Research on Trypanosoma cruzi and Analysis of Inflammatory Infiltrate in Esophagus and Colon from Chronic Chagasic Patients with and without Mega

Cancer and Trypanosoma cruzi: Tumor induction or protection?

Trypanosoma cruzi causes Chagas disease, a neglected disease that can be divided, overall, into acute and chronic phases. Understanding the mechanisms underlying its progression is based on the parasite-host interactions occurring during the infection. Although the pathophysiology of the main symptomatic forms of Chagas disease has been the subject of several studies, little is known about their relationship with the development of different types of cancer. Therefore, knowledge regarding the molecular aspects of infection in the host, as well as the influence of the immune response in the parasite and the host, can help to understand the association between Chagas disease and tumor development. This review aims to summarize the main molecular mechanisms related to T. cruzi-dependent carcinogenic development and the mechanisms associated with tumor protection mediated by different parasite components.

Molecular detection and parasite load of Trypanosoma cruzi in digestive tract tissue of Chagas disease patients affected by megacolon

Chagas disease, caused by the Trypanosoma cruzi parasite in the Americas affects ∼ 7 million people, 30% with cardiac tissue damage and 10-15% with digestive disorders. In this study, we have developed a protocol to detect the presence of the parasite and estimate its load in resected dysfunctional tissue segments of chronically infected patients with digestive megacolon. We have included samples from 43 individuals, 38/5 with positive/negative serology for Chagas disease and digestive syndromes.. Samples of 1.5 to 2.0 cm were taken from different points of the dysfunctional digestive tract in specialized centres in Cochabamba, Bolivia. T.cruzi cultures were performed by inoculation with NNN-LIT culture medium, and genomic material was obtained from the samples formultiplex qPCR with TaqMan probes targeting satellite nuclear DNA. Cultures failed to isolate T. cruzi but qPCR reached a sensitivity of 42.1% (16/38) with all three spots and in triplicate.. A new quantification methodology using synthetic satellite DNA as quantitation standard revealed parasite loads ranging from 2.2 × 10² to 1.0 × 10⁶ satellite DNA copies/μl. Positive samples from the distal end showed a higher parasite load. The results of the present study strengthen and add further evidence to previous findings in an experimental mouse model of chronic T. cruzi infection, providing a valuable tool to improve scientific knowledge on the relevance of the digestive tract in parasite persistence, and underlines the need of a better understanding of host-pathogen interaction in digestive tissues, considering pathophysiology, disease immunology and response to treatment.

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

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.

Chagas disease (American trypanosomiasis) is caused by the protozoan parasite Trypanosoma cruzi. Chagas disease has two types, the cardiac form and the digestive form; some patients have symptoms of both. How the parasite causes digestive disease is poorly understood. It is known that damage to the gut’s nervous system is an important factor, but it has been unclear exactly where and when this damage occurs during the course of an infection and also why only a subset of infected people suffer from this outcome. We studied infections in mice and found certain combinations of strains of parasites and mice that exhibited symptoms similar to human digestive Chagas patients, including a problem with peristalsis that localised specifically to the colon. Using parasites that were genetically engineered to emit both bioluminescent and fluorescent light, we tracked infections over time and were able to analyse rare infected cells deep within the muscle tissue of the wall of the colon. We found evidence of damaged neurons in the same location as these infection foci over 6 months after initial infection. Our results show that digestive Chagas disease probably develops as a result of chronic infection and inflammation, which potentially changes approaches to treatment.

Understanding the oral transmission of Trypanosoma cruzi as a veterinary and medical foodborne zoonosis

Chagas disease is a neglected tropical disease transmitted by the protozoan Trypanosoma cruzi that lately has been highlighted because several outbreaks attributed to oral transmission of the parasite have occurred. These outbreaks are characterized by high mortality rates and massive infections that cannot be related to other types of transmission such as the vectorial route. Oral transmission of Chagas disease has been reported in Brazil, Colombia, Venezuela, Bolivia, Ecuador, Argentina and French Guiana, most of them are massive oral outbreaks caused by the ingestion of beverages and food contaminated with triatomine feces or parasites' reservoirs secretions and considered since 2012 as a foodborne disease. In this review, we present the current status and all available data regarding oral transmission of Chagas disease, highlighting its relevance as a veterinary and medical foodborne zoonosis.

