RESUMO
AIMS: WHO declared that mental health care should be considered one essential health service to be maintained during the coronavirus disease 2019 (COVID-19) pandemic. This study aims to describe the effect of lockdown and restrictions due to the COVID-19 pandemic in Italy on mental health services' utilisation, by considering psychiatric diagnoses and type of mental health contacts. METHODS: The study was conducted in the Verona catchment area, located in the Veneto region (northeastern Italy). For each patient, mental health contacts were grouped into: (1) outpatient care, (2) social and supportive interventions, (3) rehabilitation interventions, (4) multi-professional assessments, (5) day care. A 'difference in differences' approach was used: difference in the number of contacts between 2019 and 2020 on the weeks of lockdown and intermediate restrictions was compared with the same difference in weeks of no or reduced restrictions, and such difference was interpreted as the effect of restrictions. Both a global regression on all contacts and separate regressions for each type of service were performed and Incidence Rate Ratios (IRRs) were calculated. RESULTS: In 2020, a significant reduction in the number of patients who had mental health contacts was found, both overall and for most of the patients' characteristics considered (except for people aged 18-24 years for foreign-born population and for those with a diagnosis of schizophrenia. Moreover, in 2020 mental health contacts had a reduction of 57 096 (-33.9%) with respect to 2019; such difference remained significant across the various type of contacts considered, with rehabilitation interventions and day care showing the greatest reduction. Negative Binomial regressions displayed a statistically significant effect of lockdown, but not of intermediate restrictions, in terms of reduction in the number of contacts. The lockdown period was responsible of a 32.7% reduction (IRR 0.673; p-value <0.001) in the overall number of contacts. All type of mental health contacts showed a reduction ascribable to the lockdown, except social and supportive interventions. CONCLUSIONS: Despite the access to community mental health care during the pandemic was overall reduced, the mental health system in the Verona catchment area was able to maintain support for more vulnerable and severely ill patients, by providing continuity of care and day-by-day support through social and supportive interventions.
Assuntos
COVID-19 , Centros Comunitários de Saúde Mental , Serviços Comunitários de Saúde Mental , Transtornos Mentais , Quarentena , Itália/epidemiologia , COVID-19/epidemiologia , COVID-19/prevenção & controle , Centros Comunitários de Saúde Mental/estatística & dados numéricos , Humanos , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Serviços Comunitários de Saúde Mental/estatística & dados numéricos , Quarentena/estatística & dados numéricos , Transtornos Mentais/diagnóstico , Transtornos Mentais/epidemiologia , Transtornos Mentais/reabilitação , Transtornos Mentais/terapiaRESUMO
Mental disorders are one of the largest contributors to the burden of disease globally, this holds also for children and adolescents, especially in low- and middle-income countries. The prevalence and severity of these disorders are influenced by social determinants, including exposure to adversity. When occurring early in life, these latter events are referred to as adverse childhood experiences (ACEs).In this editorial, we provide an overview of the literature on the role of ACEs as social determinants of mental health through the lenses of global mental health. While the relation between ACEs and mental health has been extensively explored, most research was centred in higher income contexts. We argue that findings from the realm of global mental health should be integrated into that of ACEs, e.g. through preventative and responsive psychosocial interventions for children, adolescents and their caregivers. The field of global mental health should also undertake active efforts to better address ACEs in its initiatives, all with the goal of reducing the burden of mental disorders among children and adolescents globally.
