Guidelines on the treatment of chronic coinfection by Trypanosoma cruzi and HIV outside endemic areas

As a result of population migration, Chagas disease is no longer limited to the North and South American continents. In HIV-infected patients, chronic infection by Trypanosoma cruzi behaves as an opportunistic infection in severely immunosuppressed patients and is responsible for high morbidity and mortality. Unlike other opportunistic infections, information on the natural history, diagnosis, treatment, and prevention of Chagas disease is scarce. Spain has the highest number of cases of Chagas disease outside the North and South American continents, and coinfection with HIV is increasingly prevalent. In this article, the Spanish Society for Tropical Medicine and International Health (Sociedad Espa?ola de Medicina Tropical y Salud Internacional) reviews the current situation of coinfection with HIV and T. cruzi infection and provides guidelines on the diagnosis, treatment, and prevention in areas where Chagas disease is not endemic. It also identifies areas of uncertainty where additional research is necessary.     

Chagasic megacolon associated with Trypanosoma cruzi I in a Colombian patient

Chagasic megacolon has been reported in the southern cone countries of South America and is mainly associated with Trypanosoma cruzi II infection. Herein, we report the first case in Colombia of chagasic megacolon with cardiomyopathy associated with the T. cruzi I lineage. This finding suggests that in Colombia, as well as in other northern countries of South America and throughout Central America, where T. cruzi I is endemic, cardiomyopathy may not be the only clinical form of Chagas disease.     

Autoantibodies to Neurotrophic Receptors TrkA,TrkB and TrkC in Patients with Acute Chagas’ Disease

Neurotrophic receptors TrkA and TrkC double up as receptors that Trypanosoma cruzi uses to invade cells and as autoantigen in T. cruzi‐infected individuals (with Chagas’ disease). Consequently, autoantibodies against TrkA and TrkC (ATA) potently block T. cruzi invasion in vitro and in ATA‐immunized mice. Thus, ATA could keep T. cruzi invasion in check in Chagas’ disease. However, ATA has been examined only in patients with chronic Chagas’ disease. To determine whether ATA potentially participate in the early stage of infection, we analysed the sera of 15 patients with acute Chagas’ disease, 4–66 years of age. We find that all sera contain high antibody titres to TrkA, TrkB and TrkC, but not to other growth factor receptors, indicating that ATA are produced relatively soon after T. cruzi infection by an age‐independent process. One individual, who acquired the disease after an accidental laboratory infection, converted to Trk‐antibody (Ab)‐seronegative when progressing to the chronic phase. ATA from acute patients were of low avidity (K₀ <24.8 × 10^?8 m ) and of IgM and IgA isotypes. In contrast, ATA from chronic patients were of high avidity (K_o = 1.4 to 4.5 × 10^?8 m ) and of the IgG2 isotype. Therefore, ATA underwent affinity maturation and class switch when patients progressed from acute to chronic disease. Thus, it may be that Trk autoimmunity, which starts in the acute Chagas’ disease, plays a role in attenuating parasitemia and tissue parasitism that characterizes the acute/chronic phase transition of Chagas’ disease.     

Chagas disease: a threat to safe blood transfusion

Chagas disease affects approximately 8 million infected people in Mexico and Central and South America and causes 12 500 deaths annually; 41 200 new cases are reported annually (2006). Coordinated multicenter programmes have decreased about 70% of new infections in South America due to the interruption of vectorial and decreased blood transfusion transmissions. Migration of the infected population from rural areas to urban centres in endemic and non-endemic countries led to the urbanization and globalization of Chagas disease. Chagas disease is now an emerging disease in non-endemic areas, where congenital, blood and organ transplant transmissions are associated with reactivation of chronic Chagas disease in patients under immunosuppression or HIV infection. Recent initiatives in non-endemic countries have been implemented to control its transmission by blood transfusion and transplants of organs. Most of the infected people were asymptomatic individuals in the chronic phase of the disease, characterized by and low and intermittent parasitemia and diagnosed by serological tests. In endemic countries, universal mandatory screening tests for detection of Trypanosoma cruzi antibodies dramatically reduced blood transfusion transmission. In non-endemic countries, where transfusion represents the most important way of transmission, different strategies have been registered: (1) blood donor selection and deferral; (2) blood donation testing; (3) blood donation testing in people who lived in endemic areas. Questionnaires containing well-defined questions help to identify patients from endemic areas and their epidemiological data but are of limited value since they depend on donor information. High-performance serologic tests were reported for the detection of anti-T. cruzi antibodies like ELISA with epimastigotes or trypomastigotes or recombinant antigens, chemiluminescent, immunoblot and radioimmunoprecipitation assays. Almost 100% of sensitivity and specificity were registered when tested in samples of well-defined chronic chagasic patients but gold standards are not validated in circumstances of low prevalence of the disease. Additionally, their value in cases of inconclusive results (one positive test and other negative or doubtful results) was not known. Unfortunately, molecular methods are less sensitive than serology for the chronic phase of the disease (45–100% sensitivity) and were not reliable for screening tests in blood banks. Perspectives of the reduction of parasites by photochemical treatment and ultraviolet (crystal violet, methylene blue, amotosalen, riboflavin, thiopirilium) were reported sometimes with slight changes in the blood products. However, the main challenge is to demonstrate their value for prevention of a broad spectrum of agents transmitted by blood transfusion (including príon disease) and inactivation of low parasite load. In summary, questionnaires including specific questions about donor epidemiology and high-performance serologic tests have been useful for blood bank screening. The cost–benefit–effectiveness analyses of universal serologic screening vs. serologic screening of selected donors depend on the prevalence of positive donors and should be evaluated in different regions. Finally, as pathogen inactivation methods may represent remarkable improvement in blood bank transfusion, efforts from the academia are necessary to prove their safety and effectiveness, and from blood banking–transfusion medicine community and public regulators to their implementation aiming to increase the safety of blood transfusion for patients around the world.     