Low-Level Parasite Persistence Drives Vasculitis and Myositis in Skeletal Muscle of Mice Chronically Infected with Trypanosoma cruzi

In chronic Trypanosoma cruzi infection, the cause of Chagas disease, life-threatening inflammatory diseases develop over time in the heart, esophagus, and colon of some patients. C57BL/6 mice infected with the myotropic Colombiana strain of T. cruzi model many of the immunological and parasitological features of human infection but succumb to chronic paralyzing myositis and skeletal muscle vasculitis, not cardiomyopathy or gastrointestinal disease. Here we show that T cell depletion in the chronic phase of this model increased tissue parasitism to acute-phase levels and induced neutrophilic skeletal muscle inflammation. Conversely, after daily treatment with the trypanocide benznidazole for 8 weeks during the chronic phase, viable parasites were no longer detectable, myositis completely resolved, vasculitis was ∼80% reduced, fibrosis was reduced, and myofiber morphology normalized. After the drug was discontinued, parasitism rebounded, and immunopathology recurred. The parasite load was statistically strongly correlated with the severity of inflammation. Thus, both T cell immunity and trypanocidal pharmacotherapy suppress to very low levels, but do not cure, T. cruzi infection, which is necessary and possibly sufficient to induce crippling chronic skeletal muscle myositis and vasculitis in the model.

An autopsy-based study of Trypanosoma cruzi persistence in organs of chronic chagasic patients and its relevance for transplantation

BACKGROUND

Chagas' disease (CD) is caused by infection with the protozoan Trypanosoma cruzi. The disease can affect the heart and/or the gastrointestinal (GI) tract, but around 70% of infected individuals remain asymptomatic in the chronic form. Organ transplantation from T. cruzi-infected donors is often avoided because of the risk of disease transmission, previously reported after heart, kidney, or liver transplantation.

METHODS

We investigated by histology, immunohistochemistry, and polymerase chain reaction (PCR) the persistence of T. cruzi in samples of the heart, lung, liver, kidney, pancreas, adrenal gland, esophagus, and GI tract of 21 chronic chagasic patients.

RESULTS

Parasite persistence was detected in 12/21 (57.1%) heart samples, mainly by PCR-based assays. T. cruzi parasites were detected by histology and immunohistochemistry in smooth muscle cells of the central vein from 1/21 (4.8%) adrenal gland samples. No samples of the lung, liver, kidney, pancreas, esophagus, or GI tract were found to have parasites by histology, immunohistochemistry, or PCR.

CONCLUSIONS

We concluded that, aside from the heart, the other solid organs of T. cruzi-infected donors can be used for transplantation with a lot of caution. Such organs are not safe in the view of previous reports of CD transmission, but seem to present a low T. cruzi load compared to the heart.

Myenteric neuroprotective role of aspirin in acute and chronic experimental infections with Trypanosoma cruzi

BACKGROUND

Experimental and clinical studies have shown that myenteric neuron cell death during infection with Trypanosoma cruzi mainly occurs in the esophagus and colon, resulting in megaesophagus and megacolon, respectively. Evidence suggests that the cyclooxygenase enzyme (COX) is involved in the T. cruzi invasion process. The use of low-dose aspirin (ASA), a COX-1/COX-2 inhibitor, has been shown to reduce infection with T. cruzi. Therefore, in this study, we evaluated the effects of treatment with low-dose ASA on myenteric colonic neurons during murine infection with T. cruzi.

METHODS

Swiss mice were assigned into groups treated with either phosphate-buffered saline or low doses of ASA during the acute phase (20 mg/kg ASA) and chronic phase (50 mg/kg ASA) of infection with the Y strain of T. cruzi. Seventy-five days after infection, colon samples were collected to quantify inflammatory foci in histological sections and also general (myosin-V⁺ ), nitrergic, and VIPergic myenteric neurons in whole mounts. Gastrointestinal transit time was also measured.

KEY RESULTS

Aspirin treatment during the acute phase of infection reduced parasitemia (P<.05). Aspirin treatment during the acute or chronic phase of the infection reduced the intensity of inflammatory foci in the colon, protected myenteric neurons from cell death and plastic changes, and recovered the gastrointestinal transit of mice infected with T. cruzi (P<.05).

CONCLUSION & INFERENCES

Early and delayed treatment with low-dose ASA can reduce the morphofunctional damage of colonic myenteric neurons caused by murine T. cruzi infection.

Evaluation of the immunohistochemical expression of Gal-1, Gal-3 and Gal-9 in the colon of chronic chagasic patients

OBJECTIVE AND DESIGN

The aim of the present study was to evaluate the immunohistochemical expression of Gal-1, Gal-3 and Gal-9 in the colon of chronic chagasic patients compared to biopsied non-chagasic patients.

MATERIAL OR SUBJECTS

Thirty-two colon fragments were selected from chagasic patients with megacolon (n=25) and nonchagasic patients without megacolon (n=7).

METHODS

Immunohistochemistry for Gal-1, Gal-3 and Gal-9 was performed using a common light microscope and the results were scored 0-3 according to labeling intensity. Data were analyzed statistically by the chi-square test.

