Using nanopocket membranes to capture bacterial outer membrane vesicles from biofluids

项目总结

PROJECT SUMMARY Sepsis is not only the most expensive condition treated in US hospitals, but also a leading cause of death. Sepsis occurs when host pro-inflammatory immune responses become abnormally elevated due to a dysregulated or aberrant host-response to infection. Diagnostic methods for sepsis can vary between hospitals, but often involve scoring systems (e.g. APACHE II and SOFA) that grade the severity of illness in patients. Many of the altered physiological parameters measured by these scoring systems are not necessarily specific to sepsis, which makes it difficult to diagnose sepsis in early stages. Timing of a patient’s sepsis diagnosis is often predictive of their clinical outcome, underlining the need for a more definitive molecular diagnostic test. However, a recent study found that in the majority (70.1%) of sepsis cases, a specific causal organism could not be determined, likely due to aggressive antibiotics or localized infections. Bacterial outer membrane vesicles (OMVs) are attractive diagnostic biomarkers because of: A) their abundance and ability to circulate throughout the body and pass tissue barriers more easily than bacteria themselves; B) their robustness - unlike their bacterial cell “parent,” OMVs can withstand the inundation of broad-spectrum antibiotics; and C) their unique features that could allow for differentiation between bacterial species. The objective of this proposal is two-fold: Identify whether bacterial OMVs could be a molecular diagnostic biomarker for sepsis and develop a rapid approach to isolate them from patient plasma. We seek to develop a straightforward high-purity and rapid separation technology that effectively isolates and purifies OMVs from biofluids, including plasma. We will implement a modified tangential flow filtration approach, similar to those used by biopharma for high-capacity and high- yield purification, with a new nanopocket membrane that effectively captures and releases bacterial OMVs with minimal loss. Success of these aims will pave the way for the future development of a one-step, point-of-care diagnostic test for sepsis using bacterial OMVs as the molecular biomarker, as well a more complex diagnostic test that more accurately quantifies OMV levels in the patient’s biofluids to help direct early treatment and reduce mortality. This project will be led by an interdisciplinary team of experts in identifying potential biomarkers in E. coli; membranes, materials, and bioseparations; and a critical care physician scientist.