Role of Heparan Sulfate NDST-1 in Allergic Inflammation and Airway Remodeling

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Allergic asthma is a chronic inflammatory disorder of the airways. There is good evidence that many of the features of asthma, including airway remodeling (AR) are largely due to inappropriate activation of T cells and consequent imbalance of Th1/Th2 cytokines and the recruitment if inflammatory cells including macrophages to the airway. However, the role of heparan sulfates (HS) in the modulation of airway allergic responses and airway remodeling are poorly understood. Heparin and HS interact with various components of the inflammatory cascade in vitro, such as P- and L-selectins, inflammatory mediators, proteoglycans, growth factors cytokines and chemokines to mediate leukocyte migration, endothelial proliferation and tissue remodeling. However the role of endothelial and leukocyte expressed HS in allergic inflammation and AR has never been determined. To study the significance of HS in AR, glucosaminyl N-deacetylase/N-sulfotransferase- 1 (NDST1) was knocked out in endothelial cells (EC) and leukocytes using the Cre-loxP system. The NDST-1-deficient mice (NDST1f/fTie2Cre+) showed impaired inflammatory responses in multiple types of assays in vitro and in vivo. Based on our preliminary observations that lack of NDST-1 in allergenchallenged mice leads to altered leukocyte trafficking, impaired macrophage but not eosinophil recruitment in the airways, reduced expression of the Th2 cytokine IL-5, TGF-beta1 and AHR, along with diminished EC proliferation, we postulate that the targeted deficiency of NDST-1 will result in abrogation of the inflammatory conditions associated with allergen-induced inflammation and AR. To examine this, two specific aims are proposed. In the first specific aim we will assess the role of HS biosynthetic enzyme NDST-1 in the expression of Th2 cytokines, generation and recruitment of macrophages and macrophage progenitor cells to the airways and trafficking of mononuclear cells within the pulmonary vascular bed in the remodeled airways of allergen mice. In this aim the ability of bone marrow derived CD34+ progenitors cells to interact with murine lung EC in the context of HS expression will be examined in NDST1f/fTie2Cre+ mutant and NDST1f/fTie2Cre- wild type mice. In the second specific aim we will delineate the role of HS/NDST-1 in allergen-mediated AR and pulmonary angiogenesis associated with repetitive allergen challenge. Specifically, we will examine the role of HS/NDST-1 on the release of TGF-beta1, MMP-9, FGF-2 and VEGF by macrophages and other inflammatory cells and their effect on the cellular features of airway remodeling. We will also examine the role of NDST-1 and HS to modulate trafficking of inflammatory leukocytes with angiogenic blood vessels of the NDST-1 deficient and wild type mice exposed to repetitive allergen challgenge. Overall we will attempt to delineate the functional importance of EC vs. leukocyte expressed HS by NDST-1 in airway remodeling and airway allergic inflammation.