AKT controls NLRP3 inflammasome activation by inducing DDX3X phosphorylation

Protective Effects of Trans-Chalcone on Myocardial Ischemia and Reperfusion Challenge through Targeting Phosphoinositide 3-kinase/Akt-inflammosome Interaction

Ischemia-reperfusion (IR) injury remains a pivotal contributor to myocardial damage following acute coronary events and revascularization procedures. Phosphoinositide 3-kinase (PI3K), a key mediator of cell survival signaling, plays a central role in regulating inflammatory responses and cell death mechanisms. Trans-chalcone (Tch), a natural compound known for its anti-inflammatory activities, has shown promise in various disease models. The aim of the current study was to investigate the potential protective effects of Tch against myocardial injury induced by ischemia and reperfusion challenges by targeting the PI3K-inflammasome interaction. Experimental models utilizing male rats subjected to an in vivo model of IR injury and myocardial infarction were employed. Administration of Tch (100 μg/kg, intraperitoneally) significantly reduced myocardial injury, as indicated by limited infarct size and decreased levels of the myocardial enzyme troponin. Mechanistically, Tch upregulated PI3K expression, thereby inhibiting the activity of the NOD-like receptor protein 3 inflammasome followed by the activation of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18. Moreover, it mitigated oxidative stress and suppressed vascular-intercellular adhesion molecules, contributing to its cardioprotective effects. The PI3K/Akt pathway inhibitor LY294002 considerably attenuated the beneficial effects of Tch. These findings highlight the therapeutic potential of Tch in ameliorating myocardial injury associated with IR insults through its modulation of the PI3K/Akt-inflammasome axis. The multifaceted mechanisms underlying its protective effects signify Tch as a promising candidate for further exploration in developing targeted therapies aimed at mitigating ischemic heart injury and improving clinical outcomes in cardiovascular diseases characterized by IR injury.

Anticancer mechanisms on pyroptosis induced by Oridonin: New potential targeted therapeutic strategies

Pyroptosis is a type of inflammatory cell death that is triggered by the formation of pores on the cell membrane by gasdermin (GSDM) family proteins. This process activates inflammasomes and leads to the maturation and release of proinflammatory cytokines such as interleukin-1β (IL-1β) and interleukin-18 (IL-18). Pyroptosis, a form of programmed cell death, has been found to be associated with various biomolecules such as caspases, granzymes, non-coding RNA (lncRNA), reactive oxygen species (ROS), and NOD-like receptor protein 3 (NLRP3). These biomolecules have been shown to play a dual role in cancer by affecting cell proliferation, metastasis, and the tumor microenvironment (TME), resulting in both tumor promotion and anti-tumor effects. Recent studies have found that Oridonin (Ori) has anti-tumor effects by regulating pyroptosis through various pathways. Ori can inhibit pyroptosis by inhibiting caspase-1, which is responsible for activating pyroptosis of the canonical pathway. Additionally, Ori can inhibit pyroptosis by inhibiting NLRP3, which is responsible for activating pyroptosis of the noncanonical pathway. Interestingly, Ori can also activate pyroptosis by activating caspase-3 and caspase-8, which are responsible for activating pyroptosis of the emerging pathway; Ori has been found to be effective in inhibiting pyroptosis by blocking the action of perforin, which is responsible for facilitating the entry of granzyme into cells and activating pyroptosis. Additionally, Ori plays a crucial role in regulating pyroptosis by promoting the accumulation of ROS while inhibiting the ncRNA and NLRP3 pathways. It is worth noting that all of these pathways ultimately regulate pyroptosis by influencing the cleavage of GSDM, which is a key factor in the process. These studies concludes that Ori has extensive anti-cancer effects that are related to its potential regulatory function on pyroptosis. The paper summarizes several potential ways in which Ori participates in the regulation of pyroptosis, providing a reference for further study on the relationship between Ori, pyroptosis, and cancer.

The Role of Post-Translational Modifications in Regulation of NLRP3 Inflammasome Activation

Pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) induce NLRP3 inflammasome activation, and subsequent formation of active caspase-1 as well as the maturation of interleukin-1β (IL-1β) and gasdermin D (GSDMD), mediating the occurrence of pyroptosis and inflammation. Aberrant NLRP3 inflammasome activation causes a variety of diseases. Therefore, the NLRP3 inflammasome pathway is a target for prevention and treatment of relative diseases. Recent studies have suggested that NLRP3 inflammasome activity is closely associated with its post-translational modifications (PTMs). This review focuses on PTMs of the components of the NLRP3 inflammasome and the resultant effects on regulation of its activity to provide references for the exploration of the mechanisms by which the NLRP3 inflammasome is activated and controlled.

