Short-Term versus Long-Term Culture of A549 Cells for Evaluating the Effects of Lipopolysaccharide on Oxidative Stress, Surfactant Proteins and Cathelicidin LL-37.

Zuzana Nova,Henrieta Skovierova,Andrea Calkovska,Jan Strnadel,Erika Halasova

doi:10.3390/ijms21031148

Zuzana Nova, Henrieta Skovierova + Show 3 more

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https://doi.org/10.3390/ijms21031148

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Abstract

Alveolar epithelial type II (ATII) cells and their proper function are essential for maintaining lung integrity and homeostasis. However, they can be damaged by lipopolysaccharide (LPS) during Gram-negative bacterial infection. Thus, this study evaluated and compared the effects of LPS on short and long-term cultures of A549 cells by determining the cell viability, levels of oxidative stress and antimicrobial peptide cathelicidin LL-37 and changes in the expression of surfactant proteins (SPs). Moreover, we compared A549 cell response to LPS in the presence of different serum concentrations. Additionally, the effect of N-acetylcysteine (NAC) on LPS-induced oxidative stress as a possible treatment was determined. Our results indicate that A549 cells are relatively resistant to LPS and able to maintain integrity even at high LPS concentrations. Their response to endotoxin is partially dependent on serum concentration. NAC failed to lower LPS-induced oxidative stress in A549 cells. Finally, LPS modulates SP gene expression in A549 cells in a time dependent manner and differences between short and long-term cultures were present. Our results support the idea that long-term cultivation of A549 cells could promote a more ATII-like phenotype and thus could be a more suitable model for ATII cells, especially for in vitro studies dealing with surfactant production.

Highlights

The alveolar epithelium has a key role in maintaining lung integrity and homeostasis
A major function of small cuboidal alveolar epithelial type II cells (ATII) cells is the production of pulmonary surfactant, which is fundamental for preventing of alveolar collapse by reducing surface tension at the end of expiration, and plays an important role in the local pulmonary defense mechanisms in which mainly surfactant proteins (SPs) are involved [1,2]
After 48 and 72 h, LPS 10–200 μg/mL had almost no impact on cell viability, and viability decreased to 79% and 85% in cells exposed to 500 μg/mL LPS, respectively

Summary

Introduction

The alveolar epithelium has a key role in maintaining lung integrity and homeostasis It consists of alveolar epithelial type I cells (ATI) and alveolar epithelial type II cells (ATII). ATII cells are the main source of endogenous antimicrobial peptides; among them is cathelicidin hCAP18/LL-37 [3,4] These cells are referred as “defenders of the alveolus.”. Another very important role of ATII cells is the repairing of damaged tissue, as they are capable of self-regenerating and trans-differentiating into ATI cells [5]. Loss of this cell population may be a basis for various pulmonary disorders

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