Manson's schistosomiasis in the undernourished mouse: some recent findings

This paper deals with current knowledge of the interrelationships between Schistosoma infection and malnutrition. It emphasizes the relevance of these investigations in the face of dynamic and evolving changes occurring in population diets and changes in the epidemiological patterns of schistosomiasis in endemic countries. The paper further discusses the basis for continuing the studies on this subject and the reasons why it represents a misunderstood association. This review also focuses on the cellular and humoral immune responses in the undernourished mouse model infected with Schistosoma mansoni, with updated information on the immune response in wild-type and iNOS knockout mice concerning soluble egg antigen specific antibodies and kinetics of IFN-ã, IL-4, IL-10 and IL-13 cytokines, in the chronic phase of Manson's schistosomiasis. There is indication that schistosome-infected undernourished mice are able to develop a humoral immune response, but antibody titres are much lower than in the control animals. Cytokine production (IFN-ã, IL-4, IL-10) is lower in the undernourished mice, but as infection progresses to the chronic phase its kinetics run an antagonistic course when compared to that of well-nourished animals. Marked variation in the secretion of IL-13 (a fibrogenic cytokine) could explain why undernourished mice do not develop liver "pipe-stem" fibrosis described in previous papers on well-nourished animals.

Preliminary results on interleukin-4 and interleukin-10 cytokine production in malnourished, inducible nitric oxide synthase-deficient mice with schistosomiasis mansoni infection

Schistosoma mansoni infected C57Bl/6 inducible nitric oxide synthase (iNOS)-deficient and non-deficient malnourished mice, both fed a balanced controlled diet were studied. Interleukins, IL-4 and IL-10 responses to soluble egg antigens (SEA) 90 days after infection, were determined. Our results suggest that in iNOS deficient, malnourished mice, 90 days after of infection, nitric oxide has a downregulating effect on IL-4 and IL-10 production. We are currently investigating the biological significance of these findings.

Malnutrition and hepatic fibrosis in murine schistosomiasis

In this paper, four different approaches attempting to reproduce the schistosomal liver fibrosis in undernourished mice are reported: shifting from a deficient to a balanced diet and vice-versa, repeated infections, influence of the genetic background, and immunological response. Infections were performed with 30 cercariae of Schistosoma mansoni and lasted at least four months. Undernourished mice were unable to reproduce the picture of "pipestem" fibrosis, except the C57 BL/10 inbred strain, four out of 21 mice developing the liver lesion. A link of this histological finding to the type of parasite strain can not be discarded at the moment. Repeated infections increased collagen deposition mainly in well nourished animals (seven out of 16 Swiss mice developed "pipestem"-like fibrosis). In undernourished infected Swiss mice the serum levels of soluble egg antigen specific antibodies IgG1, IgG2a, IgG2b, and IgG3 were two to four times lower than those detected for well nourished controls. The decreased humoral immune response coupled to the morphological, morphometric, and biochemical results reinforce the influence of the host nutritional status on the connective tissue changes of hepatic schistosomiasis.

Host nutritional status as a contributory factor to the remodeling of schistosomal hepatic fibrosis

Weaning Swiss mice were percutaneously infected with 30 cercariae of Schistosoma mansoni and submitted to a shifting either from a deficient to a balanced diet or vice-versa, for 24 weeks. The nutritional status was weekly evaluated by measurements of growth curves and food intake. Hepatic fibrosis and periovular granulomas were studied by histological, morphometric and biochemical methods. All mice fed on a deficient diet failed to develop periportal "pipestem" fibrosis after chronic infection. An unexpected finding was the absence of pipestem fibrosis in mice on normal diet, probably related to the sample size. The lower values for nutritional parameters were mainly due to the deficient diet, rather than to infection. Liver/body weight ratio was higher in "early undernutrition" group, after shifting to the balanced diet. Volume density and numerical density of egg granulomas reached lowest values in undernourished animals. The amount of collagen was reduced in undernourished mice, attaining higher concentrations in well-fed controls and in "late undernutrition" (balanced diet shifted to a deficient one), where collagen deposition appeared increased in granulomas. That finding suggested interference with collagen degradation and resorption in "late" undernourished animals. Thus, host nutritional status plays a role in connective tissue changes of hepatic schistosomiasis in mice.

