Influence of periostin-positive cell-specific Klf5 deletion on aortic thickening in DOCA-salt hypertensive mice

Abstract

Chronic hypertension causes vascular remodeling that is associated with an increase in periostin- (postn) positive cells, including fibroblasts and smooth muscle cells. Krüppel-like factor (KLF) 5, a transcription factor, is also observed in vascular remodeling; however, it is unknown what role KLF5 plays in postn-positive cells during vascular remodeling induced by deoxycorticosterone-acetate (DOCA) salt. We used postn-positive cell-specific Klf5-deficient mice (Klf5^PostnKO: Klf5^flox/flox; Postn^Cre/-) and wild-type mice (WT: Klf5^flox/flox; Postn^-/-). We implanted a DOCA pellet and provided drinking water containing 0.9% NaCl for 8 weeks. The DOCA-salt treatment induced hypertension in both genotypes, as observed by increases in systolic blood pressure. In WT animals, DOCA-salt treatment increased the aortic medial area compared with the non-treated controls. Similarly, Tgfb1 was overexpressed in the aortas of the DOCA-salt treated WT mice compared with the controls. Immunofluorescence staining revealed that fibroblast-specific protein 1 (FSP1)⁺-α smooth muscle actin (αSMA)⁺ myofibroblasts exist in the medial area of the WT aortas after DOCA-salt intervention. Importantly, these changes were not observed in the Klf5^PostnKO animals. In conclusion, the results of this study suggest that the presence of KLF5 in postn-positive cells contributes to the pathogenesis of aortic thickening induced by DOCA-salt hypertension.

Figure 1

Systolic blood pressure during eight-week DOCA-salt treatment period. Open circle, WT-control mice (n=10); open triangle, Klf5^PostnKO-control mice (n=12); solid circle, WT-DOCA-salt mice (n=11); solid triangle, Klf5^PostnKO-DOCA-salt mice (n=10). Values are mean ± SE. *P < 0.05 vs. WT-Cont. ^†P < 0.05 vs. Klf5^Cre/−-Cont.

Figure 2

Myofibroblasts localize in thickened aortic media after eight-weeks of DOCA-salt treatment. (A) Representative EvG staining of the aorta (×100). Bar, 500 μm. (B) Aortic medial wall area. n = 10 per group. *P < 0.05. (C) mRNA expression of Tgfb1 and Col1a in aorta. n = 5 per group. Values are mean ± SE. *P < 0.05.

Figure 3

DOCA-salt treatment induced myofibroblast transition in aortic media of WT, but not Klf5^PostnKO mice. (A) Representative EvG (Scale, ×400; bar, 100μm) and immunofluorescence staining (Scale, ×600; bar, 50μm) of aorta. Arrows point to CD11b⁺ cells. (B) Immunofluorescence staining of aorta revealed an increased number of αSMA⁺ FSP1⁺ cells in WT-DOCA-salt mice. Scale, ×600; Bar, 50μm. The asterisks indicate the lumen.