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Hepatic stellate cells (HSC) play a key role in the development of chronic liver disease (CLD). Liraglutide, well-established in type 2 diabetes, showed anti-inflammatory and anti-oxidant properties. We evaluated the effects of liraglutide on HSC phenotype and hepatic microvascular function using diverse pre-clinical models of CLD. Human and rat HSC were in vitro treated with liraglutide, or vehicle, and their phenotype, viability and proliferation were evaluated. In addition, liraglutide or vehicle was administered to rats with CLD. Liver microvascular function, fibrosis, HSC phenotype and sinusoidal endothelial phenotype were determined. Additionally, the effects of liraglutide on HSC phenotype were analysed in human precision-cut liver slices. Liraglutide markedly improved HSC phenotype and diminished cell proliferation. Cirrhotic rats receiving liraglutide exhibited significantly improved liver microvascular function, as evidenced by lower portal pressure, improved intrahepatic vascular resistance, and marked ameliorations in fibrosis, HSC phenotype and endothelial function. The anti-fibrotic effects of liraglutide were confirmed in human liver tissue and, although requiring further investigation, its underlying molecular mechanisms suggested a GLP1-R-independent and NF-κB-Sox9-dependent one. This study demonstrates for the first time that liraglutide improves the liver sinusoidal milieu in pre-clinical models of cirrhosis, encouraging its clinical evaluation in the treatment of chronic liver disease.

In cirrhosis, liver microvascular dysfunction is a key factor increasing hepatic vascular resistance to portal blood flow, which leads to portal hypertension. De‐regulated inflammatory and pro‐apoptotic processes due to chronic injury play important roles in the dysfunction of liver sinusoidal cells. The present study aimed at characterizing the effects of the pan‐caspase inhibitor emricasan on systemic and hepatic hemodynamics, hepatic cells phenotype, and underlying mechanisms in preclinical models of advanced chronic liver disease. We investigated the effects of 7‐day emricasan on hepatic and systemic hemodynamics, liver function, hepatic microcirculatory function, inflammation, fibrosis, hepatic cells phenotype, and paracrine interactions in rats with advanced cirrhosis due to chronic CCl4 administration. The hepato‐protective effects of emricasan were additionally investigated in cells isolated from human cirrhotic livers. Cirrhotic rats receiving emricasan showed significantly lower portal pressure than vehicle‐treated animals with no changes in portal blood flow, indicating improved vascular resistance. Hemodynamic improvement was associated with significantly better liver function, reduced hepatic inflammation, improved phenotype of hepatocytes, liver sinusoidal endothelial cells, hepatic stellate cells and macrophages, and reduced fibrosis. In vitro experiments demonstrated that emricasan exerted its benefits directly improving hepatocytes’ expression of specific markers and synthetic capacity, and ameliorated nonparenchymal cells through a paracrine mechanism mediated by small extracellular vesicles released by hepatocytes. Conclusion: This study demonstrates that emricasan improves liver sinusoidal microvascular dysfunction in cirrhosis, which leads to marked amelioration in fibrosis, portal hypertension and liver function, and therefore encourages its clinical evaluation in the treatment of advanced chronic liver disease. One‐week emricasan promoted a significant amelioration in portal hypertension and hepatic microcirculation in experimental cirrhosis. Underlying mechanisms included direct improvement in hepatocytes phenotype, which paracrinally leads to fibrosis improvement, better endothelial function, and less inflammation.