Assuntos
Experiências Adversas da Infância , Transtornos Mentais , Adolescente , Criança , Humanos , Renda , Transtornos Mentais/epidemiologia , Saúde Mental , Taurina/análogos & derivadosRESUMO
The limited success of recent phenotypic anti-leishmanial drug screening campaigns calls for new screening strategies for the discovery of clinically relevant hits. Here we present such a novel strategy based on physiologically relevant, ex vivo biology. We established high content phenotypic assays that combine primary murine macrophages and lesion-derived, virulent L. donovani and L. amazonensis amastigotes, which we applied to validate previously identified, anti-leishmanial hit compounds referred to as 'GSK Leish-Box'. Together with secondary screens using cultured promastigotes, our pipeline distinguished stage- and/or species-specific compounds, including 20 hits with broad activity at 10 µM against intracellular amastigotes of both viscerotropic and dermotropic Leishmania. Even though the GSK Leish-Box hits were identified by phenotypic screening using THP-1 macrophage-like cells hosting culture-derived L. donovani LdBob parasites, our ex vivo assays only validated anti-leishmanial activity at 10 µM on intra-macrophagic L. donovani for 23 out of the 188 GSK Leish-Box hits. In conclusion, our comparative approach allowed the identification of hits with broad anti-leishmanial activity that represent interesting novel candidates to be tested in animal models. Physiologically more relevant screening approaches such as described here may reduce the very high attrition rate observed during pre-clinical and clinical phases of the drug development process.
Assuntos
Antiprotozoários/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Leishmania donovani/efeitos dos fármacos , Leishmania mexicana/efeitos dos fármacos , Leishmaniose Cutânea/prevenção & controle , Leishmaniose Visceral/prevenção & controle , Animais , Antiprotozoários/química , Células Cultivadas , Humanos , Leishmania donovani/patogenicidade , Leishmania mexicana/patogenicidade , Leishmaniose Cutânea/parasitologia , Leishmaniose Visceral/parasitologia , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Camundongos Endogâmicos BALB C , Estrutura Molecular , Fenótipo , Especificidade da Espécie , Células THP-1 , Virulência/efeitos dos fármacosRESUMO
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
RESUMO
Leishmania are protozoan parasites that, as amastigotes, live in the macrophages of mammalian hosts within compartments called parasitophorous vacuoles. These organelles share features with late endosomes/lysosomes and are also involved in the trafficking of several major histocompatibility complex (MHC)-encoded molecules. Improved knowledge of the parasitophorous vacuoles may help clarify how these protozoa persist in their hosts.
Assuntos
Leishmania/imunologia , Leishmaniose/parasitologia , Macrófagos/parasitologia , Fagossomos/parasitologia , Vacúolos/parasitologia , Adaptação Biológica , Animais , Endocitose , Interações Hospedeiro-Parasita , Membranas Intracelulares/química , Complexo Principal de Histocompatibilidade , Camundongos , Modelos ImunológicosRESUMO
Sixty-seven extracts of 30 medicinal plants traditionally used in New Caledonia or Vanuatu by healers to treat inflammation, fever and in cicatrizing remedies were evaluated in vitro for their antiprotozoal activity against Leishmania donovani, Leishmania amazonensis and Trypanosoma cruzi. Among the selected plants, Pagiantha cerifera was the most active against both Leishmania species; four extracts were active against promastigotes of Leishmania donovani at EC(50) values inferior to 5 microg/ml. Garcinia pedicillata extract had an EC(50) value of 12.5 microg/ml against intracellular amastigotes of Leishmania amazonensis. Alone Amborella trichopoda reduced by more of 80% the trypomastigotes of Trypanosoma cruzi in the blood.
