While the advent of combination antiretroviral therapy (ART) has significantly improved survival, tuberculosis (TB) remains the leading cause of death in the HIV-infected population. We used Mycobacterium tuberculosis/simian immunodeficiency virus-coinfected (M. tuberculosis/SIV-coinfected) macaques to model M. tuberculosis/HIV coinfection and study the impact of ART on TB reactivation due to HIV infection. Although ART significantly reduced viral loads and increased CD4 + T cell counts in blood and bronchoalveolar lavage (BAL) samples, it did not reduce the relative risk of SIV-induced TB reactivation in ART-treated macaques in the early phase of treatment. CD4 + T cells were poorly restored specifically in the lung interstitium, despite their significant restoration in the alveolar compartment of the lung as well as in the periphery. IDO1 induction in myeloid cells in the inducible bronchus-associated lymphoid tissue (iBALT) likely contributed to dysregulated T cell homing and impaired lung immunity. Thus, although ART was indispensable for controlling viral replication, restoring CD4 + T cells, and preventing opportunistic infection, it appeared inadequate in reversing the clinical signs of TB reactivation during the relatively short duration of ART administered in this study. This finding warrants the modeling of concurrent treatment of TB and HIV to potentially reduce the risk of reactivation of TB due to HIV to inform treatment strategies in patients with M. tuberculosis/HIV coinfection.

Antigen-specific T cell responses are critical for immune control of M. tuberculosis infection. In response to M. tuberculosis infection, the majority of infected people mount robust CD4 + T cell responses involving Th1 cytokines, such as IFN-γ and TNF-α, which are important for activating macrophages and curtailing M. tuberculosis replication in the lung (6, 7). In addition, IL-17 and Th17 responses have emerged as important for protective immunity against TB (8,9). Animal studies have shown a role for IL-17 in induction of chemokines, recruitment of CD4 + T cells to the site of infection, formation of granulomas, and protection during M. tuberculosis infection and Bacille Calmette-Guérin (BCG) vaccination (10)(11)(12)(13)(14)(15)(16)(17)(18). The role of IL-17 and Th17 responses in human TB is less clear and has been mainly studied by comparing individuals with active TB and healthy controls. Reports from humans vary widely, with studies showing no difference in the levels of IL-17 between the groups (19), while others have seen low levels of IL-17 in patients with TB compared with healthy controls (20,21). Human genetic mutations and polymorphisms in IL-17 have been associated with TB susceptibility (12,22), whereas other studies have shown the association of Th17/IL-17 responses with TB pathogenesis and disease progression (23)(24)(25)(26). Overall, how IL-17, and in particular, M. tuberculosis antigen-specific Th17 cells, function to control M. tuberculosis infection during asymptomatic LTBI in humans remains poorly understood. We have limited knowledge of the onset and maintenance of M. tuberculosis antigen-specific Th1 and Th17 cell responses in the blood and lung compartments during LTBI and of the phenotypes and functions associated with the LTBI state. This is in part because small-animal models do not reproduce key aspects of human LTBI. Moreover, accurately documenting M. tuberculosis exposure, initial infection, and early events following infection in humans is almost impossible. Thus, studies of M. tuberculosis antigen-specific T cells in humans have been largely confined to cross-sectional characterization of peripheral responses in the blood (27)(28)(29)(30)(31). While some studies have examined responses in bronchoalveolar lavage (BAL) (32-34), longitudinal studies in humans comparing M. tuberculosis antigen-specific T cell responses in blood and lung compartments have been lacking. Thus, detailed characterization of the nature and kinetics of M. tuberculosis antigen-specific T cells associated with human-like asymptomatic LTBI is important for identifying correlates of immune control and protection.Nonhuman primate (NHP) macaque models of M. tuberculosis infection recapitulate multiple features of human M. tuberculosis infection, including clinically asymptomatic infection and symptomatic active TB disease (35-42), and are attractive for studying immune parameters associated with control of M. tuberculosis infection in peripheral blood and lung compartments. We have previously established a mode...

