Advances in the molecular mechanisms of NLRP3 inflammasome activators and inactivators

Full-spectrum cannabidiol reduces UVB damage through the inhibition of TGF-β1 and the NLRP3 inflammasome

The thermodynamic characteristics, antioxidant potential, and photoprotective benefits of full-spectrum cannabidiol (FS-CBD) against UVB-induced cellular death were examined in this study. In silico analysis of CBD showed antioxidant capacity via proton donation and UV absorption at 209.09, 254.73, and 276.95 nm, according to the HAT and SPLET methodologies. FS-CBD protected against UVB-induced bacterial death for 30 min. FS-CBD protected against UVB-induced cell death by 42% (1.5 μg/mL) and 35% (3.5 μg/mL) in an in vitro keratinocyte cell model. An in vivo acute irradiated CD-1et/et mouse model (UVB-irradiated for 5 min) presented very low photoprotection when FS-CBD was applied cutaneously, as determined by histological analyses. In vivo skin samples showed that FS-CBD regulated inflammatory responses by inhibiting the inflammatory markers TGF-β1 and NLRP3. The docking analysis showed that the CBD molecule had a high affinity for TGF-β1 and NLRP3, indicating that protection against inflammation might be mediated by blocking these proinflammatory molecules. This result was corroborated by the docking interactions between CBD and TGF-β1 and NLRP3, which resulted in a high affinity and inhibition of both proteins The present work suggested a FS-CBD moderate photoprotective agent against UVB light-induced skin damage and that this effect is partially mediated by its anti-inflammatory activity.

Biochemical and molecular determinants of the subclinical inflammatory mechanisms in Rett syndrome

To date, Rett syndrome (RTT), a genetic disorder mainly caused by mutations in the X-linked MECP2 gene, is increasingly considered a broad-spectrum pathology, instead of just a neurodevelopmental disease, due to the multitude of peripheral co-morbidities and the compromised metabolic pathways, affecting the patients. The altered molecular processes include an impaired mitochondrial function, a perturbed redox homeostasis, a chronic subclinical inflammation and an improper cholesterol metabolism. The persistent subclinical inflammatory condition was first defined ten years ago, as a previously unrecognized feature of RTT, playing a role in the pathology progress and modulation of phenotypical severity. In light of this, the present work aims at reviewing the current knowledge on the chronic inflammatory status and the altered immune/inflammatory functions in RTT, as well as investigating the emerging mechanisms underlying this condition with a special focus on the latest findings about inflammasome system, autoimmunity responses and intestinal micro- and mycobiota. On these bases, although further research is needed, future therapeutic strategies able to re-establish an adequate immune/inflammatory response could represent potential approaches for RTT patients.

Fucoidan modulates SIRT1 and NLRP3 to alleviate hypertensive retinopathy: in vivo and in vitro insights

BACKGROUND

Hypertension influences the inflammatory pathological changes in the retina. The function of the inflammasomes is significant. To see if Sirtuin 1 (SIRT1) regulates angiotensin II (Ang II)-induced hypertensive retinopathy and inflammation by modulating NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation and the potential protective effects of fucoidan (FO) in mouse retinal vascular endothelial cells (mRECs) and mice retina.

METHODS

The diagnosis of hypertensive retinopathy was made after three weeks of Ang II infusion (3000 ng/kg/min). One day prior to the commencement of Ang II infusion, the mice were treatment with NLRP3 inhibitor MCC950 (10 mg/kg/day, intraperitoneal injections) or FO (300 mg/kg/day, oral gavage). A blood pressure was recorded. Hematoxylin and eosin (H&E) staining was used to conduct pathological alterations, dihydroethidium bromide (DHE) was utilized to assess oxidative stress damage in the retina, and fluorescence angiography was used to identify vascular disorders in the eye. Using immunohistochemical labeling, NLRP3 expression was found. Reactive protein and mRNA expression levels in mouse retina and cells were assessed using Western blot and real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

NLRP3 inflammasome activation and SIRT1 decrease were brought about by Ang II infusion. Retinopathy and dysfunction were lessened by MCC950 target-induced NLRP3 inflammasome activation, while overexpression of SIRT1 had the opposite impact on NLRP3 inflammasome activation, indicating that SIRT1 functions as an upstream regulator of NLRP3 activity. FO may improve SIRT1 expression and decrease NLRP3 activation in retinopathy and dysfunction brought on by Ang II, and the effects were consistent across both in vivo and in vitro models.

CONCLUSIONS

SIRT1 adversely regulates the NLRP3 inflammasome pathway, which in turn increases Ang II-induced inflammation and hypertensive retinopathy. FO may mitigate Ang II-induced retinopathy and dysfunction via modulating the expression of SIRT1/NLRP3. This implies practical approaches to the management of hypertensive retinopathy.

Inhibition of NLRP3 inflammasome-A potential mechanistic therapeutic for treatment of polycystic ovary syndrome?

This review article explores the relationship between the NOD-like receptor protein 3 (NLRP3) inflammasome and the risk of developing polycystic ovary syndrome (PCOS). The NLRP3 inflammasome, a fundamental element of the innate immune system, plays a crucial role in the production of proinflammatory mediators and pyroptosis, a type inflammatory cell death. We conducted a thorough search on scientific databases to gather relevant information on this topic, utilizing relevant keywords. The reviewed studies indicated a correlation between PCOS and a higher incidence of granulosa cell (GC) death and the presence of ovarian tissue fibrosis. NLRP3 inflammasome stimulation and subsequent pyroptosis in GCs play a significant role in the pathophysiology of PCOS. Active NLRP3 inflammasome is involved in the production of inflammatory mediators like interleukin-1β (IL-1β) and IL-18, contributing to the development of PCOS, particularly in overweight patients. Therefore, inhibiting NLRP3 activation and pyroptosis could potentially offer novel therapeutic strategies for PCOS. Some limited studies have explored the use of agents with antioxidant and anti-inflammatory properties, as well as gene therapy approaches, to target the NLRP3 and pyroptosis signaling pathways. This study overview the understanding of the relationship between NLRP3 inflammasome activation, pyroptosis, and PCOS. It highlights the potential of targeting the NLRP3 inflammasome as an approach for treating PCOS. Nonetheless, further research and clinical trials are imperative to validate these results and explore the effectiveness of NLRP3 inflammasome inhibition in the management of PCOS.

Pharmacological targets at the lysosomal autophagy-NLRP3 inflammasome crossroads

Many aspects of cell homeostasis and integrity are maintained by the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome. The NLRP3 oligomeric protein complex assembles in response to exogenous and endogenous danger signals. This inflammasome has also been implicated in the pathogenesis of a range of disease conditions, particularly chronic inflammatory diseases. Given that NLRP3 modulates autophagy, which is also a key regulator of inflammasome activity, excessive inflammation may be controlled by targeting this intersecting pathway. However, specific niche areas of NLRP3-autophagy interactions and their reciprocal regulatory mechanisms remain underexplored. Consequently, we lack treatment methods specifically targeting this pivotal axis. Here, we discuss the potential of such strategies in the context of autoimmune and metabolic diseases and propose some research avenues.

NLRP3 inflammasome in cognitive impairment and pharmacological properties of its inhibitors

Cognitive impairment is a multifactorial and multi-step pathological process that places a heavy burden on patients and the society. Neuroinflammation is one of the main factors leading to cognitive impairment. The inflammasomes are multi-protein complexes that respond to various microorganisms and endogenous danger signals, helping to initiate innate protective responses in inflammatory diseases. NLRP3 inflammasomes produce proinflammatory cytokines (interleukin IL-1β and IL-18) by activating caspase-1. In this review, we comprehensively describe the structure and functions of the NLRP3 inflammasome. We also explore the intrinsic relationship between the NLRP3 inflammasome and cognitive impairment, which involves immune cell activation, cell apoptosis, oxidative stress, mitochondrial autophagy, and neuroinflammation. Finally, we describe NLRP3 inflammasome antagonists as targeted therapies to improve cognitive impairment.

Immunomodulation by cannabidiol in bovine primary ruminal epithelial cells

BACKGROUND

Ruminant livestock experience a number of challenges, including high concentrate diets, weaning and transport, which can increase their risk of disorders such as ruminal acidosis, and the associated inflammation of the ruminal epithelium. Cannabidiol (CBD), a phytochemical from hemp (Cannabis sativa), is a promising target as a therapy for gastrointestinal inflammation, and may be extremely valuable as either a treatment or prophylactic. However, the effects of CBD in the the ruminant gastrointestinal tract have not been explored, in part due to the restrictions on feeding hemp to livestock. Therefore, the objective of this study was to investigate the immunomodulatory properties of CBD using a model of inflammation in primary ruminal epithelial cells (REC). In addition, CBD dose was evaluated for possible cytotoxic effects.

