[Injury and epithelial wound healing: a pathophysiologic hypothesis for nasal and sinus polyposis]

[Management strategies for chronic rhinosinusitis with nasal polyps in adults]

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the categories of chronic rhinosinusitis and is defined by the presence of bilateral polyps. It is frequently associated with other conditions (asthma, atopy, aspirin intolerance), which worsen its prognosis.

STATE OF ART

The pathophysiology of CRSwNP is still poorly understood. The genesis of polyps is thought to be based on an initial epithelial lesion caused by environmental factors in the context of self-maintained chronic local inflammation. Multiple local and general factors can be involved in this inflammation, which is mainly of Th2 type in Europe. Abnormalities of the epithelial barrier and the immune system (eosinophilia, cytokines, T and B lymphocytes), genetic factors and pathogens, including Staphylococcus aureus, have been incriminated. The treatment of CRSwNP is mainly based on the application of local corticosteroids. Surgery remains an important part of patient management where CRSwNP becomes resistant to topical therapy. The management of CRSwNP may be at a turning point thanks to the arrival of biological therapies (anti-IgE, anti-IL-5, anti-IL-4/IL-13) the initial results of which are promising.

PERSPECTIVES/CONCLUSIONS

With the new concept of endotypes, current avenues of research are moving towards a better understanding of the inflammatory mechanisms of CRSwNP. Immunotherapy appears to be a promising future for the treatment of CRSwNP.

Biotherapy and treatment of adult primary chronic rhinosinusitis with nasal polyps: Cellular and molecular bases

The present article reviews the molecular and cellular mechanisms involved in the pathophysiology of chronic rhinosinusitis with nasal polyps (CRSwCRSwNP) and underlying the action mechanisms of biotherapies. Biotherapy uses substances naturally produced by the organism or their specific antagonists targeting a proinflammatory mechanism. CRSwCRSwNP is a form of chronic rhinosinusitis (CRS), which is classically subdivided in to 2 types according to the presence of polyps. In recent years, the concept of endotypes emerged, with a more exhaustive definition of the types of CRS according to inflammatory mechanism, with a view to developing personalized treatments. CRSwNP pathophysiology is poorly understood. Polyps arise from a primary epithelial lesion in a context of chronic local inflammation, mainly type 2 in Europe, implicating eosinophils, IgE, Th2 cytokines (IL-4/IL-13, IL-5) and T and B cells. Biotherapy seems promising in CRSwNP. The present review details the various pathophysiological pathways underlying the action mechanisms of biotherapies, and the various published studies, assessing efficacy and mode of action in the treatment of CRSwNP.

Pathogenesis of chronic rhinosinusitis with nasal polyps: role of IL-6 in airway epithelial cell dysfunction

Background

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by an alteration in airway epithelial cell functions including barrier function, wound repair mechanisms, mucociliary clearance. The mechanisms leading to epithelial cell dysfunction in nasal polyps (NPs) remain poorly understood. Our hypothesis was that among the inflammatory cytokines involved in NPs, IL-6 could alter epithelial repair mechanisms and mucociliary clearance. The aim of this study was to evaluate the in vitro effects of IL-6 on epithelial repair mechanisms in a wound repair model and on ciliary beating in primary cultures of Human Nasal Epithelial Cells (HNEC).

Methods

Primary cultures of HNEC taken from 38 patients during surgical procedures for CRSwNP were used in an in vitro model of wound healing. Effects of increasing concentrations of IL-6 (1 ng/mL, 10 ng/mL, and 100 ng/mL) and other ILs (IL-5, IL-9, IL-10) on wound closure kinetics were compared to cultures without IL-modulation. After wound closure, the differentiation process was characterized under basal conditions and after IL supplementation using cytokeratin-14, MUC5AC, and β_IV tubulin as immunomarkers of basal, mucus, and ciliated cells, respectively. The ciliated edges of primary cultures were analyzed on IL-6 modulation by digital high-speed video-microscopy to measure: ciliary beating frequency (CBF), ciliary length, relative ciliary density, metachronal wavelength and the ciliary beating efficiency index.

Results

Our results showed that: (i) IL-6 accelerated airway wound repair in vitro, with a dose–response effect whereas no effect was observed after other ILs-stimulation. After 24 h, 79% of wounded wells with IL6-100 were fully repaired, vs 46% in the IL6-10 group, 28% in the IL6-1 group and 15% in the control group; (ii) specific migration analyses of closed wound at late repair stage (Day 12) showed IL-6 had the highest migration compared with other ILs (iii) The study of the IL-6 effect on ciliary function showed that CBF and metachronal wave increased but without significant modifications of ciliary density, length of cilia and efficiency index.

Conclusion

The up-regulated epithelial cell proliferation observed in polyps could be induced by IL-6 in the case of prior epithelial damage. IL-6 could be a major cytokine in NP physiopathology.

TGF-β1 Induces Epithelial-Mesenchymal Transition of Chronic Sinusitis with Nasal Polyps through MicroRNA-21

OBJECTIVES

To characterize the epithelial-mesenchymal transition (EMT) in chronic rhinosinusitis with nasal polyps (CRSwNP) and to investigate the mechanism by which microRNA-21 (miR-21) regulates EMT in CRSwNP.

