Sirtuin-1 ameliorates cadmium-induced endoplasmic reticulum stress and pyroptosis through XBP-1s deacetylation in human renal tubular epithelial cells

Naringenin mitigates cadmium-induced cell death, oxidative stress, mitochondrial dysfunction, and inflammation in KGN cells by regulating the expression of sirtuin-1

The objective of this study was to examine the potential protective role of naringenin against the harmful effects induced by cadmium in KGN cell line. Cell viability was evaluated by cell counting kit-8 assay. Caspase-3/-9 activities were determined by caspase-3/-9 activity assay kits, respectively. Intracellular reactive oxygen species (ROS) level was detected by ROS-Glo™ H2O2 Assay, antioxidant capacity was determined by a total antioxidant capacity assay kit. Mitochondrial membrane potential (MMP), ATP level, and ATP synthase activity were determined by JC-1, ATP assay kit, and ATP synthase activity assay kit, respectively. The mRNA expression was determined by qRT-PCR. Cadmium reduced cell viability and increased caspase-3/-9 activities in a concentration-dependent manner. Naringenin improved cell viability and reduced caspase-3/-9 activities in cadmium-stimulated KGN cells in a concentration-dependent manner. Cadmium diminished the antioxidant capacity, increased ROS production, and induced mitochondrial dysfunction in KGN cells. These effects were ameliorated by naringenin treatment in a concentration-dependent manner. Furthermore, naringenin reduced the levels of pro-inflammatory cytokines in KGN cells exposed to cadmium. SIRT1 knockdown downregulated its expression in KGN cells and compromised the protective effects of naringenin on cell viability and caspase-3/-9 activities in cadmium-stimulated KGN cells. Naringenin prevented the reduction of MMP, ATP levels, and ATP synthase activity in cadmium-stimulated KGN cells in a concentration-dependent manner. However, these protective effects were significantly reversed by SIRT1 knockdown. In conclusion, this study suggests that naringenin protects against cadmium-induced damage by regulating oxidative stress, mitochondrial function, and inflammation in KGN cells, with SIRT1 playing a potential mediating role.

SIRT1 alleviates Cd nephrotoxicity through NF-κB/p65 deacetylation-mediated pyroptosis in rat renal tubular epithelial cells

Cadmium (Cd) is a widely distributed environmental pollutant, primarily causing nephrotoxicity through renal proximal tubular cell impairment. Pyroptosis is an inflammation-related nucleotide-binding oligomerization segment-like receptor family 3 (NLRP3)-dependent pathway for programmed cell death. We previously reported that inappropriate inflammation caused by Cd is a major contributor to kidney injury. Therefore, research on Cd-induced inflammatory response and pyroptosis may clarify the mechanisms underlying Cd-induced nephrotoxicity. In this study, we observed that Cd-induced nephrotoxicity is associated with NLRP3 inflammasome activation, leading to an increase in proinflammatory cytokine expression and secretion, as well as pyroptosis-related gene upregulation, both in primary rat proximal tubular (rPT) cells and kidney tissue from Cd-treated rats. In vitro, these effects were significantly abrogated through siRNA-based Nlrp3 silencing; thus, Cd may trigger pyroptosis through an NLRP3 inflammasome-dependent pathway. Moreover, Cd exposure considerably elevated reactive oxygen species (ROS) content. N-acetyl-l-cysteine, an ROS scavenger, mitigated Cd-induced NLRP3 inflammasome activation and subsequent pyroptosis. Mechanistically, Cd hindered the expression and deacetylase activity of SIRT1, eventually leading to a decline in SIRT1-p65 interactions, followed by an elevation in acetylated p65 levels. The administration of resveratrol (a SIRT1 agonist) or overexpression of Sirt1 counteracted Cd-induced RELA/p65/NLRP3 pathway activation considerably, leading to pyroptosis. This is the first study to reveal significant contributions of SIRT1-triggered p65 deacetylation to pyroptosis and its protective effects against Cd-induced chronic kidney injury. Our results may aid in developing potential therapeutic strategies for preventing Cd-induced pyroptosis through SIRT1-mediated p65 deacetylation.

Cadmium toxicity and autophagy: a review

Cadmium (Cd) is an important environmental pollutant that poses a threat to human health and represents a critical component of air pollutants, food sources, and cigarette smoke. Cd is a known carcinogen and has toxic effects on the environment and various organs in humans. Heavy metals within an organism are difficult to biodegrade, and those that enter the respiratory tract are difficult to remove. Autophagy is a key mechanism for counteracting extracellular (microorganisms and foreign bodies) or intracellular (damaged organelles and proteins that cannot be degraded by the proteasome) stress and represents a self-protective mechanism for eukaryotes against heavy metal toxicity. Autophagy maintains cellular homeostasis by isolating and gathering information about foreign chemicals associated with other molecular events. However, autophagy may trigger cell death under certain pathological conditions, including cancer. Autophagy dysfunction is one of the main mechanisms underlying Cd-induced cytotoxicity. In this review, the toxic effects of Cd-induced autophagy on different human organ systems were evaluated, with a focus on hepatotoxicity, nephrotoxicity, respiratory toxicity, and neurotoxicity. This review also highlighted the classical molecular pathways of Cd-induced autophagy, including the ROS-dependent signaling pathways, endoplasmic reticulum (ER) stress pathway, Mammalian target of rapamycin (mTOR) pathway, Beclin-1 and Bcl-2 family, and recently identified molecules associated with Cd. Moreover, research directions for Cd toxicity regarding autophagic function were proposed. This review presents the latest theories to comprehensively reveal autophagy behavior in response to Cd toxicity and proposes novel potential autophagy-targeted prevention and treatment strategies for Cd toxicity and Cd-associated diseases in humans.

Up-regulation of HSP90α in HDM-induced asthma causes pyroptosis of airway epithelial cells by activating the cGAS-STING-ER stress pathway

Heat Shock protein 90 α (HSP90α), an main subtype of chaperone protein HSP90, involves important biological functions such as DNA damage repair, protein modification, innate immunity. However, the potential role of HSP90α in asthma occurrence and development is still unclear. This study aimed to elucidate the underlying mechanism of HSP90α in asthma by focusing on the cGAS-STING-Endoplasmic Reticulum stress pathway in inflammatory airway epithelial cell death (i.e., pyroptosis; inflammatory cell death). To accomplish that, we modeled allergen exposure in C57/6BL mice and bronchial epithelial cells with house dust mite. Protein technologies and immunofluorescence utilized to study the expression of HSP90α, activation of cGAS-STING pathway and pyroptosis. The effect of inhibitors on HDM-exposed mice detected by histological techniques and examination of bronchoalveolar lavage fluid. Results showed that HSP90α promotes asthma inflammation via pyroptosis and activation of the cGAS-STING-ER stress pathway. Treatment with the HSP90 inhibitor tanespimycin (17-AAG) significantly relieved airway inflammation and abrogated the effect of HSP90α on pyroptosis and cGAS-STING-ER stress in vitro and in vivo models of HDM. Further data indicated that up-regulation of HSP90α stabilized STING through interaction, which increased localization of STING on the ER. Activation of STING triggered ER stress and leaded to pyroptosis-related airway inflammation. The finding showed the potential role of pyroptosis caused by dysregulation of HSP90α on airway epithelial cells in allergic inflammation, suggested that targeting HSP90α in airway epithelial cells might prove to be a potential additional treatment strategy for asthma.

Sirtuin dysregulation in Parkinson's disease: Implications of acetylation and deacetylation processes

Parkinson's disease (PD) is a progressive neurodegenerative condition that primarily affects motor function and is caused by a gradual decline of dopaminergic neurons in the brain's substantia pars compacta (Snpc) region. Multiple molecular pathways are involved in the pathogenesis, which results in impaired cellular functions and neuronal degeneration. However, the role of sirtuins, a type of NAD+-dependent deacetylase, in the pathogenesis of Parkinson's disease has recently been investigated. Sirtuins are essential for preserving cellular homeostasis because they control a number of biological processes, such as metabolism, apoptosis, and DNA repair. This review shed lights on the dysregulation of sirtuin activity in PD, highlighting the role that acetylation and deacetylation processes play in the development of the disease. Key regulators of protein acetylation, sirtuins have been found to be involved in the aberrant acetylation of vital substrates linked to PD pathology when their balance is out of balance. The hallmark characteristics of PD such as neuroinflammation, oxidative stress, and mitochondrial dysfunction have all been linked to the dysregulation of sirtuin expression and activity. Furthermore, we have also explored how the modulators of sirtuins can be a promising therapeutic intervention in the treatment of PD.

Genetic and pharmacological targeting of XBP1 alleviates hepatic ischemia reperfusion injury by enhancing FoxO1-dependent mitophagy

Hepatic ischemia reperfusion (I/R) injury is a common clinical complication. X-box binding protein 1 (XBP1), as a critical regulator of the endoplasmic reticulum stress, has been implicated in a variety of diseases. In this study, we aimed to investigate the effects and the underlying mechanism of XBP1 in the progression of hepatic I/R injury. Hepatocyte-specific XBP1 knockout mice, multiple viral delivery systems and specific pharmacological inhibitors were applied in vivo in a partial hepatic I/R injury mouse model and in vitro in a cell model of hypoxia-reoxygenation (H/R) injury. Mitophagy and autophagic flux were evaluated and fluorescence resonance energy transfer (FRET) as well as immunoprecipitation were performed. The results demonstrated that reperfusion for 6 h represented a critical timepoint in hepatic I/R injury and resulted in significant intracellular mitochondrial dysfunction; led to the breakdown of hepatocytes accompanied by the highest expression levels of XBP1. Hepatocyte-specific XBP1 knockout alleviated hepatic I/R injury via enhanced mitophagy, as demonstrated by the reduction in hepatocellular damage/necrosis and increased expression of mitophagy markers. Mechanistically, XBP1 interacted with FoxO1 directly and catalyzed the ubiquitination of FoxO1 for proteasomal degradation. Targeting XBP1 by genetic or pharmacological techniques potentiated the protein levels of FoxO1, further promoting the activity of the PINK1/Parkin signaling pathway, thus augmenting mitophagy and exerting hepatoprotective effects upon I/R injury. In conclusion, the inhibition of XBP1 potentiated FoxO1-mediated mitophagy in hepatic I/R injury. Specific genetic and pharmacological treatment targeting XBP1 in the perioperative 6 h prior to reperfusion exerted beneficial effects, thus providing a novel therapeutic approach.

