RESUMO
This review of human amoebiasis is based on the most current knowledge of pathogenesis, diagnosis, treatment, and Entamoeba/microbiota interactions. The most relevant findings during this last decade about the Entamoeba parasite and the disease are related to the possibility of culturing trophozoites of different isolates from infected individuals that allowed the characterization of the multiple pathogenic mechanisms of the parasite and the understanding of the host-parasite relationship in the human. Second, the considerable advances in molecular biology and genetics help us to analyze the genome of Entamoeba, their genetic diversity, and the association of specific genotypes with the different amoebic forms of human amoebiasis. Based on this knowledge, culture and/or molecular diagnostic strategies are now available to determine the Entamoeba species and genotype responsible for invasive intestinal or extraintestinal amoebiasis cases. Likewise, the extensive knowledge of the immune response in amoebiasis with the appearance of new technologies made it possible to design diagnostic tools now available worldwide. Finally, the understanding of the interaction between the Entamoeba species and the intestinal microbiota aids the understanding of the ecology of this parasite in the human environment. These relevant findings will be discussed in this review.
Assuntos
Amebíase , Disenteria Amebiana , Entamoeba histolytica , Entamoeba , Humanos , Entamoeba histolytica/genética , Ecossistema , Amebíase/diagnóstico , Amebíase/terapia , Amebíase/parasitologia , Disenteria Amebiana/diagnóstico , Disenteria Amebiana/terapia , Disenteria Amebiana/parasitologia , Intestinos , Entamoeba/genéticaRESUMO
Entamoeba histolytica (E. histolytica) is a protozoan responsible for intestinal amebiasis in at least 500 million people per year, although only 10% of those infected show severe symptoms. It is known that E. histolytica captures molecules released during the host immune response through membrane receptors that favor its pathogenetic mechanisms for the establishment of amebic invasion. It has been suggested that E. histolytica interacts with acetylcholine (ACh) through its membrane. This promotes the increase of virulence factors and diverse mechanisms carried out by the amoeba to produce damage. The aim of this study is to identify a membrane receptor in E. histolytica trophozoites for ACh. Methods included identification by colocalization for the ACh and Gal/GalNAc lectin binding site by immunofluorescence, western blot, bioinformatic analysis, and quantification of the relative expression of Ras 5 and Rab 7 GTPases by RT-qPCR. Results show that the Gal/GalNAc lectin acts as a possible binding site for ACh and this binding may occur through the 150 kDa intermediate subunit. At the same time, this interaction activates the GTPases, Ras, and Rab, which are involved in the proliferation, and reorganization of the amoebic cytoskeleton and vesicular trafficking. In conclusion, ACh is captured by the parasite, and the interaction promotes the activation of signaling pathways involved in pathogenicity mechanisms, contributing to disease and the establishment of invasive amebiasis.
Assuntos
Amebíase , Disenteria Amebiana , Entamoeba histolytica , Humanos , Entamoeba histolytica/metabolismo , Lectinas/metabolismo , Receptores Colinérgicos/metabolismo , Proteínas de Protozoários/metabolismo , Disenteria Amebiana/parasitologiaRESUMO
E. histolytica is the etiological agent of intestinal amebiasis and liver abscesses, which still poses public health threat globally. Metronidazole is the drug of choice against amebiasis. However, metronidazole-resistant amoebic clinical isolates and strains have been reported recently, challenging the efforts for amebiasis eradication. In search of alternative treatments, E. histolytica transcriptomes have shown the association of genes involved in RNA metabolism with the virulence of the parasite. Among the upregulated genes in amoebic liver abscesses are the splicing factors EhU2AF2 and a paralog of EhSF3B1. For this reason and because EhU2AF2 contains unusual KH-QUA2 (84KQ) motifs in its lengthened C-terminus domain, here we investigated how the role of EhU2AF2 in pre-mRNA processing impacts the virulence of the parasite. We found that 84KQ is involved in splicing inhibition/intron retention of several virulence and non-virulence-related genes. The 84KQ domain interacts with the same domain of the constitutive splicing factor SF1 (SF1KQ), both in solution and when SF1KQ is bound to branchpoint signal RNA probes. The 84KQ-SF1KQ interaction prevents splicing complex E to A transition, thus inhibiting splicing. Surprisingly, the deletion of the 84KQ domain in EhU2AF2 amoeba transformants increased splicing and enhanced the in vitro and in vivo virulence phenotypes. We conclude that the interaction of the 84KQ and SF1KQ domains, probably involving additional factors, tunes down Entamoeba virulence by favoring intron retention.
