Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of antineutrophil cytoplasm antibody (ANCA)-associated vasculitis, distinguished by a complex interplay between type 2 (T2) eosinophilic and non-T2 inflammatory pathways. Systemic glucocorticosteroids remain the mainstay of both induction and maintenance therapy, achieving remission in patients without poor prognostic factors, yet long-term dependence and toxicity remain pervasive challenges. Conventional immunosuppressive agents such as cyclophosphamide (CYC), azathioprine, and methotrexate have been widely used, and rituximab has shown similar remission rates to CYC for induction therapy. However, robust randomized controlled trial evidence supporting their efficacy in EGPA is limited. Biologic therapies targeting eosinophils through IL-5 or IL-5R blockade, notably mepolizumab and benralizumab, have markedly reduced relapse rates, steroid exposure, and improved remission rates in relapsing or refractory disease, with excellent tolerability. Their role in induction is yet to be assessed, alongside novel approaches targeting thymic stromal lymphopoietin and other non-T2 immune pathways. Future priorities include clarifying the contribution of vasculitic versus nonvasculitic mechanisms, the significance of ANCA status, and the immunobiology of relapse. Despite therapeutic inertia in the absence of definitive trials, the collective drive of clinicians and researchers promises to transform and advance management of EGPA in the years ahead.
Background: Netherton syndrome (NS) is a rare genetic disorder resulting from biallelic mutations in the serine protease inhibitor Kazal-type 5 (SPINK5) gene, also known as lymphoepithelial-Kazal-type-related-inhibitor (LEKTI). Although currently classified as a hyper-IgE syndrome, several manifestations contradict this categorization. Data on genotype-phenotype correlations remain limited, and pediatric outcomes of biologic therapies are inconsistent.
Objective: This study investigated the clinical, immunological features, genotype-phenotype correlations, and pediatric outcomes of various systemic and biologic therapies in detail.
Methods: Clinical, immunological, and treatment data from eight patients were collected in a retrospective-prospective design. Variants were categorized based on the affected bio-reactive fragments (FR1-FR5) of the LEKTI protein.
Results: Of six SPINK5 variants, including two novel ones, four FR1-related were linked to severe phenotypes, while two FR5-related were associated with milder disease. The onset of skin features was significantly earlier in patients with allergic manifestations than in those without. Although no intrinsic developmental defects in T or B cells were identified, skin barrier disruption was associated with immune activation and skewing toward Th2/Th17 responses. Notably, increased PD-1 expression, expansion of CD4+IL-17+ T cells, and reduced frequencies of IFN-γ-producing CD4+ T cells correlated with clinical disease severity. In scaly erythroderma, secukinumab was most effective for scaling, while dupilumab was more effective for pruritus. The Efficacy of dupilumab and infliximab was temporary, with rebound skin lesions observed during follow-up. Immunoglobulin therapy supported growth but revealed variable skin benefits.
Conclusion: The described findings support the concept of indirect immune dysregulation in NS due to a defective skin barrier, emphasizing the need for therapies that extend beyond single cytokine or receptor blockade.

