One of the authors (Andrea Chiricozzi) is from the Laboratory of Investigative Dermatology at The Rockefeller University.
Craig is a heretic. He does not believe psoriasis is an autoimmune disease, but an infection. He also believes other so-called autoimmune diseases are infections (or begin as one). For example, Crohn's disease is initiated by infection with mycobacterial pseudotuberculosis. Similarly, Craig believes psoriasis is caused by a gram positive bacterium on the skin that produces an exotoxin (e.g., a corynebacterium similar to corynebacterium diphtheriae), which causes cell proliferation. For psoriasis we see disorganization of the outer skin layer and increased cellular proliferation in the germ layers. We also see small pus pockets beneath the stratum corneum. Full of polymorphonuclear leukocytes (PMNs), these cells go after bacteria. Craig thinks autoimmunity is more hypersensitivity to something. Those with it have a hypersensitive immune system that is overreacting to something that basically is normal flora, cleared or ignored by everyone else. Hence, he agrees with the immune discussion in this paper, for example, is correct. But, it's not the cause, just the result.