RESUMO
Human immunodeficiency virus type 2 (HIV-2) is known to be less pathogenic than HIV-1. However, the mechanism(s) underlying the decreased HIV-2 pathogenicity is not fully understood. Herein, we report that ß-chemokine CCL2 expression was increased in HIV-1-infected human monocyte-derived macrophages (MDM) but decreased in HIV-2-infected MDM when compared to uninfected MDM. Inhibition of CCL2 expression following HIV-2 infection occurred at both protein and mRNA levels. By microarray analysis, quantitative PCR, and Western blotting, we identified that Signal Transducer and Activator of Transcription 1 (STAT1), a critical transcription factor for inducing CCL2 gene expression, was also reduced in HIV-2-infected MDM. Blockade of STAT1 in HIV-infected MDM using a STAT1 inhibitor significantly reduced the production of CCL2. In contrast, transduction of STAT1-expressing pseudo-retrovirus restored CCL2 production in HIV-2-infected MDM. These findings support the concept that CCL2 inhibition in HIV-2-infected MDM is meditated by reduction of STAT1. Furthermore, we showed that STAT1 reduction in HIV-2-infected MDM was regulated by the CUL2/RBX1 ubiquitin E3 ligase complex-dependent proteasome pathway. Knockdown of CUL2 or RBX1 restored the expression of STAT1 and CCL2 in HIV-2-infected MDM. Taken together, our findings suggest that differential regulation of the STAT1-CCL2 axis may be one of the mechanisms underlying the different pathogenicity observed for HIV-1 and HIV-2.
Assuntos
Quimiocina CCL2 , Infecções por HIV , HIV-1 , HIV-2 , Humanos , Células Cultivadas , Regulação da Expressão Gênica , Soropositividade para HIV , HIV-1/genética , HIV-2/genética , Macrófagos , Virulência , Replicação Viral , Quimiocina CCL2/metabolismo , Infecções por HIV/metabolismo , Infecções por HIV/virologiaRESUMO
The objective of this study was to determine whether simian immunodeficiency virus (SIV) infection of macaques could be used as a model system to assess the role of selenium in AIDS. Plasma and serum selenium levels were determined by standard assays in monkeys before and after inoculation of SIV. SIV-infected cells or cells expressing the HIV Tat protein were labeled with 75Se, and protein extracts were prepared and electrophoresed to analyze selenoprotein expression. Total tRNA was isolated from CEMx174 cells infected with SIV or from KK1 cells infected with HIV, and selenocysteine tRNA isoforms were characterized by reverse phase chromatography. SIV-infected monkeys show a decrease in blood selenium levels similar to that observed in AIDS with development of SAIDS. Cells infected with SIV in vitro exhibit reduced selenoprotein levels and an accumulation of small molecular weight selenium compounds relative to uninfected cells. Examination of the selenocysteine tRNA isoforms in HIV-infected KK1 cells or SIV-infected CEMx174 cells reveals an isoform distribution characteristic of selenium-deficient cells. Furthermore, transfection of Jurkat E6 cells with the Tat gene selectively altered selenoprotein synthesis, with GPX4 and Sep15 being the most inhibited and TR1 the most enhanced. Taken together, the data show that monkeys infected with SIV in vivo and cells infected with SIV in vitro will provide appropriate models for investigating the mechanism(s) responsible for reduced selenium levels that accompany the progression of AIDS in HIV disease.
Assuntos
Síndrome da Imunodeficiência Adquirida/sangue , Modelos Animais de Doenças , Macaca mulatta/sangue , Macaca mulatta/virologia , Selênio/sangue , Síndrome de Imunodeficiência Adquirida dos Símios/sangue , Animais , Linhagem Celular , Progressão da Doença , Feminino , Regulação da Expressão Gênica , Produtos do Gene tat/genética , Produtos do Gene tat/metabolismo , HIV/fisiologia , Humanos , Células Jurkat , Ligação Proteica , Biossíntese de Proteínas , Proteínas/genética , Proteínas/metabolismo , RNA de Transferência/análise , RNA de Transferência/genética , Radioisótopos de Selênio/metabolismo , Selenoproteínas , Vírus da Imunodeficiência Símia/fisiologia , Produtos do Gene tat do Vírus da Imunodeficiência HumanaRESUMO
Macrophage colony-stimulating factor (M-CSF) enhances the susceptibility of macrophages to infection with HIV-1, in part by increasing the expression of CD4 and CCR5. Human monocyte-derived macrophages (MDMs) infected in vitro with HIV-1 endogenously produce M-CSF, with kinetics paralleling virus replication, which can lead to enhanced spreading of the infection. AZT and ritonavir both inhibit HIV replication, but their impact on M-CSF production by HIV-infected human MDMs is unknown. The dose response and kinetics of virus replication in the presence of AZT and ritonavir were determined for HIV-infected MDMs from HIV-seronegative donors. Harvested supernatants were monitored for reverse transcriptase activity, M-CSF production, and HIV proteins. Our data suggest that threshold levels of HIV replication must occur before maximum M-CSF production is induced. Addition of AZT or ritonavir before or after establishment of productive HIV infection dramatically reduces virus replication and M-CSF production by human MDMs. However, ongoing virus replication and M-CSF production are slow to return to baseline levels after addition of AZT or ritonavir, suggesting that HIV replication and virion release from infected macrophages continue long after initiation of antiretroviral therapy. Our results suggest that, in human macrophages, HIV-1 replication and M-CSF production are inextricably linked, such that inhibition of one leads to a concomitant reduction of the other. Low-level HIV replication and M-CSF release during ongoing antiretroviral therapies may facilitate the survival and maintenance of infected macrophages and suggests that additional therapies targeting M-CSF may be critical for elimination of macrophage reservoirs.
