NLRP3 Signaling Pathway Research Articles

Evaluation on the effect of hydrogen sulfide on the NLRP3 signaling pathway and its involvement in the pathogenesis of atherosclerosis.

As a common disease, the incidence of atherosclerosis (AS) in the world is high. Therefore, we aimed to evaluate the involvement of hydrogen sulfide (H 2 S)/cystathionine γ-lyase (CSE) in the pathogenesis of AS as well as their possible signaling pathways. Enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blot analysis were used to detect the effect of CSE on the expression of inflammatory cytokines, ie, H 2 S, thioredoxin-interacting protein (TXNIP), NLRP3, apoptosis-associated speck-like protein (ASC), caspase-1, and interleukin (IL)-1β. In addition, immunohistochemistry and Western blot analysis were performed to detect the levels of TXNIP, NLRP3, ASC, caspase-1, IL-1β, and IL-18 among different groups. Knockdown of CSE by the transfection of CSE small interfering RNA upregulated the levels of two inflammatory cytokines, ie, IL-1β and IL-18. In addition, the downregulation of CSE promoted the expression of TXNIP, NLRP3, ASC, caspase-1, and IL-1β in THP-1 cells. Meanwhile, treating the cells with sodium hydrosulfide (NaHS) inhibited the productions of IL-1β and IL-18. Furthermore, upregulation of H 2 S synthesis by treating the cells with NaHS also reduced the protein levels of TXNIP, NLRP3, ASC, caspase-1, and IL-1β. Finally, the protein levels of TXNIP and NLRP3 in the AS group were much higher than those in the AS + H 2 S group, which in turn was higher than the sham group. In addition, the AS group displayed the highest protein levels of TXNIP, NLRP3, ASC, caspase-1, IL-1β, and IL-18, while the levels of these proteins in the AS + H 2 S group were higher than those in the sham group. In summary, the present finding suggested a possible linkage between H 2 S metabolism and AS through the H 2 S/CSE-TXNIP-NLRP3-IL-18/IL-1β-nitric oxide (NO) signaling pathway.

Crocin, a natural product attenuates lipopolysaccharide-induced anxiety and depressive-like behaviors through suppressing NF-kB and NLRP3 signaling pathway

Depression is one of the foremost psychological illness which is closely leagued with inflammation. Crocin is a natural product that exhibits both anti-inflammatory and anti-oxidant activities. However, little is known about anti-inflammatory mechanisms of crocin on LPS-induced anxiety and depressive-like behaviors. The objective of this study is emphasized on neuroprotective role of crocin against LPS-induced anxiety and depressive-like behaviors in mice. It is observed that crocin inhibited LPS-induced production of NO, TNF-α, IL-1β and ROS in BV-2 microglial cells. Moreover, crocin significantly declined the expression of iNOS, NF-κB p65 and CD16/32 (M1 marker), as well as elevated the expression of CD206 (M2 marker) in BV-2 cell line with decreased LPS-induced anxiety and depressive-like behaviors by improved locomotor activity, reduced sucrose intake, and decreased immobility time in forced swim and tail suspension test in Kunming mice. Expression of NLRP3, ASC and caspase-1 by i.p administration of LPS found to be neutralized with reduction in level of IL-1β, IL-18 and TNF-α in mouse hippocampus. In conclusion, these results suggested that crocin as a potential therapeutic candidate for neuro-inflammation and depressive-like behaviors induced by LPS. The effect was found to be due to inhibition of NLRP3 inflammasome and NF-κB and its promoted M1 to M2 phenotypic conversion of microglia.

