Neutrophil elastase cleaves VEGF to generate a VEGF fragment with altered activity

Abstract

Excessive neutrophil elastase (NE) activity and altered vascular endothelial growth factor (VEGF) signaling have independently been implicated in the development and progression of pulmonary emphysema. In the present study, we investigated the potential link between NE and VEGF. We noted that VEGF(165) is a substrate for NE. Digestion of purified VEGF(165) with NE generated a partially degraded disulfide-linked fragment of VEGF. Mass spectrometric analysis revealed that NE likely cleaves VEGF(165) at both the NH(2) and COOH termini to produce VEGF fragment chains approximately 5 kDa reduced in size. NE treatment of VEGF-laden endothelial cell cultures and smooth muscle cells endogenously expressing VEGF generated VEGF fragments similar to those observed with purified VEGF(165). NE-generated VEGF fragment showed significantly reduced binding to VEGF receptor 2 and heparin yet retained the ability to bind to VEGF receptor 1. Interestingly, VEGF fragment showed altered signaling in pulmonary artery endothelial cells compared with intact VEGF(165). Specifically, treatment with VEGF fragment did not activate extracellular-regulated kinases 1 and 2 (ERK1/2), yet resulted in enhanced activation of protein kinase B (Akt). Treatment of monocyte/macrophage RAW 264.7 cells with VEGF fragment, on the other hand, led to both Akt and ERK1/2 activation, increased VEGFR1 expression, and stimulated chemotaxis. These findings suggest that the tissue response to NE-mediated injury might involve the generation of diffusible VEGF fragments that stimulate inflammatory cell recruitment and activation via VEGF receptor 1.

Expanding the Clinical Indications for α1-Antitrypsin Therapy

“…In various studies, AAT has been shown to induce vascular endothelial growth factor (VEGF) production (55)(56)(57) and to prevent proteolytic degradation of VEGF (58). In addition, AAT was shown to facilitate smooth muscle myocyte migration and proliferation (59) and reduce endothelial cell and smooth muscle cell apoptosis (55,56,60,61).…”

RIG-like Helicase Innate Immunity Inhibits Vascular Endothelial Growth Factor Tissue Responses via a Type I IFN–dependent Mechanism

“…More recently it has been shown to confer protection against injury and oxidative stress. This protection may be particularly important in the respiratory alveolus because pharmacological inhibition of VEGF activity and lung-targeted inactivation of the VEGF gene result in emphysematous phenotypes whereas VEGF expression diminishes emphysema in murine modeling systems (11,14,16,(32)(33)(34)49). In accordance with this finding, a number of investigators have reported decreased levels of VEGF expression/ accumulation in biological samples from patients with emphysema (16,33,(35)(36)(37).…”

“…This may be clearly seen in the lung, where studies from our laboratory and others have demonstrated that VEGF overexpression induces tracheal angiogenesis, tissue edema, parenchymal inflammation, dendritic cell activation, airway fibrosis, mucus metaplasia, enhanced helper T-cell type 2 (Th2)-and IL-13-induced tissue responses and cytoprotection in the setting of oxidant injury (5,12). In accordance with these varied responses, normal lung development, baseline lung function, and the ability of the lung to respond to injury appear to be critically dependent on the presence of local functional VEGF (12)(13)(14)(15)(16). VEGF excess has been implicated in the pathogenesis of a variety of disorders including pulmonary edema and asthma (5,16,17).…”

Mesenchymal stem cell-based HSP70 promoter-driven VEGFA induction by resveratrol alleviates elastase-induced emphysema in a mouse model

“…Thus, all evidence supports a Bvascular hypothesis^as a major feature of COPD pathophysiology (Henson et al 2006). Moreover, VEGFA may be partially cleaved by neutrophil elastase (NE), generating a VEGFA fragment with altered activities (Kurtagic et al 2009). The resulting binding by the altered receptor is translated to a loss of signaling potentials in endothelial cells and hinders lung vascular functions (Kurtagic et al 2009).…”