DMF-Activated Nrf2 Ameliorates Palmitic Acid Toxicity While Potentiates Ferroptosis Mediated Cell Death: Protective Role of the NO-Donor S-Nitroso-N-Acetylcysteine

Maresin1 Inhibits Ferroptosis via the Nrf2/SLC7A11/GPX4 Pathway to Protect Against Sepsis-Induced Acute Liver Injury

Purpose

Maresin 1 (MaR1) is a specialized pro-resolving mediator with anti-inflammatory properties that promotes tissue repair. This study aims to investigate the molecular involvement of MaR1 in protecting against sepsis-induced acute liver injury (SI-ALI).

Methods

In vivo, a murine SI-ALI model was established using the cecal ligation and puncture (CLP) paradigm, providing a system in which the mechanistic functions of MaR1 could be tested. These analyses were supplemented through in vitro assays in which Alpha mouse liver 12 (AML12) hepatocytes and RAW264.7 macrophages were co-cultured in a Transwell system, with lipopolysaccharide (LPS) stimulation being used to establish a sepsis model. These cells were treated with MaR1 and/or nuclear factor erythroid 2-related factor 2 (Nrf2)inhibitor, while lentiviral transduction was used to knock down Nrf2 within AML12 cells. Hepatic pathological damage was assessed through hematoxylin and eosin staining. Lipid peroxidation-related analyses were conducted through the use of thiobarbituric acid, ferrous ions, glutathione, and appropriate fluorescent probes for reactive oxygen species detection. Liver enzymes and inflammatory mediators were quantified using appropriate Enzyme-Linked Immunosorbent Assays (ELISAs). Protein concentrations were evaluated via Western blot analysis.

Results

The presence of ferroptosis in SI-ALI. MaR1 was found to proficiently suppress ferroptosis in SI-ALI. Mechanistically, MaR1 enhanced Nrf2 expression in AML12 hepatocytes, while the Nrf2 inhibitor ML-385 or Nrf2 siRNA mitigated MaR1's regulatory influence on ferroptosis. Meanwhile, the expressions of the downstream genes solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) diminished, suggesting that MaR1 has a protective function via activating the Nrf2/SLC7A11/GPX4 pathway to mitigate ferroptosis in septic liver injury.

Conclusion

The results indicate that MaR1 mitigates SI-ALI via stimulating the Nrf2/SLC7A11/GPX4 pathway to suppress ferroptosis. Moreover, it offers significant potential as a new agent for the prevention of SI-ALI.

Unveiling Smyd-2's Role in Cytoplasmic Nrf-2 Sequestration and Ferroptosis Induction in Hippocampal Neurons After Cerebral Ischemia/Reperfusion

SET and MYND Domain-Containing 2 (Smyd-2), a specific protein lysine methyltransferase (PKMT), influences both histones and non-histones. Its role in cerebral ischemia/reperfusion (CIR), particularly in ferroptosis-a regulated form of cell death driven by lipid peroxidation-remains poorly understood. This study identifies the expression of Smyd-2 in the brain and investigates its relationship with neuronal programmed cell death (PCD). We specifically investigated how Smyd-2 regulates ferroptosis in CIR through its interaction with the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway. Smyd-2 knockout protects HT-22 cells from Erastin-induced ferroptosis but not TNF-α + Smac-mimetic-induced apoptosis/necroptosis. This neuroprotective effect of Smyd-2 knockout in HT-22 cells after Oxygen-Glucose Deprivation/Reperfusion (OGD/R) was reversed by Erastin. Smyd-2 knockout in HT-22 cells shows neuroprotection primarily via the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway, despite the concurrent upregulation of Smyd-2 and Nrf-2 observed in both the middle cerebral artery occlusion (MCAO) and OGD/R models. Interestingly, vivo experiments demonstrated that Smyd-2 knockout significantly reduced ferroptosis and lipid peroxidation in hippocampal neurons following CIR. Moreover, the Nrf-2 inhibitor ML-385 abolished the neuroprotective effects of Smyd-2 knockout, confirming the pivotal role of Nrf-2 in ferroptosis regulation. Cycloheximide (CHX) fails to reduce Nrf-2 expression in Smyd-2 knockout HT-22 cells. Smyd-2 knockout suppresses Nrf-2 lysine methylation, thereby promoting the Nrf-2/Keap-1 pathway without affecting the PKC-δ/Nrf-2 pathway. Conversely, Smyd-2 overexpression disrupts Nrf-2 nuclear translocation, exacerbating ferroptosis and oxidative stress, highlighting its dual regulatory role. This study underscores Smyd-2's potential for ischemic stroke treatment by disrupting the Smyd-2/Nrf-2-driven antioxidant capacity, leading to hippocampal neuronal ferroptosis. By clarifying the intricate interplay between ferroptosis and oxidative stress via the Nrf-2/Keap-1 pathway, our findings provide new insights into the molecular mechanisms of CIR and identify Smyd-2 as a promising therapeutic target.

