RESUMO
The Apicomplexa protozoan Toxoplasma gondii is a mandatory intracellular parasite and the causative agent of toxoplasmosis. This illness is of medical importance due to its high prevalence worldwide and may cause neurological alterations in immunocompromised persons. In chronically infected immunocompetent individuals, this parasite forms tissue cysts mainly in the brain. In addition, T. gondii infection has been related to mental illnesses such as schizophrenia, bipolar disorder, depression, obsessive-compulsive disorder, as well as mood, personality, and other behavioral changes. In the present study, we evaluated the kinetics of behavioral alterations in a model of chronic infection, assessing anxiety, depression and exploratory behavior, and their relationship with neuroinflammation and parasite cysts in brain tissue areas, blood-brain-barrier (BBB) integrity, and cytokine status in the brain and serum. Adult female C57BL/6 mice were infected by gavage with 5 cysts of the ME-49 type II T. gondii strain, and analyzed as independent groups at 30, 60 and 90 days postinfection (dpi). Anxiety, depressive-like behavior, and hyperactivity were detected in the early (30 dpi) and long-term (60 and 90 dpi) chronic T. gondii infection, in a direct association with the presence of parasite cysts and neuroinflammation, independently of the brain tissue areas, and linked to BBB disruption. These behavioral alterations paralleled the upregulation of expression of tumor necrosis factor (TNF) and CC-chemokines (CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1ß and CCL5/RANTES) in the brain tissue. In addition, increased levels of interferon-gamma (IFNγ), TNF and CCL2/MCP-1 were detected in the peripheral blood, at 30 and 60 dpi. Our data suggest that the persistence of parasite cysts induces sustained neuroinflammation, and BBB disruption, thus allowing leakage of cytokines of circulating plasma into the brain tissue. Therefore, all these factors may contribute to behavioral changes (anxiety, depressive-like behavior, and hyperactivity) in chronic T. gondii infection.
Assuntos
Comportamento Animal , Barreira Hematoencefálica/patologia , Barreira Hematoencefálica/parasitologia , Inflamação/parasitologia , Toxoplasma/fisiologia , Toxoplasmose Cerebral/parasitologia , Animais , Ansiedade/complicações , Ansiedade/fisiopatologia , Edema Encefálico/complicações , Edema Encefálico/fisiopatologia , Doença Crônica , Citocinas/metabolismo , Depressão/complicações , Depressão/fisiopatologia , Feminino , Inflamação/fisiopatologia , Locomoção , Camundongos Endogâmicos C57BL , Força Muscular , Parasitos/fisiologia , Fatores de Tempo , Toxoplasmose Cerebral/fisiopatologia , Regulação para CimaRESUMO
BACKGROUND: Malaria is a parasitic disease that compromises the human host. Currently, control of the Plasmodium falciparum burden is centered on artemisinin-based combination therapies. However, decreased sensitivity to artemisinin and derivatives has been reported, therefore it is important to identify new therapeutic strategies. METHOD: We used human erythrocytes infected with P. falciparum and experimental cerebral malaria (ECM) animal model to assess the potential antimalarial effect of eugenol, a component of clove bud essential oil. RESULTS: Plasmodium falciparum cultures treated with increasing concentrations of eugenol reduced parasitemia in a dose-dependent manner, with IC50 of 532.42 ± 29.55 µM. This effect seems to be irreversible and maintained even in the presence of high parasitemia. The prominent effect of eugenol was detected in the evolution from schizont to ring forms, inducing important morphological changes, indicating a disruption in the development of the erythrocytic cycle. Aberrant structural modification was observed by electron microscopy, showing the separation of the two nuclear membrane leaflets as well as other subcellular membranes, such as from the digestive vacuole. Importantly, in vivo studies using ECM revealed a reduction in blood parasitemia and cerebral edema when mice were treated for 6 consecutive days upon infection. CONCLUSIONS: These data suggest a potential effect of eugenol against Plasmodium sp. with an impact on cerebral malaria. GENERAL SIGNIFICANCE: Our results provide a rational basis for the use of eugenol in therapeutic strategies to the treatment of malaria.
