Treponema denticola alters cell vitality and induces HO-1 and Hsp70 expression in porcine aortic endothelial cells

Glutathione catabolism by Treponema denticola impacts its pathogenic potential

Treponema denticola is a spirochete that is etiologic for periodontal diseases. This bacterium is one of two periodontal pathogens that have been shown to have a complete three step enzymatic pathway (GTSP) that catabolizes glutathione to H2S. This pathway may contribute to the tissue pathology seen in periodontitis since diseased periodontal pockets have lower glutathione levels than healthy sites with a concomitant increase in H2S concentration. In order to be able to demonstrate that glutathione catabolism by the GTSP is critical for the pathogenic potential of T. denticola, allelic replacement mutagenesis was used to make a deletion mutant (Δggt) in the gene encoding the first enzyme in the GTSP. The mutant cannot produce H2S from glutathione since it lacks gamma-glutamyltransferase (GGT) activity. The hemolytic and hemoxidation activities of wild type T. denticola plus glutathione are reduced to background levels with the Δggt mutant and the mutant has lost the ability to grow aerobically when incubated with glutathione. The Δggt bacteria with glutathione cause less cell death in human gingival fibroblasts (hGFs) in vitro than do wild type T. denticola and the levels of hGF death correlate with the amounts of H2S produced. Importantly, the mutant spirochetes plus glutathione make significantly smaller lesions than wild type bacteria plus glutathione in a mouse back lesion model that assesses soft tissue destruction, a major symptom of periodontal diseases. Our results are the first to prove that T. denticola thiol-compound catabolism by its gamma-glutamyltransferase can play a significant role in the in the types of host tissue damage seen in periodontitis.

In Vitro Anti-Inflammatory Effect of Salvia sagittata Ethanolic Extract on Primary Cultures of Porcine Aortic Endothelial Cells

The aim of the present research was to study the effects of an ethanolic extract of Salvia sagittata Ruiz & Pav (SSEE), an endemic Ecuadorian plant traditionally used to treat inflammation and different intestinal affections, on primary cultures of porcine aortic endothelial cells (pAECs). pAECs were cultured in the presence of different concentrations (1-200 μg/mL) of SSEE for 24 h, and cytotoxicity was evaluated by the MTT assay. SSEE did not negatively affect cellular viability at any concentration tested. Cell cycle was analyzed and no significant change was observed. Then, the anti-inflammatory effects of SSEE on pAECs were analyzed using a lipopolysaccharide (LPS) as the inflammatory stimulus. Different markers involved in the inflammatory process, such as cytokines and protective molecules, were evaluated by real-time quantitative PCR and Western blot. SSEE showed the ability to restore pAEC physiological conditions reducing interleukin-6 and increasing Heme Oxygenase-1 protein levels. The phytochemical composition of SSEE was also evaluated via HPLC-DAD and spectrophotometric assays. The presence of different phenolic acids and flavonoids was revealed, with rosmarinic acid as the most abundant component. SSEE possesses an interesting antioxidant activity, as assessed through both the Oxygen Radical Absorbance Capacity (ORAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. In conclusion, results suggest that SSEE is endowed with an in vitro anti-inflammatory effect. This represents the initial step in finding a possible scientific support for the traditional therapeutic use of this plant.

Response of epithelial cells infected by Treponema denticola

OBJECTIVE

In the gingival crevice, the interaction between epithelial cells and periodontopathic bacteria is important for the development of periodontitis. Treponema denticola is a major pathogen of chronic periodontitis and possesses several virulence factors, such as major surface protein (Msp) and prolyl-phenylalanine-specific protease (dentilisin). Here, we investigated the behaviours of epithelial cells infected with T. denticola by measuring the expression of interleukin (IL)-1β, IL-6, β defensin 2 (BD-2) and heat-shock protein 70 (HSP70).

METHODS

Epithelial cells were infected with T. denticola wild-type strain, Msp-deficient mutant or dentilisin-deficient mutant, and the expression levels of the above targets were analysed by polymerase chain reaction.

RESULTS

Infection with T. denticola wild-type strain and mutants induced the production of IL-6 and HSP70. The level of BD-2 induced by T. denticola wild-type strain at 24 hr was significantly higher than that of the dentilisin-deficient mutant. The level of IL-1β mRNA in the wild-type strain and dentilisin-deficient mutant was slightly lower than that in the uninfected control.

CONCLUSION

These results suggest that the levels of BD-2 were affected by Msp and dentilisin. This effect may contribute to the disruption of the response of epithelial cells to eradicate T. denticola.

Water/ethanol extract of Cucumis sativus L. fruit attenuates lipopolysaccharide-induced inflammatory response in endothelial cells

Background

It is widely accepted the key role of endothelium in the onset of many chronic and acute vascular and cardiovascular diseases.

