Gene network analysis during early infection of human coronary artery smooth muscle cells by Trypanosoma cruzi and Its gp83 ligand.

Trypanosoma cruzi, the causative agent of Chagas' disease, infects heart and muscle cells leading to cardiac arrest, followed by death. The genetic architectures in the early T. cruzi infection process of human cells are unknown. To understand the genetic architectures of the early invasion process of T. cruzi, we conducted gene transcription microarray analysis, followed by gene network construction of the host cell response in primary human coronary artery smooth muscle (HCASM) cells infected with T. cruzi or exposed to T. cruzi gp83, a ligand used by the trypanosome to bind host cells. Using seven RT-PCR verified up-regulated genes (FOSB, ATF5, INPP1, CCND2, THBS1, LAMC1, and APLP2) as the seed for network construction, we built an interaction network of the early T. cruzi infection process containing 165 genes, connected by 598 biological interactions. This interactome network is centered on the BCL6 gene as a hub. Silencing the expression of two seed genes (THBS1 and LAMC1) by RNAi reduced T. cruzi infection. Overall, our results elucidate the significant and complex process involved in T. cruzi infection of HCASM cells at the transcriptome level. This is the first elucidation into the interactome network in human cells caused by T. cruzi and its gp83 ligand.

Human galectin-3 promotes Trypanosoma cruzi adhesion to human coronary artery smooth muscle cells.

Human galectin-3 binds to the surface of Trypanosoma cruzi trypomastigotes and human coronary artery smooth muscle (CASM) cells. CASM cells express galectin-3 on their surface and secrete it. Exogenous galectin-3 increased the binding of T. cruzi to CASM cells. Trypanosome binding to CASM cells was enhanced when either T. cruzi or CASM cells were preincubated with galectin-3. Cells stably transfected with galectin-3 antisense show a dramatic decrease in galectin-3 expression and very little T. cruzi adhesion to cells. The addition of galectin-3 to these cells restores their initial capacity to bind to trypanosomes. Thus, host galectin-3 expression is required for T. cruzi adhesion to human cells and exogenous galectin-3 enhances this process, leading to parasite entry.

Myocardial expression of endothelin-1 in murine Trypanosoma cruzi infection.

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of myocarditis and chronic cardiomyopathy and is accompanied by microvascular spasm and myocardial ischemia. We reported previously that infection of cultured endothelial cells with T. cruzi increased the synthesis of biologically active endothlein-1 (ET-1). In the present study, we examined the role of ET-1 in the cardiovascular system of CD1 mice infected with the Brazil strain of T. cruzi and C57BL/6 mice infected with the Tulahuen strain during acute infection. In the myocardium of infected mice myonecrosis and multiple pseudocysts were observed. There was also an intense vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium. Immunohistochemistry studies employing anti-ET-1 antibody revealed increased expression of ET-1 that was most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for preproET-1, endothelin converting enzyme and ET-1 were observed in the same myocardial samples. Plasma ET-1 levels were significantly elevated in infected CD1 mice 10-15 days post infection. These observations suggest that increased levels of ET-1 are a consequence of the initial invasion of the cardiovascular system and provide a mechanism for infection-associated myocardial dysfunction.

Localization of Borrelia burgdorferi in murine Lyme borreliosis by electron microscopy.

Lyme borreliosis is a newly recognized systemic infection with protean clinical manifestations. Because the localization of the causative spirochete (Borrelia burgdorferi) in infected tissues is unknown, we used electron microscopy to find spirochetes in the hearts of chronically infected mice. There were three predominant locations for the spirochete in the hearts. In mice infected for one month or less, the spirochetes were mostly in or around blood vessels. They were either in the lumen or in the perivascular space. Mice infected for more than one month had B. burgdorferi in cardiac myocytes as well, often with clear spaces around them. The third area in which spirochetes were common was collagen fibers; the borreliae were wrapped around fibers with their long axis parallel to the fibers. The number of spirochetes was relatively low, but there was no appreciable decrease in numbers of spirochetes with increasing time postinfection. Inflammatory infiltrates were primarily in the endocardium and pericardium, but spirochetes were generally not in or near areas of inflammation. These data are consistent with previously published information that have identified the heart as a site of chronic infection and inflammation in the mouse. The studies extend our understanding of the behavior of the spirochete in vivo by identifying common locations of B. burgdorferi and by noting the disparity between infection and inflammation.

Analysis of body-length distribution of Dirofilaria immitis in the cardio-pulmonary blood vessel of naturally infected dogs in Shiga Prefecture, Japan.

Body-length frequencies of Dirofilaria immitis collected from the cardio-pulmonary blood vessel of the dogs were studied in Shiga Prefecture. Japan, in October 1983 and in January and May 1984. The frequencies were not distributed normally because they included the populations of shorter-bodied worms, probably the growing younger worms, whereas the distributions of the body length of worms collected in July 1983 were proved to fit the single normal distribution. From the results of body-length distribution analysis, the worms collected in different seasons were each composed of 1 to 3 groups with different mean body-lengths, standard deviations and composition rates and successive changes were observed in the distribution patterns. According to the analysis of population structures, the infective season was estimated to range from April or May to October or November in 1983 from the respective ages of shorter-bodied worm groups. The annual rates of first infection and re-infection in 1983 determined by the population of shorter-bodied females collected in January were 48% and 93% respectively and the number of newly infecting females per dog ranged from 1 to 27 with a geometric mean of 8.5. The numbers of newly infecting female worms were distributed following the negative binomial and Poisson distributions in newly infected and already infected dogs respectively.

