Recombinant Human Monocyte/Neutrophil Elastase Inhibitor Protects Rat Lungs against Injury from Cystic Fibrosis Airway Secretions

Abstract

Human monocyte/neutrophil elastase inhibitor (M/NEI) is a fast-acting stoichiometric inhibitor of neutrophil elastase (NE), cathepsin-G, and proteinase-3. Recombinant M/NEI (rM/NEI) was evaluated with a rat model of NE-induced lung damage. rM/NEI was found to protect against pulmonary injury caused by instilled human NE or by a preparation from airway secretions (sputum) of cystic fibrosis patients (CF sol). Human NE instilled into rat lungs produced dose-dependent hemorrhage and increased epithelial permeability, whereas NE incubated in vitro with rM/NEI did neither. Similarly, hemorrhage was induced by CF sol, but not by CF sol incubated in vitro with rM/NEI. To examine its distribution and survival time in airways, rM/NEI was labeled with the fluorochrome Texas Red (rM/NEI-TR) and instilled into rat lungs. Confocal microscopy showed that rM/NEI-TR could be detected on large airways (300 microm) at 5 min, 1 h, 4 h, and 24 h after instillation. Pretreating rats with rM/NEI was found to provide extended protection upon subsequent NE challenge, reducing hemorrhage by 98, 96, and 73%, respectively, at 1, 4, and 24 h after rM/NEI pretreatment. Pretreating rats with rM/NEI similarly conferred protection against subsequent exposure to CF sol, reducing hemorrhage by 95, 86, and 87%, respectively, at 1, 4, and 24 h after pretreatment. The findings that rM/NEI (1) mitigates protease-induced lung injury and (2) remains present and active in the lungs for 24 h after instillation strongly support its potential for treating patients with neutrophil protease-induced inflammatory lung damage, such as occurs in CF and other diseases.

Red blood cells increase secretion of matrix metalloproteinases from human lung fibroblasts in vitro

“…In the lung, tissue remodeling plays a prominent role in many disorders, including pulmonary fibrosis, pulmonary emphysema, chronic bronchitis, and asthma. Interestingly, a role for both MMPs and neutrophils has also been suggested in these conditions (10,15,41,45,49). Patients with idiopathic pulmonary hemosiderosis frequently develop fibrosis in the lung parenchyma (7,31), suggesting a possible role of RBC in ECM remodeling.…”

Neutrophil Elastase, Proteinase 3, and Cathepsin G as Therapeutic Targets in Human Diseases

“…In the mouse model of COPD, aerosolized human ␣1-PI, serpinB1, SLPI, reduced the severity and the extent of the elastase-induced tissue damages and airspace enlargement (Rees et al, 1999;Churg et al, 2003;Pemberton et al, 2006). We recently showed, however, a limitation of the mouse model by demonstrating the different substrate specificities of mouse and human HNE and PR3 (Kalupov et al, 2009).…”

The Serpins Are an Expanding Superfamily of Structurally Similar but Functionally Diverse Proteins

“…In addition, endogenous or exogenous ov-serpins may protect bystander cells and tissue from proteolytic damage. Studies in rats show that recombinant MNEI delivered to the airways prevents lung injury by neutrophil proteinases and point to its potential in treating inflammatory lung disease (23).…”