Research progress of NLRP3 inflammasome and its inhibitors with aging diseases

Preventing NLRP3 inflammasome activation: Therapeutic atrategy and challenges in atopic dermatitis

Atopic dermatitis (AD) is a prevalent inflammatory skin disorder characterized by its chronic, persistent, and recurrent nature. The pathophysiology of this condition is complex, involving various factors including cell-mediated immune responses, compromised skin barrier function, and alterations in hypersensitivity reactions. These components synergistically contribute to the perpetuation of the bothersome "itch-scratch-itch" cycle. Recent research has highlighted the significant role of the NLRP3 inflammasome in the development of AD and other inflammatory conditions. Current research indicates that the NLRP3 inflammasome plays a pivotal role in both the acute and chronic phases of AD by modulating the Th2/Th1 immune deviation. Moreover, the pharmacological suppression of NLRP3 has shown promising results in mitigating the pathological aspects of AD. This review outlines potential drug development strategies that target the NLRP3 inflammasome as a therapeutic approach for AD and the challenges faced in this endeavor.

Senoinflammation as the underlying mechanism of aging and its modulation by calorie restriction

Senoinflammation is characterized by an unresolved low-grade inflammatory process that affects multiple organs and systemic functions. This review begins with a brief overview of the fundamental concepts and frameworks of senoinflammation. It is widely involved in the aging of various organs and ultimately leads to progressive systemic degeneration. Senoinflammation underlying age-related inflammation, is causally related to metabolic dysregulation and the formation of senescence-associated secretory phenotype (SASP) during aging and age-related diseases. This review discusses the biochemical evidence and molecular biology data supporting the concept of senoinflammation and its regulatory processes, highlighting the anti-aging and anti-inflammatory effects of calorie restriction (CR). Experimental data from CR studies demonstrated effective suppression of various pro-inflammatory cytokines and chemokines, lipid accumulation, and SASP during aging. In conclusion, senoinflammation represents the basic mechanism that creates a microenvironment conducive to aging and age-related diseases. Furthermore, it serves as a potential therapeutic target for mitigating aging and age-related diseases.

Recent advances in the treatment of gout with NLRP3 inflammasome inhibitors

Gout is an autoinflammatory disorder characterized by the accumulation of monosodium urate crystals in joints and other tissues, representing the predominant type of inflammatory arthritis with a notable prevalence and propensity for severe outcomes. The NLRP3 inflammasome, a member of the pyrin domain-containing NOD-like receptor family, exerts a substantial impact on both innate and adaptive immune responses and serves as a pivotal factor in the pathogenesis of gout. In recent years, there has been significant academic and industrial interest in the development of NLRP3-targeted small molecule inhibitors as a promising therapeutic approach for gout. To assess the advancements in NLRP3 inflammasome inhibitors for gout treatment, this review offers a comprehensive analysis and evaluation of current clinical candidates and other inhibitors targeting NLRP3 inflammasome from a chemical structure standpoint, with the goal of identifying more efficacious options for clinical management of gout.

Discovery of Potent, Specific, and Orally Available NLRP3 Inflammasome Inhibitors Based on Pyridazine Scaffolds for the Treatment of Septic Shock and Peritonitis

The NLRP3 inflammasome is a multiprotein complex that is a component of the innate immune system, involved in the production of pro-inflammatory cytokines. Its abnormal activation is associated with many inflammatory diseases. In this study, we designed and synthesized a series of NLRP3 inflammasome inhibitors based on pyridazine scaffolds. Among them, P33 exhibited significant inhibitory effects against nigericin-induced IL-1β release in THP-1 cells, BMDMs, and PBMCs, with IC50 values of 2.7, 15.3, and 2.9 nM, respectively. Mechanism studies indicated that P33 directly binds to NLRP3 protein (KD = 17.5 nM), inhibiting NLRP3 inflammasome activation and pyroptosis by suppressing ASC oligomerization during NLRP3 assembly. Additionally, P33 displayed excellent pharmacokinetic properties, with an oral bioavailability of 62%. In vivo efficacy studies revealed that P33 significantly ameliorated LPS-induced septic shock and MSU crystal-induced peritonitis in mice. These results indicate that P33 has great potential for further development as a candidate for treating NLRP3 inflammasome-mediated diseases.

Anti-Inflammatory Role of the Klotho Protein and Relevance to Aging

The α-Klotho protein (hereafter Klotho) is an obligate coreceptor for fibroblast growth factor 23 (FGF23). It is produced in the kidneys, brain and other sites. Klotho insufficiency causes hyperphosphatemia and other anomalies. Importantly, it is associated with chronic pathologies (often age-related) that have an inflammatory component. This includes atherosclerosis, diabetes and Alzheimer's disease. Its mode of action in these diseases is not well understood, but it inhibits or regulates multiple major pathways. Klotho has a membrane form and a soluble form (s-Klotho). Cytosolic Klotho is postulated but not well characterized. s-Klotho has endocrine properties that are incompletely elucidated. It binds to the FGF receptor 1c (FGFR1c) that is widely expressed (including endothelial cells). It also attaches to soluble FGF23, and FGF23/Klotho binds to FGFRs. Thus, s-Klotho might be a roaming FGF23 coreceptor, but it has other functions. Notably, Klotho (cell-bound or soluble) counteracts inflammation and appears to mitigate related aging (inflammaging). It inhibits NF-κB and the NLRP3 inflammasome. This inflammasome requires priming by NF-κB and produces active IL-1β, membrane pores and cell death (pyroptosis). In accord, Klotho countered inflammation and cell injury induced by toxins, damage-associated molecular patterns (DAMPs), cytokines, and reactive oxygen species (ROS). s-Klotho also blocks the TGF-β receptor and Wnt ligands, which lessens fibrotic disease. Low Klotho is associated with loss of muscle mass (sarcopenia), as occurs in aging and chronic diseases. s-Klotho counters the inhibitory effects of myostatin and TGF-β on muscle, reduces inflammation, and improves muscle repair following injury. The inhibition of TGF-β and other factors may also be protective in diabetic retinopathy and age-related macular degeneration (AMD). This review examines Klotho functions especially as related to inflammation and potential applications.

