MMP-10 Deficiency Effects Differentiation and Death of Chondrocytes Associated with Endochondral Osteogenesis in an Endemic Osteoarthritis

Reduction reactions dominate the interactions between Mg alloys and cells: Understanding the mechanisms

Magnesium (Mg) alloys are popular biodegradable metals studied for orthopedic and cardiovascular applications, mainly because Mg ions are essential trace elements known to promote angiogenesis and osteogenesis. However, Mg corrosion consists of oxidation and reduction reactions that produce by-products, such as hydrogen gas, reactive oxygen species, and hydroxides. It is still unclear how all these by-products and Mg ions concomitantly alter the microenvironment and cell behaviors spatially and temporally. This study shows that Mg corrosion can enhance cell proliferation by reducing intracellular ROS. However, Mg cannot decrease ROS and promote cell proliferation in simulated inflammatory conditions, meaning the microenvironment is critical. Furthermore, cells may respond to Mg ions differently in chronic or acute alkaline pH or oxidative stress. Depending on the corrosion rate, Mg modulates HIF1α and many signaling pathways like PI3K/AKT/mTOR, mitophagy, cell cycle, and oxidative phosphorylation. Therefore, this study provides a fundamental insight into the importance of reduction reactions in Mg alloys.

Downregulation of HSP47 Triggers ER Stress-mediated Apoptosis of Hypertrophic Chondrocytes Contributing to T-2 toxin-induced Cartilage Damage

T-2 toxin contamination in food and feed is a growing global concern, with its toxic effects on developing cartilage remaining poorly understood. In this study, we constructed an animal model using 4-week-old male Sprague-Dawley rats, which were administered T-2 toxin (200 ng/g body weight per day) by gavage for one month. Histological analysis showed a significant reduction in hypertrophic chondrocytes and increased caspase-3 expression and TUNEL staining in the deep cartilage zone of T-2 toxin-treated rats. T-2 toxin exposure significantly decreased the expression of heat shock protein 47 (HSP47) and elevated ER stress-mediated apoptosis markers (BiP, caspase-12, and CHOP) in the cartilage of T-2 toxin-treated rats. In an in vitro hypertrophic ATDC5 chondrocyte model, T-2 toxin exposure (10, 25, 50 ng/mL) reduced cell viability and HSP47 expression, while increasing the expression of BiP, caspase-12, and CHOP. Treatment with the ER stress inhibitor Salubrinal suppressed the upregulation of caspase-3 activity, BiP, caspase-12, and CHOP while partially restoring HSP47 expression in T-2 toxin-treated hypertrophic ATDC5 chondrocytes. Furthermore, Hsp47 knockdown in hypertrophic ATDC5 chondrocytes increased the apoptosis ratio, caspase-3 activity, and the expression of BiP, caspase-12, and CHOP. In children with Kashin-Beck disease, a human condition associated with T-2 toxin exposure, reduced HSP47 expression and increased BiP and CHOP expression were observed in the deep zone of articular cartilage. These findings demonstrated that T-2 toxin-induced cartilage damage primarily involves hypertrophic chondrocyte apoptosis in the deep zone. Downregulation of HSP47 leads to ER stress-mediated apoptosis in T-2 toxin-induced cartilage damage. Inhibition of ER stress offers a potential therapeutic approach for mitigating T-2 toxin-induced cartilage damage.

Caspase-12 affects chondrogenesis in mice

Caspase-12 is a molecule whose functions are still not well understood. Although its expression has been found in various tissues, specific roles have been described in only a few cases. These include the effect of caspase-12 on murine bone cell differentiation during craniofacial development. This work focused on the development of the limbs taking place through endochondral ossification, which precedes the formation of the cartilaginous growth plate. Caspase-12 was described here for the first time in growth plate chondrocytes during physiological development. Using pharmacological inhibition, caspase-12 was found to affect chondrogenesis. Limb-derived micromass cultures showed a significantly increased area of chondrogenic nodules after caspase-12 inhibition and there were changes in gene expression, the most significant of which was the reduction of Mmp9. These data point to potential new functions of caspase-12 in chondrogenesis.

Effective protective agents against the organ toxicity of T-2 toxin and corresponding detoxification mechanisms: A narrative review

T-2 toxin is one of the most widespread and toxic fungal toxins in food and feed. It can cause gastrointestinal toxicity, hepatotoxicity, immunotoxicity, reproductive toxicity, neurotoxicity, and nephrotoxicity in humans and animals. T-2 toxin is physicochemically stable and does not readily degrade during food and feed processing. Therefore, suppressing T-2 toxin-induced organ toxicity through antidotes is an urgent issue. Protective agents against the organ toxicity of T-2 toxin have been recorded widely in the literature, but these protective agents and their molecular mechanisms of detoxification have not been comprehensively summarized. In this review, we provide an overview of the various protective agents to T-2 toxin and the molecular mechanisms underlying the detoxification effects. Targeting appropriate targets to antagonize T-2 toxin toxicity is also an important option. This review will provide essential guidance and strategies for the better application and development of T-2 toxin antidotes specific for organ toxicity in the future.

ATAC-seq reveals the roles of chromatin accessibility in the chondrocytes of Kashin-Beck disease compared with primary osteoarthritis

Objective: This study aimed to investigate the roles of accessible chromatin in understanding the different pathogeneses between Kashin-Beck disease (KBD) and primary osteoarthritis (OA). Methods: Articular cartilages of KBD and OA patients were collected, and after tissue digestion, primary chondrocytes were cultured in vitro. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) was performed to compare the accessible chromatin differences of chondrocytes between KBD and OA groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were executed for the promoter genes. Then, the IntAct online database was used to generate networks of significant genes. Finally, we overlapped the analysis of differentially accessible region (DAR)-associated genes and differentially expressed genes (DEGs) obtained from whole-genomic microarray. Results: We obtained 2,751 total DARs, which contained 1,985 loss and 856 gain DARs and belonged to 11 location distributions. We obtained 218 motifs associated with loss DARs, 71 motifs associated with gain DARs, 30 motif enrichments of loss DARs, and 30 motif enrichments of gain DARs. In total, 1,749 genes are associated with loss DARs, and 826 genes are associated with gain DARs. Among them, 210 promoter genes are associated with loss DARs, and 112 promoter genes are associated with gain DARs. We obtained 15 terms of GO enrichment and 5 terms of KEGG pathway enrichment from loss DAR promoter genes, and 15 terms of GO enrichment and 3 terms of KEGG pathway enrichment from gain DAR promoter genes. We obtained CAPN6 and other 2 overlap genes from loss DARs-vs-down DEGs, AMOTL1 from gain DARs-vs-down DEGs, EBF3 and other 12 overlap genes from loss DARs-vs-up DEGs, and ADARB1 and other 10 overlap genes from 101 gain DARs-vs-up DEGs. These overlap genes were built into 4 gene interaction networks. Conclusion: FGF7, GPD1L, NFIB, RUNX2, and VCAM1 were the overlapped genes from the DAR-associated genes and DEGs. These genes were associated with the abnormal chondrocyte function, which may play crucial roles in different processes between KBD and OA in the way of accessible chromatin.