Aspartate Metabolism Facilitates IL-1ß Production in Inflammatory Macrophages.

Increasing evidence support that cellular amino acid metabolism shapes the fate of immune cells; however, whether aspartate metabolism dictates macrophage function is still enigmatic. Here, we found that the metabolites in aspartate metabolism are depleted in lipopolysaccharide (LPS) plus interferon gamma (IFN-γ)-stimulated macrophages. Aspartate promotes interleukin-1ß (IL-1ß) secretion in M1 macrophages. Mechanistically, aspartate boosts the activation of hypoxia-inducible factor-1α (HIF-1α) and inflammasome and increases the levels of metabolites in aspartate metabolism, such as asparagine. Interestingly, asparagine also accelerates the activation of cellular signaling pathways and promotes the production of inflammatory cytokines from macrophages. Moreover, aspartate supplementation augments the macrophage-mediated inflammatory responses in mice and piglets. These results uncover a previously uncharacterized role for aspartate metabolism in directing M1 macrophage polarization.

Xi Lei San Attenuates Dextran Sulfate Sodium-Induced Colitis in Rats and TNF-α-Stimulated Colitis in CACO2 Cells: Involvement of the NLRP3 Inflammasome and Autophagy.

OBJECTIVE: Inflammatory bowel disease (IBD) is a chronic nonspecific inflammatory bowel disease with an unclear etiology. The active ingredients of traditional Chinese medicines (TCMs) exert anti-inflammatory, antitumor, and immunomodulatory effects, and their multitarget characteristics provide them with a unique advantage for treating IBD. However, the therapeutic effects and underlying mechanisms of Xi Lei San in treatment of IBD remain unknown. This study was designed to investigate whether Xi Lei San exerted an anti-inflammatory effect in IBD via a mechanism involving NLRP3 inflammasomes and autophagy. METHODS: We successfully established a rat model of dextran sulfate sodium- (DSS-) induced colitis as well as a cellular model of TNF-α-induced colitis. Xi Lei San and indirubin were identified by HPLC analysis. Rats were treated with Xi Lei San or alum crystals, and their body weights and morphology of intestinal tissues were examined. A western blot analysis was performed to determine the expression levels of inflammasome-related proteins and autophagy-related proteins, ELISA was performed to analyze IL-1ß, IL-18, and IL-33 concentrations, and flow cytometry was used to monitor cell apoptosis and ROS levels. RESULTS: Xi Lei San and indirubin were identified by HPLC analysis. We found that Xi Lei San could significantly increase the weights of rats and improve the structure of the intestinal tissues in DSS-induced colitis model rats. We also found that Xi Lei San significantly inhibited NLRP3 inflammasome activity, reduced the levels of inflammatory cytokines, and suppressed autophagy in DSS-induced colitis model rats. In vitro experiments revealed that Xi Lei San could repress apoptosis as well as ROS and inflammatory cytokine production in TNF-α-induced CACO2 cells by reducing the activity of NLRP3 inflammasomes and autophagy. CONCLUSIONS: Our findings showed that Xi Lei San significantly ameliorated IBD by inhibiting NLRP3 inflammasome, autophagy, and oxidative stress.

Anti-inflammatory effects of Capparis ecuadorica extract in phthalic-anhydride-induced atopic dermatitis of IL-4/Luc/CNS-1 transgenic mice.

