Research Progress on the Relationship between the NLRP3 Inflammasome and Immune Reconstitution in HIV-Infected Patients Receiving Antiretroviral Therapy.

Human immunodeficiency virus (HIV) infection is characterized not only by severe immunodeficiency but also by persistent inflammation and immune activation. These characteristics persist in people living with HIV (PLHIV) receiving effective antiretroviral therapy (ART) and are associated with morbidity and mortality in nonacquired immunodeficiency syndrome (AIDS) events. ART can inhibit HIV replication and promote immune reconstitution, which is currently the most effective way to control AIDS. However, despite effective long-term ART and overall suppression of plasma HIV RNA level, PLHIV still shows chronic low-level inflammation. The exact mechanisms that trigger chronic inflammation are unknown. Activation of the inflammasome is essential for the host response to pathogens, and some recent studies have confirmed the role of the inflammasome in the pathogenesis of inflammatory diseases. The NLRP3 inflammasome has been widely studied, which is a pyrin domain-containing protein 3 belonging to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs). Recent studies suggest that inflammasome-mediated pyroptosis is associated with CD4+ T cell loss in the absence of persistent infectious HIV replication. This article reviews the mechanism of the NLRP3 inflammasome and its correlation with immune reconstitution in PLHIV treated with ART.

Alliin alleviates LPS-induced pyroptosis via promoting mitophagy in THP-1 macrophages and mice.

Pyroptosis is a new type of programmed cell death associated with inflammation. Excessive pyroptosis can cause body damage. Alliin is an organosulfur compound extracted from garlic, bearing anti-oxidation and anti-inflammatory properties. In this study, we revealed that alliin alleviated LPS-induced macrophage pyroptosis by detecting PI staining, IL-1ß and IL-18 release in vitro and in vivo. In the study of mechanism, we found that alliin might reduce the activation of NLRP3 inflammosome by decreasing intracellular ROS generation. Subsequently, we detected the effect of alliin on mitophagy which degraded damaged mitochondria. The results showed that alliin promoted PINK 1/Parkin-mediated mitophagy. After adding the mitophagy inhibitor CsA, the alleviating effect of alliin on mitochondrial damage and mitochondrial ROS were reversed and the relieving effect of alliin on LPS-induced pyroptosis was inhibited. These results suggested that alliin might reduce intracellular ROS production by promoting mitophagy, thus alleviating LPS-induced macrophages pyroptosis. Our study provides a new perspective and theoretical basis for alliin to alleviate pyroptosis which could further induce body damage.

Mechanosensitive TRPV4 is required for crystal-induced inflammation.

Crystal structures activate innate immune cells, especially macrophages and initiate inflammatory responses. We aimed to understand the role of the mechanosensitive TRPV4 channel in crystal-induced inflammation. Real-time RT-PCR, RNAscope in situ hybridisation, and Trpv4eGFP mice were used to examine TRPV4 expression and whole-cell patch-clamp recording and live-cell Ca2+ imaging were used to study TRPV4 function in mouse synovial macrophages and human peripheral blood mononuclear cells (PBMCs). Both genetic deletion and pharmacological inhibition approaches were used to investigate the role of TRPV4 in NLRP3 inflammasome activation induced by diverse crystals in vitro and in mouse models of crystal-induced pain and inflammation in vivo. TRPV4 was functionally expressed by synovial macrophages and human PBMCs and TRPV4 expression was upregulated by stimulation with monosodium urate (MSU) crystals and in human PBMCs from patients with acute gout flares. MSU crystal-induced gouty arthritis were significantly reduced by either genetic ablation or pharmacological inhibition of TRPV4 function. Mechanistically, TRPV4 mediated the activation of NLRP3 inflammasome by diverse crystalline materials but not non-crystalline NLRP3 inflammasome activators, driving the production of inflammatory cytokine interleukin-1ß which elicited TRPV4-dependent inflammatory responses in vivo. Moreover, chemical ablation of the TRPV1-expressing nociceptors significantly attenuated the MSU crystal-induced gouty arthritis. In conclusion, TRPV4 is a common mediator of inflammatory responses induced by diverse crystals through NLRP3 inflammasome activation in macrophages. TRPV4-expressing resident macrophages are critically involved in MSU crystal-induced gouty arthritis. A neuroimmune interaction between the TRPV1-expressing nociceptors and the TRPV4-expressing synovial macrophages contributes to the generation of acute gout flares.