Comparative Evaluation of 11 Commercialized Rapid Diagnostic Tests for Detecting Trypanosoma cruzi Antibodies in Serum Banks in Areas of Endemicity and Nonendemicity

Chagas disease is one of the main public health issues in Latin America. Increasingly during the past few decades, Trypanosoma cruzi infection has been detected in North America, Europe, and the Western Pacific, mainly as a result of population movement. The limited availability of rapid serological diagnostic tests hinders rapid diagnosis and early treatment in areas of endemicity and nonendemicity. In collaboration with 11 national reference laboratories (NRLs) from different geographical areas, we evaluated the performances of commercialized serological rapid diagnostic tests (RDT) for T. cruzi infection. Eleven commercialized T. cruzi infection RDTs were evaluated on a total of 474 samples extensively tested with at least three different techniques for Chagas disease, maintained at controlled low temperatures, and stored in the serum banks of the 11 NRLs. We measured the sensitivity, specificity, and concordance of each RDT and provided an additional questionnaire to evaluate its ease of use. The selected RDTs in this study were performed under controlled laboratory conditions. Out of the 11 RDTs, we found 8 of them to be useful, with the cassette format favored over the strip. We did not observe significant differences in RDT performances in the different regions. Overall, the performance results were lower than those disclosed by the manufacturers. The results of this evaluation validate the possibility of using RDTs to diagnose Chagas disease, thereby decreasing the time to treatment at a primary health care facility for patients who are willing to be treated. Further studies should be conducted in the laboratory and in the field to confirm these data, expressly to evaluate reproducibility in resource-limited settings, or using whole blood in clinical settings in areas of endemicity and nonendemicity.     

The Chronic Gastrointestinal Manifestations of Chagas Disease

Chagas disease is an infectious disease caused by the protozoan Trypanosoma cruzi. The disease mainly affects the nervous system, digestive system and heart. The objective of this review is to revise the literature and summarize the main chronic gastrointestinal manifestations of Chagas disease. The chronic gastrointestinal manifestations of Chagas disease are mainly a result of enteric nervous system impairment caused by T. cruzi infection. The anatomical locations most commonly described to be affected by Chagas disease are salivary glands, esophagus, lower esophageal sphincter, stomach, small intestine, colon, gallbladder and biliary tree. Chagas disease has also been studied in association with Helicobacter pylori infection, interstitial cells of Cajal and the incidence of gastrointestinal cancer.     

Current understanding of immunity to Trypanosoma cruzi infection and pathogenesis of Chagas disease

Chagas disease caused by Trypanosoma cruzi remains an important neglected tropical disease and a cause of significant morbidity and mortality. No longer confined to endemic areas of Latin America, it is now found in non-endemic areas due to immigration. The parasite may persist in any tissue, but in recent years, there has been increased recognition of adipose tissue both as an early target of infection and a reservoir of chronic infection. The major complications of this disease are cardiomyopathy and megasyndromes involving the gastrointestinal tract. The pathogenesis of Chagas disease is complex and multifactorial involving many interactive pathways. The significance of innate immunity, including the contributions of cytokines, chemokines, reactive oxygen species, and oxidative stress, has been emphasized. The role of the components of the eicosanoid pathway such as thromboxane A₂ and the lipoxins has been demonstrated to have profound effects as both pro- and anti-inflammatory factors. Additionally, we discuss the vasoconstrictive actions of thromboxane A₂ and endothelin-1 in Chagas disease. Human immunity to T. cruzi infection and its role in pathogen control and disease progression have not been fully investigated. However, recently, it was demonstrated that a reduction in the anti-inflammatory cytokine IL-10 was associated with clinically significant chronic chagasic cardiomyopathy.     

