CXCL5/CXCL8 induces neutrophilic inflammation in peri-implantitis.

OBJECTIVE AND BACKGROUND: This research aimed to examine the role of C-X-C motif chemokine ligand 5 (CXCL5) and C-X-C motif chemokine ligand 8 (CXCL8; also known as IL-8) in neutrophilic inflammation triggered by peri-implantitis and to shed light on the underlying mechanisms that link them to the development of this condition. MATERIALS: This study included 40 patients who visited the Department of Periodontology at Kyungpook University Dental Hospital. They were divided into two groups based on their condition: healthy implant (HI) group (n = 20) and peri-implantitis (PI) group (n = 20). Biopsy samples of PI tissue were collected from the patients under local anesthesia. HI tissue was obtained using the same method during the second implant surgery. To construct libraries for control and test RNAs, the QuantSeq 3' mRNA-Seq Library Prep Kit (Lexogen, Inc., Austria) was used according to the manufacturer's instructions. Samples were pooled based on representative cytokines obtained from RNA sequencing results and subjected to Reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Hematoxylin and eosin staining, and immunohistochemistry (IHC) analysis were performed to visually assess expression levels and analyze tissue histology. Student's t-test was employed to conduct statistical analyses. RESULTS: Initially, heatmaps were used to examine gene expression variations between the HI and PI groups based on the results of RNA sequencing. Notably, among various cytokines, CXCL5 and CXCL8 had the highest expression levels in the PI group compared with the HI group, and they are known to be associated with inflammatory responses. In the gingival tissues, the expression of genes encoding cytokines such as interleukin (IL)-1ß, tumor necrosis factor-alpha (TNF)-α, interleukin (IL)-6, and CXCL5/CXCL8 was assessed via RT-qPCR. The mRNA expression level of CXCL5/CXCL8 significantly increased in the PI group compared with the HI group (p < .045). Contrarily, the mRNA expression level of interleukin 36 receptor antagonist (IL36RN) significantly decreased (p < .008). IHC enabled examination of the distribution and intensity of CXCL5/CXCL8 protein expression within the tissue samples. Specifically, increased levels of CXCL5/CXCL8 promote inflammatory responses, cellular proliferation, migration, and invasion within the peri-implant tissues. These effects are mediated through the activation of the PI3K/Akt/NF-κB signaling pathway. CONCLUSIONS: This study found that the PI sites had higher gene expression level of CXCL8/CXCL5 in the soft tissue than HI sites, which could help achieve more accurate diagnosis and treatment planning.

Metabolic profiling of peri-implant crevicular fluid in peri-implantitis.

OBJECTS: This study aims to explore the etiology of peri-implantitis by comparing the metabolic profiles in peri-implant crevicular fluid (PICF) from patients with healthy implants (PH) and those with peri-implantitis (PI). MATERIALS AND METHODS: Fifty-six patients were enrolled in this cross-sectional study. PICF samples were collected and analyzed using both non-targeted and targeted metabolomics approaches. The relationship between metabolites and clinical indices including probing depth (PD), bleeding on probing (BOP), and marginal bone loss (MBL) was examined. Additionally, submucosal microbiota was collected and analyzed using 16S rRNA gene sequencing to elucidate the association between the metabolites and microbial communities. RESULTS: Significant differences in metabolic profiles were observed between the PH and PI groups, with 179 distinct metabolites identified. In the PI group, specific amino acids and fatty acids were significantly elevated compared to the PH group. Organic acids including succinic acid, fructose-6-phosphate, and glucose-6-phosphate were markedly higher in the PI group, showing positive correlations with mean PD, BOP, and MBL. Metabolites that increased in the PI group positively correlated with the presence of Porphyromonas and Treponema and negatively with Streptococcus and Haemophilus. CONCLUSIONS: This study establishes a clear association between metabolic compositions and peri-implant condition, highlighting enhanced metabolite activity in peri-implantitis. These findings open avenues for further research into metabolic mechanisms of peri-implantitis and their potential therapeutic implications.

Identification of novel candidate biomarkers related to immune cell infiltration in peri-implantitis.