Cicadidae Periostracum Attenuates Atopic Dermatitis Symptoms and Pathology via the Regulation of NLRP3 Inflammasome Activation.

Atopic dermatitis (AD) is a multifactorial inflammatory skin disease of complex etiology. Despite its increasing prevalence, treatment for AD is still limited. Crude drugs, including herbal extracts or natural resources, are being used to treat AD symptoms, with minimum side effects. Cicadidae Periostracum (CP), derived from the slough of insects belonging to the family Cicadidae, is a commonly used crude drug in traditional Asian medicine to treat/control epilepsy, shock, and edema. However, the effect of CP on AD-like skin lesions is unknown. In this study, we examined the effect of a CP water extract on AD disease development in vivo, using a house dust mite-induced AD mouse model, and in vitro, using HaCaT keratinocytes and a 3D human skin equivalent system. Importantly, CP administration alleviated house dust mite-induced AD-like symptoms, suggested by the quantified dermatitis scores, animal scratching behaviors, skin moisture retention capacity, and skin lesion and ear thickness. Furthermore, histopathological analysis demonstrated that CP decreased intralesional mast cell infiltration. In addition, CP treatments decreased the systemic levels of immunoglobulin E, histamine, and thymic stromal lymphopoietin (TSLP) and the local mRNA expression of TSLP and several Th1/Th2 cytokines. Our data suggest that these effects were mediated by the inhibition of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome activation. In vivo and in vitro CP treatments resulted in the downregulation of inflammasome components, such as ASC and cleaved caspase-1, as well as related mediators such as IL-1ß and reactive oxygen species. Collectively, our results suggest that CP is a potential therapeutic agent for AD, controlling inflammatory responses through the suppression of NLRP3 inflammasome activation.

Qingre Jianpi decoction attenuates inflammatory responses by suppressing NOD-like receptor family pyrin domain-containing 3 inflammasome activation in dextran sulfate sodium-induced colitis mice.

OBJECTIVE: To investigate the effects of Qingre Jianpi decoction (，QRJPD) on dextran sulfate sodium (DSS)-induced colitis mice and explore its mechanism. METHODS: All mice were randomly divided into six groups. Weight changes, disease activity index values, and histological damage were detected. Inflammatory cytokines and immune cell infiltration were measured using enzyme-linked immunosorbent assays (ELISA) and immunohistochemistry (IHC) method. The key protein expression levels of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome were detected by western blot analysis, IHC, and quantitative reverse transcription polymerase chain reaction. RESULTS: QRJPD played an anti-inflammatory role in the treatment of ulcerative colitis (UC), reduced the secretion of inflammatory cytokines, and inhibited the inflammatory infiltration of immune cells by suppressing DSS-induced activation of the NLRP3 inflammasome. CONCLUSION: QRJPD exerts protective effects by inhibiting DSS-induced NLRP3 inflammasome activation.

Curcumin analogue AI-44 alleviates MSU-induced gouty arthritis in mice via inhibiting cathepsin B-mediated NLRP3 inflammasome activation.

NOD-like receptors (NLRs), as a part of intracellular pattern recognition receptors (PRR), are important regulators in innate immune system. The NLRP3 inflammasome which is a member of NLRs has been linked to several human inflammatory diseases. Gouty arthritis is triggered when the deposition of monosodium urate (MSU) crystals in joints induces acute inflammation characterized by the recruitment of macrophages and neutrophils. In this study, we explored the curcumin analogue AI-44 alleviated the gouty arthritis in mice via suppressing MSU engaging NLRP3 inflammasome activation. Furthermore, we demonstrated that AI-44 inhibited the interaction of cathepsin B and NLRP3 to prevent the activation of NLRP3 inflammasome. Moreover, we found AI-44 inhibited the enzyme activity of cathepsin B and bound to the key residue E122 in cytoplasm but not in lysosome. Collectively, these data suggest that AI-44 is a novel drug candidate for the treatment of gouty arthritis through targeting cathepsin B and inhibiting NLRP3 inflammasome activation.

Intracellular NAD+ Depletion Confers a Priming Signal for NLRP3 Inflammasome Activation.

