Anti-inflammatory effect of artemisinin on uric acid-induced NLRP3 inflammasome activation through blocking interaction between NLRP3 and NEK7

Neuroprotective effects and mechanisms of action of artemisinin in retinal ganglion cells in a mouse model of traumatic optic neuropathy

Introduction

Traumatic optic neuropathy is known to be a critical condition that can cause blindness; however, the specific mechanism underlying optic nerve injury is unclear. Recent studies have reported that artemisinin, considered vital in malaria treatment, can also be used to treat neurodegenerative diseases; however, its precise role and mechanism of action remain unknown. Therefore, in this study, we aimed to investigate the impact and probable mechanism of action of artemisinin in retinal ganglion cells (RGCs) in a mouse model of traumatic optic neuropathy induced by optic nerve crush (ONC).

Methods

ONC was induced in the left eye of mice by short-term clamping of the optic nerve; oral artemisinin was administered daily. The neuroprotective effect of the drug was assessed using Tuj-1 staining in RGCs. In addition, the inflammatory response and the expression levels of phosphorylated tau protein and tau oligomers were observed using RT-qPCR, TUNEL assay, and fluorescence staining to investigate the underlying mechanisms.

Results

Artemisinin increased the survival rate of RGCs 14 days after ONC. Artemisinin significantly reduced the levels of inflammatory factors such as CXCL10, CXCR3, and IL-1β in the retina and decreased the apoptosis of RGCs. Moreover, downregulation of the phosphorylation of tau proteins and the expression of tau oligomers were observed after artemisinin treatment.

Conclusion

Our results suggest that artemisinin can increase the survival rate of RGCs after ONC and reduce their apoptosis. This effect may be achieved by inhibiting the inflammatory response it triggers and downregulating tau protein phosphorylation and tau oligomer expression. These findings suggest the potential application of artemisinin as a therapeutic agent for neuropathy.

SLC25A3 negatively regulates NLRP3 inflammasome activation by restricting the function of NLRP3

The NACHT, leucine-rich repeat, and pyrin domains-containing protein 3 (collectively known as NLRP3) inflammasome activation plays a critical role in innate immune and pathogenic microorganism infections. However, excessive activation of NLRP3 inflammasome will lead to cellular inflammation and tissue damage, and naturally it must be precisely controlled in the host. Here, we discovered that solute carrier family 25 member 3 (SLC25A3), a mitochondrial phosphate carrier protein, plays an important role in negatively regulating NLRP3 inflammasome activation. We found that SLC25A3 could interact with NLRP3, overexpression of SLC25A3 and knockdown of SLC25A3 could regulate NLRP3 inflammasome activation, and the interaction of NLRP3 and SLC25A3 is significantly boosted in the mitochondria when the NLRP3 inflammasome is activated. Our detailed investigation demonstrated that the interaction between NLRP3 and SLC25A3 disrupted the interaction of NLRP3-NEK7, promoted ubiquitination of NLRP3, and negatively regulated NLRP3 inflammasome activation. Thus, these findings uncovered a new regulatory mechanism of NLRP3 inflammasome activation, which provides a new perspective for the therapy of NLRP3 inflammasome-associated inflammatory diseases.

The landscape of pathophysiology guided therapeutic strategies for gout treatment

INTRODUCTION

Gout is a common autoinflammatory disease caused by hyperuricemia with acute and/or chronic inflammation as well as tissue damage. Currently, urate-lowering therapy (ULT) and anti-inflammatory therapy are used as first-line strategies for gout treatment. However, traditional drugs for gout treatment exhibit some unexpected side effects and are not suitable for certain patients due to their comorbidity with other chronic disease.

AREAS COVERED

In this review, we described the pathophysiology of hyperuricemia and monosodium urate (MSU) crystal induced inflammatory response during gout development in depth and comprehensively summarized the advances in the investigation of promising ULT drugs as well as anti-inflammatory drugs that might be safer and more effective for gout treatment.

EXPERT OPINION

New drugs that are developed based on these molecular mechanisms exhibited great efficacy on reduction of disease burden both in vitro and in vivo, implying their potential for clinical application. Moreover, hyperthermia also showed regulation effect on MSU crystals formation and the signaling pathways involved in inflammation.

The NLRP3 inflammasome: contributions to inflammation-related diseases

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines interleukin (IL)-1β and IL-18. Multiple studies have demonstrated the importance of the NLRP3 inflammasome in the development of immune and inflammation-related diseases, including arthritis, Alzheimer's disease, inflammatory bowel disease, and other autoimmune and autoinflammatory diseases. This review first explains the activation and regulatory mechanism of the NLRP3 inflammasome. Secondly, we focus on the role of the NLRP3 inflammasome in various inflammation-related diseases. Finally, we look forward to new methods for targeting the NLRP3 inflammasome to treat inflammation-related diseases, and provide new ideas for clinical treatment.