Assuntos
Entamoeba histolytica , Proteínas de Protozoários/metabolismo , Fatores de Processamento de RNA/metabolismo , Animais , Disenteria Amebiana/parasitologia , Entamoeba histolytica/metabolismo , Entamoeba histolytica/patogenicidade , Humanos , Metronidazol , Splicing de RNA , Fator de Processamento U2AF/genética , Fator de Processamento U2AF/metabolismoRESUMO
Amoebiasis is a parasitic disease caused by Entamoeba histolytica (E. histolytica), an extracellular enteric protozoan. This infection mainly affects people from developing countries with limited hygiene conditions, where it is endemic. Infective cysts are transmitted by the fecal-oral route, excysting in the terminal ileum and producing invasive trophozoites (amoebae). E. histolytica mainly lives in the large intestine without causing symptoms; however, possibly as a result of so far unknown signals, the amoebae invade the mucosa and epithelium causing intestinal amoebiasis. E. histolytica possesses different mechanisms of pathogenicity for the adherence to the intestinal epithelium and for degrading extracellular matrix proteins, producing tissue lesions that progress to abscesses and a host acute inflammatory response. Much information has been obtained regarding the virulence factors, metabolism, mechanisms of pathogenicity, and the host immune response against this parasite; in addition, alternative treatments to metronidazole are continually emerging. An accesible and low-cost diagnostic method that can distinguish E. histolytica from the most nonpathogenic amoebae and an effective vaccine are necessary for protecting against amoebiasis. However, research about the disease and its prevention has been a challenge due to the relationship between E. histolytica and the host during the distinct stages of the disease is multifaceted. In this review, we analyze the interaction between the parasite, the human host, and the colon microbiota or pathogenic microorganisms, which together give rise to intestinal amoebiasis.
Assuntos
Amebíase/parasitologia , Países em Desenvolvimento , Disenteria Amebiana/parasitologia , Intestinos/parasitologia , Saúde Pública , Amebíase/tratamento farmacológico , Amebíase/epidemiologia , Animais , Antiprotozoários/uso terapêutico , Disenteria Amebiana/epidemiologia , Entamoeba histolytica/imunologia , Entamoeba histolytica/patogenicidade , Fezes/parasitologia , Microbioma Gastrointestinal , Interações Hospedeiro-Patógeno , Humanos , Intestinos/microbiologia , Metronidazol/uso terapêutico , Camundongos , VirulênciaRESUMO
INTRODUCTION: In Mexico, seroprevalence of Entamoeba histolytica is 8.4%. The intestinal amebiasis in patients with acute leukemia of novo, after the start of chemotherapy (CT) in the Hematology Service of the CMN 20 de Noviembre is 12%, even if patients show a negative baseline coprological test. OBJECTIVE: To find out if the administration of tinidazole, in patients with acute leukemia and negative coprological test, at the beginning of the CT, decreases the incidence of amoebic colitis during the induction to remission. METHOD: Prospective and not comparative study. Patients with de novo diagnosis of acute leukemia who initiate induction and initial coprological CT. Tinidazole was indicated, 2 g/day for 5 days in the first week of CT started. They were monitored until the induction was concluded and hematopoietic recovery started. RESULTS: 38 patients, 15 women and 23 men with a mean age of 44 years (16-72), with acute lymphoblastic leukemia 19, myeloblastic 16 and promyelocytic 3. Cases without and with intestinal amebiasis were 35 and 3, respectively. Patients with amebiasis only received tinidazole for 3 days and it was given 2 days after the CT started. CONCLUSION: Tinidazole, in patients with acute de novo leukemia who initiate induction CT, is effective in the prevention of intestinal amebiasis, during the induction stage, if administered at 2 g/day, for five days, starting on day 1 of the CT.
Assuntos
Amebicidas/uso terapêutico , Disenteria Amebiana/prevenção & controle , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Promielocítica Aguda/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Tinidazol/uso terapêutico , Adolescente , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Disenteria Amebiana/parasitologia , Feminino , Humanos , Quimioterapia de Indução/métodos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto JovemAssuntos
Doenças do Ceco/etiologia , Doenças do Ceco/parasitologia , Disenteria Amebiana/complicações , Disenteria Amebiana/parasitologia , Entamoeba histolytica , Idoso , Doenças do Ceco/diagnóstico por imagem , Ceco/diagnóstico por imagem , Disenteria Amebiana/diagnóstico por imagem , Humanos , MasculinoRESUMO
Amebiasis is the infection by Entamoeba histolytica, a protozoan capable of invading the colonic mucosa causing a diarrheic syndrome, although most of the time is mild, it can lead to a fulminating colitis. Sometimes it can spread to other organs; among extra-intestinal manifestations of this parasite, the most frequent is the amebic liver abscess. In the next pages, general aspects of this protozoan, its epidemiology, clinical findings, diagnosis and treatment are reviewed, emphasizing the possibilities of diagnosis and treatment available in Chile.
