TNF and pemphigus: Similarly, and independently of long-term systemic corticosteroid use, the association between pemphigus (and generally autoimmune blistering skin diseases) and OP is based on the shared chronic pro-inflammatory substrate of cytokines such as IL-17, TNF, IL-1, and IL-6, which, together with auto-reactive B and T cells, drive osteoclast-mediated bone resorption.