Costunolide covalently targets NACHT domain of NLRP3 to inhibit inflammasome activation and alleviate NLRP3-driven inflammatory diseases

Aucklandiae radix targeted PKM2 to alleviate ulcerative colitis: Insights from the photocrosslinking target fishing technique

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic and relapsing disease marked by chronic tissue inflammation that alters the integrity and function of the gut, seriously impacting patient health and quality of life. Aucklandiae Radix (AR), known as Mu Xiang in Chinese, is a traditional Chinese medicine documented in Chinese Pharmacopoeia with effects of strengthening the intestine and stopping diarrhea. However, the potential of AR in treating intestinal inflammation and its underlying mechanism have yet to be further elucidated.

PURPOSE

The objective of this study was to explore the protective effect and the potential mechanism attributable to AR for treating ulcerative colitis (UC).

STUDY DESIGN AND METHODS

A murine model of UC was constructed using dextran sulfate sodium (DSS) to examine the therapeutic potential of AR in alleviating inflammation and modulating the immune response. Advanced techniques such as photocrosslinking target fishing technique, click chemistry, Western blot analysis, real-time quantitative PCR, flow cytometry, immunofluorescence, and immunohistochemistry were employed to unveil the therapeutic mechanism of AR for treating IBD.

RESULTS

AR decreased disease activity index (DAI) score to alleviate the course of IBD through ameliorating intestinal barrier function in DSS-induced mice. Furthermore, AR suppressed NF-κB and NLRP3 pathways to reduce the release of pro-inflammatory factors interleukin-6 and 1β (IL-6 and IL-1β) and tumor necrosis factor α (TNF-α), allowing to alleviate the inflammatory response. Flow cytometry revealed that AR could reduce the accumulation of intestinal macrophages and neutrophils, maintaining intestinal immune balance by regulating the ratio of Treg to Th17 cells. It was worth noting that pyruvate kinase isozyme type M2 (PKM2) served as a potential target of AR using the photocrosslinking target fishing technology, which was further supported by cellular thermal shift assay (CETSA), drug affinity target stability (DARTS), and PKM2 knockdown experiments.

CONCLUSION

AR targeted PKM2 to inhibit NF-κB and NLRP3 pathways, thereby modulating the inflammatory response and immunity to alleviate DSS-induced UC. These findings suggested the potential of AR in the treatment of UC and AR as a candidate for developing PKM2 regulators.

Mesenchymal stem cells and their extracellular vesicles in bone and joint diseases: targeting the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a cytosolic multi-subunit protein complex, and recent studies have demonstrated the vital role of the NLRP3 inflammasome in the pathological and physiological conditions, which cleaves gasdermin D to induce inflammatory cell death called pyroptosis and mediates the release of interleukin-1 beta and interleukin-18 in response to microbial infection or cellular injury. Over-activation of the NLRP3 inflammasome is associated with the pathogenesis of many disorders affecting bone and joints, including gouty arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis, and periodontitis. Moreover, mesenchymal stem cells (MSCs) have been discovered to facilitate the inhibition of NLRP3 and maybe ideal for treating bone and joint diseases. In this review, we implicate the structure and activation of the NLRP3 inflammasome along with the detail on the involvement of NLRP3 inflammasome in bone and joint diseases pathology. In addition, we focused on MSCs and MSC-extracellular vesicles targeting NLRP3 inflammasomes in bone and joint diseases. Finally, the existing problems and future direction are also discussed.

Heme oxygenase 1-mediated ferroptosis in Kupffer cells initiates liver injury during heat stroke

With the escalating prevalence of global heat waves, heat stroke has become a prominent health concern, leading to substantial liver damage. Unlike other forms of liver injury, heat stroke-induced damage is characterized by heat cytotoxicity and heightened inflammation, directly contributing to elevated mortality rates. While clinical assessments have identified elevated bilirubin levels as indicative of Kupffer cell dysfunction, their specific correlation with heat stroke liver injury remains unclear. Our hypothesis proposes the involvement of Kupffer cell ferroptosis during heat stroke, initiating IL-1β-mediated inflammation. Using single-cell RNA sequencing of murine macrophages, a distinct and highly susceptible Kupffer cell subtype, Clec4F+/CD206+, emerged, with heme oxygenase 1 (HMOX-1) playing a pivotal role. Mechanistically, heat-induced HMOX-1, regulated by early growth response factor 1, mediated ferroptosis in Kupffer cells, specifically in the Clec4F+/CD206+ subtype (KC2), activating phosphatidylinositol 4-kinase beta and promoting PI4P production. This cascade triggered NLRP3 inflammasome activation and maturation of IL-1β. These findings underscore the critical role of targeted therapy against HMOX-1 in ferroptosis within Kupffer cells, particularly in Clec4F+/CD206+ KCs. Such an approach has the potential to mitigate inflammation and alleviate acute liver injury in the context of heat stroke, offering a promising avenue for future therapeutic interventions.

