Macrophage inflammatory protein 3alpha-CC chemokine receptor 6 interactions play an important role in CD4+ T-cell accumulation in periodontal diseased tissue

A high-throughput, 28-day, microfluidic model of gingival tissue inflammation and recovery

Nearly half of American adults suffer from gum disease, including mild inflammation of gingival tissue, known as gingivitis. Currently, advances in therapeutic treatments are hampered by a lack of mechanistic understanding of disease progression in physiologically relevant vascularized tissues. To address this, we present a high-throughput microfluidic organ-on-chip model of human gingival tissue containing keratinocytes, fibroblast and endothelial cells. We show the triculture model exhibits physiological tissue structure, mucosal barrier formation, and protein biomarker expression and secretion over several weeks. Through inflammatory cytokine administration, we demonstrate the induction of inflammation measured by changes in barrier function and cytokine secretion. These states of inflammation are induced at various time points within a stable culture window, providing a robust platform for evaluation of therapeutic agents. These data reveal that the administration of specific small molecule inhibitors mitigates the inflammatory response and enables tissue recovery, providing an opportunity for identification of new therapeutic targets for gum disease with the potential to facilitate relevant preclinical drug efficacy and toxicity testing.

Streptococcus gordonii-induced miRNAs regulate CCL20 responses in human oral epithelial cells

The mechanisms through which oral commensal bacteria mitigates uncontrolled inflammatory responses of the oral mucosa remain unknown. Here, we show that representative oral bacterial species normally associated with oral health [S. gordonii (Sg), V. parvula (Vp); A. naeslundii (An); C. sputigena (Cs), and N. mucosa (Nm)] enhanced differential chemokine responses in oral epithelial cells (OECs), with some bacteria (An, Vp, and Nm) inducing higher chemokine levels (CXCL1, CXCL8) than others (Sg, Cs). Although all bacterial species (except Cs) increased CCL20 mRNA levels consistent with protein elevations in cell lysates, only An, Vp and Nm induced higher CCL20 secretion, similar to the effect of the oral pathogen F. nucleatum (Fn). In contrast, most CCL20 remained associated with OECs exposed to Sg and negligible amounts released into the cell supernatants. Consistently, Sg attenuated An-induced CCL20. MiR-4516 and miR-663a were identified as Sg-specifically induced miRNAs modulating validated targets of chemokine-associated pathways. Cell transfection with miR-4516 and miR-663a decreased An- and Fn-induced CCL20. MiRNAs up-regulation and attenuation of An-induced CCL20 by Sg were reversed by catalase. Up-regulation of both miRNAs was specifically enhanced by oral streptococci H₂O₂-producers. These findings suggest that CCL20 levels produced by OECs in response to bacterial challenge are regulated by Sg-induced miR-4516 and miR-663a in a mechanism that involves hydrogen peroxide. This type of molecular mechanism could partly explain the central role of specific oral streptococcal species in balancing inflammatory and antimicrobial responses given the critical role of CCL20 in innate (antimicrobial) and adaptive immunity (modulates Th17 responses).

Anti-Inflammatory and Protective Effects of Juncus effusus L. Water Extract on Oral Keratinocytes

Periodontitis is a chronic inflammatory disease caused by periodontopathogenic bacteria that form biofilms in periodontal pockets. The gingival epithelium acts as the first physical barrier in fighting attacks by periodontopathogenic pathogens, such as the primary etiological agent Porphyromonas gingivalis, and various exogenous chemicals, as well as regulates the local innate immune responses. Therefore, the development of novel oral care products to inhibit inflammatory reactions caused by bacterial infection and protect the gingival epithelium is necessary. Juncus effusus L. has generally been used as an indigenous medicine, such as a diuretic, an antipyretic, and an analgesic, in ancient practice. In this study, we examined the effects of a water extract from J. effusus L. on the inhibition of the inflammatory reaction elicited by bacterial infection and protection of the oral epithelium by chemical irritation. Pretreatment of oral epithelial cells with the water extract from J. effusus L. significantly reduced P. gingivalis or its lipopolysaccharide- (LPS-) mediated production of chemokines (interleukin-8 and C-C-chemokine ligand20) in a concentration-dependent manner with comparable to or greater effects than epigallocatechin gallate and protected oral epithelial cells from injury by chemical irritants, cetylpyridinium chloride, and benzethonium chloride. Moreover, the water extract from J. effusus L. in the presence of antimicrobial agents or antifibrinolytics already used as ingredients in mouthwash could significantly reduce the production of chemokines from P. gingivalis LPS-stimulated oral epithelial cells in a concentration-dependent manner. These findings suggest that the water extract from J. effusus L. is potentially useful for oral care to prevent oral infections, such as periodontal infections, and maintain oral epithelial function.

Decreased MIP-3α Production from Antigen-Activated PBMCs in Symptomatic HIV-Infected Subjects

CD4⁺ CCR6⁺ T cells are highly susceptible to HIV infection, and a high cytokine producing CCR6⁺ T cell subset is selectively lost during HIV infection. The CCR6 chemokine MIP-3α (CCL20) is produced at sites of infection in SIV animal models. Recently, we have shown that MIP-3α inhibits HIV replication. This inhibition of HIV infection is mediated by CCR6 signaling and eventuates in increased APOBEC3G expression. Since there are few existing reports on the role of MIP-3α in health or disease, we studied its production by PBMCs from HIV-seronegative and HIV+ subjects. We evaluated the ability of PBMCs to produce MIP-3α in response to antigen stimulation using cells obtained from two groups: one composed of HIV-seronegative subjects (n = 16) and the other composed of HIV+ subjects (n = 58), some asymptomatic and some with clinically defined AIDS. Antigens included fragment C of the tetanus toxin, Candida albicans, whole-inactivated HIV, and HIV p24. MIP-3α was detected by ELISA in tissue culture supernatants of antigen-stimulated PBMCs. MIP-3α production by antigen-stimulated PBMCs was readily measured for HIV-negative subjects and for HIV-seropositive asymptomatic subjects, but not for patients with AIDS. These results suggest that subversion of the MIP-3α-CCR6 axis by HIV during the course of infection contributes to the loss of immune function that eventually leads to AIDS.

Carnosic acid inhibits inflammatory cytokines production in human periodontal ligament cells

OBJECTIVES

Carnosic acid (CA), which is one of bioactive compounds from rosemary, has various biological activities. However, the effect of CA on periodontal ligament cells is still uncertain. The aim of this study was to examine the effects of CA on inflammatory cytokines production in human periodontal ligament cells.

