Defining the microbiome of the head and neck: A contemporary review

Microbiota transplantation and administration of live biotherapeutic products for the treatment of dysbiosis-associated diseases

INTRODUCTION

The microbiota composition in humans varies according to the anatomical site and is crucial for maintaining homeostasis and an overall healthy state. Several gastrointestinal, vaginal, respiratory, and skin diseases are associated with dysbiosis. Alternative therapies such as microbiota transplantation can help restore microbiota normal composition and can be implemented to treat clinically relevant diseases.

AREAS COVERED

Current microbiota transplantation therapies conducted in clinical trials were included in this review (after searching on MEDLINE database from years 2017 to 2025) such as fecal microbiota transplantation (FMT) against recurrent Clostridioides difficile infection (rCDI) and vaginal microbiota transplantation (VMT) against bacterial vaginosis. Washed microbiota transplantation (WMT) and live biotherapeutic products (LBPs) were also reviewed.

EXPERT OPINION

In microbiota-based transplantation therapy, selecting optimal donors is a limitation. A stool or a vaginal microbiota bank should be implemented to overcome the time-consuming and expensive process of donor recruitment. Microbiota-based LBPs are also promising treatment alternatives for rCDI and other dysbiosis-associated diseases. Specific LBPs could be engineered out of donor fluids-derived strains to achieve the selection of specific beneficial microorganisms for the treatment of specific dysbiosis-associated diseases. Personalized microbiota-based treatments are promising solutions for dysbiosis-associated diseases, which remains an important necessity in clinical practice.

The Association Between Postoperative Prophylactic Antibiotics and Severe Infections After Cochlear Implantation: A Retrospective Cohort Study

OBJECTIVE

To investigate the association between postoperative antibiotic prophylaxis and the risk of infections leading to implant explantation or hospitalization, with a follow-up of up to 12 years.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary medical institution.

PATIENTS

Adult patients (≥18 yr) receiving cochlear implant surgery between 2010 and 2022.

INTERVENTION

Postoperative oral prophylactic antibiotic treatment for 4 to 10 days.

MAIN OUTCOME MEASURES

The medical records of patients receiving cochlear implants were assessed (n = 927). Two groups were formed: group A, receiving postoperative oral antibiotic treatment (period: 2010-2015) (n = 526), and group B, not receiving postoperative oral antibiotic treatment (period: 2016-2022) (n = 401). The two groups were compared regarding infections leading to hospitalization or explantation, and baseline characteristics.

RESULTS

In total, 28 patients (3.0%) had infections requiring explantation or hospitalization. Of these, 13 were explantations (1.4%). The infection rate in group A was 2.9%, compared with 3.2% in group B, with an odds ratio of 1.2 in group B (p = 0.646). Group B had a 2.2 odds ratio of explantation caused by infection compared with group A (p = 0.179). We observed a significant correlation between severe infections in patients previously having otologic surgery (7.7%, p = 0.011) and in patients with previous issues of chronic otitis (16.7%, p = 0.005).

CONCLUSION

Occurrence of postoperative infection leading to explantation and hospitalization was not significantly associated with the use of postoperative antibiotic prophylaxis. However, infections were higher in patients not receiving antibiotic prophylaxis, despite having a lower risk of postoperative infection.

The Prominence of the Broad-Spectrum Protease inhibitor gene A2ML1 as a potential biomarker in cervical cancer diagnostics using Immunotherapeutic and Multi-Omics approaches

One of the venereal tumors that threaten human life is cervical cancer. A2ML1 is detected in advanced-stage cancer patients and is found to be strongly associated with cervical cancer. A2ML1 was shown to be substantially expressed in cervical cancer in this study, which used data from the TCGA database. Those with high A2ML1 expression had a lower chance of survival than patients with low A2ML1 expression. Both univariate and multivariate Cox regression analyses were utilized to investigate the relationship between clinical variables and overall survival rates. An investigation into the link between A2ML1 and immune infiltration was subsequently conducted. Utilizing the immune cell database, research was conducted to investigate the dispersion of 24 immune cells and their correlation to A2ML1 expression. In addition to this, the favorable correlation between immune cells and A2ML1 was validated using all three immune cell methodologies. The Genomics of Drug Sensitivity in Cancer database was used to confirm the idea that there is a link between A2ML1 expression and the efficacy of chemotherapy or immunotherapy. The findings demonstrated that A2ML1 is a potential biomarker for cervical cancer diagnostics. This biomarker may be used to chaperone immunotherapy, as well as to explain the elucidates of cervical cancer caused by the immunological microenvironment.

Metagenome Analysis of Cholesteatoma-associated Bacteria: A Pilot Study

Introduction

Cholesteatoma usually harbors a poly-microbial infection. As the diversity of bacterial pathogens in the Indian COM is unknown, we set out to identify the bacteria associated with cholesteatoma disease in different patients of North India using targeted metagenomic analysis of the 16 S rRNA gene.

