NLR family pyrin domain containing 3 (NLRP3) and caspase 1 (CASP1) modulation by intracellular Cl- concentration

Inhibition of caspase-1 by ginsenoside Rg1 ameliorates d-gal-induced renal aging and injury through suppression of oxidative stress and inflammation

BACKGROUND

The disruption of renal cell homeostasis caused by aging has attracted considerable attention. A traditional Chinese medicine, ginseng, is a potential drug for treating aging-related diseases. The study investigates the effect and mechanism of ginsenoside Rg1, an active component of ginseng, on renal aging and injury.

MATERIALS AND METHODS

The potential targets of ginsenoside Rg1 in relieving renal aging and injury were predicted using network pharmacology. d-Galactose (d-gal) was used to induce aging and mice were randomly divided into six groups: a wild-type control group, a wild-type d-gal group, and a wild-type d-gal with Rg1 group (20 mg/kg/d), a caspase-1-/- control group, a caspase-1-/- d-gal group, and a caspase-1-/- d-gal with Rg1 group (n = 5). The duration of the study was 42 days. The effect of Rg1 was assessed by hematoxylin and eosin and Masson staining, quantitative reverse transcription PCR, enzyme-linked immunosorbent assay, and Western blotting.

RESULTS

Network pharmacology revealed that caspase-1 was one of the crucial targets. In vivo experiments, ginsenoside Rg1 treatment resulted in lowered levels of β-Gal, p53, p21, blood urea nitrogen, serum creatinine, malondialdehyde, reactive oxygen species, tumor necrosis factor-α and renal fibrosis, along with a reduction of caspase-1, interleukin-1 and interleukin-18 in mice induced by d-gal. Additionally, knockout of caspase-1 can improve the above indicators and caspase-1-/- mice treated with Rg1 showed better protective effects in alleviating renal senescence, ameliorating kidney injury, and mitigating inflammation and oxidative stress.

CONCLUSION

The findings in this study provide experimental support for the clinical application of ginsenoside Rg1 in kidney aging. The underlying mechanisms require further experimental validation.

Vitamin D and Retinoic Acid Require Protein Kinase C Activity and Reactive Oxygen Species as Opposing Signals Regulating PEIG-1/GPRC5A Expression in Caco-2 and T84 Colon Carcinoma Cells

PEIG-1/GPRC5A (phorbol ester induced gene-1/G-protein Coupled Receptor Class C Group 5 Member A) was the first identified member of the orphan G protein-coupled receptor family GPRC5. Deregulation of its expression is associated with the development and progression of various types of tumours, particularly colon carcinoma. In this work, we study the effects of vitamin D (VD, cholecalciferol) and retinoic acid (RA) on GPRC5A mRNA expression in the colorectal cancer cell lines Caco-2 and T84. Both VD (10 µM) and all-trans retinoic acid (ATRA, atRA, RA) (10 µM) increased GPRC5A mRNA levels. Protein kinase C (PKC) inhibition with Gö6983 (10 µM) completely abolished the effects of VD and RA on GPRC5A expression. In parallel, VD and RA increased cytosolic and mitochondrial ROS levels (cROS and mtROS). However, the antioxidants NAC (10 mM) and MitoTEMPO (10 µM) raised GPRC5A gene expression levels in the presence of VD or RA, suggesting that elevated ROS may inhibit GPRC5A expression. In conclusion, both VD and RA stimulate GPRC5A expression. The mechanisms involve a common and essential PKC signalling pathway, as Gö6983 inhibited both VD- and RA-induced signalling.

How Effectively Can Oxidative Stress and Inflammation Be Reversed When CFTR Function Is Pharmacologically Improved?

