Antioxidant effects of melatonin in heart tissue after induction of experimental periodontitis in rats

Beneficial Effects of Melatonin on Periodontitis Management: Far More Than Oral Cavity

Periodontitis as a highly prevalent chronic infection/inflammatory disease can eventually lead to tooth loss and masticatory dysfunction. It also has a negative impact on general health and largely impairs quality of life. The tissue destruction during periodontitis is mainly caused by the excessive immune-inflammatory response; hence, how to modulate the host's reaction is of profound importance for effective periodontal treatment and tissue protection. Melatonin, as an endogenous hormone exhibiting multiple biological functions such as circadian rhythm regulation, antioxidant, and anti-inflammation, has been widely used in general healthcare. Notably, the past few years have witnessed increasing evidence for the application of melatonin as an adjunctive approach in the treatment of periodontitis and periodontitis-related systemic comorbidities. The detailed underlying mechanisms and more verification from clinical practice are still lacking, however, and further investigations are highly required. Importantly, it is essential to establish standard guidelines in the near future for the clinical administration of melatonin for periodontal health and general wellbeing.

High-efficient serum-free differentiation of endothelial cells from human iPS cells

Introduction

Endothelial cells (ECs) form the inner lining of all blood vessels of the body play important roles in vascular tone regulation, hormone secretion, anticoagulation, regulation of blood cell adhesion and immune cell extravasation. Limitless ECs sources are required to further in vitro investigations of ECs’ physiology and pathophysiology as well as for tissue engineering approaches. Ideally, the differentiation protocol avoids animal-derived components such as fetal serum and yields ECs at efficiencies that make further sorting obsolete for most applications.

Method

Human induced pluripotent stem cells (hiPSCs) are cultured under serum-free conditions and induced into mesodermal progenitor cells via stimulation of Wnt signaling for 24 h. Mesodermal progenitor cells are further differentiated into ECs by utilizing a combination of human vascular endothelial growth factor A165 (VEGF), basic fibroblast growth factor (bFGF), 8-Bromoadenosine 3′,5′-cyclic monophosphate sodium salt monohydrate (8Bro) and melatonin (Mel) for 48 h.

Result

This combination generates hiPSC derived ECs (hiPSC-ECs) at a fraction of 90.9 ± 1.5% and is easily transferable from the two-dimensional (2D) monolayer into three-dimensional (3D) scalable bioreactor suspension cultures. hiPSC-ECs are positive for CD31, VE-Cadherin, von Willebrand factor and CD34. Furthermore, the majority of hiPSC-ECs express the vascular endothelial marker CD184 (CXCR4).

Conclusion

The differentiation method presented here generates hiPSC-ECs in only 6 days, without addition of animal sera and at high efficiency, hence providing a scalable source of hiPSC-ECs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02924-x.

Resveratrol prevents inflammation and oxidative stress response in LPS-induced human gingival fibroblasts by targeting the PI3K/AKT and Wnt/β-catenin signaling pathways

This study aimed to elucidate the anti-inflammatory and antioxidant properties of resveratrol (RSV) in human gingival fibroblasts (HGFs) following stimulation by P. gingivalis lipopolysaccharide (LPS). The levels of the inflammatory cytokines IL-1β, IL-6, IL-8 and TNFα, the activity of the antioxidant enzymes SOD and GSH-Px, and the levels of MDA, were evaluated by ELISA. It was observed that the expression of IL-1β, IL-6, IL-8 and TNFα in LPS-induced HGFs was significantly downregulated by RSV in a dose-dependent manner. RSV also partly increased oxidative stress (OS)-related factors, including SOD and GSH-Px, which was accompanied by a decrease in MDA production, although the results were not statistically significant. Additionally, RSV-induced deactivation of the PI3K/AKT and Wnt/β-catenin pathways in LPS-induced HGFs was observed by western blot analysis. Subsequently, it was demonstrated treatment with PI3K/AKT pathway inhibitor (LY294002) or Wnt/β-catenin pathway inhibitor (Dickkopf-1, DKK-1) could further enhance the anti-inflammatory and antioxidant effects of RSV by downregulating the expression of IL-1β, IL-6, IL-8 and TNFα, and the production of MDA, and increasing the activity of SOD and GSH-Px in LPS-induced HGFs. These results suggested RSV attenuated the inflammation and OS injury of P. gingivalis LPS-treated HGFs by deactivating the PI3K/AKT and Wnt/β-catenin signaling pathways.

