Inflammatory injury of the intestine is often accompanied by symptoms such as damage to intestinal mucosa, increased intestinal permeability, and intestinal motility dysfunction. Inflammatory factors spread throughout the body via blood circulation, and can cause multi-organ failure. Pyroptosis is a newly discovered way of programmed cell death, which is mainly characterized by the formation of plasma membrane vesicles, cell swelling until the rupture of the cell membrane, and the release of cell contents, thereby activating a drastic inflammatory response and expanding the inflammatory response cascade. Pyroptosis is widely involved in the occurrence of diseases, and the underlying mechanisms for inflammation are still a hot spot of current research. The caspase-1 mediated canonical inflammasome pathway of pyroptosis and caspase-4/5/8/11-mediated non-canonical inflammasome pathway are closely related to the occurrence and development of intestinal inflammation. Therefore, investigation of the signaling pathways and molecular mechanisms of pyroptosis in intestinal injury in sepsis, inflammatory bowel diseases, infectious enteristic, and intestinal tumor is of great significance for the prevention and treatment of intestinal inflammatory injury.
Humans ; Pyroptosis ; Inflammasomes/metabolism* ; Apoptosis ; Caspase 1 ; Inflammation

High mobility group box 1 (HMGB1) is an evolutionarily conserved non-histone chromatin-binding protein. During infection or injury, activated immune cells and damaged cells release HMGB1 into the extracellular space, where HMGB1 functions as a proinflammatory mediator and contributes importantly to the pathogenesis of inflammatory diseases. Recent studies reveal that inflammasomes, intracellular protein complexes, critically regulate HMGB1 release from activated immune cells in response to a variety of exogenous and endogenous danger signals. Double stranded RNA dependent kinase (PKR), an intracellular danger-sensing molecule, physically interacts with inflammasome components and is important for inflammasome activation and HMGB1 release. Together, these studies not only unravel novel mechanisms of HMGB1 release during inflammation, but also provide potential therapeutic targets to treat HMGB1-related inflammatory diseases.
HMGB1 Protein ; chemistry ; metabolism ; Humans ; Inflammasomes ; metabolism ; Macrophages ; immunology ; metabolism ; eIF-2 Kinase ; metabolism

Pyroptosis ; Ketoglutaric Acids ; Gasdermins ; Intracellular Signaling Peptides and Proteins/metabolism* ; Caspases/metabolism* ; Inflammasomes/metabolism*

The inflammasome is a group of multiprotein complexes in the cytoplasm, which can activate caspase-1 that mediates the maturation and release of IL-1β, IL-18, IL-33 and other pro-inflammatory cytokines.NALP1 (NACHT leucine-rich-repeat protein 1), also known as NLRP1, is the first one of the identified complex inflammasomes with definite ligands mainly involved in the activation of inflammasome assembly and the formation of apoptotic bodies. Moreover, it was also found that NLRP1 plays an important biological role in the development of acute leukemia, the bone marrow hematopoietic stem cell apoptosis and other blood diseases. This review briefly summarizes the structure, activation mechanism, regulation and the role of NLRP1 in the hematopoietic system.
Adaptor Proteins, Signal Transducing ; metabolism ; Apoptosis ; Apoptosis Regulatory Proteins ; metabolism ; Cytokines ; Hematologic Diseases ; metabolism ; pathology ; Humans ; Inflammasomes ; Multiprotein Complexes

Inflammatory bowel disease (IBD), the most important entities being ulcerative colitis and Crohn's disease, are chronic, relapsing and remitting inflammatory conditions that result from chronic dysregulation of the mucosal immune system in the intestinal tract. Although the precise pathogenesis of IBD is still incompletely understood, increased levels of proinflammatory cytokines, including interleukin (IL)-1beta, IL-18 and tumor necrosis factor-alpha, are detected in active IBD and correlate with the severity of inflammation, indicating that these cytokines may play a key role in the development of IBD. Recently, the intracellular nucleotide-binding oligomerization domain-like receptor (NLR) family members, including NLRP1, NLRP3, NLRC4 and NLRP6, are emerging as important regulators of intestinal homeostasis. Together, one of those aforementioned molecules or the DNA sensor absent in melanoma 2 (AIM2), apoptosis-associated speck-like protein containing 'a caspase recruitment domain (CARD)' (ASC) and caspase-1 form a large (>700 kDa) multi-protein complex called the inflammasome. Stimulation with specific microbial and endogenous molecules triggers inflammasome assembly and caspase-1 activation. Activated caspase-1 leads to the secretion of proinflammatory cytokines, including IL-1beta and IL-18, and the promotion of pyroptosis, a form of phagocyte cell death induced by bacterial pathogens, in an inflamed tissue. Therefore, inflammasomes are assumed to mediate host defense against microbial pathogens and gut homeostasis, so that their dysregulation might contribute to IBD pathogenesis. This review focuses on recent advances of the role of NLRP3 inflammasome signaling in IBD pathogenesis. Improving knowledge of the inflammasome could provide insights into potential therapeutic targets for patients with IBD.
CARD Signaling Adaptor Proteins/metabolism ; Carrier Proteins/metabolism/physiology ; Caspase 1/metabolism ; Humans ; Inflammasomes/*metabolism ; Inflammatory Bowel Diseases/metabolism/*pathology ; Interleukin-18/metabolism ; Interleukin-1beta/metabolism ; Signal Transduction

