Autofluorescence in freshly isolated adult human liver sinusoidal cells

Autofluorescent granules of various sizes were observed in primary human liver endothelial cells (LSECs) upon laser irradiation using a wide range of wavelengths. Autofluorescence was detected in LAMP-1 positive vesicles, suggesting lysosomal location. Confocal imaging of freshly prepared cultures and imaging flow cytometry of non-cultured cells revealed fluorescence in all channels used. Treatment with a lipofuscin autofluorescence quencher reduced autofluorescence, most efficiently in the near UV-area. These results, combined with the knowledge of the very active blood clearance function of LSECs support the notion that lysosomally located autofluorescent material reflected accumulation of lipofuscin in the intact liver. These results illustrate the importance of careful selection of fluorophores, especially when labelling of live cells where the quencher is not compatible.

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.

Silencing of sinusoidal DDR1 reduces murine liver metastasis by colon carcinoma

Liver metastasis depends on the collagenous microenvironment generated by hepatic sinusoidal cells (SCs). DDR1 is an atypical collagen receptor linked to tumor progression, but whether SCs express DDR1 and its implication in liver metastasis remain unknown. Freshly isolated hepatic stellate cells (HSCs), Kupffer cells (KCs), and liver sinusoidal endothelial cells (LSECs), that conform the SCs, expressed functional DDR1. HSCs expressed the largest amounts. C26 colon carcinoma secretomes increased DDR1 phosphorylation in HSCs and KCs by collagen I. Inhibition of kinase activity by DDR1-IN-1 or mRNA silencing of DDR1 reduced HSCs secretion of MMP2/9 and chemoattractant and proliferative factors for LSECs and C26 cells. DDR1-IN-1 did not modify MMP2/9 in KCs or LSECs secretomes, but decreased the enhancement of C26 migration and proliferation induced by their secretomes. Gene array showed that DDR1 silencing downregulated HSCs genes for collagens, MMPs, interleukins and chemokines. Silencing of DDR1 before tumor inoculation reduced hepatic C26 metastasis in mice. Silenced livers bore less tumor foci than controls. Metastatic foci in DDR1 silenced mice were smaller and contained an altered stroma with fewer SCs, proliferating cells, collagen and MMPs than foci in control mice. In conclusion, hepatic DDR1 promotes C26 liver metastasis and favors the pro-metastatic response of SCs to the tumor.

SINUSOIDAL CELLS AND CYTOKINE RESPONSE IN THE TETRACHLOROMETHANE-INDUCED HEPATOTOXICITY AND AN APPROACH TO ITS CORRECTION

High occurence of liver diseases (toxic, viral hepatitis, liver failure, cirrhosis) requires urgent search of new methods for management of the hepatobiliary diseases. At the present time, the role of immune mechanisms in pathogenesis of diffuse toxic liver damage is not finally clarified. The model of toxic hepatitis induced by carbon tetrachloride (CCl4) is widely known, but this approach allows us to perform complex evaluation and develop the methods for adequate correction of liver disorders in experimental model, which is not always feasible in clinical setting.To design a model of diffuse toxic liver damage, the CCl4 oil solution was used, having been administered intraperitoneally to experimental animals, at a single dose of 50 mg per 100 g body mass. Aiming for correction of toxic liver damage, the injections of aminophthalhydrazide (APH) to experimental animals were carried out intramuscularly at the dose of 2 mg/kg over the terms of experiment. An evaluation of the role of sinusoidal cells (SC) and cytokine production at the local and systemic level were carried out in the model of toxic liver damage caused by CCl4 and its correction by APH treatment. In the course of developing diffuse toxic liver damage induced by CCl4, the production of proinflammatory cytokines TNFα, IL-1α and IL-18 was enhanced at the local level, whereas an increase in TNFα concentration was observed in blood plasma. Following aminophthalhydrazide (APH) administration, the concentrations of proinflammatory cytokines (TNFα and IL-18) decreased at system level, along with locally decreased levels of IL-6 and IFNγ.Changes in the functional state of immunocompetent cells, which include sinusoidal cells (SC), have a significant impact on the development of pathological processes in the liver. The results of our study presume that, over the early periods of toxic impact upon liver tissue, the number of SCs increases both due to influx of blood monocytes and mature macrophages from the peritoneal cavity that enter the injury site directly via mesothelial layer. The SCs provide phagocytosis of damaged hepatocytes and contribute to resolution of the inflammatory process.Modulation of the macrophage activities by APH contributes to increased amounts of SCs at the early stages, and stabilizes their quantities after 2 weeks of APH injections. Change in the numbers of liver SCs during toxic damage affects the production of cytokines. A direct effect of APH upon the SCs may change the production of regulatory factors and compensate the insufficient rate of recovery processes after the toxic damage.

Porto-Sinusoidal Vascular Disease Associated to Oxaliplatin: An Entity to Think about It

Portal sinusoidal vascular disease is a presinusoidal cause of portal hypertension (PHT) of unknown etiology, characterized by typical manifestations of PHT (esophageal varices, ascites, portosystemic collaterals), plaquetopenia and splenomegaly with a gradient of portal pressure slightly increased, according to the presinusoidal nature of the PHT. A few cases in the literature have shown a relationship between oxaliplatin and the development of presinusoidal portal hypertension, years after the chemotherapy for colorectal cancer (therefore, different to sinusoidal obstruction syndrome). There are three mechanisms through which oxaliplatin can cause sinusoidal damage: (1) damage at the level of endothelial cells and stimulates the release of free radicals and depletion of glutathione transferase, with altering the integrity of the sinusoidal cells. The damage in the endothelial sinusoidal cells allows to erythrocytes to across into the Dissé space and formation of perisinusoidal fibrosis, (2) the appearance of nodular regenerative hyperplasia is favored by the chronic hypoxia of the centrilobular areas and, finally, (3) oxaliplatin can generate an obliteration of the blood capillaries and zones of parenchymal extinction. These three facts can develop, in a minority of cases, the appearance of a presinusoidal increase of portal pressure, which typically appears years after the completion of chemotherapy and sometimes is underdiagnosed until variceal bleeding, ascites or encephalopathy appear. The knowledge of this pathology is essential to be able to perform an early diagnostic and consult to the hepatologist.

ROLE OF THE STROMAL CELLULAR COMPONENT IN COMPENSATORY PROCESSES IN DIFFUSE LIVER DAMAGE

The aim of the study was to assess the role of the cellular component of the stroma in liver regeneration after its toxic damage. The experimental model of toxic hepatitis caused by intraperitoneal administration of tetrachloromethane (CCl4) showed that regeneration processes in the liver on the 3rd day are manifested in an increase in binuclear hepatocytes, Ki-67 + cells and hepatocytes dividing by mitosis. The reaction of the stromal component is expressed in an increase in the number of CD45 +, mast and sinusoidal cells (SC). On the 7th day of the development of toxic hepatitis the hepatocyte alteration increases, that is accompanied by a sharp decrease in the mitotic index and the number of Ki-67 + cells. In the stromal component there is a decrease in the number of sinusoidal cells, CD45 + and a significant increase in mast cells with a high secretion granule content.