Wild Bitter Melon Extract Regulates LPS-Induced Hepatic Stellate Cell Activation, Inflammation, Endoplasmic Reticulum Stress, and Ferroptosis

Momordica charantia Bioactive Components: Hypoglycemic and Hypolipidemic Benefits Through Gut Health Modulation

Momordica charantia (MC), a member of the Cucurbitaceae family, is well known for its pharmacological activities that exhibit hypoglycemic and hypolipidemic properties. These properties are largely because of its abundant bioactive compounds and phytochemicals. Over the years, numerous studies have confirmed the regulatory effects of MC extract on glycolipid metabolism. However, there is a lack of comprehensive reviews on newly discovered MC-related components, such as insulin receptor-binding protein-19, adMc1, and MC protein-30 and triterpenoids 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al, and the role of MC in gut microbiota and bitter taste receptors. This review offers an up-to-date overview of the recently reported chemical compositions of MC, including polysaccharides, saponins, polyphenolics, peptides, and their beneficial effects. It also provides the latest updates on the role of MC in the regulation of gut microbiota and bitter taste receptor signaling pathways. As a result, this review will serve as a theoretical basis for potential applications in the creation or modification of MC-based nutrient supplements.

Recent progress in the effect of ferroptosis of HSCs on the development of liver fibrosis

Fibrosis is a common pathological process that must take place for multiple chronic liver diseases to develop into cirrhosis and liver cancer. Liver fibrosis (LF) is regulated by various cytokines and signaling pathways in its occurrence and development. Ferroptosis is an important mode of cell death caused by iron-dependent oxidative damage and is regulated by iron metabolism and lipid peroxidation signaling pathways. In recent years, numerous studies have shown that ferroptosis is closely related to LF. As the main material secreted by the extracellular matrix, hepatic stellate cells (HSCs) are a general concern in the development of LF. Therefore, targeting HSC ferroptosis against LF is crucial. This review describes the current status of treating LF by inducing HSC ferroptosis that would aid studies in better understanding the current knowledge on ferroptosis in HSCs and the future research direction in this field.

9-POHSA prevents NF-kB activation and ameliorates LPS-induced inflammation in rat hepatocytes

Liver inflammation has become increasingly prevalent in recent years, leading to the development of diseases like hepatitis, alcoholic liver disease, and fatty liver disease. One factor that has been linked to liver inflammation is increased levels of lipopolysaccharides (LPS), which can be caused by poor diets and sedentary lifestyles that contribute to liver inflammation. There is promising research on a new class of lipids called fatty acid esters of hydroxy fatty acids (FAHFAs), which have been shown to potentiate insulin release and exert an anti-inflammatory effect. Specifically, one type of FAHFA called 9-POHSA (palmitoleic acid ester of 9-hydroxy stearic acid) has been studied for its potential to attenuate inflammation-related indexes induced by LPS in hepatocytes, which play a critical role in the progression of liver inflammation. This study found that following LPS treatment, tumor necrosis factor- α, interleukin-6, and connective tissue growth factor (CTGF) were upregulated and increased cell migration, but 9-POHSA pre-treatment attenuated the upregulation of these markers and prevented cell migration induced by LPS. Using flowcytometry analysis, intracellular reactive oxygen species (ROS) was found to be responsible for CTGF upregulation. In addition, the effects of 9-POHSA were likely associated with its inhibition of the activation of the NF-kB. These results suggest that 9-POHSA has potential as a therapy for liver inflammation and fibrosis by attenuating inflammation-related indexes induced by LPS in hepatocytes. This study provides important insight into the mechanisms of liver inflammation and the potential for new treatments to address liver diseases.

Zooming in and out of ferroptosis in human disease

Ferroptosis is defined as an iron-dependent regulated form of cell death driven by lipid peroxidation. In the past decade, it has been implicated in the pathogenesis of various diseases that together involve almost every organ of the body, including various cancers, neurodegenerative diseases, cardiovascular diseases, lung diseases, liver diseases, kidney diseases, endocrine metabolic diseases, iron-overload-related diseases, orthopedic diseases and autoimmune diseases. Understanding the underlying molecular mechanisms of ferroptosis and its regulatory pathways could provide additional strategies for the management of these disease conditions. Indeed, there are an expanding number of studies suggesting that ferroptosis serves as a bona-fide target for the prevention and treatment of these diseases in relevant pre-clinical models. In this review, we summarize the progress in the research into ferroptosis and its regulatory mechanisms in human disease, while providing evidence in support of ferroptosis as a target for the treatment of these diseases. We also discuss our perspectives on the future directions in the targeting of ferroptosis in human disease.

