Apoptosis and efferocytosis as mechanisms of impaired fibrotic tissue repair in diabetes associated vascular complications

Background:

Diabetes mellitus type 2 (T2D) is rapidly increasing. T2D patients have a significantly higher risk to suffer from cardiovascular events but the underlying cause is unknown. We recently provided evidence for an impaired tissue repair rather than an enhanced inflammatory activity as the cause of the high risk in T2D.

Apoptosis and the removal of apoptotic cells (efferocytosis) is central for tissue repair. It has been shown that apoptotic/necrotic cells agglomerate in T2D plaques. This suggests that an enhanced apoptosis or an impaired efferocytosis leads to agglomerates of dead cells which could be the cause of an impaired tissue repair in T2D.

I aim to explore: - If apoptosis contributes to future cardiovascular events in T2D - Identify key pathways for impaired efferocytosis and enhanced apoptosis in T2D - The influence of lipid metabolism on cell death and tissue repair - Differences in pro- and anti-inflammatory cell populations important for efferocytosis in plaques from T2D

- Differences in tissue repair focusing on ECM proteins and growth factors and to determine how apoptosis/efferocytosis affects tissue repair in T2D Workplan: Carotid/femoral plaques, blood and follow up data is available in the CPIP biobank (n=1200 patients). ELISA will be used to study the role of apoptosis for future events.

Apoptosis/necrosis/efferocytosis in situ will be assessed by histology/ELISA/confocal.

Key apoptosis/efferocytosis pathways will identified by RNA sequencing on plaque and located with spatial transcriptomics. Functionality of live cells isolated from human plaques will be studied in vitro and by single cell sequencing. Efferocytosis markers/growth factors will be determined using Luminex and a SciLife platform.

Cell populations will be assessed by histology, masscytometry and single cell sequencing.

Mass spectrometry and Seahorse will be used to study extra cellular matrix repair, lipid patterns and cellular metabolism. Significance:

The identification of biological differences in T2D atherosclerosis which cause the high risk for complications is crucial. By understanding differences in cell death, efferocytosis and tissue repair we aim to identify new therapeutic targets and biomarkers to prevent cardiovascular events in T2D.