Interleukin-4 suppresses IL-1-induced expression of matrix metalloproteinase-3 in human gingival fibroblasts

Avoiding implant-related complications in medically compromised patients with or without unhealthy lifestyle/Elevated oxidative stress

Increased human life expectancy broadens the alternatives for missing teeth and played a role in the widespread use of dental implants and related augmentation procedures for the aging population. Though, many of these patients may have one or more diseases. These systemic conditions may directly lead to surgical complications, compromise implant/bone healing, or influence long-term peri-implant health and its response to biologic nuisances. Offering patients credible expectations regarding intra- and postoperative complications and therapeutic prognosis is an ethical and legal obligation. Clear identification of potential types of adverse effects, complications, or errors is important for decision-making processes as they may be related to different local, systemic, and technical aspects. Therefore, the present review structures the underlying biological mechanisms, clinical evidence, and clinical recommendations for the most common systemic risk factors for implant-related complications.

Interleukin 1β and Prostaglandin E2 affect expression of DNA methylating and demethylating enzymes in human gingival fibroblasts

Periodontitis is a common chronic inflammatory condition that results in increased levels of inflammatory cytokines and inflammatory mediators. In addition to oral disease and tooth loss, it also causes low-grade systemic inflammation that contributes to development of systemic conditions including cardiovascular disease, pre-term birth, diabetes and cancer. Chronic inflammation is associated with epigenetic change, and it has been suggested that such changes can alter cell phenotypes in ways that contribute to both ongoing inflammation and development of associated pathologies. Here we show that exposure of human gingival fibroblasts to IL-1β increases expression of maintenance methyltransferase DNMT1 but decreases expression of de novo methyltransferase DNMT3a and the demethylating enzyme TET1, while exposure to PGE2 decreases expression of all three enzymes. IL-1β and PGE2 both affect global levels of DNA methylation and hydroxymethylation, as well as methylation of some specific CpG in inflammation-associated genes. The effects of IL-1β are independent of its ability to induce production of PGE2, and the effects of PGE2 on DNMT3a expression are mediated by the EP4 receptor. The finding that exposure of fibroblasts to IL-1β and PGE2 can result in altered expression of DNA methylating/demethylating enzymes and in changing patterns of DNA methylation suggests a mechanism through which inflammatory mediators might contribute to the increased risk of carcinogenesis associated with inflammation.

Characterization of Cytokines and Proliferation Marker Ki67 in Cleft Affected Lip Tissue

Background and objectives: Cleft lip palate takes the second place among all anomalies. The complex appearance of cytokines and proliferation markers has still not been clarified despite their possible crucial role in cleft tissue. Therefore, the aim of work was the detection of appearance of pro- and anti-inflammatory cytokines and proliferation marker Ki67, and their inter-correlations in cleft affected lip (CAL). Materials and Methods: The lip material was obtained from 16 children aged before primary dentition during plastic surgery. Control was obtained from 7 non-CAL oral tissue. Tissues were stained for IL-1, IL-4, IL-6, IL-8, IL-10 and Ki67 immunohistochemically. Non-parametric statistic, Mann-Whitney and Spearman's coefficient were used. Results: All cytokines positive cells were observed more into the epithelium. Statistically significant difference was seen between epithelial IL-1, IL-10, IL-8 and Ki67 positive cells and IL-10-, IL-4-containing connective tissue cells in comparison to the control. Strong positive correlation was detected in CAL epithelium between IL-10 and IL-8, IL-10 and IL-4, IL-10 and IL-1, IL-1 and IL-8, IL-1 and IL-4, IL-4 and IL-8, IL-8 and Ki67, IL-10 and Ki67, but moderate-in connective tissue between IL-1 and IL-10, IL-1 and IL-4. Conclusion: The CAL epithelium is the main source for the interleukins. Rich similar expression of IL-1 and IL-10 suggests the balance between pro-and anti-inflammatory tissue response on basis of dysregulated tissue homeostasis (increase of IL-8). The correlations between the different ILs -1, -4, -8, -10 in CAL epithelium seem to indicate the self-protection compensatory mechanism for intensification of local inflammatory-immune response without involvement of IL-6. The correlations between Ki67 and cytokines indicate the involvement of IL-8 and IL-10 in stimulation of cellular proliferation. IL-4 and IL-10 expression from CAL connective tissue simultaneously to IL-1, IL-4 and IL-10 inter-correlations there suggests the intensification of local immune response regulated probably by main pro-inflammatory cytokine-IL-1.

