Diazoxide ameliorates severity of experimental osteoarthritis by activating autophagy via modulation of the osteoarthritis-related biomarkers

Miao medicine Gu Yan Xiao tincture inhibits mTOR to stimulate chondrocyte autophagy in a rabbit model of osteoarthritis

ETHNOPHARMACOLOGICAL RELEVANCE

The Gu Yan Xiao tincture, a blend of traditional Chinese herbs, is traditionally used for osteoarthritis and related pain. This study investigated its mechanism of action in order to rationalize and validate its therapeutic use.

AIM OF THE STUDY

This study analyzed, in a rabbit model of knee osteoarthritis, whether and how Gu Yan Xiao tincture exerts therapeutic benefits by modulating chondrocyte autophagy.

MATERIALS AND METHODS

The active constituents within the GYX tincture were identified using liquid chromatography-mass spectrometry. The rabbit model was established by injecting animals with type II collagenase intra-articularly, and the effects of topically applied tincture were examined on osteoarthritis lesions of the knee using histopathology, micro-computed tomography and x-ray imaging. Effects of the tincture were also evaluated on levels of inflammatory cytokines, matrix metalloproteases, and autophagy in chondrocytes. As a positive control, animals were treated with sodium diclofenac.

RESULTS

The tincture mitigated the reduction in joint space, hyperplasia of the synovium and matrix metalloproteases in serum that occurred after injection of type II collagenase in rabbits. These therapeutic effects were associated with inhibition of mTOR and activation of autophagy in articular chondrocytes. Inhibiting mTOR with rapamycin potentiated the therapeutic effects of the tincture, while inhibiting autophagy with 3-methyladenine antagonized them.

CONCLUSIONS

Gu Yan Xiao tincture mitigates tissue injury in a rabbit model of osteoarthritis, at least in part by inhibiting mTOR and thereby promoting autophagy in chondrocytes. These results rationalize the use of the tincture not only against osteoarthritis but also potentially other diseases involving inhibition of autophagy in bones and joints.

Identification of autophagy-related genes in osteoarthritis articular cartilage and their roles in immune infiltration

Background

Autophagy plays a critical role in the progression of osteoarthritis (OA), mainly by regulating inflammatory and immune responses. However, the underlying mechanisms remain unclear. This study aimed to investigate the potential relevance of autophagy-related genes (ARGs) associated with infiltrating immune cells in OA.

Methods

GSE114007, GSE169077, and ARGs were obtained from the Gene Expression Omnibus (GEO) database and the Human Autophagy database. R software was used to identify the differentially expressed autophagy-related genes (DEARGs) in OA. Functional enrichment and protein-protein interaction (PPI) analyses were performed to explore the role of DEARGs in OA cartilage, and then Cytoscape was utilized to screen hub ARGs. Single-sample gene set enrichment analysis (ssGSEA) was used to conduct immune infiltration analysis and evaluate the potential correlation of key ARGs and immune cell infiltration. Then, the expression levels of hub ARGs in OA were further verified by the GSE169077 and qRT-PCR. Finally, Western blotting and immunohistochemistry were used to validate the final hub ARGs.

Results

A total of 24 downregulated genes and five upregulated genes were identified, and these genes were enriched in autophagy, mitophagy, and inflammation-related pathways. The intersection results identified nine hub genes, namely, CDKN1A, DDIT3, FOS, VEGFA, RELA, MAP1LC3B, MYC, HSPA5, and HSPA8. GSE169077 and qRT-PCR validation results showed that only four genes, CDKN1A, DDT3, MAP1LC3B, and MYC, were consistent with the bioinformatics analysis results. Western blotting and immunohistochemical (IHC) showed that the expression of these four genes was significantly downregulated in the OA group, which is consistent with the qPCR results. Immune infiltration correlation analysis indicated that DDIT3 was negatively correlated with immature dendritic cells in OA, and FOS was positively correlated with eosinophils.

