Parasitological and morphological study of Schistosoma mansoni and diabetes mellitus in mice

AbstractSchistosomes are blood-dwelling flukes which are highly dependent on the host metabolism. The aim of this study was to investigate possible relationship between streptozotocin-induced diabetes and the outcome of acute murine schistosomiasis mansoni. Male and female SW mice were treated by a single intraperitoneally injected dose of streptozotocin (180mg/kg). Seven days after induction, both control and diabetic animals were infected with 70 Schistosoma mansoni cercariae (BH strain). Diabetics and their controls were weighed 45days after birth and for the last time prior to killing. Susceptibility to infection was evaluated twice a week by quantifying fecal egg excretion 7–9weeks post-infection by the Kato–Katz’ thick smear method. Mice were euthanized the day after the last fecal examination was performed. Adult worms were recovered from the portal system and mesenteric veins, whereas liver and intestine were removed for enumeration of egg load. No differences in worm length or in measurements of the reproductive organs, tegument, and suckers were detected. Also oviposition was unaffected as the total number of eggs per female worm from the liver, the small and the large intestine was the same in both groups. An oogram evaluation revealed a lower percentage of mature (23.0% vs. 40.7%) and a higher percentage of immature (69.1% vs. 51.7%) eggs in the small intestine of the diabetic mice. We suggest that principally a hampered egg passage through the intestine tissue caused this reduction and that probably both the eggs and the impaired host response play a role

Implicações biológicas da plasticidade fenotípica no modelo Schistosoma mansoni - Nectomys squamipes

The water-rat Nectomys squamipes is mostly important non-human host in schistosomiasis mansoni transmission in Brazil, due to its susceptibility, high abundance and water-contact pattern. During experimental infection of N. squamipes with Schistosoma mansoni, adult worms show phenotypic plasticity. This finding led us to investigate whether biological behavior is also affected. This was assessed comparing the biological characteristics of four S. mansoni strains: BE (State of Belém do Pará), CE (State of Pernambuco), CMO (State of Rio Grande do Norte) and SJ (State of São Paulo) using laboratory-bred N. squamipes. The infection was monitored by determination of the pre-patent period, fecal egg output, egg viability, intestinal egg count and, infectivity rate. No biological modification was observed in these parameters. Overall results highlight that N. squamipes was susceptible to several S. mansoni strains, suggesting that it might contribute to the maintenance of schistosomiasis mansoni in Brazil.O rato d´água Nectomys squamipes é importante transmissor não-humano da esquistossomose. Durante a infecção experimental em N. squamipes, os vermes adultos apresentam plasticidade fenotípica. Esses achados levaram-nos a investigar se os aspectos biológicos também são afetados. Foram comparadas as características biológicas de quatro cepas de S. mansoni: BE (Estado de Belém do Pará), CM (Estado de Pernambuco), CMO (Estado do Rio Grande do Norte) e SJ (Estado de São Paulo), utilizando como modelo experimental N. squamipes criados e mantidos em laboratório. A infecção foi monitorada para a determinação do período pré-patente, eliminação de ovos nas fezes, viabilidade dos ovos, contagem de ovos retidos no intestino e infectividade. Nenhuma modificação biológica foi observada nesses parâmetros. Os resultados sugerem que o N. squamipes é susceptível a várias cepas de S. mansoni, contribuindo para a manutenção da esquistossomose no Brasil

Spurious infection by Calodium hepaticum (Bancroft, 1983) Moravec, 1982 and intestinal parasites in forest reserve dwellers in Western Brazilian Amazon

