Fecal microbiota transplantation reduces age-related vascular stiffness in mice with concomitant changes in senescence and oxidative stress markers

Background and Purpose

Vascular stiffness is a hallmark of aging and a major contributor to cardiovascular risk. Aging is accompanied by gut microbiome dysbiosis, which has been linked to hypertension and increased pulse wave velocity (PWV), especially in females. We investigated whether microbiome rejuvenation via fecal microbiota transplantation (FMT) from young donors improves aged-related vascular stiffness in mice in both sexes.

Methods

Aged (18-month-old) female and male C57BL/6 mice received FMT from young (2-month-old) donors by oral gavage twice weekly for four weeks, followed by a four-week engraftment period. Microbial engraftment was assessed by fecal 16S rRNA sequencing of the V3–V4 region. Carotid artery PWV was measured before the first FMT and four weeks after the final transplantation. Aortic tissue was collected for histological analysis, quantitative PCR, and Western blotting.

Results

FMT induced a shift toward a youthful microbiome profile, particularly in females, as demonstrated by proportional abundance analysis showing increased Lactobacillus and Bifidobacterium levels (p<0.05) in transplanted mice compared with aged controls (Figure 1A). Principal component analysis demonstrated clustering of transplanted mice with young controls (Figure 1B).

PWV was significantly elevated in aged mice at baseline (p<0.01) and significantly reduced after FMT (p<0.05) (Figure 1C). Paired analysis pre- and post FMT revealed a more pronounced PWV reduction in transplanted females compared with males, while PWV remained unchanged in aged control mice of both sexes (Figure 1D).

Mechanistically, Masson–Trichrome staining showed increased adventitial collagen deposition in aged controls, with a trend toward reduced collagen in transplanted mice (Figure 2A). Elastin breaks increased with aging and were reduced after FMT; while in females, elastin breaks were significantly reduced after FMT (p<0.01), a similar trend was observed in males (Figure 2B). Protein and mRNA expression of the senescence marker p16 were elevated in aged controls but significantly lower in transplanted mice (p<0.01), reaching levels comparable to young animals (Figure 2C). mRNA expression of superoxide dismutase 1 (SOD1) was significantly reduced in aged controls (p<0.01) and restored to youthful levels following FMT (Figure 2D).

Conclusion

Age-related vascular stiffness is attenuated by fecal microbiota transplantation, with more pronounced effects in females. These effects are associated with reduced vascular senescence and restoration of oxidative stress balance. Ongoing analyses aim to further delineate the contribution of these pathways, focusing also on systemic markers and gut microbiota-derived metabolites.