Immediate and extended effects of abrasion on stratum corneum natural moisturizing factor.

BACKGROUND

Natural moisturizing factor (NMF), principally comprised of hygroscopic amino acids and derivatives that absorb moisture from the surrounding environment, serves as the primary humectant of the stratum corneum (SC). Acute barrier disruption has been shown to differentially affect the concentration of NMF in the SC. This study measured the recovery kinetics of NMF after mechanical damage of the SC, which is not well understood.

METHODS

The study population included 20 healthy female volunteers (18-72-year old) with no history of dermatological disorders. Transepidermal water loss (TEWL), erythema, and SC water and NMF were measured at all sites before abrasion, 30 min following abrasion, and 1-3, 6, 8, and 10 days following abrasion. Measurements obtained from the abraded site were compared with those obtained from an untreated site.

RESULTS

As expected, both TEWL and erythema increased significantly with abrasion. Erythema and TEWL values remained higher at the abraded site for 2 and 6 days, respectively, after abrasion. No changes in NMF component levels in the SC were observed at 30 min after abrasion. One day following abrasion, reduced levels of glycine, histidine pH4, trans-urocanic acid (tUca) pH4, and tUca pH8 were observed. In addition, a significantly lower level of serine was observed at the abraded site 2 and 6 days following abrasion. Within 8 days after abrasion, these components returned to levels comparable to those observed in untreated skin. Throughout the study, no differences were observed in the level of water in the SC.

CONCLUSION

These results demonstrate that acute barrier disruption induced by mechanical abrasion has relatively little impact on biochemical events responsible for NMF generation. Though reductions in certain NMF components were observed, abrasion had no measureable effect on SC water content over the duration of the study. This implies that the reduced NMF components may not contribute substantially to water retention in the SC. The reduced components belong to a group of NMF molecules thought to be principally derived through degradation of S-100 proteins in the epidermis. NMF components measured in this study that are derived from sweat and/or urea cycling were not impacted. These data imply that while abrasion elicits clinical signs of barrier disruption within the SC, effects on its biochemical constituents and ability to retain water are relatively minor.