Possible role of an adrenal parasite reservoir in the pathogenesis of chronic Trypanosoma cruzi myocarditis

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.

Tuberculosis of the adrenal gland: a case report and review of the literature of infections of the adrenal gland

Infections of the adrenal glands remain an important cause of adrenal insufficiency, especially in the developing world. Indeed, when Thomas Addison first described the condition that now bears his name over 150 years ago, the vast majority of cases were attributable to tuberculosis. Here we describe a classic, but relatively uncommon, presentation in the United States of adrenal insufficiency followed by a review of the current literature pertaining to adrenal infections.

Trypanosomiasis

African (sleeping sickness) and American (Chagas' disease) trypanosomiasis, caused by protozoa of the family Trypanosomatidae, are diseases that are endemic in parts of Africa and Latin America, respectively. Physicians in developed countries may occasionally see cases because of extensive travel and immigration from endemic countries. Although neurological involvement is common in both, its incidence and clinical presentation differ considerably. African trypanosomiasis, caused by subspecies of Trypanosoma brucei (T b rhodesiense, T b gambiense), is transmitted by the tsetse fly and causes meningoencephalitis, in which somnolence is a prominent feature. Parasites may reach the brain parenchyma through the choroid plexus or the Virchow Robin spaces. American trypanosomiasis, caused by Trypanosoma cruzi is transmitted by reduviid bugs. While lesions in the central nervous system are not prominent, except in the reactivated forms which occur in immunodeficient patients, the peripheral nerve, mainly the autonomic nervous system, is frequently involved, leading to the cardiomegaly and the digestive megaviscera. Congenital infections may also occur. In this paper we give an account of the epidemiology, clinical presentation and pathological features of these two protozoal infections based on human and experimental studies of both the central and peripheral nervous system.

An update on the management of Chagas cardiomyopathy

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, infects nearly 18 million people in Latin America and mainly affects the heart, causing heart failure, arrhythmias, heart block, thromboembolism, stroke and death. In this review, the clinical diagnosis and management of Chagas cardiomyopathy are discussed. Particular emphasis is placed on the clinical staging of patients and the use of various diagnostic tests that may be useful in individualizing treatment of the two most relevant clinical syndromes, that is, heart failure and arrhythmias. The relevance of specific treatments are discussed, stressing the important role of parasite persistence in disease pathogenesis. We also discuss new therapy modalities that may have a role in the treatment of Chagas cardiomyopathy.

Adrenal infections

Adrenal infections are an important but under-recognized clinical entity. The adrenal gland can be infected by a myriad of pathogens including fungi, viruses, parasites, and bacteria. Infection can directly or indirectly cause tissue damage and alteration in endocrine function. Direct damage occurs via microbial replication and local production of toxic compounds, such as endotoxins. Indirect damage results from alterations in the regulation of a host's immunologic and endocrine mediators in response to damage by a microbe at a distant site. Variations in pathogen tropism, adrenal anatomy, and host immune integrity contribute to the progression of active disease and discernable adrenal dysfunction. Early recognition and intervention in the case of adrenal infection can significantly improve outcome, demonstrating the need for increased clinical suspicion in the appropriate clinical setting.

Trypanosoma cruzi-induced molecular mimicry and Chagas' disease

Chagas' disease, caused by Trypanosoma cruzi, has been considered a paradigm of infection-induced autoimmune disease. Thus, the scarcity of parasites in the chronic phase of the disease contrasts with the severe cardiac pathology observed in approximately 30% of chronic patients and suggested a role for autoimmunity as the origin of the pathology. Antigen-specific and antigen-non-specific mechanisms have been described by which T. cruzi infection might activate T and B cells, leading to autoimmunity. Among the first mechanisms, molecular mimicry has been claimed as the most important mechanism leading to autoimmunity and pathology in the chronic phase of this disease. In this regard, various T. cruzi antigens, such as B13, cruzipain and Cha, cross-react with host antigens at the B or T cell level and their role in pathogenesis has been widely studied. Immunization with those antigens and/or passive transfer of autoreactive T lymphocytes in mice lead to clinical disturbances similar to those found in Chagas' disease patients. On the other hand, the parasite is becoming increasingly detected in chronically infected hosts and may also be the cause of pathology either directly or through parasite-specific mediated inflammatory responses. Thus, the issue of autoimmunity versus parasite persistence as the cause of Chagas' disease pathology is hotly debated among many researchers in the field. We critically review here the evidence in favor of and against autoimmunity through molecular mimicry as responsible for Chagas' disease pathology from clinical, pathological and immunological perspectives.