RESULTS

Negative effects on cell viability were not observed when REC were exposed to 10 μM CBD. However, when the dose was increased to 50 μM for 24 h, there was a significant cytotoxic effect. When 10 μM CBD was added to culture media as treatment for inflammation induced with lipopolysaccharide (LPS), expression of genes encoding for pro-inflammatory cytokine IL1B was less compared to LPS exposure alone, and CBD resulted in a down-regulation of IL6. As a pre-treatment, prior to LPS exposure, REC had decreased expression of IL6 and CXCL10 while CBD was present in the media, but not when it was removed prior to addition of LPS.

CONCLUSIONS

Results suggest that CBD may reduce cytokine transcription both during LPS-induced inflammation and when used preventatively, although these effects were dependent on its continued presence in the culture media. Overall, these experiments provide evidence of an immunomodulatory effect by CBD during a pro-inflammatory response in primary REC in culture.

Aluminum exposure induces central nervous system impairment via activating NLRP3-medicated pyroptosis pathway

PURPOSE

Aluminum is an environmental toxicant whose long-term exposure is closely associated with nervous system impairment. This study mainly investigated neurological impairment induced by subchronic aluminum exposure via activating NLRP3-medicated pyroptosis pathway.

METHODS

In vivo, Kunming mice were exposed to AlCl3 (30.3 mg/kg, 101 mg/kg and 303 mg/kg) via drinking water for 3 months, and administered with Rsv (100 mg/kg) by gavage for 1 month. Cognitive impairment was assessed by Morris water maze test, and pathological injury was detected via H&E staining. BBB integrity, pyroptosis and neuroinflammation were evaluated through western blotting and immunofluorescence methods. In vitro, BV2 microglia was treated with AlCl3 (0.5 mM, 1 mM and 2 mM) to sensitize pyroptosis pathway. The protein interaction was verified by co-immunoprecipitation, and neuronal damage was estimated via a conditioned medium co-culture system with BV2 and TH22 cells.

RESULTS

Our results showed that AlCl3 induced mice memory disorder, BBB destruction, and pathological injury. Besides, aluminum caused glial activation, sensitized DDX3X-NLRP3 pyroptosis pathway, released cytokines IL-1β and IL-18, initiating neuroinflammation. BV2 microglia treated with AlCl3 emerged hyperactivation and pyroptotic death, and Ddx3x knockdown inhibited pyroptosis signaling pathway. DDX3X acted as a live-or-die checkpoint in stressed cells by regulating NLRP3 inflammasome and G3BP1 stress granules. Furthermore, aluminum-activated microglia had an adverse effect on co-cultured neurons and destroyed nervous system homeostasis.

CONCLUSION

Aluminum exposure could induce pyroptosis and neurotoxicity. DDX3X determined live or die via selectively regulating pro-survival stress granules or pro-death NLRP3 inflammasome. Excessive activation of microglia might damage neurons and aggravate nerve injury.

Beneficial effects of flavonoids on cardiovascular diseases by influencing NLRP3 inflammasome

Cardiovascular diseases (CVDs) are a leading cause of global mortality and have a high incidence rate worldwide. The function of inflammasomes in CVDs has received a lot of attention recently, and the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome may be a new target for the prevention and treatment of CVDs. Flavonoids, which are found in food and plant extracts, inhibited inflammation in CVDs by regulating the NLRP3 inflammasome. CB-Dock was used to investigate whether 34 flavonoids from natural products acted on NLRP3 inflammasome. In brief, the PDB format of NLRP3 was selected as a protein file, and 34 flavonoids in SDF format were selected as the ligand file, and then input to CB-Dock for molecular docking. The docking results showed that epigallocatechin-3-gallate (EGCG), amentoflavone, baicalin, scutellarin, vitexin, silibinin, and puerarin had good binding affinities to NLRP3, which could be used as NLRP3 inhibitors, and aid in the discovery of lead compounds for the design and development of CVDs.

The beneficial effects of astragaloside IV on ameliorating diabetic kidney disease

Diabetic kidney disease (DKD) has become the major cause of chronic kidney disease or end-stage renal disease. There is still a need for innovative treatment strategies for preventing, arresting, treating, and reversing DKD, and a plethora of scientific evidence has revealed that Chinese herbal monomers can attenuate DKD in multiple ways. Astragaloside IV (AS-IV) is one of the active ingredients of Astragalus membranaceus and was selected as a chemical marker in the Chinese Pharmacopeia for quality control purposes. An increasing amount of studies indicate that AS-IV is a promising novel drug for the treatment of DKD. AS-IV has been shown to improve DKD by combating oxidative stress, attenuating endoplasmic reticulum stress, regulating calcium homeostasis, alleviating inflammation, improving vascular function, improving epithelial to mesenchymal transition and so on. This review briefly summarizes the pathogenesis of DKD, systematically reviews the mechanisms by which AS-IV improves DKD, and aims to facilitate related pharmacological research and development to promote the utilization of Chinese herbal monomers in DKD.

Lycopene ameliorates DEHP exposure-induced renal pyroptosis through the Nrf2/Keap-1/NLRP3/Caspase-1 axis

Di (2-ethylhexyl) phthalate (DEHP) is commonly used as a plasticizer in plastic products, and due to its unique chemical composition, it frequently dissolves and enters the environment. Lycopene as a natural carotenoid has been shown to have powerful antioxidant capacity and strong kidney protection. This study aimed to investigate the role of the interplay between oxidative stress and the classical pyroptosis pathway in LYC alleviating DEHP-induced renal injury. ICR mice were given DEHP (500 mg/kg/d or 1000 mg/kg/d) and/or LYC (5 mg/kg/d) for 28 days to explore the underlying mechanisms of this hypothesis. Our results indicated that DEHP caused the shedding of renal tubular epithelial cells, increased the content of kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL) in the tissue, the decrease of antioxidant activity markers and the increase of oxidative stress indexes. It is gratifying that LYC alleviates DEHP-induced renal injury. The expression of nuclear factor erythrocyte 2-related factor 2 (Nrf2) and its downstream target genes is improved in DEHP induced renal injury through LYC mediated protection. Meanwhile, LYC supplementation can inhibit DEHP-induced Caspase-1/NLRP3-dependent pyroptosis and inflammatory responses. Taken together, DEHP administration resulted in nephrotoxicity, but these changes ameliorated by LYC may through crosstalk between the Nrf2/Keap-1/NLRP3/Caspase-1 pathway. Our study provides new evidence that LYC protects against kidney injury caused by DEHP.

Aldehyde dehydrogenase 2 and NOD-like receptor thermal protein domain associated protein 3 inflammasome in atherosclerotic cardiovascular diseases: A systematic review of the current evidence

Inflammation and dyslipidemia underlie the pathological basis of atherosclerosis (AS). Clinical studies have confirmed that there is still residual risk of atherosclerotic cardiovascular diseases (ASCVD) even after intense reduction of LDL. Some of this residual risk can be explained by inflammation as anti-inflammatory therapy is effective in improving outcomes in subjects treated with LDL-lowering agents. NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation is closely related to early-stage inflammation in AS. Aldehyde dehydrogenase 2 (ALDH2) is an important enzyme of toxic aldehyde metabolism located in mitochondria and works in the metabolism of toxic aldehydes such as 4-HNE and MDA. Despite studies confirming that ALDH2 can negatively regulate NLRP3 inflammasome and delay the development of atherosclerosis, the mechanisms involved are still poorly understood. Reactive Oxygen Species (ROS) is a common downstream pathway activated for NLRP3 inflammasome. ALDH2 can reduce the multiple sources of ROS, such as oxidative stress, inflammation, and mitochondrial damage, thereby reducing the activation of NLRP3 inflammasome. Further, according to the downstream of ALDH2 and the upstream of NLRP3, the molecules and related mechanisms of ALDH2 on NLRP3 inflammasome are comprehensively expounded as possible. The potential mechanism may provide potential inroads for treating ASCVD.