The glycolytic metabolite methylglyoxal covalently inactivates the NLRP3 inflammasome

The NLRP3 inflammasome promotes inflammation in disease, yet the full repertoire of mechanisms regulating its activity is not well delineated. Among established regulatory mechanisms, covalent modification of NLRP3 has emerged as a common route for the pharmacological inactivation of this protein. Here, we show that inhibition of the glycolytic enzyme phosphoglycerate kinase 1 (PGK1) results in the accumulation of methylglyoxal, a reactive metabolite whose increased levels decrease NLRP3 assembly and inflammatory signaling in cells. We find that methylglyoxal inactivates NLRP3 via a non-enzymatic, covalent-crosslinking-based mechanism, promoting inter- and intraprotein MICA (methyl imidazole crosslink between cysteine and arginine) posttranslational linkages within NLRP3. This work establishes NLRP3 as capable of sensing a host of electrophilic chemicals, both exogenous small molecules and endogenous reactive metabolites, and suggests a mechanism by which glycolytic flux can moderate the activation status of a central inflammatory signaling pathway.

Design, Synthesis, and Biological Evaluation of Ferulic Acid-Piperazine Derivatives Targeting Pathological Hallmarks of Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent cause of dementia and is characterized by low levels of acetyl and butyrylcholine, increased oxidative stress, inflammation, accumulation of metals, and aggregations of Aβ and tau proteins. Current treatments for AD provide only symptomatic relief without impacting the pathological hallmarks of the disease. In our ongoing efforts to develop naturally inspired novel multitarget molecules for AD, through extensive medicinal chemistry efforts, we have developed 13a, harboring the key functional groups to provide not only symptomatic relief but also targeting oxidative stress, able to chelate iron, inhibiting NLRP3, and Aβ1-42 aggregation in various AD models. 13a exhibited promising anticholinesterase activity against AChE (IC50 = 0.59 ± 0.19 μM) and BChE (IC50 = 5.02 ± 0.14 μM) with excellent antioxidant properties in DPPH assay (IC50 = 5.88 ± 0.21 μM) over ferulic acid (56.49 ± 0.62 μM). The molecular docking and dynamic simulations further corroborated the enzyme inhibition studies and confirmed the stability of these complexes. Importantly, in the PAMPA-BBB assay, 13a turned out to be a promising molecule that can efficiently cross the blood-brain barrier. Notably, 13a also exhibited iron-chelating properties. Furthermore, 13a effectively inhibited self- and metal-induced Aβ1-42 aggregation. It is worth mentioning that 13a demonstrated no symptom of cytotoxicity up to 30 μM concentration in PC-12 cells. Additionally, 13a inhibited the NLRP3 inflammasome and mitigated mitochondrial-induced reactive oxygen species and mitochondrial membrane potential damage triggered by LPS and ATP in HMC-3 cells. 13a could effectively reduce mitochondrial and cellular reactive oxygen species (ROS) in the Drosophila model of AD. Finally, 13a was found to be efficacious in reversing memory impairment in a scopolamine-induced AD mouse model in the in vivo studies. In ex vivo assessments, 13a notably modulates the levels of superoxide, catalase, and malondialdehyde along with AChE and BChE. These findings revealed that 13a holds promise as a potential candidate for further development in AD management.

Chloranthalactone B covalently binds to the NACHT domain of NLRP3 to attenuate NLRP3-driven inflammation

NLRP3 inflammasome plays an important role in autoimmunity and the dysregulation of NLRP3 inflammasome can lead to various human diseases. Natural products are an important source for the discovery of safe and effective inflammatory inhibitors. Chloranthalactone B (CTB), a lindenane sesquiterpenoid (LS) from a common traditional Chinese medicine (TCM) (Sarcandra glabra), could significantly inhibit the level of IL-1β. This study aims to investigate the anti-inflammatory mechanism and target of CTB and its therapeutic effects on inflammatory diseases. CTB significantly inhibited IL-1β secretion induced by different agonists. Co-IP and flow cytometry results showed that CTB inhibited NLRP3-NEK7 interactions, but had no significant effect on upstream events. Pull-down, DARTS, CETSA, biolayer interferometry assay (BLI), and LC/MS/MS results showed that CTB could covalently bind to cysteine 279 (Cys279) in the NACHT domain of NLRP3. The result of the chemical modification indicated that the epoxide motif was the key group of CTB for its anti-inflammatory effect of CTB. Further animal studies showed that CTB significantly reduced the symptoms and inflammation levels of gout, peritonitis, and acute lung injury. However, the protective effect of CTB against peritonitis and gout was abolished in NLRP3-knocked out (NLRP3 KO) mice. Overall, our research revealed that CTB was a specific NLRP3 covalent inhibitor, and epoxide motif was an active pharmacophore that covalently binds to NLRP3, which provided new insights in designing new NLRP3 inhibitors for treating NLRP3-driven diseases.

