Erianin: A Direct NLRP3 Inhibitor With Remarkable Anti-Inflammatory Activity

Grape/Blueberry Anthocyanins and Their Gut-Derived Metabolites Attenuate LPS/Nigericin-Induced Inflammasome Activation by Inhibiting ASC Speck Formation in THP-1 Monocytes

Inflammasomes are multi-protein complexes, which are formed in response to tissue injury, infections, and metabolic stress. However, aberrant inflammasome activation has been linked to several inflammatory diseases. Anthocyanins have been reported to attenuate NLR family pyrin domain-containing 3 (NLRP3) inflammasome activation, but the influence of grape/blueberry anthocyanins and especially their gut-derived metabolites on NLRP3 inflammasome activation in human monocytes remains unclear. Therefore, human leukemic monocytes (THP-1 cells, Tohoku Hospital Pediatrics-1 cells) were preincubated with different concentrations of grape/blueberry anthocyanins, homovanillyl alcohol, or 2,4,6-trihydroxybenzaldehyde (THBA) before the NLRP3 inflammasome was activated by lipopolysaccharide and/or nigericin. Apoptosis-associated speck-like protein containing a CARD (ASC) speck formation, as well as ASC and NLRP3 protein expression, were determined using flow cytometry. Caspase-1 activity was measured in cultured cells, and pro-inflammatory cytokine secretion was determined using enzyme-linked immunosorbent assays. Anthocyanins and their metabolites had no effect on ASC or NLRP3 protein expression. However, THBA significantly inhibited ASC speck formation in primed and unprimed THP-1 monocytes, while caspase-1 activity was significantly declined by grape/blueberry anthocyanins. Furthermore, reduced inflammasome activation resulted in lower pro-inflammatory cytokine secretion. In conclusion, our results show for the first time that grape/blueberry anthocyanins and their gut-derived metabolites exert anti-inflammatory effects by attenuating NLRP3 inflammasome activation in THP-1 monocytes.

Erianin promotes apoptosis and inhibits Akt-mediated aerobic glycolysis of cancer cells

Highly activated aerobic glycolysis provides the metabolic requirements for tumor cell growth and proliferation. Erianin, a natural product isolated from Dendrobium chrysotoxum Lindl, has been reported to exert antitumor activity in multiple cancers. However, whether Erianin exerts inhibitory effects on aerobic glycolysis and the inherent mechanism remain poorly defined in non-small cell lung cancer (NSCLC). Here, we showed that Erianin inhibited the cell viability and proliferation, and induced apoptosis in NSCLC cells. Moreover, Erianin overtly suppressed aerobic glycolysis via decreasing HK2 expression. Mechanistically, Erianin dose-dependently curbed the Akt-GSK3β signaling pathway phosphorylation activation, which afterwards downregulated HK2 expression. Meanwhile, Erianin inhibited HCC827 tumor growth in vivo. Taken together, our results suggest that the natural product Erianin can suppress aerobic glycolysis and exert potent anticancer effects via the Akt-GSK3β signaling pathway in NSCLC cells.

Drugging the NLRP3 inflammasome: from signalling mechanisms to therapeutic targets

Diseases associated with chronic inflammation constitute a major health burden across the world. As central instigators of the inflammatory response to infection and tissue damage, inflammasomes - and the NACHT, LRR and PYD domain-containing protein 3 (NLRP3) inflammasome in particular - have emerged as key regulators in diverse rheumatic, metabolic and neurodegenerative diseases. Similarly to other inflammasome sensors, NLRP3 assembles a cytosolic innate immune complex that activates the cysteine protease caspase-1, which in turn cleaves gasdermin D (GSDMD) to induce pyroptosis, a regulated mode of lytic cell death. Pyroptosis is highly inflammatory, partly because of the concomitant extracellular release of the inflammasome-dependent cytokines IL-1β and IL-18 along with a myriad of additional danger signals and intracellular antigens. Here, we discuss how NLRP3 and downstream inflammasome effectors such as GSDMD, apoptosis-associated speck-like protein containing a CARD (ASC) and nerve injury-induced protein 1 (NINJ1) have gained significant traction as therapeutic targets. We highlight the recent progress in developing small-molecule and biologic inhibitors that are advancing into the clinic and serving to harness the broad therapeutic potential of modulating the NLRP3 inflammasome.