Role of SIRT1 in Potentially Toxic Trace Elements (Lead, Fluoride, Aluminum and Cadmium) Associated Neurodevelopmental Toxicity

The formation of the central nervous system is a meticulously planned and intricate process. Any modification to this process has the potential to disrupt the structure and operation of the brain, which could result in deficiencies in neurological growth. When neurotoxic substances are present during the early stages of development, they can be exceptionally dangerous. Prenatally, the immature brain is extremely vulnerable and is therefore at high risk in pregnant women associated with occupational exposures. Lead, fluoride, aluminum, and cadmium are examples of possibly toxic trace elements that have been identified as an environmental concern in the aetiology of a number of neurological and neurodegenerative illnesses. SIRT1, a member of the sirtuin family has received most attention for its potential neuroprotective properties. SIRT1 is an intriguing therapeutic target since it demonstrates important functions to increase neurogenesis and cellular lifespan by modulating multiple pathways. It promotes axonal extension, neurite growth, and dendritic branching during the development of neurons. Additionally, it contributes to neurogenesis, synaptic plasticity, memory development, and neuroprotection. This review summarizes the possible role of SIRT1 signalling pathway in potentially toxic trace elements -induced neurodevelopmental toxicity, highlighting some molecular pathways such as mitochondrial biogenesis, CREB/BDNF and PGC-1α/NRF1/TFAM.

Cadmium exposure induces pyroptosis of TM4 cells through oxidative stress damage and inflammasome activation

Cadmium (Cd) is a harmful metal that seriously affects the male reproductive system, but the mechanism of how Cd exposure damages Sertoli cells is not fully understood. This study used TM4 cells to explore the mechanism of Cd damage to Sertoli cells. We found that Cd was concentration- and time-dependent on TM4 cell viability. Cd exposure increased intracellular reactive oxygen species (ROS) levels, lactate dehydrogenase (LDH), and Interleukin-1β (IL-1β) release in TM4 cells, decreased mitochondrial function, and increased pyroptosis. N-acetylcysteine (NAC), MCC950 and BAY 11-7082 (BAY) alleviate the release of IL-1β and LDH induced by Cd. NAC reduced Cd induced increases in ROS, NLRP3, Caspase-1, Heme oxygenase-1(HO-1), superoxide dismutase (SOD2), and increased mitochondrial function. The activation of GSDMD is the main causes of pyroptosis, and NAC significantly inhibit its activation and formation. Our results suggest that Cd exposure induces a toxic mechanism of GSDMD-mediated pyroptosis in TM4 cells by increasing ROS levels and activating the inflammasome.

Modulating SIRT1, Nrf2, and NF-κB signaling pathways by bergenin ameliorates the cadmium-induced nephrotoxicity in rats

In light of the current industrial evolution, exposure to cadmium has become a significant public health concern. Cadmium accumulates in the renal tubular cells and causes nephrotoxicity largely through disruption of the redox homeostasis, induction of inflammation, and suppression of the histone deacetylase SIRT1 expression. The current work aimed at exploring the protective capability of bergenin, a naturally-occurring methyl gallic acid derivative, against the cadmium-evoked nephrotoxicity. Male Wistar rats were treated either with cadmium alone or with cadmium and bergenin for a 7-day experimental period followed by collection of kidney and blood specimens that were subjected to biochemical, molecular, and histological investigations. The results revealed the ability of bergenin to improve the renal functions in the cadmium-intoxicated rats as evidenced by increased glomerular filtration rate, and decreased serum creatinine and blood urea nitrogen. Equally important, bergenin reduced the renal tissue injury and enhanced its redox homeostasis as indicated by decreased protein expression of the kidney injury marker KIM-1, reduced lipid peroxidation, and improved antioxidant potential and histopathological picture of the renal tissues. Mechanistically, bergenin reduced the renal tissue cadmium content, markedly up-regulated protein expression of SIRT1 that regulates inflammation and the redox status of the renal tissues. Additionally, it improved the expression of the major antioxidant transcription factor Nrf2 and its responsive gene products heoxygenase-1 and NAD(P)H quinone dehydrogenase 1 in the cadmium-intoxicated rats. In the same context, bergenin down-regulated the acetylation and the nuclear translocation of the inflammatory transcription factor NF-κB and reduced levels of its responsive gene products TNF-α and IL-1β, as well as the activity of the inflammatory cell infiltration biomarker myeloperoxidase. Collectively, the current study underscores the ameliorating activity of bergenin against the cadmium-evoked nephrotoxicity and highlights modulation of SIRT1, Nrf2, and NF-κB signaling as potential underlining molecular mechanisms.

SIRT1 regulates endoplasmic reticulum stress-related organ damage

Endoplasmic reticulum (ER) stress plays a key role in the pathogenesis of several organ damages. Studies show that excessive ER stress (ERS) can destroy cellular homeostasis, causing cell damage and physiological dysfunction in various organs. In recent years, Sirtuin1 (SIRT1) has become a research hotspot on ERS. Increasing evidence suggests that SIRT1 plays a positive role in various ERS-induced organ damage via multiple mechanisms, including inhibiting cellular apoptosis and promoting autophagy. SIRT1 can also alleviate liver, heart, lung, kidney, and intestinal damage by inhibiting ERS. We discuss the possible mechanism of SIRT1, explore potential therapeutic targets of diseases, and provide a theoretical basis for treating ERS-related diseases.

N-methyl-d-aspartate receptor 1 activation mediates cadmium-induced epithelial-mesenchymal transition in proximal tubular cells

Cadmium (Cd) is a commonly found environmental pollutant and is known to damage multiple organs with kidneys being the most common one. N-methyl-d-aspartate receptor 1 (NMDAR1) is a ligand-gated ion channel that is highly permeable to calcium ion (Ca2+). Because Cd2+ and Ca2+ have structural and physicochemical similarities, whether and how Cd could interfere NMDAR1 function to cause renal epithelial cells dysfunction remains unknown. In this study, we investigated the role of NMDAR1 in Cd-induced renal damage and found that Cd treatment upregulated NMDAR1 expression and promoted epithelial-mesenchymal transition (EMT) in mouse kidneys in vivo and human proximal tubular epithelial HK-2 cells in vitro, which were accompanied with activation of the inositol-requiring enzyme 1 (IRE-1α) / spliced X box binding protein-1 (XBP-1s) pathway, an indicative of endoplasmic reticulum (ER) stress. Mechanistically, NMDAR1 upregulation by Cd promoted Ca2+ channel opening and Ca2+ influx, resulting in ER stress and subsequently EMT in HK-2 cells. Inhibition of NMDAR1 by pharmacological antagonist MK-801 significantly attenuated Cd-induced Ca2+ influx, ER stress, and EMT. Pretreatment with the IRE-1α/XBP-1s pathway inhibitor STF-083010 also restored the epithelial phenotype of Cd-treated HK-2 cells. Therefore, our findings suggest that NMDAR1 activation mediates Cd-induced EMT in proximal epithelial cells likely through the IRE-1α/XBP-1s pathway, supporting the idea that NMDAR1 could be a potential therapeutic target for Cd-induced renal damage.

NLRP3 inflammasome-mediated pyroptosis involvement in cadmium exposure-induced cognitive deficits via the Sirt3-mtROS axis

Cadmium (Cd), a toxic heavy metal, exerts deleterious effects on neuronal survival and cognitive function. NOD-like receptor 3 (NLRP3) inflammasome-dependent pyroptosis has been linked to Cd-induced cytotoxicity. The current research intended to elucidate the role of NLRP3 inflammasome-mediated pyroptosis in Cd-evoked neuronal death and cognitive impairments and the underlying mechanisms. Exposure to 1 mg/kg Cd for 8 weeks led to hippocampal-dependent cognitive deficits and neural/synaptic damage in mice. NLRP3 inflammasome-related protein expression (NLRP3, ASC, and caspase1 p20) and neuronal pyroptosis were significantly upregulated in Cd-treated hippocampi and SH-SY5Y cells. Moreover, pretreatment with the NLRP3 inhibitor MCC950 mitigated Cd-elicited NLRP3 inflammasome activation and subsequent neuronal pyroptosis in SH-SY5Y cells. Furthermore, exposure to Cd downregulated Sirt3 expression, suppressed SOD2 activity by hyperacetylation, and enhanced mtROS accumulation in vivo and in vitro. Notably, Cd-induced NLRP3 inflammasome-dependent neuronal pyroptosis was attenuated by a mtROS scavenger or Sirt3 overexpression in SH-SY5Y cells. In addition, Cd failed to further suppress SOD activity and activate NLRP3 inflammasome-dependent neuronal pyroptosis in Sirt3 shRNA-treated SH-SY5Y cells. Collectively, our findings indicate that Cd exposure induces neuronal injury and cognitive deficits by activating NLRP3 inflammasome-dependent neuronal pyroptosis and that activation of the NLRP3 inflammasome is partially mediated by the Sirt3-mtROS axis.

