A noncanonical autophagy is involved in the transfer of <i>Plasmodium</i>-microvesicles to astrocytes

Cerebral malaria is a neuroinflammatory disease induced by <i>P. falciparum</i> infection. In animal models, the neuro-pathophysiology of cerebral malaria results from the sequestration of infected red blood cells (iRBCs) in microvessels that promotes the activation of glial cells in the brain. This activation provokes an exacerbated inflammatory response characterized by the secretion of proinflammatory cytokines and chemokines, leading to brain infiltration by pathogenic CD8⁺ T lymphocytes. Astrocytes are a major subtype of brain glial cells that play an important role in maintaining the homeostasis of the central nervous system, the integrity of the brain–blood barrier and in mounting local innate immune responses. We have previously shown that parasitic microvesicles (<i>Pb</i>A-MVs) are transferred from iRBCs to astrocytes. The present study shows that an unconventional LC3-mediated autophagy pathway independent of ULK1 is involved in the transfer and degradation of <i>Pb</i>A-MVs inside the astrocytes. We further demonstrate that inhibition of the autophagy process by treatment with 3-methyladenine blocks the transfer of <i>Pb</i>A-MVs, which remain localized in the astrocytic cell membrane and are not internalized. Moreover, bafilomycin A₁, another drug against autophagy promotes the accumulation of <i>Pb</i>A-MVs inside the astrocytes by inhibiting the fusion with lysosomes, and prevents ECM in mice infected with <i>Pb</i>A. Finally, we establish that RUBCN/rubicon or ATG5 silencing impede astrocyte production in CCL2 and CXCL10 chemokines induced by <i>Pb</i>A stimulation. Altogether, our data suggest that a non-canonical autophagy-lysosomal pathway may play a key role in cerebral malaria through regulation of brain neuro-inflammation by astrocytes.脑型疟疾（Cerebral malaria）是由恶性疟原虫（*P. falciparum*）感染诱导的神经炎性疾病。在动物模型中，脑型疟疾的神经病理生理学过程源于感染红细胞（infected red blood cells，简称iRBCs）在微血管内的黏附滞留，该过程可促进脑内神经胶质细胞的激活。此种激活会引发过度炎症反应，其特征为促炎细胞因子与趋化因子的分泌，最终导致致病性CD8⁺ T淋巴细胞浸润脑组织。星形胶质细胞是脑内神经胶质细胞的主要亚型，在维持中枢神经系统内稳态、血脑屏障（blood–brain barrier）完整性以及启动局部固有免疫应答中发挥关键作用。我们此前的研究证实，疟原虫源性微囊泡（*Pb*A-MVs）可从感染红细胞转移至星形胶质细胞。本研究表明，一种不依赖ULK1的非常规LC3介导自噬通路参与了星形胶质细胞内*Pb*A-MVs的转运与降解。我们进一步证明，通过3-甲基腺嘌呤（3-methyladenine）处理抑制自噬过程，会阻断*Pb*A-MVs的胞吞，使这些囊泡滞留于星形胶质细胞膜表面而无法被内化。此外，巴弗洛霉素A₁（bafilomycin A₁）作为另一种自噬抑制剂，可通过抑制囊泡与溶酶体的融合，促进星形胶质细胞内*Pb*A-MVs的积累，并可减轻*Pb*A感染小鼠的实验性脑型疟疾（experimental cerebral malaria, ECM）。我们还证实，RUBCN/鲁比康蛋白（RUBCN/rubicon）或自噬相关基因5（ATG5）的基因沉默，会阻碍*Pb*A刺激诱导的星形胶质细胞分泌CCL2与CXCL10趋化因子。综上，本研究数据表明，非经典自噬-溶酶体通路可能通过调控星形胶质细胞介导的脑神经炎症，在脑型疟疾的发病机制中发挥关键作用。