Overview of Innate Immune Cell Landscape in Liver Aging.

Aging is a biological process with a gradual decline in functional capacity, and this process often enhances the risk of chronic disease morbidity and mortality. With advanced age, the immune system undergoes a process of remodeling that can lead to a chronic inflammatory state, termed immunosenescence and inflammaging, respectively. Immunosenescence is accompanied by changes in the number, proportion, and functional capacity of the innate immune cells. The accumulation of dysfunctional immune cells and the presence of low-grade inflammation can lead to organ damage and expedite the aging process. The liver, crucial in regulating the body's metabolism and immune function, is not exempt from these effects. Age-related modifications affect its immune function and regenerative abilities, potentially increasing the prevalence of age-related liver diseases. While aging's impact on the liver is relatively less severe compared to other organ systems, it still experiences an infiltration of innate immune cells and heightened inflammation levels. This review will elaborate on how aging affects the liver's innate immune cells, such as neutrophils, macrophages, dendritic cells, mast cells, and innate lymphoid cells. It will also explore potential strategies for delaying immunosenescence to alleviate these age-related changes.

[Effect and mechanism of Dahuang Zhechong Pills in improving liver aging in rats by regulating ROS-mediated PI3K/Akt/FoxO4 signaling pathway].

Recent studies have shown that the occurrence and development of common liver diseases, including non-alcoholic fatty liver disease, cirrhosis, and liver cancer, are related to liver aging(LA). Therefore, to explore the effect and mechanism of Dahuang Zhechong Pills(DHZCP), a traditional classic prescription in improving LA with multiple targets, the present study randomly divided 24 rats into a normal group, a model group, a DHZCP group, and a vitamin E(VE) group, with six rats in each group. The LA model was induced by continuous intraperitoneal injection of D-galactose(D-gal) in rats. For the LA model rats, the general situation was evaluated by aging phenotype and body weight(BW). LA was assessed by the pathological characteristics of hepatocyte senescence, hepatic function indexes, the staining characteristics of phosphorylated histone family 2A variant(γ-H2AX), and the expression levels of cell cycle arrest proteins(P21, P53, P16) and senescence-associated secretory phenotype(SASP) in the liver. The activation of the reactive oxygen species(ROS)-mediated phosphatidylinositol-3 kinase(PI3K)/protein kinase B(Akt)/forkhead box protein O4(FoxO4) signaling pathway was estimated by hepatic ROS expression feature and the protein expression levels of the key signaling molecules in the PI3K/Akt/FoxO4 signaling pathway. The results showed that after the treatment with DHZCP or VE for 12 weeks, for the DHZCP and VE groups, the characterized aging phenotype, BW, pathological characteristics of hepatocyte senescence, hepatic function indexes, relative expression of ROS in the liver, protein expression levels of key signaling molecules including p-PI3K, p-Akt, and FoxO4 in the liver, staining characteristics of γ-H2AX, and the protein expression levels of P16, P21, P53, interleukin-6(IL-6), and tumor necrosis factor-α(TNF-α) in the liver were improved, and the effects of DHZCP and VE were similar. Based on the D-gal-induced LA model in rats, this study demonstrates that DHZCP can ameliorate LA with multiple targets in vivo, and its effects and mechanism are related to regulating the activation of the ROS-mediated PI3K/Akt/FoxO4 signaling pathway in the liver. These findings are expected to provide new pharmacological evidence for the treatment of DHZCP in aging-related liver diseases.

Integrating Network Pharmacology and Transcriptomic Strategies to Explore the Pharmacological Mechanism of Hydroxysafflor Yellow A in Delaying Liver Aging.