METHODS

Cytokine and chemokine levels were measured by ELISA. Activations of signal transduction pathway were determined by Western blotting.

RESULTS

Treatment of CA decreased inflammatory cytokines such as interleukin (IL)-6, CXC chemokine ligand (CXCL)10, CC chemokine ligand (CCL)2, and CCL20 productions in IL-1β or tumor necrosis factor (TNF)-α-stimulated human periodontal ligament cells in a dose-dependent manner. Moreover, we found that CA could suppress Jun-N-terminal kinase (JNK) pathway, nuclear factor (NF)-κB pathway and signal transducer and activator of transcription (STAT)3 pathway activation in IL-1β or TNF-α-stimulated human periodontal ligament cells.

CONCLUSION

The results of this study suggest that CA has anti-inflammatory effects in human periodontal ligament cells by inhibiting JNK, NF-κB and STAT3 pathways.

Anti-inflammatory effects of olanexidine gluconate on oral epithelial cells

Background

Periodontitis is a biofilm-induced chronic inflammatory condition of the periodontium. Chemokines produced by the innate and acquired immune responses play a significant role in disease progression. Reducing biofilm formation and inflammatory response caused by chemokines is vital for preventing and treating periodontitis. Previously, we observed that treatment with 0.1% olanexidine gluconate (OLG) inhibited biofilm formation on saliva-coated hydroxyapatite. This study aimed to evaluate the anti-inflammatory effect of OLG on oral epithelial cells.

Methods

We examined if OLG could inhibit the inflammatory responses caused by Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) and heat-killed P. gingivalis in immortalized human oral keratinocytes (RT7).

Results

Treatment of RT7 with non-cytotoxic OLG concentrations significantly inhibited the production of inflammatory chemokines such as interleukin 8 (IL-8), C-C motif ligand 20 (CCL20), and growth-related oncogene protein-α (GRO-α), which are stimulated by P. gingivalis LPS in a concentration-dependent manner. Moreover, the inhibitory effects were observed regardless of the treatment time with P. gingivalis LPS (6, 12, or 24 h). OLG also significantly inhibited chemokine production stimulated by heat-killed P. gingivalis.

Conclusions

The findings of this study suggest that treatment with OLG inhibits chronic inflammatory reactions in oral mucosal cells, such as periodontitis, caused by oral bacteria.

Systemic Antibiotic Therapy Reduces Circulating Inflammatory Dendritic Cells and Treg-Th17 Plasticity in Periodontitis

Periodontitis (PD) is a common dysbiotic inflammatory disease that leads to local bone deterioration and tooth loss. PD patients experience low-grade bacteremias with oral microbes implicated in the risk of heart disease, cancer, and kidney failure. Although Th17 effectors are vital to fighting infection, functional imbalance of Th17 effectors and regulatory T cells (Tregs) promote inflammatory diseases. In this study, we investigated, in a small pilot randomized clinical trial, whether expansion of inflammatory blood myeloid dendritic cells (DCs) and conversion of Tregs to Th17 cells could be modulated with antibiotics (AB) as part of initial therapy in PD patients. PD patients were randomly assigned to either 7 d of peroral metronidazole/amoxicillin AB treatment or no AB, along with standard care debridement and chlorhexidine mouthwash. 16s ribosomal RNA analysis of keystone pathogen Porphyromonas gingivalis and its consortium members Fusobacterium nucleatum and Streptococcus gordonii confirmed the presence of all three species in the reservoirs (subgingival pockets and blood DCs) of PD patients before treatment. Of the three species, P. gingivalis was reduced in both reservoirs 4-6 wk after therapy. Further, the frequency of CD1C⁺CCR6⁺ myeloid DCs and IL-1R1 expression on IL-17A⁺FOXP3⁺CD4⁺ T cells in PD patients were reduced to healthy control levels. The latter led to decreased IL-1β-stimulated Treg plasticity in PD patients and improvement in clinical measures of PD. Overall, we identified an important, albeit short-term, beneficial role of AB therapy in reducing inflammatory DCs and Treg-Th17 plasticity in humans with PD.

Antibiofilm and Anti-Inflammatory Activities of Houttuynia cordata Decoction for Oral Care

Dental biofilms that form in the oral cavity play a critical role in the pathogenesis of several infectious oral diseases, including dental caries, periodontal disease, and oral candidiasis. Houttuynia cordata (HC, Saururaceae) is a widely used traditional medicine, for both internal and external application. A decoction of dried HC leaves (dHC) has long been consumed as a health-promoting herbal tea in Japan. We have recently reported that a water solution of HC poultice ethanol extract (wHCP) exerts antimicrobial and antibiofilm effects against several important oral pathogens. It also exhibits anti-inflammatory effects on human keratinocytes. In our current study, we examined the effects of dHC on infectious oral pathogens and inflammation. Our results demonstrated that dHC exerts moderate antimicrobial effects against methicillin-resistant Staphylococcus aureus (MRSA) and other oral microorganisms. dHC also exhibited antibiofilm effects against MRSA, Fusobacterium nucleatum (involved in dental plaque formation), and Candida albicans and inhibitory effects on interleukin-8, CCL20, IP-10, and GROα productions by human oral keratinocytes stimulated by Porphyromonas gingivalis lipopolysaccharide (a cause of periodontal disease), without cytotoxic effects. This suggests that dHC exhibits multiple activities in microorganisms and host cells. dHC can be easily prepared and may be effective in preventing infectious oral diseases.