Assuntos
Plantas Medicinais/química , Tripanossomicidas/química , Tripanossomicidas/farmacologia , Animais , Avaliação Pré-Clínica de Medicamentos , Leishmania donovani/efeitos dos fármacos , Camundongos , Testes de Sensibilidade Microbiana , Nova Caledônia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , VanuatuRESUMO
Leishmania are protozoans of the trypanosomatidae family that cause human infections. The amastigote form of Leishmania is an obligate intracellular parasite of mononuclear phagocytes that multiplies within parasitophorous vacuoles (pv) of phagolysosomal origin. To investigate the strategies which allow Leishmania to withstand these potentially cytotoxic conditions, the distribution and activities of various lysosomal peptidases in rat macrophages infected or uninfected with Leishmania amazonensis amastigotes were studied. Specific immunoglobulins against cathepsins (cat.) B, H, L and D were used to localize these endopeptidases by immunocytochemistry. Results showed that most or even all of the secondary lysosomes in the host cell fuse with parasite-filled phagosomes, leading to translocation of the proteases in the parasitophorous vacuoles. A further study consisted in assays of five protease activities: dipeptidylpeptidases (DPP) I and II (exopeptidases), cat. B, cat. H and cat. D. Infection of macrophages was followed by a gradual increase in all these protease activities except for DPP II. These increases were apparently not related to parasite protease activities. It seems that infection by Leishmania amazonensis is followed by increased synthesis and/or reduced catabolism of host cell lysosomal proteases or alternatively by inactivation of endogenous inhibitors. Amastigote infectivity may be related, at least in part, to the development of mechanisms that allow the parasite to withstand unfavorable environmental conditions.
Assuntos
Endopeptidases/metabolismo , Leishmania/enzimologia , Lisossomos/enzimologia , Macrófagos/parasitologia , Animais , Macrófagos/ultraestrutura , RatosRESUMO
Leishmania amastigotes are intracellular protozoan parasites of mononuclear phagocytes which reside within parasitophorous vacuoles of phagolysosomal origin. The pH of these compartments was studied with the aim of elucidating strategies used by these microorganisms to evade the microbicidal mechanisms of their host cells. For this purpose, rat bone marrow-derived macrophages were infected with L. amazonensis amastigotes. Intracellular acidic compartments were localized by using the weak base 3-(2,4-dinitroanilino)-3'-amino-N-methyldipropylamine as a probe. This indicator, which can be detected by light microscopy by using immunocytochemical methods, mainly accumulated in perinuclear lysosomes of uninfected cells, whereas in infected cells, it was essentially localized in parasitophorous vacuoles, which thus appeared acidified. Phagolysosomal pH was estimated quantitatively in living cells loaded with the pH-sensitive endocytic tracer fluoresceinated dextran. After a 15- to 20-h exposure, the tracer was mainly detected in perinuclear lysosomes and parasitophorous vacuoles of uninfected and infected macrophages, respectively. Fluorescence intensities were determined from digitized video images of single cells after processing and automatic subtraction of background. We found statistically different mean pH values of 5.17 to 5.48 for lysosomes and 4.74 to 5.26 for parasitophorous vacuoles. As for lysosomes of monensin-treated cells, the pH gradient of parasitophorous vacuoles collapsed after monensin was added. This very likely indicates that these vacuoles maintain an acidic internal pH by an active process. These results show that L. amazonensis amastigotes are acidophilic and opportunistic organisms and suggest that these intracellular parasites have evolved means for survival under these harsh conditions and have acquired plasma membrane components compatible with the environment.
Assuntos
Leishmania/fisiologia , Macrófagos/parasitologia , Vacúolos/parasitologia , Animais , Células Cultivadas , Dextranos , Dinitrobenzenos , Feminino , Fluoresceínas , Concentração de Íons de Hidrogênio , Lisossomos/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Ratos , Ratos Endogâmicos F344RESUMO
The natural resistance-associated macrophage protein (Nramp1) regulates macrophage activation. One of its pleiotropic effects on macrophage function is to regulate expression of major histocompatibility class II molecules. In this study macrophages stably transfected with the wild-type (infection-resistant) or the natural mutant (infection-susceptible) allele of the Nramp1 gene were used to study class II expression and processing and presentation of recombinant protein antigens to CD4+ T-cell hybridomas. As demonstrated previously for macrophages from Nramp1-resistant and -susceptible congenic mouse strains, transfected macrophage clones carrying the wild-type allele showed enhanced upregulation of class II molecules in response to gamma interferon compared to that shown by macrophage clones carrying an endogenous mutant allele or transfected with the mutant allele expressed under a viral long terminal repeat promoter. The wild-type allele-transfected macrophage clones also demonstrated an enhanced, lipopolysaccharide-dependent ability to process the recombinant leishmanial antigen LACK-delta 1 (the Leishmania homolog of receptors for activated C kinase) for presentation to LACK-specific CD4+ T cells. An influence on antigen processing must therefore be added to the growing list of pleiotropic effects of the Nramp1 gene potentially contributing to its role in infectious and autoimmune disease susceptibility. These results also have important implications for analysis of T-cell responses to vaccination, especially where antigens are presented to the immune system using live Salmonella species or Mycobacterium bovis BCG as a vaccine vehicle.
