SETDB2通过调控巨噬细胞M2型极化减轻骨关节炎小鼠冷痛敏的机制研究OA

AIM:This study aims to explore the role of SET domain bifurcated histone lysine methyltransfer-ase 2(SETDB2)in the development and progression of cold allodynia in knee osteoarthritis(KOA)and to clarify the un-derlying mechanism through which SETDB2 modulates cold allodynia via the regulation of macrophage M2 polarization in the dorsal root ganglion(DRG).METHODS:A KOA mouse model was induced by destabilizing the medial meniscus(DMM).Myeloid-specific SETDB2 conditional knockout mice were generated using the Cre-loxP system,and an SETDB2 overexpression model was established by intrathecal administration of an AAV-SETDB2 vector.Histopathological changes in knee articular cartilage were assessed by HE staining and safranin O-fast green staining.The expression levels of colla-gen type Ⅱ alpha 1 chain(Col2a1),aggrecan(ACAN),matrix metalloproteinase 3(MMP3)and MMP13 in cartilage,as well as SETDB2,macrophage markers CD86(M1 phenotype)and CD206(M2 phenotype),and cold-sensitive channels transient receptor potential cation channel subfamily M member 8(TRPM8)and transient receptor potential cation chan-nel subfamily A member 1(TRPA1)in DRG tissue,were analyzed by Western blot and RT-qPCR.Nissl staining was used to examine morphological alterations in DRG neurons.Serum levels of inflammatory cytokines interleukin-1β(IL-1β)and IL-6,as well as pain-associated molecules calcitonin gene-related peptide(CGRP)and substance P(SP),were measured by ELISA.Flow cytometry was employed to determine the M2/M1 macrophage ratio in DRG tissue.Cold allo-dynia thresholds were assessed using the acetone evaporation test and the cold plate test.RESULTS:In KOA mice,both protein and mRNA levels of SETDB2 in DRG tissue were significantly reduced(P<0.05).Articular cartilage displayed erosion and destruction,with decreased expression of anabolic markers Col2a1 and ACAN,and increased expression of catabolic markers MMP3 and MMP13.The DRG neurons exhibited blurred and pale Nissl bodies.Macrophage M2 polar-ization in DRG tissue was suppressed.Paw withdrawal latency was significantly shortened(P<0.05).Protein and mRNA expression levels of IL-1β,IL-6,CGRP,SP,TRPM8 and TRPA1 were elevated(P<0.05).These pathological and mo-lecular alterations were further aggravated in myeloid-specific SETDB2 conditional knockout mice,while they were signifi-cantly reversed in SETDB2-overexpressing mice(P<0.05).CONCLUSION:SETDB2 plays a protective role in the on-set and progression of KOA.Its overexpression alleviates cold allodynia in KOA mice by promoting M2 polarization of local DRG macrophages,reducing neuroimmune inflammation,and down-regulating the expression of pain-and cold-sensitivity-related molecules.