A Plant Proteinase Inhibitor from Enterolobium contortisiliquum Attenuates Pulmonary Mechanics, Inflammation and Remodeling Induced by Elastase in Mice.

Osmar Theodoro-Júnior,Beatriz Saraiva-Romanholo,Maria Oliva,Bruno Martins-Oliveira,Yara Lobo,Nathalia Pinheiro,Mílton Martins,Leandro Oliva,Carla Prado,Renato Righetti,Iolanda Tibério,Edna Leick,Rafael Almeida-Reis

doi:10.3390/ijms18020403

Abstract

Proteinase inhibitors have been associated with anti-inflammatory and antioxidant activities and may represent a potential therapeutic treatment for emphysema. Our aim was to evaluate the effects of a plant Kunitz proteinase inhibitor, Enterolobium contortisiliquum trypsin inhibitor (EcTI), on several aspects of experimental elastase-induced pulmonary inflammation in mice. C57/Bl6 mice were intratracheally administered elastase (ELA) or saline (SAL) and were treated intraperitoneally with EcTI (ELA-EcTI, SAL-EcTI) on days 1, 14 and 21. On day 28, pulmonary mechanics, exhaled nitric oxide (ENO) and number leucocytes in the bronchoalveolar lavage fluid (BALF) were evaluated. Subsequently, lung immunohistochemical staining was submitted to morphometry. EcTI treatment reduced responses of the mechanical respiratory system, number of cells in the BALF, and reduced tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), matrix metalloproteinase-12 (MMP-12), tissue inhibitor of matrix metalloproteinase (TIMP-1), endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS)-positive cells and volume proportion of isoprostane, collagen and elastic fibers in the airways and alveolar walls compared with the ELA group. EcTI treatment reduced elastase induced pulmonary inflammation, remodeling, oxidative stress and mechanical alterations, suggesting that this inhibitor may be a potential therapeutic tool for chronic obstructive pulmonary disease (COPD) management.

Highlights

Chronic obstructive pulmonary disease (COPD) is the major pulmonary cause of chronic morbidity and is one of the most important causes of death in most countries [1]
There was a significant increase in Ers in the elastase (ELA) groups when compared to the saline (SAL) control and SAL-Enterolobium contortisiliquum trypsin inhibitor (EcTI) groups (p < 0.05)
There was a significant decrease in respiratory system resistance (Rrs) in the ELA-EcTI and SAL-EcTI groups when compared with the ELA and SAL groups (p < 0.05)

Summary

Introduction

Chronic obstructive pulmonary disease (COPD) is the major pulmonary cause of chronic morbidity and is one of the most important causes of death in most countries [1] The physiopathology of this disease, characterized by a mixture of small airway disease (obstructive bronchiolitis) and parenchymal destruction (emphysema), leads to obstructive processes and airflow limitations [2]. According to the proteinase-antiproteinase hypothesis, cigarette smoke causes inflammation and the subsequent release of proteolytic enzymes into the lung in excess of their natural inhibitors. In this way, elastase secreted by neutrophils and macrophages plays an important role in alveolar wall destruction [3,4]. This model has been used to elucidate the mechanisms involved in emphysema pathophysiology and to test new therapeutic agents [6]

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