TNF/TNFR signal transduction pathway-mediated anti-apoptosis and anti-inflammatory effects of sodium ferulate on IL-1β-induced rat osteoarthritis chondrocytes in vitro

Synergistic therapeutic effect of parecoxib and ilomastat combination in osteoarthritis via inhibition of IL-17/PI3K/AKT/NF-κB activity

BACKGROUND

Osteoarthritis is a degenerative disease, and current drug treatment is to give nonsteroidal anti-inflammatory drugs to relieve symptoms. The anti-inflammatory ability of parecoxib and ilomastat has been confirmed, but the synergistic effect of combined administration in osteoarthritis has not been clear.

METHODS

Mouse primary chondrocytes stimulated with IL-1β were cultured. The expression levels of inflammatory cytokines and matrix metalloproteinases were investigated by western blotting, quantitative real-time polymerase chain reaction and ELISA. The effects of parecoxib and ilomastat on chondrocyte apoptosis were evaluated by flow cytometry. In addition, the rat model of osteoarthritis was established by meniscal instability, and the morphological changes of cartilage and the expression levels of related molecules were monitored using Safranin O-Fast green and immunohistochemical staining after intra-articular injection of parecoxib, ilomastat, and the combination of the two.

RESULTS

In vitro experiments showed that the combined administration of parecoxib and ilomastat more effectively inhibited the expression of proinflammatory factors and matrix metalloproteinases compared with single drug administration. The combined drug treatment could more effectively inhibit IL-1β-induced chondrocyte apoptosis. The combined drug treatment alleviated the progression of osteoarthritis by inhibiting the IL-17/PI3K/AKT/NF-κB pathway. In addition, in vivo experiments showed that the combined administration could improve the further deterioration of the osteoarthritis rat model.

CONCLUSIONS

The combined administration of parecoxib and ilomastat to inhibit IL-17/PI3K/AKT/NF-κB transduction is beneficial to reduce the infiltration of inflammatory factors and matrix metalloproteinases in osteoarthritis.

Pathogen-induced apoptosis in echinoderms: A review

Echinoderms possess unique biological traits that make them valuable models in immunology, regeneration, and developmental biology studies. As a class rich in active substances with significant nutritional and medicinal value, echinoderms face threats from marine pathogens, including bacteria, viruses, fungi, protozoa, and parasites, which have caused substantial economic losses in echinoderm aquaculture. Echinoderms counteract pathogen invasion through innate immunity and programmed cell death, in particular, with apoptosis being essential for eliminating infected or damaged cells and maintaining homeostasis in many echinoderm cell types. Despite the importance of this process, there is a lack of comprehensive and updated reviews on this topic. This review underscores that echinoderm apoptotic pathways exhibit a complexity comparable to that of vertebrates, featuring proteins with unique domains that may indicate the presence of novel signaling mechanisms. We synthesize current knowledge on how echinoderms utilize diverse transcriptional and post-transcriptional mechanisms to regulate apoptosis in response to pathogen infections and explore how pathogens have evolved strategies to manipulate echinoderm apoptosis, either by inhibiting it to create survival niches or by inducing excessive apoptosis to weaken the host. By elucidating the primary apoptotic pathways in echinoderms and the host-pathogen interactions that modulate these pathways, this review aims to reveal new mechanisms of apoptosis in animal immune defense and provide insights into the evolutionary arms race between hosts and pathogens.

Casticin ameliorates osteoarthritic cartilage damage in rats through PI3K/AKT/HIF-1α signaling

Knee osteoarthritis (KOA) is a chronic, disabling knee joint lesion in which degeneration and defects in articular cartilage are the most important features. Casticin (CAS) is a flavonoid extracted from the Chinese herb Vitex species that has anti-inflammatory and antitumor effects. The aim of this study was to investigate the therapeutic and mechanistic effects of CAS on cartilage damage in KOA. A KOA rat model was established by anterior cruciate ligament transection (ACLT), and cartilage morphological changes were assessed by histological analysis and micro-CT scans. Subsequently, chondrocytes were treated with 10 ng/mL IL-1β to establish an OA model. CCK-8 assays and EdU assays were performed to assess the viability of CAS-treated chondrocytes. Western blotting, flow cytometry and Hoechst 33342/PI Double Stain were used to detect chondrocyte apoptosis. Western blotting, qRT‒PCR and ELISA were used to detect changes in inflammatory mediators. In addition, cartilage matrix-related indices were detected by Western blotting, qRT‒PCR and immunofluorescence (IF) analysis. Immunohistochemistry (IHC) and Western blotting were performed to detect the expression of p-PI3K, p-AKT and HIF-1α in vivo and in vitro. Micro-CT, pathological sections and related scores showed that CAS improved the alterations in bony structures and reduced cartilage damage and osteophyte formation in the ACLT model. In vivo, CAS attenuated IL-1β-induced cartilage matrix degradation, apoptosis and the inflammatory response. In addition, CAS inhibited the expression of the PI3K/AKT/HIF-1α signaling pathway in the ACLT animal model and IL-1β cell model. CAS may ameliorate cartilage damage in OA by inhibiting the PI3K/AKT/HIF-1α signaling pathway, suggesting that CAS is a potential strategy for the treatment of OA.

Fermented Lettuce Extract Induces Immune Responses through Polarization of Macrophages into the Pro-Inflammatory M1-Subtype

It has been reported that lettuce and its bioactive compounds enhance the host immune system by acting as immune modulators. This study aimed to identify the immunological effect of fermented lettuce extract (FLE) on macrophages. To evaluate the efficacy of FLE in enhancing macrophage function, we measured and compared the levels of macrophage activation-related markers in FLE- and lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Treatment with FLE activated RAW 264.7 macrophages, increased their phagocytic ability, and increased the production of nitric oxide (NO) and pro-inflammatory cytokine levels-similar to LPS. The effects of FLE on M1/M2 macrophage polarization were investigated by determining M1 and M2 macrophage transcript markers in mouse peritoneal macrophages. The FLE-related treatment of peritoneal macrophages enhanced the expression of M1 markers but reduced IL-4 treatment-induced M2 markers. After the generation of tumor-associated macrophages (TAMs), alterations in the levels of M1 and M2 macrophage markers were measured after treatment with FLE. The FLE-related treatment of TAMs increased the expression and production of pro-inflammatory cytokines and also led to the enhanced apoptosis of pancreatic cancer cells. These findings suggest that FLE may be useful for macrophage-targeted cancer therapy because of its ability to regulate the activation and polarization of macrophages in the tumor microenvironment.

Exploring active ingredients of anti-osteoarthritis in raw and wine-processed Dipsaci Radix based on spectrum-effect relationship combined with chemometrics

ETHNOPHARMACOLOGICAL RELEVANCE

Dipsaci Radix (DR) is the dry root of the Dipsacus asper Wall. ex DC., which has the function of tonifying the liver and kidney, continuing tendons and bones, and regulating blood vessels. However, there are few reports on the main active ingredients.

AIM OF THE STUDY

This study aimed to find the main active components of DR in the treatment of osteoarthritis (OA) by spectrum-effect relationship and compare the differences between RDR and WDR.

MATERIALS AND METHODS

Firstly, the high-performance liquid chromatography (HPLC) method was used to establish the fingerprint of DR, and 10 peaks of them were determined by UPLC-Q-TOF/MS. Then, the OA rat model was established by injecting sodium iodoacetate to study the effect of DR on OA. The spectrum-effect relationship was analyzed by grey relational analysis (GRA) and Pearson correlation analysis.

RESULTS

According to the pharmacological results, compared with the model group, the cartilage score, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), and Mankin score of rats in low, medium and high dose groups were decreased, and the therapeutic effect of wine-processed DR tended to be better than raw DR at the same dose. Finally, the active components of DR were preliminarily determined as 4 (loganic acid), 6 (chlorogenic acid), 8 (caffeic acid), 14 (dipsanoside B), 16, and 17 (asperosaponin VI) which had a large correlation in GRA and Pearson correlation analysis.

CONCLUSION

This study established the spectrum-effect relationship between the raw and wine-processed DR for the first time, which provided a theoretical basis for the study of the pharmacodynamic substance basis of DR before and after processing. This research provided a reference for the subsequent study of DR.

The role of apoptosis in the pathogenesis of osteoarthritis

PURPOSE

Apoptosis is an important physiological process, making a great difference to development and tissue homeostasis. Osteoarthritis (OA) is a chronic joint disease characterized by degeneration and destruction of articular cartilage and bone hyperplasia. This purpose of this study is to provide an updated review of the role of apoptosis in the pathogenesis of osteoarthritis.

METHODS

A comprehensive review of the literature on osteoarthritis and apoptosis was performed, which mainly focused on the regulatory factors and signaling pathways associated with chondrocyte apoptosis in osteoarthritis and other pathogenic mechanisms involved in chondrocyte apoptosis.

