Surface Of Hepatocytes Research Articles

Reduction of Cardiovascular Risk Using Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors in Patients With Acute Coronary Syndrome: A Systematic Review.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a hepatic enzyme that regulates blood cholesterol levels by degrading low-density lipoprotein (LDL) receptors from the surface of hepatocytes. Studies have shown that inhibiting this molecule decreases the cardiovascularrisk in individuals with atherosclerotic cardiovascular disease (ASCVD)by lowering low-density lipoprotein cholesterol (LDL-C). Two major cardiovascular outcome trials showed that the use of the PCSK9 inhibitors (alirocumab and evolocumab) in patients with recent acute coronary syndrome (ACS) is associated with a lower risk of further cardiovascular (CV) events. Information regarding the use of these monoclonal antibodies for primary prevention has also been reported by these trials. The goal of this systematic review is to describe the mechanism of PCSK9 inhibitors and further discuss their ability to reduce CV risk in high-risk populations. The search strategy was used in a systematic way using PubMed Central, Google Scholar, and ScienceDirect. We included randomized control trials (RCTs), systematic reviews, and narrative reviews in English published in the last five years. Observational studies,case reports, and case studies were excluded. The quality of the studies was evaluated using the Cochrane Collaboration Risk of Bias Tool, Assessment of Multiple Systematic Reviews 2, and Scale for the Assessment of Narrative Review Articles. A total of 10 articles were included in this systematic review. These included an RCT, a systematic review, and eight narrative reviews. Our study suggested that adding PCSK9 inhibitors to background statin therapy for selected patients with high-risk factors demonstrated substantial benefits in reducing overall CV morbidity and mortality after ACS. Multiple studies have demonstrated the short-term safety of low LDL-C levels caused by these drugs. However, long-term safety must be assessed with further studies.

Melatonin alleviates alcoholic liver disease via EGFR–BRG1–TERT axis regulation

Chronic alcohol consumption causes liver steatosis, cell death, and inflammation. Melatonin (MLT) is reported to alleviate alcoholic liver disease (ALD)-induced injury. However, its direct regulating targets in hepatocytes are not fully understood. In the current study, a cell-based screening model and a chronic ethanol-fed mice ALD model were used to test the protective mechanisms of MLT. MLT ameliorated ethanol-induced hepatocyte injury in both cell and animal models (optimal doses of 10μmol/L and 5mg/kg, respectively), including lowered liver steatosis, cell death, and inflammation. RNA-seq analysis and loss-of-function studies in AML-12cells revealed that telomerase reverse transcriptase (TERT) was a key downstream effector of MLT. Biophysical assay found that epidermal growth factor receptor (EGFR) on the hepatocyte surface was a direct binding and regulating target of MLT. Liver specific knock-down of Tert or Egfr in the ALD mice model impaired MLT-mediated liver protection, partly through the regulation of nuclear brahma-related gene-1 (BRG1). Long-term administration (90 days) of MLT in healthy mice did not cause evident adverse effect. In conclusion, MLT is an efficacious and safe agent for ALD alleviation. Its direct regulating target in hepatocytes is EGFR and downstream BRG1-TERT axis. MLT might be used as a complimentary agent for alcoholics.

Cargo-Specific Role for Retriever Subunit VPS26C in Hepatocyte Lipoprotein Receptor Recycling to Control Postprandial Triglyceride-Rich Lipoproteins.

