Low-Molecular-Weight Fish Collagen Peptide (Valine-Glycine-Proline-Hydroxyproline-Glycine-Proline-Alanine-Glycine) Prevents Osteoarthritis Symptoms in Chondrocytes and Monoiodoacetate-Injected Rats.

The objective of this study was to investigate the effect of low-molecular-weight fish collagen (valine-glycine-proline-hydroxyproline-glycine-proline-alanine-glycine; LMWCP) on H2O2- or LPS-treated primary chondrocytes and monoiodoacetate (MIA)-induced osteoarthritis rat models. Our findings indicated that LMWCP treatment exhibited protective effects by preventing chondrocyte death and reducing matrix degradation in both H2O2-treated primary chondrocytes and cartilage tissue from MIA-induced osteoarthritis rats. This was achieved by increasing the levels of aggrecan, collagen type I, collagen type II, TIMP-1, and TIMP-3, while simultaneously decreasing catabolic factors such as phosphorylation of Smad, MMP-3, and MMP-13. Additionally, LMWCP treatment effectively suppressed the activation of inflammation and apoptosis pathways in both LPS-treated primary chondrocytes and cartilage tissue from MIA-induced osteoarthritis rats. These results suggest that LMWCP supplementation ameliorates the progression of osteoarthritis through its direct impact on inflammation and apoptosis in chondrocytes.

PG545 Prevents Osteoarthritis Development by Regulating PI3K/AKT/mTOR Signaling and Activating Chondrocyte Autophagy.

INTRODUCTION: Osteoarthritis (OA) is a degenerative disease common in the elderly and is characterized by joint pain, swelling, and restricted movement. In recent years, heparanase has been reported to play an important role in the development of osteoarthritic cartilage. PG545 is a heparan sulfate mimetic with heparanase inhibitory activity. In this study, the therapeutic effects and possible mechanisms of PG545 were investigated in a chondrocyte injury model induced by interleukin-1ß (IL -1ß). METHODS: Following treatment with PG545 or the autophagy inhibitor 3-methyladenine (3-MA), chondrocyte viability was detected using Cell Counting Kit-8 and fluorescein diacetate/propidium iodide double staining. The apoptosis rate of chondrocytes was determined by flow cytometry. Expression of light chain 3 and P62 was monitored by immunofluorescence labeling. Western blot, lentivirus infection with red fluorescent protein and green fluorescent protein, and quantitative real-time polymerase chain reaction were used to determine the expression levels of chondrocyte markers, apoptosis-related factors, autophagy proteins, and key proteins of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway. The expression and activity of stress-specific enzymes such as malondialdehyde, superoxide dismutase, and catalase (CAT) were investigated. Chondrocytes with ATG5 knockdown were used to investigate the relationship between the therapeutic effect of PG545 and autophagy. The therapeutic effect of PG545 was verified in vivo. RESULTS: PG545 had a significant protective effect on chondrocytes by reducing oxidative stress, apoptosis, and degradation of chondrocytes and increasing chondrocyte proliferation. PG545 was effective in inducing autophagy in IL-1ß-treated cells, while 3-MA attenuated the effect. The PI3K/Akt/mTOR pathway may be involved in the promotion of autophagy and OA treatment by PG545. CONCLUSION: PG545 was able to restore impaired autophagy and autophagic flux via the PI3K/Akt/mTOR pathway, thereby delaying the progression of OA, suggesting that PG545 may be a novel therapeutic approach for OA.

[Peptides prevent the forming of secretory phenotype of chondrocytes associated with the aging.]

Secretory phenotype associated with the aging (SASP) of chondrocytes forms the conditions for the musculoskeletal system diseases development, in particular, osteoarthritis (OA). The search for effective methods for OA treating is an urgent task of molecular gerontology. The purpose of this work is to characterize the SASP of chondrocytes and to conduct a comparative assessment of the effect of AED peptide and the cartilage polypeptide complex (CPC). It was found that chondrocyte's SASP is characterized by an increase of the synthesis of p16, p21, p53 pro-apoptotic proteins, TNF-α, IL-1α pro-inflammatory cytokines and a decrease of Sirt1synthesis. Peptides AED and CPC normalize the synthesis of molecules that form SASP of chondrocytes. This effect may explain their geroprotective effect and effectiveness in studies of various pathologies of the musculoskeletal system, including OA.

Astaxanthin prevents osteoarthritis by blocking Rspo2-mediated Wnt/ß-catenin signaling in chondrocytes and abolishing Rspo2-related inflammatory factors in macrophages.

