NLRC5 attenuates inflammatory response in IL-1ß-stimulated human osteoarthritis chondrocytes through the NF-κB signaling pathway.

NOD-like receptor family caspase recruitment domain family domain containing 5 (NLRC5) has been found to be a critical mediator of inflammatory response. However, the role of NLRC5 in osteoarthritis (OA) has not been reported. Our results showed that NLRC5 was down-regulated by IL-1ß induction in chondrocytes. Overexpression of NLRC5 in chondrocytes significantly suppressed IL-1ß-induced inflammatory response through inhibiting the production of multiple inflammatory mediators including inducible nitric oxide synthases (iNOS), and cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), NO, TNF-α and IL-6, as well matrix metalloproteinase 3 (MMP-3) and MMP-13. Consistently, NLRC5 knockdown exhibited opposite effects on the production of these inflammatory mediators in IL-1ß-induced chondrocytes. Furthermore, overexpression of NLRC5 increased the IĸBα expression, while decreased the p-p65 expression, indicating that NLRC5 inhibited the activation of NF-κB signaling. Additionally, inhibition of NF-κB by PDTC mitigated the si-NLRC5-mediated promotion of IL-1ß-induced inflammatory injury in chondrocytes. Finally, NLRC5 treatment ameliorated cartilage degeneration in an OA model in rats. Taken together, these findings revealed that NLRC5 attenuated IL-1ß-induced inflammatory injury in chondrocytes through regulating the NF-κB signaling.

Doxycycline aggravates granulomatous inflammation and lung microstructural remodeling induced by Schistosoma mansoni infection.

Although doxycycline exhibits immunomodulatory properties, its effects on pulmonary infection by Schistosoma mansoni remain overlooked. Thus, we investigated the impact of this drug on lung granulomatous inflammation and microstructural remodeling in a murine model of schistosomiasis. Swiss mice were randomized in four groups: (i) uninfected, (ii) infected with S. mansoni and untreated, (iii) infected treated with praziquantel (Pzq; 200 mg/kg), and (iv) infected treated with Dox (50 mg/kg). Pz was administered in a single dose, and Dox for 60 days. S. mansoni induced marked granulomatous lung inflammation, which was associated to cytokines upregulation (IL-2, IL-4, IL-10, IFN-γ, TNF-α, and TGF-ß), neutrophils and macrophages recruitment, alveolar collapse, lung fibrosis, and extensive depletion of elastic fibers. These parameters were attenuated by Pzq and aggravated by Dox. Exudative/productive granulomas were predominant in untreated and Dox-treated animals, while fibrotic granulomas were more frequent in Pzq-treated mice. The number and size of granulomas in Dox-treated animals was higher than untreated and Pzq-treated mice. Dox treatment inhibited the increase in MMP-1 and MMP-2 activity but upregulated myeloperoxidase and N-acetylglucosaminidase activity compared to untreated and Pzq-treated animals. Dox and Pzq exerted no effect on elastin depletion and upregulation of elastase activity. Together, our findings indicated that Dox aggravated granulomatous inflammation, accelerating lung microstructural remodeling by downregulating MMP-1 and MMP-2 activity without impair neutrophils and macrophages recruitment or elastase activity. Thus, Dox potentiates inflammatory damage associated with lung fibrosis, elastin depletion and massive alveolar collapse, profoundly subverting lung structure in S. mansoni-infected mice.

ß-Hydroxyisovalerylshikonin inhibits IL-1ß-induced chondrocyte inflammation via Nrf2 and retards osteoarthritis in mice.