Morphometric study of Schistosoma mansoni adult worms recovered from undernourished infected mice

Some unfavourable effects of malnutrition of the host on Schistosoma mansoni worm biology and structure have been reported based upon brigthfield microscopy. This paper aims to study by morphometric techniques, some morphological parameters in male and female adult worms recovered from undernourished albino mice in comparison with parasites recovered from well-fed infected mice. Undernourished animals were fed a multideficient and essentially low protein diet (RBD diet) and compared to well-fed control mice fed with the commercial diet NUVILAB. Seventy-five days post-infection with 80 cercarie (BL strain) animals were sacrificed. All adult worms were fixed in 10 percent formalin and stained with carmine chloride. One hundred male and 60 female specimens from each group (undernourished and control) were examined using an image system analysis Leica Quantimet 500C and the Sigma Scan Measurement System. The following morphometrical parameters were studied: body length and width, oral and ventral suckers, number and area of testicular lobes, length and width of ovary and uterine egg. For statistical analysis, the Student's t test for unpaired samples was applied. Significant differences (p < 0.05) were detected in body length and width, in parameters of suckers, uterine egg width, ovary length and area of testicular lobes, with lower values for specimens from undernourished mice. The nutritional status of the host has negative influence on S. mansoni adult worms, probably through unavailability of essential nutrients to the parasites

The use of protein hydrolysate improves the protein intestinal absorption in undernourished mice infected with Schistosoma mansoni

Patients residing in endemic areas for schistosomiasis in Brazil are usually undernourished and when they develop the hepatosplenic clinical form of the disease should usually receive hospital care, many of them being in need of nutritional rehabilitation before specific treatment can be undertaken. In the mouse model, investigations carried out in our laboratory detected a reduced aminoacid uptake in undernourished animals which is aggravated by a superimposed infection with Schistosoma mansoni. However, in well-nourished infected mice no dysfunction occurs. In this study, we tried to improve the absorptive intestinal performance of undernourished mice infected with S. mansoni by feeding them with hydrolysed casein instead of whole casein. The values obtained for the coefficient of protein intestinal absorption (cpia) among well-nourished mice were above 90 percent (either hydrolysed or whole protein). In undernourished infected mice, however, the cpia improved significantly after feeding them with hydrolysed casein, animals reaching values close to those obtained in well-nourished infected mice

Morphological aspects of Schistosoma mansoni adult worms isolated from nourished and undernourished mice: a comparative analysis by confocal laser scanning microscopy

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite

Preliminary results on the effects of CD40/CD40L interactions and SAC-induction on IFN-gamma expression in human schistosomiasis

In this communication the authors analyzed the pattern of expression of IFN-gamma as a surrogate type 1 response in different clinical forms of schistosomiasis in response to stimulation involving T-cell dependent and T-cell independent pathways, to investigate which pathways were functional in human schistosomiasis, and to further characterize the nature of Th1 response impairment in this parasitic disease

Effects of non-specific immunopotentiators in experimental Schistosoma mansoni infection: II. Corynebacterium parvum

Neste trabalho foram avaliados os efeitos do Corynebacterium parvum na protecao do hospedeiro, reacao tecidual e quimiotaxia "in vivo" em camundongos infectados pelo S. mansoni. O C. parvum foi dado intraperitonealmente usando uma dose de 0,7 mg, duas vezes por semana (durante 04 semanas), 30 dias antes (tratamento profilatico) e 30 dias apos a infeccao (tratamento curativo). A protecao do hospedeiro foi avaliada atraves da contagem de vermes adultos obtidos atraves da perfusao hepatica de camundongos infectados e esse numero foi bem menor no grupo profilatico comparado ao grupo controle (p=0,018), obtendo-se 44 por cento de protecao. A resposta quimiotatica "in vivo", nos grupos curativo e profilatico, foi maior do que no grupo infectado/nao tratado (p=0,009 e p=0,003, respectivamente). As reacoes teciduais foram descritas em todos os grupos, embora nao tenham ocorrido diferencas marcantes entre eles. As possiveis implicacoes biologicas e a relevancia dos achados para a resposta defensiva do hospedeiro e controle da esquistossomose sao discutidas neste trabalho

