title: Vitamin-K-Dependent Protection of the Renal Microvasculature: Histopathological Studies in Normal and Diseased Kidneys.
abstract: Vitamin-K-dependent carboxylation of matrix Gla protein (MGP) protects the macrocirculation against calcification. We recently reported in a multiethnic population study that the estimated glomerular filtration rate, a microvascular trait, decreased and the risk of chronic kidney disease increased with higher circulating levels of inactive dephospho-uncarboxylated MGP, a marker of vitamin K deficiency. These findings highlighted the possibility that vitamin K might have a beneficial effect on the renal microcirculation. To substantiate these epidemiological findings, we undertook a pilot study, in which we stained renal tissue samples obtained by biopsy from 2 healthy kidney donors and 4 patients with nephropathy for carboxylated and uncarboxylated MGP and calcium deposits. Three patients had renal calcifications, which were consistently associated with carboxylated and uncarboxylated MGP. Normal renal tissue was devoid of microcalcifications and staining for carboxylated and uncarboxylated MGP. Pending confirmation in a larger study covering a wider range of renal pathologies, these histopathological findings suggest that MGP might inhibit calcification not only in large arteries, as was known before, but in renal tissue as well, thereby highlighting potentially new avenues for promoting renal health, for instance by vitamin K supplementation.
authors.affiliation: Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Fang-Fei
authors.initials: FF
authors.lastname: Wei
authors.affiliation: R &amp; D Group VitaK, Maastricht University, Maastricht, The Netherlands.
authors.forename: Nadja E A
authors.initials: NE
authors.lastname: Drummen
authors.affiliation: Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Thijs
authors.affiliation: Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Lotte
authors.initials: L
authors.lastname: Jacobs
authors.affiliation: R &amp; D Group VitaK, Maastricht University, Maastricht, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Herfs
authors.affiliation: R &amp; D Group VitaK, Maastricht University, Maastricht, The Netherlands.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Van't Hoofd
authors.affiliation: R &amp; D Group VitaK, Maastricht University, Maastricht, The Netherlands.
authors.forename: Cees
authors.initials: C
authors.lastname: Vermeer
authors.affiliation: Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium; R &amp; D Group VitaK, Maastricht University, Maastricht, The Netherlands.
authors.forename: Jan A
authors.initials: JA
authors.lastname: Staessen
keywords: Calcification; Kidney; Matrix Gla protein; Microcirculation; Vitamin K