Downregulation of miR-221-3p promotes the ferroptosis in gastric cancer cells via upregulation of ATF3 to mediate the transcription inhibition of GPX4 and HRD1

BACKGROUND

Gastric cancer (GC) is an aggressive gastrointestinal tumor. MiRNAs participate in the tumorigenesis of GC. Nevertheless, the function of miR-221-3p in GC remains largely unknown.

METHODS

RNA levels were assessed by RT-qPCR. Western blot was performed to test the protein levels. The relation between miR-221-3p and ATF3 was investigated by dual-luciferase reporter assay. ChIP and dual-luciferase reporter assay were applied to assess the interaction between ATF3 and HRD1 or GPX4. Meanwhile, cell proliferation was investigated by CCK8 and colony formation assay. The content of erastin-induced Fe²⁺ was investigated by iron assay kit. Erastin-induced lipid ROS level was assessed by C11-BODIPY 581/591. Co-immunoprecipitation was used to detect the interaction between HRD1 and ACSL4. In addition, xenograft mice model was established to detect the effect of miR-221-3p in GC.

RESULTS

Depletion of miR-221-3p greatly attenuated GC cell proliferation through promoting ferroptosis. Meanwhile, ATF3 was downregulated in GC, and it was identified to be the downstream mRNA of miR-221-3p. MiR-221-3p downregulation could promoted the ferroptosis in GC cells through upregulation of ATF3. HRD1 mediates ubiquitination and degradation of ACSL4 to inhibit ferroptosis. ATF3 upregulation could reduce GC cell proliferation via downregulating the transcription of GPX4 and HRD1. Furthermore, downregulation of miR-221-3p markedly attenuated the growth of GC in mice.

CONCLUSION

HRD1 mediates ubiquitination and degradation of ACSL4 to inhibit ferroptosis. MiR-221-3p depletion upregulates the ferroptosis in GC cells via upregulation of ATF3 to mediate the transcription inhibition of GPX4 and HRD1. Our study might provide a novel target for GC treatment.

Iron as a therapeutic target in chronic liver disease

It was clearly realized more than 50 years ago that iron deposition in the liver may be a critical factor in the development and progression of liver disease. The recent clarification of ferroptosis as a specific form of regulated hepatocyte death different from apoptosis and the description of ferritinophagy as a specific variation of autophagy prompted detailed investigations on the association of iron and the liver. In this review, we will present a brief discussion of iron absorption and handling by the liver with emphasis on the role of liver macrophages and the significance of the iron regulators hepcidin, transferrin, and ferritin in iron homeostasis. The regulation of ferroptosis by endogenous and exogenous mod-ulators will be examined. Furthermore, the involvement of iron and ferroptosis in various liver diseases including alcoholic and non-alcoholic liver disease, chronic hepatitis B and C, liver fibrosis, and hepatocellular carcinoma (HCC) will be analyzed. Finally, experimental and clinical results following interventions to reduce iron deposition and the promising manipulation of ferroptosis will be presented. Most liver diseases will be benefited by ferroptosis inhibition using exogenous inhibitors with the notable exception of HCC, where induction of ferroptosis is the desired effect. Current evidence mostly stems from in vitro and in vivo experimental studies and the need for well-designed future clinical trials is warranted.

Pharmacological modulation of ferroptosis as a therapeutic target for liver fibrosis

Liver fibrosis, which is characterized by the excessive deposition of extracellular matrix (ECM) materials (primarily fibrillar collagen-I), is an abnormal repair reaction and pathological outcome of chronic liver diseases caused by alcohol abuse, non-alcoholic fatty liver disease, and chronic hepatitis B and C virus infections. Liver fibrosis often progresses to liver cirrhosis and hepatocellular carcinoma. Ferroptosis, characterized by lipid peroxidation, is a form of iron-dependent non-apoptotic cell death, and recent studies have reported that ferroptosis contribute to the development of liver fibrosis. Moreover, several agents have demonstrated therapeutic effects in experimental liver fibrosis models by inducing hepatic stellate cell (HSCs) ferroptosis. This review delineates the specific mechanism by which ferroptosis contributes to the development of liver fibrosis. Specifically, we focused on the different types of therapeutic agents that can induce HSCs ferroptosis and summarize their pharmacological effectiveness for liver fibrosis treatment. We suggest that HSCs ferroptosis may be a potential useful target of novel therapies for preventing and treating liver fibrosis.

