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Summary The NLRP3 inflammasome is a multiprotein complex that upon activation by the innate immune system drives a broad inflammatory response. The primary initial mediators of this response are pro‐IL‐1β and pro‐IL‐18, both of which are in an inactive form. Formation and activation of the NLRP3 inflammasome activates caspase‐1, which cleaves pro‐IL‐1β and pro‐IL‐18 and triggers the formation of gasdermin D pores. Gasdermin D pores allow for the secretion of active IL‐1β and IL‐18 initiating the organism‐wide inflammatory response. The NLRP3 inflammasome response can be beneficial to the host; however, if the NLRP3 inflammasome is inappropriately activated it can lead to significant pathology. While the primary components of the NLRP3 inflammasome are known, the precise details of assembly and activation are less well defined and conflicting. Here, we discuss several of the proposed pathways of activation of the NLRP3 inflammasome. We examine the role of subcellular localization and the reciprocal regulation of the NLRP3 inflammasome by autophagy. We focus on the roles of mitochondria and mitophagy in activating and regulating the NLRP3 inflammasome. Finally, we detail the impact of pathologic NLRP3 responses in the development and manifestations of pulmonary disease. [ABSTRACT FROM AUTHOR]

Inflammasomes continue to generate interest in an increasing number of disciplines owing to their unique ability to integrate a myriad of signals from pathogen- and damage-associated molecular patterns into a proinflammatory response. This potent caspase-1-dependent process is capable of activating the innate immune system, initiating pyroptosis (an inflammatory form of programmed cell death), and shaping adaptive immunity. The NLRP3 inflammasome is the most thoroughly studied of the inflammasome complexes that have been described thus far, perhaps owing to its disparate assortment of agonists. This review highlights our current understanding of the mechanisms of both priming and activation of the NLRP3 inflammasome. [ABSTRACT FROM AUTHOR]

T-cell immunoglobulin mucin-1 (Tim-1) is a transmembrane protein postulated to be a key regulator of Th2-type immune responses. This hypothesis is based in part upon genetic studies associating Tim-1 polymorphisms in mice with a bias toward airway hyperrespon-siveness (AHR) and the development of Th2-type CD4+ T cells. Tim-1 expressed by Th2 CD4+ T cells has been proposed to function as a co-stimulatory molecule. Tim-1 is also expressed by B cells, macrophages, and dendritic cells, but its role in responses by these cell types has not been firmly established. Here, we generated Tim-1-deficient mice to determine the role of Tim-1 in a murine model of allergic airway disease that depends on the development and function of Th2 effector cells and results in the generation of AHR. We found antigen-driven recruitment of inflammatory cells into airways is increased in Tim-1-deficient mice relative to WT mice. In addition, we observed increased antigen-specific cytokine production by splenocytes from antigen-sensitized Tim-1-deficient mice relative to those from controls. These data support the conclusion that Tim-1 functions in pathways that suppress recruitment of inflammatory cells into the airways and the generation or activity of CD4+ T cells. [ABSTRACT FROM AUTHOR]

Summary: The NLRP3 inflammasome is activated in response to a variety of signals that are indicative of damage to the host including tissue damage, metabolic stress, and infection. Upon activation, the NLRP3 inflammasome serves as a platform for activation of the cysteine protease caspase-1, which leads to the processing and secretion of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18. Dysregulated NLRP3 inflammasome activation is associated with both heritable and acquired inflammatory diseases. Here, we review new insights into the mechanism of NLRP3 inflammasome activation and its role in disease pathogenesis. [ABSTRACT FROM AUTHOR]

Type 2 T helper (TH2) cells are critical for the development of allergic immune responses; however, the molecular mechanism controlling their effector function is still largely unclear. Here, we report that the transcription factor NFIL3/E4BP4 regulates cytokine production and effector function by TH2 cells. NFIL3 is highly expressed in TH2 cells but much less in TH1 cells. Production of interleukin (IL)-13 and IL-5 is significantly increased in Nfil3−/− TH2 cells and is decreased by expression of NFIL3 in wild-type TH2 cells. NFIL3 directly binds to and negatively regulates the Il13 gene. In contrast, IL-4 production is decreased in Nfil3−/− TH2 cells. Increased IL-13 and IL-5 together with decreased IL-4 production by antigen-stimulated splenocytes from the immunized Nfil3−/− mice was also observed. The ability of NFIL3 to alter TH2 cytokine production is a T-cell intrinsic effect. Taken together, these data indicate that NFIL3 is a key regulator of TH2 responses. [ABSTRACT FROM AUTHOR]