CONTEXT: The natural products derived from Capparis ecuadorica H.H. Iltis (Capparaceae) could have great potential for anti-inflammation since they inhibited the inflammatory response in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. OBJECT: This study investigated the anti-inflammatory effects and related mechanism of methanol extract of C. ecuadorica leaves (MCE) during atopic dermatitis (AD) responses. MATERIALS AND METHODS: Alterations in the phenotypical markers for AD, luciferase signal, iNOS-mediated COX-2 induction pathway, and inflammasome activation were analysed in non-Tg (n = 5) and 15% phthalic anhydride (PA) treated IL-4/Luc/CNS-1 transgenic (Tg) HR1 mice (n = 5 per group), subsequent to treatment with acetone-olive oil (AOO), vehicle (DMSO) and two dose MCE (20 and 40 mg/kg) three times a week for 4 weeks. RESULTS: MCE treatment reduced the intracellular ROS level (48.2%), NO concentration (7.1 mmol/L) and inflammatory cytokine expressions (39.1%) in the LPS-stimulated RAW264.7 cells. A significant decrease was detected for ear thickness (16.9%), weight of lymph node (0.7 mg), IgE concentration (1.9 µg/mL), and epidermal thickness (31.8%) of the PA + MCE treated Tg mice. MCE treatment induced the decrease of luciferase signal derived from the IL-4 promoter and the recovery of the IL-4 downstream regulator cytokines. PA + MCE treated Tg mice showed decreasing infiltration of mast cells (42.5%), iNOS-mediated COX-2 induction pathway, MAPK signalling pathway and inflammasome activation in the ear tissue. CONCLUSIONS: These findings provide the first evidence that MCE may have great potential to suppress chemical-induced skin inflammation through the suppression of IL-4 cytokine and the iNOS-mediated COX-2 induction pathway, and activation of inflammasome.

Can nutritional interventions modulate the activation of the NLRP3 inflammasome in chronic kidney disease?

Inflammatory and innate immune responses triggered by pathogen-associated and other danger-associated signals emerging during infections, results in the activation of cytosolic inflammasomes. The nod-like receptor pyrin domain containing 3 (NLRP3) is one of the inflammasomes mediating such responses through the activation of caspase-1, which increases the production and release of pro-inflammatory cytokines, such as IL-1ß and IL-18 and induces programmed cell death through pyroptosis. NLRP3 is thought to play a crucial role in the underlying inflammatory responses in many lifestyles related chronic diseases. Consequently, research on the NLRP3 inflammasome has expanded dramatically in recent years. Although several studies have investigated the role of NLRP3 activation in chronic kidney disease (CKD), few studies have evaluated strategies to modulate its activation by means of interventions using non-pharmacological strategies. This review discusses some nutritional strategies (bioactive compounds, probiotics and caloric restriction) that have been shown to influence NLRP3 in experimental models of renal disease, and in CKD. It discusses how nutritional interventions could potentially dampen NLRP3 associated inflammatory burden, as part of nutritional strategies to prevent and treat CKD and its complications.

Renoprotective effects of artemisinin and hydroxychloroquine combination therapy on IgA nephropathy via suppressing NF-κB signaling and NLRP3 inflammasome activation by exosomes in rats.

Immunoglobulin A nephropathy (IgAN) is an autoimmune kidney disease with complex pathogenesis leading to end-stage renal damage. The prime pathological characteristics of IgAN are IgA immune complexes deposition accompany with mesangial cell proliferation and urine protein elevation. Artemisinin (ART) is extracted from traditional Chinese medicine Artemisia annua L. Hydroxychloroquine (HCQ) is a classical antimalarial drug applied in the treatment of autoimmune diseases. Both of them possess anti-inflammatory and immunomodulatory properties. The purpose of this research was to investigate the pharmacological effects of ART combined with HCQ (AH) and discuss thoroughly the potential molecular mechanisms in IgAN. In vivo, our results demonstrated that AH could efficiently ameliorate kidney damage by improving kidney dysfunction and reducing the levels of 24 h urine protein, IgA and IgG immune complexes deposition in glomerulus of IgAN rats. Interestingly, AH obviously promoted the secretion of exosomes in renal tissues, inhibited the expressions of nuclear factor-κB (NF-κB) signaling and NLRP3 inflammasome-related proteins, including IκB-α, p-p65, NLRP3, ASC, IL-1ß and caspase-1 in IgAN rats. In vitro, further mechanistic study illustrated that exosomes derived from human renal tubular epithelial cells (HK-2) were significantly enhanced by AH, which could be utterly taken up in human mesangial cells (HMCs) and inhibited the activation of NF-κB pathway and NLRP3 inflammasome after AH intervention. However, GW4869 interdicted the promotive effect of AH on exosomes from HK-2 cells and the suppression of exosomes on NF-κB/NLRP3 activation in HMCs. Taken together, this study demonstrated that there was an inhibitory effect of AH therapy on NF-κB/NLRP3 signaling via mediating exosomes release in IgAN rats, which provided an alternative approach for IgAN treatment.

