Effects of apoptosis on liver aging

Prolonged Supplementation of Ozonated Sunflower Oil Bestows an Antiaging Effect, Improves Blood Lipid Profile and Spinal Deformities, and Protects Vital Organs of Zebrafish (Danio rerio) against Age-Related Degeneration: Two-Years Consumption Study

Ozonated sunflower oil (OSO) is renowned for its diverse therapeutic benefits. Nonetheless, the consequences of extended dietary intake of OSO have yet to be thoroughly investigated. Herein, the effect of 2-year dietary supplementation of OSO was examined on the survivability, obesity, skeletal deformities, swimming behavior, and liver, kidney, ovary, and testis function of zebrafish. Results showed that the zebrafish feed supplemented with 20% (wt/wt) OSO for 2 years emerged with higher survivability and body weight management compared to sunflower oil (SO) and normal diet (ND)-supplemented zebrafish. Radio imaging (X-ray)-based analysis revealed 2.6° and 15.2° lower spinal curvature in the OSO-supplemented groups than in the SO and ND-supplemented groups; consistently, OSO-supplemented zebrafish showed better swimming behavior. The histology analysis of the liver revealed the least fatty liver change and interleukin (IL)-6 generation in the OSO-supplemented group. Additionally, a significantly lower level of reactive oxygen species (ROS), apoptotic, and senescent cells were observed in the liver of the OSO-supplemented zebrafish. Also, no adverse effect on the kidney, testis, and ovary morphology was detected during 2 years of OSO consumption. Moreover, lower senescence with diminished ROS and apoptosis was noticed in the kidney and ovary in response to OSO consumption. The OSO supplementation was found to be effective in countering age-associated dyslipidemia by alleviating total cholesterol (TC), triglycerides (TG), low-density lipoproteins (LDL-C) and elevating high-density lipoproteins (HDL-C)/TC levels. Conclusively, prolonged OSO consumption showed no adverse effect on the morphology and functionality of vital organs; in fact, OSO supplementation displayed a protective effect against age-associated detrimental effects on spinal deformities, vital organ functionality, cell senescence, and the survivability of zebrafish.

Red Ginseng Attenuates the Hepatic Cellular Senescence in Aged Mice

Cellular senescence is defined as an irreversible cell cycle arrest accompanied by morphological and physiological alterations during aging. Red ginseng (RG), processed from fresh ginseng (Panax ginseng C.A. Meyer) with a one-time steaming and drying process, is a well-known beneficial herbal medicine showing antioxidant, anti-inflammatory, and anti-aging properties. The current study aimed to investigate the benefits of RG in alleviating hepatic cellular senescence and its adverse effects in 19-month-old aged mice. We applied two different intervention methods and durations to compare RG's effects in a time-dependent manner: (1) oral gavage injection for 4 weeks and (2) ad libitum intervention for 14 weeks. We observed that 4-week RG administration was exerted to maintain insulin homeostasis against developing age-associated insulin insensitivity and suppressed cellular senescence pathway in the liver and primary hepatocytes. Moreover, with remarkable improvement of insulin homeostasis, 14-week RG supplementation downregulated the activation of c-Jun N-terminal kinase (JNK) and its downstream transcriptional factor nuclear factor-κB (NF-κB) in aged mice. Lastly, RG treatment significantly reduced the senescence-associated β-galactosidase (SA-β-gal)-positive cells in primary hepatocytes and ionizing radiation (IR)-exposed mouse embryonic fibroblasts (MEFs). Taken together, we suggest that RG can be a promising candidate for a senolytic substance by preventing hepatic cellular senescence.

A novel role of Fas in delaying cellular senescence

Fas-mediated apoptosis is a major player of many physiological and pathological cellular processes. Fas-regulated immune regulation exhibits either the beneficial or the harmful effects which is associated with the onset or development of immune disorders. Alterations in apoptosis may contribute to age-associated changes. However, the role of apoptosis in the ageing process remains ambiguous. Here we demonstrated Fas signaling-mediated premature senescence in young mouse embryonic fibroblast (MEF) cells. Activated Fas signaling by agonist Jo-2 resulted in declined senescence in young and aged MEFs. Premature senescence induced the early activation of senescence markers, including the increase in the percentage of SA-β-galactosidase (SA-β-gal) cells, the induction of p53 phosphorylation, and the enhanced expression of p16 and p21 protein and elevated IL-6 pro-inflammatory cytokine in the absence of Fas. The elevated production of reactive oxygen species (ROS) in Fas-deficient MEFs was associated with dysfunctional mitochondria. Further, we determined that the known ROS scavenger NAC (N-acetyl-l-cysteine) could reverse the process of premature senescence in absence of Fas. Therefore, this study signifies a novel role of Fas in the control of cellular senescence.