Chondrocyte degeneration and classically activated macrophage (AM)-related inflammation play critical roles in osteoarthritis (OA). Here, we explored the effects of astaxanthin and Rspo2 on OA in vitro and in vivo. We observed that the Rspo2 gene was markedly elevated in synovial tissues of OA patients compared with healthy controls. In 2D cultures, Rspo2 and inflammatory factors were enhanced in AMs compared with nonactivated macrophages (NMs), and the protein expression levels of Rspo2, ß-catenin, and inflammatory factors were increased, and anabolic markers were reduced in osteoarthritic chondrocytes (OACs) compared to normal chondrocytes (NCs). Astaxanthin reversed these changes in AMs and OACs. Furthermore, Rspo2 shRNA significantly abolished inflammatory factors and elevated anabolic markers in OACs. In NCs cocultured with AM, and in OACs cocultured with AMs or NMs, astaxanthin reversed these changes in these coculture systems and promoted secretion of Rspo2, ß-catenin and inflammatory factors and suppressed anabolic markers compared to NCs or OACs cultured alone. In AMs, coculture with NCs resulted in a slight elevation of Rspo2 and AM-related genes, but not protein expression, compared to culture alone, but when cocultured with OACs, these inflammatory mediators were significantly enhanced at both the gene and protein levels. Astaxanthin reversed these changes in all the groups. In vivo, we observed a deterioration in cartilage quality after intra-articular injection of Rspo2 associated with medial meniscus (DMM)-induced instability in the OA group, and astaxanthin was protective in these groups. Our results collectively revealed that astaxanthin attenuated the process of OA by abolishing Rspo2 both in vitro and in vivo.

2021 EULAR recommendations regarding lifestyle behaviours and work participation to prevent progression of rheumatic and musculoskeletal diseases.

OBJECTIVES: A European League Against Rheumatism taskforce was convened to review the literature and develop recommendations on lifestyle behaviours for rheumatic and musculoskeletal diseases (RMDs). METHODS: Six lifestyle exposures (exercise, diet, weight, alcohol, smoking, work participation) and seven RMDs (osteoarthritis, rheumatoid arthritis, axial spondyloarthritis, psoriatic arthritis, systemic lupus erythematosus, systemic sclerosis, gout) were considered. The taskforce included health professionals in rheumatology, geriatricians, epidemiologists, public health experts, people with RMDs and exposure domain experts. Systematic reviews were conducted to gather available evidence, from which recommendations were developed. RESULTS: Five overarching principles and 18 specific recommendations were defined based on available evidence. The overarching principles define the importance of a healthy lifestyle, how lifestyle modifications should be implemented, and their role in relation to medical treatments. Exercise recommendations highlight the safety and benefits of exercise on pain and disability, particularly among people with osteoarthritis and axial spondyloarthritis. The diet recommendations emphasise the importance of a healthy, balanced diet for people with RMDs. People with RMDs and health professionals should work together to achieve and maintain a healthy weight. Small amounts of alcohol are unlikely to negatively affect the outcomes of people with RMDs, although people with rheumatoid arthritis and gout may be at risk of flares after moderate alcohol consumption. Smokers should be supported to quit. Work participation may have benefits on RMD outcomes and should be discussed in consultations. CONCLUSIONS: These recommendations cover a range of lifestyle behaviours and can guide shared decision making between people with RMDs and health professionals when developing and monitoring treatment plans.

Guia de boas práticas do cuidado do quadril infantil do Hospital do Servidor Público Municipal de São Paulo / Good practice guide for children's hip care at the Hospital do Servidor Público Municipal de São Paulo

Introdução: A Displasia de Desenvolvimento do Quadril (DDQ) é uma condição que pode ocorrer durante o crescimento ou desenvolvimento embrionário, fetal e infantil. O diagnóstico precoce e o tratamento adequado são essenciais para evitar complicações futuras, como a osteoartrose. Atualmente, é estabelecido que o posicionamento pós-natal é um fator causal para a ocorrência da DDQ. Deste modo, o posicionamento pós-natal como no uso de dispositivos como "charutinhos" e "cangurus" influencia na incidência de DDQ. Promover a conscientização de profissionais de saúde e pais de recém-nascidos sobre estes cuidados pode contribuir para um desenvolvimento saudável do quadril e uma menor incidência de DDQ. Objetivo: Elaborar uma cartilha de conscientização a respeito de ações e cuidados com o quadril infantil a fim de diminuir a incidência de displasia do desenvolvimento do quadril em crianças. Método: Revisão da literatura pelos autores, com o objetivo de sistematizar o conteúdo relevante, de forma acessível e didática na forma de uma cartilha que será distribuída aos pais, responsáveis e profissionais de saúde que acompanham as crianças. Resultados: A elaboração da cartilha será estruturada em tópicos abrangendo explicações relacionadas a displasia do desenvolvimento de quadril em formato de textos e imagens de forma informative e acessível. Discussão: A implementação de políticas que conscientizem sobre as práticas adequadas relacionadas ao posicionamento do quadril das crianças poderá diminuir a incidência da DDQ, implicando na diminuição de casos de osteoartrose futuros secundários a esta doença. Isto poderá ter impacto positivo tanto na qualidade de vida e morbimortalidade futuros, como também nos custos de saúde relacionados a dor, locomoção e tratamentos definitivos para os quadris afetados. Conclusão: A conscientização a respeito dos cuidados com o quadril das crianças poderá resultar, além da diminuição da incidência de casos de DDQ, no aumento da adesão ambulatorial de pacientes e responsáveis; promoção de políticas e linhas de cuidados relacionados à prevenção da DDQ; conscientização de profissionais e responsáveis a respeito da DDQ; diminuição de custos relacionados a complicações de diagnósticos tardios da DDQ; possibilitar a realização de estudos futuros relacionadas a implementação das medidas propostas. Palavras-chave: Displasia do desenvolvimento dos quadris. Quadril. Ortopedia Pediátrica.

