A ROLE FOR NEUTROPHIL ELASTASE IN THE PROGRESSION OF SOLAR ELASTOSIS

Hairless (SKH-1) mice were mated with Beige (C57B/bb) mice to produce a hairless mouse deficient in neutrophil elastase (hhbb). These mice w ere exposed to 0.091 UVB irradiation for 5 months to see if neutrophil elastase was an important factor in elastin remodeling and developmen t of solar elastoses. Analysis of peritoneal neutrophils confirmed mat the hhbb mouse was deficient in elastase, retaining only 10% as much activity as the normal littermates (hhHb). Skin MPO activity was equal ly elevated in all the mice receiving UVB suggesting an equal influx o f inflammatory cells. The absolute breaking strength of the skin in bo th the hhBb and hhbb mice was not altered by UVB treatment over the 5 month exposure period. Elastin quantitated biochemically as desmosine, or visualized histologically, was increased following WE exposure in the normal mice. In the elastase deficient mice, however, the elastin fibers appeared to be unaffected by exposure to UVB irradiation at thi s level. The results suggest that neutrophil elastase is an important mediator in the development of solar elastosis resulting from continue d exposure to UVB irradiation.