Small molecule α-methylene-γ-butyrolactone, an evolutionarily conserved moiety in sesquiterpene lactones, ameliorates arthritic phenotype via interference DNA binding activity of NF-κB

Rheumatoid arthritis (RA) is an inflammatory disease accompanied by abnormal synovial microenvironment (SM). Sesquiterpene lactones (SLs) are the main anti-inflammatory ingredients of many traditional herbs utilized in RA treatment. α-Methylene-γ-butyrolactone (α-M-γ-B) is a core moiety that widely exists in natural SLs. This study was designed to investigate the anti-arthritic potential of α-M-γ-B as an independent small molecule in vitro and in vivo. α-M-γ-B exhibited stronger electrophilicity and anti-inflammatory effects than the other six analogs. α-M-γ-B inhibited the production of pro-inflammatory mediators via repolarizing M1 macrophages into M2 macrophages. The transcriptome sequencing suggested that α-M-γ-B regulated the immune system pathway. Consistently, α-M-γ-B attenuated collagen type II-induced arthritic (CIA) phenotype, restored the balance of Tregs-macrophages and remodeled SM via repolarizing the synovial-associated macrophages in CIA mice. Mechanistically, although α-M-γ-B did not prevent the trans-nucleus of NF-κB it interfered with the DNA binding activity of NF-κB via direct interaction with the sulfhydryl in cysteine residue of NF-κB p65, which blocked the activation of NF-κB. Inhibition of NF-κB reduced the M1 polarization of macrophage and suppressed the synovial hyperplasia and angiogenesis. α-M-γ-B failed to ameliorate CIA in the presence of N-acetylcysteine or when the mice were subjected to the macrophage-specific deficiency of Rela. In conclusion, α-M-γ-B significantly attenuated the CIA phenotype by directly targeting NF-κB p65 and inhibiting its DNA binding ability. These results suggest that α-M-γ-B has the potential to serve as an alternative candidate for treating RA. The greater electrophilicity of α-M-γ-B, the basis for triggering strong anti-inflammatory activity, accounts for the reason why α-M-γ-B is evolutionarily conserved in the SLs by medical plants.

Costunolide ameliorates MNNG-induced chronic atrophic gastritis through inhibiting oxidative stress and DNA damage via activation of Nrf2

BACKGROUND

Chronic atrophic gastritis (CAG) is a chronic digestive disease. Modern research has revealed substantial evidence indicating that the progression of CAG is closely linked to the occurrence of oxidative stress-induced DNA damage and apoptosis in the gastric mucosa. Additionally, research has indicated that Costunolide (COS), the primary active compound found in Aucklandiae Radix, a traditional herb, exhibits antioxidant properties. Nevertheless, the therapeutic potential of COS in treating CAG and its molecular targets have not yet been determined.

PURPOSE

The objective of this research was to explore the potential gastric mucosal protective effects and mechanisms of COS against N-Methyl-N´-nitro-N-nitrosoguanidine (MNNG)-induced CAG.

METHODS

Firstly, the MNNG-induced rat CAG model was established in vivo. Occurrence of CAG was detected through macroscopic examination of the stomachs and H&E staining. Additionally, we assessed oxidative stress, DNA damage, and apoptosis using biochemical detection, Western blot, immunohistochemistry and immunofluorescence. Then, an in vitro model was developed to induce MNNG-induced damage in GES-1 cells, and the occurrence of cell damage was determined by Hoechst 33,342 staining and flow cytometry. Finally, the key targets of COS for the treatment of CAG were identified through molecular docking, cellular thermal shift assay (CETSA), and inhibitor ML385.

RESULTS

In vivo studies demonstrated that COS promotes the expression of Nrf2 in gastric tissues. This led to an increased expression of SOD, GSH, HO-1, while reducing the production of MDA. Furthermore, COS inhibited DNA damage and apoptosis by suppressing the expression of γH2AX and PARP1 in gastric tissues. In vitro studies showed that COS effectively reversed apoptosis induced by MNNG in GES-1 cells. Additionally, COS interacted with Nrf2 to promote its expression. Furthermore, the expression levels of SOD, GSH, and HO-1 were augmented, while the generation of ROS and MDA was diminished.

CONCLUSIONS

Our results indicate that COS exhibits therapeutic effects on CAG through the promotion of Nrf2 expression and inhibition of oxidative stress and DNA damage. Therefore, COS has the potential to provide new drugs for the treatment of CAG.

Gingerenone A Attenuates Ulcerative Colitis via Targeting IL-17RA to Inhibit Inflammation and Restore Intestinal Barrier Function

Ulcerative colitis (UC) is a complicated and recurrent intestinal disease. Currently available drugs for UC treatment are scarce, therefore, novel therapeutic drugs for the UC are urgently to be developed. Gingerenone A (GA) is a phenolic compound known for its anti-inflammatory effect, but its effect on UC remains unknown. Here, it is shown that GA protects mice against UC, which is closely associated with inhibiting intestinal mucosal inflammation and enhancing intestinal barrier integrity in vivo and in vitro. Of note, RNA sequencing analysis demonstrates an evident correlation with IL-17 signaling pathway after GA treatment, and this effect is further corroborated by Western blot. Mechanistically, GA directly interacts with IL-17RA protein through pull-down, surface plasmon resonance analysis and molecular dynamics simulation. Importantly, lentivirus-mediated IL-17RA/Act1 knock-down or GA co-treatment with brodalumab/ixekizumab significantly impairs the protective effects of GA against DSS-induced inflammation and barrier dysfunction, suggesting a critical role of IL-17RA signaling for GA-mediated protection against UC. Overall, these results indicate that GA is an effective agent against UC mainly through the direct binding of IL-17RA to inhibit inflammatory signaling activation.

Protective effects of sinomenine against dextran sulfate sodium-induced ulcerative colitis in rats via alteration of HO-1/Nrf2 and inflammatory pathway

BACKGROUND

Dextran Sulfate Sodium (DSS) induces ulcerative colitis (UC), a type of inflammatory bowel disease (IBD) that leads to inflammation, swelling, and ulcers in the large intestine. The aim of this experimental study is to examine how sinomenine, a plant-derived alkaloid, can prevent or reduce the damage caused by DSS in the colon and rectum of rats.

