Pleural tuberculosis in patients with early HIV infection is associated with increased TNF-alpha expression and necrosis in granulomas.

Although granulomas may be an essential host response against persistent antigens, they are also associated with immunopathology. We investigated whether HIV co-infection affects histopathological appearance and cytokine profiles of pleural granulomas in patients with active pleural tuberculosis (TB). Granulomas were investigated in pleural biopsies from HIV positive and negative TB pleuritis patients. Granulomas were characterised as necrotic or non-necrotic, graded histologically and investigated for the mRNA expression of IL-12, IFN-gamma, TNF-alpha and IL-4 by in situ hybridisation. In all TB patients a mixed Th1/Th2 profile was noted. Necrotic granulomas were more evident in HIV positive patients with a clear association between TNF-alpha and necrosis. This study demonstrates immune dysregulation which may include TNF-alpha-mediated immunopathology at the site of disease in HIV infected pleural TB patients.

Anatomically compartmentalized human immunodeficiency virus replication in HLA-DR+ cells and CD14+ macrophages at the site of pleural tuberculosis coinfection.

This study examined the impact of the host inflammatory microenvironment associated with localized tuberculosis (TB) on human immunodeficiency virus type 1 (HIV-1) replication within lymphocytes and macrophages in vivo. Paired plasma and pleural fluid samples from HIV-1-infected individuals with pleural TB (n=9) were analyzed. Detection of host proteins incorporated into the HIV-1 envelope by immunomagnetic capture analysis provided insight into the phenotype of cells supporting HIV-1 replication. The results indicated that the 4.0-fold greater median HIV-1 load in pleural fluid, compared with median load in plasma (P<.01), was derived in part from viral replication within HLA-DR+ cells, CD26+ lymphocytes, and, importantly, CD14+ macrophages. Greatly increased local concentrations of proinflammatory cytokines and immune activation markers in the pleural space correlated with the virologic findings. In summary, HIV-1 replication was increased at sites of Mycobacterium tuberculosis coinfection within activated cells, including lymphocytes and CD14+ macrophages.

Human immunodeficiency virus type 1 (HIV-1) quasispecies at the sites of Mycobacterium tuberculosis infection contribute to systemic HIV-1 heterogeneity.

We have recently reported an increased heterogeneity in the human immunodeficiency virus type 1 (HIV-1) envelope gene (env) in HIV-1-infected patients with pulmonary tuberculosis (TB) compared to patients with HIV-1 alone. This increase may be a result of dissemination of lung-derived HIV-1 isolates from sites of Mycobacterium tuberculosis infection and/or the systemic activation of the immune system in response to TB. To distinguish between these two mechanisms, blood and pleural fluid samples were obtained from HIV-1-infected patients with active pleural TB in Kampala, Uganda (CD4 cell counts of 34 to 705 cells/microl, HIV-1 plasma loads of 2,400 to 280,000 RNA copies/ml, and HIV-1 pleural loads of 7,600 to 4,500,000 RNA copies/ml). The C2-C3 coding region of HIV-1 env was PCR amplified from lysed peripheral blood mononuclear cells and pleural fluid mononuclear cells and reverse transcriptase-PCR amplified from plasma and pleural fluid HIV-1 virions of eight HIV-1 patients with pleural TB. Phylogenetic and phenetic analyses revealed a compartmentalization of HIV-1 quasispecies between blood and pleural space in four of eight patients, with migration events between the compartments. There was a trend for a greater genetic heterogeneity in the pleural space, which may be the result of an M. tuberculosis-mediated increase in HIV-1 replication and/or selection pressure at the site of infection. Collectively, these findings suggest that HIV-1 quasispecies in the M. tuberculosis-infected pleural space may leak into the systemic circulation and lead to increased systemic HIV-1 heterogeneity during TB.

Increased replication of HIV-1 at sites of Mycobacterium tuberculosis infection: potential mechanisms of viral activation.

Tuberculosis (TB) enhances HIV-1 replication and the progression to AIDS in dually infected patients. We employed pleural TB as a model to understand the interaction of the host with HIV-1 during active TB, at sites of Mycobacterium tuberculosis (MTB) infection. HIV-1 replication was enhanced both in the cellular (pleural compared with blood mononuclear cells) and acellular (pleural fluid compared with plasma) compartments of the pleural space. Several potential mechanisms for expansion of HIV-1 in situ were found, including augmentation in expression of tumor necrosis factor (TNF)-alpha and the HIV-1 noninhibitory beta-chemokine (MCP-1), low presence of HIV-1 inhibitory beta-chemokines (MIP-1 alpha, MIP-1 beta, and RANTES [regulated on activation, normal T expressed and secreted]), and upregulation in expression of the HIV-1 coreceptor, CCR5, by pleural fluid mononuclear cells. Thus, at sites of MTB infection, conditions are propitious both for transcriptional activation of HIV-1 in latently infected mononuclear cells, and facilitation of viral infection of newly recruited cells. These mechanisms may contribute to enhanced viral burden and dissemination during TB infection.

Augmentation of apoptosis and interferon-gamma production at sites of active Mycobacterium tuberculosis infection in human tuberculosis.

Pleural tuberculosis (TB) was employed as a model to study T cell apoptosis at sites of active Mycobacterium tuberculosis (MTB) infection in human immunodeficiency virus (HIV)-coinfected (HIV/TB) patients and patients infected with TB alone. Apoptosis in blood and in pleural fluid mononuclear cells and cytokine immunoreactivities in plasma and in pleural fluid were evaluated. T cells were expanded at the site of MTB infection, irrespective of HIV status. Apoptosis of CD4 and non-CD4 T cells in the pleural space occurred in both HIV/TB and TB. Interferon (IFN)-gamma levels were increased in pleural fluid, compared with plasma. Spontaneous apoptosis correlated with specific loss of MTB-reactive, IFN-gamma-producing pleural T cells. Immunoreactivities of molecules potentially involved in apoptosis, such as tumor necrosis factor-alpha, Fas-ligand, and Fas, were increased in pleural fluid, compared with plasma. These data suggest that continued exposure of immunoreactive cells to MTB at sites of infection may initiate a vicious cycle in which immune activation and loss of antigen-responsive T cells occur concomitantly, thus favoring persistence of MTB infection.