Some intestinal bacteria facilitate fatty deposits in the arteries of the heart

2023-07-12 13:48:25

Some bacteria that reside in the intestine can be key in the development of atherosclerotic plaques, which are formed by the accumulation of fat and cholesterol deposits, and which constitute one of the main causes of heart attacks.

The study led by researchers from the Universities of Uppsala and Lund (Sweden) has been published in the magazine «Circulation» and analyzed gut bacteria and cardiac imaging among 8,973 participants aged 50 to 65 years from Uppsala and Malmö without previously known heart disease. They were all participants in the Swedish Cardiopulmonary Bioimaging Study (SCAPIS).

“We have seen that oral bacteria, especially species of the Streptococcus genus, are associated with a greater occurrence of atherosclerotic plaques in the small arteries of the heart when they are present in the intestinal flora. Species of the genus Streptococcus are common causes of pneumonia and infections of the throat, skin, and heart valves. We now need to understand whether these bacteria are contributing to the development of atherosclerosis,” explains Tove Fall, Professor of Molecular Epidemiology at Uppsala University’s Department of Medical Sciences and SciLifeLab, who coordinated the study along with researchers from the Lund University.

Technological advances have enabled large-scale, in-depth characterization of bacterial communities in biological samples by sequencing the DNA content and comparing it to known bacterial sequences. Furthermore, improvements in imaging techniques have enabled the detection and measurement of early changes in the small vessels of the heart.

SCAPIS represents one of the world’s largest collections of these two types of data. In this study, the scientists investigated the links between the gut microbiota and the buildup of fatty deposits in the arteries of the heart.

“The large number of samples with high-quality data from cardiac imaging and gut flora allowed us to identify novel associations. Among our most significant findings, Streptococcus anginosus and S. oralis subsp. oralis were the two strongest,” says Sergi Sayols-Baixeraslead author from Uppsala University.

fat deposits

The research team also found that some of the species linked to the buildup of fatty deposits in the arteries of the heart were linked to levels of the same species in the mouth.

This was assessed using fecal and saliva samples collected from the Malmö Offspring Study and the Malmö Offspring Dental Study.

Furthermore, these bacteria were associated with markers of inflammation in the blood, even after accounting for differences in diet and medication between participants who carried the bacteria and those who did not.

“As soon as we start to understand how the human host and the bacterial community in the different compartments of the body affect each other. Our study shows worse cardiovascular health in carriers of streptococci in the intestine. We now need to investigate whether these bacteria play an important role in the development of atherosclerosis,” says Marju Orho-Melander, one of the study’s lead authors.