RESULTS

Higher Gal-1, Gal-3 and Gal-9 expression was observed in the myenteric plexus ganglia of chagasic patients compared to non-chagasic patients, p=0.0487, p=0.0019 and p=0.0325, respectively, whereas no significant differences were observed between groups regarding the expression of Gal-1, Gal-3 and Gal-9 in the muscle layer.

CONCLUSION

Since Gal-1, Gal-3 and Gal-9 galectin expression was higher in the myenteric plexus ganglia of chagasic patients, we believe that these lectins may be associated with ganglionitis in the chagasic megacolon. However, since the present study was the first to report the participation of Gal-9 in Chagas disease, further investigations are needed to elucidate the role of galectin 9 in this disease.

Putting Infection Dynamics at the Heart of Chagas Disease

In chronic Trypanosoma cruzi infections, parasite burden is controlled by effective, but nonsterilising immune responses. Infected cells are difficult to detect because they are scarce and focally distributed in multiple sites. However, advances in detection technologies have established a link between parasite persistence and the pathogenesis of Chagas heart disease. Long-term persistence likely involves episodic reinvasion as well as continuous infection, to an extent that varies between tissues. The primary reservoir sites in humans are not definitively known, but analysis of murine models has identified the gastrointestinal tract. Here, we highlight that quantitative, spatial, and temporal aspects of T. cruzi infection are central to a fuller understanding of the association between persistence, pathogenesis, and immunity, and for optimising treatment.

Host and parasite genetics shape a link between Trypanosoma cruzi infection dynamics and chronic cardiomyopathy

Host and parasite diversity are suspected to be key factors in Chagas disease pathogenesis. Experimental investigation of underlying mechanisms is hampered by a lack of tools to detect scarce, pleiotropic infection foci. We developed sensitive imaging models to track Trypanosoma cruzi infection dynamics and quantify tissue-specific parasite loads, with minimal sampling bias. We used this technology to investigate cardiomyopathy caused by highly divergent parasite strains in BALB/c, C3H/HeN and C57BL/6 mice. The gastrointestinal tract was unexpectedly found to be the primary site of chronic infection in all models. Immunosuppression induced expansion of parasite loads in the gut and was followed by widespread dissemination. These data indicate that differential immune control of T. cruzi occurs between tissues and shows that the large intestine and stomach provide permissive niches for active infection. The end-point frequency of heart-specific infections ranged from 0% in TcVI-CLBR-infected C57BL/6 to 88% in TcI-JR-infected C3H/HeN mice. Nevertheless, infection led to fibrotic cardiac pathology in all models. Heart disease severity was associated with the model-dependent frequency of dissemination outside the gut and inferred cumulative heart-specific parasite loads. We propose a model of cardiac pathogenesis driven by periodic trafficking of parasites into the heart, occurring at a frequency determined by host and parasite genetics.

Inflammatory responses and intestinal injury development during acute Trypanosoma cruzi infection are associated with the parasite load

Background

Chagas disease is caused by the protozoan Trypanosoma cruzi and is characterized by cardiac, gastrointestinal, and nervous system disorders. Although much about the pathophysiological process of Chagas disease is already known, the influence of the parasite burden on the inflammatory process and disease progression remains uncertain.

Methods

We used an acute experimental disease model to evaluate the effect of T. cruzi on intestinal lesions and assessed correlations between parasite load and inflammation and intestinal injury at 7 and 14 days post-infection. Low (3 × 10²), medium (3 × 10³), and high (3 × 10⁴) parasite loads were generated by infecting C57BL/6 mice with “Y”-strain trypomastigotes. Statistical analysis was performed using analysis of variance with Tukey’s multiple comparison post-test, Kruskal–Wallis test with Dunn’s multiple comparison, χ2 test and Spearman correlation.

Results

High parasite load-bearing mice more rapidly and strongly developed parasitemia. Increased colon width, inflammatory infiltration, myositis, periganglionitis, ganglionitis, pro-inflammatory cytokines (e.g., TNF-α, INF-γ, IL-2, IL-17, IL-6), and intestinal amastigote nests were more pronounced in high parasite load-bearing animals. These results were remarkable because a positive correlation was observed between parasite load, inflammatory infiltrate, amastigote nests, and investigated cytokines.

Conclusions

These experimental data support the idea that the parasite load considerably influences the T. cruzi-induced intestinal inflammatory response and contributes to the development of the digestive form of the disease.

Mast cells in the colon of Trypanosoma cruzi-infected patients: are they involved in the recruitment, survival and/or activation of eosinophils?