Recent Update on the Development of PCSK9 Inhibitors for Hypercholesterolemia Treatment

The proprotein convertase subtilisin/kexin-type 9 (PCSK9) binds to low-density lipoprotein receptors (LDLR), thereby trafficking them to lysosomes upon endocytosis and enhancing intracellular degradation to prevent their recycling. As a result, the levels of circulating LDL cholesterol (LDL-C) increase, which is a prominent risk factor for developing atherosclerotic cardiovascular diseases (ASCVD). Thus, PCSK9 has become a promising therapeutic target that offers a fertile testing ground for new drug modalities to regulate plasma LDL-C levels to prevent ASCVD. In this review, we have discussed the role of PCSK9 in lipid metabolism and briefly summarized the current clinical status of modalities targeting PCSK9. In particular, a detailed overview of peptide-based PCSK9 inhibitors is presented, which emphasizes their structural features and design, therapeutic effects on patients, and preclinical cardiovascular disease (CVD) models, along with PCSK9 modulation mechanisms. As a promising alternative to monoclonal antibodies (mAbs) for managing LDL-C, anti-PCSK9 peptides are emerging as a prospective next generation therapy.

Сyclooxygenase-2 Inhibitor Parecoxib Reduces LPS-Induced Activation of BV2 Microglia Cells

We studied the inhibitory effect of cyclooxygenase-2 inhibitor parecoxib on LPS-induced activation of BV2 microglia cells. The optimal dose of parecoxib (80 μmol/liter) was evaluated by the Cell Counting Kit-8. The cells were divided into the following groups: control (intact cells without treatment); LPS (treatment with 1 μg/ml LPS for 6 h), and experimental (pretreatment with 80 μmol/liter parecoxib for 24 h followed by incubation with 1 μg/ml LPS for 6 h). Cell morphology and proliferation and the expression of NLRP3, caspase-1, pro-caspase-1, and IL-1β were assessed. LPS induced significant morphological changes and decreased proliferation of primary BV2 cells in comparison with the control. These changes were prevented by parecoxib pretreatment. LPS significantly increased NLRP3 inflammatory vesicle activation and expression of NLRP3, caspase-1, pro-caspase-1, and IL-1β in comparison with the control group; pretreatment with parecoxib prevented all these changes. Our results suggest that pretreatment with parecoxib inhibited LPS-induced activation of BV2 microglial cells and probably inhibited NLRP3 inflammasome activation.

Hunting down NLRP3 inflammasome: An executioner of radiation-induced injury

Radiotherapy is one of the mainstream treatment modalities for several malignancies. However, radiation-induced injury to surrounding normal tissues limits its efficacy. The NLRP3 inflammasome is an essential mechanism of innate immunity that reacts to challenges from endogenous danger signals and pathological microbes. A growing body of evidence has demonstrated a key role of NLRP3 inflammasome in the pathogenesis of radiation-induced tissue injury. Despite accumulating evidence, the potential value of the NLRP3 inflammasome in the management of radiation-induced tissue injury is not adequately recognized. We conducted a literature review to characterize the relationship between NLRP3 inflammasome and radiation injury. By analyzing recent evidence, we identify NLRP3 inflammasome as one of the executioners of radiation-induced injury, since it responds to the challenges of radiation, induces cell pyroptosis and tissue dysfunction, and initiates non-resolving inflammation and fibrosis. Based on these concepts, we propose early intervention/prevention strategies targeting NLRP3 inflammasome in a radiation context, which may help resolve imperative clinical problems.

Pivotal regulatory roles of traditional Chinese medicine in ischemic stroke via inhibition of NLRP3 inflammasome

ETHNOPHARMACOLOGICAL RELEVANCE

Many studies have demonstrated the powerful neuroprotection abilities of multiple traditional Chinese medicines (TCMs) against NLRP3 inflammasome-mediated ischemic cerebral injury. These TCMs may be in the form of TCM prescriptions, Chinese herbal medicines and their extracts, and TCM monomers.

AIM OF THE STUDY

This review aimed to analyze and summarize the existing knowledge on the assembly and activation of the NLRP3 inflammasome and its role in the pathogenesis of ischemic stroke (IS). We also summarized the mechanism of action of the various TCMs on the NLRP3 inflammasome, which may provide new insights for the management of IS.

MATERIALS AND METHODS

We reviewed recently published articles by setting the keywords "NLRP3 inflammasome" and "traditional Chinese medicines" along with "ischemic stroke"; "NLRP3 inflammasome" and "ischemic stroke" along with "natural products" and so on in Pubmed and GeenMedical.

RESULTS

According to recent studies, 16 TCM prescriptions (officially authorized products and clinically effective TCM prescriptions), 7 Chinese herbal extracts, and 29 TCM monomers show protective effects against IS through anti-inflammatory, anti-oxidative stress, anti-apoptotic, and anti-mitochondrial autophagy effects.

CONCLUSIONS

In this review, we analyzed studies on the involvement of NLRP3 in IS therapy. Further, we comprehensively and systematically summarized the current knowledge to provide a reference for the further application of TCMs in the treatment of IS.

Alterations of the gut microbiota and metabolomics in children with e-waste lead exposure

BACKGROUND

A lead (Pb) exposure can alter the composition and metabolites of gut microbiota. However, few studies investigated this association in the children.

METHODS

A total of 551 children aged 3-7 years were recruited from Guiyu (the e-waste dismantling area) and Haojiang (the reference area). There were finally 70 subjects met the inclusive criteria. Blood and urinary Pb concentrations were detected by GFAAS and ICP-MS techniques. The microbiota and metabolites were measured in stool samples using 16 S rRNA MiSeq sequencing technology and gas chromatography-mass spectrometry (GC-MS), respectively.

RESULTS

Average Pb concentrations in the blood and urine of children were higher in Guiyu than in Haojiang. There were 58 kinds of differential genera and 19 types of discrepant metabolites between the two groups, and wide and significant correlations were found between them. Exposure to Pb caused the most significant differences in microbiota, metabolites, and physical development parameters between the two groups in terms of microbiota, metabolites, and physical development indicators. Sphingolipid metabolism and ion transport may also be altered by Pb exposure.

CONCLUSIONS

Exposure to Pb is associated with significant alterations in the gut microbiota and metabolome in children. More research is needed to confirm the findings of this study.

Expression and Mechanism of TXNIP/NLRP3 Inflammasome in Sciatic Nerve of Type 2 Diabetic Rats

Objective

To determine the expression profiling and mechanism of thioredoxin-interacting protein (TXNIP)/nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome pathway in sciatic nerve (SN) of type 2 diabetes mellitus (T2DM) rats.

Methods

Ten out of the 35 healthy SD rats (specific pathogen free) purchased were randomized into the control group, while the others were established a T2DM model by feeding a high-fat and high-sugar diet plus laparoscopic injection of 1% streptozotocin (STZ). The successfully modeled rats were subgrouped into two arms: a DM group with 10 rats and a resveratrol- (RES-) treated DM intervention group with 11 rats. Normal saline to control and DM groups. Alterations in fasting blood glucose (FBG) and body weight (BW) at different time points after administration were observed. Sciatic nerve conduction velocity (SNCV) and mechanical pain threshold (MPT) were measured. TXNIP, NLRP3, caspase-1, and interleukin- (IL-) 1β levels in rat SN tissue were determined.

Results

DM group rats showed higher FBG and lower BW than control rats at different time points (P < 0.05). The FBG of DM intervention group at 2, 4, and 6 weeks after administration was lower, and the BW at 4 and 6 weeks after dosing was higher than DM group. Higher MPT and SNCV were determined in DM intervention group versus DM group (P < 0.05). DM group rats had disordered, swollen, and dissolved SN myelin sheath structure; TXNIP inhibition led to a small amount of nerve myelin fragments and mild pathological changes. Lower TXNIP, NLRP3, caspase-1, and IL-1β protein levels were found in DM intervention group versus DM group (P < 0.05).

Conclusion

The pathogenesis of peripheral neuropathy in T2DM rats may be linked to TXNIP/NLRP3 inflammasome pathway activation, indicating the potential of this pathway as a therapeutic target for diabetic peripheral neuropathy (DPN).

Hematopoietic stem cell mobilization

Hematopoietic stem cell (HSC) transplantation has been used to treat hematopoietic diseases for over 50 years. HSCs can be isolated from bone marrow (BM), umbilical cord blood, or peripheral blood. Because of lower costs, shorter hospitalization, and faster engraftment, peripheral blood has become the predominant source of HSCs for transplantation. The major factors determining the rate of successful HSC transplantation include the degree of human leukocyte antigen matching between the donor and recipient and the number of HSCs for transplantation. Administration of granulocyte colony-stimulating factor (G-CSF) alone or combined with plerixafor (AMD3100) are clinical used methods to promote HSC mobilization from BM to the peripheral blood for HSC transplantations. However, a significant portion of healthy donors or patients may be poor mobilizers of G-CSF, resulting in an insufficient number of HSCs for the transplantation and necessitating alternative strategies to increase the apheresis yield. The detailed mechanisms underlying G-CSF-mediated HSC mobilization remain to be elucidated. This review summarizes the current research on deciphering the mechanism of HSC mobilization.