The copper metabolism MURR1 domains/coiled-coil domain containing 22/coiled-coil domain containing 93 (CCC) complex is required for the transport of low-density lipoprotein receptor (LDLR) and LRP1 (LDLR-related protein 1) from endosomes to the cell surface of hepatocytes. Impaired functioning of hepatocytic CCC causes hypercholesterolemia in mice, dogs, and humans. Retriever, a protein complex consisting of subunits VPS26C, VPS35L, and VPS29, is associated with CCC, but its role in endosomal lipoprotein receptor transport is unclear. We here investigated the contribution of retriever to hepatocytic lipoprotein receptor recycling and plasma lipids regulation. Using somatic CRISPR/Cas9 gene editing, we generated liver-specific VPS35L or VPS26C-deficient mice. We determined total and surface levels of LDLR and LRP1 and plasma lipids. In addition, we studied the protein levels and composition of CCC and retriever. Hepatocyte VPS35L deficiency reduced VPS26C levels but had minimal impact on CCC composition. VPS35L deletion decreased hepatocytic surface expression of LDLR and LRP1, accompanied by a 21% increase in plasma cholesterol levels. Hepatic VPS26C ablation affected neither levels of VPS35L and CCC subunits, nor plasma lipid concentrations. However, VPS26C deficiency increased hepatic LDLR protein levels by 2-fold, probably compensating for reduced LRP1 functioning, as we showed in VPS26C-deficient hepatoma cells. Upon PCSK9 (proprotein convertase subtilisin/kexin type 9)-mediated LDLR elimination, VPS26C ablation delayed postprandial triglyceride clearance and increased plasma triglyceride levels by 26%. Our study suggests that VPS35L is shared between retriever and CCC to facilitate LDLR and LRP1 transport from endosomes to the cell surface. Conversely, retriever subunit VPS26C selectively transports LRP1, but not LDLR, and thereby may control hepatic uptake of postprandial triglyceride-rich lipoprotein remnants.

Hepatocyte-targeting and tumor microenvironment-responsive liposomes for enhanced anti-hepatocarcinoma efficacy

To increase the antitumor drug concentration in the liver tumor site and improve the therapeutic effects, a functionalized liposome (PPP-LIP) with tumor targetability and enhanced internalization after matrix metalloproteinase-2 (MMP2)-triggered cell-penetrating peptide (TATp) exposure was modified with myrcludex B (a synthetic HBV preS-derived lipopeptide endowed with compelling liver tropism) for liver tumor-specific delivery. After intravenous administration, PPP-LIP was mediated by myrcludex B to reach the hepatocyte surface. The MMP2-overexpressing tumor microenvironment deprotected PEG, exposing it to TATp, facilitating tumor penetration and subsequent efficient destruction of tumor cells. In live imaging of small animals and cellular uptake, PPP-LIP was taken up much more than typical unmodified liposomes in the ICR mouse liver and liver tumor cells. Hydroxycamptothecin (HCPT)-loaded PPP-LIP showed a better antitumor effect than commercially available HCPT injections among MTT, three-dimensional (3 D) tumor ball, and tumor-bearing nude mouse experiments. Our findings indicated that PPP-LIP nanocarriers could be a promising tumor-targeted medication delivery strategy for treating liver cancers with elevated MMP2 expression.

SEMA7AR148W mutation promotes lipid accumulation and NAFLD progression via increased localization on the hepatocyte surface.

Genetic polymorphisms are associated with the development of nonalcoholic fatty liver disease (NAFLD). Semaphorin7a (Sema7a) deficiency in mouse peritoneal macrophages reduces fatty acid (FA) oxidation. Here, we identified 17 individuals with SEMA7A heterozygous mutations in 470 patients with biopsy-proven NAFLD. SEMA7A heterozygous mutations increased susceptibility to NAFLD, steatosis severity, and NAFLD activity scores in humans and mice. The Sema7aR145W mutation (equivalent to human SEMA7AR148W) significantly induced small lipid droplet accumulation in mouse livers compared with WT mouse livers. Mechanistically, the Sema7aR145W mutation increased N-glycosylated Sema7a and its receptor integrin β1 proteins in the cell membranes of hepatocytes. Furthermore, Sema7aR145W mutation enhanced its protein interaction with integrin β1 and PKC-α and increased PKC-α phosphorylation, which were both abrogated by integrin β1 silencing. Induction of PKCα_WT, but not PKCα_dominant negative, overexpression induced transcriptional factors Srebp1, Chrebp, and Lxr expression and their downstream Acc1, Fasn, and Cd36 expression in primary mouse hepatocytes. Collectively, our findings demonstrate that the SEMA7AR148W mutation is a potentially new strong genetic determinant of NAFLD and promotes intrahepatic lipid accumulation and NAFLD in mice by enhancing PKC-α–stimulated FA and triglyceride synthesis and FA uptake. The inhibition of hepatic PKC-α signaling may lead to novel NAFLD therapies.