La amebiasis corresponde a la infección por Entamoeba histolytica, protozoo capaz de invadir la mucosa del colon provocando un cuadro diarréico que, si bien la mayoría de las veces es leve, puede llegar a una colitis fulminante. En algunas oportunidades puede diseminarse a otros órganos; dentro de las manifestaciones extra-intestinales de este parásito, la más frecuente es el absceso hepático amebiano. A continuación se revisan aspectos generales de este protozoo, su epidemiología, cuadro clínico, diagnóstico y tratamiento, destacando las posibilidades de diagnóstico y tratamiento disponibles en Chile.
Assuntos
Humanos , Disenteria Amebiana/diagnóstico , Disenteria Amebiana/tratamento farmacológico , Abscesso Hepático Amebiano/diagnóstico , Abscesso Hepático Amebiano/tratamento farmacológico , Diarreia/parasitologia , Disenteria Amebiana/parasitologia , Entamoeba histolytica/patogenicidade , Abscesso Hepático Amebiano/parasitologia , Metronidazol/uso terapêutico , Antiparasitários/uso terapêuticoAssuntos
Doenças do Ceco/parasitologia , Doenças do Colo/parasitologia , Disenteria Amebiana/parasitologia , Granulomatose com Poliangiite/complicações , Perfuração Intestinal/parasitologia , Adulto , Biópsia , Doenças do Ceco/complicações , Doenças do Ceco/diagnóstico , Colectomia , Doenças do Colo/complicações , Doenças do Colo/diagnóstico , Disenteria Amebiana/complicações , Disenteria Amebiana/diagnóstico , Evolução Fatal , Granulomatose com Poliangiite/diagnóstico , Granulomatose com Poliangiite/tratamento farmacológico , Humanos , Ileostomia , Imunossupressores/uso terapêutico , Perfuração Intestinal/diagnóstico , Perfuração Intestinal/cirurgia , Masculino , Resultado do TratamentoRESUMO
The pathogenic amoeba Entamoeba histolytica is able to migrate within various compartments of the human body. The present article reviews progress in understanding the mechanisms of cell motility in E. histolytica during human intestinal invasion and, in particular, how the three-dimensional characteristics of the environment regulate the parasite's behaviour. The amoeboid mode of migration that applies to E. histolytica's displacements on two-dimensional surfaces is also expected to apply to the three-dimensional environment in the human intestine although several unknown, distinct modalities may be involved. Recent advances in the field of tissue engineering have provided clues on how the construction of a human colon model could help us to understand the host's intestinal physiology and its changes following amoebic infection.
Assuntos
Disenteria Amebiana/parasitologia , Entamoeba histolytica/fisiologia , Intestinos/fisiopatologia , Intestinos/parasitologia , Animais , Colo/parasitologia , Colo/fisiopatologia , Entamoeba histolytica/patogenicidade , Humanos , Movimento , Técnicas de Cultura de Órgãos , Engenharia TecidualRESUMO
The parasite Entamoeba histolytica causes intestinal amebiasis and amebic liver abscess as its main extraintestinal manifestation. To study the in vivo events related to inflammation and the interactions between hosts and parasites during amebiasis, we designed a novel model of host-parasite interactions using cellulose membrane dialysis bags containing E. histolytica trophozoites. A bag is placed into the hamster peritoneal cavity, as has been reported in previous studies of programmed cell death (PCD) in E. histolytica trophozoites. To determine if virulence factors such as cysteine proteinases (EhCP2 and EhCP5) and Gal/GalNAc lectin could be involved in the host-parasite interaction using this model, we examined the relative expression of the ehcp2 and ehcp5 genes and the carbohydrate recognition domain (crd) of Gal/GalNAc lectin using real-time quantitative PCR (qRT-PCR). All analyzed genes were over-expressed 0.5h after the initiation of the host-parasite interaction and were then progressively down-regulated. However, Gal/GalNAc lectin had the greatest increase in gene expression 1.5h after host-parasite interaction; Gal/GalNAc lectin had a 250-fold increase with respect to the axenically grown trophozoites, which over-express Gal/GalNAc lectin in in vivo models. These results support the important role of these molecules in the initiation of cell damage by E. histolytica.