Galangin protects human rheumatoid arthritis fibroblast‑like synoviocytes via suppression of the NF‑κB/NLRP3 pathway.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that significantly affects patient quality of life. Galangin is an extract with multiple health benefits, including anti‑oxidative, anti‑proliferative, immunoprotective and cardioprotective effects. However, to the best of the authors' knowledge, no detailed studies have investigated its regulatory effects on the nuclear factor (NF)‑κB/NLR family pyrin domain containing 3 (NLRP3) signaling pathway. The present study aimed to investigate the protective mechanism of galangin in RA fibroblast‑like synoviocytes with regards to the NF‑κB/NLRP3 signaling pathway. Human RA fibroblast‑like synovium cells (RAFSCs) were treated with lipopolysaccharide (LPS) to induce inflammation. The levels of interleukin (IL)‑1β, tumor necrosis factor (TNF)‑α, IL‑18, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)‑2, prostaglandin E2 (PGE2), and nitric oxide (NO) were measured by enzyme‑linked immunosorbent assay or western blotting in the absence or presence of different concentrations of galangin. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were additionally evaluated. Furthermore, factors involved in the NF‑κB/NLRP3 pathway, including NLRP3, apoptosis‑associated speck‑like protein containing A, IL‑1β, pro‑caspase‑1, caspase‑1, phosphorylated (p)‑NF‑κB inhibitor α and p‑NF‑κB, were assessed by western blotting. The results revealed that LPS significantly stimulated IL‑1β, TNF‑α, IL‑18, PGE2, NO, iNOS, COX‑2 and NF‑κB/NLRP3 factor expression, compared with the control. SOD activity was reduced. Pre‑treatment with galangin significantly attenuated the effects of LPS, and galangin was demonstrated to have effective anti‑oxidative properties. In conclusion, galangin protected RAFSCs through downregulation of the NF‑κB/NLRP3 signaling pathway. These findings suggested that galangin may provide a novel direction for the development of RA therapies in the future.

Triiodothyronine alleviates alcoholic liver disease injury through the negative regulation of the NLRP3 signaling pathway.

The aim of the present study was to investigate the effect and mechanism of triiodothyronine (T3) on alcoholic liver disease (ALD)-induced injuries in mice. A total of 40 male C57/BL6 mice were randomly divided into the Control, ALD, ALD+T3 and ALD+T3+AMP-activated protein kinase inhibitor (CC) groups. Mice were administered alcohol (4 g/kg/day) intragastrically for 4 weeks except for Control group. Mice in the ALD+T3 group were given T3 (0.1 mg/kg/day) while mice in ALD+T3+CC group were given T3 (0.1 mg/kg/day) and CC (10 mg/kg/day) for 1 week. Control and ALD groups were treated with saline. Liver tissue and blood samples were obtained for testing. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) levels were determined and morphological changes in the liver tissues were observed under the optical microscope. Inflammatory factors, including IL-1β and transforming growth factor (TGF)-β/1, α-smooth muscle actin (SMA) and protein levels of nucleotide-binding oligomerization domain, leucine rich repeat containing family, pyrin domain containing 3 (NLRP3), caspase-1 and pro-IL-1β were measured. Serum ALT, AST and TBIL levels in the ALD+T3 group were significantly reduced compared with the ALD group, while they were significantly increased in the ALD+T3+CC group (P<0.05). The number of hepatic lobules in the ALD+T3 group was significantly reduced compared with the ALD group, whereas the number in the ALD+T3+CC group was significantly increased (P<0.05). IL-1β and TGF-β1 levels in the ALD+T3 group were significantly decreased compared with the ALD group; however, levels in the ALD+T3+CC group were significantly increased compared with the ALD+T3 group (P<0.05). In addition, it was revealed that the expression of α-SMA mRNA and protein in the ALD+T3 group was significantly decreased compared with the ALD group, whereas it was significantly increased in the ALD+T3+CC group compared with the ALD+T3 group. Expression of NLRP3, caspase-1, IL-1β and TGF-β1 in the ALD+T3 group was significantly decreased compared with the ALD group, while expression was significantly increased in the ALD+T3+CC group. Conversely, compared with the ALD group, expression of pro-IL-1β was significantly increased in the ALD+T3 group and decreased in the ALD+T3+CC group. In conclusion, T3 may reduce the inflammatory response and severity of liver cirrhosis in mice with ALD by negatively regulating the NLRP3 signaling pathway.

NLRP3 inflammasome inhibition ameliorates tubulointerstitial injury in the remnant kidney model

