Interferon-gamma (IFN-γ) signaling is necessary for the proinflammatory activation of macrophages but IFN-γ-independent pathways, for which the initiating stimuli and downstream mechanisms are lesser known, also contribute. Here we identify, by high-content screening, SEPTIN2 (SEPT2) as a negative regulation of IFN-γ-independent macrophage autoactivation. Mechanistically, endoplasmic reticulum (ER) stress induces the expression of SEPT2, which balances the competition between acetylation and ubiquitination of heat shock protein 5 at position Lysine 327, thereby alleviating ER stress and constraining M1-like polarization and proinflammatory cytokine release. Disruption of this negative feedback regulation leads to the accumulation of unfolded proteins, resulting in accelerated M1-like polarization, excessive inflammation and tissue damage. Our study thus uncovers an IFN-γ-independent macrophage proinflammatory autoactivation pathway and suggests that SEPT2 may play a role in the prevention or resolution of inflammation during infection.

干扰素-γ (IFN-γ) 信号传导对于巨噬细胞的促炎激活是必需的，但 IFN-γ 独立途径（其起始刺激和下游机制知之甚少）也有贡献。在这里，我们通过高内涵筛选，鉴定出 SEPTIN2 (SEPT2) 作为 IFN-γ 独立巨噬细胞自动激活的负调节。从机制上讲，内质网（ER）应激诱导SEPT2的表达，SEPT2平衡热休克蛋白5赖氨酸327位的乙酰化和泛素化之间的竞争，从而减轻ER应激并限制M1样极化和促炎细胞因子释放。这种负反馈调节的破坏会导致未折叠蛋白的积累，从而导致 M1 样极化加速、过度炎症和组织损伤。因此，我们的研究揭示了一种不依赖于 IFN-γ 的巨噬细胞促炎自激活途径，并表明 SEPT2 可能在感染期间预防或解决炎症中发挥作用。