Variation in the activities of late stage filaggrin processing enzymes, calpain‐1 and bleomycin hydrolase, together with pyrrolidone carboxylic acid levels, corneocyte phenotypes and plasmin activities in non‐sun‐exposed and sun‐exposed facial stratum corneum of different ethnicities

Abstract

Variation in PCA levels has been found for different ethnic groups in this study (AA > BA > C subjects). The values in the AA subjects are surprising as one might expect that the lack of pigmentation, and thereby increased photodamage, might lead to lower levels. Increased BH, but not C-1 activity, was observed in the AA subjects indicating that BH is associated with PCA production to a greater extent. Surprisingly, corneocyte maturation is still impaired with elevated PCA levels in AA subjects. The higher levels of plasmin and BH activities on the cheeks, especially for AA and C subjects, suggest that they can be used as markers for epidermal photodamage.

The effect of photodamage on the female Caucasian facial stratum corneum corneome using mass spectrometry‐based proteomics

“…Indeed, dramatically higher levels of the desquamatory‐associated serine protease kallikrein 7 were observed in the cheek samples (4.27×) as well as kallikrein 10 (2.39×) which is consistent with our previously reported enzyme activity data . Moreover, increases in levels of cathepsin L2 and D were observed which have also been associated with desquamation .…”

“…Despite this, increased levels of SASPase, bleomycin hydrolase, caspase‐14 and calpain‐1 were observed on the cheek. The latter is not consistent with our activity measurements, and its activity may be compensated by increased expression of calpastatin on the cheek (see Table ) . Equally, the increased levels of prostasin on the cheek should also increase the processing of profilaggrin .…”

“…Increased levels of Serpin B13 were also observed on the cheek and may also inhibit cathepsin L, calpain‐1 and some serine proteases. Nevertheless, our previous work indicated increased desquamation on the cheek, and as a result, the protease–anti‐protease balance must be in favour of proteolysis on the cheek . Increased levels of puromycin‐sensitive aminopeptidase may be involved in general proteolysis pathways which was the major protease increased on the cheek samples, but its role in corneodesmolysis is unknown.…”

Early-life regional and temporal variation in filaggrin-derived natural moisturizing factor, filaggrin-processing enzyme activity, corneocyte phenotypes and plasmin activity: implications for atopic dermatitis

“…We show that the cheek CE is immature from birth and does not improve rapidly with age. Therefore, cheek CE immaturity is present from birth and persists into adulthood . In adults, facial TEWL is much higher than that of the forearm and upper arm .…”

“…The same 37 individuals were assessed for plasmin, C‐1 and BH activities. Protease activities were determined on the fifth tape stripping using previously reported methods …”