Browsing by Subject "Inflammasome"

Now showing 1 - 8 of 8
  • Thumbnail Image
    Item
    Caspase-1 causes truncation and aggregation of the Parkinson's disease-associated protein α-synuclein
    (National Academy of Sciences, 2016-08-23) Wang, Wei; Nguyen, Linh T. T.; Burlak, Christopher; Chegini, Fariba; Guo, Feng; Chataway, Tim; Ju, Shulin; Fisher, Oriana S.; Miller, David W.; Datta, Debajyoti; Wu, Fang; Wu, Chun-Xiang; Landeru, Anuradha; Wells, James A.; Cookson, Mark R.; Boxer, Matthew B.; Thomas, Craig J.; Gai, Wei Ping; Ringe, Dagmar; Petsko, Gregory A.; Hoang, Quyen Q.; Department of Biochemistry & Molecular Biology, IU School of Medicine
    The aggregation of α-synuclein (aSyn) leading to the formation of Lewy bodies is the defining pathological hallmark of Parkinson's disease (PD). Rare familial PD-associated mutations in aSyn render it aggregation-prone; however, PD patients carrying wild type (WT) aSyn also have aggregated aSyn in Lewy bodies. The mechanisms by which WT aSyn aggregates are unclear. Here, we report that inflammation can play a role in causing the aggregation of WT aSyn. We show that activation of the inflammasome with known stimuli results in the aggregation of aSyn in a neuronal cell model of PD. The insoluble aggregates are enriched with truncated aSyn as found in Lewy bodies of the PD brain. Inhibition of the inflammasome enzyme caspase-1 by chemical inhibition or genetic knockdown with shRNA abated aSyn truncation. In vitro characterization confirmed that caspase-1 directly cleaves aSyn, generating a highly aggregation-prone species. The truncation-induced aggregation of aSyn is toxic to neuronal culture, and inhibition of caspase-1 by shRNA or a specific chemical inhibitor improved the survival of a neuronal PD cell model. This study provides a molecular link for the role of inflammation in aSyn aggregation, and perhaps in the pathogenesis of sporadic PD as well.
  • Thumbnail Image
    Item
    Characterization of age-associated inflammasome activation reveals tissue specific differences in transcriptional and post-translational inflammatory responses
    (Springer Nature, 2024-09-10) Talley, Sarah; Nguyen, Tyler; Van Ye, Lily; Valiauga, Rasa; DeCarlo, Jake; Mustafa, Jabra; Cook, Benjamin; White, Fletcher A.; Campbell, Edward M.; Anesthesia, School of Medicine
    Aging is associated with systemic chronic, low-grade inflammation, termed 'inflammaging'. This pattern of inflammation is multifactorial and is driven by numerous inflammatory pathways, including the inflammasome. However, most studies to date have examined changes in the transcriptomes that are associated with aging and inflammaging, despite the fact that inflammasome activation is driven by a series of post-translational activation steps, culminating in the cleavage and activation of caspase-1. Here, we utilized transgenic mice expressing a caspase-1 biosensor to examine age-associated inflammasome activation in various organs and tissues to define these post-translational manifestations of inflammaging. Consistent with other studies, we observe increased inflammation, including inflammasome activation, in aged mice and specific tissues. However, we note that the degree of inflammasome activation is not uniformly associated with transcriptional changes commonly used as a surrogate for inflammasome activation in tissues. Furthermore, we used a skull thinning technique to monitor central nervous system inflammasome activation in vivo in aged mice and found that neuroinflammation is significantly amplified in aged mice in response to endotoxin challenge. Together, these data reveal that inflammaging is associated with both transcriptional and post-translational inflammatory pathways that are not uniform between tissues and establish new methodologies for measuring age-associated inflammasome activation in vivo and ex vivo.
