The impact of steatosis on liver regeneration

Preoperative assessment of liver regeneration using T1 mapping and the functional liver imaging score derived from Gd-EOB-DTPA-enhanced magnetic resonance for patient with hepatocellular carcinoma after hepatectomy

Objectives

To explore whether T1 mapping parameters and the functional liver imaging score (FLIS) based on Gd-EOB-DTPA MRI could evaluate liver regeneration after hepatectomy for HCC patient.

Methods

This retrospective study finally included 60 HCC patients (48 men and 12 women, with a median age of 53 years). T1 relaxation time of liver before gadoxetic acid injection (T1pre) and during the hepatobiliary phase (T1HBP), reduction rate (Δ%) and FLIS were calculated, their correlations with liver fibrosis stage, hepatic steatosis, and liver regeneration, quantified as regeneration index (RI), were assessed by Kendall's tau-b correlation test or Spearman's correlation test. Multivariate linear regression analyses were used to explore the indicator of RI.

Results

T1pre, T1HBP, Δ%, and FLIS manifested significant correlation with fibrosis stage (r = 0.434, P =0.001; r = 0.546, P < 0.001; r = -0.356, P =0.005; r = -0.653, P <0.001, respectively). T1pre showed significant correction with steatosis grade (r = 0.415, P =0.001). Fibrosis stage and steatosis grade were associated with RI (r = -0.436, P<0.001; r = -0.338, P =0.008). Accordingly, T1pre, T1HBP and FLIS were the significant predictors (P<0.05) of RI in multivariate analysis. Similarly, in the patients undergoing minor hepatectomy (n=35), T1HBP, Δ% and FLIS were related to RI (P<0.05) in multivariate analysis. Nevertheless, in the patients undergoing major hepatectomy (n=25), no T1 mapping parameter and FLIS was the independent predictor of RI.

Conclusions

T1 mapping parameters and FLIS were the potential noninvasive indicators of liver regeneration, except for HCC patients undergoing major hepatectomy.

Clinical relevance statement

The value of T1 mapping and FLIS with Gd-EOB-DTPA MRI for accurate preoperative evaluation of liver regeneration is critical to prevent liver failure and improve prognosis of HCC patients.

Cell metabolism-based therapy for liver fibrosis, repair, and hepatocellular carcinoma

Progression of chronic liver injury to fibrosis, abnormal liver regeneration, and HCC is driven by a dysregulated dialog between epithelial cells and their microenvironment, in particular immune, fibroblasts, and endothelial cells. There is currently no antifibrogenic therapy, and drug treatment of HCC is limited to tyrosine kinase inhibitors and immunotherapy targeting the tumor microenvironment. Metabolic reprogramming of epithelial and nonparenchymal cells is critical at each stage of disease progression, suggesting that targeting specific metabolic pathways could constitute an interesting therapeutic approach. In this review, we discuss how modulating intrinsic metabolism of key effector liver cells might disrupt the pathogenic sequence from chronic liver injury to fibrosis/cirrhosis, regeneration, and HCC.

Novel Optical Criteria and Mechanisms of Critical Decline in Liver Regenerative Potential

The most effective method of treating tumors localized in the liver remains resection. However, in the presence of concomitant pathology, the regenerative potential of the liver is significantly reduced. To date, there is insufficient fundamental data on the mechanisms responsible for the disruption of liver regeneration, and there is no effective method for assessing its regenerative potential. The most suitable model for these purposes is acute liver injury (ALI). Modern non-contrast methods of multiphoton microscopy with second harmonic generation and fluorescence lifetime imaging microscopy (FLIM) modes enable intravital evaluation of the metabolic status of the hepatocytes; therefore, this expands the possibilities for studying the processes occurring in cells during regeneration in the context of any pathologies.

Aging, ROS, and cellular senescence: a trilogy in the progression of liver fibrosis

Ageing is an inevitable and multifaceted biological process that impacts a wide range of cellular and molecular mechanisms, leading to the development of various diseases, such as liver fibrosis. Liver fibrosis progresses to cirrhosis, which is an advanced form due to high amounts of extracellular matrix and restoration of normal liver structure with failure to repair damaged tissue and cells, marking the end of liver function and total liver failure, ultimately death. The most important factors are reactive oxygen species (ROS) and cellular senescence. Oxidative stress is defined as an impairment by ROS, which are by-products of the mitochondrial electron transport chain and other key molecular pathways that induce cell damage and can activate cellular senescence pathways. Cellular senescence is characterized by pro-inflammatory cytokines, growth factors, and proteases secreted by senescent cells, collectively known as the senescence-associated secretory phenotype (SASP). The presence of senescent cells, which disrupt tissue architecture and function and increase senescent cell production in liver tissues, contributes to fibrogenesis. Hepatic stellate cells (HSCs) are activated in response to chronic liver injury, oxidative stress, and senescence signals that drive excessive production and deposition of extracellular matrix. This review article aims to provide a comprehensive overview of the pathogenic role of ROS and cellular senescence in the aging liver and their contribution to fibrosis.

