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At least 19 records

Lipid accumulation-induced hepatocyte senescence regulates the activation of hepatic stellate cells through the Nrf2-antioxidant response element pathway

Highlights: • Oxidative stress caused by lipid deposition causes hepatocyte senescence. • Free fatty acid-induced senescent hepatocytes promote hepatic stellate cell activation and development of hepatic fibrosis. • Senescent hepatocytes regulate hepatic fibrosis through the Nrf2-antioxidant response element pathway. Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease globally. Elderly individuals are at a higher risk of developing NAFLD with severe clinical outcomes. Although NAFLD is closely related to liver aging, the role of hepatocyte senescence in the progression of NAFLD, especially in the development of fibrosis, is still unclear. The early stage of NAFLD is mainly characterized by lipid accumulation in hepatocytes, which could lead to severe oxidative stress, causing cellular senescence. In the present study, hepatocytes cultured in the presence of free fatty acids to induce lipid deposition were used as a hepatocyte senescence model in vitro. Senescent hepatocytes significantly increased the activation of co-cultured primary hepatic stellate cells (HSCs) and the expression of pro-fibrosis molecules. Moreover, the antioxidant regulator nuclear factor erythroid 2-related factor 2 (Nrf2) that was upregulated in senescent hepatocytes was found to be related to the activation of co-cultured HSCs. The Nrf2 agonist sulforaphane, which upregulated the transcriptional activity of the Nrf2-antioxidant response element (ARE) pathway, remarkably inhibited hepatocyte senescence and its activation effect on HSCs. However, the liver tissue obtained from non-alcoholic steatohepatitis (NASH) mice with Nrf2 knockdown showed decreased antioxidation and significant liver senescence and fibrosis. In conclusion, this study confirmed that lipid accumulation induces hepatocyte senescence, which leads to HSC activation and development of hepatic fibrosis. Increasing the activity of the Nrf2-ARE antioxidant pathway in senescent hepatocytes elicited the opposite effect, suggesting that targeting Nrf2 may prevent or delay the progression of aging-related liver fibrosis in NASH.

60 APPLIED LIFE SCIENCES↗

Genotoxicity evaluation using primary hepatocytes isolated from rhesus macaque ( Macaca mulatta )

Non-human primates (NHPs) have played a vital role in fundamental, pre-clinical, and translational studies because of their high physiological and genetic similarity to humans. We report a method to isolate primary hepatocytes from the livers of rhesus macaques (Macaca mulatta) after in situ whole liver perfusion. Isolated primary macaque hepatocytes (PMHs) were treated with various compounds known to have different pathways of genotoxicity/carcinogenicity and the resulting DNA damage was evaluated using the high-throughput CometChip assay. The comet data were quantified using benchmark dose (BMD) modeling and the BMD50 values for treatments of PMHs were compared with those generated from primary human hepatocytes (PHHs) in our previous study. The results showed that despite varying CYP450 enzyme activities, PMHs had the same sensitivity and specificity as PHHs in detecting four indirect-acting (i.e., requiring metabolic activation) and seven direct-acting genotoxicants/carcinogens, as well as five non-carcinogens that are negative or equivocal for genotoxicity in vivo. The BMD50 estimates and their confidence intervals revealed species differences for DNA damage potency, especially for direct-acting compounds. The present study provides a practical method for maximizing the use of animal tissues by isolating primary hepatocytes from NHPs. Our data support the use of PMHs as a reliable surrogate of PHHs for evaluating the genotoxic hazards of chemical substances for humans.

59 BASIC BIOLOGICAL SCIENCES↗

Src-mediated Tyr353 phosphorylation of IP3R1 promotes its stability and causes apoptosis in palmitic acid-treated hepatocytes

