IL-38-mediated NLRP3/caspase-1 inhibition is a disease-modifying treatment for TMJ inflammation.

Recently, interleukin-38 (IL-38) was identified as an important anti-inflammatory and immunosuppressive factor, but its functional role in temporomandibular joint (TMJ) inflammation remains unknown. This study aimed to elucidate how IL-38 affects chondrocytes and the underlying mechanism that contributes to anti-inflammatory processes in the TMJ. Western blotting, quantitative real-time PCR, enzyme-linked immunosorbent assay, and immunofluorescence analysis were used to verify that IL-38 has anti-inflammatory effects on chondrocytes, and the related key pathways were analyzed by western blotting. SiRNA-IL-38, siRNA-NLRP3, and MCC950 were used to investigate the mechanism underlying the anti-inflammatory effects of IL-38. Inflammation models were induced by injection of complete Freund's adjuvant in TMJ with mouse recombinant IL-38 in in vivo studies. Histological and immunohistochemical analyses were used to investigate histological changes in the cartilage. The results showed that IL-38 inhibited the expression of inflammatory cytokines and MMPs. IL-38 limited inflammation by inhibiting the expression of MAPKs/NF-κB and the NLRP3/caspase-1 pathway. In vivo, IL-38 reduced chondrocyte inflammation and limited cartilage degeneration. This study shows for the first time that IL-38 plays a protective role in TMJ cartilage. IL-38 exerts anti-inflammatory effects through the NLRP3/caspase-1 pathway and may be a promising agent for treating TMJ inflammation.

Synovial Macrophages in Osteoarthritis: The Key to Understanding Pathogenesis?

Effective treatment of osteoarthritis (OA) remains a huge clinical challenge despite major research efforts. Different tissues and cell-types within the joint contribute to disease pathogenesis, and there is great heterogeneity between patients in terms of clinical features, genetic characteristics and responses to treatment. Inflammation and the most abundant immune cell type within the joint, macrophages, have now been recognised as possible players in disease development and progression. Here we discuss recent findings on the involvement of synovial inflammation and particularly the role of synovial macrophages in OA pathogenesis. Understanding macrophage involvement may hold the key for improved OA treatments.

Cartilage Protective and Immunomodulatory Features of Osteoarthritis Synovial Fluid-Treated Adipose-Derived Mesenchymal Stem Cells Secreted Factors and Extracellular Vesicles-Embedded miRNAs.

Intra-articular administration of adipose-derived mesenchymal stem cells (ASCs), either in vitro expanded or within adipose tissue-based products obtained at point-of-care, has gained popularity as innovative regenerative medicine approach for osteoarthritis (OA) treatment. ASCs can stimulate tissue repair and immunomodulation through paracrine factors, both soluble and extracellular vesicles (EV) embedded, collectively defining the secretome. Interaction with the degenerative/inflamed environment is a crucial factor in understanding the finely tuned molecular message but, to date, the majority of reports have described ASC-secretome features in resting conditions or under chemical stimuli far from the in vivo environment of degenerated OA joints. In this report, the secretory profile of ASCs treated with native synovial fluid from OA patients was evaluated, sifting 200 soluble factors and 754 EV-embedded miRNAs. Fifty-eight factors and 223 EV-miRNAs were identified, and discussed in the frame of cartilage and immune cell homeostasis. Bioinformatics gave a molecular basis for M2 macrophage polarization, T cell proliferation inhibition and T reg expansion enhancement, as well as cartilage protection, further confirmed in an in vitro model of OA chondrocytes. Moreover, a strong influence on immune cell chemotaxis emerged. In conclusion, obtained molecular data support the regenerative and immunomodulatory properties of ASCs when interacting with osteoarthritic joint environment.

Circ_0134111 knockdown relieves IL-1ß-induced apoptosis, inflammation and extracellular matrix degradation in human chondrocytes through the circ_0134111-miR-515-5p-SOCS1 network.