Role of NLRP3 in the pathogenesis and treatment of gout arthritis

Gout arthritis (GA) is a common and curable type of inflammatory arthritis that has been attributed to a combination of genetic, environmental and metabolic factors. Chronic deposition of monosodium urate (MSU) crystals in articular and periarticular spaces as well as subsequent activation of innate immune system in the condition of persistent hyperuricemia are the core mechanisms of GA. As is well known, drugs for GA therapy primarily consists of rapidly acting anti-inflammatory agents and life-long uric acid lowering agents, and their therapeutic outcomes are far from satisfactory. Although MSU crystals in articular cartilage detected by arthrosonography or in synovial fluid found by polarization microscopy are conclusive proofs for GA, the exact molecular mechanism of NLRP3 inflammasome activation in the course of GA still remains mysterious, severely restricting the early diagnosis and therapy of GA. On the one hand, the activation of Nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome requires nuclear factor kappa B (NF-κB)-dependent transcriptional enhancement of NLRP3, precursor (pro)-caspase-1 and pro-IL-1β, as well as the assembly of NLRP3 inflammasome complex and sustained release of inflammatory mediators and cytokines such as IL-1β, IL-18 and caspase-1. On the other hand, NLRP3 inflammasome activated by MSU crystals is particularly relevant to the initiation and progression of GA, and thus may represent a prospective diagnostic biomarker and therapeutic target. As a result, pharmacological inhibition of the assembly and activation of NLRP3 inflammasome may also be a promising avenue for GA therapy. Herein, we first introduced the functional role of NLRP3 inflammasome activation and relevant biological mechanisms in GA based on currently available evidence. Then, we systematically reviewed therapeutic strategies for targeting NLRP3 by potentially effective agents such as natural products, novel compounds and noncoding RNAs (ncRNAs) in the treatment of MSU-induced GA mouse models. In conclusion, our present review may have significant implications for the pathogenesis, diagnosis and therapy of GA.

Cornus officinalis Seed Extract Inhibits AIM2-Inflammasome Activation and Attenuates Imiquimod-Induced Psoriasis-like Skin Inflammation

The AIM2 inflammasome is an innate immune system component that defends against cytosolic bacteria and DNA viruses, but its aberrant activation can lead to the progression of various inflammatory diseases, including psoriasis. However, there have been few reports of specific inhibitors of AIM2 inflammasome activation. In this study, we aimed to investigate the inhibitory activity of ethanolic extracts of seeds of Cornus officinalis (CO), a herb and food plant used in traditional medicine, on AIM2-inflammasome activation. We found that CO inhibited the release of IL-1β induced by dsDNA in both BMDMs and HaCaT cells, but that it showed no effect on the release of IL-1β induced by NLRP3 inflammasome triggers, such as nigericin and silica, or the NLRC4 inflammasome trigger flagellin. Furthermore, we demonstrated that CO inhibited the cleavage of caspase-1, an inflammasome activation marker, and an upstream event, the translocation and speck formation of ASC. In addition, further experiments and mechanistic investigations revealed that CO can inhibit AIM2 speck formation induced by dsDNA in AIM2-overexpressing HEK293T cells. To verify the correlation in vivo, we investigated the efficacy of CO in an imiquimod (IMQ)-induced psoriasis model, which has reported associations with the AIM2 inflammasome. We found that topical application of CO alleviated psoriasis-like symptoms, such as erythema, scaling, and epidermal thickening, in a dose-dependent manner. Moreover, CO also significantly decreased IMQ-induced expression of AIM2 inflammasome components, including AIM2, ASC, and caspase-1, and led to the elevation of serum IL-17A. In conclusion, our results suggest that CO may be a valuable candidate for the discovery of AIM2 inhibitors and the regulation of AIM2-related diseases.

On the Need for Human Studies of PM Exposure Activation of the NLRP3 Inflammasome

Particulate matter air pollution is associated with blood inflammatory biomarkers, however, the biological pathways from exposure to periferal inflammation are not well understood. We propose that the NLRP3 inflammasome is likely stimulated by ambient particulate matter, as it is by some other particles and call for more research into this pathway.

Artemisinin analog SM934 alleviates epithelial barrier dysfunction via inhibiting apoptosis and caspase-1-mediated pyroptosis in experimental colitis

Intestinal barrier disruption due to the intestinal epithelial cells’ (IECs) death is one of the critical pathological features of inflammatory bowel diseases (IBDs). SM934, an artemisinin analog, has previously been proven to ameliorate colitis induced by dextran sulfate sodium (DSS) in mice by suppressing inflammation response. In this study, we investigated the protective effects of SM934 on the epithelial barrier and the underlying mechanism in trinitrobenzene sulfonic acid (TNBS)-induced colitis mice. We demonstrated that SM934 restored the body weight and colon length, and improved the intestine pathology. Furthermore, SM934 treatment preserved the intestinal barrier function via decreasing the intestinal permeability, maintaining epithelial tight junction (TJ) protein expressions, and preventing apoptosis of epithelial cells, which were observed both in the colon tissue and the tumor necrosis factor-α (TNF-α)-induced human colonic epithelial cell line HT-29. Specifically, SM934 reduced the pyroptosis of IECs exposed to pathogenic signaling and inhibited pyroptosis-related factors such as NOD-like receptor family pyrin domain containing 3 (NLRP3), adapter apoptosis-associated speck-like protein (ASC), cysteine protease-1 (caspase-1), gasdermin (GSDMD), interleukin-18 (IL-18), and high-mobility group box 1 (HMGB1) both in colon tissue and lipopolysaccharide (LPS) and adenosine triphosphate (ATP) co-stimulated HT-29 cells in vitro. Moreover, SM934 interdicted pyroptosis via blocking the transduction of mitogen-activated protein kinase (MAPK) and nuclear factor-kB (NF-kB) signaling pathways. In conclusion, SM934 protected TNBS-induced colitis against intestinal barrier disruption by inhibiting the apoptosis and pyroptosis of epithelial cells via the NLRP3/NF-κB/MAPK signal axis, and intestinal barrier protection in company with an anti-inflammatory strategy might yield greater benefits in IBD treatment.