Palmitic acid (PA)-induced hepatocyte apoptosis is critical for the progression of nonalcoholic fatty liver disease (NAFLD). Inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) is an intracellular Ca{sup 2+}-release channel and is involved in PA-induced hepatocyte apoptosis. While the expression of IP3R1 is elevated in patients with NAFLD and in hepatocytes treated with PA, it remains unclear how PA promotes the expression of IP3R1. In present study, our results showed that PA induced mitochondrial dysfunction and apoptosis, which is accompanied with the increase of the IP3R1 expression in hepatic cells. The inhibition of IP3R1 expression using siRNA ameliorated the PA-induced mitochondrial dysfunction. Furthermore, PA enhanced the stability of the IP3R1 protein instead of an increase in its mRNA levels. PA also promoted the phosphorylation of IP3R1 at the Tyr353 site and increased the phosphorylation of src in hepatic cells. Moreover, an inhibitor of src kinase (SU6656) significantly reduced the Tyr353 phosphorylation of IP3R1 and decreased its stability. In addition, SU6656 improved mitochondrial function and reduced apoptosis in hepatocytes. Conclusion: PA promotes the Tyr353 phosphorylation of IP3R1 by activating the src pathway and increasing the protein stability of IP3R1, which consequently results in mitochondrial Ca{sup 2+} overload and mitochondrial dysfunction in hepatic cells. Our results also suggested that inhibition of the src/IP3R1 pathway, such as by SU6656, may be a novel potential therapeutic approach for the treatment of NAFLD.

60 APPLIED LIFE SCIENCES↗

Hepatitis B e Antigen-Negative Single Hepatocyte Analysis Shows Transcriptional Silencing and Slow Decay of Infected Cells With Treatment

Background Nucleos(t)ide analogues (NUCs) rarely cure chronic hepatitis B (CHB) because they do not eliminate covalently closed circular deoxyribonucleic acid, the stable replication template. In hepatitis B e antigen (HBeAg)-positive CHB during NUCs, HBV-infected cells decline slowly and are transcriptionally silenced. Whether these occur in HBeAg-negative CHB is unknown. Methods Using paired liver biopsies separated by 2.7–3.7 years in 4 males with HIV and HBeAg-negative CHB at both biopsies and 1 male with HIV who underwent HBeAg seroconversion between biopsies, we quantified amounts of viral nucleic acids in hundreds of individual hepatocytes. Results In the 4 persistently HBeAg-negative participants, HBV-infected hepatocytes ranged from 6.2% to 17.7% (biopsy 1) and significantly declined in 3 of 4 by biopsy 2. In the HBeAg seroconverter, the proportion was 97.4% (biopsy 1) and declined to 81.9% at biopsy 2 (P < .05). Here, we extrapolated that HBV eradication with NUCs would take >100 years. At biopsy 1 in the persistently HBeAg-negative participants, 23%–56.8% of infected hepatocytes were transcriptionally inactive—higher than we observed in HBeAg-positive CHB—and significantly declined in 1 of 4 at biopsy 2. Conclusions In HBeAg-negative CHB on NUCs, the negligible decline in infected hepatocytes is similar to HBeAg-positive CHB, supporting the need for more potent therapeutics to achieve functional cure.

59 BASIC BIOLOGICAL SCIENCES↗

Single hepatocytes show persistence and transcriptional inactivity of hepatitis B

There is no cure for the more than 270 million people chronically infected with HBV. Nucleos(t)ide analogs (NUCs), the mainstay of anti-HBV treatment, block HBV reverse transcription. NUCs do not eliminate the intranuclear covalently closed circular DNA (cccDNA), from which viral RNAs, including pregenomic RNA (pgRNA), are transcribed. A key gap in designing a cure is understanding how NUCs affect HBV replication and transcription because serum markers yield an incomplete view of intrahepatic HBV. We applied single-cell laser capture microdissection and droplet digital PCR to paired liver biopsies collected from 5 HBV/HIV-coinfected persons who took NUCs over 2–4 years. From biopsy 1 to 2, proportions of HBV-infected hepatocytes declined with adherence to NUC treatment (P < 0.05); we extrapolated that eradication of HBV will take over 10 decades with NUCs in these participants. In individual hepatocytes, pgRNA levels diminished 28- to 73-fold during NUC treatment, corresponding with decreased tissue HBV core antigen staining (P < 0.01). In 4 out of 5 participants, hepatocytes with cccDNA but undetectable pgRNA (transcriptionally inactive) were present, and these were enriched in 3 participants during NUC treatment. Further work to unravel mechanisms of cccDNA transcriptional inactivation may lead to therapies that can achieve this in all hepatocytes, resulting in a functional cure.

