Chronic pulmonary diseases such as asthma, COPD, and Idiopathic pulmonary fibrosis are significant causes of mortality and morbidity worldwide. Currently, there is no radical treatment for many chronic pulmonary diseases, and the treatment options focus on relieving the symptoms and improving lung function. Therefore, efficient therapeutic agents are highly needed. Bronchial epithelial cells and airway smooth muscle cells and their crosstalk play a significant role in the pathogenesis of these diseases. Thus, targeting the interactions of these two cell types could open the door to a new generation of effective therapeutic options. However, the studies on how these two cell types interact and how their crosstalk adds up to respiratory diseases are not well established. With the rise of modern research tools and technology, such as lab-on-chip, organoids, co-culture techniques, and advanced immunofluorescence imaging, a substantial degree of evidence about these cell interactions emerged. Hence, this contribution aims to review the growing evidence of bronchial epithelial cells and airway smooth muscle cells crosstalk under normal and pathophysiological conditions. The review first deliberates the effects of both healthy and stressed epithelial cells on airway smooth muscle cells, taking into account three themes; contraction, migration, and proliferation. Then, it discusses the impact of airway smooth muscle cells on the epithelium in inflammatory settings. Later, it examines the role of airway smooth muscle cells in the early development of bronchial epithelial cells and their recovery after injury.
Rationale: Chronic obstructive pulmonary disease (COPD) is a prevalent respiratory disease lacking effective treatment. Focusing on the early stage of COPD should help to discover disease modifying therapies. Objectives: In this study, we examined the role of the CXCL12/CXCR4 axis in both a mouse model of early COPD and in human samples from COPD patients. Methods: To generate the early COPD model, mice were exposed to cigarette smoke (CS) for 10 weeks and intranasal instillations of polyinosinic-polycytidylic acid (poly(I:C)) for 5 weeks to mimic exacerbations. Measurements and Main Results: Exposed mice presented mild airway obstruction, peri-bronchial fibrosis and right heart remodeling. CXCR4 expressing cells number was increased in the blood of exposed mice, as well as in the blood of patients with COPD. Lung CXCL12 expression was higher in both exposed mice and early COPD patients. The density of fibrocytes expressing CXCR4 was increased in the bronchial submucosa of exposed mice. Conditional inactivation of CXCR4 at adult stage as well as pharmacological inhibition of CXCR4 with plerixafor injections improved lung function, reduced inflammation and protected against CS and poly-(I:C)-induced airway and cardiac remodeling. CXCR4-/- and plerixafor-treated mice also had less CXCR4-expressing circulating cells and a lower density of peri-bronchial fibrocytes. Conclusions: We demonstrate that targeting CXCR4 has beneficial effects in an animal model of early COPD and provide a framework to translate these preclinical findings to clinical settings within a drug repurposing approach.
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