Interleukin-1beta induced activation of nuclear factor-kappab can be inhibited by novel pharmacological agents in osteoarthritis

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

Potential Joint Protective and Anti-Inflammatory Effects of Integrin αvβ3 in IL-1β-Treated Chondrocytes Cells

In osteoarthritis (OA), the articular cartilage covering the articular surface of the bone wears out, exposing the subchondral bone, and the synovial membrane surrounding the joint becomes inflamed, causing pain and deformity. OA causes pain, stiffness, and swelling, and discomfort in the knee when climbing stairs is a typical symptom. Although drug development studies are conducted to treat these inflammatory joint diseases, it is difficult to find conclusive research results which could reduce inflammation and slow cartilage tear. The development of drugs to relieve inflammatory pain often utilizes inflammatory triggers. Interleukins, one of the proteins in the limelight as pro-inflammatory factors, are immune-system-stimulating factors that promote the body's fight against harmful factors such as bacteria. In this study, inflammation was induced in Chondrocytes cells (Chon-001 cells) with IL-1β and then treated with integrin αvβ3 to show anti-inflammatory and chondrogenesis effects. Integrin αvβ3 was not toxic to Chon-001 cells in any concentration groups treated with or without IL-1β. COX-2 and iNOS, which are major markers of inflammation, were significantly reduced by integrin αvβ3 treatment. Expressions of p-ERK, p-JNK, and p-p38 corresponding to the MAPKs signaling pathway and p-IκBα and p-p65 corresponding to the NF-κB signaling pathway were also decreased in a dose-dependent manner upon integrin αvβ3 treatment, indicating that inflammation was inhibited, whereas treatment with integrin αvβ3 significantly increased the expression of ALP, RUNX2, BMP2, BMP4, Aggrecan, SOX9, and COL2A1, suggesting that osteogenesis and chondrogenesis were induced. These results suggest that integrin αvβ3 in-duces an anti-inflammatory effect, osteogenesis, and chondrogenesis on IL-1β-induced Chon-001 cells.

ACY-1215 exhibits anti-inflammatory and chondroprotective effects in human osteoarthritis chondrocytes via inhibition of STAT3 and NF-κB signaling pathways

Cartilage degeneration is a basic pathological feature of osteoarthritis (OA), and there is growing evidence that it is associated with inflammation. ACY-1215, a selective HDAC6 inhibitor, has been reported to have anti-inflammatory effects. Here, we investigated the anti-inflammatory and chondroprotective effects of ACY-1215 in IL-1β-stimulated human primary chondrocytes and C28/I2 cells. The results suggested that ACY-1215 can markedly suppress the expression of inflammatory factors, including IL-1β and IL-6 in human primary chondrocytes and C28/I2 cells. Furthermore, ACY-1215 exerts potent chondroprotection through the amelioration of cartilage degradation by inhibiting the expression of matrix-degrading proteases, including MMP-1 and MMP-13 in chondrocytes. These effects may be related to ACY-1215 induced down-regulation of NF-κB and STAT3 pathways in OA chondrocytes. Taken together, our results show that ACY-1215 may be a potential and promising therapeutic drug for the management of OA.

Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice

Objectives

This study aimed to examine the effects of SRT1720, a potent SIRT1 activator, on osteoarthritis (OA) progression using an experimental OA model.

Methods

Osteoarthritis was surgically induced by destabilization of the medial meniscus in eight-week-old C57BL/6 male mice. SRT1720 was administered intraperitoneally twice a week after surgery. Osteoarthritis progression was evaluated histologically using the Osteoarthritis Research Society International (OARSI) score at four, eight, 12 and 16 weeks. The expression of SIRT1, matrix metalloproteinase 13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), cleaved caspase-3, PARP p85, and acetylated nuclear factor (NF)-κB p65 in cartilage was examined by immunohistochemistry. Synovitis was also evaluated histologically. Primary mouse epiphyseal chondrocytes were treated with SRT1720 in the presence or absence of interleukin 1 beta (IL-1β), and gene expression changes were examined by real-time polymerase chain reaction (PCR).

