Search

Autoinflammation has recently been suggested in the pathogenesis of neutrophilic dermatoses but systematic studies on their cytokine profile are lacking. Notably, amicrobial pustulosis of the folds (APF), classified among neutrophilic dermatoses, has been studied only in small case series. In our University Hospital, we conducted an observational study on 15 APF patients, analyzing their clinical and laboratory features with a follow-up of 9 months to 20 years. Skin cytokine pattern of 9 of them was compared to that of 6 normal controls. In all patients, primary lesions were pustules symmetrically involving the skin folds and anogenital region with a chronic-relapsing course and responding to corticosteroids. Dapsone, cyclosporine, and tumor necrosis factor blockers were effective in refractory cases. In skin samples, the expressions of interleukin (IL)-1β, pivotal cytokine in autoinflammation, and its receptors I and II were significantly higher in APF (P = 0.005, 0.018, and 0.034, respectively) than in controls. Chemokines responsible for neutrophil recruitment such as IL-8 (P = 0.003), CXCL 1/2/3 (C-X-C motif ligand 1/2/3) (P = 0.010), CXCL 16 (P = 0.045), and RANTES (regulated on activation, normal T cell expressed and secreted) (P = 0.034) were overexpressed. Molecules involved in tissue damage like matrix metalloproteinase-2 (MMP-2) (P = 0.010) and MMP-9 (P = 0.003) were increased. APF is a pustular neutrophilic dermatosis with a typical distribution in all patients. The disorder may coexist with an underlying autoimmune/dysimmune disease but is often associated only with a few autoantibodies without a clear autoimmunity. The overexpression of cytokines/chemokines and molecules amplifying the inflammatory network supports the view that APF has an important autoinflammatory component.

The therapy of inflammatory bowel disease, particularly with tumor necrosis factor (TNF) blockers, may be associated with a number of cutaneous adverse effects, including psoriasis-like, eczema-like, and lichenoid eruptions. Other rare skin complications are neutrophilic dermatoses such as amicrobial pustulosis of the folds (APF), which is a chronic relapsing pustular disorder classified in this spectrum. The authors analyzed clinical, histopathologic, and cytokine expression profiles of 3 inflammatory bowel disease patients with APF triggered by adalimumab (patient 1) and infliximab (patients 2 and 3). All 3 patients presented with sterile pustules involving the cutaneous folds, genital regions, and scalp 6 months after starting adalimumab (patient 1) and 9 months after starting infliximab (patients 2 and 3). Histology was characterized by epidermal spongiform pustules with a dermal neutrophilic and lymphocytic infiltrate. Tumor necrosis factor blocker withdrawal associated with topical and systemic corticosteroids induced complete remission of APF in all 3 patients. The expressions of interleukin (IL)-1 beta and its receptors as well as TNF alpha and its receptors were significantly higher in APF than in controls. Also IL-17, leukocyte selectin, and chemokines, such as IL-8, [C-X-C motif] chemokine ligand 1/2/3 (C = cysteine, X = any amino acid), [C-X-C motif] chemokine ligand 16 (C = cysteine, X = any amino acid), and RANTES (regulated on activation, normal T cell expressed and secreted) were significantly overexpressed. Finally, the authors found significant overexpression of both metalloproteinases 2/9 and their inhibitors 1/2. The observation of 3 patients with APF following anti-TNF therapy expands not only the clinical context of APF but also the spectrum of anti-TNF side effects. Overexpression of cytokines/chemokines and molecules amplifying the inflammatory network supports the view that APF is autoinflammatory in origin.