Anti-inflammatory effects of zinc in PMA-treated human gingival fibroblast cells

Bioactivity and antibacterial effects of zinc-containing bioactive glass on the surface of zirconia abutments

OBJECTIVES

This study aimed to enhance gingival fibroblast function and to achieve antibacterial activity around the implant abutment by using a zinc (Zn)-containing bioactive glass (BG) coating.

METHODS

45S5 BG containing 0, 5, and 10 wt.% Zn were coated on zirconia disks. The release of silica and Zn ions in physiological saline and their antibacterial effects were measured. The effects of BG coatings on human gingival fibroblasts (hGFs) were assessed using cytotoxicity assays and by analyzing the gene expression of various genes related to antioxidant enzymes, wound healing, and fibrosis.

RESULTS

BG coatings are capable of continuous degradation and simultaneous ion release. The antibacterial effect of BG coatings increased with the addition of Zn, while the cytotoxicity remained unchanged compared to the group without coatings. BG coating enhances the expression of angiogenesis genes, while the Zn-containing BG enhances the expression of antioxidant genes at an early time point. BG coating enhances the expression of collagen genes at later time points.

CONCLUSIONS

The antibacterial effect of BG improved with the increase in Zn concentration, without inducing cytotoxicity. BG coating enhances the expression of angiogenesis genes, and Zn-containing BG enhances the expression of antioxidant genes at an early time point. BG coating enhances the expression of collagen genes at later time points.

CLINICAL SIGNIFICANCE

Adding 10 wt% Zn to BG could enhance the environment around implant abutments by providing antibacterial, antioxidant, and anti-fibrotic effects, having potential for clinical use.

The changes and potential effects of zinc homeostasis in periodontitis microenvironment

Zinc is a very important and ubiquitous element, which is present in oral environment, daily diet, oral health products, dental restorative materials, and so on. However, there is a lack of attention to the role of both extracellular or intracellular zinc in the progression of periodontitis and periodontal regeneration. This review summarizes the characteristics of immunological microenvironment and host cells function in several key stages of periodontitis progression, and explores the regulatory effect of zinc during this process. We find multiple evidence indicate that zinc may be involved and play a key role in the stages of immune defense, inflammatory response and bone remodeling. Zinc supplementation in an appropriate dose range or regulation of zinc transport proteins can promote periodontal regeneration by either enhancing immune defense or up-regulating local cells proliferation and differentiation functions. Therefore, zinc homeostasis is essential in periodontal remodeling and regeneration. More attention is suggested to be focused on zinc homeostasis regulation and consider it as a potential strategy in the studies on periodontitis treatment, periodontal-guided tissue regeneration, implant material transformation, and so on.

Molecular pathogenicity of 1-nonadecene and L-lactic acid, unique metabolites in radicular cysts and periapical granulomas

Recently, 1-nonadecene and L-lactic acid were identified as unique metabolites in radicular cysts and periapical granuloma, respectively. However, the biological roles of these metabolites were unknown. Therefore, we aimed to investigate the inflammatory and mesenchymal-epithelial transition (MET) effects of 1-nonadecene, and the inflammatory and collagen precipitation effects of L-lactic acid on both periodontal ligament fibroblasts (PdLFs) and peripheral blood mononuclear cells (PBMCs). PdLFs and PBMCs were treated with 1-nonadecene and L-lactic acid. Cytokines' expression was measured using quantitative real-time polymerase chain reaction (qRT-PCR). E-cadherin, N-cadherin, and macrophage polarization markers were measured using flow cytometry. The collagen, matrix metalloproteinase (MMP)-1, and released cytokines were measured using collagen assay, western blot, and Luminex assay, respectively. In PdLFs, 1-nonadecene enhances inflammation through the upregulation of some inflammatory cytokines including IL-1β, IL-6, IL-12A, monocyte chemoattractant protein (MCP)-1, and platelet-derived growth factor (PDGF) α. 1-Nonadecene also induced MET through the upregulation of E-cadherin and the downregulation of N-cadherin in PdLFs. 1-Nonadecene polarized macrophages to a pro-inflammatory phenotype and suppressed their cytokines' release. L-lactic acid exerted a differential impact on the inflammation and proliferation markers. Intriguingly, L-lactic acid induced fibrosis-like effects by enhancing collagen synthesis, while inhibiting MMP-1 release in PdLFs. These results provide a deeper understanding of 1-nonadecene and L-lactic acid's roles in modulating the microenvironment of the periapical area. Consequently, further clinical investigation can be employed for target therapy.