Assuntos
Antimaláricos/farmacologia , Edema Encefálico/tratamento farmacológico , Eugenol/farmacologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária Cerebral/tratamento farmacológico , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/parasitologia , Edema Encefálico/parasitologia , Modelos Animais de Doenças , Eritrócitos/efeitos dos fármacos , Eritrócitos/parasitologia , Humanos , Concentração Inibidora 50 , Estágios do Ciclo de Vida/fisiologia , Malária Cerebral/parasitologia , Malária Falciparum/parasitologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/crescimento & desenvolvimento , Plasmodium berghei/parasitologia , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/patogenicidadeRESUMO
Toxoplasmosis is one of the leading parasitic diseases worldwide. Some data suggest that chronic acquired toxoplasmosis could be linked to behavioral alterations in humans. The parasite infects neurons, forming immunologically silent cysts. Cerebral microcirculation homeostasis is determinant to brain functions, and pathologic states can alter capillarity or blood perfusion, leading to neurodegeneration and cognitive deficits. Albino mice were infected with Toxoplasma gondii (ME49 strain) and analyzed after 10, 40, and 180 days. Infected mice presented decreased cerebral blood flow at 10 and 40 days post infection (dpi), which were restored at 180 dpi, as shown by laser speckle contrast imaging. Intravital microscopy demonstrated that infection led to significant capillary rarefaction, accompanied by neuroinflammation, with microglial activation and increased numbers of rolling and adherent leukocytes to the wall of cerebral capillaries. Acetylcholine-induced vasodilation was altered at all time points, and blood brain barrier permeability was evident in infected animals at 40 dpi. Infection reduced angiogenesis, with a decreased number of isolectin B4-stained blood vessels and a decrease in length and branching of laminin-stained capillaries. Sulfadiazine reduced parasite load and partially repaired microvascular damages. We conclude that T. gondii latent infection causes a harmful insult in the brain, promoting neuroinflammation and microcirculatory dysfunction in the brain, with decreased angiogenesis and can contribute to a neurodegenerative process.
Assuntos
Barreira Hematoencefálica/patologia , Endotélio Vascular/patologia , Inflamação/patologia , Microcirculação , Neurônios/patologia , Toxoplasma/patogenicidade , Toxoplasmose Cerebral/patologia , Animais , Barreira Hematoencefálica/imunologia , Barreira Hematoencefálica/parasitologia , Endotélio Vascular/imunologia , Endotélio Vascular/parasitologia , Feminino , Inflamação/imunologia , Inflamação/parasitologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/imunologia , Neurônios/parasitologia , Toxoplasmose Cerebral/imunologia , Toxoplasmose Cerebral/parasitologiaRESUMO
Naegleria fowleri causes a fatal disease known as primary amoebic meningoencephalitis. This condition is characterized by an acute inflammation that originates from the free passage of peripheral blood cells to the central nervous system through the alteration of the blood-brain barrier. In this work, we established models of the infection in rats and in a primary culture of endothelial cells from rat brains with the aim of evaluating the activation and the alterations of these cells by N. fowleri. We proved that the rat develops the infection similar to the mouse model. We also found that amoebic cysteine proteases produced by the trophozoites and the conditioned medium induced cytopathic effect in the endothelial cells. In addition, N. fowleri can decrease the transendothelial electrical resistance by triggering the destabilization of the tight junction proteins claudin-5, occludin, and ZO-1 in a time-dependent manner. Furthermore, N. fowleri induced the expression of VCAM-1 and ICAM-1 and the production of IL-8, IL-1ß, TNF-α, and IL-6 as well as nitric oxide. We conclude that N. fowleri damaged the blood-brain barrier model by disrupting the intercellular junctions and induced the presence of inflammatory mediators by allowing the access of inflammatory cells to the olfactory bulbs.