RESULTS

Inflammatory mediators such as reactive oxygen species (ROS), nitric oxide (NO), IL-1β, tumor necrosis factor-α (TNF-α), and Fas are closely related to chondrocyte apoptosis. NF-κB signaling pathway, Wnt signaling pathway, and Notch signaling pathway activate proteins and gene targets that promote or inhibit the progression of osteoarthritis disease, including chondrocyte apoptosis and ECM degradation. Long non-coding RNAs (LncRNAs) and microRNAs (microRNAs) have gradually replaced single and localized research methods and become the main research approaches. In addition, the relationship between cellular senescence, autophagy, and apoptosis was also briefly explained.

CONCLUSION

This review offers a better molecular delineation of apoptotic processes that may help in designing new therapeutic options for OA treatment.

Synthesis and biological evaluation of pyrazole-fused oleanolic acid derivatives as novel inhibitors of inflammatory and osteoclast differentiation

A series of pyrazole-fused oleanolic acid derivatives were designed and synthesized. The modification of these analogues focused on the substituents screening on the pyrazole ring. The cytotoxicity of these compounds and their anti-inflammatory activities via inhibiting interleukin-1β (IL-1β) production were evaluated in RAW264.7 cells. Most of the derivatives showed significantly improved potency compared with oleanolic acid. Among them, compound 7n exhibited the most potent anti-inflammatory activity on decreasing IL-1β production with low cytotoxicity. Moreover, the further study found 7n could inhibit RANKL-induced osteoclast differentiation on bone marrow-derived macrophages (BMMs). These findings may provide a potential direction for the drug development of osteoarthritis.

Molecular mechanisms of the Guizhi decoction on osteoarthritis based on an integrated network pharmacology and RNA sequencing approach with experimental validation

Background: Our aim was to determine the potential pharmacological mechanisms of the Guizhi decoction (GZD) in the treatment of osteoarthritis (OA) through an integrated approach of network pharmacological analyses, RNA sequencing (RNA-seq), and experimental validation. Methods: The quality control and identification of bioactive compounds of the GZD were carried out by using ultra-performance liquid chromatography (UPLC), and their OA-related genes were identified through overlapping traditional Chinese medicine systems pharmacology database (TCMSP), DrugBank and SEA Search Server databases, and GeneCards. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were implemented after constructing the component-target network. RNA-seq was used to screen differentially expressed genes (DEGs) under intervention conditions with and without the GZD in vitro. The crossover signaling pathways between RNA-seq and network pharmacology were then analyzed. Accordingly, protein-protein interaction (PPI) networks, GO, and KEGG analysis were performed using the Cytoscape, STRING, or DAVID database. The OA rat model was established to further verify the pharmacological effects in vivo. Hematoxylin-eosin (H&E) and safranin O/fast green (S-O) staining were used to grade the histopathological features of the cartilage. We verified the mRNA and protein expressions of the key targets related to the TNF signaling pathways in vivo and in vitro by qPCR, Western blotting (WB), and immunofluorescence assay. In addition, we also detected inflammatory cytokines in the rat serum by Luminex liquid suspension chip, which included tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). Results: Eighteen compounds and 373 targets of the GZD were identified. A total of 2,356 OA-related genes were obtained from the GeneCards database. A total of three hub active ingredients of quercetin, kaempferol, and beta-sitosterol were determined, while 166 target genes associated with OA were finally overlapped. The RNA-seq analysis revealed 1,426 DEGs. In the KEGG intersection between network pharmacology and RNA-seq analysis, the closest screening relevant to GZD treatment was the TNF signaling pathway, of which TNF, IL-6, and IL-1β were classified as hub genes. In consistent, H&E and S-O staining of the rat model showed that GZD could attenuate cartilage degradation. When compared with the OA group in vivo and in vitro, the mRNA levels of TNF-α, IL-1β, IL-6, matrix metalloproteinase 3 (MMP3), and matrix metalloproteinase 9 (MMP9) were all downregulated in the GZD group (all p < 0.05). The expression levels of anabolic proteins (Col2α1 and SOX9) were all higher in the GZD group than in the OA group (p < 0.05), while the expression levels of the catabolic proteins (MMP9 and COX-2) and TNF-α in the GZD group were significantly lower than those in the OA group (p < 0.05). In addition, the expression levels of TNF, IL-6, and IL-1β were upregulated in the OA group, while the GZD group prevented such aberrations (p < 0.01). Conclusion: The present study reveals that the mechanism of the GZD against OA may be related to the regulation of the TNF signaling pathway and inhibition of inflammatory response.

Carbon dots derived from folic acid attenuates osteoarthritis by protecting chondrocytes through NF-κB/MAPK pathway and reprogramming macrophages

Background

Osteoarthritis (OA) is a common joint disorder worldwide which causes great health and economic burden. However, there remains an unmet goal to develop an effective therapeutic method to prevent or delay OA. Chondrocytes, as the major cells involved in OA progression, may serve as a promising therapeutic target.

Results

A kind of carbon dots (CDs) with excellent biocompatibility was fabricated from folic acid via hydrothermal method and could effectively attenuate osteoarthritis. It was demonstrated that CDs treatment could rescue IL1β-induced proinflammatory responses, oxidative stress, cartilage degeneration and extracellular matrix degradation. Moreover, CDs reprogrammed lipopolysaccharide (LPS)-induced macrophage inflammation and polarization. Conditioned medium (CM) from CDs-treated macrophages could attenuate IL1β-induced chondrocyte injury. Also, CM from CDs-treated chondrocytes had immunoregulatory functions on macrophages. Mechanistically, CDs inhibited the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPK) signaling pathways in IL1β-stimulated chondrocytes. In vivo, anterior cruciate ligament transection (ACLT) mice model was adopted and it was indicated that intra-articular injection of CDs effectively delays OA pathogenesis.

Conclusions

Taken together, these findings indicated CDs could mediate OA via promoting cartilage repair and immunomodulating macrophages within local microenvironment, which may provide evidences for utilizing CDs as a novel nanomaterial for OA treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01681-6.

Underlying Mechanisms and Related Diseases Behind the Complex Regulatory Role of NOD-Like Receptor X1

Among nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), NOD-like receptor X1 (NLRX1) is the only known NLR family member that is targeted to the mitochondria, which contains a C-terminal leucine-rich repeat domain, a central conserved nucleotide-binding domain, and an unconventional N-terminal effector domain. It is unique due to several atypical features, such as mitochondrial localization, noninflammasome forming, and relatively undefined N-terminal domain. NLRX1 has multiple functions, including negative regulation of type-I interferon signaling, attenuation of proinflammatory nuclear factor kappa B (NF-κB) signaling, autophagy induction, modulation of reactive oxygen species production, cell death regulation, and participating in cellular senescence. In addition, due to its diverse functions, NLRX1 has been associated with various human diseases, including respiratory, circulatory, motor, urinary, nervous, and digestive systems, to name but a few. However, the exact regulatory mechanisms of NLRX1 are still unclear in many related diseases since conflicting and controversial topics on NLRX1 in the previous studies remain. In this review, we review recent research advances on the underlying mechanisms and related disorders behind the complex regulatory role of NLRX1, which may provide a promising target to prevent and/or treat the corresponding diseases.

The Role of TNF-α in the Pathogenesis of Temporomandibular Disorders

Temporomandibular disorder (TMD) is an oral dentofacial disease that is related to multiple factors such as disordered dental occlusion, emotional stress, and immune responses. In the past decades, tumor necrosis factor-alpha (TNF-α), a pleiotropic cytokine, has provided valuable insight into the pathogenesis of TMD, particularly in settings associated with inflammation. It is thought that TNF-α participates in the pathogenesis of TMD by triggering immune responses, deteriorating bone and cartilage, and mediating pain in the temporomandibular joint (TMJ). Initially, TNF-α plays the role of "master regulator" in the complex immune network by increasing or decreasing the production of other inflammatory cytokines. Then, the effects of TNF-α on cells, particularly on chondrocytes and synovial fibroblasts, result in pathologic cartilage degradation in TMD. Additionally, multiple downstream cytokines induced by TNF-α and neuropeptides can regulate central sensitization and inflammatory pain in TMD. Previous studies have also found some therapies target TMD by reducing the production of TNF-α or blocking TNF-α-induced pathways. All this evidence highlights the numerous associations between TNF-α and TMD; however, they are currently not fully understood and further investigations are still required for specific mechanisms and treatments targeting specific pathways. Therefore, in this review, we explored general mechanisms of TNF-α, with a focus on molecules in TNF-α-mediated pathways and their potential roles in TMD treatment. In view of the high clinical prevalence rate of TMD and damage to patients' QOL, this review provides adequate evidence for studying links between inflammation and TMD in further research and investigation.