OBJECTIVE: The present study was performed to identify key biomarkers associated with immune cell infiltration in peri-implantitis through bioinformatic analyses. METHODS: Six peri-implantitis soft tissue samples and six healthy gingiva samples were obtained from GSE106090, and were used to identify immune-associated differentially expressed genes (DEGs) in peri-implantitis. The candidate biomarkers associated with immune cell infiltration were examined by immunohistochemical staining. RESULTS: We identified 2089 upregulated and 2173 downregulated genes. Upregulated DEGs were significantly associated with immune response. Ten key candidate biomarkers were identified in the PPI network, including IL1B, TLR2, TLR4, CCL4, CXCL8, IL10, IL6, CD4, CCL3, and PTPRC. The expression level of the 10 genes increased in peri-implantitis soft tissue samples compared with healthy gingiva samples. The proportion of CD4+ T cells, iTreg, and Tfh in infiltration immune cells increased in peri-implantitis soft tissue samples and were positively correlated with the expression level of candidate biomarkers TLR4, CCL3, CXCL8, and IL1B. Immunohistochemistry showed that there were more lymphocytes in peri-implantitis soft tissue samples, with an increased expression level of TLR4, CCL3, CXCL8, and IL1B. CONCLUSION: Identification of four novel diagnostic biomarkers was helpful for revealing the molecular mechanisms and could serve as a risk predictor for the immune microenvironment in peri-implantitis.

Evaluation of salivary stress markers and inflammatory cytokine levels in peri-implantitis patients.

BACKGROUND AND OBJECTIVE: Psychological stress has been identified in some observational studies as a potential factor that may modify and affect periodontal diseases, but there are no similar data for peri-implantitis. The aim of this study was to determine the relationship between interleukin (IL)-1ß, IL-6, IL-10, interferon (IFN)α inflammatory cytokines and the psychological stress-related markers, glucocorticoid receptor-α (GRα), and salivary α-amylase (sAA) gene expression levels in saliva samples obtained from healthy implants and peri-implantitis patients. MATERIALS AND METHODS: The study included a total of 50 systemically healthy subjects. Peri-implant clinical parameters were recorded and psychological stress level was evaluated with the hospital anxiety and depression scale (HAD) and state-trait anxiety inventory (STAI) questionnaire forms. Following the evaluations, the patients were divided into 4 groups according their stress and clinical status (Ia, Ib, IIa, IIb). IL-1ß, IL-6, IL-10, IFNα, GRα, sAA gene expression levels in the saliva samples were quantified by quantitative polymerase chain reaction (qPCR). RESULTS: In the group of peri-implantitis who had a high score in stress level assessment scales, significantly higher IL-1ß, IL-6, sAA expression levels were observed (p < 0.001). The IL-10 gene expression levels were lower in the groups with a high score in the stress level assessment scales (p < 0.001). GRα gene was expressed at lower levels in the group of peri-implantitis who had a high score in stress level assessment scales but the difference was not statistically significant (p = 0.065). CONCLUSION: The study findings suggest that psychological stress may increase the inflammation associated with peri-implantitis by affecting cytokine expression levels. CLINICAL RELEVANCE: To prevent peri-implantitis or reduce its prevalence, it could be beneficial to evaluate stress levels and identify individuals experiencing stress.

Peri-implant phenotype, calprotectin and MMP-8 levels in cases diagnosed with peri-implant disease.

OBJECTIVES: The purpose of this prospective cohort study is to evaluate the effect of peri-implant phenotype (PPh) on the severity of peri-implant diseases and the results of non-surgical mechanical treatment (NSMT), along with calprotectin (CLP) and MMP-8(matrix metalloproteinase-8) levels. MATERIALS AND METHODS: 77 implants from 39 patients were included. The implants were categorized Group-1(peri-implant mucositis), Group-2(peri-implantitis).Baseline (0. Month-PrT) clinical parameters (PD, GI, PI, BOP, CAL) and radiographic bone loss were documented, and peri-implant crevicular fluid (PICF) samples were collected. Various intruments and methodologies were employed to assess PPh components (mucosa thickness, supracrestal tissue height, keratinized mucosa) and peri-implant attached mucosa (AM). NSMT was applied to diseased implant sites. All clinical parameters were reassessed again by taking PICF samples at the 6th month-after treatment (PT). In PICF samples obtained from both groups, MMP-8 and CLP levels were evaluated using the ELISA test. RESULTS: PrT-PD,PrT-GI,PrT-CAL and PrT-BOP percentage values in Group-2 were significantly higher than Group-1.PrT-PD,PrTPI scores are significantly higher in thin biotype implants. All components of the PPh and AM were significantly lower in thin biotype. Intra-group time-dependent changes of MMP-8 and CLP were significant in both groups (p < 0.05). When the relationship between thin and thick biotype and biochemical parameters was evaluated, the change in PrT-PT didn't show a significant difference (p > 0.05). CONCLUSIONS: PPh plays a role in influencing the severity of peri-implant diseases. However, the impact of phenotype on NSMT outcomes was similar in both groups. CLINICAL RELEVANCE: The PPh should be considered when planning implant surgery.