Molecular mechanism of GSDMD mediated glomerular endothelial cells pyroptosis: An implying in the progression of diabetic nephropathy

Diabetic nephropathy (DN), a chronic progressive kidney disease, is the most prevalent microvascular complication associated with diabetes which causes the end-stage renal disease. Glomerular endothelial cells (GECs) are one of the inherent cells of the glomerulus and are particularly susceptible to be damaged by glucose, lipids and inflammatory factors. Numerous studies indicated that GECs injury was a critical pathological event in the early stages of DN. Previous studies have shown that podocyte pyroptosis occurred through the classical caspase-1 pathway, leading to kidney injury. However, the occurrence of pyroptosis in GECs and the underlying mechanism remain unclear. In this study, we investigated the pyroptosis of GECs during DN and its underlying mechanism. Upon stimulation with high glucose (HG), we observed the upregulation of GSDMD and cleaved N-terminus, disruption of cell membrane integrity, and an increase in IL-18 inflammatory cytokines. Also, we found that the expression of caspase-11, GSDMD and GSDMD-N were increased in C57BL/6J mice induced by STZ combined with high sugar and fat. In addition, the pathological results of kidney showed a significant thickening of the glomerular basement membrane, abnormal increasement of extracellular matrix and hyperplasia with blurred boundaries of glomerulus. Furthermore, interfering the expression of GSDMD improved the pathological degree of kidney. These findings indicated that the pyroptosis of GECs during DN was facilitated by the non-classical pathway of caspase-11/GSDMD, ultimately leading to GECs injury and further aggravating the progression of DN. This work highlights the potential of GSDMD as a therapeutic target for the treatment of DN.

Resveratrol‑mediated activation of SIRT1 inhibits the PERK‑eIF2α‑ATF4 pathway and mitigates bupivacaine‑induced neurotoxicity in PC12 cells

Endoplasmic reticulum (ER) stress and apoptosis play significant roles in the development of neurotoxicity caused by bupivacaine (BUP). By activating sirtuin 1 (SIRT1), resveratrol (RSV) can regulate various cellular processes associated with anti-oxidative stress, anti-apoptosis and anti-inflammatory responses, thereby exerting neuroprotective effects. However, it remains unknown whether the activation of SIRT1 by RSV is able to attenuate BUP-induced ER stress and apoptosis. Therefore, the present study aimed to explore the effect of RSV on BUP-induced cytotoxicity in PC12 cells and the underlying mechanism. Cell Counting Kit-8 assays, flow cytometry and inverted phase-contrast microscopy were used to assess the viability, apoptosis rate and morphological changes of the cells, respectively. Western blotting and immunofluorescence staining were used to analyze the levels of SIRT1, the apoptosis-related proteins Bax, Bcl-2 and cleaved caspase-3, the ER stress-related proteins glucose-regulated protein 78, caspase-12 and CHOP, and the protein kinase RNA-like ER kinase (PERK)-eukaryotic translation initiation factor 2 α (eIF2α)-activating transcription factor 4 (ATF4) pathway-associated proteins phosphorylated (p)-PERK, PERK, p-eIF2α, eIF2α and ATF4. The results revealed that BUP induced cell apoptosis and decreased cell viability, accompanied by the downregulation of SIRT1. However, RSV restored SIRT1 protein expression, downregulated the expression of the pro-apoptotic protein Bax, upregulated the expression of the anti-apoptotic protein Bcl-2, decreased the apoptosis rate of the cells and increased cell viability. Furthermore, the anti-apoptotic effects exhibited by RSV were associated with inhibition of the PERK-eIF2α-ATF4 pathway of ER stress. However, the protective effect of RSV was significantly mitigated by the SIRT1 inhibitor EX527. These results indicate that the activation of SIRT1 by RSV alleviates BUP-induced PC12 cell ER stress and apoptosis via regulation of the PERK-eIF2α-ATF4 pathway. These findings offer insights into the molecular mechanism underlying BUP-induced apoptosis and suggest the potential of RSV as a therapeutic agent against the neurotoxicity caused by BUP.

Cadmium-induced pyroptosis is mediated by PERK/TXNIP/NLRP3 signaling in SH-SY5Y cells

Cadmium (Cd) is a hypertoxic heavy metal that may be exposed to environmental pollutants by humans and animals. It can lead to cognitive disfunction, and is linked to neurodegenerative diseases. Cadmium reportedly can induce endoplasmic reticulum (ER) stress, but few studies have concentrated on it in nerve cells, and the connection between ER stress and neuroinflammation. In this study, in vitro experiments on SH-SY5Y neuroblastoma cells were carried out. We aimed at exploring whether Cd attributed to the cell pyroptosis and the role of PERK in promoting this form of cell damage which can induce strong inflammatory responses. Our results demonstrated that CdCl2 treatment induced excess reactive oxygen species (ROS) production, caused significant modifications in the expression of PERK and increased TXNIP, NLRP3, IL-1β, IL-18, and caspase1 in SH-SY5Y cells. In addition, scavenging ROS with N-acetylcysteine or inhibiting the expression of PERK by using GSK2606414, rescued the SH-SY5Y cells from cadmium-induced pyroptosis. In conclusion, the results suggest that Cd induces pyroptotic death of SH-SY5Y cells through ER stress, and this may be the potential mechanism of Cd incurring neurological diseases.

Epigenetic regulation of mitochondrial-endoplasmic reticulum dynamics in kidney diseases

Kidney diseases are serious health problems affecting >800 million individuals worldwide. The high number of affected individuals and the severe consequences of kidney dysfunction demand an intensified effort toward more effective prevention and treatment. The pathophysiology of kidney diseases is complex and comprises diverse organelle dysfunctions including mitochondria and endoplasmic reticulum (ER). The recent findings prove interactions between the ER membrane and nearly all cell compartments and give new insights into molecular events involved in cellular mechanisms in health and disease. Interactions between the ER and mitochondrial membranes, known as the mitochondria-ER contacts regulate kidney physiology by interacting with each other via membrane contact sites (MCS). ER controls mitochondrial dynamics through ER stress sensor proteins or by direct communication via mitochondria-associated ER membrane to activate signaling pathways such as apoptosis, calcium transport, and autophagy. More importantly, these organelle dynamics are found to be regulated by several epigenetic mechanisms such as DNA methylation, histone modifications, and noncoding RNAs and can be a potential therapeutic target against kidney diseases. However, a thorough understanding of the role of epigenetic regulation of organelle dynamics and their functions is not well understood. Therefore, this review will unveil the role of epigenetic mechanisms in regulating organelle dynamics during various types of kidney diseases. Moreover, we will also shed light on different stress origins in organelles leading to kidney disease. Henceforth, by understanding this we can target epigenetic mechanisms to maintain/control organelle dynamics and serve them as a novel therapeutic approach against kidney diseases.

Role and significance of SIRT1 in regulating the LPS-activated pyroptosis pathway in children with congenital hydronephrosis

Objective

To explore the characteristics and mechanism of sirtuin 1 (SIRT1) in lipopolysaccharide (LPS)-activated pyroptosis in the renal tissue of children with congenital hydronephrosis (CHn).

Methods

We detected the expression characteristics and clinical significance of SIRT1 and pyroptosis pathway proteins in CHn renal tissues by immunohistochemistry. The degree of renal fibrosis was detected by Masson staining. The human renal tubular epithelial cell line (HK-2) was cultured in vitro and treated with LPS (1 µg/mL), the SIRT1-specific agonist SRT1720 (2.5 µmol/L) and small interfering RNA (siRNA)-SIRT1 for 48 hours. After 48 hours, Cell Counting Kit-8 was used to detect the changes in cell proliferation ability, and ELISA was used to detect the changes in the expression of interleukin (IL)-1β and IL-18 in the cell supernatant. Real-time PCR (quantitative RT-PCR) and western blot analysis were used to detect the expression of SIRT1, caspase-1, caspase-4, NOD-like receptor thermal protein domain associated protein 3(NLRP3), and cleaved gasdermin D (GSDMD) in each group.

Results

Serum inflammatory cytokines were significantly elevated in 13 children with CHn with urinary tract infection, mainly caused by Gram-negative bacteria. Severe renal fibrosis occurred in children with CHn. Compared with the control group, the expression of SIRT1 in CHn kidney tissues was decreased, and the expression of caspase-4 and GSDMD was increased. LPS inhibited the expression of SIRT1 in HK-2 cells, promoted the expression of caspase-1, caspase-4, NLRP3, cleaved GSDMD, promoted the expression of IL-1β and IL-18 in the supernatant, and promoted pyroptosis in HK-2 cells. SRT1720 can inhibit LPS-activated pyroptosis by promoting SIRT1 expression, while siRNA-SIRT1 can further aggravate LPS-activated pyroptosis after inhibiting SIRT1 expression.

Conclusions

LPS can promote the inflammatory response in children with CHn by activating non-canonical pyroptosis and inhibiting SIRT1 expression. Promoting SIRT1 expression can inhibit pyroptosis of renal tubular epithelial cells, reduce the release of IL-18 and IL-1β, and alleviate the progression of renal fibrosis in children with CHn.

The role of Chinese herbal medicine in the treatment of diabetic nephropathy by regulating endoplasmic reticulum stress

Diabetic nephropathy (DN), a prevalent microvascular complication of diabetes mellitus, is the primary contributor to end-stage renal disease in developed countries. Existing clinical interventions for DN encompass lifestyle modifications, blood glucose regulation, blood pressure reduction, lipid management, and avoidance of nephrotoxic medications. Despite these measures, a significant number of patients progress to end-stage renal disease, underscoring the need for additional therapeutic strategies. The endoplasmic reticulum (ER) stress response, a cellular defense mechanism in eukaryotic cells, has been implicated in DN pathogenesis. Moderate ER stress can enhance cell survival, whereas severe or prolonged ER stress may trigger apoptosis. As such, the role of ER stress in DN presents a potential avenue for therapeutic modulation. Chinese herbal medicine, a staple in Chinese healthcare, has emerged as a promising intervention for DN. Existing research suggests that some herbal remedies may confer renoprotective benefits through the modulation of ER stress. This review explores the involvement of ER stress in the pathogenesis of DN and the advancements in Chinese herbal medicine for ER stress regulation, aiming to inspire new clinical strategies for the prevention and management of DN.

