Table 1.
Descriptive statistics of animals.
Figure 1.
Left ventricular SgII gene expression in heart failure.
A, SgII mRNA levels in non-infarcted left ventricular tissue during HF development. SgII mRNA levels were 10.5 fold increased (p<0.001) in non-infarcted LV tissue in HF animals (n = 9) compared to sham-operated animals (n = 8). Gene expression was measured by RT-qPCR and is presented as fold change ± SEM. B, LV SgII mRNA levels were closely correlated with CgA mRNA levels in both HF (r = 0.68, p = 0.04) and sham animals (r = 0.81, p = 0.02). **p<0.001.
Figure 2.
SgII is produced by cardiomyocytes and increased in the left ventricle during HF development.
A, SgII protein levels as measured by RIA were increased in both the non-infarcted and infarcted region of the LV in HF animals compared to levels in the myocardium of sham-operated animals (n = 9 for both groups). B, Representative photomicrographs of myocardial tissue sections of a HF mouse demonstrating SgII immunoreactivity (brown staining) in cardiomyocytes of the non-infarcted LV (upper left image). Images of the area bordering the infarcted zone (border zone) are presented in the upper right image (magnification: ×100) and the lower left image (magnification: ×400) and demonstrate SgII immunoreactivity also in non-cardiomyocyte cardiac cells, including fibroblasts. In the upper right image, the infarct area is seen on the left side with granulation tissue in between non-infarcted tissue in the center. Bottom right picture demonstrates very weak staining after use of non-immune rabbit serum as control (ctr). Magnification: ×100 except lower left image (×400). C, SgII mRNA levels were measured in fractions of cardiomyocytes (n = 5), endothelial cells (n = 2), and non-cardiomyocytes, non-endothelial cells (n = 5) extracted from LV tissue. Gene expression was measured by RT-qPCR and is presented as fold change ± SEM vs. levels in the cardiomyocyte fraction. **p<0.001, *p<0.01.
Figure 3.
SgII processing is increased in the myocardium of HF mice.
A, Figure of SgII processing as reported in non-cardiac tissue (modified from ref. 18). B, SgII processing in myocardial tissue, pulmonary tissue, and tissue from the stomach. Bands at 81, 66, 55, and 32-30 kDa were measured and are presented as fold change (SEM) vs. sham animals (n = 6 for each group). C, Levels of the proteases PC1/3 and PC2 in HF and sham animals.
Figure 4.
SgII production outside of the left ventricle in heart failure.
SgII levels were decreased in pulmonary tissue during HF development, while levels were unchanged in the other tissues examined. SgII levels in the (A) right ventricle, (B) pulmonary tissue, (C) liver, (D) spleen, (E) kidney, (F) stomach, (G) colon, and (H) skeletal muscle were measured by RIA and are presented as fold change ± SEM (n = 6 for both groups, except pulmonary tissue: HF: n = 14, sham: n = 13). # p<0.05.
Figure 5.
Regulation of cardiomyocyte SgII expression by important hormonal and paracrine factors in HF.
SgII mRNA levels were measured by RT-qPCR after stimulating neonatal rat cardiomyocytes for 24 h with either PBS (Ctr, n = 9), forskolin (FSK n = 5), norepinephrine (NE, n = 5), angiotensin II (AngII, n = 4), endothelin-1 (ET-1, n = 5), transforming growth factor-β (TGF-β, n = 6), or tumor necrosis factor-α (TNF-α, n = 6). SgII mRNA levels are presented as fold change ± SEM vs. PBS-stimulated cells. **p<0.001, *p<0.01, # p<0.05.
Figure 6.
The secretogranin II fragment secretoneurin has protective effects during myocardial ischemia and cardiomyocyte stress.
A, Secretoneurin (SN) perfusion reduces infarct size by 30% (upper left) as demonstrated in representative TTC stained images (upper right) after global ischemia in the isolated perfused rat heart. B, Secretoneurin perfusion also improves myocardial function as assessed by LV end-diastolic pressure (LVEDP) after I/R injury. C, Cardiomyocyte apoptosis in vitro after H2O2 exposure was attenuated by secretoneurin stimulation. Cells were extracted from 5 different cell isolations (n = 5 for all groups). D, Short-term stimulation of cardiomyocytes with 10 µg/mL secretoneurin activated protective intracellular pathways as reflected by increased Stat3 and Erk1/2 phosphorylation (n = 5 for all groups). **p<0.001, *p<0.01, # p<0.05.
Table 2.
Descriptive statistics of heart failure patients and control subjects.
Figure 7.
Circulating SgII levels are elevated in patients with chronic, stable HF.
SgII levels were significantly increased in HF patients (n = 58) compared to healthy age- and gender-matched control subjects (n = 20): Median 0.16 (Q1–3 0.14–0.18) vs. 0.12 (0.10–0.14) nmol/L, p<0.001. HF patients are presented according to NYHA functional class. The horizontal line within the box represents the median level, the boundaries of the box the 25th and 75th percentile levels, and the whiskers the 10th–90th percentile. **p<0.001.