BACKGROUND: Osteoarthritis (OA) is characterized by chondrocyte injury and dysfunction, such as excessive apoptosis, inflammatory response and extracellular matrix (ECM) degradation. Circular RNA (circRNA) deregulation is reported to be involved in OA. Our study aimed to explore the role of circ_0134111 in OA. METHODS: Human chondrocytes were treated with interleukin-1ß (IL-1ß) to mimic OA cell model. The expression of circ_0134111, miR-515-5p and suppressor of cytokine signaling 1 (SOCS1) mRNA was measured by real-time quantitative polymerase chain reaction (RT-qPCR), and the protein levels of SOCS1 and apoptosis-/inflammation-/ECM-related markers were determined by western blot. Cell proliferation and cell apoptosis were assessed using cell counting kit-8 (CCK-8) and flow cytometry assay, respectively. For mechanism analysis, the predicted interaction between miR-515-5p and circ_0134111 or SOCS1 was verified by dual-luciferase reporter assay, pull-down assay and RNA immunoprecipitation (RIP) assay. Rescue experiments were performed to explore the interplay between miR-515-5p and circ_0134111 or SOCS1. RESULTS: Circ_0134111 was overexpressed in OA cartilage tissues and IL-1ß-induced chondrocytes. IL-1ß-induced chondrocyte apoptosis, inflammatory responses and ECM degradation were alleviated by circ_0134111 knockdown or miR-515-5p restoration. Circ_0134111 acted as miR-515-5p sponge to regulate miR-515-5p expression, and miR-515-5p deficiency reversed the effects of circ_0134111 knockdown in IL-1ß-induced chondrocytes. MiR-515-5p directly bound to SOCS1, and circ_0134111 decoyed miR-515-5p to increase SOCS1 level. MiR-515-5p restoration alleviated IL-1ß-induced chondrocyte apoptosis, inflammatory responses and ECM degradation, While SOCS1 overexpression partly abolished these effects. CONCLUSION: Circ_0134111 knockdown alleviated apoptosis, inflammatory responses and ECM degradation in OA cell model by mediating the miR-515-5p-SOCS1 network, hinting that circ_0134111 was involved in OA progression.

De-Epithelialized Heterotopic Tracheal Allografts without Immunosuppressants in Dogs: Long-Term Results for Cartilage Viability and Structural Integrity.

OBJECTIVES: Reconstruction of long segmental tracheal defects is difficult because no ideal tracheal substitutes are currently available. Tracheal allotransplantation maintains cartilage and epithelium viability but requires immunosuppression because of epithelial immunogenicity. We aimed to obtain an epithelium-decellularized allograft that maintains cartilage viability and to evaluate long-term outcomes of such allografts implanted on dog backs without immunosuppressants. METHODS: Twenty-five tracheas harvested from mongrel dogs were used to explore the period of epithelium decellularization by combined use of 1% sodium dodecyl sulfate and an organ preservation solution and to assess the chondrocyte viability and immunogenicity of the tracheas after decellularization. Sixteen epithelium-decellularized tracheal allografts and 10 fresh tracheal segments (6 cm long) were implanted in 26 beagles for durations of 10 days and 1, 3, 6, and 12 months. Macroscopic and microscopic examinations were used to evaluate the morphology, viability, and immune rejection of the allografts. Safranin-O staining was used to detect glycosaminoglycans. RESULTS: The epithelium disappeared after 24 hours of decellularization. At 72 hours, almost no nuclei remained in the mucosa, while the mean survival rate of chondrocytes was 88.1%. Histological analysis demonstrated that the allograft retained intact tracheal rings and viable cartilage after heterotopic implantation for 1 year, with no immunological rejection. There were no significant differences in the glycosaminoglycan contents among the implanted epithelium-decellularized allografts. CONCLUSIONS: Epithelium-decellularized tracheal allografts with chondrocyte viability can be achieved by combined use of a detergent and organ preservation solution, which showed satisfactory cartilage viability and structural integrity after long-term heterotopic transplantation. Further studies on orthotopic transplantation are needed to assess the feasibility of allografts in reconstructing long segmental tracheal defects.

