Oral Pathobionts Aggravate Myocardial Infarction Through Mobilization of B2 Cells

Myocardial infarction (MI) is a high-prevalence disease that threatens human survival and quality of life worldwide. Considerable evidence has suggested that periodontitis (PD) is detrimental to MI. However, the direct impact of PD on MI is unclear; which oral pathobionts contribute to and how microbial signals regulate the pathogenesis of MI remain obscure.

The effect of PD on MI was assessed in a mouse model that combined ligature-induced PD with MI. Ectopic accumulation of oral pathobionts in infarcted hearts was identified by bacterial sequencing and fluorescence in situ hybridization. Oral pathobionts-reactive B2 cells detrimental for MI were determined by flow cytometry and verified in gnotobiotic mice. Several mouse strains, including CD45.1, Kaede, and knockout strains for Ighm, Rag1, C-X-C motif chemokine ligand 13, S1pr, interleukin-6, and tumor necrosis factor-α, were used for mechanistical exploration. Mutant strains of Fusobacterium nucleatum and Porphyromonas gingivalis deficient in adhesion proteins were generated to investigate bacterial mechanism involved in MI exacerbation. Patients with MI with or without PD were recruited to test the deteriorating impact of PD on MI and the association between oral pathobionts and cardiac function.

Ligature-induced PD and subgingival plaques of patients with PD exacerbated MI in mice by oral pathobionts. Prevotella intermedia, Fusobacterium nucleatum, Selenomonas sputigena, Porphyromonas gingivalis, and Bacteroides plebeius expanded in the oral cavity and ectopically accumulated in the infarcted hearts through impairment of epithelial and endothelial cell barriers. These oral pathobionts mobilized B cells, particularly B2 cells that produced interleukin-6 and tumor necrosis factor-α, to aggravate MI. Mechanistically, oral pathobiont-promoted B cells egress from cervical lymph nodes by a sphingosine-1-phosphate-sphingosine-1-phosphate receptor axis and infiltrate infarcted hearts by a C-X-C motif chemokine ligand 13-C-X-C motif chemokine receptor 5 axis.

Oral pathobionts and proinflammatory B2 cells significantly exacerbate MI, supporting the oral-heart axis as a novel pathogenic pathway. Interventions targeting PD, oral pathobionts, or related immunological mechanisms may improve the therapy of MI.