Variants of mast cell tryptase as markers and mediators of inflammation and tissue remodelling in asthma

Asthma and other allergic diseases represent a major health problem in this country. These conditions are associated with the release into the lungs of substantial quantities of an enzyme called tryptase. This has become a new target for drug development.
There are multiple forms of tryptase, prominent among which are the alpha and beta forms. We propose to investigate the degree to which asthmatic patients may exhibit genetic differences in the tryptases they possess. The relatively little studied alpha tryptase will be purified and its properties compared with those of beta tryptase.
The pattern of release of tryptases from cells will be studied, and the extent to which they are released into blood or fluids lining the lung examined. We shall carefully investigate the ability of the different tryptases to alter the function of cells to promote inflammation and structural alterations in the lung. These studies should advance understanding of fundamental processes of allergic disease and on the new approaches to treatment directed against tryptases.

Tryptase, the major product of human mast cells, is emerging as a key mediator of inflammation and tissue remodelling in asthma and other allergic conditions. This tetrameric serine protease is often considered as a single enzyme, but multiple sequences have been derived, and a family of related proteases mapped to chromosome 16p13.3. We shall investigate the degree of genetic variation at this site in families with bronchial asthma, and examine the potential for linkage with features of disease. Alpha tryptase will be purified from a recombinant expression system and enzymatic properties investigated with synthetic and natural substrates. Comparison will be made with the more extensively studied beta tryptases, and the degree to which heterotypic tetramers may form will be examined. The cellular expression and release will be examined of alpha and beta of tryptase in vitro, and in vivo in body fluids from patients with allergic conditions. The ability of alpha tryptase to stimulate altered gene expression in epithelial cells and airway smooth muscle cells will be investigated using microarray procedures, and compared with the patterns with beta tryptase. The release of selected cytokines, matrix components or mediators, and the rate of cell proliferation in response to alpha and beta tryptases will be investigated, exploring potential proteolytic and non-proteolytic mechanisms. The abilities of alpha tryptase to provoke pro-inflammatory changes following transfer to a guinea pig model will be assessed and compared with those of beta tryptase. This integrative biology approach should yield crucial information on the mediator actions of human tryptases and their potential as targets for therapeutic intervention.