Department of Spine Surgery, Third Xiangya Hospital of Central South University, Changsha, China.
Department of Orthopedics and Traumatology, Hunan Chest Hospital, Changsha, China.
Acta Neurobiol Exp (Wars). 2022;82(1):65-76. doi: 10.55782/ane-2022-006.
Microglia is activated and polarized to pro‑inflammatory M1 phenotype or anti‑inflammatory M2 phenotype in neuroinflammation. Apelin‑13 exerts protective properties against neuroinflammation in several neurological disorders. We aimed to investigate whether apelin‑13 played a protective role on BV‑2 microglia and explore its underlying mechanisms. Lipopolysaccharide (LPS)‑stimulated BV‑2 microglia cells were treated with apelin‑13. Microglia activation was evaluated by immunofluorescence with F‑actin. Western blot was performed to measure the expression of autophagy associated proteins. CD16/32 and CD206 were detected to assess microglia polarization by western blot and flow cytometry. qRT‑PCR was utilized to measure inducible nitric oxide synthase (iNOS), arginase‑1 (Arg‑1), interleukin‑10 (IL‑10), interleukin‑6 (IL‑6) and tumor necrosis factor‑alpha (TNF‑α). Histone H3 acetyl lysine 9 (H3K9ac) enrichment of TNF‑α and IL‑6 promoter was detected by ChIP. We discovered that apelin‑13 impacted the actin cytoskeleton, recovering the control phenotype following LPS exposure. Apelin‑13 improved autophagy‑mediated microglia polarization towards M2 phenotype to alleviate inflammatory response in LPS‑stimulated cells. Autophagy flux inhibitor chloroquine antagonized these effects of apelin‑13 on LPS‑stimulated cells. Besides, apelin‑13 decreased the enrichment of H3K9ac at the promoter region of TNF‑α and IL‑6 to inhibit inflammatory response, which was reversed by histone deacetylase antagonist valproate. Taken together, apelin‑13 alleviated inflammation via facilitating microglia M2 polarization due to autophagy promotion, and inhibiting H3K9ac enrichment on promoter regions of TNF‑α and IL‑6.
小胶质细胞在神经炎症中被激活并极化为促炎 M1 表型或抗炎 M2 表型。Apelin-13 在几种神经疾病中对神经炎症发挥保护作用。我们旨在研究 Apelin-13 是否对 BV-2 小胶质细胞发挥保护作用，并探讨其潜在机制。用脂多糖（LPS）刺激 BV-2 小胶质细胞，用 Apelin-13 处理。用 F-肌动蛋白的免疫荧光评估小胶质细胞的激活。通过 Western blot 测定自噬相关蛋白的表达。通过 Western blot 和流式细胞术检测 CD16/32 和 CD206 来评估小胶质细胞极化。qRT-PCR 用于测量诱导型一氧化氮合酶（iNOS）、精氨酸酶-1（Arg-1）、白细胞介素-10（IL-10）、白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）。通过 ChIP 检测 TNF-α 和 IL-6 启动子的组蛋白 H3 乙酰赖氨酸 9（H3K9ac）富集。我们发现 Apelin-13 影响肌动蛋白细胞骨架，在 LPS 暴露后恢复对照表型。Apelin-13 通过促进小胶质细胞向 M2 表型极化改善自噬介导的小胶质细胞极化，从而减轻 LPS 刺激细胞的炎症反应。自噬流抑制剂氯喹拮抗 Apelin-13 对 LPS 刺激细胞的这些作用。此外，Apelin-13 减少 TNF-α 和 IL-6 启动子区域的 H3K9ac 富集，以抑制炎症反应，这一反应被组蛋白去乙酰化酶拮抗剂丙戊酸逆转。总之，Apelin-13 通过促进自噬来减轻炎症，从而促进小胶质细胞 M2 极化，并抑制 TNF-α 和 IL-6 启动子区域的 H3K9ac 富集。
