Indications et modalités d’utilisation des antagonistes de l’interleukine (IL)-1 dans les dermatoses inflammatoires

Neutrophilic dermatoses with unusual and atypical presentations

Neutrophilic dermatoses (NDs) are a group of reactive, noninfectious autoinflammatory diseases characterized by (1) infiltration of the epidermis, dermis, and or/hypodermis by neutrophils; (2) their association with distinct diseases (eg, hematologic malignancy and chronic inflammatory diseases); (3) potential extracutaneous involvement; and (4) response to anti-inflammatory drugs, such as corticosteroids, dapsone, colchicine, and novel biologic therapies, such as the anti-interleukin-1 blockade. Although distinct NDs have been described, transitional forms with overlapping features are often identified. These justify a simplified classification of NDs with three major forms: superficial (epidermal or pustular) NDs, dermal (en plaques) NDs, and deep NDs. We review selected or novel variants of NDs, including subcorneal pustular dermatosis, the group of immunoglobulin A neutrophilic dermatoses, amicrobial pustular dermatosis of the folds, and neutrophilic urticarial dermatosis, as well as atypical forms of Sweet syndrome and pyoderma gangrenosum closely mimicking severe infectious diseases. Knowledge of these variants is essential for proper diagnosis, adequate management, and avoidance of a dangerous escalation of therapy, such as unnecessary immunosuppression or extensive surgery.

Anti-Inflammatory Effects of Potassium Iodide on SDS-Induced Murine Skin Inflammation

Potassium iodide (KI), initially derived from seaweed in the early 19th century, is used for treating sporotrichosis in dermatological practice. KI has also been used to treat several noninfectious inflammatory skin diseases. However, the mechanisms underlying the improvement in such skin diseases remain unknown, and KI is not used widely. Thus, although KI is an old drug, physicians may not prescribe it frequently because they lack knowledge about it. Although KI is very inexpensive and causes few side effects, it has been superseded by new powerful and expensive drugs, such as biological agents. We applied 3% KI topically to areas of inflammation induced by SDS in mice. The levels of IL-1 and TNF-α gene expression were reduced, whereas that of IL-10 gene expression was increased. Small interfering RNA that was designed to reduce IL-10 gene expression levels was injected into the same mice, and the anti-inflammatory effects of KI were not observed. Thus, the pharmacologic action of KI is based on its anti-inflammatory effects caused by the increase in IL-10 levels. This information would increase dermatologists' awareness of KI as an efficacious and cost-effective treatment.

Learning From Success and Failure: Biologics for Non-approved Skin Diseases

The impressive potential of biologics has been demonstrated in psoriasis, hidradenitis suppurativa, and urticaria. Numerous biologicals are entering the field for a restricted number of skin disorders. Off-label use of biologics in other recalcitrant skin diseases has increased. Mounting data point to the potential of already existing biologics acting on the IL-17/IL-23 pathway in skin disorders with epidermal hyperkeratosis (e.g., pityriasis rubra pilaris), acneiform inflammation (e.g., hidradenitis suppurativa), and loss of mucosal integrity (e.g., aphthosis). TNF-α blockers are also effective in the latter conditions but seem of particular value in granulomatous (e.g., granuloma annulare) and neutrophilic disorders (e.g., pyoderma gangrenosum). Failure of IL-17 blockade in skin diseases resulting from immune-mediated cell destruction (e.g., alopecia areata and vitiligo) illustrates its limited involvement in Th1-dependent skin immunology. Overall, disappointing results of TNF-α blockers in alopecia areata and vitiligo point to the same conclusion although promising results in toxic epidermal necrolysis suggest TNF-α exerts at least some in vivo Th1-related activities. Acting on both the Th1 and Th17 pathway, ustekinumab has a rather broad potential with interesting results in lupus and alopecia areata. The efficacy of omalizumab in bullous pemphigoid has revealed an IgE-mediated recruitment of eosinophils leading to bullae formation. Reconsidering reimbursement criteria for less common but severe diseases seems appropriate if substantial evidence is available (e.g., pityriasis rubra pilaris). For other disorders, investigator- and industry-initiated randomized clinical trials should be stimulated. They are likely to improve patient outcome and advance our understanding of challenging skin disorders.

Pyoderma Gangrenosum: An Update on Pathophysiology, Diagnosis and Treatment

Pyoderma gangrenosum (PG) is a rare inflammatory neutrophilic disorder with prototypical clinical presentations. Its pathophysiology is complex and not fully explained. Recent information regarding the genetic basis of PG and the role of auto-inflammation provides a better understanding of the disease and new therapeutic targets. PG equally affects patients of both sexes and of any age. Uncontrolled cutaneous neutrophilic inflammation is the cornerstone in a genetically predisposed individual. Multimodality management is often required to reduce inflammation, optimize wound healing, and treat underlying disease. A gold standard for the management of PG does not exist and high-level evidence is limited. Multiple factors must be taken into account when deciding on the optimum treatment for individual patients: location, number and size of lesion/ulceration(s), extracutaneous involvement, presence of associated disease, cost, and side effects of treatment, as well as patient comorbidities and preferences. Refractory and rapidly progressive cases require early initiation of systemic therapy. Newer targeted therapies represent a promising pathway for the management of PG, and the main focus of this review is the management and evidence supporting the role of new targeted therapies in PG.

A Review and Proposed Approach to the Neutrophilic Dermatoses of Childhood

Neutrophilic dermatoses (NDs) are inflammatory skin conditions that are not associated with infection. The classification and clinical approach to these conditions in children is poorly described. This review classifies these conditions into five nosological subtypes: Sweet's syndrome, pyoderma gangrenosum, aseptic pustules, neutrophilic urticarial dermatoses, and Marshall's syndrome. In addition, we review the various secondary diseases that need to be excluded in the clinical management of the NDs of childhood, with a focus on the autoinflammatory conditions that the reader may not be familiar with. We propose a practical clinical approach to these disorders.