Nasal administration of interleukin‐33 induces airways angiogenesis and expression of multiple angiogenic factors in a murine asthma surrogate

Abstract

SummaryThe T-helper cell type 2-promoting cytokine interleukin-33 (IL-33) has been implicated in asthma pathogenesis. Angiogenesis is a feature of airways remodelling in asthma. We hypothesized that IL-33 induces airways angiogenesis and expression of angiogenic factors in an established murine surrogate of asthma. In the present study, BALB/c mice were subjected to serial intranasal challenge with IL-33 alone for up to 70 days. In parallel, ovalbumin (OVA) -sensitized mice were subjected to serial intranasal challenge with OVA or normal saline to serve as positive and negative controls, respectively. Immunohistochemical analysis of expression of von Willebrand factor and erythroblast transformation-specific-related gene, both blood vessel markers, and angiogenic factors angiogenin, insulin-like growth factor-1, endothelin-1, epidermal growth factor and amphiregulin was performed in lung sections ex vivo. An established inhouse assay was used to test whether IL-33 was able to induce microvessel formation by human vascular endothelial cells. Results showed that serial intranasal challenge of mice with IL-33 or OVA resulted in proliferation of peribronchial von Willebrand factor-positive blood vessels to a degree closely related to the total expression of the angiogenic factors amphiregulin, angiogenin, endothelin-1, epidermal growth factor and insulin-like growth factor-1. IL-33 also induced microvessel formation by human endothelial cells in a concentration-dependent fashion in vitro. Our data are consistent with the hypothesis that IL-33 has the capacity to induce angiogenesis at least partly by increasing local expression of multiple angiogenic factors in an allergen-independent murine asthma surrogate, and consequently that IL-33 or its receptor is a potential novel molecular target for asthma therapy.

The effects of interleukin‐33 on airways collagen deposition and matrix metalloproteinase expression in a murine surrogate of asthma

“…Previous studies have strongly implicated IL‐33 in playing a key role in the pathogenesis of the airways mucosal inflammation that typically accompanies human asthma . In our own previous studies we showed that direct, per‐nasal application of IL‐33 alone to the murine airway is sufficient to cause asthma‐like inflammation, including subepithelial deposition of collagens .…”

“…Murine surrogates of asthma induced by IL‐33 or OVA challenge were prepared and studied as previously described . Briefly, recombinant murine IL‐33 (rmIL‐33, 100 ng in 50 μl saline; R&D Systems, Minneapolis, MN) or saline control was administered per‐nasally directly to the airways of two groups of mice daily from days 18–23 from the commencement of the experiment, then every 2 days until day 53.…”

“…Immunoreactivity was measured using a Nikon microscope (Nikon, Tokyo, Japan) connected with a computer imaging system and analysed using proprietary software ( image‐pro plus 6.0; Media Cybernetics, Silver Spring, MD). The data were expressed as percentages of the positively stained areas in the entire lung sections as previously described …”

“…Specific inhibition of IL‐33 or its receptor ST2 has been reported to abrogate airways inflammation, mucus hypersecretion and airways hyper‐responsiveness in murine surrogates of asthma . Our own previous findings have shown that direct, per‐nasal application of IL‐33 alone to the respiratory tract can induce typical asthma‐like features in mice, including airways eosinophilic mucosal infiltration, hyperresponsiveness and neoangiogenesis . Recent studies indicate that IL‐33 is able to exert some of these effects indirectly by activating airways mucosal group 2 innate lymphoid cells (ILC2), inducing the latter to produce T helper type 2‐type cytokines .…”

An Imbalance between Proteases and Endogenous Protease Inhibitors in Eosinophilic Airway Disease

“…In addition there is evidence, at least from animal surrogates, that these cytokines can effect many of the aspects of airways remodelling deemed characteristic of asthma, such as neoangiogenesis (5). A range of both endogenous, local stimuli as well as external, environmental stimuli can elicit epithelial release of these cytokines -one such category of stimuli is endogenous and environmental proteases.…”