MATERIAL AND METHODS

Induction of ulcerative colitis (UC) in rats was achieved by orally administering a 2% Dextran Sulfate Sodium (DSS) solution, while the rats concurrently received oral administrations of sinomenine and sulfasalazine. The food, water intake was estimated. The body weight, disease activity index (DAI), colon length and spleen index estimated. Antioxidant, cytokines, inflammatory parameters and mRNA expression were estimated. The composition of gut microbiota was analyzed at both the phylum and genus levels in the fecal samples obtained from all groups of rats.

RESULTS

Sinomenine treatment enhanced the body weight, colon length and reduced the DAI, spleen index. Sinomenine treatment remarkably suppressed the level of NO, MPO, ICAM-1, and VCAM-1 along with alteration of antioxidant parameters such as SOD, CAT, GPx, GR and MDA. Sinomenine treatment also decreased the cytokines like TNF-α, IL-1, IL-1β, IL-6, IL-10, IL-17, IL-18 in the serum and colon tissue; inflammatory parameters viz., PAF, COX-2, PGE2, iNOS, NF-κB; matrix metalloproteinases level such as MMP-1 and MMP-2. Sinomenine significantly (P < 0.001) enhanced the level of HO-1 and Nrf2. Sinomenine altered the mRNA expression of RIP1, RIP3, DRP3, NLRP3, IL-1β, caspase-1 and IL-18. Sinomenine remarkably altered the relative abundance of gut microbiota like firmicutes, Bacteroidetes, F/B ratio, Verrucomicrobia, and Actinobacteria.

CONCLUSION

The results clearly indicate that sinomenine demonstrated a protective effect against DSS-induced inflammation, potentially through the modulation of inflammatory pathways and gut microbiota.

A Perfect Storm: The Convergence of Aging, Human Immunodeficiency Virus Infection, and Inflammasome Dysregulation

The emergence of combination antiretroviral therapy (cART) has greatly transformed the life expectancy of people living with HIV (PWH). Today, over 76% of the individuals with HIV have access to this life-saving therapy. However, this progress has come with a new challenge: an increase in age-related non-AIDS conditions among patients with HIV. These conditions manifest earlier in PWH than in uninfected individuals, accelerating the aging process. Like PWH, the uninfected aging population experiences immunosenescence marked by an increased proinflammatory environment. This phenomenon is linked to chronic inflammation, driven in part by cellular structures called inflammasomes. Inflammatory signaling pathways activated by HIV-1 infection play a key role in inflammasome formation, suggesting a crucial link between HIV and a chronic inflammatory state. This review outlines the inflammatory processes triggered by HIV-1 infection and aging, with a focus on the inflammasomes. This review also explores current research regarding inflammasomes and potential strategies for targeting inflammasomes to mitigate inflammation. Further research on inflammasome signaling presents a unique opportunity to develop targeted interventions and innovative therapeutic modalities for combating HIV and aging-associated inflammatory processes.

The specialized sesquiterpenoids produced by the genus Elephantopus L.: Chemistry, biological activities and structure-activity relationship exploration

The genus Elephantopus L. is a valuable resource rich in sesquiterpenoids with structural diversity and various bioactivities, showing great potential for applications in medicinal field and biological industry. Up to now, over 129 sesquiterpenoids have been isolated and identified from this plant genus, including 114 germacrane-type, 7 guaianolide-type, 5 eudesmane-type, 1 elemanolide-type, and 2 bis-sesquiterpenoids. These sesquiterpenoids were reported to show a diverse range of pharmacological properties, including cytotoxic, anti-tumor, anti-inflammatory, antimicrobial, and antiprotozoal. Consequently, some of them were identified as active scaffolds in the design and development of drugs. Considering that there is currently no overview available that covers the sesquiterpenoids and their biological activities in the Elephantopus genus, this article aims to comprehensively review the chemical structures, biosynthetic pathways, pharmacological properties, and structure-activity relationship of sesquiterpenoids found in the Elephantopus genus, which will establish a theoretical framework that can guide further research and exploration of sesquiterpenoids from Elephantopus plants as promising therapeutic agents.

Asiaticoside exerts neuroprotection through targeting NLRP3 inflammasome activation

BACKGROUND

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by motor symptoms due to the progressive loss of dopaminergic neurons in the substantia nigra (SN) and striatum (STR), alongside neuroinflammation. Asiaticoside (AS), a primary active component with anti-inflammatory and neuroprotective properties, is derived from Centella asiatica. However, the precise mechanisms through which AS influences PD associated with inflammation are not yet fully understood.

PURPOSE

This study aimed to explore the protective mechanism of AS in PD.

METHODS

Targets associated with AS and PD were identified from the Swiss Target Prediction, Similarity Ensemble Approach, PharmMapper, and GeneCards database. A protein-protein interaction (PPI) network was constructed to identify potential therapeutic targets. Concurrently, GO and KEGG analyses were performed to predict potential signaling pathways. To validate these mechanisms, the effects of AS on 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD in mice were investigated. Furthermore, neuroinflammation and the activation of the NLRP3 inflammasome were assessed to confirm the anti-inflammatory properties of AS. In vitro experiments in BV2 cells were then performed to investigate the mechanisms of AS in PD. Moreover, CETSA, molecular docking, and molecular dynamics simulations (MDs) were performed for further validation.