Osteoarthritis is a chronic degenerative disease characterized by cartilage destruction. It is the fourth most disabling disease worldwide and is currently incurable. Inflammation and extracellular matrix (ECM) degradation are considered to be substantial reasons for accelerating the progression of OA. ß-Hydroxyisoamylshikonin (ß-HIVS) is a natural naphthoquinone compound with anti-inflammatory and antioxidant activity. However, the effect of ß-HIVS on OA is still unclear. In this study, we found that ß-HIVS can down-regulate the expression of NO, PEG2, IL-6, TNF-α, COX-2, and iNOS, suggesting its anti-inflammatory effects in chondrocytes; we also found that ß-HIVS may down-regulate the expression of ADAMTS5 and MMP13 and up-regulate the expression of aggrecan and collagen II to inhibit the degradation of ECM. Mechanistically, ß-HIVS inhibited the NFκB pathway by activating the Nrf2/HO-1 axis, thereby exerting its anti-inflammatory and inhibitory effects on ECM degradation. In vivo experiments also proved the therapeutic effects of ß-HIVS on OA in mice, and Nrf2 is the target of ß-HIVS. These findings indicate that ß-HIVS may become a new drug for the treatment of OA.

Up-regulated DERL3 in fibroblast-like synoviocytes exacerbates inflammation of rheumatoid arthritis.

Endoplasmic reticulum (ER) stress associated proteins contribute to the pathogenesis of rheumatoid arthritis (RA) through affecting synoviocyte proliferation and proinflammatory cytokine production. The role of DERL3, an ER-associated degradation component, in joint inflammation of RA was explored. Synovial tissues from RA and osteoarthritis (OA) patients were collected, and in RA synovial tissue, DERL3 showed up-regulation and significantly positive correlation with the expression of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6 and matrix metalloproteinase (MMP)-1. Immunofluorescence result suggested DERL3 was located in fibroblast-like synoviocytes (FLS). Among different inflammatory stimuli, DERL3 could be up-regulated by TNF-α stimulation in FLS. Under TNF-α stimulation, knocking down DERL3, the expression of IL-6, IL-8, MMP-1, MMP-13 was reduced and the activation of nuclear factor kappa B (NF-κB) signaling pathway was inhibited. In pristane-induced arthritis (PIA) rat model, Derl3 was up-regulated in synovial tissue and disease was attenuated after intraarticular injection of siDerl3. Overall, we conclude that TNF-α inducing DERL3 expression promotes the inflammation of FLS through activation of NF-κB signaling pathway, suggesting DERL3 plays important roles in the pathogenesis of RA and is a promising therapeutic target.

Retinoic Acid-Platinum (II) Complex [RT-Pt(II)] Protects Against Rheumatoid Arthritis in Mice via MEK/Nuclear Factor kappa B (NF-κB) Pathway Downregulation.

BACKGROUND Rheumatoid arthritis (RA) is an inflammatory disorder that is present in approximately 1% of the world's population. This study was aimed to investigate the effect of retinoic acid-platinum (II) complex [RT-Pt(II)] on rheumatoid arthritis (RA) and to explore the mechanism involved. MATERIAL AND METHODS MH7A cell viability was determined by MTT assay and apoptosis was assessed using FACSCalibur flow cytometry. RT-PCR and Western blot assays were used for assessment of mRNA and proteins levels. RESULTS Treatment of rheumatoid arthritis with RT-Pt(II) significantly reduced the levels of IL­1ß, IL-6, IL-8, MMP-1, and MMP-13 in synovial fluid of mice in a dose-dependent manner. The expression of iNOS and COX-2 mRNA and protein in rheumatoid arthritis rats was also significantly inhibited by treatment with RT-Pt(II). The TNF-alpha-induced proliferation of MH7A cells was alleviated by RT-Pt(II) treatment in a concentration-dependent manner. Moreover, RT-Pt(II) treatment induced apoptosis and caused arrest of cell cycle in MH7A cells. The activation of MEK/NF-kappaB pathway was downregulated by RT-Pt(II) treatment in MH7A cells. CONCLUSIONS In summary, the present study demonstrated that RT-Pt(II) inhibits TNF-alpha-induced inflammatory response, suppresses cell viability, and induces apoptosis in rheumatoid arthritis synovial cells. Moreover, RT-Pt(II) exhibited its effect through targeting the MEK/NF-kappaB pathway. Therefore, RT-Pt(II) can be used for the development of treatments for rheumatoid arthritis.