Triglyceride-rich lipoprotein lipolysis products increase blood-brain barrier transfer coefficient and induce astrocyte lipid droplets and cell stress

Elevation of blood triglycerides, primarily as triglyceride-rich lipoproteins (TGRL), has been linked to cerebrovascular inflammation, vascular dementia, and Alzheimer's disease (AD). Brain microvascular endothelial cells and astrocytes, two cell components of the neurovascular unit, participate in controlling blood-brain barrier (BBB) permeability and regulating neurovascular unit homeostasis. Our studies showed that infusion of high physiological concentrations of TGRL lipolysis products (TGRL + lipoprotein lipase) activate and injure brain endothelial cells and transiently increase the BBB transfer coefficient (K_i = permeability × surface area/volume) in vivo. However, little is known about how blood lipids affect astrocyte lipid accumulation and inflammation. To address this, we first demonstrated TGRL lipolysis products increased lipid droplet formation in cultured normal human astrocytes. We then evaluated the transcriptional pathways activated in astrocytes by TGRL lipolysis products and found upregulated stress and inflammatory-related genes including activating transcription factor 3 (ATF3), macrophage inflammatory protein-3α (MIP-3α), growth differentiation factor-15 (GDF15), and prostaglandin-endoperoxide synthase 2 (COX2). TGRL lipolysis products also activated the JNK/cJUN/ATF3 pathway, induced endoplasmic reticulum stress protein C/EBP homologous protein (CHOP), and the NF-κB pathway, while increasing secretion of MIP-3α, GDF15, and IL-8. Thus our results demonstrate TGRL lipolysis products increase the BBB transfer coefficient (K_i), induce astrocyte lipid droplet formation, activate cell stress pathways, and induce secretion of inflammatory cytokines. Our observations are consistent with evidence for lipid-induced neurovascular injury and inflammation, and we, therefore, speculate that lipid-induced astrocyte injury could play a role in cognitive decline.

Chemokines in Oral Inflammatory Diseases: Apical Periodontitis and Periodontal Disease

The inflammatory oral diseases are characterized by the persistent migration of polymorphonuclear leukocytes, monocytes, lymphocytes, plasma and mast cells, and osteoblasts and osteoclasts. In the last decade, there has been a great interest in the mediators responsible for the selective recruitment and activation of these cell types at inflammatory sites. Of these mediators, the chemokines have received particular attention in recent years. Chemokine messages are decoded by specific receptors that initiate signal transduction events, leading to a multitude of cellular responses, including chemotaxis and activation of inflammatory and bone cells. However, little is known about their role in the pathogenesis of inflammatory oral diseases. The purpose of this review is to summarize the findings regarding the role of chemokines in periapical and periodontal tissue inflammation, and the integration, into experimental models, of the information about the role of chemokines in human diseases.

Preventive Effects of Houttuynia cordata Extract for Oral Infectious Diseases

Houttuynia cordata (HC) (Saururaceae) has been used internally and externally as a traditional medicine and as an herbal tea for healthcare in Japan. Our recent survey showed that HC poultice (HCP) prepared from smothering fresh leaves of HC had been frequently used for the treatment of purulent skin diseases with high effectiveness. Our experimental study also demonstrated that ethanol extract of HCP (eHCP) has antibacterial, antibiofilm, and anti-inflammatory effects against S. aureus which caused purulent skin diseases. In this study, we focused on novel effects of HCP against oral infectious diseases, such as periodontal disease and dental caries. We determined the antimicrobial and antibiofilm effects of water solution of HCP ethanol extract (wHCP) against important oral pathogens and investigated its cytotoxicity and anti-inflammatory effects on human oral epithelial cells. wHCP had moderate antimicrobial effects against some oral microorganisms and profound antibiofilm effects against Fusobacterium nucleatum, Streptococcus mutans, and Candida albicans. In addition, wHCP had no cytotoxic effects and could inhibit interleukin-8 and CCL20 productions by Porphyromonas gingivalis lipopolysaccharide-stimulated human oral keratinocytes. Our findings suggested that wHCP may be clinically useful for preventing oral infectious diseases as a mouthwash for oral care.

Macrophage Inflammatory Protein-3 Alpha (MIP-3α)/CCL20 in HIV-1-Infected Individuals

OBJECTIVE

Uncontrolled HIV infection progresses to the depletion of systemic and mucosal CD4 and AIDS. Early HIV infection may be associated with increases in the concentration of MIP-3α in the blood and gut fluids. MIP-3α/CCL20 is the only chemokine known to interact with CCR6 receptors which are expressed on immature dendritic cells and both effector and memory CD8⁺ and CD4⁺ T cells. The role and prognostic value of blood levels of MIP-3α in HIV-infected individuals has yet to be described.

METHODS

We determined the serum levels of MIP-3α, and IFN-γ, in 167 HIV-1-infected and 27 HIV-1-uninfected men participating in the Multicenter AIDS Cohort Study (MACS). The blood biomarkers were measured using enzyme-linked immunosorbent assays (ELISA) and the cell phenotypes using flow cytometry.

RESULTS

Median serum levels of MIP-3α in HIV-1-infected and uninfected men was significantly different (p<0.0001) and were 21.3 pg/mL and 6.4 pg/mL respectively. The HIV-1-infected men with CD4⁺ T cell count <200 cells/μL showed the highest median serum MIP-3α (23.1 pg/mL). Serum levels of MIP-3α in HIV-1 infected (n=167) were negatively correlated with absolute number of CD4⁺ T cell (p=0.01) and were positively correlated with CD38 molecules on CD8⁺ T cells (p=0.0002) and with serum levels of IFN-γ (0.006).

CONCLUSION

Serum levels of MIP-3α concomitantly increase with plasma levels of IFN-γ, CD38 expression on CD8⁺ T cells, and decreased of absolute CD4⁺ T cells in HIV-1-infected men. A higher blood level of MIP-3α may be representation of locally high level of MIP-3α and more recruitment of immature dendritic cell at site of infection. Involvement of CCR6/CCL20 axis and epithelial cells at the recto-colonel level may enhance sexual transmission of HIV-1 in MSM and may be useful as a prognostic marker in HIV-1-infection and AIDS.

Expression of P2X7 ATP receptor mediating the IL8 and CCL20 release in human periodontal ligament stem cells

ATP is released by human periodontal ligament cells (hPDLCs) and has been shown to regulate PDL regeneration and responses to mechanical stress through activation of P2Y receptors. This nucleotide, however, has also been reported to trigger the pro-inflammatory cascade by inducing the maturation and/or release of chemokines/cytokines from various cell types mainly via P2X7 receptors. Much less is known on the possible role of ATP in stem cells deriving from PDL (hPDLSCs) which are considered to be a promising tool for cell-based therapy to restore lesions. Given the role played by P2X7 in pathophysiological conditions, in this study we investigated the expression of P2X7 ATP receptors in hPDLSCs. The results obtained showed that hPDLSCs express P2X7 receptors evaluated by means of cytofluorimetric, immunohistochemistry, reverse transcriptase-PCR, and Western blot analyses. P2X7 ligation by 2',3'-(benzoyl-4-benzoyl)-ATP (BzATP), a specific receptor agonist, was followed by an increase in intracellular Ca2+ and in the uptake of ethidium bromide. These effects were dramatically reduced by oxidized ATP (oATP), the P2X7 irreversible inhibitor, suggesting that the P2X7 is the functional receptor involved. At 24 h treatment of hPDLSCs with BzATP it enhanced the release of the pro-inflammatory agents IL8 and CCL20, without influencing cell viability. These effects were counteracted by pre-treating the cells with oATP or with A-740003, a selective and potent P2X7 competitive antagonist. Collectively, these results indicated that extracellular ATP mediate a pro-inflammatory response via P2X7 receptors in hPDLSCs opening a further approach to control hPDLSCs behavior in their possible application as therapeutic tool.