Conclusion

CDKN1A, DDIT3, MAP1LC3B, and MYC were identified as ARGs that were closely associated with immune infiltration in OA cartilage. Among them, DDIT3 showed a strong negative correlation with immature dendritic cells. This study found that the interaction between ARGs and immune cell infiltration may play a crucial role in the pathogenesis of OA; however, the specific interaction mechanism needs further research to be clarified. This study provides new insights to further understand the molecular mechanisms of immunity involved in the process of OA by autophagy.

The Effect of JAK Inhibitor Tofacitinib on Chondrocyte Autophagy

Osteoarthritis (OA) is a multifactorial disease of the whole joint that has a complex pathogenesis. There is currently no cure for OA. Tofacitinib is a broad JAK inhibitor that can have an anti-inflammatory effect. The objective of this study was to investigate the effect of tofacitinib on the cartilage extracellular matrix in OA and determine whether tofacitinib exerts a protective effect by inhibiting the JAK1/STAT3 signaling pathway and upregulating autophagy in chondrocytes. We investigated the expression profile of OA in vitro by exposing SW1353 cells to interleukin-1β (IL-1β), and induced OA in vivo using the modified Hulth method in rats. We found that IL-1β promoted the expression of OA-related matrix metalloproteinases (MMP3 and MMP13), reduced the expression of collagen II, reduced the expression of beclin1 and LC3-II/I, and promoted the accumulation of p62 in SW1353 cells. Tofacitinib attenuated IL-1β-stimulated changes in MMPs and collagen II and restored autophagy. In IL-1β-stimulated SW1353 cells, the JAK1/STAT3 signaling pathway was activated. Tofacitinib inhibited the IL-1β-stimulated expression of p-JAK1 and p-STAT3 and prevented translocation of p-STAT3 to the nucleus. In the rat model of OA, tofacitinib reduced articular cartilage degeneration by delaying cartilage extracellular matrix degradation and increasing chondrocyte autophagy. Our study demonstrates that chondrocyte autophagy was impaired in experimental models of OA. Tofacitinib reduced the inflammatory response and restored the damaged autophagic flux in OA.

The Effect of the JAK-inhibitor Tofacitinib on Chondrocyte Autophagy in Osteoarthritis.. [DOI: 10.21203/rs.3.rs-2670470/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Osteoarthritis (OA) is a multifactorial disease of the whole joint that has a complex pathogenesis. There is currently no cure for OA. Tofacitinib is a broad JAK inhibitor that can have an anti-inflammatory effect. The objective of this study was to investigate the effect of tofacitinib on the cartilage extracellular matrix in OA and determine whether tofacitinib exerts a protective effect by inhibiting the JAK1/STAT3 signaling pathway and upregulating autophagy in chondrocytes. We established an vitro OA model by exposing SW1353 cells to interleukin-1β (IL-1β) and induced OA in rats using the modified Hulth method. We found that IL-1β promoted the expression of OA-related matrix metalloproteinases (MMP-3 and MMP-13), reduced the expression of collagen II, reduced the expression of beclin1 and LC3-II/I, and promoted the accumulation of p62 in SW1353 cells. Tofacitinib attenuated IL-1β-stimulated changes in MMPs and collagen II and restored chondrocyte autophagy. In IL-1β-stimulated SW1353 cells, the JAK1/STAT3 signaling pathway was activated. Tofacitinib inhibited the IL-1β-stimulated expression of p-JAK1 and p-STAT3 and prevented translocation of p-STAT3 to the nucleus. In the rat model of OA, tofacitinib reduced articular cartilage degeneration by delaying cartilage extracellular matrix degradation and increasing chondrocyte autophagy. Our study demonstrates that chondrocyte autophagy was impaired in experimental models of OA. Tofacitinib reduced the inflammatory response and restored the damaged autophagic flux in OA.

