PPL and Alzheimer disease: Also, various AD endotypes were described based on differences in patient age and race, AD severity and course (chronic vs acute), immune polarization of T cell subsets, interleukin and chemokine expression, IgE levels, skin barrier defects (e.g., altered lipid composition, expression status of filaggrin, keratin 16, locrin, periplakin) and microbiome alterations [7].