Nicotinamide adenine dinucleotide (NAD+) is an important cofactor in many redox and non-redox NAD+-consuming enzyme reactions. Intracellular NAD+ level steadily declines with age, but its role in the innate immune potential of myeloid cells remains elusive. In this study, we explored whether NAD+ depletion by FK866, a highly specific inhibitor of the NAD salvage pathway, can affect pattern recognition receptor-mediated responses in macrophages. NAD+-depleted mouse bone marrow-derived macrophages (BMDMs) exhibited similar levels of proinflammatory cytokine production in response to LPS or poly (I:C) stimulation compared with untreated cells. Instead, FK866 facilitated robust caspase-1 activation in BMDMs in the presence of NLRP3-activating signals such as ATP and nigericin, a potassium ionophore. However, this FK866-mediated caspase-1 activation was completely abolished in Nlrp3-deficient macrophages. FK866 plus nigericin stimulation caused an NLRP3-dependent assembly of inflammasome complex. In contrast, restoration of NAD+ level by supplementation with nicotinamide mononucleotide abrogated the FK866-mediated caspase-1 cleavage. FK866 did not induce or increase the expression levels of NLRP3 and interleukin (IL)-1ß but drove mitochondrial retrograde transport into the perinuclear region. FK866-nigericin-induced mitochondrial transport is critical for caspase-1 cleavage in macrophages. Consistent with the in vitro experiments, intradermal coinjection of FK866 and ATP resulted in robust IL-1ß expression and caspase-1 activation in the skin of wild-type, but not Nlrp3-deficient mice. Collectively, our data suggest that NAD+ depletion provides a non-transcriptional priming signal for NLRP3 activation via mitochondrial perinuclear clustering, and aging-associated NAD+ decline can trigger NLRP3 inflammasome activation in ATP-rich environments.

COVID-19: A Case for Inhibiting NLRP3 Inflammasome, Suppression of Inflammation with Curcumin?

Curcumin is the effective ingredient of turmeric, sometimes used as a painkiller in traditional medicine. It has extensive biological properties such as anti-inflammatory and antioxidant activities. SARS-CoV-2 is a betacoronavirus developing severe pneumonitis. Inflammasome is one of the most important components of innate immunity, which exacerbates inflammation by increasing IL-1ß and IL-18 production. Studies on viral infections have shown overactivity of inflammasome and thus the occurrence of destructive and systemic inflammation in patients. NLRP3 inflammasome has been shown to play a key role in the pathogenesis of viral diseases. The proliferation of SARS-CoV-2 in a wide range of cells can be combined with numerous observations of direct and indirect activation of inflammasome by other coronaviruses. Activation of the inflammasome is likely to be involved in the formation of cytokine storm. Curcumin regulates several molecules in the intracellular signal transduction pathways involved in inflammation, including IBB, NF-kBERK1,2, AP-1, TGF-ß, TXNIP, STAT3, PPARγ, JAK2-STAT3, NLRP3, p38MAPK, Nrf2, Notch-1, AMPK, TLR-4 and MyD-88. Due to anti-inflammatory and anti-inflammasome properties without any special side effects, curcumin can potentially play a role in the treatment of COVID-19 infection along with other drug regimens.

Echinatin effectively protects against NLRP3 inflammasome-driven diseases by targeting HSP90.

Aberrant activation of NLRP3 inflammasome has been implicated in a variety of human inflammatory diseases, but currently, no pharmacological NLRP3 inhibitor has been approved. In this study, we showed that echinatin, the ingredient of the traditional herbal medicine licorice, effectively suppresses the activation of NLRP3 inflammasome in vitro and in vivo. Further investigation revealed that echinatin exerts its inhibitory effect on NLRP3 inflammasome by binding to heat-shock protein 90 (HSP90), inhibiting its ATPase activity and disrupting the association between the cochaperone SGT1 and HSP90-NLRP3. Importantly, in vivo experiments demonstrated that administration of echinatin obviously inhibits NLRP3 inflammasome activation and ameliorates LPS-induced septic shock and dextran sodium sulfate-induced (DSS-induced) colitis in mice. Moreover, echinatin exerted favorable pharmacological effects on liver inflammation and fibrosis in a mouse model of nonalcoholic steatohepatitis (NASH). Collectively, our study identifies echinatin as a potentially novel inhibitor of NLRP3 inflammasome, and its use may be developed as a therapeutic approach for the treatment of NLRP3-driven diseases.