Molecular Mechanisms of Hepatic Dysfunction in Sickle Cell Disease: Lessons From The Townes Mouse Model

Sickle cell disease (SCD) is an autosomal-recessive-genetic disorder that affects ~100,000 Americans and millions of people worldwide. Erythrocyte sickling, vaso-occlusion, sterile inflammation and hemolysis are the major pathophysiological pathways leading to liver injury in SCD. Although hepatic dysfunction affects up to 10-40% of SCD patients, therapeutic approaches to prevent liver injury in SCD are not known, and the molecular mechanisms promoting progressive liver injury in SCD remain poorly understood. Animal models have been beneficial in bridging the gap between preclinical and translational research in SCD. Recent advances in methodology have allowed the development of several humanized mouse models to address various aspects of SCD related liver diseases. This review provides an overview of current knowledge of the molecular mechanisms and potential therapeutic options of SCD associated liver dysfunction using the Townes mouse model.

Intravital imaging reveals inflammation as a dominant pathophysiology of age-related hepatovascular changes

Aging is the most significant risk factor for the majority of chronic diseases, including liver disease. The cellular, molecular, and pathophysiological mechanisms that promote age-induced hepatovascular changes are unknown due to our inability to visualize changes in liver pathophysiology in live mice over time. We performed quantitative liver intravital microscopy (qLIM) in live C57BL/6J mice to investigate the impact of aging on the hepatovascular system over a 24-mo period. qLIM revealed that age-related hepatic alterations include reduced liver sinusoidal blood flow, increased sinusoidal vessel diameter, and loss of small hepatic vessels. The ductular cell structure deteriorates with age, along with altered expression of hepatic junctional proteins. Furthermore, qLIM imaging revealed increased inflammation in the aged liver, which was linked to increased expression of proinflammatory macrophages, hepatic neutrophils, liver sinusoidal endothelial cells, senescent cells, and procoagulants. Finally, we detected elevated NF-κB pathway activity in aged livers. Overall, these findings emphasize the importance of inflammation in age-related hepatic vasculo-epithelial alterations and highlight the utility of qLIM in studying age-related effects in organ pathophysiology.

Green Tea Polyphenols Upregulate the Nrf2 Signaling Pathway and Suppress Oxidative Stress and Inflammation Markers in D-Galactose-Induced Liver Aging in Mice

The beneficial effects of green tea polyphenols (GTPs) on D-galactose (D-Gal)-induced liver aging in male Kunming mice were investigated. For this purpose, 40 adult male Kunming mice were divided into four groups. All animals, except for the normal control and GTPs control, were intraperitoneally injected with D-galactose (D-Gal; 300 mg/kg/day for 5 days a week) for 12 consecutive weeks, and the D-Gal-treated mice were allowed free access to 0.05% GTPs (w/w) diet or normal diet for 12 consecutive weeks. Results showed that GTP administration improved the liver index and decreased transaminases and total bilirubin levels. Furthermore, GTPs significantly increased hepatic glutathione and total antioxidant levels, and the activities of superoxide dismutase, catalase, and glutathione S-transferase (GST). Furthermore, GTPs downregulated 8-hydroxy-2-deoxyguanosine, advanced glycation end products, and hepatic oxidative stress markers, such as malondialdehyde and nitric oxide. Additionally, GTPs abrogated dysregulation in hepatic Kelch-like ECH-associated protein 1 and nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target gene expression [heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1, and GST] and inhibited tumor necrosis factor-α, transforming growth factor-β, and interleukin (IL)-1β and IL-6 in the liver of treated mice. Finally, GTPs effectively attenuated D-Gal-induced edema, vacuole formation, and inflammatory cell infiltration. In conclusion, GTPs showed antioxidant and anti-inflammatory properties in D-Gal-induced aging mice, and may be considered a natural alternative to the effects of hepatic aging.