Construction of polysaccharide scaffold-based perfusion bioreactor supporting liver cell aggregates for drug screening

Rebuilding a suitable microenvironment of liver cells is the key challenge to enhancing the expression of hepatic functions for drug screening in vitro. To improve the microenvironment by providing the specific adhesive ligands for hepatocytes in the three-dimensional dynamic culture, a perfusion bioreactor with a pectin/alginate blend porous scaffold was constructed in this study. The galactosyl component in the main chain of pectin was able to be specifically recognized by the asialoglycoprotein receptor on the surface of hepatocytes, and subsequently promoted the adhesion and aggregation of hepatocytes co-cultured with hepatic non-parenchymal cells. The bioreactor was optimized for 4 h of dynamic inoculation followed by perfusion at a flow rate of 2 mL/min, which provided adequate oxygen supply and good mass transfer to the liver cells. During dynamic cultured in the bioreactor for 14 days, more multicellular aggregates were formed and were evenly distributed in the pectin/alginate blend scaffolds. The expressions of intercellular interaction and hepatic functions of the hepatocytes in aggregates were significantly enhanced in the three-dimensional dynamic group. Furthermore, the bioreactor not only markedly upregulated the cell polarity markers expression of hepatocytes but also enhanced their metabolic capacity to acetaminophen, isoniazid, and tolbutamide, which exhibited a significant concentration-dependent manner. Therefore, the pectin/alginate blend scaffold-based perfusion bioreactor appeared to be a promising candidate in the field of drug development and liver regeneration research.

Deciphering signal transduction networks in the liver by mechanistic mathematical modelling.

In health and disease, liver cells are continuously exposed to cytokines and growth factors. While individual signal transduction pathways induced by these factors were studied in great detail, the cellular responses induced by repeated or combined stimulations are complex and less understood. Growth factor receptors on the cell surface of hepatocytes were shown to be regulated by receptor interactions, receptor trafficking and feedback regulation. Here, we exemplify how mechanistic mathematical modelling based on quantitative data can be employed to disentangle these interactions at the molecular level. Crucial is the analysis at a mechanistic level based on quantitative longitudinal data within a mathematical framework. In such multi-layered information, step-wise mathematical modelling using submodules is of advantage, which is fostered by sharing of standardized experimental data and mathematical models. Integration of signal transduction with metabolic regulation in the liver and mechanistic links to translational approaches promise to provide predictive tools for biology and personalized medicine.

Abstract 452: Classification And Effect Of Correctors On ABCG8 Sitosterolemia Associated Cytosolic Mutants

Background: Sitosterolemia is a rare form of Familial Hypercholesterolemia (FH) which is unique from other forms of FH due to the accumulation of phytosterols in the plasma and tissues. Sitosterolemia is autosomal recessive and caused by mutations in either the ABCG5 or ABCG8 gene. ABCG5 and ABCG8 form a heterodimer (ABCG5/ABCG8) that functions at the apical surface of hepatocytes and enterocytes to promote cholesterol and phytosterol excretion. Small molecule modulators classified as either correctors or potentiators have therapeutic benefit when used to treat mutants of ABCB4 (PFIC3) or ABCC7 (Cystic Fibrous) that have impaired folding, stability, or activity. There are over 40 missense mutations in ABCG5/ABCG8 which have been clinically confirmed in patients with Sitosterolemia. Methods: We developed a classification system for ABCG5 and ABCG8 mutations based on the underlying molecular defect for ABCG5/ABCG8 dysfunction (maturation, trafficking, activity, etc.). We used site directed mutagenesis to introduce ABCG8 missense mutations located in the N-terminal, cytosolic domain of human ABCG8. Normal and mutant ABCG5/ABCG8 constructs were transiently transfected into a human hepatocyte cell line, Huh-7, and analyzed for heterodimerization, trafficking beyond the ER, and localization at the cell surface. Results: Of the ABCG8 cytosolic mutants studied, R184H, L196Q, L228P, and R263Q failed to traffic beyond the ER to form a stable heterodimer (class II) while P231T, T400K, N409D, N409I, and P415H were trafficking competent. Conclusions: Forty four percent (4 of 9) of cytosolic, ABCG8 mutations that cause Sitosterolemia are due to failures in complex formation and trafficking beyond the ER. Fifty six (5 of 9) percent were trafficking competent, indicating a stable ABCG5/G8 complex, but loss of activity due to impaired ATP hydrolysis or substrate binding. ABCG8 mutants may be potentially restored by proteostatic regulators and/or potentiators & correctors that have shown to be effective in disease-causing mutations in other ABC transporters.

