RESUMO
Invasion of the central nervous system (CNS) by microorganisms is a severe and frequently fatal event during the course of many infectious diseases. It may lead to deafness, blindness, cerebral palsy, hydrocephalus, cognitive impairment or permanent neurological dysfunction in survivors. Pathogens can cross the blood-brain barrier by transcellular migration, paracellular migration and in infected macrophages. Pathogens may breach the blood-brain barrier and be recognized by antigen-presenting cells through the binding of Toll-like receptors. This induces the activation of nuclear factor kappa B or mitogen-activated protein kinase pathways and subsequently induces leukocyte infiltration and proliferation and the expression of numerous proteins involved in inflammation and the immune response. Many brain cells can produce cytokines, chemokines and other pro-inflammatory molecules in response to bacteria stimuli; as a consequence, polymorphonuclear cells are attracted and activated, and release large amounts of superoxide anion and nitric oxide, leading to peroxynitrite formation and oxidative stress. This cascade leads to lipid peroxidation, mitochondrial damage and blood-brain barrier breakdown, contributing to cellular injury during neuronal infection. Current evidence suggests that bacterial CNS infections can play a role in the etiopathogenesis of behavioral disorders by increasing pro-inflammatory cytokines and bacterial virulence factors. The aim of this review is to summarize the current knowledge of the relevant pathophysiologic steps in CNS infections.
Assuntos
Infecções Bacterianas do Sistema Nervoso Central/complicações , Transtornos Mentais/etiologia , Bactérias/patogenicidade , Morte Celular , Sistema Nervoso Central/imunologia , Infecções Bacterianas do Sistema Nervoso Central/fisiopatologia , Citocinas/fisiologia , Humanos , Sistema Imunitário/fisiopatologia , Imunidade Inata/imunologia , Transtornos Mentais/fisiopatologia , NeurôniosRESUMO
Invasion of the central nervous system (CNS) by microorganisms is a severe and frequently fatal event during the course of many infectious diseases. It may lead to deafness, blindness, cerebral palsy, hydrocephalus, cognitive impairment or permanent neurological dysfunction in survivors. Pathogens can cross the blood-brain barrier by transcellular migration, paracellular migration and in infected macrophages. Pathogens may breach the blood-brain barrier and be recognized by antigen-presenting cells through the binding of Toll-like receptors. This induces the activation of nuclear factor kappa B or mitogen-activated protein kinase pathways and subsequently induces leukocyte infiltration and proliferation and the expression of numerous proteins involved in inflammation and the immune response. Many brain cells can produce cytokines, chemokines and other pro-inflammatory molecules in response to bacteria stimuli; as a consequence, polymorphonuclear cells are attracted and activated, and release large amounts of superoxide anion and nitric oxide, leading to peroxynitrite formation and oxidative stress. This cascade leads to lipid peroxidation, mitochondrial damage and blood-brain barrier breakdown, contributing to cellular injury during neuronal infection. Current evidence suggests that bacterial CNS infections can play a role in the etiopathogenesis of behavioral disorders by increasing pro-inflammatory cytokines and bacterial virulence factors. The aim of this review is to summarize the current knowledge of the relevant pathophysiologic steps in CNS infections.