Through regulation of the SIRT1 pathway plant sterol ester of α-linolenic acid inhibits pyroptosis thereby attenuating the development of NASH in mice

Increasing evidence demonstrated that pyroptosis and subsequent inflammation played an important role in the pathological process of non-alcoholic steatohepatitis (NASH). Plant sterol ester of α-linolenic acid (PS-ALA) was beneficial for non-alcoholic fatty liver disease, but the underlying mechanisms are still not fully understood. This study aims to investigate whether PS-ALA can protect against proptosis via regulating SIRT1. Thirty male C57BL/6J mice were fed a normal diet, a high-fat and high-cholesterol diet (HFCD), or a HFCD supplemented with either 1.3%ALA, 2%PS, or 3.3% PS-ALA for 24 weeks. Hepatocytes were treated with oleic acid and cholesterol (OA/Cho) with or without PS-ALA. We found that PS-ALA ameliorated NASH in HFCD-fed mice. In addition, PS-ALA decreased the expression of NLRP3 and ASC and reduced the co-localization of NLRP3 and cleave-Caspase-1. Also, PS-ALA protected against pyroptosis as evidenced by decreased co-localization of GSDMD and propidium iodide (PI) positive cells. Mechanistically, we revealed that the inhibitory action of PS-ALA on the pyroptosis was mediated by SIRT1. This was demonstrated by the fact that silencing SIRT1 with small interfering RNA or inhibition of SIRT1 with its inhibitor abolished the inhibition effect of PS-ALA on the expression of NLRP3 and GSDMD cleavage. Collectively, the data from the present study reveals a novel mechanism that PS-ALA inhibits pyroptosis and it triggered inflammation via stimulating SIRT1, which provides new insights into the beneficial effect of PS-ALA on NASH.

Beneficial effects of Chrysin on Cadmium-induced nephrotoxicity in rats: Modulating the levels of Nrf2/HO-1, RAGE/NLRP3, and Caspase-3/Bax/Bcl-2 signaling pathways

Cadmium (Cd) is a toxic heavy metal that targets the kidney directly in the body. Chrysin (CHR) is a natural flavonoid with many properties such as antioxidant, anti-inflammatory and anti-apoptotic. The current study discloses new evidence as regards of the curative effects of CHR on Cd-induced nephrotoxicity by regulating oxidative stress, apoptosis, autophagy, and inflammation. Cd was administered orally at a dose of 25 mg/kg body weight alone or in combination with orally administered CHR (25 and 50 mg/kg body weight) for 7 days. Biochemical, molecular, and histological methods were used to investigate inflammation, apoptosis, autophagy, and oxidant pathways in renal tissue. Renal function tests were also evaluated. Cd caused an increase in serum toxicity markers, lipid peroxidation and a decrease in the activities of antioxidant enzymes. Nrf-2 triggered inflammatory responses by suppressing HO-1 and NQO1 mRNA transcripts and increasing NF-κB, TNF-α, IL-1β and iNOS mRNA transcripts. Cd caused inflammasome by increasing RAGE and NLRP3 mRNA transcripts. In addition, Cd application caused apoptosis by increasing Bax, Apaf-1 and Caspase-3 mRNA transcripts and decreasing Bcl-2 mRNA transcript level. It caused autophagy by increasing the activity of Beclin-1 level. CHR treatment had the opposite effect on all these values and reduced the damage caused by all these signal pathways. Overall, the data of this study indicate that renal damage associated with Cd toxicity could be ameliorated by CHR administration.

SIRT3 alleviates imiquimod-induced psoriatic dermatitis through deacetylation of XBP1s and modulation of TLR7/8 inducing IL-23 production in macrophages

Current evidence suggests that IL-23, IL-6, and TNF-α play pivotal roles in the pathogenesis of psoriasis. Although it has been established that Sirtuin 3 (SIRT3) mediates the inflammatory process, the underlying mechanisms remain largely unclear. Herein, we substantiated that the inhibition or deletion of SIRT3 increased the acetylation level of spliced form of X-box binding protein 1 (XPB1s), enhancing its transcriptional activity and IL-23a production. Pharmacologically inhibition of XBP1s with MKC8866 downregulated the expression of inflammatory cytokines in SIRT3-inhibited or Sirt3-KO BMDMs stimulated by IMQ. Inhibition or knockdown of SIRT3 could exacerbate psoriasis-like skin inflammation in an imiquimod-induced psoriasis-like mouse model. Besides, a decrease in SIRT3 expression was observed in the macrophages of psoriasis patients, which increased the expression and acetylation level of XBP1s. Overall, we provide compelling evidence of the crucial role of SIRT3 in the IL-23 axis in psoriatic inflammation and novel molecular insights into the anti-inflammatory effects of SIRT3.

Cadmium exposure impairs oocyte meiotic maturation by inducing endoplasmic reticulum stress in vitro maturation of porcine oocytes

Cadmium (Cd) is toxic metal that can induce various diseases, such as cardiovascular, nervous, and reproductive systems. This study investigated the effect of Cd exposure on porcine oocyte maturation and the underlying mechanism. Porcine cumulus-oocyte complexes were exposed various Cd concentration and tauroursodeoxycholic acid (TUDCA), an inhibitor of endoplasmic reticulum (ER) stress during in vitro maturation (IVM). After IVM, we evaluated meiotic maturation, ER stress, and oocyte quality by Cd exposure. Cd exposure inhibited cumulus cell expansion and meiotic maturation, increased oocyte degeneration, and induced ER stress. The levels of spliced XBP1 and ER stress-associated transcripts, markers of ER stress, were elevated in Cd-treated cumulus-oocyte complexes and denuded oocytes during IVM. Moreover, Cd-induced ER stress impaired oocyte quality by disrupting mitochondrial function and elevating intracellular reactive oxygen species levels while decreasing ER function. Interestingly, TUDCA supplementation significantly decreased the expression of ER stress-related genes and increased the quantity of ER compared with the Cd treatment. Additionally, TUDCA was also able to rescue excessive levels of ROS and restore normal mitochondrial function. Moreover, the addition of TUDCA under Cd exposure greatly ameliorated Cd-mediated detrimental effects on meiotic maturation and oocyte quality, including cumulus cell expansion and MII rate. These findings suggest that Cd exposure during IVM impairs the meiotic maturation of oocytes by inducing of ER stress.

Mechanism of histone deacetylase HDAC2 in FOXO3-mediated trophoblast pyroptosis in preeclampsia

Histone deacetylase 2 (HDAC2) has been demonstrated to regulate trophoblast behaviors. However, its role in trophoblast pyroptosis remains unknown. This study sought to analyze the molecular mechanism of HDAC2 in trophoblast pyroptosis in PE. Expression levels of HDAC2, forkhead box O3 (FOXO3), and protein kinase R-like endoplasmic reticulum kinase (PERK) in placenta tissues and HTR8/SVneo cells and H3K27ac levels in cells were determined. Levels of IL-1β and IL-18 in placenta tissues were determined, and their correlation with HDAC2 was analyzed. Cell proliferation, migration, and invasion were evaluated, and levels of pyroptosis-associated proteins and cytokines were determined. The enrichments of H3K27 acetylation (H3K27ac) and FOXO3 in the FOXO3/PERK promoter region were determined. HDAC2 was downregulated, and FOXO3, PERK, IL-1β, and IL-18 levels were elevated in PE placenta tissues. In HTR8/SVneo cells, HDAC2 downregulation suppressed cell proliferation, migration, and invasion and increased pyroptosis. HDAC2 erased H3K27ac in the FOXO3 promoter region and repressed FOXO3, and FOXO3 bound to the PERK promoter and increased PERK transcription. Functional rescue experiments revealed that silencing FOXO3 or PERK counteracted HDAC2 downregulation-induced cell pyroptosis. Overall, HDAC2 downregulation enhanced H3K27ac to activate FOXO3 and PERK, leading to the occurrence of trophoblast pyroptosis in PE.

Coexposure to multiple metals and renal tubular damage: a population-based cross-sectional study in China's rural regions

Previous studies have indicated that exposure to a single toxic metal can cause renal tubular damage, while evidence about the effects of multimetal exposure on renal tubular damage is relatively limited. We aimed to evaluate the relationships of multimetal coexposure with renal tubular damage in adults in heavy metal-polluted rural regions of China. A cross-sectional study of 1918 adults in China's heavy metal-contaminated rural regions was conducted. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to measure the plasma levels of 18 metals in participants, and immune turbidimetry was used to measure sensitive biological indicators, reflecting renal tubular damage (including retinol-binding protein and β2-microglobulin). Least absolute shrinkage and selection operator (LASSO) penalized regression analysis, logistic and linear regression analysis, restricted cubic spline (RCS) regression analysis and the Bayesian kernel machine regression (BKMR) method were used to explore associations of multimetal coexposure with renal tubular damage risk or renal tubular damage indicators. Plasma selenium, cadmium, arsenic, and iron were identified as the main plasma metals associated with renal tubular damage risk after dimensionality reduction. Multimetal regression models showed that selenium was positively associated, and iron was negatively associated with renal tubular damage risk or its biological indicators. Multimetal RCS analyses additionally revealed a non-linear relationship of selenium with renal tubular damage risk. The BKMR models showed that the metal mixtures were positively associated with biological indicators of renal tubular damage when the metal mixtures were above the 50th percentile of concentration. Our findings indicated that natural exposure to high levels of multimetal mixtures increases the risk of renal tubular damage. Under the conditions of multimetal exposure, selenium was positively associated, and iron was negatively associated with renal tubular damage risk or its biological indicators.