Expression of miRNAs (146a and 155) in human peri-implant tissue affected by peri-implantitis: a case control study.

BACKGROUND: In literature, the levels of miRNA-146a and miRNA-155 are increased in periodontitis. Limited data are available regarding the expression of miRNA-146a and miR-NA-155 in diseased human peri-implant tissue. Therefore, the objective of this study was to explore the expression of miRNA-146a and miRNA-155 in human gingival peri-implant tissue affected by peri-implantitis. METHODS: After recording the clinical parameters, human peri-implant pocket tissues were harvested from sites diagnosed with peri-implantitis (n = 15 cases) in addition to healthy peri-implant sulcus tissues (n = 15 controls). The levels of miRNA-146a and miRNA-155 were assessed using real-time qPCR. RESULTS: Cases exhibited a significantly higher mean expression of miRNA-155 (5.2-fold increase) and miRNA-146a (2.8-fold increase) than controls. MiRNA-155 and miRNA-146a demonstrated an appropriate sensitivity (87.5% and 87.5%, respectively) and specificity (73.3% and 66.7%, respectively) in discriminating cases from controls. A moderate correlation (r = 0.544, p = 0.029) was found between miRNA-155 and miRNA-146a levels in the case group. CONCLUSIONS: The expressions of miRNA-146a and miR-NA-155 are different between healthy and peri-implantitis affected tissues. Both miRNAs might potentially able to discriminate healthy from peri-implantitis affected tissues.

Immunohistochemical analysis with apoptosis and autophagy markers in periodontitis and peri-implantitis: Clinical comparative study.

BACKGROUND AND OBJECTIVES: Recently, the terms autophagy and apoptosis have been studied on implants, especially in cell culture and in vitro studies, but in vivo evaluations are limited. The aim of this study was to compare the differences in apoptosis and autophagy intensity at the molecular and cellular level in periodontal and peri-implant diseases. METHODS: Sixty-four biopsy samples were obtained from 52 patients, 36 female and 16 male, whose mean age was between 18 and 75, and were included in the study. The periodontitis group was defined as PG (n:30 sample) and the peri-implantitis group as IG (n:34 samples). Granulation tissues as biopsy materials were collected, and immunohistochemical analysis was performed with hematoxylin-eosin, Masson's trichrome, anti-MAP1LC3A, anti-beclin, and anti-active caspase-3 antibodies and terminal TdT-mediated dUTP-biotin nick end labeling (TUNEL) methods. The histological slide images were evaluated with the ImageJ software program. Inflammatory cell density in epithelial tissue, inflammatory cell density in connective tissue, the density of necrotic tissue debris, and collagen density in connective tissue were scored between 0 and 3 (0: none, 1: minimal, 2: moderate, 3: severe by hematoxylin-eosin and Masson's trichrome). The antibody binding reaction areas were evaluated per unit area (mm2 ) in connective tissue by immunohistochemical examination. RESULTS: As histochemical evaluations, there was no statistically significant differences the mean inflammatory cell density value in the epithelial tissue, inflammatory cell density value in the connective tissue, density value of necrotic tissue debris, collagen density value in the connective tissue between the groups. There was no statistically significant difference on immunohistochemical staining with LC3, caspase-3, Beclin-1 and TUNEL between the two groups (p > .05). CONCLUSIONS: A higher rate of inflammatory accumulation was shown on peri-implantitis, but no difference was found between periodontitis and peri-implantitis according to autophagy and apoptosis markers. Studies with high sample sizes with different markers are needed.

