Harrison School of Pharmacy

Faculty and Staff Directory

 

Peter Panizzi Peter Panizzi
Associate Professor

Department: Drug Discovery and Development
Auburn University
Harrison School of Pharmacy
3211j Walker Building
Auburn, AL 36849
Email: prp0003@auburn.edu
Phone: 334-844-7941
Fax: 334-844-8331

Curriculum Vitae

Education:
B.S. - Montevallo, 1996
M.S., Biochemistry - Vanderbilt, 1999
Ph.D., Cellular and Molecular Pathology - Vanderbilt, 2004

Research Summary | Project ALIAS Website | Complete List of Published Work

 Personal Statement

My lab uses state-of-the-art molecular imaging technologies to monitor disease progression and to evaluate therapeutic efficacy. On the whole, my lab is split between three seemingly divergent subjects, namely the imaging of bacterial infections, assessing tumor development processes during cancer and tracking neutrophil response during inflammation. Although seemingly unrelated these processes and diseases have nascent similarities in that they are triggered by an abnormal cluster of cells (either self or foreign) that grow rapidly in the host at rates governed by a combination of both the individual bacterial or cancer cells' reproduction parameters and by the degree of host immune response to this new stimuli (e.g., neutrophil burst or macrophage involvement in the growing tumor). In all cases, we have to tailor our studies to maximize the information acquired in our defined imaging window.

For example, in our murine sepsis or injury-induced endocarditis models the subject is monitored for up to 10 days, while in our cancer studies the athymic NCR nude mice are monitored for up to several months. Given this vast discrepancy, we can often use our bacterial infection models to test defined logistical aspects and protocols for new imaging systems and some agents prior to application in cancer studies. As such, we feel this to be a tremendous advantage that many of our peer labs do not consider given their staunch opposition entertaining diverse portfolios of projects. In our work here at Auburn Univ., we have also noticed problems with serial collection of bioluminescent / fluorescence datasets in mice over time regardless of the model and have taken steps to design better options for future implementation in these in vivo studies.

About at the same time, we were approached by the iThera Medical Company to place a Multi-Spectral Optoaccoustic Tomography (a.k.a., MSOT) system at Auburn Univ., in order to valid their in vivo imaging system for use with infectious disease research. Through a combined effort, we were able to bring that technology to Auburn University, thereby making Auburn University 1 of 5 MSOT locations in North America (circa Spring 2015). The acquisition of the MSOT imager provides us with unprecedented resolution when imaging optical targets deep with an animal. We have begun to assess tumor develop over time with this technology and determine the response of the tumor to classical doxorubicin chemotherapy. As a testament to the utility and popularity of these new methodologies at Auburn University, we recently participated as a key resource to all applicants for the state-sponsored Auburn Univ. Research Initiative in Cancer (AURIC) major grants program, thereby under-scoring the bright future of non-invasive optical imaging of cancer in rodent models here at Auburn.

At the same time, my lab began to collaborate others at Auburn, namely the Arnold, Amin, David, Petrenko, and Greene labs to tackle the difficult problem of tracking delivery of novel cancer therapies designed to limit tumor growth and metastases. To facilitate this venture, I have also established the Auburn Laboratory for Imaging Animal Systems (Project ALIAS) to assist other investigators as they seek to answer probative questions about the underlying biology of a disease and formulate ways to address challenging drug delivery problems. As an aside, my lab has maintained continuous NIH supported as a PI since 2007.

