ASIC1a inhibits cell pyroptosis induced by acid-induced activation of rat hepatic stellate cells

ASIC1a regulates airway epithelial cell pyroptosis in acute lung injury by NLRP3-Caspase1-GSDMD pathway

BACKGROUND

Acidosis is the most common complication that seriously affects the prognosis of acute respiratory distress syndrome (ARDS). Acid-sensitive ion channel 1a (ASIC1a) is activated in acidic environments to regulate inflammatory process. However, the role of ASIC1a in ARDS is unclear.

METHODS

In this study, we examined the expression of ASIC1a in airway epithelial cells in an acidic environment. We then investigated whether blocking ASIC1a could inhibit pyroptosis of airway epithelial cells and the molecular mechanism. In the mouse acute lung injury (ALI) model, we observed the changes of lung histopathology, arterial blood gas and pyroptosis related indexes after ASIC1a inhibition. Bronchoalveolar lavage fluid (BALF) from patients with ARDS were collected to explore the expression level of ASIC1a in ARDS patients.

RESULTS

Inhibiting ASIC1a can reduce the airway epithelial cell pyroptosis induced by an extracellular acidic environment. ASIC1a can bind to PRKACA, and silencing ASIC1a and PRKACA can inhibit the occurrence of pyroptosis in airway epithelial cells. Compared with control group, arterial blood pH and PaO2 in ALI group were significantly reduced. The inflammation in the lungs is more intense, and the mRNA and protein of NLRP3, Caspase1 and GSDMD were increased, while ASIC1a specific blocker psalmotoxin-1 alleviated this phenomenon. The expression of ASIC1a in BALF of ARDS patients was significantly increased, especially in non-survival group.

CONCLUSION

Acidic micro-environment can induce the increased expression of ASIC1a, and inhibition of ASIC1a can alleviate the inflammation and airway epithelial cell pyroptosis in ARDS. ASIC1a may be a new target for the treatment of ARDS.

Ginsenoside Rb1 alleviates 3-MCPD-induced renal cell pyroptosis by activating mitophagy

Ginsenoside Rb1 (Gs-Rb1) is among the most significant effective pharmacological components in ginseng. 3-monochloropropane-1,2-diol (3-MCPD), a chloropropanol-like contaminant, is produced in the production of refined oils and thermal processing of food. Pyroptosis is a type of programmed cell death triggered by inflammasomes. Excessive pyroptosis causes kidney injury and inflammation. Previous studies have revealed that 3-MCPD induced pyroptosis in mice and NRK-52E cells. In the present study, we find that Gs-Rb1 attenuates 3-MCPD-induced renal cell pyroptosis by assaying GSDMD-N, caspase-1, IL-18, and IL-1β in mice and NRK-52E cells. In further mechanistic studies, we show that Gs-Rb1 removes damaged mitochondria via mitophagy and reduces intracellular reactive oxygen species (ROS) generation, therefore alleviating 3-MCPD-induced NOD-like receptor family pyrin domain containing 3 (NLRP3) activation and pyroptosis. The above results are further validated by the addition of autophagy inhibitor Chloroquine (CQ) and mitophagy inhibitor Cyclosporin A (CsA). Afterward, we explore how Gs-Rb1 activated mitophagy in vitro. We determine that Gs-Rb1 enhances the protein expression and nuclear translocation of Transcription factor EB (TFEB). However, silencing of the TFEB gene by small interfering RNA technology reverses the role of Gs-Rb1 in activating mitophagy. Therefore, we conclude that 3-MCPD damages mitochondria and leads to ROS accumulation, which causes NLRP3 activation and pyroptosis in ICR mice and NRK-52E cells, while Gs-Rb1 mitigates this phenomenon via the TFEB-mitophagy pathway. Our findings may provide new insights for understanding the molecular mechanisms by which Gs-Rb1 mitigates renal injury.