Assuntos
Apresentação de Antígeno/genética , Proteínas de Transporte/genética , Proteínas de Transporte de Cátions , Ativação de Macrófagos/genética , Proteínas de Membrana/genética , Transfecção/imunologia , Animais , Apresentação de Antígeno/efeitos dos fármacos , Antígenos/metabolismo , Células Clonais , Antígenos de Histocompatibilidade Classe II/genética , Imunidade Inata/genética , Interferon gama/farmacologia , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Polimixina B/farmacologia , Proteínas Recombinantes/farmacologiaRESUMO
In mammalian hosts, Leishmania amastigotes are obligatory intracellular parasites of macrophages and multiply within parasitophorous vacuoles of phagolysosomal origin. To understand how they escape the harmful strategies developed by macrophages to kill ingested microorganisms, it is important to obtain information on the functional state of parasitophorous vacuole. For this purpose, we studied the intracellular distribution and activity of host lysosomal proteases in rat bone marrow-derived macrophages infected with Leishmania amazonensis amastigotes. Localization of cathepsins B, H, L, and D was investigated by using specific immunoglobulins. In uninfected macrophages, these enzymes were located in perinuclear granules (most of them were probably secondary lysosomes) which, after infection, disappeared progressively. In infected macrophages, cathepsins were detected mainly in the parasitophorous vacuoles, suggesting that the missing secondary lysosomes had fused with these organelles. Biochemical assays of various proteases (cathepsins B, H, and D and dipeptidyl peptidases I and II) showed that infection was accompanied by a progressive increase of all activities tested, except that of dipeptidyl peptidase II, which remained constant. No more than 1 to 10% of these activities could be attributed to amastigotes. These data indicate that (i) Leishmania infection is followed by an increased synthesis and/or a reduced catabolism of host lysosomal proteases, and (ii) amastigotes grow in a compartment rich in apparently fully active proteases. Unexpectedly, it was found that infected and uninfected macrophages degraded endocytosed proteins similarly. The lack of correlation in infected macrophages between increase of protease activities and catabolism of exogenous proteins could be linked to the huge increase in volume of the lysosomal compartment.
Assuntos
Catepsinas/metabolismo , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Leishmaniose/enzimologia , Lisossomos/enzimologia , Macrófagos/parasitologia , Animais , Compartimento Celular , Imunofluorescência , Macrófagos/enzimologia , Camundongos , Camundongos Endogâmicos BALB C , Inibidores de Proteases/farmacologia , Proteínas/metabolismo , Ratos , Ratos Endogâmicos F344RESUMO
Macrophages are apparently the only cells that in vivo allow the growth of the intracellular pathogen Leishmania. They are thus generally considered as likely candidates for the presentation of parasite Ag to CD4+ T lymphocytes known to be involved in protective and counterprotective immune responses. In the present study, we examined whether mouse macrophages infected with Leishmania were capable of stimulating T cell hybrids and a T cell clone reacting with the previously identified protective Ag LACK (Leishmania homologue of receptors for Activated C Kinase). This parasite protein is expressed in both promastigote and amastigote stages of Leishmania. We found that IFN-gamma-treated macrophages recently infected with live Leishmania promastigotes were fully competent to activate LACK-reactive T cells. However, at later times of infection, permissive macrophages infected with promastigotes were no longer able to present LACK, in spite of the presence of numerous intracellular parasites. This punctual presentation of LACK was apparently linked with the destruction, at least partial, of the intracellular parasites. In contrast, macrophages infected with live Leishmania amastigotes were always unable to stimulate the LACK-specific T cells. Amastigote-infected macrophages could, however, reactivate the T cells if LACK-delta(1), a recombinant form of LACK, was added as an exogenous protein in the culture medium. Similar results were obtained with all combinations tested involving macrophages from various origins, different activating cytokines (IFN-gamma, granulocyte-macrophage CSF, IL-4), several Leishmania species (L. amazonensis, L. major, L. donovani), and 15 different LACK-reactive T cell hybrids and clones. From these data, it is tempting to propose that the differentiation of promastigotes into amastigotes, which leads to a better survival of the parasites within macrophages, also allows them to go unnoticed by the immune system.
