In vitro studies on lipid metabolism in Keratinocytes of different racial origin

Abstract

Lipids play a predominant role in the barrier function of the skin, with different lipid classes playing unique parts in the maintenance of a competent barrier. Comparison of clinical studies conducted on Indian and Caucasian volunteers reveal differences in their skin lipid profile. Our study aimed to examine the possible reasons behind this observation, by evaluating lipid profiles of epidermal keratinocytes from Caucasian and Indian origin cultured under various growth conditions, and expression profiles of genes involved in lipid metabolism. We have not found much difference in the constitutive lipid profiles between cultured keratinocytes having different ethnic origin, both in the proliferating as well as differentiated states, except in case of cholesterol sulphate and phospholipids, which seem to be markedly increased in the Caucasian cells. When the cells were given high-glucose treatment for 48h, Indian cells show increased levels glycerolipids and cholesterol esters as opposed to Caucasians, with differentiation also influencing the lipid profiles. LDL treatments also show an increase in levels of glycerolipids and cholesteryl esters in Indians, which might be due to uptake. Further, qRT-PCR studies showed that there were no stark differences in expression patterns of genes involved in ceramide or cholesterol metabolism between the two groups, whereas those for glycerolipid metabolism showed some characteristic differentiation associated trends, and also higher expression in Indian keratinocytes, notably in DGAT2, which catalyzes the final step in biosynthesis of triglycerides. Physiological significance of our results may be predicted only after further confirmation with multiple sets of cultures and in vivo studies. Trends are indicative and give possible directions which may be explored to give conclusive answers.