Changes in levels of omega‐O‐acylceramides and related processing enzymes of sun‐exposed and sun‐protected facial stratum corneum in differently pigmented ethnic groups

Abstract

Introduction:We report on the differences in ceramide composition and levels of omega-O-acylceramide processing enzymes of sun-exposed and sun-protected facialstratum corneum (SC) among Albino African, Black African and Caucasian women living in South Africa.Methods: Tape strippings were taken from the sun-exposed cheek and the sunprotected postauricular site (PA). In two subsets proteomic (n = 18) and lipidomic (n = 24) analysis were performed using mass-spectrometry-based shotgun platforms.Results: No significant differences in total ceramide levels or ceramide subtypes were found between the Black African and Caucasian women in either the cheek or PA samples. Compared to the other two groups the levels of total ceramide as well as selected omega-O-acylceramide species were increased in Albino Africans. On the cheek, ceramide (CER) EOS, EOH along with CER AS were increased relative to the Caucasian women, while CER EOP and EOdS were elevated relative to the Black African women. Moreover, on the PA site CER EOP and EOdS were elevated compared with the Black African women and CER EOdS in Caucasians. Decreasesin masslevels of 12R-LOX and eLOX3 were observed on cheeks compared with the PA sites in all ethnic groups. On the PA sites 12R-LOX was particularly lower in the Albino Africans compared with the Black African and Caucasian women. On the cheeks mass levels of SDR9C7 was also lower in the Albino Africans. Conclusion:The mass levels of the ceramides were similar between Black African and Caucasian women. However, elevated total ceramides and excessively elevated selected omega-O-acylceramides were apparent in the Albino African women. The findings in the Albino African women were unexpected as these participants suffer from impaired skin barrier function. However, the elevated levels omega-O-acylceramides can contribute to barrier insufficiency by directly

Moisturizing at a molecular level – The basis of Corneocare

“…As shown in Figure 24, for our studies, there are no differences in the 12 ceramide classes we measured on cheek SC for Black African and Caucasian females living in South Africa. However, the acylceramides we measured are elevated in skin of Albino Africans (EOS, EODS, EOH and EOP) [86]. We propose these increases are related to reductions in the corneocyte ceramide processing enzymes previously described such as reductions in 12R-LOX activity but in this study, we also demonstrated reductions in the mass levels of SDR9C7 by mass spectrometry-based proteomics in the Albino Africans.…”

A comprehensive comparison of facial skin hydration based on capacitance and conductance measurements in Chinese women

“…Preliminary research also indicates that the SC is more depleted of natural moisturizing factors in the cheek areas [ 46 ]. Compared with other non‐photodamaged sites, corneocyte envelopes are also more immature on the cheeks which relates to reduced 12R‐lipoxygenase (12R‐LOX), epidermis‐type lipoxygenase 3 (eLOX3) and transglutaminase‐1 levels and activities together with reduced ceramide EOS levels [ 47 , 48 , 49 , 50 , 51 ]. Nevertheless, more studies are needed to decipher the biological and anatomical differences on the different facial locations in order to explain the relative differences in the hydration maps between the two instruments.…”

Current insights into skin lipids and their roles in cutaneous health and disease

“…ultraviolet radiation (UVR), ozone], ageing and inflammatory disease (e.g. atopic dermatitis, psoriasis, xerosis, ichthyosis) [14–17]. Studies into the barrier function and stratum corneum lipid composition of ethnic or pigmented skin are so far inconclusive, with more work needed to identify any potential differences [18,19].…”

“…ultraviolet radiation (UVR), ozone], ageing and inflammatory disease (e.g. atopic dermatitis, psoriasis, xerosis, ichthyosis) [14][15][16][17]. Studies into the barrier function and stratum corneum lipid composition of ethnic or pigmented skin are so far inconclusive, with more work needed to identify any potential differences [18,19] Sphingomyelin, a sphingolipid providing ceramides via a hydrolysis pathway, can also contribute to the maintenance of the skin barrier via phosphorylation of the signal transducer and activator of transcription 3 (STAT3) [29].…”