Flavonoids interfere with NLRP3 inflammasome activation

Lim, Hyun,Min, Dong Suk,Park, Haeil,Kim, Hyun Pyo Elsevier 2018 Toxicology and applied pharmacology Vol.355 No.-

<P><B>Abstract</B></P> <P>NOD-like receptor (NLR) family, pyrin domain-containing 3 (NLRP3) inflammasome is a component of innate immunity, and is responsible for producing mature IL-1β and -18. Several flavonoids were found to affect inflammasome pathway, but the mechanism of action is still obscure. To elucidate the effects on NLRP3 inflammasome pathway and to determine the structure-activity relationships, NLRP3 inflammasome in differentiated THP-1 cells was activated via treatment with monosodium urate (MSU) crystals. Levels of mature IL-1β, NLRP3 inflammasome components and apoptosis-associated speck-like protein containing a CARD (caspase recruitment domain) (ASC) oligomerization were investigated and the mechanisms of action were also elucidated. Among the 56 flavonoids initially tested, only flavone, 2′,4′-dihhydroxyflavone, 3′,4′-dichloroflavone, 4′,5,7-trihydroxyflavone (apigenin), 3,4′,5,7-tetrahydroxyflavone (kaempferol) and 3,3′,4′,5,7-pentahydroxyflavone (quercetin) significantly inhibited IL-1β production at 10 μM. Apigenin, kaempferol and 3′,4′-dichloroflavone inhibited ASC oligomerization without affecting the ASC level in cell lysates. Apigenin also inhibited absent in melanoma 2 (AIM2) inflammasome-related pathway, but not NLR family CARD domain-containing protein 4 (NLRC4) inflammasome activation. The action of apigenin on NLRP3 inflammasome activation is mediated partly via inhibition of phosphorylation of spleen tyrosine kinase/protein tyrosine kinase 2 (Syk/Pyk2) pathway. Furthermore, orally administered apigenin (100 mg/kg) strongly reduced the number of neutrophils and monocytes in MSU-induced peritonitis in mice. The present study, for the first time, demonstrated the structure-activity profiles of flavonoids in NLRP3 inflammasome activation and mechanisms of cellular action. Certain flavonoids including apigenin are expected to ameliorate the inflammatory symptoms in autoinflammatory diseases associated with NLRP3 inflammasome activation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Certain flavonoids inhibit ASC oligomerization in NLRP3 inflammasome complex. </LI> <LI> Apigenin inhibits NLRP3 inflammasome partially by interrupting Syk/Pyk2 pathway. </LI> <LI> Apigenin inhibits NLRP3 and AIM2 inflammasome activation, but not NLRC4. </LI> <LI> Apigenin reduces peritoneal infiltrating cells in MSU-induced peritonitis in mice. </LI> <LI> Flavonoids are potential therapeutics for NLRP3 inflammasome-associated disorders. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Horse inflammasomes and the signal pathways

Gilyoung Lee,Geun-Shik Lee 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7

Inflammasome, a cytosolic multi-protein complex, is assembled by sensing intracellular pathogenic and endogenic danger signals fallowed by caspase-1 activation, which maturates precursor cytokines such as interleukin (IL)-1β. Most inflammasome researches have been studied in human and rodents, however the inflammasome in veterinary animals has not been well-characterized. In this study, we observed the effect of the well-known inflammasome activators on equine peripheral blood monocytes (PBMCs). NLRP3 inflammasome triggers, ATP, nigericin, aluminium crystals, and monosodium urate crystals, induced IL-1β secretion in dose-dependent manner. Activators of NLRC4 and AIM2 inflammasomes, cytosolic flagellin and dsDNA, provoked IL-1β secretion, and bacterial inflammasome triggers, Salmonella Typhimurium and Listeria monocytogenes, also elicited IL-1β releases. To elucidate the role of potassium efflux as an upstream signal of NLRP3 inflammasome activation, equine PBMCs, murine macrophages, and human monocyte-like cells (THP-1) were treated with blockers of potassium efflux, glibenclamide and high potassium solution, in the presence of NLRP3 triggers. As results, the potassium efflux was not relatively less involved in equine NLRP3 inflammasome activation compared to human and murine inflammasomes. Taken together, equine PBMCs normally secreted IL-1β in response to the well-known inflammasome activators although equine NLRP3 inflammasome might be differently regulated from human and mice.