The anti-apoptotic function and tumor-associated expression of HSP70 is consistent with HSP70 functioning as a survival factor to promote tumorigenesis. However, its immunomodulatory activities to induce anti tumor immunity predict the suppression of tumor growth. Using the Hsp70.1/3−/− (Hsp70−/−) mouse model, we observed that tumor-derived HSP70 was neither required for cellular transformation nor for in vivo tumor growth. Hsp70−/− murine embryonic fibroblasts (MEFs) were transformed by E1A/Ras and generated tumors in immune deficient hosts as efficiently as WT transformants. Comparison of Bcr-Abl-mediated transformation of WT and Hsp70−/− bone marrow and progression of B cell leukemogenesis in vivo revealed no differences in disease onset or survival rates and Eμ-Myc driven lymphoma in Hsp70−/− mice was phenotypically indistinguishable from WT Eμ-Myc mice. However, Hsp70−/− E1A/Ras MEFs generated significantly larger tumors than their WT counterparts in C57BL/6J immune competent hosts. Concurrent with this was a reduction in intra-tumoral infiltration of innate and adaptive immune cells, including macrophages and CD8+ T cells. Evaluation of several potential mechanisms revealed an HSP70-chemokine-like activity to promote cellular migration. These observations support a role for tumor-derived HSP70 in facilitating anti-tumor immunity to limit tumor growth and highlight the potential consequences of anti-HSP70 therapy as an efficacious anti-cancer strategy.

Antigen-specific CD4 and CD8 T cells are important components of the immune response to , yet little information is currently known regarding how the breadth, specificity, phenotype, and function of-specific T cells correlate with infection outcome in humans. To facilitate evaluation of human-specific T cell responses targeting multiple different Ags, we sought to develop a high throughput and reproducible T cell response spectrum assay requiring low blood sample volumes. We describe here the optimization and standardization of a microtiter plate-based, diluted whole blood stimulation assay utilizing overlapping peptide pools corresponding to a functionally diverse panel of 60 Ags. Using IFN-γ production as a readout of Ag specificity, the assay can be conducted using 50 μl of blood per test condition and can be expanded to accommodate additional Ags. We evaluated the intra- and interassay variability, and implemented testing of the assay in diverse cohorts of-unexposed healthy adults, foreign-born adults with latent infection residing in the United States, and tuberculosis household contacts with latent infection in a tuberculosis-endemic setting in Kenya. The -specific T cell response spectrum assay further enhances the immunological toolkit available for evaluating-specific T cell responses across different states of infection, and can be readily implemented in resource-limited settings. Moreover, application of the assay to longitudinal cohorts will facilitate evaluation of treatment- or vaccine-induced changes in the breadth and specificity of Ag-specific T cell responses, as well as identification of-specific T cell responses associated with infection outcomes.

Dendritic cells (DCs) play a key role in the generation of CD4 T cell responses to pathogens. Mycobacterium tuberculosis (Mtb) harbors immune evasion mechanisms that impair DC responses and prevent optimal CD4 T cell immunity. The vaccine strain Mycobacterium bovis Bacille Calmette-Guérin (BCG) shares many of the immune evasion proteins utilized by Mtb, but the role of these proteins in DC and T cell responses elicited by BCG is poorly understood. We previously reported that the Mtb serine protease, Hip1, promotes sub-optimal DC responses during infection. Here, we tested the hypothesis that BCG Hip1 modulates DC functions and prevents optimal antigen-specific CD4 T cell responses that limit the immunogenicity of BCG. We generated a strain of BCG lacking hip1 (BCGΔhip1) and show that it has superior capacity to induce DC maturation and cytokine production compared with the parental BCG. Furthermore, BCGΔhip1-infected DCs were more effective at driving the production of IFN-γ and IL-17 from antigen-specific CD4 T cells in vitro. Mucosal transfer of BCGΔhip1-infected DCs into mouse lungs induced robust CD4 T cell activation in vivo and generated antigen-specific polyfunctional CD4 T cell responses in the lungs. Importantly, BCGΔhip1-infected DCs enhanced control of pulmonary bacterial burden following Mtb aerosol challenge compared with the transfer of BCG-infected DCs. These results reveal that BCG employs Hip1 to impair DC activation, leading to attenuated lung CD4 T cell responses with limited capacity to control Mtb burden after challenge.