Ethanol-induced lymphatic endothelial cell permeability via MAP-kinase regulation.

Matthew Herrera,Flavia M Souza-Smith,Patricia Molina

doi:10.1152/ajpcell.00039.2021

Abstract

Chronic alcohol alters the immune system enhancing the susceptibility to inflammation, bacterial, and viral infections in alcohol users. We have shown that alcohol causes increased permeability of mesenteric lymphatic vessels in alcohol-fed rats. The mechanisms of alcohol-induced lymphatic leakage are unknown. Endothelial cell monolayer permeability is controlled by junctional proteins complexes called tight junctions (TJ) and adherens junctions (AJ), and each can be regulated by MAPK activation. We hypothesize that ethanol induces lymphatic endothelial cell (LEC) permeability via disruption of LEC TJ through MAPK activation. An in vitro model of rat LECs was used. Ethanol-supplemented medium was added at concentrations of 0, 25, and 50 mM to confluent cells. Resistance-based barrier function, transwell permeability, cell viability, TJ, AJ, and MAPK protein activity, TJ and AJ gene expressions, and the role of p38 MAPK in barrier function regulation were measured. Ethanol increased the permeability of LECs compared to controls that was not associated with decreased cell viability. LECs treated with 50 mM ethanol showed an increase in phosphorylated levels of p38. No significant changes in TJ and AJ gene or protein expressions were observed after ethanol treatment. p38 inhibition prevented ethanol-induced increases in permeability. These findings suggest that p38 may play a role in the regulation of ethanol-induced LEC permeability, but altered permeability may not be associated with decreased TJ or AJ protein expression. Further investigation into junctional protein localization is needed to better understand the effects of ethanol on lymphatic endothelial cell-to-cell contacts and hyperpermeability.

Highlights

Excessive alcohol consumption is associated with alterations in inflammatory and immune responses and can cause increased susceptibility to infection [1]
After considering the trends in mitogen-activated protein kinase (MAPK) activation seen in the previously described literature and the results presented here, it was decided that the appropriate time to measure MAPK activation was at 50% of the maximum change in resistance elicited by the highest dose of ethanol
After addition of normal medium, the maximum change in transendothelial resistance (TER) was positive in lymphatic endothelial cell (LEC) treated with 0 mM ethanol and negative in LECs treated with 25 and 50 mM ethanol, with a greater decrease caused by 50 mM ethanol compared to 25 mM ethanol (Fig. 1B)

Summary

Introduction

Excessive alcohol consumption is associated with alterations in inflammatory and immune responses and can cause increased susceptibility to infection [1]. The LS is a network of vessels throughout the entire body that plays an important role in tissue fluid pressure regulation, immune surveillance, and absorption of dietary fats in the intestine [5,6,7,8]. It has not been studied extensively until recent decades, the lymphatic system is known to contribute to numerous diseases, such as lymphedema, cancer metastasis, and several inflammatory disorders [5, 9, 11,12,13]. The circulation of lymph fluid throughout the LS allows for proper immune dialogue between tissues and lymph nodes [14], which assist to generate a specialized microenvironment for the meeting of migratory immune cells, such as lymphocytes and antigen presenting cells (APCs) [15, 16]

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Discussion

Conclusion