A Combination of Mitochondrial Oxidative Stress and Excess Fat/Calorie Intake Accelerates Steatohepatitis by Enhancing Hepatic CC Chemokine Production in Mice

Unraveling the impact of micro- and nano-sized polymethyl methacrylate on gut microbiota and liver lipid metabolism: Insights from oral exposure studies

Microplastics, particularly polymethyl methacrylate (PMMA), have emerged as significant environmental pollutants, with growing concerns about their impact on various biological processes. However, the effects of chronic PMMA exposure on hepatic lipid metabolism remain insufficiently studied. This research aimed to examine the consequences of chronic exposure to PMMA particles of different sizes (100 nm and 2 μm) on hepatic lipid metabolism in mice. Female C57BL/6J mice were administered PMMA particles in drinking water over an 8-week period, and the effects on intestinal and liver morphology and function were evaluated. Histopathological analyses, gut microbiota profiling, and serum and liver assays were conducted to assess oxidative stress, lipid metabolism-related biomarkers, and liver metabolomics. The results revealed that PMMA particles accumulated in both the liver and colon, causing liver injury characterized by elevated ALT and AST levels. The exposure also induced oxidative stress by inhibiting the NRF2/HO-1 signaling pathway. Furthermore, PMMA exposure resulted in significant alterations to the gut microbiota and hepatic metabolism. These changes were linked to increased microbial diversity, which impacted cholesterol metabolism through the gut-liver axis. Additionally, the activation of the PI3K/AKT/PPARγ signaling pathway disrupted hepatic lipid metabolism, leading to increased cholesterol synthesis and hepatic lipid accumulation. This study underscores the potential of PMMA to disrupt both hepatic lipid metabolism and gut microbiota composition, suggesting a novel mechanism by which PMMA exposure could contribute to metabolic disorders and liver disease.

Adipokines regulate the development and progression of MASLD through organellar oxidative stress

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), which is increasingly being recognized as a leading cause of chronic liver pathology globally, is increasing. The pathophysiological underpinnings of its progression, which is currently under active investigation, involve oxidative stress. Human adipose tissue, an integral endocrine organ, secretes an array of adipokines that are modulated by dietary patterns and lifestyle choices. These adipokines intricately orchestrate regulatory pathways that impact glucose and lipid metabolism, oxidative stress, and mitochondrial function, thereby influencing the evolution of hepatic steatosis and progression to metabolic dysfunction-associated steatohepatitis (MASH). This review examines recent data, underscoring the critical interplay of oxidative stress, reactive oxygen species, and redox signaling in adipokine-mediated mechanisms. The role of various adipokines in regulating the onset and progression of MASLD/MASH through mitochondrial dysfunction and endoplasmic reticulum stress and the underlying mechanisms are discussed. Due to the emerging correlation between adipokines and the development of MASLD positions, these adipokines are potential targets for the development of innovative therapeutic interventions for MASLD management. A comprehensive understanding of the pathogenesis of MASLD/MASH is instrumental for identifying therapies for MASH.

Modification of exosomes with carbonate apatite and a glycan polymer improves transduction efficiency and target cell selectivity

Exosomes are secreted from a variety of cells and transmit parental cell-derived biomolecules, such as nucleic acids and proteins, to recipient cells in distant organs. In addition to their important roles in both physiological and pathological conditions, exosomes are expected to serve as natural drug carriers without any cytotoxicity, immunogenicity, or tumorigenicity. However, the use of exosomes as drug delivery tools is limited due to the low uptake efficiency of the target cells, insufficient release of the contents from the endosome to the cytosol, and possible adverse effects caused by the delivery to non-target cells. In the present study, we examined the effects of the modification of exosomes with carbonate apatite or a lactose-carrying polymer. Using newly generated monitoring exosomes that contain either firefly luciferase or fused mCherry/enhanced green fluorescent protein, we demonstrated that the modification of exosomes with carbonate apatite improved their release from the endosome into the cytosol in recipient cells. Meanwhile, the modification of exosomes with a lactose-carrying polymer enhanced the selective delivery to parenchymal hepatocytes. These modified exosomes may provide an efficient strategy for macromolecule therapy for incurable diseases that cannot be treated with conventional small-molecule compounds.