IL-6 trans-signaling enhances CCL20 production from IL-1β-stimulated human periodontal ligament cells

CC chemokine ligand 20 (CCL20) plays a central role in the recruitment of CCR6-expressing cells, including Th17 cells which are related to bone resorption in periodontal lesions and thus in the development of periodontal disease. IL-6 is an important cytokine that is associated with the pathogenesis of periodontitis. However, the effect of IL-6 on CCL20 production is uncertain. The aim of this study was to examine whether IL-6 could modify CCL20 expression in human periodontal ligament cells (HPDLCs). HPDLCs expressed gp130 but did not express IL-6R on the surface of HPDLCs. So, IL-6 trans-signaling is important to recognize IL-6 by HPDLCs. IL-6/sIL-6R stimulation enhanced CCL20 production in IL-1β-stimulated HPDLCs. IL-6 produced from IL-1β-stimulated HPDLCs with sIL-6R could increase CCL20 production in HPDLCs with sIL-6R. Signal transducer and activator of transcription (STAT)3 activation was related to CCL20 production in IL-1β and IL-6/sIL-6R-stimulated HPDLCs. Our data suggests that HPDLCs, in response to IL-6, sIL-6R, and IL-1β, may shift chemokine production to that favoring CCR6-expressing cells recruitment in periodontal lesions.

Relationship between chemokines and dendritic cells in human chronic periodontitis

BACKGROUND

The purpose of this study was to evaluate the relationship between chemokines and dendritic cells (DCs) in human chronic periodontitis (CP).

METHODS

Gingival samples were obtained from 23 individuals with CP, and six samples of normal mucosa (NM) overlapping the third molar were used to control for the chemokine levels. Periodontal examination was conducted. Immunohistochemistry was performed for Factor XIIIa(+) and cluster of differentiation (CD)1a(+) immature DCs and CD83(+) mature DCs. Levels of the CC chemokine ligand (CCL)2, CCL3, CCL5, CCL19, CCL20, and CXC chemokine ligand (CXCL)8 were measured in gingival tissues using enzyme-linked immunosorbent assay. Inflammatory infiltrate, DCs, chemokines, classification of human CP, and clinical parameters were correlated and compared.

RESULTS

The expression of CCL2 and CCL20 was positively correlated with increased densities of CD1a(+) DCs. CCL3 and CXCL8 were positively related to the clinical attachment level. CCL3, CCL5, CCL19, and CXCL8 levels increased in the gingival samples of patients with CP compared with NM, whereas CCL20 levels increased in advanced CP compared with mild-moderate CP.

CONCLUSIONS

More CD1a(+) immature DCs are related to CCL2 and CCL20. CCL3 and CXCL8 chemokines are related to a greater severity of human CP.

EBV infection is common in gingival epithelial cells of the periodontium and worsens during chronic periodontitis

An amplifying role for oral epithelial cells (ECs) in Epstein-Barr Virus (EBV) infection has been postulated to explain oral viral shedding. However, while lytic or latent EBV infections of oro/nasopharyngeal ECs are commonly detected under pathological conditions, detection of EBV-infected ECs in healthy conditions is very rare. In this study, a simple non-surgical tissue sampling procedure was used to investigate EBV infection in the periodontal epithelium that surrounds and attaches teeth to the gingiva. Surprisingly, we observed that the gingival ECs of the periodontium (pECs) are commonly infected with EBV and may serve as an important oral reservoir of latently EBV-infected cells. We also found that the basal level of epithelial EBV-infection is significantly increased in chronic periodontitis, a common inflammatory disease that undermines the integrity of tooth-supporting tissues. Moreover, the level of EBV infection was found to correlate with disease severity. In inflamed tissues, EBV-infected pECs appear to be prone to apoptosis and to produce larger amounts of CCL20, a pivotal inflammatory chemokine that controls tissue infiltration by immune cells. Our discovery that the periodontal epithelium is a major site of latent EBV infection sheds a new light on EBV persistence in healthy carriers and on the role of this ubiquitous virus in periodontitis. Moreover, the identification of this easily accessible site of latent infection may encourage new approaches to investigate and monitor other EBV-associated disorders.

TLR3 agonist enhances CC chemokine ligand 20 production in IL-1β-stimulated human gingival fibroblasts

Viruses are related to the etiology of periodontitis. However, the role of viruses on Th17 cells infiltration in periodontitis lesions is unknown. Therefore, we examined the effects of TLR3 ligand on CCL20, which is related to Th17 cells migration, production in human gingival fibroblasts (HGFs). Polyinosinic-polycytidylic acid (Poly I:C), which is a TLR3 agonist, stimulation could moderately induce CCL20 production in HGFs. Poly I:C synergistically enhanced CCL20 expression from IL-1β-stimulated HGFs. Inhibitors of p38 MAPK, extracellular signal-regulated kinase (ERK), c-Jun N terminal kinase (JNK), and NF-κB significantly inhibited CCL20 production in Poly I:C/IL-1β-stimulated HGFs. Western blot analysis disclosed phosphorylation of p38 MAPK, JNK, and IκB-α were enhanced in Poly I:C/IL-1β-treated HGFs. These data suggested that virus infection is related to Th17 cells migration in periodontitis lesion to induce CCL20 production in HGFs via TLR3. Therefore, our results indicated that virus might be important pathogen in periodontal disease.

