Acute laryngotracheitis in the rat induced by Sendai virus: the influx of six different types of immunocompetent cells into the laryngeal mucosa differs strongly between the subglottic and the glottic compartment

Prospective, Multi-Center Study of the Anatomic Distribution of Recurrent Respiratory Papillomatosis

OBJECTIVES/HYPOTHESIS

To create a model of the anatomic distribution, recurrence, and growth patterns of recurrent respiratory papillomatosis (RRP).

STUDY DESIGN

Prospective, multi-institutional cohort study.

METHODS

Adult patients with a diagnosis of RRP evaluated between August 1, 2018 and February 1, 2021 at six participating centers were invited to enroll. At each office or operating room encounter, laryngologists recorded the location and size of RRP lesions using a 22-region schematic. A generalized linear mixed effects model was used to compare region variations in lesion prevalence and recurrence.

RESULTS

The cohort comprised 121 patients: 74% were male, 81% had been diagnosed with adult-onset RRP, and a plurality (34%) had undergone 0 to 3 RRP interventions prior to enrollment. Across the study period, the odds of a lesion occurring in the glottis was significantly higher (odds ratio [OR]: 26.51; 95% confidence interval [CI]: 11.76-59.75, P < .001) compared with all other areas of the larynx and trachea. Within the true vocal folds, the membranous vocal folds had significantly higher odds (OR: 6.16; 95% CI: 2.66-14.30, P < .001) of lesion occurrence compared to the cartilaginous vocal folds. Despite these strong trends in lesion distribution, there were no differences in the odds of lesion recurrence, growth, or in the time to recurrence, between anatomic subsites.

CONCLUSIONS

RRP lesions are most likely to occur in the glottis, particularly the membranous vocal folds, compared with other regions of the larynx or trachea. However, all lesions demonstrate similar behavior with respect to recurrence, growth, and time to recurrence regardless of anatomic location.

LEVEL OF EVIDENCE

3 Laryngoscope, 132:2403-2411, 2022.

Quantitative Analysis of OX62-Positive Dendritic Cell Distribution in the Rat Laryngeal Complex

Objectives:

Dendritic cells (DCs) are key instigators of rejection after transplantation. Their distribution has not been systematically characterized in all locations of the larynx and its surrounding tissues.

Methods:

Rat larynges were stained with monoclonal antibodies identifying DCs. These cells were then enumerated by a new combination of techniques including immunofluorescence, confocal microscopy, and imaging software.

Results:

The vast majority of DCs were located in the epithelium and subepithelium of the airway; the mean DC density ranged from 9 cells per square millimeter (0.2% of cells) to 645 cells per square millimeter (10.3% of cells). Their density in the epithelium was 3 to 11 times higher than that in the subepithelium. Non-airway sites (thyroid, parathyroid, muscle, fat) had mean DC densities varying from 3 cells per square millimeter (0.2%) to 57 cells per square millimeter (0.8%). No DCs were detected in cartilage.

Conclusions:

Dendritic cells are concentrated in the laryngotracheal epithelium and subepithelium and represent a much smaller proportion in the other sites studied. A baseline for laryngeal DC population studies has been established, and a computerized model for consistent quantitation using confocal microscopy has been developed. This unique method will serve as a foundation for investigating DC trafficking after rat laryngeal transplantation.

Antigen challenge induces a supraglottic but not a subglottic edema in the rat larynx

OBJECTIVE: To examine the reaction of mast cells in the larynx of sensitized rats after allergen challenge and determine whether a type I hypersensitivity reaction can elicit a supraglottic and subglottic edema.

STUDY DESIGN: Rats were sensitized with ovalbumin (OA) and challenged 3 weeks later by intravenous injection of either OA or NaCl and perfused with glutaraldehyde. The larynges were removed and processed for light and electron microscopy. Sections from the epiglottis and subglottic region were examined.

