Chronic manganese (Mn) exposure can lead to manganism, a neurological disorder sharing common symptoms with Parkinson's disease (PD). Studies have shown that Mn can increase the expression and activity of leucine-rich repeat kinase 2 (LRRK2), leading to inflammation and toxicity in microglia. LRRK2 G2019S mutation also elevates LRRK2 kinase activity. Thus, we tested if Mn-increased microglial LRRK2 kinase is responsible for Mn-induced toxicity, and exacerbated by G2019S mutation, using WT and LRRK2 G2019S knock-in mice and BV2 microglia. Mn (30 mg/kg, nostril instillation, daily for 3 weeks) caused motor deficits, cognitive impairments, and dopaminergic dysfunction in WT mice, which were exacerbated in G2019S mice. Mn induced proapoptotic Bax, NLRP3 inflammasome, IL-1β, and TNF-α in the striatum and midbrain of WT mice, and these effects were more pronounced in G2019S mice. BV2 microglia were transfected with human LRRK2 WT or G2019S, followed by Mn (250 μM) exposure to better characterize its mechanistic action. Mn increased TNF-α, IL-1β, and NLRP3 inflammasome activation in BV2 cells expressing WT LRRK2, which was elevated further in G2019S-expressing cells, while pharmacological inhibition of LRRK2 mitigated these effects in both genotypes. Moreover, the media from Mn-treated G2019S-expressing BV2 microglia caused greater toxicity to the cath.a-differentiated (CAD) neuronal cells compared to media from microglia expressing WT. Mn-LRRK2 activated RAB10 which was exacerbated in G2019S. RAB10 played a critical role in LRRK2-mediated Mn toxicity by dysregulating the autophagy-lysosome pathway and NLRP3 inflammasome in microglia. Our novel findings suggest that microglial LRRK2 via RAB10 plays a critical role in Mn-induced neuroinflammation.

长期接触锰 (Mn) 会导致锰中毒，这是一种与帕金森病 (PD) 具有共同症状的神经系统疾病。研究表明，Mn 可以增加富含亮氨酸重复激酶 2 (LRRK2) 的表达和活性，导致小胶质细胞炎症和毒性。LRRK2 G2019S 突变也会提高 LRRK2 激酶活性。因此，我们使用 WT 和 LRRK2 G2019S 敲入小鼠和 BV2 小胶质细胞测试了 Mn 增加的小胶质细胞 LRRK2 激酶是否负责 Mn 诱导的毒性，并因 G2019S 突变而加剧。Mn（30 mg/kg，鼻孔滴注，每天一次，持续 3 周）会导致 WT 小鼠运动缺陷、认知障碍和多巴胺能功能障碍，在 G2019S 小鼠中加剧。Mn 诱导 WT 小鼠纹状体和中脑中的促凋亡 Bax、NLRP3 炎性体、IL-1β 和 TNF-α，这些作用在 G2019S 小鼠中更为明显。BV2 小胶质细胞用人 LRRK2 WT 或 G2019S 转染，然后暴露于 Mn (250 μM)，以更好地表征其机制作用。Mn 增加表达 WT LRRK2 的 BV2 细胞中 TNF-α、IL-1β 和 NLRP3 炎症小体的激活，在表达 G2019S 的细胞中进一步升高，而 LRRK2 的药理学抑制可减轻这两种基因型的这些影响。此外，与来自表达WT的小胶质细胞的培养基相比，来自经Mn处理的表达G2019S的BV2小胶质细胞的培养基对导管分化(CAD)神经元细胞造成更大的毒性。Mn-LRRK2 激活 RAB10，并在 G2019S 中加剧。RAB10 通过调节小胶质细胞中的自噬-溶酶体途径和 NLRP3 炎性体，在 LRRK2 介导的锰毒性中发挥关键作用。我们的新发现表明，小胶质细胞 LRRK2通过RAB10 在锰诱导的神经炎症中发挥着关键作用。