A critical challenge in the age of advanced modulator therapies is to understand and determine how effectively chronic oxidative stress and oxidative stress-induced inflammation can be reversed and physiological balance restored when CFTR function is pharmacologically improved. The triple therapy with elexacaftor-tezacaftor-ivacaftor (ETI) suggests that CFTR activity in individuals with at least one F508del mutation can be partially restored to about 50% of normal levels. Although incomplete, the partial recovery of CFTR function has been shown to drastically lower sputum pathogen content, enhance microbiome diversity, and lower inflammation markers within the first year of treatment in adolescents and adults with cystic fibrosis. However, despite these advancements, residual airway infection, oxidative stress and inflammation persist, with levels similar to other chronic lung conditions, like non-CF bronchiectasis. This persistence highlights the necessity for innovative antioxidant and anti-inflammatory treatments, in particular for individuals with advanced lung disease. To address this issue, emerging multi-omics technologies offer valuable tools to investigate the impact of modulator therapies on various molecular pathways. By analyzing changes in gene expression, epigenetic modifications, protein profiles and metabolic processes in airway-derived samples, it could be possible to uncover the mechanisms driving persistent oxidative stress and inflammation. These insights could pave the way for identifying new therapeutic targets to fully restore airway health and overall physiological balance.

Exploring the correlation between innate immune activation of inflammasome and regulation of pyroptosis after intracerebral hemorrhage: From mechanism to treatment

Stroke has emerged as the primary cause of disability and death globally in recent years. Intracerebral hemorrhage (ICH), a particularly severe kind of stroke, is occurring in an increasing number of people. The two main clinical treatments for ICH now in use are conservative pharmaceutical therapy and surgical intervention, both of which have risks and drawbacks. Consequently, it is crucial to look into the pathophysiology of ICH and consider cutting-edge therapeutic approaches. Recent research has revealed that pyroptosis is a newly identified type of cell death distinguished by the break of the cell membrane and the discharge of pro-inflammatory substances through different routes. Following ICH, glial cells experience pyroptosis, which worsens neuroinflammation. Hence, the onset and progression of ICH are strongly linked to pyroptosis, which is facilitated by different inflammasomes. It is essential to conduct a comprehensive investigation of ICH damage processes and uncover new targets for treatment. The impact and function of pyroptosis in ICH, as well as the activation and regulation of inflammasomes and their mediated pyroptosis pathways will be fully discussed in this review.

Schisandrin protects against ulcerative colitis by inhibiting the SGK1/NLRP3 signaling pathway and reshaping gut microbiota in mice

BACKGROUND

According to the Chinese Pharmacopoeia, the fruit of Schisandra chinensis (Turcz.) Baill. (SC) is an important traditional Chinese medicine that can be used to treat diarrhea. Despite the increasing research on the anti-inflammatory and anti-oxidant aspects of SC, the studies on the anti-ulcerative colitis of Schisandrin (SCH), the main constituent of SC, are relatively few.

METHODS

The mice used in the study were randomly distributed into 6 groups: control, model, 5-ASA, and SCH (20, 40, 80 mg/kg/d). The mice in the model group were administered 3% (w/v) dextran sulfate sodium (DSS) through drinking water for 7 days, and the various parameters of disease activity index (DAI) such as body weight loss, stool consistency, and gross blood were measured. ELISA was used to detect inflammatory factors, and bioinformatics combined with transcriptome analysis was done to screen and verify relevant targets. 16S rDNA high-throughput sequencing was used to analyze the composition of the gut microbiota(GM), while mass spectrometry was done to analyze the changes in the content of bile acids (BAs) in the intestine.

RESULTS

Mice treated with SCH experienced significant weight gain, effectively alleviating the severity of colitis, and decreasing the levels of inflammatory factors such as TNF-α, IL-1β, IL-18, IL-6, and other related proteins (NLRP3, Caspase-1, SGK1) in UC mice. Furthermore, the analysis of GM and BAs in mice revealed that SCH increased the relative abundance of Lactobacilli spp, reduced the relative abundance of Bacteroides, and promoted the conversion of primary BAs to secondary BAs. These effects contributed to a significant improvement in the DSS-induced GM imbalance and the maintenance of intestinal homeostasis.

CONCLUSION

It seems that there is a close relationship between the SCH mechanism and the regulation of SGK1/NLRP3 pathway and the restoration of GM balance. Therefore, it can be concluded that SCH could be a potential drug for the treatment of UC.

