IMPACT · Immune Mechanisms of Necrotic DNA Phagocytosis by Neutrophils: A Role for Integrins
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2020-01-01 → 2024-01-01
- EU contribution
- €178,320
- Participants
- 1
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
Immune Mechanisms of Necrotic DNA Phagocytosis by Neutrophils: A Role for Integrins
Injury is common to all living beings. By performing daily activities and being exposed to harmful agents, we are at constant risk of suffering damage. In humans, that happens most often by mechanical forces (crushing, fractures), extreme temperatures (burns, frostbite) and chemical toxicity (substance abuse, adverse reactions). These situations lead to necrosis, a type of cell death strongly associated to inflammation. One of the consequences of necrosis is the generation of cell debris, which can be deposited in tissues and even reach our bloodstream. Cell debris is a powerful inducer of inflammation, and when accumulated in tissues, can actively delay tissue regeneration and recovery from injury. For this reason, it was paramount that we understood how the necrotic debris is removed from tissues in the first place. It is hypothesized that white blood cells named phagocytes go into the injury sites and clear the cell debris by themselves. The aim of the IMPACT project was to understand how phagocytes are able to do that and to find means to enhance the clearance of cell debris, such as cellular DNA, accelerating tissue recovery after necrotic injuries. To achieve this, necrotic debris clearance were characterized in vitro using a new model of necrotic cell debris phagocytosis and in live tissues using intravital microscopy. This enabled to visualize directly the activity of phagocytes and how they performed their role. By grasping the mechanisms of necrotic debris clearance, we could develop molecules and peptides that improved the function of phagocytes and facilitated the recognition of cell debris in tissues. This provides the basis for the creation of new therapies for a variety of necrotic diseases, including toxic liver injury, atherosclerosis, severe trauma, and even chronic diseases such as systemic lupus erythematosus. The conclusions and products of developing this project were multiple, including: 1) the demonstration and characterization of necrotic debris clearance from injury sites by neutrophils; 2) Establishing the central role of antibodies and the complement system in the recognition and elimination of necrotic cell debris; 3) The identification of a peptide that binds DNA from necrotic cells both in vitro and in vivo, reducing tissue inflammation; 4) Creation of new therapeutic strategies to treat injury, based on the improvement of necrotic cell clearance by antibodies; 5) Training and maturation of the researcher into an independent principal investigator.
Data: CORDIS, © European Union
Project objective
Cell death is inherently connected to the existence of multicellular organisms. Our body loses billions of cells a day due to thermal, mechanical or chemical damage in a cell death process with loss of plasma membrane integrity and pro-inflammatory properties known as necrosis. Organisms face necrosis frequently, thus, there must be specific pathways to remove the large amount of cellular debris left behind. In this way, it is no surprise that improper removal of cellular debris, such as DNA, is associated to inflammatory diseases as lupus erythematosus, acute liver injury, atherosclerosis and severe trauma. Removal of necrotic debris is thought to be mediated by phagocytes, although reports showing it are scarce. Neutrophils, a subset of phagocytes, are good candidates for debris removal since they are abundant and quickly recruited to necrotic sites. The means used by neutrophils to identify, internalize and degrade necrotic DNA are currently unknown, thus, the main objective of my project is to understand how neutrophils phagocytose and eliminate necrotic DNA debris. Neutrophils express the DNA-sensing receptor TLR9, which is not a phagocytic receptor. However, they also express very high levels of beta2 integrins such as CD11b/CD18, which act as adhesion molecule and as complement receptor (CR3). The release of necrotic DNA promotes complement activation in vivo through several pathways, therefore, my hypothesis is that neutrophils use beta2 integrins to bind and phagocytose complement-coated necrotic DNA. To assess the role of beta2 integrins, TLR9 and complement in phagocytosis of necrotic DNA by neutrophils, I will combine a novel in vitro method (DNA deposit in coverslip) with an in vivo approach (confocal intravital microscopy). I will also develop novel peptides for DNA labelling and modulation of phagocytosis, which I will use in both models. The findings of this project will directly favor the development of novel therapies for inflammatory diseases.
Original text from CORDIS.
Participants
- KATHOLIEKE UNIVERSITEIT LEUVEN · LeuvenCoordinatorBelgium
Links
Data: CORDIS, © European Union