A novel protein B2URF3 from Akkermansia muciniphila increased by intermittent fasting alleviates vascular calcification.

Alternate-day intermittent fasting (IF1:1) attenuates vitamin D-induced vascular calcification in mice, while a 5:2 regimen is ineffective.

• The IF1:1 regimen involves alternating fasting and feeding days, while the 5:2 regimen involves two fasting days per week.
• The model used was vitamin D-induced vascular calcification in mice.
• Only IF1:1, not the 5:2 regimen, conferred protection against VC.
• The differential efficacy of the two regimens suggests a threshold or frequency-dependent effect of fasting on vascular protection.

The protective effect of IF1:1 against vascular calcification is gut microbiota-dependent, particularly through enrichment of Akkermansia muciniphila.

• The gut microbiota dependence was demonstrated as part of the mechanistic investigation of IF1:1's protective effects.
• IF1:1 specifically enriched Akkermansia muciniphila (Akk) in the gut microbiota.
• Akk was identified as the particular microbiota member mediating the downstream protective effects.
• This finding establishes a gut-vascular axis linking dietary intervention to vascular pathology.

Akkermansia muciniphila-derived extracellular vesicles (Akk-EVs) are internalized by vascular smooth muscle cells and suppress osteogenic differentiation and calcification.

• Akk-EVs function as nano-scale mediators that bypass spatiotemporal constraints of bacterial survival to facilitate long-distance communication with host cells.
• Internalization of Akk-EVs by vascular smooth muscle cells (VSMCs) was demonstrated in vitro.
• Suppression of osteogenic differentiation and calcification was demonstrated both in vitro and in vivo.
• Microbiota-derived extracellular vesicles were described as providing 'a crucial pathway for downstream mechanistic investigation.'

Proteomic analysis identified B2URF3 as a highly enriched functional protein in both Akk-EVs and Akkermansia muciniphila.

• B2URF3 was identified as a novel protein through proteomic analysis of Akk-EVs and Akk.
• B2URF3 was described as 'highly enriched' in both Akk-EVs and the parent bacterium Akk.
• B2URF3 was functionally characterized as a key mediator of Akk-EVs' anti-calcification effects.
• The identification of B2URF3 represents a novel protein not previously described in the context of vascular calcification.

B2URF3 interacts with Aldehyde Dehydrogenase 1 Family Member B1 (ALDH1B1) to inhibit vascular smooth muscle cell osteogenic transdifferentiation.

• The interaction between B2URF3 and ALDH1B1 was identified as the molecular mechanism underlying the anti-calcification effect.
• ALDH1B1 (Aldehyde Dehydrogenase 1 Family Member B1) was identified as the host cell binding partner for B2URF3.
• The interaction results in inhibition of osteogenic transdifferentiation of VSMCs.
• This protein-protein interaction defines a specific molecular axis linking bacterially-derived EVs to host cell phenotypic change.

Patients with coronary calcification show reduced fecal Akkermansia muciniphila abundance and lower serum B2URF3 levels compared to controls.

• Both reduced fecal Akk abundance and lower serum B2URF3 levels were observed in patients with coronary calcification.
• These clinical observations were described as translational validation of the experimental findings.
• The findings nominate serum B2URF3 as a potential clinical biomarker for coronary calcification.
• The clinical data support the relevance of the gut-vascular axis identified in mouse models to human disease.