Subtyping of polyposis nasi: phenotypes, endotypes and comorbidities

Abstract

Background: Chronic rhinosinusitis (CRS) is a heterogeneous, multifactorial inflammatory disease of the nasal and paranasal mucosa. It has not been possible to date to develop an internationally standardized, uniform classification for this disorder. A phenotype classification according to CRS with (CRSwNP) and without polyposis (CRSsNP) is usually made. However, a large number of studies have shown that there are also different endotypes of CRS within these phenotypes, with different pathophysiologies of chronic inflammation of the nasal mucosa. This review describes the central immunological processes in nasal polyps, as well as the impact of related diseases on the inflammatory profile of nasal polyps.

Materials and methods: The current knowledge on the immunological and molecular processes of CRS, in particular CRSwNP and its classification into specific endotypes, was put together by means of a structured literature search in Medline, PubMed, the national and international guideline registers, and the Cochrane Library.

Results: Based on the current literature, the different immunological processes in CRS and nasal polyps were elaborated and a graphical representation in the form of an immunological network developed. In addition, different inflammatory profiles can be found in CRSwNP depending on related diseases, such as bronchial asthma, cystic fibrosis (CF), or NASID-Exacerbated Respiratory Disease (N‑ERD).

Conclusion: The identification of different endotypes of CRSwNP may help to improve diagnostics and develop novel individual treatment approaches in CRSwNP.

Keywords: Asthma; CRSwNP; Chronic rhinosinusitis; Nasal polyps; N‑ERD.

Fig. 1

The immunological processes in nasal polyps. CRSwNP can be divided into three different endotypes: the T cell‑/Th2 cytokine-based endotype, the B cell‑/IgE-based endotype, and the eosinophil-based endotype. This gives rise to different treatment approaches in CRSwNP. CRSwNP chronic rhinosinusitis with nasal polyps; CD cluster of differentiation; IL interleukin; TSLP thymic stromal lymphopoietin; Th T-helper; ILC innate lymphoid cell; CXCL CXC motif chemokine ligand; CXCR CXC motif chemokine receptor; Ig immunoglobulin; IFN interferon; CCR CC motif chemokine receptor; CCL CC motif chemokine ligand

Fig. 2

The affect of various comorbidities of CRSwNP on the inflammatory profile in nasal polyps: different comorbidities of CRSwNP affect the development of endotypes of nasal polyps. As a result, the classic inflammatory profile in nasal polyps shifts and gains additional specific markers. When associated with cystic fibrosis, the inflammatory profile of nasal polyps changes extensively. CRSwNP chronic rhinosinusitis with nasal polyps; CF cystic fibrosis; AFRS allergic fungal rhinosinusitis; EFRS eosinophilic fungal rhinosinusitis; NAScA non-asthmatic sinusitis with allergy; AScA asthmatic sinusitis with allergy; ASsA asthmatic sinusitis without allergy; N‑ERD NASID-Exacerbated Respiratory Disease; IL interleukin; Th T-helper; MPO myeloperoxidase; Ig immunoglobulin; TNF tumor necrosis factor; CCL CC motif chemokine ligand