Assuntos
Apresentação de Antígeno , Antígenos de Protozoários/metabolismo , Leishmania/imunologia , Macrófagos/imunologia , Macrófagos/parasitologia , Proteínas de Protozoários/imunologia , Animais , Antígenos de Protozoários/administração & dosagem , Cricetinae , Modelos Animais de Doenças , Feminino , Células Híbridas , Técnicas In Vitro , Leishmania/crescimento & desenvolvimento , Leishmania/patogenicidade , Leishmaniose/imunologia , Leishmaniose/parasitologia , Leishmaniose/prevenção & controle , Ativação Linfocitária , Mesocricetus , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Nus , Proteínas de Protozoários/administração & dosagem , Proteínas de Protozoários/metabolismo , Linfócitos T/imunologia , Fatores de TempoRESUMO
We describe six Italian families affected by microcephaly with an apparently autosomal mode of inheritance (total number of microcephalic children and adults, 21). All microcephalic subjects were of normal height, with the exception of one. The head volume was measured directly in at least one adult microcephalic member from five of the six families, and lower values were obtained in these subjects than in control subjects. Psychometric tests were performed on seven children and five adults among the microcephalic subjects. Normal values were found for all but one of the subjects. In the selected families microcephaly seems to be inherited in an autosomal dominant manner. Because some families showing autosomal dominant microcephaly have normal intelligence, psychometric evaluation of microcephalic children and their microcephalic relatives is important for genetic counseling.
Assuntos
Aberrações Cromossômicas/genética , Genes Dominantes , Deficiência Intelectual/genética , Microcefalia/genética , Adulto , Cefalometria , Criança , Pré-Escolar , Aberrações Cromossômicas/diagnóstico , Transtornos Cromossômicos , Humanos , Lactente , Microcefalia/diagnóstico , Linhagem , Testes Psicológicos , PsicometriaRESUMO
The comparative surface antigen study of 10 bolivian strains and 1 brazilian reference strain from L. b. braziliensis sub-species shows an important homogeneity within this group. All the strains tested so far present similar antigenic patterns with a major antigen at 72 kD. On the contrary, the comparative analysis of surface antigens of L. b. braziliensis with those of L. b. guyanensis, L. b. panamensis, L. mexicana amazonensis and L. donovani chagasi shows a large antigenic heterogeneity between the Leishmania sub-species and species we studied. The 72 kD antigen was only detected on L. b. braziliensis surface.