Exosomal Lnc NEAT1 from endothelial cells promote bone regeneration by regulating macrophage polarization via DDX3X/NLRP3 axis

BACKGROUND

Bone regeneration is a complex procedure that involves an interaction between osteogenesis and inflammation. Macrophages in the microenvironment are instrumental in bone metabolism. Amount evidence have revealed that exosomes transmitting lncRNA is crucial nanocarriers for cellular interactions in various biotic procedures, especially, osteogenesis. However, the underlying mechanisms of the regulatory relationship between the exosomes and macrophages are awaiting clarification. In the present time study, we aimed to explore the roles of human umbilical vein endothelial cells (HUVECs)-derived exosomes carrying nuclear enrichment enriched transcript 1 (NEAT1) in the osteogenesis mediated by M2 polarized macrophages and elucidate the underlying mechanisms.

RESULTS

We demonstrated HUVECs-derived exosomes expressing NEAT1 significantly enhanced M2 polarization and attenuated LPS-induced inflammation in vitro. Besides, the conditioned medium from macrophages induced by the exosomes indirectly facilitated the migration and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Mechanically, Exos carrying NEAT1 decreased remarkably both expression of dead-box helicase 3X-linked (DDX3X) and nod-like receptor protein 3 (NLRP3). The level of NLRP3 protein increased significantly after RAW264.7 cells transfected with DDX3X overexpression plasmid. Additionally, the knockdown of NEAT1 in exosomes partially counteracted the aforementioned effect of Exos. The results of air pouch rat model demonstrated that HUVECs-derived exosomes increased anti-inflammatory cytokines (IL-10) and decreased pro-inflammatory cytokines (IL-1β and IL-6) significantly in vivo, contributing to amelioration of LPS-induced inflammation. Afterwards, we further confirmed that the HUVECs-derived exosomes encapsulated in alginate/gelatin methacrylate (GelMA) interpenetrating polymer network (IPN) hydrogels could promote the bone regeneration, facilitate the angiogenesis, increase the infiltration of M2 polarized macrophages as well as decrease NLRP3 expression in the rat calvarial defect model.

CONCLUSIONS

HUVECs-derived exosomes enable transmitting NEAT1 to alleviate inflammation by inducing M2 polarization of macrophages through DDX3X/NLRP3 regulatory axis, which finally contributes to osteogenesis with the aid of alginate/GelMA IPN hydrogels in vivo. Thus, our study provides insights in bone healing with the aid of HUVECs-derived exosomes-encapsulated composite hydrogels, which exhibited potential towards the use of bone tissue engineering in the foreseeable future.

The involvement of DDX3X in compression-induced nucleus pulposus pyroptosis

OBJECTIVE

A study has been conducted to investigate the relationship between DDX3X and nucleus pulposus (NP) pyroptosis.

METHODS

DDX3X and pyroptosis-related proteins (Caspase-1, Full-length GSDMD, Cleaved GSDMD) were measured in compression-induced human NP cells and tissue. DDX3X was overexpressed or knocked down by gene transfection. The expressions of NLRP3, ASC, and pyroptosis-related proteins were detected by Western blot assay. IL-1β and IL-18 were detected by ELISA. HE staining and immunohistochemistry were used to observe the expression of DDX3X, NLRP3, and Caspase-1 in the rat model of compression-induced disc degeneration.

RESULTS

DDX3X, NLRP3, and Caspase-1 were highly expressed in degenerated NP tissue. Overexpression of DDX3X induced pyroptosis in NP cells and increased levels of NLRP3, IL-1β, IL-18, and pyroptosis-related proteins. Knockdown of DDX3X showed an opposite trend to overexpression of DDX3X. The NLRP3 inhibitor CY-09 effectively prevented the up-regulation of the expression of IL-1β, IL-18, ASC, Pro-caspase-1, Full-length GSDMD, and Cleaved GSDMD. Increased expression of DDX3X, NLRP3, and Caspase-1 was observed in the rat model of compression-induced disc degeneration.

CONCLUSION

Our study showed that DDX3X mediates pyroptosis of NP cells by upregulating NLRP3 expression, which ultimately leads to intervertebral disc degeneration (IDD). This discovery deepens the understanding of IDD pathogenesis and provides a promising and novel therapeutic target for IDD.

