There are several clues that an IL-23/Type17 T-cell pathway may be active in HS which include detection of Th17 T-cells in skin infiltrates, increased production of IL-17A, and increased production of LL-37/cathlecidin, S100A7, S100A8, S100A9, LCN2, IL-8, beta-defensins and IL-36; which are all molecules induced by IL-17 in keratinocytes, as also the presence of psoriasis-like epidermal hyperplasia in some reports. The gene discussed is S100A9; the disease is psoriasis.