A novel Atlantic salmon (Salmo salar) bone collagen peptide delays osteoarthritis development by inhibiting cartilage matrix degradation and anti-inflammatory.

Nowadays, the biological activity of collagen peptides has been revealed, but the effect of Atlantic salmon (Salmo salar) bone-derived collagen peptide (CPs) on osteoarthritis remains unclear. In this study, CPs was identified as a small molecular weight peptide rich in Gly-X-Y structure. Meanwhile, interleukin-1ß (IL-1ß)-induced hypertrophic chondrocytes and partial medial meniscectomy (pMMx) surgery model in rats were performed. In IL-1ß stimulated chondrocytes, CPs significantly increased the type-II collagen content, reduced the type-X collagen abundance and chondrocytes apoptosis. Meanwhile, CPs reversed the increased expression of matrix metalloproteinase, metalloproteinase with thrombospondin motifs and RUNX family transcription factor 2 in chondrocytes induced by IL-1ß. In vivo, CPs increased pain tolerance of rats and without organ toxicity at 1.6 g/kg.bw. CPs significantly decreased the levels of COMP and Helix-II in serum. Furthermore, a significant decrease of IL-1ß in synovial fluid and cartilage tissue were observed by CPs intervention. From Micro-CT, CPs (0.8 g/kg.bw) significantly decreased Tb.sp and SMI value. Meanwhile, the expression of tumor necrosis factor and interleukin-6 were reduced by CPs administration both in vitro and in vivo. Together, CPs showed potential to be a novel and safe dietary supplement for helping anti-inflammatory and cartilage regeneration, ultimately hindering osteoarthritis development. However, the clear mechanism of CPs's positive effect on osteoarthritis needs to be further explored.

RORß modulates a gene program that is protective against articular cartilage damage.

Osteoarthritis (OA) is the most prevalent chronic joint disease which increases in frequency with age eventually impacting most people over the age of 65. OA is the leading cause of disability and impaired mobility, yet the pathogenesis of OA remains unclear. Treatments have focused mainly on pain relief and reducing joint swelling. Currently there are no effective treatments to slow the progression of the disease and to prevent irreversible loss of cartilage. Here we demonstrate that stable expression of RORß in cultured cells results in alteration of a gene program that is supportive of chondrogenesis and is protective against development of OA. Specifically, we determined that RORß alters the ratio of expression of the FGF receptors FGFR1 (associated with cartilage destruction) and FGFR3 (associated with cartilage protection). Additionally, ERK1/2-MAPK signaling was suppressed and AKT signaling was enhanced. These results suggest a critical role for RORß in chondrogenesis and suggest that identification of mechanisms that control the expression of RORß in chondrocytes could lead to the development of disease modifying therapies for the treatment of OA.

Prophylactic administration of miR-451 inhibitor decreases osteoarthritis severity in rats.

Transfection of chondrocytes with microRNA-451(miR-451), present in growth zone cartilage of the growth plate, upregulates production of enzymes association with extracellular matrix degradation. miR-451 is also present in articular cartilage and exacerbates IL-1ß effects in articular chondrocytes. Moreover, when osteoarthritis (OA) was induced in Sprague Dawley rats via bilateral anterior cruciate ligament transection (ACLT), miR-451 expression was increased in OA cartilage compared to control, suggesting its inhibition might be used to prevent or treat OA. To examine the prophylactic and therapeutic potential of inhibiting miR-451, we evaluated treatment with miR-451 power inhibitor (451-PI) at the onset of joint trauma and treatment after OA had developed. The prophylactic animal cohort received twice-weekly intra-articular injections of either 451-PI or a negative control (NC-PI) beginning on post-surgical day 3. OA was allowed to develop for 24 days in the therapeutic cohort before beginning injections. All rats were killed on day 45. Micro-CT, histomorphometrics, OARSI scoring, and muscle force testing were performed on samples. 451-PI mitigated OA progression compared to NC-PI limbs in the prophylactic cohort based on histomorphometric analysis and OARSI scoring, but no differences were detected by micro-CT. 451-PI treatment beginning 24 days post-surgery was not able to reduce OA severity. Prophylactic administration of 451-PI mitigates OA progression in a post-trauma ACLT rat model supporting its potential to prevent OA development following an ACLT injury clinically.