The role of matrix metalloproteinases in osteoarthritis pathogenesis: An updated review.

Extensive degeneration of articular cartilage (AC) is a primary event in the pathogenesis of osteoarthritis (OA) and other types of joint and bone inflammation. OA results in the loss of joint function, usually accompanied by severe pain, and are the most common type of arthritis, affecting more than 10% of adults. The characteristic signs of OA are progressive cartilage destruction and, eventually, complete loss of chondrocytes. A key enzyme responsible for these degenerative changes in cartilage is matrix metalloproteinase-13 (MMP-13), which is thought to be a major contributor to the degenerative process occurring during OA pathogenesis. The aim of the present review is to shed light on the general role of MMPs, with special emphasis on MMP-13, in the induction of OA and the general basis of OA treatment. The pathogenic mechanism of this highly prevalent disease is not clear, and no effective disease-modifying treatment is currently available. Any updated information about OA treatment in human patients will also benefit companion animals such as horses and dogs, which also suffer from OA. Selective inhibition of MMP-13 seems to be an attractive therapeutic strategy.

Morin Exhibits Anti-Inflammatory Effects on IL-1ß-Stimulated Human Osteoarthritis Chondrocytes by Activating the Nrf2 Signaling Pathway.

BACKGROUND/AIMS: Osteoarthritis (OA) is a multifactorial disease that is associated with inflammation in joints. The purpose of the present study was to investigate the anti-inflammatory activity and mechanism of morin on human osteoarthritis chondrocytes stimulated by IL-1ß. METHODS: The levels of NO and PGE2 were measured by the Griess method and ELISA. The levels of MMP1, MMP3, and MMP13 were also measured by ELISA. RESULTS: The results revealed that IL-1ß significantly increased the production of NO, PGE2, MMP1, MMP3, and MMP13. Additionally, the increases were significantly attenuated by treatment with morin. Furthermore, IL-1ß-induced NF-κB activation was suppressed by morin. In addition, the expression of Nrf2 and HO-1 were increased by morin and knockdown of Nrf2 could prevent the anti-inflammatory effects of morin. CONCLUSION: In conclusion, this study suggested that morin attenuated IL-1ß-induced inflammation by activating the Nrf2 signaling pathway.

Analysis of IL-1α, bFGF, TGF-ß1, IFNγ, MMP-1, and CatD Expression in Multinuclea Macrophages In Vitro.

The incidence of mono- and multinuclear cells and their expression of pro- and antifibrotic factors were studied in cultured peritoneal macrophages from intact and BCG-infected mice. Generally, the expression of factors increased with an increase in the number of nuclei per cell. However, the expression was higher in macrophages from BCG infected mice, except the cells with 3 and more nuclei, extremely rarely expressing IL-1α in cultures from intact and BCG-infected animals. The number of macrophages with 3 and more nuclei, expressing CatD, was comparable with the number of mono- and binuclear macrophages. Presumably, this was determined by various mechanisms of formation of multinuclear (3-5 and more nuclei) macrophages, for example, by amitosis.

Carvacrol ameliorates inflammatory response in interleukin 1ß-stimulated human chondrocytes.

Carvacrol, a monoterpenic phenol present in Origanum vulgare (oregano) and Thymus vulgaris (thyme), possesses anti­inflammatory effects; however, little is known about the effects and underlying mechanism of carvacrol on chondrocytes in osteoarthritis (OA). The present study aimed to investigate the protective effects of carvacrol against inflammation in interleukin 1ß (IL­1ß)­stimulated human chondrocytes. The results indicated that carvacrol inhibited nitric oxide (NO) and prostaglandin E2 (PGE2) production, and decreased the expression of inducible NO synthase (iNOS) and cyclooxygenase (COX­2). Carvacrol also suppressed the protein expression levels of matrix metalloproteinase (MMP)­3 and MMP­13 in IL­1ß­stimulated human OA chondrocytes. Furthermore, carvacrol suppressed the activation of nuclear factor (NF)­κB signaling pathway in IL­1ß­induced human chondrocytes. In conclusion, the present results demonstrated that carvacrol was able to inhibit IL­1ß­induced NO and PGE2 production, as well as iNOS, COX­2 and MMPs expression in human chondrocytes by suppressing the activation of NF­κB signaling pathway. Thus, carvacrol may have potential therapeutic functions for the treatment of OA.

