UPSALA UNIVERSITY
In a major Swedish study, researchers discovered a link between levels of certain bacteria living in the gut and coronary atherosclerotic plaques. These atherosclerotic plaques, which are formed by the accumulation of fat and cholesterol deposits, are one of the main causes of heart attacks. The study was led by researchers from Uppsala and Lund Universities and the findings have been published in the scientific journal Circulation .
The new study was based on analyzes of gut bacteria and cardiac imaging among 8,973 participants aged 50 to 65 from Uppsala and Malmö with no previously known heart disease. All were participants in the Swedish Cardiopulmonary Bioimaging Study (SCAPIS).
“We found that oral bacteria , especially species of the genus Streptococcus , are associated with an increased 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. “Now we need to understand whether these bacteria are contributing to the development of atherosclerosis,” says Tove Fall, professor of molecular epidemiology at the Department of Medical Sciences and SciLifeLab at Uppsala University, who coordinated the study together with researchers from Lund University.
Technological advances have enabled large-scale in-depth characterization of bacterial communities in biological samples by sequencing DNA content and comparing it to known bacterial sequences. Additionally, improvements in imaging techniques have allowed the detection and measurement of early changes in the small vessels of the heart. The SCAPIS study represents one of the world’s largest collections of these two types of data. In this study, scientists investigated the links between the gut microbiota and the accumulation of fatty deposits in the arteries of the heart.
“The large number of samples with high-quality cardiac imaging and gut flora data 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-Baixeras, lead author from Uppsala University.
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 measured using fecal and saliva samples collected from the Malmö Offspring Study and the Malmö Offspring Dental Study. Additionally, 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.
“We are just beginning to understand how the human host and the bacterial community in different compartments of the body affect each other. Our study shows worse cardiovascular health in carriers of streptococcus in the intestine. “Now we need to investigate whether these bacteria play an important role in the development of atherosclerosis,” says Marju Orho-Melander, professor of genetic epidemiology at Lund University and one of the lead authors of the study.
Reference : Sergi Sayols-Baixeras et al.; Streptococcus species abundance in the gut is linked to subclinical coronary atherosclerosis in 8973 participants from the SCAPIS cohort. Circulation. 2023. DOI: 10.1161/CIRCULATIONAHA.123.063914 [Online ahead-of-print], the link will be: https://www.ahajournals.org.doi/10.1161/CIRCULATIONAHA.123.063914