An intense 60-day weight-loss course leads to an 18 kg body weight reduction and metabolic reprogramming of soldiers with obesity

Soldiers of the Mexican Army with obesity were subjected to an intense 60-day weight-loss course consisting of a controlled diet, daily physical training, and psychological sessions. The nutritional treatment followed the European Society of Cardiology (ESC) recommendations, incorporating elements of the traditional milpa diet in the nutritional intervention. The total energy intake was reduced by 200 kcal every 20 days, starting with 1,800 kcal and ending with 1,400 kcal daily. On average, the participants reduced their body weight by 18 kg. We employed an innovative approach to monitor the progress of the twelve soldiers who completed the entire program. We compared the untargeted metabolomics profiles of their urine samples, taken before and after the course. The data obtained through liquid chromatography and high-resolution mass spectrometry (LC-MS) provided insightful results. Classification models perfectly separated the profiles pre and post-course, indicating a significant reprogramming of the participants' metabolism. The changes were observed in the C1-, vitamin, amino acid, and energy metabolism pathways, primarily affecting the liver, biliary system, and mitochondria. This study not only demonstrates the potential of rapid weight loss and metabolic pathway modification but also introduces a non-invasive method for monitoring the metabolic state of individuals through urine mass spectrometry data.

Basal MET phosphorylation is an indicator of hepatocyte dysregulation in liver disease

Chronic liver diseases are worldwide on the rise. Due to the rapidly increasing incidence, in particular in Western countries, metabolic dysfunction-associated steatotic liver disease (MASLD) is gaining importance as the disease can develop into hepatocellular carcinoma. Lipid accumulation in hepatocytes has been identified as the characteristic structural change in MASLD development, but molecular mechanisms responsible for disease progression remained unresolved. Here, we uncover in primary hepatocytes from a preclinical model fed with a Western diet (WD) an increased basal MET phosphorylation and a strong downregulation of the PI3K-AKT pathway. Dynamic pathway modeling of hepatocyte growth factor (HGF) signal transduction combined with global proteomics identifies that an elevated basal MET phosphorylation rate is the main driver of altered signaling leading to increased proliferation of WD-hepatocytes. Model-adaptation to patient-derived hepatocytes reveal patient-specific variability in basal MET phosphorylation, which correlates with patient outcome after liver surgery. Thus, dysregulated basal MET phosphorylation could be an indicator for the health status of the liver and thereby inform on the risk of a patient to suffer from liver failure after surgery.

Endothelial autophagy is not required for liver regeneration after partial hepatectomy in mice with fatty liver

BACKGROUND & AIMS

Patients with non-alcoholic fatty liver disease (NAFLD) have impaired liver regeneration. Liver endothelial cells play a key role in liver regeneration. In non-alcoholic steatohepatitis (NASH), liver endothelial cells display a defect in autophagy, contributing to NASH progression. We aimed to determine the role of endothelial autophagy in liver regeneration following liver resection in NAFLD.

METHODS

First, we assessed autophagy in primary endothelial cells from wild type mice fed a high fat diet and subjected to partial hepatectomy. Then, we assessed liver regeneration after partial hepatectomy in mice deficient (Atg5lox/lox ;VE-cadherin-Cre+ ) or not (Atg5lox/lox ) in endothelial autophagy and fed a high fat diet. The role of endothelial autophagy in liver regeneration was also assessed in ApoE-/- hypercholesterolemic mice and in mice with NASH induced by methionine- and choline-deficient diet.

RESULTS

First, autophagy (LC3II/protein) was strongly increased in liver endothelial cells following hepatectomy. Then, we observed at 40 and 48 h and at 7 days after partial hepatectomy, that Atg5lox/lox ;VE-cadherin-Cre+ mice fed a high fat diet had similar liver weight, plasma AST, ALT and albumin concentration, and liver protein expression of proliferation (PCNA), cell-cycle (Cyclin D1, BrdU incorporation, phospho-Histone H3) and apoptosis markers (cleaved Caspase-3) as Atg5lox/lox mice fed a high fat diet. Same results were obtained in ApoE-/- and methionine- and choline-deficient diet fed mice, 40 h after hepatectomy.

