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Hosokawa I, Hosokawa Y, Ozaki K, Yumoto H, Nakae H, Matsuo T. Proinflammatory effects of muramyldipeptide on human gingival fibroblasts. J Periodont Res 2010; 45: 193–199. © 2010 The Authors. Journal compilation © 2010 Blackwell Munksgaard Background and Objective: Because human gingival fibroblasts (HGFs) are the predominant cells in periodontal tissues, we hypothesized that HGFs are contributed to receptors for components of bacteria. In this study, we focused on expression and function of nucleotide binding oligomerization domain 2 (NOD2) in HGFs, which is a mammalian cytosolic pathogen recognition molecule. Material and Methods: Expression of NOD2 in HGFs was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry. Production of interleukin (IL)-6, IL-8, cc chemokine ligand2, cxc chemokine ligand10 (CXCL10) and CXCL11 from HGFs was examined by enzyme-linked immunosorbent assay (ELISA). We used RT-PCR and immunohistochemistry to detect the NOD2 expression in human gingival tissues. Results: We found clear NOD2 expression in HGFs. Upon stimulation with NOD2 agonist, muramyldipeptide (MDP), production of proinflammatory cytokines was enhanced. Moreover, MDP-induced production of proinflammatory cytokines was inhibited in a different manner by mitogen-activated protein kinase inhibitors and phosphatidylinositol 3-kinase inhibitor. Furthermore, MDP enhanced CXCL10 and CXCL11 productions by tumor necrosis factor-α (TNF-α)- or interferon-γ (IFN-γ)-stimulated HGFs, although MDP alone did not induce these chemokines. TNF-α and IFN-γ increased NOD2 expression in HGFs. In addition, we detected NOD2 expression in mononuclear cells and HGFs in periodontally diseased tissues. Conclusion: These findings indicate that MDP which induces production of cytokines and chemokines from HGFs is related to the pathogenesis of periodontal disease. [ABSTRACT FROM AUTHOR]

We have reported that CXCL16, a recently discovered transmembrane chemokine, is expressed in human gingival fibroblasts (HGF). However, it is not known whether HGF express CXCR6, the receptor for CXCL16, or CXCL16 affects HGF biology. We have shown that HGF expressed CXCR6 by reverse transcription–polymerase chain reaction and flow cytometric analysis. Moreover, we elucidated that tumour necrosis factor (TNF)-α and cytosine-guanine dinucleotide (CpG) DNA (Toll-like receptor-9 ligand) treatment enhanced CXCR6 expression by HGF. Interleukin (IL)-4, IL-13 and CpG DNA up-regulated CXCR6 expression by TNF-α-stimulated HGF. On the other hand, IL-1β and interferon-γ inhibited CXCR6 expression on TNF-α-treated HGF. CXCL16 treatment induced HGF proliferation and phosphorylation of extracellular regulated kinase (ERK) and protein kinase B (AKT) in HGF. In conclusion, HGF expressed CXCR6 functionally, because CXCL16 induced HGF proliferation and ERK and AKT phosphorylation in HGF. These results indicate that CXCL16 may play an important role in the pathogenesis and remodelling in periodontally diseased tissues. [ABSTRACT FROM AUTHOR]

Background and Objective: CXC chemokine 10 (CXCL10) activates CXC chemokine receptor 3 (CXCR3) and attracts activated T-helper 1 cells. In this study we examined the effects of cytokines on CXCL10 production by human gingival fibroblasts. Material and Methods: Human gingival fibroblasts were exposed to pro-inflammatory cytokines (interleukin-1β, tumor necrosis factor-α), a T-helper 1 cytokine (interferon-γ), T-helper 2 cytokines (interleukin-4, interleukin-13), T-helper 17 cytokines (interleukin-17A, interleukin-22) and regulatory T-cell cytokines (interleukin-10, transforming growth factor-β1) for 24 h. CXCL10 production by human gingival fibroblasts was examined by enzyme-linked immunosorbent assay. Results: Human gingival fibroblasts produced CXCL10 protein upon stimulation with interleukin-1β, tumor necrosis factor-α and interferon-γ. Treatment of human gingival fibroblasts with interferon-γ in combination with tumor necrosis factor-α or interleukin-1β resulted in a synergistic production of CXCL10. However, interleukin-4 and interleukin-13 inhibited CXCL10 production by interferon-γ-stimulated or tumor necrosis factor-α-stimulated-human gingival fibroblasts. On the other hand, interleukin-17A and interleukin-22 enhanced CXCL10 production by human gingival fibroblasts treated with interferon-γ and inhibited CXCL10 production by tumor necrosis factor-α-stimulated human gingival fibroblasts. Furthermore, the anti-inflammatory cytokine, interleukin-10, inhibited CXCL10 production by both interferon-γ- and tumor necrosis factor-α-stimulated human gingival fibroblasts, but transforming growth factor-β1 enhanced interferon-γ-mediated CXCL10 production by human gingival fibroblasts. Conclusion: These results mean that the balance of cytokines in periodontally diseased tissue may be essential for the control of CXCL10 production by human gingival fibroblasts, and the production of CXCL10 might be important for the regulation of T-helper 1 cell infiltration in periodontally diseased tissue. [ABSTRACT FROM AUTHOR]

