2 The periodontal host response contains both protective and destructive elements.3 The factors that drive the host anti-bacterial response towards a destructive or protective response seem not to be understood completely. Dendritic cells (DCs) are a class

of specialized antigen-presenting cells that play an important role in the recruitment and activation of cells of the innate immune system, and deliver co-stimulatory signals to activate naïve T cells, thus triggering the initiation of the adaptive immune response.4 The cytokines secreted from DCs greatly affect the quality of the innate and adaptive immune responses.5 Depending on their differentiation and maturation Idelalisib molecular weight state, DCs can tolerize T cells, or direct HSP inhibitor cancer their differentiation towards protective or pathogenic immunity.6 Thus, the interactions between DCs and cells of the innate and adaptive immune system are important in the pathogenesis of many infectious diseases.7 and 8 DCs are

derived from precursor cells present in bone marrow and peripheral blood, mainly monocytes. Then migrate to oral tissues and live there as resident DCs, acting as sentinels in host defense; or differentiate in the sites of infection when they find an invading pathogen. In the immature state, DCs capture antigens efficiently, but as they mature, they undergo phenotypic changes that facilitate their migration towards lymphoid organs and their unique ability to prime T cells.4 and 9 It is known that bacterial LPS can estimulate the production of chemokines and cytokines, specially GM-CSF, that modulates DC movement and maturation.4

However, the effects of periodontal bacteria on DC differentiation, maturation and function/activation remain poorly understood. Few studies have been performed and their results are contradictory. Experiments Gefitinib datasheet by Jotwani et al.10 and Aroonrerk et al.11 showed that in vitro-generated MDDCs pulsed with Porphyromonas gingivalis underwent maturation (shown as an increase in CD83+), regulation of co-stimulatory molecules (CD80, CD86), release of both pro-inflammatory (IL-1β, IL-12p70) and anti-inflammatory (IL-10) cytokines, and secreted immunomodulatory molecules, such as PGE2. In contrast, studies by Cohen et al. 12 and Kanaya et al. 9 suggested that P. gingivalis either inhibited maturation of DCs, which had increased CD1a expression (characteristic of immature DCs) or was only weakly immunostimulatory. In the present study, we hypothesized that monocyte-derived dendritic cells (MDDCs) from individuals with periodontitis may be more easily directed towards a pro-inflammatory response than DCs from periodontally healthy subjects. We also hypothesized that pathogenic bacteria may influence the pro-inflammatory response to modulate MDDCs maturation.