Role of Tonsillar Chronic Inflammation and Commensal Bacteria in the Pathogenesis of Pediatric OSA

Paired qualitative and quantitative analysis of bacterial microcolonies in the tonsils of patients with tonsillar hyperplasia

The discovery of bacterial microcolonies in tonsillar tissue of patients with tonsillar hyperplasia has raised the question of their role in provoking the local immune response. Tonsils collected from patients undergoing tonsillectomy were stained for three clinically relevant bacterial taxa and lymphocytes. The bacterial composition and abundance of microcolonies was investigated using a combination of laser-microdissection, amplicon sequencing and Droplet Digital polymerase chain reaction. Microcolonies were detected in most samples (32/35) with a high prevalence of Haemophilus influenzae (78% of samples). B and T cell lymphocytes were significantly higher in the epithelium adjacent to microcolonies compared to epithelium distal to microcolonies. Furthermore, significant positive and negative correlations were identified between bacterial taxa and lymphocytes. Genus Streptococcus, which includes Group A Streptococcus (traditionally described as the main pathogen of tonsillar hyperplasia), was found in low abundance in this study. These results suggest other potential pathogens may be involved in stimulating the local immune response leading to tonsillar hyperplasia.

Risk factors of sleep-disordered breathing and poor asthma control in children with asthma

BACKGROUND

Sleep-disordered breathing (SDB) may lead to poor asthma control in children.

OBJECTIVE

To identify risk factors of SDB in children with asthma and assess its impact on asthma control.

METHODS

In this cross-sectional study, we collected data of outpatients with asthma at the Children's Hospital of Chongqing Medical University from June 2020 to August 2021. The Pediatric Sleep Questionnaire-Sleep-Related Breathing Disorder and the age-appropriate asthma control tests Childhood Asthma Control Test and Test for Respiratory and Asthma Control in Kids were completed.

RESULTS

We enrolled 397 children with a male-to-female ratio of 1.7:1 and a mean age of 5.70 ± 2.53 years. The prevalence of SDB was 21.6%. Allergic rhinitis (odds ratio OR = 3.316), chronic tonsillitis (OR = 2.246), gastroesophageal reflux (OR = 7.518), adenoid hypertrophy (OR = 3.479), recurrent respiratory infections (OR = 2.195), and a family history of snoring (OR = 2.048) were risk factors for the development of combined SDB in children with asthma (p < 0.05). Asthma was poorly controlled in 19.6% of the children. SDB (OR = 2.391) and irregular medication use (OR = 2.571) were risk factors for poor asthma control (p < 0.05).

CONCLUSIONS

Allergic rhinitis, chronic tonsillitis, gastroesophageal reflux, adenoid hypertrophy, recurrent respiratory infections, and a family history of snoring were independent risk factors for the development of SDB in children with asthma. SDB and irregular medication use were independent risk factors for poor asthma control.

Role of germinal center and CD39highCD73+ B cells in the age-related tonsillar involution

BACKGROUND

The tonsils operate as a protection ring of mucosa at the gates of the upper aero-digestive tract. They show similarities with lymph nodes and participate as inductive organs of systemic and mucosal immunity. Based on the reduction of their size since puberty, they are thought to experience involution in adulthood. In this context, we have used tonsillar mononuclear cells (TMC) isolated from patients at different stages of life, to study the effect of ageing and the concomitant persistent inflammation on these immune cells.

RESULTS

We found an age-dependent reduction in the proportion of germinal center B cell population (BGC) and its T cell counterpart (T follicular helper germinal center cells, TfhGC). Also, we demonstrated an increment in the percentage of local memory B cells and mantle zone T follicular helper cells (mTfh). Furthermore, younger tonsils rendered higher proportion of proliferative immune cells within the freshly isolated TMC fraction than those from older ones. We demonstrated the accumulation of a B cell subset (CD20+CD39highCD73+ cells) metabolically adapted to catabolize adenosine triphosphate (ATP) as patients get older. To finish, tonsillar B cells from patients at different ages did not show differences in their proliferative response to stimulation ex vivo, in bulk TMC cultures.

