Department of Neurosurgery, the Affiliated Hospital of Guizhou Medical University, Guiyang, China.
Department of Neurosurgery, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
Front Immunol. 2023 May 8;14:1158758. doi: 10.3389/fimmu.2023.1158758. eCollection 2023.
Macrophage infiltration and polarization are crucial for the pathogenesis of intracranial aneurysm (IA) rupture. Axl, a receptor tyrosine kinase, is involved in inflammation and efferocytosis in multiple organs. Upregulated soluble Axl in cerebrospinal fluid (CSF) and plasma is correlated with intracranial aneurysm rupture. This study aimed to investigate the role of Axl in IA rupture and macrophage polarization.
Male C57BL/6J mice were used to induce IA. The level of Axl from control vessels and unruptured and ruptured IA samples was detected. In addition, the relationship between Axl and macrophages was confirmed. The pathway of Axl-mediated macrophage polarization was explored after IA induction and in bone marrow-derived macrophages (BMDMs) stimulated by LPS/IFN-γ . The animals were randomized into three groups and treated intraperitoneally with the vehicle, selective AXL antagonist R428, and recombinant mouse growth arrest-specific 6 (rmGas6) for 21 consecutive days. Then, we evaluated the influence of Axl on IA rupture by administrating R428 to inhibit or rmGas6 to activate the Axl receptor .
Compared with that in normal vessels, Axl expression was significantly upregulated in unruptured IA samples. The ruptured IA tissue exhibited significantly higher expression of Axl than the unruptured IA tissue. Axl and F4/80 were coexpressed in IA tissue and LPS/IFN-γ-stimulated BMDMs. R428 treatment significantly reduced the rate of M1-like macrophage infiltration and IA rupture. In contrast, rmGas6 treatment promoted M1 macrophage infiltration and IA rupture. Mechanistically, R428 inhibited the phosphorylation of Axl and STAT1 and the expression of hypoxia-inducible factor-1α (HIF-1α) and decreased the levels of IL-1β, NOS2, and MMP9 in LPS/IFN-γ-stimulated BMDMs. rmGas6 promoted the phosphorylation of Axl and STAT1 and the expression of HIF-1α. In addition, STAT1 knockdown abolished Axl-mediated M1 macrophage polarization.
The inhibition of Axl reduced macrophage polarization toward the M1 phenotype the STAT1/HIF-1α signaling pathway and prevented IA rupture in mice. This finding suggests that pharmacological inhibition of Axl might be used to prevent the progression and rupture of IA.
巨噬细胞浸润和极化对于颅内动脉瘤（IA）破裂的发病机制至关重要。受体酪氨酸激酶 Axl 参与多个器官的炎症和吞噬作用。脑脊液（CSF）和血浆中可溶性 Axl 的上调与颅内动脉瘤破裂有关。本研究旨在探讨 Axl 在 IA 破裂和巨噬细胞极化中的作用。
雄性 C57BL/6J 小鼠用于诱导 IA。检测对照血管、未破裂和破裂的 IA 样本中的 Axl 水平。此外，还证实了 Axl 与巨噬细胞之间的关系。在 IA 诱导后和 LPS/IFN-γ 刺激的骨髓来源巨噬细胞（BMDMs）中探索了 Axl 介导的巨噬细胞极化途径。动物随机分为三组，连续 21 天腹腔内给予载体、选择性 AXL 拮抗剂 R428 和重组小鼠生长停滞特异性 6（rmGas6）。然后，我们通过给予 R428 抑制 Axl 或给予 rmGas6 激活 Axl 受体来评估 Axl 对 IA 破裂的影响。
与正常血管相比，未破裂的 IA 样本中 Axl 表达明显上调。破裂的 IA 组织中 Axl 的表达明显高于未破裂的 IA 组织。Axl 和 F4/80 在 IA 组织和 LPS/IFN-γ 刺激的 BMDMs 中共表达。R428 治疗显著降低了 M1 样巨噬细胞浸润和 IA 破裂的发生率。相比之下，rmGas6 处理促进了 M1 巨噬细胞浸润和 IA 破裂。在机制上，R428 抑制了 Axl 和 STAT1 的磷酸化以及缺氧诱导因子-1α（HIF-1α）的表达，并降低了 LPS/IFN-γ 刺激的 BMDMs 中 IL-1β、NOS2 和 MMP9 的水平。rmGas6 促进了 Axl 和 STAT1 的磷酸化以及 HIF-1α 的表达。此外，STAT1 敲低消除了 Axl 介导的 M1 巨噬细胞极化。
Axl 的抑制减少了巨噬细胞向 M1 表型的极化——通过 STAT1/HIF-1α 信号通路，并防止了小鼠的 IA 破裂。这一发现表明，药理学抑制 Axl 可能用于预防 IA 的进展和破裂。