Targeting NLRP3 Inflammasome: Structure, Function, and Inhibitors

Inflammasomes are multimeric protein complexes that can detect various physiological stimuli and danger signals. As a result, they perform a crucial function in the innate immune response. The NLRP3 inflammasome, as a vital constituent of the inflammasome family, is significant in defending against pathogen invasion and preserving cellhomeostasis. NLRP3 inflammasome dysregulation is connected to various pathological conditions, including inflammatory diseases, cancer, and cardiovascular and neurodegenerative diseases. This profile makes NLRP3 an applicable target for treating related diseases, and therefore, there are rising NLRP3 inhibitors disclosed for therapy. Herein, we summarized the updated advances in the structure, function, and inhibitors of NLRP3 inflammasome. Moreover, we aimed to provide an overview of the existing products and future directions for drug research and development.

Antiphagocytic Properties of Polygallic Acid with Implications in Gouty Inflammation

Polygallic acid (PGAL) has been used in vitro to protect synoviocytes from monosodium urate (MSU) crystals due to its anti-inflammatory properties. However, MSU crystals can also activate other cells of the synovial fluid (SF). We studied the impact of PGAL on the phagocytosis of MSU crystals, inflammation, and oxidative stress using an in vitro model with SF leukocytes and THP-1 monocyte cells. SF leukocytes were stimulated with PGAL and MSU crystals, proinflammatory cytokines and phagocytosis were assessed. In THP-1 cells, the effect of PGAL on the phagocytosis of MSU crystals and the levels of IL-1β, IL-6, TNF-α, and reactive oxygen species (ROS) was evaluated. PGAL was added to THP-1 cultures 24 h before MSU crystal addition as a pre-treatment, and IL-1β was measured. One-way ANOVA with Tukey's post hoc test was performed, and a P value < 0.05 was considered statistically significant. PGAL (100 µg/mL) decreased phagocytosis in SF leukocytes by 14% compared to cells exposed to crystals without PGAL. In THP-1 cells, 100 and 200 µg/mL PGAL reduced phagocytosis by 17% and 15%, respectively. In SF cells, there was a tendency to decrease IL-1β and IL-6. In THP-1 cells, decreases in IL-1β and TNF-α, as well as a slight decrease in ROS, were identified. PGAL pre-treatment resulted in a reduction of IL-1β. PGAL inhibits MSU phagocytosis by exerting an anti-inflammatory effect on cells exposed to crystals. The use of PGAL before an acute attack of gout suggests an important protective factor to control the inflammation.

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.

Erianin: A phytoestrogen with therapeutic potential

Erianin, a phytoestrogen with therapeutic potential, is one of the major active components of Dendrobll caulis. Erianin has a variety of pharmacological effects, such as anti-tumor, anti-inflammatory, anti-diabetic retinopathy, anti-psoriasis, and antibacterial effects. Especially, in regard to the anti-tumor effect of erianin, the underlying molecular mechanism has been partly clarified. In fact, the numerous pharmacological actions of erianin are complex and interrelated, mainly including ERK1/2, PI3K/Akt, JAK2/STAT3, HIF-1α/PD-L1, PPT1/mTOR, JNK/c-Jun, and p38 MAPK signal pathway. However, on account of the poor water solubility and the low bioavailability of erianin, greatly affected and limited its further development and application. And it is worthwhile and meaningful to explore more extensive pharmacological effects and mechanisms, clarify pharmacokinetics, and synthesize the derivatives of erianin. Conclusively, in this paper, the pharmacological effects of erianin and its mechanism, pharmacokinetics, and derivatives studies were reviewed, in order to provide a reference for the development and application of erianin.

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.