Gingko biloba-inspired lactone prevents osteoarthritis by activating the AMPK-SIRT1 signaling pathway.

BACKGROUND: Uncoupled extracellular matrix (ECM) causes cartilage degeneration and osteoarthritis (OA) by suppressing the synthesis and activating the degradation of ECM components. Gingko biloba is a natural Chinese herb with a variety of biological functions; however, the extent to which it can protect against OA and the mechanisms involved are unknown. METHODS: In our study, using bioinformatics tools, we were able to identify an important lactone, bilobalide (BB), from Gingko biloba. In vitro experiments were performed to evaluate the potential therapeutic effects of BB on ECM homeostasis. In vivo experiments were conducted to assess the protection of systemic administration of BB on cartilage degeneration. Molecular mechanisms underlying BB-regulated anti-arthritic role were further explored. RESULTS: In interleukin-1ß-incubated human chondrocytes, in vitro treatment with BB increased the expression of cartilage anabolic proteins, while inhibiting the activities of ECM degrading enzymes. In a mice model, systemic administration of BB, in vivo, prevented post-traumatic cartilage erosion and attenuated the formation of abnormal osteophytes in the subchondral bone. Mechanistically, the activation of the adenosine 5'-monophosphate-activated protein kinase (AMPK)-sirtuin 1 (SIRT1) signaling pathway was involved in the anti-arthritic effects of BB. In vitro, blocking BB's chondroprotection with the AMPK-specific inhibitor Compound C abrogated it. CONCLUSIONS: These results demonstrated that BB extracted from Gingko biloba regulates ECM balance to prevent OA by activating the AMPK-SIRT1 signaling pathway. This study proposed the monomer BB, a traditional Chinese medicine, as a de novo therapeutic insight for OA. Schematic representation of the experimental design. Based on the bioinformatic analysis, bilobalide (BB), a natural herb Gingko biloba-derived ingredient, was identified as a candidate for treating osteoarthritis. In vitro, BB treatment not only facilitates cartilage extracellular matrix synthesis but also inhibits proteolytic enzyme activities. In vivo intraperitoneal injection of BB improves cartilage degeneration and subchondral bone sclerosis. BB, in particular, had anti-arthritic effects by activating the AMPK-SIRT1 signaling pathway.

Necroptotic TNFα-Syndecan 4-TNFα Vicious Cycle as a Therapeutic Target for Preventing Temporomandibular Joint Osteoarthritis.

Temporomandibular joint osteoarthritis (TMJOA) is a chronic degenerative disease for which the underlying mechanism still remains unclear. Compared with apoptosis and autophagy, necroptosis causes greater harm to tissue homeostasis by releasing damage-associated molecular patterns (DAMPs). However, the role of necroptosis and downstream key DAMPs in TMJOA is unknown. Here, rodent models of TMJOA were established by the unilateral anterior crossbite (UAC). Transmission electron microscopy (TEM) and immunohistochemistry of receptor interacting protein kinase 3 (RIPK3)/phosphorylation of mixed lineage kinase domain-like protein (pMLKL) were conducted to evaluate the occurrence of necroptosis in vivo. The therapeutic effects of blocking necroptosis were achieved by intra-articularly injecting RIPK3 or MLKL inhibitors and using RIPK3 or MLKL knockout mice. In vitro necroptosis of condylar chondrocyte was induced by combination of tumor necrosis factor alpha (TNFα), second mitochondria-derived activator of caspases (SMAC) mimetics and carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]- fluoromethylketone (z-VAD-fmk). The possible DAMPs released by necroptotic chondrocytes were screened by quantitative proteomics and blocked by specific antibody. Translucent cytosol, swollen organelles, and ruptured cell membranes, features of necroptosis, were frequently manifested in chondrocytes at the early stage of condylar cartilage degeneration in TMJOA, which was accompanied by upregulation of RIPK3/pMLKL. Inhibiting or knocking out RIPK3/MLKL significantly prevented cartilage degeneration. DAMPs released by necroptotic condylar chondrocytes, such as syndecan 4 (SDC4) and heat shock protein 90 (HSP90), were verified. Furthermore, blocking the function of SDC4 significantly attenuated the expression of TNFα in cartilage and synovium, and accordingly increased cartilage thickness and reduced synovial inflammation. Thus, the necroptotic vicious cycle of TNFα-SDC4-TNFα contributes to cartilage degeneration and synovitis, and can serve as a potential therapeutic target for treating TMJOA. © 2022 American Society for Bone and Mineral Research (ASBMR).