In the last decade, traditional compounds utilized in “folk medicine” were considered with increasing interest to discover new bioactive molecules potentially effective in a wide range of diseases including cardiovascular ones. Since ancient times different parts of the Cucumis sativus L. plant were utilized in Ayurvedic medicine, among these, fruits were traditionally used to alleviate skin problem such as sunburn irritation and inflammation. The main purpose of the present research was, in a well-defined in vitro model of endothelial cells, to investigate whether a water/ethanol extract of Cucumis sativus L. (CSE) fruit can attenuate the damaging effect of pro-inflammatory lipopolysaccharide (LPS).

Methods

Cell viability, gene expression of endothelial cell markers, cytokines secretion and in vitro angiogenesis assay were performed on porcine Aortic Endothelial Cells exposed to increasing doses (0.02; 02; 2 mg/ml) of CSE in the presence of pro-inflammatory lipopolysaccharide (LPS 10 μg/ml).

Results

CSE reduced LPS-induced cytotoxicity and decreased the cellular detachment, restoring the expression of tight junction ZO-1. The increase of TLR4 expression induced by LPS was counterbalanced by the presence of CSE, while the protective gene Hemeoxygenase (HO)-1 was increased. Cucumis sativus L. inhibited the early robust secretion of inflammatory IL-8 and GM-CSFs, furthermore inhibition of inflammatory IL-6 and IL-1α occurred late at 7 and 24 h respectively. On the contrary, the secretion of anti-inflammatory IL-10, together with IL-18 and IFN-γ was increased. Moreover, the in vitro angiogenesis induced by inflammatory LPS was prevented by the presence of Cucunis sativus L. extract, at any doses tested.

Conclusions

Our results have clearly demonstrated that Cucumis sativus L. extract has attenuated lipopolysaccharide-induced inflammatory response in endothelial cells.

Inflammasomes in cardiovascular diseases

NOD-like receptors (NLRs) constitute a recently identified family of macromolecules that participate in regulation of innate immune responses. To date, 23 members of the NLR family are identified in humans. Diverse NLRs are stimulated by a broad range of pathogen- or danger-associated molecular patterns, and collectively function as intracellular pattern recognition receptors (PRRs). The most studied inflammasomes are NLRP1 and NLRP3 that process inactive pro-caspase-1 to its active form, allowing the cleavage and subsequent activation of pro-IL-1β and pro-IL-18, and initiation of inflammatory responses. Three models, based upon extracellular ATP/K(+) flux, lysosomal release of cathepsin, and reactive oxygen species, have been proposed to be involved in signaling activation of NLRs and downstream events. In this review, I discuss the current state of knowledge related to the roles of NLRs and inflammasomes in the development of cardiovascular diseases.

[Inflammasome and cardiovascular diseases]

NOD-like receptors (NLRs) constitute a recently identified family of intracellular pattern recognition receptors which contains more than 20 members in mammals. Some of the NLRs, the NALP subfamily, constituted from 14 members, many of them without actual identified role, form multiproteic complex known as inflammasome, that initiate inflammation by processing inactive pro-caspase-1 to its active form, allowing the cleavage and subsequent activation of pro-IL-1β and pro-IL-18. We review the identified roles of NLRs in pathologies and argue for the role of inflammasome in the development of cardiovascular diseases. The atherogenic cytokines IL-1β and IL-18 are matured in NLRPs inflammasomes. Immunocytochemistry shows that Nlrp3 inflammasome is expressed in plaques, upregulated and activated in the CD11b(+)Gr1(high) atherosclerosis-prone monocyte subset and modulated by oxLDL in murine macrophages. These results provide an unexpected role for Nlrp3 inflammasome in atherosclerosis.

The central region of the msp gene of Treponema denticola has sequence heterogeneity among clinical samples, obtained from patients with periodontitis

Background

Treponema denticola is an oral spirochete involved in the pathogenesis and progression of periodontal disease. Of its virulence factors, the major surface protein (MSP) plays a role in the interaction between the treponeme and host. To understand the possible evolution of this protein, we analyzed the sequence of the msp gene in 17 T. denticola positive clinical samples.

Methods

Nucleotide and amino acid sequence of MSP have been determined by PCR amplification and sequencing in seventeen T. denticola clinical specimens to evaluate the genetic variability and the philogenetic relationship of the T. denticola msp gene among the different amplified sequence of positive samples. In silico antigenic analysis was performed on each MSP sequences to determined possible antigenic variation.

Results

The msp sequences showed two highly conserved 5' and 3' ends and a central region that varies substantially. Phylogenetic analysis categorized the 17 specimens into 2 principal groups, suggesting a low rate of evolutionary variability and an elevated degree of conservation of msp in clinically derived genetic material. Analysis of the predicted antigenic variability between isolates, demonstrated that the major differences lay between amino acids 200 and 300.

Conclusion

These findings showed for the first time, the nucleotide and amino acids variation of the msp gene in infecting T. denticola, in vivo. This data suggested that the antigenic variability found in to the MSP molecule, may be an important factor involved in immune evasion by T. denticola.