Recently, we reported downregulation of MMP-8 and overexpression of S100A8 in the GCF of patients with atopic dermatitis and psoriasis, respectively, independent of the patient’s periodontal status, indicating that MMP-8 and S100A8 proteins could be used as diagnostic biomarkers of these diseases, respectively [29,30]. Here, S100A8 is linked to psoriasis.