IVIG ameliorate inflammation in collagen-induced arthritis: projection for IVIG therapy in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease that leads to joint destruction and disability. Despite a significant progress in administration of biological agents for RA patients, there is still a need for improved therapy. Intravenous immunoglobulins (IVIG), a pooled polyspecific immunoglobulin (Ig)G extracted from 5000 to 20 000 healthy subjects, showed beneficial therapeutic effect in patients with immune deficiency, sepsis and autoimmune diseases. The current study aimed to investigate the beneficial effect of treatment with IVIG in established collagen-induced arthritis in DBA/1j mice. Murine arthritis was induced in DBA/1j mice. Treatment with IVIG began when the disease was established. The clinical score was followed twice a week until day 48. The mice were bled for plasma and the paws were hematoxylin and eosin (H&E)-stained. Cytokine profile in the plasma was analyzed by Luminex technology and titers of circulating anti-collagen antibodies in the plasma was tested by enzyme-linked immunosorbent assay. Our results show that treatment with IVIG in murine significantly reduced the clinical arthritis score (P < 0·001). Moreover, mode of action showed that IVIG significantly reduced circulating levels of inflammatory cytokines [interferon (IFN)-γ, interleukin (IL)-1ß, IL-17, IL-6, tumor necrosis factor (TNF)-α, P < 0·001], inhibiting anti-collagen antibodies (P < 0·001) in the plasma of collagen-induced arthritis mice. Importantly, histopathological examination revealed that IVIG treatment prevented the migration of inflammatory immune cells into the cartilage and synovium, reduced the extent of joint damage and preserved joint architecture. Our results proved for the first time the valuable anti-inflammatory treatment of IVIG in experimental RA. We propose IVIG therapy for a subgroup of patients with rheumatologically related diseases.

Construction of CII-Specific CAR-T to Explore the Cytokine Cascades Between Cartilage-Reactive T Cells and Chondrocytes.

Cytokine cascades exist in many autoimmune disorders which amplify and sustain the autoimmune process and lead to chronic inflammatory injury to the host tissues. Increasing evidence indicates that chondrocytes can interact with T cells, which may be a crucial event in inflammatory arthritis. To address the reciprocal influences of cartilage-reactive T cells and chondrocytes, we constructed cartilage-reactive T cells by developing a type II collagen-specific chimeric antigen receptor (CII-CAR). An in vitro co-culture model of CII-CAR-T cells and fresh cartilage was developed, in which CII-CAR-T displayed specific proliferative capacity and cytokine release against fresh cartilage samples, and chondrocytes could respond to CII-CAR-T cells by secreting IL-6. The proposed model will help us to explore the possible cytokine cascades between cartilage-reactive T cells and cartilage.

Modeling Rheumatoid Arthritis In Vitro: From Experimental Feasibility to Physiological Proximity.

Rheumatoid arthritis (RA) is a chronic, inflammatory, and systemic autoimmune disease that affects the connective tissue and primarily the joints. If not treated, RA ultimately leads to progressive cartilage and bone degeneration. The etiology of the pathogenesis of RA is unknown, demonstrating heterogeneity in its clinical presentation, and is associated with autoantibodies directed against modified self-epitopes. Although many models already exist for RA for preclinical research, many current model systems of arthritis have limited predictive value because they are either based on animals of phylogenetically distant origin or suffer from overly simplified in vitro culture conditions. These limitations pose considerable challenges for preclinical research and therefore clinical translation. Thus, a sophisticated experimental human-based in vitro approach mimicking RA is essential to (i) investigate key mechanisms in the pathogenesis of human RA, (ii) identify targets for new therapeutic approaches, (iii) test these approaches, (iv) facilitate the clinical transferability of results, and (v) reduce the use of laboratory animals. Here, we summarize the most commonly used in vitro models of RA and discuss their experimental feasibility and physiological proximity to the pathophysiology of human RA to highlight new human-based avenues in RA research to increase our knowledge on human pathophysiology and develop effective targeted therapies.