Insight into the Evolving Role of PCSK9.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is the last discovered member of the family of proprotein convertases (PCs), mainly synthetized in hepatic cells. This serine protease plays a pivotal role in the reduction of the number of low-density lipoprotein receptors (LDLRs) on the surface of hepatocytes, which leads to an increase in the level of cholesterol in the blood. This mechanism and the fact that gain of function (GOF) mutations in PCSK9 are responsible for causing familial hypercholesterolemia whereas loss-of-function (LOF) mutations are associated with hypocholesterolemia, prompted the invention of drugs that block PCSK9 action. The high efficiency of PCSK9 inhibitors (e.g., alirocumab, evolocumab) in decreasing cardiovascular risk, pleiotropic effects of other lipid-lowering drugs (e.g., statins) and the multifunctional character of other proprotein convertases, were the cause for proceeding studies on functions of PCSK9 beyond cholesterol metabolism. In this article, we summarize the current knowledge on the roles that PCSK9 plays in different tissues and perspectives for its clinical use.

Recent Advances in Glycyrrhetinic Acid-Functionalized Biomaterials for Liver Cancer-Targeting Therapy.

Liver cancer is one of the most common causes of cancer mortality worldwide. Chemotherapy and radiotherapy are the conventional therapies generally employed in patients with liver tumors. The major issue associated with the administration of chemotherapeutics is their high toxicity and lack of selectivity, leading to systemic toxicity that can be detrimental to the patient’s quality of life. An important approach to the development of original liver-targeted therapeutic products takes advantage of the employment of biologically active ligands able to bind specific receptors on the cytoplasmatic membranes of liver cells. In this perspective, glycyrrhetinic acid (GA), a pentacyclic triterpenoid present in roots and rhizomes of licorice, has been used as a ligand for targeting the liver due to the expression of GA receptors on the sinusoidal surface of mammalian hepatocytes, so it may be employed to modify drug delivery systems (DDSs) and obtain better liver or hepatocyte drug uptake and efficacy. In the current review, we focus on the most recent and interesting research advances in the development of GA-based hybrid compounds and DDSs developed for potential employment as efficacious therapeutic options for the treatment of hepatic cancer.

PreS1 Antigen of HBV Down-Regulates MHC-Ⅰ on the Surface of Hepatocytes and Promotes Hepatocarcinogenesis

To explore the internal mechanism of hepatocellular carcinoma (HCC) induced by chronic hepatitis B virus (HBV) infection. L02, HepG2 and Huh7 cells stably overexpressing HBV preS1 antigen were analyzed by flow cytometry, qRT-PCR and tumorigenesis in nude mice to evaluate the effect of preS1 antigen in HBV-related hepatocarcinogenesis. Our results showed that the expression of cancer stem cell (CSCs) related factors and cell surface markers in preS1 overexpressing cells were up-regulated, and the tumorigenicity of these cells was enhanced in nude mice. In addition, preS1 overexpression could down-regulate the expression of major histocompatibility complex Ⅰ (MHC-Ⅰ). The expression of MHC-Ⅰ on the cell surface could be restored by adding interferon gamma (IFN-γ) in the process of cell culturing and the tumorigenicity of cells in nude mice could thus be reduced. Based on the above results, we believe that preS1 is a carcinogen of HBV and that it promotes the formation of liver cancer through down regulating MHC-Ⅰ on the surface of hepatocytes.