Assuntos
Antígenos de Protozoários/análise , Antígenos de Superfície/análise , Leishmania braziliensis/imunologia , Leishmania/imunologia , Animais , Eletroforese em Gel de Poliacrilamida , Leishmania donovani/imunologia , Leishmania mexicana/imunologiaRESUMO
In their amastigote stage, Leishmania live in mammalian macrophages within parasitophorous vacuoles (PV), organelles of phagolysosomal origin that, in macrophages activated with IFN-gamma, contain major histocompatibility complex (MHC) class II molecules apparently devoid of invariant chains. We have now studied the fate of PV-associated class II molecules in mouse bone marrow-derived macrophages infected with L. amazonensis amastigotes using immunocytochemical and biochemical approaches. We have found that at least a part of these class II molecules was internalized by amastigotes and reached structures very often located in their posterior poles. This process was much more obvious if infected macrophages were incubated with protease inhibitors like antipain, chymostatin, Z-Phe-AlaCHN2 and Z-Phe-PheCHN2, or if amastigotes were pre-treated with the irreversible cysteine protease inhibitor Z-Phe-AlaCHN2 before infection, clearly indicating that amastigotes also degraded the internalized class II molecules. Study of infected macrophage cryosections by immuno-electron microscopy allowed the identification of the class II-positive structures in amastigotes as the lysosome-like organelles known as megasomes. Other PV membrane components like the prelysosomal/lysosomal glycoproteins Igp110, Igp120 and macrosialin could not be detected in megasomes of amastigotes even after treatment of macrophages with protease inhibitors, suggesting the involvement of some specific mechanism(s) for the internalization of class II molecules. Interestingly, after treatment of infected macrophages with various protease inhibitors (antipain, leupeptin, E-64, Z-Phe-AlaCHN2, Z-Phe-PheCHN2), PV membrane as well as megasomes of amastigotes become positive for invariant chains. A quantitative analysis of amastigote-associated class II molecules based on enzyme immunoassays showed that: (a) amastigotes extracted from macrophages treated with both IFN-gamma and antipain or Z-Phe-AlaCHN2 contained a much greater amount of class II than amastigotes extracted from macrophages treated with IFN-gamma alone; (b) class II molecules associated with the former were mainly intracellular and, at least some of them, were complexed with invariant chains or fragments of invariant chains; (c) amastigotes pre-incubated with Z-Phe-AlaCHN2 before infection accumulated a greater amount of intracellular class II than amastigotes pre-incubated without inhibitor, clearly indicating that the blockade of parasite cysteine proteases was sufficient to enhance the pool of these molecules within megasomes. On the whole, these data are consistent with the idea that class II molecules reaching PV are newly synthesized and still complexed with intact invariant chains or with partially degraded invariant chains.(ABSTRACT TRUNCATED AT 400 WORDS)
Assuntos
Antígenos de Histocompatibilidade Classe II/imunologia , Leishmania mexicana/imunologia , Leishmaniose/imunologia , Macrófagos/microbiologia , Animais , Medula Óssea/imunologia , Células da Medula Óssea , Células Cultivadas , Feminino , Antígenos de Histocompatibilidade Classe II/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BLRESUMO
Leishmania-infected macrophages are potential antigen-presenting cells for CD4+ T lymphocytes, which recognize parasite antigens bound to major histocompatibility complex class II molecules (Ia). However, the intracellular sites where Ia and antigens may interact are far from clear, since parasites grow within the modified lysosomal compartment of the host cell, whereas Ia molecules seem to be targeted to endosomes. To address this question, the expression and fate of Ia molecules were studied by immunocytochemistry in Leishmania amazonensis-infected murine macrophages stimulated with gamma interferon. In uninfected macrophages, Ia molecules were localized on the plasma membrane and in perinuclear vesicles, but they underwent a dramatic redistribution after infection, since most of the intracellular staining was then associated with the periphery of the parasitophorous vacuoles (p.v.) and quite often polarized towards amastigote-binding sites. The Ii invariant chain, which is transiently associated with Ia during their intracellular transport, although well expressed in infected macrophages, apparently did not reach the p.v. Similar findings were observed with macrophages from mice either resistant or highly susceptible to Leishmania infection. In order to determine the origin of p.v.-associated Ia, the fate of plasma membrane, endosomal, and lysosomal markers, detected with specific antibodies, was determined after infection. At 48 h after infection, p.v. was found to exhibit a membrane composition typical of mature lysosomes. Overall, these data suggest that (i) Ia located in p.v. originate from secondary lysosomes involved in the biogenesis of this compartment or circulate in several endocytic organelles, including lysosomes and (ii) p.v. could play a role in antigen processing and presentation. Alternatively, the presence of high amounts of Ia in p.v. could be due to a Leishmania-induced mechanism by means of which this organism may evade the immune response.