NEK7: a new target for the treatment of multiple tumors and chronic inflammatory diseases

NIMA-related kinase 7 (NEK7) is a serine/threonine kinase, which is the smallest one in mammalian NEK family. At present, many studies have reported that NEK7 has a physiological role in regulating the cell cycle and promoting the mitotic process of cells. In recent years, an increasing number of studies have proposed that NEK7 is involved in the activation of the NLRP3 inflammasome. Under normal conditions, NEK7 is in a low activity state, while under pathological conditions, NEK7 is abnormally expressed and therefore plays a key role in the progression of multiple tumors and chronic inflammatory diseases. This review will concentrate on the mechanism of NEK7 participates in the process of mitosis and regulates the activation of NLRP3 inflammasome, the aberrant expression of NEK7 in a variety of tumors and chronic inflammatory diseases, and some potential inhibitors, which may provide some new ideas for the treatment of diverse tumors and chronic inflammatory diseases associated with NEK7.

Knockdown of NEK7 alleviates anterior cruciate ligament transection osteoarthritis (ACLT)-induced knee osteoarthritis in mice via inhibiting NLRP3 activation

Osteoarthritis is thought to be a NLRP3-related disease. NEK7 is an essential mediator for NLRP3 inflammasome activation. This study aimed to demonstrate whether NEK7 has regulatory roles in the pathogenesis of osteoarthritis. C57BL/6 mice were subjected to anterior cruciate ligament transection osteoarthritis (ACLT) for constructing animal models of osteoarthritis. Injection of adeno-associated virus (AAV) expressing NEK7-specific shRNA into the knee joints of mice, following of which immunohistochemistry, qRT-PCR, western blotting, Safranin-O Fast Green staining, ELISA, and co-immunoprecipitation were performed to determine the effects of NEK7. NEK7 was highly expressed in the joint tissues of ACLT mice. As compared with shScr, AAV delivery of NEK7 shRNA significantly inhibited cartilage degeneration, OARSI score, and serum CTX-II and COMP levels. AAV delivery of NEK7 shRNA downregulated the expression of matrix-degrading enzymes (ADAMTS-4, MMP3, and MMP13) and upregulated the expression of ECM-related molecules (SOX9, collagen II, and aggrecan). In addition, AAV delivery of NEK7 shRNA alleviated ACLT-induced synovial inflammation, as was evidenced by the decreased levels of TNF-α, IL-6, IL-1β, and IL-18 and increased levels of IL-10. In the joint tissues of ACLT mice, NEK7 interacted with NLRP3 proteins. AAV delivery of NEK7 shRNA inhibited the protein interaction, and thereby inhibited the activation of the NLRP3 inflammasome. AAV delivery of NEK7 shRNA has no significant effects on cartilage degeneration and synovial inflammation in Nlrp3^-/- mice. In conclusion, knockdown of NEK7 exerted anti-osteoarthritic effects, possibly via inhibiting the activation of the NLRP3 inflammasome. This study provided a novel mechanism of NEK7-NLRP3 interaction affecting osteoarthritis.

The Mechanism of the NLRP3 Inflammasome Activation and Pathogenic Implication in the Pathogenesis of Gout

The NACHT, LRR, and PYD-domains-containing protein 3 (NLRP3) inflammasome is an intracellular multi-protein signaling platform that is activated by cytosolic pattern-recognition receptors such as NLRs against endogenous and exogenous pathogens. Once it is activated by a variety of danger signals, recruitment and assembly of NLRP3, ASC, and pro-caspase-1 trigger the processing and release of pro-inflammatory cytokines including interleukin-1β (IL-1β) and IL-18. Multiple intracellular and extracellular structures and molecular mechanisms are involved in NLRP3 inflammasome activation. Gout is an autoinflammatory disease induced by inflammatory response through production of NLRP3 inflammasome-mediated proinflammatory cytokines such as IL-1β by deposition of monosodium urate (MSU) crystals in the articular joints and periarticular structures. NLRP3 inflammasome is considered a main therapeutic target in MSU crystal-induced inflammation in gout. Novel therapeutic strategies have been proposed to control acute flares of gouty arthritis and prophylaxis for gout flares through modulation of the NLRP3/IL-1 axis pathway. This review discusses the basic mechanism of NLRP3 inflammasome activation and the IL-1-induced inflammatory cascade and explains the NLRP3 inflammasome-induced pathogenic role in the pathogenesis of gout.

Inflammatory Response to Regulated Cell Death in Gout and Its Functional Implications

Gout, a chronic inflammatory arthritis disease, is characterized by hyperuricemia and caused by interactions between genetic, epigenetic, and metabolic factors. Acute gout symptoms are triggered by the inflammatory response to monosodium urate crystals, which is mediated by the innate immune system and immune cells (e.g., macrophages and neutrophils), the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation, and pro-inflammatory cytokine (e.g., IL-1β) release. Recent studies have indicated that the multiple programmed cell death pathways involved in the inflammatory response include pyroptosis, NETosis, necroptosis, and apoptosis, which initiate inflammatory reactions. In this review, we explore the correlation and interactions among these factors and their roles in the pathogenesis of gout to provide future research directions and possibilities for identifying potential novel therapeutic targets and enhancing our understanding of gout pathogenesis.