Gasdermin D: A Potential New Auxiliary Pan-Biomarker for the Detection and Diagnosis of Diseases

Pyroptosis is a form of programmed cell death mediated by gasdermins, particularly gasdermin D (GSDMD), which is widely expressed in tissues throughout the body. GSDMD belongs to the gasdermin family, which is expressed in a variety of cell types including epithelial cells and immune cells. It is involved in the regulation of anti-inflammatory responses, leading to its differential expression in a wide range of diseases. In this review, we provide an overview of the current understanding of the major activation mechanisms and effector pathways of GSDMD. Subsequently, we examine the importance and role of GSDMD in different diseases, highlighting its potential as a pan-biomarker. We specifically focus on the biological characteristics of GSDMD in several diseases and its promising role in diagnosis, early detection, and differential diagnosis. Furthermore, we discuss the application of GSDMD in predicting prognosis and monitoring treatment efficacy in cancer. This review proposes a new strategy to guide therapeutic decision-making and suggests potential directions for further research into GSDMD.

GAS5-inhibited hepatocyte pyroptosis contributes to hepatic stellate cell inactivation via microRNA-684 and AHR

Hepatocyte pyroptosis has been shown to be involved in liver damage progression. Previously, we found that growth arrest-specific 5 (GAS5) is a regulator of hepatic stellate cell (HSC) activation. However, whether GAS5 plays a role in hepatocyte pyroptosis remains unclear. In this study, reduced GAS5 was shown in CCl₄-treated mice and restoration of GAS5-inhibited liver fibrosis in vivo. Hepatocyte pyroptosis participated in the effects of GAS5-inhibited liver fibrosis, associated with reduced caspase-1, NLRP3, and IL-1β (hepatocyte pyroptosis markers). Notably, AHR expression, a suppressor of NLRP3, was enhanced by GAS5. Silencing AHR inhibited GAS5-mediated hepatocyte pyroptosis. GAS5 and AHR were targets of microRNA-684 (miR-684). In addition, the effects of GAS5 on hepatocyte pyroptosis could be inhibited by miR-684. Interestingly, GAS5-mediated hepatocyte pyroptosis contributed to HSC inactivation. In conclusion, we demonstrate that GAS5 inhibits hepatocyte pyroptosis and HSC activation, at least in part, via regulation of miR-684 and AHR.

ASIC1a involves the acid-mediated activation of pancreatic stellate cells associated with autophagy induction

The acidic tumor microenvironment (TME) of pancreatic cancer affects the physiological function of pancreatic stellate cells (PSCs), which in turn promotes cancer progression. Acid-sensing ion channel 1a (ASIC1a) is responsible for acidosis-related physiopathological processes. In this study, we investigated the effect of acid exposure on the activation and autophagy of PSCs, and the role of ASIC1a in these events. The results showed that acidic medium upregulated the expression of ASIC1a, induced PSCs activation and autophagy, which can be suppressed by inhibiting ASIC1a using PcTx1 or ASIC1a knockdown, suggesting that ASIC1a involves these two processes. In addition, the acid-induced activation of PSCs was impaired after the application of autophagy inhibitor alone or in combination with ASIC1a siRNA, meaning a connection between autophagy and activation. Collectively, our study provides evidence for the involvement of ASIC1a in the acid-caused PSCs activation, which may be associated with autophagy induction.

CaM/CaMKII mediates activation and proliferation of hepatic stellate cells regulated by ASIC1a

The activation of hepatic stellate cells (HSCs) is closely related to hepatic fibrosis and plays a key role in its occurrence and development. In the damaged liver, inhibition of the activation, proliferation, and clearance of HSCs is an important therapeutic strategy. However, the mechanism underlying the activation of HSCs is not completely clear. Acid-sensitive ion channel 1a (ASIC1a) is a cation channel activated by extracellular acid, which is responsible for the transport of Ca²⁺ and Na⁺ and participates in the activation of HSCs and the occurrence and development of many inflammatory diseases, suggesting that ASIC1a plays an important role in liver fibrosis. A previous study by the project team found that when the membrane channel protein ASIC1a was opened, intracellular Ca²⁺ levels increased, the expression of CaM/CaMKII in HSCs was high, and HSC was activated and proliferated. Therefore, we established an SD rat model of hepatic fibrosis and induced HSC-T6 activation by stimulating ASIC1a with acid in vitro. In vivo, CCl₄ was used to induce liver fibrosis in rats, and different doses of KN93 (0.5, 1, and 2 mg/kg/d) and colchicine (0.1 mg/kg/d) were administered. Eight weeks later, the activities of ALT and AST in serum were measured and hematoxylin-eosin and Masson staining in liver tissue, and immunohistochemistry analysis were performed in SD rats. The expressions of ASIC1a, α-SMA, Collagen-1, CaM, and CaMKII were detected. In vitro, we activated HSC-T6 cells by stimulating ASIC1a with acid. The results showed that inhibition of ASIC1a could improve acid-induced HSCs activation. In addition, CaM/CaMKII was expressed in HSC of rats with hepatic fibrosis regulated by ASIC1a. After blocking or silencing the expression of CaMKII, the fibrosis marker protein can be down-regulated. KN93 also reduced inflammation and improved the activation, proliferation and fibrosis of HSC. In summary, we concluded that CaM/CaMKII participates in ASIC1a regulation of the proliferation and activation of HSC and promotes the occurrence of liver fibrosis.

