Collagen synthesis in human skin in vivo: modulation by aging, ultraviolet B irradiation and localization.

The effect of aging, sex, skin location and a short whole body ultraviolet B (UVB) phototherapy on type I and type III skin collagen synthesis were studied by measuring carboxy- and aminoterminal propeptides of type I and aminoterminal propeptide of type III procollagens (PICP, PINP and PIIINP, respectively) in suction blister fluid (SBF). The concentrations of PICP and PIIINP correlated negatively with age in the material of 30 men and 27 women (age range 23-86 years, mean age 51 years). As the subjects were divided into 3 age groups (23-34, 35-54 and 55-86 years) and the mean concentrations of the procollagens were compared between the groups, the youngest age groups in men and in the whole material had significantly higher concentrations than the two older age groups. These results confirm the previous results, which have shown by other methods that skin collagen synthesis decreases during aging. SBF was also obtained from 4 different body regions (back, arm, abdomen and leg) of 5 young male subjects and from 2 different body regions (abdomen and thigh) of 9 older subjects. Wide individual range in the concentrations of PICP, PINP and PIIINP was noticed but, in general, none of the body regions seemed to have more excessive collagen synthesis than the other ones. SBF was further collected from abdominal skin of 8 young male dermatological patients receiving UVB phototherapy. When the concentrations of PICP and PIIINP in SBF obtained before the treatment, after the treatment and from the covered control area were compared no statistical differences were noted, suggesting that short UVB treatment has no effect on skin collagen synthesis in vivo.