Results

The OARSI score was significantly lower in mice treated with SRT1720 than in control mice at eight and 12 weeks associated with the decreased size of osteophytes at four and eight weeks. The delayed OA progression in the mice treated with SRT1720 was also associated with increased SIRT1-positive chondrocytes and decreased MMP-13-, ADAMTS-5-, cleaved caspase-3-, PARP p85-, and acetylated NF-κB p65-positive chondrocytes and decreased synovitis at four and eight weeks. SRT1720 treatment partially rescued the decreases in collagen type II alpha 1 (COL2A1) and aggrecan caused by IL-1β, while also reducing the induction of MMP-13 by IL-1β in vitro.

Conclusion

The intraperitoneal injection of SRT1720 attenuated experimental OA progression in mice, indicating that SRT1720 could be a new therapeutic approach for OA.Cite this article: K. Nishida, T. Matsushita, K. Takayama, T. Tanaka, N. Miyaji, K. Ibaraki, D. Araki, N. Kanzaki, T. Matsumoto, R. Kuroda. Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice. Bone Joint Res 2018;7:252-262. DOI: 10.1302/2046-3758.73.BJR-2017-0227.R1.

Anti-Inflammatory Effects of p-Coumaric Acid, a Natural Compound of Oldenlandia diffusa, on Arthritis Model Rats

Objectives

In China, Oldenlandia diffusa (OD) is a natural herb that is widely used and has been proven to be effective in the treatment of rheumatoid arthritis (RA). This study aimed to preliminarily reveal the mechanism by which OD exerts its beneficial effect.

Methods

Ultra-performance liquid chromatography photodiode array was applied to identify the absorbable compounds in the plasma of collagen-induced arthritis (CIA) model rats. After 2 weeks, an OD decoction or the identified absorbable compound was administered to CIA rats. Morphology, X-ray images of the joints, pathological images, arthritis index, and cytokine (TNF-α and IL-6) levels were evaluated.

Results

p-Coumaric acid (p-CA) was identified as the absorbed compound in plasma. After administration of p-CA solution or the OD decoction, symptoms in the treated rats were alleviated as compared to the untreated model rats, and inflammatory cell infiltration was suppressed. The arthritis index and serum levels of TNF-α and IL-6 were decreased as compared to the control group.

Conclusions

OD may exert its anti-inflammatory effect on RA via its active ingredient, p-CA. This information sheds light on the mechanism by which OD exerts its anti-inflammatory effort in RA and forms the basis for further development of therapeutic agents for RA.

Transcriptional network systems in cartilage development and disease

Transcription factors play important roles in the regulation of cartilage development by controlling the expression of chondrogenic genes. Genetic studies have revealed that Sox9/Sox5/Sox6, Runx2/Runx3 and Osterix in particular are essential for the sequential steps of cartilage development. Importantly, these transcription factors form network systems that are also required for appropriate cartilage development. Molecular cloning approaches have largely contributed to the identification of several transcriptional partners for Sox9 and Runx2 during cartilage development. Although the importance of a negative-feedback loop between Indian hedgehog (Ihh) and parathyroid hormone-related protein (PTHrP) in chondrocyte hypertrophy has been well established, recent studies indicate that several transcription factors interact with the Ihh-PTHrP loop and demonstrated that Ihh has multiple functions in the regulation of cartilage development. The most common cartilage disorder, osteoarthritis, has been reported to result from the pathological action of several transcription factors, including Runx2, C/EBPβ and HIF-2α. On the other hand, NFAT family members appear to play roles in the protection of cartilage from osteoarthritis. It is also becoming important to understand the homeostasis and regulation of articular chondrocytes, because they have different cellular and molecular features from chondrocytes of the growth plate. This review summarizes the regulation and roles of transcriptional network systems in cartilage development and their pathological roles in osteoarthritis.