The poor prognosis of chronic liver disease (CLD) generates the need to investigate the evolving mechanisms of disease progression, thus disclosing therapeutic targets before development of clinical complications. Considering the central role of liver sinusoidal endothelial cells (LSECs) in pre-neoplastic advanced CLD, the present study aimed at investigating the progression of CLD from an endothelial holistic perspective. RNAseq defined the transcriptome of primary LSECs isolated from three pre-clinical models of advanced CLD, during the progression of the disease, and from fresh human cirrhotic tissue. At each stage of the disease, the effects of LSECs secretome on neighboring cells and proteomic analysis of LSECs-derived extracellular vesicles (EVs) were also determined. CLD was associated with deep common modifications in the transcriptome of LSECs in the pre-clinical models. Pathway enrichment analysis showed predominance of genes related with pro-oncogenic, cellular communication processes, and EVs biogenesis during CLD progression. Crosstalk experiments revealed endothelial EVs as potent angiocrine effectors. The proteome of LSECs EVs showed stage-specific signatures, including over-expression of tropomyosin-1. Proof-of-principle experiments treating cirrhotic HSCs with recombinant tropomyosin-1 suggested de-activating effects. Our data provide the basis for discovering novel biomarkers and therapeutic targets for new disease-modifying treatments for patients with advanced CLD.

Progressive hepatic damage and fibrosis are major features of chronic liver diseases of different etiology, yet the underlying molecular mechanisms remain to be fully defined. N-RAS, a member of the RAS family of small guanine nucleotide-binding proteins also encompassing the highly homologous H-RAS and K-RAS isoforms, was previously reported to modulate cell death and renal fibrosis; however, its role in liver damage and fibrogenesis remains unknown. Here, we approached this question by using N-RAS deficient (N-RAS −/− ) mice and two experimental models of liver injury and fibrosis, namely carbon tetrachloride (CCl 4 ) intoxication and bile duct ligation (BDL). In wild-type (N-RAS +/+ ) mice both hepatotoxic procedures augmented N-RAS expression in the liver. Compared to N-RAS +/+ counterparts, N-RAS −/− mice subjected to either CCl 4 or BDL showed exacerbated liver injury and fibrosis, which was associated with enhanced hepatic stellate cell (HSC) activation and leukocyte infiltration in the damaged liver. At the molecular level, after CCl 4 or BDL, N-RAS −/− livers exhibited augmented expression of necroptotic death markers along with JNK1/2 hyperactivation. In line with this, N-RAS ablation in a human hepatocytic cell line resulted in enhanced activation of JNK and necroptosis mediators in response to cell death stimuli. Of note, loss of hepatic N-RAS expression was characteristic of chronic liver disease patients with fibrosis. Collectively, our study unveils a novel role for N-RAS as a negative controller of the progression of liver injury and fibrogenesis, by critically downregulating signaling pathways leading to hepatocyte necroptosis. Furthermore, it suggests that N-RAS may be of potential clinical value as prognostic biomarker of progressive fibrotic liver damage, or as a novel therapeutic target for the treatment of chronic liver disease.

Liver sinusoidal endothelial cells (LSECs) form the wall of the hepatic sinusoids. Unlike other capillaries, they lack an organized basement membrane and have cytoplasm that is penetrated by open fenestrae, making the hepatic microvascular endothelium discontinuous. LSECs have essential roles in the maintenance of hepatic homeostasis, including regulation of the vascular tone, inflammation and thrombosis, and they are essential for control of the hepatic immune response. On a background of acute or chronic liver injury, LSECs modify their phenotype and negatively affect neighbouring cells and liver disease pathophysiology. This Review describes the main functions and phenotypic dysregulations of LSECs in liver diseases, specifically in the context of acute injury (ischaemia–reperfusion injury, drug-induced liver injury and bacterial and viral infection), chronic liver disease (metabolism-associated liver disease, alcoholic steatohepatitis and chronic hepatotoxic injury) and hepatocellular carcinoma, and provides a comprehensive update of the role of LSECs as therapeutic targets for liver disease. Finally, we discuss the open questions in the field of LSEC pathobiology and future avenues of research. Liver sinusoidal endothelial cells (LSECs) form the wall of the hepatic sinusoids and have essential roles in hepatic homeostasis. This Review describes the phenotypic dysregulations of LSECs in the context of liver disease and hepatocellular carcinoma, and provides an update of the role of LSECs as therapeutic targets. Key points Liver sinusoidal endothelial cells (LSECs) form the vascular wall of the hepatic microcirculatory system, the hepatic sinusoid, and exhibit unique phenotypic characteristics, including open fenestrae and lack of a basement membrane. In health, LSECs have key roles maintaining hepatic homeostasis and are critical for several processes, including immune regulation, control of inflammation, modulation of vascular tone and regulation of the coagulation cascade. LSECs become rapidly dedifferentiated during acute and chronic liver injuries, acquiring vasoconstrictor, proinflammatory and prothrombotic properties; this process, termed ‘capillarization’, contributes to the activation and dedifferentiation of other hepatic cells. LSEC capillarization plays a key part in the pathophysiology of major liver diseases, including ischaemia–reperfusion injury, drug-induced liver injury, chronic liver disease and hepatocellular carcinoma; several LSEC molecular targets have been proposed as treatments.