Aging affects the structure and function of the liver. Hydroxysafflor yellow A (HSYA) effectively improves liver aging (LA) in mice, but the potential mechanisms require further exploration. In this study, an integrated approach combining network pharmacology and transcriptomics was used to elucidate the potential mechanisms of HSYA delay of LA. The targets of HSYA were predicted using the PharmMapper, SwissTargetPrediction, and CTD databases, and the targets of LA were collected from the GeneCards database. An ontology (GO) analysis and a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation of genes related to HSYA delay of LA were performed using the DAVID database, and Cytoscape software was used to construct an HSYA target pathway network. The BMKCloud platform was used to sequence mRNA from mouse liver tissue, screen differentially expressed genes (DEGs) that were altered by HSYA, and enrich their biological functions and signaling pathways through the OmicShare database. The results of the network pharmacology and transcriptomic analyses were combined. Then, quantitative real-time PCR (qRT-PCR) and Western blot experiments were used to further verify the prediction results. Finally, the interactions between HSYA and key targets were assessed by molecular docking. The results showed that 199 potentially targeted genes according to network pharmacology and 480 DEGs according to transcriptomics were involved in the effects of HSYA against LA. An integrated analysis revealed that four key targets, including HSP90AA1, ATP2A1, NOS1 and CRAT, as well as their three related pathways (the calcium signaling pathway, estrogen signaling pathway and cGMP-PKG signaling pathway), were closely related to the therapeutic effects of HSYA. A gene and protein expression analysis revealed that HSYA significantly inhibited the expressions of HSP90AA1, ATP2A1 and NOS1 in the liver tissue of aging mice. The molecular docking results showed that HSYA had high affinities with the HSP90AA1, ATP2A1 and NOS1 targets. Our data demonstrate that HSYA may delay LA in mice by inhibiting the expressions of HSP90AA1, ATP2A1 and NOS1 and regulating the calcium signaling pathway, the estrogen signaling pathway, and the cGMP-PKG signaling pathway.

Hepatitis B and elders: An underestimated issue.

As the world's population becomes older, the burden of hepatitis B virus in elderly has to be considered. The liver changes with aging and its function is eventually altered. The prevalence of hepatitis B virus is paradoxically more important in elderly in areas having vaccination programs, because of a loosening of the prevention in older patients. Some differences in hepatitis B presentation must be enhanced in elderly: lower spontaneous hepatitis B surface antigen clearance after a recent contamination, major risk of cirrhosis and hepatocarcinoma. Acute hepatitis B seems to be more often symptomatic, with a great risk of chronicity. Hepatocarcinoma linked to hepatitis B virus has a higher prevalence and a different presentation in elderly. Its treatment is the same as in younger people but is less often possible. Liver transplantation is contraindicated after 70 years old. Hepatitis B treatment panel is the same as in younger people (pegylated interferon, nucleoside or nucleotide agents). It gives identical results with no particular adverse events if the precautions for use are followed. Vaccination is less efficient, as in immunocompromised patients, and needs specific protocols.

The biological mechanism and emerging therapeutic interventions of liver aging.

Research on liver aging has become prominent and has attracted considerable interest in uncovering the mechanism and therapeutic targets of aging to expand lifespan. In addition, multi-omics studies are widely used to perform further mechanistic investigations on liver aging. In this review, we illustrate the changes that occur with aging in the liver, present the current models of liver aging, and emphasize existing multi-omics studies on liver aging. We integrated the multi-omics data of enrolled studies and reanalyzed them to identify key pathways and targets of liver aging. The results indicated that C-X-C motif chemokine ligand 9 (Cxcl9) was a regulator of liver aging. In addition, we provide a flowchart for liver aging research using multi-omics analysis and molecular experiments to help researchers conduct further research. Finally, we present emerging therapeutic treatments that prolong lifespan. In summary, using cells and animal models of liver aging, we can apply a multi-omics approach to find key metabolic pathways and target genes to mitigate the adverse effects of liver aging.

Integrative analysis of the transcriptome and metabolome reveals the importance of hepatokine FGF21 in liver aging.

Aging is a contributor to liver disease. Hence, the concept of liver aging has become prominent and has attracted considerable interest, but its underlying mechanism remains poorly understood. In our study, the internal mechanism of liver aging was explored via multi-omics analysis and molecular experiments to support future targeted therapy. An aged rat liver model was established with d-galactose, and two other senescent hepatocyte models were established by treating HepG2 cells with d-galactose and H2O2. We then performed transcriptomic and metabolomic assays of the aged liver model and transcriptome analyses of the senescent hepatocyte models. In livers, genes related to peroxisomes, fatty acid elongation, and fatty acid degradation exhibited down-regulated expression with aging, and the hepatokine Fgf21 expression was positively correlated with the down-regulation of these genes. In senescent hepatocytes, similar to the results found in aged livers, FGF21 expression was also decreased. Moreover, the expressions of cell cycle-related genes were significantly down-regulated, and the down-regulated gene E2F8 was the key cell cycle-regulating transcription factor. We then validated that FGF21 overexpression can protect against liver aging and that FGF21 can attenuate the declines in the antioxidant and regenerative capacities in the aging liver. We successfully validated the results from cellular and animal experiments using human liver and blood samples. Our study indicated that FGF21 is an important target for inhibiting liver aging and suggested that pharmacological prevention of the reduction in FGF21 expression due to aging may be used to treat liver aging-related diseases.

