Plasma osteopontin levels, but not its myocardial expression, reflect heart failure severity in recently diagnosed dilated cardiomyopathy

Expression of Osteopontin and Gremlin 1 Proteins in Cardiomyocytes in Ischemic Heart Failure

A relevant role of osteopontin (OPN) and gremlin 1 (Grem1) in regulating cardiac tissue remodeling and formation of heart failure (HF) are documented, with the changes of OPN and Grem1 levels in blood plasma due to acute ischemia, ischemic heart disease-induced advanced HF or dilatative cardiomyopathy being the primary focus in most of these studies. However, knowledge on the early OPN and Grem1 proteins expression changes within cardiomyocytes during remodeling due to chronic ischemia remains insufficient. The aim of this study was to determine the OPN and Grem1 proteins expression changes in human cardiomyocytes at different stages of ischemic HF. A semi-quantitative immunohistochemical analysis was performed in 105 myocardial tissue samples obtained from the left cardiac ventricles. Increased OPN immunostaining intensity was already detected in the stage A HF group, compared to the control group (p < 0.001), and continued to increase in the stage B HF (p < 0.001), achieving the peak of immunostaining in the stages C/D HF group (p < 0.001). Similar data of Grem1 immunostaining intensity changes in cardiomyocytes were documented. Significantly positive correlations were detected between OPN, Grem1 expression in cardiomyocytes and their diameter as well as the length, in addition to positive correlation between OPN and Grem1 expression changes within cardiomyocytes. These novel findings suggest that OPN and Grem1 contribute significantly to reorganization of cellular geometry from the earliest stage of cardiomyocyte remodeling, providing new insights into the ischemic HF pathogenesis.

The clinical significance of osteopontin on the cardiovascular outcomes in patients with stable coronary artery disease

BACKGROUND

Osteopontin (OPN) is a noncollagenous matricellular protein which is mainly present in bone matrix. A high OPN level has been associated with heart failure and acute coronary syndrome, however data on patients with chronic coronary syndrome (CCS) are lacking. The present study aimed to evaluate the association between OPN and the prognosis of Taiwanese patients with CCS.

METHODS

We enrolled participants from the Biosignature Registry, a nationwide prospective cohort study conducted at nine different medical centers throughout Taiwan. The inclusion criteria were participants who had received successful percutaneous coronary intervention at least once previously, and stable under medical therapy for at least 1 month before enrollment. They were followed for at least 72 months. Logistic regression and Cox proportional hazard model were used to investigate the association between OPN and clinical outcomes. The outcomes of this study were the first occurrence of hard cardiovascular events and composite cardiovascular outcomes including cardiovascular mortality, revascularization, hospitalization for acute myocardial infarction (AMI) or heart failure.

RESULTS

A total of 666 patients with both hs-CRP and osteopontin measurements were enrolled and followed for 72 months. OPN was correlated positively with AMI-related hospitalization, where the highest tertile (Tertile 3) of baseline OPN had the highest risk of AMI-related hospitalization, which remained significant after multivariate adjustments (HR 3.20, p = 0.017). In contrast, combining OPN and hs-CRP did not improve the prediction of CV outcomes.

CONCLUSION

OPN may be a potentially valuable biomarker in predicting CV outcomes. During 6 years of follow-up period, an OPN level >4810 pg/ml was associated with a significantly higher incidence of AMI-related hospitalization in CCS patients who received successful PCI before the enrollment.

Clinical and Molecular Implications of Osteopontin in Heart Failure

The matricellular protein osteopontin modulates cell-matrix interactions during tissue injury and healing. A complex multidomain structure of osteopontin enables it not only to bind diverse cell receptors but also to interact with various partners, including other extracellular matrix proteins, cytokines, and growth factors. Numerous studies have implicated osteopontin in the development and progression of myocardial remodeling in diverse cardiac diseases. Osteopontin influences myocardial remodeling by regulating extracellular matrix production, the activity of matrix metalloproteinases and various growth factors, inflammatory cell recruitment, myofibroblast differentiation, cardiomyocyte apoptosis, and myocardial vascularization. The exploitation of osteopontin loss- and gain-of-function approaches in rodent models provided an opportunity for assessment of the cell- and disease-specific contribution of osteopontin to myocardial remodeling. In this review, we summarize the recent knowledge on osteopontin regulation and its impact on various cardiac diseases, as well as delineate complex disease- and cell-specific roles of osteopontin in cardiac pathologies. We also discuss the current progress of therapeutics targeting osteopontin that may facilitate the development of a novel strategy for heart failure treatment.