REGULATION OF M-CSF PRODUCTION IN HUMAN MONOCYTES

我们先前报道，感染HIV-1的单核细胞来源的巨噬细胞(MDM)产生高水平的巨噬细胞集落刺激因子(M-CSF)。M-CSF的产生与HIV-1产生的速度和数量平行，并且依赖于病毒的活跃复制(JI，1995)。其他人发现，淋巴因子白介素2(IL-2)上调M-CSF受体的表达，促进人类单核细胞产生M-CSF，从而促进分化，增加MDM对HIV-1感染的易感性。IL-2用于治疗艾滋病患者的CD4+T细胞的恢复，但它在给药后不久就会导致未知细胞中的HIV-1RNA短暂爆发。我们研究了IL-2通过上调M-CSF的产生来增强巨噬细胞中HIV-1表达的体外能力。我们发现，感染前暴露于IL-2的MDM导致HIV-1复制急剧下降，这与IL-2诱导的HIV-1受体CD4和趋化因子共受体CCR5的下调有关。然而，M-CSF的产生不受调节，这表明IL-2不仅有助于恢复艾滋病患者的免疫功能，还可能通过减少HIV-1受体和辅助受体的表达来帮助预防健康巨噬细胞的感染(AIDS 1998)。虽然M-CSF可以调节MDM感染HIV-1的易感性和感染率，并且感染后其产量增加，但其在MDM感染其他病毒中的作用尚未确定。我们用一组单链RNA病毒感染MDM，包括HIV-1、HIV-2、麻疹病毒(MV)和呼吸道合胞病毒(RSV)。我们发现，单核细胞株HIV-1或HIV-2感染MDM后，M-CSF的产生增加。然而，感染MV或RSV的MDM不能诱导M-CSF的产生，但可导致选择性促炎细胞因子和β趋化因子的产生。用AZT治疗感染艾滋病毒的MDM导致完全抑制HIV-1复制，这阻止了M-CSF mRNA和蛋白的增加，并证实了病毒复制的必要性。在HIV感染的MDM培养中加入M-CSF拮抗剂，包括抗M-CSF和可溶性M-CSF受体的单抗和多克隆抗体，可显著抑制HIV-1的复制。此外，经M-CSF拮抗剂处理后，HIV-1感染MDM分泌的单核细胞趋化因子MIP-1α的产生也显著减少。综上所述，这些结果提示，M-CSF的生物拮抗剂可能是有效的治疗方法，通过阻断HIV-1的产生，减少趋化因子(MIP-1α)对HIV敏感的T细胞和巨噬细胞的募集，从而抑制HIV-1在MDM中的复制，防止感染的MDM作为HIV的储存库而建立和维持。

We previously reported that monocyte-derived macrophages (MDM) infected with HIV-1 produce high levels of macrophage colony stimulating factor (M-CSF). M-CSF production parallels both the rate and amount of HIV-1 produced and is dependent on active replication of the virus (JI 1995). Others have found that the lymphokine, interleukin-2 (IL-2), upregulates M-CSF receptor expression and enhances M-CSF production by human monocytes, which facilitates differentiation and increases the susceptibility of MDM to HIV-1 infection. IL-2 is used for therapeutic restoration of CD4+ T cells in AIDS patients, but it causes a transient burst of HIV-1 RNA from unidentified cells shortly after administration. We investigated the in vitro ability of IL-2 to enhance HIV-1 expression in macrophages via upregulation of M-CSF production. We found that exposure of MDM to IL-2 prior to infection leads to a dramatic decrease in HIV-1 replication, which correlates with an IL-2-induced down-modulation of the HIV-1 receptor, CD4, and the chemokine co-receptor, CCR5. However, production of M-CSF is not modulated, suggesting that IL-2 may not only be of benefit in restoring immune function in AIDS patients, but may also help prevent infection of healthy macrophages by decreasing the expression of HIV-1 receptors and co-receptors (AIDS 1998). Although M-CSF can modulate the susceptibility and rate of infection of MDM with HIV-1 and its production is enhanced following infection, its role in the infection of MDM with other viruses has not been characterized. We infected MDM with a panel of single stranded RNA viruses including HIV-1, HIV-2, measles virus (MV) and respiratory syncitial virus (RSV). We found that infection of MDM with monocytropic strains of HIV-1 or HIV-2 led to enhanced production of M-CSF. However, infection of MDM with MV or RSV failed to induce production of M-CSF, but did result in production of select pro-inflammatory cytokines and beta chemokines. Treatment of HIV-infected MDM with AZT led to complete inhibition of HIV-1 replication, which prevented enhanced production of M-CSF mRNA and protein and confirmed the need for viral replication. The addition of M-CSF antagonists to cultures of HIV-infected MDM, including monoclonal and polyclonal antibodies to M-CSF and soluble M-CSF receptors, dramatically inhibited HIV-1 replication. Furthermore, production of MIP-1 alpha, a monocyte chemotactic factor secreted by HIV-1-infected MDM, was also significantly reduced when HIV-1 infected MDM were treated with M-CSF antagonists. Taken together, these results suggest that biologic antagonists to M-CSF may be useful therapies for inhibiting HIV-1 replication in MDM by blocking production of HIV-1, reducing chemokine (MIP-1 alpha) recruitment of HIV susceptible T cells and macrophages, and preventing the establishment and maintenance of infected MDM as a reservoir for HIV.