Assuntos
Barreira Hematoencefálica/parasitologia , Infecções Protozoárias do Sistema Nervoso Central/metabolismo , Células Endoteliais/metabolismo , Naegleria fowleri/metabolismo , Naegleria fowleri/patogenicidade , Proteínas de Junções Íntimas/metabolismo , Animais , Infecções Protozoárias do Sistema Nervoso Central/parasitologia , Infecções Protozoárias do Sistema Nervoso Central/patologia , Claudina-5/metabolismo , Cisteína Proteases/metabolismo , Citocinas/metabolismo , Modelos Animais de Doenças , Inflamação , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-1beta/metabolismo , Interleucina-8/metabolismo , Masculino , Meningoencefalite/parasitologia , Meningoencefalite/patologia , Camundongos , Mucosa/parasitologia , Mucosa/patologia , Ocludina/metabolismo , Ratos , Ratos Wistar , Trofozoítos/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Conchas Nasais/patologia , Molécula 1 de Adesão de Célula Vascular/metabolismo , Proteína da Zônula de Oclusão-1/metabolismoRESUMO
Malaria continues to be a major global health problem, and over 40% of the world's population is at risk. Severe or complicated malaria is defined by clinical or laboratory evidence of vital organ dysfunction, including dysfunction of the central nervous system (CNS). The pathogenesis of complicated malaria has not been completely elucidated; however, the development of the multiorgan affection seems to play an important role in the disruption of the blood brain barrier (BBB) that protects the CNS against chemical insults. Historically, the BBB has received more attention in the pathogenesis of malaria than have the cerebrospinal fluid-brain barrier (CSFBB) and ependymal cells. This perspective may be misguided because, in the context of disease or toxicity, the CSFBB is more vulnerable to many foreign invaders than are the capillaries. Given the lack on studies of the damage to the CSFBB and ependymal epithelium in experimental murine malaria, the present study evaluated morphological changes in the ependymal cells of CD-1 male mice infected with lethal Plasmodium yoelii yoelii (Pyy) via histopathology and scanning electron microscopy (SEM). Samples were taken two, four and six days post-infection (PI). No lesions were observed upon the initial infection. By the fourth day PI, fourth ventricle ependymal samples exhibited disruptions and roughened epithelia. More severe injuries were observed at six days PI and included thickened cilia and deep separations between the ependymal intercellular spaces. In some of the analyzed areas, the absence of microvilli and cell layer detachment were observed, and some areas exhibited blebbing surfaces. The ependymal cell lesions observed in the CD1 male mice infected with lethal Pyy seemed to facilitate the paracellular permeability of the CSFBB and consequently promote the access of inflammatory mediators and toxic molecules through the barrier, which resulted in damage to the brain tissue. Understanding the mechanism of ependymal disruption during lethal murine malaria could help to elucidate the local and systemic factors that are involved in the pathogenesis of the disease and may provide essential clues for the prevention and treatment of complicated human malaria.
Assuntos
Epêndima/patologia , Malária/patologia , Plasmodium yoelii , Animais , Barreira Hematoencefálica/parasitologia , Barreira Hematoencefálica/patologia , Encéfalo/parasitologia , Encéfalo/patologia , Contagem de Células , Ventrículos Cerebrais/parasitologia , Ventrículos Cerebrais/patologia , Malária/parasitologia , Masculino , Mesencéfalo/parasitologia , Mesencéfalo/patologia , CamundongosRESUMO
Cerebral malaria (CM) is a life-threatening complication of Plasmodium falciparum malaria that continues to be a major global health problem. Brain vascular dysfunction is a main factor underlying the pathogenesis of CM and can be a target for the development of adjuvant therapies for the disease. Vascular occlusion by parasitised red blood cells and vasoconstriction/vascular dysfunction results in impaired cerebral blood flow, ischaemia, hypoxia, acidosis and death. In this review, we discuss the mechanisms of vascular dysfunction in CM and the roles of low nitric oxide bioavailability, high levels of endothelin-1 and dysfunction of the angiopoietin-Tie2 axis. We also discuss the usefulness and relevance of the murine experimental model of CM by Plasmodium berghei ANKA to identify mechanisms of disease and to screen potential therapeutic interventions.
