Trichophyton tonsurans exocellular protease expression: correlation with clinical presentation in tinea capitis

Tinea capitis remains an overwhelmingly prevalent disease in children. Despite the fact that it was described over a century ago, disease pathogenesis remains incompletely characterized. This investigation was designed to evaluate whether inter-strain variability in fungal protease expression for clinical Trichophyton tonsurans isolates correlates with disease severity. Children with tinea capitis were enrolled and a clinical severity score (CSS) determined for all subjects by grading eight symptoms on a 4-point scale. Fungal specimens were collected by brush culture, placed in aqueous medium and incubated at 32 degrees C for 5 days. The culture supernatant was lyophilized and aliquots used to characterize protease activity. Enzyme activity, normalized to total soluble protein, varied 550-fold, 150-fold and 6-fold for collagenase, elastase and keratinase, respectively. A significant decrease in elastase and collagenase activity was observed with increasing duration of infection. In one-half of the children, CSS increased in direct response to collagenase and elastase production, while CSS was independent of enzyme activity in the remaining children. The relationship between enzyme activity and time course of disease are consistent with theories on enzyme regulation in dermatophytoses; however, the finding that two potential subsets of children exist with varied response to fungal antigens has yet to be described.