Ulcerative colitis (UC) is a chronic, non-specific intestinal disease that not only affects the quality of life of patients and their families but also increases the risk of colorectal cancer. The nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome is an important component of inflammatory response system, and its activation induces an inflammatory cascade response that is involved in the development and progression of UC by releasing inflammatory cytokines, damaging intestinal epithelial cells, and disrupting the intestinal mucosal barrier. Chinese medicine (CM) plays a vital role in the prevention and treatment of UC and is able to regulate NLRP3 inflammasome. Many experimental studies on the regulation of NLRP3 inflammasome mediated by CM have been carried out, demonstrating that CM formulae with main effects of clearing heat, detoxifying toxicity, drying dampness, and activating blood circulation. Flavonoids and phenylpropanoids can effectively regulate NLRP3 inflammasome. Other active components of CM can interfere with the process of NLRP3 inflammasome assembly and activation, leading to a reduction in inflammation and UC symptoms. However, the reports are relatively scattered and lack systematic reviews. This paper reviews the latest findings regarding the NLRP3 inflammasome activation-related pathways associated with UC and the potential of CM in treating UC through modulation of NLRP3 inflammasome. The purpose of this review is to explore the possible pathological mechanisms of UC and suggest new directions for development of therapeutic tools.
Humans ; Inflammasomes/metabolism* ; Colitis, Ulcerative/pathology* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Medicine, Chinese Traditional ; Quality of Life ; Colitis

Chronic inflammatory reaction has been established as an important sign of the occurrence and development of diabetes mellitus (DM), accompanied by the production of a large number of inflammatory factors, thus aggravating the disease progression. As an important non-invasive intervention measure to inhibit inflammation, exercise plays a very important role in the amelioration of DM. NOD-like receptor protein 3 (NLRP3) inflammasome, a regulatory factor of inflammatory response, can induce a variety of inflammatory cascades and cell death, which are closely related to glucose uptake and dyslipidemia regulation. The development of DM can be postponed with exercise. Previous studies have reported the effects of NLRP3 inflammasome on DM, but the crucial role of exercise in this process remains unclear. Therefore, this paper reviews the research progress on the improving effects of exercise intervention on the symptoms of DM by mediating NLRP3 inflammasome, providing a novel theoretical foundation for understanding the prevention and treatment of DM through exercise.
Humans ; Inflammasomes/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; NLR Proteins ; Diabetes Mellitus ; Inflammation ; Exercise Therapy

