Defective expansion and function of memory like natural killer cells in HIV+ individuals with latent tuberculosis infection.

PURPOSE: Tuberculosis (TB) is the leading cause of infectious disease related mortality, and only 10% of the infected individuals develop active disease. The likelihood of progression of latent tuberculosis infection (LTBI) to active TB disease is high in HIV infected individuals. Identification of HIV+ individuals at risk would allow treating targeted population, facilitating completion of therapy for LTBI and prevention of TB development. NK cells have an important role in T cell independent immunity against TB, but the exact role of NK cell subsets in LTBI and HIV is not well characterized. METHODS: In this study, we compared the expansion and function of memory like NK cells from HIV-LTBI+ individuals and treatment naïve HIV+LTBI+ patients in response to Mtb antigens ESAT-6 and CFP-10. RESULTS: In freshly isolated PBMCs, percentages of CD3-CD56+ NK cells were similar in HIV+LTBI+ patients and healthy HIV-LTBI+ individuals. However, percentages of CD3-CD56+CD16+ NK cells were higher in healthy HIV-LTBI+ individuals compared to HIV+LTBI+ patients. HIV infection also inhibited the expansion of memory like NK cells, production of IL-32α, IL-15 and IFN-γ in response to Mtb antigens in LTBI+ individuals. CONCLUSION: We studied phenotypic, functional subsets and activation of memory like-NK cells during HIV infection and LTBI. We observed that HIV+LTBI+ patients demonstrated suboptimal NK cell and monocyte interactions in response to Mtb, leading to reduced IL-15, IFN-γ and granzyme B and increased CCL5 production. Our study highlights the effect of HIV and LTBI on modulation of NK cell activity to understand their role in development of interventions to prevent progression to TB in high risk individuals.

Transforming Growth Factor-ß Suppresses Interleukin (IL)-2 and IL-1ß Production in HIV-Tuberculosis Co-Infection.

Interleukin (IL)-1ß and IL-2 play important roles in protective immune responses against Mycobacterium tuberculosis (Mtb) infection. Information on the factors that regulate the production of these cytokines in the context of human immunodeficiency virus and latent tuberculosis infection (LTBI) or active tuberculosis (TB) disease is limited. In this study, we compared the production of these cytokines by peripheral blood mononuclear cells (PBMCs) from HIV- and HIV+ individuals with latent and active Tuberculosis infection in response to Mtb Antigen 85A. PBMCs from HIV+ LTBI+ and HIV+ active TB patients produced low IL-1ß, IL-2 but high transforming growth factor beta (TGF-ß) compared to healthy controls. CD4+ T cells from HIV patients expressed low retinoic acid-related orphan receptor gamma (RORγ), and high suppressors of cytokine signaling-3 (SOCS-3). Active TB infection in HIV+ individuals further inhibited antigen-specific IL-1ß and IL-2 production compared with those with LTBI. Neutralization of TGF-ß restored IL-1ß and IL-2 levels and lowered SOCS-3 production by CD4+ T cells. We hypothesize that high TGF-ß in HIV patients could be a reason for defective Mtb-specific IL-1ß, IL-2 production and activation of latent TB in HIV. Coupling anti-TGF-ß antibodies with antiretroviral therapy treatment might increase T cell function to boost the immune system for effective clearance of Mtb.

IL-17 and IL-22 production in HIV+ individuals with latent and active tuberculosis.

BACKGROUND: IL-17 and IL-22 cytokines play an important role in protective immune responses against Mycobacterium tuberculosis (Mtb) infection. Information on the production of these cytokines and the factors that regulate their production in the context of human immunodeficiency virus (HIV) and latent tuberculosis infection (LTBI) or active tuberculosis disease (ATB) is limited. In the current study, we compared the production of these two cytokines by PBMC of HIV-LTBI+ and HIV + LTBI+ individuals in response to Mtb antigens CFP-10 (culture filtrate protein) and ESAT-6 (Early Secretory Antigenic Target). We also determined the mechanisms involved in their production. METHODS: We cultured Peripheral Blood Mononuclear Cells (PBMCs) from HIV- individuals and HIV+ patients with latent tuberculosis and active disease with CFP-10 and ESAT-6. Production of IL-17, IL-22 and PD1 (Programmed Death 1), ICOS (Inducible T-cell Costimulator), IL-23R and FoxP3 (Forkhead box P3) expression on CD4+ T cells was measured. RESULTS: In response to Mtb antigens CFP-10 and ESAT-6, freshly isolated PBMCs from HIV+ LTBI+ and HIV+ active TB patients produced less IL-17 and IL-22 and more IL-10, expressed less IL-23R, and more PD1 and expanded to more FoxP3+ cells. Active TB infection in HIV+ individuals further inhibited antigen specific IL-17 and IL-22 production compared to those with LTBI. Neutralization of PD1 restored IL-23R expression, IL-17 and IL-22 levels and lowered IL-10 production and reduced expansion of FoxP3 T cells. CONCLUSIONS: In the current study we found that increased PD1 expression in HIV + LTBI+ and HIV+ active TB patients inhibits IL-17, IL-22 production and IL-23R expression in response to Mtb antigens CFP-10 and ESAT-6.

Defective MyD88 and IRAK4 but not TLR-2 expression in HIV+ individuals with latent tuberculosis infection.

HIV infection markedly increases the likelihood of latent tuberculosis infection progressing to active TB. Information on expression of TLR-2, myeloid differentiation factor (MyD88), IL-1R- associated kinase-4 (IRAK4) and nuclear factor kappa B (NF-kB) in HIV+LTBI+ and HIV+ patients with active TB disease is limited. We found significantly higher percentages of CD14+TLR2+ cells in PBMCs of HIV+LTBI+ patients compared to HIV-LTBI+ individuals. γ-irradiated Mtb was unable to induce MyD88, IRAK4 expression and IL-1ß, MCP-1, IP-10 production in HIV+LTBI+ patients. Pleural fluids from HIV+TB+ patients had low IL-1ß, MCP-1, IP-10 and high IL-10, TNF-α production. γ-irradiated Mtb stimulated CD14+ cells from HIV+TB+ patients had low IL-1ß, MCP-1, IP-10 production and MyD88, IRAK4 and similar NF-kB expression compared to those from of HIV-TB+ patients. Our results suggest defective MyD88, IRAK4 but not NF-kB inhibit IL-1ß, MCP-1 and IP-10 production by CD14+ cells of HIV+ individuals with LTBI and active TB disease in peripheral blood and at the site of disease.