Phenols and terpenoids: natural products as inhibitors of NLRP3 inflammasome in cardiovascular diseases

Inflammatory infiltration has been implicated in the pathogenesis of cardiovascular diseases (CVDs). The NLRP3 inflammasome is involved in the development of several types of CVDs, including myocardial infarction, myocardial ischemia-reperfusion damage, heart failure, atrial fibrillation, and hypertension. Inhibiting the activity of NLRP3 inflammasome can inhibit the progress of CVDs. However, there is no NLRP3 inflammasome inhibitor in clinic, and it is very important to find a safe and effective NLRP3 inhibitor. Phenols and terpenoids are naturally natural products that have many anti-inflammatory effects in CVDs by modulating the NLRP3 inflammatory pathway. Thus, 20 natural products from phenols and terpenoids for the treatment of cardiovascular disease based on the inhibition of NLRP3 inflammasome were summarized and screened. Docking results showed salvianolic acid B and ellagic acid in phenols, and oridonin and triptolide in terpenoids had a better binding activity with NLRP3, which can provide theoretical support for finding novel NLRP3 inflammasome inhibitors or lead compounds in the future.

Evidence for the effect of soluble uric acid in augmenting endoplasmic reticulum stress markers in human peripheral blood mononuclear cells

There is evidence regarding the association of hyperuricemia with inflammatory disorders. Hence, it has been of particular interest to dissect the exact role of alteration in uric acid (UA) levels in the context of inflammation. Recently, the endoplasmic reticulum (ER) stress pathway has come into the forefront as a possible mechanism linking hyperuricemia to inflammation. Here, we intended to examine the role of UA in the presence or absence of a second stimulus, LPS, in human peripheral blood mononuclear cells (PBMCs), and analyzed ROS production as well as expression of ER stress markers: GRP78 and CHOP, and inflammatory cytokines.PBMCs were isolated using Ficoll gradient centrifugation from healthy volunteers. Cell viability was measured by MTT assay. PBMCs were treated with an increasing concentration of soluble UA (0, 5, 12, and 20 mg/dl) for 20 h, followed by the addition of 100 ng/mL of LPS or vehicle for another 4 h. Real time-PCR was performed to investigate the mRNA expression of GRP78, CHOP, TNF-α, IL-1β, and IL-6, and western blot was used to investigate the protein levels of GRP78 and CHOP. Moreover, ELISA was used to evaluate the protein levels of TNF-α, IL-1β, and IL-6. Finally, intracellular ROS production was determined using fluorescent probes (DCFH-DA).High concentrations of UA either alone or combined with LPS increased the protein levels of GRP78 and CHOP. On the other hand, LPS alone increased the protein levels of GRP78 and CHOP. However, there was no significant difference between the mRNA expression of GRP78, CHOP, TNF-α, IL-1β, and IL-6 when PBMCs were treated with UA. High concentrations of UA augmented LPS-stimulated IL-1β transcript and protein levels as well as TNF-α protein levels in PBMC culture. Moreover, high concentrations of UA along with LPS significantly increased intracellular ROS production.It seems that a high concentration of UA not only induces the protein levels of ER stress markers in PBMCs but also augments the impact of LPS on the levels of pro-inflammatory markers and ROS production.

The Essential Oil of Artemisia argyi H.Lév. and Vaniot Attenuates NLRP3 Inflammasome Activation in THP-1 Cells

Artemisia argyi H. Lév. and Vaniot is a traditional medical herb that has been used for a long time in China and other Asian counties. Essential oil is the main active fraction of Artemisia argyi H. Lév. and Vaniot, and its anti-inflammatory potential has been observed in vitro and in vivo. Here, we found that the essential oil of Artemisia argyi H. Lév. and Vaniot (EOAA) inhibited monosodium urate (MSU)- and nigericin-induced NLRP3 inflammasome activation. EOAA suppressed caspase-1 and IL-1β processing and pyroptosis. NF-κB p65 phosphorylation and translocation were also inhibited. In addition, EOAA suppressed nigericin-induced NLRP3 inflammasome activation without blocking ASC oligomerization, suggesting that it may inhibit NLRP3 inflammasome activation by preventing caspase-1 processing. Our study thus indicates that EOAA inhibits NLRP3 inflammasome activation and has therapeutic potential against NLRP3-driven diseases.

Plant-microbial interaction: The mechanism and the application of microbial elicitor induced secondary metabolites biosynthesis in medicinal plants

Plants and microbes interact with each other via different chemical signaling pathways. At the risophere level, the microbes can secrete molecules, called elicitors, which act on their receptors located in plant cells. The so-called elicitor molecules as well as their actions differ according to the mcirobes and induce different bilogical responses in plants such as the synthesis of secondary metabolites. Microbial compounds induced phenotype changes in plants are known as elicitors and signaling pathways which integrate elicitor's signals in plants are called elicitation. In this review, the impact of microbial elicitors on the synthesis and the secretion of secondary metabolites in plants was highlighted. Moreover, biological properties of these bioactive compounds were also highlighted and discussed. Indeed, several bacteria, fungi, and viruses release elicitors which bind to plant cell receptors and mediate signaling pathways involved in secondary metabolites synthesis. Different phytochemical classes such as terpenoids, phenolic acids and flavonoids were synthesized and/or increased in medicinal plants via the action of microbial elicitors. Moreover, these compounds compounds exhibit numerous biological activities and can therefore be explored in drugs discovery.