Inflammasome as a promising therapeutic target for cancer.

Inflammasomes are the major mechanistic complexes that include members of the NOD-like receptor (NLRs) or AIM2-like receptors (ALRs) families, which are affiliated with the innate immune system. Once NLRs or ALRs are activated by pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs), the caspase-1 or -11 is activated by binding with NLRs or ALRs via its own unique cytosolic domains. As a result, caspase-1 or -11 enhances the production of IL-1ß and IL-18, which results in inflammation via the recruitment of immune cells, such as macrophages, and the promotion of programmed cell death mechanisms such as pyroptosis. In addition, the consistent cascades of inflammasomes would precede both minor and severe autoimmune diseases and cancers. The clinical relevance of inflammasomes in multiple forms of cancer highlights their therapeutic promise as molecular targets. To closely analyze the physiological roles of inflammasomes in cancers, here, we describe the fundamental knowledge regarding the current issues of inflammasomes in relevant cancers, and discuss possible therapeutic values in targeting these inflammasomes for the prevention and treatment of cancer.

Pharmacological Effects and Mechanisms of Chinese Medicines Modulating NLRP3 Inflammasomes in Ischemic Cardio/Cerebral Vascular Disease.

Cardio/cerebral-vascular diseases seriously threaten human health and are the leading cause of death. As such, there is great interest in identifying a potential mechanism that controls the development process of cardio/cerebral vascular diseases. Present studies demonstrate that inflammasomes play an important role in the process of ischemic cardio/cerebral vascular diseases (ICCVDs). Among the pathological process of ICCVDs, inflammasomes activated the sterile inflammatory response that accelerated the development of diseases and aggravated the acute lesion of tissue. As the most thoroughly studied inflammasome, the NLRP3 inflammasome has been proven to be a potential therapeutic target for ICCVDs. In this review, we summarized the mechanisms of Chinese herbal medicine which can affect ICCVDs via the regulation of the NLRP3 inflammasome. Our study discovers that active compounds of Chinese medicines have a negative effect on NLRP3 in different ICCVDs models. Astragaloside IV may influence the receptor of the cell membrane to inhibit NLRP3 activation. Resveratrol, colchicinesis, salvianolic acid B, chrysophanol and sulforaphane may directly damage the formation of NLRP3 by inhibiting ASC or Caspase-1. Most of the active natural compounds can negatively regulate the downstream products of NLRP3 inflammasome such as IL-18 and IL1 ß . In addition, Chinese medicines such as sinomenine, ruscogenin, resveratrol, arctigenin and cepharanthineas may downregulate NLRP3 inflammasome by inducing autophagy activation. Due to the advantages of multi-target effects, Chinese herbal medicine can be treated as a splendid therapy for ICCVDs by inhibiting NLRP3 inflammasome.

The role of NLRP3 inflammasome in stroke and central poststroke pain.

BACKGROUND: NLRP3 inflammasome plays a prominent role in the pathogenesis and progression of many diseases, such as type 2 diabetes mellitus, obesity, atherosclerosis, and Alzheimer's disease. However, little knowledge is known about the role of NLRP3 inflammasome in central post-stroke pain (CPSP). METHODS: We selected relevant studies by searching PubMed, Embase, and Medline from inception through February, 2018. We systematically reviewed available publications according to the terms "NLRP3 inflammasome" and "stroke" or "central post-stroke pain" in the title/abstract field. RESULTS: We reviewed the articles and put forward two possible ways for NLRP3 inflammasome in CPSP. One way is that NLRP3 activation causes cerebral cortex injure, decreasing descending projection fiber to thalamus. Such condition may let GABAergic releases reduce, making the ventral basal (VB) neurons excitability increased. Finally, CPSP occur. Another way is that NLRP3 inflammasome leads to thalamic lesion and strengthens inflammatory response of microglia at the same time. Persistent inflammation causes GABAergic alteration in thalamus reticular neurons (TRN) to restrain VB interneurons functions, contributing to CPSP. CONCLUSIONS: These possible mechanisms will help become knowledgeable about the occurrence CPSP and provide potential therapy for CPSP.