CONCLUSION

These results demonstrate that the defect in endothelial autophagy occurring in NASH does not account for the impaired liver regeneration occurring in this setting.

Controlled Attenuation Parameter Is Associated with a Distinct Systemic Inflammatory Milieu after Clearance of HCV Infection

Hepatitis C virus (HCV) infection is closely associated with lipid metabolism defects along with a high prevalence of hepatic steatosis. After HCV clearance, steatosis persists in many patients. However, the reasons behind this phenomenon are not completely clear. To investigate the association between 92 soluble inflammatory mediators (SIMs) and the steatosis grade, we made use of a cohort of 94 patients with chronic HCV infection who cleared HCV after direct-acting antiviral agent (DAA) treatment. Patients were classified into three groups according to their controlled attenuation parameter (CAP). CAP is associated with ALT, γ-GT and liver stiffness after HCV clearance. While stem cell factor (SCF) and tumor necrosis factor ligand superfamily member 12 (TWEAK) levels were significantly reduced in patients with CAP > 299 dB/m, the levels of fibroblast growth factor (FGF)-21 and interleukin-18 receptor 1 (IL-18R1) were higher in those patients at week 96 after virus clearance. These four markers also showed a linear correlation with CAP values. FGF-21 levels correlated with CAP only after HCV clearance. Taken together, these four biomarkers, namely SCF, TWEAK, FGF-21 and IL-18R1, are associated with CAP status after virus clearance. A potential role of these proteins in the pathogenesis of post-sustained viral response (SVR) nonalcoholic steatohepatitis requires further investigation.

Can endocan serve as a molecular "hepatostat" in liver regeneration?

BACKGROUND

Intriguingly, liver regeneration after injury does not induce uncontrolled growth and the underlying mechanisms of such a "hepatostat" are still not clear. Endocan, a proteoglycan, was implicated in liver regeneration. It can support the function of hepatocyte growth factor/scatter factor in tissue repair after injury. Endostatin, a 20 kDa C-terminal fragment of collagen XVIII, may modulate the cessation of liver regeneration. eEF2K, a protein kinase that regulates protein synthesis, can regulate angiogenesis. Thus, we investigated the role of endocan, endostatin and eEF2K during normal liver regeneration.

METHODS

Serum samples and regenerating remnant liver tissues were obtained on various days after partial hepatectomy in rats. mRNA expression levels of Vegf and Pcna were analyzed in addition to immunohistochemical evaluations. Liver tissue protein levels of endostatin, endocan and p-eEF2K/eEF2K were determined with Western blot. Serum levels of endostatin and endocan were assessed with ELISA.

RESULTS

Pcna expression level in residual liver tissues peaked on day-1, while Vegf expression reached its highest level on days 1-3 after partial hepatectomy (70%). Endocan activity declined gradually on days 1-7. The decrease in liver endocan expression was accompanied by an increase in serum endocan levels. Partial hepatectomy induced a rapid increase in liver endostatin levels. Following its surge on day-1, endostatin expression gradually declined, which was accompanied by a peak in serum endostatin. Finally, partial hepatectomy was shown to regulate eEF2K; thus, increasing protein translation.

CONCLUSIONS

We revealed possible mechanistic insights into liver regeneration by examining the associations of Pcna, Vegf, endocan, endostatin, eEF2K with hepatic regeneration after partial hepatectomy. Indeed, endocan might serve as a useful biomarker to monitor clinical prognosis in a plethora of conditions such as recovery of donor's remaining liver after living-donor liver transplant. Whether endocan might represent a strategy to optimize liver regeneration when given therapeutically needs to be investigated in future studies.

Regeneration during Obesity: An Impaired Homeostasis

Simple Summary

Regeneration represents the biological processes that allow cells and tissues to renew and develop. During obesity, a variety of changes and reactions are seen. This includes inflammation and metabolic disorders. These obesity-induced changes do impact the regeneration processes. Such impacts that obesity has on regeneration would affect tissues and organs development and would also have consequences on the outcomes of therapies that depend on cells regeneration (such as burns, radiotherapy and leukemia) given to patients suffering from obesity. Therefore, a particular attention should be given to patients suffering from obesity in biological, therapeutic and clinical contexts that depend on regeneration ability.

