FGF-16 protects against adverse cardiac remodeling in the infarct diabetic heart

Abstract

Till now, no functional studies for FGF-16 in diabetic heart have been reported. Therefore, this study aims to evaluate the potential function of FGF-16 in inhibiting adverse cardiac remodeling in post myocardial infarction (MI) of diabetic heart. We investigated the role of fibroblast growth factor-16 (FGF-16) in post-MI remodeling and role of cardio-protection in the diabetic infarct heart. Adult db/db diabetic mice were assigned to sham group, MI group and MI+FGF-16 group, respectively. MI group was induced by permanent coronary artery ligation, and the mice were subjected to 2D trans-thoracic echocardiography 2-4 weeks post-surgery. The results showed that the infiltration of monocytes, the associated pro-inflammatory cytokines were significantly increased, and the adverse cardiac remodeling and left ventricular dysfunction were observed in MI group. FGF-16 treatment protected against apoptosis, cardiac dysfunction and chamber dilatation post-MI, and decreased monocyte infiltration and cardiomyocyte hypertrophy/apoptosis. Meanwhile, the FGF-16 treatment also attenuated interstitial fibrosis and myocardial inflammation post-MI, increased M2 macrophage differentiation and associated anti-inflammatory cytokines, reduced adverse remodeling, and improved cardiac function. In conclusion, our results suggest that the heart appears to be a target of systemic and possibly locally generated FGF-16, which plays a therapeutic role in cardiac protection in the post-MI diabetic heart.

Keywords: FGF-16; cardiac remodeling; diabetes; myocardial infarction.

Figure 1

Effect of FGF-16 on infarct size and interstitial fibrotic areas after MI. A. Images for infract size areas and interstitial fibrotic areas (%; n=15); B. Statistical analysis for infarct size and Interstitial fibrotic area (mm²; n=15). P<0.05 represents the infarct size or interstitial fibrotic areas in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents infarct size or interstitial fibrotic area in MI group compared to Sham group. #P<0.05 represents infarct size or interstitial fibrotic area in MI+GFG16 compared to MI group.

Figure 2

Effect of FGF-16 on heart weight/body weight and cardiomyocyte cross-sectional areas after MI. A. Heart weight/ body weight (HW/BW; n=15), B. Cardiomyocyte cross-sectional area (mm²; n=15). P<0.05 represents the heart weight/body weight or cardiomyocyte cross-sectional areas in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents the values in MI group compared to Sham group. #P<0.05 represents values in MI+GFG16 compared to MI group.

Figure 3

Effect of FGF-16 on cardiomyocyte remodelling after MI. A-F. quantification data of mRNA expression of cardiomyocyte genes by real-time RT-PCR (n=15). P<0.05 represents the gene levels in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents the mRNA levels in MI group compared to Sham group. #P<0.05 represents mRNA levels in MI+GFG16 compared to MI group.

Figure 4

Effect of FGF-16 on myocardial inflammation after MI. A-D. Quantification data CD45, F4/80, Mac-2, and IL-6 staining to assess leukocyte and macrophage infiltration from sham, MI, and MI+FGF16 groups (n=15). P<0.05 represents the cell levels in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents the values in MI group compared to Sham group. #P<0.05 represents values in MI+GFG16 compared to MI group.

Figure 5

Quantification analysis of TUNEL assay for apoptosis and immunohistochemical staining showing effect of FGF-16 on NF-B p65, p38 MAPK, and JNK1/2 in post-MI diabetic myocardium. (A) TUNEL staining and statistical analysis for the apoptosis cells. The levels of phosphorylated NF-κB p65 (B), p38 MAPK (C), and JNK1/2 (D) in the MI+FGF16 group are significantly reduced compared to those in the MI group (n=15). P<0.05 represents the cytokine levels in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents the values in MI group compared to Sham group. #P<0.05 represents values in MI+GFG16 compared to MI group.

Figure 6

Effect of FGF-16 on Akt expression in post-MI diabetic myocardium. A. Western blot assay for the phosphorylated Akt expression and the statistical analysis. B. Western blot assay for total Akt expression and the statistical analysis. P<0.05 represents the protein levels in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents the protein expression in MI group compared to Sham group. #P<0.05 represents protein expression in MI+GFG16 compared to MI group.

Figure 7

Effect of FGF-16 on GSK-3β expression in post-MI diabetic myocardium. A. Western blot assay for the phosphorylated GSK-3β expression and the statistical analysis. B. Western blot assay for the total GSK-3β expression and the statistical analysis. P<0.05 represents the protein levels in MI group compared to Sham group or in MI+FGF16 group compared to MI group. *P<0.05 represents the protein expression in MI group compared to Sham group. #P<0.05 represents protein expression in MI+GFG16 compared to MI group.

Figure 8

Exogenous FGF-16 Treatment Improves Cardiac Function in post-MI diabetic myocardium. Quantitative analyses are shown for (A) left ventricularinternal dimension-diastole (LVIDd); (B) left ventricular internal dimension-systole (LVIDs); (C) shortening percentage (%); (D) left ventricular volume at enddiastole (EDV), (E) left ventricular volume at end systole (ESV), and (F) ejection percentage (%). (n=15, P<0.05). *P<0.05 represents the values in MI group compared to Sham group. #P<0.05 represents values in MI+GFG16 compared to MI group.