  • Thumbnail Image
    Item
    Determining distinct roles of IL-1α through generation of an IL-1α knockout mouse with no defect in IL-1β expression
    (Frontiers Media, 2022-11-24) Malireddi, R.K. Subbarao; Bynigeri, Ratnakar R.; Kancharana, Balabhaskararao; Sharma, Bhesh Raj; Burton, Amanda R.; Pelletier, Stephane; Kanneganti, Thirumala-Devi; Medical and Molecular Genetics, School of Medicine
    Interleukin 1α (IL-1α) and IL-1β are the founding members of the IL-1 cytokine family, and these innate immune inflammatory mediators are critically important in health and disease. Early studies on these molecules suggested that their expression was interdependent, with an initial genetic model of IL-1α depletion, the IL-1α KO mouse (Il1a-KOline1), showing reduced IL-1β expression. However, studies using this line in models of infection and inflammation resulted in contrasting observations. To overcome the limitations of this genetic model, we have generated and characterized a new line of IL-1α KO mice (Il1a-KOline2) using CRISPR-Cas9 technology. In contrast to cells from Il1a-KOline1, where IL-1β expression was drastically reduced, bone marrow-derived macrophages (BMDMs) from Il1a-KOline2 mice showed normal induction and activation of IL-1β. Additionally, Il1a-KOline2 BMDMs showed normal inflammasome activation and IL-1β expression in response to multiple innate immune triggers, including both pathogen-associated molecular patterns and pathogens. Moreover, using Il1a-KOline2 cells, we confirmed that IL-1α, independent of IL-1β, is critical for the expression of the neutrophil chemoattractant KC/CXCL1. Overall, we report the generation of a new line of IL-1α KO mice and confirm functions for IL-1α independent of IL-1β. Future studies on the unique functions of IL-1α and IL-1β using these mice will be critical to identify new roles for these molecules in health and disease and develop therapeutic strategies.
  • Thumbnail Image
    Item
    Editorial: A new frontier in translational research on autoinflammatory diseases - various aspects of innate immunity on human diseases
    (Frontiers Media, 2023-01-31) Mukai, Tomoyuki; Ida, Hiroaki; Ueki, Yasuyoshi; Nishikomori, Ryuta; Biomedical Sciences and Comprehensive Care, School of Dentistry
  • Thumbnail Image
    Item
    Hematopoietic IKBKE limits the chronicity of inflammasome priming and metaflammation
    (PNAS, 2015-01-13) Patel, Meghana N.; Bernard, William G.; Milev, Nikolay B.; Cawthorn, William P.; Figg, Nichola; Hart, Dan; Prieur, Xavier; Virtue, Sam; Hegyi, Krisztina; Bonnafous, Stephanie; Bailly-Maitre, Beatrice; Chu, Yajing; Griffin, Julian L.; Mallat, Ziad; Considine, Robert V.; Tran, Albert; Gual, Philippe; Takeuchi, Osamu; Akira, Shizuo; Vidal-Puig, Antonio; Bennett, Martin R.; Sethi, Jaswinder K.; Department of Medicine, IU School of Medicine
    Obesity increases the risk of developing life-threatening metabolic diseases including cardiovascular disease, fatty liver disease, diabetes, and cancer. Efforts to curb the global obesity epidemic and its impact have proven unsuccessful in part by a limited understanding of these chronic progressive diseases. It is clear that low-grade chronic inflammation, or metaflammation, underlies the pathogenesis of obesity-associated type 2 diabetes and atherosclerosis. However, the mechanisms that maintain chronicity and prevent inflammatory resolution are poorly understood. Here, we show that inhibitor of κB kinase epsilon (IKBKE) is a novel regulator that limits chronic inflammation during metabolic disease and atherosclerosis. The pathogenic relevance of IKBKE was indicated by the colocalization with macrophages in human and murine tissues and in atherosclerotic plaques. Genetic ablation of IKBKE resulted in enhanced and prolonged priming of the NLRP3 inflammasome in cultured macrophages, in hypertrophic adipose tissue, and in livers of hypercholesterolemic mice. This altered profile associated with enhanced acute phase response, deregulated cholesterol metabolism, and steatoheptatitis. Restoring IKBKE only in hematopoietic cells was sufficient to reverse elevated inflammasome priming and these metabolic features. In advanced atherosclerotic plaques, loss of IKBKE and hematopoietic cell restoration altered plaque composition. These studies reveal a new role for hematopoietic IKBKE: to limit inflammasome priming and metaflammation.
  • Thumbnail Image
    Item
    Leukotriene B4 licenses inflammasome activation to enhance skin host defense
    (National Academy of Science, 2020-12-01) Guerta Salina, Ana Carolina; Brandt, Stephanie L.; Klopfenstein, Nathan; Blackman, Amondrea; Ribeiro Bazzano, Júlia Miranda; Sá-Nunes, Anderson; Byers-Glosson, Nicole; Brodskyn, Claudia; Machado Tavares, Natalia; Santos Da Silva, Icaro Bonyek; Medeiros, Alexandra I.; Serezani, C. Henrique; Microbiology and Immunology, School of Medicine
    The initial production of inflammatory mediators dictates host defense as well as tissue injury. Inflammasome activation is a constituent of the inflammatory response by recognizing pathogen and host-derived products and eliciting the production of IL-1β and IL-18 in addition to inducing a type of inflammatory cell death termed "pyroptosis." Leukotriene B4 (LTB4) is a lipid mediator produced quickly (seconds to minutes) by phagocytes and induces chemotaxis, increases cytokine/chemokine production, and enhances antimicrobial effector functions. Whether LTB4 directly activates the inflammasome remains to be determined. Our data show that endogenously produced LTB4 is required for the expression of pro-IL-1β and enhances inflammasome assembly in vivo and in vitro. Furthermore, LTB4-mediated Bruton's tyrosine kinase (BTK) activation is required for inflammasome assembly in vivo as well for IL-1β-enhanced skin host defense. Together, these data unveil a new role for LTB4 in enhancing the expression and assembly of inflammasome components and suggest that while blocking LTB4 actions could be a promising therapeutic strategy to prevent inflammasome-mediated diseases, exogenous LTB4 can be used as an adjuvant to boost inflammasome-dependent host defense.
