Identification of Biomarkers, Pathways, Immune Properties of Mitophagy Genes, and Prediction Models for Intervertebral Disc Degeneration.

Background: Intervertebral disc degeneration (IDD) is the leading cause of low back pain (LBP). The mechanism of IDD development and progression is not fully understood. Peripheral biomarkers are increasingly vital non-radioactive methods in early detection and diagnosis for IDD. Nevertheless, less attention has been paid to the role of mitophagy genes in the progress of IDD. This study aimed to identify the mitophagy disease-causing genes in the process of IDD and mitophagy diagnostic biomarkers for IDD. Methods: Mitophagy-related differentially expressed genes (MRDEGs) related to IDD were investigated by analyzing the microarray datasets of IDD cases from GEO, PathCards and Molecular Signatures Databases. We used R software, WGCNA, PPI, mRNA-miRNA, mRNA-TF, GO, KEGG, GSEA, GSVA and Cytoscape to analyze and visualize the data. We further used ssGSEA for immunoinfiltration analysis to obtain different immune cell infiltration. LASSO model was developed to screen for genes that met the diagnostic gene model requirements. Finally, qRT-PCR, Western blotting and HE were used to verify hub genes and their expression from clinical IDD samples. Results: We identified 14 MRDEGs and 12 hub genes. GO, KEGG, GSEA and GSVA analyses demonstrated that hub genes were critical for the development of IDD. LASSO diagnostic model consisted of six hub genes, among which SQSTM1, ATG7 and OPTN were significantly different between the two IDD disease subtypes. At the same time, SQSTM1 also had a high correlation with immune characteristic subtypes. The results of qRT-PCR and Western blotting also indicated that these genes were significantly differentially expressed in nucleus pulposus cells (NPCs) of the IDD group. Conclusion: We explored an association between MRDEGs-associated signature in IDD and validated that hub genes like SQSTM1 might serve as biomarkers for diagnostic and therapeutic targets for IDD. Meanwhile, this study can provide new insights into the functional characteristics and mechanism of mitophagy in the development of IDD.

Tumor necrosis factor-α inhibition restores matrix formation by human adipose-derived stem cells in the late stage of chondrogenic differentiation.

BACKGROUND: Cartilage tissue engineering is a promising strategy for treating cartilage damage. Matrix formation by adipose-derived stem cells (ADSCs), which are one type of seed cell used for cartilage tissue engineering, decreases in the late stage of induced chondrogenic differentiation in vitro, which seriously limits research on ADSCs and their application. AIM: To improve the chondrogenic differentiation efficiency of ADSCs in vitro, and optimize the existing chondrogenic induction protocol. METHODS: Tumor necrosis factor-alpha (TNF-α) inhibitor was added to chondrogenic culture medium, and then Western blotting, enzyme linked immunosorbent assay, immunofluorescence and toluidine blue staining were used to detect the cartilage matrix secretion and the expression of key proteins of nuclear factor kappa-B (NF-κB) signaling pathway. RESULTS: In this study, we found that the levels of TNF-α and matrix metalloproteinase 3 were increased during the chondrogenic differentiation of ADSCs. TNF-α then bound to its receptor and activated the NF-κB pathway, leading to a decrease in cartilage matrix synthesis and secretion. Blocking TNF-α with its inhibitors etanercept (1 µg/mL) or infliximab (10 µg/mL) significantly restored matrix formation. CONCLUSION: Therefore, this study developed a combination of ADSC therapy and targeted anti-inflammatory drugs to optimize the chondrogenesis of ADSCs, and this approach could be very beneficial for translating ADSC-based approaches to treat cartilage damage.

Association between Mean Corpuscular Hemoglobin and Platelet Distribution Width Ratio and Knee Osteoarthritis Severity.

BACKGROUND: The goal was to simply and efficiently predict the indicators of disease severity in knee osteoarthritis (KOA) patients. METHODS: One hundred eighty-four patients with KOA and 126 healthy subjects were included. WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) was used as a reference index for disease severity in KOA patients, in which WOMAC < 80 was classified as mild and WOMAC ≥ 80 as moderate and severe. Blood routine parameters of the KOA and the healthy groups were analyzed by the Mann Whitney U test. Receiver operating characteristic curves were used to analyze the sensitivity and specificity of mean corpuscular hemoglobin and platelet distribution width ratio (MPR) and monocyte and hemoglobin ratio (MHR) indicators. The correlation between MPR and MHR and disease severity of KOA was determined by bivariate regression analysis. Independent predictors of disease severity in patients with KOA were assessed by multivariate regression analysis. RESULTS: MPR, MHR, and WOMAC were significantly higher in the KOA group. The ROC curve indicated that the cutoff values of MPR and MHR were 2.09 and 0.0030, respectively, with sensitivity of 86.4% and 68.5% and specificity of 99.2% and 79.4%. Bivariate regression analysis found that MPR was better correlated with disease severity than MHR. The results of multivariate regression analysis demonstrated that the MPR values of moderate and severe patients were more than 19 times that of mild patients, and the OR values were 21.695 and 19.558, respectively. CONCLUSIONS: MPR and MHR demonstrated a good correlation with disease severity in patients with KOA. MPR is a potential independent predictor of disease severity in patients with KOA.

Matrix Metalloproteinase 3: A Promoting and Destabilizing Factor in the Pathogenesis of Disease and Cell Differentiation.

Cells must alter their expression profiles and morphological characteristics but also reshape the extracellular matrix (ECM) to fulfill their functions throughout their lifespan. Matrix metalloproteinase 3 (MMP-3) is a member of the matrix metalloproteinase (MMP) family, which can degrade multiple ECM components. MMP-3 can activate multiple pro-MMPs and thus initiates the MMP-mediated degradation reactions. In this review, we summarized the function of MMP-3 and discussed its effects on biological activities. From this point of view, we emphasized the positive and negative roles of MMP-3 in the pathogenesis of disease and cell differentiation, highlighting that MMP-3 is especially closely involved in the occurrence and development of osteoarthritis. Then, we discussed some pathways that were shown to regulate MMP-3. By writing this review, we hope to provide new topics of interest for researchers and attract more researchers to investigate MMP-3.