DEFENSE MECHANISMS OF LUNG CELLS AGAINST MYCOBACTERIUM TUBERCULOSIS

点击翻译按钮获取中文摘要

This renewal application focuses on the dissection of the defense mechanisms of the normal lung against typical Mycobacterium tuberculosis (MTB) and on the understanding how these mechanisms may be impaired in HIV infection. We will carry insights from our previous work on peripheral blood derived macrophages (PBM) and Mycobacterium avium to new experiments using primary bronchoalveolar lavage (BAL) cells and MTB. These experiments will compare functions of normal BAL cells to BAL cells infected with HIV-1 in vitro and with BAL cells derived from HIV-infected individuals. We intend to characterize the normal defense mechanisms of these cells against MTB, then to learn if specific defects arise in the setting of HIV in vitro and in vivo. Our preliminary data, and recent work by others, suggests that the cytokines IL-2, IL-7, IL-1O, IL-12, IL-13, TNF-alpha, IFN-gamma and the plasminogen activator inhibitor type 2 (PAI-2) participate in the modulation of the functions of macrophages and lymphocytes in the context of a mycobacterial infection. We will examine the induction of these cytokines in BAL cells following MTB challenge and the response of BAL cells to activating cytokines in assays of MTB killing. We will also examine the actions of PAI-2 (which we have previously shown to rescue PBM infected with Mycobacterium avium from death) in experiments with alveolar macrophages (AM) infected with HIV-1 or AM from HIV+ patients. These studies are designed to clarify the validity of our hypothesis that the impaired pulmonary defense function of HIV-infected individuals against MTB is due to one or more of the following defects: 1. T cell dysfunction resulting in impairment of cytokine production, e.g. failure to produce IL-2, IL-7 and IFN-gamma or hyperproduction of IL-10 or IL-13, 2. failure of the AM to be effectively activated in mycobacterial infection, e.g. due to dysfunctional cytokine effects or direct effects of HIV, and 3. incapacity of AM to survive mycobacterial infection possibly due to dysfunction of the protective function of PAI-2. Our goal is to identify candidates for immunotherapy to supplement available anti- tuberculous chemotherapy which may be of limited benefit in AIDS patients. To this end we will also examine whether the antimycobacterial response can be augmented by addition of lipoarabinomannans from nonvirulent MTB and we will explore therapeutic strategies employing mycobacteriophages for targeted molecular therapy and for direct lysis of MTB.