Recent studies suggest that NLRP3 inflammasome activation is involved in the pathogenesis of chronic kidney disease (CKD). Allopurinol (ALLO) inhibits xanthine oxidase (XOD) activity, and, consequently, reduces the production of uric acid (UA) and reactive oxygen species (ROS), both of which can activate the NLRP3 pathway. Thus, ALLO can contribute to slow the progression of CKD. We investigated whether inhibition of XOD by ALLO reduces NLRP3 activation and renal injury in the 5/6 renal ablation (Nx) model. Adult male Munich–Wistar rats underwent Nx and were subdivided into the following two groups: Nx, receiving vehicle only, and Nx + ALLO, Nx rats given ALLO, 36 mg/Kg/day in drinking water. Rats undergoing sham operation were studied as controls (C). Sixty days after surgery, Nx rats exhibited marked albuminuria, creatinine retention, and hypertension, as well as glomerulosclerosis, tubular injury, and cortical interstitial expansion/inflammation/fibrosis. Such changes were accompanied by increased XOD activity and UA renal levels, associated with augmented heme oxigenase-1 and reduced superoxide dismutase-2 renal contents. Both the NF-κB and NLRP3 signaling pathways were activated in Nx. ALLO normalized both XOD activity and the parameters of oxidative stress. ALLO also attenuated hypertension and promoted selective tubulointerstitial protection, reducing urinary NGAL and cortical interstitial injury/inflammation. ALLO reduced renal NLRP3 activation, without interfering with the NF-κB pathway. These observations indicate that the tubulointerstitial antiinflammatory and antifibrotic effects of ALLO in the Nx model involve inhibition of the NLRP3 pathway, and reinforce the view that ALLO can contribute to arrest or slow the progression of CKD.

Methylene blue attenuates renal ischemia-reperfusion injury by negative regulation of NLRP3 signaling pathway.

To investigate the effect of methylene blue (MB) on renal ischemia-reperfusion (IR) injury in mice and its possible relevant mechanisms. A total of 30 male C57/BL6 mice aged 4 months old were randomly divided into the following three groups: Sham group (n=10), IR group (n=10), and MB group (n=10). Mice in MB group were treated with gavage continuously using methylene blue solution (dosage: 25 mg·kg-1·d-1) until they were 7 months old. Mice in the other two groups were administrated with the same amount of normal saline for gavage. After that, the abdomen of mice in Sham group was opened and closed, and bilateral renal pedicles of mice in IR group and MB group were occluded using a micro-artery clamp for 45 min for modeling. After modeling, the renal tissues and blood samples of mice were taken for detection. The levels of serum creatinine (Scr), blood urea nitrogen (BUN), and malondialdehyde (MDA), and activity of superoxide dismutase (SOD) in mice in each experimental group were detected and statistically analyzed, respectively. The degree of renal tubular necrosis in renal tissues of mice was observed under an optical microscope. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory factors [interleukin-1β (IL-1β), IL-18, IL-10 and transforming growth factor-β1 (TGF-β1)] in renal tissues of mice in each experimental group, followed by relevant statistical analyses. The expressions of relevant proteins [NACHT, LRR, and PYD domains-containing protein 3 (NLRP3), nuclear factor-κB (NF-κB), caspase-1, pro-IL-1β, and IL-1β] in renal tissues of mice in each experimental group were detected via Western blotting, and the gray value of each band was detected for statistical analysis. It was found in this experimental study that Scr and BUN levels in MB group were significantly lower than those in IR group, and the differences were statistically significant (p<0.05). Compared with that in IR group, the degree of renal tubular necrosis in MB group was significantly alleviated, and the difference was statistically significant (p<0.05). Compared with those in IR group, the levels of inflammatory factors (IL-1β and IL-18) in MB group were significantly decreased, but the levels of IL-10 and TGF-β1 in MB group were significantly increased, and the differences were statistically significant (p<0.05). Compared with those in IR group, the activity of SOD in MB group was increased significantly, but the level of MDA was decreased, and the differences were statistically significant (p<0.05). The protein expressions of NLRP3, NF-κB, caspase-1, and pro-IL-1β in MB group were decreased compared with those in IR group, but the expression of IL-1β in MB group was increased, and the differences were statistically significant (p<0.05). We showed that methylene blue can alleviate the apoptosis and inflammatory response induced by renal IR injury in mice, and its relevant mechanism may be related to the fact that methylene blue can negatively regulate NLRP3 signaling pathway.

