Early changes of graft function,cytokines and superoxide dismutase serum levels after donor liver denervation and Kupffer cell depletion in a rat-to-rat liver transplantation model

BACKGROUND:Hepatic reperfusion injury may cause acute inflammatory damage,producing significant organ dysfunction,and is an important problem in liver transplantation.This experiment aimed to study early changes of hepatic function after donor liver denervation and Kupffer cell depletion in rat-to-rat liver transplantation and to evaluate the effect of pre-treatment on liver reperfusion injury.METHODS:Donor rats were divided into four groups:control group;group G was pre-treated with gadolinium chloride(G),...     

Transforming growth factor beta-activated kinase 1 (TAK1)-dependent checkpoint in the survival of dendritic cells promotes immune homeostasis and function

Homeostatic control of dendritic cell (DC) survival is crucial for adaptive immunity, but the molecular mechanism is not well defined. Moreover, how DCs influence immune homeostasis under steady state remains unclear. Combining DC-specific and -inducible deletion systems, we report that transforming growth factor beta-activated kinase 1 (TAK1) is an essential regulator of DC survival and immune system homeostasis and function. Deficiency of TAK1 in CD11c(+) cells induced markedly elevated apoptosis, leading to the depletion of DC populations, especially the CD8(+) and CD103(+) DC subsets in lymphoid and nonlymphoid tissues, respectively. TAK1 also contributed to DC development by promoting the generation of DC precursors. Prosurvival signals from Toll-like receptors, CD40 and receptor activator of nuclear factor-κB (RANK) are integrated by TAK1 in DCs, which in turn mediated activation of downstream NF-κB and AKT-Foxo pathways and established a gene-expression program. TAK1 deficiency in DCs caused a myeloid proliferative disorder characterized by expansion of neutrophils and inflammatory monocytes, disrupted T-cell homeostasis, and prevented effective T-cell priming and generation of regulatory T cells. Moreover, TAK1 signaling in DCs was required to prevent myeloid proliferation even in the absence of lymphocytes, indicating a previously unappreciated regulatory mechanism of DC-mediated control of myeloid cell-dependent inflammation. Therefore, TAK1 orchestrates a prosurvival checkpoint in DCs that affects the homeostasis and function of the immune system.     

Role of Kupffer cells in the outgrowth of colorectal cancer liver metastases

Colorectal cancer is one of the commonest malignancies in the developed world. The liver constitutes the main host organ for its distant metastases which, when present, augur a bad prognosis for the disease. Kupffer cells (KCs) are macrophages that constantly reside within the liver and form an effective first line defence against multiple harmful agents which reach the hepatic sinusoids via the portal circulation. KCs remove chemical compounds and dead or damaged cells, eliminate bacteria and protect against invading tumour cells. They may play a crucial tumouricidal role, exerting cytotoxic and cytostatic functions through the release of multiple cytokines and chemokines. Subsequently, colorectal metastasising cells are destroyed either by KC-performed phagocytosis or via the stimulation of other immune cells which migrate into the sinusoids and act accordingly. On the contrary, KC products, including cytokines, growth factors and matrix-degrading enzymes may promote liver metastasis, supporting tumour cell extravasation, motility and invasion. Current research aims to exploit the antineoplastic properties of KCs in new therapeutic approaches of colorectal cancer liver metastasis. Numerous agents, such as the granulocyte macrophage-colony stimulating factor, interferon gamma, muramyl peptide analogues and various antibody based treatments, have been tested in experimental models with promising results. Future trials may investigate their use in everyday clinical practice and compare their therapeutic value with current treatment of the disease.     

