Role of Eosinophils in the Proliferation of Airway Smooth Muscle (ASM) Cells

Rational and hypothesis Asthma is a chronic inflammatory disorder of the lung airways that is associated with airway remodeling and hyperresponsiveness (AHR). Its is well documented that the smooth muscle mass in asthmatic airways is increased due to hypertrophy and hyperplasia of the ASM cells. Moreover, eosinophils have been proposed in different studies to play a major role in airway remodeling. The association between increased eosinophil numbers and asthma severity has been well documented. Here, we hypothesized that the interaction between eosinophils and ASM cells plays an important role in airway remodeling and that eosinophils modulate the airways through enhancing ASM cell proliferation. Objectives of the study The aim of this study is to examine the effect of eosinophils on ASM cell proliferation using eosinophils isolated from asthmatic subjects. Specific aim 1. Effect of co-culture of ASM cells with eosinophils on ASM cell proliferation. In this specific aim, the effect of eosinophil on ASM cell proliferation will be studied by co-culturing eosinophils isolated from asthmatic and healthy patients with ASM cells in vitro. This will be done using non-stimulated eosinophils or eosinophils activated with Interleukin-5 (IL-5)and Interleukin-3 (IL-3). ASM proliferation will be monitored by determining the levels of the proliferation marker Ki-67 expression in ASM cells. Specific aim 2. Understanding the mechanism by which eosinophils enhance ASM proliferation. In this specific aim, we will study the mechanism by which eosinophils enhance the proliferation of ASM cells. To study if this effect of eosinophils is done through direct contact with ASM cells, we will co-culture ASM cells with eosinophils membrane fractions. Moreover, we will examine the effect of cytokines and extracellular matrix (ECM) proteins produced by eosinophils on smooth muscle cells