59 BASIC BIOLOGICAL SCIENCES↗

Astragaloside IV improved antioxidative stress capacity and related gene expression of the Keap1‐Nrf2 pathway in grass carp ( Ctenopharyngodon idella ) hepatocytes under heat stress

Abstract This study aims to investigate the protective effects of astragaloside IV (AS‐IV) on the hepatocytes of grass carp ( Ctenopharyngodon idella ) on heat stress. Cultured cells were treated with AS‐IV (0, 50, 100 and 200 μg/ml) at 28°C for 24 h and then exposed to heat stress by increasing the culturing temperature (32 ± 0.5°C) for 6 h. The increased temperatures significantly reduced cell viability and superoxide dismutase (SOD) activity, and increased malondialdehyde (MDA) levels in the 0 μg/ml AS‐IV treatment group at 32°C, but the grass carp hepatocytes treated with 100 and 200 μg/ml AS‐IV had significantly increased cell viability and SOD activity and decreased MDA levels. The mRNA levels of keap1a , keap1b , nrf2 , gsh‐px , cat , cu‐zn sod , mgst1 and il‐6 were significantly lower in the 0 μg/ml AS‐IV treatment group at 32°C, while those of keap1a , nrf2 , gsh‐px , cat , cu‐zn sod , gstp1 , ho‐1 and il‐6 were significantly higher in cells treated with 100 or 200 μg/ml AS‐IV. Our findings indicate that AS‐IV could enhance the antioxidative stress capacity of grass carp hepatocytes under heat stress, and its mechanism may be associated with the activation of the Keap1‐Nrf2 pathway. Thus, these results provide new insights into how to alleviate heat stress in grass carp.

Liu, Hua↗

Hepatocellular Metabolic Profile: Understanding Post-Thawing Metabolic Shift in Primary Hepatocytes In Vitro

Primary human hepatocytes (PHHs) are widely used as in vitro models for liver function and drug metabolism studies, yet their metabolic stability post-thawing remains an open question. To better characterize early metabolic changes, we conducted a time-course experiment using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze metabolic shifts in PHHs cultured in suspension. Unexposed and exposed (acetaminophen-treated) samples were evaluated, and TITAN analysis was applied to determine the time point of maximal metabolic change at both individual metabolite and global metabolic profile levels. Our results indicate that the majority of metabolic shifts occur within the first five hours post-thawing. In the early culture time points, substantial metabolic overlap was observed between unexposed and exposed cells, suggesting a conserved biological response likely related to cellular recovery. However, at later time points, metabolite profiles diverged, with acetaminophen treatment-specific metabolic changes emerging, potentially reflecting differences in homeostatic restoration versus hepatotoxic responses. Our study highlights the importance of considering early post-thawing metabolic dynamics in experimental design and offers insights for optimizing hepatocyte culture protocols to better replicate in vivo physiological conditions.

59 BASIC BIOLOGICAL SCIENCES↗

Modeling of hepatitis B virus infection spread in primary human hepatocytes

ABSTRACT Chronic hepatitis B virus (HBV) infection poses a significant global health threat, causing severe liver diseases including cirrhosis and hepatocellular carcinoma. We characterized HBV DNA kinetics in primary human hepatocytes (PHHs) over 32 days post-inoculation (p.i.) and modified ourin-vivoagent-based modeling (ABM) to gain insights into the HBV lifecycle and spreadin vitro. Parallel PHH cultures were mock-treated or treated with HBV entry inhibitor Myr-preS1 (6.25 µg/mL) was initiated 24 h p.i. In untreated PHH, three viral DNA kinetic patterns were identified: (i) an initial decline, followed by (ii) rapid amplification and (iii) slower amplification/accumulation. In the presence of Myr-preS1, viral DNA and infected cell numbers in phase 3 were effectively blocked, with minimal to no increase. This suggests that phase 2 represents viral amplification in initially infected cells, while phase 3 corresponds to viral spread to naïve cells. The ABM reproduced well the HBV kinetic patterns observed and predicted that the viral eclipse phase lasts between 18 and 38 h. After the eclipse phase, the viral production rate increased over time, starting with a slow production cycle of 1 virion per day, which gradually accelerated to 1 virion per hour after 3 days. Approximately 4 days later, virion production reached a steady state production rate of 4 virions/h. The estimated median efficacy of Myr-preS1 in blocking HBV spread was 91% (range: 90–92%). The HBV kinetics and the predicted estimates of the HBV eclipse phase duration and HBV production cycles in PHH are similar to those predicted in uPA/SCID mice with human livers. IMPORTANCE While primary human hepatocytes (PHHs) are the most physiologically relevant culture system for studying HBV infectionin vitro, a comprehensive understanding of HBV infection kinetics and spread in PHH is lacking. In this study, we characterize HBV viral kinetics and modify ourin vivoagent-based modeling (ABM) to provide quantitative insights into the HBV production cycle and viral spread in PHH. The ABM provides an estimate of the HBV eclipse phase duration, HBV production cycles, and Myr-preS1 efficacy in blocking HBV spread in PHH. The results resemble those predicted in uPA/SCID mice with human livers, demonstrating that estimated HBV infection kinetic parameters in PHHin vitromirror those observed in thein vivoHBV infection chimeric mouse model.