Inflammasome activation in traumatic brain injury and Alzheimer's disease

Traumatic brain injury (TBI) and Alzheimer's disease (AD) represent 2 of the largest sources of death and disability in the United States. Recent studies have identified TBI as a potential risk factor for AD development, and numerous reports have shown that TBI is linked with AD associated protein expression during the acute phase of injury, suggesting an interplay between the 2 pathologies. The inflammasome is a multi-protein complex that plays a role in both TBI and AD pathologies, and is characterized by inflammatory cytokine release and pyroptotic cell death. Products of inflammasome signaling pathways activate microglia and astrocytes, which attempt to resolve pathological inflammation caused by inflammatory cytokine release and phagocytosis of cellular debris. Although the initial phase of the inflammatory response in the nervous system is beneficial, recent evidence has emerged that the heightened inflammatory response after trauma is self-perpetuating and results in additional damage in the central nervous system. Inflammasome-induced cytokines and inflammasome signaling proteins released from activated microglia interact with AD associated proteins and exacerbate AD pathological progression and cellular damage. Additionally, multiple genetic mutations associated with AD development alter microglia inflammatory activity, increasing and perpetuating inflammatory cell damage. In this review, we discuss the pathologies of TBI and AD and how they are impacted by and potentially interact through inflammasome activity and signaling proteins. We discuss current clinical trials that target the inflammasome to reduce heightened inflammation associated with these disorders.

Serum/glucocorticoid-inducible kinase 1 deficiency induces NLRP3 inflammasome activation and autoinflammation of macrophages in a murine endolymphatic hydrops model

Ménière's disease, a multifactorial disorder of the inner ear, is characterized by severe vertigo episodes and hearing loss. Although the role of immune responses in Ménière's disease has been proposed, the precise mechanisms remain undefined. Here, we show that downregulation of serum/glucocorticoid-inducible kinase 1 is associated with activation of NLRP3 inflammasome in vestibular-resident macrophage-like cells from Ménière's disease patients. Serum/glucocorticoid-inducible kinase 1 depletion markedly enhances IL-1β production which leads to the damage of inner ear hair cells and vestibular nerve. Mechanistically, serum/glucocorticoid-inducible kinase 1 binds to the PYD domain of NLRP3 and phosphorylates it at Serine 5, thereby interfering inflammasome assembly. Sgk^-/- mice show aggravated audiovestibular symptoms and enhanced inflammasome activation in lipopolysaccharide-induced endolymphatic hydrops model, which is ameliorated by blocking NLRP3. Pharmacological inhibition of serum/glucocorticoid-inducible kinase 1 increases the disease severity in vivo. Our studies demonstrate that serum/glucocorticoid-inducible kinase 1 functions as a physiologic inhibitor of NLRP3 inflammasome activation and maintains inner ear immune homeostasis, reciprocally participating in models of Ménière's disease pathogenesis.

Activation of Swell1 in microglia suppresses neuroinflammation and reduces brain damage in ischemic stroke

Cl^- movement and Cl^--sensitive signal pathways contributes to the survival and switch of inflammatory phenotype of microglia and are believed to play a key role in the inflammatory brain injury after ischemic stroke. Here, we demonstrated an important role of Cl^- transmembrane transporter Swell1, in the survival and M2-like polarization of microglia in ischemic stroke. Knockdown or overexpression of Swell1 in cultured microglia inhibited or increased hypotonic-activated Cl^- currents, respectively, and these changes were completely blocked by the volume-regulated anion channels (VRACs) inhibitor DCPIB. Swell1 conditional knock-in mice promoted microglia survival in ischemic brain region and resulted in significant reductions in neural cell death, infarction volume and neurological deficits following transient middle cerebral artery occlusion (tMCAO). Using gene manipulating technique and pharmacological inhibitors, we further revealed that Swell1 opening led to SGK1 (a Cl^--sensitive kinase)-mediated activation of FOXO3a/CREB as well as WNK1 (another Cl^--sensitive kinase)-mediated SPAK/OSR1-CCCs activation, which promoted microglia survival and M2-like polarization, thereby attenuating neuroinflammation and ischemic brain injury. Taken together, our results demonstrated that Swell1 is an essential component of microglia VRACs and its activation protects against ischemic brain injury through promoting microglia survival and M2-like polarization.

