Bioluminescence imaging of chronic Trypanosoma cruzi infections reveals tissue-specific parasite dynamics and heart disease in the absence of locally persistent infection
Bioluminescence imaging of chronic Trypanosoma cruzi infections reveals tissue-specific parasite dynamics and heart disease in the absence of locally persistent infection
复制标题
DOI：
10.1111/cmi.12297
复制
发表时间：
2014-09-01
影响因子：
3.4
通讯作者：
Kelly, John M.
中科院分区：
文献类型：
--
作者：
Lewis, Michael D.;Francisco, Amanda Fortes;Kelly, John M.
慢性克氏锥虫感染在20%-30%的病例中导致心肌病。由于缺乏可靠的方法来检测组织内罕见的局部分布的寄生虫，因此很难确定心脏感染和病理之间的因果联系。我们开发了一种高灵敏度的生物发光成像系统，该成像系统基于表达一种新型荧光素酶的克氏锥虫，该酶能发出组织穿透的橙红色光。这使得能够对单个小鼠的寄生虫负担进行长期的连续评估，体内检测到的寄生虫的极限明显少于1000种。寄生虫在慢性感染期间的分布具有高度的局部性和时空动态，但不局限于心脏。终点体外生物发光成像允许以最小的采样偏差对寄生虫负载进行组织特异性定量。在慢性感染期间，胃肠道，特别是结肠和胃，是唯一持续观察到克氏毛虫感染的部位。定量PCR推断的寄生虫载量与体外生物发光相关，并证实肠道是寄生虫的储存库。慢性感染的小鼠发展为心肌炎和心脏纤维化，尽管没有局部持续寄生虫。这些数据表明，肠道是克氏毛滴虫长期感染的允许利基，并表明查加斯病的典型特征可以在没有持续的心肌特异性感染的情况下发生。
Chronic Trypanosoma cruzi infections lead to cardiomyopathy in 20-30% of cases. A causal link between cardiac infection and pathology has been difficult to establish because of a lack of robust methods to detect scarce, focally distributed parasites within tissues. We developed a highly sensitive bioluminescence imaging system based on T. cruzi expressing a novel luciferase that emits tissue-penetrating orange-red light. This enabled long-term serial evaluation of parasite burdens in individual mice with an in vivo limit of detection of significantly less than 1000 parasites. Parasite distributions during chronic infections were highly focal and spatiotemporally dynamic, but did not localize to the heart. End-point ex vivo bioluminescence imaging allowed tissue-specific quantification of parasite loads with minimal sampling bias. During chronic infections, the gastro-intestinal tract, specifically the colon and stomach, was the only site where T. cruzi infection was consistently observed. Quantitative PCR-inferred parasite loads correlated with ex vivo bioluminescence and confirmed the gut as the parasite reservoir. Chronically infected mice developed myocarditis and cardiac fibrosis, despite the absence of locally persistent parasites. These data identify the gut as a permissive niche for long-term T. cruzi infection and show that canonical features of Chagas disease can occur without continual myocardium-specific infection.