritic joints. We conducted quantitative reverse transcription polymerase chain reaction and western blot analysis to investigate the relationship between TGFβ1 and TG2 in chondrocytes and determined whether TG2 regulates the expressions of matrix metalloproteinase (MMP)-13, type II, and type X collagen. We also examined the extent of cartilage degradation after performing anterior cruciate ligament transection (ACLT) and destabilization of the medial meniscus (DMM) surgery in TG2 knock-out mice. We confirmed the overexpression of TGFβ1 and TG2 in human osteoarthritic cartilage compared with non-osteoarthritic cartilage. TGFβ1 treatment significantly increased the expression of TG2 via p38 and ERK activation. TGFβ1-induced TG2 also elevated the level of MMP-13 and type X collagen via NF-κB activation in chondrocytes. Cartilage damage after ACLT and DMM surgery was less severe in TG2 knock-out mice compared with wild-type mice. TGFβ1 modulated catabolic processes in chondrocytes in a TG2-dependent manner. TGFβ1-induced TG2 might be the therapeutic target for treating cartilage degeneration and osteoarthritis.

Stachydrine attenuates IL-1β-induced inflammatory response in osteoarthritis chondrocytes through the NF-κB signaling pathway

Osteoarthritis (OA) is a common degenerative joint disease that is closely associated with inflammation. Stachydrine (STA) is a bioactive alkaloid with anti-inflammatory activity. However, the role of STA in OA remains unknown. This study aimed to explore the effects of STA on OA chondrocytes in the presence of IL-1β. Primary human OA chondrocytes were pretreated with various concentrations of STA for 2 h and then stimulated with IL-1β for 24 h. Inflammatory mediators and cytokines including NO, PGE2, TNF-α and IL-6 in chondrocytes were detected to reflect inflammation status. Production of extracellular matrix (ECM) degrading enzymes including MMP-3, MMP-13, ADAMTS-4 and ADAMTS-5 in chondrocytes was measured using ELISA. The expression levels of iNOS, COX-2, p65, p-p65, p-IκBα, and IκBα were detected by Western blot analysis. Our results showed that STA significantly suppressed IL-1β-induced inflammation with decreased levels of inflammatory mediators and cytokines including NO, PGE2, iNOS, COX-2, TNF-α and IL-6. Treatment with STA suppressed the production of ECM degrading enzymes including MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 in IL-1β-induced chondrocytes. Furthermore, STA blocked the IL-1β-mediated potentiation of NF-κB pathway in chondrocytes. In conclusion, these findings demonstrated that STA protected chondrocytes from IL-1β-induced inflammation through the NF-κB signaling pathway.

Knockdown of TRIM8 Attenuates IL-1β-induced Inflammatory Response in Osteoarthritis Chondrocytes Through the Inactivation of NF-κB Pathway

Osteoarthritis (OA) is a degenerative joint disease associated with inflammatory response. Tripartite motif 8 (TRIM8) is a member of TRIM family that has been found to regulate inflammation. The present study was aimed to evaluate the role of TRIM8 in OA chondrocytes. Our results showed that TRIM8 expression was significantly increased in interleukin 1 beta (IL-1β)-stimulated OA chondrocytes. To knock down the TRIM8 expression in chondrocytes, the chondrocytes were transfected with si-TRIM8. Knockdown of TRIM8 attenuated IL-1β-induced production of inflammatory mediators including nitric oxide and prostaglandin E2. The increased expression levels of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1β-induced chondrocytes were suppressed by TRIM8 knockdown. The IL-1β-induced production of proinflammatory cytokines including TNF-α and IL-6 was significantly decreased after transfection with si-TRIM8. Besides, knockdown of TRIM8 mitigated the IL-1β-induced decrease in aggrecan and collagen-II proteins expression and increase in matrix-degrading enzymes in chondrocytes. Furthermore, TRIM8 knockdown prevented IL-1β-induced nuclear factor kappa B (NF-κB) activation in chondrocytes. Taken together, these findings indicated that knockdown of TRIM8 attenuates IL-1β-induced inflammatory response in OA chondrocytes through the inactivation of NF-κB pathway. Thus, targeting TRIM8 might provide therapeutic treatment for OA.

Salidroside attenuates interleukin-1β-induced inflammation in human osteoarthritis chondrocytes.

Salidroside, a bioactive constituent isolated from Rhodiola rosea, has been reported to have anti-inflammatory effects. However, the effects of salidroside on interleukin (IL)-1β-stimulated osteoarthritis (OA) chondrocytes remain to be elucidated. Thus, this study aimed to evaluate the anti-inflammatory effects of salidroside on IL-1β-stimulated human OA chondrocytes and explore its underlying mechanisms. Our results showed that salidroside significantly inhibited the production of nitric oxide and prostaglandin E-2, as well as suppressed the expression of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1β-stimulated chondrocytes ( P < .05). In addition, salidroside also suppressed IL-1β-induced matrix metalloproteinases production in human OA chondrocytes ( P < .05). Furthermore, pretreatment with salidroside prevented IL-1β-induced NF-κB activation in OA chondrocytes ( P < .05). In conclusion, the current study demonstrated that salidroside inhibited the IL-1β-induced inflammatory response in OA chondrocytes via inhibition of NF-κB activation.