Melatonin ameliorates periodontitis-related inflammatory stress at cardiac left ventricular tissues in rats

BACKGROUND

The aim of this experimental rat study was to investigate the potential inflammatory effects of periodontitis on cardiac left ventricular tissue and the therapeutic activity of melatonin on these effects.

METHODS

Twenty-four male Sprague-Dawley rats were randomly divided into three groups: control, experimental periodontitis (Ep), and Ep-melatonin (Ep-Mel). Experimental periodontitis was induced by placing and maintaining 3.0 silk ligatures at a peri marginal position on the left and right mandibular first molars for 5 weeks. Afterward, following the removal of ligatures, melatonin (10 mg/body weight) to Ep-Mel group, and vehicle (saline) to Ep and control groups were administered intraperitoneally for 14 days. On the first day of the eighth week, mandibular and cardiac left ventricular tissue samples were obtained following the euthanasia of the rats in all groups. Alveolar bone loss measurements were made on histological and microcomputed tomographic slices. Cardiac tissue levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), matrix metalloproteinase-9 (MMP-9), and cardiac Troponin-T (cTnT) were evaluated by appropriate biochemical methods.

RESULTS

Measurements made on the histological and microcomputed tomographic slices showed that melatonin significantly limits the ligature-induced periodontal tissue destruction (P <0.01). In addition, melatonin was detected to cause a significant decrease of MDA, MMP-9, and cTnT levels which were found to be significantly higher on rats with Ep (P <0.05) while having no significant effect on antioxidant levels (GSH, SOD, and CAT) (P >0.05).

CONCLUSION

Melatonin might be regarded as an important supportive therapeutic agent to reduce the early degenerative changes and possible hypertrophic remodeling at cardiac left ventricular tissues provoked by periodontitis-related bacteria and/or periodontal inflammation.

Antioxidant and Anti-Inflammatory Properties of Melatonin in Patients with Type 2 Diabetes Mellitus with Periodontal Disease Under Non-Surgical Periodontal Therapy: A Double-Blind, Placebo-Controlled Trial

BACKGROUND AND AIM

The imbalance between pro-oxidant and antioxidant systems often leads to further oxidative damage in the pathogenesis of both diabetes and periodontal disease. This study aimed to investigate the antioxidant and anti-inflammatory properties of melatonin in type 2 diabetes mellitus (T2DM) patients with periodontal disease (PD) under non-surgical periodontal therapy (NSPT).

MATERIALS AND METHODS

In this double-blind clinical trial study, 50 T2DM patients with PD were randomly allocated to intervention and control groups and received 250 mg/day (2 tablets) either melatonin or placebo 1 h before bedtime for 8 weeks. The NSPT was performed for all patients in both groups at the beginning of the study. The serum levels of interleukin-1b (IL-1b), malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were measured pre- and post-intervention.

RESULTS

Supplementation with melatonin in adjunct to NSPT significantly increased the serum levels of TAC, SOD, CAT, and GPx in the intervention group (P = 0.02, 0.008, 0.004 and 0.004, respectively). The mean changes of SOD, CAT, and GPx were significantly (P = 0.02, 0.04 and 0.04, respectively) greater in the intervention group compared with the control group. Also, after adjusting for confounding factors, the results did not change in terms of significance (P < 0.05). After the intervention, serum levels of MDA and IL-1b were significantly reduced in the intervention group (P < 0.001 and P = 0.008, respectively). The intervention group exhibited lower mean changes of MDA compared with the control group, and these changes were statistically significant (P = 0.008). In addition, after adjusting for confounding factors, the results did not change in terms of significance.