Immunomodulatory effects of chicken cathelicidin-2 on a primary hepatic cell co-culture model

Cathelicidin-2 is an antimicrobial peptide (AMP) produced as part of the innate immune system of chickens and might be a new candidate to combat infection and inflammation within the gut-liver axis. Studying the hepatic immune response is of high importance as the liver is primarily exposed to gut-derived pathogen-associated molecular patterns. The aim of the present study was to assess the effects of chicken cathelicidin-2 alone or combined with lipoteichoic acid (LTA) or phorbol myristate acetate (PMA) on cell viability, immune response and redox homeostasis in a primary hepatocyte-non-parenchymal cell co-culture of chicken origin. Both concentrations of cathelicidin-2 decreased the cellular metabolic activity and increased the extracellular lactate dehydrogenase (LDH) activity reflecting reduced membrane integrity. Neither LTA nor PMA affected these parameters, and when combined with LTA, cathelicidin-2 could not influence the LDH activity. Cathelicidin-2 had an increasing effect on the concentration of the proinflammatory CXCLi2 and interferon- (IFN-)γ, and on that of the anti-inflammatory IL-10. Meanwhile, macrophage colony stimulating factor (M-CSF), playing a complex role in inflammation, was diminished by the AMP. LTA elevated IFN-γ and decreased M-CSF levels, while PMA only increased the concentration of M-CSF. Both concentrations of cathelicidin-2 increased the H2O2 release of the cells, but the concentration of malondialdehyde as a lipid peroxidation marker was not affected. Our findings give evidence that cathelicidin-2 can also possess anti-inflammatory effects, reflected by the alleviation of the LTA-triggered IFN-γ elevation, and by reducing the M-CSF production induced by PMA. Based on the present results, cathelicidin-2 plays a substantial role in modulating the hepatic immune response with a multifaceted mode of action. It was found to have dose-dependent effects on metabolic activity, membrane integrity, and reactive oxygen species production, indicating that using it in excessively high concentrations can contribute to cell damage. In conclusion, cathelicidin-2 seems to be a promising candidate for future immunomodulating drug development with an attempt to reduce the application of antibiotics.

Optimizing the bio-degradability and biocompatibility of a biogenic collagen membrane through cross-linking and zinc-doped hydroxyapatite

Biogenic collagen membranes have been widely used as soft tissue barriers in guided bone regeneration (GBR) and guided tissue regeneration (GTR). Nevertheless, their clinical performance remains unsatisfactory because of their low mechanical strength and fast degradation rate in vivo. Although cross-linking with chemical agents is effective and reliable for prolonging the degradation time of collagen membranes, some adverse effects including potential cytotoxicity and undesirable tissue integration have been observed during this process. As a fundamental nutritional trace element, zinc plays an active role in promoting the growth of cells and regulating the degradation of the collagen matrix. Herein, a biogenic collagen membrane was cross-linked with glutaraldehyde-alendronate to prolong its degradation time. The physiochemical and biological properties were enhanced by the incorporation of zinc-doped nanohydroxyapatite (nZnHA), with the native structure of collagen preserved. Specifically, the cross-linking combined with the incorporation of 1% and 2% nZnHA seemed to endow the membrane with the most appropriate biocompatibility and tissue integration capability among the cross-linked membranes, as well as offering a degradation period of six weeks in a rat subcutaneous model. Thus, improving the clinical performance of biogenic collagen membranes by cross-linking together with the incorporation of nZnHA is a promising strategy for the improvement of biogenic collagen membranes. STATEMENT OF SIGNIFICANCE: The significance of this research includes.

Oral wound healing models and emerging regenerative therapies

Following injury, the oral mucosa undergoes complex sequences of biological healing processes to restore homeostasis. While general similarities exist, there are marked differences in the genomics and kinetics of wound healing between the oral cavity and cutaneous epithelium. The lack of successful therapy for oral mucosal wounds has influenced clinicians to explore alternative treatments and potential autotherapies to enhance intraoral healing. The present in-depth review discusses current gold standards for oral mucosal wound healing and compares endogenous factors that dictate the quality of tissue remodeling. We conducted a review of the literature on in vivo oral wound healing models and emerging regenerative therapies published during the past twenty years. Studies were evaluated by injury models, therapy interventions, and outcome measures. The success of therapeutic approaches was assessed, and research outcomes were compared based on current hallmarks of oral wound healing. By leveraging therapeutic advancements, particularly within in cell-based biomaterials and immunoregulation, there is great potential for translational therapy in oral tissue regeneration.

