弓形虫脑炎的神经系统损伤及其病理机制

Pathogenic mechanisms of toxoplasmic encephalitis in central nervous system

弓形虫是引起人兽共患寄生虫病的重要病原之一。人体的获得性感染主要是由于误食了含有包囊或卵囊的食物或水。在免疫力正常人体主要表现为慢性隐性感染。随着AIDS、器官移植患者、肿瘤放化疗以及大量免疫抑制剂的应用,弓形虫脑炎的发病率明显增加,对免疫机能低下患者造成严重的威胁。弓形虫由包囊内的缓殖子向速殖子转变是导致疾病发生的先决条件,进而速殖子又可以感染神经系统中的不同细胞。这些细胞在对抗弓形虫入侵的同时也会产生各种炎症因子对神经系统造成损伤。因而对弓形虫脑炎的抗炎免疫研究甚为重要。本文主要从神经系统和细胞两个方面探讨弓形虫脑炎的损伤及其机制。

Toxoplasma gondii is one of the crucial pathogens to cause parasitic zoonoses.Infection is mainly acquired by ingestion of food or water that is contaminated with oocysts shed by cats or by eating undercooked or raw meat containing tissue cysts.In the central nervous system of immunocompentent hosts,T.gondii establishes chronic lifelong asymptomatic infection.With acquired immune deficiencies,however,such as the acquired immunodeficiency syndrome（AIDS）,recipients of organ transplants,cancer chemotherapy,as well as individuals with prolonged immunosuppressive treatments,the incidence of toxoplasmic encephalitis increased.It is a serious threat for the patients with low immune function.Conversion from bradyzoite cyst-stage parasites to fast-replicating tachyzoites is consideredas a prerequisite for reactivation and disseminated infection,and then fast-replicating tachyzoites can infect different cells which can both resist the invasion of T.gondii and generate proinflammatory cytokines.This review focuses on the injury and its mechanisms of toxoplasmic encephalitis in central nervous system.