Browsing by Subject "Inflammasome"

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    ItemOpen Access
    MCC950, a selective NLPR3 inflammasome inhibitor, improves neurologic function and survival after cardiac arrest and resuscitation.
    (Journal of neuroinflammation, 2020-08-31) Jiang, Maorong; Li, Ran; Lyu, Jingjun; Li, Xuan; Wang, Wei; Wang, Zhuoran; Sheng, Huaxin; Zhang, Weiguo; Karhausen, Jörn; Yang, Wei

    Background

    Cardiac arrest (CA) is associated with high morbidity and mortality, even after spontaneous circulation is re-established. This dire situation is partly due to post-CA syndrome for which no specific and effective intervention is available. One key component of post-CA syndrome is sterile inflammation, which affects various organs including the brain. A major effector of sterile inflammation is activated NLRP3 inflammasome, which leads to increased release of interleukin (IL)-1β. However, how NLRP3 inflammasome impacts neuroinflammation and neurologic outcome after CA is largely undefined.

    Methods

    Mice were subjected to a potassium-based murine CA and cardiopulmonary resuscitation (CPR) model. MCC950 was used to suppress activation of NLRP3 inflammasome after CA/CPR. Levels of protein and mRNA were examined by Western blotting and quantitative PCR, respectively. Immunologic changes were assessed by measuring cytokine expression and immune cell compositions. CA outcomes, including neurologic deficits, bacterial load in the lung, and survival rate, were evaluated.

    Results

    Using our CA/CPR model, we found that NLRP3 inflammasome was activated in the post-CA brain, and that pro-inflammatory cytokine levels, including IL-1β, were increased. After treatment with MCC950, a potent and selective NLRP3 inflammasome inhibitor, mice exhibited improved functional recovery and survival rate during the 14-day observational period after CA/CPR. In line with these findings, IL-1β mRNA levels in the post-CA brain were significantly suppressed after MCC950 treatment. Interestingly, we also found that in MCC950- vs. vehicle-treated CA mice, immune homeostasis in the spleen was better preserved and bacterial load in the lung was significantly reduced.

    Conclusions

    Our data demonstrate that activation of NLRP3 inflammasome could be a key event shaping the post-CA immuno- and neuro-pathology, and identify this pathway as a unique and promising therapeutic target to improve outcomes after CA/CPR.
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    The AIM2 Inflammasome Is Activated In Astrocytes During EAE
    (2021) Barclay, William Elliot

    The inflammasomes are a group of pattern recognition receptors (PRRs) with unique characteristics and critical to innate immunity by translating microbial and damage signals into inflammation. While early investigation into inflammasomes focused on their ability to respond to invading pathogens, now inflammasomes are known to collectively respond to a broad range of sterile damage signals. Indeed, several inflammasomes, and most notably the NLRP3 inflammasome, are known to promote pathogenesis of several autoinflammatory conditions, including the autoimmune neuroinflammation which is modeled in the mouse model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). While this association of inflammasomes with EAE is well established, the timing, tissue localization, and cell-specificity of inflammasome activation in the central nervous system (CNS) remains poorly understood during disease. Thus, this dissertation details our investigation into the specific sites and timing of inflammasome activation during EAE, as well as determining which inflammasome is activated in the CNS during disease. The interrogation of inflammasome activation in vivo during disease states required our use of genetically modified mice with fluorescent-protein tagged inflammasome adaptor ASC (ASC-Citrine), which serves as a reporter of active inflammasomes. We identified in situ inflammasome activation in specific CNS cell types of these mice using antibody-based immunofluorescent staining techniques and confocal microscopy, and confirmed the result by genetically modified mice, which allowed cell-specific expression of ASC-Citrine. Further, we used mice genetically deficient in inflammasome components ASC and AIM2 to investigate the involvement of these proteins in disease development. Our study concluded with several insights. Firstly, inflammasome activation occurs in the antigen draining lymph nodes prior to symptom onset during EAE, but inflammasome activation occurs more significantly in the spinal cord at 30 days post induction (dpi) of EAE. Spinal cord inflammasome activation during EAE occurs selectively in radioresistent cells, mainly in astrocytes. Further, this astrocyte inflammasome is dependent on AIM2, and does not result in outcomes, which are canonically observed in myeloid cells, such as release of the inflammatory cytokine, IL-1β. Indeed, AIM2 limits EAE development. Lastly, astrocyte inflammasomes differ morphologically from the traditional structure (known as the “ASC speck”) as seen in macrophages. This dissertation thus expands our understanding of inflammasome activation during EAE, and introduces new areas of investigation into the AIM2 inflammasome during EAE and inflammasome activation in astrocytes.