Inhibiting NLRP3 Inflammasome Activation by CY-09 Helps to Restore Cerebral Glucose Metabolism in 3×Tg-AD Mice

Decoding NLRP3 Inflammasome Activation in Alzheimer's Disease: A Focus on Receptor Dynamics

Alzheimer's disease (AD) is a leading neurodegenerative disorder marked by progressive cognitive decline and significant neuropsychiatric disturbances. Neuroinflammation, mediated by the NLRP3 inflammasome, is increasingly recognized as a critical factor in AD pathogenesis. The NLRP3 inflammasome, a crucial component of the innate immune system, is activated in response to both pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In AD, amyloid-beta (Aβ) plaques and tau aggregates act as DAMPs, triggering NLRP3 inflammasome activation in microglia and astrocytes. This activation leads to the production of pro-inflammatory cytokines IL-1β and IL-18, contributing to chronic neuroinflammation and neuronal death. This review explores the intricate mechanisms involved in NLRP3 activation, with a particular focus on TREM-2, Msn Kinase MINK, NF-κB, Toll-like receptors, and P2X7 receptors. Understanding these mechanisms offers insight into the multifaceted regulation of the NLRP3 inflammasome and its impact on AD pathology. By elucidating the roles of TREM-2, MINK1, NF-κB, TLRs, and P2X7 receptors, this review highlights potential therapeutic targets for modulating NLRP3 activity. Targeting these pathways could offer novel strategies for mitigating neuroinflammation and slowing the progression of AD. The interplay between these receptors and signaling pathways underscores the complexity of NLRP3 inflammasome regulation and its significance in AD, providing a foundation for future research aimed at developing effective therapeutic interventions.

Cardiac fibroblast-derived mitochondria-enriched sEVs regulate tissue inflammation and ventricular remodeling post-myocardial infarction through NLRP3 pathway

Resident cardiac fibroblasts (CFs) play crucial roles in sensing injury signals and regulating inflammatory responses post-myocardial infarction (MI). Damaged mitochondria can be transferred extracellularly via various mechanisms, including extracellular vesicles (EVs). In this study, we aimed to investigate whether CFs could transfer damaged mitochondrial components via small EVs (sEVs) and elucidate their role in regulating inflammatory responses post-MI. Left anterior descending coronary artery ligation was performed in mice. Mitochondrial components in sEVs were detected using nanoflow cytometry. Differential protein expression in sEVs from normoxia and normoglycemia CFs (CFs-Nor-sEVs) and CFs post oxygen-glucose deprivation (CFs-OGD-sEVs) was identified using label-free proteomics. CFs-sEVs were co-cultured with mouse bone marrow-derived macrophages (BMDMs) to assess macrophage inflammatory responses. Effects of intramyocardial injection of CFs-sEVs were assessed in MI mice in the absence or presence of NLRP3 inhibitor CY-09. Results demonstrated that mitochondrial components were detected in CFs-derived sEVs post-MI. Damaged mitochondrial components were enriched in CFs-OGD-sEVs (CFs-mt-sEVs), which promoted pro-inflammatory phenotype activation of BMDMs in vitro. Myocardial injection of CFs-mt-sEVs enhanced tissue inflammation, aggravated cardiac dysfunction, and exacerbated maladaptive ventricular remodeling post-MI in vivo. Mechanistically, above effects were achieved via activation of NLRP3 and above effects could be reversed by NLRP3 inhibitor CY-09. This study indicates that CFs could transfer damaged mitochondrial components via the sEVs post-MI, promote macrophage inflammatory activation and exacerbate maladaptive ventricular remodeling post MI by activating NLRP3. Our findings highlight the potential therapeutic effects of inhibiting CFs-mt-sEVs and NLRP3 to improve cardiac function and attenuate ventricular remodeling post-MI.

NLRP3 inflammasome in neuroinflammation and central nervous system diseases

Neuroinflammation plays an important role in the pathogenesis of various central nervous system (CNS) diseases. The NLRP3 inflammasome is an important intracellular multiprotein complex composed of the innate immune receptor NLRP3, the adaptor protein ASC, and the protease caspase-1. The activation of the NLRP3 inflammasome can induce pyroptosis and the release of the proinflammatory cytokines IL-1β and IL-18, thus playing a central role in immune and inflammatory responses. Recent studies have revealed that the NLRP3 inflammasome is activated in the brain to induce neuroinflammation, leading to further neuronal damage and functional impairment, and contributes to the pathological process of various neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, and stroke. In this review, we summarize the important role of the NLRP3 inflammasome in the pathogenesis of neuroinflammation and the pathological course of CNS diseases and discuss potential approaches to target the NLRP3 inflammasome for the treatment of CNS diseases.

