Anti-inflammatory Effects and Mechanisms of Vitamin K and Related Molecules

Abstract

Vitamin K contributes to blood coagulation and bone homeostasis through post-translational modification (γ-carboxylation of glutamate) of vitamin K-dependent proteins. Vitamin K is distributed not only in the liver and bones but also in the brain and testis, where γ-carboxylation activity is low, but its role in these organs has not been well studied. Genome-wide gene expression analysis and subsequent studies have shown that vitamin K exerts anti-inflammatory effects by suppressing activation of the nuclear factor kappa B (NFκB) pathway. In addition, geranylgeraniol (GGOH), a side chain moiety of menaquinone-4, a type of vitamin K₂, also shows anti-inflammatory effects by suppressing the activation of interleukin-1 receptor-associated kinase 1 (IRAK1) in the NFκB signaling pathway. Additionally, vitamin K may suppress any reduction of testicular testosterone production through suppression of NFκB, which is activated during inflammation, and vitamin K and GGOH may also suppress inflammation in brain microglial cells.