库普弗细胞在非酒精性脂肪性肝病中的作用

库普弗细胞(KC)是定居于肝内的单核-巨噬细胞,其表面存在多种受体,可被多种配体激活,通过产生细胞因子、炎症介质和活性氧簇等在多种肝损伤的发病过程中起重要作用。近年的研究显示KC也参与非酒精性脂肪性肝病的发病机制,在胰岛素抵抗、氧应激和炎症过程中起重要作用,因此控制KC的活化将有助于减轻或阻止非酒精性脂肪性肝病的的发展。     

Role of Kupffer cells in the pathogenesis of liver disease

INTRODUCTION The sinusoidal lining of the liver contains the nonparen-chymal cell populations which consist of Kupffer cells (KCs), sinusoidal endothelial cells (SEC) and stellate cells (SC). All three cell-types seem to play a crucial role in liver homeo…     

Pathogenesis of alcoholic liver disease: interactions between parenchymal and non-parenchymal cells

The development of alcoholic liver disease (ALD) is a complex process involving both the parenchymal and non-parenchymal cells in the liver. The impact of ethanol on hepatocytes can be characterized as a condition of organelle stress with multifactorial changes in hepatocellular function accumulating during ethanol exposure. These changes include oxidative stress, mitochondrial dysfunction, decreased methylation capacity, endoplasmic reticulum stress, impaired vesicular trafficking and altered proteasome function. Injury to hepatocytes is attributed, in part, to ethanol metabolism by the hepatocytes. Changes in the structural integrity of hepatic sinusoidal endothelial cells, as well as enhanced inflammation in the liver during ethanol exposure are also important contributors to injury. Activation of hepatic stellate cells initiates the deposition of extracellular matrix proteins characteristic of fibrosis. Kupffer cells, the resident macrophages in the liver, are particularly critical to the onset of ethanol-induced liver injury. Chronic ethanol exposure sensitizes Kupffer cells to activation by lipopolysaccharides via toll-like receptor 4. This sensitization enhances the production of inflammatory mediators, such as tumor necrosis factor-α and reactive oxygen species that contribute to hepatocyte dysfunction, necrosis and apoptosis of hepatocytes and the generation of extracellular matrix proteins leading to fibrosis. In this review we provide an overview of the complex interactions between parenchymal and non-parenchymal cells in the liver during the progression of ethanol-induced liver injury.     

库普弗细胞在酒精性肝病发病机理中的作用

库普弗细胞(KC)是肝内定居的巨噬细胞,由于其细胞表面存在多种受体,可被多种配体和激活剂激活,通过产生反应氧、细胞因子和炎症介质等贯穿于酒精性肝病的发病过程,控制KC的活化将有助于减轻或阻止酒精性肝病的肝脏病变。     

Augmenter of liver regeneration promotes hepatocyte proliferation induced by Kupffer cells

AIM: To observe the effects of augmenter of liver regeneration (ALR) on Kupffer cells and to determine whether ALR promotes hepatocyte proliferation induced by Kupffer cells. METHODS: Kupffer cells and hepatocytes were cultured in vitro and various concentrations of recombinant rat ALR (rrALR) were added. 3H-thymidine, BrdU and 3H-leucine incorporation was determined in cultured Kupffer cells and hepatocytes, in hepatocytes conditioned by Kupffer cells, and in associated medium. rrALR was labeled by iodination and used to determine its binding activity by Scatchard analysis in Kupffer cells and primarily cultured rat hepatocytes. RESULTS: rrALR stimulated DMA replication in Kupffer cells and protein synthesis both in cells and in medium in a non-concentration-dependent manner. The effect was significant at the concentration of 1μg/L ALR. However, rrALR had no effect on primarily cultured hepatocytes, when hepatocytes were cultured with the Kupffer cell medium conditioned by ALR, DNA replication and protein synthesis in hepatocytes increased significantly at the concentration of 1μg/L ALR. When the ALR concentration was increased, its effect on hepatocyte proliferation decreased to the basal level. Scatchard analysis indicated the presence of a single class of high affinity receptors with a dissociation constant (Kd) of 0.883 nmol/L and a maximum binding capacity (Bmax) of 126.1 pmol/g protein in the rat Kupffer cells. CONCLUSION: ALR can promote hepatocyte proliferation induced by Kupffer cells, which is associated with the concentration of ALR, suggesting that Kupffer cells play a dual role in liver regeneration.     