Chagas disease as example of a reemerging parasite

Trypanosoma cruzi, the protozoan that causes Chagas disease, is primarily transmitted by three main Triatomine vectors in endemic areas. However, the infection has become a potential emerging disease because the vector is found in non-endemic areas, there is migration of infected asymptomatic people that can infect the vector, become blood donors, or pass the disease vertically (congenital infections). Lastly, the disease can be acquired through contaminated food (oral transmission). This review will present the different transmission pathways, clinical manifestations, diagnostic modalities and treatment considerations of Chagas disease.     

Sudden death caused by chronic Chagas disease in a non‐endemic country: Autopsy report

Chagas disease is a tropical disease that is prevalent in Latin America. Described herein is an autopsy case of the sudden death of a 48‐year‐old Brazilian man who had stayed in Japan for 7 years. The man, who had a history of Chagas disease, collapsed unexpectedly at work. Because the cause of death was unknown, forensic autopsy examination was performed. As gross findings, the heart was dilated and rounded with an increase in size and weight. The esophagus and large intestine were dilated moderately, with extensive interstitial inflammatory infiltration in the cardiac muscle, but no apparent parasite nest was observed in various tissues. On post‐mortem laboratory examinations, indirect immunofluorescence antibody test indicated the presence of IgG antibody specific to Trypanosoma cruzi in the serum. Subsequent polymerase chain reaction amplification using DNA extracted from blood yielded the specific product derived from T. cruzi genomic DNA. These examinations indicate that the infection had resulted from the Tripanosoma parasite. The cause of death was judged to be chronic cardiomyopathy caused by Chagas disease. It is important for pathologists to know the possible involvement of chronic Chagas disease in sudden unexpected deaths in the current globalized society of Japan.     

Specific activation of CD4–CD8– double‐negative T cells by Trypanosoma cruzi‐derived glycolipids induces a proinflammatory profile associated with cardiomyopathy in Chagas patients

Cardiomyopathy is the most severe outcome of Chagas disease, causing more than 12 000 deaths/year. Immune cells participate in cardiomyopathy development either by direct tissue destruction, or by driving inflammation. We have shown that CD4^–CD8^– [double‐negative (DN)] T cells are major sources of inflammatory and anti‐inflammatory cytokines, associated with the cardiac (CARD) and indeterminate (IND) forms of Chagas disease, respectively. Here, we sought to identify Trypanosoma cruzi‐derived components that lead to activation of DN T cells in Chagas patients. Glycolipid (GCL), lipid (LIP) and protein‐enriched (PRO) fractions derived from trypomastigote forms of T. cruzi were utilized to stimulate cells from IND and CARD patients to determine DN T cell activation by evaluating CD69 and cytokine expression. We observed that GCL, but not LIP or PRO fractions, induced higher activation of DN T cells, especially T cell receptor (TCR)‐γδ DN T, from IND and CARD. GCL led to an increase in tumour necrosis factor (TNF) and interleukin (IL)‐10 expression by TCR‐γδ DN T cells from IND, while inducing IFN‐γ expression by TCR‐γδ DN T cells from CARD. This led to an increase in the ratio IFN‐γ/IL‐10 in TCR‐γδ DN T cells from CARD, favouring an inflammatory profile. These results identify GCL as the major T. cruzi component responsible for activation of DN T cells in chronic Chagas disease, associated predominantly with an inflammatory profile in CARD, but not IND. These findings may have implications for designing new strategies of control or prevention of Chagas disease cardiomyopathy by modulating the response to GCL.     

Differential tissue distribution of diverse clones of Trypanosoma cruzi in infected mice

Chagas disease, caused by the protozoan Trypanosoma cruzi, presents variable clinical course but the phenomena underlying this variability remain largely unknown. T. cruzi has a clonal population structure and infecting strains are often multiclonal. T. cruzi genetic variability could be a determinant of differential tissue tropism or distribution and consequently of the clinical forms of the disease. We tested this hypothesis by using low-stringency single specific primer polymerase chain reaction (LSSP-PCR) to type genetically the parasites in tissues of experimental infected mice. BALB/c mice were simultaneously inoculated with two different T. cruzi populations (JG strain and Col1.7G2 clone). Doubly infected animals showed clear differential tissue distribution for the two populations (chronic phase). Our results indicate a significant influence of the genetic polymorphism of infecting T. cruzi populations in the pathogenesis of chronic Chagas disease.     