Notch signalling cascade and proinflammatory mediators in peri-implant lesions with different RANKL/OPG ratios-An observational study.

BACKGROUND & OBJECTIVE: Notch signaling pathway has been linked to bone loss in periodontitis and peri-implantitis. This research aimed to determine the Notch signaling molecules expression levels (Notch1, Notch2, Jagged1, Hes1, and Hey1), along with bone remodeling mediators (RANKL and OPG) and proinflammatory cytokines (TNF-α, IL-17, IL-1ß, and IL-6) in patients with peri-implant diseases. The aforementioned markers' expression was evaluated in patients with different RANKL/OPG ratios. METHODS: Fifty patients with peri-implantitis (PI group) and 45 patients with peri-implant mucositis (PM group) were enrolled. Relative gene expression levels of investigated molecules were determined by reverse transcriptase-real-time polymerase chain reaction. On the basis of RANKL/OPG ratio, all peri-implant lesions were divided into subgroups: RANKL-predominant (RANKL > OPG) and OPG-predominant (RANKL < OPG). Clinical periodontal parameters (probing depth-PD, bleeding on probing-BOP, clinical attachment level-CAL and plaque index-PLI), were recorded for each patient around every tooth, and around placed implants (PDi, BOPi, CALi, PLIi). RESULTS: RANKL-predominant PM patients exhibited higher expression levels of Notch2 (p = .044) and Hey1 (p = .005) compared to OPG-predominant lesions. In all RANKL-predominant cases, Hey1 (p = .001), IL-1ß (p = .005), IL-6 (p = .002) were overexpressed in PI comparing to PM, accompanied with significantly higher PDi, CALi and PLIi in PI than PM (p = .001, p = .001 and p = .009). CONCLUSIONS: Notch2 upregulation in RANKL-predominant PM lesions could be an important contributor to alveolar bone resorption and represent a predictor of PM to PI transition. Similarly, the overexpression of IL-1ß and IL-6 might provide an osteoclastogenic environment in PI RANKL-predominant lesions.

Reprogramming mitochondrial metabolism of macrophages by miRNA-released microporous coatings to prevent peri-implantitis.

Although various new biomaterials have enriched the methods for peri-implant inflammation treatment, their efficacy is still debated, and secondary operations on the implant area have also caused pain for patients. Recently, strategies that regulate macrophage polarization to prevent or even treat peri-implantitis have attracted increasing attention. Here, we prepared a laser-drilled and covered with metal organic framework-miR-27a agomir nanomembrane (L-MOF-agomir) implant, which could load and sustain the release of miR-27a agomir. In vitro, the L-MOF-agomir titanium plate promoted the repolarization of LPS-stimulated macrophages from M1 to M2, and the macrophage culture supernatant promoted BMSCs osteogenesis. In a ligation-induced rat peri-implantitis model, the L-MOF-agomir implants featured strong immunomodulatory activity of macrophage polarization and alleviated ligation-induced bone resorption. The mechanism of repolarization function may be that the L-MOF-agomir implants promote the macrophage mitochondrial function and metabolism reprogramming from glycolysis to oxidative phosphorylation. Our study demonstrates the feasibility of targeting cell metabolism to regulate macrophage immunity for peri-implantitis inhibition and provides a new perspective for the development of novel multifunctional implants.

A GP130-Targeting Small Molecule, LMT-28, Reduces LPS-Induced Bone Resorption around Implants in Diabetic Models by Inhibiting IL-6/GP130/JAK2/STAT3 Signaling.

In this study, we examined the effect of the GP130-targeting molecule, LMT-28, on lipopolysaccharide- (LPS-) induced bone resorption around implants in diabetic models using in vitro and rat animal experiments. First, LMT-28 was added to osteoblasts stimulated by LPS and advanced glycation end products (AGEs), and nuclear factor-κB receptor-activating factor ligand (RANKL) and associated pathways were evaluated. Then, LMT-28 was administered by gavage at 0.23 mg/kg once every 5 days for 2 weeks to type 2 diabetic rats with peri-implantitis induced by LPS injection and silk ligature. The expression of IL-6 and RANKL was evaluated by immunohistochemistry, and the bone resorption around implants was evaluated by microcomputed tomography. The results showed that LMT-28 downregulated the expression of RANKL through the JAK2/STAT3 signaling pathway in osteoblasts stimulated by LPS and AGEs, reduced bone resorption around implants with peri-implantitis, decreased the expression of IL-6 and RANKL, and decreased osteoclast activity in type 2 diabetic rats. This study confirmed the ability of LMT-28 to reduce LPS-induced bone resorption around implants in diabetic rats.

