FT-IR Spectroscopic Imaging of Endothelial Cells Response to Tumor Necrosis Factor-α: To Follow Markers of Inflammation Using Standard and High-Magnification Resolution

Abstract

Two endothelial cell lines were selected as models to investigate an effect of incubation with cytokine tumor necrosis factor type α (TNF-α) using Fourier transform infrared (FT-IR) imaging spectroscopy. Both cell lines are often used in laboratories and are typical lung vascular endothelial cells (HMLVEC) derived from the fusion of umbilical vein endothelial cells with lung adenocarcinoma cells (EA.hy926). This study was focused on alteration of spectral changes accompanying inflammation at the cellular level by applying two resolution systems of FT-IR microscopy. The standard approach, with a pixel size of ca. 5.5 μm2, determined the inflammatory state of the whole cell, while a high-magnification resolution (pixel size of ca. 1.1 μm2) provided information at the subcellular level. Importantly, the analysis of IR spectra recorded with different modes produced similar results overall and yielded unambiguous classification of inflamed cells. Generally, the most significant changes in the cells under the influence of TNF-α are related with lipids—their composition and concentration; however, segregation of cells into subcellular compartments provided an additional insight into proteins and nucleic acids related events. The observed spectral alterations are specific for the type of endothelial cell line.