Cryptotanshinone specifically suppresses NLRP3 inflammasome activation and protects against inflammasome-mediated diseases.

NLRP3 inflammasome activation is implicated in the pathogenesis of a wide range of inflammatory diseases, but medications targeting the NLRP3 inflammasome are not available for clinical use. Here, we demonstrate that cryptotanshinone (CTS), a major component derived from the traditional medicinal herb Salvia miltiorrhiza Bunge, is a specific inhibitor for the NLRP3 inflammasome. Cryptotanshinone inhibits NLRP3 inflammasome activation in macrophages, but has no effects on AIM2 or NLRC4 inflammasome activation. Mechanistically, cryptotanshinone blocks Ca2+ signaling and the induction of mitochondrial reactive oxygen species (mtROS), which are important upstream signals of NLRP3 inflammasome activation. In vivo, cryptotanshinone attenuates caspase-1 activation and IL-1ß secretion in mouse models of NLRP3 inflammasome-mediated diseases such as endotoxemia syndrome and methionine- and choline-deficient-diet-induced nonalcoholic steatohepatitis (NASH). Our findings suggest that cryptotanshinone may be a promising therapeutic agent for the treatment of NLRP3 inflammasome-mediated diseases.

Reduning plus ribavirin display synergistic activity against severe pneumonia induced by H1N1 influenza A virus in mice.

OBJECTIVE: To investigate synergistic effect of Reduning (RDN) injection plus ribavirin against severe pneumonia induced by H1N1 influenza A virus in mice. METHODS: We established a mouse model of severe pneumonia induced by influenza A virus by infecting Balb/c mice with CA07 virus. We randomly assigned the infected mice into four groups, and treated them with normal saline (NS group), RDN (injection, 86.6 mg/kg), ribavirin (injection, 66.6 mg/kg) or double Ribavirin plus RDN group, the same dosage as used in the single treatments) for 5 d. Lung index and lung pathology were recorded or calculated in terms of the curative effective. Cytokines, NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome related protein including caspase-associated recruitment domain (CARD) domain Apoptosis-associated speck-like protein containing a caspase recruitment domain(ASC), caspase-1 and NOD-like receptor family, pyrin domain containing 3 (NLRP3), and reactive oxygen species were simultaneously investigated. RESULTS: RDN plus ribavirin treatment, not RDN or ribavirin alone, provided a significant survival benefit to the influenza A virus-infected mice. The combination treatment protected the mice against severe influenza infection by attenuating the severe lung injury. The combined treatment also reduced the viral titers in mouse lungs and lung index, downregulated their immunocytokine levels, including IL-1ß and IL-18, and down regulated the NLRP3, especially the transcription and translation of caspase-1. Meanwhile NS group had significantly higher reactive oxygen species (ROS) expression which could was dramatically reduced by the treatment of RDN plus ribavirin. CONCLUSION: Our study showed that RDN combined with ribavirin could protect the mice, and reduce the lung immunopathologic damage caused by severe influenza pneumonia. The mechanism could be that it reduced ROS produce and inhibited NLRP3 inflammasome activation so that mainly lower the downstream inflammatory cytokines IL-1ß and IL-18.

Soy isoflavones ameliorate experimental colitis by targeting ERα/NLRP3 inflammasome pathways.

Soy isoflavones (SIFs) are selective estrogen receptor modulators (SERMs) that have anti-inflammatory activities. Our previous study found that estrogen receptor α (ERα) directly regulates the NLRP3 transcription and NLRP3 inflammasome assembly. Therefore, we hypothesized that SIFs alleviate colitis via an ERα-dependent mechanism by targeting the NLRP3 inflammasome. The influence of SIFs on colitis and the potential mechanisms were thoroughly determined in this study. The results suggested that SIFs ameliorated dextran sodium sulfate (DSS)-induced body weight loss, reduced disease activity index and promoted the recovery of colon pathological damage in mice. Moreover, expression of the NLRP3 inflammasome was significantly inhibited, and the release of IL-1ß and IL-18 was suppressed by SIFs. Furthermore, ERα blockade ameliorated DSS-induced inflammatory responses in the intestine, and SIFs markedly suppressed the expression of ERα in a dose-dependent manner. Our study demonstrated that the protective therapeutic action of SIFs on DSS-induced colitis depended on inhibition of ERα and subsequent NLRP3 inflammasome activation, and SIFs are promising therapeutic agents for the treatment of colitis.