Subsistence hunting is the main source of protein for forest reserve dwellers, contributing to the development of spurious infections by Calodium hepaticum, frequently associated with the consumption of the liver from wild mammals. The prevalence of infections by soil-transmitted helminths (STHs) and intestinal protozoa is considered an indicator of the social vulnerability of a country, besides providing information on habits, customs and quality of life of a given population. Intestinal parasites mostly affect poor rural communities with limited access to clean water and adequate sanitation. This study reports the results of a parasitological survey carried out in 2017 and 2019, in two municipalities (Xapuri and Sena Madureira) in Acre State. Stool samples were collected from 276 inhabitants. Upon receipt, each sample was divided into two aliquots. Fresh samples without preservative were processed and examined by the Kato-Katz technique. Samples fixed in 10% formalin were processed by the spontaneous sedimentation and the centrifugal sedimentation techniques. Calodium hepaticum eggs were found in three stool samples. The overall STH prevalence was 44.9%. The hookworm prevalence (19.2%) was higher than that of Ascaris lumbricoides (2.5%) and Trichuris trichiura (0.7%), an unexpected finding for municipalities belonging to the Western Brazilian Amazon. When considering parasites transmitted via the fecal-oral route, Endolimax nana and Entamoeba coli showed the highest positivity rates, of 13% and 10.9%, respectively. This study is the first report of spurious infection by C. hepaticum among forest reserve dwellers that consume undercooked liver of lowland pacas. Additionally, this is the first report of Blastocystis sp. in Acre State

CARACTERÍSTICAS HISTOPATÓLOGICAS DE LA INFECCIÓN POR SCHISTOSOMA MANSONI EN AKODON CURSOR (RODENTIA: SIGMODONTINAE)

El ratón de hierba del Brasil Akodon cursor Winge, 1887 es especialmente susceptible a la infección natural y experimental por Schistosoma mansoni Sambon, 1907. Este estudio está referido a las características histopatológicas de la infección experimental por S. mansoni. Los ratones criados en laboratorio fueron infectados con 150 cercarias (cepa BH) por vía subcutánea y sacrificados nueve semanas más tarde. Las muestras de los tejidos del huésped, incluyendo el hígado, el bazo, el intestino y el páncreas se recogieron para su examen histopatológico. En esta infección aguda, la participación del tejido fue de intensidad variable, aunque granulomas exudativos predominaron en todos los tejidos observados. En la composición celular predominaron los linfocitos, macrófagos y eosinófilos y fibroblastos, según el granuloma individual y su etapa de desarrollo. Nuestros resultados mostraron que A. cursor puede proporcionar un modelo útil para estudiar la patogénesis de la schistosomiais mansoni en un modelo de roedor silvestre

Schistosoma mansoni coactivator associated arginine methyltransferase 1 (SmCARM1) effect on parasite reproduction

IntroductionThe human blood fluke parasite Schistosoma mansoni relies on diverse mechanisms to adapt to its diverse environments and hosts. Epigenetic mechanisms play a central role in gene expression regulation, culminating in such adaptations. Protein arginine methyltransferases (PRMTs) promote posttranslational modifications, modulating the function of histones and non-histone targets. The coactivator-associated arginine methyltransferase 1 (CARM1/PRMT4) is one of the S. mansoni proteins with the PRMT core domain.MethodsWe carried out in silico analyses to verify the expression of SmPRMTs in public datasets from different infection stages, single-sex versus mixed-worms, and cell types. The SmCARM1 function was evaluated by RNA interference. Gene expression levels were assessed, and phenotypic alterations were analyzed in vitro, in vivo, and ex vivo.ResultsThe scRNAseq data showed that SmPRMTs expression is not enriched in any cell cluster in adult worms or schistosomula, except for Smcarm1 expression which is enriched in clusters of ambiguous cells and Smprmt1 in NDF+ neurons and stem/germinal cells from schistosomula. Smprmt1 is also enriched in S1 and late female germ cells from adult worms. After dsRNA exposure in vitro, we observed a Smcarm1 knockdown in schistosomula and adult worms, 83 and 69%, respectively. Smcarm1-knockdown resulted in reduced oviposition and no significant changes in the schistosomula or adult worm phenotypes. In vivo analysis after murine infection with Smcarm1 knocked-down schistosomula, showed no significant change in the number of worms recovered from mice, however, a significant reduction in the number of eggs recovered was detected. The ex vivo worms presented a significant decrease in the ovary area with a lower degree of cell differentiation, vitelline glands cell disorganization, and a decrease in the testicular lobe area. The worm tegument presented a lower number of tubercles, and the ventral sucker of the parasites presented a damaged tegument and points of detachment from the parasite body.DiscussionThis work brings the first functional characterization of SmCARM1 shedding light on its roles in S. mansoni biology and its potential as a drug target. Additional studies are necessary to investigate whether the reported effects of Smcarm1 knockdown are a consequence of the SmCARM1-mediated methylation of histone tails involved in DNA packaging or other non-histone proteins