Two Sides to Every Question: Attempts to Activate Chicken Innate Immunity in 2D and 3D Hepatic Cell Cultures

The liver with resident tissue macrophages is the site of vivid innate immunity, activated also by pathogen-associated molecular patterns (PAMPs) leaking through the intestinal barrier. As gut-derived inflammatory diseases are of outstanding importance in broiler chickens, the present study aimed to establish a proper hepatic inflammatory model by comparing the action of different PAMPs from poultry pathogens on chicken 2D and 3D primary hepatocyte—non-parenchymal cell co-cultures, the latter newly developed with a magnetic bioprinting method. The cultures were challenged by the bacterial endotoxins lipopolysaccharide (LPS) from Escherichia coli, lipoteichoic acid (LTA) from Staphylococcus aureus and by enterotoxin (ETxB) from Escherichia coli, Salmonella Typhimurium derived flagellin, phorbol myristate acetate (PMA) as a model proinflammatory agent and polyinosinic polycytidylic acid (poly I:C) for mimicking viral RNA exposure. Cellular metabolic activity was assessed with the CCK-8 test, membrane damage was monitored with the lactate dehydrogenase (LDH) leakage assay and interleukin-6 and -8 (Il-6 and -8) concentrations were measured in cell culture medium with a chicken specific ELISA. Both LPS and LTA increased the metabolic activity of the 3D cultures, concomitantly decreasing the LDH leakage, while in 2D cultures ETxB stimulated, PMA and poly I:C depressed the metabolic activity. Based on the moderately increased extracellular LDH activity, LTA seemed to diminish cell membrane integrity in 2D and poly I:C in both cell culture models. The applied endotoxins remarkably reduced the IL-8 release of 3D cultured cells, suggesting the effective metabolic adaptation and the presumably initiated anti-inflammatory mechanisms of the 3D spheroids. Notwithstanding that the IL-6 and IL-8 production of 2D cells was mostly not influenced by the endotoxins used, only the higher LTA dose was capable to evoke an IL-8 surge. Flagellin, PMA and poly I:C exerted proinflammatory action in certain concentrations in both 2D and 3D cultures, reflected by the increased cellular IL-6 release. Based on these data, LTA, flagellin, PMA and poly I:C can be considered as potent candidates to induce inflammation in chicken primary hepatic cell cultures, while LPS failed to trigger proinflammatory cytokine production, suggesting the relatively high tolerance of avian liver cells to certain bacterial endotoxins. These results substantiate that the established 3D co-cultures seemed to be proper tools for testing potential proinflammatory molecules; however, the remarkable differences between 2D and 3D models should be addressed and further studied.

Effect of zinc on oropharyngeal mucositis in children with acute leukemia undergoing chemotherapy

Background

Oropharyngeal mucositis (OM) is one of the main side-effects of oncological therapy. There is no treatment to prevent its occurrence, but some zinc-based therapies have been proven to help in decreasing its intensity. The objective of this study was to determine the effect of zinc in OM in children with acute leukemia in the early stages of oncological treatment.

Material and Methods

This quasi-experimental study evaluated OM in 2 groups (control group: conventional hospital management, and experimental group: administration of 50 mg of zinc gluconate daily plus conventional hospital management). OM severity was recorded at a two-month follow-up.

Results

Forty-nine patients (26 in the control group and 23 in the experimental group) were included. The mean age of the patients was 11.1 ± 2.7 years; 65.3% had a diagnosis of pre-B acute lymphoblastic leukemia. The incidences of OM in the control group and the experimental group were 46.2% and 26.1%, respectively, but the difference was not significant. Based on a negative binomial regression model, females had, on average, 1.5 more days with OM (p = 0.002), and patients assigned to the experimental group had, on average, 2 less days with OM than the control group (p = 0.001). The pain score was higher in the control group (p = 0.0009), as was the mean score on the WHO scale (p = 0.0012).

Conclusions

Zinc facilitated a reduction in the severity and duration of OM; further studies focusing on children are needed to confirm the effects of this trace element.

Key words:Oropharyngeal, mucositis, zinc, chemotherapy, children, leukemia.

Preoperative oral zinc tablet decreases incidence of postoperative sore throat

Background and Aims

Postoperative sore throat (POST) is very frequently reported after endotracheal intubation. Zinc lozenge has been shown to reduce POST. The aim of this study was to evaluate the effect of dispersible zinc tablet on POST.