Chemerin/CMKLR1 ameliorates nonalcoholic steatohepatitis by promoting autophagy and alleviating oxidative stress through the JAK2-STAT3 pathway

Nonalcoholic steatohepatitis (NASH) is a global public health challenge. Overwhelmed oxidative stress and impaired autophagy play an important role in the progression of NASH. Chemerin is an adipokine that has attracted much attention in inflammation and metabolic diseases. This study aimed to examine the effects of chemerin in NASH and its association with oxidative stress and autophagy. In this study, chemerin was found to significantly ameliorate high-fat diet (HFD) induced NASH, marked by decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α), decreased insulin resistance (IR) and leptin resistance (LR), and improved liver lesions. Besides, chemerin prevented enhanced oxidative stress in NASH mice by regulating the antioxidant defense system (MDA downregulation and upregulation of superoxide dismutase (SOD)). Moreover, chemerin contributed to the alleviation of NASH through autophagy activation (p62 downregulation, and upregulation of beclin-1 and LC3). Furthermore, these effects were related to increased phosphorylation of JAK2-STAT3 stimulated by chemerin, which could be inhibited by the CMKLR1 specific inhibitor α-NETA. In conclusion, excess chemerin highly probably ameliorated NASH by alleviating oxidative stress and promoting autophagy, the mechanism responsible for this process was related, at least in part, to the increased phosphorylation of JAK2-STAT3 stimulated by chemerin/CMKLR1. Rh-chemerin may represent promising therapeutic targets in the treatment of NASH.

The Effect of Zinc Supplementation on Steatosis Severity and Liver Function Enzymes in Overweight/Obese Patients with Mild to Moderate Non-alcoholic Fatty Liver Following Calorie-Restricted Diet: a Double-Blind, Randomized Placebo-Controlled Trial

The role of zinc is known in balancing the oxidant/antioxidant system and also in improving insulin resistance in many diseases. Recently, in vivo and in vitro studies revealed roles of zinc on lipophagy and suppressing hepatic lipid deposition. The present study is the first double-blind randomized clinical trial that investigated the effect of zinc supplement on clinical manifestations and anthropometric parameters of overweight/obese non-alcoholic fatty liver patients following calorie-restricted diet. Fifty-six overweight/obese subjects with confirmed non-alcoholic fatty liver disease (NAFLD) using ultrasonography were randomized to treatment (calorie-restricted diet plus 30 mg/day zinc supplement) or placebo (calorie-restricted diet and placebo) groups. Serum liver enzymes and liver steatosis were measured at the baseline and 12 weeks post-intervention. Anthropometric measurements and food recalls were collected at the beginning, weeks 6 and 12. Zinc supplementation significantly elevated serum zinc concentrations in the treatment group (p < 0.001). Treatment also reduced alanine aminotransferase and γ-glutamyl transpeptidase enzymes in the treatment group (p < 0.05). Waist circumference was also significantly lowered in the zinc group (p < 0.05). Liver steatosis and fatty liver index changes were not significant between the groups. Overall, beneficial effects of zinc supplementation were shown on serum levels of zinc and liver enzymes in overweight/obese NAFLD patients.

Selenoprotein P inhibits cell proliferation and ROX production in HCC cells

Selenoprotein P (SEPP1) is a kind of secretory glycoproteins with an antioxidant effect during the development of some diseases. In this study, we attempted to observe the expression of SEPP1 in livers from the patients with hepatocellular carcinoma (HCC) and explore its effect on HCC cells. All the tissues from patients with HCC were obtained from Affiliated Hospital of Nantong University. Western blot and immunohistochemical results showed that SEPP1 was reduced in HCC liver tissues. Its expression was negatively correlated with Ki67 expression in tissues. The expression of SEPP1 in normal liver cell line was significantly higher than those in the liver cancer cell lines. Serum starvation and release experiment demonstrated that SEPP1 expression was reduced and PCNA expression was increased, when the serum was re-added into cell culture system and the cells were on a proliferation state. After SEPP1 over-expression plasmid was transfected into HepG2 cells, cell proliferation of HepG2 cells and PCNA expression level were all inhibited by SEPP1. Results obtained via 8-isoprostane ELISA further indicated that inhibited ROS level was found in HepG2 cells transfected with SEPP1 over-expression plasmid. In addition, RT-qPCR results demonstrated that GPX1 expression levels increased in HepG2 cells transfected with SEPP1 over-expression plasmid. In conclusion, SEPP1 may inhibit the proliferation of HCC cells, accompanied by the reduction of ROS production and the increasing of GPX1 expression.

