Reduction of Matrix Metallopeptidase 13 and Promotion of Chondrogenesis by Zeel T in Primary Human Osteoarthritic Chondrocytes

UGDH Lactylation Aggravates Osteoarthritis by Suppressing Glycosaminoglycan Synthesis and Orchestrating Nucleocytoplasmic Transport to Activate MAPK Signaling

Osteoarthritis (OA) progression is closely related to dysregulated glycolysis. As the primary metabolite of glycolysis, lactate plays a detrimental role in OA. However, how lactate exacerbates OA process remains unclear. Here, this study revealed that lactate levels are elevated in the synovial fluid of OA patients and IL-1β-treated human primary chondrocytes, promoting protein pan-lactylation. Functionally, hyper-lactylation exacerbates chondrocytes extracellular matrix (ECM) degradation and cell apoptosis in vitro and in vivo. Moreover, UDP-glucose dehydrogenase (UGDH) is proven to be the key lactylated protein in lactate-treated chondrocytes, which undergoes lactylation at lysine 6 (K6). Lactylated UGDH repressed its enzymatic activity, reducing glycosaminoglycan synthesis and disregulating its nuclear-cytoplasmic distribution. Mechanistically, K6 lactylation of UGDH impedes the interaction of UGDH and signal transducer and activator of transcription 1 (STAT1), thus promoting the transcription of mitogen-activated protein kinase kinase kinase 8 (MAP3K8) and activating the MAPK signaling pathway. Importantly, in vitro and in vivo treatment with A485, a specific acyltransferase P300 inhibitor, suppressed UGDH lactylation and rescued chondrocytes ECM degradation and OA progression. These findings uncover a new mechanism underlying OA pathogenesis and highlight the potential of targeting UGDH lactylation as a novel therapeutic strategy for OA.

The multifunctional protein CCN1/CYR61: Bridging physiology and disease

The matricellular protein CYR61/CCN1 is a member of the CCN protein family that plays significant roles in a broad range of physiological processes, including development, tissue repair, and inflammation, among others. CCN1 is also implicated in pathological conditions such as cancer and fibrosis. The diverse functions of CCN1 arise from its ability to bind different receptors located on many cell types, thereby activating diverse signaling pathways. The diverse, yet contradictory, functions mediated by CCN1 makes it a compelling target for investigation, as it offers the prospect of understanding fundamental cellular topics and their possible implications in various diseases. Recently, new cellular functions were attributed to CCN1, including senescence, pro-/anti- fibrosis, and rejuvenation. In this review, we discuss all these new findings along with the basic knowledge about CCN1 to provide an overall understanding of its conflicting roles and their potential corresponding mechanisms of action.

Systems biology-based analysis exploring shared biomarkers and pathogenesis of myocardial infarction combined with osteoarthritis

Background

More and more evidence supports the association between myocardial infarction (MI) and osteoarthritis (OA). The purpose of this study is to explore the shared biomarkers and pathogenesis of MI complicated with OA by systems biology.

Methods

Gene expression profiles of MI and OA were downloaded from the Gene Expression Omnibus (GEO) database. The Weighted Gene Co-Expression Network Analysis (WGCNA) and differentially expressed genes (DEGs) analysis were used to identify the common DEGs. The shared genes related to diseases were screened by three public databases, and the protein-protein interaction (PPI) network was built. GO and KEGG enrichment analyses were performed on the two parts of the genes respectively. The hub genes were intersected and verified by Least absolute shrinkage and selection operator (LASSO) analysis, receiver operating characteristic (ROC) curves, and single-cell RNA sequencing analysis. Finally, the hub genes differentially expressed in primary cardiomyocytes and chondrocytes were verified by RT-qPCR. The immune cell infiltration analysis, subtypes analysis, and transcription factors (TFs) prediction were carried out.