Assuntos
Acetilgalactosamina/metabolismo , Cisteína Endopeptidases/metabolismo , Entamoeba histolytica/metabolismo , Entamebíase/parasitologia , Mesocricetus/parasitologia , Animais , Cricetinae , Cisteína Endopeptidases/genética , Disenteria Amebiana/parasitologia , Entamoeba histolytica/genética , Interações Hospedeiro-Parasita , Humanos , Lectinas/metabolismo , Abscesso Hepático Amebiano/parasitologia , Masculino , Proteínas de Protozoários/genética , Trofozoítos/patologiaRESUMO
BACKGROUND: Invasive amebiasis is not frequently seen in the United States. It is associated with considerable morbidity in patients residing in or traveling to endemic areas. We report a case series of patients with amebic colitis in a United States-Mexico border city to alert physicians to the varied clinical manifestations. CASE PRESENTATION: Nine patients were diagnosed with amebic colitis. Mean age was 56 (38-83), 6 were males, and all were Hispanic. Common symptoms were diarrhea (56 %), hematochezia (33 %) and abdominal bloating (11 %). The diagnosis of amebic colitis was established in the following ways: 8 patients by colonoscopy with biopsy, 1 by surgery for colonic obstruction. The diagnosis of amebic colitis was confirmed in 8 patients (89 %) by amebic trophozoites present in histopathologic sections. One patient was diagnosed with amebic colitis based upon clinical symptoms, colitis on colonoscopy and visualization of amebic trophozoites on stool examination. In the 8 patients in whom colonoscopy was done, 6 (75 %) had inflammation with rectosigmoid involvement and 5 (62.5 %) had ulcerations. Infection resolved after treatment with metronidazole in most patients; however, one patient developed a liver abscess and another had a colonic perforation and later developed a liver abscess. CONCLUSION: The occurrence of amebic colitis in this United States-Mexico border city hospital population was low, but in some cases potentially life-threatening. Physicians should be alert to the less common presentations of amebic colitis, such as overt gastrointestinal bleeding, exacerbation of inflammatory bowel disease, and the incidental finding of association with colon cancer, or a surgical abdomen. Rectosigmoid involvement was typically found on colonoscopy.
Assuntos
Colonoscopia/métodos , Disenteria Amebiana/parasitologia , Entamoeba histolytica/fisiologia , Trofozoítos/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Colite/diagnóstico , Colite/etnologia , Diagnóstico Diferencial , Diarreia/diagnóstico , Diarreia/etnologia , Disenteria Amebiana/diagnóstico , Disenteria Amebiana/etnologia , Entamoeba histolytica/isolamento & purificação , Feminino , Hispânico ou Latino , Interações Hospedeiro-Parasita , Humanos , Abscesso Hepático Amebiano/diagnóstico , Abscesso Hepático Amebiano/etnologia , Masculino , México , Pessoa de Meia-Idade , Estados UnidosRESUMO
Os enteroparasitos são causa importante de agravos à saúde humana e podem interferir de forma significativa no desenvolvimento infantil. Embora as formas de transmissão sejam bemdocumentadas, a desinformação e as precárias condições socioeconômicas de alguns segmentos da população ainda são fatores que contribuem para a manutenção de parasitos no País, viabilizando a transmissão. Este estudo foi realizado entre crianças residentes e funcionários de uma instituiçãofilantrópica religiosa, situada na cidade de Niterói, Rio de Janeiro, consistindo em um ciclo de palestras educativas, seguido da coleta de amostras fecais para diagnóstico coproparasitológico.Foram coletadas 68 amostras fecais frescas e encontrados enteroparasitos em 41 delas (60 por cento),sendo o Blastocystis hominis o parasito mais prevalente (44 por cento). Adicionalmente, sete amostrasforam positivas para o complexo Entamoeba histolytica/E. dispar, sendo uma confirmada como E. histolytica pelo ELISA para pesquisa de coproantígeno. Em 37 amostras de fezes foi pesquisadaa presença de E. histolytica e E. dispar pela técnica de Nested-PCR. Entre essas, 12 (32 por cento) amplificaram um fragmento de 195 pb quando utilizados primers específicos para E. dispar, não havendo amplificação de qualquer produto com os primers de E. histolytica. Estudo feito no entornoda instituição revelou acúmulo de lixo e a presença de saídas de esgoto no peridomicílio, as quais desembocavam nas proximidades da área de lazer das crianças. É possível que esses pontos sejam responsáveis pela contaminação do solo e mesmo incriminados como uma das possíveis fontes deinfestação para as crianças.
