Antisense-mediated inhibition of ICAM-1 expression: a therapeutic strategy against inflammation of human periodontal tissue

Astragaloside reduces toxic effect of periodontal ligament fibroblasts induced by lipopolysaccharide

Periodontitis is a non-specific and chronic disease which is highly prevalent, resulting in inflammation and destruction of periodontal tissues. This study aims to explore the effect and mechanism of astragaloside on periodontitis. We used CCK-8, Western Blot, qPCR and flow cytometry to analyze cell viability, related protein and mRNA expression, and cell apoptosis. We found that AST could promote cell proliferation and reduce apoptosis induced by LPS. Besides, AST could alleviate the increased expression of COX-2 and ICAM-1 induced by LPS. MiR-26b-3P specifically targeted the 3' UTR of ICAM-1. These results indicate that AST reduces toxic effect of human periodontal ligament cells through regulating miR-26b-3P/ICAM-1, thus highlighting its protective role in periodontitis.

Identification of several hub-genes associated with periodontitis using integrated microarray analysis

The aim of the present study was to identify differentially expressed genes and biological processes associated with periodontitis. In this study, the most significant 200 differentially expressed genes associated with periodontitis were identified using integrated analysis of multiple microarray data in combination with screening for genome-wide relative significance and genome-wide global significance. Gene Ontology (GO) enrichment analysis and pathway analysis were performed using the GO website and Kyoto Encyclopedia of Genes and Genomes (KEGG). A protein-protein interaction (PPI) network was constructed based on the Search Tool for the Retrieval of Interacting Genes/Proteins. The top 200 differentially expressed genes were found to be highly associated with periodontitis. GO enrichment analyses revealed that the identified genes were significantly enriched in terms of response to organic substance, response to wounding and cell migration. The most common term of the KEGG pathway was cytokine-cytokine receptor interaction. PPI network analysis indicated that interleukin (IL)8, IL1β, vascular endothelial growth factor A, intercellular adhesion molecule 1, PTGS2 and CXCL10 were hub genes, which formed numerous interactions with several genes. In conclusion, the present study identified numerous genes that were differentially expressed in periodontitis, as well as determined the biological pathways and PPI network associated with those genes.

Regulation of ICAM-1 expression in gingival fibroblasts infected with high-glucose-treated P. gingivalis

Porphyromonas gingivalis is a major pathogen in the initiation and progression of periodontal disease, which is recognized as a common complication of diabetes. ICAM-1 expression by human gingival fibroblasts (HGFs) is crucial for regulating local inflammatory responses in inflamed periodontal tissues. However, the effect of P. gingivalis in a high-glucose situation in regulating HGF function is not understood. The P. gingivalis strain CCUG25226 was used to study the mechanisms underlying the modulation of HGF ICAM-1 expression by invasion of high-glucose-treated P. gingivalis (HGPg). A high-glucose condition upregulated fimA mRNA expression in P. gingivalis and increased its invasion ability in HGFs. HGF invasion with HGPg induced increases in the expression of ICAM-1. By using specific inhibitors and short hairpin RNA (shRNA), we have demonstrated that the activation of p38 MAPK and Akt pathways is critical for HGPg-induced ICAM-1 expression. Luciferase reporters and chromatin immunoprecipitation assays suggest that HGPg invasion increases NF-κB- and Sp1-DNA-binding activities in HGFs. Inhibition of NF-κB and Sp1 activations blocked the HGPg-induced ICAM-1 promoter activity and expression. The effect of HGPg on HGF signalling and ICAM-1 expression is mediated by CXC chemokine receptor 4 (CXCR4). Our findings identify the molecular pathways underlying HGPg-dependent ICAM-1 expression in HGFs, providing insight into the effect of P. gingivalis invasion in HGFs.

Role of high endothelial postcapillary venules and selected adhesion molecules in periodontal diseases: a review

Periodontitis is accompanied by the proliferation of small blood vessels in the gingival lamina propria. Specialized postcapillary venules, termed periodontal high endothelial-like venules, are also present, and demonstrate morphological and functional traits similar to those of high endothelial venules (HEVs) in lymphatic organs. The suggested role of HEVs in the pathogenesis of chronic periodontitis involves participation in leukocyte transendothelial migration and therefore proinflammatory effects appear. Recent observations suggest that chronic periodontitis is an independent risk factor for systemic vascular disease and may result in stimulation of the synthesis of acute phase protein by cytokines released by periodontal high endothelial cells (HECs). However, tissue expression of HEV-linked adhesion molecules has not been evaluated in the gingiva of patients with chronic periodontitis. This is significant in relation to potential therapy targeting expression of the adhesion molecules. In this review, current knowledge of HEV structure and the related expression of four surface adhesion molecules of HECs [CD34, platelet endothelial cell adhesion molecule 1, endoglin and intercellular adhesion molecule 1 (ICAM-1)], involved in the key steps of the adhesion cascade in periodontal diseases, are discussed. Most studies on the expression of adhesion molecules in the development and progression of periodontal diseases pertain to ICAM-1 (CD54). Studies by the authors demonstrated quantitatively similar expression of three of four selected surface markers in gingival HEVs of patients with chronic periodontitis and in HEVs of reactive lymph nodes, confirming morphological and functional similarity of HEVs in pathologically altered tissues with those in lymphoid tissues.