Oleuropein inhibits the IL-1ß-induced expression of inflammatory mediators by suppressing the activation of NF-κB and MAPKs in human osteoarthritis chondrocytes.

Osteoarthritis (OA) is the most common form of joint disease and is widespread in the elderly population and is characterized by erosion of articular cartilage, subchondral bone sclerosis and synovitis. Oleuropein (OL), a secoiridoid, is considered as the most prevalent phenolic component in olive leaves and seeds, pulp and peel of unripe olives and has been shown to have potent anti-inflammatory effects. However, its effects on OA have not been clearly elucidated. This study aimed to assess the effect of OL on human OA chondrocytes. Human OA chondrocytes were pretreated with OL (10, 50 and 100 µM) for 2 h and subsequently stimulated with IL-1ß for 24 h. The production of NO, PGE2, MMP-1, MMP-13, and ADAMTS-5 was evaluated by the Griess reaction and ELISA assays. The messenger RNA (mRNA) expression of COX-2, iNOS, MMP-1, MMP13, ADAMTS-5, aggrecan, and collagen-II was measured by using real-time PCR. The protein expressions of COX-2, iNOS, p65, IκB-α, JNK, p-JNK, ERK, p-ERK, p38, and p-p38 were tested by using western blot. We found that OL significantly inhibited the IL-1ß-induced production of NO and PGE2; expression of COX-2, iNOS, MMP-1, MMP-13, and ADAMTS-5; and degradation of aggrecan and collagen-II. Furthermore, OL dramatically suppressed IL-1ß-stimulated NF-κB and MAPK activation. Immunofluorescence staining demonstrated that OL could suppress IL-1ß-induced phosphorylation of p65 nuclear translocation. These results indicate that the therapeutic effect of OL on OA is accomplished through the inhibition of both NF-κB and MAPK signaling pathways. Altogether, our findings provide the evidence to develop OL as a potential therapeutic agent for patients with OA.

Down-regulation of microRNA-216b inhibits IL-1ß-induced chondrocyte injury by up-regulation of Smad3.

Osteoarthritis (OA) is the most common type of joint disease, leading to a major cause of pain and disability. OA is characterized by the continuous degradation of articular cartilage, mainly resulting in an imbalance between synthesis and degradation of articular chondrocyte extracellular matrix (ECM). Aberrant miR-216b expression has been found in multiple cancers. However, the level of miR-216b in OA cartilage and its role in progression of this disease are still unknown. In the present study, the functional roles of miR-216b and its expression in OA tissues and interleukin-1ß (IL-1ß)-induced chondrocytes were examined. We found that the level of miR-216b was significantly higher and Smad3 expression was obviously lower in OA cartilage and IL-1ß-induced chondrocytes than in normal tissues and cells. Furthermore, a bioinformatics analysis and luciferase reporter assay identified Smad3 as a direct target gene of miR-216b, and Smad3 expression was reduced by miR-216b overexpression at both the mRNA and protein levels. A functional analysis demonstrated that miR-216b down-regulation obviously alleviated the IL-1ß-induced inhibition in cell proliferation, type II collagen, and aggrecan down-regulation and matrix metalloproteinase-13 (MMP-13) up-regulation, while miR-216b overexpression had the opposite effects. Knockdown of Smad3 by siRNA reversed the effects of the miR-216b inhibitor on cell proliferation, the expressions of type II collagen, aggrecan, and MMP-13. Our results suggested that miR-216b contributes to progression of OA by directly targeting Smad3, providing a potential therapeutic target for treatment of OA.

Therapeutic mechanisms of ibuprofen, prednisone and betamethasone in osteoarthritis.