Long Non-coding RNA Signatures Associated With Liver Aging in Senescence-Accelerated Mouse Prone 8 Model

The liver is sensitive to aging because the risk of hepatopathy, including fatty liver, hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma, increases dramatically with age. Long non-coding RNAs (lncRNAs) are >200 nucleotides long and affect many pathological and physiological processes. A potential link was recently discovered between lncRNAs and liver aging; however, comprehensive and systematic research on this topic is still limited. In this study, the mouse liver genome-wide lncRNA profiles of 8-month-old SAMP8 and SAMR1 models were explored through deep RNA sequencing. A total of 605,801,688 clean reads were generated. Among the 2,182 identified lncRNAs, 28 were differentially expressed between SAMP8 and SAMR1 mice. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) surveys showed that these substantially dysregulated lncRNAs participated in liver aging from different aspects, such as lipid catabolic (GO: 0016042) and metabolic pathways. Further assessment was conducted on lncRNAs that are most likely to be involved in liver aging and related diseases, such as LNC_000027, LNC_000204E, NSMUST00000144661.1, and ENSMUST00000181906.1 acted on Ces1g. This study provided the first comprehensive dissection of lncRNA landscape in SAMP8 mouse liver. These lncRNAs could be exploited as potential targets for the molecular-based diagnosis and therapy of age-related liver diseases.

Apoptosis Disorder, a Key Pathogenesis of HCMV-Related Diseases

Human cytomegalovirus (HCMV) belongs to the β-herpesvirus family, which is transmitted in almost every part of the world and is carried by more than 90% of the general population. Increasing evidence indicates that HCMV infection triggers numerous diseases by disrupting the normal physiological activity of host cells, particularly apoptosis. Apoptosis disorder plays a key role in the initiation and development of multiple diseases. However, the relationship and molecular mechanism of HCMV-related diseases and apoptosis have not yet been systematically summarized. This review aims to summarize the role of apoptosis in HCMV-related diseases and provide an insight into the molecular mechanism of apoptosis induced by HCMV infection. We summarize the literature on HCMV-related diseases and suggest novel strategies for HCMV treatment by regulating apoptosis.

Cadmium induced skeletal underdevelopment, liver cell apoptosis and hepatic energy metabolism disorder in Bufo gargarizans larvae by disrupting thyroid hormone signaling

Cadmium (Cd) is hazardous to human health and it is also highly detrimental to amphibian life. In this study, Bufo gargarizans larvae were exposed to environmentally relevant Cd concentrations of 5, 100 and 200 μg L^-1 from Gosner stage (Gs) 26 to Gs 42 of metamorphic climax about 6 weeks. The results showed thyroid structural injuries and thyroid signaling disruption were induced by high Cd exposure (100 and 200 μg L^-1). Moreover, tadpole skeleton including whole body, vertebrata, forelimb and hindlimb was developmentally delayed by high Cd exposure through downregulating the mRNA expressions of genes involved with skeletal ossification and growth pathway. Moreover, liver histopathological injuries were caused by high Cd exposure featured by hepatocytes malformation, nuclear degeneration and increasing melanomacrophage centers. Meanwhile, liver apoptosis rate showed on the rise in a dose-dependent way and Cd stimulated liver apoptosis by upregulating mRNA expressions of genes related to extrinsic and intrinsic apoptosis pathways. Furthermore, high Cd caused hepatic glucometabolism disorder by decreasing the genetic expressions associated with glycolysis and mitochondrial oxidative phosphorylation. In addition, liver lipid metabolism was disrupted by high Cd exposure through downregulating mRNA levels of genes related to fatty oxidation and upregulating mRNA levels of genes related to fatty acid synthesis. We suggested that Cd did great harm to tadpole health by disturbing thyroid function, skeletal growth, liver cell apoptosis signaling and hepatic energy metabolism pathway.

