Reduced Type I and Type III Procollagens in Photodamaged Adult Human Skin
Journal of Investigative Dermatology
We have quantitatively assessed the relation between type I and type III procollagen precursor levels and the severity of clinical photodamage in human skin. Levels of procollagen, pN collagen (collagen without the carboxypropeptide), and/or pC collagen (collagen without the aminopropeptide) were determined by radioimmunoassay, Western blot, and immunohistology in punch biopsy specimens from mildly and severely photodamaged forearm skin and from sunprotected underarm and buttock skin of the
... subjects. Collagen precursor levels in forearm and underarm skin were expressed relative to buttock levels for comparison. In the mildly photodamaged group, collagen precursors in the forearm did not differ from those in the underarm by any measurement, except for type I collagen precursors measured by radioimtnunoassay, which were reduced 16%. In severely photodamaged forearm skin, both type I and type ill collagen precursor levels, measured by radioimmunoassay, were significantly reduced (approximately 40%). Western analysis revealed similar signifi-T h e extracellular m atrix of the d ermis provid es stren g th and resi li en cy to ski n, and accumulatin g evide n ce sugges ts that alte ra tion s in the d e rm al extr ace llular matrix are p.-imarily respo n sible for the clinical appea rance of photodamaged skin [1 ,2]. Dermis contains predominantly typ e I coll agen, with lesse r amounts of type [Il collage n . The individual pol ypeptide chains of typ es l and III collage ns are synth esized b y d e rmal fibrobla sts as prec m so r molec ules, procoUagens, whi ch contain g lobu lar amino and ca rboxy terminal d o m a ins. Within th e cell , the individual chains asse mbl e into trimeric type I or III procolla gens, whi c h are secre te d into th e extracellular space as solubl e proteins. Durin g formation of Manuscript received J anuary 27, 1994; final revision received March 24 , 1995; accepted for pubLi cation May 2, 1995. Reprint req uests to : Dr. Gary]. Fisher, Departm ent of Dermatology, Kresge I, R 6558, University of Michigan, Ann Arb or, Ml 48109. A bbrev iatio ns: PI C P, type I procollagcn carboxyterminal propeptide measured by radioimmunoassa)'; Pll!NP, type Ill procollagen aminoterminal propeptidc measured by radioimmunoassay; type I pC coll agen. type I procoll agen without the aminopropeptide; type I pN collagen. type I procollagen without the carbo,.:ypropeptide; type Ill pC coll agen. type Ill procollagen w ithout the aminopropeptide; type Ill pN collagen, type lll procollagcn without the c:u·boxypropcptide. T he first two authors made equivalen t contribu tions to this work. C hri stop her E. M. Griffith's present address: Section of Dermatology. Urrivers ity of Man chester. School of Med icin e, Man chester, U.K.