Methods

Eighty-eight patients undergoing surgery with endotracheal intubation were randomly allocated into two groups, to either receive dispersible zinc tablet 40 mg (zinc group) or placebo tablet (control group), 30 min preoperatively. Assessment for incidence and severity was performed for POST, on a 4-point scale (0-3) at 0, 30 min, 2, 4, and 24 h postoperatively. The primary outcome was incidence of POST at 4 h postoperatively. Secondary outcome was severity of POST at the 5 evaluation time points postoperatively. Mann-Whitney U test, Fisher's exact, and Chi-square test were used as applicable.

Results

At 4 h, there was a significantly lower incidence of POST in zinc group (6.8%) than the control group (31.8%) with a P value of 0.003. Three patients in placebo group complained of severe POST compared to none in the zinc group. The severity of POST was significantly lower in Zinc group than Placebo group at 0 min (P = 0.003), 30 min (P = 0.002), 2 h (P < 0.001), and 4 h (P = 0.001).

Conclusion

Preoperative administration of 40 mg dispersible zinc tablet effectively reduces the incidence and severity of POST in the immediate postoperative period.

Evaluation of zinc sulfate mucoadhesive formulation on recurrent aphthous stomatitis: a randomized double-blind, placebo-controlled clinical trial

BACKGROUND

Recurrent aphthous stomatitis (RAS) is a common lesion that affects the oral mucosa. There are several methods to treat RAS, including systemic and topical formulations. This study was conducted to evaluate the anti-inflammatory effect of topical zinc sulfate and its efficacy in the treatment of RAS.

METHODS

A double-blind randomized clinical trial was conducted on 46 patients with RAS. They were randomly assigned into two groups to receive a zinc sulfate mucoadhesive tablet or placebo for 7 days. The pain severity was measured at baseline and daily while the diameter of the lesion was measured at baseline and on days 3, 5, and 7. The obtained data were analyzed in SPSS V.16.

RESULTS

There was no significant difference in the mean diameter of lesions and pain at baseline between the two groups (P = 0.643 and P = 0.842, respectively). However, on the third, fifth, and seventh days of the study, the diameter of the lesion significantly reduced in the intervention group (P = 0.001) and the pain intensity became significantly different between groups from the fourth day of the study (P = 0.001).

CONCLUSION

Zinc sulfate mucoadhesive tablet was effective in recovery and reducing the pain and diameter of the aphthous lesion and could be considered for the treatment of RAS.

TRIAL REGISTRATION

Evaluation of the effectiveness of zinc sulfate mucoadhesive tablet in the improvement of recurrent aphthous stomatitis (RAS), IRCT20151109024975N9. Registered August 1, 2018, https://en.irct.ir/trial/32423 . This project was registered by the Iranian Registry of Clinical Trials ( http://www.irct.ir ). The IRCT ID was IRCT20151109024975N9.

Conditional nutrition (I): concerning zinc as a beneficial but variable regulator of inflammation and experimental arthritis

This article extends the concept of conditional pharmacology (Whitehouse and Vernon-Roberts 1991; Whitehouse 1995) that considers how both internal factors/disease and external/environmental factors may alter the availability or efficacy of exogenous drugs. The same and other conditioning factors may also affect the utility and value of many nutriceuticals that may be clearly beneficial in the context of inflammation but sometimes showing quite variable pharmaco-activity. This is illustrated by considering some factors affecting the bioavailability and pharmaco-efficacy of dietary ionic zinc, Zn (II) an essential trace metal and a critical regulator of inflammation and tissue repair. With chronic zinc deficiency (zincopenia) due to diet, drugs and/or disease, we can usually survive-but may not necessarily thrive. Some strategies to minimise zincopenia are considered, based upon finding efficient means for (1) preventing its cause and/or (2) using parenteral delivery of zinc supplements to circumvent dietary and enteric impediments to zinc bio-availability.

Topical oral wound healing potential of anthocyanin complex: animal and clinical studies

Aim: An anthocyanin complex (AC), combined Zea mays and Clitoria ternatea extracts, was evaluated for topical oral wound healing in rats and a clinical trial in orthodontic patients. Methods/results: AC enhanced anthocyanin permeation in vitro. In rats, 10% w/w of AC in a mucoadhesive gel (AG) reduced erythema and sizes of oral wounds after topical applications at higher extent than its placebo gel. Acute orthodontic wounds in 68 volunteers were randomly assigned to topically receive either AG or placebo gel and double-blind assessed. Wound size reduction and wound closure enhancement were obvious in AG-treated group on day 3 (p < 0.05). Conclusion: At 10% w/w, AC promoted wound closure and possessed a potential in healing stimulation of acute oral wounds.

