Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
Infect Immun. 2013 Jun;81(6):2002-11. doi: 10.1128/IAI.01145-12. Epub 2013 Mar 18.
Toxoplasma gondii infects both hematopoietic and nonhematopoietic cells and can cause cerebral and ocular toxoplasmosis, as a result of either congenital or postnatally acquired infections. Host protection likely acts at both cellular levels to control the parasite. CD40 is a key factor for protection against cerebral and ocular toxoplasmosis. We determined if CD40 induces anti-T. gondii activity at the level of nonhematopoietic cells. Engagement of CD40 on various endothelial cells including human microvascular brain endothelial cells, human umbilical vein endothelial cells, and a mouse endothelial cell line as well as human and mouse retinal pigment epithelial cells resulted in killing of T. gondii. CD40 stimulation increased expression of the autophagy proteins Beclin 1 and LC3 II, enhanced autophagy flux, and led to recruitment of LC3 around the parasite. The late endosomal/lysosomal marker LAMP-1 accumulated around the parasite in CD40-stimulated cells. This was accompanied by killing of T. gondii dependent on lysosomal enzymes. Accumulation of LAMP-1 and killing of T. gondii were dependent on the autophagy proteins Beclin 1 and Atg7. Together, these studies revealed that CD40 induces toxoplasmacidal activity in various nonhematopoietic cells dependent on proteins of the autophagy machinery.
刚地弓形虫感染造血细胞和非造血细胞,并可导致中枢神经系统和眼弓形体病,这是由于先天或后天获得性感染。宿主的保护作用可能在细胞水平上控制寄生虫。CD40 是预防中枢神经系统和眼弓形体病的关键因素。我们确定 CD40 是否在非造血细胞水平诱导抗弓形体活性。CD40 与各种内皮细胞(包括人脑微血管内皮细胞、人脐静脉内皮细胞和小鼠内皮细胞系以及人视网膜色素上皮细胞和小鼠视网膜色素上皮细胞)的结合导致弓形体的杀伤。CD40 刺激增加了自噬蛋白 Beclin 1 和 LC3 II 的表达,增强了自噬通量,并导致 LC3 围绕寄生虫募集。晚期内体/溶酶体标记物 LAMP-1 在 CD40 刺激的细胞中在寄生虫周围积累。这伴随着依赖溶酶体酶的弓形体的杀伤。LAMP-1 的积累和弓形体的杀伤依赖于自噬蛋白 Beclin 1 和 Atg7。总之,这些研究表明,CD40 在各种非造血细胞中诱导依赖于自噬机制蛋白的杀弓形体活性。