Knockdown of PRMT1 suppresses IL-1β-induced cartilage degradation and inflammatory responses in human chondrocytes through Gli1-mediated Hedgehog signaling pathway.

Osteoarthritis (OA) is characterized by articular cartilage degradation and joint inflammation. The purpose of the present study is to elucidate the role of the specific function of PRMT1 in chondrocytes and its association with the pathophysiology of OA. We observed that the expression of PRMT1 was apparently upregulated in OA cartilage, as well as in chondrocytes stimulated with IL-1β. Additionally, knockdown of PRMT1 suppressed interleukin 1 beta (IL-1β)-induced extracellular matrix (ECM) metabolic imbalance by regulating the expression of MMP-13, ADAMTS-5, COL2A1, and ACAN. Furthermore, silencing of PRMT1 dramatically declined the production of prostaglandin E2 (PGE2) and nitric oxide as well as the level of pro-inflammatory cytokine IL-6 and TNF-α. Mechanistic analyses further revealed that IL-1β-induced activation of the Hedgehog/Gli-1 signaling is suppressed upon PRMT1 knockdown. However, the effects of inhibition of PRMT1-mediated IL-1β-induced cartilage matrix degradation and inflammatory response in OA chondrocytes were obviously abolished by Hedgehog agonist Purmorphamine (Pur). Our data collectively suggest that silencing of PRMT1 exerts anti-catabolic and anti-inflammatory effects on IL-1β-induced chondrocytes via suppressing the Gli-1 mediated Hedgehog signaling pathway, indicating that PRMT1 plays a critical role in OA development and serves as a promising therapeutic target for OA.

Effects of platycodin D on IL-1β-induced inflammatory response in human osteoarthritis chondrocytes

Platycodin D (PYD), a major saponin derived and isolated from the roots of Platycodon grandiflorum, has been reported to have anti-inflammatory and anti-tumor effects. The present study aimed to investigate the effects of PYD on IL-1β-stimulated human osteoarthritis chondrocytes. Chondrocytes were treated with PYD 1h before IL-1β treatment. The levels of MMP1, MMP13, IL-8, RANTES, PGE2, and NO were measured in this study. The expression of LXRα, NF-κB, and IκBα were detected by western blot analysis. The results showed that PYD significantly inhibited IL-1β-induced MMP1, MMP13, IL-8, RANTES, PGE2, and NO production. PYD also suppressed IL-1β-induced NF-κB activation. Furthermore, the expression of LXRα was up-regulated by PYD in a dose-dependent manner. In addition, LXRα siRNA inhibited the effects of PYD on MMP1, MMP13, PGE2, and NO production in human osteoarthritis chondrocytes. In conclusion, these results suggested that PYD attenuated IL-1β-induced inflammatory response in osteoarthritis chondrocyte by activating LXRα.

In vitro response of osteoarthritic chondrocytes and fibroblast‐like synoviocytes to a 500–730 kDa hyaluronan amide derivative

The aim of this study was to compare the effects of native hyaluronan (HA) with that of its hexadecylamide derivative (HYADD) on proliferation of fibroblast-like synoviocytes (FLS) and chondrocytes. The production of inflammatory and anti-inflammatory cytokines was also analyzed in FLS cultures. The proliferation of osteoarthritis (OA) chondrocytes was enhanced when cells were treated with 0.5-1.5 mg mL(-1) of HA or HYADD®4-G. This effect was completely suppressed by the anti-CD44 antibody. At 0.5 to 1 mg mL(-1) , HA and HYADD®4-G did not influence the proliferation of normal or pathological FLS; however, at the higher concentration (1.5 mg mL(-1) ), HYADD®4-G did significantly inhibit cell proliferation. As to effects on inflammation, a significant increase in the expression of the IL-10 gene was observed when FLS were pretreated with tumor necrosis factor alpha and then cultured in the presence of 0.5 mg mL(-1) HYADD® 4-G or HA. The effects of HA derivatives on FLS proliferation and production of anti-inflammatory cytokines indicate that they may be of therapeutic benefit in OA. The longer residence time in the joint cavity, the increased viscoelasticity, and the anti-inflammatory potential of HYADD®4-G make it a better candidate than native HA for OA therapy.

Alarmins S100A8 and S100A9 Elicit a Higher Catabolic Response in Osteoarthritic Chondrocytes Compared to Normal Chondrocytes that is Toll Like Receptor 4 Dependent

Alarmins S100A8 and S100A9 Elicit a Higher Catabolic Response in Osteoarthritic Chondrocytes Compared to Normal Chondrocytes that is Toll Like Receptor 4 Dependent