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This study focuses on the inflammatory regulatory mechanism of ectopic bone formation, using a mouse model induced by trauma/burns as the subject, to explore the role of macrophage-driven inflammation in the disease process and the molecular regulatory mechanism. The study confirmed that protein arginine methyltransferase 6 (PRMT6) is the core epigenetic amplifier driving inflammation by macrophages, and it upregulates the expression of chemokine CCL2, linking the early injury response with ectopic bone formation, providing a new perspective for understanding the pathogenic mechanism of ectopic bone formation.
This review addresses the regeneration and repair challenges caused by the heterogeneity of bone-cartilage tissue, with a tissue engineering system combining mesenchymal stem cells and biomaterial scaffolds as the core, clarifying the regulatory mechanism of biological physical signals on stem cell fate, systematically summarizing the progress in the design of biomimetic microenvironment scaffolds under mechanical biology guidance, achieving precise regulation of the lineage-specific differentiation of mesenchymal stem cells, and providing theoretical support and design references for layered bone-cartilage regeneration, especially for the regeneration and repair of subchondral bone.
01 Research Background
Ectopic bone formation is a disabling disease characterized by abnormal bone formation in soft tissues, mostly induced by inflammation after trauma. The inflammatory response driven by macrophages plays a key role in the pathogenesis of ectopic bone formation, but the molecular mechanism of its initiation, amplification, and resolution remains unclear, which limits the in-depth understanding of the pathological essence of this disease.
The transitional bone tissue has a highly specialized extracellular matrix structure, with the core feature being the hierarchical arrangement of collagen and the gradient composition of minerals. This structural system can achieve stable force transmission and guide the cell phenotype of spatial organization. Currently, it is impossible to precisely reproduce the complex multi-scale structure and composition gradient at the tendon-bone interface, which has become a key bottleneck hindering the integration regeneration of soft and hard tissues. It is urgently needed to develop biomimetic matrix construction schemes that conform to the natural structure characteristics.
02 Main Content
This study focuses on the regulatory role of PRMT6 in the inflammatory response driven by macrophages and ectopic bone formation, systematically analyzing the expression changes, functional effects, and molecular regulatory pathways of PRMT6:
1. The expression characteristics of PRMT6 in macrophages after injury and its impact on ectopic bone formation;
2. The mechanism by which PRMT6 regulates the expression of chemokine CCL2 to affect the accumulation and migration of macrophages;
3. The core role of PRMT6-mediated epigenetic modification in the amplification of inflammation and ectopic bone formation.
03 Research Design
1. Animal model construction: Using a mouse model of ectopic bone formation induced by trauma/burns to simulate the disease occurrence process;
2. Gene screening and verification: Through transcriptome analysis, screening for differentially expressed genes in macrophages after injury, and identifying PRMT6 as a key candidate factor;
3. Functional intervention experiments: Using genetic deletion, macrophage-targeted knockdown, and drug inhibition methods to intervene in the expression or activity of PRMT6, observing its effects on macrophage accumulation and ectopic bone formation;
4. Downstream mechanism verification: Through macrophage depletion, CCL2 gene knockout, and supplementation experiments, verifying the role of CCL2 as a key factor downstream of PRMT6;
5. Molecular mechanism analysis: From transcriptional and epigenetic levels, analyzing the interaction between PRMT6 and NF-κB and the modification regulation of the Ccl2 promoter.
04 Results
1. In the early stage of injury, the injury site of ectopic bone formation model mice showed rapid and continuous accumulation of macrophages, and macrophage depletion could significantly inhibit the formation of ectopic bone formation;
2. Transcriptome analysis showed that the expression of PRMT6 in macrophages after injury was significantly upregulated; genetic deletion or macrophage-targeted knockdown of Prmt6 could reduce macrophage accumulation and significantly weaken ectopic bone formation, and did not damage the tendon repair process; 3. Drug inhibition of PRMT6 activity can effectively suppress ectopic ossification only when intervention is carried out during the early inflammatory stage, suggesting that its effect is time-specific;
4. Mechanistically, PRMT6 upregulates CCL2 expression through transcriptional and epigenetic pathways, enhancing the chemotactic signal transduction of macrophages; genetic disruption of CCL2 derived from macrophages can eliminate the phenotypes regulated by PRMT6, while supplementing CCL2 can rescue macrophage recruitment in Prmt6-deficient mice and partially restore ectopic ossification;
5. At the molecular level, PRMT6 forms a co-activating complex with NF-κB, catalyzing asymmetric dimethylation of H3R17 in the Ccl2 promoter region, thereby promoting the continuous expression of chemokines and achieving the amplification of the inflammatory response;
05 Extension of ideas
1. Further exploration of downstream targets of PRMT6 epigenetic regulation can improve the early inflammatory regulatory network of ectopic ossification;
2. Investigating the function of PRMT6 in other inflammation-related bone metabolic diseases can expand its research scope in the field of bone diseases;
3. Deeply analyzing the interaction mechanism between macrophage inflammation and abnormal bone formation can provide new directions for the pathological study of bone diseases;
4. Studying the regulatory differences of PRMT6-mediated epigenetic modifications in different bone microenvironments can enrich the epigenetic regulation theory of bone metabolism.