Evaluation of gingival crevicular fluid levels of tissue plasminogen activator, plasminogen activator inhibitor 2, matrix metalloproteinase-3 and interleukin 1-β in patients with different periodontal diseases

OBJECTIVES

The purpose of this study was to evaluate the gingival crevicular fluid levels of interleukin-1beta (IL-1β), matrix metalloproteinases-3 (MMP-3), tissue type plasminogen activator (t-PA) and plasminogen activator inhibitor 2 (PAI-2) in patients with chronic periodontitis, aggressive periodontitis (AgP) and healthy individuals (controls).

MATERIAL AND METHODS

Systemically healthy (21 chronic periodontitis, 23 AgP and 20 controls) subjects were included in this study. Plaque index, gingival index, probing pocket depth and clinical attachment level were recorded and gingival crevicular fluid samples were collected. Assays for IL-1β, MMP-3, t-PA and PAI-2 levels in gingival crevicular fluid were carried out by an enzyme-linked immunosorbent assay. The one-sample Kolmogorov-Smirnov test, Mann-Whitney U test and Spearman correlation coefficient were used for data analyses.

RESULTS

Gingival crevicular fluid levels of t-PA and IL-1β were significantly higher in chronic periodontitis and AgP groups than in the control group (p < 0.001). MMP-3 levels in gingival crevicular fluid were detected as significantly higher in the chronic periodontitis and AgP groups compared with the control group (p < 0.05). The t-PA/PAI-2 rate of patients with chronic periodontitis and AgP were significantly higher than the control group (p < 0.05). The positive correlations were found among the PAI-2, t-PA, IL-1β and MMP-3 levels in gingival crevicular fluid. The volume of the gingival crevicular fluid correlated with all of the clinical parameters (p < 0.001). There were positive correlations between the gingival crevicular fluid levels of PAI-2 and the probing pocket depth and between gingival crevicular fluid levels of PAI-2 and the clinical attachment level (p < 0.01). Similarly, significant correlations were found between t-PA levels and probing pocket depth and between t-PA levels and clinical attachment level measurements (p < 0.001).

CONCLUSION

The present data showed that gingival crevicular fluid levels of IL-1 β, MMP-3 and t-PA increased in periodontal disease regardless of the periodontitis type and played a part in tissue destruction.

IL-4 inhibition of IL-1 induced Matrix metalloproteinase-3 (MMP-3) expression in human fibroblasts involves decreased AP-1 activation via negative crosstalk involving of Jun N-terminal kinase (JNK)

Matrix metalloproteinase-3 (MMP-3) over-expression is associated with tissue destruction in the context of chronic inflammation. Previous studies showed that IL-4 inhibits induction of MMP-3 by IL-1β, and suggested that AP-1 might be involved. Here we show that IL-1 induced binding of transcription factor AP-1 to the MMP-3 promoter consists primarily of c-Jun, JunB, and c-Fos and that binding of c-Jun and c-Fos is inhibited by the combination of cytokines while binding of Jun B is not. Mutation of the AP-1 site in the MMP-3 promoter decreased the ability of IL-4 to inhibit its transcription in transfected MG-63 cells. Western blotting showed that both cytokines activate Jun N-terminal kinase (JNK), but with somewhat different kinetics, and that activation of JNK by both cytokines individually is inhibited by the combination. These results indicate that IL-4 inhibition of MMP-3 expression is associated with reduction of IL-1 induced binding of active forms of the AP-1 dimer, while less active JunB-containing dimers remain, and suggest that these changes are associated with decreased activation of JNK.