Trypanosoma cruzi cleaves galectin-3 N-terminal domain to suppress its innate microbicidal activity

Galectin-3 is the best-characterized member of galectins, an evolutionary conserved family of galactoside-binding proteins that play central roles in infection and immunity, regulating inflammation, cell migration and cell apoptosis. Differentially expressed by cells and tissues with immune privilege, they bind not only to host ligands, but also to glycans expressed by pathogens. In this regard, we have previously shown that human galectin-3 recognizes several genetic lineages of the protozoan parasite Trypanosoma cruzi, the causal agent of Chagas’ disease or American trypanosomiasis. Herein we describe a molecular mechanism developed by T. cruzi to proteolytically process galectin-3 that generates a truncated form of the protein lacking its N-terminal domain – required for protein oligomerization – but still conserves a functional carbohydrate recognition domain (CRD). Such processing relies on specific T. cruzi proteases, including Zn-metalloproteases and collagenases, and ultimately conveys profound changes in galectin-3-dependent effects, as chemical inhibition of parasite proteases allows galectin-3 to induce parasite death in vitro. Thus, T. cruzi might have established distinct mechanisms to counteract galectin-3-mediated immunity and microbicide properties. Interestingly, non-pathogenic T. rangeli lacked the ability to cleave galectin-3, suggesting that during evolution two genetically similar organisms have developed different molecular mechanisms that, in the case of T. cruzi, favoured its pathogenicity, highlighting the importance of T. cruzi proteases to avoid immune mechanisms triggered by galectin-3 upon infection. This study provides the first evidence of a novel strategy developed by T. cruzi to abrogate signalling mechanisms associated with galectin-3-dependent innate immunity.     

Bone marrow cells migrate to the heart and skeletal muscle and participate in tissue repair after Trypanosoma cruzi infection in mice

Infection by Trypanosoma cruzi, the aetiological agent of Chagas disease, causes an intense inflammatory reaction in several tissues, including the myocardium. We have previously shown that transplantation of bone marrow cells (BMC) ameliorates the myocarditis in a mouse model of chronic Chagas disease. We investigated the participation of BMC in lesion repair in the heart and skeletal muscle, caused by T. cruzi infection in mice. Infection with a myotropic T. cruzi strain induced an increase in the percentage of stem cells and monocytes in the peripheral blood, as well as in gene expression of chemokines SDF‐1, MCP1, 2, and 3 in the heart and skeletal muscle. To investigate the fate of BMC within the damaged tissue, chimeric mice were generated by syngeneic transplantation of green fluorescent protein (GFP⁺) BMC into lethally irradiated mice and infected with Trypanosoma cruzi. Migration of GFP⁺ BMC to the heart and skeletal muscle was observed during and after the acute phase of infection. GFP⁺ cardiomyocytes and endothelial cells were present in heart sections of chimeric chagasic mice. GFP⁺ myofibres were observed in the skeletal muscle of chimeric mice at different time points following infection. In conclusion, BMC migrate and contribute to the formation of new resident cells in the heart and skeletal muscle, which can be detected both during the acute and the chronic phase of infection. These findings reinforce the role of BMC in tissue regeneration.     

Clinical and Immunologic Predictors of Death After an Acute Opportunistic Infection: Results from ACTG A5164

Background: In the pre–antiretroviral therapy (ART) era, markers of increased disease severity during an acute opportunistic infection (OI) were associated with mortality. Even with ART, mortality remains high during the first year after an OI in persons with advanced HIV infection, but it is unclear whether previous predictors of mortality remain valid in the current era. Objective: To determine clinical and immunological predictors of death after an OI. Methods: We used clinical data and stored plasma from ACTG A5164, a multicenter study evaluating the optimal timing of ART during a nontuberculous OI. We developed Cox models evaluating associations between clinical parameters and plasma marker levels at entry and time to death over the first 48 weeks after the diagnosis of OI. We developed multivariable models incorporating only clinical parameters, only plasma marker levels, or both. Results: The median CD4+ T-cell count in study participants at baseline was 29 cells/µL. Sixty-four percent of subjects had Pneumocystis jirovecii pneumonia (PCP). Twenty-three of 282 (8.2%) subjects died. In univariate analyses, entry mycobacterial infection, OI number, hospitalization, low albumin, low hemoglobin, lower CD4, and higher IL-8 and sTNFrII levels and lower IL-17 levels were associated with mortality. In the combined model using both clinical and immunologic parameters, the presence of an entry mycobacterial infection and higher sTNFrII levels were significantly associated with death. Conclusions: In the ART era, clinical risk factors for death previously identified in the pre-ART era remain predictive. Additionally, activation of the innate immune system is associated with an increased risk of death following an acute OI.     