Bacteroides acidifaciens in the gut plays a protective role against CD95-mediated liver injury

ABSTRACT The intestinal flora plays an important role in the development of many human and animal diseases. Microbiome association studies revealed the potential regulatory function of intestinal bacteria in many liver diseases, such as autoimmune hepatitis, viral hepatitis and alcoholic hepatitis. However, the key intestinal bacterial strains that affect pathological liver injury and the underlying functional mechanisms remain unclear. We found that the gut microbiota from gentamycin (Gen)-treated mice significantly alleviated concanavalin A (ConA)-induced liver injury compared to vancomycin (Van)-treated mice by inhibiting CD95 expression on the surface of hepatocytes and reducing CD95/CD95L-mediated hepatocyte apoptosis. Through the combination of microbiota sequencing and correlation analysis, we isolated 5 strains with the highest relative abundance, Bacteroides acidifaciens (BA), Parabacteroides distasonis (PD), Bacteroides thetaiotaomicron (BT), Bacteroides dorei (BD) and Bacteroides uniformis (BU), from the feces of Gen-treated mice. Only BA played a protective role against ConA-induced liver injury. Further studies demonstrated that BA-reconstituted mice had reduced CD95/CD95L signaling, which was required for the decrease in the L-glutathione/glutathione (GSSG/GSH) ratio observed in the liver. BA-reconstituted mice were also more resistant to alcoholic liver injury. Our work showed that a specific murine intestinal bacterial strain, BA, ameliorated liver injury by reducing hepatocyte apoptosis in a CD95-dependent manner. Determination of the function of BA may provide an opportunity for its future use as a treatment for liver disease.

TFEB Regulates ATP7B Expression to Promote Platinum Chemoresistance in Human Ovarian Cancer Cells.

ATP7B is a hepato-specific Golgi-located ATPase, which plays a key role in the regulation of copper (Cu) homeostasis and signaling. In response to elevated Cu levels, ATP7B traffics from the Golgi to endo-lysosomal structures, where it sequesters excess copper and further promotes its excretion to the bile at the apical surface of hepatocytes. In addition to liver, high ATP7B expression has been reported in tumors with elevated resistance to platinum (Pt)-based chemotherapy. Chemoresistance to Pt drugs represents the current major obstacle for the treatment of large cohorts of cancer patients. Although the mechanisms underlying Pt-tolerance are still ambiguous, accumulating evidence suggests that lysosomal sequestration of Pt drugs by ion transporters (including ATP7B) might significantly contribute to drug resistance development. In this context, signaling mechanisms regulating the expression of transporters such as ATP7B are of great importance. Considering this notion, we investigated whether ATP7B expression in Pt-resistant cells might be driven by transcription factor EB (TFEB), a master regulator of lysosomal gene transcription. Using resistant ovarian cancer IGROV-CP20 cells, we found that TFEB directly binds to the predicted coordinated lysosomal expression and regulation (CLEAR) sites in the proximal promoter and first intron region of ATP7B upon Pt exposure. This binding accelerates transcription of luciferase reporters containing ATP7B CLEAR regions, while suppression of TFEB inhibits ATP7B expression and stimulates cisplatin toxicity in resistant cells. Thus, these data have uncovered a Pt-dependent transcriptional mechanism that contributes to cancer chemoresistance and might be further explored for therapeutic purposes.

Abstract P171: Ligand-displaying-exosomes using RNA nanotechnology for targeted delivery of multispecific drugs for liver cancer regression

Abstract Liver cancer such as hepatocellular carcinoma (HCC) poorly responds to chemotherapeutics as there are no effective means to deliver drugs to liver cancer due to the intrinsic drug effluxion and detoxification properties of the liver. Exosomes are extracellular vesicles that deliver payload via a fusion mechanism to cell cytosol without endosome trapping. Here we report the use of GalNAc as ligands to decorate exosomes that loaded with anticancer therapeutics Paclitaxel (PTX) and miR122 that silence both the drug efflux pump MDR1 (multidrug-resistant protein-1) and the oncogenic gene ADAM10 (A Disintegrin and metalloproteinase domain-containing protein 10). GalNAc is the ligand that provides exosome targeting ability to bind the hepatocyte surface receptor ASGP-R (asialoglycoprotein-receptor) usually express on liver cancer cell surface abundantly. PTX is highly hydrophobic, when it is conjugated to a polymeric hydrophilic RNA as a prodrug, its water solubility increases 32000-fold. No toxicity was detected. The PTX conjugated RNA strands assembled into a 4-way junction RNA nanoparticle to harbor 24-copies of PTX and 1-copy of miR122. The 4WJ RNA nanoparticles are loaded into the exosome and are decorated with GalNAc as a targeting ligand using RNA nanotechnology. Binding studies demonstrated that the multispecific exosome selectively binds and internalizes into the HepG2 liver cancer cells, and delivers the PTX and miR122 into the cell cytosol, exhibiting the highest efficacy in killing the targeted cancer cells due to the multispecific effect comes from miR122, PTX, GalNAc, and Exos. The liver cancer tumor regressed significantly after systemic injection of the multispecific exosomes to mice xenograft-bearing liver cancer. The results demonstrate that exosomes can serve as a multivalent vector to carry ligands, RNAi, and chemical drugs as a multispecific strategy to treat incurable liver cancers. Citation Format: Xin Li, Satheesh Ellipilli, Hongzhi Wang, Wen-Jui Lee, Yuan Soon Ho, Peixuan Guo. Ligand-displaying-exosomes using RNA nanotechnology for targeted delivery of multispecific drugs for liver cancer regression [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P171.

