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

Inflammasomes are high-molecular-weight, multiprotein complexes in cells, which are assembled after cytoplasmic nucleotide-binding oligomerization domain like receptors (NLRs) sense pathogens and danger signals. The inflammasome can activate caspase-1, and later makes the pro-IL-1β, proIL-18 precursor mature by cleavaging, thereby mediates the innate immunity. Dysregulation of inflammasomes plays an important role in the development of sepsis and other immune inflammatory diseases, thus inflammasome may be a new target for prevention and treatment of sepsis.
Caspase 1 ; immunology ; metabolism ; Humans ; Inflammasomes ; chemistry ; immunology ; metabolism ; Interleukin-18 ; immunology ; metabolism ; Interleukin-1beta ; immunology ; metabolism ; Sepsis ; immunology ; metabolism ; Signal Transduction

Chronic inflammatory responses have long been observed to be associated with various types of cancer and play decisive roles at different stages of cancer development. Inflammasomes, which are potent inducers of interleukin (IL)-1β and IL-18 during inflammation, are large protein complexes typically consisting of a Nod-like receptor (NLR), the adapter protein ASC, and Caspase-1. During malignant transformation or cancer therapy, the inflammasomes are postulated to become activated in response to danger signals arising from the tumors or from therapy-induced damage to the tumor or healthy tissue. The activation of inflammasomes plays diverse and sometimes contrasting roles in cancer promotion and therapy depending on the specific context. Here we summarize the role of different inflammasome complexes in cancer progression and therapy. Inflammasome components and pathways may provide novel targets to treat certain types of cancer; however, using such agents should be cautiously evaluated due to the complex roles that inflammasomes and pro-inflammatory cytokines play in immunity.
Animals ; Carcinoma ; immunology ; pathology ; therapy ; Gastrointestinal Neoplasms ; immunology ; pathology ; therapy ; Humans ; Inflammasomes ; metabolism ; Melanoma ; immunology ; pathology ; therapy ; Neoplasms ; immunology ; pathology ; therapy ; Skin Neoplasms ; immunology ; pathology ; therapy

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

Inflammasomes are large multi-protein complexes that serve as a platform for caspase-1 activation, and this process induces subsequent maturation and secretion of the proinflammatory cytokines IL-1β and IL-18, as well as pyroptosis. As an important component of the innate immune system, early activation of inflammasomes in a variety of immune cell subsets can mediate inflammatory response and immunological conditions after burn injury. Here, we review the current knowledge of inflammasomes and its role in immunological and inflammatory response at the early stage of burn injury.
Apoptosis ; Burns ; immunology ; Caspase 1 ; metabolism ; Cytokines ; Humans ; Inflammasomes ; physiology ; Inflammation Mediators ; immunology ; Interleukin-18 ; immunology ; physiology ; Interleukin-1beta ; immunology ; physiology

The NLRP3 inflammasome, a protein complex belonging to the family of nucleotide-binding and oligomerization domain like receptors (NLRs), plays a vital role in the innate immune system. It promotes pro-caspase 1 cleavage into active caspase-1, which contributes to maturation and releases of IL-1β and IL-18 in response to the harmful signals and participates in the host immune response and sterile inflammation. Recently a large number of studies have shown that NLRP3 inflammasome closely relates to the pathogenesis of the vascular diseases. NLRP3 inflammasome, which involves in the sterile inflammation of the vascular wall, plays an important role in the pathogenesis of main, middle and small arteries.
Caspase 1 ; immunology ; metabolism ; Gene Expression Regulation ; genetics ; immunology ; Humans ; Inflammasomes ; immunology ; Inflammation ; complications ; genetics ; Interleukin-18 ; genetics ; immunology ; Interleukin-1beta ; genetics ; immunology ; NLR Family, Pyrin Domain-Containing 3 Protein ; immunology ; Signal Transduction ; genetics ; immunology ; Vascular Diseases ; etiology ; genetics ; immunology

