Trypanosoma cruzi modulates lipid metabolism and highjacks phospholipids from the midgut of Rhodnius prolixus.

Chagas disease is potentially life-threatening and caused by the protozoan parasite Trypanosoma cruzi. The parasite cannot synthesize some lipids and depends on the uptake of these lipids from its vertebrate and invertebrate hosts. To achieve this, T. cruzi may need to modify the physiology of the insect host for its own benefit. In this study, we investigated the interaction of T. cruzi (Y strain) with its insect vector Rhodnius prolixus and how it manipulates the vector lipid metabolism. We observed a physiological change in lipid flux in of infected insects. In the fat body of infected insects, triacylglycerol levels decreased by 80.6% and lipid storage droplet-1(LSD-1) mRNA levels were lower, when compared to controls. Lipid sequestration by infected midguts led to increased levels of 5' AMP-activated protein kinase (AMPK) phosphorylation and activation in the fat body, inhibiting the synthesis of fatty acids and stimulating their oxidation. This led to reduced lipid levels in the fat body of infected insets, despite the fact that T. cruzi does not colonize this tissue. There was a 3-fold increase, in lipid uptake and synthesis in the midgut of infected insects. Finally, our results suggest that the parasite modifies the lipid flux and metabolism of its vector R. prolixus through the increase in lipid delivery from the fat body to midgut that are then scavenge by T cruzi.

Dosage compensation in sciarids is achieved by hypertranscription of the single X chromosome in males.

Dosage compensation refers to the process whereby females and males with different doses of sex chromosomes have similar amounts of products from sex chromosome-linked genes. We analyzed the process of dosage compensation in Sciara ocellaris, Diptera of the suborder Nematocera. By autoradiography and measurements of X-linked rRNA in females (XX) and males (XO), we found that the rate of transcription of the single X chromosome in males is similar to that of the two X chromosomes in females. This, together with the bloated appearance of the X chromosome in males, support the idea that in sciarids dosage compensation is accomplished by hypertranscription of the X chromosome in males.

Agreement between histopathological results in clinically diagnosed cases of indeterminate leprosy in São Paulo, Brazil.

Histopathological slides from skin biopsies of fifty-seven self-reporting patients diagnosed as indeterminate leprosy by the Leprosy Control Programme in São Paulo, were sent to three independent histopathologists. Agreement between the reports were based on the following diagnosis: "indeterminate leprosy", "suggestive leprosy" or "no leprosy". A great variation was observed in the interpretation of the histopathological examination. The three pathologists reported "indeterminate leprosy" respectively in 7.0%, 54.4% and 84.2%, of the cases studied. A kappa index of agreement between any two pathologists ranged from 0.08 to 0.32, showing poor agreement between observers. Agreement improved by pooling together the reports "suggestive leprosy" and "indeterminate leprosy". The three pathologists agreed in the results of 24 biopsies of the 27 classified as leprosy by any one of the three observers. Eight cases were considered as "no leprosy" by all pathologists. Higher agreement indices were obtained for positive and negative proportionate concordance between any two examiners. The implications of the variation in the diagnosis of indeterminate leprosy and early leprosy are discussed in the context of public health and case-management.

Environmental risk factors in endemic pemphigus foliaceus (Fogo selvagem). "The Cooperative Group on Fogo Selvagem Research".

Endemic pemphigus foliaceus or Fogo selvagem (FS) is an epidermal organ-specific autoimmune disease mediated by autoantibodies. Individuals at risk are peasants who live and work on farms located in the interior of certain endemic states of Brazil. This case-control study compares a group of 52 FS patients with 52 patients suffering from other dermatoses admitted and followed at the hospital for pemphigus (Hospital do Penfigo) in the city of Goiania, state of Goias. Patients and controls matched 1:1 by age, sex, and occupation were examined by two dermatologists at the time of admission and asked to respond to a prepared questionnaire. This questionnaire concerned current and past (1 and 5 years) exposure to environmental risk factors. The following risk factors were assessed: black fly bites, presence of rodents at home, exposure to cereal dust, exposure to fumes or dust released by tree and shrub removal, and exposure to insecticides. Relative risks were estimated from tabulated data by the odds ratio and tested for significance by the chi-square test. The 95% confidence interval for the odds ratio was also calculated for each of the risk factors. The only risk factor showing an odds ratio significantly different from one was exposure to simuliidae bites (odds ratio 4.7, p less than 0.001). This study reinforces the hypothesis that chronic exposure to black fly antigens may precipitate IgG4 antibody formation in predisposed individuals. These antibodies in turn may cross-react with epidermal antigens and cause acantholysis and the clinical expression of the disease known as FS.