Pulsed Electromagnetic Field Attenuates Osteoarthritis Progression in a Murine Destabilization-Induced Model through Inhibition of TNF-α and IL-6 Signaling

OBJECTIVE

To investigate the anti-inflammatory effects and mechanisms of pulsed electromagnetic field (PEMF) in the treatment of osteoarthritis (OA) in the destabilization of the medial meniscus (DMM) mice.

DESIGN

Ten-week-old male wild-type (WT), interleukin (IL)-6-/- and tumor necrosis factor (TNF)-α-/- mice undergoing DMM surgery were randomly divided into 2 groups (n = 10 each): mice with PEMF exposure and mice with sham PEMF exposure. PEMF (75 Hz, 3.8 mT, 1 h/day) or sham PEMF was applied for 4 weeks. Pain behavior of mice, histological assessment of cartilage and synovium, micro-CT (computed tomography) analysis of bone, real-time polymerase chain reaction, and immunohistochemical staining of cartilage were performed.

RESULTS

After DMM surgery, PEMF had a beneficial effect on pain, cartilage degeneration, synovitis, and trabecular bone microarchitecture in WT mice; these protective effects were reduced in IL-6-/- and TNF-α-/- mice. In addition, PEMF downregulated IL-6 and TNF-α expression in cartilage. PEMF also ameliorated cartilage matrix, chondrocyte apoptosis, and autophagy, while deletion of IL-6 or TNF-α suppressed the effects.

CONCLUSIONS

PEMF attenuates structural and functional progression of OA through inhibition of TNF-α and IL-6 signaling. The protective effects of PEMF on chondrocyte apoptosis and autophagy are regulated by TNF-α and IL-6 signaling.

COL3A1 and MMP9 Serve as Potential Diagnostic Biomarkers of Osteoarthritis and Are Associated With Immune Cell Infiltration

Background

Osteoarthritis (OA) is one of the most common age-related degenerative diseases. In recent years, some studies have shown that pathological changes in the synovial membrane occur earlier than those in the cartilage in OA. However, the molecular mechanism of synovitis in the pathological process of OA has not been elucidated. This study aimed to identify novel biomarkers associated with OA and to emphasize the role of immune cells in the pathogenesis of OA.

Methods

Microarray datasets were obtained from the Gene Expression Omnibus (GEO) and ArrayExpress databases and were then analyzed using R software. To determine differential immune cell subtype infiltration, the CIBERSORT deconvolution algorithm was used. Quantitative reverse transcription PCR (qRT-PCR) was used to determine the relative expressions of selected genes. Besides, Western blotting was used to assess the protein expression levels in osteoarthritic chondrocytes.

Results

After analyzing the database profiles, two potential biomarkers, collagen type 3 alpha 1 chain (COL3A1), and matrix metalloproteinase 9 (MMP9), associated with OA were discovered, which were confirmed by qRT-PCR and Western blotting. Specifically, the results revealed that, as the concentration of IL-1β increased, so did the gene and protein expression levels of COL3A1 and MMP9.

Conclusion

The findings provide valuable information and direction for future research into novel targets for OA immunotherapy and diagnosis and aids in the discovery of the underlying biological mechanisms of OA pathogenesis.

Quercetin Alleviates Osteoarthritis Progression in Rats by Suppressing Inflammation and Apoptosis via Inhibition of IRAK1/NLRP3 Signaling

Introduction

Quercetin was recently reported to help protect against osteoarthritis (OA) progression, but the molecular mechanism for that protective affect remains unclear.

Methods

Here, OA model rats were intraperitoneally injected with quercetin, and the severity of cartilage damage in the rats was evaluated by H&E, Safranin O, and Toluidine blue, as well as by using the Osteoarthritis Research Society International (OARSI) Scoring System. Additionally, rat chondrocytes were treated with quercetin and then stimulated with IL-1β. The levels of pro-inflammatory cytokines (IL-1β, IL-18, and TNF-α) were detected by ELISA.Cell apoptosis was evaluated by flow cytometry and Hoechst staining. ROS levels were measured using a DCFH-DA probe. Protein expression was evaluated by Western blotting, immunohistochemical staining, and immunofluorescence. 

Results

Our data showed that quercetin attenuated the degeneration and erosion of articular cartilage, suppressed inflammation and apoptosis, and downregulated the levels of IRAK1, NLRP3, and caspase-3 expression. In vitro data showed that overexpression of NLRP3 could reverse the suppressive effect of quercetin on IL-1β-induced rat chondrocyte injuries. Importantly, rescue experiments confirmed that quercetin inhibited IL-1β-induced rat chondrocyte injuries in vitro by suppressing the IRAK1/NLRP3 signaling pathway.

Conclusion

Our study indicated that quercetin inhibits IL-1β-induced inflammation and cartilage degradation by suppressing the IRAK1/NLRP3 signaling pathway.

MiR-24-3p attenuates IL-1β-induced chondrocyte injury associated with osteoarthritis by targeting BCL2L12

Background

MiR-24-3p has been reported to be involved in an osteoarthritis (OA)-resembling environment. However, the functional role and underlying mechanism of miR-24-3p in chondrocyte injury associated with OA remains unknown.

Methods

The expression of miR-24-3p was determined using reverse transcription quantitative PCR analysis in OA cases and control patients, as well as IL-1β-stimulated chondrocyte cell line CHON-001. The cell viability was analyzed by CCK-8 assay. Apoptosis status was assessed by caspase-3 activity detection. The pro-inflammatory cytokines (TNF-α and IL-18) were determined using ELISA assay. The association between miR-24-3p and B cell leukemia 2-like 12 (BCL2L12) was confirmed by luciferase reporter assay.

Results

We first observed that miR-24-3p expression level was lower in the OA cases than in the control patients and IL-1β decreased the expression of miR-24-3p in the chondrocyte CHON-001. Functionally, overexpression of miR-24-3p significantly attenuated IL-1β-induced chondrocyte injury, as reflected by increased cell viability, decreased caspase-3 activity, and pro-inflammatory cytokines (TNF-α and IL-18). Western blot analysis showed that overexpression of miR-24-3p weakened IL-1β-induced cartilage degradation, as reflected by reduction of MMP13 (Matrix Metalloproteinase-13) and ADAMTS5 (a disintegrin and metalloproteinase with thrombospondin motifs-5) protein expression, as well as markedly elevation of COL2A1 (collagen type II). Importantly, BCL2L12 was demonstrated to be a target of miR-24-3p. BCL2L12 knockdown imitated, while overexpression significantly abrogated the protective effects of miR-24-3p against IL-1β-induced chondrocyte injury.

Conclusions

In conclusion, our work provides important insight into targeting miR-24-3p/BCL2L12 axis in OA therapy.

Circular RNA circ_0128846 promotes the progression of osteoarthritis by regulating miR-127-5p/NAMPT axis

Background

Mounting evidence indicates that circular RNAs (circRNAs) participate in the occurrence and development of various diseases, including osteoarthritis (OA). However, the effects and molecular mechanism of circ_0128846 in OA have not been reported.

Methods

The expression levels of circ_0128846, microRNA-127-5p (miR-127-5p), and nicotinamide phosphoribosyltransferase (NAMPT) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell viability was determined by Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis was examined by flow cytometry and western blot assay. Inflammatory response and cartilage extracellular matrix (ECM) degradation were evaluated by western blot assay. The relationship between miR-127-5p and circ_0128846 or NAMPT was predicted by bioinformatics tools and verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays.

Results

Circ_0128846 and NAMPT were upregulated and miR-127-5p was downregulated in OA cartilage tissues. Knockdown of circ_0128846 increased cell viability and inhibited apoptosis, inflammation and ECM degradation in OA chondrocytes, while these effects were reversed by downregulating miR-127-5p. Moreover, circ_0128846 positively regulated NAMPT expression by sponging miR-127-5p. Furthermore, miR-127-5p promoted cell viability and suppressed apoptosis, inflammation, and ECM degradation in OA chondrocytes by directly targeting NAMPT.

Conclusion

Circ_0128846 knockdown might inhibit the progression of OA by upregulating miR-127-5p and downregulating NAMPT, offering a new insight into the potential application of circ_0128846 in OA treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02428-z.