Revealing leukocyte populations in human peri-implantitis and periodontitis using flow cytometry.

OBJECTIVE: To identify, quantify, and characterize leukocyte populations in PI and periodontitis using flow cytometry. METHODS: Fresh biopsies from human PI and periodontitis lesions were processed to a single-cell suspension. The immune cell types were identified using flow cytometry. RESULTS: Twenty-one biopsies were obtained and analyzed corresponding to fourteen PI and seven periodontitis samples. Participants' average age was 63.95 ± 14.77 years without a significant difference between PI and periodontitis patients, the female/male ratio was 8/12, and mean PD was 8.5 ± 2.17. High similarity was found between periodontitis and PI in the main immune cell types. Out of the leukocytes, the PMN proportion was 40% in PI and 33% in periodontitis. T-cells 22% in PI and 18% in periodontitis. Similar proportions of B-cells 10% and macrophages 6% were found in PI and periodontitis. Dendritic and NK cells were found in low proportions (~ 1%) in PI and periodontitis. T-cell sub-analysis showed that CD4-positive were more prevalent than CD8-positive in both diseases (CD4/CD8 ratio of 1.2). CONCLUSION: With the use of flow cytometry analysis, the leukocyte populations in human peri-implantitis and periodontitis were classified. In PI and periodontitis, we identified similar proportions of specific (CD4/CD8) and innate (dendritic and NK) immune cells. These results corroborate previous histological studies. CLINICAL RELEVANCE: Flow cytometry analysis can be used to identify and quantify immune cells in PI and periodontitis, including sub-classification of T cells (CD4/8) as well as detection of cells that require multiple markers for identification (such as dendritic cells).

Docosahexaenoic Acid-Loaded Nanostructured Lipid Carriers for the Treatment of Peri-Implantitis in Rats.

Being the most common cause of implant failure, peri-implantitis is defined as a pathological condition associated with the occurrence of peri-implant plaque, characterized by peri-implant mucosal inflammation and progressive loss of the supporting bone tissue attributed to the persistence of pro-inflammatory cytokines. Docosahexaenoic acid (DHA), which is a type of omega-3 polyunsaturated fatty acid, is generally used for the treatment of many inflammatory diseases. However, a suitable form for dosing and its therapeutic effect on peri-implantitis remain unclear. In this study, a novel nanostructured lipid carrier (NLC) loaded with squalene and DHA was fabricated (DHA-loaded NLC). The encapsulation efficiency and drug loading efficiency values of the DHA-loaded NLC were 78.13% ± 1.85% and 28.09% ± 0.48%, respectively. The release of DHA was gradual and steady until 144 h. In addition, the free-radical-scavenging rate of DHA-loaded NLC (0.57 ± 0.03) was much higher than that of sole DHA (0.17 ± 0.003). By inhibiting nuclear factor-κB p65 nuclear translocation, DHA-loaded NLC prevented the activation of nuclear factor-κB downstream inflammatory pathways and exerted anti-inflammatory effects on macrophages. Moreover, DHA-loaded NLC showed better effects on preventing alveolar bone resorption of rat peri-implantitis model than sole DHA. Hence, DHA-loaded NLC enhanced the anti-inflammatory bioavailability of DHA, offering a novel approach for the treatment of peri-implantitis.

Yth m6A RNA-Binding Protein 1 Regulates Osteogenesis of MC3T3-E1 Cells under Hypoxia via Translational Control of Thrombospondin-1.

