MSCs attenuate airway remodeling in HDM-induced asthma by inhibiting the Timp1-Wnt2b axis

Abstract

MSCs have demonstrated their unique therapeutic potential in early clinical trials for a variety of respiratory diseases in recent years, but their use in the treatment of asthma has rarely been reported. In this study, a chronic murine asthma model that is more similar to clinical asthma is constructed via sustained HDM induction for 70 days, followed by treatment via tail vein injection of MSCs after modeling. The mechanism by which MSCs alleviate airway remodeling is investigated via RNA-seq. The airways on the day following treatment are used to screen for transcriptomic changes resulting from the MSC treatment under study, filtering for differentially expressed genes (DEGs), identifying their enrichment pathways, and finally confirming the DEGs gained via western blot analysis. After HDM treatment, airway remodeling is reversed, asthma and the HIF-1 signaling pathway are inhibited, and the expression levels of Timp1 and Wnt2b in the fibrosis pathway are also significantly decreased. STRING analysis reveals a reciprocal interaction in their expression, which is also confirmed by western blot analysis. To verify whether MSCs alleviate airway remodeling by inhibiting Timp1, we construct MSCs overexpressing Timp1 and evaluate their effects in vitro and in vivo. The ability of MSCs to alleviate airway remodeling is reversed after Timp1 is overexpressed. These findings demonstrate that MSCs alleviate asthma-induced airway remodeling by inhibiting the Timp1-Wnt2b axis.

1. Introduction

Asthma is one of the most prevalent chronic inflammatory respiratory diseases and is characterized by bronchoconstriction and dyspnea. Approximately 300 million people worldwide suffer from asthma, leading to one in every 250 deaths each year [1]. Recently, the combination of inhaled corticosteroids (ICSs) and long-acting β-receptor agonists (LABAs) has become the first-line therapy for the treatment of asthma. However, patients with chronic asthma suffer from long-term disease duration or poor compliance, resulting in frequently recurring exacerbations. Even if patients have been following the medication for a long time, daily exposure to ICSs and LABAs also increases their risk for metabolic diseases, osteoporosis, and infections [2]. Thus, long-term drugs with few side effects are urgently needed to improve asthma therapy.

Chronic and recurrent airway inflammation in patients with asthma results in airway remodeling, which in turn leads to airway obstruction and pulmonary dysfunction. The development of airway remodeling is often characterized by the accumulation of extracellular matrix and pulmonary fibrosis due to abnormal fibroblast proliferation, consequently resulting in thickening of the airway wall in patients [3]. The ratio of tissue inhibitors of metalloproteinases (TIMPs) to matrix metalloproteinases (MMPs) has been suggested as a biomarker for airway remodeling by numerous previous studies [4,5]. Timp1, a member of the TIMP family, inhibits the tissue damage caused by MMPs and leads to the accumulation of ECM. Therefore, reducing Timp1 expression while alleviating lung injury has the potential to treat airway remodeling in patients with asthma.

Mesenchymal stem cells (MSCs) are multipotent cells with the capacity for proliferation and differentiation and have gained attention for their potential in treating and inhibiting further development of chronic degenerative diseases [6,7]. Additionally, the use of MSCs for the treatment of an animal model of asthma has been reported, which demonstrated the ability of MSC treatment to modulate the immune microenvironment after asthma and to reverse airway remodeling after ova stimulation [8–10]. Although these studies suggest that MSCs have clinical potential for the treatment of asthma [11], there is still wide variation in response among patients treated with MSCs in clinical trials, and the specific mechanisms by which they alleviate airway remodeling are still unclear.