Down-regulation of microRNA-203a suppresses IL-1β-induced inflammation and cartilage degradation in human chondrocytes through Smad3 signaling

Osteoarthritis (OA) is a chronic and prevalent degenerative musculoskeletal disorder, which is characterized by articular cartilage degradation and joint inflammation. MicroRNA-203a (miR-203a) has been shown to be involved in multiple pathological processes during OA, but little is known about its function in chondrocyte extracellular matrix (ECM) degradation. In the present study, we aimed to elucidate the effects of miR-203a on articular cartilage degradation and joint inflammation. We observed that the miR-203a level was significantly up-regulated in OA tissues and in an in vitro model of OA, respectively. Inhibition of miR-203a significantly alleviated the interleukin (IL)-1β-induced inflammatory response and ECM degradation in chondrocytes. Moreover, mothers against decapentaplegic homolog 3 (Smad3), a key factor in maintaining chondrocyte homeostasis, was identified as a putative target of miR-203a in chondrocytes. More importantly, inhibition of Smad3 impaired the inhibitory effects of the miR-203a on IL-1β-induced inflammatory response and ECM degradation. Collectively, these results demonstrated that miR-203a may contribute to articular cartilage degradation of OA by targeting Smad3, suggesting a novel therapeutic target for the treatment of OA.

CircSEC24A promotes IL-1β-induced apoptosis and inflammation in chondrocytes by regulating miR-142-5p/SOX5 axis

BACKGROUND

Osteoarthritis (OA) is a common joint disease. Currently, many studies have revealed that circular RNAs (circRNAs) are strongly related to the occurrence and development of diseases. Hence, we aimed to further elucidate the role and molecular mechanism of circRNA SEC24 homolog A, COPII coat complex component (circSEC24A) in OA.

METHODS

Chondrocytes were treated with interleukin-1β (IL-1β) to establish OA cell model in vitro. The expression levels of circSEC24A, microRNA-142-5p (miR-142-5p), and sex-determining region Y-box protein 5 (SOX5) were determined by quantitative real-time polymerase chain reaction. MTT and colony formation assays were used to determine cell proliferation. Cell apoptosis was detected by flow cytometry analysis. The protein levels of inflammatory factors and SOX5 were determined by western blot assay. The relationship between miR-142-5p and circSEC24A or SOX5 was confirmed using dual-luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

CircSEC24A and SOX5 expression were enhanced, while miR-142-5p level was reduced in OA cartilage tissues and chondrocytes. Overexpression of circSEC24A promoted IL-1β-induced injury through decreasing cell proliferation and increasing apoptosis and inflammation in chondrocytes. MiR-142-5p was a direct target of circSEC24A, and its upregulation ameliorated IL-1β-induced injury and abated the effect of oe-circSEC24A in IL-1β-induced chondrocytes. Additionally, SOX5 was a downstream target of miR-142-5p, and its overexpression had a similar role with oe-circSEC24A and reversed the impact of miR-142-5p in IL-1β-induced chondrocytes. CircSEC24A acted as a molecular sponge of miR-142-5p to regulate SOX5 expression in chondrocytes.

CONCLUSION

CircSEC24A aggravated IL-1β-induced injury via modulating miR-142-5p/SOX5 axis, providing possible targets for the clinical diagnosis and treatment of OA.

Influence of sodium ferulate on miR-133a and left ventricle remodeling in rats with myocardial infarction

To explore the influence of sodium ferulate (SF) on miR-133a and left ventricle remodeling (LVR) in rats with myocardial infarction (MI). The left coronary artery was ligated to create 36 ischemia-reperfusion (IR) rat models that were randomly divided into mock surgical group (MSG) (not ligated), model group (MG), and sodium ferulate group (SFG). After the successful modeling, SFG was intravenously injected with SF at the dose of 10 mg/kg, and the other two groups were injected with the same volume of normal saline. After 28 days, cardiac hemodynamic indices of all groups were measured; the myocardial infarction size (MIS), left ventricular mass index (LVMI), and collagen volume fraction (CVF) were calculated, the content of serum malondialdehyde (MDA) and activities of catalase (CAT), superoxide dismutase (SOD) and glutathione catalase (GSH-px) were detected by ELISA, and miR-133a expression in myocardial tissues of the left ventricle (LV) was detected by RT-qPCR. SF improved the cardiac hemodynamic indices of rat model and reduced the MIS, LVMI and CVF. SF decreased the serum MDA level and increased the serum CAT, SOD and GSH-px levels in rat model. SF increased the expression of miR-133a in myocardial tissue of rat model. Therefore, SF could effectively reduce the myocardial injury of IR rats and improve the LVR. Its mechanism may be related to the antioxygenation and upregulation of miR-133a.

MicroRNA-320c inhibits articular chondrocytes proliferation and induces apoptosis by targeting mitogen-activated protein kinase 1 (MAPK1)

AIM

To clarify the interaction of microRNA-320c (miR-320c) and mitogen-activated protein kinase 1 (MAPK1), and to investigate the effects of miR-320c on articular chondroctye proliferation and apoptosis.

METHODS

Lentiviral expression vectors were constructed and dual luciferase assays containing MAPK1 3'-untranslated regions (3'-UTRs) were performed. Small hairpin RNA (shRNA) was utilized to modulate MAPK1 expression. The messenger RNA and protein expression levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting respectively. Cell Counting Kit-8 and flow cytometry were conducted to detect the proliferation and apoptosis of Human Chondrocyte-articular (HC-a) cells. Besides that, the influences of miR-320c and MAPK1 on MAPK pathway activation were also evaluated.

RESULTS

Our data identified MAPK1 as a direct target gene of miR-320c, and miR-320c can negatively regulate MAPK1 expression by directly binding to MAPK1 3'-UTR in HC-a cells. Further functional study displayed that miR-320c overexpression and MAPK1 shRNA significantly suppressed the proliferation of HC-a cells and promoted cell apoptosis. Meanwhile, MAPK1 shRNA could attenuate miR-320c inhibitor promotive effects on HC-a cell proliferation and reverse its inhibitory effect on cell apoptosis. MAPK1 overexpression could rescue the inhibitory effect of miR-320c on HC-a cell proliferation, and weaken the accelerating effect of miR-320c on cell apoptosis. However, neither miR-320c or MAPK1 shRNA regulate the expression of c-JUN, JNK and c-Fos.

CONCLUSION

miR-320c inhibits articular chondrocyte proliferation and induces apoptosis by targeting MAPK1, suggesting that miR-320c perhaps participates in the pathogenesis of osteoarthritis and acts as a potential target for the therapeutic treatment of osteoarthritis.

Identification of Diagnostic Biomarkers of Osteoarthritis Based on Multi-Chip Integrated Analysis and Machine Learning

The pathogenesis of osteoarthritis (OA) is still unclear. It is therefore important to identify relevant diagnostic marker genes for OA. We performed an integrated analysis with multiple microarray data cohorts to identify potential transcriptome markers of OA development. Further, to identify OA diagnostic markers, we established gene regulatory networks based on the protein-protein interaction network involved in these differentially expressed genes (DEGs). Using support vector machine (SVM) pattern recognition, a diagnostic model for OA prediction and prevention was established. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that 190 DEGs were mainly enriched in pathways like the tumor necrosis factor signaling pathway, interleukin-17 signaling pathway, mitogen-activated protein kinase signaling pathway, nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway, and osteoclast differentiation. Eight hub genes (POSTN, MMP2, CTSG, ELANE, COL3A1, MPO, COL1A1, and COL1A2) were considered potential diagnostic biomarkers for OA, the area under curve (AUC) was >0.95, which showed high accuracy. The sensitivity and specificity of the SVM model of OA based on these eight genes reached 100% in multiple external verification cohorts. Our research provides a theoretical basis for OA diagnosis for clinicians.

PDLIM2 protects articular chondrocytes from lipopolysaccharide-induced apoptosis, degeneration and inflammatory injury through down-regulation of nuclear factor (NF)-κB signaling

Excessive inflammatory response-induced apoptosis and the degeneration of articular chondrocytes contribute to the development and progression of osteoarthritis. PDZ and LIM domain containing protein 2 (PDLIM2) has emerged as one of the pivotal regulators in orchestrating an inflammatory response through regulating the activity of transcription factor nuclear factor (NF)-κB. However, whether PDLIM2 participates in the articular chondrocyte-associated inflammatory response in osteoarthritis remains unknown. In the current study, we aimed to explore the biological function of PDLIM2 in lipopolysaccharide (LPS)-stimulated articular chondrocytes, an in vitro model of osteoarthritis. Herein, we found that PDLIM2 expression was significantly down-regulated in chondrocytes in response to LPS exposure. Functional experiments revealed that PDLIM2 overexpression increased the viability and decreased the apoptosis of chondrocytes following LPS treatment. Moreover, PDLIM2 overexpression attenuated LPS-induced degeneration of chondrocytes via the down-regulation of matrix metalloproteinase (MMP)-3 and MMP-13 and the up-regulation of COL2A1 and ACAN. In addition, the overexpression of PDLIM2 decreased LPS-induced production of interleukin (IL)-1β, IL-6 and TNF-α. In contrast, depletion of PDLIM2 exhibited the opposite effect. Mechanism research elucidated that PDLIM2 repressed the activation of NF-κB signaling associated with the down-regulation of NF-κB p65 protein expression. PDLIM2 depletion-exacerbated LPS-induced injury was significantly reversed by NF-κB inhibition. Taken together, these results demonstrate that PDLIM2 overexpression attenuates LPS-induced injury of articular chondrocytes through the inactivation of NF-κB signaling.