Megacolon is frequently observed in patients who develop the digestive form of Chagas disease. It is characterized by dilation of the rectum-sigmoid portion and thickening of the colon wall. Microscopically, the affected organ presents denervation, which has been considered as consequence of an inflammatory process that begins at the acute phase and persists in the chronic phase of infection. Inflammatory infiltrates are composed of lymphocytes, macrophages, natural killer cells, mast cells, and eosinophils. In this study, we hypothesized that mast cells producing tryptase could influence the migration and the activation of eosinophils at the site, thereby contributing to the immunopathology of the chronic phase. We seek evidence of interactions between mast cells and eosinophils through (1) evaluation of eosinophils, regarding the expression of PAR2, a tryptase receptor; (2) correlation analysis between densities of mast cells and eosinophils; and (3) ultrastructural studies. The electron microscopy studies revealed signs of activation of mast cells and eosinophils, as well as physical interaction between these cells. Immunohistochemistry and correlation analyses point to the participation of tryptase immunoreactive mast cells in the migration and/or survival of eosinophils at the affected organ.

Altered distribution of peripheral blood memory B cells in humans chronically infected with Trypanosoma cruzi

Numerous abnormalities of the peripheral blood T cell compartment have been reported in human chronic Trypanosoma cruzi infection and related to prolonged antigenic stimulation by persisting parasites. Herein, we measured circulating lymphocytes of various phenotypes based on the differential expression of CD19, CD4, CD27, CD10, IgD, IgM, IgG and CD138 in a total of 48 T. cruzi-infected individuals and 24 healthy controls. Infected individuals had decreased frequencies of CD19+CD27+ cells, which positively correlated with the frequencies of CD4+CD27+ cells. The contraction of CD19+CD27+ cells was comprised of IgG+IgD-, IgM+IgD- and isotype switched IgM-IgD- memory B cells, CD19+CD10+CD27+ B cell precursors and terminally differentiated CD19+CD27+CD138+ plasma cells. Conversely, infected individuals had increased proportions of CD19+IgG+CD27-IgD- memory and CD19+IgM+CD27-IgD+ transitional/naïve B cells. These observations prompted us to assess soluble CD27, a molecule generated by the cleavage of membrane-bound CD27 and used to monitor systemic immune activation. Elevated levels of serum soluble CD27 were observed in infected individuals with Chagas cardiomyopathy, indicating its potentiality as an immunological marker for disease progression in endemic areas. In conclusion, our results demonstrate that chronic T. cruzi infection alters the distribution of various peripheral blood B cell subsets, probably related to the CD4+ T cell deregulation process provoked by the parasite in humans.

Bioluminescence imaging of chronic Trypanosoma cruzi infections reveals tissue-specific parasite dynamics and heart disease in the absence of locally persistent infection

Summary

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.

Complete genome sequence of a nephropathogenic infectious bronchitis virus strain isolated in china

Infectious bronchitis virus (IBV) causes tremendous economic losses to the poultry industry. Here, we report the complete genome analysis results for a new natural recombination nephropathogenic IBV strain named SAIBK, which was isolated in the Sichuan province of China in 2005.

Complete genome sequences of two Chinese virulent avian coronavirus infectious bronchitis virus variants

Avian coronavirus infectious bronchitis virus (IBV) is variable, which causes many serotypes. Here we reported the complete genome sequences of two virulent IBV variants from China, GX-YL5 and GX-YL9, belonging to different serotypes. Differences between GX-YL5 and GX-YL9 were found mainly in stem-loop structure I in the predicted RNA secondary structure of open reading frame (ORF) 1b and the S protein gene fusion region, which will help us understand the molecular evolutionary mechanism of IBV and the disconcordance between the genotypes and serotypes of coronavirus.

The significantly reduced number of interstitial cells of Cajal in chagasic megacolon (CM) patients might contribute to the pathophysiology of CM

In addition to neurons, interstitial cells of Cajal (ICC) play an important role in coordinating intestinal motility with a pacemaker function. This study aimed to quantitatively analyze ICC, neurons, and muscular area, the latter to correct for quantitation errors resulting from dilation in case of a megacolon and from the dispersion of ICC that can be attributed to muscular hypertrophy. We analyzed 30 colon samples: ten chagasic megacolon (CM), ten chagasic colons without megacolon (CXM), and ten nonchagasic control patients (NC). We measured the area of muscularis propria and counted the number of neurons of the myenteric plexus in a histological section of an intestinal ring and the number of ICC at the level of the myenteric plexus and circular muscle layer, the latter in a section immunohistochemically stained for CD117. Muscular hypertrophy occurred only in the CM group. Compared to the NC group, we found in the CM group a statistically significant reduction of 80 % in the number of neurons, 60 % in the number of ICC in the myenteric plexus, and 38 % in the area of circular muscle. In the CXM group, these numbers were highly variable, and their reduction, less pronounced. We conclude that the number of ICC is significantly reduced in CM patients, and that this might contribute to the pathophysiology of CM. However, the development of CM requires severe denervation, whereas CXM generally exhibits less than 50 % denervation, favoring the hypothesis that the reduction in ICC number is, in part, a consequence of denervation.