Regulation of avoidant behaviors and pain by the anti-inflammatory tyrosine phosphatase SHP-1

The protein tyrosine phosphatase SHP-1 is a critical regulator of cytokine signaling and inflammation. Mice homozygous for a null allele at the SHP-1 locus have a phenotype of severe inflammation and are hyper-responsive to the TLR4 ligand LPS. TLR4 stimulation in the CNS has been linked to both neuropathic pain and sickness behaviors. To determine if reduction in SHP-1 expression affects LPS-induced behaviors, responses of heterozygous SHP-1-deficient (me/+) and wild-type (+/+) mice to LPS were measured. Chronic (4-week) treatment with LPS induced avoidant behaviors indicative of fear/anxiety in me/+, but not +/+, mice. These behaviors were correlated with a LPS-induced type 2 cytokine, cytokine receptor, and immune effector arginase profile in the brains of me/+ mice not found in +/+ mice. Me/+ mice also had a constitutively greater level of TLR4 in the CNS than +/+ mice. Additionally, me/+ mice displayed constitutively increased thermal sensitivity compared to +/+ mice, measured by the tail-flick test. Moreover, me/+ glial cultures were more responsive to LPS than +/+ glia. Therefore, the reduced expression of SHP-1 in me/+ imparts haploinsufficiency with respect to the control of CNS TLR4 and pain signaling. Furthermore, type 2 cytokines become prevalent during chronic TLR4 hyperstimulation in the CNS and are associated positively with behaviors that are usually linked to type 1 pro-inflammatory cytokines. These findings question the notion that type 2 immunity is solely anti-inflammatory in the CNS and indicate that type 2 immunity induces/potentiates CNS inflammatory processes.

Application of a disease-regulated promoter is a safer mode of local IL-4 gene therapy for arthritis

The application of disease-regulated promoters in local gene therapy for rheumatoid arthritis potentiates the development of a sophisticated treatment that relies on a restricted and fine-tuned supply of biologicals. Although several studies have investigated regulated promoters for achieving effective transgene expression during arthritis, none have explored their potential for minimizing deleterious effects arising from constitutive overexpression of transgenes under naive conditions. Using naive and collagen-induced arthritic mice, we examined the applicability of a hybrid interleukin-1 enhancer/interleukin-6 proximal promoter for achieving efficacious murine interleukin-4 gene therapy under arthritic conditions, while minimizing interleukin-4-induced inflammation under naive conditions. We found strong upregulation of transgene expression in virally transduced knee joints under arthritic conditions compared to levels in naive animals. Besides its responsiveness, the promoter strength proved sufficient for generating therapeutically efficacious levels interleukin-4, as demonstrated by the successful protection against cartilage erosion in collagen-induced arthritis. Most importantly, promoter-mediated restriction of the potent chemotactic interleukin-4 in naive animals strongly reduced the amounts of inflammatory cell influx. This study suggests the suitability of the interleukin-1 enhancer/interleukin-6 proximal promoter for the development of a local gene therapy strategy for rheumatoid arthritis that requires fine-tuned and restricted expression of transgenes with a pleiotrophic nature.

Interleukin-4 inhibition of interleukin-1-induced expression of matrix metalloproteinase-3 (MMP-3) is independent of lipoxygenase and PPARgamma activation in human gingival fibroblasts

Background

Interleukin 4 (IL-4) has been shown to suppress interleukin-1 (IL-1) induced expression of matrix metalloproteinase-3 (MMP-3) in human synovial and gingival fibroblasts, but the mechanism of suppression has not been determined. Activators of peroxisome proliferator-activated receptor-γ (PPARγ) have been shown to inhibit cytokine induced expression of MMPs in other cell types, and IL-4 has been shown to activate PPARγ by stimulating production of ligands through the lipoxygenase pathway. It has been suggested that PPARγ may inhibit expression of MMPs by competing with transcription factor AP-1 for binding to a putative composite binding element in the promoters. The objective of this study was to determine whether the suppressive effects of IL-4 on the IL-1 induced expression of MMP-3 involve activation of lipoxygenase and/or PPARγ.

Results

Western blotting revealed the presence of PPARγ in nuclear extract of HGF. IL-1 induced binding of nuclear extract to the putative composite PPRE/AP-1 site was diminished in the presence of pioglitazone, but there was no evidence of any change in the composition of the retarded complexes, and no evidence of PPARγ binding to this site. Nordihydroguaiaretic acid (NDGA), a non-selective lipoxygenase inhibitor, and MK886, a specific inhibitor of 5-lipoxygenase, induced MMP-3 expression synergistically with IL-1. However IL-4 was still able to inhibit MMP-3 expression in the presence of NDGA or MK886 and IL-1. Activation of PPARγ with pioglitazone not only failed to inhibit IL-1 induced expression of MMP-3 mRNA, but rather super-induced MMP-3 in the presence of IL-1. PPARγ antagonist GW9662 failed to abolish the suppressive effects of IL-4. Another PPARγ activator, 15-deoxy-Delta12,14prostaglandin J2 (15dPGJ2), also super-induced MMP-3 mRNA, and this was due at least in part to increased transcription.

