TBCE and infection: In the onset of psoriasis, KCs are attacked and stressed upon various stimuli, such as trauma, drugs, and infections, followed by the release of damaged DNA/RNA, LL-37, AMPs, DAMPs and other cytokines/chemokines from these activated KCs, which could initiate innate immune responses and attract more neutrophils infiltration into the epidermis to form Munro or Kogoj abscesses, this sterile pustules constitutes typical pathological manifestations of GPP.