ULTRAVIOLET-B RADIATION INCREASES STEADY-STATE MESSENGER-RNA LEVELS FOR CYTOKINES AND INTEGRINS IN HAIRLESS MOUSE SKIN - MODULATION BY TOPICAL TRETINOIN

Chronically sun-damaged human skin has a wrinkled, aged appearance as a result of alterations in the dermal extracellular matrix, Secondary effectors such as cytokines and integrins may mediate the effects of U V radiation on the skin by regulating the synthesis of metalloproteina ses and structural proteins including collagen, The aim of this study was to semiquantify the steady-state mRNA levels of interleukin-1 alph a, tumor necrosis factor alpha, transforming growth factor beta collag enase, stromelysin, collagen, and integrins (alpha(1) and alpha(2)) in the skin of hairless mice that were? either treated with UV or concur rently treated with UV and topical tretinoin for 5 weeks, Total RNA wa s extracted from the skin of the mice, reverse transcribed to cDNA, an d amplified by the polymerase chain reaction in the presence of P-32-d CTP using gene-specific primers, Results were normalized relative to g lyceraldehyde-3-phosphate dehydrogenase levels, Steady-state mRNA leve ls of the cytokines and integrins were increased by UV radiation, Conc urrent UV and topical tretinoin treatment superinduced the expression of interleukin-1, increased alpha(1) and decreased alpha(2) integrin e xpression. Immunofluorescence analysis showed increased dermal localiz ation of beta(1) integrin in UV and tretinoin treated skin, These resu lts suggest that cytokines and integrins may be involved in the mechan ism of photodamage.