Mitophagy: a balance regulator of NLRP3 inflammasome activation

( Min-ji Kim ),( Joo-heon Yoon ),( Ji-hwan Ryu ) 생화학분자생물학회 2016 BMB Reports Vol.49 No.10

The NLRP3 inflammasome is activated by a variety of external or host-derived stimuli and its activation initiates an inflammatory response through caspase-1 activation, resulting in inflammatory cytokine IL-1꺬 maturation and secretion. The NLRP3 inflammasome activation is a kind of innate immune response, most likely mediated by myeloid cells acting as a host defense mechanism. However, if this activation is not properly regulated, excessive inflammation induced by overactivated NLRP3 inflammasome can be detrimental to the host, causing tissue damage and organ dysfunction, eventually causing several diseases. Previous studies have suggested that mitochondrial damage may be a cause of NLRP3 inflammasome activation and autophagy, which is a conserved self-degradation process that negatively regulates NLRP3 inflammasome activation. Recently, mitochondria-selective autophagy, termed mitophagy, has emerged as a central player for maintaining mitochondrial homeostasis through the elimination of damaged mitochondria, leading to the prevention of hyperinflammation triggered by NLRP3 inflammasome activation. In this review, we will first focus on the molecular mechanisms of NLRP3 inflammasome activation and NLRP3 inflammasome-related diseases. We will then discuss autophagy, especially mitophagy, as a negative regulator of NLPP3 inflammasome activation by examining recent advances in research. [BMB Reports 2016; 49(10): 529-535]

Repurposing Auranofin, an Anti-Rheumatic Gold Compound, to Treat Acne Vulgaris by Targeting the NLRP3 Inflammasome

( Gabsik Yang ),( Seon Joo Lee ),( Han Chang Kang ),( Yong-yeon Cho ),( Hye Suk Lee ),( Christos C. Zouboulis ),( Sin-hee Han ),( Kyung-ho Ma ),( Jae-ki Jang ),( Joo Young Lee ) 한국응용약물학회 2020 Biomolecules & Therapeutics(구 응용약물학회지) Vol.28 No.5

Activation of the NLRP3 inflammasome is critical for host defense as well as the progression of inflammatory diseases through the production of the proinflammatory cytokine IL-1β, which is cleaved by active caspase-1. It has been reported that overactivation of the NLRP3 inflammasome contributes to the development and pathology of acne vulgaris. Therefore, inhibiting activation of the NLRP3 inflammasome may provide a new therapeutic strategy for acne vulgaris. In this study, we investigated whether auranofin, an anti-rheumatoid arthritis agent, inhibited NLRP3 inflammasome activation, thereby effectively treating acne vulgaris. Auranofin suppressed NLRP3 inflammasome activation induced by Propionibacterium acnes, reducing the production of IL-1β in primary mouse macrophages and human sebocytes. In a P. acnes-induced acne mouse model, injection of P. acnes into the ears of mice induced acne symptoms such as redness, swelling, and neutrophil infiltration. Topical application of auranofin (0.5 or 1%) to mouse ears significantly reduced the inflammatory symptoms of acne vulgaris induced by P. acnes injection. Topical application of auranofin led to the downregulation of the NLRP3 inflammasome activated by P. acnes in mouse ear skin. These results show that auranofin inhibits the NLRP3 inflammasome, the activation of which is associated with acne symptoms. The results further suggest that topical application of auranofin could be a new therapeutic strategy for treating acne vulgaris by targeting the NLRP3 inflammasome.

Mitochondria-associated NLRP3 inflammasome contributes to LPS-induced neutrophil-dominant acute lung injury

( So Ri Kim ),( Hee Jung Kim ),( Yong Chul Lee ),( Yeong Hun Choe ),( Seung Yong Park ),( Jae Seok Jeong ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.0

Purpose: NLRP3 inflammasome activation has been demonstrated to play a critical role in various pulmonary inflammatory disorders including acute lung injury/acute respiratory distress syndrome. Besides, mitochondrial reactive oxygen species (ROS) induce the assembly of the NLRP3 inflammasome. Some NLRP family members are known to localize to the mitochondria. However, the localization and the role of NLRP3 in the mitochondrial fraction are not well known. Methods: In this study, we aimed to evaluate the localization of NLRP3 in mitochondria of various inflammatory cells under LPS-induced neutrophilic pulmonary inflammation and pharmacologic effects of MCC950, a specific NLRP3 inflammasome inhibitor on LPS-induced acute lung injury using animal models and human samples. Results: LPS-instilled mice showed typical features of neutrophil-dominant acute lung injury; pulmonary neutrophilia, vascular leakage, nuclear translocation of nuclear factor-κB (NF-κB), increased expression of Toll-like receptor 4 (TLR4), and mitochondrial ROS generation. Interestingly, the NLRP3 inflammasome activation indicators, NLRP3, caspase-1, IL-1β, and IL-18 were dramatically increased in lung tissues, particularly in the mitochondrial fraction. Moreover, we also found that NLRP3 inflammasome effector cytokines; mature IL-1β and IL-18 as well as mitochondria fractions were increased in the plasma from patients with neutrophilic acute lung injury. When MCC950 or NecroX was administered to LPS-instilled mice, mice showed the dramatic improvement of all inflammatory features including NLRP3 inflammasome activation, particularly in the mitochondrial fraction-associated ones. Conclusion: These findings suggest that NLRP3 inflammasome assembly, especially mitochondrial-associated NLRP3 plays critical roles in the pathogenesis of LPS-induced pulmonary inflammation and that plasma NLRP3-related proteins or mitochondrial volume can be a biomarker predicting the severity and therapeutic responses of the inflammasome inhibitors in neutrophilic acute lung injury.