The Role of the NLRP3 Inflammasome in Mediating Glomerular and Tubular Injury in Diabetic Nephropathy

The NOD-like receptor protein 3 (NLRP3) inflammasome is a multi-protein signalling complex integral to the chronic inflammatory response, activated in response to sterile and non-sterile cellular damage. The assembly and activation of the NLRP3 inflammasome comprise a two-step process involving nuclear factor kappa B (NFkB)-mediated priming, followed by canonical, non-canonical or alternative signalling pathways. These result in the maturation and release of inflammatory cytokines interleukin 1 beta (IL1ß) and interleukin-18 (IL18), which are associated with chronic inflammatory conditions including diabetic kidney disease. Diabetic nephropathy is a condition affecting ∼40% of people with diabetes, the key underlying pathology of which is tubulointerstitial inflammation and fibrosis. There is growing evidence to suggest the involvement of the NLRP3 inflammasome in this chronic inflammation. Early deterioration of kidney function begins in the glomerulus, with tubular inflammation dictating the progression of late-stage disease. Priming and activation of the NLRP3 inflammasome have been linked to several clinical markers of nephropathy including proteinuria and albuminuria, in addition to morphological changes including mesangial expansion. Treatment options for diabetic nephropathy are limited, and research that examines the impact of directly targeting the NLRP3 inflammasome, or associated downstream components are beginning to gain favour, with several agents currently in clinical trials. This review will explore a role for NLRP3 inflammasome activation and signalling in mediating inflammation in diabetic nephropathy, specifically in the glomerulus and proximal tubule, before briefly describing the current position of therapeutic research in this field.

Role of NLRP3 Inflammasome in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by multi-articular, symmetrical and invasive arthritis resulting from immune system abnormalities involving T and B lymphocytes. Although significant progress has been made in the understanding of RA pathogenesis, the underlying mechanisms are not fully understood. Recent studies suggest that NLRP3 inflammasome, a regulator of inflammation, might play an important role in the development of RA. There have been increasing clinical and pre-clinical evidence showing the treatment of NLRP3/IL-1β in inflammatory diseases. To provide a foundation for the development of therapeutic strategies, we will briefly summarize the roles of NLRP3 inflammasome in RA and explore its potential clinical treatment.

Cochlear Marginal Cell Pyroptosis Is Induced by Cisplatin via NLRP3 Inflammasome Activation

Better understanding the mechanism of cisplatin-induced ototoxicity is of great significance for clinical prevention and treatment of cisplatin-related hearing loss. However, the mechanism of cisplatin-induced inflammatory response in cochlear stria vascularis and the mechanism of marginal cell (MC) damage have not been fully clarified. In this study, a stable model of cisplatin-induced MC damage was established in vitro, and the results of PCR and Western blotting showed increased expressions of NLRP3, Caspase-1, IL-1β, and GSDMD in MCs. Incomplete cell membranes including many small pores appearing on the membrane were also observed under transmission electron microscopy and scanning electron microscopy. In addition, downregulation of NLRP3 by small interfering RNA can alleviate cisplatin-induced MC pyroptosis, and reducing the expression level of TXNIP possesses the inhibition effect on NLRP3 inflammasome activation and its mediated pyroptosis. Taken together, our results suggest that NLRP3 inflammasome activation may mediate cisplatin-induced MC pyroptosis in cochlear stria vascularis, and TXNIP is a possible upstream regulator, which may be a promising therapeutic target for alleviating cisplatin-induced hearing loss.

NLRP3-Mediated Inflammation in Atherosclerosis and Associated Therapeutics

The NLRP3 inflammasome is a crucial constituent of the body’s innate immune system, and a multiprotein platform which is initiated by pattern recognition receptors (PRRs). Its activation leads to caspase-1 maturation and release of inflammatory cytokines, interleukin-1β (IL-1β) and IL-18, and subsequently causes pyroptosis. Recently, the excess activation of NLRP3 inflammasome has been confirmed to mediate inflammatory responses and to participate in genesis and development of atherosclerosis. Therefore, the progress on the discovery of specific inhibitors against the NLRP3 inflammasome and the upstream and downstream inflammatory factors has become potential targets for clinical treatment. Here we review the recently described mechanisms about the NLRP3 inflammasome activation, and discuss emphatically the pharmacological interventions using statins and natural medication for atherosclerosis associated with NLRP3 inflammasome.

Construction of a ceRNA Network Related to Rheumatoid Arthritis

(1) Background: Rheumatoid arthritis (RA) is a common systemic autoimmune disease affecting many people and has an unclear and complicated physiological mechanism. The competing endogenous RNA (ceRNA) network plays an essential role in the development and occurrence of various human physiological processes. This study aimed to construct a ceRNA network related to RA. (2) Methods: We explored the GEO database for peripheral blood mononuclear cell (PBMC) samples and then analyzed the RNA of 52 samples (without treatment) to obtain lncRNAs (DELs), miRNAs (DEMs), and mRNAs (DEGs), which can be differentially expressed with statistical significance in the progression of RA. Next, a ceRNA network was constructed, based on the DELs, DEMs, and DEGs. At the same time, the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis were used to validate the possible function of the ceRNA network. (3) Results: Through our analysis, 389 DELs, 247 DEMs, and 1081 DEGs were screened. After this, a ceRNA network was constructed for further statistical comparisons, including 16 lncRNAs, 1 miRNA, and 15 mRNAs. According to the GO and KEGG analysis, the ceRNA network was mainly enriched in the mTOR pathway, the dopaminergic system, and the Wnt signaling pathway. (4) Conclusions: The novel ceRNA network related to RA that we constructed offers novel insights into and targets for the underlying molecular mechanisms of the mTOR pathway, the dopaminergic system, and the Wnt signaling pathway (both classic and nonclassic pathways) that affect the level of the genetic regulator, which might offer novel ways to treat RA.

P2X7 Receptor and Heart Function in a Mouse Model of Systemic Inflammation Due to High Fat Diet

Purpose

Low-grade inflammation contributes to heart failure in obesity or type 2 diabetes mellitus. The P2X7 receptor (P2X7R) is a key regulator of several pro-inflammatory responses in multiple tissues and organs; however, its involvement in the onset of heart dysfunction remains unclear. The study evaluated the role of P2X7R as a cardiac function regulator in C57BL/6J wild-type (WT) and P2X7R knockout (KO) mice by inducing systemic inflammation with high fat diet (HFD).

Methods

Specific parameters of systolic and diastolic function and heart morphology were measured in vivo before animal sacrifice by high-frequency ultrasonographic analysis. Gene and protein expression of cardiac biomarkers associated with inflammatory-oxidative pathways were evaluated by real-time PCR and Western Blotting.

Results

P2X7R-mediated up-regulation of the NLRP3-caspase-1 complex, increased expression of key oxidative stress (NOS-2, TNFα), and chemotactic (MCP-1) mediators were revealed in WT-HFD animals. In KO-HFD mice, such inflammatory-oxidative pathway was silent. Nevertheless, HFD induced in vivo a clear alteration of diastolic pattern (E/A: p < 0.03 vs WT-HFD) and a cardiac morphologic remodelling (left ventricular mass: p < 0.05 vs WT-HFD) only in P2X7R KO animals. Surprisingly, the transcriptional and protein expression of IL-1β and IL-6, usually regulated through P2X7R activation, were significantly higher in KO-HFD than in WT-HFD mice (both p < 0.05). Furthermore, an up-regulation of miR-214 and a down-regulation of miR-126 in heart of HFD-KO mice were observed, suggesting a link between such epigenetic dysregulation and cytokine overexpression as a potential pathophysiologic mechanism concurring to the progressive cardiac dysfunction.

Conclusion

These findings seem to suggest a cardioprotective role of P2X7R toward this tissue-specific inflammatory damage, likely through tissue homeostasis and organ functionality preservation.

