Matrix Gla Protein Levels Are Associated With Arterial Stiffness and Incident Heart Failure With Preserved Ejection Fraction

Abstract

Objective: Arterial stiffness is a risk factor for cardiovascular disease, including heart failure with preserved ejection fraction (HFpEF). MGP (matrix Gla protein) is implicated in vascular calcification in animal models, and circulating levels of the uncarboxylated, inactive form of MGP (ucMGP) are associated with cardiovascular disease-related and all-cause mortality in human studies. However, the role of MGP in arterial stiffness is uncertain. Approach and Results: We examined the association of ucMGP levels with vascular calcification, arterial stiffness including carotid-femoral pulse wave velocity (PWV), and incident heart failure in community-dwelling adults from the Framingham Heart Study. To further investigate the link between MGP and arterial stiffness, we compared aortic PWV in age- and sex-matched young (4-month-old) and aged (10-month-old) wild-type and Mgp^+/- mice. Among 7066 adults, we observed significant associations between higher levels of ucMGP and measures of arterial stiffness, including higher PWV and pulse pressure. Longitudinal analyses demonstrated an association between higher ucMGP levels and future increases in systolic blood pressure and incident HFpEF. Aortic PWV was increased in older, but not young, female Mgp^+/- mice compared with wild-type mice, and this augmentation in PWV was associated with increased aortic elastin fiber fragmentation and collagen accumulation.

Conclusions: This translational study demonstrates an association between ucMGP levels and arterial stiffness and future HFpEF in a large observational study, findings that are substantiated by experimental studies showing that mice with Mgp heterozygosity develop arterial stiffness. Taken together, these complementary study designs suggest a potential role of therapeutically targeting MGP in HFpEF.

Keywords: arterial stiffness; biomarker; heart failure; hypertension; mice; pulse wave velocity.

Figure 1:. Arterial stiffness is increased in 10-month-old female Mgp^+/− mice.

(a) No difference was observed in pulse wave velocity (PWV) between female and male wild-type (WT) and Mgp^+/− mice at 4 months of age. (b) 10-month-old female Mgp^+/− mice had increased PWV compared to age-matched WT female mice, but no difference between male Mgp^+/− and WT mice was observed. PWV was higher in 10-month-old female Mgp^+/− mice than their male counterparts. (c) Mgp heterozygosity is associated with a >50% decrease in aortic expression of Mgp mRNA. mRNA expression levels of Mgp were significantly lower in aged Mgp^+/− female and male mice (n=7 in each group) compared to age-matched wild-type mice (n=5 in each group). No difference in aortic Mgp mRNA levels was detected between Mgp^+/− female and male mice. Statistical comparisons were made with a one-way ANOVA with Sidak’s post-hoc testing.

Figure 2:. Mgp heterozygosity is associated with increased medial collagen accumulation and elastin disruption and reduced MGP expression in vascular smooth muscle cells increases collagen I expression.

(a) to (c) show sections of aortas from 10-month-old female wild-type (WT) and Mgp^+/− mice. (a) Verhoeff–Van Gieson (VVG) staining showing disrupted elastin fiber integrity in the aortas of female Mgp^+/− mice compared to wild-type mice. (b) Masson’s Trichrome staining demonstrating increased collagen (blue staining) in the medial layer of aortas from female Mgp^+/− mice compared to wild-type mice (quantification shown in the right panel, Student’s t-test). (c) Aortas isolated from WT and Mgp^+/− mice were stained for F-Actin (green), COL1 (pink), COL3 (gold) and DNA (blue, DAPI). Increased levels of COL1, but not COL3, protein were seen in aortas from female Mgp^+/− mice compared to wild-type mice. (d) Treatment of MOVAS (n=6 biologically independent samples in each group) with siMGP (resulting in >70% knockdown of Mgp mRNA) caused an increase in Runx2, Col1a1, and Col1a2 expression (Student’s t-test). (e) Treatment of human aortic smooth muscle cells (n=6 biologically independent samples in each group) with siMGP (resulting in >90% knockdown of MGP mRNA) increased RUNX2 and COL1A2 mRNA levels (Student’s t test).