Smp38 MAP Kinase Regulation in Schistosoma mansoni: Roles in Survival, Oviposition, and Protection Against Oxidative Stress

Eukaryotic protein kinases (ePKs) are good medical targets for drug development in different biological systems. ePKs participate in many cellular processes, including the p38 MAPK regulation of homeostasis upon oxidative stress. We propose to assess the role of Smp38 MAPK signaling pathway in Schistosoma mansoni development and protection against oxidative stress, parasite survival, and also to elucidate which target genes have their expression regulated by Smp38 MAPK. After a significant reduction of up to 84% in the transcription level by Smp38 MAPK gene knockdown, no visible phenotypic changes were reported in schistosomula in culture. The development of adult worms was tested in vivo in mice infected with the Smp38 knocked-down schistosomula. It was observed that Smp38 MAPK has an essential role in the transformation and survival of the parasites as a low number of adult worms was recovered. Smp38 knockdown also resulted in decreased egg production, damaged adult worm tegument, and underdeveloped ovaries in females. Furthermore, only ~13% of the eggs produced developed into mature eggs. Our results suggest that inhibition of the Smp38 MAPK activity interfere in parasites protection against reactive oxygen species. Smp38 knockdown in adult worms resulted in 80% reduction in transcription levels on the 10th day, with consequent reduction of 94.4% in oviposition in vitro. In order to search for Smp38 MAPK pathway regulated genes, we used an RNASeq approach and identified 1,154 DEGs in Smp38 knockdown schistosomula. A substantial proportion of DEGs encode proteins with unknown function. The results indicate that Smp38 regulates essential signaling pathways for the establishment of parasite homeostasis, including genes related to antioxidant defense, structural composition of ribosomes, spliceosomes, cytoskeleton, as well as, purine and pyrimidine metabolism pathways. Our data show that the Smp38 MAPK signaling pathway is a critical route for parasite development and may present attractive therapeutic targets for the treatment and control of schistosomiasis

A Educação em Saúde na área da Parasitologia: a experiência dos projetos de extensão LiPar e Educac na “Semana de meninas e mulheres na Ciência” ocorrida na Universidade do Estado do Rio de Janeiro

As atividades de extensão universitária têm ganhado cada vez mais espaço, por mostrarem-se importantes instrumentos de construção do pensamento científico, colaborando para a incorporação de novos saberes e práticas para a sociedade e para os extensionistas. Os espaços não formais de ensino, por sua vez, revelam-se ótimos meios para tornar a construção desses saberes possível. Logo, através da associação das atividades de extensão em espaços não formais de ensino, é possível promover as temáticas de educação em saúde em parasitologia, buscando conscientizar e prevenir, de modo criativo e ativo, as parasitoses que ainda são um grande problema de saúde pública. Desta forma, esse trabalho se propôs relatar a experiência dos projetos de extensão da Universidade do Estado do Rio de Janeiro, LiPar (Liga de Parasitologia) e Educac, no evento “Semana de Meninas e Mulheres na Ciência”, organizado por mulheres de diferentes áreas das ciências e tecnologias. Assim, analisou-se de que forma o espaço não formal de ensino pode ajudar na prática educativa das atividades propostas pelas extensões e de que maneira esses projetos levam o conhecimento de educação em saúde em parasitologia nesses espaços. Além disso, por meio da técnica da Nuvem de Palavras, buscou-se identificar as principais dúvidas sobre os assuntos de parasitologia abordados e também as pré-concepções sobre o tema. Portanto, concluiu-seque o espaço não formal institucionalizado pode ser um grande aliado para o ensino de educação em saúde em parasitologia, pois permite utilizar diferentes metodologias que colaboram para a compreensão da teoria com a prática