Intestinal parasites are important agents of human diseases, besides being responsible for impairingchildhood development. Although transmission is well known, lack of information and precarioussocial and economic conditions are risk factors that allow maintenance of parasite cycles, favoringtransmission. This study was carried out among resident children and employees of a Catholic Institution, located in Niterói, Rio de Janeiro, and consisted of delivering lectures and collectingfresh stool samples, which were processed through the Willis and Hoffman, Pons and Janermethods. Enteroparasites were found in 41 samples (60 percent) and Blastocystis hominis was the mostprevalent (44 percent). Additionally, in seven samples where microscopic examination was positive forthe E. histolytica/E. dispar complex an ELISA was employed to detect E. histolytica and only onereacted positively in the immunoassay. In 37 samples a Nested-PCR was carried out for detectionof E. histolytica and E. dispar and in 12 samples (32 percent) a product with 195 bp was observed usingE. dispar primers, while there was no amplification product with E. histolytica specific primers. As the Institution has a good pattern of hygiene not related with the results, a superficial analysis of its peripheral area was carried out and showed lots of garbage in the neighborhood and sewage outflowinto the play area of the Institution. We concluded that these points may be responsible for the soil contamination and could be incriminated as one of the sources of infection in the children.
Assuntos
Humanos , Recém-Nascido , Criança , Blastocystis/parasitologia , Disenteria Amebiana/diagnóstico , Disenteria Amebiana/parasitologia , Doenças Parasitárias/diagnóstico , Doenças Parasitárias/fisiopatologia , Fezes/parasitologia , Ensaio de Imunoadsorção Enzimática , Reação em Cadeia da PolimeraseRESUMO
Analysis of the mechanisms underlying the inflammatory response in amoebiasis is important to understand the immunopathology of the disease. Mucosal associated effector and regulatory T cells may play a role in regulating the inflammatory immune response associated to Entamoeba histolytica infection in the colon. A subpopulation of regulatory T cells has recently been identified and is characterized by the expression of the chemokine receptor CCR9. In this report, we used CCR9 deficient (CCR9(-/-)) mice to investigate the role of the CCR9(+) T cells in a murine model of E. histolytica intestinal infection. Intracecal infection of CCR9(+/+), CCR9(+/-) and CCR9(-/-) mice with E. histolytica trophozoites, revealed striking differences in the development and nature of the intestinal inflammatory response observed between these strains. While CCR9(+/+) and CCR9(+/-) mice were resistant to the infection and resolved the pathogen-induced inflammatory response, CCR9(-/-) mice developed a chronic inflammatory response, which was associated with over-expression of the cytokines IFN-γ, TNF-α, IL-4, IL-6 and IL-17, while IL-10 was not present. In addition, increased levels of CCL11, CCL20 and CCL28 chemokines were detected by qRT-PCR in CCR9(-/-) mice. E. histolytica trophozoites were identified in the lumen of the cecum of CCR9(-/-) mice at seven days post infection (pi), whereas in CCR9(+/+) mice trophozoites disappeared by day 1 pi. Interestingly, the inflammation observed in CCR9(-/-) mice, was associated with a delayed recruitment of CD4(+)CD25(+)FoxP3(+) T cells to the cecal epithelium and lamina propria, suggesting that this population may play a role in the early regulation of the inflammatory response against E. histolytica, likely through IL-10 production. In support of these data, CCR9(+) T cells were also identified in colon tissue sections obtained from patients with amoebic colitis. Our data suggest that a population of CCR9(+)CD4(+)CD25(+)FoxP3(+) T cells may participate in the control and resolution of the inflammatory immune response to E. histolytica infection.