METHOD

(1) Tissue experiments: Mucosa tissues were collected from 13 patients with CRSwNP and 12 patients with CRS without nasal polyps (CRSsNP), as well as 11 patients without CRS (controls). Protein localization and quantification were achieved by immunofluorescence staining and Western blotting, involving the epithelial marker protein E-cadherin and the mesenchymal marker proteins α-smooth muscle actin (α-SMA), fibronectin, and vimentin. Quantitative RT-PCR was used to detect the relative expression levels of miR-21 and TGF-β1 mRNAs. (2) Cellular experiments: Primary human nasal epithelial cells (PHNECs) treated with TGF-β1, or TGF-β1 with miR-21 inhibitor, or miR-21 mimics alone were observed for morphology changes under a phase-contrast microscope. The expression levels of epithelial/mesenchymal marker proteins were determined as aforementioned. PTEN and phosphorylated Akt were detected by Western blotting.

RESULTS

(1) Tissue experiments: Compared with the CRSsNP and control groups, the expression of E-cadherin was downregulated in the CRSwNP group, whereas the expression of TGF-β1, α-SMA, fibronectin, and vimentin was upregulated. The expression levels of miR-21 and TGF-β1 mRNAs in CRSwNP were significantly higher than those in CRSsNP and controls. (2) Cellular experiments: TGF-β1 induced EMT-like transformation in PHNECs, featured by changes in cell morphology and upregulation of mesenchymal proteins and miR-21. The miR-21 inhibitor, as well as the Akt-specific -inhibitor, suppressed TGF-β1-induced EMT. Mechanically, downregulation of miR-21 resulted in increased PTEN and decreased Akt phosphorylation. Furthermore, overexpression of miR-21 had the opposite effects.

CONCLUSIONS

Our findings suggest that the TGF-β1-miR-21-PTEN-Akt axis may contribute to the pathogenesis of CRSwNP. miR-21 might be a reliable target for treating nasal polyp genesis through EMT suppression. Moreover, miR-21 inhibitors could be a novel class of antipolyp drug that modulates PTEN expression and Akt activation. In addition, further investigation regarding the reason underlying miR-21 overexpression in CRSwNP could provide a molecular target for novel treatment strategies for nasal polyposis.

Profibrotic transforming growth factor beta 1 and activin A are increased in nasal polyp tissue and induced in nasal polyp epithelium by cigarette smoke and Toll-like receptor 3 ligation

BACKGROUND

The mechanism of airway remodeling in chronic rhinosinusitis with nasal polyposis (CRSwNP) remains unknown. We wished to determine whether profibrotic transforming growth factor beta 1 (TGF-β1) and activin A and their downstream signaling proteins are increased in CRSwNP and if they are regulated in epithelial cells by noxious or inflammatory stimuli.

METHODS

Frozen tissue from CRSwNP patients, healthy control (HC) middle turbinates, and sinus tissue from CRS without NP (CRSsNP) patients were immunostained for TGF-β1, activin A, and downstream signaling proteins. Primary nasal epithelial cells (PNECs) from HCs and CRSwNP patients were cultured in media, cigarette smoke extract (CSE), or double-stranded RNA (dsRNA) (a ligand for Toll-like receptor-3) and examined for inflammatory and profibrotic genes using real-time polymerase chain reaction (PCR).

RESULTS

CRSwNP patients showed increased TGF-β1 and activin A in the stroma, increased TGF-β1 signaling (phosphorylated Smad2/3) in the stroma and epithelium, and increased Smad3-dependent Snail1 in the stroma. Immunostaining for TGF-β1, pSmad2/3, and Snail1 in CRSwNP patients was highly correlated. Immunostaining for pSmad2/3 and Snail1 was similar in CRSwNP and CRSsNP patients. Compared to HCs, PNECs from CRSwNP patients were more responsive to CSE and dsRNA in terms of TGF-β1 and activin A and more strongly induced by dsRNA in terms of chemokines.

CONCLUSION

Increased TGF-β1 and activin A and increased downstream TGF-β1 signaling is present in CRSwNP patients, primarily in the stroma. This may contribute to features of airway remodeling previously described. PNECs from CRSwNP patients are induced to produce TGF-β1 and activin A by CSE and dsRNA, suggesting that cigarette smoke and viral infection might also contribute to airway remodeling.

Clinical survey and analysis of Chinese patients with family history of nasal polyposis

CONCLUSION

Nasal polyposis (NP) is frequently found to run in families. Earlier onset of the condition strongly suggested the genetic basis for the development of NP and implied that it might be a genetic disease involving multiple genes.

OBJECTIVE

The etiology and pathogenesis of NP remain largely unknown, although it is assumed to be associated with allergic reaction and infection. The reported familial cases suggested hereditary factors existing in NP. The purpose of this study was to determine whether a hereditary factor could be implicated in NP.

METHODS

A total of 418 NP patients admitted to our department were questioned concerning the existence of familial history (parents, siblings or children) and other accompanying diseases.

RESULTS

In all, 253 cases were successfully followed up. Among these, 44 cases (17.4%) were confirmed to have a familial history of NP, most (59.1%) of which had two immediate family members with a positive family history, with the distribution significantly greater among first-degree and second-degree relatives. Patients with familial NP reported an earlier onset (mean age = 27.7 years) than the sporadic group (mean age = 32.7 years, t = 2.133, p < 0.05). No statistical significance was found when both groups were associated with fungal and allergic diseases.