Transthyretin deposition promotes progression of osteoarthritis

Deposition of amyloid is a common aging-associated phenomenon in several aging-related diseases. Osteoarthritis (OA) is the most prevalent joint disease, and aging is its major risk factor. Transthyretin (TTR) is an amyloidogenic protein that is deposited in aging and OA-affected human cartilage and promotes inflammatory and catabolic responses in cultured chondrocytes. Here, we investigated the role of TTR in vivo using transgenic mice overexpressing wild-type human TTR (hTTR-TG). Although TTR protein was detected in cartilage in hTTR-TG mice, the TTR transgene was highly overexpressed in liver, but not in chondrocytes. OA was surgically induced by destabilizing the medial meniscus (DMM) in hTTR-TG mice, wild-type mice of the same strain (WT), and mice lacking endogenous Ttr genes. In the DMM model, both cartilage and synovitis histological scores were significantly increased in hTTR-TG mice. Further, spontaneous degradation and OA-like changes in cartilage and synovium developed in 18-month-old hTTR mice. Expression of cartilage catabolic (Adamts4, Mmp13) and inflammatory genes (Nos2, Il6) was significantly elevated in cartilage from 6-month-old hTTR-TG mice compared with WT mice as was the level of phospho-NF-κB p65. Intra-articular injection of aggregated TTR in WT mice increased synovitis and significantly increased expression of inflammatory genes in synovium. These findings are the first to show that TTR deposition increases disease severity in the murine DMM and aging model of OA.

Gypenoside inhibits interleukin-1β-induced inflammatory response in human osteoarthritis chondrocytes

Gypenoside (GP), the main active ingredient of Gynostemma pentaphyllum, possesses a variety of pharmacological capacities including anti-inflammation, anti-oxidation, and anti-tumor. However, the effects of GP on IL-1β-stimulated human osteoarthritis (OA) chondrocytes are still unknown. Therefore, this study aimed to investigate the anti-inflammatory effects of GP on IL-1β-stimulated human OA chondrocytes and explore the possible mechanism. Our results showed that GP dose-dependently inhibited IL-1β-induced NO and PGE2 production in human OA chondrocytes. In addition, treatment of GP inhibited the expression of MMP3 and MMP13, which was increased by IL-1β. Finally, we found that pretreatment of GP obviously suppressed NF-κB activation in IL-1β-stimulated human OA chondrocytes. Taken together, the results demonstrated that GP has chondro-protective effects, at least in part, through inhibiting the activation of NF-κB signaling pathway in human OA chondrocytes. Thus, these findings suggest that GP may be considered as an alternative therapeutic agent for the management of OA patients.

AMPK deficiency in chondrocytes accelerated the progression of instability-induced and ageing-associated osteoarthritis in adult mice

Osteoarthritis (OA) is a progressive degenerative disease of the joints that is associated with both joint injury and ageing. Here, we investigated the role of the energy sensor AMP-activated protein kinase (AMPK) in maintaining a healthy state of articular cartilage and in OA development. Using cartilage-specific, tamoxifen-inducible AMPKα1 conditional knockout (AMPKα1 cKO), AMPKα2 conditional knockout (AMPKα2 cKO) and AMPKα1α2 conditional double knockout (AMPKα cDKO) mice, we found that compared with wild-type (WT) littermates, mutant mice displayed accelerated severity of surgically induced OA, especially AMPKα cDKO mice. Furthermore, male but not female AMPKα cDKO mice exhibited severely spontaneous ageing-associated OA lesions at 12 months of age. The chondrocytes isolated from AMPKα cDKO mice resulted in an enhanced interleukin-1β (IL-1β)-stimulated catabolic response. In addition, upregulated expression of matrix metalloproteinase-3 (MMP-3), MMP-13 and phospho-nuclear factor-κB (phospho-NF-κB) p65 and increased levels of apoptotic markers were detected in the cartilage of AMPKα cDKO mice compared with their WT littermates in vivo. Thus, our findings suggest that AMPK activity in chondrocytes is important in maintaining joint homeostasis and OA development.