Intracellular survival pathways in the liver.

Recent studies have drawn attention to cytokines as important modulators of hepatocyte cell death during acute and chronic liver disease. Through interaction with cell surface receptors, they activate specific intracellular pathways that influence cell fate in different manners. For example, tumor necrosis factor not only induces proapoptotic signals via the caspase cascade but also activates intracellular survival pathways, namely the nuclear factor (NF)-kappaB pathway. In this article, we will focus on the function of the NF-kappaB pathway in liver physiology and pathology. Especially, recent data based on experiments with genetically modified mice will be discussed, which demonstrated important and controversial functions of this pathway e.g. in cytokine-mediated hepatocyte apoptosis, ischemia-reperfusion injury, liver regeneration and the development of hepatocellular carcinoma. Moreover, the role of the interleukin-6 pathway and its possible protective function in the context of liver failure will be summarized.     

肝脏非实质细胞在肝脏缺血再灌注损伤中的作用

肝脏非实质细胞在肝脏中发挥着非常重要的作用。回顾近几年关于非实质肝细胞,如Kupffer细胞、肝窦内皮细胞、肝星状细胞、树突状细胞等在肝脏缺血再灌注损伤(HIRI)中的作用。分析表明肝脏非实质细胞在HIRI过程中扮演着非常重要的角色,能通过各种途径最终加重或者减轻HIRI。     

Kupffer细胞在非酒精性脂肪性肝病发病机制中的作用

Kupffer细胞是肝脏的非实质细胞,具有分泌细胞因子及吞噬、免疫等功能,并与多种肝脏疾病如肝损伤、肝纤维化、肝硬化等密切相关。近年来,国内外学者对其在非酒精性脂肪性肝病（NAFLD）发生机制中的作用给予高度重视。本文从脂质代谢、信号蛋白变化、活性氧、抗原递呈等方面对Kupffer细胞在NAFLD发病机制中的作用进行综述。     

Role of gut microbiota in liver diseases

The liver constantly encounters food‐derived antigens and bacterial components such as lipopolysaccharide translocated from the gut into the portal vein. Bacterial components stimulate Toll‐like receptors (TLR), which are expressed on Kupffer cells, biliary epithelial cells, hepatocytes, hepatic stellate cells, endothelial cells and dendritic cells and recognize specific pathogen‐associated molecular patterns. The signaling of TLR to its main ligand triggers inflammation. Usually, in order to protect against hyperactivation of the immune system and to prevent organ failure by persistent inflammation, TLR tolerance to repeated stimuli is induced. In chronic liver diseases, a breakdown in TLR tolerance occurs. Furthermore, Kupffer cells, hepatic stellate cells and natural killer T cells are key components of innate immunity. Decreased numbers and impaired ability of these cells lead to failures in immune tolerance, resulting in persistent inflammation. Recently, the activation of inflammasome was revealed to control the secretion of pro‐inflammatory cytokines such as interleukin‐1β in response to bacterial pathogens. Innate immunity seems to be an important contributor to the pathogenesis of fatty liver disease and autoimmune liver disease. Recently, probiotics were reported to affect various liver diseases via shifts in gut microbiota and the stability of intestinal permeability. However, many unresolved questions remain. Further analysis will be needed to gain a more comprehensive understanding of the association of innate immunity with the pathogenesis of various liver diseases.     

Regulatory natural killer cells in murine liver and their immunosuppressive capacity

