Cryptotanshinone interferes with chondrocyte apoptosis in osteoarthritis by inhibiting the expression of miR‑574‑5p

Nutritional Epigenomics: Bioactive Dietary Compounds in the Epigenetic Regulation of Osteoarthritis

Nutritional epigenomics is exceptionally important because it describes the complex interactions among food compounds and epigenome modifications. Phytonutrients or bioactive compounds, which are secondary metabolites of plants, can protect against osteoarthritis by suppressing the expression of inflammatory and catabolic mediators, modulating epigenetic changes in DNA methylation, and the histone or chromatin remodelling of key inflammatory genes and noncoding RNAs. The combination of natural epigenetic modulators is crucial because of their additive and synergistic effects, safety and therapeutic efficacy, and lower adverse effects than conventional pharmacology in the treatment of osteoarthritis. In this review, we have summarized the chondroprotective properties of bioactive compounds used for the management, treatment, or prevention of osteoarthritis in both human and animal studies. However, further research is needed into bioactive compounds used as epigenetic modulators in osteoarthritis, in order to determine their potential value for future clinical applications in osteoarthritic patients as well as their relation with the genomic and nutritional environment, in order to personalize food and nutrition together with disease prevention.

Protective effects of pulsed electromagnetic field therapy attenuates autophagy and apoptosis in osteoporotic osteoarthritis model rats by activating PPARγ

Osteoporotic osteoarthritis (OPOA) is a specific phenotype of OA with high incidence and severe cartilage damage. This study aimed to explore the protective efficacy of PEMF on the progression of OPOA and observed the effects of PEMF on PPARγ, autophagy- and apoptosis-related proteins in OPOA rats. Rats were randomly divided into three groups: control group, OPOA group, and PEMF group (n = 6). One week after surgery, the rats in PEMF group were subjected to PEMF (3.82 mT, 8 Hz, 40 min/day and 5 day/week) for 12 weeks. Results showed that PEMF retarded cartilage degeneration and bone loss, as evidenced by pathological staining image, decreased MMP-13 expression and increased bone mineral density. PEMF inhibited the serum levels of inflammatory cytokines, and the expressions of caspase-3 and caspase-8, while upregulated the expression of PPARγ. Moreover, PEMF significantly improved the autophagy disorders, represented by decrease expressions of Beclin-1, P62, and LC3B. The research demonstrates that PEMF can effectively prevent cartilage and subchondral bone destruction in OPOA rats. The potential mechanism may be related to upregulation of PPARγ, inhibition of chondrocyte apoptosis and inflammation, and improvement of autophagy disorder. PEMF therapy thus shows promising application prospects in the treatment of postmenopausal OA.

Circ-ABCA1 promotes oxidized low-density lipoprotein-induced inflammation and phenotypic switch in vascular smooth muscle cells

OBJECTIVE

Atherosclerosis (AS) is a chronic inflammatory disease of the arterial wall, in which Human Vascular Smooth Muscle Cells (HVSMCs) are involved. Nevertheless, the functions and mechanisms of circRNAs in oxidized Low-Density Lipoprotein (ox-LDL)-induced vascular smooth muscle cells remain unclear.

METHODS

Circ-ABCA1 expression was measured in the models of AS. Then, in the vitro model, oligonucleotide transfection was performed, followed by an analysis of VSMC proliferation, migration, inflammation, and phenotypic switch. Also, in the in vivo model, mice were injected with shRNA lentivirus, followed by histological examination of aortic tissues. Finally, the interaction of circ-ABCA1, miR-885-5p, and ROCK2 was identified.

RESULTS

Circ-ABCA1, was confirmed to be overexpressed in ox-LDL-induced VSMCs and mouse models of AS. Functionally, silencing circ-ABCA1 via oligonucleotide transfection suppressed VSMC proliferation, migration, inflammation, and phenotypic switch in vitro and prevented AS development in mice in vivo. Mechanistically, circ-ABCA1 absorbed miR-885-5p, which targeted ROCK2.

CONCLUSION

Taken together, the data from this study suggest that circ-ABCA1 mediates cellular inflammation and phenotype switching through the miR-885-5p/ROCK2 axis in ox-LDL-induced VSMCs, and the circ-ABCA1/miR-885-5p/ROCK2 axis is a new potential biomarker for the treatment of AS.

Exploration and breakthrough in the mode of chondrocyte death - A potential new mechanism for osteoarthritis

Osteoarthritis (OA) is a frequent chronic joint disease in orthopedics that effects individuals and society significantly. Obesity, aging, genetic susceptibility, and joint misalignment are all known risk factors for OA, but its pathomechanism is still poorly understood. Researches have revealed that OA is a much complex process related to inflammation, metabolic and chondrocyte death. It can affect all parts of the joint and is characterized by causing chondrocyte death and extracellular matrix descent. Previously, OA was thought to develop from excessive mechanical loading leading to the destruction of articular cartilage. Since some programmed cell deaths and OA share a pattern of chondrocyte destruction, it is likely that OA also involves programmed cell death. Even though chondrocyte apoptosis and pyroptosis have been investigated in OA, clarifing solely conventional cell death pathways is still insufficient to understand the pathophysiology of osteoarthritis. With more researches, it has been discovered that osteoarthritis and other new cell death processes, including PANoptosis, ferroptosis, and cell senescence, are strongly associated. Among these, PANoptosis combines the key traits of pyroptosis, cell apoptosis, and necrotic apoptosis into a highly coordinated and dynamically balanced programmed inflammatory cell death mechanism. Furthermore, we think that PANopotosis might obstruct necroptosis and cell senescence. Therefore, in order to offer direction for therapeutic treatment, we evaluate the development of research on multiple cell death of chondrocytes in OA.

