Gross Cystic Disease Fluid Protein 15 in Stratum Corneum Is a Potential Marker of Decreased Eccrine Sweating for Atopic Dermatitis

It is well known that eccrine sweating is attenuated in patients with atopic dermatitis (AD). We have reported by using proteome analysis that gross cystic disease fluid protein 15 (GCDFP15), a substance secreted from eccrine sweat glands, is decreased in tape-stripped stratum corneum (SC) samples from AD patients. The aim of this study was to evaluate GCDFP15 production by eccrine glands with SC samples and to assess sweating in AD. SC samples were obtained from 51 healthy control (HC) and 51 AD individuals. Sweat samples were from 18 HC and 12 AD subjects. GCDFP15 was quantified by ELISA. By immunohistochemistry, the expression of GCDFP15 in eccrine glands was examined in normal and AD skin specimens. To identify GCDFP15-producing cells, double immunofluorescence staining for GCDFP15 and S100 protein was performed in frozen sections. To address the mechanism underlying the decreased eccrine sweating in AD patients, we examined the expression of cholinergic receptor M3 (CHRM3), a receptor for acetylcholine-induced sweating, in eccrine sweat glands. The amounts of GCDFP15 in the SC extracts were significantly lower in AD than HC (P < 0.0001). The sweat samples from AD patients also had lower levels of GCDFP15 concentration (P < 0.05). Immunohistochemistry showed positive GCDFP15 staining in the eccrine gland secretory cells and the ductal and acrosyringial lumen in normal skin, but AD lacked clear staining. Immunofluorescence staining revealed that GCDFP15 was co-expressed with S100 protein, suggesting that the clear cell of eccrine glands produces GCDFP15. Finally, we found that the expression of CHRM3 was depressed in AD, suggesting contribution to the low sweating. The SC of AD patients contains a low amount of GCDFP15 due to both low sweating and low GCDFP15 concentration in the sweat. GCDFP15 in SC is a potential marker for dysregulated sweating in AD.