Correction: Interleukin-1 Receptor Antagonist Has a Novel Function in the Regulation of Matrix Metalloproteinase-13 Expression.

[This corrects the article DOI: 10.1371/journal.pone.0140942.].

Adhesion Properties of Human Oral Epithelial-Derived Cells to Zirconia.

BACKGROUND: Few studies have examined epithelial attachment to zirconia and the proliferative ability of epithelial cells on zirconia surfaces. PURPOSE: To evaluate the adhesion properties of zirconia materials for epithelial cell attachment and compare this with titanium and alumina. MATERIALS AND METHODS: Human oral epithelial cells were cultured on smooth-surfaced specimens of commercially pure titanium (cpTi), ceria-stabilized zirconia/alumina nano-composite (P-NANOZR), yttria-stabilized zirconia (Cercon), and alumina oxide (inCoris AL). The cell morphology, the cell viability and mRNA of integrin ß4 , laminin γ2 , catenin δ2 , and E-cadherin were evaluated by SEM, Cell-Counting Kit-8, and real-time PCR, respectively. RESULTS: Morphology of cells attached to specimens was similar among all groups. The viable cell numbers on Cercon and inCoris AL after 24 hours culture were significantly higher than for cpTi. Integrin ß4 , laminin γ2 , and catenin δ2 mRNA expression was not different among all groups. However, at 3 and 24 hours after incubation, E-cadherin mRNA expression in the P-NANOZR group was significantly higher than for cpTi. CONCLUSION: Zirconia may support binding of epithelial cells through hemidesmosomes comparable with titanium. Furthermore, P-NANOZR may impart resistance to exogenous stimuli through strong intercellular contacts with peri-implant mucosal cells when used as an abutment and implant superstructure.

Interleukin-1 Receptor Antagonist Has a Novel Function in the Regulation of Matrix Metalloproteinase-13 Expression.

Interleukin-1 receptor antagonist (IL-1Ra) is an IL-1 family member, which binds to IL-1 receptors but does not induce any intracellular signaling. We addressed whether IL-1Ra has a novel function in regulation of the extracellular matrix or adhesion molecules. Polymerase chain reaction array analysis demonstrated a ~5-fold increase in matrix metalloproteinase 13 (MMP-13) mRNA expression of IL-1Ra siRNA-transfected Ca9-22 human oral squamous epithelial carcinoma cells compared with the control. In fact, MMP-13 mRNA and protein expression as well as its activity in IL-1Ra siRNA-transfected Ca9-22 cell lines were significantly higher than those in the control. IL-1Ra siRNA treatment resulted in strong elevation of MMP-13 expression, whereas addition of rhIL-1Ra (40 ng/ml) suppressed MMP-13 expression, suggesting that IL-1Ra had a specific effect on MMP-13 induction. IL-1Ra siRNA could potently suppress IL-1α. No significant difference was found between the MMP-13 mRNA expression of IL-1Ra siRNA-transfected cells and those treated with anti-IL-1α or anti-IL-1ß antibodies. These results suggested that continuous supply of IL-1 had no effect on the induction of MMP-13 by IL-1Ra siRNA. Histopathological investigation of MMP-13 in periodontal tissue showed specific localization in the junctional epithelial cells of IL-1Ra knockout (KO) mice. Furthermore, infection with Aggregatibacter actinomycetemcomitans to establish an experimental periodontitis model resulted in predominant localization of MMP-13 along apical junctional epithelial cells. Laminin-5, which is degraded by MMP-13, was found in the internal basal lamina of wild-type mice, whereas the internal basal lamina of IL-1Ra KO mice did not show obvious laminin-5 localization. In particular, laminin-5 localization almost disappeared in the internal basal lamina of IL-1Ra KO mice infected with A. actinomycetemcomitans, suggesting that the suppression of IL-1Ra resulted in strong induction of MMP-13 that degraded laminin-5. In conclusion, IL-1Ra is associated with MMP-13 expression and has a novel function in such regulation without interference of the IL-1 signaling cascade.

Enhanced bioactivity of polyvinylidene chloride films using argon ion bombardment for guided bone regeneration.

Polyvinylidene chloride (PVDC) is a long chain carbon synthetic polymer. The objective of this study was to improve the bioactivity of PVDC films through surface modification using argon (Ar) ion bombardment to create Ar-modified PVDC films (Ar-PVDC) to address the clinical problems of guided bone regeneration (GBR), which is technique-sensitive, and low bone regenerative ability. First, the effects of Ar ion bombardment, a low temperature plasma etching technique widely used in industry, on PVDC film wettability, surface chemistry, and morphology were confirmed. Next, fibroblast-like and osteoblast-like cell attachment and proliferation on Ar-PVDC were assessed. As a preclinical in vivo study, Ar-PVDC was used to cover a critical-sized bone defect on rat calvaria and osteoconductivity was evaluated by micro-computed tomography analysis and histological examinations. We found that the contact angle of PVDC film decreased by 50° because of the production of -OH groups on the PVDC film surface, though surface morphological was unchanged at 30 min after Ar ion bombardment. We demonstrated that cell attachment increased by about 40% and proliferation by more than 140% because of increased wettability, and 2.4 times greater bone regeneration was observed at week 3 with Ar-PVDC compared with untreated PVDC films. These results suggest that Ar ion bombardment modification of PVDC surfaces improves osteoconductivity, indicating its potential to increase bone deposition during GBR.