Cadmium induces mitochondrial dysfunction via SIRT1 suppression-mediated oxidative stress in neuronal cells

Cadmium is a widespread environmental contaminant and its neurotoxicity has raised serious concerns. Mitochondrial dysfunction is a key event in Cd-induced nervous system disease; however, the exact molecular mechanism involved has not been fully elucidated. Increasing evidences have shown that Sirtuin 1 (SIRT1) is the key target protein impaired in Cd-induced mitochondrial dysfunction. In this study, the role of SIRT1 in Cd-induced mitochondrial dysfunction and cell death and the underlying mechanisms were evaluated in vitro using PC12 cells and primary rat cerebral cortical neurons. The results showed that Cd exposure caused cell death by inhibiting SIRT1 expression, thus inducing oxidative stress and mitochondrial dysfunction in vitro. However, inhibition of oxidative stress by the antioxidant puerarin alleviated Cd-induced mitochondrial dysfunction. Furthermore, activation of SIRT1 using the agonist Srt1720 significantly abolished Cd-induced oxidative stress and mitochondrial dysfunction and ultimately alleviated Cd-induced neuronal cell death. Collectively, our data indicate that Cd induced mitochondrial dysfunction via SIRT1 suppression-mediated oxidative stress, leading to the death of PC12 cells and primary rat cerebral cortical neurons. These findings suggest a novel mechanism for Cd-induced neurotoxicity.

Pollutant-induced pyroptosis in humans and other animals

Pyroptosis is a form of lytic cell death with pro-inflammatory characteristics, induced upon the activation of certain inflammatory caspases by inflammasome complexes such as NLRP3 inflammasome. Gasdermin proteins as the mediators of pyroptosis form cell membrane pores upon activation, which release certain cellular contents into the extracellular space including inflammatory cytokines such as IL-1β and IL-18, and also damage the integrity of the cell membrane. Gasdermins have been implicated in autoimmune and inflammatory diseases, infectious diseases, deafness and cancer. Mostly in the last 2 years, diverse pollutant types including particulate matter, cadmium and polystyrene microplastics were reported to induce pyroptotic cell death in diverse tissues from mammals to birds. In the present study, we review our current understanding of pollutant-induced pyroptosis as well as current knowledge of upstream events leading to pyroptotic cell death upon exposure to pollutants.

Hydroquinone triggers pyroptosis and endoplasmic reticulum stress via AhR-regulated oxidative stress in human lymphocytes

Benzene is a frequent component of environmental pollution and is abundant in petrochemicals, decorative materials, motor vehicle exhaust and cigarette smoke. Benzene is a well-known carcinogen in humans and animals, but the molecular mechanism has not yet been elucidated. Our earlier research indicated that hydroquinone (HQ), one of the main reactive metabolites of benzene, could activate aryl hydrocarbon receptor (AhR), which is essential for HQ-induced toxicity, including apoptosis and DNA damage. Since AhR is an important regulator of the immune system that integrates the environmental stimulus and immune response, we examined whether and how HQ-induced AhR activity could lead to NLRP3 inflammasome-dependent pyroptosis in JHP cells. Our results showed that HQ could cause inflammation process and resultant pyroptosis. In JHP cells, HQ also induced endoplasmic reticulum stress (ERS) by releasing excessive reactive oxygen species (ROS). The activation of pyroptosis induced by HQ treatment was reversed by an antioxidant (NAC) and an ERS inhibitor (4-PBA). Interestingly, the treatment of CH223191, an AhR inhibitor, reversed HQ-induced oxidative stress, ERS and pyroptosis. These data suggested that AhR-mediated HQ-induced ERS, ROS and inflammasome activation may play vital roles in the toxic effects of benzene. This work provides insights and prospective strategies into potential mechanisms for reducing benzene-induced hematotoxicity.

XBP1 modulates endoplasmic reticulum and mitochondria crosstalk via regulating NLRP3 in renal ischemia/reperfusion injury

The functional status of mitochondria and the endoplasmic reticulum are central to renal ischemia/reperfusion injury (IRI). X-box binding protein 1 (XBP1) is an important transcription factor in endoplasmic reticulum stress. NLR family pyrin domain containing-3 (NLRP3) inflammatory bodies are closely related to renal IRI. In vivo and in vitro, we examined the molecular mechanisms and functions of XBP1-NLRP3 signaling in renal IRI, which influences ER-mitochondrial crosstalk. In this study, mice were subjected to 45 min of unilateral renal warm ischemia, the other kidney resected, and reperfusion was performed for 24 h in vivo. In vitro, murine renal tubular epithelial cells (TCMK-1) were exposed to hypoxia for 24 h and reoxygenation for 2 h. Tissue or cell damage was evaluated by measuring blood urea nitrogen and creatinine levels, histological staining, flow cytometry, terminal deoxynucleotidyl transferase-mediated nick-end labeling, diethylene glycol staining, and transmission electron microscopy (TEM). Western blotting, immunofluorescence staining, and ELISA were used to analyze protein expression. Whether XBP1 regulates the NLRP3 promoter was evaluated using a luciferase reporter assay. Kidney damage was reduced with decreasing blood urea nitrogen, creatinine, interleukin-1β, and interleukin-18 levels. XBP1 deficiency reduced tissue damage and cell apoptosis, protecting the mitochondria. Disruption of XBP1 was associated with reduced NLRP3 and cleaved caspase-1 levels and markedly improved survival. In vitro in TCMK-1 cells, XBP1 interference inhibited caspase-1-dependent mitochondrial damage and reduced the production of mitochondrial reactive oxygen species. The luciferase assay showed that spliced XBP1 isoforms enhanced the activity of the NLRP3 promoter. These findings reveal that XBP1 downregulation suppresses the expression of NLRP3, a potential regulator of endoplasmic reticulum mitochondrial crosstalk in nephritic injury and a potential therapeutic target in XBP1-mediated aseptic nephritis.

N-acetylcysteine delayed cadmium-induced chronic kidney injury by activating the sirtuin 1-P53 signaling pathway

With the development of modern industrial civilization, cadmium (Cd), a known nephrotoxic metal, has become a growing public safety issue due to its ability to induce various types of kidney disease. Maladaptive proximal tubule repair is a significant cause of Cd-induced chronic kidney disease (CKD), which is characterized by premature senescence and pro-fibrosis. Previously, we demonstrated that cadmium causes DNA damage and cycle arrest in renal tubular epithelial cells, which may be relevant to premature senescence regulated by sirtuin 1 (SIRT1). In this study, in vivo and in vitro studies were conducted to elucidate the role of SIRT1-mediated premature renal senescence in Cd-induced CKD. As oxidative stress is a significant cause of aging, we evaluated whether N-acetylcysteine (NAC) would inhibit Cd-induced premature aging and dysfunction in rat renal tubular epithelial cells. Cadmium induced premature renal senescence and fibrosis, and NAC inhibited premature renal senescence and fibrosis through the SIRT1-P53 pathway and delayed CKD progression. Overall, the results suggested that the SIRT1-P53 pathway mediates oxidative stress, premature renal senescence, and renal fibrosis during cadmium exposure, which may be a potential therapeutic target for Cd-induced CKD.

Repair effect of the poly (D,L-lactic acid) nanoparticle containing tauroursodeoxycholic acid-eluting stents on endothelial injury after stent implantation

Background

Chronic endoplasmic reticulum stress (ERS) plays a crucial role in cardiovascular diseases. Thus, it can be considered a therapeutic target for these diseases. In this study, poly (D,L-lactic acid) (PDLLA) nanoparticle-eluting stents loaded with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor, was fabricated to assess their ability to reduce endothelial cell apoptosis and promote re-endothelialization after stent implantation.

Materials and methods

PDLLA nanoparticles loaded with TUDCA were prepared via the emulsification-solvent evaporation method. The cumulative release rates of TUDCA were measured in vitro via high-performance liquid chromatography. The carotid arteries of rabbits were subsequently implanted with stents in vivo. The rabbits were then sacrificed after 4 weeks for scanning electron microscopy. Meanwhile, TUDCA concentration in the homogenate of the peripheral blood and distal vascular tissue after stent implantation was measured. The effect of TUDCA on ERS, apoptosis, and human umbilical vein endothelial cell (HUVEC) function was investigated in vitro by performing cell migration assay, wound healing assay, cell proliferation assays, endoplasmic reticulum (ER)-specific fluorescence staining, immunofluorescence, and western blotting.

Results

TUDCA nanoparticles were released slowly over 28 days. In addition, TUDCA-eluting stents enhanced re-endothelialization and accelerated the recovery of endotheliocytes in vivo. ERS and apoptosis significantly increased in H₂O₂-treated HUVECs in vitro. Meanwhile, TUDCA reduced apoptosis and improved function by inhibiting ERS in H₂O₂-treated HUVECs. Decreased rates of apoptosis and ERS were observed after silencing XBP-1s in H₂O₂-treated HUVECs.

Conclusion

TUDCA can inhibit apoptosis and promote re-endothelialization after stent implantation by inhibiting IRE/XBP1s-related ERS. These results indicate the potential therapeutic application of TUDCA as a drug-coated stent.