Endoplasmic reticulum stress-mediated cell death in liver injury

The endoplasmic reticulum is an important intracellular organelle that plays an important role in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) and unfolded protein response (UPR) are induced when the body is exposed to adverse external stimuli. It has been established that ERS can induce different cell death modes, including autophagy, apoptosis, ferroptosis, and pyroptosis, through three major transmembrane receptors on the ER membrane, including inositol requirement enzyme 1α, protein kinase-like endoplasmic reticulum kinase and activating transcription factor 6. These different modes of cell death play an important role in the occurrence and development of various diseases, such as neurodegenerative diseases, inflammation, metabolic diseases, and liver injury. As the largest metabolic organ, the liver is rich in enzymes, carries out different functions such as metabolism and secretion, and is the body's main site of protein synthesis. Accordingly, a well-developed endoplasmic reticulum system is present in hepatocytes to help the liver perform its physiological functions. Current evidence suggests that ERS is closely related to different stages of liver injury, and the death of hepatocytes caused by ERS may be key in liver injury. In addition, an increasing body of evidence suggests that modulating ERS has great potential for treating the liver injury. This article provided a comprehensive overview of the relationship between ERS and four types of cell death. Moreover, we discussed the mechanism of ERS and UPR in different liver injuries and their potential therapeutic strategies.

Ferroptosis in Chronic Liver Diseases: Opportunities and Challenges

Ferroptosis, an iron-dependent non-apoptotic cell death characterized by lipid peroxidation, is a cell death pathway discovered in recent years. Ferroptosis plays an important role in tumors, ischemia-reperfusion injury, neurological diseases, blood diseases, etc. Recent studies have shown the importance of ferroptosis in chronic liver disease. This article summarizes the pathological mechanisms of ferroptosis involved in System Xc−, iron metabolism, lipid metabolism, and some GPX4-independent pathways, and the latest research on ferroptosis in chronic liver diseases such as alcoholic liver disease, non-alcoholic fatty liver disease, liver fibrosis, hepatocellular carcinoma. In addition, the current bottleneck issues that restrict the research on ferroptosis are proposed to provide ideas and strategies for exploring new therapeutic targets for chronic liver diseases.

Role of Ferroptosis in Fibrotic Diseases

Ferroptosis is a unique and pervasive form of regulated cell death driven by iron-dependent phospholipid peroxidation. It results from disturbed cellular metabolism and imbalanced redox homeostasis and is regulated by various cellular metabolic pathways. Recent preclinical studies have revealed that ferroptosis may be an attractive therapeutic target in fibrotic diseases, such as liver fibrosis, pulmonary fibrosis, kidney fibrosis, and myocardial fibrosis. This review summarizes the latest knowledge on the regulatory mechanism of ferroptosis and its roles in fibrotic diseases. These updates may provide a novel perspective for the treatment of fibrotic diseases as well as future research.

The Regulatory Roles of Polysaccharides and Ferroptosis-Related Phytochemicals in Liver Diseases

Liver disease is a global health burden with high morbidity and mortality worldwide. Liver injuries can develop into severe end-stage diseases, such as cirrhosis or hepatocellular carcinoma, without valid treatment. Therefore, identifying novel drugs may promote liver disease treatment. Phytochemicals, including polysaccharides, flavonoids, alkaloids, and terpenes, are abundant in foods and medicinal plants and have various bioactivities, such as antioxidation, immunoregulation, and tumor killing. Recent studies have shown that many natural polysaccharides play protective roles in liver disease models in vitro and in vivo, such as fatty liver disease, alcoholic liver disease, drug-induced liver injury, and liver cancer. The mechanisms of liver disease are complex. Notably, ferroptosis, a new type of cell death driven by iron and lipid peroxidation, is considered to be the key mechanism in many hepatic pathologies. Therefore, polysaccharides and other types of phytochemicals with activities in ferroptosis regulation provide novel therapeutic strategies for ferroptosis-related liver diseases. This review summarizes our current understanding of the mechanisms of ferroptosis and liver injury and compelling preclinical evidence of natural bioactive polysaccharides and phytochemicals in treating liver disease.