 Contribution to Science
  1. My research has uncovered a critical role for pro-coagulant virulence factors in the pathogenesis of Staphylococcal endocarditis. In particular, we found that staphylocoagulase was a more important determinant in establishment of the bacterial-fibrin-platelet vegetations. In our studies it was necessary to better understand the molecular mechanisms that regulate prothrombin activation by staphylocoagulase. The following citations indicate classical biochemistry studies that have proven for the first time the "Molecular Sexuality" mechanism of bacterial co-factor induced activation of host blood clotting zymogens; determined thermodynamic parameters for staphylocoagulase binding to host prothrombin (now known to occur with picomolar affinity); the mechanism of fibrinogen recognition as a specific substrate for the prothrombin-staphylocoagulase complex in the absence of both functioning exosites; and the structural basis for the observed 5,800-fold reduction in the Kcat/Km for human vs. bovine prothrombin-staphylocoagulase complexes. These studies served as a building block for many of my other contributions to science.
    1. Friedrich R, Panizzi P, Fuentes-Prior P, Richter K, Verhamme I, Anderson P, Kawabata S, Huber R, Bode W, Bock P. Staphylocoagulase is a prototype for the mechanism of cofactor-induced zymogen activation. Nature. 2003 October 2; 425(6957):535-539.
    2. Panizzi P, Friedrich R, Fuentes-Prior P, Kroh H, Briggs J, Tans G, Bode W, Bock P. Novel Fluorescent Prothrombin Analogs as Probes of Staphylocoagulase-Prothrombin Interactions. Journal of Biological Chemistry. 2005 October 17; 281(2):1169-1178.
    3. Panizzi P, Friedrich R, Fuentes-Prior P, Richter K, Bock P, Bode W. Fibrinogen Substrate Recognition by Staphylocoagulase{middle dot}(Pro)thrombin Complexes. Journal of Biological Chemistry. 2005 October 17; 281(2):1179-1187.
    4. Friedrich R, Panizzi P, Kawabata S, Bode W, Bock P, Fuentes-Prior P. Structural Basis for Reduced Staphylocoagulase-mediated Bovine Prothrombin Activation. Journal of Biological Chemistry. 2005 October 17; 281(2):1188-1195.
  2. My research studies also led to the discovery of the Zymogen Activator and Adhesion Proteins (ZAAPs) family of virulence factors elaborated by Staph and Strep. To begin to understand these novel proteins it was necessary to over-express them in E. coli, purify them, and screen them for possible activation of different human zymogens. This contribution is based on our continued collaboration with the lab of Dr. Paul E. Bock at Vanderbilt University School of Medicine. The citations listed below denote the initial discovery of the ZAAP family along with the collection of mechanistic studies that attribute newly discovered functions to a few of these novel ZAAP members.
    1. Panizzi P, Friedrich R, Fuentes-Prior P, Bode W, Bock P. The staphylocoagulase family of zymogen activator and adhesion proteins. Cellular and Molecular Life Sciences. 2004 November; 61(22):2793-2798.
    2. Kroh H, Panizzi P, Bock P. Von Willebrand factor-binding protein is a hysteretic conformational activator of prothrombin. Proceedings of the National Academy of Sciences. 2009 April 28; 106(19):7786-7791.
    3. Panizzi P, Nahrendorf M, Figueiredo J, Panizzi J, Marinelli B, Iwamoto Y, Keliher E, Maddur A, Waterman P, Kroh H, Leuschner F, Aikawa E, Swirski F, Pittet M, Hackeng T, Fuentes-Prior P, Schneewind O, Bock P, Weissleder R. In vivo detection of Staphylococcus aureus endocarditis by targeting pathogen-specific prothrombin activation. Nature Medicine. 2011; 17(9):1142-1146.
  3. My lab has continued to build on our previous foundation to better understand the development of and subsequent efficacy of treatment for S. aureus diseases. Our initial idea was to exploit the strong dependency that these gram-positive pathogen have for harnessing / acquiring host proteins to enhancing virulence of the pathogen during an infection. To add novelty, we use molecular imaging technology (primarily optical methods) to track these dangerous pathogens during an infection, such as endocarditis and sepsis. As proof of principal, we began our studies with S. aureus, which has the unique ability to wall itself off from host blood and tissue cells, avoiding immune detection and causing localized inflammation at the surrounding infection site. In the pathology of endocarditis, the protective endothelium layer is damaged in some way and circulating bacteria adhere to these sites of exposed host basement matrix through bacterial surface receptors. Once attached the pathogens rapidly multiply, whilst secreting factors to clot the host blood in order to build this aforementioned wall around the developing vegetation. Because of the virulent nature of S. aureus and their increasing resistance to antibiotic treatment, there is an urgent, clinical need to develop methods for the early and reliable diagnosis of S. aureus-based endocarditis. To facilitate this, our lab has used our understanding of the molecular mechanisms underpinning these processes. To this end, we have developed non-invasive imaging methods for the specific detection of S. aureus in vivo and begun to assess novel therapies to combat these infections.