RESULTS

Network pharmacology analysis identified 17 potential targets affected by AS in PD. GO and KEGG analyses suggested the biological roles of these targets, demonstrating that AS interacts with 149 pathways in PD. Notably, the NOD-like receptor signaling pathway was identified as a key pathway mediating AS's effect on PD. In vivo studies demonstrated that AS alleviated motor dysfunction and reduced the loss of dopaminergic neurons in MPTP-induced PD mice. In vitro experiments demonstrated that AS substantially decreased IL-1β release in BV2 cells, attributing this to the modulation of the NLRP3 signaling pathway. CETSA and molecular docking studies indicated that AS forms a stable complex with NLRP3. MDs suggested that ARG578 played an important role in the formation of the complex.

CONCLUSION

In this study, we first predicted that the potential target and pathway of AS's effect on PD could be NLRP3 protein and NOD-like receptor signaling pathway by network pharmacology analysis. Further, we demonstrated that AS could alleviate symptoms of PD induced by MPTP through its interaction with the NLRP3 protein for the first time by in vivo and in vitro experiments. By binding to NLRP3, AS effectively inhibits the assembly and activation of the inflammasome. These findings suggest that AS is a promising inhibitor for PD driven by NLRP3 overactivation.

Novel Isoalantolactone-Based Derivatives as Potent NLRP3 Inflammasome Inhibitors: Design, Synthesis, and Biological Characterization

The NLRP3 inflammasome has been recognized as a promising therapeutic target in drug discovery for inflammatory diseases. Our initial research identified a natural sesquiterpene isoalantolactone (IAL) as the active scaffold targeting NLRP3 inflammasome. To improve its activity and metabolic stability, a total of 64 IAL derivatives were designed and synthesized. Among them, compound 49 emerged as the optimal lead, displaying the most potent inhibitory efficacy on nigericin-induced IL-1β release in THP-1 cells, with an IC50 value of 0.29 μM, approximately 27-fold more potent than that of IAL (IC50: 7.86 μM), and exhibiting higher metabolic stability. Importantly, 49 remarkably improved DSS-induced ulcerative colitis in vivo. Mechanistically, we demonstrated that 49 covalently bound to cysteine 279 in the NACHT domain of NLRP3, thereby inhibiting the assembly and activation of NLRP3 inflammasome. These results provided compelling evidence to further advance the development of more potent NLRP3 inhibitors based on this scaffold.

The Glycolytic Metabolite Methylglyoxal Covalently Inactivates the NLRP3 Inflammasome

The NLRP3 inflammasome promotes inflammation in disease, yet the full repertoire of mechanisms regulating its activity are not well delineated. Among established regulatory mechanisms, covalent modification of NLRP3 has emerged as a common route for pharmacological inactivation of this protein. Here, we show that inhibition of the glycolytic enzyme PGK1 results in the accumulation of methylglyoxal, a reactive metabolite whose increased levels decrease NLRP3 assembly and inflammatory signaling in cells. We find that methylglyoxal inactivates NLRP3 via a non-enzymatic, covalent crosslinking-based mechanism, promoting inter- and intra-protein MICA posttranslational linkages within NLRP3. This work establishes NLRP3 as capable of sensing a host of electrophilic chemicals, both exogenous small molecules and endogenous reactive metabolites, and suggests a mechanism by which glycolytic flux can moderate the activation status of a central inflammatory signaling pathway.

Britannin as a novel NLRP3 inhibitor, suppresses inflammasome activation in macrophages and alleviates NLRP3-related diseases in mice

Overactivation of the NLRP3 inflammasomes induces production of pro-inflammatory cytokines and drives pathological processes. Pharmacological inhibition of NLRP3 is an explicit strategy for the treatment of inflammatory diseases. Thus far no drug specifically targeting NLRP3 has been approved by the FDA for clinical use. This study was aimed to discover novel NLRP3 inhibitors that could suppress NLRP3-mediated pyroptosis. We screened 95 natural products from our in-house library for their inhibitory activity on IL-1β secretion in LPS + ATP-challenged BMDMs, found that Britannin exerted the most potent inhibitory effect with an IC50 value of 3.630 µM. We showed that Britannin (1, 5, 10 µM) dose-dependently inhibited secretion of the cleaved Caspase-1 (p20) and the mature IL-1β, and suppressed NLRP3-mediated pyroptosis in both murine and human macrophages. We demonstrated that Britannin specifically inhibited the activation step of NLRP3 inflammasome in BMDMs via interrupting the assembly step, especially the interaction between NLRP3 and NEK7. We revealed that Britannin directly bound to NLRP3 NACHT domain at Arg335 and Gly271. Moreover, Britannin suppressed NLRP3 activation in an ATPase-independent way, suggesting it as a lead compound for design and development of novel NLRP3 inhibitors. In mouse models of MSU-induced gouty arthritis and LPS-induced acute lung injury (ALI), administration of Britannin (20 mg/kg, i.p.) significantly alleviated NLRP3-mediated inflammation; the therapeutic effects of Britannin were dismissed by NLRP3 knockout. In conclusion, Britannin is an effective natural NLRP3 inhibitor and a potential lead compound for the development of drugs targeting NLRP3.