RESULTS: In challenged animals, the connective tissue mast cells (CTMC) in the epiglottic submucosa, but not the mucosal mast cells (MMC) in epithelium, were significantly reduced compared with the case of controls, and the connective tissue was edematous. In the subglottic region, the number of both MMC and CTMC was reduced (albeit not significantly), and there was no edema in the lamina propria.

CONCLUSIONS: Allergen challenge induces a marked edema in the epiglottis but not in the subglottic area.

SIGNIFICANCE: The results indicate that the supraglottic and subglottic regions react differently to allergen challenge. (Otolaryngol Head Neck Surg 2005;132:694-700.)

The mucosal immune response to laryngopharyngeal reflux

RATIONALE

Laryngopharyngeal reflux (LPR) affects up to 20% of Western populations. Although individual morbidity is usually moderate, treatment costs are high and there are associations with other diseases, including laryngeal cancer. To date, there have been no studies of the mucosal immune response to this common inflammatory disease.

OBJECTIVES

To determine the mucosal immune response to LPR.

METHODS

We performed a prospective immunologic study of laryngeal biopsies from patients with LPR and control subjects (n = 12 and 11, respectively), and of primary laryngeal epithelial cells in vitro.

MEASUREMENTS AND MAIN RESULTS

Quantitative multiple-color immunofluorescence, using antibodies for lymphocytes (CD4, CD8, CD3, CD79, CD161), granulocytes (CD68, EMBP), monocytic cells (CD68, major histocompatibility complex [MHC] class II), and classical and nonclassical MHC (I, II, beta(2)-microglobulin, CD1d). Univariate and multivariate analysis and colocalization measurements were applied. There was an increase in percentage area of mucosal CD8(+) cells in the epithelium (P < 0.005), whereas other leukocyte and granulocyte antigens were unchanged. Although epithelial MHC class I and II expression was unchanged by reflux, expression of the nonclassical MHC molecule CD1d increased (P < 0.05, luminal layers). In vitro, laryngeal epithelial cells constitutively expressed CD1d. CD1d and MHC I expression were inversely related in all subjects, in a pattern which appears to be unique to the upper airway. Colocalization of natural killer T (NKT) cells with CD1d increased in patients (P < 0.01).

CONCLUSIONS

These data indicate a role for the CD1d-NKT cell axis in response to LPR in humans. This represents a useful target for novel diagnostics and treatments in this common condition.

From grunts to words: experiments in laryngeal transplantation

INTRODUCTION

Laryngeal transplantation remains an increasingly viable option for patients with irreversible disease or damage to the larynx. Successful organ transplantation relies on minimising surgical, ischaemic and immunological insults. The inherent immunogenicity of an organ is dependent on the amount of immunologically active cells within it. The presence of immunologically active cells within non-transplanted NIH-minipigs was investigated and an in vivo laryngeal transplant model was developed.

MATERIALS AND METHODS

Quantitative, multiple-colour immunofluorescence using pig-specific monoclonal antibodies was used to assess the normal immunological architecture and the short-term immunological changes associated with 3 h of cold ischaemia and 8 h of reperfusion in an MHC-matched animal model.

RESULTS AND CONCLUSIONS

There is a complex immunological architecture within the non-transplanted, healthy pig larynx. In addition, an in vivo laryngeal transplant model was developed that allowed successful perfusion for 8 h post transplantation. There were significant changes in cell numbers within different anatomical subsites of the larynx. However, the biological significance remains debatable in view of the large range of cell numbers both within and between individual animals.

The larynx as an immunological organ: immunological architecture in the pig as a large animal model