Background and Objective: It has been reported that T helper 2 (Th2) cells are related to exacerbation of periodontal disease. However, it is uncertain how the migration of Th2 cells is controlled. In this study, we examined the expression of CC chemokine ligand 17 (CCL17), which is a Th2 chemokine, in periodontal tissues. Moreover, we investigated the effects of cytokines and toll-like receptor (TLR) ligands on the production of CCL17 by human gingival fibroblasts (HGFs). Material and Methods: We used immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) to detect CCL17 in periodontal tissues. HGFs were exposed to cytokines and TLR ligands. Expression of CCL17 was examined by RT-PCR and enzyme-linked immunosorbent assay. We used signal transduction inhibitors in some experiments. Results: Both CCL17 and its receptor, CC chemokine receptor 4 (CCR4), were expressed in diseased periodontal tissues. A combination of tumour necrosis factor α (TNF-α) and interleukin (IL)-4/IL-13 increased CCL17 expression. Moreover, treatment of HGFs with a low dose of interferon-γ (IFN-γ) in combination with TNF-α and IL-4 or IL-13 had synergistic effects on the production of CCL17, whereas a high dose of IFN-γ inhibited CCL17 production. Furthermore, Escherichia coli (E. coli) lipopolysaccharide (TLR4 ligand) and Pam3CSK4 (TLR2 ligand) inhibited CCL17 production by TNF-α + IL-4-stimulated HGFs, while CpG DNA (TLR9 ligand) enhanced TNF-α + IL-4 induced-CCL17 production by HGFs. Furthermore, a c-Jun NH2 terminal kinase (JNK) inhibitor, a phosphatidylinositol-3-kinase (PI3K) inhibitor and a nuclear factor κB (NF-κB) inhibitor inhibited CCL17 production by HGFs. Conclusion: These results suggest that the CCL17 produced by HGFs may be involved in the migration of Th2 cells into inflamed tissues, and provide evidence that CCL17 production is controlled by cytokines and TLR ligands in periodontal disease. [ABSTRACT FROM AUTHOR]

Periodontal disease is an inflammatory disorder characterized by the involvement of chemokines that are important for the recruitment of leucocytes. Several cytokines, including tumour necrosis factor alpha (TNF-α), are involved in regulating levels of chemokines in periodontal disease. CXC chemokine ligand 10 (CXCL10) is a chemokine related to the migration of T helper 1 cells. In this study, we examined CXCL10 expression in human gingival fibroblasts (HGFs). Moreover, we investigated the effects of adrenomedullin (AM), which is a multi-functional regulatory peptide, on the production of CXCL10 by HGFs. We revealed that TNF-α stimulation induced CXCL10 production by HGFs. HGFs expressed AM and AM receptors, calcitonin-receptor-like receptor (CRLR) and receptor-activity-modifying protein (RAMP) 2, mRNAs constitutively. AM treatment supressed CXCL10 production by TNF-α-stimulated HGFs. Moreover, we elucidated that AM produced by HGFs inhibited CXCL10 production by HGFs, because AM antagonist enhanced CXCL10 production by HGFs. TNF-α treatment enhanced CRLR and RAMP2 mRNA expression in HGFs. Furthermore, AM is expressed in human periodontal tissues, including both inflamed and clinically healthy tissues. These results suggest that the CXCL10 produced by HGFs may be involved in the migration of leucocytes into inflamed tissues and related to exacerbation of periodontal disease. AM might be a therapeutic target of periodontal disease, because AM can inhibit CXCL10 production by HGFs. [ABSTRACT FROM AUTHOR]

