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

Epigallocatechin-3-O-gallate promotes extracellular matrix and inhibits inflammation in IL-1β stimulated chondrocytes by the PTEN/miRNA-29b pathway

CONTEXT

Epigallocatechin-3-O-gallate (EGCG) exhibits anti-arthritic activity. MiR-29b-3p provokes chondrocyte apoptosis and promotes the initiation and development of osteoarthritis (OA).

OBJECTIVE

To explore the roles of EGCG and miR-29b-3p in interleukin-1β (IL-1β)-stimulated chondrocytes.

MATERIALS AND METHODS

HE and Safranin O staining were used to detect the pathological changes of cartilage tissue in OA patients and healthy people. OA-like chondrocyte injury was mimicked by 5 ng/mL IL-1β stimulation for 24 h in vitro, and after transfection with miR-29b-3p mimics and pcDNA-PTEN, IL-1β-stimulated chondrocytes were pre-treated with EGCG (20 and 50 μM) for 2 h. Cell viability, colony numbers, apoptosis rate, the levels of IL-6 and matrix metalloproteinase-13 (MMP-13), miR-19b-3p, PTEN and apoptosis-associated proteins in chondrocytes were evaluated.

RESULTS

MiR-29b-3p level was upregulated in cartilage tissues of OA patients (3.5-fold change, p < 0.001) and IL-1β stimulated chondrocytes (two fold change, p < 0.001). The matrix staining was weakened and unevenly distributed, and the chondrocytes were arranged disorderly in the tissues of patients with OA. EGCG (20 and 50 μM) increases viability and decreases the levels of miR-29b-3p and MMP-13 and IL-6 in IL-1β stimulated chondrocytes (p < 0.05). MiR-29b-3p mimics reversed the effects above 50 μM EGCG (p < 0.05). Furthermore, PTEN overexpression abrogated the effects of miR-29b-3p mimics on viability, colony numbers, apoptosis rate and the levels of Bcl-2, MMP-13, IL-6, Bax and cleaved caspase 3 in IL-1β-stimulated chondrocytes (p < 0.01).

DISCUSSION AND CONCLUSIONS

EGCG is a potential candidate for the treatment of OA, which also can be explored in a novel therapeutic method for other degenerative or inflammatory disorders.

Expression of VEGF-A Signaling Pathway in Cartilage of ACLT-induced Osteoarthritis Mouse Model

BACKGROUND

Anterior cruciate ligament transection surgery (ACLT)-induced OA model was often used to investigate the molecular mechanism of knee osteoarthritis (KOA). Researches have shown that vascular endothelial growth factor (VEGF) played an important role in OA. The present study aimed to investigate the pathological changes after ACLT surgery and reveal the expression characteristics of the VEGF-A/VEGFR2 signaling pathway in this model.

METHODS

Moderate KOA model was established by ACLT, and 1, 2, 4, 8, and 12 weeks after surgery, hematoxylin-eosin (HE) and Safranin-O(S-O) staining were used to detect the pathological changes in mouse knee cartilage, and the matrix biomarkers A Disintegrin and Metalloproteinase with Thrombospondin Motifs 5(ADAMTS5), Collagen II (COL-II) were detected using immunohistochemistry (IHC), CD31 was detected by immunofluorescence (IF) to show the vascular invasion in cartilage, and proteins expression of VEGF-A pathway were detected by Western blot (WB). Meanwhile, the inflammatory biomarkers cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in cartilage were detected by WB.

RESULTS

ACLT surgery can lead to degeneration of cartilage in mice, and the characteristics of the lesion were time-dependent. The ADAMTS5-positive cells increased while COL-II decreased in OA cartilage with time, and new blood vessels labeled by CD31 can be seen from 1 week in OA cartilage, and increased in 8 and 12 weeks. The expression of VEGF-A, VEGFR2, COX-2, and iNOS were higher than control groups, which were basically consistent with the degree of osteoarthritis.

CONCLUSIONS

The degenerative degree of articular cartilage was time-dependent; angiogenesis and inflammation were important pathological changes of cartilage in KOA. The expression of the VEGF-A/VEGFR2 signaling pathway was basically correlated with the degree of KOA.

MiR-30b-5p Influences Chronic Exercise Arthritic Injury by Targeting Hoxa1

We identified the role of miR-30b-5p in chronic exercise arthritic injury. Rats with chronic exercise arthritic injury received treatment with miR-30b-5p antagomiR. H&E and Safranin O-fast green staining were performed. The levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were detected. The binding relationship between homeobox A1 (Hoxa1) and miR-30b-5p was revealed. After manipulating the expressions of miR-30b-5p and/or Hoxa1 in chondrocytes, the viability, apoptosis and migration of chondrocytes were assessed. The levels of molecules were determined by qRT-PCR or Western blot. MiR-30b-5p antagomiR ameliorated articular cartilage lesion and destruction, reduced Mankin's score and the levels of TNF-α, IL-1β, miR-30b-5p, matrix metallopeptidase 13 (MMP-13), and cleaved caspase-3, and increased relative thickness and the levels of Hoxa1, Aggrecan and type II collagen (COLII) in model rats. MiR-30b-5p up-regulation decreased Hoxa1 level, viability, migration and induced apoptosis, whereas miR-30b-5p down-regulation produced the opposite effects. MiR-30b-5p up-regulation increased the levels of MMP-13 and cleaved caspase-3, but decreased those of Aggrecan and COLII in chondrocytes. However, the action of miR-30b-5p up-regulation on chondrocytes was reversed by Hoxa1 overexpression. In conclusion, miR-30b-5p is involved in cartilage degradation in rats with chronic exercise arthritic injury and regulates chondrocyte apoptosis and migration by targeting Hoxa1.

