Cytokine Profiling of Macrophages Exposed toPorphyromonas gingivalis, Its Lipopolysaccharide, or Its FimA Protein

Abstract

To characterize the roles of Porphyromonas gingivalis and its components in the disease processes, we investigated the cytokine profile induced by live P. gingivalis, its lipopolysaccharides (LPS), and its major fimbrial protein, fimbrillin (FimA). Using cytokine antibody arrays, we found that P. gingivalis LPS and FimA induced a similar profile of cytokine expression when exposed to mouse peritoneal macrophages but that this profile differed significantly in response to live P. gingivalis. In vitro, mouse peritoneal macrophages were stimulated to produce interleukin-6 (IL-6), granulocyte colony-stimulating factor, and lymphotactin by live P. gingivalis, but not by P. gingivalis LPS or FimA, while RANTES, gamma interferon, IL-17, vascular cell adhesion molecule 1 (VCAM-1), and vascular endothelial growth factor were induced by P. gingivalis LPS or FimA, but not by live P. gingivalis. In vivo, IL-6 mRNA was strongly induced only by live P. gingivalis while monocyte chemoattractant protein 1 mRNA was strongly induced only by P. gingivalis LPS and FimA in mouse calvarial scalp, further confirming the differences of cytokine profile induced in vitro. Cytokine antibody arrays using toll-like receptor 2 (TLR2)-and TLR4-deficient macrophages revealed that most of the cytokines induced by P. gingivalis LPS or FimA signal through TLR2, while most of cytokines induced by live P. gingivalis signal through both TLR2 and TLR4. Interestingly, the activation of TLR2 by live P. gingivalis inhibited the release of RANTES, VCAM-1, and IL-1␣ from mouse peritoneal macrophages. A tumor necrosis factor alpha enzyme-linked immunosorbent assay further confirmed that P. gingivalis LPS and FimA activate mouse peritoneal macrophages via TLR2. These results indicate that host immune cells sense live P. gingivalis and its components differently, which translates into the expression of different inflammatory cytokine profiles.

Gingival epithelial cells heterozygous for Toll-like receptor 4 polymorphisms Asp299Gly and Thr399Ile are hypo-responsive to Porphyromonas gingivalis

“…P. gingivalis is one of the more researched periodontal microorganisms and displays interesting properties signaling through TLR-2 and -4 and producing a wide cytokine response. 14 …”

The role of T helper 17 (Th17) and regulatory T cells (Treg) in human organ transplantation and autoimmune disease

“…It was described initially as a product of activated and memory CD4 + T cells [23,30,30,31] but it is now known that the production of IL-17A is more ubiquitous and has been demonstrated in gd T cells [32], CD8 + memory T cells [31,33], eosinophils [34], neutrophils [31] and monocytes [35]. Nevertheless, the predominant source of IL-17A (henceforth referred to as IL-17) remains the CD4 + memory T cell population [4,33].…”

Critical Role of Apoptotic Speck Protein Containing a Caspase Recruitment Domain (ASC) and NLRP3 in Causing Necrosis and ASC Speck Formation Induced by Porphyromonas gingivalis in Human Cells

“…During an infection, bacteria may directly activate a host cell-mediated host response via various bacterial products, with P. gingivalis-derived LPS being a prominent pathogen-associated molecule. Monocytes/macrophages present in the periodontal tissues of patients are major contributors of host response during periodontal diseases (3). In addition to monocytes/macrophages, other immune cell types such as keratinocytes, fibroblasts, dendritic cells, and endothelial cells also play a role in producing cytokines (4 -6).…”

“…Recently, new proteins that are members of the nucleotide-binding domain (NLR, 3 leucine-rich repeat (LRR) or NBD-LRR) family (http://www.genenames.org/genefamily/nacht.html; Ref. 17) have been identified as important regulators of the host response to pathogens and their components.…”