Assuntos
Antígenos de Histocompatibilidade Classe II/biossíntese , Leishmania mexicana/imunologia , Macrófagos/imunologia , Fagossomos/imunologia , Animais , Anticorpos Monoclonais , Membrana Celular/imunologia , Membrana Celular/ultraestrutura , Células Cultivadas , Feminino , Corantes Fluorescentes , Técnicas Imunoenzimáticas , Interferon gama/farmacologia , Cinética , Leishmania mexicana/crescimento & desenvolvimento , Lisossomos/imunologia , Lisossomos/parasitologia , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Macrófagos/ultraestrutura , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Nus , Organelas/imunologia , Fagossomos/parasitologia , Proteínas Recombinantes , Frações Subcelulares/metabolismoRESUMO
The establishment of Leishmania in mammals depends on the transformation of metacyclic promastigotes into amastigotes within macrophages. The kinetics of this process was examined using mouse macrophages infected with metacyclic promastigotes of L. amazonensis. The appearance of amastigote characteristics, including large lysosome-like organelles called megasomes, stage-specific antigens, high cysteine protease activity and sensitivity to L-leucine methyl ester, was followed over a 5-day period. Megasomes were observed at 48 h but probable precursors of these organelles were detected at 12h p.i. The promastigote-specific molecules examined were down-regulated within 5 to 12h after phagocytosis whereas the amastigote-specific antigens studied were detectable from 2 to 12-24 h. An increase in the cysteine protease activity and in sensitivity to L-leucine methyl ester of the parasites was detected from 24 h. The data indicate that at 48 h p.i., parasites exhibit several amastigote features but that complete differentiation requires at least 5 days. The appearance of megasomes or of megasome precursors and the rise in cysteine protease activity correlate quite well with the capacity of parasites to internalize and very likely degrade host MHC molecules. The fact that internalization by the parasites of host cell molecules occurs very early during the differentiation process argues for a role of this mechanism in parasite survival.
Assuntos
Endopeptidases , Antígenos de Histocompatibilidade Classe II/metabolismo , Interações Hospedeiro-Parasita/imunologia , Leishmania/imunologia , Leishmaniose/veterinária , Animais , Western Blotting/veterinária , Catepsina B/análise , Catepsina L , Catepsinas/análise , Células Cultivadas , Cisteína Endopeptidases , Regulação para Baixo , Feminino , Técnica Indireta de Fluorescência para Anticorpo/veterinária , Cinética , Leishmania/patogenicidade , Leishmaniose/imunologia , Leishmaniose/parasitologia , Leucina/análogos & derivados , Leucina/farmacologia , Macrófagos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microscopia Imunoeletrônica/veterinária , Fagocitose , Fatores de TempoRESUMO
The synthesis of 2-substituted-trifluoromethylquinolines from aniline, trifluoromethylanilines, 3-aminoquinoline and trifluoromethylquinaldines is reported. In vitro antileishmanial evaluation of 2-alkyl, 2-alkenyl and 2-epoxypropyl-trifluoromethylquinolines is presented.