Ethanol attenuates presentation of cytotoxic T-lymphocyte epitopes on hepatocytes of HBV-infected humanized mice.

Approximately 3.5% of the global population is chronically infected with Hepatitis B Virus (HBV), which puts them at high risk of end-stage liver disease, with the risk of persistent infection potentiated by alcohol consumption. However, the mechanisms underlying the effects of alcohol on HBV persistence remain unclear. Here, we aimed to establish in vivo/ex vivo evidence that alcohol suppresses HBV peptides-major histocompatibility complex (MHC) class I antigen display on primary human hepatocytes (PHH), which diminishes the recognition and clearance of HBV-infected hepatocytes by cytotoxic T-lymphocytes (CTLs). We used fumarylacetoacetate hydrolase (Fah)-/-, Rag2-/-, common cytokine receptor gamma chain knock-out (FRG-KO) humanized mice transplanted with human leukocyte antigen-A2 (HLA-A2)-positive hepatocytes. The mice were HBV-infected and fed control and alcohol diets. Isolated hepatocytes were exposed ex vivo to HBV 18-27-HLA-A2-restricted CTLs to quantify cytotoxicity. For mechanistic studies, we measured proteasome activities, unfolded protein response (UPR), and endoplasmic reticulum (ER) stress in hepatocytes from HBV-infected humanized mouse livers. We found that alcohol feeding attenuated HBV core 18-27-HLA-A2 complex presentation on infected hepatocytes due to the suppression of proteasome function and ER stress induction, which diminished both the processing of HBV peptides and trafficking of HBV-MHC class I complexes to the hepatocyte surface. This alcohol-mediated decrease in MHC class I-restricted antigen presentation of the CTL epitope on target hepatocytes reduced the CTL-specific elimination of infected cells, potentially leading to HBV-infection persistence, which promotes end-stage liver disease outcomes.

Malaria parasite liver stages

Malaria parasite liver stages

Are Humanized Mouse Models Useful for Basic Research of Hepatocarcinogenesis through Chronic Hepatitis B Virus Infection?

Chronic hepatitis B virus (HBV) infection is a global health problem that can lead to liver dysfunction, including liver cirrhosis and hepatocellular carcinoma (HCC). Current antiviral therapies can control viral replication in patients with chronic HBV infection; however, there is a risk of HCC development. HBV-related proteins may be produced in hepatocytes regardless of antiviral therapies and influence intracellular metabolism and signaling pathways, resulting in liver carcinogenesis. To understand the mechanisms of liver carcinogenesis, the effect of HBV infection in human hepatocytes should be analyzed. HBV infects human hepatocytes through transfer to the sodium taurocholate co-transporting polypeptide (NTCP). Although the NTCP is expressed on the hepatocyte surface in several animals, including mice, HBV infection is limited to human primates. Due to this species-specific liver tropism, suitable animal models for analyzing HBV replication and developing antivirals have been lacking since the discovery of the virus. Recently, a humanized mouse model carrying human hepatocytes in the liver was developed based on several immunodeficient mice; this is useful for analyzing the HBV life cycle, antiviral effects of existing/novel antivirals, and intracellular signaling pathways under HBV infection. Herein, the usefulness of human hepatocyte chimeric mouse models in the analysis of HBV-associated hepatocarcinogenesis is discussed.

