Mouse handling and the experimental procedures were approved by the Seoul National University Institutional Animal Care and Use Committees (permit numbers: SNU-150612-4) and were performed in accordance with the approved guidelines

Mouse handling and the experimental procedures were approved by the Seoul National University Institutional Animal Care and Use Committees (permit numbers: SNU-150612-4) and were performed in accordance with the approved guidelines. via p38 MAPK plays a central role in the rapid synthesis of pro-IL-1 in response to MSU crystals, which is an essential step for IL-1 production in human monocytes. Inflammation is an essential part of the immune response, which is aimed at removing harmful stimuli and maintaining host tissue integrity1,2. Innate immune cells play a pivotal role for launching inflammatory responses after Arteether sensing infectious pathogens or tissue injury through a variety of pattern recognition receptors (PPRs)3,4,5. It is now evident that sterile inflammation, which is caused by damage-associated molecular pattern (DAMP) molecules endogenously derived from host tissue injury and necrotic cells, largely contributes to the pathogenesis of numerous acute and chronic inflammatory diseases including gout, atherosclerosis, cancer, and Alzheimers disease1,6. The cellular and molecular mechanisms governing sterile inflammation remain poorly defined; however IL-1 has been suggested as a central mediator of this process1,6,7,8. IL-1 is a potent, multifunctional proinflammatory cytokine, which is primarily produced by monocytes/macrophages and is involved in a variety of immunological functions such as proliferation, activation, and differentiation as well as in the recruitment of additional inflammatory cells. Given that unchecked or prolonged production of IL-1 Rabbit Polyclonal to Caspase 7 (p20, Cleaved-Ala24) is implicated in various inflammatory disorders9,10,11, it is not surprising that its activity is tightly controlled at the transcription, translation, maturation, and secretion levels. Unlike other cytokines, IL-1 is initially produced as a bioinactive precursor (pro-IL-1) during a and requires subsequent intracellular proteolytic cleavage by caspase 1 for maturation. The activation of caspase 1 occurs following the assembly of an inflammasome complex during the and leads to cleavage of pro-IL-1 to mature IL-1, which is then released into the extracellular environment12. Among a variety of DAMPs, sterile particulates Arteether including monosodium urate (MSU) and cholesterol crystals are capable of inducing robust Arteether inflammatory responses. This excessive and unremitting inflammation causes damage to healthy tissue and underlies the pathogenesis of many crystal-based diseases13,14. MSU crystals are the crystallized form of uric acid, which is the end product of purine metabolism. Upon injury cells may leak uric acid, which subsequently functions as a danger signal or DAMP which can act as an adjuvant signal in the immune system8,15. The aberrant deposition of needle-shape MSU crystals in joints or tissues causes gout, the prototypic crystal-induced cause of acute inflammation8,16. An intensively studied mechanism underling crystal-induced inflammation is the activation of the cytosolic NALP3 inflammasome by MSU crystals in monocytes/macrophages. The inflammasome is an essential signaling complex for active IL-1 production17,18,19, and IL-1-driven inflammation might contribute to the development of other comorbidities including hypertension, diabetes mellitus and cardiovascular disease in patients with gout8,20. Although both the priming and activation steps are prerequisite for productive IL-1 generation21, much attention has been paid to understanding how endocytosed sterile particulates initiate the activation of the NLRP3 inflammasome resulting in the production of mature IL-1 in monocytes/macrophages. Thus, a majority of studies have utilized THP-1 cells pre-stimulated with PMA, a sufficient priming stimuli for producing pro-IL-1; however, there is accumulating evidence that the caspase-1/IL-1 activation pathway differs between primary human monocytes and the monocyte-like leukemia cell line, THP-1, and murine macrophages, cells often used to study crystal-mediated sterile inflammation22,23. For example, primary human monocytes are capable of producing and releasing IL-1 with only TLR or cytokine stimulation as the priming step due to constitutive expression of active caspase 1. In contrast, secretion of IL-1 in THP-1 cells and murine macrophages is largely dependent on both the priming and activation steps, requiring bacterial products or Phorbol 12-Myristate 13-Acetate (PMA) stimulation prior to MSU stimulation19. Given that cytokines are central initiators of innate immune responses, the rapid and robust production of proinflammatory cytokines such as TNF- is important for successful innate immunity. In order to mediate rapid and dynamic responses to stimuli and external stress, immune effector cells rely on enhancement of the stability and of translation rate of pre-existing mRNAs as an important regulatory step24. Recently the biosynthesis of Arteether TNF- was shown to be controlled by protein kinases at various post-transcriptional levels24,25,26. Moreover, LPS-induced activation of the.