Activation of dopamine D1 receptor decreased NLRP3-mediated inflammation in intracerebral hemorrhage mice

BackgroundInflammasomes are involved in diverse inflammatory diseases. Previous study reported that the neurotransmitter dopamine inhibited NLRP3 inflammasome activation via dopamine D1 receptor (DRD1). The present study aims to investigate the role of DRD1 on neuroinflammation in intracerebral hemorrhage (ICH) mice and the potential mechanism mediated by NLRP3 inhibition.MethodsOne hundred and six male CD-1 mice were subjected to intrastriatal injection of bacterial collagenase or PBS. A68930 (DRD1 specific agonist) was administered by subcutaneous injection at 1 h after collagenase injection. Behavioral deficits and brain water content were assayed. The expression of Iba 1 and MPO levels were measured by immunofluorescence staining. The expressions of proteins in the DRD1/interferon-beta (IFN-beta)/NLRP3 signaling pathway were evaluated by western blotting.ResultsActivation of the DRD1 by A68930 decreased brain edema and improved behavior at 24 and 72 h of ICH. A68930 inhibited partly the activation of microglia and the neutrophil infiltration after 24 h of ICH. IFN-beta, p-STAT1 increased while NLRP3, caspase 1, and IL-1beta decreased after A68930 administration in ICH mice. DRD1 antagonist and IFN-beta siRNA reversed effects of A68930 on neurological outcome and brain edema. DRD1 antagonist and IFN-beta siRNA blocked not only A68930-mediated increases of IFN-beta, p-STAT1 but also A68930-mediated decreases of NLRP3, caspase 1, and IL-1beta.ConclusionsDRD1 activation by A68930 improves neurological outcome through inhibition of NLRP3-mediated inflammation in ICH mice.

WITHDRAWN: Cordycepin inhibits LPS-induced acute lung injury by inhibiting inflammatory response

// Xian Jiang 1 , Zhuo Zhang 2 , Fang Wang 3 , Siwei Chen 4 , Xiaobin Wang 1 and Jicheng Wei 1 1 Department of anesthesiology, The Affiliated Hospital of College of pharmacy, Southwest medical university, Luzhou, Sichuan, China 2 Laboratory of pharmacology, College of pharmacy, Southwest medical university, Luzhou, Sichuan, China 3 Laboratory of Pharmaceutics, College of pharmacy, Southwest medical university, Luzhou, Sichuan, China 4 Laboratory of Science of Chinese Pharmacology, College of pharmacy, Southwest medical university, Luzhou, Sichuan, China Correspondence: Jicheng Wei, email: jichengwei8383_88@yeah.net Keywords : cordycepin; LPS; lung injury; NLRP3; NF-κB Received: August 23, 2017 Accepted: December 16, 2017 Epub: January 01, 2018 Abstract Inflammatory response has been reported to play an important role in the development of acute lung injury (ALI). Cordycepin is known to have several pharmaceutical effects, including anti-antioxidant, and anti-inflammation. But no reported on the effect of Cordycepin on ALI. The present study was aimed to measure the protective effect of cordycepin on lipopolysaccharide (LPS)-induced ALI in mice. The mice were treated with cordycepin 1 h before LPS stimulation. 7 h later, the bronchial alveolar lavage fluid (BALF) was collected to measure the levels of inflammatory cells and inflammatory cytokines. The lung tissues were collected to test the lung pathological changes, wet/dry radio, myeloperoxidase (MPO) activity and the expression of NF-κB and NLRP3 signaling pathways. The results showed that cordycepin significantly inhibited the TNF-α, IL-1β, IL-6 production, the total cells, neutrophils, and macrophages numbers in BALF, and suppressed the pathological changes, wet/ dry radio, and MPO activity in lung tissues that induced by LPS. For further research the protect mechanism of cordycepin on ALI, we found that cordycepin inhibited the activation of NF-κB and NLRP3 signaling pathways in LPS-induced ALI in mice. In conclusion, the results suggested that cordycepin inhibited LPS-induced inflammatory response through modulating NF-κB and NLRP3 signaling, and cordycepin may be an effective treatment to cure ALI.

Protective effect of baicalin against severe burn‑induced remote acute lung injury in rats.

Baicalin exhibits antibacterial, anti‑viral, anti‑oxidative, antipyretic, analgesic, anti‑inflammatory and anti‑tumor properties. The chemical scavenges oxygen free radicals, protects the cardiovascular system and neurons, protects the liver, and has been used for the prevention and treatment of diabetes‑associated complications. The present study investigated the effect of baicalin on severe burn‑induced remote acute lung injury (ALI). The present study demonstrated that baicalin significantly decreased the lung wet‑to‑dry weight ratio, improved pulmonary histological alterations and reduced the expression of high mobility group protein B1 in the rat model of ALI. In addition, treatment with baicalin decreased tumor necrosis factor‑α, interleukin (IL)‑8, IL‑1β and IL‑18 concentrations in the serum, reduced myeloperoxidase activity and malondialdehyde content, and increased the level of superoxide dismutase in the serum in treated model rats with ALI. As a result, baicalin significantly suppressed nucleotide‑binding oligomerization, NACHT, LRR and PYD domains‑containing protein 3 (NLRP3), caspase‑1, nuclear factor‑κB and matrix metalloproteinase‑9 protein expression in the rat model of ALI. The results of the present study suggested that baicalin may serve a protective role against ALI in rats through the NLRP3 signaling pathway.

