10.14639/0392-100X-N1768
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.
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1827-675X
1768
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Michele Cassano
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ACTA Otorhinolaryngologica Italica
nasal cytology
Should the role of mast cells in chronic rhinosinusitis with nasal polyps be revaluated?
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2023-10-18
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2023-10-18
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Michele Cassano
2021
10.14639/0392-100X-N1768
576
Department of Otolaryngology, University Hospital of Foggia, Foggia, Italy
1827-675X
nasal cytology
en
577
Should the role of mast cells in chronic rhinosinusitis with nasal polyps be revaluated?
https://www.actaitalica.it/article/download/1768/729
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ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:576-577; doi: 10.14639/0392-100X-N1768




Letter to the Editor


Should the role of mast cells in chronic rhinosinusitis
with nasal polyps be revaluated?
Dovremmo rivalutare il ruolo dei mastociti nella rinosinusite cronica associata
a poliposi nasale?
Matteo Gelardi, Rossana Giancaspro, Michele Cassano
Department of Otolaryngology, University Hospital of Foggia, Foggia, Italy


KEY WORDS: mast cells, chronic rhinosinusitis with nasal polyps, nasal cytology
PAROLE CHIAVE: mastociti, rinosinusite cronica associata a poliposi nasale, citologia nasale


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 treat-
ment 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 glu-
cocorticoid 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
                                                                                               Received: July 21, 2021
authors, the expression of SWI/SNF occurs in the sinonasal mucosa of both eo-                  Accepted: September 21, 2021
sinophilic CRS (eCRS) and non-eosinophilic CRS (neCRS), with lower expres-
sion in the former. Blood eosinophil count (BEC) and histopathology eosinophil                 Correspondence
                                                                                               Rossana Giancaspro
count correlate negatively with all the SWI/SNF subunits and positively with
                                                                                               Department of Otolaryngology, University of Fog-
clinical findings, such as Lund-Mackay CT scores and Sino-Nasal Outcome                        gia, via Luigi Pinto 1, 71122. Foggia, Italy
Test (SNOT)-22. Although the inflammatory mechanisms and molecular pro-                        E-mail: rogianca@live.it
cesses underlying eCRS are still not fully understood, the authors hypothesise
                                                                                               Funding
that the negative correlation of the SWI/SNF complex with eosinophils may                      None
explain the worse prognosis of eCRS, compared to neCRS, and resistance to
glucocorticoid treatments. Thus, they emphasise the role of eosinophils in the                 Conflict of interest
pathophysiology of CRS, which represent a marker of severity of disease.                       The Authors declare no conflict of interest.
Actually, the crucial role that eosinophils play in the pathogenesis of CRS
has long been recognised and several biomarkers of eosinophilic inflammation                     How to cite this article: Gelardi M, Giancaspro
                                                                                                 R, Cassano M. Should the role of mast cells in
have been identified, including the Charcot-Leyden crystal protein (CLCP) 2.                     chronic rhinosinusitis with nasal polyps be reval-
However, in the era of precision medicine, accurately identifying the different                  uated? Acta Otorhinolaryngol Ital 2021;41:576-
phenotypes and endotypes of chronic respiratory disorders is crucial in order to                 577. https://doi.org/10.14639/0392-100X-N1768
guarantee therapeutic approaches tailored to each patient 3. In this context, we
                                                                                               © Società Italiana di Otorinolaringoiatria
would emphasise the role of mast cells (MCs), which are too often underesti-                   e Chirurgia Cervico-Facciale
mated. In fact, even if over the years knowledge of the CRS has increased sig-
nificantly, most studies have focused attention on eosinophilic or neutrophilic                               OPEN ACCESS
inflammation 4. Only recently, attention is shifting towards another cytotype,                 This is an open access article distributed in accordance with
                                                                                               the CC-BY-NC-ND (Creative Commons Attribution-Non-
equally involved in the mechanisms underlying CRS, represented by the MC.                      Commercial-NoDerivatives 4.0 International) license. The
In particular, MCs, which are probably activated by local IgE, cytokines and                   article can be used by giving appropriate credit and mentio-
                                                                                               ning the license, but only for non-commercial purposes and
chemokines, promote eosinophilic infiltration and tissue remodeling through                    only in the original version. For further information: https://
the degradation of the extracellular matrix 5.                                                 creativecommons.org/licenses/by-nc-nd/4.0/deed.en




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                                                                                        The role of mast cells in chronic rhinosinusitis with nasal polyps




                                                                           when eosinophils are intensely activated and undergo ETo-
                                                                           sis, causing a crystallopathy 2. Although it has classically
                                                                           been considered the expression of exclusively eosinophilic
                                                                           inflammation, our aforementioned study demonstrates that
                                                                           CLCP-10 also co-localises with MCs. These observations
                                                                           suggest the involvement of MCs in the pathogenesis of
                                                                           CRS and, in particular, in the spectrum of pathologies un-
                                                                           derlying Type 2 inflammation, such as CRSwNP.
                                                                           In light of this evidence, although Kowalik and colleagues
                                                                           have clearly shown the correlation between the SWI/SNF
                                                                           complex and eosinophilic inflammation in the pathogenesis
                                                                           of CRS, we believe that the attention of research should no
                                                                           longer focus exclusively on eosinophils, but should turn to
                                                                           the study of other cytotypes, such as MCs. This new cyto-
                                                                           logical point of view could guarantee a specific diagnosis
Figure 1. Pathological findings at nasal cytology in CRSwNP.               and therefore effective therapy, tailored to the patient’s phe-
E: eosinophil; MC: Mast cell. May-Grunwald-Giemsa (MGG) staining. Magni-   notype and endotype.
fication 1000x.

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neutrophils are respectively found in 3.5% and 2.8% of                     6
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by a high-grade CCG, are significantly associated with a                   9
                                                                                Gelardi M, Porro G, Quaranta N, et al. Clinical-cytological-grading
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characteristically forms bi-pyramidal hexagonal crystals                        org/10.1177/19458924211049867




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