Should the role of mast cells in chronic rhinosinusitis with nasal polyps be revaluated?

Abstract

Dear Editor, we read with great interest the study by Kowalik and colleagues concerning the crucial role that the SWI/SNF complex might play in the development and treatment of Chronic Rhinosinusitis (CRS) 1. In fact, chromatin remodelling in the SWI/SNF complex is involved in transcriptional control, DNA repair, hormonal signalling and inflammation. Moreover, the SWI/SNF complex regulates glucocorticoid receptors and the action of vitamin D by modulating the expression of the vitamin D receptor. In particular, the combination of activated VDR and the SWI/SNF complex promotes anti-inflammatory processes. As shown by the authors, the expression of SWI/SNF occurs in the sinonasal mucosa of both eosinophilic CRS (eCRS) and non-eosinophilic CRS (neCRS), with lower expression in the former. Blood eosinophil count (BEC) and histopathology eosinophil count correlate negatively with all the SWI/SNF subunits and positively with clinical findings, such as Lund-Mackay CT scores and Sino-Nasal Outcome Test (SNOT)-22. Although the inflammatory mechanisms and molecular processes underlying eCRS are still not fully understood, the authors hypothesise that the negative correlation of the SWI/SNF complex with eosinophils may explain the worse prognosis of eCRS, compared to neCRS, and resistance to glucocorticoid treatments. Thus, they emphasise the role of eosinophils in the pathophysiology of CRS, which represent a marker of severity of disease.