Liver microcirculatory dysfunction is one of the key mechanisms that promotes the progression of chronic liver disease. In this Review, the authors explore the role of liver microcirculatory dysfunction in cirrhotic portal hypertension, the preclinical models used to study liver circulation and potential therapeutics.

The liver sinusoids are a unique type of microvascular beds. The specialized phenotype of sinusoidal cells is essential for their communication, and for the function of all hepatic cell types, including hepatocytes. Liver sinusoidal endothelial cells (LSECs) conform the inner layer of the sinusoids, which is permeable due to the fenestrae across the cytoplasm; hepatic stellate cells (HSCs) surround LSECs, regulate the vascular tone, and synthetize the extracellular matrix, and Kupffer cells (KCs) are the liver-resident macrophages. Upon injury, the harmonic equilibrium in sinusoidal communication is disrupted, leading to phenotypic alterations that may affect the function of the whole liver if the damage persists. Understanding how the specialized sinusoidal cells work in coordination with each other in healthy livers and chronic liver disease is of the utmost importance for the discovery of new therapeutic targets and the design of novel pharmacological strategies. In this manuscript, we summarize the current knowledge on the role of sinusoidal cells and their communication both in health and chronic liver diseases, and their potential pharmacologic modulation. Finally, we discuss how alterations occurring during chronic injury may contribute to the development of hepatocellular carcinoma, which is usually developed in the background of chronic liver disease.

Liver cells isolated from pre‐clinical models are essential tools for studying liver (patho)physiology, and also for screening new therapeutic options. We aimed at developing a new antibody‐free isolation method able to obtain the four main hepatic cell types (hepatocytes, liver sinusoidal endothelial cells [LSEC], hepatic macrophages [HMΦ] and hepatic stellate cells [HSC]) from a single rat liver. Control and cirrhotic (CCl4 and TAA) rat livers (n = 6) were perfused, digested with collagenase and mechanically disaggregated obtaining a multicellular suspension. Hepatocytes were purified by low revolution centrifugations while non‐parenchymal cells were subjected to differential centrifugation. Two different fractions were obtained: HSC and mixed LSEC + HMΦ. Further LSEC and HMΦ enrichment was achieved by selective adherence time to collagen‐coated substrates. Isolated cells showed high viability (80%‐95%) and purity (>95%) and were characterized as functional: hepatocytes synthetized albumin and urea, LSEC maintained endocytic capacity and in vivo fenestrae distribution, HMΦ increased expression of inflammatory markers in response to LPS and HSC were activated upon in vitro culture. The 4 in 1 protocol allows the simultaneous isolation of highly pure and functional hepatic cell sub‐populations from control or cirrhotic single livers without antibody selection.

Portal hypertension represents one of the major clinical consequences of chronic liver disease, having a deep impact on patients’ prognosis and survival. Its pathophysiology defines a pathological increase in the intrahepatic vascular resistance as the primary factor in its development, being subsequently aggravated by a paradoxical increase in portal blood inflow. Although extensive preclinical and clinical research in the field has been developed in recent decades, no effective treatment targeting its primary mechanism has been defined. The present review critically summarizes the current knowledge in portal hypertension therapeutics, focusing on those strategies driven by the disease pathophysiology and underlying cellular mechanisms.

