Research Projects

Sepsis is a disease caused by the effects of a systemic infection accompanied by host hyper-immune response. Gram-negative sepsis (GNS) accounts for just under half of the overall cases of bacterial sepsis, which is currently the leading cause of death in hospitals. One pivotal clinical study demonstrated that human antisera raised against a J5 mutant of Escherichia coli (E. coli) reduced death in human sepsis patients in half. Later, IgG from that antisera was shown to bind several E. coli lipoproteins, including peptidoglycan associated lipoprotein (Pal). Since those studies, Pal has been shown to be released from E. coli in several animal models of GNS and to cause an inflammatory response and death in certain animal models, suggesting that Pal may be a bacterial mediator of E. coli sepsis. The Michel Research Group uses biochemical and biophysical methods to better understand how and why Pal is released from E. coli during sepsis, with the long-term goal of using Pal as a biomarker for early diagnosis of sepsis. This work is part of a collaboration between the Michel Research Group and the research group of Dr. Judith Hellman, Professor & Vice Chair for Research in the Department of Anesthesia and Perioperative Care at UC San Francisco.

Additionally, we propose that Pal is released from E. coli inside bacterial outer membrane vesicles (OMVs). OMVs are ~20–250 nm spherical buds derived from the outer membrane of Gram-negative cells. We propose that bacterial OMVs are also highly attractive diagnostic biomarkers for sepsis due to their abundance, their robustness, even in the presence of antibiotics, and their unique features that could allow for differentiation between bacterial species. This work is part of a collaboration between the Michel Research Group, the research group of Dr. Thomas Gaborski, Associate Professor of Biomedical Engineering at RIT, and Dr. Anthony Pietropaoli, Professor and Vice Chief of Pulmonary Diseases and Critical Care at University of Rochester.

Patent Pending: Sepsis Diagnosis via PAL (Peptidoglycan Associated Lipoprotein) Detection in Urine

https://www.rit.edu/research/ipmo/companies/licensing

Gamma B crystallin is the bovine homolog to the human lens gamma D crystallin protein. Abnormalities, such as single point mutations, in crystallin proteins have been implicated in cataracts, a condition where loss of protein solubility in the eye lens leads to partial or total blindness due to lens cloudiness. In addition, changes in interactions between crystallin proteins due to altered electrostatic effects can contribute to phase separation in the lens. In order to better understand these protein-protein interactions, it is necessary to first describe the probable charge patterns on the proteins. These charge patterns greatly impact inter-protein interactions and therefore have an effect on liquid-liquid phase separation in the lens. The Michel Research Group collaborates with the Thurston Research Group (PI of the project: Dr. George Thurston, Physics) to describe the charge patterns on gamma B crystallin and predict those charge probabilities at low protein concentrations; to measure the acidity of individual gamma B crystallin residues using nuclear magnetic resonance (NMR) spectroscopy and other computational methods; and to use other NMR experiments to better understand how and under what conditions the gamma B crystallins interact with each other.