Circadian and concentration profile of cathepsin S in sera from healthy subjects and asthmatic patients

Cathepsin S (CS) has been proposed to be associated with asthma pathogenesis but its exact role is not established. In order to understand this proposed association our objective was to follow the 24-h concentration pattern of CS in sera from apparently healthy subjects and from steroid-independent and steroid-dependent asthmatics before and after one weeks' treatment with methylprednisolone (MP) and cyclosporin A (CsA), respectively. Blood samples were collected every 4 h over a 24-h period. Statistical evaluation of data for time effect was performed by one way ANOVA and least-squares fit of 24-h cosine. Little or no significant change of CS concentrations with time over a 24-h period was observed in healthy and asthmatic sera. CS concentrations were significantly lower in steroid-independent asthmatics compared to controls while there was no difference between healthy subjects and steroid-dependent asthmatics. After one week of therapy MP decreased CS concentrations while CsA had no effect. Our data suggest the involvement of CS in asthma pathogenesis and the potential use of CS levels as an additional biological parameter for monitoring the extent of disease and response to therapy.