Metformin and resveratrol suppress type 2 diabetes mellitus-induced articular cartilage damage in rats associated with the inhibition of inflammation and augmentation of proteoglycans / La metformina y el resveratrol suprimen el daño del cartílago articular inducido por la diabetes mellitus tipo 2 en ratas asociado con la inhibición de la inflamación y el aumento de proteoglicanos

SUMMARY: Induction of osteoarthritis (OA) following diabetes is characterized by a sever inflammation of the joints that can lead to disability. The cartilage content of proteoglycans can substantially be reduced, following the induction of diabetes mellitus associated with inflammation as well as knee joint injury, and the antidiabetic drug metformin combined with the anti-inflammatory agent resveratrol can prevent these deleterious effects. Therefore, insulin-independent diabetes, type 2 diabetes mellitus (T2DM) was induced in Albino rats by streptozotocin (STZ) injection (50 mg/kg) after being fed on a high carbohydrate and fat diets for 2 weeks. The protective group of rats which also received a single injection of STZ was treated daily with metformin (Met; 200 mg/kg) and resveratrol (Res; 30 mg/kg) for 12 weeks. Harvested knee joint tissues were prepared for basic histology stain and for proteoglycans staining using light microscopy. Histology images showed in diabetic rats (T2DM) OA development as demonstrated by profound injury to the knee joint and severe decrease of articular cartilage proteoglycans content, which were substantialy protected by Met+Res. Met+Res also significantly (p< 0.0001) decreased diabetes induced glycemia, dyslipidemia, and the inflammatory biomarkers, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and high sensitivity C-reactive protein (hs-CRP). In addition, there was a significant correlation between OA and glycemia, dyslipidemia, and inflammation. Collectively, we demonstrate an association between knee joint damage and biomarkers of glycemia, dyslipidemia, and inflammation in diabetes-induced OA, with metformin plus resveratrol providing protective effects.

RESUMEN: La inducción de osteoartritis (OA) después de la diabetes se caracteriza por una inflamación severa de las articulaciones que puede conducir a la discapacidad. El contenido de cartílago de proteoglicanos se puede reducir sustancialmente, luego de la inducción de diabetes mellitus asociada con inflamación y lesión en la articulación de la rodilla sin embargo, el fármaco antidiabético metformina combinado con el agente antiinflamatorio resveratrol puede prevenir estos efectos nocivos. Por lo tanto, se indujo diabetes insulino dependiente, diabetes mellitus tipo 2 (T2DM) en ratas albinas mediante inyección de estreptozotocina (STZ) (50 mg/kg) después de haber sido alimentadas con dietas ricas en carbohidratos y grasas durante 2 semanas. El grupo protector de ratas que también recibió una inyección única de STZ fue tratado diariamente con metformina (Met; 200 mg/kg) y resveratrol (Res; 30 mg/kg) durante 12 semanas. Tejidos de la articulación de la rodilla fueon retirados y teñidos con histología básica y tinción de proteoglicanos usando microscopía óptica. Las imágenes histológicas en ratas diabéticas mostraban (T2DM) desarrollo de OA visualizadas por una lesión profunda en la articulación de la rodilla y una disminución severa del contenido de proteoglicanos del cartílago articular, los cuales estaban sustancialmente protegidos por Met+Res. Met+Res. También disminuyó significativamente (p< 0,0001) la glucemia inducida por la diabetes, la dislipidemia y los biomarcadores inflamatorios, el factor de necrosis tumoral alfa (TNF-α), la interleucina-6 (IL-6) y la proteína C reactiva de alta sensibilidad (PCR-hs). Además, hubo una correlación significativa entre la OA y la glucemia, la dislipidemia y la inflamación. En conjunto, demostramos una asociación entre el daño de la articulación de la rodilla y los biomarcadores de glucemia, dislipidemia e inflamación en la OA inducida por diabetes, con metformina más resveratrol que brindan efectos protectores.

Systemic inhibition or global deletion of CaMKK2 protects against post-traumatic osteoarthritis.