  • Thumbnail Image
    Item
    Lysosomal disruption by orthopedic wear particles induces activation of the NLRP3 inflammasome and macrophage cell death by distinct mechanisms
    (Wiley, 2021) Fort, Brian P.; Dubyak, George R.; Greenfield, Edward M.; Orthopaedic Surgery, School of Medicine
    Wear particles from orthopedic implants cause aseptic loosening, the leading cause of implant revisions. The particles are phagocytosed by macrophages leading to activation of the nod-like receptor protein 3 (NLRP3) inflammasome and release of interleukin-1β (IL-1β) which then contributes to osteoclast differentiation and implant loosening. The mechanism of inflammasome activation by orthopedic particles is undetermined but other particles cause the cytosolic accumulation of the lysosomal cathepsin-family proteases which can activate the NLRP3 inflammasome. Here, we demonstrate that lysosome membrane disruption causes cathepsin release into the cytoplasm that drives both inflammasome activation and cell death but that these processes occur independently. Using wild-type and genetically-manipulated immortalized murine bone marrow derived macrophages and pharmacologic inhibitors, we found that NLRP3 and gasdermin D are required for particle-induced IL-1β release but not for particle-induced cell death. In contrast, phagocytosis and lysosomal cathepsin release are critical for both IL-1β release and cell death. Collectively, our findings identify the pan-cathepsin inhibitor Ca-074Me and the NLRP3 inflammasome inhibitor MCC950 as therapeutic interventions worth exploring in aseptic loosening of orthopedic implants. We also found that particle-induced activation of the NLRP3 inflammasome in pre-primed macrophages and cell death are not dependent on pathogen-associated molecular patterns adherent to the wear particles despite such pathogen-associated molecular patterns being critical for all other previously studied wear particle responses, including priming of the NLRP3 inflammasome.
  • Thumbnail Image
    Item
    NRF2 transcriptionally regulates Caspase-11 expression to activate HMGB1 release by Autophagy-deficient hepatocytes
    (Springer Nature, 2023-07-28) Khambu, Bilon; Cai, Genxiang; Liu, Gang; Bailey, Niani Tiaye; Mercer, Arissa A.; Baral, Kamal; Ma, Michelle; Chen, Xiaoyun; Li, Yu; Yin, Xiao-Ming; Pathology and Laboratory Medicine, School of Medicine
    Injury or stress can induce intracellular translocation and release of nuclear HMGB1, a DAMP molecule known to participate in inflammation and other pathological processes. Active release of HMGB1 from stimulated macrophages can be mediated by inflammasomes, which cleave Gasdermin D to form pores on cytoplasmic membranes. We previously had shown that active release of HMGB1 from autophagy deficient hepatocytes also depended on the inflammasome but how the inflammasome was activated was not known. Here we report that persistent activation of transcription factor NRF2 under the autophagy deficient condition led to transcriptional upregulation of Caspase-11 expression, which could then activate the CASPASE-1inflammasome. Using chromatin immunoprecipitation (CHIP) and luciferase-based reporter assays, we show that NRF2 directly binds to the Caspase-11 promoter and transcriptionally increase the expression of Caspase-11. Genetic deletion of Caspase-11 in autophagy-deficient livers represses the release of HMGB1 and its pathological consequence, ductular cell proliferation. Consistently, deletion of NLRP3, which can activate CASPASE-1 mediated inflammasomes under other types of signals, did not prevent HMGB1 release and ductular cell proliferation in autophagy deficient livers. Surprisingly, while cleavage of GASDEMIN D occurred in autophagy-deficient livers its deletion did not prevent the HMGB1 release, suggesting that CASPASE-11-mediated inflammasome activation may also engage in a different mechanism for HMGB1 release by the autophagy deficient hepatocytes. Collectively, this work reveals the novel role of NRF2 in transcriptional upregulation of Caspase-11 and in inflammasome activation to promote active release of HMGB via a non-Gasdermin D mediated avenue.