Total saponins of Aralia elata (Miq.) Seem. alleviate myocardial ischemia-reperfusion injury by promoting NLRP3-inflammasome inactivation via PI3K/Akt signaling

Total saponins of Aralia elata (Miq.) Seem. (TSAE) have been shown to play a significant role in cardiovascular protection, anti-tumor, liver protection, anti-oxidant stress, and anti-inflammation. However, the specific mechanisms of TSAE in myocardial ischemia-reperfusion injury (MIRI) remain largely elusive. Hearts from male Wistar rats were used to establish the isolated heart MIRI model. Using a multichannel physiological recorder, the whole course heart rate (HR), left ventricular development pressure (LVDP), and maximum rise/decrease rate of left ventricular pressure (±dp/dt_max ) were recorded. 2,3,5-triphenyl-2H-tetrazolium chloride staining observed the infarct area, while hematoxylin & eosin staining detected pathological changes in myocardial tissue. Creatine kinase, lactate dehydrogenase, total superoxide dismutase, and malondialdehyde concentrations were determined by enzyme-linked immunosorbent assay. Immunohistochemistry, quantitative PCR, and western blot assay were used to assess the amounts of IL-18 and IL-1β, NLR family protein (NLRP3) inflammasome- and apoptosis-related proteins, respectively. Treatment with TSAE or MCC950 (NLRP3-specific inhibitor) significantly reduced the myocardial infarction area, alleviated pathological changes in myocardial tissues, enhanced LVDP and ±dp/dt_max levels, prevented myocardial oxidative damage, and inhibited NLRP3 inflammasome formation. In addition, TSAE enhanced Akt and GSK3β phosphorylation, and LY29004 co-reperfusion markedly diminished the protective role of TSAE reperfusion on cardiac function, oxidative damage, and inflammatory responses. Collectively, TSAE treatment exhibited a protective effect on I/R-triggered inflammatory responses, cell necrosis, and oxidative stress injury by stimulating PI3K/Akt signaling-mediated NLRP3 inflammasome inhibition.

Inhibition of DDX3X ameliorated CD4+ T cells pyroptosis and improves survival in septic mice

Over-expression of DDX3X mRNA is associated with T cell loss in septic patients. This study aimed to investigate the molecular mechanism of DDX3X on T cell reduction in sepsis. The sepsis model was established using lipopolysaccharide stimulation in vitro and cecal ligation and puncture (CLP) surgery in vivo. Results showed that the expression of DDX3X was significantly upregulated in CD4⁺ T cells in sepsis. RK-33, the inhibitor of DDX3X, was found to dramatically increase CD4⁺ T cell counts and prolong the survival rate of mice with sepsis. The results also showed that the expression of caspase-1/GSDMD in CD4⁺ T cells was significantly increased in vitro and in vivo, and RK-33 can substantially reduce CD4⁺ T cell pyroptosis through inhibiting NLRP3/caspase-1/GSDMD. Globally, our results suggest that DDX3X is involved in the loss of CD4⁺ T cells partly through activating the pyroptotic pathway during sepsis, which may provide potential targets for therapeutic interventions in this highly lethal disease.

NLRP3-mediated pyroptosis in diabetic nephropathy

Diabetic nephropathy (DN) is the main cause of end-stage renal disease (ESRD), which is characterized by a series of abnormal changes such as glomerulosclerosis, podocyte loss, renal tubular atrophy and excessive deposition of extracellular matrix. Simultaneously, the occurrence of inflammatory reaction can promote the aggravation of DN-induced kidney injury. The most important processes in the canonical inflammasome pathway are inflammasome activation and membrane pore formation mediated by gasdermin family. Converging studies shows that pyroptosis can occur in renal intrinsic cells and participate in the development of DN, and its activation mechanism involves a variety of signaling pathways. Meanwhile, the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome can not only lead to the occurrence of inflammatory response, but also induce pyroptosis. In addition, a number of drugs targeting pyroptosis-associated proteins have been shown to have potential for treating DN. Consequently, the pathogenesis of pyroptosis and several possible activation pathways of NLRP3 inflammasome were reviewed, and the potential drugs used to treat pyroptosis in DN were summarized in this review. Although relevant studies are still not thorough and comprehensive, these findings still have certain reference value for the understanding, treatment and prognosis of DN.