Characterization of a Trypanosoma cruzi strain isolated from a non-endemic area in northeast Brazil

A cepa WSL (Wild Sao Lorenco) de T. cruzi, isolada de um cobaio proveniente de Sao Lorenco da Mata (Nordeste do Brasil) foi caracterizada atraves da analise do seu comportamento morfobiologico e perfil isoenzimatico. Para o estudo do comportamento morfobiologico, tripomastigotas sanguineos (1 x 10 elevado a quinta potencia) da cepa WSL foram inoculados por via intraperitonal em camundongos albinos Swiss. Como controle a cepa Y (Tipo I) foi usada. Durante o curso de infeccao os seguintes parametros foram analisados: parasitemia, mortalidade, morfologia dos parasitas no sangue periferico e tropismo tissular. O perfil isoenzimatico foi analisado em relacao as enzimas ALAT, GPI e PGM usando como controle de referencia as cepas Peruana (Tipo I), 21SF (Tipo II) e Colombiana (Tipo III). A cepa WSL apresentou as seguintes caracteristicas biologicas: 1) multiplicacao lenta e pico parasitemico entre 21 - 25 dias pos-infeccao; 2) mortalidade de 3,3 por cento 40 dias pos-infeccao; 3) predominancia de formas largas no sangue periferico e 4) miotropismo com predominante envolvimento cardiaco. A analise isoenzimatica mostrou um padrao de zimodema 2 (Z@) que corresponde as cepas biologicas Tipo II. Os resultados mostram que a cepa WSL apresenta baixa virulencia e patogenicidade.

Intestinal protein absorption in malnourished mice with acute schistosomiasis mansoni

Intestinal protein absorption was studied in undernourished albino Swiss mice with acute schistosomiasis mansoni. Undernutrition was induced by feeding mice with the Regional Basic Diet (RBD) ingested by human populations in Northeast Brazil, an experimental model previously developed in our laboratory. Weaning mice were infected with 40 cercariae and compared to undernourished non-infected mice and/or to infected mice fed a balanced control diet. Apparent and True Protein Absorption Coefficients were determined by nitrogen balance during five consecutive days ending at the 63rd day of the trial (acute phase of murine schistosomiasis). Fecal metabolic nitrogen (FMN) was determined after administration of a non-protein diet and was also calculated through linear regression. Our results showed a reduced protein absorption in non-infected RBD-fed mice as compared to mice fed a casein control diet. Infection with Schistosoma mansoni had apparently no effect on intestinal protein absorption in well-nourished mice. However, infection seemed to interfere with protein absorption in under-nourished animals, since the lowest absorption ratios have been detected among RBD-fed infected mice. A brief discussion is made on the advantages of using the method of linear regression for the determination of FMN

The influence of the regional basic diet from northeast Brazil of health and nutritional conditions of mice infected with Schistosoma mansoni

Indicadores do estado nutricional de proteínas foram estudados em camundongos albinos suíços recém-desmamados e infectados com S. mansoni, aos quais foi administrada a Dieta Básica Regional (DBR) do Nordeste do Brasil. Cada camundongo foi infectado com 80 cercárias, por via percutânea. O experimento teve a duraçäo de 63 dias. Os parâmetros investigados foram: evoluçäo ponderal, consumo alimentar, ingestäo protéica, ganho ponderal, Coeficiente de Eficiência Protéica (PER) e Coeficiente de Eficiencia Proetéica Líquida (NPR). Os camundongos alimentados com a DBR revelaram acentuada perda de peso, menor consumo alimentar e protéico, maior lentidäo no ganho em peso relacionado com a fase de crescimento e taxas menos elevadas de utilizaçäo da proteína dietética, quando comparados com os controles (alimentados com dieta balanceada, à base de 22,60 por cento de caseína). As diferenças encontradas entre camundongos infectados e näo infectados, näo foram consistentes. Os resultados sugerem que os efeitos provocados pela má-nutriçäo induzida pelo consumo da DBR säo muito mais perniciosos para a saúde e estado nutricional do hospedeiro, do que aqueles resultantes da infecçäo pelo S. mansoni, na fase inicial da doença