OBJECTIVE: To investigate the role of Ca2+/calmodulin-dependent protein kinase 2 (CaMKK2) in post-traumatic osteoarthritis (PTOA). METHODS: Destabilization of the medial meniscus (DMM) or sham surgeries were performed on 10-week-old male wild-type (WT) and Camkk2-/- mice. Half of the DMM-WT mice and all other cohorts (n = 6/group) received tri-weekly intraperitoneal (i.p.) injections of saline whereas the remaining DMM-WT mice (n = 6/group) received i.p. injections of the CaMKK2 inhibitor STO-609 (0.033 mg/kg body weight) thrice a week. Study was terminated at 8- or 12-weeks post-surgery, and knee joints processed for microcomputed tomography imaging followed by histology and immunohistochemistry. Primary articular chondrocytes were isolated from knee joints of 4-6-day-old WT and Camkk2-/- mice, and treated with 10 ng/ml interleukin-1ß (IL)-1ß for 24 or 48 h to investigate gene and protein expression. RESULTS: CaMKK2 levels and activity became elevated in articular chondrocytes following IL-1ß treatment or DMM surgery. Inhibition or absence of CaMKK2 protected against DMM-associated destruction of the cartilage, subchondral bone alterations and synovial inflammation. When challenged with IL-1ß, chondrocytes lacking CaMKK2 displayed attenuated inflammation, cartilage catabolism, and resistance to suppression of matrix synthesis. IL-1ß-treated CaMKK2-null chondrocytes displayed decreased IL-6 production, activation of signal transducer and activator of transcription 3 (Stat3) and matrix metalloproteinase 13 (MMP13), indicating a potential mechanism for the regulation of inflammatory responses in chondrocytes by CaMKK2. CONCLUSIONS: Our findings reveal a novel function for CaMKK2 in chondrocytes and highlight the potential for its inhibition as an innovative therapeutic strategy in the prevention of PTOA.

Oral administration of berberine limits post-traumatic osteoarthritis development and associated pain via AMP-activated protein kinase (AMPK) in mice.

OBJECTIVE: We investigated the effect of berberine, a natural plant product that can activate AMP-activated protein kinase (AMPK), on Osteoarthritis (OA) development and associated pain in mice. DESIGN: Human primary knee chondrocytes were utilized to investigate how AMPK is activated by berberine. Both global knockout (KO) of AMPKα1 and congenic wild type (WT) mice were subjected to the post-traumatic OA through destabilization of medial meniscus (DMM) surgery. Two weeks after surgery, the mice were randomly divided into two groups with one group receiving berberine chloride daily via drinking water and were sacrificed at 6 and 12 weeks after surgery. OA severity was assessed by histological and histomorphometric analyses of cartilage degradation, synovitis, and osteophyte formation. OA-associated pain behavior was also determined. Immunohistochemistry (IHC) analyses were carried out to examine changes in AMPK signaling. RESULTS: Berberine induced phosphorylation of AMPKα (Thr172) via liver kinase B1 (LKB1), the major upstream kinase of AMPK, in chondrocytes in vitro. Both WT and AMPKα1KO developed OA and associated pain post DMM surgery. However, treatment with berberine significantly reduced severity of OA and associated pain in WT but not AMPKα1KO mice. IHC analysis of WT DMM knee cartilage further revealed that berberine inhibited concomitant loss of expression and phosphorylation of AMPKα and expression of SIRT1 and SIRT3, suggesting an important role of activation of AMPK signaling in mediating beneficial effect of berberine. CONCLUSIONS: Berberine acts through AMPK to reduce joint structural damage and pain associated with post-traumatic OA in mice in vivo.

Metformin attenuates osteoclast-mediated abnormal subchondral bone remodeling and alleviates osteoarthritis via AMPK/NF-κB/ERK signaling pathway.

This study explored the mechanism by which metformin (Met) inhibits osteoclast activation and determined its effects on osteoarthritis (OA) mice. Bone marrow-derived macrophages were isolated. Osteoclastogenesis was detected using tartrate-resistant acid phosphatase (TRAP) staining. Cell proliferation was evaluated using CCK-8, F-actin rings were detected by immunofluorescence staining, and bone resorption was detected using bone slices. Nuclear factor kappa-B (NF-κB) and nuclear factor of activated T-cell cytoplasmic 1 (NFATc1) were detected using luciferase assays, and the adenosine monophosphate-activated protein kinase (AMPK), NF-κB, and mitogen-activated protein kinase (MAPK) signaling pathways were detected using western blotting. Finally, expression of genes involved in osteoclastogenesis was measured using quantitative polymerase chain reaction. A knee OA mouse model was established by destabilization of the medial meniscus (DMM). Male C57BL/6J mice were assigned to sham-operated, DMM+vehicle, and DMM+Met groups. Met (100 mg/kg/d) or vehicle was administered from the first day postoperative until sacrifice. At 4- and 8-week post OA induction, micro-computed tomography was performed to analyze microstructural changes in the subchondral bone, hematoxylin and eosin staining and Safranin-O/Fast Green staining were performed to evaluate the degenerated cartilage, TRAP-stained osteoclasts were enumerated, and receptor activator of nuclear factor κB ligand (RANKL), AMPK, and NF-κB were detected using immunohistochemistry. BMM proliferation was not affected by Met treatment below 2 mM. Met inhibited osteoclast formation and bone resorption in a dose-dependent manner in vitro. Met suppressed RANKL-induced activation of p-AMPK, NF-κB, phosphorylated extracellular regulated protein kinases (p-ERK) and up-regulation of genes involved in osteoclastogenesis. Met reversed decreases in BV/TV, Tb.Th, Tb.N, and CD, and an increase in Tb.Sp at 4 weeks postoperatively. The number of osteoclasts and OARSI score were decreased by Met without effect on body weight or blood glucose levels. Met inhibited RANKL, p-AMPK, and NF-κB expression in early OA. The mechanism by which Met inhibits osteoclast activation may be associated with AMPK/NF-κB/ERK signaling pathway, indicating a novel strategy for OA treatment.