Results

In this study, 23 common DEGs were obtained by WGCNA and DEGs analysis. In addition, 199 common genes were acquired from three public databases by PPI. Inflammation and immunity may be the common pathogenic mechanisms, and the MAPK signaling pathway may play a key role in both disorders. DUSP1, FOS, and THBS1 were identified as shared biomarkers, which is entirely consistent with the results of single-cell RNA sequencing analysis, and furher confirmed by RT-qPCR. Immune infiltration analysis illustrated that many types of immune cells were closely associated with MI and OA. Two potential subtypes were identified in both datasets. Furthermore, FOXC1 may be the crucial TF, and the relationship of TFs-hub genes-immune cells was visualized by the Sankey diagram, which could help discover the pathogenesis between MI and OA.

Conclusion

In summary, this study first revealed 3 (DUSP1, FOS, and THBS1) novel shared biomarkers and signaling pathways underlying both MI and OA. Additionally, immune cells and key TFs related to 3 hub genes were examined to further clarify the regulation mechanism. Our study provides new insights into shared molecular mechanisms between MI and OA.

Effects of 2-carba-cyclic phosphatidic acid derivatives on IL-1β-stimulated human chondrocytes

Osteoarthritis (OA) is a common joint disease characterized by the breakdown of subchondral bone and cartilage damage, most often affecting middle-aged and elderly people. Although the etiology of OA is still unknown, some reports suggest that inflammatory factors such as interleukin (IL)- 1β mediate the progression of OA. To investigate the effect of IL-1β and the possibility of treatment for OA, we applied 2-carba-cyclic phosphatidic acid (2ccPA) and its derivatives on human chondrocytes. 2ccPA is a synthesized phospholipid derived from a bioactive phospholipid mediator: cyclic phosphatidic acid (cPA). It has been previously reported that 2ccPA exhibits anti-inflammatory and chondroprotective effects in an OA animal model. 2ccPA and its ring-opened body (ROB) derivative significantly suppressed IL-1β-induced upregulation of IL-6, matrix metalloproteinase-13, and cyclooxygenase-2, as well as the degradation of type II collagen and aggrecan. However, the other two derivatives, namely the deacylated and ring-opened deacylated bodies, showed little effect on an IL-1β-exposed human chondrosarcoma cell-line. These data suggest that the intactness of 2ccPA and ROB is essential for anti-inflammatory effects on OA. Collectively, this study provides evidence that 2ccPA and ROB would be novel therapeutic agents for OA.

Curcuma longa and Boswellia serrata Extracts Modulate Different and Complementary Pathways on Human Chondrocytes In Vitro: Deciphering of a Transcriptomic Study

Objectives:Curcuma longa (CL) and Boswellia serrata (BS) extracts are used to relieve osteoarthritis symptoms. The aim of this in vitro study was to investigate their mechanisms of action at therapeutic plasmatic concentrations on primary human osteoarthritic (OA) chondrocytes.

Methods: BS (10–50 μg/ml) and CL (0.4–2 μg/ml corresponding to 1–5 µM of curcumin) were evaluated separately or in combination on primary chondrocytes isolated from 17 OA patients and cultured in alginate beads. Ten patients were used for RNA-sequencing analysis. Proteomic confirmation was performed either by immunoassays in the culture supernatant or by flow cytometry for cell surface markers after 72 h of treatment.

Results: Significant gene expression modifications were already observed after 6 h of treatment at the highest dose of CL (2 μg/ml) while BS was significantly effective only after 24 h of treatment irrespective of the concentration tested. The most over-expressed genes by CL were anti-oxidative, detoxifying, and cytoprotective genes involved in the Nrf2 pathway. Down-regulated genes were principally pro-inflammatory cytokines and chemokines. Inversely, BS anti-oxidant/detoxifying activities were related to the activation of Nrf1 and PPARα pathways. BS anti-inflammatory effects were associated with the increase in GDF15, decrease in cholesterol cell intake and fatty acid metabolism-involved genes, and down-regulation of Toll-like receptors (TLRs) activation. Similar to CL, BS down-regulated ADAMTS1, 5, and MMP3, 13 genes expression. The combination of both CL and BS was significantly more effective than CL or BS alone on many genes such as IL-6, CCL2, ADAMTS1, and 5.

Conclusion: BS and CL have anti-oxidative, anti-inflammatory, and anti-catabolic activities, suggesting a protective effect of these extracts on cartilage. Even if they share some mechanism of action, the two extracts act mainly on distinct pathways, and with different time courses, justifying their association to treat osteoarthritis.