Nasal glands and goblet cells in chronic hypertrophic rhinitis

Mechanobiology of conjunctival epithelial cells exposed to wall shear stresses

The human conjunctival epithelial cells (HCEC) line the inner sides of the eyelids and the anterior part of the sclera. They include goblet cells that secret mucus into the tear film that protects the ocular surface. The conjunctival epithelium is subjected to mechano-physical stimuli due to eyelid movement during blinking, during wiping and rubbing the eyes, and when exposed to wind and air currents. We cultured primary HCEC under air-liquid interface (ALI) conditions in custom-designed wells that can be disassembled for installation of the in vitro model in a flow chamber. We exposed the HCEC after ALI culture of 8-10 days to steady and oscillatory airflows. The in vitro model of HCEC was exposed to steady wall shear stresses (sWSS) of 0.5 and 1.0 dyne/cm² for lengths of 30 and 60 min and to oscillatory wall shear stresses (oWSS) of 0.5 and 0.77 dyne/cm² amplitudes for a length of 10 min. Cytoskeletal alterations and MUC5AC mucin secretion in response to WSS were investigated using immunohistochemically fluorescent staining and enzyme-linked lectin assay (ELLA), respectively. The results revealed that both exposure times and sWSS values increased the polymerization of F-actin filaments while mucin secretion decreased. However, after a recovery of 24 h in the incubator we observed a decrease of F-actin fibers and mucin secretion only for exposure of 30 min. The length of exposure was more influential on cytoskeletal alterations than the level of sWSS. The very small effect of sWSS on mucin secretion is most likely related to the much smaller amount of goblet cell than in other mucus-secreting tissue. The results for both oWSS amplitudes revealed similar trends regarding F-actin and mucin secretion. Immediately post-exposure we observed an increase in polymerization of F-actin filaments while mucin secretion decreased. However, after 24-h recovery we observed that both F-actin and mucin secretion returned to the same values as for unexposed cultures. The results of this study suggest that WSS should be considered while exploring the physiological characteristics of HCEC.

The Pathogenetic Theories on Formation of Nasal Polyps

Various pathogenetic theories on polyp formation have been reviewed and critically analyzed. The authors’ theories have been discussed. It has been argued that demonstration of formation of mucosal edema and tissue pressure does not explain why the polyps arise in one particular place but not in another.

Neural Abnormalities in Nonallergic Rhinitis

Sensory nerve endings within the airway epithelial cells and the solitary chemoreceptor cells, synapsing with sensory nerves, respond to airborne irritants. Transient receptor potential (TRP) channels (A1 and V1 subtypes, specifically) on these nerve endings initiate local antidromic reflexes resulting in the release of neuropeptides such as substance P and calcitonin G-related peptides. These neuropeptides dilate epithelial submucosal blood vessels and may therefore increase transudation across these vessels resulting in submucosal edema, congestion, and rhinitis. Altered expression or activity of these TRP channels can therefore influence responsiveness to irritants. Besides these pathogenic mechanisms, additional mechanisms such as dysautonomia resulting in diminished sympathetic activity and comparative parasympathetic overactivity have also been suggested as a probable mechanism. Therapeutic effectiveness for this condition has been demonstrated through desensitization of TRPV1 channels with typical agonists such as capsaicin. Other agents effective in treating nonallergic rhinitis (NAR) such as azelastine have been demonstrated to exhibit TRPV1 channel activity through the modulation of Ca(2+) signaling on sensory neurons and in nasal epithelial cells. Roles of antimuscarinic agents such as tiotropium in NAR have been suggested by associations of muscarinic cholinergic receptors with TRPV1. The associations between these channels have also been suggested as mechanisms of airway hyperreactivity in asthma. The concept of the united airway disease hypothesis suggests a significant association between rhinitis and asthma. This concept is supported by the development of late-onset asthma in about 10-40 % of NAR patients who also exhibit a greater severity in their asthma. The factors and mechanisms associating NAR with nonallergic asthma are currently unknown. Nonetheless, free immunoglobulin light chains and microRNA alteration as mediators of these inflammatory conditions may play key roles in this association.

Inferior turbinate goblet cell secretion in patients with perennial allergic and nonallergic rhinitis

Perennial rhinitis is clinically associated with a significant increase in nasal mucus secretion. Moreover, it has already been established that the number of goblet cells, in the inferior turbinates of patients with perennial allergic and nonallergic rhinitis, does not differ from that of normal subjects. Thus a question is raised, whether the above-mentioned phenomenon is ascribed exclusively to submucosal glandular activity, or may also be a result of a nonhyperplastic increase of goblet cell functional activity. This study was conducted to assess inferior turbinate goblet cell mucus secretion in a cohort of patients with perennial allergic and nonallergic rhinitis compared with normal controls. A semiquantitative morphometric method was used to examine goblet cell mucus secretion in sections stained with Alcian blue and periodic acid Schiff. Mucus secretion in each section was established in terms of secretory ratio, calculated as the number of secreting goblet cells divided by the number of nonsecreting ones. The mean secretory ratio of patients with perennial allergic (n = 11) and nonallergic rhinitis (n = 23) was 0.89 and 0.57, respectively, compared to controls (n = 10) 0.25. Statistical analysis confirmed that the secretory ratio of patients with perennial allergic rhinitis was significantly higher than that of the control group. No significant difference prevailed between patients with perennial nonallergic rhinitis and controls, as well as between allergic and nonallergic patients. Based on the results of the study, a basal state of nasal goblet cell mucus secretion in nonstimulated healthy people was established. Furthermore, it was concluded that the enhancement in mucus discharge, from the inferior turbinate goblet cells of patients with perennial allergic rhinitis, was attributed to a nonhyperplastic increase of nasal goblet cell functional activity.

Goblet cell density of the inferior turbinates in patients with perennial allergic and nonallergic rhinitis

Nasal mucus production is regulated by submucosal glands and epithelial goblet cells. The role and especially the number of the latter are quite debatable. The present study compares the distribution and density of goblet cells in the inferior turbinates of patients with perennial allergic and nonallergic rhinitis to normal controls. The periodic acid Schiff-alcian blue whole-mount method was used to identify and count their number. Goblet cell distribution was found nonhomogeneous, and considerable variations were observed among adjacent localities of the same specimen. The mean number of goblet cells per mm2 was 6499 in normal controls (n = 12), 6818 in patients with perennial allergic rhinitis (n = 13), and 6801 in patients with perennial nonallergic rhinitis (n = 18). Statistical analysis confirmed that the density of goblet cells did not differ significantly between patients with and without allergy, as well as between each group of patients and controls. Therefore, it could be concluded that the number of goblet cells in the inferior turbinate is not influenced by the presence of perennial allergic or nonallergic rhinitis.

Factors influencing the goblet cell density in paranasal sinuses

The goblet cell density in normal and abnormal paranasal sinuses is presented and compared with other areas of the respiratory tract. Several factors influencing the goblet cell density are discussed.