Assuntos
Humanos , Infecções Bacterianas do Sistema Nervoso Central/complicações , Transtornos Mentais/etiologia , Bactérias/patogenicidade , Morte Celular , Infecções Bacterianas do Sistema Nervoso Central/fisiopatologia , Sistema Nervoso Central/imunologia , Citocinas/fisiologia , Sistema Imunitário/fisiopatologia , Imunidade Inata/imunologia , Transtornos Mentais/fisiopatologia , NeurôniosRESUMO
Tropical infections refer to a group of diseases usually located in regions with a warm climate, particularly affecting developing countries, partly because of the conditions that allow them to thrive. However, due to the increased international travel, infectious agents that were previously limited to tropical regions pose an increasing threat to populations at risk for opportunistic infection (OI), especially those infected with the HIV. Tropical infections can facilitate HIV transmission and accelerate the progression of asymptomatic HIV infection to AIDS. Some have the potential to alter the epidemiology, natural history, and/or response to treatment of the other. The introduction of highly active antiretroviral therapy has provided a huge benefit for the vast majority of patients infected with the HIV, by allowing the immune system to recover, improving the clinical and radiological results and reducing the number of OI. On the other hand, some patients have developed various disorders of immune reconstitution, resulting in either hyper-immune inflammatory response to an exogenous antigen or autoimmunity. A significant proportion of these cases have been reported in immigrants from tropical countries to high-income countries, therefore awareness of these phenomena is needed since clinical presentations are often atypical and pose diagnostic challenges. This article reviews some of the key diagnostic aspects of tropical infections associated with HIV infection.
Assuntos
Infecções por HIV/complicações , Doenças do Sistema Nervoso/complicações , Amebíase/complicações , Terapia Antirretroviral de Alta Atividade , Brasil , Infecções Bacterianas do Sistema Nervoso Central/complicações , Infecções Fúngicas do Sistema Nervoso Central/complicações , Infecções Protozoárias do Sistema Nervoso Central/complicações , Países em Desenvolvimento , Infecções por HIV/tratamento farmacológico , Infecções por HIV/patologia , Helmintíase/complicações , Humanos , Síndrome Inflamatória da Reconstituição Imune/complicações , Microsporidiose/complicações , Doenças do Sistema Nervoso/tratamento farmacológico , Doenças do Sistema Nervoso/patologia , Toxoplasmose/complicações , Medicina Tropical , Viroses/complicaçõesRESUMO
A 41 year old man presented to the outpatient department with a three month history of difficulty in walking. He also had a history of positive sensory symptoms in the form of pins and needle sensation mostly below the waist. His symptoms had been progressive and there was no significant family history. He demonstrated a spastic gait and could only walk with assistance and support. DTR were hypertonic and sensory deficit was observed below twelfth dorsal vertebra. Sphincter abnormalities were present. Plantars were extensor bilaterally. Cerebral and spinal MRI with contrast was unremarkable. Brucella antigen titers were significantly high. CSF report was consistent with neurobrucellosis. After detailed analysis of his history, clinical picture and investigations the diagnosis of neurobrucellosis was made. Combined antimicrobial therapy was started, his neurologic condition gradually improved and he was able to walk without help after three months of treatment. Hence this case showed that neurobrucellosis may present as acquired progressive spastic paraparesis and it should always be borne in mind in patients with spastic paraparesis.
Assuntos
Adulto , Humanos , Masculino , Brucelose/complicações , Infecções Bacterianas do Sistema Nervoso Central/complicações , Paraparesia Espástica/etiologia , Antibacterianos/uso terapêutico , Brucelose/diagnóstico , Brucelose/tratamento farmacológico , Infecções Bacterianas do Sistema Nervoso Central/diagnóstico , Infecções Bacterianas do Sistema Nervoso Central/tratamento farmacológico , Imageamento por Ressonância MagnéticaRESUMO
A 41 year old man presented to the outpatient department with a three month history of difficulty in walking. He also had a history of positive sensory symptoms in the form of pins and needle sensation mostly below the waist. His symptoms had been progressive and there was no significant family history. He demonstrated a spastic gait and could only walk with assistance and support. DTR were hypertonic and sensory deficit was observed below twelfth dorsal vertebra. Sphincter abnormalities were present. Plantars were extensor bilaterally. Cerebral and spinal MRI with contrast was unremarkable. Brucella antigen titers were significantly high. CSF report was consistent with neurobrucellosis. After detailed analysis of his history, clinical picture and investigations the diagnosis of neurobrucellosis was made. Combined antimicrobial therapy was started, his neurologic condition gradually improved and he was able to walk without help after three months of treatment. Hence this case showed that neurobrucellosis may present as acquired progressive spastic paraparesis and it should always be borne in mind in patients with spastic paraparesis.