A milestone study published in the journal Nature Communications is offering the first demonstration of a direct causal relationship between the gut microbiome and a human neurovascular disease. Verifying prior animal studies, the research suggests a microbiome metabolite can travel through the bloodstream, reach blood vessels in the brain and expedite the development of lesions.
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The researchers collected fecal samples from over 100 CA patients and discovered the condition did correlate with a very particular microbiome signature. Levels of three common species particularly distinguished CA patients from a healthy control. Higher than normal levels of Odoribacter splanchnicus were seen in CA patients, alongside lower levels of Faecalibacterium prausnitzii and Bifidobacterium adolescentis.
"The CA patients from all the different collection sites had the same distinctive microbiome, regardless of whether they had inherited the mutation or had a sporadic lesion, and regardless of the number of lesions they had," explains Awad.
Further analysis revealed the specific CA-microbiome signature identified in the human subjects resulted in heightened synthesis of lipopolysaccharide (LPS) molecules. Prior mouse studies have found LPS molecules produced in the gut can travel through the bloodstream into the brain and drive the development of CA lesions.
Sean Polster, first author on the new study, says analyzing microbial populations in tandem with a number of blood-based biomarkers resulted in incredibly accurate diagnoses of CA severity.
"By looking at both bacteria combinations and the blood biomarkers, we were able to measure just how aggressive the disease was in each patient," adds Polster.