Salidroside protects mice against CCl4-induced acute liver injury via down-regulating CYP2E1 expression and inhibiting NLRP3 inflammasome activation.

Salidroside (Sal), a natural phenolic compound isolated from Rhodiola sachalinensis, has been utilized as anti-inflammatory and antioxidant for centuries, however, its effects against liver injury and the underlying mechanisms are unclear. This study was designed to evaluate the protective effects and underlying mechanisms of Sal on carbon tetrachloride (CCl4)-induced acute liver injury (ALI) in mice. C57BL/6 mice were pretreated with Sal before CCl4 injection, the serum and liver tissue were collected to evaluate liver damage and molecular indices. The results showed that Sal pretreatment dose-dependently attenuated CCl4-induced acute liver injury, as indicated by lowering the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and inhibiting hepatic pathological damage and apoptosis. In addition, Sal alleviated CCl4-primed oxidative stress and inflammatory response by restoring hepatic glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and inhibiting cytokines. Finally, Sal also down-regulated the expression of cytochrome P4502E1 (CYP2E1), and Nod-like receptor protein 3 (NLRP3) inflammasome activation in the liver of mice by CCl4. Our study demonstrates that Sal exerts its hepatoprotective effects on ALI through its antioxidant and anti-inflammatory effects, which might be mediated by down-regulating CYP2E1 expression and inhibiting NLRP3 inflammasome activation.

Microbiota-gut-brain axis in health and disease: Is NLRP3 inflammasome at the crossroads of microbiota-gut-brain communications?

Growing evidence highlights the relevance of microbiota-gut-brain axis in the maintenance of brain homeostasis as well as in the pathophysiology of major neurological and psychiatric disorders, including Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), autism spectrum disorder (ASD) and major depressive disorder (MDD). In particular, changes in gut microbiota can promote enteric and peripheral neurogenic/inflammatory responses, which, in turn, could contribute to neuroinflammation and neurodegeneration in the central nervous system (CNS). Of note, the nucleotide-binding oligomerization domain leucine rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome acts as a key player in both coordinating the host physiology and shaping the peripheral and central immune/inflammatory responses in CNS diseases. In this context, there is pioneering evidence supporting the existence of a microbiota-gut-inflammasome-brain axis, in which enteric bacteria modulate, via NLRP3 signaling, inflammatory pathways that, in turn, contribute to influence brain homeostasis. The present review provides an overview of current knowledge on the role of microbiota-gut-inflammasome-brain axis in the major CNS diseases, including PD, AD, MS, ASD and MDD. In particular, though no direct and causal correlation among altered gut microbiota, NLRP3 activation and brain pathology has been demonstrated and in-depth studies are needed in this setting, our purpose was to pave the way to a novel and pioneering perspective on the pathophysiology of CNS disorders. Our intent was also to highlight and discuss whether alterations of microbiota-gut-inflammasome-brain axis support a holistic view of the pathophysiology of CNS diseases, even though each disorder displays a different clinical picture.

Cinnamaldehyde suppresses NLRP3 derived IL-1ß via activating succinate/HIF-1 in rheumatoid arthritis rats.

Cinnamaldehyde (CA) is an essential component of cinnamon (Cinnamomum cassia Presland), which is often used as a flavoring condiment in beverages, pastries, perfumes, etc. Cinnamon is also used as herbal medicine in China and Southeast Asia to treat rheumatoid arthritis. However, the molecular mechanism is unclear. In this study, we aim to investigate its anti-inflammatory effects against Rheumatoid arthritis (RA) using activated macrophages (Raw246.7) in vitro and adjuvant arthritis rats (AA) in vivo. The results demonstrated that CA significantly reduced synovial inflammation in AA rats, possibly due to suppression of the expressions of pro-inflammatory cytokines, especially the IL-1ß. Further investigation found that CA also suppressed the activity of HIF-1α by inhibiting the accumulation of succinate in cytoplasm. As we know, the reduction of HIF-1α nucleation slows down IL-1ß production, because HIF-1α activates the expression of NLRP3, which is involved in the assembly of inflammasome and processing of IL-1ß. In addition, CA also inhibited the expression of the succinate receptor GPR91, which in turn inhibited the activation of HIF-1α. In conclusions, our results suggested that CA might be a potential therapeutic compound to relieve rheumatoid arthritis progress by suppressing IL-1ß through modulating succinate/HIF-1α axis and inhibition of NLRP3.