Role of Peripheral NLRP3 Inflammasome in Cognitive Impairments: Insights of Non-central Factors

Cognitive impairments are common clinical manifestation of Alzheimer's disease, vascular dementia, type 2 diabetes mellitus, and autoimmune diseases. Emerging evidence has suggested a strong correlation between peripheral chronic inflammation and cognitive impairments. For example, nearly 40% of individuals with inflammatory bowel disease also suffer from cognitive impairments. In this condition, NLRP3 inflammasome (NLRP3-I) generating pro-inflammatory cytokines like IL-1β serves as a significant effector, and its persistence exerts adverse effects to both periphery and the brain. Moreover, investigations on serum biomarkers of mild cognitive impairments have shown NLRP3-I components' upregulation, suggesting the involvement of peripheral inflammasome pathway in this disorder. Here, we systematically reviewed the current knowledge of NLRP3-I in inflammatory disease to uncover its potential role in bridging peripheral chronic inflammation and cognitive impairments. This review summarizes the molecular features and ignition process of NLRP3-I in inflammatory response. Meanwhile, various effects of NLRP3-I involved in peripheral inflammation-associated disease are also reviewed, especially its chronic disturbances to brain homeostasis and cognitive function through routes including gut-brain, liver-brain, and kidney-brain axes. In addition, current promising compounds and their targets relative to NLRP3-I are discussed in the context of cognitive impairments. Through the detailed investigation, this review highlights the critical role of peripheral NLRP3-I in the pathogenesis of cognitive disorders, and offers novel perspectives for developing effective therapeutic interventions for diseases associated with cognitive impairments. The present review outlines the current knowledge on the ignition of NLRP3-I in inflammatory disease and more importantly, emphasizes the role of peripheral NLRP3-I as a causal pathway in the development of cognitive disorders. Although major efforts to restrain cognitive decline are mainly focused on the central nervous system, it has become clear that disturbances from peripheral immune are closely associated with the dysfunctional brain. Therefore, attenuation of these inflammatory changes through inhibiting the NLRP3-I pathway in early inflammatory disease may reduce future risk of cognitive impairments, and in the meantime, considerations on such pathogenesis for combined drug therapy will be required in the clinical evaluation of cognitive disorders.

Inflammasomes in neurodegenerative diseases

Inflammasomes represent a crucial component of the innate immune system, which respond to threats by recognizing different molecules. These are known as pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs). In neurodegenerative diseases and neuroinflammation, the accumulation of misfolded proteins, such as beta-amyloid and alpha-synuclein, can lead to inflammasome activation, resulting in the release of interleukin (IL)-1β and IL-18. This activation also induces pyroptosis, the release of inflammatory mediators, and exacerbates neuroinflammation. Increasing evidence suggests that inflammasomes play a pivotal role in neurodegenerative diseases. Therefore, elucidating and investigating the activation and regulation of inflammasomes in these diseases is of paramount importance. This review is primarily focused on evidence indicating that inflammasomes are activated through the canonical pathway in these diseases. Inflammasomes as potential targets for treating neurodegenerative diseases are also discussed.

Design, synthesis, and biological evaluation of oridonin derivatives as novel NLRP3 inflammasome inhibitors for the treatment of acute lung injury

Acute lung injury (ALI) is a severe respiratory disorder closely associated with the excessive activation of the NLRP3 inflammasome. Oridonin (Ori), a natural diterpenoid compound, had been confirmed as a specific covalent NLRP3 inflammasome inhibitor, which was completely different from that of MCC950. However, the further clinical application of Ori was limited by its weak inhibitory activity against NLRP3 inflammasome (IC50 = 1240.67 nM). Fortunately, through systematic structure-optimization of Ori, D6 demonstrated the enhancement of IL-1β inhibitory activity (IC50 = 41.79 nM), which was better than the parent compound Ori. Then, by using SPR, molecular docking and MD simulation, D6 was verified to directly interact with NLRP3 via covalent and non-covalent interaction. The further anti-inflammatory mechanism studies were revealed that D6 could inhibit the activation of NLRP3 inflammasome without affecting the initiation phase of NLRP3 inflammasome activation, and D6 was a broad-spectrum and selective NLRP3 inflammasome inhibitor. Finally, D6 demonstrated a favorable therapeutic effect on LPS-induced ALI in mice model, and the potent pharmacodynamic effect of D6 was correlated with the specific inhibition of NLRP3 inflammasome activation in vivo. Thus, D6 is proved as a potent NLRP3 inhibitor, and has the potential to develop as a novel anti-ALI agent.

