Morphological characterization of the false vocal cords as larynx-associated lymphoid tissue

Laryngeal T regulatory cells in the setting of smoking and reflux

OBJECTIVES/HYPOTHESIS

The larynx is a mucosal organ rich in lymphatic tissue that is regularly exposed to a multitude of inhaled, ingested, and refluxed microorganisms and irritants. The first line of mucosal immune defense is the barrier, including resident immune cells. T regulatory (Treg) cells are a specialized subset of CD4+ T cells that suppress or dampen immune responses to prevent damaging immunopathology. As Treg cells have been shown to preferentially accumulate at sites of infection, and Treg responses may contribute to persistence of infection by impairing antibacterial immunity, we sought to quantify these cells in laryngeal tissue exposed to smoking and reflux.

STUDY DESIGN

Cross-sectional study.

METHODS

Using an epigenetic assay, we quantified Treg and T cells and calculated the ratio of Treg to T cells (i.e., cellular ratio of immune tolerance [ImmunoCRIT]) in disease-free laryngeal biopsies representing four inflammatory states: 1) tobacco-exposed tissue, 2) refluxate and tobacco-exposed tissue, 3) refluxate-exposed tissue, and 4) unexposed tissue.

RESULTS

There was epigenetic evidence of Treg cells in all tissues, and we found no differences in Treg cell frequency relative to smoking and reflux in laryngeal tissue collected from 42 non-treatment-seeking participants. There was a decrease in total T cell frequency and an increase in ImmunoCRIT values in smokers regardless of reflux status.

CONCLUSIONS

In this study, laryngeal tissue from smokers show decreased overall T cells and increased ImmunoCRIT values. Our findings indicate that laryngeal inflammation is not directly mediated by loss of Treg cells in response to smoking and reflux in local tissue and increased ImmunoCRIT values in smokers implicate a role for this environmental exposure in modulating laryngeal immune homeostasis. More studies are indicated to explore Treg cell dysfunction in the pathophysiology of laryngeal disease.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:882-887, 2017.

Comparison of the larynx-associated lymphoid tissue in the false vocal cords and subglottis in pediatric autopsies

The aim this work was to compare the distribution of cellular phenotypes of the LF in the FVC to the ones in the subglottic region in pediatric autopsy, relating this distribution to age and different causes of death. We analyzed 60 larynges of newborns and children autopsied in the period from 1993 to 2003. The fragments were prepared in order to perform histochemical and immunohistochemical techniques. The morphological analysis showed cases that presented LF only in FVC (35%), LF only in the subglottic region (20%), lack of LF in FVC (30%) and lymphoid aggregates, which did not characterize an LF (15%). The cases of LF in the subglottic region were significantly younger compared to the ones that presented LF in the FVC (p=0.017). The LF in the subglottic region was bigger than the LF in the FVC (p=0.020). There was no significant difference between the cause of death and cellular phenotype for both FVC and the subglottic region. In conclusion, the cells that make up the LF in the FVC in newborns and children younger than one year have functional characteristics similar to LF cells in the subglottic region, suggesting that there are similarities with LALT.