Cryptococcosis in HIV-AIDS patients from Southern Brazil: Still a major problem

IntroductionCryptococcus neoformans is an opportunistic pathogen that causes ∼15% mortality in AIDS patients. Rio Grande City, Rio Grande do Sul (RS), Brazil, has the highest national rate of HIV/AIDS, considering cities with population more than 100,000 habitants.ObjectiveWe aimed to evaluate the clinical and epidemiological profile of cryptococcosis in a reference service for HIV-AIDS patients in the South region of Brazil, over seven years. Material and methods A retrospective study was performed including all cryptococcosis cases diagnosed at the University Hospital, Federal University of Rio Grande (UH-FURG) between January 2010 and December 2016.ResultsSeventy cases of cryptococcosis were diagnosis from 2010 to 2016 in the UH-FURG in the seven years of the study. These numbers were responsible for 2.1% to 8.1% of the hospitalizations/year for HIV patients. All were caused by C. neoformans infection (95% C. neoformans var. grubii VNI and 5% C. neoformans var. grubii VNII). Neurocryptococcosis was the major clinical manifestation and cryptococcosis was the HIV- defining condition in 40% of patients. The period of hospitalization was an average of 39.3 days (SD = 31.3), and more than half of patients (53%; 37/70) died after a mean of 82 days.DiscussionThe present study showed the importance of cryptococcosis as an AIDS-defining disease in HIV-AIDS patients in a tertiary hospital from Southern Brazil. More investment is necessary to reduce the impact of this opportunistic mycosis in HIV-AIDS patients from southern Brazil.     

A monoclonal antibody that inhibits <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis> growth in vitro and its reaction with intracellular triosephosphate isomerase

In parasites of the order Kinetoplastida, such as Trypanosoma cruzi and Trypanosoma brucei, glycolysis is carried out by glycolytic enzymes in glycosomes. One of the glycolytic enzymes is triosephosphate isomerase (TIM), which in T. brucei is localized exclusively in glycosomes, whereas in T. cruzi, the localization of TIM has not been fully ascertained. In the present work, we made a monoclonal antibody (mAb 6-11G) against recombinant T. cruzi TIM (rTcTIM). Incubation of T. cruzi epimastigotes with the mAb inhibited parasite survival. Western blotting showed that the mAb recognized rTcTIM and a 27 kDa band in T. cruzi lysates that corresponded to TcTIM. Sera from patients with Chagas disease recognized rTcTIM and cross-reacted with human recombinant TIM. The cross reactivity between parasite and human TIM possibly contributes to the autoimmune pathogenesis of Chagas disease. Electron microscopy of T. cruzi epimastigotes with the mAb showed that TIM was located within glycosomes, in the cytoplasm, the nucleus, and the kinetoplast. Collectively, the data shed new light on T. cruzi TIM and opens perspectives for drug design.     

85-kDa protein of Trypanosoma cruzi purified by affinity chromatography used in the multiple antigen binding assay (MABA) for the diagnosis of T. cruzi infection in a Venezuelan rural community

No ideal test exists for Chagas’ disease, and better diagnostic strategies are needed. We determined the diagnostic utility of an 85-kDa Trypanosoma cruzi protein in a multiple antigen binding assay (MABA). A standardized MABA test based on concentrated trypomastigote excretory–secretory antigen (TESA) and an 85-kDa purified protein showed 100% sensitivity and specificity. In field conditions, 6/66 individuals tested in a region not thought to be endemic (Rio Brito) were identified as seropositive for T. cruzi infection with our MABA test. In parallel, an enzyme-linked immunosorbent assay based on fixed epimastigotes detected 7/66 positives, which were independently confirmed. These data suggest that the 85-kDa and TESA proteins could be used in the MABA format as a complementary tool for the diagnosis of latent Chagas’ disease. High anti-T. cruzi antibody detection rates, poor knowledge of Chagas’ disease and its vector, and the demonstration of infected vectors in the study community all suggest a significant risk of reemergence of T. cruzi infection in this region of Venezuela.     