Involvement of NLRP3 inflammasome in the impacts of sodium and potassium on insulin resistance in normotensive Asians.

Salt, promoting oxidative stress, contributes to insulin resistance, whereas K, inhibiting oxidative stress, improves insulin sensitivity. Oxidative stress activation of NLRP3 inflammasome is a central player in the induction of insulin resistance. Therefore, we hypothesised that NLRP3 inflammasome may mediate the effects of salt and K on insulin resistance. In all, fifty normotensive subjects were recruited from a rural community of Northern China. The protocol included a low-salt diet for 7 d, then a high-salt diet for 7 d and a high-salt diet with K supplementation for another 7 d. In addition, THP-1 cells were cultured in different levels of Na with and without K. The results showed that salt loading elevated fasting blood glucose, insulin and C-peptide levels, as well as insulin resistance, whereas K supplementation reversed them. Meanwhile, additional K reversed the active effects of high salt on NLRP3 inflammasome in both the subjects and THP-1 cells, and the change of insulin resistance index notably related with the alteration of plasma IL-1ß, the index of NLRP3 inflammasome activation, during intervention in the subjects. Additional K ameliorated oxidative stress induced by high salt in both the subjects and cultured THP-1 cells, and the change of oxidative stress related with the alteration of plasma IL-1ß during intervention in the subjects. In vitro, antioxidant N-acetyl-l-cysteine significantly prevented the active effects of high Na or oxidant Rosup on NLRP3 inflammasome, so did K. Our study indicates that oxidative stress modulation of NLRP3 inflammasome may be involved in the impacts of Na and K on insulin resistance.

Beneficial Properties of Phytochemicals on NLRP3 Inflammasome-Mediated Gout and Complication.

Gouty arthritis is characterized by the precipitation of monosodium urate (MSU) crystals in the joint. Pro-inflammatory cytokine IL-1ß is a critical manifestation in response to MSU crystals attack. IL-1ß secretion is dependent on the nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) inflammasome. Abnormal activation of the NLRP inflammasome is related to cellular oxidative stress. However, recent studies have illustrated that phytochemicals with potent antioxidant activity exert inhibitory effects on NLRP3 inflammasome-mediated diseases. This review focuses on the current findings of studies on the NLRP3 inflammasome and the proposed mechanisms that MSU crystals trigger inflammation via activation of the NLRP3 inflammasome. We also summarized the potential use of phytochemicals on NLRP3 inflammasome-mediated diseases, suggesting that phytochemicals can further prevent acute gout attack.

BAY 11-7082 inhibits the NF-κB and NLRP3 inflammasome pathways and protects against IMQ-induced psoriasis.

BAY 11-7082 antagonizes I-κB kinase-ß preventing nuclear translocation of nuclear factor-κB (NF-κB); it also inhibits NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation. NF-κB is involved in psoriasis, whereas the role of NLRP3 is controversial. We investigated BAY 11-7082 effects in an experimental model of psoriasis-like dermatitis. Psoriasis-like lesions were induced by a topical application of imiquimod (IMQ) cream (62.5 mg/day) on the shaved back skin of C57BL/6 and NLRP3 knockout (KO) mice for 7 consecutive days. Sham psoriasis animals were challenged with Vaseline cream. Sham and IMQ animals were randomized to receive BAY 11-7082 (20 mg/kg/i.p.) or its vehicle (100 µl/i.p of 0.9% NaCl). Skin of IMQ animals developed erythema, scales, thickening and epidermal acanthosis. IMQ skin samples showed increased expression of pNF-κB and NLRP3 activation. BAY 11-7082 blunted epidermal thickness, acanthosis and inflammatory infiltrate. BAY 11-7082 reduced pNF-κB, NLRP3, tumour necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1ß expression, blunted the phosphorylation of signal transducer and activators of transcription 3 (STAT3) and decreased IL-23 levels. In addition, BAY 11-7082 reawakened the apoptotic machinery. NLRP3 KO animals showed a reduced total histological score but persistent mild acanthosis, dermal thickness and expression of pNF-κB and pSTAT3, following IMQ application. Our data suggest that BAY 11-7082 might represent an interesting approach for the management of psoriasis-like dermatitis depending on the dual inhibition of NF-κB and NLRP3.