Virology↗

Comprehensive characterization of hepatocyte-derived extracellular vesicles identifies direct miRNA-based regulation of hepatic stellate cells and DAMP-based hepatic macrophage IL-1ß and IL-17 upregulation in alcoholic hepatitis mice.

Extracellular vesicles (EVs) have been growingly recognized as biomarkers and mediators of alcoholic liver disease (ALD) in human and mice. Here we characterized hepatocyte-derived EVs (HC-EVs) and their cargo for their biological functions in a novel murine model that closely resembles liver pathology observed in patients with alcoholic hepatitis (AH), the most severe spectrum of ALD. The number of circulating EVs and HC-EVs were significantly increased by 10-fold in AH mice compared to control mice. The miRNA(miR)-seq analysis detected 20 up-regulated and 4 down-regulated miRNAs (P < 0.001-0.05) in AH-HC-EVs. Treatment of murine primary hepatic stellate cells (HSCs) with AH-HC-EVs induced ?-SMA (P < 0.05) and Col1a1 (P < 0.001). Smad7, Nr1d2, and Rora genes which regulate HSC activation were predicted targets of 17 miRs up-regulated in AH-HC-EVs. Among them were miR-27a and miR-181 which upon transfection in HSCs, repressed Nr1d2, the HSC quiescence marker. AH-HC-EVs were also enriched in organelle proteins and mitochondrial DNA (10-fold, P < 0.05) and upregulated IL-1??and IL-17 production by hepatic macrophages (HMs) from AH mice in a TLR9-dependent manner. These results demonstrate HC-EV release is intensified in AH and suggest that AH-HC-EVs orchestrate liver fibrogenesis by directly targeting HSC quiescence transcripts via a unique set of miRNAs and by amplifying HSC activation via DAMP-based induction of profibrogenic IL-1? and IL-17 by HMs.

AH, hepatocyte-derived EVs, miRNAs, DAMPs, HSC act↗

Suppression of hepatitis B virus through therapeutic activation of RIG-I and IRF3 signaling in hepatocytes

Hepatitis B virus (HBV) mediates persistent infection, chronic hepatitis, and liver disease. HBV covalently closed circular (ccc)DNA is central to viral persistence such that its elimination is considered the cornerstone for HBV cure. Inefficient detection by pathogen recognition receptors (PRRs) in the infected hepatocyte facilitates HBV persistence via avoidance of innate immune activation and interferon regulatory factor (IRF)3 induction of antiviral gene expression. We evaluated a small molecule compound, F7, and 5'-triphosphate-poly-U/UC pathogen-associated-molecular-pattern (PAMP) RNA agonists of RIG-I, a PRR that signals innate immunity, for ability to suppress cccDNA. F7 and poly-U/UC PAMP treatment of HBV-infected cells induced RIG-I signaling of IRF3 activation to induce antiviral genes for suppression of cccDNA formation and accelerated decay of established cccDNA, and were additive to the actions of entecavir. Our study shows that activation of the RIG-I pathway and IRF3 to induce innate immune actions offers therapeutic benefit toward elimination of cccDNA.