Overexpression of HMGB1 A-box reduced IL-1β-induced MMP expression and the production of inflammatory mediators in human chondrocytes

The pro-inflammatory cytokine interleukin-1 beta (IL-1β) plays a crucial role in the pathogenesis of osteoarthritis (OA) by stimulating several mediators that contribute to cartilage degradation. The aim of this study was to investigate the effects and mechanism of high mobility group box 1 (HMGB1) inhibitors HMGB1 A-box on the expression of matrix metalloproteinase (MMP) and the production of inflammatory mediators in human osteoarthritis chondrocytes after activation by IL-1β. We found that the overexpression of HMGB1 A-box significantly decreased the IL-1β-stimulated the production of MMP-1, MMP-3 and MMP-9, and also reduced the elevated levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) associated with the inhibition of prostaglandin E2 (PGE2) and nitric oxide (NO) production in IL-1β-stimulated chondrocytes. In addition, overexpression of the HMGB1 A-box significantly inhibited the up-regulation of ADAMTS-4, ADAMTS-5 and HMGB1 caused by IL-1β in chondrocytes. Moreover, the overexpression of HMGB1 A-box markedly suppressed the IL-1β-mediated activation of the Toll-like receptor 4 (TRL4)/NF-κB pathway. Our observations indicated that the HMGB1 A-box can play a protective role by suppressing the IL-1β-induced expression of MMPs and that the production of inflammatory mediators in chondrocytes was associated with suppression of the HMGB1/TLR4/NF-κB pathway. In conclusion, HMGB1 A-box relieves the development of OA that may be associated with regulating the HMGB1/TLR4/NF-κB pathway.

Trichostatin A increases the TIMP-1/MMP ratio to protect against osteoarthritis in an animal model of the disease

The histone deacetylase inhibitor trichostatin A (TSA) has been demonstrated to alleviate certain symptoms associated with osteoarthritis (OA). However, the exact mechanisms underlying this protective effect remain to be elucidated. The present study therefore examined the effects of TSA on the expression levels of interleukin-1β (IL-1β)-induced matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in vitro and in vivo. In vitro, reverse transcription-quantitative polymerase chain reaction was performed to investigate alterations in mRNA expression levels in TSA-treated chondrocytes in the presence or absence of IL-1β; in addition, protein expression and acetylation levels were assessed by western blotting. In vivo, TSA was administered to rats by intra-articular injection, following which the mRNA and protein expression levels were analyzed. In addition, macroscopic and histological observations were conducted. Chondrocytes treated with IL-1β demonstrated increased mRNA and protein expression levels of MMP-1, MMP-3 and MMP-13, and decreased expression levels of TIMP-1 mRNA and protein; these alterations were significantly attenuated by TSA treatment. In addition, increased MMPs and decreased TIMP-1 expression levels were observed in vivo in the OA rat model. TSA treatment demonstrated in vivo efficacy through the attenuation of various OA-associated molecular and physiological changes. Taken together, the results of the present study suggest that TSA has potential therapeutic value for the treatment of OA.

Overexpression of Sirtuin 6 suppresses cellular senescence and NF-κB mediated inflammatory responses in osteoarthritis development

The aim of our study was to evaluate if Sirt6, a NAD + dependent histone deacetylase, plays a protective role in cartilage degeneration by suppressing cellular senescence and inflammatory responses. The expression level of sirt6 in normal and OA human knee articular cartilage was compared by immunofluorescence and western blotting. The effect of sirt6 overexpression on replicative senescence of chondrocytes and NF-κB target genes expression was evaluated. Histological assessment of OA mice knee joint was carried out to assess the in vivo effects of sirt6 overexpression on mice chondrocytes. We found sirt6 level was significantly decreased in the articular chondrocytes of OA patients compare to normal human. SA-β-gal staining revealed that overexpression of sirt6 suppressed replicative senescence of chondrocytes. Meanwhile, the expression of NF-κB dependent genes were significantly attenuated by sirt6 overxpression. Safranin-O staining and OARSI score of knee joint cartilage in OA mice revealed that Lenti-Sirt6 intraarticular injection could protect mice chondrocytes from degeneration. These data strongly suggest that overexpression of Sirt6 can prevent OA development by reducing both the inflammatory response and chondrocytes senescence. Therefore, the development of specific activators of Sirt6 may have therapeutic potential for the treatment of OA.

