RESUMO
HIV-1-associated dementia (HAD) is an important complication of HIV-1 infection. Reactive astrogliosis is a key pathological feature in HAD brains and in other central nervous system (CNS) diseases. Activated astroglia may play a critical role in CNS inflammatory diseases such as HAD. In order to test the hypothesis that activated astrocytes cause neuronal injury, we stimulated primary human fetal astrocytes with HAD-relevant pro-inflammatory cytokine IL-1beta. IL-1beta-activated astrocytes induced apoptosis and significant changes in metabolic activity in primary human neurons. An FITC-conjugated pan-caspase inhibitor peptide FITC-VAD-FMK was used for confirming caspase activation in neurons. IL-1beta activation enhanced the expression of death protein FasL in astrocytes, suggesting that FasL is one of the potential factors responsible for neurotoxicity observed in HAD and other CNS diseases involving glial inflammation. Our data presented here add to the developing picture of role of activated glia in HAD pathogenesis.
Assuntos
Astrócitos/efeitos dos fármacos , Astrócitos/fisiologia , Interleucina-1/farmacologia , Neurônios/fisiologia , Análise de Variância , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Contagem de Células/métodos , Células Cultivadas , Meios de Cultivo Condicionados/farmacologia , Interações Medicamentosas , Ensaio de Imunoadsorção Enzimática/métodos , Proteína Ligante Fas , Feto , Regulação da Expressão Gênica/efeitos dos fármacos , Proteína Glial Fibrilar Ácida/metabolismo , Ácido Glutâmico/farmacologia , Humanos , Imuno-Histoquímica/métodos , Marcação In Situ das Extremidades Cortadas/métodos , Indóis , Proteínas de Filamentos Intermediários/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Nestina , Proteínas de Neurofilamentos/metabolismo , Neurônios/efeitos dos fármacos , Sais de Tetrazólio , Tiazóis , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Reactive astrogliosis is a prominent pathological feature of HIV-1-associated dementia (HAD). We hypothesized that in HAD, astrocytes activated with proinflammatory stimuli such as IL-1beta express Fas ligand (FasL), a death protein. IL-1beta and HIV-1-activated astrocytes expressed FasL mRNA and protein. Luciferase reporter constructs showed that IL-1beta and HIV-1 upregulated FasL promoter activity (p<0.001). The NF-kappaB pathway was involved as shown by inhibition with SN50 and dominant negative IkappaBalpha mutants. Brain extracts from HAD patients had significantly elevated FasL levels compared to HIV-seropositive (p<0.001) and seronegative individuals (p<0.01). We propose that astrocyte expression of FasL may participate in neuronal injury in HAD.