PM2.5 exposure inducing ATP alteration links with NLRP3 inflammasome activation

Fine particulate matter (PM_2.5) has been the primary air pollutant and the fourth leading risk factor for disease and death in the world. Exposure to PM_2.5 is related to activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, but the mechanism of PM_2.5 affecting the NLRP3 inflammasome is still unclear. Previous studies have shown that PM_2.5 can cause alterations in adenosine triphosphate (ATP), and an increase in extracellular ATP and a decrease in intracellular ATP can trigger the activation process of the NLRP3 inflammasome. Therefore, we emphasize that ATP changes may be the central link and key mechanism of PM_2.5 exposure that activates the NLRP3 inflammasome. This review briefly elucidates and summarizes how PM_2.5 acts on ATP and subsequently further impacts the NLRP3 inflammasome. Investigation of ATP changes due to exposure to PM_2.5 may be essential to regulate NLRP3 inflammasome activation and treat inflammation-related diseases such as coronavirus disease 2019 (COVID-19).

Therapeutic potential of carbon monoxide in hypertension-induced vascular smooth muscle cell damage revisited: from physiology and pharmacology

As a chronic and progressive disorder, hypertension remains to be a serious public health problem around the world. Among the different types of hypertension, pulmonary arterial hypertension (PAH) is a devastating disease associated with pulmonary arteriole remodeling, right ventricular failure and death. The contemporary management of systemic hypertension and PAH has substantially grown since more therapeutic targets and/or agents have been developed. Evolving treatment strategies targeting the vascular remodeling lead to improving outcomes in patients with hypertension, nevertheless, significant advancement opportunities for developing better antihypertensive drugs remain. Carbon monoxide (CO), an active endogenous gasotransmitter along with hydrogen sulfide (H₂S) and nitric oxide (NO), is primarily generated by heme oxygenase (HO). Cumulative evidence suggests that CO is considered as an important signaling molecule under both physiological and pathological conditions. Studies have shown that CO confers a number of biological and pharmacological properties, especially its involvement in the pathological process and treatment of hypertension-related vascular remodeling. This review will critically outline the roles of CO in hypertension-associated vascular remodeling and discuss the underlying mechanisms for the protective effects of CO against hypertension and vascular remodeling. In addition, we will propose the challenges and perspectives of CO in hypertensive vascular remodeling. It is expected that a comprehensive understanding of CO in the vasculature might be essential to translate CO to be a novel pharmacological agent for hypertension-induced vascular remodeling.

miR-155-5p in Extracellular Vesicles Derived from Choroid Plexus Epithelial Cells Promotes Autophagy and Inflammation to Aggravate Ischemic Brain Injury in Mice

Ischemic stroke is a common disease of the central nervous system, and ischemic brain injury (IBI) is its main manifestation. Recently, extracellular vesicles (EVs) have been strongly related to the diagnosis and treatment of IBI. However, the underlying mechanism of their effects remains enigmatic. In the present study, we aimed to study how miR-155-5p plays a role in choroid plexus epithelial (CPE) cell-derived EVs in IBI pathology. We found that miR-155-5p expression was enriched in CPE cell-derived EVs, which were subsequently internalized by neurons, enabling the delivery of miR-155-5p into neurons. An inducible oxygen and glucose deprivation and reoxygenation (OGD/R) cell model was developed to mimic ischemic neuronal injury in vitro. miR-155-5p overexpression led to reduced neuron viability, promoted apoptosis, elevated autophagic proteins' expression, and activated NLR family pyrin domain-containing 3- (NLRP3-) related inflammasomes, thereby aggravating OGD-induced neuronal injury. A dual-luciferase reporter assay exhibited that miR-155-5p could inhibit the Ras homolog enriched in brain (Rheb) expression, a mechanism critical for miR-155-5p-mediated neuronal injury. Furthermore, a mouse IBI model was developed using the transient middle cerebral artery occlusion (tMCAO) method. Animal experiments verified that miR-155p delivery via CPE cell-derived EVs aggravated IBI by suppressing Rheb expression. In conclusion, miR-155-5p in CPE-derived EVs can aggravate IBI pathology by suppressing Rheb expression and promoting NLRP3-mediated inflammasomes, suggesting its role as a potential therapeutic target in IBI.

Leptin Aggravates Periodontitis by Promoting M1 Polarization via NLRP3

Periodontitis is characterized by periodontal pocket formation, loss of attachment, and alveolar bone resorption. Both innate and adaptive immunity are involved in the pathogenesis of this oral chronic inflammatory disease. Accumulating evidence indicates a critical role of leptin in periodontal diseases. However, the mechanism by which leptin promotes periodontitis pathogenesis remains unclear. In the present study, we observed an elevated expression of leptin in the serum of periodontitis mice compared to that in healthy controls. There was a higher extent of M1 phenotype macrophage infiltration in mice periodontitis samples than in healthy controls. A positive correlation was observed between the serum leptin levels and M1 macrophages. Treatment with leptin increased M1 macrophage polarization and decreased M2 macrophage polarization in RAW 264.7 cells. Moreover, leptin facilitated lipopolysaccharide (LPS)-induced M1 phenotype macrophage polarization in RAW 264.7 cells. In bone marrow-derived macrophages (BMDMs) generated from leptin-deficient obese (ob/ob) mice, M1 macrophage polarization was significantly attenuated after LPS stimulation compared to the healthy controls. With regards to the molecular mechanism, we found that leptin activated the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and promoted M1 polarization via the NLRP3 inflammasome in vitro. In BMDMs generated from Nlrp3^-/- mice, M1 macrophage polarization was significantly attenuated after synchronous stimulation with leptin and LPS compared with BMDMs produced by healthy controls. The NLRP3 inhibitor MCC950 also prevented leptin-mediated M1 macrophage polarization in RAW 264.7 cells. Nlrp3^-/- periodontitis models indicated that leptin aggravates the periodontal response to the ligature by promoting M1 macrophage polarization via the NLRP3 inflammasome. Taken together, we show that leptin promotes the progression of periodontitis via proinflammatory M1 macrophage skewing, and targeting leptin/NLRP3 signaling may be a feasible approach for treating periodontitis.

Nrf2 in the Field of Dentistry with Special Attention to NLRP3

The aim of this review article was to summarize the functional implications of the nuclear factor E2-related factor or nuclear factor (erythroid-derived 2)-like 2 (Nrf2), with special attention to the NACHT (nucleotide-binding oligomerization), LRR (leucine-rich repeat), and PYD (pyrin domain) domains-containing protein 3 (NLRP3) inflammasome in the field of dentistry. NLRP3 plays a crucial role in the progression of inflammatory and adaptive immune responses throughout the body. It is already known that this inflammasome is a key regulator of several systemic diseases. The initiation and activation of NLRP3 starts with the oral microbiome and its association with the pathogenesis and progression of several oral diseases, including periodontitis, periapical periodontitis, and oral squamous cell carcinoma (OSCC). The possible role of the inflammasome in oral disease conditions may involve the aberrant regulation of various response mechanisms, not only in the mouth but in the whole body. Understanding the cellular and molecular biology of the NLRP3 inflammasome and its relationship to Nrf2 is necessary for the rationale when suggesting it as a potential therapeutic target for treatment and prevention of oral inflammatory and immunological disorders. In this review, we highlighted the current knowledge about NLRP3, its likely role in the pathogenesis of various inflammatory oral processes, and its crosstalk with Nrf2, which might offer future possibilities for disease prevention and targeted therapy in the field of dentistry and oral health.

Spotlight on NLRP3 Inflammasome: Role in Pathogenesis and Therapies of Atherosclerosis

Inflammation is an intricate biological response of body tissues to detrimental stimuli. Cardiovascular disease (CVD) is the leading cause of death worldwide, and inflammation is well documented to play a role in the development of CVD, especially atherosclerosis (AS). Emerging evidence suggests that activation of the NOD-like receptor (NLR) family and the pyridine-containing domain 3 (NLRP3) inflammasome is instrumental in inflammation and may result in AS. The NLRP3 inflammasome acts as a molecular platform that triggers the activation of caspase-1 and the cleavage of pro-interleukin (IL)-1β, pro-IL-18, and gasdermin D (GSDMD). The cleaved GSDMD forms pores in the cell membrane and initiates pyroptosis, inducing cell death and the discharge of intracellular pro-inflammatory factors. Hence, the NLRP3 inflammasome is a promising target for anti-inflammatory therapy against AS. In this review, we systematically summarized the current understanding of the activation mechanism of NLRP3 inflammasome, and the pathological changes in AS involving NLRP3. We also discussed potential therapeutic strategies targeting NLRP3 inflammasome to combat AS.

