Lipopolysaccharide binding protein resists hepatic oxidative stress by regulating lipid droplet homeostasis.

Oxidative stress-induced lipid accumulation is mediated by lipid droplets (LDs) homeostasis, which sequester vulnerable unsaturated triglycerides into LDs to prevent further peroxidation. Here we identify the upregulation of lipopolysaccharide-binding protein (LBP) and its trafficking through LDs as a mechanism for modulating LD homeostasis in response to oxidative stress. Our results suggest that LBP induces lipid accumulation by controlling lipid-redox homeostasis through its lipid-capture activity, sorting unsaturated triglycerides into LDs. N-acetyl-L-cysteine treatment reduces LBP-mediated triglycerides accumulation by phospholipid/triglycerides competition and Peroxiredoxin 4, a redox state sensor of LBP that regulates the shuttle of LBP from LDs. Furthermore, chronic stress upregulates LBP expression, leading to insulin resistance and obesity. Our findings contribute to the understanding of the role of LBP in regulating LD homeostasis and against cellular peroxidative injury. These insights could inform the development of redox-based therapies for alleviating oxidative stress-induced metabolic dysfunction.

Early application of IFNγ mediated the persistence of HBV in an HBV mouse model.

The antiviral activity of interferon gamma (IFNγ) against hepatitis B virus (HBV) was demonstrated both in vivo and in vitro in a previous study. IFNγ can suppress HBV replication by accelerating the decay of replication-competent nucleocapsids of HBV. However, in this study, we found that the direct application of the mouse IFNγ (mIFNγ) expression plasmid to the liver of an HBV hydrodynamic injection (HI) mouse model led to the persistence of HBV, as indicated by sustained HBsAg and HBeAg levels in the serum as well as an increased percentage of the HBsAg positive mice, whereas the level of HBV DNA in the serum and the expression of HBcAg in the liver were inhibited at the early stage after HI. Meanwhile, we found that the productions of both HBcAb and HBsAb were suppressed after the application of mIFNγ. In addition, we found that HBV could be effectively inhibited in mice immunized with HBsAg expression plasmid before the application of mIFNγ. Furthermore, mIFNγ showed antiviral effect and promoted the production of HBsAb when the mice subjected to the core-null HBV plasmid. These results indicate that the application of mIFNγ in the HBV HI mouse model, the mice showed defective HBcAg-specific immunity that impeded the production of HBcAb and HBsAb, finally allowing the persistence of the virus. Moreover, IFNγ-induced negative immune regulatory factors also play an important role in virus persistence.

Calcitriol ameliorates the progression of hepatic fibrosis through autophagy-related gene 16-like 1-mediated autophagy.

BACKGROUND: Calcitriol has the potential to counteract fibrotic diseases beyond its classical action of maintaining calcium and bone metabolism; however, its functional mechanism remains unknown. Autophagy-related gene 16-like 1 (Atg16l1) is one of the genes related to autophagy and is involved in protecting against fibrotic diseases. The present study aimed to explore the contribution of autophagy to the inhibition of calcitriol-induced hepatic fibrosis, as well as its potential molecular mechanism. METHODS: Carbon tetrachloride (Ccl4)-treated mice were established as hepatic fibrosis models and received calcitriol treatment for 6 weeks. Quantification of Sirius red staining and measurement of key fibrotic markers (collagen-1 and α-SMA) was performed to detect hepatic fibrosis. Chloroquine (CQ) treatment was used to observe autophagic flux, and 3-methyladenine (3-MA) was used to inhibit autophagy. Furthermore, the effects of calcitriol on transforming growth factor ß1 (TGFß1)-stimulated primary hepatic stellate cells (HSCs) were detected. Downregulation of Atg16l1 or vitamin D receptor (VDR) in LX-2 cells was used to explore the mechanism of action of calcitriol in fibrosis and autophagy. Additionally, the electrophoretic mobility shift assay (EMSA) was used to investigate the interactions between VDR and ATG16L1. RESULTS: Calcitriol increased the expression of VDR and ATG16L1, enhanced autophagy and attenuated hepatic fibrosis. 3-MA treatment and VDR silencing abolished the protective effects of calcitriol against fibrosis. Calcitriol-induced anti-fibrosis effects were blocked by ATG16L1 suppression. Furthermore, VDR bound to the ATG16L1 promoter and downregulation of VDR decreased the expression of ATG16L1 in LX-2 cells. CONCLUSION: Calcitriol mitigates hepatic fibrosis partly through ATG16L1-mediated autophagy.