Assuntos
Modelos Animais de Doenças , Disenteria Amebiana/imunologia , Entamoeba histolytica/imunologia , Receptores CCR/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Quimiocina CCL11/genética , Quimiocina CCL11/imunologia , Quimiocina CCL11/metabolismo , Quimiocina CCL20/genética , Quimiocina CCL20/imunologia , Quimiocina CCL20/metabolismo , Quimiocinas CC/genética , Quimiocinas CC/imunologia , Quimiocinas CC/metabolismo , Disenteria Amebiana/metabolismo , Disenteria Amebiana/parasitologia , Entamoeba histolytica/fisiologia , Citometria de Fluxo , Fatores de Transcrição Forkhead/imunologia , Fatores de Transcrição Forkhead/metabolismo , Expressão Gênica , Humanos , Mediadores da Inflamação/imunologia , Mediadores da Inflamação/metabolismo , Interferon gama/imunologia , Interferon gama/metabolismo , Interleucina-17/imunologia , Interleucina-17/metabolismo , Subunidade alfa de Receptor de Interleucina-2/imunologia , Subunidade alfa de Receptor de Interleucina-2/metabolismo , Interleucina-4/imunologia , Interleucina-4/metabolismo , Interleucina-6/imunologia , Interleucina-6/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores CCR/genética , Receptores CCR/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Trofozoítos/imunologia , Trofozoítos/fisiologia , Fator de Necrose Tumoral alfa/imunologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND: Epidemiological and microbiologic studies suggest that enteropathogenic microorganisms play a substantial role in the clinical initiation and relapses of inflammatory bowel disease. AIM: To explore the prevalence of intestinal protozoa in patients with ulcerative colitis (UC) and its impact on clinical disease course. METHODS: A total of 215 patients with definitive diagnosis of UC were studied. Fresh feces samples taken from all UC patients were examined immediately using trichrome-staining methods. RESULTS: A total of 103 female and 112 male UC patients were analyzed. The mean age at diagnosis was 30.5 +/- 10.8 years. The prevalence of overall parasitic infections was 24% and distributed as follows: Blastocystis hominis in 22 patients (10%), Endolimax nana in 19 cases (9%), and Entamoebahistolytica in 11 cases (5%). A significantly increased frequency of protozoa infection was found in those patients with persistent activity and intermittent activity as compared to active than inactive group (p = 1 x 10(-7), OR 13.05, 95% CI 4.28-42.56, and p = 0.003, OR 1.42-14.47, respectively). Interestingly, this association remained significant when we compared the persistent activity group versus intermittent activity group (p = 0.003, OR 2.97, 95% CI 1.35-6.59). Subgroup analysis showed no association between protozoa infection (E. histolytica, B. hominis, and E. nana) and other clinical variables such as gender, extent of disease, extraintestinal complications, medical treatment and grade of disease activity. CONCLUSION: The prevalence of intestinal protozoa infections in Mexican UC patients was 24% and these microorganisms could be a contributing cause of persistent activity despite medical treatment in our population.
Assuntos
Amebíase/epidemiologia , Infecções por Blastocystis/epidemiologia , Colite Ulcerativa/parasitologia , Amebíase/parasitologia , Animais , Infecções por Blastocystis/parasitologia , Blastocystis hominis/isolamento & purificação , Distribuição de Qui-Quadrado , Colite Ulcerativa/epidemiologia , Progressão da Doença , Disenteria Amebiana/epidemiologia , Disenteria Amebiana/parasitologia , Endolimax/isolamento & purificação , Entamoeba histolytica/isolamento & purificação , Fezes/parasitologia , Feminino , Humanos , Masculino , México/epidemiologia , Pessoa de Meia-Idade , PrevalênciaRESUMO
BACKGROUND: It has been suggested that the damage observed in invasive amebiasis is related to interactions between polymorphonuclear leukocytes (PMN) and Entamoeba histolytica trophozoites. We analyzed the relation between infiltrating inflammatory cell populations and E. histolytica density in intestinal amebic lesions. METHODS: Biopsies obtained endoscopically from patients with amebic colitis were analyzed to describe their morphologic abnormalities. Cellular populations and E. histolytica trophozoites were measured quantitatively in order to assess the correlation between infiltrating inflammatory cell populations and parasite density. RESULTS: Amebic lesions were most often located in the colon (55%). The histopathologic diagnoses were colitis in 31%, erosive colitis in 26%, and ulcerated colitis in 24%. The predominant cellular populations found in the lesions were lymphocytes (59.8%) (3,672 +/- 2,413/mm(2)) followed by PMN (17%) (1,038 +/- 1,171 PMN/mm(2)) (p < 0.01). A higher density of PMN infiltration was observed in severe cases. Cellular populations predictive of the presence of E. histolytica trophozoites (p = 0.047) were PMN (p = 0.019) and lymphocytes (p = 0.033). The highest association was found between E. histolytica trophozoites and PMN (p = 0.0221). CONCLUSIONS: Neutrophils and lymphocytes, particularly the former, are associated significantly with the density of parasites. Our findings support the theory that PMN interaction with E. histolytica contributes to the pathogenesis of amebic intestinal lesions.