Influence of microflow on hepatic sinusoid blood flow and red blood cell deformation

Hepatic sinusoids present complex anatomical structures such as the endothelial sieve pores and the Disse space, which govern the microscopic blood flow in the sinusoids and are associated with structural variations in liver fibrosis and cirrhosis. However, the contributions of the permeability of endothelial and collagen layers and the roughness of hepatocyte microvilli to the features of this microflow remain largely unknown. Here, an immersed boundary method coupled with a lattice Boltzmann method was adopted in an in vitro hepatic sinusoidal model, and flow field and erythrocyte deformation analyses were conducted by introducing three new source terms including permeability of the endothelial layer, resistance of hepatocyte microvilli and collagen layers, and deformation of red blood cells (RBCs). Numerical calculations indicated that alterations in endothelial permeability could significantly affect the flow velocity and flow rate distributions in hepatic sinusoids. Interestingly, a biphasic regulating pattern of shear stress occurred simultaneously on the surface of hepatocytes and the lower side of endothelium, i.e., the shear stress increased with increased thickness of hepatocyte microvilli and collagen layer when the endothelial permeability was high but decreased with the increase of the thickness at low endothelial permeability. Additionally, this specified microflow manipulates typical RBC deformation inside the sinusoid, yielding one-third of the variation of deformable index with varied endothelial permeability. These simulations not only are consistent with experimental measurements using in vitro liver sinusoidal chip but also elaborate the contributions of endothelial and collagen layer permeability and wall roughness. Thus, our results provide a basis for further characterizing this microflow and understanding its effects on cellular migration and deformation in the hepatic sinusoids.

Naturalne inhibitory PCSK9 — przegląd substancji o możliwym wpływie na PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein discovered in 2003 and playing an important role in lipoprotein metabolism. The main function of PCSK9 is to regulate the number of low-density lipoprotein (LDL) receptors on the surface of hepatocytes. The biological effect of PSCK9 is to reduce the number of LDL receptors on the surface of hepatocytes, which reduces their ability to take up LDL lipoproteins. PCSK9 inhibitors such as alirocumab, evolocumab or inclisiran are a new, very effective method of lipid-lowering therapy. Recently, a number of naturally derived compounds have been identified that are characterized by the ability to reduce the activity of PCSK9. These compounds are among the alkaloids, polyphenols, sterols, stanols, vegetable proteins and other nutrients and may find application in supporting the pharmacotherapy of lipid disorders.

Oral delivery of a Lactococcus lactis expressing extracellular TGFβR2 alleviates hepatic fibrosis.

Liver fibrosis is caused by the accumulation of extracellular matrix proteins on the surface of hepatocytes and results from chronic liver injury. TGFβ1 is one of the most important promoters of hepatic fibrosis, which accelerates the transformation of hepatic stellate cells to myofibroblasts and collagen expression. It is well-known that TGFβ1 binds to TGFβR2 to mediate its downstream signal cascades to regulate target gene transcription. Therefore, the TGFβR2 blocker might be a prominent drug candidate. We constructed TGFβR2 extracellular domain into living biotherapeutics Lactococcus lactis to reduce hepatic fibrosis in CCl4 treated mice in the present study. We found that the culture supernatant of the recombinant bacteria can inhibit the TGFβ1-induced collagen synthesis in the hepatic stellate cells at the cellular level. In addition, results of in vivo study showed that the recombinant bacteria significantly reduced the degree of liver fibrosis in CCl4-treated mice. Furthermore, flow cytometry results indicated that the recombinant bacteria treatment significantly reduced the CD11b+ Kupffer cells compared with the empty vector bacteria group. Consistently, fibrosis-related gene and protein expression were significantly reduced upon recombinant bacteria treatment. Finally, the subchronic toxicity test results showed that this bacteria strain did not have any significant side effects. In conclusion, our recombinant Lactococcus lactis shows tremendous therapeutic potential in liver fibrosis. KEY POINTS: • The supernatant of L. lactis expressing TGFβR2 inhibits the activation of myofibroblast. • The oral recombinant strain reduced the degree of liver fibrosis and inflammation in mice. • The recombinant strain was safe in subchronic toxicity test in mice.