The present study aimed to investigate the therapeutic mechanisms of nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids in osteoarthritis (OA). The CHON­002 human chondrocyte cell line was used in the study. The levels of the cytokines, interleukin (IL)­1ß, IL­6, IL­8 and IL­10, released by cells treated with tumor necrosis factor­α (TNF­α) were determined by ELISA. Levels of collagen I, aggrecan, matrix metalloproteinase (MMP)­1, MMP­13, signal transducer and activator of transcription (STAT) 3, nuclear factor­κB (NF­κB) subunit p65 and inhibitory subunit of NF­κB (IκB) following treatment with IL­1ß, IL­6, IL­8 or IL­10 were assessed by western blot. Levels of IL­6 and IL­8 were measured by ELISA following administration of TNF­α combined with certain drugs. In addition, these parameters were evaluated by western blot following incubation with drugs in combination with IL­6 or IL­8 and after knockdown of STAT3, by addition of small interfering RNA (siRNA)­STAT3 (siSTAT3), an inhibitor of the proteasome (MG132) or both. IL­1ß, IL­6, IL­8 and IL-10 were upregulated by TNF­α. Addition of IL­6 or IL­8 led to increased collagen I, MMP­1 and MMP­13 protein levels, and also promoted STAT3 phosphorylation and increased the expression of NF­κB subunit p65, but had no effect on aggrecan protein levels. When siSTAT3 and MG132 treatment was combined, levels of collagen I, MMP­1 and MMP­13 were reduced. Additionally, levels of IL­6 and IL­8 were significantly decreased by prednisone, ibuprofen and betamethasone. However, no significant differences were observed following treatment with piroxicam or indomethacin. In combination with IL­6 or IL­8, prednisone, ibuprofen and betamethasone significantly reduced the levels of collagen I, MMP­1 and MMP­13, and inactivated NF­κB and STAT3 pathways. In conclusion, prednisone, ibuprofen and betamethasone may prevent OA by suppressing the expression of IL­6 and IL­8, subsequently inactivating NF­κB and STAT3 pathways, and ultimately, leading to decreased levels of collagen I, MMP­1, and MMP­13.

Inhibitory Effects of Viscum coloratum Extract on IgE/Antigen-Activated Mast Cells and Mast Cell-Derived Inflammatory Mediator-Activated Chondrocytes.

The accumulation and infiltration of mast cells are found in osteoarthritic lesions in humans and rodents. Nonetheless, the roles of mast cells in osteoarthritis are almost unknown. Although Viscum coloratum has various beneficial actions, its effect on allergic and osteoarthritic responses is unknown. In this study, we established an in vitro model of mast cell-mediated osteoarthritis and investigated the effect of the ethanol extract of Viscum coloratum (VEE) on IgE/antigen (IgE/Ag)-activated mast cells and mast cell-derived inflammatory mediator (MDIM)-stimulated chondrocytes. The anti-allergic effect of VEE was evaluated by degranulation, inflammatory mediators, and the FcεRI signaling cascade in IgE/Ag-activated RBL-2H3 cells. The anti-osteoarthritic action of VEE was evaluated by cell migration, and the expression, secretion, and activity of MMPs in MDIM-stimulated SW1353 cells. VEE significantly inhibited degranulation (IC50: 93.04 µg/mL), the production of IL-4 (IC50: 73.28 µg/mL), TNF-α (IC50: 50.59 µg/mL), PGD2 and LTC4, and activation of the FcεRI signaling cascade in IgE/Ag-activated RBL-2H3 cells. Moreover, VEE not only reduced cell migration but also inhibited the expression, secretion, and/or activity of MMP-1, MMP-3, or MMP-13 in MDIM-stimulated SW1353 cells. In conclusion, VEE possesses both anti-allergic and anti-osteoarthritic properties. Therefore, VEE could possibly be considered a new herbal drug for anti-allergic and anti-osteoarthritic therapy. Moreover, the in vitro model may be useful for the development of anti-osteoarthritic drugs.