[Molecular regulative mechanisms of NLRP3 inflammasome activation in diabetic nephropathy and interventional effects of Chinese herbal medicine].

The progression of renal damage in diabetic nephropathy(DN)is closely related to Nod-like receptor protein3(NLRP3)inflammasome activation. The characteristics of NLRP3 inflammasome activation include the changed expression and combination levels of NLRP3, apoptosis-associated speck-like protein(ASC)and pro-caspase-1, the increased expression levels of caspase-1, interleukin(IL)-1ß and IL-18 and the excessive release levels of the relative inflammatory mediators. Its molecular regulative mechanisms involve the activation of multiple signaling pathways including reactive oxygen species(ROS)/thioredoxin-interacting protein(TXNIP)pathway, nuclear factor(NF)-κB pathway, nuclear factor erythroid-related factor 2(Nrf2)pathway, long non-coding RNA(lncRNA)pathway and mitogen-activated protein kinases(MAPKs)pathway. In addition, more importantly, never in mitosis aspergillus-related kinase 7(Nek7), as a kinase regulator, could target-combine with NLRP3 at upstream to activate NLRP3 inflammasome. Some extracts of Chinese herbal medicines(CHMs)such as quercetin, curcumin, cepharanthine, piperine and salidroside, as well as Chinese herbal compound prescriptions such as Wumei Pills both could treat NLRP3 inflammasome to ameliorate inflammatory renal damage in DN. Therefore, accurately clarifying the targets of anti-inflammatory CHMs and Chinese herbal compound prescriptions delaying DN progression by targeting the molecular regulative mechanisms of NLRP3 inflammasome activation will be one of the development directions in the future.

Protective effect of ginsenoside Rg5 against kidney injury via inhibition of NLRP3 inflammasome activation and the MAPK signaling pathway in high-fat diet/streptozotocin-induced diabetic mice.

Diabetic nephropathy (DN) is a common and serious complication of diabetes and causes kidney failure. Ginsenoside Rg5 (Rg5) is an important monomer in the main protopanaxadiol component of black ginseng. Rg5 has exhibited some beneficial biological effects, such as anti-cancer, neuroprotection, and anti-depression, but the effect of Rg5 on DN and its potential mechanism remains unclear. The aim of this study is to investigate the effect of Rg5 on kidney injury of C57BL/6 diabetic mice induced by high-fat diet and streptozotocin. After treatment with different concentration of Rg5 (30 and 60 mg kg-1·d-1) for 6 consecutive weeks, the fasting blood glucose, insulin levels, serum creatinine, serum urea, and serum UA in Rg5-treated DN mice were significantly reduced, while the renal histopathology was remarkably improved, compared with untreated DN mice. Moreover, ROS production, oxidative stress markers (MDA, SOD, and GSH-PX), Nox4 and TXNIP expressions of kidney in DN mice were significantly reduced after Rg5 treatment. Additionally, the expression levels of the NLRP3 inflammasome (NLRP3, ASC, and Caspase-1) and the inflammatory cytokines IL-1ß and IL-18 were significantly inhibited, and the expression of NF-kB and the phosphorylation of p38 MAPK were also decreased with Rg5 treatment compared with no treatment in DN mice. Together, our results indicate that Rg5 attenuated renal injury in diabetic mice by inhibiting oxidative stress and NLRP3 inflammasome activation to reduce inflammatory responses, indicating that Rg5 is a potential compound to prevent or control diabetic renal injury.

Electroacupuncture preconditioning attenuates acute myocardial ischemia injury through inhibiting NLRP3 inflammasome activation in mice.