Background Chronic liver disease is a major health concern, but sex-specific differences in its pathophysiology remain unclear. Preclinical studies have predominantly used male animals, limiting findings' relevance to both sexes. This project aimed to explore sex differences in cirrhosis and portal hypertension (PH) in rats, and to find similarities in human samples for translational relevance. Methods Advanced chronic liver disease (ACLD) was induced in male and female Sprague–Dawley rats using thioacetamide (TAA, 250 mg/kg; 12 weeks) or bile duct ligation (BDL; 28 days). Healthy rats served as controls (n = 11–18/group). We assessed in vivo hepatic and systemic hemodynamic parameters, hepatic microvascular function, and hepatic transcriptomic analyses, including sex-specific differences in cellular composition using gene deconvolution (n = 5/group). Two human sample cohorts were compared to preclinical data for translational insights. Results Both animal models showed PH. TAA males had similar portal pressure (PP) to females (14.2 vs 14.1 mmHg), but BDL males had significantly higher PP than females (14.5 vs 12.5 mmHg; p = 0.003). No differences were observed in hepatic microvascular function. In the BDL model, females had more fenestrae and porosity, and less fibrosis. Transcriptomic analysis revealed that TAA males had dysregulated metabolic pathways, while females had deregulated genes in hormone signaling. In the BDL model, males showed higher deregulation in platelet activation, protein degradation, vesicular transport, and disease-related pathways. Gene deconvolution showed males had a more specialized endothelial phenotype basally, with more changes in endothelial and macrophage phenotypes after injury. In MASLD patients, men had dysregulated metabolic pathways, while women showed deregulation in fibrosis, extracellular matrix, and endocrine regulation. In HBV patients, men had more dysregulation in fibrosis, inflammation, and immune response. Female MASLD patients had more activated hepatic stellate cells, and greater loss of endothelial phenotype compared to men. Conclusions This study highlights sex-dependent molecular differences in the pathophysiology of cirrhosis in two preclinical models. Further research in preclinical and human liver disease is essential to develop safe and effective treatments for ACLD in both sexes. Highlights Animal models showed portal hypertension. BDL males had significantly higher portal pressure and fibrosis than females, while BDL females showed increased sinusoidal fenestration and reduced disease severity. Transcriptomic analysis in TAA models revealed dysregulated metabolic pathways in males, while females displayed alterations in hormone signalling. In BDL models, males showed higher deregulation in platelet activation, protein degradation, vesicular transport, and disease-related pathways. In MASLD patients, transcriptomic data showed males with dysregulated metabolic and inflammatory pathways, while females exhibited alterations in fibrosis, extracellular matrix remodelling, and endocrine regulation, corroborating preclinical findings. Gene deconvolution in animal models revealed sex-specific changes in hepatic endothelial and macrophage phenotypes, with males undergoing greater shifts after liver injury. In MASLD patients, gene deconvolution showed females with greater endothelial phenotype loss and hepatic stellate cell activation than males, aligning with fibrosis-related findings in transcriptomic data. Plain language summary Chronic liver disease is a serious global health issue, but men and women experience it differently. Despite this, most preclinical research has focused on male animals, creating a gap in understanding how the disease develops and progresses in females. Our study aimed to address these sex-based differences using two preclinical models of advanced liver disease in male and female rats, and to compare these findings with patients. We identified significant differences between male and female rats with liver disease. In one model, male rats exhibited higher portal pressure and more extensive liver fibrosis, while females displayed milder disease and healthier liver structures. Analysis of genetic activity in liver tissue revealed sex-specific patterns: males showed alterations in metabolic pathways, while females exhibited changes related to hormone signalling. These findings were consistent with observations in human liver samples, where men demonstrated greater inflammation and metabolic dysfunction, and women showed more pronounced fibrosis and vascular remodelling. Furthermore, we analysed specific liver cell types and found that male rats experienced greater changes in certain cells after injury, potentially contributing to worse outcomes. These insights underscore the importance of including both sexes in research to develop safer and more effective treatments for advanced liver disease.