Secretion rates of human nasal submucosal glands from patients with chronic rhinosinusitis or cystic fibrosis

Septum submucosal glands exhibit aberrant morphology and reduced mucin production in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is characterized by significant accumulation and thickening of mucus in the sinonasal cavities. One contributor of aberrant mucus production and impaired mucociliary clearance (MCC) is altered function of the sinonasal submucosal glands (SMGs), yet contributions of SMGs to upper airway disease initiation and progression remain unknown. The objective of this study was to characterize the morphology and secretory cell identities of the nasal septum SMGs in both healthy and CRS adults.

METHODS

Biopsies from adult participants with CRS without nasal polyps (CRSsNP, n = 4), CRS with nasal polyps (CRSwNP, n = 8), and non-CRS controls (n = 14) were collected from the posterior septum. Glandular morphology and mucus markers were investigated using histological techniques and high-resolution confocal microscopy.

RESULTS

Analysis revealed a significant decrease in gland density in the posterior septum of CRSsNP (28% ± 6.15%) and CRSwNP (23% ± 3.09%) compared to control participants (53% ± 1.59%, p < 0.0001). Further analysis of the CRS SMG secretory function revealed an overall decrease in Mucin 5B+ gland mucus being produced. Dilated and cystic ductal structures filled with inspissated mucus were also common to CRS glands.

CONCLUSION

Here, we describe a significant alteration in SMG structure and function in the adult CRS posterior septum suggesting reduced gland contribution to MCC. The SMGs of both the nose and sinuses may represent targets for future therapeutic approaches.

FGF10 is an essential regulator of tracheal submucosal gland morphogenesis

Mucus secretion and mucociliary clearance are crucial processes required to maintain pulmonary homeostasis. In the trachea and nasal passages, mucus is secreted by submucosal glands (SMGs) that line the airway, with an additional contribution from goblet cells of the surface airway epithelium. The SMG mucus is rich in mucins and antimicrobial enzymes. Defective tracheal SMGs contribute to hyper-secretory respiratory diseases, such as cystic fibrosis, asthma, and chronic obstructive pulmonary disease, however little is known about the signals that regulate their morphogenesis and patterning. Here, we show that Fgf10 is essential for the normal development of murine tracheal SMGs, with gland development arresting at the early bud stage in the absence of FGF10 signalling. As Fgf10 knockout mice are lethal at birth, inducible knockdown of Fgf10 at late embryonic stages was used to follow postnatal gland formation, confirming the essential role of FGF10 in SMG development. In heterozygous Fgf10 mice the tracheal glands formed but with altered morphology and restricted distribution. The reduction in SMG branching in Fgf10 heterozygous mice was not rescued with time and resulted in a reduction in overall tracheal mucus secretion. Fgf10 is therefore a key signal in SMG development, influencing both the number of glands and extent of branching morphogenesis, and is likely, therefore, to play a role in aspects of SMG-dependent respiratory health.

Nf-GH, a glycosidase secreted by Naegleria fowleri, causes mucin degradation: an in vitro and in vivo study

AIM

The aim of this work was to identify, characterize and evaluate the pathogenic role of mucinolytic activity released by Naegleria fowleri.

MATERIALS & METHODS

Zymograms, protease inhibitors, anion exchange chromatography, MALDI-TOF-MS, enzymatic assays, Western blot, and confocal microscopy were used to identify and characterize a secreted mucinase; inhibition assays using antibodies, dot-blots and mouse survival tests were used to evaluate the mucinase as a virulence factor.

RESULTS

A 94-kDa protein with mucinolytic activity was inducible and abolished by p-hydroxymercuribenzoate. MALDI-TOF-MS identified a glycoside hydrolase. Specific antibodies against N. fowleri-glycoside hydrolase inhibit cellular damage and MUC5AC degradation, and delay mouse mortality.

CONCLUSION

Our findings suggest that secretory products from N. fowleri play an important role in mucus degradation during the invasion process.

Factors influencing the need for endoscopic sinus surgery in adult patients with cystic fibrosis

BACKGROUND

Risk factors in adult patients with cystic fibrosis (CF) associated with surgical intervention have not been delineated.

OBJECTIVE

To identify characteristics of adult patients with CF and with chronic rhinosinusitis that predict surgical intervention with endoscopic sinus surgery (ESS).

METHODS

Patients were identified in a tertiary sinus center by the International Classification of Diseases, Ninth Revision codes 277.00-277.03, which represent CF. Charts were reviewed for the CF transmembrane conductance regulator (CFTR) gene mutation, Lund-Mackay score (LMS), the 22-item Sino-Nasal Outcome Test (SNOT-22) score, previous ESS, and occurrence of ESS after presentation. The Fisher exact test was used to test frequency of events between the groups, and the Mann Whitney U test and the t-test were used to compare means among LMS, SNOT-22, and age. The Cox proportional hazard analysis was used to calculate hazard ratios (HR) for the impact of LMS, SNOT-22 score, previous ESS, and CFTR gene mutation status on the occurrence of ESS after presentation.

RESULTS

One hundred and fifteen patients met the inclusion criteria for the study. Patients with a history of surgery more often underwent ESS after presentation (p ≤ 0.01). The LMS and the SNOT-22 score were not significantly different between the groups of previous ESS and no previous ESS (p = 0.23 and p = 0.28, respectively). A severe mutation genotype was predictive of ESS after presentation (p = 0.03). SNOT-22 scores did not differ between the severe and mild groups (36.0 and 32.4, respectively; p = 0.57), but the mean LMS was significantly higher in the severe mutation group (12.5 and 9.7; p ≤ 0.01). Univariate Cox proportional hazard analysis revealed an increased occurrence of ESS for patients with severe mutations (HR, 3.6; p ≤ 0.01) or a history of ESS (HR, 2.3; p ≤ 0.01).

CONCLUSION

The occurrence of ESS in adult patients with CF was predicted by previous ESS intervention as well as the severity of CFTR mutation.