Visualization and isolation of zone-specific murine hepatocytes that maintain distinct cytochrome P450 oxidase expression in primary culture

Parenchymal hepatocytes are responsible for most of the metabolic functions of the liver, but exhibit distinct functional properties depending on their localization within the hepatic lobule. Cytochrome P450 oxidases represent a family of drug-metabolizing enzymes, which are expressed predominantly in hepatocytes localized in the centrilobular area (zone 3). The present study describes a unique transgenic mouse strain that distinguishes zone 3 hepatocytes from periportal zone 1 hepatocytes by the intensity of EGFP fluorescence. Both zone 1 and zone 3 hepatocytes isolated from these mice showed the same zone-specific gene expression patterns as in liver tissue in vivo. Experiments using primary cultures of hepatocytes indicated that a combination of low oxygen concentration and activation of Wnt/β-catenin signaling maintained the expression of zone 3-specific P450 drug-metabolizing enzymes, which was characterized by their susceptibility to acetaminophen-induced mitochondrial dysfunction. These zone-specific hepatocytes provide a useful system in the research area of liver pathophysiology and drug development.

Role of mitochondrial quality control in the pathogenesis of nonalcoholic fatty liver disease

Nutrient oversupply and mitochondrial dysfunction play central roles in nonalcoholic fatty liver disease (NAFLD). The mitochondria are the major sites of β-oxidation, a catabolic process by which fatty acids are broken down. The mitochondrial quality control (MQC) system includes mitochondrial fission, fusion, mitophagy and mitochondrial redox regulation, and is essential for the maintenance of the functionality and structural integrity of the mitochondria. Excessive and uncontrolled production of reactive oxygen species (ROS) in the mitochondria damages mitochondrial components, including membranes, proteins and mitochondrial DNA (mtDNA), and triggers the mitochondrial pathway of apoptosis. The functionality of some damaged mitochondria can be restored by fusion with normally functioning mitochondria, but when severely damaged, mitochondria are segregated from the remaining functional mitochondrial network through fission and are eventually degraded via mitochondrial autophagy, also called as mitophagy. In this review, we describe the functions and mechanisms of mitochondrial fission, fusion, oxidative stress and mitophagy in the development and progression of NAFLD.

Antioxidant Mechanism of Xiaojin Pill () for Treatment of Peyronie's Disease in Rats Based on Matrix Metalloproteinases

OBJECTIVE

To evaluate the effects of Xiaojin Pill () in the treatment of Peyronie's disease (PD) in a rat model.

METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into four groups with 6 in each: sham operation, PD model, vehicle control and Xiaojin Pill groups. The rats in the sham operation group received penile tunica albsginea (TA) injection with 50 μL vehicle, while the rats in the other 3 groups received 50 μL penile TA injection of 50 μg transforming growth factor (TGF)-β1. Forty-two days after the injection, rats in the vehicle control and Xiaojin Pill groups received 0.5 mL water and Xiaojin Pill solution (107 mg/kg of body weight), respectively by gavage for 28 days, while those in the sham operation and PD model groups did not receive any intervention. After intervention, the expressions of matrix metalloproteinase 2/9 (MMP2/9), nitric oxidesynthase (NOS), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured.

RESULTS

Rats in the PD model and vehicle control groups presented obvious fibrosis in corpus cavernosum (CC) and demonstrated a significantly increased expressions of MMP2 and MMP9 in the CC compared with the sham operation group (all P<0.01). In contrast, the expressions of MMP2 and MMP9 in the Xiaojin Pill group were significantly down-regulated (both P<0.01). In addition, the levels of NOS and MDA in CC were significantly increased while the activity of SOD was decreased in the PD model and vehicle control groups compared with the sham operation group (all P<0.01). After Xiaojin Pill treatment, the levels of MDA, NOS and SOD appeared to be corrected (all P<0.01).

CONCLUSIONS

Xiaojin Pill could reduce fibrosis in the CC by decreasing the expressions of MMPs, NOS and MDA, and by increasing the activity of SOD. Therefore, Xiaojin Pill might be a therapeutic option for PD.

Identification of a Novel Bone Marrow Cell-Derived Accelerator of Fibrotic Liver Regeneration Through Mobilization of Hepatic Progenitor Cells in Mice