Novel glucosamine-loaded thermosensitive hydrogels based on poloxamers for osteoarthritis therapy by intra-articular injection

Glucosamine (GlcN) is a common drug used to treat osteoarthritis (OA). To prolong the action time of glucosamine on OA and improve its therapeutic effect, this research explored the potential application of GlcN-loaded thermosensitive hydrogels based on poloxamer 407 and poloxamer 188 for OA therapy by intra-articular injection. The thermosensitive hydrogels were prepared by cold method, and the effects of P407, P188, and GlcN on sol-gel transition temperature (T_sol-gel) were compared. After screening was performed, the optimized formulation showed good temperature sensitivity, and T_sol-gel was approximately 35 °C. In vitro release tests showed that GlcN was slowly released from the thermosensitive hydrogels. After the gels were intra-articularly administered to treat OA in rabbits, the degree of swelling and inflammatory factors were significantly decreased in the hydrogel group compared with those in the OA model group (P < 0.05). Histological results showed that the GlcN-administered group had a good repair effect on damaged cartilage. At the same dose, the effect of the thermosensitive hydrogels was better than that of the aqueous solution. Therefore, GlcN-loaded thermosensitive hydrogels based on poloxamers are promising sustainable delivery systems for OA therapy by intra-articular injection.

The Fibroblast-Like Synoviocyte Derived Exosomal Long Non-coding RNA H19 Alleviates Osteoarthritis Progression Through the miR-106b-5p/TIMP2 Axis

Osteoarthritis (OA) is a common degenerative joint disease that affects people worldwide. The interaction between fibroblast-like synoviocytes (FLSs) and chondrocytes may play a vital role in OA disease pathology. However, the underlying mechanisms by which FLSs exert regulatory effects on chondrocytes still need to be elucidated. Exosomes, small membrane vesicles secreted from living cells, are known to play a variety of roles in mediating cell-to-cell communication through the transferring of biological components such as non-coding RNAs and proteins. Here, we investigate the cellular processes of chondrocytes regulated by FLS-derived exosomes and the mechanisms of action underlying the functions of exosomes in OA pathogenesis. We observed that exosome-mediated cartilage repair was characterized by increased cell viability and migration as well as alleviated matrix degradation. Using chondrocyte cultures, the enhanced cellular proliferation and migration during exosome-mediated cartilage repair was linked to the exosomal lncRNA H19-mediated regulation of the miR-106b-5p/TIMP2 axis. Transfection of miR-106-5p mimics in chondrocytes significantly decreased cell proliferation and migration, promoted matrix degradation characterized by elevated MMP13 and ADAMTS5 expression, and reduced the expression of COL2A1 and ACAN in chondrocytes. Furthermore, we found that TIMP2 was directly regulated by miR-106-5p. Co-transfections of miR-106-5p mimics and TIMP2 resulted in higher levels of COL2A1 and ACAN, but lower levels of MMP13 and ADAMTS5. Together, these observations demonstrated that the lncRNA H19 may promote chondrocyte proliferation and migration and inhibit matrix degradation in OA possibly by targeting the miR-106b-5p/TIMP2 axis. In the future, H19 may serve as a potential therapeutic target for the treatment of OA.

Promoted Viability and Differentiated Phenotype of Cultured Chondrocytes With Low Level Laser Irradiation Potentiate Efficacious Cells for Therapeutics

Effective clinical treatments of cartilage lesions in affected joints require large numbers of viable chondrogenic cells generated through in vivo stimulation or ex vivo expansion of chondrocytes isolated from small biopsy specimens. Conventional passaging of chondrocytes in culture provides sufficient cells for treatments but these cells usually lose their differentiated phenotype. This leads to the formation of fibrocartilaginous tissue due to a malfunctioning repair process. Biostimulation of passaging chondrocytes with low level laser irradiation (LLLI) may theoretically produce more functional chondrocytes for cell-based repair of cartilage defects. Molecular and cellular analyses, cytochemistry, cell cultivation, and microscopy showed that LLLI treatments were found to (1) increase chondrocyte viability, (2) promote secretion of matrix proteins, (3) upregulate expression of chondrogenic genes, and (4) downregulate gene expression of cell destructive proteases and genes coding for mediators involved in the extrinsic apoptosis signaling pathway. Furthermore, LLLI attenuated induction of genes associated with cell death and matrix breakdown induced by IL-1β, some of which was seen at the protein level, with verification of effects on gene expression in the C28/I2 human chondrocyte line. LLLI treatments during culture generated larger numbers of viable chondrocytes compared to untreated cultures. Moreover, LLLI-treated chondrocytes in culture also rectified and simultaneously maintained their differentiated phenotype. Cultured chondrocytes treated with LLLI are a promising cell source for repairing cartilage lesions in vivo and restoration of articular function using tissue engineering strategies.

miR-149-5p mitigates tumor necrosis factor-α-induced chondrocyte apoptosis by inhibiting TRADD

Introduction

Chondrocyte apoptosis as a prominent characteristic is usually accompanied by cartilage degeneration in osteoarthritis (OA). Herein, we aimed to determine the roles of miR-149-5p in tumor necrosis factor-α (TNF-α)-induced chondrocyte apoptosis.

Material and methods

Human chondrocytes were cultured with TNF-α to establish an apoptosis cell model in vitro. After transfection with miR-149-5p mimics or co-expression with TRADD in chondrocytes, cell viability, apoptosis, inflammatory cytokines, mRNA and protein expression were measured using CCK8, Annexin V-FITC double staining, ELISA assays, RT-qPCR and western blotting, respectively.

Results

TNF-α-induced chondrocyte apoptosis occurred in association with the inhibition of cell proliferation, the elevation of inflammatory cytokine levels and the activation of TRADD and caspase-3/8 signaling. The post-transcriptional regulatory mechanism suggested that TRADD was a direct target of miR-149-5p, and overexpression of miR-149-5p resulted in the down-regulation of TRADD protein expression in chondrocytes. In addition, miR-149-5p mimics had the ability to attenuate TNF-α-induced inflammation and apoptosis, while transfection with TRADD vector neutralized the protective effects of miR-149-5p on TNF-α-induced chondrocyte dysfunction.

Conclusions

miR-149-5p inversely regulated TNF-α-mediated chondrocyte damage by inhibiting TRADD-modulated caspases signaling. The miR-149-5p/TRADD signaling pathway might be a promising therapeutic target for the treatment of OA.

The transcriptional coactivator YAP1 is overexpressed in osteoarthritis and promotes its progression by interacting with Beclin-1

Osteoarthritis (OA) constitutes the most common disease of degenerative joints, with chondrocytes playing an important role in disease progression. However, the underlying pathobiological mechanisms have not been fully characterized. In this study, we investigated the role of Yes-associated protein 1 (YAP1)-regulated autophagy in chondrocyte proliferation, apoptosis, and differentiation. The data showed that YAP1, a transcriptional coactivator, was overexpressed in OA tissues from a murine model of OA, as analyzed by real time PCR and western blot. Overexpression of YAP1 significantly suppressed ATDC5 chondrogenic cell proliferation and decreased the expression of differentiation-related genes including Runx2, osteocalcin, and collagen I, and elevated cell apoptosis, whereas these cellular processes were reversed by knockdown of YAP1. Immunofluorescence analysis demonstrated that YAP1 co-localized with the autophagy regulator beclin1. Co-immunoprecipitation experiments indicated that this interaction was enhanced in OA tissues. In contrast, YAP1 lacking the internal WW domains failed to interact with beclin1 and was unable to inhibit beclin1 ubiquitination. This resulted in upregulated autophagy, which significantly improved OA by increasing chondrocyte proliferation and differentiation. Notably, YAP1 expression was significantly downregulated by various anti-OA drugs. Finally, the Yap1 promoter was activated by transcriptional factors AP2α and SP1, whereas its 3'UTR was targeted by miR-5624-5p, miR-33-3p, and miR-6918-5p. In conclusion, inhibition of YAP1 could facilitate beclin1-regulated autophagy in OA, suggesting a potential therapeutic approach to combat OA.

