REGULATION OF CYTOKINE EXPRESSION BY HIV

HIV-1在全身性病毒感染的早期阶段感染大脑。 然而，HIV-1相关的认知/运动复合体在晚期发展， 这表明脑细胞介导的宿主反应 可能有助于抑制早期生产性感染， 大脑和神经系统疾病的发展。 宏观经济发挥作用 在艾滋病毒感染的发病机制中起着关键作用， 病毒复制和作为多功能细胞因子的来源。 我们 先前报道，单核细胞衍生的ET-1在HIV感染期间被刺激， 感染，并建议其有效的血管活性特性， 可能介导脑灌注模式的改变 与艾滋病痴呆综合症有关 然而，我们的研究与 单核细胞衍生的巨噬细胞（MDM）显示，在体外感染 嗜巨噬细胞的HIV-1分离物既不诱导ET-1的分泌， 通过已知的诱导剂LPS增强其产生。 此外，mRNA 从HIV感染和未感染的MDM制备，并使用RT-PCR进行检测 技术揭示了ET-1和一氧化氮合酶（NOS）的基因， 一种负责产生强效血管扩张剂NO的酶， 没有表达。 很可能，体外系统只关注 MDM未能反映出在细胞内发生的更复杂的细胞相互作用。 vivo. 由于HIV-1产生细胞在大脑中，如血液来源的 巨噬细胞和脑小胶质细胞，被星形胶质细胞包围，我们 确定星形胶质细胞对MDM中HIV-1表达的影响。 HIV感染的MDM与原代人星形胶质细胞共培养， 减少病毒复制。 这种效应可能是由一种 分泌因子，因为星形胶质细胞条件培养基也抑制HIV 复制MDM和多聚甲醛固定的星形胶质细胞不能分泌 细胞因子不能抑制HIV。 相反，细胞与细胞之间的接触 星形细胞瘤细胞可以增强MDM中HIV-1的复制， 与M-CSF的产生增强相关（已提交，AIDS）。 另外的研究表明，诱导型一氧化氮合酶（iNOS）的表达与 星形胶质细胞同时产生NO，但不是MDM，当星形胶质细胞 与HIV感染的MDM共培养。 与此同时，艾滋病毒感染率也在下降。 复制的 尽管来自HIV感染的MDM的共培养物的上清液 星形胶质细胞刺激星形胶质细胞中的iNOS表达， 未检测到诱导iNOS表达。 竞争性NOS抑制剂 部分逆转了星形胶质细胞的HIV-1抑制作用（提交， 血液）。 这表明星形胶质细胞在决定 神经系统HIV疾病的过程通过产生HIV调节剂 细胞因子和iNOS/NO的表达。这也使我们推测， 在HIV疾病中观察到的神经损伤可能是由于长期的，高水平的 水平，NO的生产失调。

HIV-1 infects the brain in the early stage of systemic viral infection. However, HIV-1-associated cognitive/ motor complex develops later in the course of disease, suggesting that host responses mediated by brain cells may contribute to inhibition of the early productive infection in the brain and the development of neurologic disease. Macrophages play a critical role in the pathogenesis of HIV infection, both as targets for viral replication and as sources of multifunctional cytokines. We previously reported that monocyte-derived ET-1 is stimulated during HIV infection and suggested that its potent vasoactive properties could potentially mediate alterations in the cerebral perfusion pattern associated with AIDS dementia complex. However, our studies with monocyte derived macrophages (MDM) revealed that in vitro infection with macrophage tropic HIV-1 isolates neither induces secretion of ET-1 nor potentiates its production by the known inducer, LPS. In addition, mRNA prepared from HIV-infected and uninfected MDM and examined using RT-PCR techniques revealed that genes for ET-1 and nitric oxide synthase (NOS), an enzyme responsible for production of the potent vasodilator, NO, are not expressed. It is probable that the in vitro system looking only at MDM fails to reflect the more complex cellular interactions occurring in vivo. Since HIV-1 producing cells in the brain, such as blood-derived macrophages and brain microglia, are surrounded by astrocytes, we determined the effect of astrocytes on HIV-1 expression in MDM. Co-culture of HIV-infected MDM with primary human astrocytes resulted in diminished virus replication. This effect was likely mediated by a secreted factor, since astrocyte conditioned medium also suppressed HIV replication MDM and paraformaldehyde fixed astrocytes unable to secrete cytokines failed to inhibit HIV. In contrast, cell-to-cell contact with astrocytoma cells can enhance replication of HIV-1 in MDM, which correlates with enhanced production of M-CSF (submitted, AIDS). Additional studies revealed the expression of inducible NOS (iNOS) with concomitant production of NO in astrocytes, but not MDM, when astrocytes were cocultured with HIV-infected MDM. This coincided with decreased HIV replication. Although supernatants from cocultures of HIV-infected MDM and astrocytes stimulated iNOS expression in astrocytes, cytokines known to induce iNOS expression were not detected. A competitive NOS inhibitor partially reversed the HIV-1 suppressive effect of astrocytes (submitted, BLOOD). This suggests that astrocytes play a pivotal role in determining the course of neurologic HIV disease via production of HIV modulating cytokines and expression of iNOS/NO. It also leads us to speculate that neurologic damage observed in HIV disease may ensue from prolonged, high level, dysregulated production of NO.