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are pattern-recognition receptors similar to toll-like receptors (TLRs). While TLRs are transmembrane receptors, NLRs are cytoplasmic receptors that play a crucial role in the innate immune response by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Based on their N-terminal domain, NLRs are divided into four subfamilies: NLRA, NLRB, NLRC, and NLRP. NLRs can also be divided into four broad functional categories: inflammasome assembly, signaling transduction, transcription activation, and autophagy. In addition to recognizing PAMPs and DAMPs, NLRs act as a key regulator of apoptosis and early development. Therefore, there are significant associations between NLRs and various diseases related to infection and immunity. NLR studies have recently begun to unveil the roles of NLRs in diseases such as gout, cryopyrin-associated periodic fever syndromes, and Crohn's disease. As these new associations between NRLs and diseases may improve our understanding of disease pathogenesis and lead to new approaches for the prevention and treatment of such diseases, NLRs are becoming increasingly relevant to clinicians. In this review, we provide a concise overview of NLRs and their role in infection, immunity, and disease, particularly from clinical perspectives.
Autophagy/immunology ; Carrier Proteins ; Humans ; *Immunity, Innate ; Inflammasomes ; Nod Signaling Adaptor Proteins/immunology/*metabolism ; Pathogen-Associated Molecular Pattern Molecules ; Receptors, Cytoplasmic and Nuclear/immunology/*metabolism ; Receptors, Pattern Recognition/*immunology ; *Signal Transduction ; Toll-Like Receptors/metabolism

Inflammasomes are multiprotein complexes that serve as a platform for caspase-1 activation and interleukin-1β (IL-1β) maturation as well as pyroptosis. Though a number of inflammasomes have been described, the NLRP3 inflammasome is the most extensively studied. NLRP3 inflammasome is triggered by a variety of stimuli, including infection, tissue damage and metabolic dysregulation, and then activated through an integrated cellular signal. Many regulatory mechanisms have been identified to attenuate NLRP3 inflammasome signaling at multiple steps. Here, we review the developments in the negative regulation of NLRP3 inflammasome that protect host from inflammatory damage.
Animals ; Autophagy ; Carrier Proteins ; antagonists & inhibitors ; metabolism ; Caspase 1 ; metabolism ; Humans ; Inflammasomes ; metabolism ; Interferon Type I ; metabolism ; MicroRNAs ; metabolism ; NLR Family, Pyrin Domain-Containing 3 Protein ; Nitric Oxide ; metabolism ; Signal Transduction ; T-Lymphocytes ; immunology ; metabolism

Animals ; Carrier Proteins ; metabolism ; Caspase 1 ; metabolism ; Humans ; Inflammasomes ; metabolism ; Interleukin-1beta ; metabolism ; Lipopolysaccharides ; toxicity ; Mice ; Monocytes ; drug effects ; immunology ; metabolism ; NLR Family, Pyrin Domain-Containing 3 Protein ; Signal Transduction ; drug effects

Although the etiology of inflammatory bowel disease is still uncertain, increasing evidence indicates that the excessive activation of NLRP3 inflammasome plays a major role. Norisoboldine (NOR), an alkaloid isolated from Radix Linderae, has previously been demonstrated to inhibit inflammation and IL-1β production. The present study was to examine the effect of NOR on colitis and the underlying mechanism related to NLRP3 inflammasome activation. Our results showed that NOR alleviated colitis symptom in mice induced by 2, 4, 6-trinitrobenzene sulfonic acid (TNBS). Moreover, it significantly reduced expressions of cleaved IL-1β, NLRP3 and cleaved Caspase-1 but not ASC in colons of mice. In THP-1 cells, NOR suppressed the expressions of NLRP3, cleaved Caspase-1 and cleaved IL-1β but not ASC induced by lipopolysaccharide (LPS) and adenosine triphosphate (ATP). Furthermore, NOR could activate aryl hydrocarbon receptor (AhR) in THP-1 cells, inducing CYP1A1 mRNA expression, and promoting dissociation of AhR/HSP90 complexes, association of AhR and ARNT, AhR nuclear translocation, XRE reporter activity and binding activity of AhR/ARNT/XRE. Both siAhR and α-naphthoflavone (α-NF) markedly diminished the inhibition of NOR on NLRP3 inflammasome activation. In addition, NOR elevated Nrf2 level and reduced ROS level in LPS- and ATP-stimulated THP-1 cells, which was reversed by either siAhR or α-NF treatment. Finally, correlations between activation of AhR and attenuation of colitis, inhibition of NLRP3 inflammasome activation and up-regulation of Nrf2 level in colons were validated in mice with TNBS-induced colitis. Taken together, NOR ameliorated TNBS-induced colitis in mice through inhibiting NLRP3 inflammasome activation via regulating AhR/Nrf2/ROS signaling pathway.
Alkaloids ; administration & dosage ; Animals ; Colitis ; chemically induced ; drug therapy ; genetics ; immunology ; Drugs, Chinese Herbal ; administration & dosage ; Humans ; Inflammasomes ; drug effects ; immunology ; Interleukin-1beta ; genetics ; immunology ; Lindera ; chemistry ; Male ; Mice ; Mice, Inbred BALB C ; NF-kappa B ; genetics ; immunology ; Receptors, Aryl Hydrocarbon ; agonists ; genetics ; metabolism ; Trinitrobenzenesulfonic Acid ; adverse effects