Autophagy in the pathogenesis and therapeutic potential of post-traumatic osteoarthritis

Autophagy, as a fundamental mechanism for cellular homeostasis, is generally involved in the occurrence and progression of various diseases. Osteoarthritis (OA) is the most common musculoskeletal disease that often leads to pain, disability and economic loss in patients. Post-traumatic OA (PTOA) is a subtype of OA, accounting for >12% of the overall burden of OA. PTOA is often caused by joint injuries including anterior cruciate ligament rupture, meniscus tear and intra-articular fracture. Although a variety of methods have been developed to treat acute joint injury, the current measures have limited success in effectively reducing the incidence and delaying the progression of PTOA. Therefore, the pathogenesis and intervention strategy of PTOA need further study. In the past decade, the roles and mechanisms of autophagy in PTOA have aroused great interest in the field. It was revealed that autophagy could maintain the homeostasis of chondrocytes, reduce joint inflammatory level, prevent chondrocyte death and matrix degradation, which accordingly improved joint symptoms and delayed the progression of PTOA. Moreover, many strategies that target PTOA have been revealed to promote autophagy. In this review,  we summarize the roles and mechanisms of autophagy in PTOA and the current strategies for PTOA treatment that depend on autophagy regulation, which may be beneficial for PTOA patients in the future.

MiR-21 participates in the neuroprotection of diazoxide against hypoxic-ischemia encephalopathy by targeting PDCD4

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of neonatal death and permanent neurological disability. Here, we designed to quest therapeutic effects of diazoxide (DZ) on HIE and its mechanism.

METHODS

The cell model of HIE was established. CCK8 and flow cytometry were applied to test cell viability and apoptosis. RT-qPCR and western blotting was evaluated to the expression of miR-21, PDCD4, PI3K, and p-AKT/AKT. Commercial kits were employed to detect SOD, MDA, LDH. DCFH-DA was used to measure intracellular ROS. ELISA was performed to estimate IL-1β, IL-6 and TNF-α. Dual-luciferase reporter gene and RIP assay were applied to confirm the binding relationships between miR-21 and PDCD4.

RESULTS

In H19-7 cells and PC12 cells stimulated by OGD, with low cell viability, high apoptosis, miR-21 high expression and PDCD4 low expression. However, the functions were all reversed by DZ administration. Furthermore, miR-21 inhibitor could abolish the beneficial effects of DZ on OGD-induced cells. Besides, miR-21 could interact with PDCD4. In addition, PDCD4 involved with the regulation of DZ to OGD-induced cells via PI3K/AKT pathway.

CONCLUSION

DZ enhanced miR-21 level and inhibited PDCD4 level via PI3K/AKT pathway to resisted HIE.

Timosaponin B-II alleviates osteoarthritis-related inflammation and extracellular matrix degradation through inhibition of mitogen-activated protein kinases and nuclear factor-κB pathways in vitro

Osteoarthritis (OA), an inflammatory response in chondrocytes, leads to extracellular matrix (ECM) degradation and cartilage destruction. Timosaponin B-II (TB-II) is the main bioactive component of Rhizoma Anemarrhenae with reported antioxidant and anti-inflammatory effects. This study investigated the anti-OA function and mechanism of TB-II on IL-1β-stimulated SW1353 cells and primary rat chondrocytes. We firstly screened the concentration of TB-II in SW1353 cells and primary rat chondrocytes using CCK-8 assay. Thereafter, SW1353 cells and chondrocytes were, respectively, pretreated with TB-II (20 and 40 μg/mL) and TB-II (10 and 30 μg/mL) for 24 h and then stimulated with interleukin 1β (IL-1β, 10 ng/mL) for another 24 hours. Results showed that TB-II suppressed the production of reactive oxygen species, the protein levels of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1β-stimulated SW1353 cells and chondrocytes. IL-1β-induced high secretion levels of nitric oxide and prostaglandin 2, TNF-α, IL-6 and MCP-1 were down-regulated by TB-II treatment, indicating an anti-inflammatory effect of TB-II on OA in vitro condition. Moreover, TB-II weakened the mRNA and protein expression of (matrix metalloproteinase) MMPs including MMP-1, MMP-3, and MMP-13, indicating the protection of TB-II against ECM degradation. Mechanically, TB-II suppressed MAPKs and NF-κB pathways under IL-1β stimulation evidenced by the down-regulated protein expression of p-ERK, p-p38, p-JNK, p-p65 and the reduced translocation of p65 subunit to the nucleus. The present study demonstrated that TB-II might become a novel therapeutic agent for OA treatment through repressing IL-1β-stimulated inflammation, oxidative stress and ECM degradation via suppressing the MAPKs and NF-κB pathways.

