Professor and University Scholar
Oral Health and Systemic Disease Research Group
Departments of Periodontics/Endodontics and of Microbiology/Immunology
University of Louisville School of Dentistry
501 South Preston Street, Rm 206
Louisville, KY 40202
Phone: 502-852-5276
Fax: 502-852-4052
Email: g0haji01@louisville.edu

Degrees

D.D.S. - 1989
University of Athens, Greece
Ph.D. - 1994
University of Alabama at Birmingham

Research Interests

1) Innate immunity and periodontal pathogens; microbial immune evasion; Toll-like receptors and the Complement system; impact of aging and immunosuppression on periodontitis and associated diseases; animal models.

2) Induction of oral immunity; mechanisms of adjuvant action.

Research Summary Description

Research in my laboratory is concerned with cellular and molecular aspects of innate immune recognition of periodontal pathogens, and the impact of aging on host susceptibility to periodontitis.  Our main focus is on pattern-recognition receptors and the complement system, and how their respective signaling pathways cross-talk in health and disease.  Using state-of-the-art immunological, molecular biological and biophysical techniques, we study the dynamic nature of host-bacterial interactions, which may induce protection or, conversely, may be exploited by pathogens for immune evasion.  The physiological relevance of our in vitro observations is tested using mouse models of periodontitis and associated systemic conditions.  We maintain that infection-driven inflammatory diseases can be controlled if knowledge becomes available on the mechanisms and signaling pathways from which they arise.  Other projects in the lab involve harnessing innate immunity to develop novel vaccine adjuvants.  Our long-term objective is to establish safe and effective adjuvants in mucosal vaccine formulations against pathogens which invade via oral, respiratory, gastric, or urogenital routes.

Main Collaborators

The Oral Health and Systemic Disease Research Group.

Dr. Denis F. Kinane, University of Louisville, KY.

Dr. Donald R. Demuth, University of Louisville, KY.

Dr. Terry Connell, University of Buffalo, NY.

Dr. Michael W. Russell, University of Buffalo, NY.

Dr. John D. Lambris, University of Pennsylvania, PA.

Dr. Triantafyllos Chavakis, NIH/NCI, MD.

Dr. Richard I. Tapping, University of Illinois, IL.

Dr. Kathy Triantafilou, University of Sussex, UK.

Dr. Fuminobu Yoshimura, Aichi-Gakuin University, Nagoya, Japan.

Recent Publications

1.                   Liang, S., K.B. Hosur, S. Lu, H.F. Nawar, B.R. Weber, R.I. Tapping, T.D. Connell, and G. Hajishengallis.  Mapping of a microbial protein domain involved in binding and activation of the TLR2/TLR1 heterodimer.  J. Immunol. 182:2978-2985 (2009).

2.                  Hajishengallis, G., M. Wang, S. Liang, M. Triantafilou, and K. Triantafilou.  Pathogen induction of CXCR4/TLR2 cross-talk impairs host defense function.  Proc. Natl. Acad. Sci. USA 105:13532-13537(2008).

3.                   Hajishengallis, G., M. Wang, G.J. Bagby, and S. Nelson.  TLR2 controls acute pulmonary infection with Porphyromonas gingivalis in mice.  J. Immunol 181:4141-4149 (2008).

4.                   Graves, D.T., D. Fine, Y.-T., A. Teng, T.E. Van Dyke, and G. Hajishengallis.  The use of rodent models to investigate host-bacteria interactions related to periodontal diseases.  J. Clin. Periodontol. 35:89-105 (2008).

5.                   Hajishengallis, G., M.A. Shakhatreh, Wang, M., and S. Liang.  Complement receptor-3 blockade promotes IL-12-mediated clearance of Porphyromonas gingivalis and negates its virulence in vivo. J. Immunol. 179:2359-2367 (2007).

6.                   Wang, M., M.A. Shakhatreh, D. James, S. Liang, S.-I. Nishiyama, F. Yoshimura, D.R. Demuth, and G. Hajishengallis.  Fimbrial proteins of Porphyromonas gingivalis mediate in vivo virulence and exploit TLR2 and complement receptor-3 to persist in macrophages. J. Immunol. 179:2349-2358 (2007).

7.                   Liang, S., M. Wang, R.I. Tapping, V. Stepensky, H.F. Nawar, M. Triantafilou, K. Triantafilou, T.D. Connell, and G. Hajishengallis.  Ganglioside GD1a is an essential coreceptor for Toll-like receptor 2 signaling in response to the B subunit of Type IIb enterotoxin.  J. Biol. Chem. 282: 7532-7542 (2007).

8.                   Liang, S., M. Wang, K. Triantafilou, M. Triantafilou, H.F. Nawar, M.W. Russell, T.D. Connell, and G. Hajishengallis.  The A subunit of Type IIb enterotoxin (LT-IIb) suppresses the proinflammatory potential of the B subunit and its ability to recruit and interact with TLR2.  J. Immunol. 178: 4811-4819 (2007).

9.                   Hajishengallis, G., R.I. Tapping, E. Harokopakis, S.-I. Nishiyama, P. Ratti, R.E. Schifferle, E.A. Lyle, M. Triantafilou, K. Triantafilou, and F. Yoshimura.  Differential interactions of fimbriae and lipopolysaccharide from Porphyromonas gingivalis with the Toll-like receptor 2-centered pattern recognition apparatus.  Cell. Microbiol. 8:1557-1570 (2006).

10.               Harokopakis, E., M.H. Albzreh, M.H. Martin, and G. Hajishengallis.  TLR2 transmodulates monocyte adhesion and transmigration via Rac1- and PI3K-mediated inside-out signaling in response to Porphyromonas gingivalis fimbriae.  J. Immunol. 176:7645-7656 (2006).

11.               Hajishengallis, G., P. Ratti, and E. Harokopakis. Peptide mapping of bacterial fimbrial epitopes interacting with pattern-recognition receptors. J. Biol. Chem. 280: 38902 – 38913 (2005).

Biography

Dr. Hajishengallis obtained a D.D.S. in 1989 from the University of Athens, Greece, and a Ph.D. in Cellular and Molecular Biology in 1994 from the University of Alabama at Birmingham (UAB).  He pursued postdoctoral work at UAB and at the State University of New York (SUNY) at Buffalo.  In 2003 he was appointed Assistant Professor of Microbiology and Immunology at the Louisiana State University School of Dentistry, where he received Research Excellence Awards in 2004 and 2005.  He was subsequently recruited as a tenured Associate Professor to the University of Louisville (UofL), where he received the UofL Faculty Excellence Honor in 2006.  He is currently a Professor and a principal investigator at the Oral Health and Systemic Disease Group (Dept. of Periodontics, School of Dentistry) and has a joint appointment with the Dept. of Microbiology and Immunology, School of Medicine.  Dr. Hajishengallis has published over 65 peer-reviewed papers, and his research is currently supported by three R01 grants (as PI) by the National Institute of Dental and Craniofacial Research.  He serves as a reviewer on NIH study sections, is a member of several editorial boards (including the Journal of Dental Research and the Journal of Periodontology) and is an Associate Editor of the Journal of Immunology.  He is frequently invited to give lectures at prestigious institutions and international symposia in the U. S., Europe, Australia, and Japan.