Irsogladine maleate regulates the inflammatory related genes in human gingival epithelial cells stimulated by Aggregatibacter actinomycetemcomitans

Periodontitis is an infectious inflammatory disease. Our previous studies have revealed that irsogladine maleate (IM) regulates intercellular junctional function and chemokine secretion in gingival epithelium, resulting in the suppression of the onset of periodontal disease in a rat model. Therefore, it is plausible that IM is a promising preventive remedy for periodontal disease. In this study, to gain a better understanding of IM in gingival epithelial cells, we employed a DNA microarray analysis. More specifically, human gingival epithelial cells (HGEC) were exposed to Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in the presence or absence of IM. Then, a human genome focus array was used. A. actinomycetemcomitans facilitated the expression of several inflammatory-related genes, including these for matrix metalloproteinase (MMP)-3, interleukin (IL)-6, and intercellular adhesion molecule-1 (ICAM-1) in HGEC, while these mRNA levels were attenuated by IM treatment. Importantly, consistent with mRNA levels, immunoblotting, immunofluorescence staining and ELISA analysis indicated that IM also abrogated the A. actinomycetemcomitans-induced increase in MMP-3, IL-6, and ICAM-1 at the protein level. In addition, inhibition of the ERK or p38 MAP kinase signaling cascade, previously reported to be disturbed by IM treatment in HGEC, clearly blocked A. actinomycetemcomitans-induced MMP-3, IL-6, or ICAM-1 protein expression. Moreover, animal study revealed that IM-pretreatment inhibited the A. actinomycetemcomitans-induced increase of ICAM-1 in gingival junctional epithelium. Taken together, these results suggested that IM can regulate inflammatory responses in HGEC by inhibiting the ERK or p38 MAP kinase signaling cascade, which may result in suppression of inflammation in gingival tissue, thereby contributing to the prevention of periodontitis.

Tumor necrosis factor-like weak inducer of apoptosis increases CC chemokine ligand 20 production in interleukin 1β-stimulated human gingival fibroblasts

CC chemokine ligand 20 (CCL20) is related to T-helper (Th)-17 cell migration, and Th17 cells play important roles in exacerbation in periodontal disease. However, the effect of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) on CCL20 production is unknown. In this study, we examined the mechanisms of TWEAK in combination with interleukin (IL)-1β-induced CCL20 production in human gingival fibroblasts (HGFs). TWEAK alone did not induce CCL20 production in HGFs. However, TWEAK enhanced CCL20 expression from IL-1β-stimulated HGFs in a dose-dependent manner. Inhibitors of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), protein kinase B (Akt), and nuclear factor κB (NF-κB) significantly inhibited CCL20 production in TWEAK and IL-1β-stimulated HGFs. Western blot analysis revealed that phosphorylations of ERK, Akt, and inhibitor of NF-κB were enhanced in TWEAK and IL-1β-treated HGFs. These data suggest that TWEAK is positively related to Th17 cell migration in periodontally diseased tissues to enhance CCL20 production in IL-1β-stimulated HGFs.

Yeast two-hybrid screening of proteins interacting with plasmin receptor subunit: C-terminal fragment of annexin A2

AIM

To identify proteins that interact with the C-terminal fragment of annexin A2 (A2IC), generated by plasmin cleavage of the plasmin receptor, a heterotetramer (AA2t) containing annexin A2.

METHODS

The gene that encodes the A2IC fragment was obtained from PCR-amplified cDNA isolated from human monocytes, and was ligated into the pBTM116 vector using a DNA ligation kit. The resultant plasmid (pBTM116-A2IC) was sequenced with an ABI PRISM 310 Genetic Analyzer. The expression of an A2IC bait protein fused with a LexA-DNA binding domain (BD) was determined using Western blot analysis. The identification of proteins that interact with A2IC and are encoded in a human monocyte cDNA library was performed using yeast two-hybrid screening. The DNA sequences of the relevant cDNAs were determined using an ABI PRISM BigDye terminator cycle sequencing ready reaction kit. Nucleotide sequence databases were searched for homologous sequences using BLAST search analysis (http://www.ncbi.nlm.nih.gov). Confirmation of the interaction between the protein LexA-A2IC and each of cathepsin S and SNX17 was conducted using a small-scale yeast transformation and X-gal assay.

RESULTS

The yeast transformed with plasmids encoding the bait proteins were screened with a human monocyte cDNA library by reconstituting full-length transcription factors containing the GAL4-active domain (GAL4-AD) as the prey in a yeast two-hybrid approach. After screening 1×10(7) clones, 23 independent β-Gal-positive clones were identified. Sequence analysis and a database search revealed that 15 of these positive clones matched eight different proteins (SNX17, ProCathepsin S, RPS2, ZBTB4, OGDH, CCDC32, PAPD4, and actin which was already known to interact with annexin A2).

CONCLUSION

A2IC A2IC interacts with various proteins to form protein complexes, which may contribute to the molecular mechanism of monocyte activation induced by plasmin. The yeast two-hybrid system is an efficient approach for investigating protein interactions.

Interleukin (IL)-17A synergistically enhances CC chemokine ligand 20 production in IL-1β-stimulated human gingival fibroblasts

CC chemokine ligand 20 (CCL20) plays a pivotal role in the recruitment of T-helper (Th)-17 cells and thus in the development of periodontal disease, but the effect of simultaneous interleukin (IL)-17A and IL-1β stimulation on CCL20 production in human gingival fibroblasts (HGFs) are not known. In this study, we investigated the mechanisms of IL-1β- and IL-17A-induced CCL20 production in HGFs. IL-17A synergistically enhanced CCL20 production from IL-1β-stimulated HGFs in a concentration-dependent manner. Extracellular signal-regulated kinase (ERK) and inhibitor of nuclear factor (NF)-κB-α phosphorylation were increased in IL-1β- and IL-17A-stimulated HGFs. Inhibitors of or ERK and NF-κB decreased IL-1β- and IL-17A-induced CCL20 production. IL-1β stimulation elevated IL-17 receptor C expression on HGFs. These data suggest that IL-1β is actively related to Th17 cell migration into peripheral tissues to induce production of the Th17 chemokine, CCL20. Therefore, IL-1β might be a therapeutic target for Th17-related diseases, such as periodontal disease and arthritis.