METTL3 involves the progression of osteoarthritis probably by affecting ECM degradation and regulating the inflammatory response

We aimed to identify RNA N6-methyladenosine methylation associated genes in osteoarthritis (OA), and to explore possible regulatory mechanisms of these RNA methylation associated genes. Bioinformatics analyses, including differential expression analysis, functional enrichment analysis, verification analysis, and box plot analysis, were conducted based on different datasets from OA and non-OA patients. Gene expression at mRNA and protein levels was determined by quantitative reverse transcription PCR, western blot and immunofluorescence. Interleukin 1β (IL-1β)-treated SW1353 cells was used as cell model. Lentiviral vector was used for over-expression METTL3 in vitro. CCK-8 assay kit was used to determine cell viability and inflammatory cytokines (IL-1α, IL-6, IL-8, IL-10 and TNF-α) was detected using ELISA kits. Bioinformatics analysis showed that METTL3 expression was decreased in OA group, which was confirmed in clinical samples. Expression of METTL3 was also reduced in IL-1β-treated cells. Levels of inflammatory cytokines were obviously reduced in the METTL3 overexpression group, while IL-1β treatment reversed such decrease caused by METTL3 overexpression (p < 0.05). Both METTL3 overexpression and IL-1β treatment promoted expression of p65 protein and p-ERK (p < 0.01). Additionally, increased expression of MMP1 and MMP3, and decreased expression of MMP13, TIMP-1, and TIMP-2 at both mRNA and protein levels were observed in the METTL3 overexpression group when compared with the control group (p < 0.01). Expression of m6A methylation gene METTL3 was reduced in OA. METTL3 is involved in OA probably by regulating the inflammatory response. METTL3 overexpression may affect extracellular matrix degradation in OA by adjusting the balance between TIMPs and MMPs.

Targeting the Mitochondria-Proteostasis Axis to Delay Aging

Human life expectancy continues to grow globally, and so does the prevalence of age-related chronic diseases, causing a huge medical and economic burden on society. Effective therapeutic options for these disorders are scarce, and even if available, are typically limited to a single comorbidity in a multifaceted dysfunction that inevitably affects all organ systems. Thus, novel therapies that target fundamental processes of aging itself are desperately needed. In this article, we summarize current strategies that successfully delay aging and related diseases by targeting mitochondria and protein homeostasis. In particular, we focus on autophagy, as a fundamental proteostatic process that is intimately linked to mitochondrial quality control. We present genetic and pharmacological interventions that effectively extend health- and life-span by acting on specific mitochondrial and pro-autophagic molecular targets. In the end, we delve into the crosstalk between autophagy and mitochondria, in what we refer to as the mitochondria-proteostasis axis, and explore the prospect of targeting this crosstalk to harness maximal therapeutic potential of anti-aging interventions.

Punicalagin Inhibits Tert-Butyl Hydroperoxide-Induced Apoptosis and Extracellular Matrix Degradation in Chondrocytes by Activating Autophagy and Ameliorates Murine Osteoarthritis

Background

Osteoarthritis (OA) is a prevalent articular disorder and has no entirely satisfactory treatment. Punicalagin (PUG) is a polyphenol which has shown multiple pharmacological effects on various diseases. However, the role of PUG in the treatment of OA has not been well defined.

Methods

The effects of PUG on anti-oxidative stress, anti-apoptosis, extracellular matrix (ECM) degradation and autophagy were evaluated in chondrocytes through Western blot and immunofluorescence (IF) staining. Meanwhile, the effects of PUG on destabilization of the medial meniscus (DMM) model were also assessed in vivo by performing histopathologic analysis and IF staining.

