PhD Scientific Days 2023

Translational Medicine - Posters P

Complement MASP-1 influences endothelial wound healing

Text of the abstract

Mannose-binding lectin-associated serine protease 1 (MASP-1) is one of the key components of the complement lectin pathway and can activate the endothelial cells, shifting them into a pro-inflammatory state. Activation of the complement system plays a role in the pathomechanism of heart attacks and strokes caused by atherosclerosis. In our previous transcriptomic study, we found that MASP-1 treatment significantly affected the expression of angiogenesis-related genes. Neovascularization plays an important role in regeneration after infarction so in our research we wanted to examine the fundamental answers of endothelial cells to mechanical injury and the effect of MASP-1 on angiogenesis.
Human umbilical vein endothelial cells (HUVECs) were used as a model before passage 5. Intracellular Ca2+-mobilization and CREB phosphorylation were measured with fluorescence microscopy. We measured VCAM-1 expression with cellular ELISA. The speed of the wound healing process was studied with ibidi 3 well culture inserts. Formation of networks were studied on Matrigel. We used recombinant MASP-1 for the experiments.
Mechanical injury (scratching with a sterile pipette tip) of the HUVECs induced a rapid calcium wave. The ATP scavenger apyrase did not inhibit Ca2+-mobilization in the cells closest to the scratching, but the propagation of the calcium wave was inhibited. Scratching of the endothelial cells induced the phosphorylation of CREB transcription factor (maximum at 15 minutes after scratching), which was not affected by apyrase. We found that MASP-1 did not affect the wound closure speed but promoted the disintegration of established networks on Matrigel. This effect could be blocked by C1-inhibitor (natural inhibitor of MASP-1). Mechanical injury enhanced the VCAM-1 expression of the endothelial cells and 24 hours long MASP 1 pretreatment further increased this.
Our results overlap with and reinforce the findings of other groups in the propagation and inhibition of mechanically induced calcium waves on endothelial cells. Besides calcium waves, CREB phosphorylation seems a key mediator of tissue damage process, which is also a mediator of MASP 1 signaling. Tissue damage in the presence of complement lectin pathway activation provides an elevated VCAM-1 expression, which induces a more effective immune response against the invading microbes.