Single-cell transcriptome analysis of aging mouse liver.

Aging has a great impact on the liver, which causes a loss of physiological integrity and an increase in susceptibility to injury, but many of the underlying molecular and cellular processes remain unclear. Here, we performed a comprehensive single-cell transcriptional profiling of the liver during aging. Our data showed that aging affected the cellular composition of the liver. The increase in inflammatory cells including neutrophils and monocyte-derived macrophages, as well as in inflammatory cytokines, could indicate an inflammatory tissue microenvironment in aged livers. Moreover, aging drove a distinct transcriptional course in each cell type. The commonly significant up-regulated genes were S100a8, S100a9, and RNA-binding motif protein 3 across all cell types. Aging-related pathways such as biosynthesis, metabolism, and oxidative stress were up-regulated in aged livers. Additionally, key ligand-receptor pairs for intercellular communication, primarily linked to macrophage migration inhibitory factor, transforming growth factor-ß, and complement signaling, were also elevated. Furthermore, hepatic stellate cells (HSCs) serve as the prominent hub for intrahepatic signaling. HSCs acquired an "activated" phenotype, which may be involved in the increased intrahepatic vascular tone and fibrosis with aging. Liver sinusoidal endothelial cells derived from aged livers were pseudocapillarized and procontractile, and exhibited down-regulation of genes involved in vascular development and homeostasis. Moreover, the aging-related changes in cellular composition and gene expression were reversed by caloric restriction. Collectively, the present study suggests liver aging is linked to a significant liver sinusoidal deregulation and a moderate pro-inflammatory state, providing a potential concept for understanding the mechanism of liver aging.

Autophagy and Senescence: The Molecular Mechanisms and Implications in Liver Diseases.

The liver is the primary organ accountable for complex physiological functions, including lipid metabolism, toxic chemical degradation, bile acid synthesis, and glucose metabolism. Liver function homeostasis is essential for the stability of bodily functions and is involved in the complex regulation of the balance between cell proliferation and cell death. Cell proliferation-halting mechanisms, including autophagy and senescence, are implicated in the development of several liver diseases, such as cholestasis, viral hepatitis, nonalcoholic fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Among various cell death mechanisms, autophagy is a highly conserved and self-degradative cellular process that recycles damaged organelles, cellular debris, and proteins. This process also provides the substrate for further metabolism. A defect in the autophagy machinery can lead to premature diseases, accelerated aging, inflammatory state, tumorigenesis, and cellular senescence. Senescence, another cell death type, is an active player in eliminating premalignant cells. At the same time, senescent cells can affect the function of neighboring cells by secreting the senescence-associated secretory phenotype and induce paracrine senescence. Autophagy can promote and delay cellular senescence under different contexts. This review decodes the roles of autophagy and senescence in multiple liver diseases to achieve a better understanding of the regulatory mechanisms and implications of autophagy and senescence in various liver diseases.

Nicotinamide N-methyltransferase and liver diseases.