Endemic pemphigus foliaceus (fogo selvagem). I. Clinical features and immunopathology.

Endemic pemphigus foliaceus is an autoimmune disease that has remarkable features. Endemic foci are found in characteristic environments within the interior of Brazil. The epidemiologic data strongly suggest that an environmental factor initiates the autoantibody response in the host. As such it is an important disease for in-depth study. A group of interested investigators in both Brazil and the United States has been formed to attempt to do just that. As part of the overall effort, this Cooperative Research Group for the Study of Fogo Selvagem presents a definition of the disease, a proposed clinical classification for various forms of the disease, and an outline of what is currently known of its immunopathologic characteristics.

Endemic pemphigus foliaceus (Fogo Selvagem): II. Current and historic epidemiologic studies.

This paper details current and historic epidemiologic features of Fogo Selvagem (Endemic pemphigus foliaceus) in Brazil. The following features are described. a) The disease occurs in endemic fashion in regions of Brazil within the states of Goias, Mato Grosso do Sul, Parana, Sao Paulo, and Minas Gerais. It appears that the disease is spreading toward the northwest and west, involving the states of Mato Grosso, Para, Maranhao, Rondonia, Acre, and Amazonas. b) People at risk are young peasants or children of either sex or any race exposed to the local ecology in rural areas of endemic states. Although the disease has been described in urban centers, these occurrences are rare. c) Fogo Selvagem commonly appears in wild areas being colonized and disappears as these areas become urbanized. d) The majority of patients live in close proximity to rivers and within the 10-15 Km flying range of mosquitos or black flies (such as Simulium). It is hypothesized that a black fly, Simulium pruinosum may be the vector that precipitates the disease. f) There is a significant number of Fogo Selvagem in family units where multiple, genetically related individuals are affected. g) Finally, autoantibodies against lupus-associated antigens are not present in the sera of patients with Fogo Selvagem. Clinical examination of the skin, and serologic screening for pemphigus autoantibodies are specific parameters that can be used in the search for the etiologic agents that lead to autoimmune disease of the skin. To identify and prove an etiologic agent for this well-characterized autoimmune disease would be of tremendous importance to the understanding of autoimmune skin diseases, and potentially other organ-specific autoimmune disorders.

Serologic abnormalities in patients with endemic pemphigus foliaceus (Fogo selvagem), their relatives, and normal donors from endemic and non-endemic areas of Brazil.

Based on epidemiologic data, a current hypothesis states that Fogo selvagem (FS) may be triggered by environmental factors present in endemic areas of Brazil. Because the appearance of new cases is limited to those areas, we wanted to ascertain if the presence of the pemphigus autoantibodies was restricted to the patients. To further delineate the restriction of the autoantibody response in these patients we also investigated the presence of lupus-associated autoantibodies. Using indirect immunofluorescence (IF) we tested the sera of patients with FS (n = 196), their relatives (n = 138), their cohabitants (n = 13), and normal donors from endemic (n = 38) and non-endemic areas (n = 44) for pemphigus autoantibodies. Antinuclear antibodies (ANA) and anti-nDNA antibodies were determined by indirect IF against Hep-2 cells and Crithidia lucilliae, respectively. Autoantibodies against nRNP, Ro/SSA, La/SSB, and Sm were assayed by double immune diffusion in agarose gels. FS autoantibodies were present in the sera of all patients with active disease (n = 196, 100%, titers greater than 40 to 2560), but were not found in any sera from normal individuals in endemic or non-endemic areas. The titer of the FS autoantibody showed a rough correlation with the extent and activity of the disease. Furthermore, lupus-associated autoantibodies were not present in any of the tested samples. We conclude the FS antiepidermal autoantibodies are specific serologic markers of the disease and are not present in unaffected individual from the endemic areas. As such, they provide an important marker that should be useful in ongoing epidemiologic studies aimed at identifying putative etiologic agent(s).

[Immunopathogeny of pemphigus]. / La inmunopatogenia de los pénfigos.

This article reviews recent concepts of pathogenetic mechanisms in pemphigus. We describe the pathogenic effect of the autoantibodies, the animal model for the disease and the ultrastructural alterations which follow the antibody-antigen interaction. The role of complement and protease systems in development of tissue injury are also discussed.