Levi G, Patrizio M, Bernardo A, Petrucci T C, Agresti C
Laboratory of Pathophysiology, Istituto Superiore di Sanità, Rome, Italy.
Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1541-5. doi: 10.1073/pnas.90.4.1541.
The goal of our study was to assess whether the human immunodeficiency virus (HIV) coat protein gp120 induces functional alterations in astrocytes and microglia, known for their reactivity and involvement in most types of brain pathology. We hypothesized that gp120-induced anomalies in glial functions, if present, might be mediated by changes in the levels of intracellular messengers important for signal transduction, such as cAMP. Acute (10 min) exposure of cultured rat cortical astrocytes or microglia to 100 pM gp120 caused only a modest (50-60%), though statistically significant, elevation in cAMP levels, which was antagonized by the beta-adrenergic receptor antagonist propranolol. More importantly, the protein substantially depressed [by 30% (astrocytes) and 50% (microglia)] the large increase in cAMP induced by the beta-adrenergic agonist isoproterenol (10 nM), without affecting that induced by direct adenylate cyclase stimulation by forskolin. Qualitatively similar results were obtained using a glial fibrillary acidic protein (GFAP)-positive human glioma cell line. The depression of the beta-adrenergic response had functional consequences in both astrocytes and microglia. In astrocytes we studied the phosphorylation of the two major cytoskeletal proteins, vimentin and GFAP, which is normally stimulated by isoproterenol, and found that gp120 partially (40-50%) prevented such stimulation. In microglial cells, which are the major producers of inflammatory cytokines within the brain, gp120 partially antagonized the negative beta-adrenergic modulation of lipopolysaccharide (10 ng/ml)-induced production of tumor necrosis factor alpha. Our results suggest that, by interfering with the beta-adrenergic regulation of astrocytes and microglia, gp120 may alter astroglial "reactivity" and upset the delicate cytokine network responsible for the defense against viral and opportunistic infections.
我们研究的目的是评估人类免疫缺陷病毒（HIV）包膜蛋白gp120是否会诱导星形胶质细胞和小胶质细胞发生功能改变，这两种细胞以其反应性以及参与大多数类型的脑部病变而闻名。我们推测，如果存在gp120诱导的神经胶质细胞功能异常，可能是由对信号转导重要的细胞内信使水平的变化介导的，例如环磷酸腺苷（cAMP）。将培养的大鼠皮质星形胶质细胞或小胶质细胞急性（10分钟）暴露于100 pM gp120，仅引起cAMP水平适度（50 - 60%）的升高，尽管具有统计学意义，这种升高可被β - 肾上腺素能受体拮抗剂普萘洛尔拮抗。更重要的是，该蛋白显著降低了[星形胶质细胞降低30%，小胶质细胞降低50%]由β - 肾上腺素能激动剂异丙肾上腺素（10 nM）诱导的cAMP大幅升高，而不影响由福斯可林直接刺激腺苷酸环化酶所诱导的cAMP升高。使用胶质纤维酸性蛋白（GFAP）阳性的人胶质瘤细胞系也获得了定性相似的结果。β - 肾上腺素能反应的抑制在星形胶质细胞和小胶质细胞中都产生了功能后果。在星形胶质细胞中，我们研究了两种主要细胞骨架蛋白波形蛋白和GFAP的磷酸化，它们通常由异丙肾上腺素刺激，发现gp120部分（40 - 50%）阻止了这种刺激。在作为脑内炎性细胞因子主要产生者的小胶质细胞中，gp120部分拮抗了β - 肾上腺素能对脂多糖（10 ng/ml）诱导的肿瘤坏死因子α产生的负调节作用。我们的结果表明，通过干扰星形胶质细胞和小胶质细胞的β - 肾上腺素能调节，gp120可能会改变星形胶质细胞的“反应性”，并扰乱负责抵御病毒和机会性感染的精细细胞因子网络。