    1. Panizzi P, Nahrendorf M, Figueiredo J, Panizzi J, Marinelli B, Iwamoto Y, Keliher E, Maddur A, Waterman P, Kroh H, Leuschner F, Aikawa E, Swirski F, Pittet M, Hackeng T, Fuentes-Prior P, Schneewind O, Bock P, Weissleder R. In vivo detection of Staphylococcus aureus endocarditis by targeting pathogen-specific prothrombin activation. Nature Medicine. 2011; 17(9):1142-1146.
    2. Panizzi P, Stone J, Nahrendorf M. Endocarditis and molecular imaging. Journal of Nuclear Cardiology. 2014; 21(3):486-495.
    3. Eggleston H, Panizzi P. Molecular Imaging of Bacterial Infections in vivo: The Discrimination between Infection and Inflammation. Informatics. 2014 May 30; 1(1):72-99.
    4. Davis R, Eggleston H, Johnson F, Nahrendorf M, Bock P, Peterson T, Panizzi P. In Vivo Tracking of Streptococcal Infections of Subcutaneous Origin in a Murine Model. Molecular Imaging and Biology. 2015;.
  4. My lab also has an ongoing interest in developing non-invasive imaging agents to measure the increased inflammatory burden experienced by mice in models of cancer, atherosclerosis and rheumatoid arthritis. We first asked whether disease states that have consistently high levels of circulating monocytes and /or neutrophils would have a beneficial or detrimental effect on wound healing processes after myocardial infarction. Using ApoE (-/-) mice fed a Western-diet for >6 months as our atherosclerosis model, we determined that indeed the presence of this heightened level of myeloid cells dramatically increased mortality in these mice compared to controls, especially after the mice were challenged by an ischemic event (i.e., permanent ligation of the left descending coronary artery). The resulting poor healing in the heart was assessed by rodent MRI, which proved in the weeks following the injury these atherosclerosis mice suffered from large reduction in their ejection fractions caused by a increase scar formation and a resulting dilation heart with contaminate increased in observed end diastolic volumes. Of note, Project ALIAS now has a Transonic Pressure-Loop device that will be used in future studies to more accurately test cardiac function. We then wanted to assess the mediators of inflammatory burden and, in so doing, turned our attention to myeloperoxidase (a central enzyme to inflammation). We developed a sensor of myeloperoxidase activity that can be used in mice to monitor disease pathology. Currently, we are developing novel ways to inhibit the myeloperoxidase enzyme by use of high-through put imaging, biochemical characterization, and toxicity screening in zebrafish. In two recent ABB paper, we discover that some potent myeloperoxidase inhibitors like benzoic acid hydrazide (BAH) and its analogs cause disruption of these important ester linkages that link the heme to the body of the peroxidase. We are continuing to study this area.
    1. Panizzi P, Nahrendorf M, Wildgruber M, Waterman P, Figueiredo J, Aikawa E, McCarthy J, Weissleder R, Hilderbrand S. Oxazine Conjugated Nanoparticle Detects in Vivo Hypochlorous Acid and Peroxynitrite Generation. Journal of the American Chemical Society. 2009 November 04; 131(43):15739-15744.
    2. Panizzi P, Swirski F, Figueiredo J, Waterman P, Sosnovik D, Aikawa E, Libby P, Pittet M, Weissleder R, Nahrendorf M. Impaired Infarct Healing in Atherosclerotic Mice With Ly-6Chi Monocytosis. Journal of the American College of Cardiology. 2010 April; 55(15):1629-1638.
    3. Huang J, Smith F, Panizzi P. Ordered cleavage of myeloperoxidase ester bonds releases active site heme leading to inactivation of myeloperoxidase by benzoic acid hydrazide analogs. Archives of Biochemistry and Biophysics. 2014 April; 548:74-85.
    4. Huang J, Smith F, Panizzi J, Goodwin D, Panizzi P. Inactivation of myeloperoxidase by benzoic acid hydrazide. Archives of Biochemistry and Biophysics. 2015 March; 570:14-22.

 

Last Updated: March 7, 2017