Implication of plasma intermedin levels in patients who underwent first-time diagnostic coronary angiography: a single centre, cross-sectional study

Intermedin 1-53 Inhibits Myocardial Fibrosis in Rats by Down-Regulating Transforming Growth Factor-β

BACKGROUND Myocardial fibrosis is the result of persistent anoxia and ischemic myocardial fibers caused by coronary atherosclerotic stenosis, which lead to heart failure, threatening the patient's life. This study aimed to explore the regulatory role of intermedin 1-53 (IMD1-53) in cardiac fibrosis using neonatal rat cardiac fibroblasts and a myocardial infarction (MI) rat model both in vitro and in vivo. MATERIAL AND METHODS The Western blot method was used to detect the protein expression of collagen I and collagen III in myocardial fibroblasts. The SYBR Green I real-time quantitative polymerase chain reaction (PCR) assay was used to detect the mRNA expression of collagen type I and III, IMD1-53 calcitonin receptor-like receptor (CRLR), transforming growth factor-β (TGF-β), and matrix metalloproteinase-2 (MMP-2). Masson staining was used to detect the area changes of myocardial fibrosis in MI rats. RESULTS Results in vivo showed that IMD1-53 reduced the scar area on the heart of MI rats and inhibited the expression of collagen type I and III both in mRNA and protein. Results of an in vitro study showed that IMD1-53 inhibited the transformation of cardiomyocytes into myofibroblasts caused by angiotensin II (Ang II). The further mechanism study showed that IMD1-53 inhibited the expression of TGF-β and the phosphorylation of smad3, which further up-regulated the expression of MMP-2. CONCLUSIONS IMD1-53 is an effective anti-fibrosis hormone that inhibits cardiac fibrosis formation after MI by down-regulating the expression of TGF-β and the phosphorylation of smad3, blocking fibrous signal pathways, and up-regulating the expression of MMP-2, thereby demonstrating its role in regression of myocardial fibrosis.

Plasma levels of intermedin (adrenomedullin-2) in healthy human volunteers and patients with heart failure

Intermedin/adrenomedullin-2 (IMD) is a member of the adrenomedullin/CGRP peptide family. Less is known about the distribution of IMD than for other family members within the mammalian cardiovascular system, particularly in humans. The aim was to evaluate plasma IMD levels in healthy subjects and patients with chronic heart failure. IMD and its precursor fragments, preproIMD(25-56) and preproIMD(57-92), were measured by radioimmunoassay in 75 healthy subjects and levels of IMD were also compared to those of adrenomedullin (AM) and mid-region proadrenomedullin(45-92) (MRproAM(45-92)) in 19 patients with systolic heart failure (LVEF<45%). In healthy subjects, plasma levels (mean+SE) of IMD (6.3+0.6 pg ml(-1)) were lower than, but correlated with those of AM (25.8+1.8 pg ml(-1); r=0.49, p<0.001). Plasma preproIMD(25-56) (39.6+3.1 pg ml(-1)), preproIMD(57-92) (25.9+3.8 pg ml(-1)) and MRproAM(45-92) (200.2+6.7 pg ml(-1)) were greater than their respective bioactive peptides. IMD levels correlated positively with BMI but not age, and were elevated in heart failure (9.8+1.3 pg ml(-1), p<0.05), similarly to MRproAM(45-92) (329.5+41.9 pg ml(-1), p<0.001) and AM (56.8+10.9 pg ml(-1), p<0.01). IMD levels were greater in heart failure patients with concomitant renal impairment (11.3+1.8 pg ml(-1)) than those without (6.5+1.0 pg ml(-1); p<0.05). IMD and AM were greater in patients receiving submaximal compared with maximal heart failure drug therapy and were decreased after 6 months of cardiac resynchronization therapy. In conclusion, IMD is present in the plasma of healthy subjects less abundantly than AM, but is similarly correlated weakly with BMI. IMD levels are elevated in heart failure, especially with concomitant renal impairment, and tend to be reduced by high intensity drug or pacing therapy.