Targeting 5-Hydroxytryptamine receptor 1A in portal vein to decrease portal hypertension.

BACKGROUNDS & AIMS: Portal hypertension (PH) is one of the most frequent complications of chronic liver disease. The peripheral 5-Hydroxytryptamine (5-HT) level was increased in cirrhotic patients. We aimed to elucidate the function and mechanism of 5-HT receptor 1A (HTR1A) in portal vein (PV) on PH. METHODS: PH models were induced by thioacetamide (TAA) injection, bile duct ligation (BDL) or partial portal vein ligation (PPVL). HTR1A expression was detected using real-time PCR, in situ hybridization and immunofluorescence staining. In situ intraportal infusion was employed to assess the effects of 5-HT, the HTR1A agonist 8-OH-DPAT, and the HTR1A antagonist WAY-100635 on portal pressure (PP). Htr1a knock-out (Htr1a-/-) rats and vascular smooth muscle cell (VSMC)-specific Htr1a knock-out (Htr1aΔVSMC) mice were utilized to confirm the regulatory role of HTR1A on PP. RESULTS: HTR1A expression was significantly increased in the hypertensive PV of PH model rats and cirrhotic patients. Additionally, 8-OH-DPAT increased but WAY-100635 decreased PP in rats, without affecting liver fibrosis and systemic hemodynamics. Furthermore, 5-HT or 8-OH-DPAT directly induced the contraction of isolated PVs. Genetic deletion of Htr1a in rats and VSMCs-specific Htr1a knock-out in mice prevented the development of PH. Moreover, 5-HT triggered the cAMP pathway-mediated PVSMCs contraction via HTR1A in PV. We also confirmed alverine as an HTR1A antagonist and demonstrated its capacity to decrease PP in TAA-, BDL-, and PPVL-induced portal hypertensive rats. CONCLUSIONS: Our findings reveal that 5-HT promotes PH by inducing the contraction of PV, and identify HTR1A as a promising therapeutic target for attenuating PH. As an HTR1A antagonist, alverine is expected to become a candidate for clinical PH treatment.

The Hepatic Sinusoid in Chronic Liver Disease: The Optimal Milieu for Cancer.

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.

Pan-PPAR agonist lanifibranor improves portal hypertension and hepatic fibrosis in experimental advanced chronic liver disease.

BACKGROUND & AIMS: In advanced chronic liver disease (ACLD), deregulated hepatic necroinflammatory processes play a key role in the development of liver microvascular dysfunction, fibrogenesis, and increased hepatic vascular tone, resulting in progression of ACLD and portal hypertension. Given the current lack of an effective treatment, we aimed to characterise the effects of the pan-peroxisome proliferator-activated receptor (pan-PPAR) agonist lanifibranor in 2 preclinical models of ACLD, as well as in liver cells from patients with ACLD. METHODS: Cirrhotic rats (thioacetamide or common bile duct ligation; TAA or cBDL) randomly received lanifibranor (100 mg/kg/day, po) or vehicle for 14 days (n = 12/group). PPAR expression, systemic and hepatic haemodynamics, presence of ascites, liver sinusoidal endothelial cell (LSEC) phenotype, hepatic stellate cell (HSC) activation, serum transaminases and albumin, hepatic macrophage infiltration, cytokine expression, and liver fibrosis were determined. Hepatic cells were isolated from the livers of patients with cirrhosis and their phenotype was evaluated after treatment with either lanifibranor or vehicle. RESULTS: TAA-cirrhotic rats receiving lanifibranor showed significantly lower portal pressure compared with vehicle-treated animals (-15%; p = 0.003) without decreasing portal blood flow, indicating improved hepatic vascular resistance. Moreover, lanifibranor-treated TAA-rats showed decreased ascites, improved LSEC and HSC phenotypes, ameliorated hepatic microvascular function, reduced hepatic inflammation, and significant fibrosis regression (-32%; p = 0.020). These findings were confirmed in the cBDL rat model as well as in human liver cells from patients with cirrhosis, which exhibited phenotypic improvement upon treatment with lanifibranor. CONCLUSIONS: Lanifibranor ameliorates fibrosis and portal hypertension in preclinical models of decompensated cirrhosis. Promising results in human hepatic cells further support its clinical evaluation for the treatment of ACLD. LAY SUMMARY: Advanced chronic liver disease (ACLD) constitutes a serious public health issue for which safe and effective treatments are lacking. This study shows that lanifibranor improves portal hypertension and liver fibrosis, 2 key elements of the pathophysiology of ACLD, in preclinical models of the disease. Evaluation of lanifibranor in liver cells from patients with ACLD further supports its beneficial effects.

Oxidative Stress in Chronic Liver Disease and Portal Hypertension: Potential of DHA as Nutraceutical.

Chronic liver disease constitutes a growing public health issue worldwide, with no safe and effective enough treatment clinical scenarios. The present review provides an overview of the current knowledge regarding advanced chronic liver disease (ACLD), focusing on the major contributors of its pathophysiology: inflammation, oxidative stress, fibrosis and portal hypertension. We present the benefits of supplementation with docosahexaenoic acid triglycerides (TG-DHA) in other health areas as demonstrated experimentally, and explore its potential as a novel nutraceutical approach for the treatment of ACLD and portal hypertension based on published pre-clinical data.

A Nutraceutical Rich in Docosahexaenoic Acid Improves Portal Hypertension in a Preclinical Model of Advanced Chronic Liver Disease.

Inflammation and oxidative stress play a key role in the pathophysiology of advanced chronic liver disease (ACLD) and portal hypertension (PH). Considering the current lack of effective treatments, we evaluated an anti-inflammatory and antioxidant nutraceutical rich in docosahexaenoic acid (DHA) as a possible therapy for ACLD. We investigated the effects of two-week DHA supplementation (500 mg/kg) on hepatic fatty acids, PH, oxidative stress, inflammation, and hepatic stellate cell (HSC) phenotype in rats with ACLD. Additionally, the effects of DHA were evaluated in murine macrophages and human HSC. In contrast to vehicle-treated animals, cirrhotic rats receiving DHA reestablished a healthy hepatic fatty acid profile, which was associated with an improvement in PH. The mechanisms underlying this hemodynamic improvement included a reduction in oxidative stress and inflammation, as well as a marked HSC deactivation, confirmed in human HSC. Experiments with cultured macrophages showed that treatment with DHA protects against pro-inflammatory insults. The present preclinical study demonstrates that a nutraceutical rich in DHA significantly improves PH in chronic liver disease mainly by suppressing inflammation and oxidative stress-driven HSC activation, encouraging its evaluation as a new treatment for PH and cirrhosis.