Chronic Chagastic cardiomyopathy associated with membranoproliferative glomerulonephritis: Report of an autopsy case

An autopsy case of chronic Chagas disease, a debilitating disorder caused by persistent infection by protozoa, Trypanosoma cruzi (Tr. cruzi), is reported. The patient was a 73‐year‐old Brazilian woman of Japanese descent, who had emigrated to Japan at the age of about 40 years. She died of chronic cardiac insufficiency about 8 years after the onset of cardiac symptoms. At autopsy, the heart showed typical features of chronic Chagastic cardiomyopathy: chronic lymphocytic myocarditis with extensive fibrosis and the formation of an apical aneurysm. The pathogenic protozoa were not detected in the cardiac tissue. The kidney showed typical features of membranoproliferative glomerulonephritis (MPGN). On the basis of experimental data which suggested that chronic infection of Tr. cruzi could elicit immune complex‐mediated glomerulonephritis, we considered that the chronic persistent infection by Tr. cruzi contributed to the pathogenesis of MPGN in this patient.     

Alterations in Glucose Homeostasis in a Murine Model of Chagas Disease

Chagas disease, caused by Trypanosoma cruzi, is an important cause of morbidity and mortality primarily resulting from cardiac dysfunction, although T. cruzi infection results in inflammation and cell destruction in many organs. We found that T. cruzi (Brazil strain) infection of mice results in pancreatic inflammation and parasitism within pancreatic β-cells with apparent sparing of α cells and leads to the disruption of pancreatic islet architecture, β-cell dysfunction, and surprisingly, hypoglycemia. Blood glucose and insulin levels were reduced in infected mice during acute infection and insulin levels remained low into the chronic phase. In response to the hypoglycemia, glucagon levels 30 days postinfection were elevated, indicating normal α-cell function. Administration of L-arginine and a β-adrenergic receptor agonist (CL316, 243, respectively) resulted in a diminished insulin response during the acute and chronic phases. Insulin granules were docked, but the lack of insulin secretion suggested an inability of granules to fuse at the plasma membrane of pancreatic β-cells. In the liver, there was a concomitant reduced expression of glucose-6-phosphatase mRNA and glucose production from pyruvate (pyruvate tolerance test), demonstrating defective hepatic gluconeogenesis as a cause for the T. cruzi-induced hypoglycemia, despite reduced insulin, but elevated glucagon levels. The data establishes a complex, multi-tissue relationship between T. cruzi infection, Chagas disease, and host glucose homeostasis.Chagas disease or American trypanosomiasis, a neglected tropical disease, is the result of a persistent infection with Trypanosoma cruzi.^1,2 Not only does it remain an important cause of morbidity and mortality in Latin America, but it is now also a global disease due to immigration to non-endemic areas.³ Furthermore, T. cruzi causes opportunistic infection in the setting of immunosuppression (eg, HIV/AIDS).² Infection of humans and experimental animals results in an intense inflammatory reaction accompanied by an upregulation of inflammatory mediators.^4,5 In the heart, this results in acute myocarditis and some patients eventually develop a chronic dilated cardiomyopathy accompanied by arrhythmias, congestive heart failure, and stroke.² T. cruzi infection also results in mega syndromes predominantly observed in the gastrointestinal tract.²In the 1980s, we became interested in the interface of host glucose homeostasis and parasitic diseases and observed that T. cruzi infection of mice pre-treated with streptozotocin, which destroys the insulin producing pancreatic β-cells, displayed increased parasitemia.⁶ We also demonstrated that obese diabetic mice, null for the leptin receptor (db/db)⁷ infected with T. cruzi displayed a high parasitemia and increased mortality. It has been reported that acute T. cruzi infection of mice resulted in hypoglycemia, which in some cases was predictive of increased mortality,^8,9 however, the etiology of T.cruzi-associated hypoglycemia remains unclear.There are also reports suggesting that diabetes may be more prevalent in individuals with Chagas disease, but these are based on small clinical case series^10–14 and often there are other confounding factors such as obesity, hyperlipidemia, and poverty.^15–17 The possibility that T. cruzi infection could contribute to the diabetic state is not surprising because pathological examination of the pancreas obtained from infected mice and humans revealed morphological and physiological alterations.^18–21 In addition, because of the interrelationship between the adipocyte and glucose metabolism, we examined the contributions of adipose tissue and the adipocyte in the pathogenesis of T. cruzi infection.^8,22,23 In this regard, we established that adipose tissue and adipocytes are important early targets, as well as a reservoir site for the parasite.^8,23,24 Infection of mice with T. cruzi resulted in inflammation of adipose tissue and an upregulation of inflammatory mediators,^8,22,23 suggesting that the adipocyte-pancreatic axis (ie, the adipo-insular axis) could also be impaired by T. cruzi infection.The role of the pancreas in T. cruzi infection has received limited attention in Chagas disease pathogenesis.^18,19,21 Herein, we report that T. cruzi-infection induces inflammation and parasitism of the pancreas, including the pancreatic β-cell. Furthermore, physiological studies strongly suggest that there is an impairment of both pancreatic function and hepatic gluconeogenesis. Alterations in glucose homeostasis in the setting of T. cruzi infection appear to be multifactorial and complex.     

