Unveiling Macrophage-Biofilm Interactions: Implications for Cellular Metabolism and Wound Healing

Abstract

Chronic wounds are challenging to treat, cause significant pain, prolong hospitalization, and in the most severe cases, may lead to infection and/or amputations. Understanding the pathophysiology of chronic wounds is crucial for creating novel therapies that promote healing. Bacterial biofilms have been shown to impair wound healing and promote a low-grade inflammatory response. In chronic wounds, macrophages are chronically activated in a pro-inflammatory state and are unable to promote tissue repair. It is unclear what interactions occur between biofilms and macrophages to drive this persistent pro-inflammatory activation. Emerging evidence suggests that mitochondrial reprogramming plays a key role in fine-tuning the macrophage inflammatory response to bacterial infection. In this study, we found that treatment of bone marrow-derived macrophages with conditioned medium containing secreted factors from single-species biofilms of Staphylococcus aureus or Pseudomonas aeruginosa resulted in different patterns of mitochondrial reprogramming and inflammatory responses. S. aureus conditioned media induced a low-grade inflammatory response, associated with a transient reprogramming of the mitochondria to support mitochondrial reactive oxygen species and inflammatory cytokine production. Alternatively, P. aeruginosa conditioned media induced a stronger inflammatory response associated with sustained mitochondrial reprogramming that resulted in prolonged accumulation of mtROS, which eventually resulted in cell death. When macrophages were stimulated with an anti-inflammatory signal, IL-4, they were unable to repolarize to an antiinflammatory state and demonstrated terminal reprogramming towards sustained inflammation.Our findings imply that secreted factors from biofilms (e.g., LPS) may alter mitochondrial function to rewire macrophages to promote prolonged inflammation in chronic wounds. The bacterial species that are present in wounds have a significant impact on this reprogramming. imposter syndrome. When my experiments failed and I began to self-doubt, your patience and constructive feedback helped me continue to progress. You were always positive, motivational, and committed, so I could tackle complicated research problems with the support I needed. You encouraged me to take the initiative to seek solutions and be resilient despite facing setbacks. Not only was I able to work with a fantastic team of people in your lab, but you also fostered collaboration between several research groups that allowed me to target my project from a multidisciplinary approach and conduct high-impact translational research. I am indebted to my co-supervisor and thesis advisory committee members, Dr. Joerg Overhage and Dr. Daniel Pletzer for their infinite guidance and insightful discussions, comments, and expertise throughout my thesis that has helped to improve my scientific approach. I would also like to acknowledge the collaborative efforts of Drs. Katrina DeZeeuw and Jonah Marek.Your expertise greatly helped in the development of th...