Saikosaponin a Ameliorates LPS-Induced Acute Lung Injury in Mice.

The purpose of this study was to investigate the protective effects of Saikosaponin a (SSa), a triterpene saponin derived from Radix bupleuri, on lipopolysaccharide (LPS)-induced acute lung injury (ALI) using a murine model. The mice were given SSa 1h after intranasal instillation of LPS. Then, lung histopathological examination, the wet/dry (W/D) ratio, myeloperoxidase (MPO), and inflammatory cytokines in bronchoalveolar lavage fluid (BALF) were detected in this study. The results showed that SSa reduced lung pathological injury induced by LPS. Furthermore, LPS-induced lung W/D ratio, MPO activity, and inflammatory cytokines TNF-α and IL-1β in BALF were significantly inhibited by SSa. In addition, SSa suppressed LPS-induced NF-κB activation and NLRP3 inflammasome expression. In conclusion, we found that SSa played a critical anti-inflammatory effect through inhibition of NF-κB and NLRP3 signaling pathways and protected against LPS-induced ALI.

Downregulated NLRP3 and NLRP1 inflammasomes signaling pathways in the development and progression of type 1 diabetes mellitus

BackgroundNLRP3 and NLRP1 inflammasomes signaling pathways may play an important role in the development and progression of type 1 diabetes mellitus (T1DM). However, relative research is rare. MethodsThe blood mononuclear cells (PBMCs) and granulocytes (GCs) were collected from T1DM patients. The mRNA and protein expression levels were detected by qRT-PCR and Western blotting, respectively. The NLRP3/NLRP1was knocked down by transfected with siRNA, or ovexpressed by infected with lentiviral vectors in PBMCs and GCs from non obese diabetic (NOD) mice, respectively. The occurrence of diabetes was evaluated and the intraperitoneal glucose tolerance was tested in NOD mice with IL-1 receptor-associated kinase-M deficiency (IRAK-M−/−). The pancreas and lymphonodus of IRAK-M−/− NOD mice were also collected for detection of NLRP3/NLRP1 expression. ResultsNLRP3, NLRP1, Caspase-1and IL-1β were significantly downregulated in the PBMCs and GCs of patients with T1DM, and NLRP3 and NLRP1 were markedly downregulated in T1DM patients with DKA compared to that with ND and CC. Further study indicated that IL-1β mRNA expression level was positively correlated with the expression levels of NLRP3, NLRP1 and Caspase-1. Besides, NLRP3/NLRP1 knockdown decreased the expression levels of Caspase-1 and IL-1β; whereas NLRP3/NLRP1 overexpression increased the expression levels of Caspase-1 and IL-1β in vitro. IRAK-M−/− NOD mice had early onset and rapid progression of T1DM, and weak glucose tolerance, which was regarded as an early T1D mouse model. The mRNA expression levels of NLRP3, NLRP1, Caspase-1and IL-1β in the pancreas and lymphonodus of IRAK-M−/− NOD mice were significantly higher compared to that of IRAK-M+/+ NOD mice. ConclusionNLRP3 and NLRP1 inflammasomes signaling pathways were associated with the development and progression of T1DM, which response as protective factors in the early stage of T1DM.

Therapeutic effects of silibinin on LPS-induced acute lung injury by inhibiting NLRP3 and NF-κB signaling pathways.

