Intraepithelial lymphocyte subpopulations and dendritic accessory cells in normal and hypertrophic adenoids

COVID-19 in the tonsillectomised population

Objective

Interactions between SARS-CoV-2 and pharyngeal associated lymphoid tissue are thought to influence the manifestations of COVID-19. We aimed to determine whether a previous history of tonsillectomy, as a surrogate indicator of a dysfunctional pharyngeal associated lymphoid tissue, could predict the presentation and course of COVID-19.

Methods

Multicentric cross-sectional observational study involving seven hospitals in Northern and Central Italy. Data on the clinical course and signs and symptoms of the infection were collected from 779 adults who tested positive for SARS-CoV-2, and analysed in relation to previous tonsillectomy, together with demographic and anamnestic data.

Results

Patients with previous tonsillectomy showed a greater risk of fever, temperature higher than 39°C, chills and malaise. No significant differences in hospital admissions were found.

Conclusions

A previous history of tonsillectomy, as a surrogate indicator of immunological dysfunction of the pharyngeal associated lymphoid tissue, could predict a more intense systemic manifestation of COVID-19. These results could provide a simple clinical marker to discriminate suspected carriers and to delineate more precise prognostic models.

The central role of the nasal microenvironment in the transmission, modulation, and clinical progression of SARS-CoV-2 infection

The novel coronavirus SARS-CoV-2 enters into the human body mainly through the ACE2 + TMPRSS2+ nasal epithelial cells. The initial host response to this pathogen occurs in a peculiar immune microenvironment that, starting from the Nasopharynx-Associated Lymphoid Tissue (NALT) system, is the product of a long evolutionary process that is aimed to first recognize exogenous airborne agents. In the present work, we want to critically review the latest molecular and cellular findings on the mucosal response to SARS-CoV-2 in the nasal cavity and in NALT, and to analyze its impact in the subsequent course of COVID-19. Finally, we want to explore the possibility that the regulation of the systemic inflammatory network against the virus can be modulated starting from the initial phases of the nasal and nasopharyngeal response and this may have several clinical and epidemiological implications starting from a mucosal vaccine development.

Dendritic cells and lymphocyte subpopulations of the adenoid in the pathogenesis of otitis media with effusion

OBJECTIVE

To assess dendritic cells and lymphocyte subpopulations of adenoid and peripheral blood in patients with adenoid hypertrophy and otitis media with effusion (OME). To explain the influence of immunological status of adenoid on the development of OME.

METHODS

The examined group covered 123 surgically treated patients due to adenoid hypertrophy (39 children with coexisting OME). Preoperative clinical examination included anamnesis and otorhinolaryngological examination with nasofiberoscopy, videootoscopy and assessment of the hearing organ. The material of the study were surgically removed adenoids and peripheral blood samples prepared and then analyzed by the means of tri-colour flow cytometry. The obtained results were statistically analyzed.

RESULTS

Significant differences between patients with adenoid hypertrophy with coexisting OME and children without OME concerning CD19+CD69+, CD3+CD69+, CD4+CD69+CD8+CD69+ and CD19+CD25+ cells were observed. No statistical differences were revealed in the blood of patients with and without OME. Several statistical differences were noted between the adenoid and peripheral blood in patients with otitis media with effusion concerning BDCA-2+/CD123+ cells, CD3+ and CD19+ lymphocytes with the markers of their activation.

CONCLUSIONS

The adenoid is involved in local immune response regardless of constitutional immunological mechanisms in patients with OME coexisting with adenoid hypertrophy. Significantly lower percentage of CD3+CD69+, CD4+CD69+, CD8+CD69+ and CD19+CD69+ cells of adenoid in patients with OME attests to reduced T-cells activation of the adenoid in relation to patients without OME.

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.