Assuntos
Antiprotozoários/síntese química , Antiprotozoários/farmacologia , Leishmania/efeitos dos fármacos , Quinolinas/síntese química , Quinolinas/farmacologia , Animais , Cromatografia em Camada Fina , Indicadores e Reagentes , Leishmania donovani/efeitos dos fármacos , Leishmania infantum/efeitos dos fármacos , Leishmania mexicana/efeitos dos fármacos , Espectroscopia de Ressonância MagnéticaRESUMO
In their amastigote stage, Leishmania are obligatory intracellular parasites of mammalian macrophages, residing and multiplying within phagolysosomal compartments called parasitophorous vacuoles (PV). These organelles have properties similar to those described for the MHC class II compartments of antigen-presenting cells, sites where peptide-class II molecule complexes are formed before their expression at the cell surface. After infection with Leishmania amazonensis or L. mexicana, endocytosis and degradation of class II molecules by intracellular amastigotes have also been described, suggesting that these parasites have evolved mechanisms to escape the potentially hazardous antigen-presentation process. To determine whether these events extend to other molecules of the antigen-presentation machinery, we have now studied the fate of the MHC molecule H-2M in mouse macrophages infected with Leishmania amastigotes. At least for certain class II alleles, H-2M is an essential cofactor, which catalyses the release of the invariant chain-derived CLIP peptide from the peptide-binding groove of class II molecules and facilitates the binding of antigenic peptides. H-2M was detected in PV of mouse macrophages infected with various Leishmania species including L. amazonensis, L. mexicana, L. major and L. donovani. PV thus contain all the molecules required for the formation of peptide-class II molecule complexes and especially of complexes with parasite peptides. The present data indicate, however, that if this process occurs, it does not lead to a clear increase of SDS-stable compact (alpha)(beta) dimers of class II. In PV that contained L. amazonensis or L. mexicana, both class II and H-2M molecules often colocalized at the level where amastigotes bind to the PV membrane, suggesting that these molecules are physically associated, directly or indirectly, and possibly interact with parasite components. Furthermore, as class II molecules, H-2M molecules were internalized by amastigotes of these Leishmania species and reached parasite compartments that also contained class II molecules. Immunostaining of H-2M within parasites was increased by treatment of infected macrophages with the cysteine protease inhibitors Z-Phe-AlaCHN2 or Z-Phe-PheCHN2 or by incubation of the parasites with the same inhibitors before infection. These data thus support the idea that amastigotes of certain Leishmania species capture and degrade some of the molecules required for antigen presentation. To examine whether endocytosis of class II molecules by the parasites occurs through interactions with parasite components involving their peptide-binding groove, we made use of the fact that a large fraction of the class II molecules of H-2M(alpha) knock-out H-2(b) mice are occupied by the peptide CLIP and are unable to bind other peptides. We found that, in Leishmania-infected macrophages of these mutant mice, class II-CLIP complexes reached PV and were internalized by amastigotes. These results thus prove that endocytosis of class II molecules by amastigotes (1) is H-2M-independent and (2) does not necessarily involve the peptide-binding pocket of these molecules. Altogether, these data are compatible with an endocytic mechanism based on general properties shared by classical and non-classical class II molecules.
Assuntos
Antígenos HLA-D/imunologia , Leishmania mexicana/imunologia , Macrófagos/imunologia , Macrófagos/parasitologia , Vacúolos/imunologia , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/imunologia , Células Cultivadas , Endocitose , Feminino , Antígenos de Histocompatibilidade Classe II/imunologia , Leishmania donovani/imunologia , Leishmania major/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Nus , Especificidade da EspécieRESUMO
Two strains of a presumed lower trypanosomatid isolated from immunocompetent and HIV-infected humans in French West Indies were investigated in vitro and in vivo in a murine experimental model. The ability of parasites to grow in vitro in bone marrow-derived macrophages and their virulence in vivo were assessed. For in vivo infection, two groups of BALB/c mice were inoculated either by the subcutaneous or intravenous route with 10(7) promastigotes at day 0. Infection was monitored by measuring parasite load in liver, spleen, foot pad, popliteal, and mesenteric lymph nodes and brain from day 7 to day 150 post-infection using a microtitration technique. Parasites multiplied in mouse macrophages in vitro. In vivo, both strains proved infective to mice and capable of visceralization and dissemination in the popliteal and mesenteric lymph nodes, liver, spleen, and even brain. Both strains elicited a strong humoral response against trypanosomatid antigen in mice, which cross-reacted with Leishmania antigen. Contrasting with the straightforward dissemination of parasites, the infection was strikingly well tolerated by the murine host with no clinical signs and minimal tissue changes around parasitized macrophage infiltrates.