Investigating the Role of NHE1 in Idiopathic Pulmonary Fibrosis

Abstract

Idiopathic pulmonary fibrosis is a chronic lung disorder characterized by thickening, stiffening and scaring of tissue within the lungs. Affected individuals develop shortness of breath and progressive reduced respiratory function. In order to be able to analyze this process two cell lines will be compared throughout the project. The first being LL29 cells which are human fibroblasts that were derived from a patient with idiopathic pulmonary fibrosis. In comparison to those cells will be further investigation of WI‐38 cells which are derived from normal lung tissue. In fibroblast cells, TGF‐b1, LPA, and 5HT will be investigated to differentiate between the two cell lines through analysis of their proliferation, stress fiber formation, collagen contraction and myofibroblast differentiation. Transforming growth factor beta 1 (TGF‐b1) is a cytokine that is a growth factor implicated in the pathogenesis of pulmonary fibrosis and is involved in differentiation, proliferation and matrix production of fibroblasts. Serotonin (5‐HT) is a signaling molecule that that functions through a G‐protein coupled receptors that support the increase of TGF‐b1 and the development of the fibrotic phenotype. This hormone is involved in wound healing and stimulating inflammation. LPA is a bioactive lipid signaling molecule that plays a role in mediating inflammation and activating TGF‐b1 signaling. Fibrosis ultimately results in low blood flow and hypoxia in the tissue, a microenvironment in which is closely associated with the upregulation of the sodium‐hydrogen exchanger isoform 1 (NHE1). NHE1 is a ubiquitously expressed protein that exchanges one extracellular Na+ for one intracellular H+. This regulates intracellular pH and cell progression through the cell cycle. When NHE1 is upregulated it supports increased cell proliferation and migration, indicating that it may play a vital role in the behavior of fibroblasts in idiopathic pulmonary fibrosis. Here we evaluate NHE1‐dependent changes in cell proliferation, stress fiber formation, α‐smooth muscle actin expression and collagen contraction.