CONCLUSIONS

This paper sheds light on the changing aspects of the immune cellular landscape, over the course of time and constant exposure, at the entrance of the respiratory and digestive systems. Our findings support the notion that there is a re-modelling of the immune functionality of the excised tonsils over time. They are indicative of a transition from an effector type of immune response, typically oriented to reduce pathogen burden early in life, to the development of an immunosuppressive microenvironment at later stages, when tissue damage control gets critical provided the time passed under immune attack. Noteworthy, when isolated from such histologic microenvironment, older tonsillar B cells seem to level their proliferation capacity with the younger ones. Understanding these features will not only contribute to comprehend the differences in susceptibility to pathogens among children and adults but would also impact on vaccine developments intended to target these relevant mucosal sites.

Vitamin D Deficit as Inducer of Adenotonsillar Hypertrophy in Children with Obstructive Sleep Apnea-A Prospective Case-Control Study

(1) Objective: This prospective case-control study aimed to assess the level of serum vitamin D comparing pediatric non-allergic patients with obstructive sleep apnea (OSA) and healthy controls. (2) Methods: The period of the enrollment was from November 2021 to February 2022. Children with uncomplicated OSA caused by adenotonsillar hypertrophy (ATH) were recruited. Allergy was excluded by skin prick test (SPT), and the determination of serum IgE level using ELISA test. Plasma concentration of 25-hydroxy vitamin D (25-OHD) was quantitatively determined; then, the vitamin D concentration in patients was compared with healthy controls matched for sex, age, ethnicity, and characteristics. (3) Results: Plasma 25-OHD levels were significantly lower in patients than in healthy subjects (mean 17 ng/mL, 6.27 DS, range 6-30.7 ng/mL, vs. mean 22 ng/mL, 9.45 DS, range 7-41.2 ng/ ml; p < 0.0005). The prevalence of children with vitamin D deficiency was significantly higher in the ATH group than controls. The plasma 25-OHD level did not change following the ATH clinical presentation (III or IV grade according to the Brodsky scale), while the different categories of 25-OHD status (insufficiency, deficiency, and adequacy) in the ATH group were statistically significantly different (p < 0.001) from healthy controls. (4) Conclusions: This study identified statistically significant differences between the ATH group and control regarding the plasma concentration of vitamin D; this data, despite not being directly linkable to the lymphoid tissue hypertrophy (p-value not significant), might suggest a negative effect of vitamin D deficit on the immune system.

Changes in the oral and nasal microbiota in pediatric obstructive sleep apnea

Background

Several clinical studies have demonstrated that pediatric obstructive sleep apnea (OSA) is associated with dysbiosis of airway mucosal microbiota. However, how oral and nasal microbial diversity, composition, and structure are altered in pediatric OSA has not been systemically explored.

Methods

30 polysomnography-confirmed OSA patients with adenoid hypertrophy, and 30 controls who did not have adenoid hypertrophy, were enrolled. Swabs from four surface oral tissue sites (tongue base, soft palate, both palatine tonsils, and adenoid) and one nasal swab from both anterior nares were collected. The 16S ribosomal RNA (rRNA) V3-V4 region was sequenced to identify the microbial communities.

Results

The beta diversity and microbial profiles were significantly different between pediatric OSA patients and controls at the five upper airway sites. The abundances of Haemophilus, Fusobacterium, and Porphyromonas were higher at adenoid and tonsils sites of pediatric patients with OSA. Functional analysis revealed that the differential pathway between the pediatric OSA patients and controls involved glycerophospholipids and amino acid metabolism.

Conclusions

In this study, the oral and nasal microbiome of pediatric OSA patients exhibited certain differences in composition compared with the controls. However, the microbiota data could be useful as a reference for studies on the upper airway microbiome.

Characteristics of salivary microbiota in children with obstructive sleep apnea: A prospective study with polysomnography

Objectives

The present study aimed to investigate the characteristics of salivary microbiota of children with obstructive sleep apnea (OSA) and to assess longitudinal alterations in salivary microbiota before and after adenotonsillectomy.