Lycorine protects cartilage through suppressing the expression of matrix metalloprotenases in rat chondrocytes and in a mouse osteoarthritis model.

Extracellular matrix (ECM) degrading enzymes, including matrix metalloproteinases (MMPs), are critical for cartilage destruction in the progression of osteoarthritis (OA). Thus, identifying novel drugs, which suppress the synthesis of MMPs may facilitate the treatment of OA. The cytotoxicity of lycorine was determined using a CCK8 assay. The effects of lycorine on IL­1ß­induced upregulation of MMPs and activation of mitogen­activated protein kinase pathways were detected by western blot analysis and reverse transcription­quantitative polymerase chain reaction. Hematoxylin and eosin staining and Safranin O staining were used to evaluate the effect of lycorine in a mouse anterior cruciate ligament transection model. In the present study, it was demonstrated for the first time, to the best of our knowledge, that lycorine (LY) suppressed interleukin­1ß (IL­1ß)­induced synthesis of MMP­3 and MMP­13 in vitro. Molecular analysis revealed that LY abrogated the phosphorylation of c­Jun N­terminal kinase (JNK) and the activation of the nuclear factor (NF)­κB signaling pathway caused by IL­1ß stimulation. In addition, in vivo experiments in a mouse anterior cruciate ligament transection model confirmed the protective role of LY on cartilage. Taken together, the data obtained in the present study demonstrated that LY suppressed the IL­1ß­induced expression of MMP­3 and MMP­13 through inhibition of the JNK and NF­κB pathways, suggesting that LY may be used as a potential drug for the treatment of OA.

Functional Genomic Analysis of the Impact of Camelina (Camelina sativa) Meal on Atlantic Salmon (Salmo salar) Distal Intestine Gene Expression and Physiology.

The inclusion of plant meals in diets of farmed Atlantic salmon can elicit inflammatory responses in the distal intestine (DI). For the present work, fish were fed a standard fish meal (FM) diet or a diet with partial replacement of FM with solvent-extracted camelina meal (CM) (8, 16, or 24 % CM inclusion) during a 16-week feeding trial. A significant decrease in growth performance was seen in fish fed all CM inclusion diets (Hixson et al. in Aquacult Nutr 22:615-630, 2016). A 4x44K oligonucleotide microarray experiment was carried out and significance analysis of microarrays (SAM) and rank products (RP) methods were used to identify differentially expressed genes between the DIs of fish fed the 24 % CM diet and those fed the FM diet. Twelve features representing six known transcripts and two unknowns were identified as CM responsive by both SAM and RP. The six known transcripts (including thioredoxin and ependymin), in addition to tgfb, mmp13, and GILT, were studied using qPCR with RNA templates from all four experimental diet groups. All six microarray-identified genes were confirmed to be CM responsive, as was tgfb and mmp13. Histopathological analyses identified signs of inflammation in the DI of salmon fed CM-containing diets, including lamina propria and sub-epithelial mucosa thickening, infiltration of eosinophilic granule cells, increased goblet cells and decreased enterocyte vacuolization. All of these were significantly altered in 24 % CM compared to all other diets, with the latter two also altered in 16 % CM compared with 8 % CM and control diet groups. Significant correlation was seen between histological parameters as well as between five of the qPCR analyzed genes and histological parameters. These molecular biomarkers of inflammation arising from long-term dietary CM exposure will be useful in the development of CM-containing diets that do not have deleterious effects on salmon growth or physiology.

[PHENOTYPE OF PERIPHERAL BLOOD NEUTROPHILS IN THE INITIAL STAGE OF ENDOMETRIAL CANCER].