Periodontal disease is an inflammatory disorder characterized by the involvement of chemokines that are important for the recruitment of leucocytes. Several cytokines are involved in regulating levels of chemokines in periodontal disease. CXCL16 is a chemokine related to the migration of T helper 1 (Th1) cells and natural killer (NK) cells. In this study, we examined its expression in periodontal tissues. Moreover, we investigated the effects of cytokines on the production of CXCL16 by human gingival fibroblast (HGF). Reverse transcription–polymerase chain reaction (RT–PCR) analysis and immunohistochemistry revealed that CXCL16 and its receptor, CXCR6, were expressed at the mRNA and protein levels in diseased tissues. Proinflammatory cytokines [interleukin (IL)-1β, tumour necrosis factor (TNF)-α and interferon (IFN)-γ] increased the mRNA expression and release of CXCL16 in a dose-dependent manner. Moreover, treatment of HGFs with IFN-γ in combination with IL-1β had a synergistic effect on the production of CXCL16. On the other hand, IL-4 and IL-13 inhibited the IL-1β-induced CXCL16 production by HGFs. Inhibitors of A disintegrin and metalloprotease (ADAM)10 and ADAM17, a recently identified protease of CXCL16, reduced the amount of CXCL16 released from HGFs. These results suggest that the CXCL16 produced by HGFs may be involved in the migration of leucocytes into inflamed tissues, and provide evidence that CXCL16 production is controlled by cytokines in periodontal disease. [ABSTRACT FROM AUTHOR]

Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), a member of the TNF family, is a multi-functional cytokine that regulates cellular proliferation, angiogenesis, inflammation and apoptosis. In this study, we investigated TWEAK expression in periodontally diseased tissues and the effect of TWEAK on human gingival fibroblasts (HGF). Reverse transcription–polymerase chain reaction (RT–PCR) analysis and immunohistochemistry revealed that TWEAK and the TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14), mRNA and protein were expressed in periodontally diseased tissues. HGF expressed Fn14 and produced interleukin (IL)-8 and vascular endothelial growth factor (VEGF) production upon TWEAK stimulation in a dose-dependent manner. The IL-8 and VEGF production induced by TWEAK was augmented synergistically by simultaneous stimulation with transforming growth factor (TGF)-β1 or IL-1β. IL-1β and TGF-β1 enhanced Fn14 expression in a dose-dependent manner. Moreover, TWEAK induced intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression on HGF in a dose-dependent manner. The ICAM-1 expression induced by TWEAK was augmented by TGF-β1. On the other hand, the TWEAK-induced VCAM-1 expression was inhibited by TGF-β1. Phosphatidylinositol 3-kinase (PI3K) and nuclear factor-kappaB (NF-κB) inhibitor inhibit both ICAM-1 and VCAM-1 expression induced by TWEAK. However, mitogen-activated protein kinase (MEK) and c-Jun NH2-terminal kinase (JNK) inhibitor enhanced only VCAM-1 expression on HGF. These results suggest that TWEAK may be involved in the pathophysiology of periodontal disease. Moreover, in combination with IL-1β or TGF-β1, TWEAK may be related to the exacerbation of periodontal disease to induce proinflammatory cytokines and adherent molecules by HGF. [ABSTRACT FROM AUTHOR]

Anti-microbial peptides produced from mucosal epithelium appear to play pivotal roles in the host innate immune defence system in the oral cavity. In particular, human beta-defensins (hBDs) and the cathelicidin-type anti-microbial peptide, LL-37, were reported to kill periodontal disease-associated bacteria. In contrast to well-studied hBDs, little is known about the expression profiles of LL-37 in gingival tissue. In this study, the anti-microbial peptides expressed in gingival tissue were analysed using immunohistochemistry and enxyme-linked immunosorbent assay (ELISA). Immunohistochemistry revealed that neutrophils expressed only LL-37, but not hBD-2 or hBD-3, and that such expression was prominent in the inflammatory lesions when compared to healthy gingivae which showed very few or no LL-37 expressing neutrophils. Gingival epithelial cells (GEC), however, expressed all three examined anti-microbial peptides, irrespective of the presence or absence of inflammation. Moreover, as determined by ELISA, the concentration of LL-37 in the gingival tissue homogenates determined was correlated positively with the depth of the gingival crevice. Stimulation with periodontal bacteria in vitro induced both hBD-2 and LL-37 expressions by GEC, whereas peripheral blood neutrophils produced only LL-37 production, but not hBD-2, in response to the bacterial stimulation . These findings suggest that LL-37 displays distinct expression patterns from those of hBDs in gingival tissue. [ABSTRACT FROM AUTHOR]