60 APPLIED LIFE SCIENCES↗

Enantioselectivity of Pentedrone and Methylone on Metabolic Profiling in 2D and 3D Human Hepatocyte-like Cells

Pentedrone and methylone can express stereoselectivity in toxicokinetic and toxicodynamic processes. Similarly, their chiral discrimination in metabolism, which was not yet evaluated, can result in different metabolic profiles and subsequent hepatotoxic effects. Therefore, the aim of this work was to assess, for the first time, both the hepatic cytotoxic and metabolic profile of pentedrone and methylone enantiomers using physiologically relevant in vitro models. The hepatotoxicity of these compounds was observed in a concentration-dependent manner in human stem-cell-derived hepatocyte-like cells (HLCs) cultured under 3D (3D-HLCs) and 2D (2D-HLCs) conditions. Enantioselectivity, on the other hand, was only shown for pentedrone (1 mM) in 3D-HLCs, being R-(−)-pentedrone the most cytotoxic. Furthermore, the metabolic profile was initially evaluated in human liver microsomes (HLM) and further demonstrated in 3D-HLCs and 2D-HLCs applying a gas chromatography coupled to a mass spectrometer (GC–MS) technique. Methylone and pentedrone showed distinct and preferential metabolic routes for their enantiomers, resulting in the production of differentiated metabolites; R-(+)-methylone and R-(−)-pentedrone are the most metabolized enantiomers. In conclusion, the results demonstrated enantioselectivity for pentedrone and methylone in the metabolic processes, with enantioselectivity in cytotoxicity for pentedrone.

Silva, Bárbara (ORCID:0000000173990197)↗

Second-Phase Hepatitis C Plasma Viral Kinetics Directly Reflects Reduced Intrahepatic Burden of Hepatitis C Virus

Mathematical models explain how antivirals control viral infections. Hepatitis C virus (HCV) treatment results in at least 2 phases of decline in viremia. Here, the first phase reflects clearance of rapidly produced virions. The second phase is hypothesized to derive from loss of infected cells but has been challenging to prove. Using single-cell methods, we quantified the number of hepatitis C virus (HCV)-infected hepatocytes in liver biopsies taken before and within 7 days of initiating direct-acting antivirals (DAAs) in a double-blinded randomized controlled trial testing 2 (sofosbuvir-velpatasvir) versus 3 (sofosbuvir-velpatasvir-voxilaprevir) DAAs. We employed thousands of intrahepatic measurements in 10 persons with chronic genotype 1a HCV infection: median proportion of infected hepatocytes declined from 11.3% (range, 1.3%–59%) to 0.6% (range, <0.3%–5.8%), a loss of 75%–95% infected hepatocytes. Plasma viremia correlated with numbers of HCV-infected hepatocytes (r = 0.77; P < .0001). Second-phase plasma dynamics and changes in infected hepatocytes were indistinct (P = .16), demonstrating that second-phase viral dynamics derive from loss of infected cells. DAAs led to a decline in intracellular HCV RNA and interferon-stimulated gene expression (P < .05 for both). We proved that second-phase viral dynamics reflect decay of intrahepatic burden of HCV, partly due to clearance of HCV RNA from hepatocytes.

59 BASIC BIOLOGICAL SCIENCES↗

Antiretroviral therapy for HIV and intrahepatic hepatitis C virus replication

HIV alters host responses to hepatitis C virus (HCV). However, the impact of antiretroviral therapy (ART) on HCV is rarely understood in relevant tissues and never before within individual hepatocytes. HIV and HCV kinetics were studied before and after ART initiation among 19 HIV/HCV co-infected persons. From five persons with the largest decline in plasma HCV RNA, liver tissues collected before and during ART, when plasma HIV RNA was undetectable, were studied. Here we used single-cell laser capture microdissection and quantitative PCR to assess intrahepatic HCV. Immunohistochemistry was performed to characterize intrahepatic immune cell populations. Plasma HCV RNA declined by 0.81 (0.52–1.60) log 10 IU/ml from a median (range) 7.26 (6.05–7.29) log 10 IU/ml and correlated with proportions of HCV-infected hepatocytes (r = 0.89, P = 2 × 10 -5 ), which declined from median (range) of 37% (6–49%) to 23% (0.5–52%) after plasma HIV clearance. Median (range) HCV RNA abundance within cells was unchanged in four of five participants. Liver T-cell abundance unexpectedly decreased, whereas natural killer (NK) and NK T-cell infiltration increased, correlating with changes in proportions of HCV-infected hepatocytes (r = -0.82 and r = -0.73, respectively). Hepatocyte expression of HLA-E, an NK cell restriction marker, correlated with proportions of HCV-infected hepatocytes (r = 0.79). These are the first data to show that ART control of HIV reduces the intrahepatic burden of HCV. Furthermore, our data suggest that HIV affects the pathogenesis of HCV infection by an NK/NK T-cell-mediated mechanism that may involve HLA-E and can be rescued, at least in part, by ART.