Cellular metabolism-induced epigenetic regulation is essential for the maintenance of cellular homeostasis. Nicotinamide N-methyltransferase (NNMT) is emerging as a key point of intersection between cellular metabolism and epigenetic regulation and has a central role in various physiological and pathological processes. NNMT catalyzes the methylation of nicotinamide (NAM) using the universal methyl donor S-adenosyl methionine (SAM) to yield S-adeno-syl-L-homocysteine (SAH) and N1-methylnicotinamide (MNAM), directly linking methylation balance with nicotinamide adenosine dinucleotide (NAD+) contents. NNMT acts on either the SAM-methylation balance or both NAD+ metabolism, depending on the tissue involved or pathological settings where metabolic demand is increased. Under physiological conditions, the liver act as an essential metabolic organ with abundant NNMT expression, while NNMT hepatic function is not mediated by its methyltransferase activity due to other major methyltransferases such as glycine N-methyltransferase (GNMT) in the liver. However, hepatic NNMT, as well as its metabolite is improperly regulated and linked to the worse pathological states in liver diseases, including alcoholic liver disease, non-alcoholic fatty liver disease (NAFLD), liver cirrhosis, and hepatocellular carcinoma (HCC), suggesting a potential role in the process of liver diseases. In this review, we summarize how NNMT regulates cell methylation balance and NAD metabolism, and extensively outline the current knowledge concerning the functions of NNMT in hepatic metabolism including glucose, lipid and energy, with a specific focus on the contribution of NNMT to the pathophysiology of liver-related diseases. NNMT is involved in the development and progression of liver diseases. Understanding the complex NNMT regulatory network and its effects on pathogenesis could provide new therapeutic strategies in the context of liver diseases.

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.

Corrigendum to "Release of Danger Signals during Ischemic Storage of the Liver: A Potential Marker of Organ Damage?"

[This corrects the article DOI: 10.1155/2010/436145.].

Pharmacokinetics, safety and bioequivalence of two formulations of progesterone soft capsule in healthy Chinese postmenopausal females: Impacts of a high-fat meal.

Progesterone is an important natural hormone regulating ovulation and menstruation. The present study aimed to investigate the pharmacokinetics and safety of two formulations of progesterone in Chinese postmenopausal females under fasting and fed conditions. The study adopted a single-dose, open-label, randomized, three-period bioequivalence design. A total of 96 subjects were enrolled and randomly assigned to the fasting cohort or fed cohort. A high-fat meal (890 kcal) was used in the fed study. The reference-scaled average bioequivalence method was used for bioequivalence evaluation. A high-fat meal led to a 22-fold higher peak concentration (Cmax ) and a 7-fold higher area under the curve (AUC) while time to reach Cmax and half-life was not significantly affected. The concentration-time curve displayed double peaks suggesting the existence of enterohepatic circulation. The test/reference geometric mean ratios for Cmax and AUC under fasting and fed conditions are all within the range of 80% to 125%. All adverse events (AEs) that occurred during the trial were mild and did not cause drop-out, though these AEs occurred more frequently under fed state. In conclusion, the two formulations of progesterone are bioequivalent in Chinese subjects under fasting and fed conditions. Drug label modification regarding food effects needs further discussion.

Growth differentiation factor 11 accelerates liver senescence through the inhibition of autophagy.

The "rejuvenating" effect of growth differentiation factor 11 (GDF11) is called into question recently, and its role, as well as plausible signaling mechanisms in liver senescence, is unclear. To overexpress or knockdown GDF11, aged male mice are injected with a single dose of adeno-associated viruses-GDF11 or adenovirus-small hairpin RNA-GDF11, respectively. GDF11 overexpression significantly accelerates liver senescence in aged mice, whereas GDF11 knockdown has opposite effects. Concomitantly, autophagic flux is impaired in livers from GDF11 overexpression mice. Conversely, GDF11 knockdown increases autophagic flux. Moreover, rapamycin successfully restores the impaired autophagic flux and alleviates liver senescence in GDF11 overexpression mice, while the GDF11 knockdown-mediated benefits are abolished by the autophagy inhibitor bafilomycin A1. GDF11 leads to a drop in lysosomal biogenesis resulting in defective autophagic flux at autophagosome clearance step. Mechanistically, GDF11 significantly activates mammalian target of rapamycin complex 1 (mTORC1) and subsequently represses transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy. Inhibition of mTORC1 or TFEB overexpression rescues the GDF11-impaired autophagic flux and cellular senescence. Hepatocyte-specific deletion of GDF11 does not alter serum GDF11 levels and liver senescence. Collectively, suppression of autophagic activity via mTORC1/TFEB signaling may be a critical molecular mechanism by which GDF11 exacerbates liver senescence. Rather than a "rejuvenating" agent, GDF11 may have a detrimental effect on liver senescence.