Liver Diseases: Science, Fiction and the Foreseeable Future.

This Editorial precedes the Special Issue entitled "Novel Challenges and Therapeutic Options for Liver Diseases". Following a historical outline of the roots of hepatology, we provide a brief insight into our colleagues' contributions in this issue on the current developments in this discipline related to the prevention of liver diseases, the metabolic dysfunction-associated steatotic liver disease (or non-alcoholic fatty liver disease, respectively), liver cirrhosis, chronic viral hepatitides, acute-on-chronic liver failure, liver transplantation, the liver-microbiome axis and microbiome transplantation, and telemedicine. We further add some topics not covered by the contributions herein that will likely impact future hepatology. Clinically, these comprise the predictive potential of organokine crosstalk and treatment options for liver fibrosis. With regard to promising developments in basic research, some current findings on the genetic basis of metabolism-associated chronic liver diseases, chronobiology, metabolic zonation of the liver, aspects of the aging liver against the background of demography, and liver regeneration will be presented. We expect machine learning to thrive as an overarching topic throughout hepatology. The largest study to date on the early detection of liver damage-which has been kicked off on 1 March 2024-is highlighted, too.

Canthaxanthin shows anti-liver aging and anti-liver fibrosis effects by down-regulating inflammation and oxidative stress in vivo and in vitro.

The elderly population is growing rapidly all over the world. The aging population has brought great medical pressure to the society. It is found that aging is one of the pathogenic factors of liver fibrosis and liver cancer. Therefore, it is very important to explore functional foods with anti-aging, anti-fibrosis and anti-liver cancer effect. Therefore, in this work, we studied the potential effects of Canthaxanthin on liver aging, liver fibrosis and liver cancer. Firstly, we established the aging modelof liver cells by using H2O2. On this basis, the anti-aging effect of Canthaxanthin was analyzed, and the results showed that Canthaxanthin could significantly alleviate the aging of liver cells through Sa-ß-Gal staining and analysis of the expression of aging related markers. In vivo, aged mice wereused as the animal model for studying the effect of anti-aging of Canthaxanthin. The results showed that Canthaxanthin could significantly alleviate the aging of liver in vivo. Further study show that Canthaxanthin may alleviatethe aging of liver cells by regulating SIRT6; Secondly, we evaluated the effect of Canthaxanthin on liver fibrosis. A model of liver fibrosis was established by CCl4. Masson and Sirius red staining showed that Canthaxanthin could significantly reduce the fibrosis area. Additionally, the level of liver inflammation was also reduced; Thirdly, the effect of Canthaxanthin on hepatoma cells has also been investigated. The resultsshowed that Canthaxanthin could promote the apoptosis of hepatoma cells in vivo and in vitro. To sum up, these results show that canthaxanthin can significantly alleviate liver aging and fibrosis, and Canthaxanthin can also promote the apoptosis of liver cancer cells, indicating that Canthaxanthin can be used as a potential drug or health food for the treatment of liveraging related diseases.

Cisd2 slows down liver aging and attenuates age-related metabolic dysfunction in male mice.

