Chronic pulmonary aspergillosis may cause eosinophilic granulomatosis with polyangiitis via allergic bronchopulmonary aspergillosis

Overlap of Chronic Pulmonary Aspergillosis on Allergic Bronchopulmonary Aspergillosis

An 80-year-old woman who developed allergic bronchopulmonary aspergillosis (ABPA) was admitted to our institution in 2023 for an enlarged pulmonary mass lesion. She had developed ABPA in 2017, and corticosteroid therapy had improved the mucoid impaction of the bronchi. Because part of the lesion remained, increased doses of corticosteroid, antifungals, and biologics were administered, but the pulmonary lesion enlarged in 2022. Bronchoscopy showed necrotic tissue in the bronchial lumen, and bronchial washing fluid showed neutrophilic inflammation and fungal hyphae. We subsequently diagnosed her as having chronic pulmonary aspergillosis overlapping ABPA, and voriconazole was started that resulted in shrinkage of the nodules.

Coexistence of Eosinophilic Granulomatosis With Polyangiitis and Allergic Bronchopulmonary Aspergillosis: A Fascinating Relationship

Elevated eosinophil counts are associated with various diseases, including eosinophilic granulomatosis with polyangiitis (EGPA) and allergic bronchopulmonary aspergillosis (ABPA). EGPA is a rare small-vessel vasculitis characterized by asthma, eosinophilia, fleeting pulmonary infiltrates, and systemic manifestations. ABPA, initiated by immune reactions against Aspergillus fumigatus in the airways, presents with poorly controlled asthma, wheezing, hemoptysis, productive cough, and systemic symptoms, which result in characteristic central bronchiectasis. Fleeting pulmonary opacities are common radiologic findings. We present a case of ABPA in a patient with a prior EGPA diagnosis under treatment with mepolizumab 300 mg monthly and review eight similar cases from the literature. In these cases, EGPA and ABPA diagnoses preceded each other or were concurrent. Treatment of the latter improved control of both diseases. IL-5 is pivotal in EGPA pathogenesis, and mepolizumab, targeting IL-5, has been effective in EGPA treatment. Our patient received mepolizumab for EGPA and continued it post-ABPA diagnosis, showing favorable outcomes. This suggests mepolizumab as a therapeutic link between EGPA and ABPA. Mepolizumab therapy holds promise for managing both EGPA and ABPA. Double-blind placebo-controlled studies are warranted to establish its efficacy and safety for ABPA, emphasizing the need for further research in this area.

Eosinophilic granulomatosis with polyangiitis - Advances in pathogenesis, diagnosis, and treatment

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare disease characterized by eosinophil-rich granulomatous inflammation and necrotizing vasculitis, pre-dominantly affecting small-to-medium-sized vessels. It is categorized as a primary antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) but also shares features of hypereosinophilic syndrome (HES); therefore, both vessel inflammation and eosinophilic infiltration are suggested to cause organ damage. This dual nature of the disease causes variable clinical presentation. As a result, careful differentiation from mimicking conditions is needed, especially from HES, given the overlapping clinical, radiologic, and histologic features, and biomarker profile. EGPA also remains a diagnostic challenge, in part because of asthma, which may pre-dominate for years, and often requires chronic corticosteroids (CS), which can mask other disease features. The pathogenesis is still not fully understood, however, the interaction between eosinophils and lymphocytes B and T seems to play an important role. Furthermore, the role of ANCA is not clear, and only up to 40% of patients are ANCA-positive. Moreover, two ANCA-dependent clinically and genetically distinct subgroups have been identified. However, a gold standard test for establishing a diagnosis is not available. In practice, the disease is mainly diagnosed based on the clinical symptoms and results of non-invasive tests. The unmet needs include uniform diagnostic criteria and biomarkers to help distinguish EGPA from HESs. Despite its rarity, notable progress has been made in understanding the disease and in its management. A better understanding of the pathophysiology has provided new insights into the pathogenesis and therapeutic targets, which are reflected in novel biological agents. However, there remains an ongoing reliance on corticosteroid therapy. Therefore, there is a significant need for more effective and better-tolerated steroid-sparing treatment schemes.

Airway mycosis in allergic airway disease

The allergic airway diseases, including chronic rhinosinusitis (CRS), asthma, allergic bronchopulmonary mycosis (ABPM) and many others, comprise a heterogeneous collection of inflammatory disorders affecting the upper and lower airways and lung parenchyma that represent the most common chronic diseases of humanity. In addition to their shared tissue tropism, the allergic airway diseases are characterized by a distinct pattern of inflammation involving the accumulation of eosinophils, type 2 macrophages, innate lymphoid cells type 2 (ILC2), IgE-secreting B cells, and T helper type 2 (Th2) cells in airway tissues, and the prominent production of type 2 cytokines including interleukin (IL-) 33, IL-4, IL-5, IL-13, and many others. These factors and related inflammatory molecules induce characteristic remodeling and other changes of the airways that include goblet cell metaplasia, enhanced mucus secretion, smooth muscle hypertrophy, tissue swelling and polyp formation that account for the major clinical manifestations of nasal obstruction, headache, hyposmia, cough, shortness of breath, chest pain, wheezing, and, in the most severe cases of lower airway disease, death due to respiratory failure or disseminated, systemic disease. The syndromic nature of the allergic airway diseases that now include many physiological variants or endotypes suggests that distinct endogenous or environmental factors underlie their expression. However, findings from different perspectives now collectively link these disorders to a single infectious source, the fungi, and a molecular pathogenesis that involves the local production of airway proteinases by these organisms. In this review, we discuss the evidence linking fungi and their proteinases to the surprisingly wide variety of chronic airway and systemic disorders and the immune pathogenesis of these conditions as they relate to environmental fungi. We further discuss the important implications these new findings have for the diagnosis and future therapy of these common conditions.