Fusobacterium nucleatum and human beta-defensins modulate the release of antimicrobial chemokine CCL20/macrophage inflammatory protein 3α

Cells of the innate immune system regulate immune responses through the production of antimicrobial peptides, chemokines, and cytokines, including human beta-defensins (hBDs) and CCL20. In this study, we examined the kinetics of primary human oral epithelial cell (HOEC) production of CCL20 and hBDs in response to Fusobacterium nucleatum, a commensal bacterium of the oral cavity, which we previously showed promotes HOEC induction of hBDs. HOECs secrete maximal levels of CCL20 at 6 h, following stimulation by F. nucleatum cell wall (FnCW). The kinetics of CCL20 release is distinct from that of hBD-2 and -3, which peaks after 24 h and 48 h of FnCW stimulation, respectively. FnCW-induced release of CCL20 by HOECs requires both transcriptional and translational activation. Release of CCL20 by HOECs is inhibited by brefeldin A, suggesting that it is secreted through a vesicle transport pathway. Other epithelium-derived agents that FnCW induces, such as hBD-2, hBD-3, tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), are also able to release CCL20. By focusing on mitogen-activated protein kinases, we show that both extracellular signal-regulated kinase 1/2 and p38, but not JNK, are required for hBD-, TNF-α-, and IL-1β-induced secretion of CCL20 by HOECs. The ability of FnCW and its induced hBDs to produce proinflammatory cytokines and CCL20 suggests the broad role of F. nucleatum and human antimicrobial peptides in primary immune responses elicited by oral epithelium.

Black tea polyphenol inhibits CXCL10 production in oncostatin M-stimulated human gingival fibroblasts

CXC chemokine ligand 10 (CXCL10) plays an important role in the infiltration of Th1 cells and thus in the exacerbation of periodontal disease. Theaflavin-3,3'-digallate (TFDG), polyphenol in black tea, has some beneficial effects but the effect of TFDG on CXCL10 production from human gingival fibroblasts (HGFs) is uncertain. In this study, we investigated the mechanisms by which TFDG may inhibit oncostatin M (OSM)-induced CXCL10 production in human gingival fibroblasts. TFDG prevented OSM-mediated CXCL10 production by HGFs in a dose dependent manner. TFDG significantly inhibited OSM-induced phosphorylation of c-Jun N terminal kinase (JNK), protein kinase B (Akt) (Ser473) that are related to CXCL10 production from OSM-stimulated HGFs. In addition, TFDG suppressed OSM receptor (OSMR) β expression on HGFs. These data provide a novel mechanism where the black tea flavonoid, theaflavin, could provide direct benefits in periodontal disease.

Immune response of macrophages from young and aged mice to the oral pathogenic bacterium Porphyromonas gingivalis

Periodontal disease is a chronic inflammatory gum disease that in severe cases leads to tooth loss. Porphyromonas gingivalis (Pg) is a bacterium closely associated with generalized forms of periodontal disease. Clinical onset of generalized periodontal disease commonly presents in individuals over the age of 40. Little is known regarding the effect of aging on inflammation associated with periodontal disease. In the present study we examined the immune response of bone marrow derived macrophages (BMM) from young (2-months) and aged (1-year and 2-years) mice to Pg strain 381. Pg induced robust expression of cytokines; tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10, chemokines; neutrophil chemoattractant protein (KC), macrophage colony stimulating factor (MCP)-1, macrophage inflammatory protein (MIP)-1α and regulated upon activation normal T cell expressed and secreted (RANTES), as well as nitric oxide (NO, measured as nitrite), and prostaglandin E2 (PGE2) from BMM of young mice. BMM from the 2-year age group produced significantly less TNF-α, IL-6 and NO in response to Pg as compared with BMM from 2-months and 1-year of age. We did not observe any difference in the levels of IL-1β, IL-10 and PGE2 produced by BMM in response to Pg. BMM from 2-months and 1-year of age produced similar levels of all chemokines measured with the exception of MCP-1, which was reduced in BMM from 1-year of age. BMM from the 2-year group produced significantly less MCP-1 and MIP-1α compared with 2-months and 1-year age groups. No difference in RANTES production was observed between age groups. Employing a Pg attenuated mutant, deficient in major fimbriae (Pg DPG3), we observed reduced ability of the mutant to stimulate inflammatory mediator expression from BMMs as compared to Pg 381, irrespective of age. Taken together these results support senescence as an important facet of the reduced immunological response observed by BMM of aged host to the periodontal pathogen Pg.

Catechins inhibit CXCL10 production from oncostatin M-stimulated human gingival fibroblasts

CXC chemokine ligand 10 (CXCL10) plays a pivotal role in the recruitment of Th1 cells and, thus, in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins derived from green tea, have multiple beneficial effects, but the effects of catechins on CXCL10 production from human gingival fibroblasts (HGFs) is not known. In this study, we investigated the mechanisms by which EGCG and ECG inhibit oncostatin M (OSM)-induced CXCL10 production in HGFs. HGFs constitutively expressed glycoprotein 130 and OSM receptor beta (OSMR beta), which are OSM receptors. OSM increased CXCL10 production in a concentration-dependent manner. EGCG and ECG prevented OSM-mediated CXCL10 production by HGFs. Inhibitors of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase (JNK), phosphatidylinositol-3-OH kinase and signal transducer and activator of transcription (STAT)3 decreased OSM-induced CXCL10 production. EGCG significantly prevented OSM-induced phosphorylation of JNK, Akt (Ser473) and STAT3 (Tyr705 and Ser727). ECG prevented phosphorylation of JNK and Akt (Ser473). In addition, EGCG and ECG attenuated OSMR beta expression on HGFs. These data provide a novel mechanism through which the green tea flavonoids, catechins, can provide direct benefits in periodontal disease.

Rapid myeloid cell transcriptional and proteomic responses to periodontopathogenic Porphyromonas gingivalis

Long-lived monocytes, macrophages, and dendritic cells (DCs) are Toll-like receptor-expressing, antigen-presenting cells derived from a common myeloid lineage that play key roles in innate and adaptive immune responses. Based on immunohistochemical and molecular analyses of inflamed tissues from patients with chronic destructive periodontal disease, these cells, found in the inflammatory infiltrate, may drive the progressive periodontal pathogenesis. To investigate early transcriptional signatures and subsequent proteomic responses to the periodontal pathogen, Porphyromonas gingivalis, donor-matched human blood monocytes, differentiated DCs, and macrophages were exposed to P. gingivalis lipopolysaccharide (LPS) and gene expression levels were measured by oligonucleotide microarrays. In addition to striking differences in constitutive transcriptional profiles between these myeloid populations, we identify a P. gingivalis LPS-inducible convergent, transcriptional core response of more than 400 annotated genes/ESTs among these populations, reflected by a shared, but quantitatively distinct, proteomic response. Nonetheless, clear differences emerged between the monocytes, DCs, and macrophages. The finding that long-lived myeloid inflammatory cells, particularly DCs, rapidly and aggressively respond to P. gingivalis LPS by generating chemokines, proteases, and cytokines capable of driving T-helper cell lineage polarization without evidence of corresponding immunosuppressive pathways highlights their prominent role in host defense and progressive tissue pathogenesis. The shared, unique, and/or complementary transcriptional and proteomic profiles may frame the context of the host response to P. gingivalis, contributing to the destructive nature of periodontal inflammation.