The multifaceted roles of NLRP3-modulating proteins in virus infection

The innate immune response to viruses is critical for the correct establishment of protective adaptive immunity. Amongst the many pathways involved, the NLRP3 [nucleotide-binding oligomerisation domain (NOD)-like receptor protein 3 (NLRP3)] inflammasome has received considerable attention, particularly in the context of immunity and pathogenesis during infection with influenza A (IAV) and SARS-CoV-2, the causative agent of COVID-19. Activation of the NLRP3 inflammasome results in the secretion of the proinflammatory cytokines IL-1β and IL-18, commonly coupled with pyroptotic cell death. While this mechanism is protective and key to host defense, aberrant NLRP3 inflammasome activation causes a hyperinflammatory response and excessive release of cytokines, both locally and systemically. Here, we discuss key molecules in the NLRP3 pathway that have also been shown to have significant roles in innate and adaptive immunity to viruses, including DEAD box helicase X-linked (DDX3X), vimentin and macrophage migration inhibitory factor (MIF). We also discuss the clinical opportunities to suppress NLRP3-mediated inflammation and reduce disease severity.

Inflammasome-targeting natural compounds in inflammatory bowel disease: Mechanisms and therapeutic potential

Inflammatory bowel disease (IBD), mainly including Crohn’s disease and ulcerative colitis, seriously affects human health and causes substantial social and economic burden. The pathogenesis of IBD is still not fully elucidated, whereas recent studies have demonstrated that its development is associated with the dysfunction of intestinal immune system. Accumulating evidence have proven that inflammasomes such as NLRP3 and NLRP6 play a prominent role in the pathogenesis of IBD. Thus, regulating the activation of inflammasomes have been considered to be a promising strategy in IBD treatment. A number of recent studies have provided evidence that blocking inflammasome related cytokine IL-1β can benefit a group of IBD patients with overactivation of NLRP3 inflammasome. However, therapies for targeting inflammasomes with high efficacy and safety are rare. Traditional medical practice provides numerous medical compounds that may have a role in treatment of various human diseases including IBD. Recent studies demonstrated that numerous medicinal herb derived compounds can efficiently prevent colon inflammation in animal models by targeting inflammasomes. Herein, we summarize the main findings of these studies focusing on the effects of traditional medicine derived compounds on colitis treatment and the underlying mechanisms in regulating the inflammasomes. On this basis, we provide a perspective for future studies regarding strategies to improve the efficacy, specificity and safety of available herbal compounds, and to discover new compounds using the emerging new technologies, which will improve our understanding about the roles and mechanisms of herbal compounds in the regulation of inflammasomes and treatment of IBD.

Focus on the Role of the NLRP3 Inflammasome in Multiple Sclerosis: Pathogenesis, Diagnosis, and Therapeutics

Neuroinflammation is initiated with an aberrant innate immune response in the central nervous system (CNS) and is involved in many neurological diseases. Inflammasomes are intracellular multiprotein complexes that can be used as platforms to induce the maturation and secretion of proinflammatory cytokines and pyroptosis, thus playing a pivotal role in neuroinflammation. Among the inflammasomes, the nucleotide-binding oligomerization domain-, leucine-rich repeat- and pyrin domain-containing 3 (NLRP3) inflammasome is well-characterized and contributes to many neurological diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), and ischemic stroke. MS is a chronic autoimmune disease of the CNS, and its hallmarks include chronic inflammation, demyelination, and neurodegeneration. Studies have demonstrated a relationship between MS and the NLRP3 inflammasome. To date, the pathogenesis of MS is not fully understood, and clinical studies on novel therapies are still underway. Here, we review the activation mechanism of the NLRP3 inflammasome, its role in MS, and therapies targeting related molecules, which may be beneficial in MS.

Pyrimidine Biosynthetic Enzyme CAD: Its Function, Regulation, and Diagnostic Potential

CAD (Carbamoyl-phosphate synthetase 2, Aspartate transcarbamoylase, and Dihydroorotase) is a multifunctional protein that participates in the initial three speed-limiting steps of pyrimidine nucleotide synthesis. Over the past two decades, extensive investigations have been conducted to unmask CAD as a central player for the synthesis of nucleic acids, active intermediates, and cell membranes. Meanwhile, the important role of CAD in various physiopathological processes has also been emphasized. Deregulation of CAD-related pathways or CAD mutations cause cancer, neurological disorders, and inherited metabolic diseases. Here, we review the structure, function, and regulation of CAD in mammalian physiology as well as human diseases, and provide insights into the potential to target CAD in future clinical applications.