Gelatin reduced Graphene Oxide Nanosheets as Kartogenin Nanocarrier Induces Rat ADSCs Chondrogenic Differentiation Combining with Autophagy Modification

Biocompatible reduced graphene oxide (rGO) could deliver drugs for synergistically stimulating stem cells directed differentiation with influences on specific cellular activities. Here, we prepared a biodegradable gelatin reduced graphene oxide (rGO@Ge) to evaluate its functions in promoting rat adipose derived mesenchymal stem cells (ADSCs) chondrogenic differentiation through delivering kartogenin (KGN) into the stem cell efficiently. The optimum KGN concentration (approximately 1 μM) that promoted the proliferation and chondrogenic differentiation of ADSCs was clarified by a series of experiments, including immunofluorescent (IF) staining (Sox-9, Col II), alcian blue (Ab) staining, toluidine blue (Tb) staining and real-time quantitative PCR analysis of the chondrogenic markers. Meanwhile, the biocompatibility of rGO@Ge was evaluated to clearly define the nonhazardous concentration range, and the drug loading and releasing properties of rGO@Ge were tested with KGN for its further application in inducing ADSCs chondrogenic differentiation. Furthermore, the mechanism of rGO@Ge entering ADSCs was investigated by the different inhibitors that are involved in the endocytosis of the nanocarrier, and the degradation of the rGO@Ge in ADSCs was observed by transmission electron microscopy (TEM). The synergistic promoting effect of rGO@Ge nanocarrier on ADSCs chondrogenesis with KGN was also studied by the IF, Ab, Tb stainings and PCR analysis of the chondrogenic markers. Finally, the intracellular Reactive Oxygen Species (ROS) and autophagy induced by KGN/rGO@Ge complex composites were tested in details for clarification on the correlation between the autophagy and chondrogenesis in ADSCs induced by rGO@Ge. All the results show that rGO@Ge as a biocompatible nanocarrier can deliver KGN into ADSCs for exerting a pro-chondrogenic effect and assist the drug to promote ADSCs chondrogenesis synergistically through modification of the autophagy in vitro, which promised its further application in repairing cartilage defect in vivo.

Bufalin: A Systematic Review of Research Hotspots and Antitumor Mechanisms by Text Mining and Bioinformatics

Bufalin is an anticancer drug extract from traditional Chinese medicine. Several articles about bufalin have been published. However, the literature on bufalin has not yet been systematically studied. This study aimed to identify the study status and knowledge structures of bufalin and to summarize the antitumor mechanism. Data were retrieved and downloaded from the PubMed database. The softwares of BICOMB, gCLUTO, Ucinet 6.0, and NetDraw2.084 were used to analyze these publications. The bufalin related genes were recognized and tagged by ABNER software. Then these BF-related genes were performed by Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, and protein-protein interaction (PPI) network analysis. A total of 474 papers met the search criteria from 2000 to 2019. By biclustering clustering analysis, the 50 high-frequency main MeSH terms/subheadings were classified into 5 clusters. The clusters of drug therapy and the mechanism of bufalin were hotspot topics. A total of 50 genes were identified as BF-related genes. PPI network analysis showed that inducing apoptosis was the main effect of bufalin, and apoptosis-related gene Caspase 3 was the most reported by people. Bufalin could inhibit the proliferation, invasion, and metastasis of cancer cells through multiple signaling pathways, such as PI3K/AKT, Hedgehog, MAPK/JNK, Wnt/[Formula: see text]-catenin, TGF-[Formula: see text]/Smad, Integrin signaling pathway, and NF-KB signaling pathway via KEGG analysis. Through the quantitative analysis of bufalin literature, we revealed the research status and hot spots in this field and provided some guidance for further research.

An Update on the Emerging Role of Visfatin in the Pathogenesis of Osteoarthritis and Pharmacological Intervention

Osteoarthritis (OA) is one of the most common degenerative joint diseases that affects millions of people worldwide, mainly the aging population. Despite numerous published reports, little is known about the pathology of this disease, and no feasible treatment plan exists to stop OA progression. Recently, extensive basic and clinical studies have shown that adipokines play a key role in OA development. Moreover, some drugs associated with adipokines have shown chondroprotective and anti-inflammatory effects on OA. Visfatin has been shown to play a detrimental role in the progression of OA. It increases the production of matrix metalloproteinases and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), induces the production of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, affects the differentiation of mesenchymal stem cells to adipocytes, and induces osteophyte formation by inhibiting osteoclastogenesis. Although some side effects of chemical visfatin inhibitors have been reported, they were shown to be successful in the treatment of diabetes, cancer, and other diseases that can utilize Chinese herbs, further suggesting that similar therapeutic strategies could be used in OA prevention and treatment. Here, we describe the pathophysiological mechanism of visfatin in OA and discuss some potential pharmacological interventions using Chinese herbs.

