Growth differentiation factor 15 (GDF15) is elevated in human plaques and promotes endothelial-to-mesenchymal transition (EndMT)

Abstract Introduction and Purpose Growth Differentiation Factor 15 (GDF15) is a member of the TGF-β superfamily and is upregulated under conditions of injury and stress such as hypoxia. GDF15 serum concentrations correlate with inflammation, cardiac fibrosis and unfavorable prognosis in cardiovascular diseases. The functional role of GDF15 in endothelial cells is largely unknown. Here, we investigate a possible role of GDF15 in the transdifferentiation of endothelial cells (EC) into mesenchymal cells (EndMT). Methods and Results GDF15 is expressed at mRNA and protein level in primary human ECs and is secreted as determined by qPCR, single cell sequencing (scRNA-seq) and enzyme-linked immunosorbent assay (mean ± SEM, 743.8±39.3 pg/ml, n=3). Analysis of vascular sections from Ldlr-/- mice fed a high-fat diet using spatial transcriptomics revealed increased GDF15 expression. ScRNA-seq analysis of human plaques and normal vessel sections from the same individuals revealed a 22-fold ± 5.48 (p<0.05) increase in GDF15 in ECs located in plaques compared to ECs in control vessel regions. Experiments in cultured human endothelial cells showed increased GDF15 mRNA expression qPCR (+1.7-fold control, p<0.05) and scRNA-seq analysis after EndMT induction. Treatment with increasing levels of recombinant GDF15 (10, 50 and 150 ng/ml) induced EndMT as measured by expression of the EndMT marker calponin (+3.36, 7.99 and 9.53-fold, all p<0.05). Interestingly, EndMT induction decreased extracellular GDF15 levels (-54.6%, p<0.05), whereas intracellular levels in EC were increased (+1.9-fold control, p<0.05). The use of GDF15 neutralising antibodies (1 µg/ml) reduced soluble GDF15 levels by 97.7% as measured by ELISA (p<0.001). Treatment with neutralising antibodies against GDF15 reduced EndMT induction by 54% as measured by the EndMT marker calponin (p<0.05). Conclusion In conclusion, GDF15 is elevated in mouse and human plaques, and in EndMT. Treatment with GDF15 induces EndMT, whereas inhibition by neutralising antibodies reduces EndMT induction. These data are consistent with a functional role of GDF15 in endothelial dysfunction and atherogenesis.