Soluble peptide X attenuates post-infarction cardiac remodeling through anti-inflammatory effects
Y Kobayashi, T Aonuma, S Kawaguchi, N Nakagawa, J KawabeAbstract
Background
Gene X was originally identified as an adhesion molecule that mediates peripheral nerve regeneration. Accumulating evidence, including findings from our group, indicates that Gene X participates in multiple biological processes, including angiogenesis and inflammation. Recent studies have demonstrated that the extracellular domain of Protein X can be cleaved and released from inflammatory cells as soluble Peptide X (sPeptide X), which suppresses inflammatory cell activity. However, the expression dynamics of Gene X and the functional role of sPeptide X in the myocardium remain unclear. We examined Gene X expression in the myocardial tissue and evaluated the therapeutic potential of sPeptide X using sustained-release (SR) sPeptide X mimetic peptides in a murine model of myocardial infarction (MI).
Methods
MI was induced in male C57BL/6NJ mice (8–12 weeks old) by permanent ligation of the left anterior descending coronary artery. Gene X expression in CD45-positive immune cells isolated from cardiac tissue was analyzed 3 days post-MI. SR sPeptide X nanoparticles were generated by encapsulating sPeptide X mimetic peptides into poly(lactic-co-glycolic acid) (PLGA) microspheres. sPeptide X or control particles without peptides were locally administered to the anterior myocardial wall at the time of MI induction. Cardiac function was serially assessed by echocardiography. Histological analyses of immune cell infiltration and cardiac fibrosis were performed at 3 and 28 days post-MI, respectively. To investigate anti-inflammatory mechanisms in vitro, murine RAW 264.7 macrophages were stimulated with lipopolysaccharide (LPS), and the effects of sPeptide X on Gene X expression and proinflammatory gene expression were evaluated.
Results
Gene X expression was significantly upregulated in the ischemic myocardium and in isolated immune cells following MI. Echocardiography demonstrated that treatment with sPeptide X particles significantly attenuated adverse cardiac remodeling, as evidenced by reduced left ventricular end-diastolic and end-systolic volumes and improved left ventricular ejection fraction compared with control particles at day 3 post-MI. This beneficial trend persisted through 4 weeks. Histological analyses demonstrated marked reductions in neutrophil and macrophage infiltration on day 3 and decreased myocardial fibrosis at day 28 in the sPeptide X-treated group. In RAW 264.7 cells, LPS stimulation significantly increased Gene X expression and upregulated proinflammatory cytokine. Treatment with sPeptide X significantly suppressed LPS-induced expression of inflammatory mediators.
Conclusion
SR sPeptide X nanoparticles attenuated post-MI adverse cardiac remodeling by suppressing inflammatory cell responses and preserving cardiac function. These findings suggest that sPeptide X is a promising therapeutic strategy for myocardial ischemic injury.picture 1