We have examined peripheral blood neutrophils from 123 patients with primary endometrial cancer at stage Ia. Receptor system and the ability of neutrophils to form extracellular traps were assessed by fluorescence microscopy, the spontaneous production of cytokines IL-2, IFN-γ, g-CSF, matrix metalloproteinases-1,9,13 by the method of enzyme-linked immunosorbent assay, phagocytic activity, myeloperoxidase activity, the level of cationic proteis activity in NBT-test were evaluated by cytochemical methods, activity of neutrophils in the spontaneous NBT-test was used to evaluate the oxygen-dependent bactericidal action of neutrophils. The topology and the rigidity of the membrane of neutrophils were assessed by scanning probe microscopy. We have shown that the increase in the relative number of neutrophils lead to a change in their receptor system, aerobic and anaerobic cytotoxicity and ability to phagocytosis are enchanced while reducing NET-activity. We have observed a change in the secretory activity of neutrophils, which is characterized by increased level of MMP-1, possibly initiated by enhanced production of reactive oxygen species, by a reduction in the IL-2 level (inductor of cytotoxic activity) and a sharp increase in the level of the G-CSF. Architectonics of neutrophils in the case of endonetrial cancer at stage Ia is characterized by changing the shape and loss of grit. The rigidity of the cell membrane decreased. Changes in the morphology of neutrophils on the background of the continuing hyperactivity suggests that a state of balance between the immune system and the tumor is already in stage Ia endometrial cancer.

Docosahexenoic acid treatment ameliorates cartilage degeneration via a p38 MAPK-dependent mechanism.

Osteoarthritis (OA) is a common chronic inflammatory disease, characterized by cartilage degradation. The aberrant expression of matrix metalloproteinase-13 (MMP-13) plays a vital role in the pathogenesis of OA. The anti­inflammatory property of docosahexenoic acid (DHA) was previously revealed and showed that DHA retards the progress of many types of inflammatory disease. To evaluate the prophylactic function of DHA in OA, the effect of DHA on cartilage degeneration was assessed in interleukin­1ß (IL­1ß) stimulated human chondrosarcoma SW1353 cells or a rat model of adjuvant­induced arthritis (AIA). The safe concentration range (0­50 µg/ml in vitro) of DHA was determined by flow cytometry and MTT assay. The inhibitory effects of DHA on MMP­13 mRNA and protein expression were confirmed by RT­qPCR, ELISA and western blotting. Furthermore, findings of an in vivo study showed that DHA can increase the thickness of articular cartilage and decrease MMP­13 expression in cartilage matrix in a rat AIA model. We also revealed the mechanism by which DHA ameliorates cartilage degeneration from OA. The DHA-mediated inhibition of MMP­13 expression was partially attributed to the inactivation of the p38 mitogen­activated protein kinases pathway by suppressing p­p38 in IL-1ß-stimulated SW1353 cells and a rat AIA model. Our findings suggested that DHA is a promising therapeutic agent that may be used for the prevention and treatment of OA.

Mechanical and IL-1ß Responsive miR-365 Contributes to Osteoarthritis Development by Targeting Histone Deacetylase 4.

Mechanical stress plays an important role in the initiation and progression of osteoarthritis. Studies show that excessive mechanical stress can directly damage the cartilage extracellular matrix and shift the balance in chondrocytes to favor catabolic activity over anabolism. However, the underlying mechanism remains unknown. MicroRNAs (miRNAs) are emerging as important regulators in osteoarthritis pathogenesis. We have found that mechanical loading up-regulated microRNA miR-365 in growth plate chondrocytes, which promotes chondrocyte differentiation. Here, we explored the role of the mechanical responsive microRNA miR-365 in pathogenesis of osteoarthritis (OA). We found that miR-365 was up-regulated by cyclic loading and IL-1ß stimulation in articular chondrocytes through a mechanism that involved the transcription factor NF-κB. miR-365 expressed significant higher level in rat anterior cruciate ligament (ACL) surgery induced OA cartilage as well as human OA cartilage from primary OA patients and traumatic OA Patients. Overexpression of miR-365 in chondrocytes increases gene expression of matrix degrading enzyme matrix metallopeptidase 13 (MMP13) and collagen type X (Col X). The increase in miR-365 expression in OA cartilage and in response to IL-1 may contribute to the abnormal gene expression pattern characteristic of OA. Inhibition of miR-365 down-regulated IL-1ß induced MMP13 and Col X gene expression. We further showed histone deacetylase 4 (HDAC4) is a direct target of miR-365, which mediates mechanical stress and inflammation in OA pathogenesis. Thus, miR-365 is a critical regulator of mechanical stress and pro-inflammatory responses, which contributes cartilage catabolism. Manipulation of the expression of miR-365 in articular chondrocytes by miR-365 inhibitor may be a potent therapeutic target for the prevention and treatment of osteoarthritis.