ASIC1a promotes hepatic stellate cell activation through the exosomal miR-301a-3p/BTG1 pathway

Activation of hepatic stellate cells (HSCs) is a key cause of liver fibrosis. However, the mechanisms leading to the activation of HSCs are not fully understood. In the pathological process, acid-sensing ion channel 1a (ASIC1a) is widely involved in the development of inflammatory diseases, suggesting that ASIC1a may play an important role in liver fibrosis. We found that in an acidic environment, ASIC1a leads to HSC-T6 cell activation. Meanwhile, exosomes produced by activated HSC-T6 cells (HSC-EXOs) can be reabsorbed by quiescent HSC-T6 cells to promote their activation. Exosomes mainly carry miRNAs involved in intercellular information exchange. We performed exosome miRNA whole transcriptome sequencing. The results indicated that the acidic environment could alter the miRNA expression profile in the exosomes of HSC-T6 cells. Further studies revealed that ASIC1a promotes the activation of HSCs by regulating miR-301a-3p targeting B-cell translocation gene 1 (BTG1). In conclusion, our study found that ASIC1a may affect HSC activation through the exosomal miR-301a-3p/BTG1 axis, and inhibiting ASIC1a may be a promising treatment strategy for liver fibrosis.

Apigenin alleviated PA-induced pyroptosis by activating autophagy in hepatocytes

Apigenin is a kind of natural flavonoid that abundantly exists in fruits and vegetables. Pyroptosis is a new, pro-inflammatory type of programmed necrosis cell death, and the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the key molecule to induce pyroptosis. Excessive hepatic pyroptosis results in liver injury. In the study, we found for the first time that apigenin could alleviate palmitic acid (PA)-induced NLRP3 inflammasome activation and pyroptosis in HepG2 cells and primary mouse hepatic cells. Meanwhile, apigenin could promote the autophagy of hepatocytes. When the autophagy inhibitor chloroquine (CQ) was added, the data showed that the recovery effect of apigenin on PA-induced pyroptosis was weakened, indicating that apigenin could alleviate PA-induced pyroptosis by activating autophagy. Further mechanistic studies showed that apigenin regulated the NLRP3 inflammasome through two ways, so as to alleviate PA-induced pyroptosis. On the one hand, apigenin eliminated damaged mitochondria by activating autophagy, thereby clearing reactive oxygen species (ROS) production and inhibiting the activation of the NLRP3 inflammasome, and on the other hand, activation of autophagy could directly degrade the NLRP3 inflammasome. Our study provides a new idea and target for the use of functional factors in food to alleviate liver injury.

Multi-faceted role of pyroptosis mediated by inflammasome in liver fibrosis

Liver fibrosis is a reversible pathological overreaction during the self-repair of liver injuries, and it is the common period of chronic liver diseases induced by different pathogenesis progress into cirrhosis and even hepatocellular carcinoma. Pyroptosis, a novel form of programmed cell death, is reported to take part in the pathogenesis and progression of acute or chronic liver diseases and liver fibrosis. Caspase-1 dependent canonical pathway and caspase-4/-5/-11 mediated noncanonical pathway are the two signalling pathways to induce pyroptosis. The activation of inflammasomes under the stimulation of pathogenic microorganisms and danger signals can initiate the pyroptotic pathway and release large amounts of proinflammatory and profibrotic cytokines. This article comprehensively summarizes recent researches focused on the mechanism of pyroptosis and its role in major hepatic cells, which can provide potential therapeutic strategies for liver fibrosis.