Endotypes of Asian chronic rhinosinusitis with nasal polyps: A narrative review

Chronic rhinosinusitis (CRS) is classified as CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). CRSwNP is a distinct phenotype with heterogeneous endotypes and complex pathophysiological mechanisms. Inflammation of the sinonasal mucosa that forms NPs causes symptoms such as nasal obstruction, rhinorrhea, and smell loss, and lowers patients’ quality of life. In recent years, researchers have attempted to elucidate the inflammatory endotypes of CRSwNP, and the inflammatory pattern of Asian CRSwNP was found to be different from that of Western CRSwNP. The main en-dotype of CRSwNP is type 2 inflammation, in which interleukin (IL)-4, IL-5, and IL-13 are key cytokines. In contrast, type 1 inflammation (interferon-γ) and type 3 inflammation (IL-17 or IL-22) play essential roles in Asian CRSwNP. Biological agents, which have recently been highlighted for the treatment of CRSwNP, are very effective in suppressing the type 2 inflammatory response and recovering smell loss. However, little information is available on the efficacy of these biologics in Asian patients with CRSwNP. Herein, we reviewed the endotypes of Asian CRSwNP and compared them to those of Western CRSwNP. We identified changes in the inflammatory patterns and summarized the therapeutic options for Asian CRSwNP.