MicroRNA-197 regulates chondrocyte proliferation, migration, and inflammation in pathogenesis of osteoarthritis by targeting EIF4G2.

Recent studies have demonstrated that microRNAs (miRNAs) are involved in many pathological conditions including osteoarthritis (OA). In the present study, we aimed to investigate the role of miR-197 in OA and the potential molecular mechanism. The expression levels of miR-197 were detected by quantitative real-time PCR analysis. Cell proliferation and migration abilities were performed by 3-(4,5-dimethylthiazol-2-yl)-2,5-di-phenyltetrazolium bromide and transwell assays. The concentrations of inflammatory cytokines, including IL-1ß, IL-6, and TNF-α, were detect using ELISA assay. Furthermore, luciferase reporter and rescue assays were applied to identify the functional target gene of miR-197 in OA. The results showed that miR-197 expression was significantly down-regulated in the OA cartilage tissues compared with normal cartilage tissues, accompanied by up-regulation of EIF4G2 expression. An inverse correlation was found between EIF4G2 and miR-197 expressions in OA cartilage tissues. Treatment with miR-197 mimics promoted the growth and migration abilities of chondrocytes, while miR-197 inhibitors induced the opposite effects. Furthermore, restoration of miR-197 significantly decreased IL-1ß, IL-6, and TNF-α expression, whereas knockdown of miR-197 led to a induction in these inflammatory mediators. Moreover, EIF4G2 was predicted and confirmed as a directly target of miR-197. Overexpressed miR-197 could down-regulate EIF4G2 expression in chondrocytes, while miR-197 knockdown could elevate EIF4G2 expression. Additionally, EIF4G2 overexpression reversed the effects of miR-197 mimics on chondrocytes proliferation, migration, and inflammation. Taken together, our study demonstrated that miR-197 promotes chondrocyte proliferation, increases migration, and inhibits inflammation in the pathogenesis of OA by targeting EIF4G2, indicating the potential therapeutic targets of the miR-197/EIF4G2 axis for OA treatment.

Bone-Inspired Tube Filling Decellularized Matrix of Toad Cartilage Provided an Osteoinductive Microenvironment for Mesenchymal Stem Cells to Facilitate the Radius Defect Repair of Rabbit.

Toad bone not only contains the rich cartilage-like matrix but also presents low immunogenicity. It is inferred that decellularized toad bone matrix (dBECM) may provide the more profitable osteoinductive microenvironment for mesenchymal stem cells (MSCs) to promote the repair of bone defects. Herein, a hollow bone-inspired tube is first made from hydroxyapatite (HA) and poly (γ-glutamic acid) (PGA), and then MSCs/dBECM hydrogel is uniformly filled to its central cavity, constructing a biomimetic bone (dBECM + MSCs - PGA + HA). In vitro scratch and transwell experiments show that dBECM hydrogel not only effectively promotes migration and proliferation of MSCs but also induces their osteogenic differentiation. Moreover, the less inflammatory macrophages infiltrate at rat skin after subcutaneously injecting dBECM hydrogel, indicating its low potential for inflammatory attack. After implanting dBECM + MSCs - PGA + HA to critical radius defect of rabbit, X-ray and CT imaging shows that the cortex is effectively regenerated and the medullary cavity recanalization is completed at 20 weeks. Moreover, the expression of Collagen-II and OCN are obviously increased in the defect after implanting dBECM + MSCs - PGA + HA. The therapeutic mechanism of dBECM + MSCs - PGA + HA scaffold are highly associated with the enhanced angiogenesis. Collectively, the biomimetic dBECM + MSCs - PGA + HA scaffold may be a promising strategy to improve radius defect healing efficiency.

Targeting Extracellular Vesicles to the Arthritic Joint Using a Damaged Cartilage-Specific Antibody.

