(P27-028-24) Altering the Gut Microbiome Through Oral Broad-Spectrum Antibiotics Influenced Colon and Liver Long-Chain Menaquinone Levels in Mice

Objectives: Long-chain menaquinones (LCMKs) are vitamin K forms produced by gut bacteria. In young male mice, antibiotic treatment altered LCMK concentrations in cecum and liver. However, the influence of antibiotic treatment on LCMK tissue concentrations in older mice is unknown. We sought to determine the response of tissue LCMK concentrations in older male and female mice to oral antibiotic-induced alterations in the gut microbiome.

Methods: Four-week-old male and female C57BL/6 mice were treated with broad-spectrum antibiotics (ampicillin and neomycin) in drinking water from 4-22 months (ADD), 19-22 months (AND), or no antibiotics (n=15/group, total n=45/sex). LCMKs (for the purpose of this study, MK9-12) were measured in liver, kidney, jejunum, and colon, and quantified by LC-MS and HPLC. LCMK levels were compared by sex and treatment groups by 2-factor ANOVA, followed by Tukey’s HSD for multiple comparisons.

Results: Among the tissues analyzed, LCMKs were detected in liver and colon. Male mice treated with antibiotics in both ADD and AND had higher colon MK9-12 concentrations compare to untreated male controls (all P values ≤0.01). No sex differences were observed in colon LCMK levels. MK10 was the only LCMK identified in liver, and levels were lower in female mice that received antibiotics in both ADD and AND compared to untreated female controls (P=0.003). There was no effect of antibiotic dosing duration on LCMK concentrations in colon or liver in either male or female mice (all P values ≥0.14). Moreover, liver MK10 concentrations were higher in female versus male mice across all treatment groups (P < 0.001).

Conclusions: Manipulation of the intestinal microbiome through oral antibiotic treatment influenced LCMK content in liver and colon regardless of dosing duration. This study expands our understanding of the contribution of bacterially produced LCMKs to regulating tissue vitamin K concentrations. Future studies are needed to determine the mechanisms by which LCMKs are transported from the colon to peripheral tissues.

Funding Sources: Vitamin K Laboratory US Department of Agriculture Agricultural Research Service Cooperative Agreement No. 58-1950-7-707 and R01AR075103