Silibinin, a natural product extracted from Silybum marianum (milk thistle), has been reported to have anti-inflammatory effect. The aim of this study was to explore the therapeutic effects and potential mechanisms of silibinin on lipopolysaccharide (LPS)-stimulated inflammatory responses in acute lung injury (ALI). Male BALB/c mice were conditioned with silibinin 1h after intranasal instillation of LPS. After 12h, the myeloperoxidase (MPO) level in lung tissues, the wet/dry (W/D) ratio, inflammatory cytokines in the bronchoalveolar lavage fluid (BALF), and histopathological examination of lung were detected. Our results showed that silibinin inhibited LPS-induced histopathological changes and MPO activity, as well as the wet/dry (W/D) ratio in the lung tissues. Furthermore, silibinin significantly inhibited LPS-induced inflammatory cytokines production in the BALF. In addition, silibinin suppressed LPS-induced NF-κB activation and the expression of NLRP3 inflammasome. These results indicate that silibinin exerts its anti-inflammatory effect by inhibiting NF-κB and NLRP3 signaling pathways.

Anti-inflammatory effect of cinnamaldehyde and linalool from the leaf essential oil of Cinnamomum osmophloeum Kanehira in endotoxin-induced mice

Cinnamomum osmophloeum Kanehira is a Taiwan native plant that belongs to genus Cinnamomum and is also known as pseudocinnamomum or indigenous cinnamon. Its leaf is traditionally used by local people in cooking and as folk therapy. We previously demonstrated the chemical composition and anti-inflammatory effect of leaf essential oil of Cinnamomum osmophloeum Kanehira of linalool chemotype in streptozotocin-induced diabetic rats and on endotoxin-injected mice. The aim of the present study is to evaluate whether cinnamaldehyde and linalool the active anti-inflammatory compounds in leaf essential oil of Cinnamomum osmophloeum Kanehira. Before the injection of endotoxin, C57BL/6 mice of the experimental groups were administered cinnamaldehyde (0.45 or 0.9 mg/kg body weight) or linalool (2.6 or 5.2 mg/kg body weight), mice of the positive control group were administered the leaf essential oil (13 mg/kg body weight), and mice of the negative group were administered vehicle (corn oil, 4 mL/kg body weight) by gavage every other day for two weeks. All mice received endotoxin (i.p. 10 mg/mL/kg body weight) the next day after the final administration and were killed 12 h after the injection. Normal control mice were pretreated with vehicle followed by the injection with saline. None of the treatment found to affect body weight or food or water intake of mice before the injection of endotoxin. Cinnamaldehyde and linalool were found significantly reversed endotoxin-induced body weight loss and lymphoid organ enlargement compared with vehicle (P < 0.05). Both compounds also significantly lowered endotoxin-induced levels of peripheral nitrate/nitrite, interleukin (IL)-1β, IL-18, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and High-mobility group box 1 protein (HMGB-1), and levels of nitrate/nitrite, IL-1β, TNF-α, and IFN-γ in spleen and mesenteric lymph nodes (MLNs) (P < 0.05). Endotoxin-induced expression of toll-like receptor 4 (TLR4), Myeloid differentiation primary response gene 88 (MyD88), myeloid differentiation protein 2 (MD2), Nod-like receptor family, pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), and caspase-1 in spleen and mesenteric lymph nodes (MLNs) were inhibited by all tested doses of cinnamaldehyde and linalool (P < 0.05). Subsequently, the activation of nuclear factor (NF)-κB and the activity of caspase-1 in spleen and MLNs were also suppressed by these two compounds (P < 0.05). In addition, cinnamaldehyde and linalool at the dose equivalent to their corresponding content in the tested dose of the leaf essential oil, which was 0.9 mg/kg and 5.2 mg/kg, respectively, showed similar or slightly less inhibitory activity for most of these inflammatory parameters compared with that of the leaf essential oil. Our data confirmed the potential use of leaf essential oil of Cinnamomum osmophloeum Kanehira as an anti-inflammatory natural product and provide evidence for cinnamaldehyde and linalool as two potent agents for prophylactic use in health problems associated with inflammations that being attributed to over-activated TLR4 and/or NLRP3 signaling pathways.

Protective Effect of Amygdalin on LPS-Induced Acute Lung Injury by Inhibiting NF-κB and NLRP3 Signaling Pathways.