Granulocyte colony stimulating factor (G-CSF) has been reported to ameliorate impaired liver function in patients with advanced liver diseases through mobilization and proliferation of hepatic progenitor cells (HPCs). However, the underlying mechanisms remain unknown. We previously showed that G-CSF treatment increased the number of bone marrow (BM)-derived cells migrating to the fibrotic liver following repeated carbon tetrachloride (CCl₄ ) injections into mice. In this study, we identified opioid growth factor receptor-like 1 (OGFRL1) as a novel BM cell-derived accelerator of fibrotic liver regeneration in response to G-CSF treatment. Endogenous Ogfrl1 was highly expressed in the hematopoietic organs such as the BM and spleen, whereas the liver contained a relatively small amount of Ogfrl1 mRNA. Among the peripheral blood cells, monocytes were the major sources of OGFRL1. Endogenous Ogfrl1 expression in both the peripheral blood monocytes and the liver was decreased following repeated CCl₄ injections. An intrasplenic injection of cells overexpressing OGFRL1 into CCl₄ -treated fibrotic mice increased the number of HPC and stimulated proliferation of hepatic parenchymal cells after partial resection of the fibrotic liver. Furthermore, overexpression of OGFRL1 in cultured HPC accelerated their differentiation as estimated by increased expression of liver-specific genes such as hepatocyte nuclear factor 4α, cytochrome P450, and fatty acid binding protein 1, although it did not affect the colony forming ability of HPC. These results indicate a critical role of OGFRL1 in the mobilization and differentiation of HPC in the fibrotic liver, and administration of OGFRL1-expressing cells may serve as a potential regenerative therapy for advanced liver fibrosis. Stem Cells 2019;37:89-101.

Serum matrix metalloproteinase-1 level represents disease activity as opposed to fibrosis in patients with histologically proven nonalcoholic steatohepatitis

Background/Aims

Nonalcoholic steatohepatitis (NASH) is prevalent in both economically developed and developing countries. Twenty percent of NASH progresses to cirrhosis with/without hepatocellular carcinoma, and there is an urgent need to find biomarkers for early diagnosis and monitoring progression of the disease. Using immunohistochemical and immunoelectron microscopic examination we previously reported that expression of matrix metalloproteinase-1 (MMP-1) increased in monocytes, Kupffer cells and hepatic stellate cells in early stage NASH. The present study investigated whether serum MMP-1 levels reflect disease activity and pharmaceutical effects in NASH patients.

Methods

We measured the serum levels of MMPs, tissue inhibitors of metalloproteinases (TIMPs), and several cytokines/chemokines in patients with histologically proven early and advanced stages of NASH and compared them with those in healthy controls.

Results

Serum MMP-1 levels in stage 1 fibrosis, but not in the more advanced fibrosis stages, were significantly higher than in healthy controls (P=0.019). There was no correlation between serum MMP-1 level and fibrosis stage. Serum MMP- 1 levels in NASH patients represented disease activity estimated by serum aminotransferase values during the follow-up period. In contrast, MMP-2, MMP-9 and TIMPs did not change with disease activity. Consistent with the finding that MMP-1 is expressed predominantly in monocytes and Kupffer cells, serum levels of monocyte chemotactic protein-1 and granulocyte-colony stimulating factor were significantly increased in NASH with stage 1 fibrosis.

Conclusions

These results suggest that serum MMP-1 levels represent disease activity and may serve as a potential biomarker for monitoring the progression of NASH.

C-C chemokine receptor type 5 deficiency exacerbates alcoholic fatty liver disease through pro-inflammatory cytokines and chemokines-induced hepatic inflammation

BACKGROUND AND AIM

Chemokines and chemokine receptors implicated with alcoholic liver disease. Studies have shown that inflammation and oxidative stress induce fat molecules aggregation in liver. We evaluated the relationship between alcoholic fatty liver disease and C-C chemokine receptor 5 (CCR5) and impact of inflammation and oxidative stress in fat molecule deposition.

METHODS

Lieber-DeCarli diet containing ethanol or isocaloric control diets were fed to wild-type and CCR5 knockout mice for 10 days and gavaged with a single dose of ethanol or isocaloric maltose dextrin at 11th day. Cytokine, chemokine, and reactive oxygen species levels were measured in liver tissues to study the role of CCR5 in alcoholic fatty liver disease.

RESULTS

C-C chemokine receptor type 5 knockout mice exacerbated ethanol-induced liver injury. Serum levels of aspartate aminotransferase and alanine aminotransferase were higher in CCR5 knockout mice than wild-type mice, and CCR5 knockout mice showed more severe lipid accumulation in liver tissue than wild-type mice after ethanol feeding. Increased expressions of pro-inflammatory cytokines TNF-α and IL-6 and chemokines CCL2, CCL3, CCL4, and CCL5 result in exacerbation of hepatitis in CCR5 knockout mice after ethanol feeding. Oxidative stress induced by reactive oxygen species was more severe in CCR5 knockout mice, and increasing level of fatty acid import and decreasing level of lipid degradation resulted in lipid accumulation in ethanol-fed CCR5 knockout mice.

