CT-1 (Cardiotrophin-1)-Gal-3 (Galectin-3) Axis in Cardiac Fibrosis and Inflammation.

Myocardial fibrosis is a main contributor to the development of heart failure (HF). CT-1 (cardiotrophin-1) and Gal-3 (galectin-3) are increased in HF and associated with myocardial fibrosis. The aim of this study is to analyze whether CT-1 regulates Gal-3. Proteomic analysis revealed that Gal-3 was upregulated by CT-1 in human cardiac fibroblasts in parallel with other profibrotic and proinflammatory markers. CT-1 upregulation of Gal-3 was mediated by ERK (extracellular signal-regulated kinase) 1/2 and Stat-3 (signal transducer and activator of transcription 3) pathways. Male Wistar rats and B6CBAF1 mice treated with CT-1 (20 µg/kg per day) presented higher cardiac Gal-3 levels and myocardial fibrosis. In CT-1-treated rats, direct correlations were found between cardiac CT-1 and Gal-3 levels, as well as between Gal-3 and perivascular fibrosis. Gal-3 genetic disruption in human cardiac fibroblasts and pharmacological Gal-3 inhibition in mice prevented the profibrotic and proinflammatory effects of CT-1. Dahl salt-sensitive hypertensive rats with diastolic dysfunction showed increased cardiac CT-1 and Gal-3 expression together with cardiac fibrosis and inflammation. CT-1 and Gal-3 directly correlated with myocardial fibrosis. In HF patients, myocardial and plasma CT-1 and Gal-3 were increased and directly correlated. In addition, HF patients with high CT-1 and Gal-3 plasma levels presented an increased risk of cardiovascular death. Our data suggest that CT-1 upregulates Gal-3 which, in turn, mediates the proinflammatory and profibrotic myocardial effects of CT-1. The elevation of both molecules in HF patients identifies a subgroup of patients with a higher risk of cardiovascular mortality. The CT-1/Gal-3 axis emerges as a candidate therapeutic target and a potential prognostic biomarker in HF.

Association of cystatin C with heart failure with preserved ejection fraction in elderly hypertensive patients: potential role of altered collagen metabolism.

OBJECTIVES: Cystatin C has been shown to be associated with heart failure with preserved ejection fraction (HFPEF). In addition, myocardial fibrosis has been involved in diastolic dysfunction in HFPEF. Therefore, we hypothesized that increased cystatin C levels may be associated with altered collagen metabolism, contributing to diastolic dysfunction in patients with HFPEF. METHODS: One hundred and forty-one elderly hypertensive patients with HFPEF were included. Cardiac morphology and function was assessed by echocardiography. Circulating levels of cystatin C, biomarkers of collagen type I synthesis (carboxy-terminal propeptide of procollagen type I) and degradation [matrix metalloproteinase-1 (MMP-1) and its inhibitor TIMP-1] and osteopontin were analyzed by ELISA. Twenty elderly sex-matched patients with no identifiable cardiac disease were used as controls. In-vitro studies were performed in human cardiac fibroblasts. RESULTS: Compared with controls, cystatin C was increased (P < 0.001) in patients with HFPEF, even in those with a normal estimated glomerular filtration rate (eGFR; P < 0.05). Cystatin C was directly correlated with the estimated pulmonary capillary wedge pressure (P < 0.01), TIMP-1 and osteopontin (P < 0.001) and inversely correlated with MMP-1:TIMP-1 (P < 0.01), but not with carboxy-terminal propeptide of procollagen type I or MMP-1 in all patients with HFPEF. These associations were independent of eGFR. In vitro, osteopontin (P < 0.01) and TIMP-1 (P < 0.001) increased in the supernatant of cardiac fibroblasts exposed to cystatin C. CONCLUSION: In patients with HFPEF of hypertensive origin, cystatin C is increased and associated with diastolic dysfunction and alterations in collagen metabolism independently of eGFR. An excess of cystatin C might contribute to diastolic dysfunction in HFPEF by facilitating myocardial fibrosis via accumulation of osteopontin and TIMP-1.

Osteopontin-mediated myocardial fibrosis in heart failure: a role for lysyl oxidase?

AIMS: We investigated whether the pro-fibrotic matricellular protein osteopontin (OPN) is associated with the enzymes involved in the extracellular synthesis of fibril-forming collagen type I (i.e. procollagen C-proteinase, PCP) and its cross-linking to form insoluble fibrils (i.e. lysyl oxidase, LOX) in heart failure (HF) of hypertensive origin. METHODS AND RESULTS: OPN, PCP, and LOX were assessed by histochemical and molecular methods in the myocardium of 21 patients with hypertensive heart disease (HHD) and HF. Whereas the myocardial expression of OPN was very scarce in control hearts (n = 10), it was highly expressed in HF patients (P < 0.0001). OPN was directly correlated with LOX (r = 0.460, P = 0.041), insoluble collagen (r = 0.534, P = 0.015), pulmonary capillary wedge pressure (r = 0.558; P = 0.009), and left-ventricular (LV) chamber stiffness (r = 0.458, P = 0.037), and inversely correlated with LV ejection fraction (r = -0.513, P = 0.017) in all patients. OPN did not correlate with PCP and other parameters assessing collagen synthesis by fibroblasts or degradation by matrix metalloproteinases. In vitro studies showed that OPN significantly (P < 0.05) increases the expression and activity of LOX in human cardiac and dermal fibroblasts. CONCLUSION: An excess of OPN is associated with increased LOX and insoluble collagen, as well as with LV stiffness and systolic dysfunction in patients with HHD and HF. In addition, OPN up-regulates LOX in human fibroblasts. It is suggested that the OPN-LOX axis might facilitate the formation of insoluble collagen (i.e. stiff and resistant to degradation) and the subsequent alteration in LV mechanical properties and function in patients with HHD and HF.

Cardiotrophin-1 in hypertensive heart disease.

Hypertensive heart disease, here defined by the presence of pathologic left ventricular hypertrophy in the absence of a cause other than arterial hypertension, is characterized by complex changes in myocardial structure including enhanced cardiomyocyte growth and non-cardiomyocyte alterations that induce the remodeling of the myocardium, and ultimately, deteriorate left ventricular function and facilitate the development of heart failure. It is now accepted that a number of pathological processes mediated by mechanical, neurohormonal, and cytokine routes acting on the cardiomyocyte and the non-cardiomyocyte compartments are responsible for myocardial remodeling in the context of arterial hypertension. For instance, cardiotrophin-1 is a cytokine member of the interleukin-6 superfamily, produced by cardiomyocytes and non-cardiomyocytes in situations of biomechanical stress that once secreted interacts with its receptor, the heterodimer formed by gp130 and gp90 (also known as leukemia inhibitory factor receptor beta), activating different signaling pathways leading to cardiomyocyte hypertrophy, as well as myocardial fibrosis. Beyond its potential mechanistic contribution to the development of hypertensive heart disease, cardiotrophin-1 offers the opportunity for a new translational approach to this condition. In fact, recent evidence suggests that cardiotrophin-1 may serve as both a biomarker of left ventricular hypertrophy and dysfunction in hypertensive patients, and a potential target for therapies aimed to prevent and treat hypertensive heart disease beyond blood pressure control.