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| Study on the Regulatory Mechanism of Macrophage-Derived Exosomes on GSDMD-Mediated Pyroptosis in Rats with Osteomyelitis |
| CHAI Hao, XU Bin, TAYIERJIANG Yasheng |
| The Sixth Affiliated Hospital, Xinjiang Medical University, Xinjiang Urumqi 830002, China |
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Abstract Objective: To explore the regulatory effects of macrophage-derived exosomes (Exo) on gasdermin D (GSDMD)-mediated pyroptosis in osteomyelitis (OM) rats. Methods: Macrophage-derived exosomes were isolated and characterized using transmission electron microscopy, nanoparticle tracking analysis, and Western blot to detect exosomal markers cluster of differentiation (CD) 9, CD63, and tumor susceptibility gene 101 (TSG101) proteins. Additionally, 48 adult male SD rats were randomly divided into four groups: normal control (NC) group with no treatment; OM group, where an osteomyelitis rat model was established; macrophage exosome treatment group (OM+Exo group), where macrophage-derived exosomes were administered to the OM model; and macrophage exosome combined with GSDMD inhibitor LDC7559 treatment group (OM+Exo+LDC7559 group), where LDC7559 was administered in addition to macrophage-derived exosomes, with n=12 rats per group. Changes in bone tissue pathological damage scores in osteomyelitis rats were observed. Western blot was used to detect the expression levels of pyroptosis marker proteins [activated caspase-1, NLR Family Pyrin Domain Containing 3 (NLRP3), interleukin (IL)-1β, IL-18, GSDMD] and inflammatory cytokines tumor necrosis factor-alpha (TNF-α), IL-6, IL-10. Enzyme-linked immunosorbent assay (ELISA) was used to measure oxidative stress indicators malondialdehyde (MDA) and superoxide dismutase (SOD) levels in bone tissue. Results: Transmission electron microscopy characterization showed that macrophage-derived exosomes are spherical vesicles with a particle size of (42.53~151.65) nm and a Zeta potential of (-29.36±4.08) mV, and they prominently express CD9, CD63, and TSG101. Compared to the NC group, the OM group showed significantly higher bone tissue damage scores, activated caspase-1, NLRP3, IL-1β, IL-18, GSDMD protein expression, TNF-α, IL-6 protein expression, and MDA levels, with significantly lower IL-10 protein expression and SOD levels (all P<0.05). Compared to the OM group, the OM+Exo group showed significant downregulation of these indicators, with significant upregulation of IL-10 protein expression and SOD levels (all P<0.05). Compared to the OM+Exo group, the OM+Exo+LDC7559 group showed further downregulation of these indicators and further upregulation of IL-10 protein expression and SOD levels (all P<0.05). Conclusion: Macrophage-derived exosomes alleviate bone tissue damage in osteomyelitis rats by downregulating GSDMD-mediated pyroptosis and inflammatory cytokine expression, and by mitigating oxidative stress response, indicating their potential value in osteomyelitis treatment.
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2025, Vol. 31 