Reactive oxygen species induced by uric acid promote NRK‑52E cell apoptosis through the NEK7‑NLRP3 signaling pathway

Increasing uric acid (UA) could induce renal tubular epithelial cell (NRK-52E) injury. However, the specific mechanism by which UA induces renal tubular epithelial cell injury remains unknown. It was hypothesized that UA induces renal tubular epithelial cell injury through reactive oxygen species (ROS) and the Never in mitosis gene A (NIMA)-related kinase 7 (NEK7)/NLR family pyrin domain containing 3 (NLRP3) signaling pathway. TUNEL assay and flow cytometry were applied to measure apoptosis, and the results of the present study showed that UA treatment induced apoptosis of NRK-52E cells in a concentration-dependent manner. Western blotting was performed to determine the expression levels of cleaved caspase-3, Bax and Bcl-xl, it was found that levels were significantly increased after UA treatment in NRK-52E cells. ROS and apoptosis were predominantly induced in NRK-52E cells and there was an association between ROS and apoptosis. Enhanced expression of NEK7, NLRP3, apoptosis-associated speck-like and caspase-1 were observed in NRK-52E cells treated with UA. The ROS inhibitor, N-acetyl-l-cysteine, exerted a protective effect on the UA-induced apoptosis of tubular epithelial cells by reducing excess ROS production, which significantly inhibited NEK7 and NLRP3 inflammasome activation. These results indicated that UA activates ROS and induces apoptosis of NRK-52E cells. The mechanism might be related to the regulation of the NEK7/NLRP3 signaling pathway.

Mechanisms and Molecular Targets of Artemisinin in Cancer Treatment

The major problems with cancer therapy are drug-induced side effects. There is an urgent need for safe anti-tumor drugs. Artemisinin is a Chinese herbal remedy for malaria with efficacy and safety. However, several studies reported that artemisinin causes neurotoxicity and cardiotoxicity in animal models. Recently, nanostructured drug delivery systems have been designed to improve therapeutic efficacy and reduce toxicity. Artemisinin has been reported to show anticancer properties. The anticancer effects of artemisinin appear to be mediated by inducing cell cycle arrest, promoting ferroptosis and autophagy, inhibiting cell metastasis. Therefore, the review is to concentrate on mechanisms and molecular targets of artemisinin as anti-tumor agents. We believe these will be important topics in realizing the potential of artemisinin and its derivatives as potent anticancer agents.

The immunosuppressive activity of artemisinin-type drugs towards inflammatory and autoimmune diseases

The sesquiterpene lactone artemisinin from Artemisia annua L. is well established for malaria therapy, but its bioactivity spectrum is much broader. In this review, we give a comprehensive and timely overview of the literature regarding the immunosuppressive activity of artemisinin-type compounds toward inflammatory and autoimmune diseases. Numerous receptor-coupled signaling pathways are inhibited by artemisinins, including the receptors for interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α), β3-integrin, or RANKL, toll-like receptors and growth factor receptors. Among the receptor-coupled signal transducers are extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), AKT serine/threonine kinase (AKT), mitogen-activated protein kinase (MAPK)/extracellular signal regulated kinase (ERK) kinase (MEK), phospholipase C γ1 (PLCγ), and others. All these receptors and signal transduction molecules are known to contribute to the inhibition of the transcription factor nuclear factor κ B (NF-κB). Artemisinins may inhibit NF-κB by silencing these upstream pathways and/or by direct binding to NF-κB. Numerous NF-κB-regulated downstream genes are downregulated by artemisinin and its derivatives, for example, cytokines, chemokines, and immune receptors, which regulate immune cell differentiation, apoptosis genes, proliferation-regulating genes, signal transducers, and genes involved in antioxidant stress response. In addition to the prominent role of NF-κB, other transcription factors are also inhibited by artemisinins (mammalian target of rapamycin [mTOR], activating protein 1 [AP1]/FBJ murine osteosarcoma viral oncogene homologue [FOS]/JUN oncogenic transcription factor [JUN]), hypoxia-induced factor 1α (HIF-1α), nuclear factor of activated T cells c1 (NF-ATC1), Signal transducers and activators of transcription (STAT), NF E2-related factor-2 (NRF-2), retinoic-acid-receptor-related orphan nuclear receptor γ (ROR-γt), and forkhead box P-3 (FOXP-3). Many in vivo experiments in disease-relevant animal models demonstrate therapeutic efficacy of artemisinin-type drugs against rheumatic diseases (rheumatoid arthritis, osteoarthritis, lupus erythematosus, arthrosis, and gout), lung diseases (asthma, acute lung injury, and pulmonary fibrosis), neurological diseases (autoimmune encephalitis, Alzheimer's disease, and myasthenia gravis), skin diseases (dermatitis, rosacea, and psoriasis), inflammatory bowel disease, and other inflammatory and autoimmune diseases. Randomized clinical trials should be conducted in the future to translate the plethora of preclinical results into clinical practice.

Gout Augments the Risk of Cardiovascular Disease in Patients With Psoriasis: A Population-Based Cohort Study

Objective

Patients with psoriasis (PsO) have a high frequency of concomitant gout and increased risk of cardiovascular diseases (CVD). We aimed to estimate the synergistic impact of gout on the risk of CVD in patients with PsO.

Methods

A population-based cohort of patients registered in the National Health Insurance Research Database of Taiwan between 2000 and 2013 was stratified according to the presence of PsO and gout. Propensity score analysis was used to match age and gender at a ratio of 1:4. Cox proportional hazard models and subgroup analyses were used to estimate the hazard ratios (HRs) for CVD adjusted for traditional risk factors. The Kaplan–Meier method was used to plot the cumulative incidence curves.

