1. Elevated epidermal serine protease activity in AD patients.2. Detection of KLK5, -7, -8, and -14 in the perspiration of AD patients3. Murine models overexpressing PAR2 develop AD-like symptoms.4. PAR2 overexpression in keratinocytes and immune cells induces IL-6, ICAM-1, and TSLP.5. PAR2 signaling activates histamine-independent itching pathways.6. PAR2 antagonist PZ235 downgrades inflammatory factors and alleviates AD symptoms. This evidence concerns the gene KLK5 and Alzheimer disease.