Figure 4.

Pro- and active MMP9 in hidradenitis skin specimens. (A) Pro-MMP9 is widespread in the skin of patients with hidradenitis, while active MMP9 is more focal and associated with ruptured epidermis (top) and ruptured hair follicles (bottom). (B) Active MMP9 and myeloid cells (MPO+ neutrophils and IBA1+ macrophages) are found proximal to the rupture in the skin, while lymphocytes (CD20+ B cells and CD3+ T cells) are secondary. F, fistula; IBA1, anti-ionized calcium-binding adaptor protein-1; MMP, matrix metalloproteinase; MPO, myeloperoxidase.