<i>Mycobacterium abscessus</i> activates the NLRP3 inflammasome via Dectin-1–Syk and p62/SQSTM1

Lee, Hye-Mi,Yuk, Jae-Min,Kim, Ki-Hye,Jang, Jichan,Kang, Gun,Park, Jin Bong,Son, Ji-Woong,Jo, Eun-Kyeong Nature Publishing Group 2012 Immunology and Cell Biology Vol.90 No.6

<P>Numerous atypical mycobacteria, including <I>Mycobacterium abscessus</I> (Mabc), cause nontuberculous mycobacterial infections, which present a serious public health threat. Inflammasome activation is involved in host defense and the pathogenesis of autoimmune diseases. However, inflammasome activation has not been widely characterized in human macrophages infected with atypical mycobacteria. Here, we demonstrate that Mabc robustly activates the nucleotide binding and oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome via dectin-1/Syk-dependent signaling and the cytoplasmic scaffold protein p62/SQSTM1 (p62) in human macrophages. Both dectin-1 and Toll-like receptor 2 (TLR2) were required for Mabc-induced mRNA expression of pro-interleukin (IL)-1β, cathelicidin human cationic antimicrobial protein-18/LL-37 and β-defensin 4 (DEFB4). Dectin-1-dependent Syk signaling, but not that of MyD88, led to the activation of caspase-1 and secretion of IL-1β through the activation of an NLRP3/apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) inflammasome. Additionally, potassium efflux was required for Mabc-induced NLRP3/ASC inflammasome activation. Furthermore, Mabc-induced p62 expression was critically involved in NLRP3 inflammasome activation in human macrophages. Finally, NLRP3/ASC was critical for the inflammasome in antimicrobial responses to Mabc infection. Taken together, these data demonstrate the induction mechanism of the NLRP3/ASC inflammasome and its role in innate immunity to Mabc infection.</P>

Fructose-arginine regulates AIM2 inflammasome activation

Gilyoung Lee,Geun-Shik Lee 한국실험동물학회 2021 한국실험동물학회 학술발표대회 논문집 Vol.2021 No.7

Korean Red Ginseng extract (RGE) has been reported to act as an inflammasome modulator. Ginsenosides, saponin molecules of RGE, selectively inhibit activation of NLRP3 and AIM2 inflammasomes, while non-saponin molecules of RGE upregulate inflammasome components associated with the initiation of NLRP3 inflammasome activation. In this study, we investigated the effect of non-saponin components of RGE on AIM2 inflammasome activation. The role of non-saponins of RGE on AIM2 inflammasomes was tested in mouse bone marrow derived macrophages, a human monocyte-like cell line, and a mouse animal model. Cells or mice were transfected with dsDNA or inoculated with Listeria monocytogenes to activate AIM2 inflammasomes. Several indices of inflammasome activation were examined via immunoblot or ELISA analysis. The non-saponin fraction and saponin-eliminating fraction (SEF) of RGE selectively attenuated the activation of AIM2 inflammasomes, but not that of NLRP3 or NLRC4 inflammasomes. Fructose-arginine, an amino-sugar, was shown to be effective against AIM2 inflammasome activation. Non-saponins of RGE, such as fructose-arginine, might be effective in regulating infectious and autoimmune diseases resulting from AIM2 inflammasome activation.

Fructose-arginine, a non-saponin molecule of Korean Red Ginseng, attenuates AIM2 inflammasome activation

Ahn, Huijeong,Han, Byung-Cheol,Lee, Seung-Ho,Lee, Geun-Shik The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.6

Background: Korean Red Ginseng extract (RGE) has been reported to act as an inflammasome modulator. Ginsenosides, saponin molecules of RGE, selectively inhibit activation of NLRP3 and AIM2 inflammasomes, while non-saponin molecules of RGE upregulate inflammasome components associated with the initiation of NLRP3 inflammasome activation. In this study, we investigated the effect of non-saponin components of RGE on AIM2 inflammasome activation. Methods: The role of non-saponins of RGE on AIM2 inflammasomes was tested in mouse bone marrow-derived macrophages, a human monocyte-like cell line, and a mouse animal model. Cells or mice were transfected with dsDNA or inoculated with Listeria monocytogenes to activate AIM2 inflammasomes. Several indices of inflammasome activation were examined via immunoblot or ELISA analysis. Results: The non-saponin fraction and saponin-eliminating fraction (SEF) of RGE selectively attenuated the activation of AIM2 inflammasomes, but not that of NLRP3 or NLRC4 inflammasomes. Fructose-arginine, an amino-sugar, was shown to be effective against AIM2 inflammasome activation. Conclusion: Non-saponins of RGE, such as fructose-arginine, might be effective in regulating infectious and autoimmune diseases resulting from AIM2 inflammasome activation.

