RESUMO
Axenically grown Entamoeba histolytica produces a pentapeptide (Met-Gln-Cys-Asn-Ser) with several anti-inflammatory properties, including the inhibition of human monocyte locomotion (Monocyte Locomotion Inhibitory Factor (MLIF)). A construct displays the same effects as the native material. It remains to be seen if MLIF is used, or even produced in vivo by the tissue-invading parasite. If MLIF were to be relevant in invasive amoebiasis, immunizing against it could diminish this parasite advantage and prevent lesions. KLH-linked MLIF mixed with Freund's adjuvant was too aggressive an immunizing material to answer this question. However, immunization with a tetramer of MLIF (but not a scrambled version of MLIF) around a lysine core (MLIF-MAPS), that displays increased antigenicity, yet lacks excessive innate immunity activation, completely protects gerbils against amoebic abscess of the liver caused by the intraportal injection of virulent E. histolytica. Liver abscesses caused by Listeria monocytogenes were not prevented. Invasive E. histolytica may produce the parent protein of MLIF in vivo, and if appropriately cleaved, it may play a role in invasive amoebiasis. MLIF may join new vaccination strategies against amoebiasis.
Assuntos
Anti-Inflamatórios/imunologia , Entamoeba histolytica/imunologia , Imunização/métodos , Abscesso Hepático Amebiano/imunologia , Abscesso Hepático Amebiano/prevenção & controle , Oligopeptídeos/imunologia , Animais , Anti-Inflamatórios/farmacologia , Ensaio de Imunoadsorção Enzimática , Gerbillinae , Hipersensibilidade Tardia/imunologia , Imunoglobulina G/sangue , Ativação Linfocitária/imunologia , Linfócitos/citologia , Linfócitos/imunologia , Masculino , Oligopeptídeos/farmacologia , Peptídeos/imunologia , Distribuição AleatóriaAssuntos
Administração da Prática Médica/tendências , Pesquisa Biomédica/economia , Depressão/psicologia , Educação Médica/economia , Educação Médica/tendências , Sistemas Pré-Pagos de Saúde/economia , Sistemas Pré-Pagos de Saúde/tendências , Pessoal de Saúde/economia , Pessoal de Saúde/psicologia , Pessoal de Saúde/tendências , Humanos , Ilusões/psicologia , Administração da Prática Médica/economiaAssuntos
Administração da Prática Médica/tendências , Doença Crônica/epidemiologia , Doenças Transmissíveis/terapia , Medicina Defensiva/legislação & jurisprudência , Medicina Defensiva/tendências , Diagnóstico por Imagem/tendências , Indústria Farmacêutica/tendências , Endoscopia/tendências , Técnicas Genéticas/tendências , Administração Hospitalar/estatística & dados numéricos , Administração Hospitalar/tendências , Humanos , Ciência de Laboratório Médico/tendências , Biologia Molecular/tendências , Neoplasias/terapia , Administração da Prática Médica/economia , Administração da Prática Médica/ética , Transplante/tendências , Vacinação/tendências , Doenças Vasculares/epidemiologiaRESUMO
While normal human eosinophils are destroyed in vitro by virulent Entamoeba histolytica, notwhistanding the presence of antibodies and complement, activated eosinophils promptly destroy the parasite although dying also at the end of the process. To study the possible in vivo participation of eosinophils in evasive amebiasis, we compared the induction of experimental amebic abscess of the liver (AAL) in gerbils (Meriones unguiculatus) previously made eosinophilic through Toxocara canis antigen injection and in normal control gerbils. After intraportal inoculation of 105 ameba trophozoites (6 and 24 hr), the ratio of gerbils with AAL, as well as the number and size of the microabscesses was comparable in eosinophilic and control gerbils. However, at 9 hr the number and size of the microabscesses were significantly smaller (p<0.05) in eosinophilic gerbils. On the other hand, the actuarial AAL survival curve up to 45 days post-amebic inoculation was sugnificantly (p<0.05) shifted to the right in controls. These results suggest that antigen-induced eosinophilia may exert a protective effect agaisnt AAL in gerbils.
Assuntos
Animais , Camundongos , Amebíase/imunologia , Eosinófilos/imunologia , Abscesso Hepático Amebiano/imunologia , Entamoeba histolytica/imunologia , Gerbillinae/parasitologiaRESUMO
This quantitative ultrastructural survery of E. histolytica locomotion in Boyden chambers supports the concept that this parasitis is capable of random, chemokinetic and chemotactic motility. An E. histolytica committed to chemotaxis will flatten over the filter, accumulate smaller vacuoles at the front of the cell, and will also project pseudopods and its polarized body towards and alongside the chemoattractant axis, respectively. Other cell features such as cell polarization, membrane ruffling, hyaline, total number of pseudopods and caudal displacement of the nucleus appear to be associated with the locomotion efforts as such, perhaps reflecting speed (chemokinesis) but irrespective of orientation (chemotaxis). Finally, only on of the 11 features that were analyzed (i.e., number of vacuoles) failed to be distinctly associated with any of the movement forms studied. E. histolytica appears to possess the full repertoire of locomotion modalities observed in free moving eukaryots, and its motility translates into ultrastructural landmarks that could be useful indicators of subcellular events related to locomotion