Perno C F, Yarchoan R, Cooney D A, Hartman N R, Gartner S, Popovic M, Hao Z, Gerrard T L, Wilson Y A, Johns D G
Clinical Oncology Program, National Cancer Institute, Bethesda, Maryland 20892.
J Exp Med. 1988 Sep 1;168(3):1111-25. doi: 10.1084/jem.168.3.1111.
Because of the probable role of HIV-infected monocyte/macrophages in the pathogenesis and progression of AIDS, it is essential that antiretroviral therapy address viral replication in cells of this lineage. Several dideoxynucleosides have been shown to have potent in vitro and, in the case of 3'-azido-2',3'-dideoxythymidine (AZT) and 2',3'-dideoxycytidine (ddC), in vivo activity against HIV. However, because these compounds must be phosphorylated (activated) in target cells, and because monocyte/macrophages may have levels of kinases that differ from those in lymphocytes, we investigated the capacity of these drugs to suppress HIV replication in monocyte/macrophages using HIV-1/HTLV-IIIBa-L (a monocytotropic isolate). In the present study, we observed that HTLV-IIIBa-L replication in fresh human peripheral blood monocyte/macrophages was suppressed by each of three dideoxynucleosides: 3'-azido-2',3'-dideoxythymidine (AZT), 2',3'-dideoxycytidine (ddC), and 2',3'-dideoxyadenosine (ddA). Similar results were observed in 5-d-cultured monocyte/macrophages, although higher concentrations of the drugs were required. We then studied the metabolism of AZT and ddC in such cells. The phosphorylation of ddC to a triphosphate moiety was somewhat decreased in monocyte/macrophages as compared with H9 T cells. On the other hand, the phosphorylation of AZT in monocyte/macrophages was markedly decreased to 25% or less of the level in T cells. However, when we examined the level of the normal endogenous 2'-deoxynucleoside triphosphate pools, which compete with 2',3'-dideoxynucleoside triphosphate for viral reverse transcriptase, we found that the level of 2'-deoxycytidine-triphosphate (dCTP) was six- to eightfold reduced, and that of 2'-deoxythymidine-triphosphate (dTTP) was only a small fraction of that found in T cell lines. These results suggest that the ratio of dideoxynucleoside triphosphate to normal deoxynucleoside triphosphate is a crucial factor in determining the antiviral activity of dideoxynucleosides in HIV target cells, and that the lower levels of dTTP may account for the antiretroviral activity of AZT in the face of inefficient phosphorylation of this compound.
由于感染HIV的单核细胞/巨噬细胞在艾滋病发病机制及病情进展中可能发挥作用，抗逆转录病毒疗法必须针对该细胞系中的病毒复制。已证实几种双脱氧核苷在体外具有强大活性，就3'-叠氮-2',3'-双脱氧胸苷（AZT）和2',3'-双脱氧胞苷（ddC）而言，在体内也具有抗HIV活性。然而，由于这些化合物必须在靶细胞中磷酸化（激活），且单核细胞/巨噬细胞中的激酶水平可能与淋巴细胞不同，我们使用HIV-1/HTLV-IIIBa-L（一种嗜单核细胞分离株）研究了这些药物抑制单核细胞/巨噬细胞中HIV复制的能力。在本研究中，我们观察到三种双脱氧核苷中的每一种都能抑制新鲜人外周血单核细胞/巨噬细胞中的HTLV-IIIBa-L复制：3'-叠氮-2',3'-双脱氧胸苷（AZT）、2',3'-双脱氧胞苷（ddC）和2',3'-双脱氧腺苷（ddA）。在培养5天的单核细胞/巨噬细胞中也观察到了类似结果，尽管所需药物浓度更高。然后我们研究了AZT和ddC在此类细胞中的代谢情况。与H9 T细胞相比，单核细胞/巨噬细胞中ddC磷酸化为三磷酸部分的程度有所降低。另一方面，单核细胞/巨噬细胞中AZT的磷酸化显著降低至T细胞中水平的25%或更低。然而，当我们检测与2',3'-双脱氧核苷三磷酸竞争病毒逆转录酶的正常内源性2'-脱氧核苷三磷酸池水平时，我们发现2'-脱氧胞苷三磷酸（dCTP）水平降低了6至8倍，而2'-脱氧胸苷三磷酸（dTTP）水平仅为T细胞系中水平的一小部分。这些结果表明，双脱氧核苷三磷酸与正常脱氧核苷三磷酸的比例是决定双脱氧核苷在HIV靶细胞中抗病毒活性至关重要的因素，并且面对该化合物磷酸化效率低下的情况，较低水平的dTTP可能解释了AZT的抗逆转录病毒活性。