Lipopolysaccharide-induced expression of astrocyte elevated gene-1 promotes degeneration and inflammation of chondrocytes via activation of nuclear factor-κB signaling

Osteoarthritis is an inflammatory disease characterized by joint degeneration and inflammation. Astrocyte elevated gene-1 (AEG-1) has been suggested as a novel inflammation-related factor in the pathological processes of various inflammatory diseases. To date, little is known about the role of AEG-1 in osteoarthritis. The aim of the present study was to explore the potential role of AEG-1 in the regulation of lipopolysaccharide-induced apoptosis and inflammation of chondrocytes. The results showed that AEG-1 expression was significantly upregulated in chondrocytes following exposure to lipopolysaccharide. Knockdown of AEG-1 increased the survival and decreased the expression of matrix metalloproteinases in chondrocytes treated with lipopolysaccharide. Moreover, silencing of AEG-1 restricted the lipopolysaccharide-induced production of proinflammatory cytokines. In contrast, AEG-1 overexpression caused opposite effects. Notably, we found that AEG-1 inhibition blocked the lipopolysaccharide-induced activation of nuclear factor-κB signaling through impeding the nuclear translocation of nuclear factor-κB p65 subunit. Additionally, inhibition of nuclear factor-κB partially reversed the AEG-1-mediated promotion of lipopolysaccharide-induced inflammatory injury in chondrocytes. In conclusion, our results demonstrate that inhibition of AEG-1 expression attenuates lipopolysaccharide-induced degeneration and inflammation of chondrocytes through suppressing the activation of nuclear factor-κB signaling. This work therefore highlights a potential role of AEG-1 in the pathogenesis of osteoarthritis, and indicates its potential as a therapeutic target.

NLRX1 alleviates lipopolysaccharide-induced apoptosis and inflammation in chondrocytes by suppressing the activation of NF-κB signaling

Osteoarthritis (OA) is a chronic debilitating disease characterized by joint degeneration. Excessive chondrocyte apoptosis and inflammation contributes to articular cartilage destruction in OA pathology. Nucleotide-binding oligomerization domain (NOD)-like receptor X1 (NLRX1) has emerged as a critical regulator of inflammation that participates in the pathology of diverse diseases. To date, little is known about the role of NLRX1 in OA. In the present study, we aimed to explore the function of NLRX1 in lipopolysaccharide (LPS)-induced injury in chondrocytes, an in vitro model of OA. NLRX1 mRNA was detected by quantitative polymerase chain reaction (qPCR) analysis. Protein expression of NLRX1, phosphorylated IκB kinase β (IKKβ), and phosphorylated nuclear factor-κB (NF-κB) p65 were examined by western blot. Cell viability was assessed by the MTT assay. Cell apoptosis was evaluated by measuring caspase-3 activity. Cytokine release was assessed by enzyme-linked immunosorbent assay (ELISA). NF-κB signaling activation was analyzed with a luciferase reporter assay. Herein, our results revealed that NLRX1 expression was markedly decreased in LPS-treated chondrocytes. Functional experiments demonstrated that NLRX1 overexpression significantly improved cell viability and attenuated LPS-treated chondrocyte apoptosis and inflammation, while NLRX1 silencing caused the opposite effects. Moreover, our results showed that NLRX1 regulated LPS-induced NF-κB signaling activation. Notably, NF-κB signaling inhibition significantly reversed the NLRX1-knockdown-mediated enhanced effects on LPS-induced apoptosis and inflammation. Overall, these results demonstrate that NLRX1 alleviates LPS-induced apoptosis and inflammation in chondrocytes by negatively regulating NF-κB signaling, results that indicate an anti-inflammatory role for NLRX1 in OA. Our findings suggest that NLRX1 may serve as a potential therapeutic target for OA.

Spectrum-Effect Relationships between High-Performance Liquid Chromatography (HPLC) Fingerprints and the Antioxidant and Anti-Inflammatory Activities of Collagen Peptides

A total of 13 batches of collagen peptide samples were extracted, isolated, and purified from chicken sternal cartilage under various process parameters. The fingerprint profiles of 13 batches of collagen peptides were established by high-performance liquid chromatography (HPLC). In addition, the amino acid profiles and molecular weight distributions of collagen peptides were investigated. The in vitro antioxidant activities of the peptide samples were measured using the 2,2'-Azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the ferric-reducing antioxidant power (FRAP) assay and an assay of the oxidative damage induced by hydrogen peroxide (H₂O₂) in the degenerative cartilage cells from the knee joint of rat C518 (C518 cell line). The anti-inflammatory activities of the peptide samples were assessed by measuring the inflammatory responses induced by lipopolysaccharides (LPSes) in C518 cells. Subsequently, the spectrum-effect relationships between HPLC fingerprints and the antioxidant and anti-inflammatory activities of collagen peptides were investigated using grey relational analysis (GRA). Fifteen common peaks were obtained from the HPLC fingerprints of collagen peptides. Each collagen peptide sample had a characteristic set of amino acid types and contents. All of the hydrolysates of the collagen peptides were primarily composed of fractions II (500⁻1000 Da) and III (1000⁻3000 Da). Collagen peptides exhibited good scavenging activity on ABTS radical, DPPH radical, and ferric-reducing antioxidant power. Collagen peptides were also effective against H₂O₂-induced cellular oxidative damage in C518 cells. The antioxidant activity of collagen peptides was due to the low molecular weight and the presence of antioxidant and hydrophobic amino acid residues within its sequence. Collagen peptides significantly inhibited the secretion of inflammatory cytokines IL-1β, TNF-α, and PGE2 in C518 cells. The anti-inflammatory activity of collagen peptides may include increased synthesis of the key components of extracellular matrix (ECM) and inhibited apoptosis of chondrocytes. The GRA results showed that peaks 2, 3, and 8 were the main components contributing to the antioxidant activity of the collagen peptides, whereas peaks 11 and 14 were the main components contributing to the anti-inflammatory activity of the collagen peptides. The components of peaks 8 and 14 were identified as GPRGPPGPVGP and VAIQAVLSLYASGR by UPLC-MS/MS. Those identified collagen peptides offer a potential therapeutic strategy for the treatment of osteoarthritis (OA) due to their antioxidative stress and due to them disturbing the catabolism and anabolism processes in arthrodial cartilage.

[Application of Lectin from Catfish Eggs to Cancer Therapy: A Fundamental Study]

Silurus asotus egg lectin (SAL) is an α-galactoside-binding protein, isolated from the egg of catfish. It belongs to the rhamnose-binding lectin family that binds to Gb3 glycan (Galα1-4Galβ1-4Glc). SAL has resulted in the induction of early apoptosis in the Raji cell line, which is a Burkitt's lymphoma cell line expressing Gb3. The apoptosis was characterized by i) increased externalization of phosphatidylserin via multidrug resistance 1 P-glycoprotein (MDR1 P-gp), and ii) reduced cell size through the activation of voltage-gated potassium channel Kv1.3. Although the incorporation of propidium iodide (PI) was observed, SAL did not cause apoptosis in Raji cells. This event may be due to an increased expression of membrane-anchored tumor necrosis factor α (TNFα) and TNF receptor 1 (TNFR1) after the binding of SAL to Gb3. Moreover, SAL arrested the cell cycle at the G_0/1 phase, thus inhibiting cell proliferation. The suppression of cell proliferation by SAL was likely due to the enhanced expression of p21 caused by the phosphorylation of ERK_1/2 through the Ras-MEK-ERK_1/2 pathway. Combination of SAL with anti-cancer drugs was also examined in this study. Interestingly, SAL increased the incorporation of doxorubicin (Dox) into Raji cells, consequently enhancing its cytotoxic effect. Similarly, the cytotoxic effects of vinblastine and irinotecan were also significantly increased in Raji cells treated with SAL. These studies demonstrate that SAL may be applied to cancer therapy.

Sodium Ferulate Attenuates Lidocaine-Induced Corneal Endothelial Impairment

The introduction of intracameral anaesthesia by injection of lidocaine has become popular in cataract surgery for its inherent potency, rapid onset, tissue penetration, and efficiency. However, intracameral lidocaine causes corneal thickening, opacification, and corneal endothelial cell loss. Herein, we investigated the effects of lidocaine combined with sodium ferulate, an antioxidant with antiapoptotic and anti-inflammatory properties, on lidocaine-induced damage of corneal endothelia with in vitro experiment of morphological changes and cell viability of cultured human corneal endothelial cells and in vivo investigation of corneal endothelial cell density and central corneal thickness of cat eyes. Our finding indicates that sodium ferulate from 25 to 200 mg/L significantly reduced 2 g/L lidocaine-induced toxicity to human corneal endothelial cells, and 50 mg/L sodium ferulate recovered the damaged human corneal endothelial cells to normal growth status. Furthermore, 100 mg/L sodium ferulate significantly inhibited lidocaine-induced corneal endothelial cell loss and corneal thickening in cat eyes. In conclusion, sodium ferulate protects human corneal endothelial cells from lidocaine-induced cytotoxicity and attenuates corneal endothelial cell loss and central corneal thickening of cat eyes after intracameral injection with lidocaine. It is likely that the antioxidant effect of sodium ferulate reduces the cytotoxic and inflammatory corneal reaction during intracameral anaesthesia.

