Dynamically upregulated mast cell CPA3 patterns in chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis

Abstract

BackgroundThe mast cell-specific metalloprotease CPA3 has been given important roles in lung tissue homeostasis and disease pathogenesis. However, the dynamics and spatial distribution of mast cell CPA3 expression in lung diseases remain unknown.MethodsUsing a histology-based approach for quantitative spatial decoding of mRNA and protein single cell, this study investigates the dynamics of CPA3 expression across mast cells residing in lungs from control subjects and patients with severe chronic obstructive pulmonary disease (COPD) or idiopathic lung fibrosis (IPF).ResultsMast cells in COPD lungs had an anatomically widespread increase of CPA3 mRNA (bronchioles p < 0.001, pulmonary vessels p < 0.01, and alveolar parenchyma p < 0.01) compared to controls, while granule-stored CPA3 protein was unaltered. IPF lungs had a significant upregulation of both mast cell density, CPA3 mRNA (p < 0.001) and protein (p < 0.05), in the fibrotic alveolar tissue. Spatial expression maps revealed altered mast cell mRNA/protein quotients in lung areas subjected to disease-relevant histopathological alterations. Elevated CPA3 mRNA also correlated to lung tissue eosinophils, CD3 T cells, and declined lung function. Single-cell RNA sequencing of bronchial mast cells confirmed CPA3 as a top expressed gene with potential links to both inflammatory and protective markers.ConclusionThis study shows that lung tissue mast cell populations in COPD and IPF lungs have spatially complex and markedly upregulated CPA3 expression profiles that correlate with immunopathological alterations and lung function. Given the proposed roles of CPA3 in tissue homeostasis, remodeling, and inflammation, these alterations are likely to have clinical consequences.

Analysis of human lung mast cells by single cell RNA sequencing

“…The tissue used was macroscopically healthy distal to the tumour, nevertheless it is of course possible that the disease has affected the included mast cells. In this context it is worth noting that CPA3 counts were high ( Figure 3 ) and CPA3 expression has been shown to correlate to decreased lung function in patients with severe chronic obstructive pulmonary disease (COPD) and idiopathic lung fibrosis (IPF) ( 50 ).…”

Identification of key genes and biological pathways in chronic obstructive pulmonary disease using bioinformatics and next generation sequencing data analysis

“…The clinical incidence of COPD is high, and its main features include expiratory airflow limitation that is not fully reversible, deregulated chronic airway inflammation, and emphysematous destruction of the lungs [2]. It might affect many other organs and cause other diseases include pneumonia [3], respiratory viral infections [4], pneumothorax [5], heart problems [6], osteoporosis [7], depression and anxiety [8], lung cancer [9], pulmonary hypertension [10], secondary polycythemia [11], idiopathic pulmonary fibrosis [12], obesity [13] and diabetes mellitus [14]. Airway inflammation is triggered by both genetic susceptibility [15] and environmental factors [16].…”

Inhaled corticosteroid responses in COPD: do mast cells hold the answer?

“…Other asthma and COPD studies have also reported that lung tissue mast cell gene expression and mast cell counts are dissociated 2 19. Increased CPA3 gene expression was demonstrated in areas of increased collagen deposition in COPD, suggesting a role for CPA3 in tissue remodelling 15. Alternatively, CPA3 may be protective by suppressing levels of vasoconstrictor and bronchoconstrictor molecules 20.…”

“…The pathophysiological role of mast cells in COPD is unclear, with studies reporting increased, similar or reduced numbers of pulmonary mast cells in COPD vs controls 13–15. There are various published mast cell signatures that can be used to understand mast cell activation, such as an 11-gene mast cell signature derived from single-cell RNA sequencing of lung tissue which includes CPA3 and was upregulated in asthma bronchial biopsies 16.…”

“…Siddhuraj et al reported a correlation between CPA3 gene expression and distal lung eosinophil counts in COPD,15 while increased CPA3 expression, within a six-gene panel, contributes to the differentiation between eosinophilic and neutrophilic predominant sputum inflammation in COPD 18. Siddhuraj et al also reported increased CPA3 gene expression in COPD versus controls, but CPA3 protein expression and mast cell numbers were similar 15. Persistent CPA3 release through small vesicles may occur in chronic inflammation, explaining high gene expression relative to intracellular protein levels.…”