Activation of the alpha 7 nicotinic acetylcholine receptor mitigates osteoarthritis progression by inhibiting NF-κB/NLRP3 inflammasome activation and enhancing autophagy.

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage degradation. Alpha 7 nicotinic acetylcholine receptor (α7nAChR) is associated with inflammatory and metabolic responses in OA. However, the mechanisms underlying the pathological process of OA remain unclear. The aim of the present study was to examine the role and mechanisms of α7nAChR-mediated autophagy and anti-inflammatory response in chondroprotection. Monosodium iodoacetate (MIA)-induced Wistar rat OA model was used to assess the in vivo effects of the ɑ7nAChR agonist (PNU-282987). The histopathological characteristics of OA were evaluated by immunohistochemistry (IHC), and the levels of autophagy markers were determined by western blotting and transmission electron microscopy. The anti-inflammatory effect of the ɑ7nAChR agonist was assessed by IHC, quantitative real-time polymerase chain reaction, and western blotting. Parallel experiments to determine the molecular mechanisms through which the ɑ7nAChR agonist prevents OA were performed using interleukin-1ß (IL-1ß)-treated chondrocytes. Our results showed that PNU-282987 reduced cartilage degeneration and matrix metalloproteinase (MMP)-1 and MMP-13 expressions. Activating α7nAChR with PNU-282987 significantly promoted MIA/IL-1ß-induced chondrocyte autophagy, as demonstrated by the increase in LC3-II/LC3-I ratio, Beclin-1 levels, and autophagosome number. Furthermore, treating chondrocyte with ULK1 siRNA attenuated the PNU282987-induced enhancement of LC3-II/LC3-I ratio and Beclin-1 level. Additionally, PNU282987 suppressed NF-κB/NLRP3 inflammasome activation by inhibiting the ROS/TXNIP pathway and suppressed tumor necrosis factor-ɑ and IL-1ß secretion in MIA/IL-1ß-treated chondrocytes. Our results demonstrate that the activation of α7nAChR promotes chondrocyte autophagy and attenuates inflammation to mitigate OA progression, providing a novel target for the treatment of OA.

High-Molecular-Weight Hyaluronic Acid Inhibits IL-1ß-Induced Synovial Inflammation and Macrophage Polarization through the GRP78-NF-κB Signaling Pathway.

Recent evidence has suggested that synovial inflammation and macrophage polarization were involved in the pathogenesis of osteoarthritis (OA). Additionally, high-molecular-weight hyaluronic acid (HMW-HA) was often used clinically to treat OA. GRP78, an endoplasmic reticulum (ER) stress chaperone, was suggested to contribute to the hyperplasia of synovial cells in OA. However, it was still unclear whether HMW-HA affected macrophage polarization through GRP78. Therefore, we aimed to identify the effect of HMW-HA in primary synovial cells and macrophage polarization and to investigate the role of GRP78 signaling. We used IL-1ß to treat primary synoviocytes to mimic OA, and then treated them with HMW-HA. We also collected conditioned medium (CM) to culture THP-1 macrophages and examine the changes in the phenotype. IL-1ß increased the expression of GRP78, NF-κB (p65 phosphorylation), IL-6, and PGE2 in primary synoviocytes, accompanied by an increased macrophage M1/M2 polarization. GRP78 knockdown significantly reversed the expression of IL-1ß-induced GRP78-related downstream molecules and macrophage polarization. HMW-HA with GRP78 knockdown had additive effects in an IL-1ß culture. Finally, the synovial fluid from OA patients revealed significantly decreased IL-6 and PGE2 levels after the HMW-HA treatment. Our study elucidated a new form of signal transduction for HMW-HA-mediated protection against synovial inflammation and macrophage polarization and highlighted the involvement of the GRP78-NF-κB signaling pathway.

Circular RNA hsa_circ_0005567 overexpression promotes M2 type macrophage polarization through miR-492/SOCS2 axis to inhibit osteoarthritis progression.