Sirtuin-1 attenuates cadmium-induced renal cell senescence through p53 deacetylation

Cadmium (Cd), the common environmental pollutant, primarily targets at renal proximal tubules and induces nephrotoxicity. Cellular senescence, a phenomenon of cell growth arrest and a characteristics of maladaptive cell self-repair, is associated with renal disease progression. However, whether and how Cd induces renal tubular cells premature senescence is unknown. In our study, we found that Cd induced kidney damage and dysfunctions, which correlated with exacerbated tubular cell senescence, evidenced by increased senescence-associated β-galactosidase activity, the upregulated protein expression of p53 and p21^Waf1/Cip1 proteins, and elevated expression and secretion of cytokines in human proximal tubular epithelial HK-2 cells in vitro and in Cd-treated mice in vivo. Moreover, a S-phase arrest and decrease in Edu positive rate were found in Cd-treated HK-2 cells. Mechanistically, Cd suppressed the expression and activity of Sirtuin-1 (SIRT1), an anti-senescence deacetylase, resulting in the accumulation of acetylated p53 and upregulation of p21^Waf1/Cip1. Activation of SIRT1 significantly abolished Cd-induced premature senescence and S-phase arrest. Finally, silencing p21^Waf1/Cip1 efficiently delayed premature senescence and recovered cell cycle progression. These findings indicate that Cd promotes tubular cells senescence and impairs tubular cells regeneration, resulting in kidney dysfunctions, which could be ameliorated by SIRT1 activation.

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.

Melatonin improves mitochondrial function by preventing mitochondrial fission in cadmium-induced rat proximal tubular cell injury via SIRT1-PGC-1α pathway activation

Melatonin is an indoleamine produced in the pineal gland and has many physiological roles. There is increasing evidence that melatonin ameliorates cadmium (Cd)-induced nephrotoxicity. The potential protective impact of melatonin against Cd-induced nephrotoxicity and the mechanisms behind this protection are unknown. The relevance of mitochondrial dynamics in Cd-induced nephrotoxicity and the putative mechanism of melatonin-mediated protection were examined in this study. We show that melatonin prevents Cd-induced nephrotoxicity by inhibiting dynamin-related protein 1 (Drp1)- and mitochondrial fission protein 1 (Fis1)-mediated mitochondrial fission. Melatonin treatment attenuated cytotoxicity, suppressed oxidative stress, restored mitochondrial membrane potential, and increased mitochondrial mass in response to Cd exposure. Consistent with this finding, melatonin treatment increased Cd-inhibited sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) expression and inhibited Drp1- and Fis1-mediated mitochondrial fission. Like melatonin, SIRT1 overexpression via resveratrol attenuated Drp1- and Fis1-mediated mitochondrial fission and other Cd-induced mitochondrial oxidative injuries effectively. Melatonin has significant pharmacological potential for protecting against Cd-induced nephrotoxicity by preventing excessive mitochondrial fission.

Yeast Selenium Exerts an Antioxidant Effect by Regulating the Level of Selenoprotein to Antagonize Cd-Induced Pyroptosis of Chicken Liver

Cadmium (Cd) exposure can cause multiple organ damage in humans and animals by causing oxidative stress. Organic selenium can antagonize the toxic damage of heavy metals by exerting antioxidant effects. Oxidative stress can activate NLRP3/Caspase1-dependent pyroptosis, but it is not clear whether yeast selenium (Se Y) can antagonize Cd-induced pyroptosis in the chicken liver. In this experiment, we studied the effects of CdCl₂ single, Se Y single, and combined exposure on the pyroptosis of chicken liver. The results showed that Cd exposure induced oxidative stress in the chicken liver, and the expression of Sepx1, SelU, SelT, GPx1, GPx4, Dio1, Dio2, Dio3, TrxR1, TrxR2, TrxR3, SelH, SelI, SelO, SelK, SelPb, Selpp, and Sel15 decreased. In addition, NLRP3 inflammasome complex (NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing (ASC), and pro-Caspase1), Cysteinyl aspartate specific proteinase (Caspase1), Interleukin-β (IL-1β), and Interleukin-18 (IL-18) were upregulated. The combined treatment of Se Y and Cd found that the antioxidant level and the expression level of selenoprotein recovered to the Se group, and the liver pyroptosis decreased. Principal component analysis and correlation analysis screened out that selenoprotein O (SelO) is negatively correlated with pyroptosis-related genes. In short, our data shows that Se Y exerts an antioxidant effect by increasing the expression of selenoproteins and antagonizing the pyroptosis of chicken liver induced by Cd. This study provides new ideas for the field of heavy metal toxicology research. And the selected SelO has an important reference significance for follow-up research.

Melatonin promotes sirtuin 1 expression and inhibits IRE1α–XBP1S–CHOP to reduce endoplasmic reticulum stress–mediated apoptosis in chondrocytes

Osteoarthritis (OA) is the most common chronic disease characterized by a loss of chondrocytes and the degeneration of cartilage. Inflammation plays an important role in the pathogenesis and progression of OA via the activation of the endoplasmic reticulum (ER) stress signaling pathway. In this study, we stimulated human primary chondrocytes with lipopolysaccharide (LPS) to reduce cell viability and induce chondrocyte apoptosis. LPS–stimulated human primary chondrocytes induced ER stress and significantly upregulated the ER chaperone glucose–regulated protein 78 (GRP78) and increased the expression level of C/EBP–homologous protein (CHOP), a key mediator of ER stress––induced apoptosis. Interestingly, melatonin treatment attenuated ER stress–mediated chondrocyte apoptosis. Melatonin inhibited the expression of cleaved caspase-3, cleaved caspase-10, Bax, CHOP, GRP78, cleaved caspase-4, phospho–inositol–requiring enzyme 1α (P-IRE1α), and spliced X-box-binding protein 1 (XBP1S). In an anterior cruciate ligament transection mouse model of OA, melatonin (50 and 150 mg/kg) dose–dependently relieved joint cartilage degeneration and inhibitied of chondrocyte apoptosis. Immunohistochemical analysis indicated that melatonin could promote SIRT1 the expression and inhibit CHOP and cleaved caspase-3 expression in OA mice. In conclusion, our findings demonstrate for the first time that melatonin inhibits the IRE1α-XBP1S-CHOP signaling pathway by promoting the expression of SIRT1 in LPS-treated human chondrocytes and delaying OA progression in vivo.

Epigallocatechin-3-gallate ameliorates renal endoplasmic reticulum stress-mediated inflammation in type 2 diabetic rats

Epigallocatechin-3-gallate (EGCG), an essential polyphenolic constituent found in tea leaves, possesses various potent biological activities. This research was undertaken to investigate the impact of EGCG against endoplasmic reticulum (ER) stress-mediated inflammation and to clarify the underlying molecular mechanism in type 2 diabetic kidneys. The male rats were randomized into four groups: normal, diabetic, low-dose EGCG, and high-dose EGCG. In type 2 diabetic rats, hyperglycemia and hyperlipidemia noticeably caused renal structural damage and dysfunction and aggravated ER stress. Meanwhile, sustained ER stress activated the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and then upregulated the contents of inflammatory cytokines in the diabetic kidney. Following supplementation with 40 mg/kg and 80 mg/kg EGCG, hyperglycemia, hyperlipidemia, and renal histopathological alterations and dysfunction were noticeably ameliorated; renal ER stress, NLRP3 inflammasome, and inflammatory response were markedly repressed in the EGCG treatment groups. In summary, the current study highlighted the renoprotective effects of EGCG in type 2 diabetes and its mechanisms are mainly associated with the repression of ER stress-mediated NLRP3 inflammasome overactivation.

Transcriptomics-based analysis of co-exposure of cadmium (Cd) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) indicates mitochondrial dysfunction induces NLRP3 inflammasome and inflammatory cell death in renal tubular epithelial cells

Environmental pollution often releases multiple contaminants resulting in as yet largely uncharacterized additive toxicities. Cadmium (Cd) is a widespread pollutant that induces nephrotoxicity in animal models and humans. However, the combined effect of Cd in causing nephrotoxicity with 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a typical congener of polybrominated diphenyl ethers (PBDEs), has not been evaluated and mechanisms are not completely clear. Here, we applied transcriptome sequencing analysis to investigate the combined toxicity of Cd and BDE-47 in the renal tubular epithelial cell lines HKCs. Cd or BDE-47 exposure decreased cell viability in a dose-dependent manner, and exhibited cell swelling and rounding similar to necrosis, which was exacerbated by co-exposure. Transcriptomic analysis revealed 2191, 1331 and 3787 differentially-expressed genes following treatment with Cd, BDE-47 and co-exposure, respectively. Interestingly, functional annotation and enrichment analyses showed involvement of pathways for oxidative stress, NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and inflammatory cell death for all three treatments. Examination of indices of mitochondrial function and oxidative stress in HKC cells showed that the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and intracellular calcium ion concentration [Ca²⁺]i were elevated, while superoxide dismutase (SOD) and mitochondrial membrane potential (MMP) were decreased. The ratio of apoptotic and necrotic cells and intracellular lactate dehydrogenase (LDH) release were increased by Cd or BDE-47 exposure, and was aggravated by co-exposure, and was attenuated by ROS scavenger N-Acetyl-L-cysteine (NAC). NLRP3 inflammasome and pyroptosis pathway-related genes of NLRP3, adaptor molecule apoptosis-associated speck-like protein (ASC), caspase-1, interleukin-18 (IL-18) and IL-1β were elevated, while gasdermin D (GSDMD) was down-regulated, and protein levels of NLRP3, cleaved caspase-1 and cleaved GSDMD were increased, most of which were relieved by NAC. Our data demonstrate that exposure to Cd and BDE-47 induces mitochondrial dysfunction and triggers NLRP3 inflammasome and GSDMD-dependent pyroptosis leading to nephrotoxicity, and co-exposure exacerbates this effect, which could be attenuated by inhibiting ROS. This study provides a further mechanistic understanding of kidney damage, and co-exposure impact is worthy of concern and should be considered to improve the accuracy of environmental health assessment.