AIMS: Electro-acupuncture pretreatment (EAP) plays a protective role in myocardial ischemia (MI) injury. However, the underlying mechanism remains unclear. A growing body of evidence suggests postinfarction inflammatory response directly affects the remodeling of ventricular function. The purpose of this study was to investigate whether EAP alleviates MI through NLRP3 inflammasome inhibition. MATERIALS AND METHODS: We constructed an AMI model by ligating the left anterior descending (LAD) coronary artery after 3 days of EAP with C57BL/6 mice. Echocardiography and TTC staining were employed to evaluate cardiac function and infarct size after 24 h of ischemia. HE staining and immunohistochemistry were employed to determine inflammatory level. Then, inflammasome activation was detected by western blotting, and macrophage polarization and neutrophil infiltration were observed by flow cytometry. KEY FINDINGS: Our preliminary findings showed that EAP reduced the infarct area and increased fractional shortening (FS) and ejection fraction (EF) and decreased the degree of inflammation after AMI injury. Meanwhile, EAP inhibited the expression of NLRP3, cleaved caspase-1 and IL-1ß in ischemia myocardial tissue, companied by inhibiting the expression of F4/80+, CD11b+, CD206low macrophages and activated M2 macrophage, and decreasing Ly-6G+CD11b+ neutrophils in ischemia myocardial and spleen tissue. SIGNIFICANCE: EAP inhibits the activation of NLRP3 inflammasome, promotes M2 polarization of macrophages and reduces the recruitment of neutrophils in damaged myocardium, thereby decreases the infarct size and improves the cardiac function.

Ginsenoside metabolite 20(S)-protopanaxatriol from Panax ginseng attenuates inflammation-mediated NLRP3 inflammasome activation.

ETHNOPHARMACOLOGICAL RELEVANCE: Panax ginseng C.A. Meyer (Araliaceae), has been used in traditional medicine for preventive and therapeutic purposes in Asian countries. One of the active ginsenoside metabolites, 20(S)-Protopanaxatriol (PPT), has been associated with diverse pharmacological effects, including anti-inflammatory properties. AIM OF THE STUDY: Although the capacity of PPT as an anti-inflammatory agent has been studied, this study aimed to explore the intrinsic mechanism of PPT in regulating inflammasome activation-mediated inflammatory responses in experimental models. MATERIALS AND METHODS: Lipopolysaccharide (LPS)-primed peritoneal macrophages in vitro was used to study the role of PPT on inflammasome activation. LPS-induced septic shock and monosodium urate (MSU)-induced murine peritonitis models were employed for in vivo evaluations. RESULTS: PPT attenuated NLRP3 inflammasome activation and also reduced ASC oligomerization, leading to attenuation of interleukin (IL)-1ß secretion. Further, PPT inhibited IL-1ß secretion in both LPS-induced septic shock and MSU-induced mouse peritonitis models. CONCLUSIONS: This study revealed that ginsenoside metabolite PPT, inhibits inflammation-mediated inflammasome activation and supported the traditional use of ginseng in treating various inflammatory disorders.

The Protective Effect of Crataegus aronia Against High-Fat Diet-Induced Vascular Inflammation in Rats Entails Inhibition of the NLRP-3 Inflammasome Pathway.

This study investigated whether the whole-plant aqueous extract of Crataegus aronia (C. aronia) could protect against or alleviate high-fat diet (HFD)-induced aortic vascular inflammation in rats by inhibiting the NLRP-3 inflammasome pathway and examined some mechanisms of action with respect to its antioxidant and hypolipidemic effects. Adult male Wistar rats were divided into five groups (n = 6/each): standard diet (10% fat) fed to control rats, control + C. aronia (200 mg/kg), HFD (40% fat), HFD + C. aronia, and HFD post-treated with C. aronia. The HFD was fed for 8 weeks and C. aronia was administered orally for 4 weeks. In addition, isolated macrophages from control rats were pre-incubated with two doses of C. aronia (25 and 50 µg/mL) with or without lipopolysaccharide (LPS) stimulation. Only in HFD-fed rats, co- and post-C. aronia therapy lowered circulatory levels of LDL-C and ox-LDL-c and aortic protein levels of LOX-1 and CD36. C. aronia also inhibited the nuclear accumulation of NF-κB and lowered protein levels of NLRP-3, caspase-1, and mature IL-1ß. In vitro, in the absence of ox-LDL-c, C. aronia led to reduced nuclear levels of NF-κB, ROS generation, and protein NLRP-3 levels, in both LPS-stimulated and unstimulated macrophages, in a dose-dependent manner. However, protein levels of LOX-1 were not affected by C. aronia in unstimulated cells. In conclusion, C. aronia inhibits the NLRP-3 inflammasome pathway, induced by HFD feeding in the aorta of rats, mainly by its hypolipidemic effect and in vitro, in LPS-stimulated macrophages, by its antioxidant effect.