Peri-implantitis is a major factor affecting implant prognosis, and the specific anatomy of the peri-implant area makes it more vulnerable to the local hypoxic environment caused by inflammation. N6-methyladenosine (m6A) plays a vital role in a multitude of biological processes, and its main "reader" Yth m6A RNA-binding protein 1 (YTHDF1) is suggested to affect osteogenic differentiation. However, the mechanism underlying the effect of YTHDF1 on osteogenic differentiation under hypoxic conditions remains unclear. To address this question, we examined the expression of YTHDF1 under hypoxia and observed that hypoxia suppressed osteogenic differentiation but promoted the expression of YTHDF1. Then we knocked down YTHDF1 and found decreased levels of osteogenic-related markers, alkaline phosphatase (ALP) activity, and alizarin red staining (ARS) under normoxia or hypoxia treatment. Bioinformatics analysis identified Thrombospondin-1 (THBS1) might be a downstream factor of YTHDF1. The results revealed that YTHDF1 enhanced the stability of THBS1 mRNA, and immunofluorescence assays found co-localization with YTHDF1 and THBS1 under hypoxia. Loss of function studies showed knocking down YTHDF1 or THBS1 exacerbated the osteogenic inhibition caused by hypoxia. All data imply that hypoxia suppresses osteogenic differentiation and promotes the expression of YTHDF1, which translationally regulates THBS1 in an m6A-dependent manner, potentially counteracting hypoxia-induced osteogenic inhibition through the YTHDF1/THBS1 pathway. The results of this study reveal for the first time the molecular mechanism of the regulation of osteogenic differentiation by YTHDF1 under hypoxia and suggest that YTHDF1, together with its downstream factor THBS1, may be critical targets to counteract osteogenic inhibition under hypoxic conditions, providing promising therapeutic strategy for the hypoxia-induced bone loss in peri-implantitis.

Effects of Candidalysin Derived from Candida albicans on the Expression of Pro-Inflammatory Mediators in Human Gingival Fibroblasts.

Candida albicans (Ca) is frequently detected in the peri-implant sulcus with peri-implantitis, a major postoperative complication after oral implant therapy. However, the involvement of Ca in the pathogenesis of peri-implantitis remains unclear. In this study, we aimed to clarify Ca prevalence in the peri-implant sulcus and investigated the effects of candidalysin (Clys), a toxin produced by Ca, on human gingival fibroblasts (HGFs). Peri-implant crevicular fluid (PICF) was cultured using CHROMagar and Ca colonization rate and colony numbers were calculated. The levels of interleukin (IL)-1ß and soluble IL-6 receptor (sIL-6R) in PICF were quantified by enzyme-linked immunosorbent assay (ELISA). Pro-inflammatory mediator production and intracellular signaling pathway (MAPK) activation in HGFs were measured by ELISA and Western blotting, respectively. The Ca colonization rate and the average number of colonies in the peri-implantitis group tended to be higher than those in the healthy group. IL-1ß and sIL-6R levels in the PICF were significantly higher in the peri-implantitis group than in the healthy group. Clys significantly induced IL-6 and pro-matrix metalloproteinase (MMP)-1 productions in HGFs, and co-stimulation with Clys and sIL-6R increased IL-6, pro-MMP-1, and IL-8 production levels in HGFs compared with Clys stimulation alone. These findings suggest that Clys from Ca plays a role in the pathogenesis of peri-implantitis by inducing pro-inflammatory mediators.

Retrospective Case-Control Study Genes Related to Bone Metabolism That Justify the Condition of Periodontal Disease and Failure of Dental Implants in Patients with down Syndrome.

Down syndrome patients show success rates in dental implants much lower than those observed in the general population. This retrospective case-control study aimed to identify possible genes that are related to the regulation of inflammatory responses and bone metabolism related to periimplantitis and implant loss, as well as genes related to bone quality. This process involved using the functional analysis of the gene expression software Transcriptome Analysis Console (TAC version 4.0 Applied BiosystemsTM, Thermo Fisher Scientific, Waltham, MA, USA) and a search for possible candidate genes involved. The focus was placed on the 93 genes related to periodontitis, periimplantitis, bone loss, implant loss, and genes related to bone quality and regulators underlying the establishment and maintenance of osseointegration. Five genes showed statistically significant results (p < 0.05) in our comparison. Four of them, IL1B (p = 0.023), IL1RN (p = 0.048), BGLAP (p = 0.0372) and PTK2 (p = 0.0075) were down-regulated in the periodontal disease and implant rejection group, and only one was overexpressed: FOXO1A (p = 0.0552). The genes with statistically significant alterations described in this article determine that the group of Down syndrome patients with periodontal disease and implant failure is a group of patients genetically susceptible to suffering from both conditions together.