Histone Methylation and STAT-3 Differentially Regulate Interleukin-6-Induced Matrix Metalloproteinase Gene Activation in Rheumatoid Arthritis Synovial Fibroblasts.

OBJECTIVE: Synovial fibroblasts (SFs) produce matrix-degrading enzymes that cause joint destruction in rheumatoid arthritis (RA). Epigenetic mechanisms play a pivotal role in autoimmune diseases. This study was undertaken to elucidate the epigenetic mechanism that regulates the transcription of matrix metalloproteinases (MMPs) in RASFs. METHODS: MMP gene expression and histone methylation profiles in the MMP promoters were examined in RASFs. The effect of WD repeat domain 5 (WDR5) silencing on histone methylation and MMP gene expression in RASFs was analyzed. MMP gene expression, surface expression of the interleukin-6 (IL-6) receptor, phosphorylation of STAT-3, and binding of STAT-3 in the MMP promoters were investigated in RASFs stimulated with IL-6. RESULTS: The MMP-1, MMP-3, MMP-9, and MMP-13 genes were actively transcribed in RASFs. Correspondingly, the level of histone H3 trimethylated at lysine 4 (H3K4me3) was elevated, whereas that of H3K27me3 was suppressed in the MMP promoters in RASFs. The decrease in H3K4me3 via WDR5 small interfering RNA reduced the levels of messenger RNA for MMP-1, MMP-3, MMP-9, and MMP-13 in RASFs. Interestingly, IL-6 signaling significantly increased the expression of MMP-1, MMP-3, and MMP-13, but not MMP-9, in RASFs. Although the IL-6 signaling pathway was similarly active in RASFs and osteoarthritis SFs, STAT-3 bound to the MMP-1, MMP-3, and MMP-13 promoters, but not the MMP-9 promoter, after IL-6 stimulation in RASFs. CONCLUSION: Our findings indicate that histone methylation and STAT-3 regulate spontaneous and IL-6-induced MMP gene activation in RASFs. The combination of chromatin structure and transcription factors may regulate distinct arthritogenic properties of RASFs.

Pathophysiological changes induced by Pseudomonas aeruginosa infection are involved in MMP-12 and MMP-13 upregulation in human carcinoma epithelial cells and a pneumonia mouse model.

Pseudomonas aeruginosa infections persist in patients with cystic fibrosis (CF) and drive lung disease progression. P. aeruginosa potently activates the innate immune system mostly through the recognition of pathogen-associated molecular patterns, such as flagellin. Matrix metalloproteinases 12 and 13 (MMP-12 and MMP-13, respectively) exacerbate chronic lung infection and inflammation by promoting uncontrolled tissue rearrangements and fibrosis, yet the underlying molecular mechanisms by which this occurs remain largely unknown. In this study, we used quantitative bacteriology, histological examination, and proinflammatory cytokine levels to evaluate the effects of MMP-12 and MMP-13 on P. aeruginosa strain K-induced infection and pneumonia in H292 epithelial cells and mice, respectively. Under inflammatory stimulation, mRNA and protein expression levels of proinflammatory mediators were higher in strain K-infected mice and cells than in uninfected counterparts, in which MMP-12 and MMP-13 expression reached levels similar to those observed in epithelial cells. Moreover, we also found that the NF-κB pathway might be involved in the induction of cytokines in response to strain K infection. Taken together, these data suggest that MMP-12 and MMP-13 alter strain K infection in mice and play a role in inflammatory regulation by modulating cytokine levels.