Identification of key genes and immune infiltration in osteoarthritis through analysis of zinc metabolism-related genes.

BACKGROUND: Osteoarthritis (OA) represents a prominent etiology of considerable pain and disability, and conventional imaging methods lack sensitivity in diagnosing certain types of OA. Therefore, there is a need to identify highly sensitive and efficient biomarkers for OA diagnosis. Zinc ions feature in the pathogenesis of OA. This work aimed to investugate the role of zinc metabolism-related genes (ZMRGs) in OA and the diagnostic characteristics of key genes. METHODS: We obtained datasets GSE169077 and GSE55235 from the Gene Expression Omnibus (GEO) and obtained ZMRGs from MSigDB. Differential expression analysis was conducted on the GSE169077 dataset using the limma R package to identify differentially expressed genes (DEGs), and the intersection of DEGs and ZMRGs yielded zinc metabolism differential expression-related genes (ZMRGs-DEGs). The clusterProfiler R package was employed for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of ZMRGs-DEGs. Potential small molecule drugs were predicted using the CMap database, and immune cell infiltration and function in OA individuals were analyzed using the ssGSEA method. Protein-protein interaction (PPI) networks were constructed to detect Hub genes among ZMRGs-DEGs. Hub gene expression levels were analyzed in the GSE169077 and GSE55235 datasets, and their diagnostic characteristics were assessed using receiver operating characteristic (ROC) curves. The gene-miRNA interaction network of Hub genes was explored using the gene-miRNA interaction network website. RESULTS: We identified 842 DEGs in the GSE169077 dataset, and their intersection with ZMRGs resulted in 46 ZMRGs-DEGs. ZMRGs-DEGs were primarily enriched in functions such as collagen catabolic processes, extracellular matrix organization, metallopeptidase activity, and pathways like the IL-17 signaling pathway, Nitrogen metabolism, and Relaxin signaling pathway. Ten potential small-molecule drugs were predicted using the CMap database. OA patients exhibited distinct immune cell abundance and function compared to healthy individuals. We identified 4 Hub genes (MMP2, MMP3, MMP9, MMP13) through the PPI network, which were highly expressed in OA and demonstrated good diagnostic performance. Furthermore, two closely related miRNAs for each of the 4 Hub genes were identified. CONCLUSION: 4 Hub genes were identified as potential diagnostic biomarkers and therapeutic targets for OA.

SND1 aggravates mitochondrial damage, apoptosis and extracellular matrix degradation in IL-1ß-stimulated chondrocytes via PINK1/BECN1 pathway.

Recently, evidence has suggested a regulatory role for SND1 in osteoarthritis progression. Interestingly, we found that SND1 protein expression was increased, mitochondria were shrunken and decreased in number, mitochondrial membrane potential was decreased, mitochondrial ROS production was increased, and ATP levels were decreased in IL-1ß treated mouse chondrocytes, and SND1 silencing removed these changes. Furthermore, IL-1ß treatment promoted inflammatory factor secretion in chondrocytes, promoted cell apoptosis, increased MMP13 protein and inhibited collagen II protein expression, and si-SND1 inhibited the IL-1ß effects. We validated the association between SND1 and PINK1 and found that PINK1 reversed the inhibitory effects of SND1 silencing on IL-1ß-induced mitochondrial damage, inflammatory reaction, apoptosis and extracellular matrix degradation in mouse chondrocytes. Furthermore, we found that PINK1 upregulated BECN1 protein expression and that BECN reversed the inhibitory effects of PINK1 silencing on IL-1ß-induced mitochondrial damage, inflammatory reaction, apoptosis and extracellular matrix degradation. Further mechanistic studies revealed that PINK1 inhibited the AMPK/mTOR signaling axis to aggravate IL-1ß induced mouse chondrocytes injury by upregulating BECN1 protein expression. In vivo results showed that the damage to cartilage tissue was significantly alleviated in rats with osteoarthritis by knocking down SND1 expression.

Enhanced efficacy of transforming growth factor-ß1 loaded an injectable cross-linked thiolated chitosan and carboxymethyl cellulose-based hydrogels for cartilage tissue engineering.

Growth factors (GFs) are soluble proteins extracellular that control a wide range of cellular processes as well as tissue regeneration. While transforming growth factor beta-1 (TGF-ß1) promotes chondrogenesis, its medical use is restricted by its potential protein instability, which necessitates high doses of the protein, which can result in adverse side effects such as inefficient cartilage formation. In this work, we have developed a novel hydrogel composite based on the polymer, cross-linked thiolated chitosan; TCS and carboxymethyl cellulose; CMC (TCS/CMC) hydrogel system was utilized as injectable TGF-ß1 carriers for cartilage tissue engineering applications. Rheological measurements showed that the elastic modulus of TCS/CMC hydrogels with an optimized CMC concentration could reach around 2.5 kPa or higher than their respective viscous modulus, indicating that they behaved like strong hydrogels. Crosslinking significantly alters the overall network distribution, surface morphology, pore size, porosity, gelation time, swelling ratio, water content, and in vitro degradation of the TCS/CMC hydrogels. TCS/CMC hydrogels maintain more than 90% of their weight and retain their original form after 21 days. TGF-ß1 released marginally from TCS/CMC hydrogels as incubation time increased, up to 21 days, with around 18.6 ± 0.9% of the drug stored inside the TCS/CMC hydrogels. On day 21, BMSC treated with TGF-ß1 in medium or TGF-ß1-loaded TCS/CMC hydrogels grew faster than the other groups. For in vivo cartilage repair, full-thickness cartilage defects were induced on rat knees for 8 weeks. The optimal ability of this novel TGF-ß1-loaded TCS/CMC hydrogel system was further demonstrated by histological analysis, resulting in a novel therapeutic strategy for repairing articular cartilage defects.