NLRP3 Inflammasome Pharmacological Inhibitors in Glycyrrhiza for NLRP3-Driven Diseases Treatment: Extinguishing the Fire of Inflammation

Inflammation is the tissues’ defense response after the body is stimulated by microbial infection or damage signals, and it is initiated when pattern recognition receptors recognize pathogen-related molecular patterns and danger-related molecular patterns. The hyperactivation of NLRP3 inflammasome, the main driving force of immune outbreaks, is involved in a wide range of inflammatory diseases. Meanwhile, growing evidence has indicated that the development of NLRP3-targeted therapies offers great potential and promise for the treatment of related diseases. The search for and development of efficacious anti-inflammatory prodrugs from natural sources of plants and traditional Chinese medicines (TCMs) have received extensive attention. Glycyrrhiza, an important minister in the kingdom of TCMs, has high activity and a wide range of therapeutic effects. Studies have shown that a variety of active components found in Glycyrrhiza, such as licochalcone A, echinatin, isoliquiritigenin, and glycyrrhizin, produce a wide range of anti-inflammatory effects by discouraging NLRP3 inflammasome activation. Here, we summarize the role and mechanism of the active ingredients in Glycyrrhiza that target the NLRP3 inflammasome and treat related inflammatory diseases. We describe a favorable approach for the development of natural, safe, and efficient drugs that exploit these naturally occurring active ingredients to treat NLRP3-driven diseases.

DExD/H-box helicases: multifunctional regulators in antiviral innate immunity

DExD/H-box helicases play critical roles in multiple cellular processes, including transcription, cellular RNA metabolism, translation, and infections. Several seminal studies over the past decades have delineated the distinct functions of DExD/H-box helicases in regulating antiviral innate immune signaling pathways, including Toll-like receptors, retinoic acid-inducible gene I-like receptors, cyclic GMP-AMP synthase-the stimulator of interferon gene, and NOD-like receptors signaling pathways. Besides the prominent regulatory roles, there is increasing attention on their functions as nucleic acid sensors involved in antiviral innate immunity. Here we summarize the complex regulatory roles of DExD/H-box helicases in antiviral innate immunity. A better understanding of the underlying molecular mechanisms of DExD/H-box helicases' regulatory roles is vital for developing new therapeutics targeting DExD/H-box helicases and their mediated signaling transduction in viral infectious diseases.

Memantine Alleviates Acute Lung Injury Via Inhibiting Macrophage Pyroptosis

ABSTRACT

Acute lung injury (ALI) is caused by direct pulmonary insults and indirect systemic inflammatory responses that result from conditions such as sepsis and trauma. Alveolar macrophages are the main and critical leukocytes in the airspace, and through the synthesis and release of various inflammatory mediators critically influence the development of ALI following infection and non-infectious stimuli. There is increasing recognition that inflammation and cell death reciprocally affect each other, which forms an auto-amplification loop of these two factors, and in turn, exaggerates inflammation. Therefore, pharmacological manipulation of alveolar macrophage death signals may serve as a logical therapeutic strategy for ALI. In this study, we demonstrate that memantine, a N-methyl-D-aspartic acid receptor (NMDAR) antagonist, through suppressing Ca2+ influx and subsequent ASC oligomerization inhibits macrophage Nlrp3 inflammasome activation and pyroptosis, therefore, alleviates ALI in septic mice. This finding explores a novel application of memantine, an FDA already approved medication, in the treatment of ALI, which is currently lacking effective therapy.

Novel insights into antidepressant mechanism of Kai Xin San formula: Inhibiting NLRP3 inflammasome activation by promoting autophagy

BACKGROUND

Kai Xin San (KXS) was widely applied for the treatment of depression for thousands of years. However, the underlying antidepressant mechanism of KXS remains not clear.

PURPOSE

This study aimed to investigate whether NLRP3 inflammasome and autophagy are involved in inflammation-induced depression and antidepressant mechanism of KXS.

METHODS

Wistar rats were exposed to chronic unpredictable mild stress (CUMS) for 6 weeks, and KXS (3, 5, and 10 g/kg/d) was administrated during the last 2 weeks of CUMS procedure. The effects of KXS on depressive-like behaviors, neuroinflammation, NLRP3 inflammasome activation, and autophagy were investigated in CUMS rats. Rat astrocytes were employed to further explore the potential mechanism of KXS in regulating NLRP3 inflammasome and autophagy. Autophagy inhibitor 3-methyladenine (3-MA, 5 mM) was used in vitro to elucidate the role of autophagy in the antidepressant mechanism of KXS.

RESULTS

In vivo, KXS improved depressive-like behaviors of CUMS rats in sucrose preference test, open field test and forced swimming test. Moreover, KXS inhibited the neuroinflammation induced by CUMS and promoted autophagy in prefrontal cortex of rats. The results in vitro further validated the anti-inflammatory and proautohapgic effects of KXS. More importantly, autophagy inhibitor 3-MA diminished the inhibitory effect of KXS on NLRP3 inflammasome activation in rat astrocytes.

CONCLUSION

KXS ameliorated CUMS-induced depressive behaviors in rats and inhibited the NLRP3 inflammasome-mediated inflammation in vivo and in vitro. These effects might be regulated by KXS-induced autophagy.

The role of NLRP3 inflammasome in the pathogenesis of rheumatic disease

Inflammasome is a molecular platform that is formed in the cytosolic compartment to mediate host immune responses to infection and cellular damage. Inflammasome can activate caspase-1, leading to the maturation of two inflammatory cytokines interleukin 1β (IL-1β) and IL-18 and initiation of a proinflammatory form of cell death called pyroptosis. Among various inflammasome complexes, the NLRP3 inflammasome is by far the most studied inflammasome. NLRP3 inflammasome is a key factor in regulating host immune defense against infectious microbes and cellular damage. However, the dysregulated NLRP3 inflammasome activation also participates in the pathogenesis of many human disorders. NLRP3 inflammasome plays an important role in the pathogenesis of rheumatic disease such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), ankylosing spondylitis (AS), Sjögren's syndrome (SS), dermatomyositis/polymyositis (DM/PM), gout, and systemic sclerosis (SSc). For example, NLRP3 inflammasome has been found highly activated in synovial tissues and peripheral blood mononuclear cells from RA patients. In this paper, we will discuss the role of NLRP3 inflammasome in the pathogenesis of rheumatic disease.

Targeting the Nod-like receptor protein 3 Inflammasome with inhibitor MCC950 rescues lipopolysaccharide-induced inhibition of osteogenesis in Human periodontal ligament cells

OBJECTIVE

We aim to investigate whether lipopolysaccharide-stimulated activition of Nod-like receptor protein 3 (NLRP3) Inflammasome inhibits osteogenesis in Human periodontal ligament cells (HPDLCs). Futhermore, to study whether MCC950 (a inhibitor of NLRP3 Inflammasome) rescues lipopolysaccharide-induced inhibition of osteogenesis in HPDLCs as well as the underlying mechanisms.

METHODS

HPDLCs were isolated from periodontal ligament of healthy orthodontic teeth from teenagers, and cells surface marker protein were detected by flow cytometry. Cells viability were determined by Cell Counting kit 8 assay. Enzyme-linked immunosorbent assay was used to analyze the secretion of proinflammatory factors. Western blot and real-time quantitative polymerase chain reaction (RT-qPCR) were measured assessing the expression of NLRP3 and Caspase-1. RT-qPCR, Alizarin red staining and Alkaline phosphatase staining were tested to determine the osteogenic differentiation capacity of HPDLCs.

RESULTS

It was found that lipopolysaccharide in the range of concentrations from 10 to 100 μg/ml significantly inhibited HPDLCs viability at 24 h and significantly improved proinflammatory cytokine expressions at 8 h and 24 h. MCC950 reversed lipopolysaccharide-stimulated proinflammatory cytokine expressions including interleukin-1β and interleukin-18, but not tumor necrosis factor-α. In addition, MCC950 rescued the lipopolysaccharide-inhibited osteogenic gene (Alkaline phosphatase, Runt-related transcription factor 2, and Osteocalcin). Moreover, MCC950 downregulated lipopolysaccharide-induced relative protein of NLRP3 Inflammasome signaling pathway, such as NLRP3 and Caspase-1.

CONCLUSION

MCC950 rescues lipopolysaccharide-induced inhibition of osteogenesis in HPDLCs via blocking NLRP3 Inflammasome signaling pathway, and it may be used as a promising therapeutic agent for periodontitis or periondontal regenerative related disease.

Activation of CB2 receptor inhibits pyroptosis and subsequently ameliorates cecal ligation and puncture-induced sepsis

BACKGROUND

Cannabinoid receptor 2 (CB2), whose activities are upregulated during sepsis, may be related to the regulation of inflammatory programmed cell death called pyroptosis. The aim of this study is to investigate the role of CB2 activation in attenuation of inflammation through inhibiting pyroptosis in cecal ligation puncture (CLP)-induced sepsis andlipopolysaccharide (LPS) + ATP-stimulated macrophages.