Abstract

Obesity is a health problem that, in addition to the known morbidities, induces the generation of a biological environment with negative impacts on regeneration. Indeed, factors like DNA damages, oxidative stress and inflammation would impair the stem cell functions, in addition to some metabolic and development patterns. At the cellular and tissulaire levels, this has consequences on growth, renewal and restoration which results into an impaired regeneration. This impaired homeostasis concerns also key metabolic tissues including muscles and liver which would worsen the energy balance outcome towards further development of obesity. Such impacts of obesity on regeneration shows the need of a specific care given to obese patients recovering from diseases or conditions requiring regeneration such as burns, radiotherapy and leukemia. On the other hand, since stem cells are suggested to manage obesity, this impaired regeneration homeostasis needs to be considered towards more optimized stem cells-based obesity therapies within the context of precision medicine.

New frontiers in liver resection for hepatocellular carcinoma

Liver resection is one of the main curative options for early hepatocellular carcinoma (HCC) in patients with cirrhosis and is the treatment of choice in non-cirrhotic patients. However, careful patient selection is required to balance the risk of postoperative liver failure and the potential benefit on long-term outcomes. In the last decades, improved surgical techniques and perioperative management, as well as better patient selection, have enabled the indications for liver resection to be expanded. In this review, we aim to describe the main indications for liver resection in the management of HCC, its role compared to percutaneous ablation and liver transplantation in the therapeutic algorithm, as well as the recent advances in liver surgery that could be used to improve the prognosis of patients with HCC.

Serine peptidase inhibitor Kazal type III (SPINK3) promotes BRL-3A cell proliferation by targeting the PI3K-AKT signaling pathway

The serine protease inhibitor, Kazal type III (SPINK3), is a trypsin inhibitor associated with liver disease, which highly overexpresses in a variety of cancers. In one of our previous studies of our laboratory, Spink3 was observed to be significantly upregulated in rat liver regeneration (LR) via a gene expression profile. For the current study, rat hepatocyte BRL-3A cells were treated by gene addition/interference, and the addition of the exogenous rat recombinant protein SPINK3. It was revealed that both the overexpression of endogenous Spink3 and addition of exogenous rat recombinant SPINK3 (rrSPINK3) significantly promoted the cell proliferation of BRL-3A cells, whereas cell proliferation was inhibited when Spink3 was interfered. Furthermore, quantitative reverse transcription polymerase chain reaction and western blot results revealed that three signaling pathways, including extracellular-signal-regulated kinase 1/2 (ERK1/2), Janus kinase (JAK)-signal transducer and activator of transcription (STAT), and phosphatidylinositol-3-kinase (PI3K)-protein kinase B (AKT), as well as their related genes, were altered following endogenous Spink3 addition/interference. Also, the PI3K-AKT and SRC-p38 pathways and their related genes were modified following exogenous SPINK3 treatment. Among them, the common signaling pathway was PI3K-AKT pathway. We concluded that SPINK3 could activate the PI3K-AKT pathway by enhancing the expression of AKT1 to regulate the proliferation of BRL-3A cells. This study may contribute to shedding light on the potential mechanisms of SPINK3 that regulate the proliferation of BRL-3A cells.

Suppressed hepatocyte proliferation via a ROS-HNE-P21 pathway is associated with nicotine- and cotinine-enhanced alcoholic fatty liver in mice

CYP2A5 is a major enzyme responsible for nicotine and cotinine metabolism in mice. Nicotine and cotinine enhance alcoholic fatty liver in wild type (WT) mice but not in CYP2A5 knockout (KO) mice, and reactive oxygen species (ROS) generated during the CYP2A5-mediated metabolism contributes to the enhancing effect. In combination with ethanol, nicotine and cotinine increased lipid peroxidation end product 4-hydroxynonenal (HNE) in WT mice but not in KO mice. In ethanol-fed KO mice, only 5 and 10 genes were regulated by nicotine and cotinine, respectively. However, in ethanol-fed WT mice, 59 and 104 genes were regulated by nicotine and cotinine, respectively, and 7 genes were up-regulated by both nicotine and cotinine. Plin 2 and Cdkn1a are among the 7 genes. Plin2 encodes adipose differentiation-related protein (ADRP), a lipid droplet-associated protein, which was confirmed to be increased by nicotine and cotinine in WT mice but not in KO mice. Cdkn1a encodes P21 and elevated P21 in nuclei was also confirmed. HNE can increase P21 and P21 inhibit cell proliferation. Consistently, hepatocyte proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 were decreased in WT mice but not in KO mice by nicotine/ethanol and cotinine/ethanol, respectively. These results suggest that inhibition of liver proliferation via a ROS-HNE-P21 pathway is involved in nicotine- and cotinine-enhanced alcoholic fatty liver.