CONCLUSION

Deficiency of CCR5 exacerbates alcoholic fatty liver disease by hepatic inflammation induced by pro-inflammatory cytokines and chemokines and oxidative stress.

Identification of a novel alpha-fetoprotein-expressing cell population induced by the Jagged1/Notch2 signal in murine fibrotic liver

The liver is well known to possess high regenerative capacity in response to partial resection or tissue injury. However, liver regeneration is often impaired in the case of advanced liver fibrosis/cirrhosis when mature hepatocytes can hardly self‐proliferate. Hepatic progenitor cells have been implicated as a source of hepatocytes in regeneration of the fibrotic liver. Although alpha‐fetoprotein (AFP) is known as a clinical marker of progenitor cell induction in injured/fibrotic adult liver, the origin and features of such AFP‐producing cells are not fully understood. Here, we demonstrate a unique and distinct AFP‐expressing cell population that is induced by the Jagged1/Notch2 signal in murine fibrotic liver. Following repeated carbon tetrachloride injections, a significant number of AFP‐positive cells with high proliferative ability were observed along the fibrous septa depending on the extent of liver fibrosis. These AFP‐positive cells exhibited features of immature hepatocytes that were stained positively for hepatocyte‐lineage markers, such as albumin and hepatocyte nuclear factor 4 alpha, and a stem/progenitor cell marker Sox9. A combination of immunohistological examination of fibrotic liver tissues and coculture experiments with primary hepatocytes and hepatic stellate cells indicated that increased Jagged1 expression in activated hepatic stellate cells stimulated Notch2 signaling and up‐regulated AFP expression in adjacent hepatocytes. The mobilization and proliferation of AFP‐positive cells in fibrotic liver were further enhanced after partial hepatectomy, which was significantly suppressed in Jagged1‐conditional knockout mice. Finally, forced expression of the intracellular domain of Notch2 in normal liver induced a small number of AFP‐expressing hepatocytes in vivo. Conclusion: Insight is provided into a novel pathophysiological role of Jagged1/Notch2 signaling in the induction of AFP‐positive cells in fibrotic liver through the interaction between hepatocytes and activated hepatic stellate cells. (Hepatology Communications 2017;1:215‐229)

The exposure to formaldehyde causes renal dysfunction, inflammation and redox imbalance in rats

Twenty-eight Fischer male rats were divided into four groups: control group (CG), exposed to the ambient air, and groups exposed to formaldehyde (FA) at concentrations of 1% (FA1%), 5% (FA5%) and 10% (FA10%). Kidney function was assessed by dosage of uric acid, creatinine and urea. Morphometry was performed on the thickness of the lumen of Bowman's capsule and diameter of the lumen of the renal tubules. We evaluated the redox imbalance through the catalase and superoxide dismutase activity as well as oxidative damage by lipid peroxidation. Inflammatory chemokines CCL2, CCL3 and CCL5 were analyzed by enzyme immunoassays. There was an increase in the concentration of urea in FA10% compared with CG and FA1%. The levels of creatinine, renal lumen and lipid peroxidation increased in all FA-treated groups compared with CG. The concentration of uric acid in FA10% was lower compared with all other groups. There was an increase in the space of Bowman's capsule in FA5% and FA10% compared with CG and FA1%. However, the superoxide dismutase activity was higher in FA5% compared with other groups while CCL5 was higher in FA1% compared with CG. The exposure to formaldehyde in a short period of time leads to changes in the kidney function, inflammation and morphology, as well as promoted the increase of superoxide dismutase activity and oxidative damage.

Peyronie's disease: a literature review on epidemiology, genetics, pathophysiology, diagnosis and work-up

Peyronie's disease (PD), a fibromatous disorder of the tunica albuginea of the penile corpus cavernosum, named after the French physician Francois de la Peyronie, is characterized by pain, plaque formation, penile curvature, and plaque calcification. The epidemiological data on PD is inconsistent, with recent reports stating a prevalence of up to 9%, and the condition affecting men of all ages, from teenagers to septuagenarians. We are just beginning to elucidate the role of genetics as a causative factor for PD. Chromosomal abnormalities and single-nucleotide polymorphisms have been shown to be associated with fibrotic diatheses. Tunical mechanical stress and microvascular trauma are major contributory factors to the pathophysiology of PD. The diagnosis of PD can be made using a combination of clinical history, physical examination and, sometimes, imaging modalities. A better understanding of the molecular pathophysiology of this condition remains paramount for the development of newer and more effective disease-targeted interventions.