DC-SIGN targeting carbohydrate moieties identified on 67 kDa mfa-1 fimbriae of mucosal pathogen Porphyromonas gingivalis (42.7)

We recently reported that the oral mucosal pathogen Porphyromonas gingivalis targets the C- type lectin receptor DC-SIGN for invasion and persistence within human monocyte-derived dendritic cells (DCs). The DCs respond by inducing an immunosuppressive and Th2-biased CD4+ T cell response (Zeituni et al 2009); moreover, DC invasion and immunosuppression are dependent upon expression of the 67 kDa mfa-1 fimbriae by P. gingivalis . We have now purified mfa-1 by ion exchange chromatography and sequenced it by tandem mass spectrometry (MS/MS), confirming its identify and revealing two putative N-glycosylation motifs as well as numerous O-glycosylation motifs. We further show mfa-1 is glycosylated by ProQ staining. Further monosaccharide analysis by gas chromatography-mass spectrometry (GC-MS) confirmed that mfa-1 contains fucose (1.35 nmol/mg) mannose (2.68 nmol/mg), N-acetylglucosamine (2.27 nmol/mg) and N-acetylgalactosamine (0.652 nmol/mg). Analysis by transmission electron microscopy reveals mfa-1 form oligomeric strains approximately 200 nm in length, which could be involved in targeting/ cross-linking DC-SIGN. These findings shed further light on mechanisms of invasion and immunosuppression by this unique mucosal pathogen.

Blood dendritic cells in cardiovascular disease risk (44.13)

An estimated 80 million U.S. adults have one or more types of cardiovascular diseases (CVD) with the total cost to the U.S. for 2009 estimated to be $475.3 billion. Atherosclerosis (ATH) is the single most important contributor to CVD; however, only 50% of ATH patients have currently identified risk factors. Chronic periodontitis (CP), a common inflammatory disease, is linked to an increased CVD risk. Dendritic cells (DCs) which infiltrate arterial walls and destabilize atherosclerotic plaques, have been implicated in CVD. While the source of atherogenic DCs is presently unclear, we propose that dermal DCs from peripheral inflamed sites, such as CP tissues are a source. We therefore designed a clinical study to elicit, quantitate and isolate DCs in the peripheral blood of otherwise healthy CP patients. Ten patients with CP were consented according to IRB standards and enrolled in the study. Peripheral blood collected at baseline and 24 hrs after mechanical debridement (MD) was used to identify and sort blood DCs. After PBMC separation, DCs were labeled with DC-SIGN-APC and BDCA-1-PE and quantitated by FACS analysis. We found that after MD there was a 5-6% increase in the numbers of blood DCs in this patient population. This increase in the blood may represent mobilization of DCs from bone marrow stores, as well as from CP tissues. We are presently analyzing the DC transcriptome of sorted DCs to identify markers of atherogenesis.