Exploration of costunolide derivatives as potential anti-inflammatory agents for topical treatment of atopic dermatitis by inhibiting MAPK/NF-κB pathways

Atopic dermatitis (AD) is a common inflammatory disease and it is very difficult to treat. In the present work, a series of costunolide derivatives have been prepared, and in vitro and in vivo anti-inflammatory activities have evaluated. The results showed that most derivatives displayed good inhibition of NO generation with low cytotoxicity, and 7d could inhibit the phosphorylation of P38, P65 NF-κB and IκB-α in LPS-induced RAW264.7 model. The in vivo researches showed that 7d could improve skin injury symptoms, decrease Th2-type cytokine levels, inhibit HIS levels, alleviate scratching and repaire the damaged skin barrier through the inhibition of phosphorylation of MAPK and NF-κB signaling pathways on MC903-induced AD model. Therefore, costunolide derivatives may be new potent anti-AD agents for further study.

Costunolide attenuates high-fat diet-induced inflammation and oxidative stress in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a progressive disease that can further evolve towards liver fibrosis and hepatocellular carcinoma in the end stage. Costunolide (Cos) is a natural sesquiterpene lactone that exhibits both anti-inflammatory and antioxidant properties. However, the therapeutic effect of Cos on NAFLD is not clear. In this study, we explored the potential protective effect and mechanism of Cos on NAFLD. C57BL/6 mice were fed with high-fat diet (HFD) to induce NAFLD. Cos was administered by gavage to observe the effect of Cos on NAFLD. We demonstrated that oral administration of Cos reduced HFD-induced hepatic fibrosis and the release of inflammatory cytokines, limiting the generation of reactive oxygen species. In vitro experiments revealed that pretreatment with Cos significantly decreased PA-induced production of inflammatory cytokines and fibrosis in AML-12 cells. Mechanism study showed that the effect of Cos was correlated to the induction of Nrf-2 and inhibition of NF-κB pathways. Collectively, these findings indicated that Cos exerts hepatoprotective effect against NAFLD through blocking inflammation and oxidative stress. Our study suggested that Cos might be an effective pharmacotherapy for the treatment of NAFLD.

The roles of ubiquitination and deubiquitination of NLRP3 inflammasome in inflammation-related diseases: A review

The inflammatory response is a natural immune response that prevents microbial invasion and repairs damaged tissues. However, excessive inflammatory responses can lead to various inflammation-related diseases, posing a significant threat to human health. The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is a vital mediator in the activation of the inflammatory cascade. Targeting the hyperactivation of the NLRP3 inflammasome may offer potential strategies for the prevention or treatment of inflammation-related diseases. It has been established that the ubiquitination and deubiquitination modifications of the NLRP3 inflammasome can provide protective effects in inflammation-related diseases. These modifications modulate several pathological processes, including excessive inflammatory responses, pyroptosis, abnormal autophagy, proliferation disorders, and oxidative stress damage. Therefore, this review discusses the regulation of NLRP3 inflammasome activation by ubiquitination and deubiquitination modifications, explores the role of these modifications in inflammation-related diseases, and examines the potential underlying mechanisms.

The role of inflammasomes in human diseases and their potential as therapeutic targets

Inflammasomes are large protein complexes that play a major role in sensing inflammatory signals and triggering the innate immune response. Each inflammasome complex has three major components: an upstream sensor molecule that is connected to a downstream effector protein such as caspase-1 through the adapter protein ASC. Inflammasome formation typically occurs in response to infectious agents or cellular damage. The active inflammasome then triggers caspase-1 activation, followed by the secretion of pro-inflammatory cytokines and pyroptotic cell death. Aberrant inflammasome activation and activity contribute to the development of diabetes, cancer, and several cardiovascular and neurodegenerative disorders. As a result, recent research has increasingly focused on investigating the mechanisms that regulate inflammasome assembly and activation, as well as the potential of targeting inflammasomes to treat various diseases. Multiple clinical trials are currently underway to evaluate the therapeutic potential of several distinct inflammasome-targeting therapies. Therefore, understanding how different inflammasomes contribute to disease pathology may have significant implications for developing novel therapeutic strategies. In this article, we provide a summary of the biological and pathological roles of inflammasomes in health and disease. We also highlight key evidence that suggests targeting inflammasomes could be a novel strategy for developing new disease-modifying therapies that may be effective in several conditions.

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.

Advances in the roles of ATF4 in osteoporosis

Osteoporosis (OP) is characterized by reduced bone mass, decreased strength, and enhanced bone fragility fracture risk. Activating transcription factor 4 (ATF4) plays a role in cell differentiation, proliferation, apoptosis, redox balance, amino acid uptake, and glycolipid metabolism. ATF4 induces the differentiation of bone marrow mesenchymal stem cells (BM-MSCs) into osteoblasts, increases osteoblast activity, and inhibits osteoclast formation, promoting bone formation and remodeling. In addition, ATF4 mediates the energy metabolism in osteoblasts and promotes angiogenesis. ATF4 is also involved in the mediation of adipogenesis. ATF4 can selectively accumulate in osteoblasts. ATF4 can directly interact with RUNT-related transcription factor 2 (RUNX2) and up-regulate the expression of osteocalcin (OCN) and osterix (Osx). Several upstream factors, such as Wnt/β-catenin and BMP2/Smad signaling pathways, have been involved in ATF4-mediated osteoblast differentiation. ATF4 promotes osteoclastogenesis by mediating the receptor activator of nuclear factor κ-B (NF-κB) ligand (RANKL) signaling. Several agents, such as parathyroid (PTH), melatonin, and natural compounds, have been reported to regulate ATF4 expression and mediate bone metabolism. In this review, we comprehensively discuss the biological activities of ATF4 in maintaining bone homeostasis and inhibiting OP development. ATF4 has become a therapeutic target for OP treatment.