Up-regulation of TRAF2 inhibits chondrocytes apoptosis in lumbar facet joint osteoarthritis

Tumor necrosis factor receptor-associated factor 2 (TRAF2) has been demonstrated that it plays a significant role in cell death receptor signal transduction. The purpose of this study was to investigate the expression of TRAF2 and its possible role in FJOA. We observed an up-regulation of TRAF2 in FJOA by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) compared to normal tissues. In vitro, we used TNF-α to stimulate Human SW1353 chondrosarcoma cells to establish the chondrocytes injury model. Western blot analysis revealed significant expression of TRAF2 and cleaved caspase-3/8 in SW1353 cells. Co-localization of TRAF2/cleaved caspase-3/8 was detected in the cells injury model by double-labeling immunofluorescent staining. We demonstrated a possible anti-apoptotic effect of TRAF2 in chondrocyte apoptosis in FJOA by knockdown of its expression with siRNA. Moreover, TRAF2 knockdown was demonstrated to enhance TNF-α-induced apoptosis by flow cytometry assay. In conclusion, our results show that the up-regulation of TRAF2 may play an important role in the inhibition of chondrocyte apoptosis of FJOA.

Ferulic acid may target MyD88-mediated pro-inflammatory signaling - Implications for the health protection afforded by whole grains, anthocyanins, and coffee

Higher dietary intakes of anthocyanins have been linked epidemiologically to decreased risk for metabolic syndrome, type 2 diabetes and cardiovascular events; clinical trials and rodent studies evaluating ingestion of anthocyanin-rich extracts confirm favorable effects of these agents on endothelial function and metabolic syndrome. However, these benefits of anthocyanins are lost in rats whose gut microbiome has been eliminated with antibiotic treatment - pointing to bacterial metabolites of anthocyanins as the likely protective agents. A human pharmacokinetic assessment of orally administered cyanidin-3-O-glucoside, a prominent anthocyanin, has revealed that, whereas this compound is minimally absorbed, ferulic acid (FA) is one of its primary metabolites that appears in plasma. FA is a strong antioxidant and phase 2 inducer that has exerted marked anti-inflammatory effects in a number of rodent and cell culture studies; in particular, FA is highly protective in rodent models of diet-induced weight gain and metabolic syndrome. FA, a precursor for lignan synthesis, is widely distributed in plant-based whole foods, mostly in conjugated form; whole grains are a notable source. Coffee ingestion boosts plasma FA owing to gastrointestinal metabolism of chlorogenic acid. Hence, it is reasonable to suspect that FA mediates some of the broad health benefits that have been associated epidemiologically with frequent consumption of whole grains, anthocyanins, coffee, and unrefined plant-based foods. The molecular basis of the anti-inflammatory effects of FA may have been clarified by a recent study demonstrating that FA can target the adaptor protein MyD88; this plays an essential role in pro-inflammatory signaling by most toll-like receptors and interleukin-1β. If feasible oral intakes of FA can indeed down-regulate MyD88-dependent signaling, favorable effects of FA on neurodegeneration, hypothalamic inflammation, weight gain, adipocyte and beta cell function, adiponectin secretion, vascular health, and cartilage and bone integrity can be predicted. Since FA is well tolerated, safe, and natural, it may have great potential as a protective nutraceutical, and clinical trials evaluating its effects are needed.

TNF‑α increases inflammatory factor expression in synovial fibroblasts through the toll‑like receptor‑3‑mediated ERK/AKT signaling pathway in a mouse model of rheumatoid arthritis

Osteoarthritis is a type of joint disease that may lead to other joint diseases. Previous research has demonstrated that tumor necrosis factor (TNF)‑α is associated with osteoarthritis activity and pathology. The possible mechanisms of the TNF‑α‑mediated signaling pathway have not been clearly elaborated in synovial fibroblasts. The present study aimed to investigate the potential mechanisms of TNF‑α in a mouse model of iodoacetate‑induced osteoarthritis. Reverse transcription‑quantitative polymerase chain reaction, ELISA, western blotting and immunohistochemistry were performed to evaluate the role of TNF‑α in the progression of osteoarthritis. The results revealed that the serum levels of TNF‑α, interleukin (IL)‑1β, IL‑4 and IL‑6 were significantly upregulated in a mouse model of iodoacetate‑induced osteoarthritis compared with healthy mice (P<0.01). TNF‑α, IL‑1β, IL‑4 and IL‑6 mRNA and protein levels were also significantly upregulated in synovial fibroblasts in the experimental mice (P<0.01). It was demonstrated that TNF‑α increased pro‑inflammation factors matrix metalloproteinase (MMP)‑3, MMP‑9, nuclear factor (NF)‑κB and receptor activator of NF‑κB ligand (RANKL) in synovial fibroblasts. It was also observed that the toll‑like receptor (TLR)‑3 was significantly upregulated and extracellular signal‑regulated kinase (ERK) and protein kinase B (AKT) were significantly downregulated in synovial fibroblasts in osteoarthritis mice (P<0.01). An in vitro assay demonstrated that TNF‑α inhibitor decreased mRNA and protein levels of IL‑1β, IL‑4 and IL‑6 in synovial fibroblasts. The knockdown of TLR‑3 abolished the TNF‑α upregulated mRNA and protein levels of IL‑1β, IL‑4 and IL‑6 in synovial fibroblasts. In addition, the knockdown of TLR‑3 also reversed TNF‑α‑upregulated ERK and AKT expression in synovial fibroblasts. In vivo assays demonstrated that TNF‑α inhibitor significantly decreased the deposition of IL‑1β, IL‑4 and IL‑6 as well as bone destruction and significantly increased the body weight and osteoarthritis score for osteoarthritic mice (P<0.01). TNF‑α inhibitor decreased TLR‑3 and significantly increased the expression and phosphorylation of ERK and AKT in articular cartilage (P<0.01). In conclusion the results of the present study indicate that TNF‑α serves an essential role in synovial fibroblasts in osteoarthritis, suggesting that inhibition of TNF‑α may decrease inflammation via the TLR‑3‑mediated ERK/AKT signaling pathway in a mouse model of monosodium iodoacetate‑induced osteoarthritis.

Anti-Inflammatory Effect of Geniposide on Osteoarthritis by Suppressing the Activation of p38 MAPK Signaling Pathway

It has been suggested that the activation of the p38 mitogen activated protein kinases (MAPKs) signaling pathway plays a significant role in the progression of OA by leading to the overexpression of proinflammatory cytokines, chemokines, and signaling enzymes in human osteoarthritis chondrocytes. However, most p38 MAPK inhibitors applied for OA have been thought to be limited due to their potential long-term toxicities. Geniposide (GE), an iridoid glycoside purified from the fruit of the herb, has been widely used in traditional medicine for the treatment of a variety of chronic inflammatory diseases. In this study, we evaluated the inhibition effect of geniposide on the inflammatory progression of the surgically induced osteoarthritis and whether the protective effect of geniposide on OA is related to the inhibition of the p38 MAPK signaling pathway. In vitro, geniposide attenuated the expression of inflammatory cytokines including interleukin-1 (IL-1), tumor necrosis factor (TNF-α), and nitric oxide (NO) production as well as matrix metalloproteinase- (MMP-) 13 in chondrocytes isolated from surgically induced rabbit osteoarthritis model. Additionally, geniposide markedly suppressed the expression of IL-1, TNF-α, NO, and MMP-13 in the synovial fluid from the rabbits with osteoarthritis. More importantly, our results clearly demonstrated that the inhibitory effect of geniposide on surgery-induced expression of inflammatory mediators in osteoarthritis was closely associated with the suppression of the p38 MAPK signaling pathways. Our study demonstrates that geniposide may have therapeutic potential to serve as an alternative agent for the p38 MAPK inhibition for the treatment of OA due to its inherent features of biological activities and low toxicity as a traditional Chinese medicine.

Downregulation of microRNA-448 inhibits IL-1β-induced cartilage degradation in human chondrocytes via upregulation of matrilin-3

Background

Osteoarthritis is characterized by the continuous degradation of the articular cartilage. The microRNA miR-448 has been found to be broadly involved in cellular processes, including proliferation, apoptosis, invasion and EMT. While aberrant expression of miR-448 has been found in multiple cancers, its level in osteoarthritis cartilage and its role in the progression of this disease are still unknown. Here, we examined the functional roles of miR-448 and its expression in osteoarthritis tissues, including IL-1β-stimulated osteoarthritis chondrocytes.

