Association of poor vitamin K status with inflammation and gut microbiota in hemodialysis patients: A cross-sectional study.

Vitamin K insufficiency is common in chronic kidney disease (CKD) and may be associated with gut dysbiosis, which decreases the number of vitamin K-producing bacteria. This insufficient status worsens inflammation, leading to vascular calcification and oxidative stress. This study investigates the correlation between vitamin K status and gut microbiota composition, and its association with inflammation in hemodialysis (HD) patients. In this cross-sectional study, patients were grouped based on dephosphorylated-uncarboxylated matrix gla-protein (dp-ucMGP) levels: adequate (≤500 pmol/L) or inadequate (>500 pmol/L) vitamin K status. Plasma cytokines were analyzed using a multiplex assay, and uremic toxins via reverse-phase high-performance liquid chromatography (RP-HPLC). Gut microbiota composition was assessed in a subgroup using fecal DNA extraction and 16S rRNA gene sequencing on the Illumina NovaSeq PE250 platform. Among 107 patients (53 [interquartile range=16] years and 36 [interquartile range=42] months on HD) completed the study, 70 patients (53 years, BMI, 24.2 Kg/m2) exhibited insufficient vitamin K status, and 37 patients presented adequate status (52.5 years, BMI, 25.6 Kg/m2). Patients with inadequate vitamin K status exhibited significantly higher levels of interleukin (IL)-6, IL-1β, granulocyte-macrophage colony-stimulating factor (GM-CSF), and granulocyte colony-stimulating factor (G-CSF) compared to patients with adequate status, reflecting elevated inflammatory marker levels in patients with insufficient vitamin K. Additionally, Bacteroides, a key vitamin K2-producing genus, was decreased in patients with inadequate vitamin K status. Gut dysbiosis is a consequence of CKD, which can result in reduced production of vitamin K and subsequent insufficient status. Additionally, inadequate vitamin K status may contribute to the inflammatory state in patients undergoing HD.