Wild Bitter Melon Extract Abrogates Hypoxia-Induced Cell Death via the Regulation of Ferroptosis, ER Stress, and Apoptosis in Microglial BV2 Cells

Microglial cells are well-known phagocytic cells that are resistant to the central nervous system (CNS) and play an important role in the maintenance of CNS homeostasis. Activated microglial cells induce neuroinflammation under hypoxia and typically cause neuronal damage in CNS diseases. In this study, we propose that wild bitter melon extract (WBM) has a protective effect on hypoxia-induced cell death via regulation of ferroptosis, ER stress, and apoptosis. The results demonstrated that hypoxia caused microglial BV-2 the accumulation of lipid ROS, ferroptosis, ER stress, and apoptosis. In this study, we investigated the pharmacological effects of WBM on BV-2 cells following hypoxia-induced cell death. The results indicated that WBM reversed hypoxia-downregulated antiferroptotic molecules Gpx4 and SLC7A11, as well as upregulated the ER stress markers CHOP and Bip. Moreover, WBM alleviated hypoxia-induced apoptosis via the regulation of cleaved-caspase 3, Bax, and Bcl-2. Our results suggest that WBM may be a good candidate for preventing CNS disorders in the future.

Orientin Alleviates Liver Inflammation via Downregulation of ZEB-2/PTEN Markers—Hepatic Stellate Cells Approach

Liver inflammation is associated with an increased risk of liver fibrosis that substantially progresses to cirrhosis. Recently, usage of the herbal supplement has been increased because of its emerging role to dominate oxidative stress in hepatic injury. Orientin is one of the bioactive flavonoids that possesses a diversity of curative activities. Therefore, the present study was conducted to evaluate the anti-inflammatory role of orientin (1 mg/kg) in vitro in lipopolysaccharide (LPS)-induced inflammation in hepatic stellate cells (HSCs) and in vivo in carbon tetrachloride (CCl4)-induced liver fibrosis in mice. Moreover, the current study was supported by in silico investigation. Orientin demonstrated protection against LPS-induced HSC inflammation as evidenced by a decrease in iNOS, NO, and TNF-α and inhibition of the fibrotic markers ZEB-2 and PTEN. In addition, orientin afforded protection against CCl4-induced liver fibrosis in mice as shown from decreased AST/ALT ratio, inhibition of the pro-inflammatory mediators TNF-α, IL-6, IL-8, and IFN-γ, reduction of fibrotic markers ZEB-2 and PTEN, and improvement of the histopathological changes. Furthermore, the docking study demonstrated virtual interactions of orientin with ZEB-2 and PTEN. Taken together, the current study suggested that the protective effects of orientin against LPS- and CCl4-induced liver inflammation are via inhibition of fibrotic markers and reduction of pro-inflammatory mediators.

Saikosaponin D Inhibits the Proliferation and Promotes the Apoptosis of Rat Hepatic Stellate Cells by Inducing Autophagosome Formation

Objective

This study aimed to investigate the effects of saikosaponin D (SSd) on the proliferation and apoptosis of the HSC-T6 hepatic stellate cell line and determine the key pathway that mediates SSd's function.

Methods

Cell viability was detected using the CCK-8 kit. The EdU kit and flow cytometry were used to examine cell proliferation. The Annexin V-FITC/PI double staining kit and flow cytometry were used to examine cell apoptosis. Western blot analysis was performed to analyze the expression levels of LC3, Ki67, cleaved caspase 3, Bax, and Bcl2. Autophagosome formation was detected by LC3-GFP adenovirus transfection.

Results

SSd inhibits the proliferation and promotes the apoptosis of acetaldehyde-activated HSC-T6 cells. SSd treatment increased the expression of cleaved caspase 3 and Bax but reduced that of Ki67 and Bcl2. The same concentration of SSd barely influenced the growth of normal rat liver BRL-3A cells. SSd upregulated LC3-II expression and induced autophagosome formation. Autophagy agonist rapamycin had the same effect as SSd and autophagy inhibitor 3-methyladenine could neutralize the effect of SSd in acetaldehyde-activated HSC-T6 cells.

Conclusions

SSd could inhibit the proliferation and promote the apoptosis of HSC-T6 cells by inducing autophagosome formation.