Topical Niosome Gel Containing an Anthocyanin Complex: a Potential Oral Wound Healing in Rats

Anthocyanins from dietary sources showing potential benefits as anti-inflammatory in oral lesions were developed as an anthocyanin complex (AC), comprised of extracts of Zea mays (CC) and Clitoria ternatea (CT), and formulated into a niosome gel to prove its topical oral wound healing in vitro and in vivo investigations. The AC formed nano-sized clusters of crystalline-like aggregates, occurring through both intra- and inter-molecular interactions, resulting in delivery depots of anthocyanins, following encapsulation in niosomes and incorporation into a mucoadhesive gel. In vitro permeation of anthocyanins was improved by complexation and further enhanced by encapsulation in niosomes. Collagen production in human gingival fibroblasts was promoted by AC and AC niosomes, but not CC or CT. The in vivo wound healing properties of AC gel (1 and 10%), AC niosome gel (1 and 10%), fluocinolone acetonide gel, and placebo gel were investigated for incisional wounds in the buccal cavities of Wistar rats. AC gel and AC niosome gel both reduced wound sizes after 3 days. AC niosome gel (10%) gave the highest reduction in wound sizes after day 3 (compared to fluocinolone acetonide gel, p < 0.05), and resulted in 100% wound healing by day 5. Histological observations of cross-sectioned wound tissues revealed the adverse effects of fluocinolone gel and wound healing potential of AC niosome gel. Topical application of AC niosome gel exhibited an anti-inflammatory effect and promoted oral wound closure in rats, possibly due to the improved mucosal permeability and presence of delivery depots of AC in the niosome gel.

Evaluation of serum zinc levels in patients with recurrent aphthous stomatitis (RAS)

BACKGROUND

Recurrent aphthous stomatitis (RAS) is an ulcerative disease of the oral mucosa without a clearly defined etiology. The aim of the study was to evaluate the serum zinc levels in patients with RAS in comparison to healthy controls and to validate the association between zinc levels and the course of RAS.

METHODS

Seventy-five patients with RAS and 72 controls underwent full dental examination. Serum zinc levels were determined by flame atomic absorption spectroscopy (F AAS). The results were statistically analyzed with Kruskal-Wallis, Mann-Whitney, chi-square tests and the test of difference between the two rates of structure with p < 0.05 as a significance level (Statistica 10, StatSoft®).

RESULTS

No statistically significant differences were detected in serum zinc levels between RAS patients and healthy controls. The mean serum zinc concentration was found to be 84.2 μg/dL in RAS group and 83.9 μd/dL in controls, within the accepted norms. Zinc deficiency was observed in 10.7% patients from the RAS group and in 6.9% controls. No significant differences in serum zinc levels were found between patients when the course of the disease was considered.

CONCLUSIONS

Serum zinc concentrations did not differ significantly in RAS patients and in healthy controls and it did not influence the course of the disease. Therefore, zinc does not appear to be an important modifying factor in the development of RAS.

The Effect of Zinc Lozenge on Postoperative Sore Throat: A Prospective Randomized, Double-Blinded, Placebo-Controlled Study

BACKGROUND

Postoperative sore throat (POST) is commonly seen after endotracheal intubation, and oral zinc prevents oral mucositis associated with chemotherapy. This study is designed to evaluate the effects of administration of zinc lozenges on POST.

METHODS

Seventy-nine patients undergoing low- or moderate-risk surgery with endotracheal intubation were randomly assigned into 2 groups: Control group received placebo and zinc group received 40-mg zinc lozenges 30 minutes preoperatively. Patients were assessed for incidence and severity (4-point scale, 0-3) of POST at 0, 2, 4, and 24 hours postoperatively. The primary outcome was incidence of POST at 4 hours after surgery. The secondary outcomes were the incidence of POST at 0, 2, and 24 hours and the severity of POST.

RESULTS

At 4 hours, there was a significantly lower incidence of POST in the zinc group, 7%, than the control group, 29% (P = .046). The incidence of POST at 0 hour was 0% in zinc group and 24% in control group (P = .004). The highest incidence of POST occurred at the second hour after surgery, with the rate of 10% in the zinc group and 34% in the control group (P = .0495). The incidence of POST at 24 hours was 13% in zinc group and 24% in control group (not significant). The severity of POST was significantly lower in the zinc group for mild (P = .003) and moderate (P = .004) POST.

CONCLUSIONS

The administration of a single dose of 40-mg zinc lozenge 30 minutes preoperatively is effective to reduce both incidence of POST in the first 4 hours and severity of mild and moderate POST in the immediate postoperative period.