Shuang Guan

Bisphenol A (BPA), an organic compound widely found in food packaging materials, is inevitably released into the food and beverages. BPA has been confirmed to be hepatotoxic, however, the precise mechanism remains unclear. In this study, we demonstrated that lysosomal membrane permeabilization (LMP) mediates BPA-induced liver injury. Further mechanistic investigation revealed that BPA resulted in cathepsin B (CTSB) release and iron efflux by triggering LMP, ultimately inducing lysosomal-dependent pyroptosis and ferroptosis. Furthermore, mitochondrial reactive oxygen species (mtROS) were identified as the trigger for BPA-induced LMP. BPA elicited mtROS overproduction by disrupting mitochondrial quality control, thereby inducing LMP. In conclusion, we demonstrated that BPA caused CTSB release and lysosomal iron efflux via the mtROS-mediated LMP, which ultimately resulted in pyroptosis and ferroptosis. Our study revealed that the mtROS/LMP axis may be a common pathway for lysosomal-dependent pyroptosis and ferroptosis, providing novel mechanistic insights into BPA-induced hepatotoxicity.

Large lipid droplets (LDs) resist lipophagy-mediated degradation due to steric hindrance, contributing to hepatic lipid accumulation in nonalcoholic fatty liver disease (NAFLD). Apigenin (API), a flavonoid abundant in fruits and vegetables, improves NAFLD, but its mechanism remains unclear. In this study, we found that API notably reduced LD size, thereby facilitating subsequent lipophagy. Transcriptomic analysis and validation revealed that API downregulated cell death-inducing DFF45-like effector C (CIDEC), a key promoter of LD fusion. Mechanistically, API suppressed CIDEC transcription by inhibiting four and a half LIM domains protein 2 (FHL2)-dependent nuclear translocation of peroxisome proliferator-activated receptor γ (PPARγ). Network pharmacology identified the Phosphatidylinositol 3-Kinase-Protein Kinase B (PI3K-AKT) pathway as a potential regulatory pathway. SC79-mediated AKT activation reversed API-induced LD size reduction and lipophagy enhancement. Collectively, API suppressed CIDEC expression through the AKT-FHL2/PPARγ pathway, thereby limiting LD fusion and creating better conditions for lipophagy, providing novel dietary intervention strategies for NAFLD.

Microplastics (MPs), as emerging food contaminants, have been established to exert adverse effects on the liver. However, the precise toxicological mechanisms remain elusive. Our results demonstrated that MPs triggered mitochondrial dysfunction and mitochondrial ROS (mtROS) accumulation, which subsequently activated NLRP3/caspase-1/GSDMD-N-dependent pyroptosis in hepatocytes. Notably, beyond its canonical translocation to the plasma membrane, GSDMD-N was observed to form pores on the mitochondrial outer membrane, exacerbating mitochondrial damage. The mitochondrial GSDMD-N pores amplified mtROS overproduction, triggering lysosomal membrane permeabilization (LMP) and facilitating lysosomal iron efflux, which ultimately initiated ferroptosis. Concurrently, mitochondrial GSDMD-N mediated mitochondrial intrinsic apoptosis by promoting cytochrome c release and caspase-3 activation. Collectively, our findings revealed that MPs induced GSDMD-N activation and its mitochondrial translocation, which in turn initiated pyroptosis, ferroptosis, and apoptosis in hepatocytes. This study provided novel mechanistic insights into MPs-induced hepatotoxicity, identifying GSDMD-N as a potential central hub coordinating multiple cell death modalities.

Benzo[a]pyrene (BaP), a ubiquitous polycyclic aromatic hydrocarbon (PAH) present in the environment and food chain, causes severe hepatotoxicity. However, the integrated cell death mechanisms underlying BaP-induced liver injury remain poorly defined. Here, we identify PANoptosis, an integrated cell death program encompassing pyroptosis, apoptosis, and necroptosis, as a central mechanism driving BaP-induced liver injury. In vivo and in vitro experiments revealed that BaP activates pyroptosis via the ROS/NLRP3/Caspase-1/GSDMD axis and necroptosis through the ROS/RIPK1/RIPK3/p-MLKL cascade. Remarkably, we uncovered that the pyroptosis executor GSDMD-N and the necroptosis effector p-MLKL translocated from the plasma membrane to mitochondria, inducing mitochondrial outer membrane permeabilization, cytochrome c release, and subsequent caspase-dependent apoptosis. Silencing either GSDMD or MLKL restored mitochondrial integrity and suppressed PANoptosis. Our work expands the conceptual framework of environmental toxicology by revealing how BaP orchestrates integrated cell death through mitochondrial targeting, offering mechanistic insight and potential therapeutic targets for PAH-induced liver injury.