Assuntos
Disenteria Amebiana/imunologia , Disenteria Amebiana/parasitologia , Entamoeba histolytica , Infiltração de Neutrófilos , Neutrófilos/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Animais , Contagem de Células , Distribuição de Qui-Quadrado , Criança , Pré-Escolar , Colo/parasitologia , Colo/ultraestrutura , Disenteria Amebiana/patologia , Entamoeba histolytica/imunologia , Feminino , Humanos , Lactente , Mucosa Intestinal/parasitologia , Mucosa Intestinal/ultraestrutura , Intestino Grosso/parasitologia , Intestino Grosso/patologia , Modelos Lineares , Linfócitos/imunologia , Masculino , Pessoa de Meia-Idade , Trofozoítos/imunologiaRESUMO
An epidemiological and molecular study on E. histolytica and E. dispar was carried out in 428 patients with gastrointestinal symptomatology of diarrhea from different health centers in Cumana, Sucre state. The samples were processed through: direct examination with 0.85% physiological saline solution, temporal lugol staining, trichromic staining and the Ritchie method of concentration; a sucrose gradient was used for cyst isolation. The small subunit of the 16S RNA was amplified by nested, multiplex PCR for the molecular detection. The E. histolytica/E. dispar prevalences according to the direct, Ritchie and trichromic staining methods were 20.09, 13.79 and 12.15%, respectively; while prevalences according to PCR for E. histolytica and E. dispar were 6.31% and 4.44%, respectively, also detecting four cases of mixed infection. Sequencing of the amplified fragments of E. histolytica showed 100% homology with the sequences with strains from Merida (Venezuela), USA, Brazil, Mexico and GenBank. The infections by E. histolytica and E. dispar were statistically associated with age but not with sex. The presence of mucus, blood and abdominal pain were only associated to E. histolytica infection. The moderate prevalence of E. histolytica shows the endemic status of this population and warns about the potential problem as a morbidity and mortality in Sucre state. The frequency of E. dispar in this population suggests the existence of an overestimation problem in the diagnosis of amoebiasis with its clinical and epidemiological implications, and shows the poor knowledge about the true prevalences of this protozoan. The PCR allowed for the differential identification of E. histolytica and E. dispar, as well as the presence of mixed infections, making a great tool for epidemiological amoebiasis studies.
Assuntos
Disenteria Amebiana/parasitologia , Entamoeba histolytica/isolamento & purificação , Entamoeba/isolamento & purificação , Adolescente , Adulto , Idoso , Animais , Sequência de Bases , Criança , Pré-Escolar , Diarreia/etiologia , Diarreia/parasitologia , Disenteria Amebiana/epidemiologia , Doenças Endêmicas , Entamoeba/genética , Entamoeba histolytica/genética , Feminino , Helmintíase/epidemiologia , Helmintíase/parasitologia , Humanos , Lactente , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/parasitologia , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Prevalência , Infecções por Protozoários/epidemiologia , Infecções por Protozoários/parasitologia , Ribotipagem , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Venezuela/epidemiologiaRESUMO
A amebíase é a segunda causa de morte entre as doenças parasitárias no mundo. Seu agente etiológico é o protozoário Entamoeba histolytica, que através da secreção de proteinases é capazes de destruir o tecido hospedeiro, matando as células-alvo por contato e fagocitando eritrócitos. Dessa forma, os trofozoítos invadem a mucosa intestinal, provocando a colite amebiana. Em alguns casos atravessam a mucosa e, através da circulação porta, chegam ao fígado, onde causam necrose constituída por poucos trofozoítos rodeados de hepatócitos mortos e debris celulares liquefeitos. Essa invasão está diretamente relacionada com a capacidade de síntese e a secreção de moléculas responsáveis pela virulência dos trofozoítos, como os amebaporos, as lectinas e as cisteína proteinases. O diagnóstico da infecção causada pelo patógeno é rotineiramente realizado através da microscopia óptica de amostras frescas ou espécimes fixados. Entretanto essa metodologia apresenta limitações, sendo incapaz de distinguir as espécies pertencentes ao complexo E. histolytica/E. dispar. A pesquisa de coproantígenos e a reação em cadeia da polimerase (PCR) têm sido utilizadas para diferenciação desses protozoários em amostras fecais. No entanto, estudos mais aprofundados são necessários para maior compreensão sobre a relação parasita/hospedeiro, a proteômica e a genômica do protozoário, o desenvolvimento de vacinas e a real prevalência dessa infecção no Brasil e no mundo.
