Executive Summary : | Neutrophils are vital in body’s fight against various infections, but upon over-activation can cause tissue damage and thus often get associated with inflammatory disorders. These cells are high in numbers (60-70% of human leukocytes), with a short life of 10-18 h, thus undergo a high turnover of 50-100 billion cells/day. Neutrophils undergo diverse deaths including steady state- apoptosis and inflammation/stimuli- dependent necroptosis, pyroptosis, NETosis and necrosis. Moreover, enhanced NET formation and their subsequent impaired degradation/clearance are associated with multiple disease pathologies including lupus, and COVID-19. Thus effective removal of these deaths and remnants (various cellular content present/ released during/after process of death) is critical to prevent inflammatory and autoimmune responses. This proposal aims to understand the diverse neutrophil deaths, that will be extended to differential DAMPs produced in various route of neutrophil deaths, their immunogenicity and clearance mechanisms. Though apoptotic cell clearance is described to an extent, here we will focus on lytic deaths including necroptosis, pyroptosis, NETosis and necrosis and their remnants. The preliminary data so far are very intrguing. The key objectives of this proposal are -1) To investigate and characterize different forms of neutrophil deaths including NETosis, pyroptosis, necroptosis, apoptosis and remnants released. 2) To unravel the immunogenic or inflammatory potential of diverse deaths and associated cellular remnants. 3) To establish significance of neutrophil clearance mechanisms in disease conditions and identification of putative therapeutic approaches. Altogether, the proposed research will provide precise understanding of diverse neutrophil deaths and mechanisms leading to immunogenic or inflammatory potential. These deaths are associated with differential immunlogical outcomes, as a key approach, upon induction of neutrophil deaths processes like caspases, DNases, ROS and mitochondrial activation with further activation of signalling pathways will be identified to specify immunogenic trigger. Further, it would be interesting to understand effect of diverse DAMPs and other remnants including exosomes, ex-DNA, diverse proteins released during deaths for immunogenic responses. The remnants responsible for inflammatory or immunogenic outcomes will be defined using proteomics and targeted approaches. Furthermore, clearance mechanism of diverse death remnants will be identified using macrophages and dendritic cells. Mechanistically NOX-2 deficient neutrophils and mice that are prone to immunogenic outcomes will be utilized. Together, this will also open up avenue to identify and understand the molecular mechanism of major immunogenic DAMPs, that may be exploited towards efficient clearance of lytic deaths and associated remnants without instigating auto-immunogenic responses and to identify targets for therapeutic applications. |