Epigenetic Modifications of MiRNAs in Osteoarthritis: A Systematic Review on Their Methylation Levels and Effects on Chondrocytes, Extracellular Matrix and Joint Inflammation

Osteoarthritis (OA) is a joint disorder characterized by progressive degeneration of cartilage extracellular matrix (ECM), chondrocyte hypertrophy and apoptosis and inflammation. The current treatments mainly concern pain control and reduction of inflammation, but no therapeutic strategy has been identified as a disease-modifying treatment. Therefore, identifying specific biomarkers useful to prevent, treat or distinguish the stages of OA disease has become an immediate need of clinical practice. The role of microRNAs (miRNAs) in OA has been investigated in the last decade, and increasing evidence has emerged that the influence of the environment on gene expression through epigenetic processes contributes to the development, progression and aggressiveness of OA, in particular acting on the microenvironment modulations. The effects of epigenetic regulation, particularly different miRNA methylation during OA disease, were highlighted in the present systematic review. The evidence arising from this study of the literature conducted in three databases (PubMed, Scopus, Web of Science) suggested that miRNA methylation state already strongly impacts OA progression, driving chondrocytes and synoviocyte proliferation, apoptosis, inflammation and ECM deposition. However, the possibility of understanding the mechanism by which different epigenetic modifications of miRNA or pre-miRNA sequences drive the aggressiveness of OA could be the new focus of future investigations.

Salidroside alleviates severe acute pancreatitis-triggered pancreatic injury and inflammation by regulating miR-217-5p/YAF2 axis

BACKGROUND

Our previous studies have shown that salidroside (Sal) exerted a protective effect in severe acute pancreatitis (SAP) via inhibiting the inflammatory response. However, the molecular mechanism has not been fully elucidated.

METHODS

Using SAP rat model and miRNA microarray, the effect of Sal on miRNA expression profiling was determined and then validated their changes by quantitative Real-time PCR (qRT-PCR). Then, SAP cell model, enzyme-linked immunosorbent assay (ELISA) and Cell Counting Kit-8 (CCK-8) assay were used to explore the biological function of miR-217-5p in vitro. Bioinformatics analysis, luciferase reporter assay and miRNA pulldown assay were performed to investigate the underlying mechanism of miR-217-5p in the protection of Sal against SAP.

RESULTS

Compared with SAP group, 21 differentially expressed miRNAs were identified in SAP + Sal group. The target genes of these miRNAs were strongly associated with regulation of transcription, Axon guidance, Pathways in cancer and MAPK signaling pathway. Among these miRNAs, miR-217-5p was the most downregulated miRNA. Sal treatment alleviated cell injury and reduced the production of pro-inflammatory cytokines. Whereas overexpression of miR-217-5p reversed the effects of Sal. We identified YY1 associated factor 2 (YAF2) as a direct target gene of miR-217-5p and Sal treatment could upregulate YAF2 expression via targeting miR-217-5p. Furthermore, knockdown of YAF2 counteracted Sal-induced alleviation of cell injury and inflammation. Moreover, Sal could suppress the activation of p38 MAPK pathway by regulating miR-217-5p/YAF2 axis.

CONCLUSIONS

Our findings for the first time highlighted that Sal alleviated pancreatic injury and inhibited inflammation by regulating miR-217-5p/YAF2 axis, which might provide new therapeutic strategies for SAP treatment.

Circular RNA MELK Promotes Chondrocyte Apoptosis and Inhibits Autophagy in Osteoarthritis by Regulating MYD88/NF-κB Signaling Axis through MicroRNA-497-5p

Osteoarthritis (OA) is a rheumatic disease and its pathogenesis involves the dysregulation of noncoding RNAs. Therefore, the regulatory mechanism of circular RNA MELK (circMELK) was specified in this work. OA human cartilage tissue was collected, and circMELK, miR-497-5p, and myeloid differentiation factor 88 (MYD88) expression were examined. Human chondrocytes were stimulated with interleukin- (IL-) 1β and interfered with vectors altering circMELK, miR-497-5p, and MyD88 expression to observe their effects on cell viability, cell cycle and apoptosis, autophagy, and inflammation. The binding relationship between RNAs was verified. The data presented that OA cartilage tissues presented raised circMELK and MYD88 and inhibited miR-497-5p expression. IL-1β suppressed cell viability, prevented cell cycle, and induced apoptosis, autophagy, and inflammation of chondrocytes. Functionally, IL-1β-induced changes of chondrocytes could be attenuated by suppressing circMELK or overexpressing miR-497-5p. circMELK acted as a sponge of miR-497-5p while miR-497-5p was a regulator of MYD88. MYD88 restricted the effect of overexpressing miR-497-5p on IL-1β-stimulated chondrocytes. MYD88 triggered nuclear factor-kappaB (NF-κB) pathway activation. Shortly, CircMELK promotes chondrocyte apoptosis and inhibits autophagy in OA by regulating MYD88/NF-κB signaling axis through miR-497-5p. Our study proposes a new molecular mechanism for the development of OA.