Restoring immune-vascular axis integrity to alleviate acute lung injury in sepsis

PROJECT SUMMARY/ABSTRACT Sepsis-induced multi organ dysfunction syndrome, which primarily affects the lungs and kidneys, is a major cause of morbidity and mortality worldwide. Acute lung injury (ALI) or its most severe form, acute respiratory distress syndrome (ARDS), are the most common complications of sepsis, for which no effective treatment except supportive care is available. Hence, novel therapeutic strategies for mitigating sepsis-induced ALI are desperately needed, more so in the face of the current SARS-CoV-2 pandemic. Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to an infection, where both immune cells and endothelial cells play critical roles. Pathogen-induced inflammatory cascade and the endothelium impact each other via autocrine or paracrine loops to increase vascular permeability and cause immune dysregulation to disrupt immune-vascular homeostasis. Hence, therapies aimed towards reinstating immune-vascular homeostasis are needed to alleviate sepsis-induced complications like ALI/ARDS. Neuropilin-1 (NRP1), implicated in vascular permeability and inflammation, may prove to be a viable target for treating sepsis-induced ALI by restoring immune-vascular integrity. Hence, the central hypothesis of our proposal is that NRP1 plays a critical role in the immune-vascular dysfunction in sepsis-induced ALI and targeting NRP1 for restoring the immune-vascular homeostasis is a viable therapeutic option for this disease. To validate our hypothesis, we propose three specific aims. In Aim 1, we will analyze the effect of ALI- relevant cytokines in vitro in mouse lung endothelial cells isolated from endothelial-specific NRP1 knockout mice. We will also develop ALI in these mice by high dose lipopolysaccharides (LPS) treatment or by cecal ligation and puncture (CLP) to evaluate the role of endothelial NRP1 in the severity of sepsis-induced ALI, in vivo vascular permeability, leukocyte rolling and extravasation. Aim 2 will investigate the effect of coculturing peripheral blood mononuclear cells (PBMCs) isolated from myeloid-specific and CD4+T-cell specific NRP1- knockout mice with wild-type mouse lung endothelial cells. Moreover, we will develop ALI in these NRP1- knockout mice models to investigate the pleotropic role of NRP1 in these two immune cell populations during sepsis-induced ALI. Aim 3 will evaluate the therapeutic efficacy of an endothelial cell (EC)-targeting liposomal formulation of a small-molecule NRP1 inhibitor (EG00229), in ameliorating the severity of sepsis-induced ALI. We anticipate that our proposal will provide a deeper insight into the role of NRP1 in the immune- vascular dysfunction in sepsis-induced ALI and lead to the development of a viable therapeutic strategy of targeting NRP1 to overcome its severity. The ultimate goal of our proposal is to benefit a large number of patients suffering from sepsis-induced lung complications for which there is no effective therapy till date.