Methods

We recruited 15 patients of cholesteatomatous chronic otitis media (COM), who underwent surgical disease clearance. We divided these patients into four groups based on the four clinic-radiological stages categorized as per the EAONO/JOS joint consensus statement classification. Representative samples were extracted during the surgery and sent for bacterial culture and sensitivity and 16 S rRNA gene metagenomic analysis.

Results

While 12 (80%) of the patients belonged to clinical Stage I/II; one patient had an extracranial complication (stage III) and two patients had an intracranial complication (stage IV). Our detailed bacterial metagenomics analyses showed that while phylum Proteobacteria was most abundant (reads up to ∼ 95%) in specimens from nine patients, phylum Firmicutes was most abundant (up to ∼ 80%) in specimens from four patients. Gamma (γ) Proteobacteria and Epsilon (ε) Proteobacteria were the most abundant class amongst Proteobacteria. Class Tissierellia stood out as the most abundant Firmicutes (40-60%), followed by Clostridia (20%) and Bacilli (10%). There was negligible difference in the bacterial profiles across all four clinical stages.

Conclusion

Cholesteatoma is primarily associated with Proteobacteria and Firmicutes phyla, even in complicated disease. Further studies with a larger sample size are required to validate our findings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-024-04678-9.

Single-cell view into the role of microbiota shaping host immunity in the larynx

Microbiota play a critical role in the development and training of host innate and adaptive immunity. We present the cellular landscape of the upper airway, specifically the larynx, by establishing a reference single-cell atlas, while dissecting the role of microbiota in cell development and function at single-cell resolution. We highlight the larynx's cellular heterogeneity with the identification of 16 cell types and 34 distinct subclusters. Our data demonstrate that commensal microbiota have extensive impact on the laryngeal immune system by regulating cell differentiation, increasing the expression of genes associated with host defense, and altering gene regulatory networks. We uncover macrophages, innate lymphoid cells, and multiple secretory epithelial cells, whose cell proportions and expressions vary with microbial exposure. These cell types play pivotal roles in maintaining laryngeal and upper airway health and provide specific guidance into understanding the mechanism of immune system regulation by microbiota in laryngeal health and disease.

Sinonasal microbiome and inflammatory profiles in fungal ball and chronic rhinosinusitis

OBJECTIVE

Fungal balls (FB) are the main form of non-invasive fungal rhinosinusitis found in immunocompetent hosts. Bacterial coinfection affects clinical symptoms. We investigated the sinonasal microbiome and inflammatory profiles in FB and chronic rhinosinusitis (CRS) patients.

METHODS

Thirty-three participants were prospectively recruited. Nasal swab samples and sinonasal tissues were collected from controls, and FB and CRS patients. DNA extraction and microbiome analysis using V3-V4 region 16S rRNA sequencing were performed. Inflammatory cytokine levels in the sinonasal tissues, blood eosinophil counts, and serum total IgE were measured.

RESULTS

No significant differences were observed in species richness or evenness measures. The phylogenetic tree demonstrated that the FB samples were different from the controls. The sinus bacteria composition differed among the groups. At the phylum level, Firmicutes in FB were significantly depleted compared with those in CRS, while Proteobacteria were more enriched in FB than that in controls and CRS. At the genus level, in FB, Staphylococcus and Corynebacterium were significantly decreased compared to those in the controls. The prevalence of Haemophilus was the highest in FB. Blood eosinophil counts and IL-5 and periostin levels in the sinonasal tissue of the FB group were significantly lower than those in the CRS group.

CONCLUSIONS

FB patients had different microbiome compositions and fewer type 2 inflammatory profiles than CRS patients did. However, whether these findings cause FB or result from bacterial and/or fungal infection remains unclear. Further studies are needed to reveal how these differences occur and affect the development of FB and clinical symptoms.

Experimental Modeling of Host-Bacterial Interactions in Head and Neck Squamous Cell Carcinoma

The microscopic species colonizing the human body, collectively referred to as the microbiome, play a crucial role in the maintenance of tissue homeostasis, immunity, and the development of disease. There is evidence to suggest associations between alterations in the microbiome and the development of head and neck squamous cell carcinomas (HNSCC). The use of two-dimensional (2D) modeling systems has made significant strides in uncovering the role of microbes in carcinogenesis; however, direct mechanistic links remain in their infancy. Patient-derived three-dimensional (3D) HNSCC organoid and organotypic models have recently been described. Compared to 2D models, 3D organoid culture systems effectively capture the genetic and epigenetic features of parent tissue in a patient-specific manner and may offer a more nuanced understanding of the role of host-microbe responses in carcinogenesis. This review provides a topical literature review assessing the current state of the field investigating the role of the microbiome in HNSCC; including in vivo and in vitro modeling methods that may be used to characterize microbiome-epithelial interactions.