Autophagy enhances NFκB activity in specific tissue macrophages by sequestering A20 to boost antifungal immunity.

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2015-01-22

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Abstract

Immune responses must be well restrained in a steady state to avoid excessive inflammation. However, such restraints are quickly removed to exert antimicrobial responses. Here we report a role of autophagy in an early host antifungal response by enhancing NFκB activity through A20 sequestration. Enhancement of NFκB activation is achieved by autophagic depletion of A20, an NFκB inhibitor, in F4/80(hi) macrophages in the spleen, peritoneum and kidney. We show that p62, an autophagic adaptor protein, captures A20 to sequester it in the autophagosome. This allows the macrophages to release chemokines to recruit neutrophils. Indeed, mice lacking autophagy in myeloid cells show higher susceptibility to Candida albicans infection due to impairment in neutrophil recruitment. Thus, at least in the specific aforementioned tissues, autophagy appears to break A20-dependent suppression in F4/80(hi) macrophages, which express abundant A20 and contribute to the initiation of efficient innate immune responses.

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10.1038/ncomms6779

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Kanayama, M, M Inoue, K Danzaki, G Hammer, Y He and ML Shinohara (2015). Autophagy enhances NFκB activity in specific tissue macrophages by sequestering A20 to boost antifungal immunity. Nat Commun, 6. p. 5779. 10.1038/ncomms6779 Retrieved from https://hdl.handle.net/10161/9376.

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Scholars@Duke

He

You-Wen He

Professor of Integrative Immunobiology

We study T cell biology in health and disease. Our current study is divided into two parts. Part I is to investigate T lymphocyte-mediated anti-caner immunity. We have found that host complement inhibits the cytokine IL-10 production in CD8+ tumor infiltrating lymphocytes through complement receptors C3aR and C5aR. Complement-deficient animals are resistant to tumor development in a T cell- and IL-10-dependent manner. CD8+ tumor infiltrating T cells express IL-10 when complement signaling is disabled. We found that tumor infiltrating lymphocytes from human cancers expanded with IL-2 plus IL-10 are potent tumor killers. Complement-mediated inhibition on antitumor immunity is independent of the PD-1/PD-L1 immune checkpoint pathway. Our findings suggest that complement receptors C3aR and C5aR expressed on CD8+ tumor infiltrating lymphocytes represent a novel class of immune checkpoints that needs to be targeted for tumor immunotherapy. Our current effort is to enhance cancer immunotherapy through several strategies. First, we investigate a combined blockade of complement signaling and anti-PD-1 to enhance the antitumor efficacy; second, we are studying the antitumor efficacy of a targeted delivery of IL-10 to antitumor CD8+ T cells by using anti-PD1-IL-10 or anti-CTLA-4-IL-10 fusion proteins; third, we are studying the tumor killing efficacy of addition of IL-10 in the expansion protocol of tumor infiltrating lymphocytes for adaptive cellular therapy.

Part II is to investigate the intracellular process termed autophagy in T lymphocyte function. Autophagy is a highly conserved self-digestion pathway that plays essential roles in maintaining the homeostasis of organelles, degrading long-lived proteins and recycling amino acids under starvation conditions. We have found that autophagy related molecules are expressed in T lymphocytes and autophagy occurs inside T lymphocytes. We have generated autophagy-deficient T lymphocytes in multiple genetic models and investigated the roles of autophagy in T lymphocytes. We found that autophagy plays a critical role in T lymphocyte function. Our current effort is to elucidate the molecular pathways by which TCR signal induces autophagy and the impact of autophagy on intracellular organelle homeostasis in dividing T cells.   

 

 

 

Shinohara

Mari L. Shinohara

Professor of Integrative Immunobiology

Shinohara Lab Website

Immune responses against pathogens are essential for host protection, but excessive and uncontrolled immune reactions can lead to autoimmunity. How does our immune system keep the balance fine-tuned? This is a central question being asked in my laboratory.

The immune system needs to detect pathogens quickly and effectively. This is performed by the innate immune system, which includes cells such as macrophages and dendritic cells (DCs). Pathogens are recognized by pattern recognition receptors (PRRs) and may be cleared in the innate immune system. However, when pathogens cannot be eliminated by innate immunity, the adaptive immune system participates by exploiting the ability of T cells and B cells. The two immune systems work together not only to clear pathogens effectively but also to avoid collateral damages by our own immune responses. 

In my lab, we use mouse models for infectious and autoimmune diseases to understand the cellular and molecular mechanisms of; pathogen recognition by PRRs in macrophages and DCs, initiation of inflammatory responses in the innate immune system, and the impact of innate immune inflammation on the development and regulation of T cell-mediated adaptive immune responses. 

Several projects are ongoing in the lab. They are to study (1) the roles of PRR in EAE (an animal model of multiple sclerosis), (2) the interplay between immune cells and CNS (central nervous system)-resident cells during EAE and fungal infection, (3) protective and pathogenic mechanisms of immune cells in the lung during fungal infection and inflammation, and (4) the roles of a protein termed osteopontin (OPN), as both secreted (sOPN) and intracellular (iOPN) isoforms, in regulation of immune responses . Although we are very active in EAE to study autoimmunity, other mouse models, such as graft-versus-host disease (GvHD) is ongoing. Cell types we study are mainly DCs, macrophagesneutrophils, and T cells


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