Study of local inflammatory response in different clinical forms of chronic polypous rhinosinusitis

Abstract

Chronic rhinosinusitis (CRS) affects 5-12% of the world’s adult population. Chronic rhinosinusitis with nasal polyps (CRSwNP) accounts for 25-30% of all cases of CRS. CRSwNP-associated inflammatory process in nasal mucosa and paranasal sinuses depends on the characteristics of local immunity, including expression of a number of cytokines. The aim of this work was to investigate the parameters of local immunity in various clinical forms of CRSwNP. In this work, the concentrations of pro-inflammatory cytokines, i.e., interleukin-1β (IL-1β) and IL-8, antimicrobial function of neutrophils from the nasal cavity was evaluated, along with histological and immunohistochemical studies of polyposis tissue. The study included 4 groups of patients: a control group of practically healthy individuals, patients with CRSwNP, clinical cases with chronic purulent rhinosinusitis and nasal polyps (CPRSwNP), and patients with CRSwNP complicated by bronchial asthma (CRSwNP + BA), including the cases with asthmatic triad (CRSwNP + intolerance to NSAIDs + BA). The patients were classified on the basis of their clinical characteristics and severity of the course of the disease. Interleukin-1β (IL-1β) and IL-8 concentrations in nasal secretions were determined by enzyme-linked immunosorbent assay (ELISA). To assess functional activity of neutrophils, a lysosomal cationic test was used on the smears from mucous surface of inferior turbinate. Histological examination of the polypous tissue biopsies was performed in slices stained with Carazzi’s hematoxylin and eosin. IL-1β and IL-8 location in the polypous tissue were detected by indirect immunohistochemistry. In all groups of the patients, IL-1β and IL-8 concentrations exceeded those in the control group. The levels of IL-1β in the groups with CPRSwNP, CRSwNP + BA were significantly increased as compared with the CRSwNP group. IL-8 concentrations in the CRSwNP and CPRSwNP groups were significantly higher than in the CRSwNP + BA group. When analyzing antimicrobial function of neutrophils, the decreased average values of cytochemical coefficient were shown in CPRSwNP and CRSwNP + BA groups, compared with the control group and CRSwNP. In all clinical forms of CPMS, complex histopathological changes were observed, including leukocyte infiltration, fibrosis, edema, and collagen depositions. In addition, the integrity of epithelial layer was found to be damaged in polyposis, epithelial metaplasia is detected as well as increased mucus production. These disorders lead to a decrease in muco-ciliary clearance in nasal cavity. The most significant pathomorphological changes occur in CRSwNP + BA, especially in cases of asthmatic triad. According to immunohistochemical data, in various forms of CRSwNP, IL-1β- and IL-8-positive leukocytes, predominantly macrophages, are detected in the polypous tissue both subepithelially and in the connective tissue stroma of the polyps. Changed concentrations of pro-inflammatory cytokines in nasal secretion of the patients, altered antimicrobial activity of mucosal neutrophils, and characteristic pathomorphological disorders in polypous tissue of patients with CRSwNP are associated with severity of inflammatory process and clinical course of the disease. The results obtained are essential to understanding the mechanisms of pathogenesis in various subgroups of CRSwNP, assessing severity of the disease and efficiency of the treatment applied.