The targeted delivery of therapies to diseased tissues offers a safe opportunity to achieve optimal efficacy while limiting systemic exposure. These considerations apply to many disease indications but are especially relevant for rheumatoid arthritis (RA), as RA is a systemic autoimmune disease which affects multiple joints. We have identified an antibody that is specific to damaged arthritic cartilage (anti-ROS-CII) that can be used to deliver treatments specifically to arthritic joints, yielding augmented efficacy in experimental arthritis. In the current study, we demonstrate that scaffolds enriched with bioactive payloads can be delivered precisely to an inflamed joint and achieve superior efficacy outcomes consistent with the pharmacological properties of these payloads. As a scaffold, we have used extracellular vesicles (EVs) prepared from human neutrophils (PMNs), which possess intrinsic anti-inflammatory properties and the ability to penetrate inflamed arthritic cartilage. EV fortified with anti-ROS-CII (EV/anti-ROS-CII) retained anti-ROS-CII specificity and bound exclusively to the damaged cartilage. Following systemic administration, EV/anti-ROS-CII (a) exhibited the ability to localize specifically in the arthritic joint in vivo and (b) was able to specifically target single (viral IL-10 or anti-TNF) or combined (viral IL-10 and anti-TNF) anti-inflammatory treatments to the arthritic joint, which accelerated attenuation of clinical and synovial inflammation. Overall, this study demonstrates the attainability of targeting a pro-resolving biological scaffold to the arthritic joint. The potential of targeting scaffolds such as EV, nanoparticles, or a combination thereof alongside combined therapeutics is paramount for designing systemically administered broad-spectrum of anti-inflammatory treatments.

A biological extract of turmeric (Curcuma longa) modulates response of cartilage explants to lipopolysaccharide.

BACKGROUND: Turmeric is commonly used as a dietary treatment for inflammation, but few studies have evaluated the direct effect of turmeric on cartilage. The purpose of this study was to characterize cartilage explants' inflammatory responses to lipopolysaccharide in the presence of a simulated biological extract of turmeric. METHODS: Turmeric was incubated in simulated gastric and intestinal fluid, followed by inclusion of liver microsomes and NADPH. The resulting extract (TURsim) was used to condition cartilage explants in the presence or absence of lipopolysaccharide. Explants were cultured for 96 h (h); the first 24 h in basal tissue culture media and the remaining 72 h in basal tissue culture media containing TURsim (0, 3, 9 or 15 µg/mL). Lipopolysaccharide (0 or 5 µg/mL) was added for the final 48 H. media samples were collected immediately prior to lipopolysaccharide exposure (0 h) and then at 24 and 48 h after, and analyzed for prostaglandin E2 (PGE2), glycosaminoglycan (GAG), and nitric oxide (NO). Explants were stained with calcein-AM for an estimate of live cells. Data were analyzed using a 2-way repeated measures (GAG, PGE2, NO) or 1-way ANOVA without repeated measures (viability). Significance accepted at p < 0.05. RESULTS: TURsim significantly reduced PGE2, NO and GAG, and calcein fluorescence was reduced. CONCLUSIONS: These data contribute to the growing body of evidence for the utility of turmeric as an intervention for cartilage inflammation.

The immune reaction and degradation fate of scaffold in cartilage/bone tissue engineering.

Tissue engineering with scaffolds provides novel prospects for bone/cartilage damage healing. Previous studies mainly focus on the development of physical/chemical property of scaffold and their efficiency on tissue regeneration. The biocompatibility and biodegradation of scaffold have been questioned with their rapidly increased application, since the ultimate clinical application requires biological safety and efficiency of biomaterials. After scaffolds are implanted in living organisms, excessive inflammatory response and foreign body reaction may compromise tissue healing outcomes, or eventually lead to the failure of regeneration. Further, scaffolds degradation and degraded derivatives may elicit immunogenic reaction, cause environmental change, influence encapsulated drug/growth factor release and cellular activity. Hence, the understanding of the degradation characteristics of various biomaterials is required as well. Non-invasive monitoring the fate of scaffolds inside the body needs to be explored for temporally and longitudinally optical observation. The review mainly aims to provide a retrospective summary and discussion of the biocompatibility, immune response and fate of scaffold in cartilage/bone tissue engineering. The continuing development of sophisticated biocompatible and biomimetic scaffolds will eventually lead to clinical application which can improve the quality of patients' care and life.