Discovery of alantolactone as a naturally occurring NLRP3 inhibitor to alleviate NLRP3-driven inflammatory diseases in mice

BACKGROUND AND PURPOSE

The NLR family pyrin domain-containing 3 (NLRP3) inflammasome is activated in many inflammatory conditions. So far, no low MW compounds inhibiting NLRP3 have entered clinical use. Identification of naturally occurring NLRP3 inhibitors may be beneficial to the design and development of compounds targeting NLRP3. Alantolactone is a phytochemical from a traditional Chinese medicinal plant with anti-inflammatory activity, but its precise target remains unclear.

EXPERIMENTAL APPROACH

A bank of phytochemicals was screened for inhibitors of NLRP3-driven production of IL-1β in cultures of bone-marrow-derived macrophages from female C57BL/6 mice. Models of gouty arthritis and acute lung injury in male C57BL/6J mice were used to determine the in vivo effects of the most potent compound.

KEY RESULTS

Among the 150 compounds screened in vitro, alantolactone exhibited the highest inhibitory activity against LPS + ATP-induced production of IL-1β in macrophages, suppressing IL-1β secretion, caspase-1 activation and pyroptosis. Alantolactone directly bound to the NACHT domain of NLRP3 to inhibit activation and assembly of NLRP3 inflammasomes. Molecular simulation analysis suggested that Arg335 in NLRP3 was a critical residue for alantolactone binding, leading to suppression of NLRP3-NEK7 interaction. In vivo studies confirmed significant alleviation by alantolactone of two NLRP3-driven inflammatory conditions, acute lung injury and gouty arthritis.

CONCLUSION AND IMPLICATIONS

The phytochemical alantolactone inhibited activity of NLRP3 inflammasomes by directly targeting the NACHT domain of NLRP3. Alantolactone shows great potential in the treatment of NLRP3-driven diseases and could lead to the development of novel NLRP3 inhibitors.

The roles of ERIANIN in tumor and innate immunity and its' perspectives in immunotherapy

Traditional Chinese medicine has been used in China for thousands of years. In 2022, the 14th Five-Year Plan for the Development of Traditional Chinese Medicine was released, aiming to enhance traditional Chinese medicine health services and improve policies and systems for high-quality traditional Chinese medicinal development by 2025. ERIANIN, the main component of the traditional Chinese medicine Dendrobium, plays an important role in anti-inflammatory, antiviral, antitumor, antiangiogenic, and other pharmacological effects. ERIANIN has broad-spectrum antitumor effects, and its tumor-suppressive effects have been confirmed in the study of various diseases, such as precancerous lesions of the stomach, gastric cancer, liver cancer, lung cancer, prostate cancer, bladder cancer, breast cancer, cervical cancer, osteosarcoma, colorectal cancer, leukaemia, nasopharyngeal cancer and melanoma through the multiple signaling pathways. Thus, the aim of this review was to systematically summarise the research on ERIANIN with the aim of serving as a reference for future research on this compound and briefly discuss some future perspectives development of ERIANIN in combined immunotherapy.

The role of NLRP3 inflammasome in digestive system malignancy

Digestive system malignancies, the most common types of cancer and a major cause of death in the worldwide, are generally characterized by high morbidity, insidious symptoms and poor prognosis. NLRP3 inflammasome, the most studied inflammasome member, is considered to be crucial in tumorigenesis. In this paper, we reviewed its pro-tumorigenic and anti-tumorigenic properties in different types of digestive system malignancy depending on the types of cells, tissues and organs involved, which would provide promising avenue for exploring new anti-cancer therapies.

Genome-wide identification and expression analysis of the GRAS gene family in Dendrobium chrysotoxum