Melatonin ameliorates renal dysfunction in glyphosate- and hard water-treated mice

Chronic interstitial nephritis in agricultural communities (CINAC) is a severe and widespread disease that has been associated with environmental and occupational exposure to glyphosate and hard water. However, the potential underlying mechanisms remain incompletely understood. Melatonin is reported to exert protective effects on the kidney, but whether melatonin can attenuate renal tubular injury in mice exposed to glyphosate combined with hard water is unclear. Here, mice were treated with high doses and environmentally relevant doses of glyphosate (100 mg/kg·bw and 0.7 mg/L, respectively) and/or hard water (2500 mg/L CaCO₃ and 250 mg/L Ca²⁺, respectively) via their drinking water for 12 weeks. We found that high-dose glyphosate or hard water treatment significantly increased the levels of biomarkers of renal damage, including β₂-microglobulin, neutrophil gelatinase-associated lipid carrier protein, and/or albumin, in the urine; these increased biomarker levels were correlated with obvious morphological changes, and all of these changes were also observed in animals exposed to environmentally relevant doses of glyphosate and/or high Ca²⁺ water. Melatonin (10 mg/kg·bw, intraperitoneal injection, daily for 12 weeks) administered concomitantly with high doses of glyphosate and hard water inhibited the glyphosate- and hard water-induced increases in the levels of kidney injury biomarkers and changes in morphology; this result was intriguing. Additionally, glyphosate combined with hard water at both high and environmentally relevant doses significantly upregulated the expression of the endoplasmic reticulum (ER) stress marker proteins Bip, ATF6, and PERK as well as the pyroptosis-related proteins (NLRP3 and caspase 1 signaling proteins) in renal tissues. Similarly, melatonin significantly attenuated the increased ER stress and pyroptosis induced by high doses of glyphosate and hard water. In summary, we conclude that exposure to glyphosate and hard water at both high doses and environmentally relevant doses causes renal dysfunction in mice, and this dysfunction can be attenuated by melatonin, possibly through the inhibition of ER stress and pyroptosis. Our results support the notion that melatonin may have therapeutic potential for the treatment of chronic kidney diseases.

Notch-activated mesenchymal stromal/stem cells enhance the protective effect against acetaminophen-induced acute liver injury by activating AMPK/SIRT1 pathway

Background

Notch signaling plays important roles in regulating innate immunity. However, little is known about the role of Notch in mesenchymal stromal/stem cell (MSC)-mediated immunomodulation during liver inflammatory response.

Methods

Notch activation in human umbilical cord-derived MSCs was performed by a tissue culture plate coated with Notch ligand, recombinant human Jagged1 (JAG1). Mice were given intravenous injection of Notch-activated MSCs after acetaminophen (APAP)-induced acute liver injury. Liver tissues were collected and analyzed by histology and immunohistochemistry.

Results

MSC administration reduced APAP-induced hepatocellular damage, as manifested by decreased serum ALT levels, intrahepatic macrophage/neutrophil infiltration, hepatocellular apoptosis and proinflammatory mediators. The anti-inflammatory activity and therapeutic effects of MSCs were greatly enhanced by Notch activation via its ligand JAG1. However, Notch2 disruption in MSCs markedly diminished the protective effect of MSCs against APAP-induced acute liver injury, even in the presence of JAG1 pretreatment. Strikingly, Notch-activated MSCs promoted AMP-activated protein kinase (AMPKα) phosphorylation, increased the sirtuins 1 (SIRT1) deacetylase expression, but downregulated spliced X-box-binding protein 1 (XBP1s) expression and consequently reduced NLR family pyrin domain-containing 3 (NLRP3) inflammasome activation. Furthermore, SIRT1 disruption or XBP1s overexpression in macrophages exacerbated APAP-triggered liver inflammation and augmented NLRP3/caspase-1 activity in MSC-administrated mice. Mechanistic studies further demonstrated that JAG1-pretreated MSCs activated Notch2/COX2/PGE2 signaling, which in turn induced macrophage AMPK/SIRT1 activation, leading to XBP1s deacetylation and inhibition of NLRP3 activity.

Conclusions

Activation of Notch2 is required for the ability of MSCs to reduce the severity of APAP-induced liver damage in mice. Our findings underscore a novel molecular insights into MSCs-mediated immunomodulation by activating Notch2/COX2/AMPK/SIRT1 pathway and thus provide a new strategy for the treatment of liver inflammatory diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02999-6.

The role of endoplasmic reticulum stress in the pathophysiology of periodontal disease

The endoplasmic reticulum (ER) is a principal organelle for folding, post-translational modifications and transport of secretory, luminal, and membrane proteins. ER stress is a condition induced by the accumulation of unfolded or misfolded proteins owing to a variety of physiological and pathological phenomena. To overcome the deleterious effects of ER stress, unfolded protein response (UPR) is initiated to translocate and remove the misfolded and accumulated proteins. Plenty of evidence shows the correlation between ER stress/UPR and the pathology of inflammatory disease. Periodontal disease is a chronic inflammatory disease characterized by the irreversible destruction of periodontal tissues, which associates with the onset and progress of several systemic diseases. Periodontopathic bacterium and pro-inflammatory mediators play a pivotal role in the progress of periodontal disease. Besides, cigarette smoke has long been associated with periodontal disease. As an inflammatory disorder of the periodontium, periodontal disease is highly related to ER stress. In this review, we provide an overview of the pathophysiological effect of ER stress on periodontal disease through five aspects as follow: ER stress and periodontal tissue remodeling, including both soft tissue and hard tissue; ER stress and the inflammation; ER stress and systematic effect during the periodontal disease; last but not least, ER stress and the autophagic apoptosis in cells.

Endoplasmic reticulum stress regulates pyroptosis in BPDE-induced BEAS-2B cells

Benzo(a)pyrene(B(a)P), as the main representative of polycyclic aromatic hydrocarbons, can promote inflammation and many chronic pulmonary diseases. However, the underlying mechanism of Benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE)-induced human bronchial epithelial cell pyroptosis related to endoplasmic reticulum stress (ERS) has not been elucidated. This study focused on the effects of BPDE on ERS and pyroptosis in human bronchial epithelial cells (BEAS-2B), and explored the relationship between ERS and pyroptosis. BEAS-2B cells were stimulated with 0.50, 0.75, and 1.00 μmol/L BPDE for 24 h to detect ERS and pyroptosis. After inhibition of ERS with 4-phenylbutyrate (4-PBA), pyroptosis of BEAS-2B cells was tested. The results showed that BPDE decreased the cell viability, changed the morphological structure of endoplasmic reticulum and increased the expression levels of GRP78 and p-PERK. After BPDE treatment, the cell membrane was damaged and incomplete under transmission electron microscope; Hoechst 33342/PI fluorescence staining showed that the number of PI-positive cells was enhanced. The expression levels of GSDMD-N, cleaved-caspase 1, and cleaved-IL-1β were elevated, and the expression levels of IL-1β, IL-18, and NLRP3 protein were improved. In BPDE combined with 4-PBA intervention group, the rate of PI-positive cells was reduced, the expression levels of GRP78, GSDMD-N, and cleaved-caspase 1 were decreased, and the expression levels of IL-1β, IL-18, and NLRP3 were decreased. In conclusion, BPDE could induce ERS and pyroptosis in BEAS-2B cells, and ERS may promote the occurrence of BPDE-induced pyroptosis.

Knocking down ETS Proto-oncogene 1 (ETS1) alleviates the pyroptosis of renal tubular epithelial cells in patients with acute kidney injury by regulating the NLR family pyrin domain containing 3 (NLRP3) transcription

Acute kidney injury (AKI) has a high mortality rate, but its pathogenesis remains unclear Lipopolysaccharide (LPS)-mediated renal tubular epithelial pyroptosis is involved in the pathogenesis of AKI. NLR family of pyrin domains containing 3 (NLRP3) plays an important role in pyroptosis. To further understand the transcriptional regulation mechanism of NLRP3, the peripheral blood of patients with AKI was analyzed in this study, showing that the levels of NLRP3 and cell pyroptosis in patients with AKI were significantly higher than those in normal controls. Furthermore, elevated levels of NLRP3 and cell pyroptosis were found in renal tubular epithelial cells after LPS treatment. Transcription factor ETS Proto-Oncogene 1 (ETS1) could bind to the upstream promoter transcription site of NLRP3 to transactivate NLRP3 in renal tubular epithelial cells. The cell pyroptosis level also decreased by knocking down ETS1. It is concluded that knocking down of ETS1 may reduce the renal tubular epithelial pyroptosis by regulating the transcription of NLRP3, thus relieving AKI. ETS1 is expected to be a molecular target for the treatment of AKI.

Tanshinone IIA down-regulates -transforming growth factor beta 1 to relieve renal tubular epithelial cell inflammation and pyroptosis caused by high glucose

Diabetic nephropathy (DN) is a microvascular disease caused by diabetes. Tanshinone IIA has been indicated to ameliorate streptozotocin-induced DN. This study explores the effect of tanshinone IIA on high glucose-induced renal tubular epithelial cell pyroptosis and inflammation. High glucose-stimulated HK-2 cells were used as the in-vitro model of DN and were treated with tanshinone IIA at concentrations of 1, 5, 10 μM for 24 h with the same doses of tolbutamide as the control. After tanshinone IIA treatment, HK-2 cells were transfected with pcDNA-transforming growth factor beta 1 (TGFB1) or sh-TGFB1 for 48 h. RT-qPCR was used to detect the mRNA levels of TNF-α, IL-6, IL-1β, and IL-18. Cell apoptosis and pyroptosis were detected by flow cytometry and cell immunofluorescence. Bioinformatics screening predicted that tanshinone IIA might be an effective component of Salvia miltiorrhiza Bunge (Labiatae) for the treatment of DN. Tanshinone IIA exerted a protective effect in the in-vitro model of DN by suppressing inflammation and pyroptosis via the TGFB1-dependent pathway. Tanshinone IIA inhibited high glucose-induced renal tubular epithelial cell inflammation and cell death through pyroptosis by regulating TGFB1, indicating the therapeutic potential of tanshinone IIA for DN treatment.