We have demonstrated recently that CCL20 was expressed in periodontal diseased tissues and abundant CCR6 positive T cells infiltrated in periodontally diseased tissue. However, it is uncertain which cells can elicit CCL20 production. In the present study, we examined the properties of CCL20 production by human gingival fibroblasts (HGF) culture. Here, we report that interleukin-1 beta (IL-1β), tumour necrosis factor-alpha (TNF-α) and Escherichia coli lipopolysaccharide (LPS) can significantly induce the production of CCL20 by HGF. We found that TNF-α and E. coli LPS enhanced the production of CCL20 by HGF treated with IL-1β. In contrast, interferon-gamma (IFN-γ) dramatically diminished CCL20 production induced by IL-1β. Moreover, we demonstrated that nuclear factor-kappaB (NF-κB), p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinases (ERK) play an important role in mediating the production of CCL20 induced by IL-1β and TNF-α. On the other hand, we found that not only NF-κB, p38 MAPK and ERK but also c-Jun NH2-terminal kinase (JNK) are involved in CCL20 production induced by E. coli LPS. Finally, we found that HGF express CCR6, CCL20 receptor, and CCL20 induced vascular endothelial growth factor (VEGF) by HGF. Taken together, these findings that HGF will be a source of CCL20 in periodontal tissue, and the CCL20 production will be controlled by proinflammatory cytokine and bacterial LPS in periodontally diseased tissue. Thus, CCL20 by HGF might be involved in inflammatory cells infiltration, and promote the progression of periodontal disease. [ABSTRACT FROM AUTHOR]

CXCL12 is a CXC chemokine that is related to lymphocyte infiltration and angiogenesis in inflammatory sites such as arthritis. However, the expression and roles of CXCL12 in periodontal disease are uncertain. The aim of this study was to assess the expression of CXCL12 and its receptor, CXCR4, in periodontal tissue and to investigate the properties of CXCL12 and CXCR4 expression by human gingival fibroblasts (HGF). RT-PCR analysis revealed that CXCL12 and CXCR4 mRNA were expressed in both normal gingival tissues and periodontal diseased tissues. Immunohistochemistry disclosed that CXCL12 was expressed and CXCR4 positive cells were found in both normal and periodontal diseased gingival tissues. Our in vitro experiments elucidated that HGF constitutively produced CXCL12, and the levels were enhanced by stimulation with tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), transforming growth factor-β (TGF–β), regulated upon activation normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein 3α (MIP-3α). On the other hand, heat killed Porphyromonas gingivalis ( P. gingivalis) and P. gingivalis LPS reduced the CXCL12 production by HGF. Flow cytometry analysis clarified that CXCR4 was highly expressed on HGF, and CXCR4 expression was abrogated by TNF-α, IFN-γ and P. gingivalis LPS. Moreover, CXCL12 induced vascular endothelial growth factor (VEGF) production by HGF. Our results demonstrated that CXCL12 might be related to CXCR4+ cells infiltration and angiogenesis both in normal periodontal tissues and periodontal diseased tissue. P. gingivalis, a known periodontal pathogen, inhibits the production of CXCL12 and the expression of CXCR4 by HGF. This fact means that P. gingivalis may inhibit CXCR4+ cells infiltration and neovascularization in periodontal tissue and escape from the immune response. [ABSTRACT FROM AUTHOR]

The regulatory role of chemokines and chemokine receptors on specific leucocyte recruitment into periodontal diseased tissue is poorly characterized. We observed that leucocytes infiltrating inflamed gingival tissue expressed marked levels of CX3CR1. In periodontal diseased tissue, the expression of fractalkine and CX3CR1 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) and further, fractalkine was distributed mainly on endothelial cells, as shown by immunohistochemistry. Moreover, we can detect CX3CR1-expressing cells infiltrated in periodontal diseased tissue by immunohistochemical staining. Furthermore, fractalkine production by human umbilical vein endothelial cells (HUVEC) was up-regulated by pathogen-associated molecular patterns (PAMPs), includingPorphyromonas gingivalislipopolysaccharide (LPS). Thus, these findings suggested that CX3CR1 and the corresponding chemokine, fractalkine may have an important regulatory role on specific leucocyte migration into inflamed periodontal tissue. [ABSTRACT FROM AUTHOR]

SUMMARY The regulatory role of chemokines and chemokine receptors on specific lymphocyte recruitment into periodontal diseased tissue is poorly characterized. We observed that lymphocytes infiltrating inflamed gingival tissue expressed marked levels of CCR6. In periodontal diseased tissue, the expression of MIP-3α mRNA was detected by RT-PCR and further, MIP-3α was distributed in the basal layer of gingival epithelial cells, microvascular endothelial cells and the areas of inflammatory cells as shown by immunohistochemistry. Moreover, CCR6-expressing cells infiltrated into periodontal diseased tissue, and the proportion of CCR6-positive CD4+ T cells was significantly elevated in periodontal diseased tissue compared with peripheral blood in the same patients. Furthermore, gingival lymphocytes isolated from patients showed migration toward MIP-3α in an in vitro chemotaxis assay in which migration was abrogated by specific antibody to CCR6. Thus, these findings suggested that CCR6 and the corresponding chemokine, MIP-3α may have an important regulatory role in specific lymphocyte migration into inflamed periodontal tissue. [ABSTRACT FROM AUTHOR]