Role of inhibiting Chk1-p53 pathway in hepatotoxicity caused by chronic arsenic exposure from coal-burning

Arsenic is a naturally occurring environmental toxicant, chronic exposure to arsenic can cause multiorgan damage, except for typical skin lesions, liver damage is the main problem for health concern in population with arsenic poisoning. Abnormal apoptosis is closely related to liver-related diseases, and p53 is one of the important hallmark proteins in apoptosis progression. This study was to investigate whether arsenic poisoning-induced hepatocyte apoptosis and the underlying role of p53 signaling pathway. A rat model of arsenic poisoning was established by feeding corn powder for 90 days, which was baked with high arsenic coal, then were treated with Ginkgo biloba extract (GBE) for 45 days by gavage. The results showed that arsenic induced liver damage, increased hepatocyte apoptosis and elevated the expression level of Chk1 and the ratios of p-p53/p53 and Bax/Bcl-2 in liver tissues, which were significantly attenuated by GBE. Additionally, to further demonstrate the potential apoptosis-associated mechanism, L-02 cells were pre-incubated with p53 inhibitor pifithrin-α (PFTα), ataxia telangiectasia-mutated (ATM)/ataxia telangiectasia-mutated and Rad3-related (ATR) inhibitor (CGK733) or GBE, then treated with sodium arsenite (NaAsO₂) for 24 h. The results showed that GBE, PFTα or CGK733 significantly reduced arsenic-induced Chk1 expression and the ratios of p-p53/p53 and Bax/Bcl-2. In conclusion, Chk1-p53 pathway was involved in arsenic poisoning-induced hepatotoxicity, and inhibiting of Chk1-p53 pathway ameliorated hepatocyte apoptosis caused by coal-burning arsenic poisoning. The study provides a pivotal clue for understanding of the mechanism of arsenic poisoning-induced liver damage, and possible intervention strategies.

[Liver regeneration: solved and problem issues]

It is known that liver is able to restore own dimensions and functional properties in response to various injuries. Despite extensive injuries, liver can preserve functional activity. Analysis of liver regeneration mechanisms allowed us to obtain significant results in the treatment of hepatitis, cirrhosis and liver failure. Liver regeneration processes substantiate the development of hepatocellular cancer following cirrhosis. Modern experimental and clinical data on liver regeneration, as well as current methods of stimulating this process are summarized in the manuscript. Despite significant advances in this issue, there are still many questions in scientific understanding of liver regeneration.

ROS-mediated PERK-eIF2α-ATF4 pathway plays an important role in arsenite-induced L-02 cells apoptosis via regulating CHOP-DR5 signaling

Chronic exposure to arsenic remains a worldwide environmental health issue, affecting hundreds of millions of people. Although, arsenic-induced oxidative stress and apoptosis have been determined, the underlying apoptosis mechanism has not been fully elucidated yet. Oxidative stress integrated-ER stress plays an important role in Life-and-Death decision of cells. The current study was to investigate whether NaAsO₂ utilizes oxidative stress integrated-ER stress signaling to exert pro-apoptotic activity in L-02 cells. Results showed that death receptor 5 (DR5) was a mediator of NaAsO₂ -induced apoptosis by enhancing construction of the death-inducing signaling complex (DISC). NaAsO₂ -sensitized DR5 elevation required maintainable transcription and its transcription factor C/EBP homologous protein (CHOP). Further results showed that NaAsO₂ increased expression in biomarker of endoplasmic reticulum (ER) stress and activated the protein kinase R-like ER kinase (PERK)-eukaryotic translation initiation 2α (eIF2α)-activating transcription factor 4 (ATF4) pathway. PERK inhibitor and ATF4 siRNA significantly attenuated NaAsO₂ -induced CHOP and DR5 expressions. In addition, the antioxidant N-acetyl-l-cysteine (NAC) treatment led to amelioration of NaAsO₂ -induced production of reactive oxygen species (ROS) and some ER stress- and apoptosis- related protein levels and cell viability. Taken together, the results indicate that ROS-mediated PERK-eIF2α-ATF4 pathway activated by NaAsO₂ is the critical upstream event for subsequent apoptosis induction via regulating CHOP-DR5 signaling in L-02 cells when chronic exposure to arsenic, and support that antioxidants might be potential therapeutic agents for preventing or delaying the onset and progress of arsenic-induced hepatotoxicity.

Pedro Ximenez sun-dried grape must: a dietary supplement for a healthy longevity

Sun-dried Pedro Ximénez white grapes must (PXM) is a potent antioxidant that regularizes apoptosis, proliferation, and regeneration of the structure and the function of aged mice liver. PXM consumption contributes to a healthy aging process.