The study looked at skin samples from people with eczema (atopic dermatitis), psoriasis, and healthy skin to see how much the body’s natural antimicrobial proteins, including LL‑37, are made. It found that LL‑37 levels weren’t higher in the disease groups, while other antimicrobial peptides were increased, especially different ones in eczema versus psoriasis.

Patients with atopic dermatitis (AD) are prone to have skin infections. We aimed to investigate mRNA expression levels of various antimicrobial peptides and proteins (AMPs) in AD patients, and compare it with psoriasis vulgaris (PV) patients and healthy subjects. Skin biopsies were obtained from healthy subjects and patients with AD and PV. Quantitative real-time RT-PCR was used to determine the mRNA levels of human beta-defensin (hBD)-1, hBD-2, hBD-3, LL-37, psoriasin, RNase 7, interferon-gamma, and interleukin-10 (IL-10). Except for LL-37, mRNA of hBDs, psoriasin, and RNase 7 was significantly higher expressed in AD (n = 42) and/or PV (n = 35) patients when compared to controls (n = 18). While PV lesions showed significantly higher mRNA hBD-2 levels than lesions of AD, the latter was associated with significantly higher mRNA levels of RNase 7 when compared to PV. A significant positive correlation of hBD expression was observed both in AD patients and PV patients. hBD mRNA levels of AD skin correlated with psoriasin and RNase 7 levels. hBD-1 mRNA expression correlated with AD activity and IL-10 mRNA expression. Most AMPs investigated in this study proved to be overexpressed in AD as well as PV when compared to controls. However, a statistically significant difference in AMP mRNA expression between AD and PV was only found for hBD-2 and RNase 7. A moderate-to-strong linear relationship between the mRNA expression of particular AMPs appears to exist in AD, and to a lesser extent in PV as well.