Autoimmune Pathogenesis of Chagas Heart Disease: Looking Back,Looking Ahead

Chagas heart disease is an inflammatory cardiomyopathy that develops in approximately one-third of individuals infected with the protozoan parasite Trypanosoma cruzi. Since the discovery of T. cruzi by Carlos Chagas >100 years ago, much has been learned about Chagas disease pathogenesis; however, the outcome of T. cruzi infection is highly variable and difficult to predict. Many mechanisms have been proposed to promote tissue inflammation, but the determinants and the relative importance of each have yet to be fully elucidated. The notion that some factor other than the parasite significantly contributes to the development of myocarditis was hypothesized by the first physician-scientists who noted the conspicuous absence of parasites in the hearts of those who succumbed to Chagas disease. One of these factors—autoimmunity—has been extensively studied for more than half a century. Although questions regarding the functional role of autoimmunity in the pathogenesis of Chagas disease remain unanswered, the development of autoimmune responses during infection clearly occurs in some individuals, and the implications that this autoimmunity may be pathogenic are significant. In this review, we summarize what is known about the pathogenesis of Chagas heart disease and conclude with a view of the future of Chagas disease diagnosis, pathogenesis, therapy, and prevention, emphasizing recent advances in these areas that aid in the management of Chagas disease.Chagas disease, caused by infection with the protozoan parasite Trypanosoma cruzi, is a neglected tropical disease that affects up to 10 million people worldwide. The disease is endemic in vast areas of the western hemisphere from the United States to Argentina, and many thousands of T. cruzi–infected individuals also reside in Canada, Europe, Japan, and Australia.¹ Although most infected individuals will experience a lifelong subclinical infection, approximately one-third will develop a potentially fatal inflammatory cardiomyopathy and/or megadisease of the gastrointestinal tract. Since the discovery of the illness and its causative agent by Chagas in 1909,² there has been extensive basic, translational, and clinical research on this important disease, which has led to the development of several successful strategies for public health intervention and informed approaches to vaccine development and drug discovery. Among the features of this disease, perhaps the most interesting is also the most understated—the tremendous variability in the outcome of infection, largely determined by genetic heterogeneity in both the virulence of specific T. cruzi strains and the susceptibility of a specific individual to infection. This unpredictable variability, compounded by differential effects of the physiological state of both parasite and host on the outcome of infection, has complicated efforts to treat and cure Chagas disease for decades.Trypanosoma cruzi infection is often characterized as having distinct acute, indeterminate, and chronic phases. Although this convention is widely used, we believe that it is easier to understand the course of infection as conveyed by our modification of a scheme by Rosenbaum (Figure 1).³ After infection through contact with trypanosome-containing excreta from the reduviid bug vector that transmits T. cruzi, consumption of food or beverages contaminated with excreta, or transfusion/transplantation of blood/tissue from an infected donor, the parasite goes through several rounds of host cell invasion, division, and cell lysis for up to several weeks. During this time, parasites can often be detected in the blood. However, most infected individuals demonstrate little, if any, indication of being infected. These are included in the 99% subclinical group (Figure 1), even though some may develop non-specific symptoms, including anorexia, chills, diarrhea, drowsiness, fever, lethargy, lymphadenopathy, and swelling near the infection site.⁴ Approximately 1% of the infected individuals, mostly children, develop clinically apparent myocarditis; most recover, but a few (1% to 5%) develop fatal complications, including acute heart failure, fatal dysrhythmias, or fulminating meningoencephalitis.⁴ Morbidity and mortality during acute infection can be much higher in some cases. In two microepidemics in northeastern Brazil caused by consumption of T. cruzi–contaminated food, 12 of 13 infected individuals developed fever and dyspnea, 5 developed congestive heart failure, and 2 died.