Dimethyl fumarate restores Ca2+ dyshomeostasis through activation of the SIRT1 signal to treat nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by an excessive lipid accumulation in the liver, with a global prevalence of approximately 25 %. While early-stage steatosis is reversible and can be intervened upon, it has the potential to progress to some serious complications, including cirrhosis and even liver cancer. Dimethyl fumarate (DMF), a derivative of fumaric acid shows promise in intervening in certain diseases. However, the precise effect and underlying mechanism of DMF on hepatic steatosis remain unclear. In this study, we demonstrated that DMF mitigates hepatic steatosis in mice subjected to high-fat/high-cholesterol (HFHC) diets. Meanwhile, our in vivo and in vitro results showed that DMF relieves lipid accumulation, oxidative stress, and endoplasmic reticulum (ER) stress. Mechanically, our findings revealed that the effect of DMF on reducing lipid accumulation is linked to the restoration of Ca2+ homeostasis. Furthermore, we found that activation of the SIRT1 signal by DMF plays an important role in correcting the mishandling of the Ca2+ signal, and knockdown of SIRT1 expression reverses the beneficial role of DMF PA-incubated AML12 cells. In conclusion, our results suggested DMF's amelioration of hepatic steatosis is related to the activation of SIRT1-mediated Ca2+ signaling.

Metformin improves nonalcoholic fatty liver disease in db/db mice by inhibiting ferroptosis

Nonalcoholic fatty liver disease (NAFLD) is the primary complication of type 2 diabetes (T2DM)-related liver disease, lacking effective treatment options. Metformin (Met), a widely prescribed anti-hyperglycemic medication, has been found to protect against NAFLD. Ferroptosis, a newly discovered form of cell death, is associated with the development of NAFLD. Despite this association, the extent of Met's protective effects on NAFLD through the modulation of ferroptosis has yet to be thoroughly investigated. In the present study, the administration of erastin or Ras-selective lethal 3 (RSL3), both known ferroptosis inducers, resulted in elevated cell mortality and reduced cell viability in AML12 hepatocytes. Notably, Met treatment demonstrated the capacity to mitigate these effects. Furthermore, we observed increased ferroptosis levels in both AML12 hepatocytes treated with palmitate and oleate (PA/OA) and in the liver tissue of db/db mice. Met treatment demonstrated significant reductions in iron accumulation and lipid-related reactive oxygen species production, simultaneously elevating the glutathione/glutathione disulfide ratio in both PA/OA-treated AML12 hepatocytes and the liver tissue of db/db mice. Interestingly, the anti-ferroptosis effects of Met were significantly reversed with the administration of RSL3, both in vitro and in vivo. Mechanistically, Met treatment regulated the glutathione peroxidase 4/solute carrier family 7 member 11/acyl-CoA synthetase long-chain family member 4 axis to alleviate ferroptosis in NAFLD hepatocytes. Overall, our findings highlight the crucial role of ferroptosis in the development of T2DM-related NAFLD and underscore the potential of Met in modulating key factors associated with ferroptosis in the context of NAFLD.

Treatment of liver fibrosis: Past, current, and future

Liver fibrosis accompanies the progression of chronic liver diseases independent of etiologies, such as hepatitis viral infection, alcohol consumption, and metabolic-associated fatty liver disease. It is commonly associated with liver injury, inflammation, and cell death. Liver fibrosis is characterized by abnormal accumulation of extracellular matrix components that are expressed by liver myofibroblasts such as collagens and alpha-smooth actin proteins. Activated hepatic stellate cells contribute to the major population of myofibroblasts. Many treatments for liver fibrosis have been investigated in clinical trials, including dietary supplementation (e.g., vitamin C), biological treatment (e.g., simtuzumab), drug (e.g., pegbelfermin and natural herbs), genetic regulation (e.g., non-coding RNAs), and transplantation of stem cells (e.g., hematopoietic stem cells). However, none of these treatments has been approved by Food and Drug Administration. The treatment efficacy can be evaluated by histological staining methods, imaging methods, and serum biomarkers, as well as fibrosis scoring systems, such as fibrosis-4 index, aspartate aminotransferase to platelet ratio, and non-alcoholic fatty liver disease fibrosis score. Furthermore, the reverse of liver fibrosis is slowly and frequently impossible for advanced fibrosis or cirrhosis. To avoid the life-threatening stage of liver fibrosis, anti-fibrotic treatments, especially for combined behavior prevention, biological treatment, drugs or herb medicines, and dietary regulation are needed. This review summarizes the past studies and current and future treatments for liver fibrosis.