392 Immune Signaling in TLR9-/- Murine Macrophages Infected with Porphyromonas gingivalis

Thursday, March 22, 2012: 2 p.m. - 3:15 p.m.
Presentation Type: Poster Session
C. WARREN, T. WYANT, S. YANAMANDRA, H. MIYAZAKI, A. YEUDALL, and J. LEWIS, School of Dentistry Philips Institute OCMB, Virginia Commonwealth University - VCU/MCV, Glen Allen, VA
Objectives: Porphyromonas gingivalis (Pg) is a major etiologic agent in the onset and progression of periodontal disease. Pg has many virulence factors of which DNA has been recognized as immunogenic. Toll-like receptor (TLR) 9 is recognized as an indispensable receptor for mediating the host response to bacterial DNA. However, studies revealed presence of other receptors. Like TLR9, DNA-dependent activator of interferon (IFN) regulatory factors (DAI) also induces release of type I IFN and pro-inflammatory cytokines. Furthermore, absent in melanoma-2 (AIM2) is responsible for activation of inflammasomes. Therefore, our aim is to elucidate the mechanisms of overall immune responses of macrophages to challenge with Pg and its DNA using WT and TLR-/- murine macrophages.

Methods: Murine macrophages were isolated. The cells were co-incubated with 50mg of DNA derived from Pg W83, Pg cells MOI 100:1 or no challenge at 6h. Macrophage RNA was isolated and microarray analysis was performed.

Results: Initial microarray analysis demonstrated that both Pg and Pg DNA showed similar numbers of genes regulated that were involved in the inflammatory response: an average of 1559 (Pg) vs. 1451(DNA). In addition, similar numbers of genes were regulated in the IL-8, chemokine, NF-κB and IL-6 pathways under both conditions. Also, TLR9-/- cells had upregulation of IFNAR1 when challenged with DNA than the WT cells and JAK1 showed similar levels of regulation amongst WT and TLR9-/- cells.

Conclusions: These results suggest that DNA is the major virulence factors in the immune response. Due to type I interferon response in the TLR9-/- cells, we believe that DAI or other unknown DNA receptor(s) may be responsible. Finally, the similar regulation of JAK1 in both cell types challenged with DNA shows that a TLR9 independent mechanism may predominate.

This abstract is based on research that was funded entirely or partially by an outside source: NIH 5 F30 DE020000-03

Keywords: Cytokine, Gene expression, Immune response, Inflammatory mediators and Periodontal disease