The Bak protein expression in germinal centers of hypertrophied adenoids in children

The aim of this study was to evaluate pro-apoptotic Bak expression in the germinal centers of adenoid in children on the assumption of the potential usefulness of Bak as adenoid function marker. The study involved 95 children undergoing adenoidectomy; divided into three age groups: aged up to 5 years (25 children), 5-10 years (54 children) and over 10 years (16 children). The analyzed material was adenoids removed on the ground of hypertrophy. Immunohistochemical analyses were carried out using goat polyclonal Bak antibodies (DAKO) directed against human Bak protein. The presence of Bak positive lymphocytes within germinal centers and Bak immunostaining were scored. The immunohistochemical staining showed the Bak positive lymphocytes mainly within the germinal centers of the lymphoid follicles. The Bak reactivity was also present in hyperplastic lymphoid tissue within the subepithelial B lymphocytes. We have not found statistically significant correlation between Bak expression and clinical status and change in Bak expression level according to age. The apoptotic presence within the germinal centers are the manifestation of which is Bak expression and its lack in the mantle zone, what we confirmed in our former study by describing Bcl-2 expression, seems to be a proper B cells maturation marker within lymphoid follicles. Our finding shows that these processes are not influenced by age and supports our thesis that adenoid involution is rather the effect of changes in the number of lymphoid follicles that changes in them.

Mucin gene expression in hypertrophic adenoids

CONCLUSION

Membrane-bound mucin MUC4 represents the predominant mucin expressed in the adenoid epithelium followed by MUC5AC (gel-forming mucin). This may suggest that membrane-bound mucins could be involved in pathogen binding and immunological stimulation.

OBJECTIVES

The aim of this study was to investigate mucin expression in hypertrophic adenoids.

MATERIALS AND METHODS

Adenoidal samples were obtained from 12 children. The expression of eight mucin genes, MUC1-4, MUC5AC, 5B, 6 and 7 was studied by in situ hybridization utilizing digoxigenin-labelled oligonucleotide probes.

RESULTS

The dominant mucin genes were MUC4, 3 and 5AC, while MUC1, 2, 5B and 7 were sparsely expressed and MUC6 was not expressed. Expression patterns were very different from those in the upper airways. Most samples expressed two membrane-bound mucins (MUC4 and 3) and one secretory mucin (MUC5AC).

Autoimmunity in the etiology of otitis media with effusion

Otitis media with effusion (OME) is one of the most common health problems seen in children. The role of autoimmunity in the etiology of OME has been discussed for a long time. The purpose of this investigation is to determine the role of circulating antibodies in the pathogenesis of OME. The presence of antibodies against rabbit tympanic bulla epithelium was investigated by indirect immunoflouresence in the serum samples of 25 patients with OME and serum samples of 25 healthy children as a control group. In the control group, positive staining was seen in only 1 case (4%), whereas 8 cases with OME were positively stained (%32). There was statistically significant difference between the 2 groups. The presence of antibodies against middle ear epithelium in the cases with OME suggest that autoimmunity might play a role in the formation of effusion in the tympanic cavity.

Adenoids and otitis media with effusion: a morphological study

PURPOSE

Adenoidectomy, especially for the treatment of suppurative otitis media, has been used for a very long time. In this study, the role of adenoids in the origin of otitis media with effusion was investigated by using light microscopy, immunocytochemistry, enzyme chemistry, and electron microscopy.

MATERIALS AND METHODS

A group of 28 children with otitis media with effusion (OME) was identified. Ages ranged from 3 to 12 years. A control group of 10 age-matched children without any middle ear and upper respiratory tract infection served as the basis for comparison. Specimens obtained at surgeries from both groups were divided into groups for light microscopy, immunocytochemistry, enzyme cytochemistry, and electron microscopy and then all were examined blindly. Also, quantitative analysis of antigen-presenting cells was performed blindly on 10 patients and 10 controls.

RESULTS

There was an increase in the number of lymphocytes, mast cells, plasma cells, macrophages, dendritic cells, and M cells in the adenoids of patients with OME when compared with the normal cases. Stratified squamous epithelial areas, collagenous fibers, and fibrocytes were also increased in the patient group. Antigen-presenting functions of epithelial cells are shown by major histocompatibility complex (MHC) class II positivity of some ciliated-columnar epithelial cells in the patient group.

CONCLUSION

Adenoid tissues of patients with OME in this study seem to be infectious foci, aggravating immune reactions, which might attack the middle ear through an ascending route.