Yang Fan, Kong Xiuqin, Hu Yuefeng, Liu Wanzhao, Xie Pengfei, Gu Yuexi, Zhang Yan, Yang Yili, Tang Chuanfeng, Li Jianmei
School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, China; China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou 225316, China.
China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou 225316, China.
J Adv Res. 2025 Aug 26. doi: 10.1016/j.jare.2025.08.050.
Microglial phagocytosis is crucial for maintaining central nervous system (CNS) homeostasis and is implicated in the development of depression. NOD-like receptor family pyrin domain containing 6 (NLRP6) represents a potential target for depression treatment, but underlying mechanisms remain unclear. Bezafibrate has been shown to exhibit multiple neuroprotective effects.
To investigate the effects of NLRP6 on microglial phagocytosis and depressive-like behaviors, elucidate the potential underlying mechanisms, and evaluate bezafibrate's therapeutic impact.
NLRP6 complete gene knockout (Nlrp6-KO), microglia-conditional knockout (Nlrp6-cKO), and chronic restraint stress (CRS) model were established in mice. Behavioral tests (OFT, TST, FST, SPT) were used to assess depressive-like behaviors. Fluorescently labeled cellular debris was stereotactically injected into the hippocampus or co-cultured with the BV2 microglial cell line to assess the microglial phagocytic activity. Underlying mechanisms were investigated using RNA-seq, luciferase assays, flow cytometry, Western blot, qPCR, and ELISA.
Enriched NLRP6 expression in microglia was confirmed by RNAscope experiment. Nlrp6-KO and Nlrp6-cKO mice exhibited significant depressive-like behaviors, accompanied by impaired microglial phagocytic function. In the BV2 cells, NLRP6 regulated phagocytosis of cellular debris by promoting the transactivation of cluster differentiation 36 (CD36). More importantly, corticosterone inhibited NLRP6 and its target gene CD36 expression, thereby reducing microglial phagocytosis. However, bezafibrate treatment restored the NLRP6-CD36 axis, enhanced microglial phagocytosis, and suppressed the inflammatory response to cellular debris in BV2 cells. In CRS mice, bezafibrate alleviated depressive-like behaviors, reversed NLRP6/CD36 downregulation, improved phagocytosis, and reduced hippocampal neuroinflammation. Importantly, bezafibrate failed to alleviate depressive-like behaviors in Nlrp6-KO mice, indicating NLRP6 is essential for its antidepressant effect.
NLRP6 critically regulates microglial phagocytosis via CD36, combating depression. Bezafibrate alleviates stress-induced depressive behaviors and neuroinflammation primarily by enhancing NLRP6-dependent phagocytosis. Thus, NLRP6 represents a promising therapeutic target in hippocampal microglia for maintaining CNS homeostasis and treating depression.
小胶质细胞吞噬作用对于维持中枢神经系统（CNS）的稳态至关重要，并且与抑郁症的发生有关。含吡啉结构域的NOD样受体家族6（NLRP6）是抑郁症治疗的一个潜在靶点，但其潜在机制仍不清楚。苯扎贝特已被证明具有多种神经保护作用。
研究NLRP6对小胶质细胞吞噬作用和抑郁样行为的影响，阐明潜在的机制，并评估苯扎贝特的治疗效果。
在小鼠中建立NLRP6完全基因敲除（Nlrp6-KO）、小胶质细胞条件性敲除（Nlrp6-cKO）和慢性束缚应激（CRS）模型。采用行为学测试（旷场试验、悬尾试验、强迫游泳试验、蔗糖偏好试验）评估抑郁样行为。将荧光标记的细胞碎片立体定向注射到海马中或与BV2小胶质细胞系共培养，以评估小胶质细胞的吞噬活性。使用RNA测序、荧光素酶测定、流式细胞术、蛋白质免疫印迹、定量聚合酶链反应和酶联免疫吸附测定研究潜在机制。
RNAscope实验证实小胶质细胞中NLRP6表达丰富。Nlrp6-KO和Nlrp6-cKO小鼠表现出明显的抑郁样行为，同时伴有小胶质细胞吞噬功能受损。在BV2细胞中，NLRP6通过促进分化簇36（CD36）的反式激活来调节细胞碎片的吞噬作用。更重要的是，皮质酮抑制NLRP6及其靶基因CD36的表达，从而降低小胶质细胞的吞噬作用。然而，苯扎贝特治疗可恢复NLRP6-CD36轴，增强小胶质细胞的吞噬作用，并抑制BV2细胞对细胞碎片的炎症反应。在CRS小鼠中，苯扎贝特减轻了抑郁样行为，逆转了NLRP6/CD36的下调，改善了吞噬作用，并减轻了海马神经炎症。重要的是，苯扎贝特未能减轻Nlrp6-KO小鼠的抑郁样行为，表明NLRP6对其抗抑郁作用至关重要。
NLRP6通过CD36关键地调节小胶质细胞的吞噬作用，对抗抑郁症。苯扎贝特主要通过增强NLRP6依赖性吞噬作用来减轻应激诱导的抑郁行为和神经炎症。因此，NLRP6是海马小胶质细胞中维持CNS稳态和治疗抑郁症的一个有前景的治疗靶点。