Methods

Chondrocytes were isolated from human articular cartilage and stimulated with IL-1β. The expression levels of miR-448 in the cartilage and chondrocytes were both determined. After transfection with an miR-448 mimic or inhibitor, the mRNA levels of aggrecan, type II collagen and MMP-13 were determined. Luciferase reporter assay, qRT-PCR and western blot were performed to explore whether matrilin-3 was a target of miR-448. Furthermore, we co-transfected chondrocytes with miR-448 inhibitor and siRNA for matrilin-3 and then stimulated them with IL-1β to determine whether miR-448-mediated IL-1β-induced cartilage matrix degradation resulted from directly targeting matrilin-3.

Results

The level of miR-448 was significantly higher and matrilin-3 expression was significantly lower in osteoarthritis cartilage and IL-1β-induced chondrocytes than in normal tissues and cells. Furthermore, matrilin-3 expression was reduced by miR-448 overexpression. MiR-448 downregulation significantly alleviated the IL-1β-induced downregulation of aggrecan and type II collagen expression, and upregulation of MMP-13 expression. MiR-448 overexpression had the opposite effects. Knockdown of matrilin-3 reversed the effects of the miR-448 inhibitor on the expressions of aggrecan, type II collagen and MMP-13.

Conclusion

The findings showed that miR-448 contributed to the progression of osteoarthritis by directly targeting matrilin-3. This indicates that it has potential as a therapeutic target for the treatment of osteoarthritis.

Regulation of type II collagen, matrix metalloproteinase-13 and cell proliferation by interleukin-1β is mediated by curcumin via inhibition of NF-κB signaling in rat chondrocytes

Curcumin possesses strong anti-inflammatory, anti-rheumatoid and anti-oxidative activities, and has the potential to inhibit nuclear factor-κB (NF-κB) signaling. Cartilage damage in osteoarthritis (OA) is largely mediated by interleukin-1β (IL-1β) via activation of various transcription factors, including NF-κB and activator protein-1. The aim of the present study was to determine whether IL-1β induces matrix metalloproteinase-13 (MMP-13) expression and inhibits type II collagen expression, as well as to examine whether cell proliferation may be inhibited by curcumin through the inhibition of NF-κB signaling. The effects of curcumin were investigated in rat articular chondrocyte cell cultures treated with IL-1β in the presence or absence of curcumin or the NF-κB inhibitor pyrrolidine dithiocarbamate. Western blotting and reverse transcription-quantitative polymerase chain reaction were conducted to evaluate protein and mRNA expression levels of type II collagen, MMP-13, NF-κB inhibitor α (IκBα), phosphorylated-IκBα and NF-κB subunit p65/RelA. Western blotting and immunofluorescence were performed to examine the effects of curcumin on the expression, phosphorylation and nuclear translocation of NF-κB-associated proteins. The effects of curcumin on cell proliferation were evaluated by Cell Counting Kit-8 (CCK-8). Curcumin was demonstrated to inhibit the IL-1β-induced activation of NF-κB by suppressing IκBα phosphorylation and p65/RelA nuclear translocation. These events were associated with the downregulation of MMP-13 expression and the upregulation of type II collagen expression, both of which are considered to be NF-κB targets. CCK-8 assays revealed that co-treatment with curcumin resulted in increased proliferation in IL-1β-treated chondrocytes. These findings implicated curcumin as a naturally occurring anti-inflammatory agent for the treatment of OA via inhibition of NF-κB signaling.

RETRACTED: Inhibition of the p38-MAPK signaling pathway suppresses the apoptosis and expression of proinflammatory cytokines in human osteoarthritis chondrocytes

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Sections within Figures 2 and 6 appear similar to each other. Also, Figure 1B appears similar with a panel from Figure 1k of the article published by Lin Xiao, Dongping Gong, Loufeng Liang, Anwei Liang, Huaxin Liang, Xiayi Xu and Hongli Teng in Clinical Epigenetics 13 (2021) 53 https://doi.org/10.1186/s13148-021-01005-9, while Figure 4B appears similar with a panel from Figure 2A of the article published by Hongwei Chen, Shengdi Yang and Ruyi Shao in Arthritis Research & Therapy 21 (2019) 271 https://doi.org/10.1186/s13075-019-2033-5. Although this article was published earlier than the other articles, the Editor decided to retract this article given concerns about the reliability of the data. Following the release of the concerns in the public domain, the authors contacted the journal to report that some of the experiments in this article were executed in the laboratory of a third-party company. The authors reportedly found that the results of these experiments were unreliable in later validation experiments. The authors would like to apologize for the inconvenience caused.

Insights on Molecular Mechanisms of Chondrocytes Death in Osteoarthritis

Osteoarthritis (OA) is a joint pathology characterized by progressive cartilage degradation. Medical care is mainly based on alleviating pain symptoms. Compelling studies report the presence of empty lacunae and hypocellularity in cartilage with aging and OA progression, suggesting that chondrocyte cell death occurs and participates to OA development. However, the relative contribution of apoptosis per se in OA pathogenesis appears complex to evaluate. Indeed, depending on technical approaches, OA stages, cartilage layers, animal models, as well as in vivo or in vitro experiments, the percentage of apoptosis and cell death types can vary. Apoptosis, chondroptosis, necrosis, and autophagic cell death are described in this review. The question of cell death causality in OA progression is also addressed, as well as the molecular pathways leading to cell death in response to the following inducers: Fas, Interleukin-1β (IL-1β), Tumor Necrosis factor-α (TNF-α), leptin, nitric oxide (NO) donors, and mechanical stresses. Furthermore, the protective role of autophagy in chondrocytes is highlighted, as well as its decline during OA progression, enhancing chondrocyte cell death; the transition being mainly controlled by HIF-1α/HIF-2α imbalance. Finally, we have considered whether interfering in chondrocyte apoptosis or promoting autophagy could constitute therapeutic strategies to impede OA progression.

Crude extract of Euphorbia formosana induces apoptosis of DU145 human prostate cancer cells acts through the caspase-dependent and independent signaling pathway

Prostate cancer is the most frequently diagnosed malignancy in men and the second highest contributor of male cancer mortality. The crude extract of Euphorbia formosana (CEEF) has been used for treatment of different diseases but the cytotoxic effects of CEEF on human cancer cells have not been reported. The purpose of the present experiments was to determine effects of CEEF on cell cycle distribution and induction of apoptosis in DU145 human prostate cancer cells in vitro. Contrast-phase microscope was used for examining cell morphological changes. Flow cytometric assays were used for cell viability, cell cycle, apoptosis, reactive oxygen species, and Ca²⁺ production and mitochondria membrane potential (ΔΨ_m ). Western blotting was used for examining protein expression of cell cycle and apoptosis associated proteins. Real-time PCR was used for examining mRNA levels of caspase-3, -8, and -9, AIF, and Endo G. Confocal laser microscope was used to examine the translocation of AIF, Endo G, and cytochrome in DU145 cells after CEEF exposure. CEEF-induced cell morphological changes, decreased the percentage of viable cells, and induced S phase arrest and apoptosis in DU145 cells. Furthermore, CEEF promoted RAS and Ca²⁺ production and reduced ΔΨ_m levels. Real-time QPCR confirmed that CEEF promoted the mRNA expression of caspase-3 and -9, AIF and Endo G and we found that AIF and Endo G and cytochrome c were released from mitochondria. Taken together, CEEF-induced cytotoxic effects via ROS production, induced S phase arrest and induction of apoptosis through caspase-dependent and independent and mitochondria-dependent pathways in DU245 cancer cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1600-1611, 2016.

Clinical effects of perazine ferulate tablets combined with eucalyptol limonene pinene enteric soft capsules for treatment of children with IgA nephropathy

The clinical effects of piperazine ferulate tablets combined with eucalyptol limonene pinene enteric soft capsules for treatment of children with IgA nephropathy were investigated. Sixty children with IgA nephropathy were included in the study and were randomly divided into the control (n=30) and observation (n=30) groups. The patients in the control group were treated with conservative or hormone therapy while patients in the observation group were treated with piperazine ferulate tablets combined with eucalyptol-limonene-pinene enteric soft capsules. Clinical effects were observed and compared. The total effective rate of the observation group was significantly higher than that of the control group, while the incidence of complications was significantly lower than that of the control group (p<0.05). Serum IgA and fibronectin levels of the observation group were significantly lower than those of the control group, while the level of C3 was significantly higher than that of the control group (p<0.05). In conclusion, piperazine ferulate tablets combined with eucalyptus enteric soft capsule constituted a safe and effective for the treatment of children with IgA nephropathy. The treatment was superior to conservative or hormone therapy, and thus worthy of clinical promotion.