Cell Migration Inducing Protein (CEMIP)-deficiency promotes adverse cardiac remodeling post ischemia and reperfusion injury in mice

R. Schneckmann (Düsseldorf)¹, V. Darakchieva (Düsseldorf)², M. Balan (Düsseldorf)³, T. Hube (Düsseldorf)⁴, K. Bottermann (Düsseldorf)⁵, S. Gorreßen (Düsseldorf)⁵, J. W. Fischer (Düsseldorf)^1
1Universitätsklinikum Düsseldorf Institut für Pharmakologie und Klinische Pharmakologie Düsseldorf, Deutschland; ² Universitätsklinikum Düsseldorf, Institut für Pharmakologie Düsseldorf, Deutschland; ³Düsseldorf, Deutschland; ⁴Uniklinikum Düsseldorf Institut für Pharmakologie Düsseldorf, Deutschland; ⁵Universitätsklinikum Düsseldorf Institut für Pharmakologie Düsseldorf, Deutschland

Background: Fibroblast activation is a critical determinant for the healing and remodeling response post myocardial infarction (MI). While transient activation is required for scar formation, sustained myofibroblast activity and extracellular matrix (ECM) deposition can contribute to adverse cardiac remodeling and fibrosis. Cell Migration Inducing Protein is a hyaluronidase which is highly expressed in cardiac myofibroblasts. This study aims to investigate the role of CEMIP in the healing and remodeling process post MI using a mouse model of cardiac ischemia/reperfusion (I/R) injury. Methods: 12 week (w) old male C57BL/6J mice were used to determine Cemip expression in left ventricles after cardiac I/R injury. Six to 8w-old CAGG Cre-ERTM+/- Cemip^flox/flox and littermate control mice (WT) were injected with tamoxifen to induce global Cemip deletion (Cemip-KO) followed by induction of I/R. Flow cytometric cell sorting was used to isolate MEFSK4+ fibroblasts for KO validation. Infarct size was determined by TTC staining. Echocardiography was used to examine cardiac function. Scar size, collagen and periostin deposition as well as myofibroblast abundance were characterized at 21d post I/R. Flow cytometry was used to analyze cell composition in the heart, blood, spleen and bone marrow as well as cardiac apoptosis. Proliferation was assessed via Ki67 immunofluorescence stainings in cardiac sections. Single cell RNA sequencing (scRNAseq) was used to elucidate effects of CEMIP deletion on the fibroblast and immune cell phenotype. Results: Cemip mRNA expression was significantly upregulated in left ventricles peaking at 72 h post I/R. While ejection fraction was decreased, end diastolic and end systolic volumes were significantly increased in Cemip-KO as compared to control mice. Moreover, Cemip-KO hearts exhibited increased scar size, collagen deposition and chronic myofibroblast abundance in the scar. Decreased fibroblast apoptosis contributed to an altered cardiac cell composition at 72h post I/R. Mechanistically, scRNA seq revealed upregulation of integrin-mediated ECM adhesion and TGFβ-pathway activity in Cemip-KO fibroblasts. Furthermore, a critical role for CEMIP in the macrophage-fibroblast-crosstalk is suggested by the results of scRNA seq. Conclusion: Our data suggest that CEMIP contributes to post-infarct healing by regulating cardiac fibroblast survival in the post-infarct environment while limiting excessive activation and myofibroblast-transition during scar formation. Thus, CEMIP may be considered as a novel target in post MI healing.