Effects of Lipopolysaccharide-Binding Protein (LBP) Single Nucleotide Polymorphism (SNP) in Infections, Inflammatory Diseases, Metabolic Disorders and Cancers.

Inflammation, which is induced by the immune response, is recognized as the driving factor in many diseases, including infections and inflammatory diseases, metabolic disorders and cancers. Genetic variations in pivotal genes associated with the immune response, particularly single nucleotide polymorphisms (SNPs), may account for predisposition and clinical outcome of diseases. Lipopolysaccharide (LPS)-binding protein (LBP) functions as an enhancer of the host response to LPS, the main component of the outer membrane of gram-native bacteria. Given the crucial role of LBP in inflammation, we will review the impact of SNPs in the LBP gene on infections and inflammatory diseases, metabolic disorders and cancers.

LBP Protects Hepatocyte Mitochondrial Function Via the PPAR-CYP4A2 Signaling Pathway in a Rat Sepsis Model.

OBJECTIVES: To explore the role of LPS binding protein (LBP) in metabolism and optimize sepsis treatment. DESIGN: A sepsis model was established by injecting LPS into LBP-/- rats and WT rats and observing changes in the liver over time (0, 1, 6, and 24 h). SETTING: Detecting liver inflammation and injury. Optimizing the treatment of sepsis. SUBJECTS: WT rats and LBP-/- rats. INTERVENTIONS: We established a sepsis model by injecting LPS intravenously. MEASUREMENTS AND MAIN RESULTS: First, we induced sepsis in WT and LBP-/- rats with LPS. The rats were sacrificed, and serum and liver samples were collected at 1, 6, and 24 h after LPS injection. We found that the deletion of LBP reduced LPS-induced liver inflammation and injury at 1 and 6 h. Ballooning degeneration was clearly present in LBP-/- rat livers at 24 h after LPS injection. We found that mitochondrial damage and reactive oxygen species (ROS) levels were higher in LBP-/- rat livers than in WT rat livers at 24 h after LPS injection. According to the transcriptomic results, the peroxisome proliferator-activated receptor (PPAR) pathway may be the reason for lesions in LBP-/- rats. To further investigate the function of PPARα in sepsis, we inhibited mTOR with rapamycin and examined mitochondrial injury and ROS levels. The levels of mitochondrial damage and ROS were reduced after LBP-/- rats were pretreated with rapamycin in the context of LPS-induced sepsis. Inhibiting CYP4a2, one of the PPARα-target gene products, reduced the level of LPS-induced ROS in LBP-/- rats. CONCLUSION: LBP protects hepatic mitochondria against LPS-induced damage via the LBP-PPARα-CYP4a2 signaling pathway.

GDF11 impairs liver regeneration in mice after partial hepatectomy.

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor (TGF)-ß superfamily. The rejuvenative effect of GDF11 has been called into question recently, and its role in liver regeneration is unclear. Here, we investigated the pathophysiologic role of GDF11, as well as its plausible signaling mechanisms in a mouse model of partial hepatectomy (PH). We demonstrated that both serum and hepatic GDF11 protein expression increased following PH. Treatment with adeno-associated viruses-GDF11 and recombinant GDF11 protein severely impaired liver regeneration, whereas inhibition of GDF11 activity with neutralizing antibodies significantly improved liver regeneration after PH. In vitro, GDF11 treatment significantly delayed cell proliferation and induced cell-cycle arrest in α mouse liver 12 (AML12) cells. Moreover, GDF11 activated TGF-ß-SMAD2/3 signaling pathway. Inhibition of GDF11-induced SMAD2/3 activity significantly blocked GDF11-mediated reduction in cell proliferation both in vivo and in vitro. In the clinical setting, GDF11 levels were significantly elevated in patients after hepatectomy. Collectively, these results indicate that rather than a 'rejuvenating' agent, GDF11 impairs liver regeneration after PH. Suppression of cell-cycle progression via TGF-ß-SMAD2/3 signaling pathway may be a key mechanism by which GDF11 inhibits liver regeneration.