Results

Patients with combined PsO and gout (n = 97), PsO alone (n = 388), gout alone (matched, n = 388) and matched controls (n = 388) were identified. Compared with the patients with PsO alone, the patients with combined PsO and gout had a significantly higher risk of CVD (relative risk 2.39, 95% CI 1.56 to 3.65). After adjustment for traditional risk factors, the risk of CVD was higher in patients with gout alone (HR 2.16, 95% CI 1.54 to 3.04) and in patients with combined PsO and gout (HR 2.72, 95% CI 1.73 to 4.28).

Conclusions

Gout augments the risk of CVD independently of traditional risk factors in patients with PsO.

Brevilin A inhibits NLRP3 inflammasome activation in vivo and in vitro by acting on the upstream of NLRP3-induced ASC oligomerization

Brevilin A (BA), is a natural biologically active ingredient derived from Centipeda minima with several reports of anti-cancer, while its anti-inflammatory activity is rarely reported. Current studies have found the dysregulated activation of NLRP3 inflammasome cause a variety of inflammatory diseases. Targeting the NLRP3 inflammasome contributes to the treatment of NLRP3-induced diseases. Here, we found that BA significantly attenuates the activation of caspase-1 and the subsequent secretion of the interleukin-1β (IL-1β) in mouse macrophages and human THP-1 cells, showing the inhibitory effect of BA on the NLRP3 inflammasome activation. Moreover, BA specifically inhibits NLRs inflammasomes activation triggered by multi-stimuli, but it has no effect on the AIM2 inflammasome activation, indicating that BA is a specific inhibitor of the NLRs inflammasomes. Research on the mechanism found BA inhibits NLRP3 inflammasome activation by blocking the upstream of ASC oligomerization. Importantly, in vivo experiments showed that BA markedly reduces the secretion of IL-1β to suppress NLRP3 inflammasome in the LPS-induced inflammation and MSU-challenged peritonitis model. In conclusion, our experiments show that BA is an effective NLRP3 inflammasome inhibitor and can be regarded as a drug candidate for NLRP3 inflammasome-driven diseases.

An update on the regulatory mechanisms of NLRP3 inflammasome activation

The NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is a multiprotein complex involved in the release of mature interleukin-1β and triggering of pyroptosis, which is of paramount importance in a variety of physiological and pathological conditions. Over the past decade, considerable advances have been made in elucidating the molecular mechanisms underlying the priming/licensing (Signal 1) and assembly (Signal 2) involved in NLRP3 inflammasome activation. Recently, a number of studies have indicated that the priming/licensing step is regulated by complicated mechanisms at both the transcriptional and posttranslational levels. In this review, we discuss the current understanding of the mechanistic details of NLRP3 inflammasome activation with a particular emphasis on protein-protein interactions, posttranslational modifications, and spatiotemporal regulation of the NLRP3 inflammasome machinery. We also present a detailed summary of multiple positive and/or negative regulatory pathways providing upstream signals that culminate in NLRP3 inflammasome complex assembly. A better understanding of the molecular mechanisms underlying NLRP3 inflammasome activation will provide opportunities for the development of methods for the prevention and treatment of NLRP3 inflammasome-related diseases.

Antimalarial and anticancer properties of artesunate and other artemisinins: current development

This review provides a recent perspective of artesunate and other artemisinins as antimalarial drugs and their uses in cancer therapy. Artesunate is an artemisinin derivative. Artemisinin is extracted from the plant Artemisia annua. Artemisinin and its derivatives have been the most useful drug for malarial treatment in human history. The artesunate has an advantage of a hydrophilic group over other artemisinins which makes it a more potent drug. On the industrial scale, artemisinins are synthesized in semisynthetic ways. The 1,2,4-endoperoxide bridge of artemisinins is responsible for the drug's antimalarial activity. There is the emergence of artemisinin resistance on Plasmodium falciparum and pieces of evidence suggest that it is mainly due to the mutation at Kelch13 protein of P. falciparum. Clinical trial data show that the artesunate is more favorable than quinine and other artemisinins to treat patients with severe malaria. Pieces of evidence indicate that artemisinins can be developed as anticancer drugs. The mechanism of actions on how artemisinins act as an anticancer drug involves oxidative stress, DNA damage and repair, and various types of cell deaths.

Inhibition of ROS/NLRP3/Caspase-1 mediated pyroptosis alleviates excess molybdenum-induced apoptosis in duck renal tubular epithelial cells

OBJECTIVE

Excess molybdenum (Mo) is harmful to the body, and the kidney is the vital target organ for Mo exposure. This study focused on the impacts of excess Mo on pyroptosis and the relationship between pyroptosis and apoptosis in kidney.

METHODS

The duck renal tubular epithelial cells were treated with (NH₄)₆Mo₇O₂₄·4H₂O (0, 480, 720 and 960 μM Mo), N-acetyl-L-cysteine (NAC) (100 μM), Z-YVAD-fluoromethylketone (YVAD) (10 μM) and the combination of Mo and NAC or YVAD for 12 h. The LDH release and IL-1β, IL-18 contents of cell supernatant were detected by LDH and ELISA kits. The MMP and ROS level were measured using MMP and ROS kits by flow cytometry. The apoptotic rate of cell was detected by AO/EB counterstaining. Pyroptosis and apoptosis-related factors mRNA and protein levels were assayed by real-time qPCR and western blot, respectively.