Background: Abundant amounts of natural killer (NK) cells are present in the liver, most of which are endowed with direct cytotoxic and inflammatory cytokine production capacities. However, the control of compromised immunity in the liver may be accomplished by a population of regulatory NK cells possessing suppressive or tolerogenic functions. Aims: To identify and characterize regulatory NK cells in murine liver. Methods: NK cells were isolated from the liver of C57BL/6 mice by magnetic‐activated cells sorting (MACS). NK cells were stimulated with different agents and those cells that produced interleukin (IL)‐10 were detected by flow cytometry and isolated by MACS. IL‐10‐producing NK cells were regarded as regulatory NK cells and the functional capacities of liver‐derived regulatory NK cells were assessed in vitro. Results: The frequencies of regulatory NK cells in the liver were 4.1 ± 0.3% of hepatic NK cells and 0.45 ± 0.02% of liver nonparenchymal cells. Regulatory NK cells produced abundant amounts of IL‐10 in culture. These cells also suppressed the proliferative capacities of T cells and B cells in vitro. However, another population of NK cells that did not produce IL‐10 (immunogenic NK cells) could not suppress lymphocyte proliferation. Conclusions: The presence of regulatory NK cells in the liver and their immunosuppressive capacities endowed these cells with the critical function of maintaining homeostasis under normal conditions. Exaggerated or impaired functions of these cells may also contribute to different pathological processes.     

内质网应激在肝脏疾病中的作用研究进展

内质网是细胞内蛋白质、脂类和糖类的重要合成基地,是细胞内钙离子的储存场所,与物质运输、物质交换、解毒作用密切相关。内质网应激是细胞的一种重要自我防御机制,能提高细胞对环境变化的适应能力,但过强过久的内质网应激则会引起不可逆的细胞损伤甚至凋亡。研究发现,内质网应激与多器官多种疾病相关。肝细胞中含有大量的内质网,对内质网应激更为敏感,许多肝脏疾病如肝细胞癌、药物性肝损伤、非酒精性脂肪性肝病、肝胰岛素抵抗等的发病机制均与内质网应激有关。本文就内质网应激对各种肝脏疾病的影响作一概述。     

Melatonin protects steatotic and nonsteatotic liver grafts against cold ischemia and reperfusion injury

Abstract: Chronic organ‐donor shortage has required the acceptance of steatotic livers for transplantation purposes despite the higher risk of graft dysfunction or nonfunction associated with the cold ischemia–reperfusion injury. This study evaluated the use of melatonin as an additive to Institute Georges Lopez (IGL‐1) solution for protecting nonsteatotic and steatotic liver grafts against cold ischemia–reperfusion injury. In the current investigation, we used an ex vivo isolated perfused rat liver model. Steatotic and nonsteatotic livers were preserved for 24 hr (4°C) in University of Wisconsin or IGL‐1 solutions with or without melatonin, as well as in University of Wisconsin solution alone. Thereafter, livers were subjected to 2‐hr reperfusion (37°C). We assessed hepatic injury (transaminases) and function [bile production and sulfobromophthalein (BSP) clearance, vascular resistance], as well as other factors potentially implicated in the high vulnerability of steatotic livers against ischemia–reperfusion injury (oxidative stress and related inflammatory mediators including nitric oxide and cytokines). We also evaluated well‐known cytoprotective factors as hemeoxygenase 1 (HO‐1). Fatty livers preserved in IGL‐1 solution enriched with melatonin showed lower transaminase levels and higher bile production and BSP clearance when compared to those obtained for livers maintained in IGL‐1 solution alone. A significant diminution of vascular resistance was also observed when melatonin was added to the IGL‐1 solution. The melatonin benefits correlated with the generation of nitric oxide (through constitutive e‐NOS activation) and the prevention of oxidative stress and inflammatory cytokine release including tumor necrosis factor and adiponectin, respectively. The addition of melatonin to IGL‐1 solution improved nonsteatotic and steatotic liver graft preservation, limiting their risk against cold ischemia–reperfusion injury.     

肝脏免疫炎症在非酒精性脂肪性肝病发生发展中的作用

非酒精性脂肪性肝病(NAFLD)是临床上常见的肝脏疾病之一,其发病机制较为复杂,二、三次打击学说仍是目前得到公认的NAFLD的主要发病机制。但近年来,肝脏免疫炎症在NAFLD的发生、发展中逐步得到众多研究者的重视。从肝脏免疫炎症的角度,阐述了肝脏免疫炎症导致NAFLD发生、发展的机制。