Abstract
(1) Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the most studied rhinological disorders. Modifications of the respiratory nasal mucosa in COVID-19 patients are so far unknown. This paper presents a comparative morphological characterization of the respiratory nasal mucosa in CRSwNP versus COVID-19 and tissue interleukin (IL)-33 concentration. (2) Methods: We analyzed CRSwNP and COVID-19 samples through histopathology, scanning and transmission electron microscopy and performed proteomic determination of IL-33. (3) Results: Histopathologically, stromal edema (p < 0.0001) and basal membrane thickening (p = 0.0768) were found more frequently in CRSwNP than in COVID-19. Inflammatory infiltrate was mainly eosinophil-dominant in CRSwNP and lymphocyte-dominant in COVID-19 (p = 0.3666). A viral cytopathic effect was identified in COVID-19. Scanning electron microscopy detected biofilms only in CRSwNP, while most COVID-19 samples showed microbial aggregates (p = 0.0148) and immune cells (p = 0.1452). Transmission electron microscopy of CRSwNP samples identified biofilms, mucous cell hyperplasia (p = 0.0011), eosinophils, fibrocytes, mastocytes, and collagen fibers. Extracellular suggestive structures for SARS-CoV-2 and multiple Golgi apparatus in epithelial cells were detected in COVID-19 samples. The tissue IL-33 concentration in CRSwNP (210.0 pg/7 μg total protein) was higher than in COVID-19 (52.77 pg/7 μg total protein) (p < 0.0001), also suggesting a different inflammatory pattern. (4) Conclusions: The inflammatory pattern is different in each of these disorders. Results suggested the presence of nasal dysbiosis in both conditions, which could be a determining factor in CRSwNP and a secondary factor in COVID-19.
Highlights
The respiratory nasal mucosa represents an important component of immunity, both as a barrier against pathogenic respiratory agents, allergens, and physical insults, and maintains the in homeostasis between commensal microbiota and pathogenic agents inhaled through the nose [1,2]
The histopathological aspects observed in the Chronic rhinosinusitis with nasal polyps (CRSwNP) patients are presented in Figure 1, and those observed in the nasal mucosa of COVID-19 patients in Stromal edema was found in 92% (n = 23/25) of the CRSwNP samples (Figure 1B), and only in 25% (n = 3/12) of the COVID-19 samples
We identified in CRSwNP samples stromal edema with eosinophilic infiltrate, basement membrane thickening, and stromal fibrosis, but most of the COVID-19 samples did not show these changes
Summary
The respiratory nasal mucosa represents an important component of immunity, both as a barrier against pathogenic respiratory agents, allergens, and physical insults, and maintains the in homeostasis between commensal microbiota and pathogenic agents inhaled through the nose [1,2]. The respiratory nasal mucosa mediates local and systemic inflammatory responses to a wide range of pathogens. Epithelium-derived cytokines are important regulatory factors in inflammatory responses and in linking innate and adaptive immunity [3]. Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is a complex type 2 inflammatory disease of the respiratory nasal mucosa, which is frequently found and has a multidirectional impact on quality of life [4]. The study of the nasal mucosa in CRSwNP remains of interest because for some patients standard medical and surgical therapies do not provide sufficient control of inflammation (refractory disease). Biologic therapies target interleukin IL-4Rα, IL-5, IL-5Rα, IL-33, immunoglobulin E, and thymic stromal lymphopoietin [5]
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