METHODS

C57BL/6 mice were subjected to CLP procedure and treated with CB2 agonist HU308 and CB2 antagonist AM630. Lung tissues were collected for analyses of lung W/D ratio, inflammatory factors levels, and pyroptosis-related protein expression. Murine bone-marrow-derived macrophages (BMDM) were treated with LPS and ATP to construct a septic model in vitro in the presence of HU308 and AM630 for assessment of cell injury, cytokine levels and pyroptosis-related protein expression accordingly. To verify the relationship between CB2 receptors and pyroptosis in the process of inflammatory response, BMDM were transduced with CB2 receptors knockdown lentiviral vectors in the presence of HU308 and AM630 for assessment of pyroptosis-related protein expression.

RESULTS

CB2 activation ameliorated the release of inflammatory mediators. The results showed that CLP-induced pyroptosis was elevated, and CB2 agonist HU308 treatment inhibited the pyroptosis activity through a decrease of the protein levels of NLRP3 as well as caspase-1 and GSDMD activation. Similar results were obtained in BMDM after LPS and ATP treatment. Treatment with CB2 knockdown lentiviral particles prevented the HU308-induced decreases in cell pyroptosis, demonstrating that endogenous CB2 receptors are required for the cannabinoid-induced cell protection.

CONCLUSIONS

CB2 receptors activation plays a protective role in sepsis through inhibition of pyroptosis. The effect of CB2 receptors against pyroptosis depends on the existence of endogenous CB2 receptors.

Danger-associated molecular pattern molecules take unexpectedly a central stage in Nlrp3 inflammasome-caspase-1-mediated trafficking of hematopoietic stem/progenitor cells

Like their homing after transplantation to bone marrow (BM), the mobilization of hematopoietic stem/progenitor cells (HSPCs) is still not fully understood, and several overlapping pathways are involved. Several years ago our group proposed that sterile inflammation in the BM microenvironment induced by pro-mobilizing agents is a driving force in this process. In favor of our proposal, both complement cascade (ComC)-deficient and Nlrp3 inflammasome-deficient mice are poor G-CSF and AMD3100 mobilizers. It is also known that the Nlrp3 inflammasome mediates its effects by activating caspase-1, which is responsible for proteolytic activation of interleukin-1β (IL-1β) and interleukin-18 (IL-18) and their release from cells along with several danger-associated molecular pattern molecules (DAMPs). We observed in the past that IL-1β and IL-18 independently promote mobilization of HSPCs. In the current work we demonstrated that caspase-1-KO mice are poor mobilizers, and, to our surprise, administration of IL-1β or IL-18, as in the case of Nlrp3-KO animals, does not correct this defect. Moreover, neither Caspase-1-KO nor Nlrp3-KO mice properly activated the ComC to execute the mobilization process. Interestingly, mobilization in these animals and activation of the ComC were both restored after injection of the DAMP cocktail eATP+HGMB1+S100A9, the components of which are normally released from cells in an Nlrp3 inflammasome-caspase-1-dependent manner. In addition, we report that caspase-1-deficient HSPCs show a decrease in migration in response to BM homing factors and engraft more poorly after transplantation. These results for the first time identify caspase-1 as an orchestrator of HSPC trafficking.

Adverse Cardiovascular Effects of Anti-COVID-19 Drugs

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 infection is the cause of the ongoing global pandemic. Mortality from COVID-19 infection is particularly high in patients with cardiovascular diseases. In addition, COVID-19 patients with preexisting cardiovascular comorbidities have a higher risk of death. Main cardiovascular complications of COVID-19 are myocardial infarction, myocarditis, acute myocardial injury, arrhythmias, heart failure, stroke, and venous thromboembolism. Therapeutic interventions in terms of drugs for COVID-19 have many cardiac adverse effects. Here, we review the relative therapeutic efficacy and adverse effects of anti-COVID-19 drugs.

Astragaloside IV ameliorates diabetic nephropathy in db/db mice by inhibiting NLRP3 inflammasome‑mediated inflammation

Diabetic nephropathy (DN) is a primary cause of end‑stage renal disease. Despite the beneficial effects of astragaloside IV (AS)‑IV on renal disease, the underlying mechanism of its protective effects against DN has not been fully determined. The aims of the present study were to assess the effects of AS‑IV against DN in db/db mice and to explore the mechanism of AS‑IV involving the NLR family pyrin domain containing 3 (NLRP3), caspase‑1 and interleukin (IL)‑1β pathways. The 8‑week‑old db/db mice received 40 mg/kg AS‑IV once a day for 12 weeks via intragastric administration. Cultured mouse podocytes were used to further confirm the underlying mechanism in vitro. AS‑IV effectively reduced weight gain, hyperglycemia and the serum triacylglycerol concentration in db/db mice. AS‑IV also reduced urinary albumin excretion, urinary albumin‑to‑creatinine ratio and creatinine clearance rate, as well as improved renal structural changes, accompanied by the upregulation of the podocyte markers podocin and synaptopodin. AS‑IV significantly inhibited the expression levels of NLRP3, caspase‑1 and IL‑1β in the renal cortex, and reduced the serum levels of tumor necrosis factor (TNF)‑α and monocyte chemoattractant protein‑1. In high glucose‑induced podocytes, AS‑IV significantly improved the expression levels of NLRP3, pro‑caspase‑1 and caspase‑1, and inhibited the cell viability decrease in a dose‑dependent manner, while NLRP3 overexpression eliminated the effect of AS‑IV on podocyte injury and the inhibition of the NLRP3 and caspase‑1 pathways. The data obtained from in vivo and in vitro experiments demonstrated that AS‑IV ameliorated renal functions and podocyte injury and delayed the development of DN in db/db mice via anti‑NLRP3 inflammasome‑mediated inflammation.

The Nlrp3 inflammasome - the evolving story of its positive and negative effects on hematopoiesis

PURPOSE OF REVIEW

Hematopoiesis is co-regulated by innate immunity, which is an ancient evolutionary defense mechanism also involved in the development and regeneration of damaged tissues. This review seeks to shed more light on the workings of the Nlrp3 inflammasome, which is an intracellular innate immunity pattern recognition receptor and sensor of changes in the hematopoietic microenvironment, and focus on its role in hematopoieisis.

RECENT FINDINGS

Hematopoietic stem progenitor cells (HSPCs) are exposed to several external mediators of innate immunity. Moreover, since hemato/lymphopoietic cells develop from a common stem cell, their behavior and fate are coregulated by intracellular innate immunity pathways. Therefore, the Nlrp3 inflammasome is functional both in immune cells and in HSPCs and affects hematopoiesis in either a positive or negative way, depending on its activity level. Specifically, while a physiological level of activation regulates the trafficking of HSPCs and most likely maintains their pool in the bone marrow, hyperactivation may lead to irreversible cell damage by pyroptosis and HSPC senescence and contribute to the origination of myelodysplasia and hematopoietic malignancies.

SUMMARY

Modulation of the level of Nrp3 inflammasome activation will enable improvements in HSPC mobilization, homing, and engraftment strategies. It may also control pathological activation of this protein complex during HSPC senescence, graft-versus-host disease, the induction of cytokine storms, and the development of hematopoietic malignancies.

Tanshinones inhibit NLRP3 inflammasome activation by alleviating mitochondrial damage to protect against septic and gouty inflammation

Tanshinones, the active ingredients derived from the roots of Salvia miltiorrhiza, have been widely used as traditional medicinal herbs for treating human diseases. Although tanshinones showed anti-inflammatory effects in many studies, large knowledge gaps remain regarding their underlying mechanisms. Here, we identified 15 tanshinones that suppressed the activation of NLRP3 inflammasome and studied their structure-activity relationships. Three tanshinones (tanshinone IIA, isocryptotanshinone, and dihydrotanshinone I) reduced mitochondrial reactive-oxygen species production in lipopolysaccharide (LPS)/nigericin-stimulated macrophages and correlated with altered mitochondrial membrane potentials, mitochondria complexes activities, and adenosine triphosphate and protonated-nicotinamide adenine dinucleotide production. The tanshinones may confer mitochondrial protection by promoting autophagy and the AMP-activated protein kinase pathway. Importantly, our findings demonstrate that dihydrotanshinone I improved the survival of mice with LPS shock and ameliorated inflammatory responses in septic and gouty animals. Our results suggest a potential pharmacological mechanism whereby tanshinones can effectively treat inflammatory diseases, such as septic and gouty inflammation.

