The majority of cell–matrix and cell–cell adhesion genes and genes encoding for ECM organizational proteins (see also Supplementary Figure S3B) was downregulated in KC from the skin of AD patients exposed to Der p 2 pep (AD_pep) compared to AD_rec with the exception of the upregulation of cathepsin L (CTSL) and cathepsin D (CTSD) expression (Figure 4C, blue rectangle). Here, CTSD is linked to Alzheimer disease.