Protective effects of biochanin A on articular cartilage: in vitro and in vivo studies

Background

Increased production of matrix metalloproteinases (MMPs) is closely related to the progression of osteoarthritis (OA). The present study was performed to investigate the potential value of biochanin A in inhibition of MMP expression in both rabbit chondrocytes and an animal model of OA.

Methods

MTT assay was performed to assess chondrocyte survival in monolayers. The mRNA and protein expression of MMPs (including MMP-1, MMP-3, and MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in interleukin-1 < beta > (IL-1β)-induced rabbit chondrocytes were determined by quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. The involvement of the NF-kappaB (NF-κB) pathway activated by IL-1β was determined by western blotting. The in vivo effects of biochanin A were evaluated by intra-articular injection in an experimental OA rabbit model induced by anterior cruciate ligament transection (ACLT).

Results

Biochanin A downregulated the expression of MMPs and upregulated TIMP-1 at both the mRNA and protein levels in IL-1β-induced chondrocytes in a dose-dependent manner. In addition, IL-1β-induced activation of NF-κB was attenuated by biochanin A, as determined by western blotting. Moreover, biochanin A decreased cartilage degradation as determined by both morphological and histological analyses in vivo.

Conclusions

Taken together, these findings suggest that biochanin A may be a useful agent in the treatment and prevention of OA.

Disruption of Sirt1 in chondrocytes causes accelerated progression of osteoarthritis under mechanical stress and during ageing in mice

OBJECTIVES

Important roles for SIRT1 are implicated in ageing and age-related diseases. The role of SIRT1 in osteoarthritis (OA), however, remains partially unknown. To investigate the role of SIRT1 in chondrocytes in vivo, cartilage-specific Sirt1-conditional knockout (CKO) mice were analysed using an experimental OA model.

METHODS

OA was surgically induced in 8-week-old C57BL6/J (wild-type) mice and Sirt1-CKO (Sirt1(flox)/(flox); Col2a1-Cre) mice generated using the Cre-loxP system. We examined changes in Sirt1 protein during the development of surgically-induced OA and during ageing in wild-type mice. OA progression in Sirt1-CKO mice was evaluated histologically at 2, 4 and 8 weeks after surgery, and at 1 year of age without surgery compared with control (Sirt1(flox)/(flox)) mice.

RESULTS

The number of Sirt1-positive chondrocytes decreased during ageing, and although it was increased at 2 weeks after surgery, then gradually decreased to the presurgical level during the progression of OA in wild-type mice. Sirt1-CKO mice showed no obvious skeletal abnormalities. The histological OA score was significantly higher in 1-year-old Sirt1-CKO mice than in control mice. Sirt1-CKO mice showed accelerated OA progression at 2 and 4 (but not 8) weeks compared with control mice. Immunohistochemical analysis revealed increases in type X collagen, matrix metalloproteinase 13, a disintegrin and metalloproteinase with thrombospondin motifs-5, apoptotic markers, and acetylated nuclear factor-κB p65 in Sirt1-CKO mice compared with control mice 2 weeks after surgery.

CONCLUSIONS

Loss of Sirt1 in chondrocytes led to the accelerated development of OA in mice. Our observations suggest that SIRT1 has a preventive role against the development of OA.

