The role of the gut mycobiome in atherosclerosis
Although it may seem hazardous to try to find a connection between gut mycobiota and atherosclerosis – the primary cause of cardiovascular morbidity and mortality in the world –, a team of researchers attempted to determine its role in carotid atherosclerosis.
A group of Spanish researchers hypothesized that the mycobiota could be involved in the formation of atheromatous plaques. They based their assumption on a recent preliminary study which suggests that the fungal microbiota has a role in the onset of metabolic disorders. While in the past few years many studies focused on the bacterial component (99% of the microbiota), these researchers assumed that the fungal component (0.03% to 2% of the microbiota) could also interact with the environment at previously unsuspected levels.
A study based on the cardiovascular risk
The study population included 33 adult obese or non-obese women. For each of them, the risk of developing a cardiovascular disease was determined based on the Framingham risk score and the carotid intima-media thickness (cIMT), measured by ultrasound. The composition of the fungal microbiota was identified by sequencing the ITS region, and the relative abundance (RA) of the different fungal groups (phylum, family, species) was correlated to the different parameters of cardiovascular risk.
Key species were found
Several significant correlations were identified. The phylum Basidiomycota was, for instance, correlated to a higher cardiovascular risk and associated to several risk factors (high BMI, high levels of LDL and hypertriglyceridemia). On the contrary, the RA of the phylum Zygomycota was associated to a positive HDL/LDL ratio as well as to a lower cIMT, similarly to the family Aspergillaceae, which was additionally associated to lower triglyceride levels.
The fungal community belonging to the phylum Zygomycota, the family Mucoraceae and the genus Mucor showed the most consistent inverse correlation to a high cardiovascular risk. In particular, M. racemosus was the most abundant species found in subjects with a low cardiovascular risk profile. There was a particularly surprising result: a very strong association between the relative abundance of the genus Mucor and cIMT. Obese subjects whose fungal microbiota did not include fungi belonging to the genus Mucor spp. had a significantly increased cIMT compared to non-obese subjects. In all cases, the presence of species of the genus Mucor spp. was associated to a low cardiovascular risk, suggesting that these species provide cardiovascular protection, independently of obesity.
Mucor racemosus: a promising lead?
Until recently, studies on the mycobiota had been focused on its correlation with IBS or obesity, among others. However, it seems that it could also play a role in the prevention of cardiovascular diseases. This could be confirmed by future works studying M. racemosus as a probiotic in animal models since this study already indicated it has a positive effect in reducing the risk of cardiovascular disease.
Chacon MR et al. The gut mycobiome composition is linked to carotid atherosclerosis. Benef Microbes. 2017 Nov 10:1-14. doi: 10.3920/BM2017.0029