Effects of Hyperbaric Oxygen Therapy on Inflammasome Signaling after Traumatic Brain Injury.

OBJECTIVE: Neuroinflammation plays an important role in secondary tissue damage after traumatic brain injury (TBI). Recently, the inflammasome-mediated inflammatory pathway has been observed in the inflammatory response of TBI. In this study, we investigated the influence of hyperbaric oxygen therapy (HBOT) on inflammasome activation after TBI. METHODS: The experimental mice were randomly divided into 4 groups as follows: sham-operated normobaric air (21% O2 at one absolute atmosphere), HBOT only, TBI + normobaric air and TBI + HBOT. Following the evaluation of motor deficits and brain edema, the expression of inflammasome components and effectors was measured by qRT-PCR and Western blotting. Moreover, alterations in IL-1ß, IL-18 and high-mobility group box 1 (HMGB1) were calculated by enzyme-linked immunosorbent assay at each time point after injury. RESULTS: HBOT improved motor score and reduced brain edema. Furthermore, it suppressed protein expression of inflammasome components and reduced the levels of IL-1ß and IL-18, accompanied by the reduction of HMGB1 in brain tissues and serum. CONCLUSION: These results suggest that HBOT may alleviate the inflammatory response after TBI by inhibiting the activation of inflammasome signaling.

Evidences of the inflammasome pathway in chronic prostatitis and chronic pelvic pain syndrome in an animal model.

BACKGROUND: The mechanism of non-bacterial chronic prostatitis (CP/CPPS) has long been investigated but remains unclear. Under the hypothesis that abnormal response of innate immunity may be a cause of CP/CPPS, this study evaluated inflammasome, as part of innate immunity, and its effects on persist inflammation and CP/CPPS. METHODS: Carrageenan was used to induce CP/CPPS in a rat animal model. After confirming tactile hyper-algesia in the rats, their local prostate inflammation status, and inflammasome expression were determined. The amount of inflammasome and its downstream protein was checked, along with prostate localization. Chlorogenic acid (CHA), an active ingredient of Chinese herbal remedy for CP/CPPS treatment, was used as treatment. RESULTS: The rats had CP/CPPS once scrotal static tactile allodynia developed and CHA treatment relieved the scrotal hypersensitivity. Downstream inflammasome proteins like IL-1ß and caspase 1 increased within the prostate and decreased with CHA treatment. Inflammasome, NALP1 but not NALP3, was significantly increased in the prostate glandular endothelial cells. Treatment with CHA also changed the distribution pattern of NALP1 in the prostate. CONCLUSIONS: There is a close relationship between activation of inflammasome and patho-physiologic changes of CP/CPSS in rats. Increased inflammasome may be a possible mechanism of CP/CPPS and clinically active regimen may inhibit the inflammasome-related pathway. This provides a new therapeutic rationale and approach for CP/CPPS treatment.

Multifunctional targets of dietary polyphenols in disease: a case for the chemokine network and energy metabolism.

Chronic, non-acute inflammation is behind conditions that represent most of the disease burden in humans and is clearly linked to immune and metabolic mechanisms. The convergence of pathways involving the immune response, oxidative stress, increased circulating lipids and aberrant insulin signaling results in CCL2-associated macrophage recruitment and altered energy metabolism. The CCL2/CCR2 pathway and the energy sensor AMP-activated protein kinase (AMPK) are attractive therapeutic targets as a part of preventive management of disease. Several effects of polyphenols are useful in this scenario, including a reduction in the activities of cytokines and modulation of cellular metabolism through histone deacetylase inhibitors, AMPK activators, calorie-restriction mimetics or epigenetic regulators. Research is currently underway to develop orally active drugs with these effects, but it is convenient to examine more closely what we are eating. If a lack of relevance in terms of toxicity and substantial effectiveness are confirmed, plant-derived components may provide useful druggable components and dietary supplements. We consider therapeutic actions as a combination of synergistic and/or antagonistic interactions in a multi-target strategy. Hence, improvement in food through enrichment with polyphenols with demonstrated activity may represent a major advance in the design of diets with both industrial and sanitary value.

