Epithelial responses in airway inflammation and immunity

Adenoid as a source of lymphocytes in the surface secretions of nasopharynx

OBJECTIVE

The significance and protective efficacy of surface secretions on mucosal membranes in the upper airways are well recognized. The aim of our study was to reveal the role of the adenoids as a source of cellular components in the mucosal secretion.

METHODS

The adenoid removed because of its hypertrophy and the samples of surface secretions taken by "imprint method" described by Ebenfelt et al. from the group of 38 children were examined by flow cytometry. The lymphocyte subsets with following antigens: CD3, CD4, CD8, CD19, CD23, CD16+56, CD45RA, CD45RO, HLA-DR were analyzed. Two groups were studied: (1) AH, children with adenoid hyperplasia without otitis media; (2) OME, children with adenoid hyperplasia and persistent otitis media with effusion. Age-related changes in percentages of lymphocyte subpopulations were analyzed.

RESULTS

The percentage of lymphocyte subsets in adenoid and secretion were similar, however, in the surface secretion there was higher proportion of lymphocytes B and NK and lower of T. There was no correlation between percentages of lymphocyte in adenoid and surface secretion except for lymphocytes Th with memory phenotype and lymphocytes B with marker CD23(+). In adenoid the percentage of T and Th lymphocytes increased with age and the percentage of B lymphocytes decreased. In the secretion age-related changes were less pronounced and only the percentage of lymphocytes B CD23(+) showed positive correlation with age. In cases of otitis media with effusion there was higher proportion of lymphocytes B (CD19(+) and CD19(+)CD23(+)) and lower of lymphocytes Ts and Th with naive phenotype in the secretion. In adenoid however, the cases of OME revealed lower percentage of lymphocytes B and higher of lymphocytes Ts.

CONCLUSIONS

Similar proportions of lymphocyte subpopulations in surface secretion and in adenoid imply that adenoid is the source of those cells. However, lack of correlation between the percentages of lymphocytes in secretion and in adenoid suggest that the process of lymphocyte migration has active and selective character.

A comparison of experimental methods in molecular chronic rhinosinusitis research

BACKGROUND

Research into the molecular pathogenesis of chronic rhinosinusitis (CRS) requires the collection and analysis of sinonasal tissue. Recent gene expression studies have used either surgical tissue specimens or isolated epithelial cell preparations. Here, we compare cultures of nasal epithelial cells, nasal brush biopsy, and whole ethmoid mucosa with respect to expression of innate immune genes.

METHODS

Ethmoid mucosa was collected intraoperatively from 12 CRS and control patients. This tissue either was processed whole for mRNA extraction or was used to generate primary nasal epithelial cell cultures. After 6 weeks, epithelial cells in culture were assessed for multiple innate immune proteins by flow cytometry. In parallel, middle meatal brush biopsy specimens were obtained from the same patients and studied acutely in a similar fashion by flow cytometry. Expression of innate immune genes was determined in whole tissue samples by real-time polymerase chain reaction.

RESULTS

Flow cytometry revealed that brush biopsy specimens contain 75% epithelial cells, whereas primary nasal epithelial cell cultures were pure. Epithelial cells derived from individual subjects expressed very similar levels of innate immune markers whether studied acutely or after 6 weeks in culture. Whole tissue mRNA levels were variable and not correlated to epithelial expression.

CONCLUSION

The choice of experimental methodology can greatly influence the results and interpretation of CRS research. Primary nasal epithelial cells maintain their innate immune receptor expression profile when grown in prolonged culture in vitro. These findings imply that alterations in innate immune gene expression in CRS may be intrinsic to the epithelial cells, even outside of their in vivo microenvironment.

In vivo imaging and genetic analysis link bacterial motility and symbiosis in the zebrafish gut

Complex microbial communities reside within the intestines of humans and other vertebrates. Remarkably little is known about how these microbial consortia are established in various locations within the gut, how members of these consortia behave within their dynamic ecosystems, or what microbial factors mediate mutually beneficial host-microbial interactions. Using a gnotobiotic zebrafish-Pseudomonas aeruginosa model, we show that the transparency of this vertebrate species, coupled with methods for raising these animals under germ-free conditions can be used to monitor microbial movement and localization within the intestine in vivo and in real time. Germ-free zebrafish colonized with isogenic P. aeruginosa strains containing deletions of genes related to motility and pathogenesis revealed that loss of flagellar function results in attenuation of evolutionarily conserved host innate immune responses but not conserved nutrient responses. These results demonstrate the utility of gnotobiotic zebrafish in defining the behavior and localization of bacteria within the living vertebrate gut, identifying bacterial genes that affect these processes, and assessing the impact of these genes on host-microbial interactions.

Sinonasal epithelial cell expression of toll-like receptor 9 is decreased in chronic rhinosinusitis with polyps

BACKGROUND

Innate immune recognition of pathogens by sinonasal epithelial cells may play an important role in the pathogenesis of chronic rhinosinusitis (CRS). Previous studies have indicated that toll-like receptor (TLR) mRNA is present in sinonasal mucosa, and levels of TLR9 expression are decreased in recalcitrant CRS with nasal polyps (CRSwNP). However, the cellular source and function of TLR9 in the sinonasal epithelium is not known. In this study, primary epithelial cell cultures were analyzed from control subjects and CRSwNP patients to determine the presence and function of TLR9 protein.

METHODS

Primary epithelial cell cultures were established from 5 controls and 10 CRSwNP patients undergoing sinus surgery. Flow cytometry was used to confirm purity of epithelial cells and to assess expression of TLR9 protein. Epithelial cells were stimulated with TLR9 agonist, and mRNA was analyzed by real-time PCR for expression of human beta-defensin (HBD) 2 and interleukin (IL)-8.

RESULTS

Flow cytometry showed TLR9 protein in 100% of epithelial cells from controls and CRSwNP patients. The level of expression was 50% lower in CRS patients than in controls. Stimulation of epithelial cells with TLR9 agonist produced a 1.5- to 9-fold increase in HBD-2 and IL-8 mRNA expression.

CONCLUSION

Functional TLR9 protein is expressed by normal and diseased sinonasal epithelial cells. The level of TLR9 expression is decreased in CRSwNP patients, consistent with the previous finding of decreased TLR9 mRNA in whole sinonasal tissue. These findings suggest that impaired innate immune responses to pathogens via TLR9 on sinonasal epithelial cells may represent a critical mechanism in chronic inflammatory sinus disease.