# P-651. The Culture Supernatant of Prevotella intermedia Caused the Ciliary Dysfunction and Delayed Clearance of S. anginosus in Vivo

## TL;DR

This study shows that the culture supernatant of Prevotella intermedia impairs ciliary function in mice, leading to delayed clearance of Streptococcus anginosus and worsened pneumonia.

## Contribution

The study demonstrates that P. intermedia supernatant causes ciliary dysfunction and delays bacterial clearance in vivo.

## Key findings

- P. intermedia supernatant significantly reduced ciliary beat amplitude in mice trachea.
- S. anginosus infection combined with P. intermedia supernatant increased bacterial load in mice lungs.
- Genes related to ciliary function were downregulated by P. intermedia supernatant.

## Abstract

Several clinical studies have revealed that poor oral hygiene, contaminated with Prevotella intermedia, is associated with the incidence and severity of pneumonia in older adults. Using a mouse model, we previously demonstrated that oropharyngeal challenge with Streptococcus anginosus and the culture supernatants of P. intermedia (P. int. sup.) exacerbated pneumonia severity compared to mono-infection with S. anginosus. Furthermore, unbiased bulk RNA sequencing with pathway analysis revealed that P. int. sup.downregulated multiple mRNA expressions related to cilium movement.

Female C57BL/6J mice aged 10-12 weeks were oropharyngeally inoculated of P. int. sup. or control medium. Mice were euthanized 36 hours post-infection, and the trachea ciliary movements, including ciliary beat frequency (CBF), ciliary beat amplitude (CBA), and ciliary beat coordination (CBC), were observed using microscopy with a high-speed camera. Also, in the same procedure, we assessed the ciliary movement under the challenge of S. anginosus along with P. int. sup or control medium. At least two blinded observers assessed these analytes, averaging five points per sample under blinded conditions. The number of bacteria in the mice's lungs was recorded 36 hours post-infection. Moreover, mice were euthanized 24 hours post-infection using the same model, and real-time RT-PCR assessed the gene expression.

Under conditions without S. anginosus infection, CBA was significantly decreased in the P. int. sup. group compared with the control medium group (p < 0.05). The CBC and CBF showed no significant difference. Under conditions with S. anginosus infection, the CBA and CBC were decreased in the P. int. sup. group (p < 0.05). The CBF exhibited no significant difference. The number of bacteria in the mice’s lungs was significantly increased in the P. int. sup. group (p < 0.05) . Genes related to ciliary function, such as Drc3, Hydin, and Dnah11, were significantly downregulated in the P. int. sup. group (p < 0.05 for each) .

P. int. sup. dysregulated ciliary movement in the mice trachea, with further worsening observed under S. anginosus infection. Collectively, P. int. sup. delayed the ciliary clearance of S. anginosus.

All Authors: No reported disclosures