Novel Compounds as NLRP3 Inhibitors for Treating Cardiovascular Diseases

Provided herein are novel compounds as NLRP3 inhibitors, pharmaceutical compositions, use of such compounds in treating cardiovascular diseases, and processes for preparing such compounds.

RND3 modulates microglial polarization and alleviates neuroinflammation in Parkinson's disease by suppressing NLRP3 inflammasome activation

Neuroinflammation mediated by microglia plays an important role in the etiology of Parkinson's disease (PD). Rho family GTPase 3 (RND3) exerts anti-inflammatory effects and may act as a potential new inducer of neuroprotective phenotypes in microglia. However, whether RND3 can be used to regulate microglia activation or reduce neuroinflammation in PD remains elusive. The study investigated the microglia modulating effects and potential anti-inflammatory effects of RND3 in vivo and in vitro, using animal models of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD and cell models of BV-2 cells stimulated by LPS plus IFN-γ with or without RND3-overexpression. The results showed that RND3 was highly expressed in the MPTP-induced PD mouse model and BV-2 cells treated with LPS and IFN-γ. In vivo experiments confirmed that RND3 overexpression could modulate microglia phenotype and ameliorate MPTP-induced neuroinflammation through inhibiting activation of the NLRP3 inflammasome in substantia nigra pars compacta (SNpc). In vitro study showed that RND3 overexpression could attenuate the production of pro-inflammatory factors in BV2 cells stimulated by LPS and IFN-γ. Mechanistically, RND3 reduced the activation of the NLRP3 inflammasome upon LPS and IFN-γ stimulation. Taken together, these findings suggest that RND3 modulates microglial polarization and alleviates neuroinflammation in Parkinson's disease by suppressing NLRP3 inflammasome activation.

Renoprotective effect of rosmarinic acid by inhibition of indoxyl sulfate-induced renal interstitial fibrosis via the NLRP3 inflammasome signaling

We previously reported that rosmarinic acid (RA) ameliorated renal fibrosis in a unilateral ureteral obstruction (UUO) murine model of chronic kidney disease. This study aimed to determine whether RA attenuates indoxyl sulfate (IS)-induced renal fibrosis by regulating the activation of the NLRP3 inflammasome/IL-1β/Smad circuit. We discovered the NLRP3 inflammasome was activated in the IS treatment group and downregulated in the RA-treated group in a dose-dependent manner. Additionally, the downstream effectors of the NLRP3 inflammasome, cleaved-caspase-1 and cleaved-IL-1β showed similar trends in different groups. Moreover, RA administration significantly decreased the ROS levels of reactive oxygen species in IS-treated cells. Our data showed that RA treatment significantly inhibited Smad-2/3 phosphorylation. Notably, the effects of RA on NLRP3 inflammasome/IL-1β/Smad and fibrosis signaling were reversed by the siRNA-mediated knockdown of NLRP3 or caspase-1 in NRK-52E cells. In vivo, we demonstrated that expression levels of NLRP3, c-caspase-1, c-IL-1β, collagen I, fibronectin and α-SMA, and TGF- β 1 were downregulated after treatment of UUO mice with RA or RA + MCC950. Our findings suggested RA and MCC950 synergistically inhibited UUO-induced NLRP3 signaling activation, revealing their renoprotective properties and the potential for combinatory treatment of renal fibrosis and chronic kidney inflammation.

Immunological dimensions of neuroinflammation and microglial activation: exploring innovative immunomodulatory approaches to mitigate neuroinflammatory progression

The increasing life expectancy has led to a higher incidence of age-related neurodegenerative conditions. Within this framework, neuroinflammation emerges as a significant contributing factor. It involves the activation of microglia and astrocytes, leading to the release of pro-inflammatory cytokines and chemokines and the infiltration of peripheral leukocytes into the central nervous system (CNS). These instances result in neuronal damage and neurodegeneration through activated nucleotide-binding domain and leucine-rich repeat containing (NLR) family pyrin domain containing protein 3 (NLRP3) and nuclear factor kappa B (NF-kB) pathways and decreased nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Due to limited effectiveness regarding the inhibition of neuroinflammatory targets using conventional drugs, there is challenging growth in the search for innovative therapies for alleviating neuroinflammation in CNS diseases or even before their onset. Our results indicate that interventions focusing on Interleukin-Driven Immunomodulation, Chemokine (CXC) Receptor Signaling and Expression, Cold Exposure, and Fibrin-Targeted strategies significantly promise to mitigate neuroinflammatory processes. These approaches demonstrate potential anti-neuroinflammatory effects, addressing conditions such as Multiple Sclerosis, Experimental autoimmune encephalomyelitis, Parkinson's Disease, and Alzheimer's Disease. While the findings are promising, immunomodulatory therapies often face limitations due to Immune-Related Adverse Events. Therefore, the conduction of randomized clinical trials in this matter is mandatory, and will pave the way for a promising future in the development of new medicines with specific therapeutic targets.