Anti-Inflammatory Effects of Novel Standardized Platelet Rich Plasma Releasates on Knee Osteoarthritic Chondrocytes and Cartilage in vitro.

BACKGROUND: Platelet Rich Plasma (PRP) has recently emerged as a potential treatment for osteoarthritis (OA), but composition heterogeneity hampers comparison among studies, with the result that definite conclusions on its efficacy have not been reached. OBJECTIVES: 1) To develop a novel methodology to prepare a series of standardized PRP releasates (PRP-Rs) with known absolute platelet concentrations, and 2) To evaluate the influence of this standardization parameter on the anti-inflammatory properties of these PRP-Rs in an in vitro and an ex vivo model of OA. METHODS: A series of PRPs was prepared using the absolute platelet concentration as the standardization parameter. Doses of platelets ranged from 0% (platelet poor plasma, PPP) to 1.5·105 platelets/µl. PRPs were then activated with CaCl2 to obtain releasates (PRP-R). Chondrocytes were stimulated with 10% of each PRP-R in serum-free culture medium for 72 h to assess proliferation and viability. Cells were co-stimulated with interleukin (IL)-1ß (5 ng/ml) and 10% of each PRP-R for 48 h to determine the effects on gene expression, secretion and intra-cellular content of common markers associated with inflammation, catabolism and oxidative stress in OA. OA cartilage explants were co-stimulated with IL-1ß (5 ng/ml) and 10% of either PRP-R with 0.75·105 platelets/µl or PRP-R with 1.5·105 platelets/µl for 21 days to assess matrix inflammatory degradation. RESULTS: Chondrocyte viability was not affected, and proliferation was dose-dependently increased. The gene expression of all pro-inflammatory mediators was significantly and dose-independently reduced, except for that of IL-1ß and IL-8. Immunoblotting corroborated this effect for inducible NO synthase (NOS2). Secreted matrix metalloproteinase-13 (MMP-13) was reduced to almost basal levels by the PRP-R from PPP. Increasing platelet dosage led to progressive loss to this anti-catabolic ability. Safranin O and toluidine blue stains supported the beneficial effect of low platelet dosage on cartilage matrix preservation. CONCLUSION: We have developed a methodology to prepare PRP releasates using the absolute platelet concentration as the standardization parameter. Using this approach, the composition of the resulting PRP derived product is independent of the donor initial basal platelet count, thereby allowing the evaluation of its effects objectively and reproducibly. In our OA models, PRP-Rs showed antiinflammatory, anti-oxidant and anti-catabolic properties. Platelet enrichment could favor chondrocyte proliferation but is not necessary for the above effects and could even be counter-productive.

Cartilage-binding antibodies induce pain through immune complex-mediated activation of neurons.

Rheumatoid arthritis-associated joint pain is frequently observed independent of disease activity, suggesting unidentified pain mechanisms. We demonstrate that antibodies binding to cartilage, specific for collagen type II (CII) or cartilage oligomeric matrix protein (COMP), elicit mechanical hypersensitivity in mice, uncoupled from visual, histological and molecular indications of inflammation. Cartilage antibody-induced pain-like behavior does not depend on complement activation or joint inflammation, but instead on tissue antigen recognition and local immune complex (IC) formation. smFISH and IHC suggest that neuronal Fcgr1 and Fcgr2b mRNA are transported to peripheral ends of primary afferents. CII-ICs directly activate cultured WT but not FcRγ chain-deficient DRG neurons. In line with this observation, CII-IC does not induce mechanical hypersensitivity in FcRγ chain-deficient mice. Furthermore, injection of CII antibodies does not generate pain-like behavior in FcRγ chain-deficient mice or mice lacking activating FcγRs in neurons. In summary, this study defines functional coupling between autoantibodies and pain transmission that may facilitate the development of new disease-relevant pain therapeutics.