MicroRNA sequence and function analysis in peri-implantitis and periodontitis: An animal study.

OBJECTIVE: To compare miRNA expression levels and predict relevant target genes and signaling pathways in peri-implantitis and periodontitis. BACKGROUND: There are many differences between periodontitis and peri-implantitis. An understanding of the similarities and differences in the transcriptional patterns of these diseases, as well as the molecular mechanisms, is beneficial for the development of management strategies. MATERIALS AND METHODS: Rat models of periodontitis (PD, n = 6) and peri-implantitis (PI, n = 5) were established by ligation. Implantation without ligation (PIC, n = 5) and normal rats (PDC, n = 6) were used as controls. Micro-CT was used to confirm the successful establishment of the model. Gingiva was harvested for miRNA transcriptome sequencing, and the results were confirmed by qRT-PCR. miRNA target genes were predicted with miRTarBase. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. RESULTS: Sixty-nine miRNAs were differentially expressed in PI vs. PD, 105 were differentially expressed in PI vs. PIC, and 70 were differentially expressed in PD vs. PDC (log2 FC ≥1 and padj <0.05). The upregulated genes in all three comparisons were mostly involved in the biological process response to stimulus, whereas most of the downregulated genes were involved in nervous system development (p < .01). The upregulated genes in PI vs. PD and PI vs. PIC were involved in Toll-like receptor signaling and RIG-I-like signaling. The upregulated genes in PI vs. PD were involved in T- and B-cell receptor signaling, apoptosis, and osteoclast differentiation. Focal adhesion was downregulated in all three comparisons, and adherens junction was downregulated in PI vs. PD and PD vs. PDC (p < .1). CONCLUSION: This study showed differences in the miRNA expression profiles between peri-implantitis and periodontitis and annotated the possible target genes and molecular mechanisms; this study could lay a foundation for the development of management strategies.

Immunopathological Inflammation in the Evolution of Mucositis and Peri-Implantitis.

The purpose of this study was to provide an immuno-mediated substantiation of the etiopathogenesis of mucositis and peri-implantitis based on the results of experimental, laboratory and clinical studies. The biopsy material was studied to identify impregnated nanoscale and microscale particles in the structure of pathological tissues by using X-ray microtomography and X-ray fluorescence analyses. Electron microscopy with energy-dispersive analysis identified the composition of supernatants containing nanoscale metal particles obtained from the surfaces of dental implants. The parameters of the nanoscale particles were determined by dynamic light scattering. Flow cytometry was used to study the effect of nanoscale particles on the ability to induce the activation and apoptosis of immunocompetent cells depending on the particles' concentrations during cultivation with the monocytic cell line THP-1 with the addition of inductors. An analysis of the laboratory results suggested the presence of dose-dependent activation, as well as early and late apoptosis of the immunocompetent cells. Activation and early and late apoptosis of a monocytic cell line when THP-1 was co-cultured with nanoscale metal particles in supernatants were shown for the first time. When human venous blood plasma was added, both activation and early and late apoptosis had a dose-dependent effect and differed from those of the control groups.

Levels of SERPIN family proteins in peri-implant crevicular fluid in patients with peri-implantitis.