Cold Exposure Induces Intestinal Barrier Damage and Endoplasmic Reticulum Stress in the Colon via the SIRT1/Nrf2 Signaling Pathway

Ambient air temperature is a key factor affecting human health. Long-term exposure to a cold environment can cause various diseases, while the impact on the intestine, the organ which has the largest contact area with the external environment, cannot be ignored. In this study, we investigated the effect of chronic cold exposure on the colon and its preliminary mechanism of action. Mice were exposed to 4°C for 3 hours a day for 10 days. We found that cold exposure damaged the morphology and structure of the colon, destroyed the tight junctions of the colonic epithelial tissue, and promoted inflammation of the colon. At the same time, cold exposure also activated the unfolded protein response (UPR) in the colon and promoted apoptosis in intestinal epithelial cells. Chronic cold exposure induced oxidative stress in vivo, but also significantly enhanced the response of the Nrf2 pathway that promotes an anti-oxidant effect. Furthermore, we demonstrated that chronic cold exposure promoted p65 acetylation to aggravate the inflammatory response by inhibiting SIRT1. Similar results were observed following SIRT1 knock-down by shRNA in Caco-2 cells treated with Thapsigargin (Tg). Knock-down of SIRT1 promoted nuclear localization of Nrf2, and increased the level of Nrf2 acetylation. Taken together, our study indicates that cold exposure may aggravate endoplasmic reticulum stress and damage epithelial tight junctions in the colon by inhibiting SIRT1, which promotes nuclear localization of Nrf2 and induces an anti-oxidant response to maintain intestinal homeostasis. These findings suggest that SIRT1 is a potential target for regulating intestinal health under cold exposure conditions.

Downregulated XBP-1 Rescues Cerebral Ischemia/Reperfusion Injury-Induced Pyroptosis via the NLRP3/Caspase-1/GSDMD Axis

Ischemic stroke is a major condition that remains extremely problematic to treat. A cerebral reperfusion injury becomes apparent after an ischemic accident when reoxygenation of the afflicted area produces pathological side effects that are different than those induced by the initial oxygen and nutrient deprivation insult. Pyroptosis is a form of lytic programmed cell death that is distinct from apoptosis, which is initiated by inflammasomes and depends on the activation of Caspase-1. Then, Caspase-1 mobilizes the N-domain of gasdermin D (GSDMD), resulting in the release of cytokines, such as interleukin-1β (IL-1β) and interleukin-18 (IL-18). X-box binding protein l (XBP-1) is activated under endoplasmic reticulum (ER) stress to form an important transcription factor XBP-1 splicing (XBP-1s). The cerebral ischemia/reperfusion (CI/R) causes cytotoxicity, which correlates with the activation of splicing XBP-1 mRNA and NLRP3 (NOD-, LRR-, and pyrin domain-containing 3) inflammasomes, along with increases in the expression and secretion of proinflammatory cytokines and upregulation of pyroptosis-related genes in HT22 cells and in the middle cerebral artery occlusion (MCAO) rat model. However, whether XBP-1 plays a role in regulating pyroptosis involved in CI/R is still unknown. Our present study showed that behavior deficits, cerebral ischemic lesions, and neuronal death resulted from CI/R. CI/R increased the mRNA level of XBP-1s, NLRP3, IL-1β, and IL-18 and the expressions of XBP-1s, NLRP3, Caspase-1, GSDMD-N, IL-1β, and IL-18. We further repeated this process in HT22 cells and C8-B4 cells and found that OGD/R decreased cell viability and increased LDH release, XBP-1s, NLRP3, Caspase-1, GSDMD-N, IL-1β, IL-18, and especially the ratio of pyroptosis, which were reversed by Z-YVAD-FMK and downregulated XBP-1. Our results suggest that downregulated XBP-1 inhibited pyroptosis through the classical NLRP3/Caspase-1/GSDMD pathway to protect the neurons.

The Protective Effect of Pilose Antler Peptide on CUMS-Induced Depression Through AMPK/Sirt1/NF-κB/NLRP3-Mediated Pyroptosis

Background: Pilose antler peptide (PAP), prepared from the pilose antler of Cervus nippon Temminck, is widely used in traditional Chinese medicine (TCM) against various inflammatory disorders. TCM prescriptions containing pilose antler are often prescribed clinically to treat depression. However, the pharmacological mechanisms of how PAP, against inflammation, prevents and treats depression remain poorly understood.

Methods: PAP was identified by de novo sequencing and database searching. Then, behavioral tests were conducted to investigate the effect of PAP on CUMS-exposed mice. In parallel, Nissl staining and Golgi-Cox staining were used for exploring the effect of PAP on neural cells and dendritic spine density. Additionally, the expression of key proteins of the AMPK/Sirt1/NF-κB/NLRP3 pathway was analyzed by Western blot. Finally, the CUMS procedure was conducted for 6 weeks. At the 5th week, PAP and fluoxetine (Flu) were intragastrically treated for 2 weeks. The silencing information regulator-related enzyme 1 (Sirt1) inhibitor EX-527 and the AMP-activated protein kinase (AMPK) inhibitor dorsomorphin were employed to investigate the effects of Sirt1 and AMPK on PAP-mediated depression.

Results: PAP attenuated the behavior alteration caused by CUMS stimulation, decreased the number of neurons, and restored the dendritic spine density. PAP treatment effectively upregulated the expressions of p-AMPK and Sirt1 and suppressed the expressions of Ac-NF-κB, NLRP3, Ac-Caspase-1, GSDMD-N, Cleaved-IL-1β, and Cleaved-IL-18. Moreover, selectively inhibited Sirt1 and AMPK were able to compromise the therapeutic effect of PAP on depression.

Conclusion: The present work indicated that PAP has a protective effect on CUMS-induced depression. In addition, AMPK and Sirt1 played critical roles in the PAP-relieved depression. PAP might be a potential therapeutic option for treating depression.

Galangin attenuates cadmium-evoked nephrotoxicity: Targeting nucleotide-binding domain-like receptor pyrin domain containing 3 inflammasome, nuclear factor erythroid 2-related factor 2, and nuclear factor kappa B signaling

The kidney is highly vulnerable to cadmium-evoked oxidative injury. Galangin is a natural flavone with reported antioxidant properties. This study investigated the potential modulating activity of galangin against cadmium-induced nephrotoxicity and explored the underlining mechanisms. Western blot analysis, spectrophotometric, ELISA, and histopathological techniques were employed. The results revealed that galangin suppressed tubular injury and improved glomerular function in the cadmium-intoxicated rats as evidenced by downregulation of kidney injury molecule-1, serum creatinine, and blood urea nitrogen. Galangin reduced cadmium-evoked inflammatory response and oxidative stress as indicated by reduced levels of interleukin-1 beta and TNF-α, decreased DNA damage, and improved antioxidant potential of the renal tissues. Mechanistically, galangin suppressed the nucleotide-binding domain-like receptor pyrin domain containing 3 inflammasome and efficiently decreased caspase-1 activity in the cadmium-intoxicated rats. Equally important, it inhibited the cadmium-induced nuclear translocation of nuclear factor kappa B and upregulated nuclear factor erythroid 2-related factor 2 signaling. The results highlight the ability of galangin to attenuate cadmium-evoked nephrotoxicity and support its therapeutic implementation although clinical investigations are warranted.

XBP1 deficiency promotes hepatocyte pyroptosis by impairing mitophagy to activate mtDNA-cGAS-STING signaling in macrophages during acute liver injury

Hepatocellular cell death and macrophage proinflammatory activation contribute to the pathology of various liver diseases, during which XBP1 plays an important role. However, the function and mechanism of XBP1 in thioacetamide (TAA)-induced acute liver injury (ALI) remains unknown. Here, we investigated the effects of XBP1 inhibition on promoting hepatocellular pyroptosis to activate macrophage STING signaling during ALI. While both TAA- and LPS-induced ALI triggered XBP1 activation in hepatocytes, hepatocyte-specific XBP1 knockout mice exhibited exacerbated ALI with increased hepatocellular pyroptosis and enhanced macrophage STING activation. Mechanistically, mtDNA released from TAA-stressed hepatocytes could be engulfed by macrophages, further inducing macrophage STING activation in a cGAS- and dose-dependent manner. XBP1 deficiency increased ROS production to promote hepatocellular pyroptosis by activating NLRP3/caspase-1/GSDMD signaling, which facilitated the extracellular release of mtDNA. Moreover, impaired mitophagy was found in XBP1 deficient hepatocytes, which was reversed by PINK1 overexpression. Mitophagy restoration also inhibited macrophage STING activation and ALI in XBP1 deficient mice. Activation of XBP1-mediated hepatocellular mitophagy and pyroptosis and macrophage STING signaling pathway were observed in human livers with ALI. Collectively, these findings demonstrate that XBP1 deficiency promotes hepatocyte pyroptosis by impairing mitophagy to activate mtDNA/cGAS/STING signaling of macrophages, providing potential therapeutic targets for ALI.

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XBP1 deficiency promoted hepatocellular pyroptosis and extracellular mtDNA release to enhance macrophage STING activation.

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XBP1 deficiency promoted ROS/NLRP3/caspase-1/GSDMD-mediated hepatocyte pyroptosis by impairing mitophagy.

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Hepatocellular mitophagy and pyroptosis and macrophage STING activation were detected in human livers with ALI.

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Hepatocyte-specific XBP1 deficiency aggravated TAA-induced ALI in mice.

The Molecular Pathways of Pyroptosis in Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease seriously endangering human health, whose occurrence and development is related to many factors. Pyroptosis is a recently identified novel programmed cell death associated with an inflammatory response and involved in the formation and progression of AS by activating different signaling pathways. Protein modifications of the sirtuin family and microRNAs (miRNAs) can directly or indirectly affect pyroptosis-related molecules. It is important to link atherosclerosis, thermogenesis and molecular modifications. This article will systematically review the molecular pathways of pyroptosis in AS, which can provide a new perspective for AS prevention and treatment.