The skin barrier defect in cutaneous T-cell lymphomas (CTCL) was recently confirmed to be similar to the one observed in atopic dermatitis (AD). We have examined the expression level of cornified envelope (CE) proteins in CTCL, AD and healthy skin, to search for the differences and their relation to the courses of both diseases. The levels of FLG, FLG2, RPTN, HRNR, SPRR1A, SPRR1B, SPRR3 and LELP-1 mRNA were determined by qRT-PCR, while protein levels were examined using the ELISA method in skin samples. We have found that mRNA levels of FLG, FLG2, LOR, CRNN and SPRR3v1 were decreased (p ≤ 0.04), whereas mRNA levels of RPTN, HRNR and SPRR1Av1 were increased in lesional and nonlesional AD skin compared to the healthy control group (p ≤ 0.04). The levels of FLG, FLG2, CRNN, SPRR3v1 mRNA increased (p ≤ 0.02) and RPTN, HRNR and SPRR1Av1 mRNA decreased (p ≤ 0.005) in CTCL skin compared to the lesional AD skin. There was a strong correlation between the stage of CTCL and increased SPRR1Av1 gene expression at both mRNA (R = 0.89; p ≤ 0.05) and protein levels (R = 0.94; p ≤ 0.05). FLG, FLG2, RPTN, HRNR and SPRR1A seem to play a key role in skin barrier dysfunction in CTCL and could be considered a biomarker for differential diagnosis of AD and CTCL. SPRR1Av1 transcript levels seem to be a possible marker of CTCL stage, however, further studies on a larger study group are needed to confirm our findings.
Keywords: FLG; atopic dermatitis; cornified envelope proteins; cutaneous lymphomas; mycosis fungoides.