Synovial macrophage polarization is essential for osteoarthritis (OA) development. Our study aims to investigate the underlying function and the molecular mechanisms of hsa_circ_0005567 in macrophage polarization. Circular RNA (CircRNA), microRNA (miRNA), and mRNA expression levels were detected by quantitative reverse transcription polymerase chain reaction (RT-qPCR). RNA pull down, luciferase reporter were employed to test the interaction between miR-492 and hsa_circ_0005567/suppressors of cytokine signaling 2 (SOCS2). Ectopic overexpression was used to evaluate the function of hsa_circ_0005567. The supernatant of THP-1 cells was used to incubate chondrocytes. Cell Counting Kit-8 (CCK-8) and flow cytometry were conducted to determine cell viability, proportion of M1 or M2 macrophages and apoptotic rate. The results showed that the hsa_circ_0005567 expression level was downregulated in the synovial tissues of osteoarthritis patients. Overexpression of hsa_circ_0005567 inhibited M1 macrophage polarization, and promoted M2 macrophage polarization. Hsa_circ_0005567 was proved to be a molecular sponge for miR-492, and SOCS2 was verified as the target of miR-492. MiR-492 mimic could reverse the effect of hsa_circ_0005567 overexpression on macrophage polarization. Besides, the supernatant from LPS-treated THP-1 macrophage significantly decreased chondrocytes cell viability and increased cell apoptosis ratio, which was reversed by hsa_circ_0005567 overexpression. In conclusion, hsa_circ_0005567 overexpression promoted M2 macrophage polarization through miR-492/SOCS2 axis to reduced chondrocyte apoptosis, which could inhibit osteoarthritis progression.

Chlorogenic acid protects human chondrocyte C28/I2 cells from oxidative stress-induced cell death through activation of autophagy.

AIMS: The development of osteoarthritis (OA), the most common form of arthritis, is commonly associated with oxidative stress. Indeed, the lack of antioxidant responses largely increases OA incidence. OA is a leading cause of disability in the elderly, which reduces the quality of life and places high socioeconomic burdens on them. Several polyphenolic compounds, including chlorogenic acid (CGA), have shown cytoprotective effects via their antioxidant activity, but the exact mechanism (s) remain elusive. In this study, we demonstrated how CGA protects human chondrocytes against H2O2-induced apoptosis. MATERIALS AND METHODS: The cytoprotective effect by CGA in 500 µM hydrogen peroxide-treated C28/I2 cells was evaluated by cell viability, TUNEL assay, and Western blotting analyses, and autophagy assessment was further performed by AO and MDC staining and tandem mRFP-GFP fluorescence analyses. KEY FINDINGS: Treatment of CGA to the human chondrocytes under oxidative stress significantly decreased apoptosis markers, such as cleaved caspase 3 and cleaved PARP, and increased anti-apoptotic marker Bcl-xL and the antioxidant response proteins NRF2 and NF-κB. Furthermore, CGA-dependent activation of antioxidant response proteins NRF2 and NF-κB and its protective effects in chondrocytes depended on autophagy. Indeed, CGA treatment and autophagy induction significantly decreased reactive oxygen species (ROS)-induced apoptosis. SIGNIFICANCE: CGA exhibited the protective effect to human chondrocyte C28/I2 cells against oxidative stress-induced cell death by activating autophagy. These findings indicate that CGA is a potential therapeutic agent for the development of OA drugs.

Preoperative T2 mapping MRI of articular cartilage values predicts postoperative osteoarthritis progression following rotational acetabular osteotomy.

AIMS: Rotational acetabular osteotomy (RAO) has been reported to be effective in improving symptoms and preventing osteoarthritis (OA) progression in patients with mild to severe develomental dysplasia of the hip (DDH). However, some patients develop secondary OA even when the preoperative joint space is normal; determining who will progress to OA is difficult. We evaluated whether the preoperative cartilage condition may predict OA progression following surgery using T2 mapping MRI. METHODS: We reviewed 61 hips with early-stage OA in 61 patients who underwent RAO for DDH. They underwent preoperative and five-year postoperative radiological analysis of the hip. Those with a joint space narrowing of more than 1 mm were considered to have 'OA progression'. Preoperative assessment of articular cartilage was also performed using 3T MRI with the T2 mapping technique. The region of interest was defined as the weightbearing portion of the acetabulum and femoral head. RESULTS: There were 16 patients with postoperative OA progression. The T2 values of the centre to the anterolateral region of the acetabulum and femoral head in the OA progression cases were significantly higher than those in patients without OA progression. The preoperative T2 values in those regions were positively correlated with the narrowed joint space width. The receiver operating characteristic analysis revealed that the T2 value of the central portion in the acetabulum provided excellent discrimination, with OA progression patients having an area under the curve of 0.858. Furthermore, logistic regression analysis showed T2 values of the centre to the acetabulum's anterolateral portion as independent predictors of subsequent OA progression (p < 0.001). CONCLUSION: This was the first study to evaluate the relationship between intra-articular degeneration using T2 mapping MRI and postoperative OA progression. Our findings suggest that preoperative T2 values of the hip can be better prognostic factors for OA progression than radiological measures following RAO. Cite this article: Bone Joint J 2021;103-B(9):1472-1478.