RESULTS

Excessive Mo markedly increased LDH, IL-18, IL-1β releases and induced overproduction of ROS, pyroptosis-related factors mRNA and protein levels. NAC and YVAD dramatically decreased pyroptosis induced by Mo. Simultaneously, YVAD significantly changed apoptosis-related factors mRNA and protein levels, and reduced cell apoptotic rate.

CONCLUSION

Excessive Mo exposure can induce pyroptosis by the ROS/NLRP3/Caspase-1 pathway in duck renal tubular epithelial cells, and restraining pyroptosis of Caspase-1 dependence might weaken excess Mo-induced apoptosis. The study provides theoretical basis for excess Mo exposure nephrotoxic researches on waterfowl and the interplay between pyroptosis and apoptosis highlights a new sight into the mechanism of Mo-induced nephrotoxicity.

Artesunate Switches Monocytes to an Inflammatory Phenotype with the Ability to Kill Leukemic Cells

Monocytes are components of the tumor microenvironment related to cancer progression and immune escape. Therapeutic strategies for reprogramming monocytes from a tumor-supporting phenotype towards a tumoricidal phenotype are of great interest. Artesunate (ART) may be an interesting option for cancer treatment; however, the role of ART in regulating the inflammatory tumor microenvironment has not yet been investigated. Our aim is to evaluate the immunomodulatory potential of ART in vitro in human primary monocytes. ART treatment induced an increase in inflammatory monocytes (CD14^highCD16⁻) with HLA-DR high expression and MCP-1/IL-1β release. On the other hand, ART treatment reduced CD206 and CD163 expression, and abolished the monocyte population known as non-classical and intermediate. Leukemia cells in contact with monocytes programmed with ART presented enhanced in vitro apoptosis suggesting that monocytes acquired the ability to kill leukemic cells. ART induced changes in the monocyte phenotype were mediated by JAK2/STAT3 downregulation. The induction of immunosuppressive environment is an important step for cancer progression. ART showed an immunomodulatory activity, leading immune cells to an antitumor phenotype and could be a candidate for immunotherapy in cancer patients.

Physiological and Pathological Roles of Mammalian NEK7

NEK7 is the smallest NIMA-related kinase (NEK) in mammals. The pathological and physiological roles of NEK7 have been widely reported in many studies. To date, the major function of NEK7 has been well documented in mitosis and NLRP3 inflammasome activation, but the detailed mechanisms of its regulation remain unclear. This review summarizes current advances in NEK7 research involving mitotic regulation, NLRP3 inflammasome activation, related diseases and potential inhibitors, which may provide new insights into the understanding and therapy of the diseases associated with NEK7, as well as the subsequent studies in the future.

Exploration of the mechanism of Zisheng Shenqi decoction against gout arthritis using network pharmacology

BACKGROUND

In this study, the network pharmacological methods were used to predict the target of effective components of compounds in Zisheng Shenqi Decoction (ZSD, or Nourishing Kidney Qi Decoction) in the treatment of gouty arthritis (GA).

METHOD

The main effective components and corresponding key targets of herbs in the ZSD were discerned through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis (TCMSP), Bioinformatics Analysis Tool for Molecular mechanism of Traditional Chinese Medicine (BATMAN-TCM) database. UniProt database and Swiss Target Prediction (STP) database was used to rectify and unify the target names and supply the target information. The targets related to GA were obtained by using GeneCards database. After we discovered the potential common targets between ZSD and GA, the interaction network diagram of "ZSD-component-GA-target" was constructed by Cytoscape software (Version 3.7.1). Subsequently, the Protein-protein interaction (PPI) network of ZSD effective components-targets and GA-related targets was constructed by Search Tool for the Retrieval of Interacting Genes Database (STRING). Bioconductor package "org.Hs.eg.db" and "cluster profiler" package were installed in R software (Version 3.6.0) which used for Gene Ontology analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis.

RESULTS

146 components and 613 targets of 11 herbal medicines in the ZSD were got from TCMSP database and BATMAN-TCM database. 987 targets of GA were obtained from GeneCards database. After intersected and removed duplications, 132 common targets between ZSD and GA were screened out by Cytoscape software (Version 3.7.1). These common targets derived from 81 effective components of 146 components, such as quercetin, stigmasterol and kaempferol. They were closely related to anti-inflammatory, analgesic and anti oxidative stress and the principal targets comprised of Purinergic receptor P2X, ligand-gated ion channel 7 (P2x7R), Nod-like receptor protein 3 (NLRP3) and IL-1β. GO enrichment analysis and KEGG pathway enrichment analysis by R software (Version 3.6.0) showed that the key target genes had close relationship with oxidative stress, reactive oxygen species (ROS) metabolic process and leukocyte migration in aspects of biological process, cell components and molecular function. It also indicated that ZSD could decrease inflammatory reaction, alleviate ROS accumulation and attenuate pain by regulating P2 × 7R and NOD like receptor signaling pathway of inflammatory reaction.

CONCLUSION

A total of 81 effective components and 132 common target genes between ZSD and GA were screened by network pharmacology. The PPI network, GO enrichment analysis and KEGG pathway enrichment analysis suggested that ZSD can exerte anti-inflammatory and analgesic effects on the treatment of GA by reducing decreasing inflammatory reaction, alleviating ROS accumulation, and attenuating pain. The possible molecular mechanism of it mainly involved multiple components, multiple targets and multiple signaling pathways, which provided a comprehensive understanding for further study. In general, the network pharmacological method applied in this study provides an alternative strategy for the mechanism of ZSD in the treatment of GA.