60 APPLIED LIFE SCIENCES↗

A Long Non-coding RNA, LOC157273, Is an Effector Transcript at the Chromosome 8p23.1-PPP1R3B Metabolic Traits and Type 2 Diabetes Risk Locus

Causal transcripts at genomic loci associated with type 2 diabetes (T2D) are mostly unknown. The chr8p23.1 variant rs4841132, associated with an insulin-resistant diabetes risk phenotype, lies in the second exon of a long non-coding RNA (lncRNA) gene, LOC157273, located 175 kilobases from PPP1R3B, which encodes a key protein regulating insulin-mediated hepatic glycogen storage in humans. We hypothesized that LOC157273 regulates expression of PPP1R3B in human hepatocytes. We tested our hypothesis using Stellaris fluorescent in situ hybridization to assess subcellular localization of LOC157273; small interfering RNA (siRNA) knockdown of LOC157273, followed by RT-PCR to quantify LOC157273 and PPP1R3B expression; RNA-seq to quantify the whole-transcriptome gene expression response to LOC157273 knockdown; and an insulin-stimulated assay to measure hepatocyte glycogen deposition before and after knockdown. We found that siRNA knockdown decreased LOC157273 transcript levels by approximately 80%, increased PPP1R3B mRNA levels by 1.7-fold, and increased glycogen deposition by >50% in primary human hepatocytes. An A/G heterozygous carrier (vs. three G/G carriers) had reduced LOC157273 abundance due to reduced transcription of the A allele and increased PPP1R3B expression and glycogen deposition. We show that the lncRNA LOC157273 is a negative regulator of PPP1R3B expression and glycogen deposition in human hepatocytes and a causal transcript at an insulin-resistant T2D risk locus.

59 BASIC BIOLOGICAL SCIENCES↗

Integrated Transcriptomic and Proteomic Analysis Identifies Plasma Biomarkers of Hepatocellular Failure in Alcohol-Associated Hepatitis

Alcohol-associated hepatitis (AH) is a form of liver failure with high short-term mortality. Recent results have shown that HNF4a defective function and systemic inflammation are major disease drivers of AH. Plasma biomarkers of hepatocyte function could be useful for diagnostic and prognostic purposes. Herein an integrative analysis of hepatic RNAseq and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed to identify plasma protein signatures for mild and severe AH patients. Alcohol-related liver disease cirrhosis (ALD)(AC), non-alcoholic fatty liver disease (NALFD), and healthy subjects (HC) were used as comparator groups. Identified proteins primarily involved in hepatocellular function were decreased in AH patients which included hepatokines, clotting factors, complement cascade components, and hepatocyte growth activators. A protein signature of AH disease severity was identified including thrombin (THRB), hepatocyte growth factor alpha (HGFA), clusterin (CLUS), human serum factor H-related protein (FHR1) and kallistatin (KAIN), which exhibited large abundance shifts between severe and non-severe AH. The combination of THRB and HGFA discriminated between severe and non-severe AH with high sensitivity and specificity. These findings were correlated with the liver expression of genes encoding secreted proteins in a similar cohort, finding a highly consistent plasma protein signature reflecting HNF4A and HNF1A functions. This unbiased proteomic-transcriptome analysis identified plasma protein signatures and pathways associated with disease severity, reflecting HNF4A/1A activity useful for diagnostic assessment in AH.

60 APPLIED LIFE SCIENCES↗