Periodontitis Salivary Microbiota Aggravates Ischemic Stroke Through IL-17A

Area of Science:

• Microbiology
• Immunology
• Neurology

Background:

• Epidemiological studies link periodontitis to ischemic stroke, but mechanisms remain unclear.
• Gut microbiota alterations impact ischemic stroke outcomes.
• Periodontitis involves oral bacteria translocation to the gut.

Purpose of the Study:

• To investigate the role of periodontitis-associated salivary microbiota in ischemic stroke pathogenesis.
• To determine if periodontitis microbiota exacerbates stroke by influencing the gut immune system.

Main Methods:

• Mice were gavaged with periodontitis salivary microbiota.
• Neuroinflammation, immune cell infiltration, and cytokine expression were assessed in the brain.
• Gut immune responses, including Th17 and γδ T cell populations, were analyzed.
• Immune cell migration from gut to brain was tracked using Kaede transgenic mice.
• The effect of IL-17A knockout on stroke outcomes was evaluated.

Main Results:

• Mice receiving periodontitis microbiota showed worse stroke outcomes and increased neuroinflammation.
• Elevated Th17 and IL-17A+ γδ T cells were found in the ileum.
• CD4+ T cells and γδ T cells migrated from the ileum to the brain post-stroke.
• Stroke severity was reduced in IL-17A knockout mice.

Conclusions:

• Periodontitis salivary microbiota aggravates ischemic stroke by inducing gut inflammation and neuroinflammation.
• Increased IL-17A-producing immune cells in the gut, potentially migrating to the brain, mediate this effect.
• This study reveals a gut-mediated mechanism linking periodontitis to worse ischemic stroke outcomes.