Mucosal Vaccination Site

Mucosal surfaces serve a wide range of functions: exchange of gasses (lungs), nutrient transport (digestive tract), sensory (nose, mouth and throat), and reproductive signals. Compared to other body surfaces, the mucosal system, because of its large surface areas and interaction with the outside world, is the most vulnerable to infection.

VaxDesign has been able to develop an alveolar mucosal model, a bilayer construct comprising primary alveolar epithelial and endothelial cells. Extracellular matrix based materials were selected to promote the Type II epithelial phenotype and function. The majority of human pathogens are encountered at a mucosal surface; in addition to providing protection against naturally acquired pathogens, the mucosal vaccination site has great attraction for the development of mucosal protective vaccines. The respiratory system in particular, with its great surface area and large population of immune cells, provides an attractive target for immunization.

Upon successful expanding and co-culturing human epithelial and endothelial cells on porous scaffolds, we visualized cell morphology and activity with TEM and immunohistochemistry of an in vitro alveolar construct. It was especially important to show significant presence of Type II alveolar epithelial cells. These cells participate in vivo in primary inflammatory and immune reaction of lung mucosa towards external contaminants and pathogens. Type II cells produce lung surfactant substance that consists of a number of lipoproteins and specifically surfactant proteins able to bind polysaccharides of bacterial membranes, and enhance protective release of oxygen radicals by alveolar macrophages.

Our results show the ability to promote the growth of Type II alveolar epithelial cells. Having a construct with Type II epithelial cells is significant because our goal is the creation of a functional mucosal construct for testing various immunology applications.

Immunosuppressant hormonal treatment (dexamethasone, hydrocortisone) effects on cytokine production in the bilayeralveolar construct. AEpi = alveolar epithelial cells, AEC = alveolar endothelial cells, control = no hormonal treatment, DM = dexamethasone(0.1uM), HC = hydrocortisone (10uM)

To test the usefulness of the alveolar construct, the effect of immunosuppressant hormonal treatment (dexamethasoneand hydrocortisone) along with environmental particulate exposure (NIST standards Diesel Particulate Matter (SRM 2975), and Urban Dust (SRM 1649a) was studied by quantifying the cytokine production by the mucosal tissue. The addition of dexamethasoneand hydrocortisone to the bilayermucosal construct resulted in a significant decrease in cytokine production by the native cells. The immunosuppressant hormonal effect was clearly observed in GM-CSF, Eotaxin, MCP-1, IL-6, IL-8, and IL-12. The results are in good accord with in vivo expectations.