FLG and Alzheimer disease: Given that proteolytic activity could contribute to desquamation, reduction of antimicrobial peptide (AMP) expression, reduction of filaggrin expression and inflammation, PSMs may modulate immune response in AD lesions through various mechanisms including induction of pro-inflammatory cytokine and chemokine production from keratinocytes, and play a role in AD pathophysiology [4,9,12,36–38].