The hygiene hypothesis of atopy: dendritic cells come clean
10 / 2003 - 10 / 2008
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
The incidence of atopic diseases has risen dramatically over the last 50 years, possibly due to altered microbial load from the environment and conditions of increased hygiene. By recognising allergens and by stimulating naive T cells, dendritic cells (DC) are responsible for sensitisation to inhaled allergen. Through high level expression of pattern recognition receptors (PRR), these cells are also uniquely sensitive to microbial products. This project will study the interaction between house dust mite (HDM) allergen Der p 1, microbial products and DCs during the process of sensitisation. The central hypothesis of the project is that exposure to microbial products and/or allergens leads to a different differentiation program in DCs obtained from HDM allergic or non-allergic individuals. Using high throughput proteomics and non-hierarchical clustering analysis, differentially expressed protein networks will be studied that clearly segregate between allergic and non-allergic donors. The functional relevance of these proteins will be validated taking advantage of RNA interference, a novel functional genomics tool to silence gene function in human cells. Both known PRR, costimulatory molecules and newly discovered differentially expressed proteins will be silenced in DCs using lentiviral siRNA vectors. The outcome of gene silencing on the interaction between microbial products, allergens and DC-induced sensitisation of T cells will be studied in vitro and in vivo, taking advantage of a DC-driven humanised severe combined immunodeficiency (hu-SCID) model of atopic asthma. This combined set-up will allow us to discover new pathways involved in the process of sensitisation and its influence by the environment and will lead to better understanding of the hygiene hypothesis. It should pave the way to novel preventive strategies for atopic diseases.