Uric Acid and Cardiovascular Disease: An Update From Molecular Mechanism to Clinical Perspective

Uric acid (UA) is the end product of purine nucleotide metabolism in the human body. Hyperuricemia is an abnormally high level of UA in the blood and may result in arthritis and gout. The prevalence of hyperuricemia has been increasing globally. Epidemiological studies have shown that UA levels are positively correlated with cardiovascular diseases, including hypertension, atherosclerosis, atrial fibrillation (AF), and heart failure (HF). Hyperuricemia promotes the occurrence and development of cardiovascular diseases by regulating molecular signals, such as inflammatory response, oxidative stress, insulin resistance/diabetes, endoplasmic reticulum stress, and endothelial dysfunction. Despite extensive research, the underlying molecular mechanisms are still unclear. Allopurinol, a xanthine oxidase (XO) inhibitor, has been shown to improve cardiovascular outcomes in patients with HF, coronary heart disease (CHD), type 2 diabetes (T2D), and left ventricular hypertrophy (LVH). Whether febuxostat, another XO inhibitor, can improve cardiovascular outcomes as well as allopurinol remains controversial. Furthermore, it is also not clear whether UA-lowering treatment (ULT) can benefit patients with asymptomatic hyperuricemia. In this review, we focus on the latest cellular and molecular findings of cardiovascular disease associated with hyperuricemia and clinical data about the efficacy of ULT in patients with cardiovascular disease.

Inhibition of ROS/NLRP3/Caspase-1 mediated pyroptosis attenuates cadmium-induced apoptosis in duck renal tubular epithelial cells

Cadmium (Cd) is an occupational and environmental pollutant, which mainly causes nephrotoxicity by damaging renal proximal tubular cells. To evaluate the effects of Cd on pyroptosis and the relationship between pyroptosis and apoptosis in duck renal tubular epithelial cells, the cells were cultured with 3CdSO4·8H2O (0, 2.5, 5.0, or 10.0 μM Cd), N-acetyl-L-cysteine (NAC) (100.0 μM), Z-YVAD-FMK (10.0 μM) or the combination of Cd and NAC or Z-YVAD-FMK for 12 h, and then cytotoxicity was assessed. The results evidenced that Cd significantly increased the releases of interleukin-18 (IL-18) and interleukin-1β (IL-1β), lactate dehydrogenase (LDH) and nitric oxide (NO), relative conductivity and cellular reactive oxygen species (ROS) level. Simultaneously, Cd also markedly upregulated NLRP3, Caspase-1, ASC, NEK7, IL-1β and IL-18 mRNA levels and NLRP3, Caspase-1 p20, GSDMD and ASC protein levels. Additionally, NAC notably improved the changes of above indicators induced by Cd. Combined treatment with Cd and Z-YVAD-FMK remarkably elevated Bcl-2 mRNA and protein levels, inhibited p53, Bax, Bak-1, Cyt C, Caspase-9 and Caspase-3 mRNA levels and p53, Bax, Bak-1, Caspase-9/cleaved Caspase-9 and Caspase-3/cleaved Caspase-3 protein levels, increased mitochondrial membrane potential (MMP), decreased apoptosis ratio and cell damage compared to treatment with Cd alone. Taken together, Cd exposure induces duck renal tubular epithelial cell pyroptosis through ROS/NLRP3/Caspase-1 signaling pathway, and inhibiting Caspase-1 dependent pyroptosis attenuates Cd-induced apoptosis.

Effects of dihydroartemisinin on the gut microbiome of mice

Dihydroartemisinin (DHA) is a semisynthetic derivative of artemisinin, which has been found to exhibit a broad range of biological activities, excluding antimalarial effects; however its effects on the gut microbiota remain poorly understood. The present study aimed to investigate the effects of DHA on the gut microbiome in mice and to determine its potential biological and pharmaceutical activities through its alteration of the gut microbiota. Serum glucose, triglyceride (TG), total cholesterol, lipopolysaccharide, high density lipoprotein‑cholesterol, low density lipoprotein‑cholesterol, alanine aminotransferase and aspartate aminotransferase levels in mice treated with DHA were analyzed using the corresponding detection kits. In addition, hematoxylin and eosin staining was performed to determine the pathological effects of DHA on the liver, kidney and intestinal tissues of mice, and the effects of DHA on the gut microbiome were analyzed using 16S ribosomal (r)DNA gene analysis. The results demonstrated that the TG serum levels of mice treated with DHA were significantly decreased compared with the control group. Furthermore, 16S rDNA gene analysis demonstrated that the bacterial diversity of mice treated with DHA was enriched compared with the control group. The DHA group exhibited increased numbers of Firmicutes and Saccharibacteria, and decreased Deferribacteres and Actinobacteria compared with the control group at the phylum level. Kyoto Encyclopedia of Genes and Genomes signaling pathway enrichment analysis also revealed that the signaling pathways associated with 'Energy metabolism' and 'Nucleotide metabolism' were upregulated, whereas the signaling pathways associated with 'Infectious diseases and 'Neurodegenerative diseases' were downregulated in the DHA group compared with the control group. In conclusion, the findings of the present study indicated that DHA may significantly decrease the serum TG levels and alter the gut microbiota, which suggested its potential to be used for the treatment of hyperlipidemia, inflammatory and neurodegenerative disorders.