Target discovery of bioactive natural products with native-compound-coupled CNBr-activated Sepharose 4B beads (NCCB): Applications, mechanisms and outlooks

Natural products (NPs) represent a treasure trove for drug discovery and development due to their chemical structural diversity and a broad spectrum of biological activities. Uncovering the biological targets and understanding their molecular mechanism of actions are crucial steps in the development of clinical therapeutics. However, the structural complexity of NPs and intricate nature of biological system present formidable challenges in target identification of NPs. Although significant advances have been made in the development of new chemical tools, these methods often require high levels of synthetic skills for preparing chemical probes. This can be costly and time-consuming relaying on operationally complicated procedures and instruments. In recent efforts, we and others have successfully developed an operationally simple and practical chemical tool known as native-compound-coupled CNBr-activated Sepharose 4B beads (NCCB) for NP target identification. In this approach, a native compound readily reacts with commercial CNBr-activated Sepharose 4B beads with a process that is easily performed in any biology laboratory. Based on NCCB, our group has identified the direct targets of more than 60 NPs. In this review, we will elucidate the application scopes, including flavonoids, quinones, terpenoids and others, characteristics, chemical mechanisms, procedures, advantages, disadvantages, and future directions of NCCB in specific target discovery.

Discovery of NLRP3 inhibitors using machine learning: Identification of a hit compound to treat NLRP3 activation-driven diseases

NLRP3 is vital in developing many human diseases as one of the most critical inflammasomes. Developing related inhibitors has been instrumental in advancing the development of therapies for associated diseases. To date, there are no NLRP3 inhibitors on the market. This study identified a series of NLRP3 inhibitors using the self-developed machine learning model. Among them, CSC-6 was validated as the hit molecule with optimal activity and significantly inhibited IL-1β secreted by PMA-THP-1 cells (IC50 = 2.3 ± 0.38 μM). The results show that CSC-6 specifically binds NLRP3 and inhibits NLRP3 activation by blocking ASC oligomerization during NLRP3 assembly. In vivo experiments have demonstrated that CSC-6 effectively reduces the symptoms of NLRP3 overactivation-mediated sepsis and Gout in mouse models. Importantly, CSC-6 has lower cytotoxicity and exhibits better stability in human-derived liver microsomes, which is more favorable for the drug to maintain its efficacy in vivo for longer. The discovery of CSC-6 may contribute to the design and discovery of related NLRP3 inhibitors.

A natural sesquiterpene lactone isolinderalactone attenuates lipopolysaccharide-induced inflammatory response and acute lung injury through inhibition of NF-κB pathway and activation Nrf2 pathway in macrophages

Isolinderalactone is the main sesquiterpene lactone isolated from Lindera aggregata, a traditional Chinese medicine widely used to treat pain and inflammation. Although isolinderalactone has been demonstrated to possess anti-cancer effect, its anti-inflammatory activity and underlying mechanism has not been well characterized. Herein, isolinderalactone was able to significantly inhibit the production of NO and PGE2 by reducing the expressions of iNOS and COX2 in LPS-stimulated RAW264.7 macrophages and BMDMs, and decreased the mRNA levels of IL-1β, IL-6, and TNF-α in LPS-induced RAW264.7 cells. In vivo, isolinderalactone effectively alleviated LPS-induced acute lung injury (ALI), which manifested as reduction in pulmonary inflammatory infiltration, myeloperoxidase activity, and production of PGE2, IL-1β, IL-6, TNF-α, and malondialdehyde. Furthermore, isolinderalactone inhibited phosphorylation of IKKα/β, phosphorylation and degradation of IκBα, and nuclear translocation of NF-κB p65, thereby blocking NF-κB pro-inflammatory pathway. Meanwhile, isolinderalactone reduced the intracellular ROS through promoting the activation of Nrf2-HMOX1 antioxidant axis. By using drug affinity responsive target stability assay and molecular docking, isolinderalactone was found to covalently interact with IKKα/β and Keap1, which may contribute to its anti-inflammatory action. Additionally, a thiol donor β-mercaptoethanol significantly abolished isolinderalactone-mediated anti-inflammatory action in vitro, indicating the crucial role of the unsaturated lactone of isolinderalactone on its anti-inflammatory effects. Taken together, isolinderalactone protected against LPS-induced ALI in mice, which may be associated with its inhibition of NF-κB pathway and activation of Nrf2 signaling in macrophages.