Amebiasis is the second cause of death among parasitary diseases in the world. Its etiologic agent is the protozoan Entamoeba histolytica, which destroys the host tissue by means of the secretion of proteinases, kills the target-cells by contact and phagocytizes erythrocytes. Accordingly, the trophozoites invade the intestinal mucosa, what causes amoebaean colitis. In some cases, they pass through the mucosa and reach the liver through the portal system, where they cause necrosis, which is composed of a few trophozoites surrounded by dead hepatocytes and liquefied cellular debris. This invasion is directly related to the synthesis capacity and secretion of molecules responsible for the virulence of trophozoites such as amoebapores, lectins and cysteine proteinases. The diagnosis of infection caused by this pathogen is routinely performed through optical microscopy of fresh samples or fixed specimens. However this methodology presents limitations insofar as it is unable to distinguish the specimens belonging to the complex E. histolytica /E. dispar. The research on coproantigens and the polymerase chain reaction (PCR) method have been used to differentiate these protozoa in fecal samples. However further studies are required for a better understanding of the host-parasite relationship, the proteomics and genomics of the protozoa, the development of vaccines and the real prevalence of this infection in Brazil and worldwide.
Assuntos
Humanos , Disenteria Amebiana/diagnóstico , Entamoeba histolytica/patogenicidade , Disenteria Amebiana/etiologia , Disenteria Amebiana/fisiopatologia , Disenteria Amebiana/parasitologiaRESUMO
Studies were carried out at a mexican pediatric hospital to determine the ratio between the pathogenic species Entamoeba histolytica and non-pathogenic species E. dispar using an enzyme-linked immunosorbent assay (ELISA) to detect the lectin (1 galactose N-acetyl D-galactosamine) of E. histolytica in feces. A close correlation was noted between the presence of the E. histolytica lectin and clinical symptoms. In the study, amebas were detected by microscopy in 120 children (either E. histolytica or E. dispar). But while almost all (13/14) of the children with E. histolytica had clinical symptoms, dysentery-feces with mocus and blood, diarrhea, cramping abdominal pain, tenesmus rectal, flatulence, vomiting and headache, almost none (1/106) of the children infected with the non-pathogenic ameba E. dispar had signs and symptoms. This suggests that much of the amebiasis diagnoses made in Mexico are, in fact, due to non-pathogenic E. dispar.
Assuntos
Humanos , Adolescente , Lactente , Pré-Escolar , Criança , Disenteria Amebiana/diagnóstico , Disenteria Amebiana/parasitologia , Entamoeba histolytica/imunologia , Acetilgalactosamina/metabolismo , Diagnóstico Diferencial , Disenteria Amebiana/imunologia , Ensaio de Imunoadsorção Enzimática , Fezes/parasitologia , México , MicroscopiaRESUMO
Reversible protein tyrosine phosphorylation is an essential signal transduction mechanism that regulates cell growth, differentiation, mobility, metabolism, and survival. Two genes coding for protein tyrosine phophatases, designed EhPTPA and EhPTPB, were cloned from Entamoeba histolytica. EhPTPA and EhPTPB proteins showed amino acid sequence identity of 37%, both EhPTPases showed similarity with Dictyostelium discoideum and vertebrate trasmembranal PTPases. mRNA levels of EhPTPA gene are up-regulated in trophozoites recovered after 96h of liver abscess development in the hamster model. EhPTPA protein expressed as a glutathione S-transferase fusion protein (GST::EhPTPA) showed enzymatic activity with p-nitrophenylphosphate as a substrate and was inhibited by PTPase inhibitors vanadate and molybdate. GST::EhPTPA protein selectively dephosphorylates a 130kDa phosphotyrosine-containing protein in trophozoite cell lysates. EhPTPA gene codifies for a 43kDa native protein. Up-regulation of EhPTPA expression suggests that EhPTPA may play an important role in the adaptive response of trophozoites during amoebic liver abscess development.
Assuntos
Disenteria Amebiana/parasitologia , Entamoeba histolytica/enzimologia , Fígado/parasitologia , Proteínas Tirosina Fosfatases/química , Proteínas Tirosina Fosfatases/metabolismo , Sequência de Aminoácidos , Animais , Clonagem Molecular , Cricetinae , Ativação Enzimática , Dados de Sequência Molecular , Proteínas Tirosina Fosfatases/análise , Homologia de Sequência de Aminoácidos , Especificidade da EspécieRESUMO
The genetic variability of Entamoeba dispar strains was investigated in 39 positive isolates on a survey of 1783 individuals from two different cities of Northeast Brazil (Recife and Macaparana) using two polymorphic species-specific loci (loci 1-2 and 5-6). A combinatory clustering analysis revealed no geographical correlation and remarkable genetic polymorphism among all the isolates examined. Nevertheless, a comparison of the frequency of eight individual PCR products, shared by both Recife and Macaparana populations, for the two loci, showed that only one product of locus 5-6 was significantly different between the two cities. These results suggested that the Macaparana population is infected by similar strains and that locus 5-6 shows potential in assaying questions related to the molecular epidemiology of this region.