⁵Open in a separate windowFigure 1Clinical course of Trypanosoma cruzi infection. During the acute phase of infection, nearly all individuals are unaware of infection, having no signs or symptoms of infection; mild and/or non-specific signs and symptoms, such as anorexia, fever, fatigue, or lymphadenopathy; or more specific, if not pathognomonic, signs of recent infection, such as unilateral periorbital edema (Romaña sign). A few individuals (approximately 1%), usually children in endemic regions, develop clinically apparent myocarditis, which normally resolves within several weeks; a few of these children (0.01% to 0.05%) succumb to myocarditis, typically due to fatal dysrhythmias. After this acute phase of a few months'' duration, virtually all infected individuals harbor subclinical (silent) disease for a variable time (several years). From that point forward, approximately 30% of infected individuals develop cardiomyopathy or megadisease during the next several decades, with approximately one-third of these (ie, 10%) with clinically apparent, symptomatic disease above the clinical threshold. Approximately 20% develop organ dysfunction that is detectable through clinical testing. Most (approximately 70%) have lifelong infection with no organ dysfunction. This figure was adapted from Rosenbaum,³ copyright 1964, with permission from Elsevier. The percentages given in this figure are rough estimates, and the outcome of infection may vary greatly depending on variables.In most immunocompetent individuals, parasite-specific adaptive immunity is generally sufficient to keep the parasite at low or undetectable levels. This is the indeterminate phase of Chagas disease. Beginning a variable time after infection (Figure 1), and extending for decades, approximately 30% will develop chronic Chagas disease, which primarily affects the heart and gastrointestinal tract, but may also involve the nervous and endocrine systems.^6,7 Approximately one-third of these individuals will have clinically overt cardiomyopathy, typically manifested as congestive heart failure, whereas two-thirds will develop subclinical Chagas disease that is detectable via several diagnostic modalities. Death from chronic Chagas disease is often the result of congestive heart failure after gradual development of myocardial dysfunction due to damage caused by chronic inflammation.^6,7In chronic Chagas heart disease (CHD), cardiac myocytes undergo necrosis and cytolysis via various mechanisms, and areas of myocellular hypertrophy and mononuclear cell infiltration develop in the cardiac tissue, with fewer macrophages, eosinophils, neutrophils, and mast cells.^4,8–10 Fibrosis develops in response to myocardial damage. This remodeling may disrupt the cardiac conduction system, leading to dysrhythmias as well as myocardial thinning and cardiac hypertrophy.⁴ Although parasite DNA or antigen can be detected in some inflammatory lesions, intact parasites are frequently absent from the heart in chronic CHD.¹¹ In addition to the histopathological changes mentioned earlier in this paragraph, development of occlusive thrombi, apical aneurysm of the dilated left ventricle, decreased contractility of muscle fibers, and destruction of the cardiac conduction system are also commonly found. The associated muscle damage leads to dilation and cardiac dysrhythmias, high-degree heart block, and, ultimately, congestive heart failure, which is the leading cause of death in chronic CHD patients.¹²Diagnosis of acute T. cruzi infection may be made by microscopic analysis of whole blood or buffy coat for the presence of motile bloodform trypomastigotes released from host cells after initial rounds of replication. In chronic Chagas patients, enzyme-linked immunosorbent assay, indirect hemagglutination, or indirect immunofluorescence can be used to test for the presence of T. cruzi–specific IgG in sera.⁴ Large-scale screening of the blood supply is underway in many parts of the western hemisphere, with a variety of commercial/industrial immunoassays used; however, several areas with at-risk populations still do not routinely screen all blood products.¹³To date, only two anti–T. cruzi drug treatments are available, nifurtimox and benznidazole, both of which oxidize the parasite''s nucleotide pool, leading to lethal double-stranded DNA breaks. Proper administration of either of these drugs can successfully ameliorate the symptoms of Chagas disease in many individuals, especially those experiencing the acute form of the disease. However, existing treatments for Chagas disease have limited efficacy in certain populations because they require repeated administration over a prolonged time period, and often produce severe adverse effects that cannot be tolerated by all individuals. These characteristics likely suppress compliance with treatment, and subsequently delay resolution of this substantial public health burden. Although the treatment of chronically infected individuals is somewhat controversial, given that most will never develop organ dysfunction, the Latin American Network for Chagas Disease now recommends treatment for all chronically infected individuals.¹⁴ Heart transplantation may also be performed on patients with severe chronic CHD experiencing congestive heart failure; however, the reappearance of T. cruzi infection may occur with immunosuppressive therapy after the transplantation procedure. Currently, no effective vaccine is available for preventing T. cruzi infection, although many share the view that the outlook is more promising now than in the past.¹⁵