NLRP3/1-mediated pyroptosis: beneficial clues for the development of novel therapies for Alzheimer's disease

The inflammasome is a multiprotein complex involved in innate immunity that mediates the inflammatory response leading to pyroptosis, which is a lytic, inflammatory form of cell death. There is accumulating evidence that nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome-mediated microglial pyroptosis and NLRP1 inflammasome-mediated neuronal pyroptosis in the brain are closely associated with the pathogenesis of Alzheimer's disease. In this review, we summarize the possible pathogenic mechanisms of Alzheimer's disease, focusing on neuroinflammation. We also describe the structures of NLRP3 and NLRP1 and the role their activation plays in Alzheimer's disease. Finally, we examine the neuroprotective activity of small-molecule inhibitors, endogenous inhibitor proteins, microRNAs, and natural bioactive molecules that target NLRP3 and NLRP1, based on the rationale that inhibiting NLRP3 and NLRP1 inflammasome-mediated pyroptosis can be an effective therapeutic strategy for Alzheimer's disease.

NLRP3/1-mediated pyroptosis: beneficial clues for the development of novel therapies for Alzheimer's disease

The inflammasome is a multiprotein complex involved in innate immunity that mediates the inflammatory response leading to pyroptosis, which is a lytic, inflammatory form of cell death. There is accumulating evidence that nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome-mediated microglial pyroptosis and NLRP1 inflammasome-mediated neuronal pyroptosis in the brain are closely associated with the pathogenesis of Alzheimer's disease. In this review, we summarize the possible pathogenic mechanisms of Alzheimer's disease, focusing on neuroinflammation. We also describe the structures of NLRP3 and NLRP1 and the role their activation plays in Alzheimer's disease. Finally, we examine the neuroprotective activity of small-molecule inhibitors, endogenous inhibitor proteins, microRNAs, and natural bioactive molecules that target NLRP3 and NLRP1, based on the rationale that inhibiting NLRP3 and NLRP1 inflammasome-mediated pyroptosis can be an effective therapeutic strategy for Alzheimer's disease.

Role of NLRP3 inflammasome in central nervous system diseases

The central nervous system (CNS) is the most delicate system in human body, with the most complex structure and function. It is vulnerable to trauma, infection, neurodegeneration and autoimmune diseases, and activates the immune system. An appropriate inflammatory response contributes to defence against invading microbes, whereas an excessive inflammatory response can aggravate tissue damage. The NLRP3 inflammasome was the first one studied in the brain. Once primed and activated, it completes the assembly of inflammasome (sensor NLRP3, adaptor ASC, and effector caspase-1), leading to caspase-1 activation and increased release of downstream inflammatory cytokines, as well as to pyroptosis. Cumulative studies have confirmed that NLRP3 plays an important role in regulating innate immunity and autoimmune diseases, and its inhibitors have shown good efficacy in animal models of various inflammatory diseases. In this review, we will briefly discuss the biological characteristics of NLRP3 inflammasome, summarize the recent advances and clinical impact of the NLRP3 inflammasome in infectious, inflammatory, immune, degenerative, genetic, and vascular diseases of CNS, and discuss the potential and challenges of NLRP3 as a therapeutic target for CNS diseases.

NLRP inflammasomes in health and disease

NLRP inflammasomes are a group of cytosolic multiprotein oligomer pattern recognition receptors (PRRs) involved in the recognition of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) produced by infected cells. They regulate innate immunity by triggering a protective inflammatory response. However, despite their protective role, aberrant NLPR inflammasome activation and gain-of-function mutations in NLRP sensor proteins are involved in occurrence and enhancement of non-communicating autoimmune, auto-inflammatory, and neurodegenerative diseases. In the last few years, significant advances have been achieved in the understanding of the NLRP inflammasome physiological functions and their molecular mechanisms of activation, as well as therapeutics that target NLRP inflammasome activity in inflammatory diseases. Here, we provide the latest research progress on NLRP inflammasomes, including NLRP1, CARD8, NLRP3, NLRP6, NLRP7, NLRP2, NLRP9, NLRP10, and NLRP12 regarding their structural and assembling features, signaling transduction and molecular activation mechanisms. Importantly, we highlight the mechanisms associated with NLRP inflammasome dysregulation involved in numerous human auto-inflammatory, autoimmune, and neurodegenerative diseases. Overall, we summarize the latest discoveries in NLRP biology, their forming inflammasomes, and their role in health and diseases, and provide therapeutic strategies and perspectives for future studies about NLRP inflammasomes.