Alcohol, one of the most widely popular and consumed beverages worldwide, often leads to acute alcoholic liver injury (AALI) when excessively consumed within a short timeframe. It can further induce alcoholic hepatitis, posing a serious risk to human health and public health safety. Pyroptosis, a typical mode of programmed cell death, is closely associated with the body's inflammatory response and plays a central role in AALI. However, the role of yogurt in acute alcohol-induced pyroptosis and inflammation is unclear. In this study, we found that yogurt and its metabolite d-lactate effectively mitigate alcohol-induced liver damage in mice, reducing hepatocyte pyroptosis and attenuating the inflammatory response. For the specific mechanism, further studies have shown that yogurt may inhibit autophagy through its substance d-lactate, leading to the accumulation of P62 protein in cells. This accumulation subsequently triggers the activation of Nrf2 through nonclassical pathways. Nrf2 translocates to the nucleus to play its antioxidant role, thereby reducing intracellular reactive oxygen species levels, inhibiting the activation of the alcohol-induced NLRP3 inflammasome, and ultimately alleviating pyroptosis and inflammation. Overall, this study reveals the potential protective effect of yogurt and its metabolite d-lactate in alleviating AALI, offering new insights and scientific basis for yogurt as a dietary strategy to improve AALI.

Lactoferrin (LF) is an important component of dairy products. Studies have shown that LF has a protective effect against liver injury, but the mechanism of action remains incompletely understood. Lipopolysaccharide (LPS), a key component of bacterial endotoxins, can lead to liver injury when exposure is excessive. Necroptosis is a newly identified type of programmed cell death characterized by cell swelling, rupture, and necrosis, and its excessive activation contributes to tissue damage. In this study, we demonstrated that LF alleviates LPS-induced oxidative stress and necroptosis in liver cells by modulating the ROS-RIPK1-RIPK3 pathway. In further mechanistic studies, we discovered that LF promotes mitophagy in liver cells to promptly remove damaged mitochondria caused by LPS, thereby reducing the increase in reactive oxygen species (ROS) levels associated with damaged mitochondria and alleviating oxidative stress and necrosis. To validate our findings, we used mitophagy inhibitor cyclosporin A (CsA) as a negative control, and the results confirmed our findings. These results provide novel strategies and insights into utilizing LF to alleviate LPS-induced liver injury.

Whey protein is widely recognized as a high-quality protein source, primarily derived from dairy products. This type of protein is valued not only for its remarkable nutritional benefits but also for its substantial antioxidant properties and its capacity to reduce inflammation. Previous studies have demonstrated that whey protein hydrolysate (WPH) is effective in both the prevention and treatment of liver injury caused by acetaminophen (APAP) overdose. Pyroptosis is a form of programmed cell death that significantly contributes to liver damage induced by APAP, and it is associated with increased levels of oxidative stress and inflammation. However, the specific mechanisms by which WPH influences pyroptosis remain not fully understood. The present study observed a significant alleviation of APAP-induced hepatocyte injury by WPH, alongside a reduction in the release of pro-inflammatory factors, specifically interleukin-1β (IL-1β) and interleukin-18 (IL-18). Moreover, the expression levels of pyroptosis-related proteins, including NOD-like receptor family pyrin domain containing 3 (NLRP3), the N-terminal domain of gasdermin D (GSDMD-N), and cleaved caspase-1, were significantly reduced following treatment with WPH. In the subsequent phase of our research, we examined the levels of reactive oxygen species (ROS) and the expression of cathepsin B (CTSB) in hepatocytes. Increased levels of ROS resulted in heightened permeability of lysosomal membranes, which led to the release of CTSB into the cytosol. The liberated CTSB subsequently activated the NLRP3 inflammasome, thereby promoting pyroptosis. Our results revealed that WPH reduced the accumulation of ROS in hepatocytes and inhibited the release of CTSB. In subsequent mechanistic studies, we found that WPH upregulated the expression of Parkin, PTEN-induced putative kinase 1 (PINK1), and microtubule-associated protein 1 light chain 3 β (LC3), while downregulating the expression of P62 to activate mitophagy. We further validated these results by introducing the mitophagy inhibitor Cyclosporin A (CsA). In conclusion, our findings suggest that WPH may enhance the removal of damaged mitochondria through the activation of the mitophagy mechanism. This process may lead to a reduction in intracellular ROS accumulation and mitigate APAP-induced activation of the NLRP3 inflammasome and pyroptosis.

Apigenin (4',5,7-trihydroxyflavone) is a significant natural flavonoid compound that is abundantly found in various fruits and vegetables. It has been demonstrated to alleviate nonalcoholic fatty liver disease and exhibit lipid-lowering effects. However, its impact on lipid droplet (LD) degradation in hepatocytes remains unclear. LDs, coated by perilipins (PLINs), are selectively exposed and degraded through chaperone-mediated autophagy (CMA), specifically targeting PLIN2 and PLIN3 to enhance lipolysis and lipophagy. Lysosome-associated membrane protein type 2A (LAMP-2A) is the rate-limiting component of CMA. We found that apigenin-alleviated high-fat diet induced LD accumulation in hepatocytes by promoting CMA. The data indicated that apigenin could improve the expression of LAMP-2A, while downregulating the expression of PLIN2 and PLIN3, reduce the volume and size of LDs. AMP-activated protein kinase (AMPK) plays a crucial role in activating nuclear factor erythroid 2-related factor 2 (Nrf2), in turn, regulating the transcription of LAMP-2A. In our study, we found that the activation of AMPK induced by apigenin promotes PLIN2 phosphorylation and Nrf2 nuclear translocation, thus subsequently enhancing the activity of CMA. This accelerated the degradation of PLINs, ultimately facilitating LD degradation. Overall, our study offered valuable insights into the mechanism of apigenin in the degradation of LDs.