Up to 300 subjects with chronic skin conditions (including but not limited to atopic dermatitis (AD), contact dermatitis, hidradenitis suppurativa (HS), and psoriasis) and 100 healthy subjects meeting the inclusion criteria will be enrolled. Medical records will be reviewed pertaining to the subject's diagnosed chronic skin condition and specific therapeutic interventions.~For atopic dermatitis subjects, AD severity will be assessed using Eczema Area and Severity Index (EASI). Study sites will be chosen by the investigator. One lesional and one nonlesional site on the trunk, upper, or lower extremities will be selected. Digital photos of the study skin site(s) will be taken. Skin barrier function indices (transepidermal water loss, pH, sebum and hydration levels) of an active lesion and adjacent nonlesional skin will be measured using noninvasive skin barrier measurement devices.~For subjects with other chronic skin conditions such as contact dermatitis, HS or psoriasis, photos of the selected study sites will be taken. No skin barrier measurements will be performed.~For all subjects, two 3mm punch biopsies will be performed over the selected skin sites. One biopsy will be performed over an active lesion and another on adjacent nonlesional skin. Tissue will be sent out for immunohistochemical staining to study the expression anti-oxidant biomarkers. Five mL of peripheral venous blood will be collected for immunoassay to measure the level inflammatory cytokines.~For healthy subjects, digital photo of the study skin site(s) over either the trunk, upper, or lower extremities will be taken. Skin barrier function indices (transepidermal water loss, pH, sebum and hydration levels) of skin be measured using noninvasive skin barrier measurement devices. One 3mm punch biopsy will be performed over the same skin site that skin barrier measurements were performed. Tissue will be sent out for immunohistochemical staining to study the expression anti-oxidant biomarkers. Five mL of peripheral venous blood will be collected for immunoassay to measure the level inflammatory cytokines.
Investigators will sample the skin and blood of patients with chronic skin conditions (including but not limited to atopic dermatitis (AD), contact dermatitis, hidradenitis suppurativa (HS), and psoriasis) to study the expression of anti-oxidative enzymes, skin barrier proteins and inflammatory molecules. In patients with atopic dermatitis, investigators will also measure skin barrier function using noninvasive devices. These results will be correlated with the disease severity in atopic dermatitis patients.