The mechanism underlying correlation of particulate matter-induced ferroptosis with inflammasome activation and iron accumulation in macrophages

Particulate matter (PM) is a global environmental hazard, which affects human health through free radical production, cell death induction, and immune responses. PM activates inflammasomes leading to excessive inflammatory responses and induces ferroptosis, a type of cell death. Despite ongoing research on the correlation among PM-induced ferroptosis, immune response, and inflammasomes, the underlying mechanism of this relationship has not been elucidated. In this study, we demonstrated the levels of PM-induced cell death and immune responses in murine macrophages, J774A.1 and RAW264.7, depending on the size and composition of particulate matter. PM2.5, with extraction ions, induced significant levels of cell death and immune responses; it induces lipid peroxidation, iron accumulation, and reactive oxygen species (ROS) production, which characterize ferroptosis. In addition, inflammasome-mediated cell death occurred owing to the excessive activation of inflammatory responses. PM-induced iron accumulation activates ferroptosis and inflammasome formation through ROS production; similar results were observed in vivo. These results suggest that the link between ferroptosis and inflammasome formation induced by PM, especially PM2.5 with extraction ions, is established through the iron-ROS axis. Moreover, this study can effectively facilitate the development of a new therapeutic strategy for PM-induced immune and respiratory diseases.

Acute kidney injury: exploring endoplasmic reticulum stress-mediated cell death

Acute kidney injury (AKI) is a global health problem, given its substantial morbidity and mortality rates. A better understanding of the mechanisms and factors contributing to AKI has the potential to guide interventions aimed at mitigating the risk of AKI and its subsequent unfavorable outcomes. Endoplasmic reticulum stress (ERS) is an intrinsic protective mechanism against external stressors. ERS occurs when the endoplasmic reticulum (ER) cannot deal with accumulated misfolded proteins completely. Excess ERS can eventually cause pathological reactions, triggering various programmed cell death (autophagy, ferroptosis, apoptosis, pyroptosis). This article provides an overview of the latest research progress in deciphering the interaction between ERS and different programmed cell death. Additionally, the report consolidates insights into the roles of ERS in AKI and highlights the potential avenues for targeting ERS as a treatment direction toward for AKI.

Inflammasome: structure, biological functions, and therapeutic targets

Inflammasomes are a group of protein complex located in cytoplasm and assemble in response to a wide variety of pathogen-associated molecule patterns, damage-associated molecule patterns, and cellular stress. Generally, the activation of inflammasomes will lead to maturation of proinflammatory cytokines and pyroptotic cell death, both associated with inflammatory cascade amplification. A sensor protein, an adaptor, and a procaspase protein interact through their functional domains and compose one subunit of inflammasome complex. Under physiological conditions, inflammasome functions against pathogen infection and endogenous dangers including mtROS, mtDNA, and so on, while dysregulation of its activation can lead to unwanted results. In recent years, advances have been made to clarify the mechanisms of inflammasome activation, the structural details of them and their functions (negative/positive) in multiple disease models in both animal models and human. The wide range of the stimuli makes the function of inflammasome diverse and complex. Here, we review the structure, biological functions, and therapeutic targets of inflammasomes, while highlight NLRP3, NLRC4, and AIM2 inflammasomes, which are the most well studied. In conclusion, this review focuses on the activation process, biological functions, and structure of the most well-studied inflammasomes, summarizing and predicting approaches for disease treatment and prevention with inflammasome as a target. We aim to provide fresh insight into new solutions to the challenges in this field.

Iron Metabolism, Redox Balance and Neurological Diseases

Iron is essential for life, and the dysregulation of iron homeostasis can lead to severe pathological changes in the neurological system [...].

Nlrp3 Deficiency Alleviates Lipopolysaccharide-Induced Acute Kidney Injury via Suppressing Renal Inflammation and Ferroptosis in Mice

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is a vital component of many inflammatory responses. Here, we intended to investigate the involvement of NLRP3 in lipopolysaccharide (LPS)-induced sepsis-associated acute kidney injury (S-AKI) and explore its mechanisms. For the first time, we validated elevated NLRP3 expression in the renal tissues of S-AKI patients by immunohistochemistry analysis. Through LPS injection in both wild-type and Nlrp3-/- mice, a S-AKI model was developed. It was found that LPS-induced kidney injury, including an abnormal morphology in a histological examination, abnormal renal function in a laboratory examination, and an increase in the expression of AKI biomarkers, was dramatically reversed in Nlrp3-deficient mice. Nlrp3 deletion alleviated renal inflammation, as evidenced by the suppression of the expression of pro-inflammatory cytokines and chemokines. A combinative analysis of RNA sequencing and the FerrDb V2 database showed that Nlrp3 knockout regulated multiple metabolism pathways and ferroptosis in LPS-induced S-AKI. Further qPCR coupled with Prussian blue staining demonstrated that Nlrp3 knockout inhibited murine renal ferroptosis, indicating a novel mechanism involving S-AKI pathogenesis by NLRP3. Altogether, the aforementioned findings suggest that Nlrp3 deficiency alleviates LPS-induced S-AKI by reducing renal inflammation and ferroptosis. Our data highlight that NLRP3 is a potential therapeutic target for S-AKI.