The overexpression of SIRT1 inhibited osteoarthritic gene expression changes induced by interleukin-1β in human chondrocytes

In this study, we examined the effects of overexpression of SIRT1 on IL-1β-induced gene expression changes in human chondrocytes to explore a protective role of SIRT1 in human chondrocytes. SIRT1 was overexpressed in human chondrocytes by expression plasmid under stimulation with IL-1β. SIRT1 was also inhibited by siRNA under stimulation with IL-1β. Gene expression changes were examined by real-time PCR. The interaction of SIRT1 and p65 (NF-κB) were examined by Western blotting. SIRT1, MMP-13, and ADAMTS-5 expressions in human cartilage were examined by immunohistochemistry. IL-1β stimulation significantly up-regulated MMP-1, 2, 9, and 13 and ADAMTS-5. Overexpression of SIRT1 significantly inhibited the up-regulation of those genes caused by IL-1β while the inhibition of SIRT1 further increased them. In addition, the overexpression of SIRT1 markedly reduced the IL-1β-induced acetylation of p65. SIRT1 expression was clearly detected in the non-OA cartilage while MMP-13 and ADAMTS-5 were undetectable. In contrast, in the OA cartilage, SIRT1 expression was decreased while MMP-13 and ADAMTS-5 were increased. Our observations suggested that SIRT1 can play a protective role by suppressing IL-1β-induced expressions of cartilage-degrading enzymes partially through the modulation of the NF-κB pathway. SIRT1 overexpression might be a new therapeutic approach for OA.

Future therapeutics for osteoarthritis

Osteoarthritis (OA) is a disease of the joints that affects several million individuals worldwide. This disease, which involves mainly the diarthrodial joints, is chronic and develops slowly over decades, making it very difficult to precisely identify the different etiological and risk factors that influence its onset. At present, most therapies for OA are symptomatic. This review will focus on new OA therapeutics in development that are directed toward pain relief as well as others with the potential to reduce or stop the progression of the disease (DMOADs). This article is part of a Special Issue entitled "Osteoarthritis".

Impact of inflammation on the osteoarthritic niche: implications for regenerative medicine

Osteoarthritis (OA) is the most common form of arthritis worldwide and is the sixth leading cause of disability. It costs the UK economy approximately 1% of gross national product per annum. With an aging population, the cost of chronic conditions such as OA continues to rise. Historically, treatments for OA have been limited to painkillers, physiotherapy and joint injections. When these fail, patients are referred for joint replacement surgery. With the advent of tissue engineering strategies aimed at generating new bone and cartilage for repair of osteochondral defects, there has been considerable interest in exploiting these techniques to devise new treatments for OA. To date, little consideration has been given to the OA niche and attendant inflammatory milieu for any regenerative skeletal strategy. This review highlights the importance of understanding the osteoarthritic niche in order to modify existing tissue engineering and regenerative medicine strategies for the future treatment of OA.

The osteoarthritic niche and modulation of skeletal stem cell function for regenerative medicine

Osteoarthritis (OA) is the most common cause of arthritis worldwide and represents a significant healthcare burden, particularly in the context of an ageing population. Traditionally, painkillers, injections and physiotherapy have been the mainstay of treatment, with patients being referred for joint replacement surgery (arthroplasty) when these options fail. Whilst effective in reducing pain and improving joint function, these approaches are not without potential complications. With the development of tissue-engineering techniques over recent years there has been considerable interest in applying these strategies to provide new, innovative, alternative effective means of treating OA. This review explores the unique microenvironment present within an osteoarthritic joint, highlighting the features that comprise the osteoarthritic niche and could be modulated in the development of novel treatments for OA. Existing tissue-engineering strategies for repairing bone and cartilage defects are discussed, with particular reference to how these might be modified, both to improve existing treatments, such as impaction bone grafting, as well as in the development of future treatments for OA.

New molecular targets for the treatment of osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disorder characterized by destruction of the articular cartilage, subchondral bone alterations and synovitis. Current treatments are focused on symptomatic relief but they lack efficacy to control the progression of this disease which is a leading cause of disability. Therefore, the development of effective disease-modifying drugs is urgently needed. Different initiatives are in progress to define the molecular mechanisms involved in the initiation and progression of OA. These studies support the therapeutic potential of pathways relevant in joint metabolism such as Wnt/beta-catenin, discoidin domain receptor 2 or proteinase-activated receptor 2. The dysregulation in cartilage catabolism and subchondral bone remodeling could be improved by selective inhibitors of matrix metalloproteinases, aggrecanases and other proteases. Another approach would favor the activity of anabolic processes by using growth factors or regulatory molecules. Recent studies have also revealed the role of oxidative stress and synovitis in the progression of this disease, supporting the development of a number of inhibitory strategies. Novel targets in OA are represented by genes involved in OA pathophysiology discovered using gene network, epigenetic and microRNA approaches. Further insights into the molecular mechanisms involved in OA initiation and progression may lead to the development of new therapies able to control joint destruction and repair.