Conclusion

IL-4 suppression of IL-1-induced MMP-3 expression in HGF is independent of lipoxygenase activity and activation of PPARγ. Super-induction of MMP-3 by pioglitazone may have important implications for patients using pioglitazone to treat type II diabetes in the presence of chronic inflammation.

Host response modulation in the management of periodontal diseases

OBJECTIVE

To review the biological mechanisms and clinical utility of therapeutic modulation of the host response in the management of periodontal diseases.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed up to and including December 2004. The search was limited to in vitro, experimental animal and clinical studies published in English. The selection criteria included all levels of available evidence: systematic reviews, randomised-controlled clinical trials, controlled clinical trials, prospective and retrospective cohort studies and case reports of human and experimental animal studies.

RESULTS

Six targets for non-microbial chemotherapeutic intervention were identified. Clinical trials have demonstrated the ability of non-steroidal anti-inflammatory drugs to slow periodontal disease progression. However, recently reported serious adverse effects preclude the use of cyclooxygenase-2 inhibitors as an adjunct to periodontal therapy. Adjunctive use of subantimicrobial dose doxycycline to non-surgical periodontal therapy is beneficial in the management of chronic periodontitis over 12 months. Controversial data exist on the effects of bisphosphonate administration as an adjunct to periodontal therapy. Evidence on modulation of other host mediators including lipoxins, cytokines and nitric oxide synthase is limited to animal research.

CONCLUSION

After validation in long-term clinical trials, adjunctive host modulation therapy may prove advantageous in the management of periodontal diseases.

Mechanisms of liver fibrosis

Liver fibrosis represents a significant health problem worldwide of which no acceptable therapy exists. The most characteristic feature of liver fibrosis is excess deposition of type I collagen. A great deal of research has been performed to understand the molecular mechanisms responsible for the development of liver fibrosis. The activated hepatic stellate cell (HSC) is the primary cell type responsible for the excess production of collagen. Following a fibrogenic stimulus, HSCs change from a quiescent to an activated, collagen-producing cell. Numerous changes in gene expression are associated with HSC activation including the induction of several intracellular signaling cascades, which help maintain the activated phenotype and control the fibrogenic and proliferative state of the cell. Detailed analyses in understanding the molecular basis of collagen gene regulation have revealed a complex process offering the opportunity for multiple potential therapeutic strategies. However, further research is still needed to gain a better understanding of HSC activation and how this cell maintains its fibrogenic nature. In this review we describe many of the molecular events that occur following HSC activation and collagen gene regulation that contribute to the fibrogenic nature of these cells and provide a review of therapeutic strategies to treat this disease.

Determination of interleukin-4-responsive region in the human cytochrome P450 2E1 gene promoter

Cytochrome P450 2E1 (CYP2E1) gene expression is known to be induced by interleukin-4 (IL4) and repressed by inflammatory cytokines, such as interleukin-1beta3 (IL1beta3) in human hepatocytes. The mechanisms involved in these transcriptional regulations remain elusive. In order to study these mechanisms, various constructs of the human CYP2E1 promoter were prepared and transfected into the human HepG2 hepatoma cell line. Our findings revealed that an IL4-responsive region of 128bp (-671/-544) was required to mediate induction by IL4. IL1beta caused moderate but significant decrease of the promoter activity, which was abolished when the two cytokines were combined. The IL1beta inhibitory effect is mediated through a regulatory sequence independent of that of IL4. Furthermore, by using specific signaling pathway inhibitors, we demonstrated that IL4 activation required protein kinase C (PKC) activation. In addition, our results suggest that induction by IL4 was not dependent on a single binding site but rather on a complex region which includes putative binding sites for signal transducer and activator of transcription (STAT)6, activator protein (AP)-1, nuclear factor kappa-B (NFkappaB), nuclear factor of activated T cells (NFAT) and CCAAT enhancer binding protein (C/EBP). Electrophoretic mobility shift assays suggest that AP1 and NFAT transcription factors are able to bind to three sites in the IL4-responsive region.