Myocardiocyte apoptosis in heart failure in chronic Chagas' disease

Chagas' disease is caused by the parasite Trypanosoma cruzi. The disease affects 16-18 million patients in South America and heart involvement is the major cause of morbidity and mortality of the disease. The myocarditis observed during the chronic phase affects patients independently of the clinical manifestation, although patients with heart failure present an intense degree of myocarditis and fibrosis. To address the pathogenesis of heart failure in Chagas' disease, we investigated the role of myocardial cell loss by apoptosis in patients in the chronic phase of Chagas' disease. Apoptosis was also evaluated in inflammatory cells. Twenty-two specimens of the left ventricle were obtained during autopsies. Eleven samples from patients with heart failure and equal number from patients without heart failure. The material was analyzed by TUNEL methods to identify early apoptotic events and fibrosis was evaluated on HE-stained slides. In patients with heart failure, the extent of fibrosis and the number of apoptotic myocardial and inflammatory cells were significantly higher than in specimens obtained from patients without heart failure. These results suggest that myocardial cell loss by apoptosis and fibrosis contribute to heart failure in the chronic phase of Chagas' disease.

[Frequency of diabetes mellitus and hyperglycemia in chagasic and non-chagasic women]

Medical records of > or = 40 years old female seen at University Hospital from June/93 to July/95 were submitted to a cross-sectional study. According to Chagas' disease tests, patients were divided into chagasic (n = 362) and controls (n = 285). Diabetes mellitus was defined on the basis of two fasting blood glucose levels > or = 140 mg/dl and hyperglycemia as fasting blood glucose > 110 mg/dl. Chagasic patients were divided into groups with the cardiac form of the disease (n = 179), with megas (n = 58), and asymptomatic (n = 125). Groups were compared by the chi 2 test, analysis of variance, Student's "t" test, and Kruskal-Wallis and Mann-Whitney tests. A significant difference was assumed when p < 0.05. Chagasic and control groups were matched for age, white color and body mass index. Diabetes mellitus was more prevalent in patients with the cardiac form of Chagas' disease than in controls, or patients with the megas or the asymptomatic form (15.1%, 7.4%, 7.4%, and 5.6%, respectively); the same was observed for hyperglycemia (37.4%, 26.7%, 25.9%, 27.2%), in agreement with the hypothesis that the reduced parasympathetic activity caused by Trypanosoma cruzi leads to relative sympathetic hyperactivity.

[The weight of the spleen in chronic chagasics]

During the course of systemic inflammatory reactions and chronic venous congestion, the documented phenomenon of increased spleen size is respectively called reactional hyperplasia and congestive splenomegaly. In Chagas' disease, the inflammatory process observed in the heart of chronically infected patients can result in heart failure and ultimately in congestive failure. In order to evaluate the spleen response to both inflammatory and cardiac processes, in this retrospective study we compare the weight of spleens from normal and chagasic patients, with or without congestive failure. Information about patient age, sex, race and spleen weight was collected from autopsy reports. Eighty-eight selected cases were divided into four groups: 1) chagasic patients with congestive failure, 2) chagasic patients without congestive failure, 3) non-chagasic patients with congestive failure, 4) non-chagasic patients without congestive failure. The average age was 44.9 +/- 15.4 years, 53.4% were Caucasians and 70.5% were males, and no significant difference in these parameters was observed between the four groups. The spleen weight for the groups presenting congestive failure was 183.7 +/- 85.9 g for chagasic and 206.3 +/- 101.0 g for non-chagasic patients; for the groups without congestive failure the average spleen weight was 173.7 +/- 118.9 g for the chagasic and 117.2 +/- 52.0 g for non-chagasic patients. The spleen weight was significantly higher for the chagasic patients without congestive failure when compared to the non-chagasic group without congestive failure. These results suggest that the inflammatory component in Chagas' disease plays an important role in the increase of spleen weight together with hemodynamic alterations arising from congestive heart failure.

Chronic chagasic cardiopathy: the product of a turbulent host-parasite relationship

The pathogenesis of chronic chagasic cardiopathy is still a debated matter. In this review, the main theories raised about it since the first description of the disease in 1909 by Carlos Chagas, are considered. The scarcity of T.cruzi parasites into the myocardium and the apparent lack of correlation between their presence and the occurrence of myocardial inflammatory infiltrate, have originated many theories indicating that chronic Chagas' cardiopathy is an autoimmune disease. Recently however, papers using immunohistochemical technique or PCR have demonstrated a strong association between moderate or severe myocarditis and presence of T.cruzi Ags, indicating a direct participation of the parasite in the genesis of chronic chagasic myocarditis. Different patterns of cytokine production seem to have important role in the outcome of the disease. Participation of the microcirculatory alterations and fibrosis as well as the relationship with the parasite are also emphasized. Finally, the author suggests that the indeterminate form of the disease occurs when the host immunological response against the parasite is more efficient while the chronic cardiopathy occurs in patients with hyperergic and inefficient immune response.