PURPOSE: Serine protease inhibitors (SERPINs) family has been discovered in many disorders with proteolysis mechanisms. Our study determined the SERPINBs protein expression via public-based GEO databases and further validated by peri-implant crevicular fluid (PICF) of peri-implantitis patients and healthy recruiters. METHODS: This study is a retrospective analysis. A total of 123 participants of Fujian Medical University Fujian Stomatological Hospital, consisting of 58 cases of peri-implantitis and 65 samples of healthy control were retrospectively analyzed by ELISA assays and explored the gene enrichment pathways and clinical significance of SERPINBs expression accompanied by two different cytokines (IL-6 and TNF-α). Moreover, the clinical significance of SERPINBs was evaluated in peri-implantitis patients with PICF samples by the receiver operating curve (ROC) using the area under the curve (AUC). RESULTS: KEGG database showed that Starch and sucrose metabolism, Retrograde endocannabinoid signaling, Prion diseases, Pentose phosphate pathways, and Olfactory pathways are up-regulated; GO database showed that synapse organization, synapse assembly, sequestering of triglyceride, sensory perception of smell, and regulation of synapse organization pathways are up-regulated. SERPINBs were overexpressed in peri-implant tissues and peri-implantitis patients with PICF. SERPINBs was positively correlated to IL-6 and TNF-α in peri-implantitis patients with PICF. The ROC-AUCs of SERPINBs achieved a significantly higher range from 0.895 to 0.939 in peri-implantitis patients with PICF. Therefore, certain SERPINBs expressions were not only perceived through PICF and peri-implant tissues but also showed potential significance in peri-implantitis. CONCLUSION: SERPINBs play an influential role in the pathogenesis of peri-implantitis via binding with other inflammatory cytokines.

Distribution and Chemical Speciation of Exogenous Micro- and Nanoparticles in Inflamed Soft Tissue Adjacent to Titanium and Ceramic Dental Implants.

Degradation of the implant surface and particle release/formation as an inflammation catalyst mechanism is an emerging concept in dental medicine that may help explain the pathogenesis of peri-implantitis. The aim of the present study was a synchrotron-based characterization of micro- and nanosized implant-related particles in inflamed human tissues around titanium and ceramic dental implants that exhibited signs of peri-implantitis. Size, distribution, and chemical speciation of the exogenous micro- and nanosized particle content were evaluated using synchrotron µ-X-ray fluorescence spectroscopy (XRF), nano-XRF, and µ-X-ray absorption near-edge structure (XANES). Titanium particles, with variable speciation, were detected in all tissue sections associated with titanium implants. Ceramic particles were found in five out of eight tissue samples associated with ceramic implants. Particles ranged in size from micro- to nanoscale. The local density of both titanium and ceramic particles was calculated to be as high as ∼40 million particles/mm3. µ-XANES identified titanium in predominantly two different chemistries, including metallic and titanium dioxide (TiO2). The findings highlight the propensity for particle accumulation in the inflamed tissues around dental implants and will help in guiding toxicological studies to determine the biological significance of such exposures.

Wnt5a is involved in LOX-1 and TLR4 induced host inflammatory response in peri-implantitis.

BACKGROUND AND OBJECTIVE: Peri-implantitis is a plaque-associated pathological condition occurring in tissues around dental implants, characterized by inflammation in the peri-implant mucosa and subsequent progressive loss of supporting bone. Wnt5a is the activating ligand of the non-canonical Wnt signaling pathways and plays important roles in leukocyte infiltration and cytokine/ chemokine production in inflammatory disorders. Previous studies showed that Wnt5a was significantly up-regulated in gingival tissues of chronic and aggressive periodontitis. However, the roles and the regulatory mechanisms of Wnt5a in peri-implantitis are not well known. METHODS: The expression of Wnt5a in gingival tissues collected from 8 healthy implant patients and 8 peri-implantitis patients was analyzed by Western blotting and immunofluorescence. Porphyromonas gingivalis infected macrophages isolated from the peripheral blood of healthy volunteers were used as an in vitro cellular model of peri-implantitis. Using neutralizing antibodies, inhibitors and siRNA, the production and roles of Wnt5a in peri-implantitis were assessed by immunofluorescence, quantitative polymerase chain reaction (RT-PCR) and Western blotting. Unpaired two-tailed Student's t test was used to compare qRT-PCR and Western blotting results. P ≤ .05 was considered statistically significant. RESULTS: Wnt5a was highly expressed in the gingival tissues of peri-implantitis patients. Compared to controls, Wnt5a increased in P gingivalis infected macrophages. Wnt5a production in response to P gingivalis infection was dependent on LOX-1 and TLR4. Compared to controls, Wnt5a knockdown impaired IL-1ß, MCP-1, and MMP2 production induced by P gingivalis infection. CONCLUSION: Our results indicate that Wnt5a is involved in LOX-1 and TLR4 induced inflammatory signature via inflammatory cytokines production in response to P gingivalis infection. These findings demonstrate that Wnt5a maybe an important component of the host immune response in peri-implantitis.