The Role of S1PR2 in MRSA-induced Barrier Dysfunction and Lung Injury - PROJECT SUMMARY/ABSTRACT The acute respiratory distress syndrome (ARDS) is a life-threatening condition that occurs frequently in critically ill patients. Sepsis and pneumonia are leading causes of ARDS, with methicillin-resistant Staphylococcus aureus (MRSA), a gram-positive, antibiotic-resistant bacteria, being a significant contributor. MRSA infection causes acute inflammatory injury to the lung (acute lung injury-ALI) that disrupts the vascular endothelial barrier leading to alveolar edema, a hallmark pathophysiologic feature of ARDS. Thus, the development of vascular-targeted therapeutic strategies aimed at restoring and preserving the lung endothelial barrier integrity is of critical importance for the effective management of ARDS. Sphingosine-1-phosphate (S1P) is an endogenous bioactive lipid that plays critical roles in regulating endothelial cell (EC) processes, including vascular barrier function. Lung EC predominantly express the S1P receptors 1-3 (S1PR1-3), where S1PR1 has a well-established role in in promoting barrier function, and S1PR3 is associated with barrier dysfunction. However, the role of S1PR2 remains much less well-defined. Our preliminary findings demonstrate that inhibition of S1PR2 exacerbates MRSA-induced lung injury in vitro and in vivo. Notably, S1PR2-deficient mice exhibit significantly worse injury compared to wild-type animals when infected with MRSA, while pharmacological inhibition of S1PR2 in human lung ECs exacerbates MRSA-induced lung barrier permeability. This proposal seeks to elucidate the novel mechanisms by which S1PR2 regulates vascular barrier function in response to MRSA-induced lung injury. Specific Aim 1 will investigate the effects of MRSA on the expression and subcellular localization of S1PR2 in lung ECs, as well as elucidate the role of S1PR2 in regulating endothelial injury caused by MRSA. Using advanced assays to assess barrier function and vascular permeability, key processes in ARDS pathophysiology, we will evaluate the effects of S1PR2 expression and activity on lung vascular function. Additionally, we will examine the potential key role of the transcription factor KLF4 in mediating S1PR2 effects through regulation of junctional proteins essential for endothelial barrier stability. Specific Aim 2 will determine the role of S1PR2 in MRSA-induced ALI in vivo. We will compare the injury responses in S1PR2-deficient and wild-type mice infected with live MRSA, evaluating multiple indices of lung injury. This aim will also utilize RNA sequencing to identify genetic differences between these two strains, providing insights into S1PR2-dependent pathways. Additionally, pharmacological inhibition of S1PR2 in C57BL/6 mice and endothelial specific S1PR2 knockdown will further clarify its role in vascular barrier regulation. This research will be conducted at the University of Illinois Chicago in the Division of Pulmonary, Critical Care, Sleep and Allergy. By advancing our understanding of endothelial barrier function in the context of MRSA-induced lung injury, this work will provide a foundation for my K99/R00 award application and facilitate my transition to independent investigator status.