Microvascular sequestration of parasitized erythrocytes in human falciparum malaria: a pathological study.

Thirty-nine falciparum malaria autopsy cases from the Hospital for Tropical Diseases, Mahidol University, Bangkok, Thailand were divided into two groups that had had either cerebral malaria (CM) or non-cerebral malaria (NCM). We then studied significant pathological differences between these groups in order to investigate the correlation between parasitized erythrocyte (PRBC) sequestration in small blood vessels in the brain, heart, lungs and small intestines. We found that the percentage of PRBC sequestration in the organs which we studied was higher in the CM patients than in the NCM patients. The difference of PRBC sequestration among the organs of two groups was significant (P less than 0.05). In the CM group, the average percentage of PRBC sequestration in the brain was significantly higher than in the heart, lungs and small intestines (P less than 0.05). No statistically significant difference was found between PRBC sequestration in the brains, hearts, lungs and small intestines in the NCM group (P greater than 0.05). Our study indicates that severity of malaria in the CM patients depends on PRBC sequestration, especially in the brain. A combination of functional disturbances of the other organs, in addition to the cerebral pathology, may augment the severity of the disease.

Enhanced platelet adherence and aggregation in Chagas' disease: a potential pathogenic mechanism for cardiomyopathy.

Spasm and thrombosis of the coronary microcirculation has been implicated in the pathogenesis of the cardiomyopathy of Chagas' disease. We demonstrate that increases in platelet adherence and aggregation accompany Trypanosoma cruzi infection and may contribute to the observed microvascular pathology. Scanning electron microscopy and radiolabeled platelets studies revealed that platelet adherence to T. cruzi-infected human endothelial cells was significantly increased when compared to controls (P = 0.024). In in vitro experiments, we determined the influence of infection on prostacyclin production, a marker of endothelial cell perturbation. The basal levels of 6-keto-prostaglandin F1 alpha was significantly greater in the supernatant of infected endothelial cells than in those of uninfected endothelial cells (P less than 0.05). The influence of infection was assessed on platelet aggregation at days 5 and 12 post-infection in A/J mice. Platelets from T. cruzi-infected mice were 2-6-fold more sensitive to aggregation induced by adenosine diphosphate and sodium arachidonate than controls. Thromboxane B2 levels in the plasma of infected mice were greater than controls. These data support the hypothesis that heightened platelet reactivity and endothelial cell dysfunction are associated with acute Chagas' disease and may cause coronary microvascular spasm and/or occlusion.

Parasitic protozoa of the blood of rodents. VI. Two new hemogregarines of the pygmy flying squirrel Idiurus macrotis (Rodentia: Theridomyomorpha: Anomaluridae) in West Africa.

Descriptions are given of two new species of Hepatozoon Miller, 1908 found in the pygmy squirrel, Idiurus macrotis, in the Ivory Coast. Gamonts of both are parasites of monocytes. The size and shape of the gamonts of one, H. normani n. sp., are similar to those of a number of gamonts of other species of rodent hemogregarines and the separate identity of the parasite is based on the host restriction of mammalian hemogregarines. The gamonts of the other species, H. dolichomorphon n. sp., are remarkably long and slender and are unlike those of any other known hemogregarine of mammals. Schizonts of this species were found in a smear prepared from heart blood.

The pathogenesis of experimentally induced Trypanosoma brucei infection in the dog. I. Tissue and organ damage.

Inoculation of dogs with Trypanosoma brucei produced an acute fetal disease similar to that seen following natural infection. The disease was characterised by high levels of parasitaemia, moderately severe anemia, and marked changes in the lymphoid system. Extravascular invasion by large numbers of trypanosomes was widespread throughout the body and was accompanied by severe tissue damage. Tissue invasion by trypanosomes was associated with marked cellular infiltration involving lymphoid cells and plasma cells followed by macrophages and polymorphonuclear leukocytes. Associated with these reactions, severe cellular degeneration and focal necrosis occurred. While these changes were widespread and were found in the majority of tissues examined, consistently severe lesions were found in the heart, eyes and central nervous system. In many organs, lymphatic vessels were distended with fluid, trypanosomes, and a cell population similar to that in the surrounding tissue; fibrin deposition and thrombus formation was sometimes observed within the lymphatic lumens. Thrombosis was also found in the blood vessels of the pampiniform plexus, the venous plexus of the ovary, and branches of the renal vein. A severe necrotizing vasculitis affecting only the coronary vessels was a prominent feature in some animals.

Surgical treatment of coronary insufficiency produced by cardiac echinococcosis.

We report two cases in which the pertinent angiographic studies disclosed the presence of hydatid cysts of the left ventricle, producing complete obstruction of the left anterior descending coronary artery in one patient and of the left anterior descending coronary artery and the circumflex coronary artery in the other patient. Both patients were successfully treated by excision of the cyst and myocardial revascularization with saphenous venous bypass grafts. From the analysis of symptoms in cardiac echinococcosis, we concluded that precordial pain is the most common complaint, that it can be due to coronary insufficiency, and that at the present, coronary angiographic studies have to be performed systematically in these patients, since coronary involvement by the cyst can explain some of the clinical manifestations and complications of the disease and can also influence its surgical management.