Does Inflammatory Endotype Change in Patients With Chronic Rhinosinusitis?

Chronic rhinosinusitis (CRS) shows remarkable heterogeneity and it clinically classified into 2 phenotypes based on nasal endoscopic findings, chronic rhinosinusitis with nasal polyps (CRSwNP) or chronic rhinosinusitis without nasal polyps (CRSsNP).1 In Western studies, these clinical phenotypes reflect that CRSsNP showed a predominance of type 1 inflammation, whereas CRSwNP is well known to be characterized by type 2 inflammation and eosinophilia compared to CRSsNP or control sinus mucosa.2,3,4 However, to date, it is well-known that the inflammation in CRSwNP varies based on race and regional differences.5,6 Increasing evidences revealed that mixed inflammatory patterns are found in Asian patients with CRSwNP and the ratio of eosinophilic versus non-eosinophilic NP is usually detected similarly in these countries.7,8,9,10 Moreover, recent a multi-national study described that Th1/Th2/Th17 cytokine profile is diverse in terms of the immunologic endotypes among CRS subjects in Europe, China, Japan, and Australia.11 Furthermore, one cluster study with phenotype-free approach identified that CRS patients have 10 distinct inflammatory endotypes,12 and the other cluster study described that each cluster had distinct inflammatory endotype and its related prognosis.13 It implies that the characteristics of each endotype in CRS may have a serial continuum of immunologic profile. However, no studies have yet been reported on whether CRSsNP evolves into CRSwNP with a long duration of illness, or whether 2 diseases occur independently in patients. Because, in order to solve these problems, it is essential to design a long-term cohort study. Unfortunately, there are many hurdles to design a cohort study, regarding cost, time, and ethics