Delivery of oligodeoxynucleotides into human saphenous veins and the adjunct effect of ultrasound and microbubbles

Therapy with naked oligodeoxynucleotides (ODNs, molecular weight: 3000 to 7500) provides an elegant means of modulating gene expression without the problems associated with conventional gene therapy, but the relatively low transfer efficiency on intravascular administration is a limitation to clinical application. Ultrasound, which can be potentiated by microbubbles, shows promise as a method of delivering macromolecules such as plasmid DNA and other transgenes into cells. Since uptake of molecules into cells depends on their molecular weight, it might be expected that the delivery of ODNs, which are relatively small, will be facilitated by ultrasound and microbubbles. In the present study, we delivered ODNs into veins using ultrasound and microbubbles. First, we quantified the uptake of fluorescent-labeled ODNs into intact ex vivo human saphenous veins and isolated smooth muscle cells from the veins, evaluating the effect of ultrasound and microbubbles on uptake. Ultrasound potentiated the delivery of ODN in cells, except at high concentrations. When intact veins were studied, we achieved nuclear localization of fluorescent-labeled ODNs in cells. This increased with increasing concentration and incubation time and was not potentiated by ultrasound, even when microbubbles were used. We then applied a therapeutic ODN (antisense to intercellular adhesion molecule 1, ICAM-1) to vein samples and documented a functional inhibition of gene expression in a sequence-specific manner at the protein level with immunohistochemistry and western blot analysis. Again, no significant difference was seen with adjunct ultrasound. These observations suggest high diffusion of ODNs into human saphenous veins in this ex vivo model, indicating potential applications to inhibition of vascular bypass graft occlusion and other vasculopathies. Although microbubble-ultrasound was of value with cells in culture, it was not beneficial with intact veins.

Upregulation of intercellular adhesion molecule 1 and proinflammatory cytokines by the major surface proteins of Treponema maltophilum and Treponema lecithinolyticum, the phylogenetic group IV oral spirochetes associated with periodontitis and endodontic infections

Treponema maltophilum and Treponema lecithinolyticum belong to the group IV oral spirochetes and are associated with endodontic infections, as well as periodontitis. Recently, the genes encoding the major surface proteins (Msps) of these bacteria (MspA and MspTL, respectively) were cloned and sequenced. The amino acid sequences of these proteins showed significant similarity. In this study we analyzed the functional role of these homologous proteins in human monocytic THP-1 cells and primary cultured periodontal ligament (PDL) cells using recombinant proteins. The complete genes encoding MspA and MspTL without the signal sequence were cloned into Escherichia coli by using the expression vector pQE-30. Fusion proteins tagged with N-terminal hexahistidine (recombinant MspA [rMspA] and rMspTL) were obtained, and any possible contamination of the recombinant proteins with E. coli endotoxin was removed by using polymyxin B-agarose. Flow cytometry showed that rMspA and rMspTL upregulated the expression of intercellular adhesion molecule 1 (ICAM-1) in both THP-1 and PDL cells. Expression of proinflammatory cytokines, such as interleukin-6 (IL-6) and IL-8, was also induced significantly in both cell types by the Msps, as determined by reverse transcription-PCR and an enzyme-linked immunosorbent assay, whereas IL-1beta synthesis could be detected only in the THP-1 cells. The upregulation of ICAM-1, IL-6, and IL-8 was completely inhibited by pretreating the cells with an NF-kappaB activation inhibitor, l-1-tosylamido-2-phenylethyl chloromethyl ketone. This suggests involvement of NF-kappaB activation. The increased ICAM-1 and IL-8 expression in the THP-1 cells obtained with rMsps was not inhibited in the presence of the IL-1 receptor antagonist (IL-1ra), a natural inhibitor of IL-1. Our results show that the Msps of the group IV oral spirochetes may play an important role in amplifying the local immune response by continuous inflammatory cell recruitment and retention at an infection site by stimulation of expression of ICAM-1 and proinflammatory cytokines.

Advantages of antisense drugs for the treatment of oral diseases

For almost two decades, antisense oligonucleotides (AS-ON) have been used successfully to suppress and regulate gene expression in vitro and in vivo. They are, meanwhile, well established to serve as molecular tools for several biologic applications, from the study of single gene functions up to complex target gene validations. Based on an at least theoretically simple mode of action, the sequence-specific inhibition of mRNA functions after complex formation by Watson-Crick base pairing and presumably enzymatic degradation of the target mRNA, they obviously carry a high therapeutic potential for the treatment of human diseases. In recent years, a remarkable number of clinical trials have been initiated and performed to evaluate the therapeutic usefulness of antisense technology. However, after the successful development of the first antisense-based drug Vitravene (Isis Pharmaceutical Inc., Carlsbad, CA) in 1998, no second product has appeared on the market to date. Here, we describe substantial advantages for the development of antisense-based drugs against less severe oral diseases that represent novel but highly promising application fields of the technology.