Identification of Tubocapsanolide A as a novel NLRP3 inhibitor for potential treatment of colitis

Increasing evidence have reported that NLRP3 inflammasome has a crucial role in various kinds of immunological diseases including colitis. However, there have only a few drug candidates directly targeting inflammasomes for the therapy of colitis. Here, we first reported that Tubocapsanolide A (TA), a natural small molecule, as a novel inhibitor of NLRP3 inflammasome for the treatment of colitis. TA inhibited the activation of NLRP3 inflammasome and suppressed the secretion of IL-1β and IL-18 in macrophages. Moreover, the ASC oligomerization was inhibited by TA. The assembly of the NLRP3 inflammasome was also restrained by TA, while had little effects on potassium and chloride efflux. Biolayer interferometry analysis showed that TA could directly bind to NLRP3. Importantly, LC-MS/MS analysis further demonstrated that TA covalently bound to the cysteine 514 residue (Cys514) of NLRP3. In vivo experiments showed that TA remarkably ameliorated DSS-induced experimental colitis in mice. However, the protection of TA against DSS-induced experimental colitis was abrogated in NLRP3-deficient (Nlrp3^-/-) mice. Taken together, this study indicates TA as a novel inhibitor of NLRP3, which identifies Cys514 as a novel regulatory site of NLRP3 and suggests TA as a promising candidate compound for the treatment of colitis.

The Role of NLRP3 Inflammasome in Cerebrovascular Diseases Pathology and Possible Therapeutic Targets

Cerebrovascular diseases are pathological conditions involving impaired blood flow in the brain, primarily including ischaemic stroke, intracranial haemorrhage, and subarachnoid haemorrhage. The nucleotide-binding and oligomerisation (NOD) domain-like receptor (NLR) family pyrin domain (PYD)-containing 3 (NLRP3) inflammasome is a protein complex and a vital component of the immune system. Emerging evidence has indicated that the NLRP3 inflammasome plays an important role in cerebrovascular diseases. The function of the NLRP3 inflammasome in the pathogenesis of cerebrovascular diseases remains an interesting field of research. In this review, we first summarised the pathological mechanism of cerebrovascular diseases and the pathological mechanism of the NLRP3 inflammasome in aggravating atherosclerosis and cerebrovascular diseases. Second, we outlined signalling pathways through which the NLRP3 inflammasome participates in aggravating or mitigating cerebrovascular diseases. Reactive oxygen species (ROS)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), ROS/thioredoxin-interacting protein (TXNIP) and purinergic receptor-7 (P2X7R) signalling pathways can activate the NLRP3 inflammasome; activation of the NLRP3 inflammasome can aggravate cerebrovascular diseases by mediating apoptosis and pyroptosis. Autophagy/mitochondrial autophagy, nuclear factor E2-related factor-2 (Nrf2), interferon (IFN)-β, sirtuin (SIRT), and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) reportedly alleviate cerebrovascular diseases by inhibiting NLRP3 inflammasome activation. Finally, we explored specific inhibitors of the NLRP3 inflammasome based on the two-step activation of the NLRP3 inflammasome, which can be developed as new drugs to treat cerebrovascular diseases.

Proprotein Convertase Subtilisin/Kexin Type 9: A View beyond the Canonical Cholesterol-Lowering Impact

Proprotein convertase subtilisin/kexin type 9 (PCSK9), mainly synthetized and released by the liver, represents one of the key regulators of low-density lipoprotein cholesterol. Although genetic and interventional studies have demonstrated that lowering PCSK9 levels corresponds to a cardiovascular benefit, identification of non-cholesterol-related processes has emerged since its discovery. Besides liver, PCSK9 is also expressed in many tissues (eg, intestine, endocrine pancreas, and brain). The aim of the present review is to describe and discuss PCSK9 pathophysiology and possible non-lipid-lowering effects whether already extensively characterized (eg, inflammatory burden of atherosclerosis, triglyceride-rich lipoprotein metabolism, and platelet activation), or to be unraveled (eg, in adipose tissue). The identification of novel transcriptional factors in the promoter region of human PCSK9 (eg, ChREBP) characterizes new mechanisms explaining how controlling intrahepatic glucose may be a therapeutic strategy to reduce cardiovascular risk in type 2 diabetes. Finally, the evidence describing PCSK9 as involved in cell proliferation and apoptosis raises the possibility of this protein being involved in cancer risk.

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.

MicroRNA-302c-3p inhibits endothelial cell pyroptosis via directly targeting NOD-, LRR- and pyrin domain-containing protein 3 in atherosclerosis

Inflammation and endothelial dysfunction are important participants and drivers in atherosclerosis. NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome activation and the resulting pyroptosis are involved in the initiation and vicious circle of chronic inflammation, thus playing an indispensable role in atherosclerosis. Accordingly, blocking the activation of NLRP3 inflammasome may be a promising treatment strategy to blunt the progression of atherosclerosis. In this study, it was demonstrated that miR-302c-3p exerted anti-pyroptosis effects by directly targeting NLRP3 in vivo and in vitro. In brief, the expression of miR-302c-3p was down-regulated whereas the expression of NLRP3 was up-regulated in human plaques and in vitro pyroptosis model of endothelial cells. Overexpression of miR-302c-3p suppressed endothelial cell pyroptosis by targeting specific sites of NLRP3. By comparison, down-regulation of endogenous miR-302c-3p led to the opposite results, which were reversed by silencing the expression of NLRP3. Finally, the up-regulation of miR-302c-3p inhibited the inflammation and pyroptosis of atherosclerosis mouse model. In conclusion, miR-302c-3p may be a powerful and attractive target for suppressing endothelial inflammation and pyroptosis, providing a novel strategy for preventing or alleviating the progression of atherosclerosis.

Glaesserella parasuis induces inflammatory response in 3D4/21 cells through activation of NLRP3 inflammasome signaling pathway via ROS

Glaesserella parasuis (G. parasuis) is an important pathogenic bacterium that can cause Glässer's disease, and it has resulted in tremendous economic losses to the global swine industry. The intensive pulmonary inflammatory response caused by G. parasuis infection is the main cause of lung injury and death in pigs. However, the exact mechanism by which it causes severe pulmonary inflammation is not fully understood yet. In this study, severe pneumonia was observed in piglets infected with G. parasuis; and an infection cell model was established using porcine alveolar macrophages cell line 3D4/21, which was determined to be susceptible to G. parasuis infection in vitro. G. parasuis infection of 3D4/21 cells induced upregulation of proinflammatory cytokines TNF-α, IL-1β, IL-18 and production of intracellular reactive oxygen species (ROS). The expression of IL-1β related to activation of the NLRP3 inflammasome signaling pathway, which had not been shown before in G. parasuis infection. Furthermore, it was first found that release of intracellular ROS, which was mediated by NADPH oxidase in 3D4/21 cells, was found crucial for the activation of the NLRP3 signaling pathway and promoted the expression of proinflammatory cytokines, such as TNF-α and IL-1. In general, this study explored the specific mechanism of severe pulmonary inflammation caused by G. parasuis infection, and provides a foundation for further elucidating the pathogenic mechanism of G. parasuis.

Carbon monoxide-triggered health effects: the important role of the inflammasome and its possible crosstalk with autophagy and exosomes

Carbon monoxide (CO) has long been known as a "silent killer" because of its ability to bind hemoglobin (Hb), leading to reduced oxygen carrying capacity of Hb, which is the main cause of CO poisoning (COP) in humans. Emerging studies suggest that mitochondria is a key target of CO action that can impact key biological processes, including apoptosis, cellular proliferation, inflammation, and autophagy. Despite its toxicity at high concentrations, CO also exhibits cyto- and tissue-protective effects at low concentrations in animal models of organ injury and disease. Specifically, CO modulates the production of pro- or anti-inflammatory cytokines and mediators by regulating the NLRP3 inflammasome. Given that human diseases are strongly associated with inflammation, a deep understanding of the exact mechanism is helpful for treatment. Autophagic factors and inflammasomes interact in various situations, including inflammatory disease, and exosomes might function as the bridge between the inflammasome and autophagy activation. Thus, the interplay among autophagy, mitochondrial dysfunction, exosomes, and the inflammasome may play pivotal roles in the health effects of CO. In this review, we summarize the latest research on the beneficial and toxic effects of CO and their underlying mechanisms, focusing on the important role of the inflammasome and its possible crosstalk with autophagy and exosomes. This knowledge may lead to the development of new therapies for inflammation-related diseases and is essential for the development of new therapeutic strategies and biomarkers of COP.