Imiquimod (IMQ) induced psoriasis-like inflammation was exposed to recombinant HMGB1 and to phosphate-buffered saline (PBS) i.d. Lesional skin from IMQ-treated mice presented high cytoplasmic levels of HMGB1 and the administration of HMGB1 into the lesional skin further worsened the psoriasis-like disease. Here, HMGB1 is linked to psoriasis.