Novel MAGL Inhibitors Alleviate LPS-Induced Acute Kidney Injury by Inhibiting NLRP3 Inflammatory Vesicles, Modulating Intestinal Flora, Repairing the Intestinal Barrier, and Interfering with Serum Metabolism

Acute kidney injury (AKI) is a complication of a wide range of serious illnesses for which there is still no better therapeutic agent. We demonstrated that M-18C has a favorable inhibitory effect on monoacylglycerol lipase (MAGL), and several studies have demonstrated that nerve inflammation could be effectively alleviated by inhibiting MAGL, suggesting that M-18C has good anti-inflammatory activity. In this study, we investigated the effect of M-18C on LPS-induced acute kidney injury (AKI), both in vivo and in vitro, by using liquid chromatography-mass spectrometry (LC-MS), 16S rRNA gene sequencing, Western blot, and immunohistochemistry. The results showed that both in vivo and in vitro M-18C reduced the release of TNF-α and IL-1β by inhibiting the expression of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) and apoptosis-associated speck-like protein containing a CARD (ASC) protein; in addition, M-18C was able to intervene in LPS-induced AKI by ameliorating renal pathological injury, repairing the intestinal barrier, and regulating gut bacterial flora and serum metabolism. In conclusion, this study suggests that M-18C has the potential to be a new drug for the treatment of AKI.

Costunolide Protects Myocardium From Ischemia Reperfusion Injury by Inhibiting Oxidative Stress Through Nrf2/Keap1 Pathway Activation

ABSTRACT

Costunolide (Cos) is a naturally occurring sesquiterpene lactone that exhibits antioxidative properties. In this study, we demonstrate the protective mechanism of Cos against ischemia/reperfusion (I/R)-induced myocardial injury. Cos significantly decreased levels of reactive oxygen species and ameliorated apoptosis of I/R cardiomyocytes both in vitro and in vivo. Further investigation revealed that Cos increased expression of the antioxidant proteins HO-1 and NQO-1 and decreased the Bax/Bcl-2 ratio, thus protecting cardiac cells. NF-E2-related factor 2 (Nrf2) silencing significantly attenuated the protective effects of Cos in tert-butyl hydroperoxide (TBHP)-treated H9C2 cells. Additionally, Cos significantly intensified the I/R- or TBHP-induced dissociation of the Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 complex both in vitro and in vivo. These results suggest that activation of Nrf2/Keap1 using Cos may be a therapeutic strategy for myocardial I/R injury.

Exploring the inhibition mechanism of interleukin-1-beta in gouty arthritis by polygonum cuspidatum using network pharmacology and molecular docking: A review

Polygonum cuspidatum (Huzhang, HZ) is one of the commonly used traditional Chinese medicines for treating gouty arthritis (GA), but the specific mechanism is not clear. This study employed network pharmacology and molecular docking techniques to examine the molecular mechanisms underlying the therapeutic effects of HZ on GA. The network pharmacology approach, including active ingredient and target screening, drug-compound-target-disease network construction, protein-protein interaction (PPI) networks, enrichment analysis, and molecular docking, was used to explore the mechanism of HZ against GA. Ten active ingredients of HZ were predicted to interact with 191 targets, 14 of which interact with GA targets. Network pharmacology showed that quercetin, physovenine, luteolin, and beta-sitosterol are the core components of HZ, and IL (interleukin)-1β, IL-6, and tumor necrosis factor (TNF) are the core therapeutic targets. The mechanism of HZ in GA treatment was shown to be related to the IL-17 signaling pathway, NOD-like receptor signaling pathway, and Toll-like receptor signaling pathway, and is involved in the inflammatory response, positive regulation of gene expression, cellular response to lipopolysaccharide, and other biological processes. Molecular docking showed that all four core compounds had good binding properties to IL-1β, with luteolin and beta-sitosterol showing better docking results than anakinra, suggesting that they could be used as natural IL-1β inhibitors in further experimental studies. The mechanism of action of HZ against GA has multi-target and multi-pathway characteristics, which provides an important theoretical basis for the study of the active ingredients of HZ as natural IL-1β inhibitors.

Tabersonine, a natural NLRP3 inhibitor, suppresses inflammasome activation in macrophages and attenuate NLRP3-driven diseases in mice

Aberrant activation of NLRP3 inflammasome causes the progression of various inflammation-related diseases, but the small-molecule inhibitors of NLRP3 are not currently available for clinical use. Tabersonine (Tab) is a natural product derived from a traditional Chinese herb Catharanthus roseus that is usually used as an anti-tumor agent. In this study we investigated the anti-inflammatory effects and molecular targets of Tab. We first screened 151 in-house natural compounds for their inhibitory activity against IL-1β production in BMDMs. We found that Tab potently inhibited NLRP3-mediated IL-1β production with an IC50 value of 0.71 μM. Furthermore, we demonstrated that Tab suppressed the assembly of NLRP3 inflammasome, especially the interaction between NLRP3 and ASC. Interestingly, we found that Tab directly bound to NLRP3 NACHT domain, thereby reducing the self-oligomerization of NLRP3. In addition, we showed that administration of Tab significantly ameliorated NLRP3-driven diseases, such as peritonitis, acute lung injury, and sepsis in mouse models. The preventive effects of Tab were not observed in the models of NLRP3 knockout mouse. In conclusion, we have identified Tab as a natural NLRP3 inhibitor and a lead compound for the design and discovery of novel NLRP3 inhibitors.