CC chemokine ligand 17 in periodontal diseases: expression in diseased tissues and production by human gingival fibroblasts

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 alpha (TNF-alpha) and interleukin (IL)-4/IL-13 increased CCL17 expression. Moreover, treatment of HGFs with a low dose of interferon-gamma (IFN-gamma) in combination with TNF-alpha and IL-4 or IL-13 had synergistic effects on the production of CCL17, whereas a high dose of IFN-gamma inhibited CCL17 production. Furthermore, Escherichia coli (E. coli) lipopolysaccharide (TLR4 ligand) and Pam3CSK4 (TLR2 ligand) inhibited CCL17 production by TNF-alpha + IL-4-stimulated HGFs, while CpG DNA (TLR9 ligand) enhanced TNF-alpha + 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 kappa B (NF-kappa B) 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.

Serum amyloid A induces CCL20 secretion in mononuclear cells through MAPK (p38 and ERK1/2) signaling pathways

Although the serum levels of SAA had been reported to be upregulated during inflammatory/infectious process, the role of this acute-phase protein has not been completely elucidated. In previous studies, we demonstrated that SAA stimulated the production of TNF-alpha, IL-1beta, IL-8, NO, and ROS by neutrophils and/or mononuclear cells. Herein we demonstrate that SAA induces the expression and release of CCL20 from cultured human blood mononuclear cells. We also focus on the signaling pathways triggered by SAA. In THP-1 cells SAA promotes phosphorylation of p38 and ERK1/2. Furthermore, the addition of SB203580 (p38 inhibitor) and PD98059 (ERK 1/2 inhibitor) inhibits the expression and release of CCL20 in mononuclear cells treated with SAA. Our results point to SAA as an important link of innate to adaptive immunity, once it might act on the recruitment of mononuclear cells.

Adrenomedullin suppresses tumour necrosis factor alpha-induced CXC chemokine ligand 10 production by human gingival fibroblasts

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-alpha), 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-alpha 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-alpha-stimulated HGFs. Moreover, we elucidated that AM produced by HGFs inhibited CXCL10 production by HGFs, because AM antagonist enhanced CXCL10 production by HGFs. TNF-alpha 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.

Human macrophage inflammatory protein 3alpha: protein and peptide nuclear magnetic resonance solution structures, dimerization, dynamics, and anti-infective properties

Human macrophage inflammatory protein 3alpha (MIP-3alpha), also known as CCL20, is a 70-amino-acid chemokine which exclusively binds to chemokine receptor 6. In addition, the protein also has direct antimicrobial, antifungal, and antiviral activities. The solution structure of MIP-3alpha was solved by the use of two-dimensional homonuclear proton nuclear magnetic resonance (NMR). The structure reveals the characteristic chemokine fold, with three antiparallel beta strands followed by a C-terminal alpha helix. In contrast to the crystal structures of MIP-3alpha, the solution structure was found to be monomeric. Another difference between the NMR and crystal structures lies in the angle of the alpha helix with respect to the beta strands, which measure 69 and approximately 56.5 degrees in the two structures, respectively. NMR diffusion and pH titration studies revealed a distinct tendency for MIP-3alpha to form dimers at neutral pH and monomers at lower pH, dependent on the protonation state of His40. Molecular dynamics simulations of both the monomeric and the dimeric forms of MIP-3alpha supported the notion that the chemokine undergoes a change in helix angle upon dimerization and also highlighted the important hydrophobic and hydrogen bonding contacts made by His40 in the dimer interface. Moreover, a constrained N terminus and a smaller binding groove were observed in dimeric MIP-3alpha simulations, which could explain why monomeric MIP-3alpha may be more adept at receptor binding and activation. The solution structure of a synthetic peptide consisting of the last 20 residues of MIP-3alpha displayed a highly amphipathic alpha helix, reminiscent of various antimicrobial peptides. Antimicrobial assays with this peptide revealed strong and moderate bactericidal activities against Escherichia coli and Staphylococcus aureus, respectively. This confirms that the C-terminal alpha-helical region of MIP-3alpha plays a significant part in its broad anti-infective activity.

CXC chemokine ligand 16 in periodontal diseases: expression in diseased tissues and production by cytokine-stimulated human gingival fibroblasts

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)-1beta, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma] increased the mRNA expression and release of CXCL16 in a dose-dependent manner. Moreover, treatment of HGFs with IFN-gamma in combination with IL-1beta had a synergistic effect on the production of CXCL16. On the other hand, IL-4 and IL-13 inhibited the IL-1beta-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.

Interleukin-24, RANTES and CCR5 gene polymorphisms are not associated with chronic adult periodontitis

BACKGROUND AND OBJECTIVE

Cytokines, such as interleukin-10, and related genetic polymorphisms, have been implicated in the pathogenesis of chronic periodontitis. The aim of this study was to investigate a possible correlation between chronic periodontitis and genetic polymorphisms coding for two interleukin-10 related chemokines [interleukin-24 and regulated on activation, normal T cells expressed and secreted (RANTES)] as well as a RANTES receptor [CC chemokine receptor 5 (CCR5)].

MATERIAL AND METHODS

A single-blind, two-centre, case-controlled study was carried out with test patients from the Clinic of Periodontics, Göteborg University, and from the Department of Periodontology, Glasgow University, and control subjects from the undergraduate clinics of both schools. Blood samples were collected from 106 patients (56 women and 50 men, mean age 51.7 yr) with generalized, severe chronic periodontitis and from 69 periodontally healthy subjects (37 women and 32 men, mean age 53.3 yr). The polymerase chain reaction (PCR) was used to identify the genetic coding for interleukin-24, RANTES and CCR5. Genotype and allele frequencies were compared between the test and control groups using Fischer's exact test at the 5% level of significance.