This study aims to explore the effect of "Trichosanthis Fructus-Allii Macrostemonis" combination(GX) on the activation of NOD-, LRR-, and pyrin domain-containing protein 3(NLRP3) inflammasome, the release of inflammatory cytokines, and the level of autophagy in RAW264.7 macrophage damaged by lipopolysaccharide(LPS), and the mechanism of GX against inflammatory response in macrophages. To be specific, LPS was used to induce the injury of RAW264.7 cells. Cell Counting Kit-8(CCK-8) assay was employed to measure the survival rate of cells, and Western blot to detect the protein expression of NLRP3, apoptosis-associated speck-like protein(ASC), cysteine-aspartic acid protease(caspase)-1, interleukin(IL)-18, IL-1β, microtubule-associated protein light chain 3(LC3)-Ⅱ, and selective autophagy junction protein p62/sequestosome 1 in RAW264.7 macrophages. ELISA was used to measure the levels of IL-18 and IL-1β in RAW264.7 cells. Transmission electron microscopy was applied to observe the number of autophagosomes in RAW264.7 cells. Immunofulourescence staining was used to detect the expression of LC3-Ⅱ and p62 in RAW264.7 cells. The result showed that GX significantly reduced the protein expression of NLRP3, ASC, and caspase-1 in RAW264.7 cells, significantly increased the protein expression of LC3Ⅱ, decreased the expression of p62, significantly inhibited the secretion of IL-18 and IL-1β, significantly increased the number of autophagosomes, significantly enhanced the immunofluorescence of LC3Ⅱ, and reduced the immunofluorescence of p62. Furthermore, 3-methyladenine(3-MA) could reverse the inhibitory effect of GX on NLRP3, ASC, and caspase-1 and reduce the release of IL-18 and IL-1β. In summary, GX can increase of the autophagy activity of RAW264.7 and inhibit the activation of NLRP3 inflammasome, thereby reducing the release of inflammatory cytokines and suppressing inflammatory response in macrophages.
Inflammasomes/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Interleukin-18/metabolism* ; Lipopolysaccharides/pharmacology* ; Macrophages ; Cytokines/metabolism* ; Caspase 1/metabolism* ; Autophagy ; Interleukin-1beta/metabolism*

OBJECTIVE: To explore the mechanism of F.nucleatum-induced pyroptosis in macrophages and the regulatory role of inflammasomes. METHODS: Lactate dehydrogenase (LDH) cytotoxicity assay and Hoechst 33342/PI double fluorescence staining were used to analyze cytolysis in F.nucleatum-infected macrophage RAW264.7 cells.The expressions of pyroptosis-related proteins caspase-1, GSDMD and IL-1β were determined using Western blotting.Inflammasome activation in the cells was analyzed by detecting the mRNA expressions of NLRP3, NLRC4, AIM2, and NLRP1 with qRT-PCR.RNA interference technique was used to knock down the key molecules involved in pyroptosis regulation in the macrophages, and the pyroptosis and necrosis rates of the cells following F.nucleatum infection were examined. RESULTS: The results of LDH cytotoxicity assay and double-fluorescence staining showed that F.nucleatum infection caused swelling and lytic cell death in RAW264.7 cells.F.nucleatum infection resulted in the activation of caspase-1 and GSDMD and upregulated IL-1β expression in a multiplicity of infection (MOI)-and time-dependent manner (P < 0.05).qRT-PCR revealed significantly increased expression of NLRC4 mRNA in the macrophages after F.nucleatum infection (P < 0.05).NLRC4 silencing by siRNA strongly inhibited the activation of caspase-1/GSDMD pathway and reduced cell death (P < 0.05) and IL-1β expression in F.nucleatum-infected cells. CONCLUSION NLRC4 inflammasome drives caspase-1/GSDMD-mediated pyroptosis and inflammatory signaling in F.nucleatum-infected macrophages, suggesting the potential of NLRC4 inflammasome as a therapeutic target for F.nucleatum infections.
Pyroptosis/genetics* ; Inflammasomes/metabolism* ; Caspase 1/metabolism* ; Interleukin-1beta/metabolism* ; Macrophages/metabolism* ; RNA, Messenger/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism*

The inflammasome is a multi-protein complex that induces maturation of inflammatory cytokines interleukin (IL)-1beta and IL-18 through activation of caspase-1. Several nucleotide binding oligomerization domain-like receptor family members, including NLRP3, recognize unique microbial and danger components and play a central role in inflammasome activation. The NLRP3 inflammasome is critical for maintenance of homeostasis against pathogenic infections. However, inflammasome activation acts as a double-edged sword for various bacterial infections. When the IL-1 family of cytokines is secreted excessively, they cause tissue damage and extensive inflammatory responses that are potentially hazardous for the host. Emerging evidence has shown that diverse bacterial pathogens or their components negatively regulate inflammasome activation to escape the immune response. In this review, we discuss the current knowledge of the roles and regulation of the NLRP3 inflammasome during bacterial infections. Activation and regulation of the NLRP3 inflammasome should be tightly controlled to prevent virulence and pathology during infections. Understanding the roles and regulatory mechanisms of the NLRP3 inflammasome is essential for developing potential treatment approaches against pathogenic infections.
Bacterial Infections/immunology/metabolism/pathology/prevention & control ; Carrier Proteins/*metabolism ; Caspase 1/metabolism ; Humans ; Inflammasomes/immunology/*metabolism ; Interleukin-1beta/metabolism ; Signal Transduction