Skin barrier function in healthy subjects and patients with atopic dermatitis in relation to filaggrin loss-offunction mutations

Patients with atopic dermatitis (AD) have a defective skin barrier even in non-lesional skin. Loss-of-function mutations in the filaggrin gene (FLG) have been suggested to contribute to the skin barrier reduction in AD. Therefore, in the present study we have investigated whether diminished skin barrier of non-lesional skin of AD patients is limited to the carriers of FLG mutations. Skin barrier was assessed by trans-epidermal water loss (TEWL) and by percutaneous penetration of polyethylene glycol (PEG 370) as determined by stratum corneum (SC) tape stripping. Compared with healthy controls wild type for FLG mutations (CTRL-wt, n = 21), AD patients with (AD-Flg, n = 18) and without (AD-wt, n = 16) FLG mutations showed elevated TEWL and diffusion of PEG370 across SC. Also subjects with healthy skin harbouring FLG mutations (n = 3) had enhanced TEWL and PEG diffusion when compared with CTRL-wt. We found no difference in TEWL or diffusion of PEG between patients with and without FLG mutations. In conclusion, this study demonstrates that AD patients, irrespective of FLG genotype have altered skin barrier as indicated by elevated TEWL and diffusion of PEG. This implies that also other factors than FLG loss-of-function mutations modulate skin barrier integrity in AD.