Immunomodulatory and anti-inflammatory effects of chondroitin sulphate

Chondroitin sulphate (CS) is a natural glycosaminoglycan present in the extracellular matrix and is formed by the 1–3 linkage of D-glucuronic acid to N-acetylgalactosamine. In chondrocytes, CS diminishes interleukin-1 p (IL-1p)-induced increases in p38 mitogen-activated protein kinase (p38MAPK) and signal-regulated kinase 1/2 (Erk1/2) phosphorylation, and decreases nuclear factor-KB (NF-kB) nuclear translocation and as a consequence, reduces the formation of pro-inflammatory cytokines, IL-1 p and TNF-a, and pro-inflammatory enzymes, such as phospholipase A2 (PLA2), cyclooxygenase 2 (COX-2) and nitric oxide synthase-2 (NOS-2). The mechanism of action of CS explains its beneficial effect on the cartilage, synovial membrane and subchondral bone. On the other hand, in vivo, CS given orally prevents hepatic NF-κB nuclear translocation, suggesting that systemic CS may elicit an anti-inflammatory effect in many tissues besides the articulation. There is preliminary evidence showing that in human beings, CS may be of benefit in other diseases where inflammation is an essential marker, such as psoriasis and atherosclerosis. The review of the literature suggest that CS might also be of interest for the treatment of other diseases with an inflammatory and/or autoimmune character, such as inflammatory bowel disease, degenerative diseases of the central nervous system and stroke, multiple sclerosis and other autoimmune diseases.

Anti-inflammatory activity of chondroitin sulfate

Osteoarthritis is primarily characterized by areas of destruction of articular cartilage and by synovitis. Articular damage and synovitis are secondary to local increase of pro-inflammatory cytokines (interleukin-1beta and tumor necrosis factor-alpha), enzymes with proteolytic activity (matrix metalloproteinases), and enzymes with pro-inflammatory activity (cyclooxygenase-2 and nitric oxide synthase-2). Enhanced expression of these proteins in chondrocytes and in synovial membrane appears associated to the activation and nuclear translocation of nuclear factor-kappaB (NF-kappaB). Chondroitin sulfate (CS) prevents joint space narrowing and reduces joint swelling and effusion. To produce these effects, CS elicits an anti-inflammatory effect at the chondral and synovial levels. CS and its disaccharides reduce NF-kappaB nuclear translocation, probably by diminishing extracellular signal-regulated kinase1/2, p38mitogen-activated protein kinase and c-Jun N-terminal kinase activation. This review discusses the evidence supporting that CS pleiotropic effects in chondrocytes and synoviocytes are primarily due to a common mechanism, e.g., the inhibition of NF-kappaB nuclear translocation.

Matrix metalloproteinase 9 (MMP9) expression in preeclamptic decidua and MMP9 induction by tumor necrosis factor alpha and interleukin 1 beta in human first trimester decidual cells