The liver plays a pivotal role in mammalian aging. However, the mechanisms underlying liver aging remain unclear. Cisd2 is a pro-longevity gene in mice. Cisd2 mediates lifespan and healthspan via regulation of calcium homeostasis and mitochondrial functioning. Intriguingly, the protein level of Cisd2 is significantly decreased by about 50% in the livers of old male mice. This down-regulation of Cisd2 may result in the aging liver exhibiting non-alcoholic fatty liver disease (NAFLD) phenotype. Here, we use Cisd2 transgenic mice to investigate whether maintaining Cisd2 protein at a persistently high level is able to slow down liver aging. Our study identifies four major discoveries. Firstly, that Cisd2 expression attenuates age-related dysregulation of lipid metabolism and other pathological abnormalities. Secondly, revealed by RNA sequencing analysis, the livers of old male mice undergo extensive transcriptomic alterations, and these are associated with steatosis, hepatitis, fibrosis, and xenobiotic detoxification. Intriguingly, a youthful transcriptomic profile, like that of young 3-month-old mice, was found in old Cisd2 transgenic male mice at 26 months old. Thirdly, Cisd2 suppresses the age-associated dysregulation of various transcription regulators (Nrf2, IL-6, and Hnf4a), which keeps the transcriptional network in a normal pattern. Finally, a high level of Cisd2 protein protects the liver from oxidative stress, and this is associated with a reduction in mitochondrial DNA deletions. These findings demonstrate that Cisd2 is a promising target for the development of therapeutic agents that, by bringing about an effective enhancement of Cisd2 expression, will slow down liver aging.

Ginsenoside Rg1 ameliorates aging­induced liver fibrosis by inhibiting the NOX4/NLRP3 inflammasome in SAMP8 mice.

Aging is often accompanied by liver injury and fibrosis, eventually leading to the decline in liver function. However, the mechanism of aging­induced liver injury and fibrosis is still not fully understood, to the best of our knowledge, and there are currently no effective treatment options available for liver aging. Ginsenoside Rg1 (Rg1) has been reported to exert potent anti­aging effects due to its potential antioxidant and anti­inflammatory activity. The present study aimed to investigate the protective effect and underlying mechanism of action of Rg1 in aging­induced liver injury and fibrosis in senescence­accelerated mouse prone 8 (SAMP8) mice treated for 9 weeks. The histopathological results showed that the arrangement of hepatocytes was disordered, vacuole­like degeneration occurred in the majority of cells, and collagen IV and TGF­ß1 expression levels, that were detected via immunohistochemistry, were also significantly upregulated in the SAMP8 group. Rg1 treatment markedly improved aging­induced liver injury and fibrosis, and significantly downregulated the expression levels of collagen IV and TGF­ß1. In addition, the dihydroethylene staining and western blotting results showed that Rg1 treatment significantly reduced the levels of reactive oxygen species (ROS) and IL­1ß, and downregulated the expression levels of NADPH oxidase 4 (NOX4), p47phox, p22phox, phosphorylated­NF­κB, caspase­1, apoptosis­associated speck­like protein containing a C­terminal caspase recruitment domain and the NLR family pyrin domain containing 3 (NLRP3) inflammasome, which were significantly upregulated in the liver tissues of elderly SAMP8 mice. In conclusion, the findings of the present study suggested that Rg1 may attenuate aging­induced liver injury and fibrosis by reducing NOX4­mediated ROS oxidative stress and inhibiting NLRP3 inflammasome activation.

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.

l-Theanine attenuates liver aging by inhibiting advanced glycation end products in d-galactose-induced rats and reversing an imbalance of oxidative stress and inflammation.

Redox and inflammation imbalances are associated with increased levels of advanced glycation end products (AGEs), leading to the degeneration of body function. l-Theanine, derived from tea, reportedly inhibits AGE formation in vitro. We investigated the effects on AGE content, oxidative stress, and inflammatory factors in d-galactose-induced aging rats for prevention and treatment of age-related liver dysfunction. l-Theanine increased activities of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, thus enhancing total antioxidant capacity, and decreasing malondialdehyde and nitric oxide synthase levels in serum and liver. Levels of the pro-inflammatory factors, interleukin (IL)-1ß, tumour necrosis factor-alpha, and IL-6 were decreased in serum and liver, whereas those of anti-inflammatory factors, IL-4 and IL-10, were increased in the serum. Further, l-theanine inhibited AGE production and decreased the levels of the liver function markers, alanine aminotransaminase and aspartate aminotransferase. It also significantly increased the mRNA expression levels of FoxO1 and downregulated NF-κB(p65) but suppressed the phosphorylation of both FOXO1 and NF-κB (p65). Moreover, l-theanine effectively attenuated d-galactose-induced oedema and vacuole formation, thus protecting the liver. Overall, l-theanine reversed the d-galactose-induced imbalance in oxidative stress and inflammatory responses, reduced AGEs content in aging rats, maintained homeostasis in the body, and ameliorated liver aging.

The peculiar aging of human liver: A geroscience perspective within transplant context.