IL-1 receptor antagonist ameliorates inflammasome-dependent alcoholic steatohepatitis in mice.

Alcoholic liver disease (ALD) is characterized by steatosis and upregulation of proinflammatory cytokines, including IL-1ß. IL-1ß, type I IL-1 receptor (IL-1R1), and IL-1 receptor antagonist (IL-1Ra) are all important regulators of the IL-1 signaling complex, which plays a role in inflammation. Furthermore, IL-1ß maturation is dependent on caspase-1 (Casp-1). Using IL-1Ra-treated mice as well as 3 mouse models deficient in regulators of IL-1ß activation (Casp-1 and ASC) or signaling (IL-1R1), we found that IL-1ß signaling is required for the development of alcohol-induced liver steatosis, inflammation, and injury. Increased IL-1ß was due to upregulation of Casp-1 activity and inflammasome activation. The pathogenic role of IL-1 signaling in ALD was attributable to the activation of the inflammasome in BM-derived Kupffer cells. Importantly, in vivo intervention with a recombinant IL-1Ra blocked IL-1 signaling and markedly attenuated alcohol-induced liver inflammation, steatosis, and damage. Furthermore, physiological doses of IL-1ß induced steatosis, increased the inflammatory and prosteatotic chemokine MCP-1 in hepatocytes, and augmented TLR4-dependent upregulation of inflammatory signaling in macrophages. In conclusion, we demonstrated that Casp-1-dependent upregulation of IL-1ß and signaling mediated by IL-1R1 are crucial in ALD pathogenesis. Our findings suggest a potential role of IL-1R1 inhibition in the treatment of ALD.

Cathelicidin LL-37: a defense molecule with a potential role in psoriasis pathogenesis.

Epidermal keratinocytes produce and secrete antimicrobial peptides (AMPs) that subsequently form a chemical shield on the skin surface. Cathelicidins are one family of AMPs in skin with various further immune functions. Consequently, dysfunction of these peptides has been implicated in the pathogenesis of inflammatory skin disease. In particular, the cathelicidin LL-37 is overexpressed in inflamed skin in psoriasis, binds to extracellular self-DNA released from dying cells and converts self-DNA in a potent stimulus for plasmacytoid dendritic cells (pDCs). Subsequently, pDCs secrete type I interferons and trigger an auto-inflammatory cascade. Paradoxically, therapies targeting the vitamin D pathway such as vitamin D analogues or UVB phototherapy ameliorate cutaneous inflammation in psoriasis but strongly induce cathelicidin expression in skin at the same time. Current evidence now suggests that self-DNA present in the cytosol of keratinocytes is also pro-inflammatory active and triggers IL-1ß secretion in psoriatic lesions through the AIM2 inflammasome. This time, however, binding of LL-37 to self-DNA neutralizes DNA-mediated inflammation. Hence, cathelicidin LL-37 shows contrasting roles in skin inflammation in psoriasis and might serve as a target for novel therapies for this chronic skin disease.

Metabolic stress boosts humoral responses in vivo independently of inflammasome and inflammatory reaction.

Adjuvant formulations boost humoral responses by acting through several, yet incompletely elucidated pathways. In this study, we show that oligomycin or 5-aminoimidazole-4-carboxamide-1-ß-D-ribonucleoside (AICAR) enhances Ab production when coinjected with T cell-dependent Ags. Oligomycin and AICAR lead to intracellular ATP reduction, suggesting that metabolic stress could be sensed by immune cells and leads to increased humoral responses. AICAR promotes IL-4 and IL-21 by naive Th cells but does not affect dendritic cell activation/maturation in vitro or in vivo. Accordingly, the adjuvant effect of AICAR or oligomycin does not require MyD88 or caspase-1 expression in vivo. Because AICAR is well tolerated in humans, this compound could represent a novel and safe adjuvant promoting humoral responses in vivo with a minimal reactogenicity.