Results

In vitro, PUG treatment not only increased the level of HO-1 and SOD1 against oxidative stress but also suppressed the expression of apoptotic proteins and inhibited ECM degradation. Meanwhile, PUG treatment activated autophagy and restores autophagic flux in chondrocytes after tert-butyl hydroperoxide (TBHP) insult, inhibition of autophagy by 3-methyladenine (3-MA) partly abrogated the protective effects of PUG on chondrocytes. In vivo, degeneration of the articular cartilage following DMM was also ameliorated by PUG treatment.

Conclusion

PUG prevents the progression of OA through inhibition of apoptosis, oxidative stress and ECM degradation in chondrocytes, which mediated by the activation of autophagy.

Chondro-protective effects of polydatin in osteoarthritis through its effect on restoring dysregulated autophagy via modulating MAPK, and PI3K/Akt signaling pathways

Osteoarthritis (OA) is a degenerative disease of the cartilage that is prevalent in the middle-aged and elderly demography. Polydatin (PD), a natural resveratrol glucoside, has shown significant anti-inflammatory and anti-arthritic potential in previous studies. This study was designed to evaluate the therapeutic properties of PD in vitro and in vivo, and elucidate their underlying mechanisms. The expression levels of all relevant factors were evaluated by qRT-PCR, western blotting, and immunohistochemistry (IHC) where suitable. Reactive oxygen species (ROS) and apoptosis were analyzed using the suitable probes and flow cytometry. The histological evidence of cartilage was assessed in rat models, moreover, the several serum cytokines levels and autophagy levels were evaluated. The result showed PD displayed significant chondro-protective effects, inferred in terms of reduced inflammation and cartilage degradation, apoptosis inhibition, and lower ROS production. The protective effects were attenuated by the autophagy inhibitor 3-MA, indicating a mediating role of autophagy in PD action. Mechanistically, PD exerted its effects by inhibiting the MAPK and PI3K/Akt signaling pathways which led to the down-regulation of mTOR. In conclusion, PD protects against cartilage degeneration by activating the autophagy flux in the chondrocytes via the MAPK and PI3K/Akt signaling pathways.

Conditioned medium of mesenchymal stem cells delays osteoarthritis progression in a rat model by protecting subchondral bone, maintaining matrix homeostasis, and enhancing autophagy

Evidence accumulated that mesenchymal stem cell (MSC) therapy ameliorated osteoarthritis (OA) via paracrine effect, whereas conditioned medium (CM) of MSCs contains all the secretomes. In vitro studies have proved its therapeutic effect in OA, but few in vivo evidences were unveiled. This study investigated the effect of MSCs-CM in an animal model of OA. OA was induced by anterior cruciate ligament transaction and destabilization of the medial meniscus in 12 rats bilaterally. The CM group (N = 6) was administered with intraarticular injection of MSCs-CM weekly, whereas the phosphate-buffered saline (PBS) group (N = 6) was injected with PBS. Six rats served as normal control and received sham operation with weekly PBS injection. Rats were sacrificed 8 weeks postoperatively. Gross and histological morphology were analysed. Microcomputed tomography was applied to assess the subchondral bone. Components of extracellular matrix (ECM) including type II collagen (Col II) and aggrecan, and ECM homeostasis-related enzymes (metalloproteinase-13 [MMP-13] and tissue inhibitor of metalloproteinase-1 [TIMP-1]), as well as autophagy markers (Beclin-1 and microtubule-associated protein light chain 3) were evaluated immunohistochemically. Chondrocyte apoptosis was measured by terminal deoxynucleotidyl transferase dUTP nick-end labelling staining. Gene expression of Col II, aggrecan, MMP-13, and TIMP-1 was confirmed by real-time polymerase chain reaction. Morphological outcomes demonstrated remarkable articular-protective effect of MSCs-CM. Well-maintained subchondral bone structure, significantly more abundant cartilage matrix, notably decreased ratio of MMP-13 to TIMP-1, and inhibited chondrocyte apoptosis with enhanced autophagy were observed in the CM group compared with the PBS group. In conclusion, MSCs-CM demonstrated satisfactory effect in alleviating OA in rats via protecting the microarchitecture of subchondral bone, balancing the ratio of MMP-13 to TIMP-1 in cartilage, and enhancing autophagy, which might provide a new remedy against OA.