CLR SENSING NECROSIS · Immune Functions of Myeloid Syk-coupled C-type Lectin Receptors Sensing Necrosis

Necrosis triggers an inflammatory response driven by macrophages that normally contributes to tissue repair but, under certain conditions, can induce a state of chronic inflammation that forms the basis of many diseases. In addition, dendritic cell (DC)-mediated presentation of antigens from necrotic cells can trigger adaptive immunity in infection-free situations, such as autoimmunity or therapy-induced tumour rejection. Recently, we and others have identified the myeloid C-type lectin receptors (CLRs) CLEC9A (DNGR-1), in DC, and Mincle, in macrophages, as receptors for necrotic cells that can signal via the Syk kinase. Previous studies on similar Syk-coupled CLRs showed that Dectin-1 and Dectin-2 can induce innate and adaptive immune responses. We thus hypothesise that recognition of cell death by myeloid Syk-coupled CLRs is at the root of immune pathologies associated with accumulation of dead cells. The overall objective of this proposal is to investigate necrosis sensing by myeloid cells as a trigger of immunity and to study the underlying molecular mechanisms. Our first goal is to characterise signalling and gene induction via CLEC9A as a model necrosis receptor in DCs. Second, we will investigate the role of myeloid Syk-coupled necrosis-sensing CLRs in animal models of atherosclerosis, lupus and immunity to chemotherapy-treated tumours. Our preliminary data suggest that additional receptors can couple necrosis recognition to the Syk pathway in DC; thus, our third aim is to identify novel myeloid Syk-coupled receptors for necrotic cells. Characterisation of the outcomes of sensing necrosis by myeloid Syk-coupled receptors and their effect on the proposed pathologies promises to identify new mechanisms and targets for the treatment of these diseases.