Extravillous trophoblasts (EVTs) invade human decidua via sequential integrin-mediated binding and proteolysis of basement membrane proteins in the extracellular matrix (ECM). In preeclampsia, shallow EVT invasion impairs spiral artery and arteriole remodeling to reduce uteroplacental blood flow. Excess decidual cell-expressed matrix metalloproteinases (MMPs) 2 and 9, in response to preeclampsia-related interleukin 1 beta (IL1B) and tumor necrosis factor alpha (TNF), may inappropriately degrade these basement membrane proteins and impede EVT invasion. This study found significantly higher immunohistochemical MMP9 levels in decidual cells and adjacent interstitial trophoblasts in placental sections of preeclamptic versus gestational age-matched control women. In contrast, immunostaining for MMP2 and tissue inhibitor of matrix metalloproteinases 1 and 2 (TIMP1 and TIMP2) were similar in preeclamptic and control groups. First-trimester decidual cells were incubated with estradiol (E(2)) or E(2) + medroxyprogesterone acetate (MPA), with or without TNF or IL1B. As measured by ELISA, both cytokines elicited concentration-dependent increases in secreted MMP9 levels that were unaffected by MPA. In contrast, secreted levels of MMP2, TIMP1, and TIMP2 were unchanged in all treatment groups. Substrate gel zymography and Western blotting confirmed that each cytokine increased secreted levels of MMP9 but not MMP2. Similarly, quantitative RT-PCR found that TNF and IL1B enhanced MMP9, but not MMP2, mRNA levels. At the implantation site, inflammatory cytokine-enhanced MMP9 may promote preeclampsia by disrupting the decidual ECM to interfere with normal stepwise EVT invasion.

Progestin-inflammatory cytokine interactions affect matrix metalloproteinase-1 and -3 expression in term decidual cells: implications for treatment of chorioamnionitis-induced preterm delivery

CONTEXT

Chorioamnionitis (CAM)-elicited preterm delivery (PTD) is associated with elevated amniotic fluid levels of IL-1beta and TNF-alpha. We hypothesized that IL-1beta and TNF-alpha may induce matrix metalloproteinase (MMP)-1 and MMP-3 activity to promote PTD by degrading decidual and fetal membranes and cervical extracellular matrix.

OBJECTIVE

Our objective was to evaluate: 1) MMP-1 and MMP-3 expression in decidual sections from uncomplicated term, idiopathic preterm, and CAM-complicated deliveries, and 2) the separate and interactive effects of IL-1beta, TNF-alpha, medroxyprogesterone acetate (MPA), and a p38 MAPK inhibitor (SB203580) on MMP-1 and MMP-3 expression in term decidual cells (DCs).

INTERVENTIONS AND MAIN OUTCOME MEASURES

Decidua were immunostained for MMP-1 and MMP-3. Cultured term DCs were incubated with estradiol (E2) or E2 plus MPA with or without IL-1beta or TNF-alpha with or without SB203580. ELISA and Western blotting assessed secreted MMP-1 and MMP-3 levels, quantitative real-time RT-PCR assessed mRNA levels, and substrate gel zymography was used to determined MMP-1 and MMP-3 proteolytic activity.

RESULTS

MMP-1 and MMP-3 immunostaining was more prominent in CAM-complicated decidua vs. control preterm and term decidual specimens (P < 0.05). Compared with basal outputs by DCs incubated with E2, TNF-alpha enhanced MMP-1 and MMP-3 secretion by 14 +/- 3- and 9 +/- 2-fold, respectively, and IL-1beta increased MMP-1 and MMP-3 secretion by 13 +/- 3- and 19 +/- 2-fold, respectively (P < 0.05). Addition of MPA lowered basal MMP-1 and MMP-3 outputs by 70%, whereas the TNF-alpha- and IL-1beta-enhanced MMP-1 and MMP-3 levels were blunted by more than 50% (P < 0.05). SB203580 suppressed TNF-alpha- and IL-1beta-induced MMP-1 and MMP-3 secretion by severalfold. Western blotting confirmed the ELISA results, and mRNA levels corresponded with MMP-1 and MMP-3 protein levels. MMP-1 and MMP-3 proteolytic activity was confirmed by substrate gel zymography.

CONCLUSION

Augmented DC-expressed MMP-1 and MMP-3 in CAM-complicated pregnancies may promote PTD via decidual, fetal membrane, and cervical extracellular matrix degradation. Effects of progestin-p38 MAPK signaling inhibition on cytokine-enhanced MMP-1 and MMP-3 expression in term DCs suggest alternative mechanisms to prevent CAM-induced PTD.