# Distinct commensal bacteria in human nasopharyngeal lymphoid tissue associated with localized immunological memory

## TL;DR

This study finds that a specific type of bacteria in the nose and throat is linked to immune memory cells that help fight viruses like SARS-CoV-2.

## Contribution

The study identifies S. aureus complex as a key driver of immune memory in the upper airway through its metabolic effects.

## Key findings

- S. aureus complex is the dominant bacteria in the human nasopharyngeal mucosa.
- Abundance of S. aureus complex correlates with increased TRM and BRM immune cells.
- S. aureus complex influences metabolic pathways linked to immune cell residency.

## Abstract

The nasopharynx (NP) serves as a primary site for localized immune responses that restrict the spread of SARS-CoV-2 to the lower respiratory tract. The microbiome is increasingly recognized as a key modulator of antiviral immunity but whether it shapes immune responses in upper airway remains uncharacterized. Detailed microbial profiles revealed that S. aureus complex abundance was the primary discriminating factor of microbial community in the NP and the enhanced abundance of S. aureus complex correlated with higher frequencies of CD4+, CD8+ tissue-resident memory T (TRM), and BRM cells. The abundance of S. aureus complex was closely associated with distinct metabolic pathways, particularly those involved in nitrogen metabolism (e.g., arginine, ornithine, and proline interconversion) and the mevalonate pathway for carotenoid biosynthesis. These findings suggest that S. aureus complex may foster unique metabolic dynamics in the NP in enhancing the tissue-residency of memory cells and localized immune responses in upper airway.

•S. aureus complex are dominant bacterial species in human NP mucosa•S. aureus complex are the key discriminating factors in NP microbial community•The abundance of S. aureus complex correlates with the frequencies of TRM and BRM•S. aureus complex-induced metabolites regulate the tissue residency of immune cells

S. aureus complex are dominant bacterial species in human NP mucosa

S. aureus complex are the key discriminating factors in NP microbial community

The abundance of S. aureus complex correlates with the frequencies of TRM and BRM

S. aureus complex-induced metabolites regulate the tissue residency of immune cells

Immunology; Microbiology