Methods

A set of cross-sectional samples consisted of 36 OSA children (17 boys and 19 girls, 7.47 ± 2.24 years old) and 22 controls (9 boys and 13 girls, 7.55 ± 2.48 years old) were included in the study, among which eight OSA children (five boys and three girls, 8.8 ± 2.0 years old) who underwent treatment of adenotonsillectomy were followed up after 1 year. Saliva samples were collected, and microbial profiles were analyzed by bioinformatics analysis based on 16S rRNA sequencing.

Results

In cross-sectional samples, the OSA group had higher α-diversity as estimated by Chao1, Shannon, Simpson, Pielou_e, and observed species as compared with the control group (p &lt; 0.05). β-Diversity based on the Bray–Curtis dissimilarities (p = 0.004) and Jaccard distances (p = 0.001) revealed a significant separation between the OSA group and control group. Nested cross-validated random forest classifier identified the 10 most important genera (Lactobacillus, Escherichia, Bifidobacterium, Capnocytophaga, Bacteroidetes_[G-7], Parvimonas, Bacteroides, Klebsiella, Lautropia, and Prevotella) that could differentiate OSA children from controls with an area under the curve (AUC) of 0.94. Linear discriminant analysis effect size (LEfSe) analysis revealed a significantly higher abundance of genera such as Prevotella (p = 0.027), Actinomyces (p = 0.015), Bifidobacterium (p &lt; 0.001), Escherichia (p &lt; 0.001), and Lactobacillus (p &lt; 0.001) in the OSA group, among which Prevotella was further corroborated in longitudinal samples. Prevotella sp_HMT_396 was found to be significantly enriched in the OSA group (p = 0.02) with significantly higher levels as OSA severity increased (p = 0.014), and it had a lower abundance in the post-treatment group (p = 0.003) with a decline in each OSA child 1 year after adenotonsillectomy.

Conclusions

A significantly higher microbial diversity and a significant difference in microbial composition and abundance were identified in salivary microbiota of OSA children compared with controls. Meanwhile, some characteristic genera (Prevotella, Actinomyces, Lactobacillus, Escherichia, and Bifidobacterium) were found in OSA children, among which the relationship between Prevotella spp. and OSA is worth further studies.

Characteristics of the bacterial microbiota in the upper respiratory tract of children

PURPOSE

The respiratory tract microbiota are deemed as the gatekeeper to health. Consequently, microbiota dysbiosis can lead to the development of diseases. To identify the exact origins of the localized pathogenic bacteria, we investigated bacterial composition in the upper airway tract.

METHODS

Separate mucosal swabs were collected from nostril or oropharynx of each participant. Meanwhile, the lymphoid tissues including adenoids and tonsils were collected during operation. DNAs were exacted from all the samples for the following 16S rRNA analysis.

RESULTS

At the phylum level, the basic bacterial structures in the adenoids, tonsils, oropharynx, and nostrils were generally similar: five main phyla Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Fusobacteria form the majority of the microbiota. However, across these four sites, the microbiota composition differed. More specifically, the bacterial composition in the nostrils was unique. There, Firmicutes and Actinobacteria were the most abundant phyla, while Bacteroides and Fusobacteria were the least abundant. At the genus level, Staphylococcus, Dolosigranulum, Corynebacterium, and Moraxella were the most plentiful, while Fusobacteria was the least ample. Across all sites, Streptococcus displayed similar abundances. Fusobacteria exhibited higher abundances in the lymphoid tissues and oropharynx. Haemophilus and Neisseria were more plentiful in the tonsils and oropharynx. Notably, Klebsiella, which is normally localized to the gut, was abundant in the adenoids and tonsils.

CONCLUSION

Our data indicate that promising pathogenic bacteria originate from all sites in the upper airway. The upper tract lymphoid tissues, normally considered as immune organs, may also serve as reservoirs for pathogenic bacteria.