The acute lung injury (ALI) is a leading cause of morbidity and mortality in critically ill patients. Amygdalin is derived from the bitter apricot kernel, an efficacious Chinese herbal medicine. Although amygdalin is used by many cancer patients as an antitumor agent, there is no report about the effect of amygdalin on acute lung injury. Here we explored the protective effect of amygdalin on ALI using lipopolysaccharide (LPS)-induced murine model by detecting the lung wet/dry ratio, the myeloperoxidase (MPO) in lung tissues, inflammatory cells in the bronchoalveolar lavage fluid (BALF), inflammatory cytokines production, as well as NLRP3 and NF-κB signaling pathways. The results showed that amygdalin significantly reduced LPS-induced infiltration of inflammatory cells and the production of TNF-α, IL-1β, and IL-6 in the BALF. The activity of MPO and lung wet/dry ratio were also attenuated by amygdalin. Furthermore, the western blotting analysis showed that amygdalin remarkably inhibited LPS-induced NF-κB and NLRP3 activation. These findings indicate that amygdalin has a protective effect on LPS-induced ALI in mice. The mechanism may be related to the inhibition of NF-κB and NLRP3 signaling pathways.

The protective effect of dopamine on ventilator-induced lung injury via the inhibition of NLRP3 inflammasome

Dopamine (DA), a neurotransmitter, was previously shown to have anti-inflammatory effects. However, its role in ventilator-induced lung injury (VILI) has not been explicitly demonstrated. This study aimed to investigate the therapeutic efficacy and molecular mechanisms of dopamine in VILI. Rats were treated with dopamine during mechanical ventilation. Afterwards, the influence of dopamine on histological changes, pulmonary edema, the lung wet/dry (W/D) ratio, myeloperoxidase (MPO) activity, polymorphonuclear(PMN)counts, inflammatory cytokine levels, and NLRP3 inflammasome protein expression were examined. Our results showed that dopamine significantly attenuated lung tissue injury, the lung W/D ratio, MPO activity and neutrophil infiltration. Moreover, it inhibited inflammatory cytokine levels in the Bronchoalveolar lavage fluid (BAL). In addition, dopamine significantly inhibited ventilation-induced NLRP3 activation. Our experimental findings demonstrate that dopamine exerted protective effects in VILI by alleviating the inflammatory response through inhibition of NLRP3 signaling pathways. The present study indicated that dopamine could be a potential effective therapeutic strategy for the treatment of VILI.

Mangiferin inhibits mastitis induced by LPS via suppressing NF-ĸB and NLRP3 signaling pathways

During the past era, small molecules derived from various plants have attracted extensive attention for their versatile medicinal benefits. Among these, one organic molecule called mangiferin from certain plant species including mangoes and honey bush tea is widely used in treating inflammation. In this study, a LPS-induced mastitis model in mouse is established to investigate the anti-inflammatory effects and mechanism of mangiferin. The result shows that mangiferin significantly alleviates LPS-induced histopathology, meanwhile, also decreases LPS-induced MPO activity. Furthermore, mangiferin treatment remarkably impeded the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. In addition, mangiferin was found to inhibit LPS-induced NF-ĸB and NLRP3 inflammasome activation. In conclusion, these results suggested that LPS-induced mastitis can be abated by mangiferin through inhibiting NF-ĸB and NLRP3 signaling pathways.

Rutin protects endothelial dysfunction by disturbing Nox4 and ROS-sensitive NLRP3 inflammasome.

High glucose induced endothelial dysfunction is blamed for initiation of vascular complication in Type 2 diabetes mellitus. Rutin has been described in possessing comprehensive pharmacological activities, but the mechanism involved in endothelial protection through regulating oxidative stress and damage is still ambiguous. In the present study, rutin was evaluated in high glucose stimulated human umbilical vein endothelial cells (HUVECs) and high glucose diet-treated SD rats were applied to explored the molecular mechanism in rutin counteracting oxidative stress and damage. Firstly, 30 and 100μM rutin effectively increased HUVECs viability in high glucose challenge. Then we found that rutin could dose-dependently reduced high glucose mediated mRNA and protein expressions of Nox4. With Nox4 and Nox2 inhibitors, we further confirm that Nox4, but not Nox2, was responsible for reactive oxygen species (ROS) production in high glucose environment. Moreover, rutin and Nox4 inhibitor significantly ameliorated ROS generation and TXNIP, NLRP3, caspase-1 and IL-1β proteins expression in vivo. Furthermore, rutin substantially recovered nitric oxide production in HUVECs under high glucose condition. However, rutin could not inhibited inflammasome protein expressions and improved nitric oxide production in Nox4-overexpressed HUVECs under high glucose challenges. Finally, we found that rutin restored phenylephrine-mediated contractions and acetylcholine induced relaxations in aortic tissue of high glucose diet treated rats. In vitro, expressions of TXNIP, NLRP3, and caspase-1 in aortic tissue of high glucose diet treated rats were decreased under rutin administration. In summary, rutin may protect endothelial dysfunction through inhibiting Nox4 responsive oxidative stress and ROS-sensitive NLRP3 signaling pathway under high glucose stress both in vivo and vitro.