Inhibition of macrophages inflammasome activation via autophagic degradation of HMGB1 by EGCG ameliorates HBV-induced liver injury and fibrosis

Background

Liver fibrosis is a reversible wound-healing response that can lead to end-stage liver diseases without effective treatment, in which HBV infection is a major cause. However, the underlying mechanisms for the development of HBV-induced fibrosis remains elusive, and efficacious therapies for this disease are still lacking. In present investigation, we investigated the effect and mechanism of green tea polyphenol epigallocatechin-3-gallate (EGCG) on HBV-induced liver injury and fibrosis.

Methods

The effect of EGCG on liver fibrosis was examined in a recombinant cccDNA (rcccDNA) chronic HBV mouse model by immunohistochemical staining, Sirius red and Masson's trichrome staining. The functional relevance between high mobility group box 1 (HMGB1) and inflammasome activation and the role of EGCG in it were analyzed by Western blotting. The effect of EGCG on autophagic flux was determined by Western blotting and flow cytometric analysis.

Results

EGCG treatment efficiently was found to alleviate HBV-induced liver injury and fibrosis in a recombinant cccDNA (rcccDNA) chronic HBV mouse model, a proven suitable research platform for HBV-induced fibrosis. Mechanistically, EGCG was revealed to repress the activation of macrophage NLRP3 inflammasome, a critical trigger of HBV-induced liver fibrosis. Further study revealed that EGCG suppressed macrophage inflammasome through downregulating the level of extracellular HMGB1. Furthermore, our data demonstrated that EGCG treatment downregulated the levels of extracellular HMGB1 through activating autophagic degradation of cytoplasmic HMGB1 in hepatocytes. Accordingly, autophagy blockade was revealed to significantly reverse EGCG-mediated inhibition on extracellular HMGB1-activated macrophage inflammasome and thus suppress the therapeutic effect of EGCG on HBV-induced liver injury and fibrosis.

Conclusion

EGCG ameliorates HBV-induced liver injury and fibrosis via autophagic degradation of cytoplasmic HMGB1 and the subsequent suppression of macrophage inflammasome activation. These data provided a new pathogenic mechanism for HBV-induced liver fibrosis involving the extracellular HMGB1-mediated macrophage inflammasome activation, and also suggested EGCG administration as a promising therapeutic strategy for this disease.

WNK1 is a chloride-stimulated scaffold that regulates mTORC2 activity and ion transport

Mammalian (or mechanistic) target of rapamycin complex 2 (mTORC2) is a kinase complex that targets predominantly Akt family proteins, SGK1 and protein kinase C (PKC), and has well-characterized roles in mediating hormone and growth factor effects on a wide array of cellular processes. Recent evidence suggests that mTORC2 is also directly stimulated in renal tubule cells by increased extracellular K+ concentration, leading to activation of the Na+ channel, ENaC, and increasing the electrical driving force for K+ secretion. We identify here a signaling mechanism for this local effect of K+. We show that an increase in extracellular [K+] leads to a rise in intracellular chloride (Cl-), which stimulates a previously unknown scaffolding activity of the protein 'with no lysine-1' (WNK1) kinase. WNK1 interacts selectively with SGK1 and recruits it to mTORC2, resulting in enhanced SGK1 phosphorylation and SGK1-dependent activation of ENaC. This scaffolding effect of WNK1 is independent of its own kinase activity and does not cause a generalized stimulation of mTORC2 kinase activity. These findings establish a novel WNK1-dependent regulatory mechanism that harnesses mTORC2 kinase activity selectively toward SGK1 to control epithelial ion transport and electrolyte homeostasis.