Nucleotide-Binding Oligomerization Domain-Like Receptor 3 Inflammasome Inhibition by MCC950 Reduces the Lipopolysaccharide-Induced Interleukin-1β in Cultured Dispersed Nasal Polyp Cells

박수경,한예녕,허준,연선희,이성복,송근호,변진희,나기상,김용민 대한이비인후과학회 2020 대한이비인후과학회지 두경부외과학 Vol.63 No.5

Background and Objectives The nucleotide-binding oligomerization domain-like receptor(NLRP) 3 is known as a member of the NLR family, and it has been confirmed that the NLRP3inflammasome is associated with various diseases such as asthma, inflammatory bowel disease,metabolic disorders and multiple sclerosis, as well as other auto-immune and auto-inflammatorydiseases. However, the role of NLRP3 in chronic rhinosinusitis with nasal polyps (CRSwNP)has not yet been explored. Subjects and Method Forty-four specimens of nasal polyps and 25 specimens of uncinateprocesses were collected from patients with chronic rhinosinusitis with nasal polyps, and 25specimens of uncinate tissues were collected from patients who underwent other rhino-surgeries. The western blot assay was employed to analyze the expression of NLRP3; interleukin (IL)-1βand IL-17A were detected using immunohistochemistry and real-time polymerase chain reaction. The production of lipopolysaccharide (LPS) induced IL-1β and IL-17A with or without theNLRP3 inflammasome inhibitor (MCC950) was measured using an enzyme linked immunosorbentassay in cultured dispersed nasal polyp cells. Results NLRP3 showed a high level of expression in nasal polyps than in the control group(p<0.01). The expression of IL-1β and IL-17A was significantly higher in nasal polyps in theCRSwNP group than in the control group (p<0.05). LPS-induced production of IL-1β was significantlysuppressed by treatment with the NLRP3 inflammasome inhibitor (p<0.05). Conclusion The NLRP3 inflammasome plays an essential role in the pathogenesis of CRSwNP,and thus MCC950 can be considered a prospective therapeutic for NLRP3 inflammasome-mediatedinflammation in nasal polyps. Our data provide new evidence that IL-17A is involved in inflammasome-associated inflammation in nasal polyps.

Pyrin Domain (PYD)-containing Inflammasome in Innate Immunity

Hong, Su-Jeong,Park, Sang-Jun,Yu, Je-Wook The Korean Society for Microbiology 2011 Journal of Bacteriology and Virology Vol.41 No.3

Inflammasome is a cytosolic multiprotein complex to activate caspase-1 leading to the subsequent processing of inactive pro-interleukin-1-beta (Pro-IL-$1{\beta}$) into its active interleukin-1 beta (IL-$1{\beta}$) in response to pathogen- or dangerassociated molecular pattern. In recent years, a huge progress has been made to identify inflammasome component as a molecular platform to recruit and activate caspase-1. Nucleotide-binding oligomerization domain-like receptor (NLR) family proteins such as NLRP1, NLRP3 or interleukin-$1{\beta}$-converting enzyme (ICE)-protease activating factor (IPAF) have been first characterized to form inflammasome complex to induce caspase-1 activation. More recently, non-NLR type, pyrin-domain (PYD)-containing proteins such as pyrin or absent in melanoma2 (AIM2) were also proposed to form caspase-1-activating inflammasome machinery with apoptosis-associated speck-like protein containing a CARD (ASC), an essential adaptor molecule. Inflammasome pathways were shown to be crucial for protecting host organisms against diverse pathogen infections, but accumulating evidences also suggest that excessive activation of inflammasome/ caspase-1 might be related to the pathogenesis of inflammation-related diseases. Indeed, mutations in NLRP3 or pyrin are closely associated with autoinflammatory diseases such as familial Mediterranean fever (FMF) syndrome or Muckle-Wells syndrome (MWS), indicating that the regulation of caspase-1 activity by inflammasome is a central process in these hereditary inflammatory disorders. Here, recent advances on the molecular mechanism of caspase-1 activation by PYD-containing inflammasomes are summarized and discussed.