Young plasma attenuates age-dependent liver ischemia reperfusion injury.

Aging is often associated with a decreased autophagic activity that contributes to the high sensitivity of aged livers to ischemia reperfusion injury (IRI). Blood from young animals can positively affect aged animals. This study was designed to evaluate the effect of young plasma in a model of liver IRI in aged rats. Aged rats were treated with pooled plasma collected from young rats before ischemia. Administration of young plasma restored aging-induced suppression in hepatic autophagic activity and reduced liver IRI. Inhibition of the young-plasma-restored autophagic activity abrogated the beneficial effect of young plasma against liver IRI. Similarly, young serum restored autophagic activity and reduced cellular injury after hypoxia/reoxygenation (H/R) in primary old rat hepatocytes. Mechanistic studies showed thatadministration of young plasma increased AMPK phosphorylation and led to unc-51-like autophagy activating kinase (ULK)1 activation. Furthermore, AMPK-inhibition abrogated the young serum-induced ULK1 activation and autophagic activity and diminished the protective action of young serum against H/R injury in primary old rat hepatocytes, whereas AMPK-activation potentiated the effects of young serum. Young plasma could restore age-impaired autophagy, at least in part, via AMPK/ULK1 signaling. Restoration of age-impaired autophagic activity may be a critical contributing mechanism to young-plasma-afforded protection against liver IRI in aged rats.-Liu, A., Yang, J., Hu, Q., Dirsch, O., Dahmen, U., Zhang, C., Gewirtz, D. A., Fang, H., Sun, J. Young plasma attenuates age-dependent liver ischemia reperfusion injury.

Modulation of Innate Immunity by G-CSF and Inflammatory Response by LBPK95A Improves the Outcome of Sepsis in a Rat Model.

INTRODUCTION: Sepsis is the primary cause of death from infection. We wanted to improve the outcome of sepsis by stimulating innate immunity in combination with modulating the severity of inflammatory responses in rats. METHOD: Sepsis was induced by the injection of feces suspension (control). A 5-day course of G-CSF treatment was given before the septic insult (G-CSF). The inflammatory response was decreased using various doses of the LPS-blocking peptide LBPK95A (5 mg/kg = 100% Combi group, 0.5 mg/kg = 10% Combi group, and 0.05 mg/kg = 1% Combi group). Survival rates were observed. Bacterial clearance, neutrophil infiltration, tissue damage, and the induction of hepatic and systemic inflammatory responses were determined 2 h and 12 h after the septic insult. RESULTS: High-dose LBPK95A (100% Combi) reduced the survival rate to 10%, whereas low-dose LBPK95A (10% and 1% Combi) increased the survival rates to 50% and 80%, respectively. The survival rates inversely correlated with multiorgan damage as indicated by the serum levels of ALT and urea. G-CSF treatment increased the white blood cell counts, hepatic neutrophil infiltration, and bacterial clearance in the liver, lung, and blood. The blockade of the LPS-LBP interaction decreased neutrophil infiltration, led to increased white blood cell count, and decreased hepatic neutrophil infiltration, irrespective of dose. However, bacterial clearance improved in the 1% and 10% Combi groups but worsened in the 100% Combi group. G-CSF increased TNF-α and IL-6 levels. Irrespective of dose, the blockade of the LPS-LBP interaction was associated with low systemic cytokine levels and delayed increases in hepatic TNF-α and IL-6 mRNA expression. The delayed increase in cytokines was associated with the phosphorylation of STAT3 and AKT. CONCLUSION: Our results revealed that increasing innate immunity by G-CSF pretreatment and decreasing inflammatory responses using LBPK95A improved the survival rates in a rat sepsis model and could be a novel strategy to treat sepsis.