Misdiagnosed dystrophic epidermolysis bullosa pruriginosa: A case report

Dupilumab: Advances in the off-label usage of IL4/IL13 antagonist in dermatoses

Type 2 immune response refers to a complicated series of immune responses characterized by Th2 polarization and Th2 cytokines secretion. The IgE secretion, airway hypersensitivity, and effector cell recruitment (eosinophils, mast cells, basophils) in skin lesion and peripheral blood stream could be upregulated during the activation of type 2 immune response. Th1/Th2 ratio, also referred as Th1/Th2 balance, represent the T lymphocytes immune pattern to a certain degree: Th1-dominated responses are often involved in intracellular infections (e.g., mycobacterium tuberculosis) and autoimmune diseases (e.g., Graves' disease) while Th2-dominated responses are involved in allergic conditions (e.g., atopic dermatitis, eczema), IgE mediated diseases (e.g., urticaria), and fibrotic dermatoses (e.g., keloids). Dupilumab, as one of the most widely applied Th2 cytokine inhibitors, could block the bioactivity of IL-14/IL-13 via competitively binding to the common IL-4Rα subunit shared by IL-4 and IL-13 receptors. In addition to the direct inhibition of type 2 response, dupilumab is also effective in autoimmune and some infectious skin diseases through indirect regulation of type 1 immune response. The pathological mechanism of Th2 responses and advanced clinical application of dupilumab in skin diseases will be summarized and discussed in the review.

Dystrophic epidermolysis bullosa pruriginosa: a new case series of a rare phenotype unveils skewed Th2 immunity

BACKGROUND

Dystrophic epidermolysis bullosa pruriginosa (DEB-Pr) is a rare subtype of hereditary epidermolysis bullosa, with a poorly understood pathogenesis and no satisfactory treatment.

OBJECTIVES

To assess the clinical and biological features, genetic basis and therapeutic management, to better characterize this rare genodermatosis.

METHODS

We have conducted a retrospective study, reviewing the clinical presentation, genetic diagnosis, immunohistopathological findings and biological characteristics and management of patients with dystrophic epidermolysis bullosa pruriginosa. This study was conducted in the Department of Dermatology at Saint-Louis Hospital and the Department of Genetics at Necker Hospital (Paris, France). All patients with a diagnosis of DEB-Pr seen between 2010 and 2020 were included.

RESULTS

Seven patients were included, the average age of 50.1 years [range 36-76]. Pruriginous-lichenified papules, plaques or nodules appeared at 27.6 years on average [range 7-66] on pretibial areas and forearms, associated with milia and toenails dystrophy. All patients received multiple treatments, but none could sustainably reduce pruritus. Immunohistopathological analysis of lesion skin revealed subepidermal blister with fibrosis, milia and mast cell infiltration. Serum TNFα, IL1β and IL6 levels were elevated in 2/6 patients. Total serum IgE levels were increased in 7/7 patients, with no history of atopy. Immunophenotyping of circulating T-cells revealed an increased Th2 subset in 4/4 patients, with reduced Th1 and Th17 subpopulations. Genetic analysis of COL7A1 identified 7 distinct causative mutations, six of which were new. Intra-familial clinical variability was documented in 5/7 patients and was associated with the co-inheritance of a recessive COL7A1 mutation or an FLG2 mutation in 2 families.

CONCLUSION

Our study confirms the stereotyped presentation of DEB-Pr with large intra-familial variability in disease expression. Mast cell infiltration, elevated IgE and increased Th2 subset without atopy strongly support a role of Th2-mediated immunity in DEB-Pr, and further argue for new targeted therapeutic options such as dupilumab.