RESULTS

There were no statistically significant differences between patients with chronic periodontitis and control subjects, regarding genotype distribution or allele frequency, irrespective of smoking status, in the combined Glasgow and Gothenburg cohort or in the specific location cohorts. The allele frequencies for healthy and control subjects for RANTES gave a p-value of 0.80 (allele G was 58.8% in healthy subjects and and 54.4% in subjects with periodontitis), for interleukin-24 the p-value was 0.90 (allele T was 56.2% in healthy subjects and and 54.9% in subjects with periodontitis) and for CCR5 the p-value was 0.90 (the wild-type allele was 85% in healthy subjects and and 82.7% in subjects with periodontitis).

CONCLUSION

The interleukin-24, RANTES and CCR5 polymorphisms investigated are not associated with chronic periodontitis.

Increase of CCL20 expression by human gingival fibroblasts upon stimulation with cytokines and bacterial endotoxin

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-1beta), tumour necrosis factor-alpha (TNF-alpha) and Escherichia coli lipopolysaccharide (LPS) can significantly induce the production of CCL20 by HGF. We found that TNF-alpha and E. coli LPS enhanced the production of CCL20 by HGF treated with IL-1beta. In contrast, interferon-gamma (IFN-gamma) dramatically diminished CCL20 production induced by IL-1beta. Moreover, we demonstrated that nuclear factor-kappaB (NF-kappaB), 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-1beta and TNF-alpha. On the other hand, we found that not only NF-kappaB, 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.

CXCL12 and CXCR4 expression by human gingival fibroblasts in periodontal disease

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-alpha (TNF-alpha), interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta), regulated upon activation normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein 3(alpha) (MIP-3(alpha)). 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-alpha, IFN-gamma 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.

Expression of fractalkine (CX3CL1) and its receptor, CX3CR1, in periodontal diseased tissue

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), including Porphyromonas gingivalis lipopolysaccharide (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.

Expression of Macrophage Inflammatory Protein 3α in Human Inflamed Dental Pulp Tissue

Severe pulpitis resulting from dental caries is characterized by marked inflammatory infiltrate such as lymphocytes. Little is known about the recruitment of these cells into the dental pulp lesions of carious teeth. Macrophage inflammatory protein-3alpha (MIP-3alpha), a CC chemokine attracts CC chemokine receptor 6 (CCR6)-expressing T cells. We examined the distribution of MIP-3alpha-positive and/or CCR6-positive cells in human inflamed and normal dental pulp by immunohistochemistry. MIP-3alpha was observed in all inflamed pulp sections, and was mostly distributed in macrophages that had accumulated in the area adjacent to carious lesions. Furthermore, CCR6 expression was also observed in the infiltrating lymphocytes. In contrast, MIP-3alpha and CCR6 were rarely detected in normal pulp. These findings suggest that MIP-3alpha plays a role in the advancement of pulpal inflammation via the recruitment of CCR6-expressing lymphocytes.

Co-localization of Macrophage Inflammatory Protein-3?? (Mip-3??) and Its Receptor, CCR6, Promotes Pancreatic Cancer Cell Invasion

PURPOSE

Macrophage inflammatory protein-3alpha (Mip-3alpha) is par t of a family of chemotactic cytokines involved in recruiting inflammatory cells throughout the body. CCR6 is a G-protein-linked, seven-transmembrane receptor that is highly specific for Mip-3alpha. The role of Mip-3alpha has been well defined in several inflammatory conditions, but its role has not been well defined in neoplastic processes. Mip-3alpha has been shown to promote pancreatic cancer cell migration, but no studies have demonstrated the effect of Mip-3alpha on pancreatic cancer cell invasion. We hypothesize that Mip-3alpha and its CCR6 receptor promote pancreatic cancer cell invasion.

MATERIALS AND METHODS

Immunohistochemical staining was per formed for Mip-3alpha and CCR6 in pancreatic cancer tissue and the human pancreatic cancer cell line PANC-1. RNA was isolated from PANC-1 cancer cells, and the presence of Mip-3alpha messenger RNA in PANC-1 cancer cells was determined by reverse transcriptase polymerase chain reaction. PANC-1 cancer cell invasion of type IV collagen was evaluated in the presence of Mip-3alpha and anti-CCR6 antibody with the use of a modified Boyden chamber invasion assay.

RESULTS

Co-localization of Mip-3alpha and its CCR6 receptor in pancreatic cancer was confirmed using immunohistochemical staining for Mip-3alpha and its CCR6 receptor and reverse transcriptase polymerase chain reaction for Mip-3alpha. Immunohistochemical staining of pancreatic cancer tissue and the PANC-1 cancer cell line showed positive staining for Mip-3alpha and its CCR6 receptor within the cancer cells. Staining was also positive for Mip-3alpha within stromal cells adjacent to the cancer cells in pancreatic cancer tissue. Reverse transcriptase polymerase chain reaction demonstrated the presence of Mip-3alpha messenger RNA within PANC-1 cancer cells. Invasion studies showed that increasing concentrations of Mip-3alpha promoted a dose-dependent increase in pancreatic cancer cell invasion of type IV collagen. The addition of 100 ng/mL of Mip-3alpha promoted a threefold increase in pancreatic cancer cell invasion over that of the control group. Anti-CCR6 antibody inhibited Mip-3alpha-stimulated PANC-1 cancer cell invasion of type IV collagen by 63%.

DISCUSSION

Co-localization of Mip-3alpha and its CCR6 receptor promotes pancreatic cancer cell invasion of type IV collagen. This finding continues to highlight the importance that inflammation plays in the progression of pancreatic cancer. As the relationship between the inflammatory and neoplastic processes involved with pancreatic cancer becomes better defined, therapies targeting the inflammatory process may help prevent pancreatic cancer invasion and metastasis.

The CC chemokine CCL20 and its receptor CCR6

CCL20, alternatively named liver and activation-regulated chemokine (LARC), macrophage inflammatory protein-3alpha (MIP-3alpha) or Exodus-1, is the only chemokine known to interact with CC chemokine receptor 6 (CCR6), a property shared with the antimicrobial beta-defensins. The ligand-receptor pair CCL20-CCR6 is responsible for the chemoattraction of immature dendritic cells (DC), effector/memory T-cells and B-cells and plays a role at skin and mucosal surfaces under homeostatic and inflammatory conditions, as well as in pathology, including cancer and rheumatoid arthritis. In this review, the discovery, the gene and protein structure, the in vitro biological activities, the cell and inducer specific expression and the tissue distribution of CCL20 and CCR6 are discussed.