Lung-on-a-Chip and Spatial Transcriptomics to Define Eicosanoid Roles in Mucosal Immunity during Influenza/Staphylococcus aureus Superinfection - PROJECT SUMMARY/ABSTRACT Respiratory infections like the flu can lead to severe complications when bacteria invade the lungs, causing what is known as a super-infection. These infections significantly increase hospitalizations and deaths, particularly when caused by antibiotic-resistant bacteria such as Staphylococcus aureus (S. aureus). Despite medical advances, scientists do not fully understand why the immune system fails to prevent these severe infections after a viral illness. One major gap in knowledge is how mucosal immunity—the immune defense system of the lungs and airways—is disrupted following viral infections, making patients more vulnerable to bacterial super- infections. Our research focuses on a group of molecules called eicosanoids, which regulate inflammation and immune responses in the lungs. Specifically, we are studying how a subset of these molecules, called cytochrome P450 (CYP450)-derived lipids, influence immune cell behavior during bacterial super-infections. Our preliminary findings suggest that CYP450 lipids activate a protein called PPARα, which weakens the immune system's ability to fight bacteria and disrupts mucosal immunity. Mice lacking PPARα showed improved resistance to super-infections, suggesting that blocking this pathway could enhance bacterial clearance and restore lung immune defenses. Additionally, we used advanced imaging techniques to track these lipids in lung tissues and found that their distribution is linked to areas of severe infection. However, we still do not fully understand how these lipids influence immune cells at a molecular level or how they alter mucosal immunity to create conditions favorable for bacterial persistence. To address these gaps, we will use two cutting-edge approaches: 1) spatial transcriptomics, which allows us to see how different cells in the lung respond to infection at a single-cell level, and 2) a lung-on-a-chip device, which mimics human lung tissue to study real-time interactions between immune cells and bacteria. These approaches will help us understand how CYP450 lipids and PPARα signaling contribute to immune dysfunction and mucosal immunity breakdown. By uncovering the molecular mechanisms behind immune suppression and mucosal immune dysregulation during bacterial super-infection, our research has the potential to lead to new treatments. Targeting PPARα could offer a novel strategy to enhance the immune response, improve mucosal immunity, and reduce the severity of respiratory infections. This study will provide critical insights into how the body responds to lung infections and may inform future drug development to combat antibiotic-resistant bacteria.