Resveratrol inhibits Src tyrosine kinase, STAT3, and Wnt signaling pathway in collagen induced arthritis model.

Resveratrol, a phytochemical, acts several cellular signaling pathways and has anti-inflammatory potentials. The purpose of this study is to research the therapeutic effect of resveratrol in collagen-induced arthritis (CIA) model in rats and whether resveratrol affects the activities of signaling pathways those are potent pathogenic actors of rheumatoid arthritis. Arthritis was induced by intradermal injection of chicken type II collagen combined with incomplete Freund's adjuvant in Wistar albino rats. One day after the onset of arthritis (day 14), resveratrol (20 mg/kg/day) was given via oral gavage, until day 29. The paws of the rats were obtained for further analysis. Tissue Wnt5a, mitogen-activated protein kinase (MAPK), Src tyrosine kinase and signal transducer, and activator of transcription-3 (STAT3) mRNA expressions were determined by real-time polymerase chain reaction. Resveratrol ameliorated the clinical and histopathological (perisynovial inflammation and cartilage-bone destruction) findings of inflammatory arthritis. The tissue mRNA expressions of Wnt5a, MAPK3, Src kinase, and STAT3 were increased in the sham group compared to the control group. Resveratrol supplement decreased their expressions. The present study shows that Src kinase, STAT3, and Wnt signaling pathway are active in the CIA model. Resveratrol inhibits these signaling pathways and ameliorates inflammatory arthritis. © 2018 BioFactors, 45(1):69-74, 2019.

RNA-seq analysis reveals different gene ontologies and pathways in rheumatoid arthritis and Kashin-Beck disease.

AIMS: To understand the pathogenesis of cartilage damage in Kashin-Beck disease (KBD) and rheumatoid arthritis (RA) which similar clinical symptoms. METHODS: RNA sequencing (RAN-seq) analysis was used to reveal the different pathogeneses between KBD and RA. The messenger RNA expression profiles of articular cartilage isolated from KBD patients (n = 3) and RA patients (n = 3) were compared using RNA-seq analysis. Differentially expressed genes (DEGs) were determined using the Benjamini-Hochberg approach. The Database for Annotation, Visualization and Integrated Discovery (DAVID 6.7) was employed to assess functional categories and Gene Ontology (GO). The Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology Based Annotation System (KOBAS 2.0) was used to identify significantly enriched KEGG pathways. RESULTS: In the individually sequenced dataset, we identified 1568 significant DEGs in KBD compared to RA (232 up-regulated genes and 1336 down-regulated genes). GO function analysis identified nine significant biological processes (BPs), eight molecular functions (MFs), and five cell components (CCs) in KBD, and also the top ten ranked significant BPs, MFs and CCs were found in RA. The KEGG pathway enrichment analysis identified biosynthesis of amino acids involved in KBD. The chemokine signaling pathway, nuclear factor-kappa B signaling pathway, B cell receptor signaling pathway, leukocyte transendothelial migration, and osteoclast differentiation were involved in RA. CONCLUSIONS: RNA-seq revealed that proteoglycan-mediated metabolic disorders contributed to the onset of KBD, whereas immune dysregulation was apparently involved in the pathogenesis of RA.

Lactobacillus acidophilus ameliorates pain and cartilage degradation in experimental osteoarthritis.

Osteoarthritis (OA) is a chronic and degenerative disease that causes pain, cartilage deformation, and joint inflammation. Lactobacillus species have been used as dietary supplements to induce the production of antimicrobial and anti-inflammatory factors. The goal of this study was to determine whether Lactobacillus acidophilus ameliorates monosodium iodoacetate-induced OA. L. acidophilus showed anti-nociceptive properties and protected against cartilage destruction. It also downregulated the levels of proinflammatory cytokines and increased the levels of anti-inflammatory cytokines in the joints of OA rats. L. acidophilus additionally restored the balance between anabolic and catabolic factors in chondrocytes from OA patients. These results suggest that L. acidophilus can alleviate OA-associated pain and delay the progression of the disease by inhibiting proinflammatory cytokine production and reducing cartilage damage.