The role of Nod-like receptor protein 3 inflammasome activated by ion channels in multiple diseases

The inflammasome is a multimeric protein complex located in the cytoplasm that is activated by many factors and subsequently promotes the release of proinflammatory factors such as interleukin (IL)-1β and IL-18, resulting in a series of inflammatory responses that ultimately lead to the occurrence of various diseases. The Nod-like receptor protein 3 (NLRP3) inflammasome is the most characteristic type and the most widely studied among many inflammasomes. Activation of the NLRP3 inflammasome is closely related to the occurrence of many diseases, such as Alzheimer's disease. At present, a large number of studies have focused on the mechanisms underlying the activation of the NLRP3 inflammasome. Plenty of articles have reported the activation of the NLRP3 inflammasome by various ions, such as K+ and Na+ reflux and Ca2+ influx. However, few articles have reviewed the effects of various ion channels on the activation of the NLRP3 inflammasome and the relationship between the diseases caused by these proteins. This article mainly summarizes the relationship between intracellular and extracellular ion activities and ion channels and the activation of the NLRP3 inflammasome. We also provide a general summary of the diseases of each system caused by NLRP3 activation. We hope that more research will provide options for the treatment of diseases driven by the NLRP3 inflammasome.

Histamine H4 Receptor Agonism Induces Antitumor Effects in Human T-Cell Lymphoma

The discovery of the human histamine H4 receptor (H4R) has contributed to our understanding of the role of histamine in numerous physiological and pathological conditions, including tumor development and progression. The lymph nodes of patients with malignant lymphomas have shown to contain high levels of histamine, however, less is known regarding the expression and function of the H4R in T-cell lymphoma (TCL). In this work we demonstrate the expression of H4R isoforms (mRNA and protein) in three human aggressive TCL (OCI-Ly12, Karpas 299, and HuT78). Histamine and specific H4R agonists (VUF8430 and JNJ28610244) significantly reduced cell viability in a dose-dependent manner (p < 0.05). The combined treatment with the H4R antagonist (JNJ7777120, 10 µM) reversed the effects of the H4R ligands. Importantly, we screened a drug repurposing library of 433 FDA-approved compounds (1 μM) in combination with histamine (10 μM) in Hut78 cells. Histamine produced a favorable antitumor effect with 18 of these compounds, including the histone deacetylase inhibitor panobinostat. Apoptosis, proliferation, and oxidative stress studies confirmed the antitumoral effects of the combination. We conclude that the H4R is expressed in TCL, and it is involved in histamine-mediated responses.

NLRP3 inflammasome promoted the malignant progression of prostate cancer via the activation of caspase-1

It is widely accepted that inflammation is an important risk for the development of prostate cancer (PCa). The objective of this study was designed to investigate the potential molecular mechanism of NLR family, pyrin domain-containing protein 3 (NLRP3) inflammasome in the malignant progression of PCa. The expression level of NLRP3 was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and fluorescence in situ hybridization. The effects of NLRP3 in the development of PCa by applying gain- and loss-of-function assays in LNCaP and PC3 cell lines were detected by CCK-8, TUNEL, and Transwell migration assays. The underlying mechanism of NLRP3 and caspase-1 in PCa was examined by the rescue experiments, western blotting, and qRT-PCR assays. In addition, the promoting effect of NLRP3 inflammasome was performed with an animal subcutaneous tumorigenesis experiment in vivo. The upregulation of NLRP3 was confirmed in PCa tissues and cell lines. Functionally, using CCK-8, TUNEL, and Transwell migration assays, these results showed that activation of NLRP3/caspase-1 inflammasome by LPS + ATP could enhance the ability of proliferation and migration; and decrease the apoptosis of LNCaP and PC3 cell lines. Western blotting assay showed that the activation of caspase-1 would increase after the stimulation of NLRP3 inflammasome by LPS + ATP. Moreover, the overexpression of NLRP3 promoted, while the knockdown of NLRP3 inhibited the malignant progression in PCa cell lines by positively regulating caspase-1. In addition, the rescue experiments revealed the association among NLRP3 and caspase-1, which showed that the overexpression vectors/inhibitors of caspase-1 could reverse the effect of knockdown/overexpression of NLRP3 in PCa cell lines in vitro. Finally, In in vivo experiment, the suppression of NLRP3 knockdown impaired tumor growth of PCa. Collectively, these results indicated that NLRP3 inflammasome played a vital role in promoting the malignant progression of PCa via the activation of caspase-1. Together, our findings provided insight into the mechanisms of NLRP3/caspase-1 inflammasome and revealed an alternative and potential target for the clinical diagnosis and treatment of PCa.