An appraisal of recent data highlighting aspects inspired by the new Geroscience perspective are here discussed. The main findings are summarized as follows: i) liver has to be considered an immunological organ, and new studies suggest a role for the recently described cells named telocytes; ii) the liver-gut axis represents a crucial connection with environment and life style habits and may influence liver diseases onset; iii) the physiological aging of liver shows relatively modest alterations. Nevertheless, several molecular changes appear to be relevant: a) an increase of microRNA-31-5p; -141-3p; -200c-3p expressions after 60 years of age; b) a remodeling of genome-wide DNA methylation profile evident until 60 years of age and then plateauing; c) changes in transcriptome including the metabolic zones of hepatocyte lobules; d) liver undergoes an accelerated aging in presence of chronic inflammation/liver diseases in a sort of continuum, largely as a consequence of unhealthy life styles and exposure to environmental noxious agents. We argue that chronic liver inflammation has all the major characteristics of "inflammaging" and likely sustains the onset and progression of liver diseases. Finally, we propose to use a combination of parameters, mostly obtained by omics such as transcriptomics and epigenomics, to evaluate in deep both the biological age of liver (in comparison with the chronological age) and the effects of donor-recipient age-mismatches in the context of liver transplant.

Effects of apoptosis on liver aging.

As an irreversible and perennial process, aging is accompanied by functional and morphological declines in organs. Generally, aging liver exhibits a decline in volume and hepatic blood flow. Even with a preeminent regenerative capacity to restore its functions after liver cell loss, its biosynthesis and metabolism abilities decline, and these are difficult to restore to previous standards. Apoptosis is a programmed death process via intrinsic and extrinsic pathways, in which Bcl-2 family proteins and apoptosis-related genes, such as p21 and p53, are involved. Apoptosis inflicts both favorable and adverse influences on liver aging. Apoptosis eliminates transformed abnormal cells but promotes age-related liver diseases, such as nonalcoholic fatty liver disease, liver fibrosis, cirrhosis, and liver cancer. We summarize the roles of apoptosis in liver aging and age-related liver diseases.

Study on Metabolic Trajectory of Liver Aging and the Effect of Fufang Zhenzhu Tiaozhi on Aging Mice.

The aim of this study was to investigate the metabolic trajectory of liver aging, the effect of FTZ against liver aging in aging mice, and its mechanism using ultraperformance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Methods: A total of 80 C57BL/6J Narl mice were randomly divided into five groups: 3-month-old group, 9-month-old group, 14-month-old group, 20-month-old group, and FTZ treatment group (20 months old). The mice in the treatment group received a therapeutic dose of oral FTZ extract (1.0 g/kg, on raw material weight basis) once daily during the experiment. The other groups received the corresponding volume of oral normal saline solution. Liver samples of all five groups were collected after 12 weeks, and UPLC-Q-TOF/MS was used to analyze metabolic changes. Orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to analyze the resulting data. Additionally, cholesterol (TC), triglyceride (TG), aspartate aminotransferase (AST), alanine aminotransferase (ALT), secretion levels of TNF-α, IL-6, 5-LOX, and COX-2, as well as their relative mRNA expression in the liver were determined. Results: The levels of TC, TG, AST, and ALT were increased, and liver tissue structure was damaged. The secretion levels of TNF-α, IL-6, 5-LOX, and COX-2, as well as their relative mRNA expression in the liver also increased with aging. FTZ administration reduced the symptoms of liver aging. The OPLS-DA score plot illustrated the effect of FTZ against liver aging, with N-acetyl-leukotriene E4, 20-hydroxy-leukotriene E4, leukotriene E4, and arachidonic acid among the key biomarkers. The pivotal pathways revealed by pathway analysis included arachidonic acid metabolism and biosynthesis of unsaturated fatty acids. The mechanism by which FTZ reduces the symptoms of liver aging in mice might be related to disorders of the abovementioned pathways. Conclusion: A metabolomic approach based on UPLC-Q-TOF/MS and multivariate statistical analysis was successfully applied to investigate the metabolic trajectory of liver aging. FTZ has a protective effect against liver aging, which may be mediated via interference with the metabolism of arachidonic acid, biosynthesis of unsaturated fatty acids, and downregulation of pro-inflammatory factors in the liver in mice in vivo.