Hyperin protects against LPS-induced acute kidney injury by inhibiting TLR4 and NLRP3 signaling pathways.

Hyperin is a flavonoid compound derived from Ericaceae, Guttifera, and Celastraceae that has been shown to have various biological effects, such as anti-inflammatory and anti-oxidant effects. However, there is no evidence to show the protective effects of hyperin on lipopolysaccharide (LPS)-induced acute kidney injury (AKI). Therefore, we investigated the protective effects and mechanism of hyperin on LPS-induced AKI in mice. The levels of TNF-α, IL-6, and IL-1β were tested by ELISA. The effects of hyperin on blood urea nitrogen (BUN) and serum creatinine were also detected. In addition, the expression of TLR4, NF-κB, and NLRP3 were detected by western blot analysis. The results showed that hyperin significantly inhibited LPS-induced TNF-α, IL-6, and IL-1β production. The levels of BUN and creatinine were also suppressed by hyperin. Furthermore, LPS-induced TLR4 expression and NF-κB activation were also inhibited by hyperin. In addition, treatment of hyperin dose-dependently inhibited LPS-induced NLRP3 signaling pathway. In conclusion, the results showed that hyperin inhibited LPS-induced inflammatory response by inhibiting TLR4 and NLRP3 signaling pathways. Hyperin has potential application prospects in the treatment of sepsis-induced AKI.

Coxiella burnetii Avirulent Nine Mile Phase II Induces Caspase-1-Dependent Pyroptosis in Murine Peritoneal B1a B Cells.

Our recent study demonstrated that virulent Coxiella burnetii Nine Mile phase I (NMI) is capable of infecting and replicating within peritoneal B1a cells and that B1a cells play an important role in host defense against C. burnetii infection in mice. However, it remains unknown if avirulent Nine Mile phase II (NMII) can infect and replicate in B1a cells and whether NMI and NMII can differentially interact with B1a cells. In this study, we examined if NMI and NMII can differentially modulate host cell apoptotic signaling in B1a cells. The results showed that NMII induced dose-dependent cell death in murine peritoneal B1a cells but NMI did not, suggesting that NMI and NMII may differentially activate host cell apoptotic signaling in B1a cells. Western blotting indicated that NMII-induced B1a cell death was not dependent on either caspase-3 or PARP-1 cleavage, but cleavage of caspase-1 was detected in NMII-infected B1a cells. In addition, inhibition or deficiency of caspase-1 activity blocked NMII-induced B1a cell death. These results suggest that NMII induces a caspase-1-dependent pyroptosis in murine peritoneal B1a cells. We also found that heat-killed NMII and type 4 secretion system (T4SS) mutant NMII were unable to induce B1a cell death and that NMII infection did not induce cell death in peritoneal B1a cells from Toll-like receptor 2 (TLR-2)- or NLRP3 inflammasome-deficient mice. These data suggest that NMII-induced caspase-1-dependent pyroptosis may require its T4SS and activation of the TLR-2 and NLRP3 signaling pathways.

Casticin inhibits lipopolysaccharide-induced acute lung injury in mice

Casticin, an active compound isolated from Vitex Fructus, has been reported to have anti-inflammatory effects in previous studies. The present study was designed to evaluate the protective effects of casticin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and clarify the underlying mechanisms. ALI was induced by intratracheal instillation of LPS. Casticin was administrated 1h before or after LPS challenge. The results showed that casticin decreased LPS-induced lung histopathological changes, MPO activity, and lung wet/dry weight ratio. Casticin also inhibited the numbers of inflammatory cells and the levels of inflammatory cytokines TNF-α, IL-6, and IL-1β production. Furthermore, casticin suppressed LPS-induced NF-κB activation, and NLRP3, ASC, and caspase-1 expression. In conclusion, the results suggested that casticin had a protective effect against LPS-induced ALI. Casticin protected against LPS-induced ALI by inhibiting inflammatory cytokines production through the inhibition of NF-κB and NLRP3 signaling pathways.