Functional Studies of HIV-Tat Effects on Endothelium

描述（由申请人提供）：最初的建议集中在HIV-1达特与大血管脐静脉和骨髓内皮的相互作用。虽然在实现目标方面取得了进展，但很明显，HIV-1达特的病理生理学是在微血管内皮，特别是淋巴起源的微血管内皮。这是因为艾滋病的原发性内皮细胞改变是卡波西肉瘤（KS）的发生，其细胞起源于淋巴。因此，我们将工作重点转移到富含淋巴源细胞的真皮微血管内皮（DMEC）。另一个重点转移是KSHV/HHV 8。这种γ疱疹病毒似乎是KS的关键病原体。其包膜糖蛋白gB与DMEC表面的α 3 β 1整联蛋白结合。为了开发更接近HIV-1和KSHV/HHV 8共感染体内发病机制的体外系统，我们开始研究达特和gB对DMEC的影响。我们发现，VEGFR 3/FLT 4，在淋巴管内皮细胞中的标志性VEGF受体，与α 3 β 1整合素连接相关，并在缺乏同源VEGF配体的情况下被gB或达特激活。此外，gB或达特通过VEGFR 3引起DMEC迁移和增殖。这些关于α 3 β 1整合素与VEGFR 3相关的数据表明，VEGFR 3可能作为KSHV的辅助受体，或者其信号传导促进KSHV进入。新的具体目标是解决达特和gB可能在改变内皮细胞功能和KSHV感染方面具有协同作用的假设：（1）进一步表征KSHV gB激活α 3 β 1整合素如何激活VEGFR 3;（2）研究VEGFR 3是否参与KSHV进入微血管内皮细胞;（3）HIV- 1达特和KSHV gB功能相关的协同相互作用的特征。这些研究的目的是提供新的信息与艾滋病的共感染的主机，从而提供了一个基础，对KS的预防或治疗策略的设计。

DESCRIPTION (provided by applicant): The initial proposal focused on interactions of HIV-1 tat with large vessel umbilical vein and marrow endothelium. While progress was made in fulfilling the aims, it became clear that the pathophysiology of HIV-1 tat was in microvascular endothelium, particularly that of lymphatic origin. This was because the primary endothelial alteration in AIDS is in the genesis of Kaposi's sarcoma (KS), whose cell of origin is lymphatic. Thus, we shifted the focus of our work to dermal microvascular endothelium (DMEC) that are enriched with cells of lymphatic origin. The other shift in focus was to KSHV/HHV8. This gamma herpes virus appears to be the key etiological agent in KS. Its envelope glycoprotein, gB, binds to the alpha3beta1 integrin on the surface of DMEC. To develop in vitro systems that more closely model in vivo pathogenesis in coinfection with HIV-1 and KSHV/HHV8, we began to study the effects of tat and gB on DMEC. We found that VEGFR3/FLT4, the signature VEGF receptor in lymphatic endothelium, associated with, and was activated upon, alpha3beta1 integrin ligation by gB or tat in the absence of cognate VEGF ligands. Furthermore, gB or tat caused DMEC migration and proliferation via VEGFR3. These data on the association of the alpha3beta1 integrin with VEGFR3 suggested that VEGFR3 may either act as a coreceptor for KSHV or that its signaling facilitates KSHV entry. The new specific aims address the hypothesis that tat and gB may have cooperative effects on altering endothelial cell function and KSHV infection: (1) to further characterize how alpha3beta1 integrin activation by KSHV gB can activate VEGFR3; (2) to investigate whether VEGFR3 is involved in entry of KSHV into microvascular endothelial cells; and (3) to characterize functionally relevant cooperative interactions of HIV- 1 tat and KSHV gB. These studies are designed to provide new information on the coinfected host with AIDS and thereby provide a foundation for the design of preventive or therapeutic strategies against KS.