Research Papers: Immunology:
Protein phosphatase, Mg2+/Mn2+-dependent 1A controls the innate antiviral and antibacterial response of macrophages during HIV-1 and Mycobacterium tuberculosis infection
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Jim Sun1, Kaitlyn Schaaf2, Alexandra Duverger2, Frank Wolschendorf2, Alexander Speer1,3, Frederic Wagner2, Michael Niederweis1 and Olaf Kutsch2
1 Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
2 Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
3 Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, Netherlands
Olaf Kutsch, email:
Jim Sun, email:
Keywords: HIV-1, PPM1A, macrophages, Mycobacterium tuberculosis, persistent infection, Immunology and Microbiology Section, Immune response, Immunity
Received: January 12, 2016 Accepted: March 04, 2016 Published: March 18, 2016
Co-infection with HIV-1 and Mycobacterium tuberculosis (Mtb) is a major public health issue. While some research has described how each pathogen accelerates the course of infection of the other pathogen by compromising the immune system, very little is known about the molecular biology of HIV-1/Mtb co-infection at the host cell level. This is somewhat surprising, as both pathogens are known to replicate and persist in macrophages. We here identify Protein Phosphatase, Mg2+/Mn2+-dependent 1A (PPM1A) as a molecular link between Mtb infection and increased HIV-1 susceptibility of macrophages. We demonstrate that both Mtb and HIV-1 infection induce the expression of PPM1A in primary human monocyte/macrophages and THP-1 cells. Genetic manipulation studies revealed that increased PPMA1 expression rendered THP-1 cells highly susceptible to HIV-1 infection, while depletion of PPM1A rendered them relatively resistant to HIV-1 infection. At the same time, increased PPM1A expression abrogated the ability of THP-1 cells to respond to relevant bacterial stimuli with a proper cytokine/chemokine secretion response, blocked their chemotactic response and impaired their ability to phagocytose bacteria. These data suggest that PPM1A, which had previously been shown to play a role in the antiviral response to Herpes Simplex virus infection, also governs the antibacterial response of macrophages to bacteria, or at least to Mtb infection. PPM1A thus seems to play a central role in the innate immune response of macrophages, implying that host directed therapies targeting PPM1A could be highly beneficial, in particular for HIV/Mtb co-infected patients.
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