key: cord-0696917-669xtcbr
authors: Demirci, Mehmet
title: Could Neisseria in oral microbiota modulate the inflammatory response of COVID‐19?
date: 2021-11-30
journal: Oral Dis
DOI: 10.1111/odi.14082
sha: dc0b37e466db480938263cf70967403097ec11b7
doc_id: 696917
cord_uid: 669xtcbr

nan

To the Editor,

The coronavirus 2019 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is ongoing. Despite the 2 years of addressing infections caused by this virus, the immunopathogenesis mechanism is still not clearly understood (Bortolotti et al., 2021) . Interactions between the innate immune system and oral microbiota can alter the host's balance between disease and health (Yu et al., 2019) . It is known that the dominant genera in the oral microbiota and the lung microbiota are quite similar, but more diversity in the oral microbiota is found. The oral microbiota migrates more to the lungs, and cytokines associated with oral microbiota may affect the respiratory tissues (Bao et al., 2020) . After searching Pubmed on October 1, 2021 using the keywords "Oral microbiota" and "COVID-19", 62 articles were found, but only four of them investigated the effects of COVID-19 on the oral microbiota using nextgeneration sequencing (NGS). Two-hundred thirty-seven healthy controls and 181 COVID-19 patients included in these articles were analyzed at the genus level (Iebba et al., 2021; Ma et al., 2021; Ren et al., 2021; Wu et al., 2021) . Regardless of age differences, three studies, except for Ren et al. (2021) , reported that Neisseria genus shows a decrease in the oral microbiota of COVID-19 patients compared with healthy controls (Iebba et al., 2021; Ma et al., 2021; Wu et al., 2021) . Wu et al. (2021) reported that oral microbiota disruption after infection with SARS-COV-2 was attributed to Neisseria, and this decrease also was shown to cause suppression of important metabolic pathways, such as the host tricarboxylic acid cycle (TCA) . Figure 1 shows a comparison of some important genera in the oral microbiota that were found in COVID-19 patients versus healthy controls. Although Ren et al. (2021) reported that the Neisseria genus was elevated in the oral microbiota of COVID-19, they also reported white blood cell and lymphocyte counts positively correlated with Neisseria genus (Ren et al., 2021) . It is known that a decrease in oral microbiota in terms of Neisseria genus in studies on influenza virus occurs (Bao et al., 2020) . Recently, de Castilhos et al.

reported that low abundance of Neisseria (especially N. subflava) led to an increase in the risk of mortality from COVID-19, but they also F I G U R E 1 Oral Microbiota change in COVID-19 patients (log fold)

Oral microbiome and SARS-CoV-2: Beware of lung co-infection

TLR3 and TLR7 RNA sensor activation during SARS-CoV-2 infection. Microorganisms

Severe dysbiosis and specific Haemophilus and Neisseria signatures as hallmarks of the oropharyngeal microbiome in critically ill COVID-19 patients

The nonpathogenic commensal Neisseria: Friends and foes in infectious disease

Profiling of Oral microbiota and cytokines in COVID-19 patients

Metagenomic analysis reveals oropharyngeal microbiota alterations in patients with COVID-19

The commensal Neisseria musculi modulates host innate immunity to promote oral colonization

Alterations in the human oral and gut microbiomes and lipidomics in COVID-19

Altered oral and gut microbiota and its association with SARS-CoV-2 viral load in COVID-19 patients during hospitalization

Innate immunity and oral microbiome: a personalized, predictive, and preventive approach to the management of oral diseases