CYTOKINES AND GROWTH-FACTORS INFLUENCE HAIR-GROWTH IN-VITRO - POSSIBLE IMPLICATIONS FOR THE PATHOGENESIS AND TREATMENT OF ALOPECIA-AREATA

Factors that influence the growth of the anagen hair follicle or initi ate the switch to a catagen growth pattern have so far not been defini tely determined, but there is increasing evidence that cytokines and g rowth factors play an important role during these processes. Recently we detected an aberrant in situ expression pattern of cytokines of the Th1 type (IFN gamma, IL-2) plus IL-1 beta expression in untreated alo pecia areata (AA), and a switch to high levels of IL-10 TGF-beta 1 exp ression after successful treatment with the contact allergen diphenylc yclopropenone (DCP). Hence the question arose as to whether cytokines are able to arrest hair growth and whether IL-10 or TGF beta 1 have th e capacity to antagonize this process. Using whole-organ cultures of m icrodissected human hair follicles we studied the effect of a panel of cytokines and growth factors on hair growth and on the gross morpholo gy of the hair follicles in vitro. IL-2, IL-10 and IFN-gamma had no ef fect in this regard, whereas TGF beta 1 partially inhibited hair growt h and EGF, TNF alpha and IL-1 beta completely abrogated it. EGF and TN F alpha induced the formation of a club-like hair follicle, similar to catagen morphology of the hair bulb, whereas hair follicles grown in the presence of IL-1 beta or TGF beta 1 showed no particular morpholog ical changes. We conclude that cytokines and growth factors are pivota l regulators of hair growth at least in vitro. IL-1 is suggested as pl aying an important role during the pathogenesis of AA. Possible mediat ors of therapeutic contact dermatitis (IL-10, TGF beta 1, TNF alpha, P GE(2)) are, at least in vitro, not able to antagonize the IL-1 beta-tr iggered hair growth inhibition. Therefore, we infer that these mediato rs rather 'modulate' the immune response in AA.