Assuntos
Eritrócitos/parasitologia , Malária Cerebral/fisiopatologia , Angiopoietina-2/metabolismo , Animais , Barreira Hematoencefálica/parasitologia , Circulação Cerebrovascular , Modelos Animais de Doenças , Endotelinas/metabolismo , Interações Hospedeiro-Parasita , Humanos , Malária Cerebral/parasitologia , Camundongos , Óxido Nítrico/metabolismo , Vasoconstrição/fisiologiaRESUMO
Cerebral malaria (CM) is a life-threatening complication of Plasmodium falciparum malaria that continues to be a major global health problem. Brain vascular dysfunction is a main factor underlying the pathogenesis of CM and can be a target for the development of adjuvant therapies for the disease. Vascular occlusion by parasitised red blood cells and vasoconstriction/vascular dysfunction results in impaired cerebral blood flow, ischaemia, hypoxia, acidosis and death. In this review, we discuss the mechanisms of vascular dysfunction in CM and the roles of low nitric oxide bioavailability, high levels of endothelin-1 and dysfunction of the angiopoietin-Tie2 axis. We also discuss the usefulness and relevance of the murine experimental model of CM by Plasmodium berghei ANKA to identify mechanisms of disease and to screen potential therapeutic interventions.
Assuntos
Animais , Humanos , Camundongos , Eritrócitos/parasitologia , Malária Cerebral/fisiopatologia , /metabolismo , Barreira Hematoencefálica/parasitologia , Circulação Cerebrovascular , Modelos Animais de Doenças , Endotelinas/metabolismo , Interações Hospedeiro-Parasita , Malária Cerebral/parasitologia , Óxido Nítrico/metabolismo , Vasoconstrição/fisiologiaRESUMO
Neurocysticercosis is a widely prevalent disease in the tropics that causes seizures and a variety into of neurological symptoms in most of the world. Experimental models are limited and do not allow assessment of the degree of inflammation around brain cysts. The vital dye Evans Blue (EB) was injected to 11 pigs naturally infected with Taenia solium cysts to visually identify the extent of disruption of the blood-brain barrier. A total of 369 cysts were recovered from the 11 brains and classified according to the staining of their capsules as blue or unstained. The proportion of cysts with blue capsules was significantly higher in brains from pigs that had received anthelmintic treatment 48 and 120h before the EB infusion, indicating a greater compromise of the blood-brain barrier due to treatment. The model could be useful for understanding the pathology of treatment-induced inflammation in neurocysticercosis.
Assuntos
Anti-Helmínticos/uso terapêutico , Barreira Hematoencefálica/patologia , Neurocisticercose/veterinária , Praziquantel/uso terapêutico , Doenças dos Suínos/patologia , Animais , Anti-Helmínticos/farmacologia , Barreira Hematoencefálica/parasitologia , Encéfalo/parasitologia , Encéfalo/patologia , Corantes , Azul Evans , Extravasamento de Materiais Terapêuticos e Diagnósticos , Neurocisticercose/tratamento farmacológico , Neurocisticercose/patologia , Praziquantel/farmacologia , Suínos , Doenças dos Suínos/tratamento farmacológico , Doenças dos Suínos/parasitologia , Taenia solium/efeitos dos fármacosRESUMO
In order to investigate the differential ALCAM, ICAM-1 and VCAM-1 adhesion molecules mRNA expression and the blood-brain barrier (BBB) permeability in C57BL/6 and BALB/c mice in Toxoplasma gondii infection, animals were infected with ME-49 strain. It was observed higher ALCAM on day 9 and VCAM-1 expression on days 9 and 14 of infection in the central nervous system (CNS) of C57BL/6 compared to BALB/c mice. The expression of ICAM-1 was high and similar in the CNS of both lineages of infected mice. In addition, C57BL/6 presented higher BBB permeability and higher IFN-gamma and iNOS expression in the CNS compared to BALB/c mice. The CNS of C57BL/6 mice presented elevated tissue pathology and parasitism. In conclusion, our data suggest that the higher adhesion molecules expression and higher BBB permeability contributed to the major inflammatory cell infiltration into the CNS of C57BL/6 mice that was not efficient to control the parasite.