MiR-485-5p promotes the development of osteoarthritis by inhibiting cartilage differentiation in BMSCs.

OBJECTIVE: To investigate whether microRNA-485-5p (miR-485-5p) can participate in osteoarthritis by inhibiting chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and promoting the secretion of inflammatory factors. MATERIALS AND METHODS: BMSCs were obtained from mouse bone marrow samples and identified by flow cytometry. The expression of specific genes and miR-485-5p in the differentiation of BMSCs was detected by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). The influence of miR-485-5p on chondrogenic differentiation was subsequently evaluated by toluidine blue staining, detection of chondrogenic specific gene expression and inflammatory factors. After over-expressing SOX9, it was assessed whether miR-485-5p can affect the chondrogenic differentiation of BMSCs by inhibiting SOX9, so as to promote the secretion of inflammatory factors. RESULTS: The miR-485-5p level was negatively correlated with the degree of differentiation of BMSCs. After overexpression of microRNA-485-5p in BMSCs, the expression of cartilage surface marker genes and toluidine blue staining were reduced, while the expression of cartilage surface inflammation factors, including interleukin and tumor necrosis factor, was significantly enhanced. Meanwhile, opposite results were observed when miR-485-5p was inhibited. In addition, overexpression of SOX9 could restore the secretion of inflammatory cytokines induced by microRNA-485-5p. CONCLUSIONS: MiR-485-5p can decrease the level of SOX9, promote the production of inflammatory factors on the cartilage surface, and block the differentiation of mouse BMSCs into chondrocytes.

A Shared Epitope of Collagen Type XI and Type II Is Recognized by Pathogenic Antibodies in Mice and Humans with Arthritis.

Background: Collagen XI (CXI) is a heterotrimeric molecule with triple helical structure in which the α3(XI) chain is identical to the α1(II) chain of collagen II (CII), but with extensive posttranslational modifications. CXI molecules are intermingled in the cartilage collagen fibers, which are mainly composed of CII. One of the alpha chains in CXI is shared with CII and contains the immunodominant T cell epitope, but it is unclear whether there are shared B cell epitopes as the antibodies tend to recognize the triple helical structures. Methods: Mice expressing the susceptible immune response gene Aq were immunized with CII or CXI. Serum antibody responses were measured, monoclonal antibodies were isolated and analyzed for specificity to CII, CXI, and triple helical collagen peptides using bead-based multiplex immunoassays, enzyme-linked immunosorbent assays, and Western blots. Arthritogenicity of the antibodies was investigated by passive transfer experiments. Results: Immunization with CII or CXI leads to a strong T and B cell response, including a cross-reactive response to both collagen types. Immunization with CII leads to severe arthritis in mice, with a response toward CXI at the chronic stage, whereas CXI immunization induces very mild arthritis only. A series of monoclonal antibodies to CXI were isolated and of these, the L10D9 antibody bound to both CXI and CII equally strong, with a specific binding for the D3 epitope region of α3(XI) or α1(II) chain. The L10D9 antibody binds cartilage in vivo and induced severe arthritis. In contrast, the L5F3 antibody only showed weak binding and L7D8 antibody has no binding to cartilage and did not induce arthritis. The arthritogenic L10D9 antibody bound to an epitope shared with CII, the triple helical D3 epitope. Antibody levels to the shared D3 epitope were elevated in the sera from mice with arthritis as well as in rheumatoid arthritis. Conclusion: CXI is immunologically not exposed in healthy cartilage but contains T and B cell epitopes cross-reactive with CII, which could be activated in both mouse and human arthritis and could evoke an arthritogenic response.