Local association of Trypanosoma cruzi chronic infection foci and enteric neuropathic lesions at the tissue micro-domain scale

Abstract

Digestive Chagas disease (DCD) is an enteric neuropathy caused by Trypanosoma cruzi infection. The mechanism of pathogenesis is poorly understood and the lack of a robust, predictive animal model has held back research. We screened a series of mouse models using gastrointestinal tracer assays and in vivo infection imaging systems to discover a subset exhibiting chronic digestive transit dysfunction and significant retention of faeces in both sated and fasted conditions. The colon was a specific site of both tissue parasite persistence, delayed transit and dramatic loss of myenteric neurons as revealed by whole-mount immunofluorescence analysis. DCD mice therefore recapitulated key clinical manifestations of human disease. We also exploited dual reporter transgenic parasites to home in on locations of rare chronic infection foci in the colon by ex vivo bioluminescence imaging and then used fluorescence imaging in tissue microdomains to reveal co-localisation of infection and enteric nervous system lesions. This indicates that long-term T. cruzi-host interactions in the colon drive DCD pathogenesis, suggesting that the efficacy of anti-parasitic chemotherapy against chronic disease progression warrants further pre-clinical investigation.

Enteric nervous system regeneration and functional cure of experimental digestive Chagas disease with trypanocidal chemotherapy

“…In the DCD model there is a highly significant delay in GI transit time in infected mice compared to uninfected controls ((33), Fig. 2a, 2b, 2c).…”

“…We have developed C3H/HeN mice infected with bioluminescent TcI-JR parasites as a model of chronic DCD (33)(Fig. 1).…”

“…Nitrergic neuronal inhibitory signalling is critical for homeostatic control of peristalsis and its disruption is linked to a range of enteric neuropathies, including human DCD (34). Evidence for altered Nos1 gene expression in our experimental model ((33); Fig. 3c, 3e) led us to analyse the expression of the corresponding protein (neuronal NOS, nNOS) in myenteric neurons from the proximal and distal colon using immunofluorescence.…”

“…Experimental bioluminescence imaging and tissue PCR studies in mice showed that the GI tract is a major long-term reservoir of infection with diverse T. cruzi strains (28-32). This led to the development of a robust mouse model of DCD, which features significantly delayed GI transit associated with co-localised parasite persistence and enteric neuronal lesions in the wall of the large intestine (33). Here, we utilised this model to formally test the hypothesis that benznidazole-mediated cure of T. cruzi infection can either prevent DCD, or reduce its severity.…”

Trypanosoma cruzi and Chagas disease: diversity, progress and challenges

“…High resolution post-mortem confocal microscopy has revealed sequestration of infection in the intestinal tract, resurgence, and associated pathology. 12 …”