Nutrition and acute schistosomiasis

In northeast Brazil, nutritional deficiency diseases and schistosomiasis mansoni overlap. An experimental model, wich reproduces the marasmatic clinical form of protein-energy malnutrition, was developed in this laboratory to study these interactions. Albino Swiss mice were fed with a food association ingested usually by human populations in northeast Brazil. This diet (Regional Basic Diet - RBD) has negative effects on the growth, food intake and protein utilization in infected mice (acute phase of murine schistosomiasis). Nitrogen balance studies have also shown that infection with Schistosoma mansoni has apparently no effect on protein intestinal absorption in well nourished mice. However, the lowest absorption ratios have been detected among RBD - fed infected animals, suggesting that suprerimposed schistosome infection aggravated the nutritional status of the undernourished host. The serum proteins electrophoretic pattern, as far as albumins are concerned, is quite similar for non-infected undernourished and infected well-fed animals. So, the significance of albumins as a biochemical indicator of the nutritional status of human populations residing in endemic foci of Manson's schistosomiasis, is discussable

Liver and serum solubre protein changes and pathomorphology in undernourished mice with acute schistonomiasis mansoni

No presente estudo os pesos corporal, hepático e esplênico; a morfologia patológica do fígado, baço e intestinos; e as modificaçöes das proteínas solúveis hepáticas e séricas, foram os parâmetros investigados em camundongos albinos Suíços desnutridos e infectados com S. mansoni. Os animais desnutridos näo infectados apresentaram relaçöes fígado/peso corporal e braço/peso corporal com valores menores do que os animais controles (grupo caseina a 22,60 por cento). Camundongos infectadas mostraram esses índices mais elevados, independentemente do tipo de dieta. O subgrupo de camundongos desnutridos infectados apresentou, no fígado, reaçäo periovular exsudativa persistente. O conteúdo de proteínas solúveis no fígado e no soro também mostrou-se reduzido nos camundongos infectados desnutridos. Diferença significativa foi detectada quanto às gamaglobulinas, comparando-se animais infectados com näo infectados alimentados com dieta controle II, valores mais altos ocorrendo no grupo dos infectados. Especula-se que os efeitos da má nutriçäo podem ser mais prejudiciais ao hospedeiro do que aqueles provocados pelo S. mansoni

Effects of betamethasone on the course of experimental infection with Trypanosoma cruzi

Foram estudados os efeitos da betametasona administrada na fase pós-aguda imediata de uma infecçäo pelo T. cruzi em camundongos. O tratamento consistiu de 30 doses diárias de 0,15 mg de betametasona, a partir de 42§ dia de infecçäo, näo havendo aparecimento de novos surtos de parasitemia. No tempo de duraçäo do experimento (7 meses) näo houve diferença entre as lesöes histopatológicas dos animais tratados e dos näo tratados. O grupo experimental apresentou uma maior mortalidade acumulada no 75§ dia de infecçäo, o que pode ser atribuído a infecçöes bacterianas associadas. Por outro lado, camundongos albinos "outbred", infectados com baixo inóculo, näo se apresentaram como bom modelo de doença de Chagas, já que näo desenvolveram lesöes importantes nem na fase aguda nem após 7 meses de infecçäo. Em conclusäo, o tratamento imunosupressivo prolongado, após a fase aguda de uma infecçäo mínima com a cepa Y do T. cruzi näo tem influência sobre o curso da infecçäo, pelo menos no que tange ao agravamento da mesma