The GRAS gene family encodes transcription factors that participate in plant growth and development phases. They are crucial in regulating light signal transduction, plant hormone (e.g. gibberellin) signaling, meristem growth, root radial development, response to abiotic stress, etc. However, little is known about the features and functions of GRAS genes in Orchidaceae, the largest and most diverse angiosperm lineage. In this study, genome-wide analysis of the GRAS gene family was conducted in Dendrobium chrysotoxum (Epidendroideae, Orchidaceae) to investigate its physicochemical properties, phylogenetic relationships, gene structure, and expression patterns under abiotic stress in orchids. Forty-six DchGRAS genes were identified from the D. chrysotoxum genome and divided into ten subfamilies according to their phylogenetic relationships. Sequence analysis showed that most DchGRAS proteins contained conserved VHIID and SAW domains. Gene structure analysis showed that intronless genes accounted for approximately 70% of the DchGRAS genes, the gene structures of the same subfamily were the same, and the conserved motifs were also similar. The Ka/Ks ratios of 12 pairs of DchGRAS genes were all less than 1, indicating that DchGRAS genes underwent negative selection. The results of cis-acting element analysis showed that the 46 DchGRAS genes contained a large number of hormone-regulated and light-responsive elements as well as environmental stress-related elements. In addition, the real-time reverse transcription quantitative PCR (RT-qPCR) experimental results showed significant differences in the expression levels of 12 genes under high temperature, drought and salt treatment, among which two members of the LISCL subfamily (DchGRAS13 and DchGRAS15) were most sensitive to stress. Taken together, this paper provides insights into the regulatory roles of the GRAS gene family in orchids.

Anti-Inflammatory and Hypouricemic Effect of Bioactive Compounds: Molecular Evidence and Potential Application in the Management of Gout

Gout is caused by the deposition of monosodium urate crystals in the joint and represents the most common form of inflammatory arthritis in men. Its prevalence is rising worldwide mainly due to the increase of risk factors associated with the disease, in particular hyperuricemia. Besides gout, hyperuricemia leads to an increased inflammatory state of the body with consequent increased risk of comorbidities such as cardiovascular diseases. Increasing evidence shows that bioactive compounds have a significant role in fighting inflammatory and immune chronic conditions. In gout and hyperuricemia, these molecules can exert their effects at two levels. They can either decrease serum uric acid concentrations or fight inflammation associated with monosodium urate crystals deposits and hyperuricemia. In this view, they might be considered valuable support to the pharmacological therapy and prevention of the disease. This review aims to provide an overview of the beneficial role of bioactive compounds in hyperuricemia, gout development, and inflammatory pathways of the disease.

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.

Anticancer Activity of Erianin: Cancer-Specific Target Prediction Based on Network Pharmacology

Erianin is a major bisbenzyl compound extracted from Dendrobium chrysotoxum Lindl., an important traditional Chinese herb. In recent years, a growing body of evidence has proved the potential therapeutic effects of erianin on various cancers, including hepatoma, melanoma, non-small-cell lung carcinoma, myelogenous leukemia, breast cancer, and osteosarcoma. Especially, the pharmacological activities of erianin, such as antioxidant and anticancer activity, have been frequently demonstrated by plenty of studies. In this study, we firstly conducted a systematic review on reported anticancer activity of erianin. All updated valuable information regarding the underlying action mechanisms of erianin in specific cancer was recorded and summarized in this paper. Most importantly, based on the molecular structure of erianin, its potential molecular targets were analyzed and predicted by means of the SwissTargetPrediction online server (http://www.swisstargetprediction.ch). In the meantime, the potential therapeutic targets of 10 types of cancers in which erianin has been proved to have anticancer effects were also predicted via the Online Mendelian Inheritance in Man (OMIM) database (http://www.ncbi.nlm.nih.gov/omim). The overlapping targets may serve as valuable target candidates through which erianin exerts its anticancer activity. The clinical value of those targets was subsequently evaluated by analyzing their prognostic role in specific cancer using Kaplan-Meier plotter (http://Kmplot.com/analysis/) and Gene Expression Profiling Interactive Analysis (GEPIA) (http://gepia.cancer-pku.cn/). To better assess and verify the binding ability of erianin with its potential targets, molecular flexible docking was performed using Discovery Studio (DS). The valuable targets obtained from the above analysis and verification were further mapped to the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway using the Database for Annotation, Visualization and Integrated Discovery (DAVID) (http://david.abcc.ncifcrf.gov/) to explore the possible signaling pathways disturbed/regulated by erianin. Furthermore, the in silico prediction of absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of erianin was also performed and provided in this paper. Overall, in this study, we aimed at 1) collecting all experiment-based important information regarding the anticancer effect and pharmacological mechanism of erianin, 2) providing the predicted therapeutic targets and signaling pathways that erianin might act on in cancers, and 3) especially providing in silico ADMET properties of erianin.