The larynx is a mucosal organ positioned at the divergence of the respiratory and digestive tracts. It is exposed to a wide variety of environmental components, including foreign antigens, tobacco smoke, laryngopharyngeal reflux and pollutants. The mucosal immune system generates either active immune responses or tolerance, depending on the nature of the antigen and we hypothesize that the larynx is important organ for immunological decision-making in the airway. Because the pig is an ideal large animal model in which to explore laryngological research questions, such as those relating to laryngeal transplantation, we investigated the normal mucosal immunology of the porcine larynx. Pig larynges and tracheae were processed and prepared for bright-field microscopy and quantitative, multiple-colour immunofluorescence histology using pig-specific monoclonal antibodies. There was an abundance of immunologically active cells within the mucosa of the larynx and trachea of both the newborn and adult animal. Specifically, major histocompatibility complex class II (MHC class II+) cells, CD4+ and CD8+ cells were identified, although regional differences in numbers were apparent: specifically, the supraglottis contained fewer immunologically relevant cells than other sites sampled. There was a significant correlation between the numbers of MHC class II+ and CD4+ cells indicating co-ordinate regulation and therefore functional local interactions. The presence of such an immunological structure suggests that the larynx may have important functions in respiratory immunology and that it may trigger strong alloresponses after laryngeal transplantation.

Presence of dendritic cells, T lymphocytes, macrophages, B lymphocytes and glandular tissue in the human fetal larynx

OBJECTIVE

The laryngeal mucosa starts to be exposed to infectious agents immediately after birth. The course of laryngeal infections in young children differs significantly from that in adults. The first line of defense encountered by an inhaled infectious agent is the mucosa-associated immune system, which includes immunocompetent cells and secretory components. The cellular elements are partially organized in a typical morphological pattern known as mucosa-associated lymphoid tissue (MALT). Differences in the ability of young children and adults to react to a laryngeal infection raise the questions of whether and to what extent immunocompetent cells are already present in the larynx at birth. These questions were investigated in this study.

MATERIAL AND METHODS

Dendritic cells, T lymphocytes, B lymphocytes, macrophages and glands were examined and detected in an (immuno-)histological study of 8 fetal larynges (14th-22nd week of gestation).

RESULTS

Immunocompetent cells and glands were present mainly in the epi- and subglottic regions and ventricular folds, whereas the glottis was largely spared. The pattern of distribution was scattered and no organized MALT was seen.

CONCLUSION

Essential cell populations of a mucosa-associated immune system for the initiation of an immune response may exist in the human larynx at birth.

TFF peptides in the human false vocal folds of the larynx

TFF peptides (formerly P domain peptides, trefoil factors) are typical secretory products of mucin-producing cells and are thought to influence the rheological properties of mucous gels. We investigated the localization of these peptides in the human false vocal folds of the larynx, also known as the ventricular folds or vestibular folds. An analysis of TFF peptide mRNA by RT-PCR and TFF protein by Western blot detected TFF1 and TFF3, but not TFF2. Immunohistochemistry revealed TFF1 to be associated with the secretory product of goblet cells and mucous parts of subepithelial seromucous glands. TFF3 occurred in columnar epithelial cells of the mucosa and in serous cells and excretory duct cells of seromucous glands. These peptides may play a role in the rheological function of mucus secreted onto the true vocal folds and are thus important constituents of vocal production.

Region-specific immunological response of the different laryngeal compartments: significance of larynx-associated lymphoid tissue

The occurrence of primary extranodal marginal-zone B-cell lymphoma [of the mucosa-associated lymphoid tissue (MALT) type] has only been described in the supraglottic region, implying that preexistent organized lymphoid tissue is present at that site only. To date, studies have not established clearly whether organized MALT shows a site-related distribution in the larynx. The supraglottic region of the false vocal folds and the subglottis from 87 unselected cadavers with no known history of nasal, oral, pharyngeal, laryngeal, tracheal, or esophageal disease were examined for the presence of organized MALT. Organized lymphoid tissue was found with the cytomorphological and immunophenotypic features of MALT in 100% of false vocal folds of children and in more than 90% of adolescents, decreasing to 7.1% in persons in their sixth decade, whereas MALT was completely absent in the subglottis in all age groups. The results explain why primary extranodal marginal-zone B-cell lymphoma has only been described in the supraglottic region but is absent in the subglottis. Moreover, the results suggest a region-specific immunological response of the different laryngeal areas as reflected in clinical observations and animal studies. However, the impact on presence or absence of laryngeal MALT awaits clarification.