Rapamycin protects chondrocytes against IL-18-induced apoptosis and ameliorates rat osteoarthritis

Interleukin 18 (IL-18) promotes inflammation and apoptosis in chondrocytes, thereby contributing to the development and progression of osteoarthritis (OA). Here, we investigated the effects of IL-18 treatment and inhibition in rat chondrocytes in vitro and in vivo. We used RT-PCR and Western blotting to measure the mRNA and protein levels of the chondrocyte-specific genes Collagen II and Aggrecan as well as the protein levels of apoptosis-related (Bax, Bcl2, Caspase3/9), autophagy-related (Atg5, Atg7, Beclin1, LC3), and mTOR pathway-related genes (PI3K, Akt, mTOR). We observed a decrease in Collagen II and Aggrecan mRNA and protein levels, upregulation of chondrocyte apoptosis, downregulation of chondrocyte autophagy, and activation of the PI3K/Akt/mTOR pathway upon IL-18 treatment. PI3K/Akt/mTOR pathway activation and inhibition tests using rat 740Y-P (PI3K activator), SC79 (AKT activator), 3BDO (mTOR activator), or LY294002 (PI3K inhibitor) revealed that activation of the PI3K/Akt/mTOR pathway enhances chondrocyte-specific gene degradation induced by IL-18, while its inhibition has protective effects on chondrocytes. We also found that treatment with rapamycin (a selective mTOR inhibitor) also exerts chondro-protective effects that ameliorate OA by promoting autophagy. These results suggest that inhibition of the mTOR pathway could be exploited for therapeutic benefits in the treatment of OA.

Circulating microRNA let‑7e is decreased in knee osteoarthritis, accompanied by elevated apoptosis and reduced autophagy

Knee osteoarthritis (KOA) is a major cause of leg disability in the elderly population. Recently, the expression levels of circulating microRNA (miRNA) let-7e have been reported to be significantly reduced in KOA. The aims of the present study were to assess the feasibility of let-7e as a serum marker for detecting KOA and to explore the underlying mechanisms of its involvement. Based on previous studies and bioinformatics analysis, let-7e may regulate apoptosis and autophagy of articular chondrocytes. A total of 10 patients with KOA and 10 patients with trauma without KOA were recruited to examine the levels of let-7e in peripheral blood. Subsequently, KOA rat models were established, and the levels of let-7e in the cartilage and serum were examined, the expression of apoptotic proteins and autophagy-related proteins in the cartilage were investigated, and apoptotic and autophagic activities of primary cultured chondrocytes were also detected. In patients with KOA, let-7e levels in the peripheral serum were significantly decreased compared with the control group, and this result was confirmed in the peripheral serum and cartilage of KOA rats. In addition, the expression levels of proteins involved in the apoptotic pathway were increased in the cartilage of KOA rats, and apoptotic activity was increased. The expression of autophagy-related proteins beclin 1 and microtubule associated protein 1 light chain 3 β (LC3B) II/LC3BI in the articular cartilage of KOA rats was lower compared with the controls, and autophagy was decreased. Si-Miao-San (SMS) treatment restored the expression of let-7e and reversed the changes in apoptosis and autophagy. Therefore, the present study provided additional evidence that circulating let-7e may be a potential serum biomarker for the diagnosis and treatment of KOA. Elevated apoptosis levels and decreased autophagy levels of cartilage tissue are involved in KOA, and treatment with SMS may reverse these effects.

Identification of Key Genes and Pathways Associated with Sex Differences in Osteoarthritis Based on Bioinformatics Analysis

Sex differences have been suggested to play critical roles in the pathophysiology of osteoarthritis (OA), resulting in sex-specific prevalence and incidence. However, their roles in the development of OA remain largely unknown. The aim of this study was to screen out key genes and pathways mediating biological differences between OA females after menopause and OA males. First, the gene expression data of GSE36700 and GSE55457 were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) between sexes were identified using R software, respectively. The overlapping DEGs were obtained. Then, protein-protein interactive (PPI) network was constructed to further analyze interactions between the overlapping DEGs. Finally, enrichment analyses were separately performed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes tools. In our results, a total of 278 overlapping DEGs were identified between OA females after menopause and OA males, including 219 upregulated and 59 downregulated genes. In the PPI network, seven hub genes were identified, including EGF, ERBB2, CDC42, PIK3R2, LCK, CBL, and STAT1. Functional enrichment analysis revealed that these genes were mainly enriched in PI3K-Akt signaling pathway, osteoclast differentiation, and focal adhesion. In conclusion, the results in the current study suggest that pathways of PI3K-Akt, osteoclast differentiation, and focal adhesion may play important roles in the development of OA females after menopause. EGFR, ERBB2, CDC42, and STAT1 may be key genes related to OA progression in postmenopausal women and may be promising therapeutic targets for OA.