CONCLUSION

The adjunctive effects of melatonin and NSPT may improve inflammatory and antioxidant parameters in T2DM patients with PD.

Prophylactic supplement with melatonin successfully suppresses the pathogenesis of periodontitis through normalizing RANKL/OPG ratio and depressing the TLR4/MyD88 signaling pathway

Periodontitis (PD) is an inflammatory disease characterized by gingival inflammation and resorption of alveolar bone. Impaired receptor activator of nuclear factor-kappa B ligand/osteoprotegerin (RANKL/OPG) signaling caused by enhanced production of pro-inflammatory cytokines plays an essential role in the pathogenesis of PD. Considering melatonin possesses significant anti-inflammatory property, this study aimed to determine whether prophylactic treatment with melatonin would effectively normalize RANKL/OPG signaling, depress toll-like receptor 4/myeloid differentiation factor 88 (TLR4/MyD88)-mediated pro-inflammatory cytokine activation, and successfully suppress the pathogenesis of PD. PD was induced in adult rats by placing the ligature at molar subgingival regions. Fourteen days before PD induction, 10, 50, or 100 mg/kg of melatonin was intraperitoneally injected for consecutive 28 days. Biochemical and enzyme-linked immunosorbent assay were used to detect TLR4/MyD88 activity, RANKL, OPG, interleukin 1β, interleukin 6, and tumor necrosis factor-α levels, respectively. The extent of bone loss, bone mineral intensity, and calcium intensity was further evaluated by scanning electron microscopy, micro-computed tomography, and energy-dispersive X-ray spectroscopy. Results indicated that high RANKL/OPG ratio, TLR4/MyD88 activity, and pro-inflammatory cytokine levels were detected following PD. Impaired biochemical findings paralleled well with severe bone loss and reduced calcium intensity. However, in rats pretreated with melatonin, all above parameters were successfully returned to nearly normal levels with maximal change observed in rats receiving 100 mg/kg. As prophylactic treatment with melatonin effectively normalizes RANKL/OPG signaling by depressing TLR4/MyD88-mediated pro-inflammatory cytokine production, dietary supplement with melatonin may serve as an advanced strategy to strengthen oral health to counteract PD-induced destructive damage.

Oxidative Stress and Antioxidants in the Diagnosis and Therapy of Periodontitis

Oxidative stress has been implicated in the pathogenesis of numerous diseases. However, large interventional studies with antioxidants failed to show benefits in the prevention or treatment of cardiovascular diseases, cancer, or diabetes mellitus. Numerous clinical studies have confirmed the association of oxidative stress markers and periodontitis. Technical and biological variability is high for most of the analyzed markers and none of them seems to be optimal for routine clinical use. In a research setting, analysis of a palette of oxidative stress markers is needed to cover lipid peroxidation, protein oxidation, and the antioxidant status. The source of reactive oxygen species and their role in the pathogenesis of periodontitis remains unclear. Interventional experiments indicate that oxidative stress might be more than just a simple consequence of the inflammation. Small studies have confirmed that some antioxidants could have therapeutic value at least as an addition to the standard non-surgical treatment of periodontitis. A clear evidence for the efficiency of antioxidant treatment in large patient cohorts is lacking. Potentially, because lowering of oxidative stress markers might be a secondary effect of anti-inflammatory or antibacterial agents. As the field of research of oxidative stress in periodontitis gains attraction and the number of relevant published papers is increasing a systematic overview of the conducted observational and interventional studies is needed. This review summarizes the currently available literature linking oxidative stress and periodontitis and points toward the potential of adjuvant antioxidant treatment, especially in cases where standard treatment fails to improve the periodontal status.