25-Hydroxyvitamin D(3)-loaded PLA microspheres: in vitro characterization and application in diabetic periodontitis models

Impact of local drug delivery and natural agents as new target strategies against periodontitis: new challenges for personalized therapeutic approach

Periodontitis is a persistent inflammation of the soft tissue around the teeth that affects 60% of the population in the globe. The self-maintenance of the inflammatory process can cause periodontal damage from the alveolar bone resorption to tooth loss in order to contrast the effects of periodontitis, the main therapy used is scaling and root planing (SRP). At the same time, studying the physiopathology of periodontitis has shown the possibility of using a local drug delivery system as an adjunctive therapy. Using local drug delivery devices in conjunction with SRP therapy for periodontitis is a potential tool since it increases drug efficacy and minimizes negative effects by managing drug release. This review emphasized how the use of local drug delivery agents and natural agents could be promising adjuvants for the treatment of periodontitis patients affected or not by cardiovascular disease, diabetes, and other system problems. Moreover, the review evidences the current issues and new ideas that can inspire potential later study for both basic research and clinical practice for a tailored approach.

Local drug delivery systems as therapeutic strategies against periodontitis: A systematic review

Periodontitis is a chronic inflammation of the soft tissue surrounding and supporting the teeth, which causes periodontal structural damage, alveolar bone resorption, and even tooth loss. Its prevalence is very high, with nearly 60% of the global population affected. Hence, periodontitis is an important public health concern, and the development of effective healing treatments for oral diseases is a major target of the health sciences. Currently, the application of local drug delivery systems (LDDS) as an adjunctive therapy to scaling and root planning (SRP) in periodontitis is a promising strategy, giving higher efficacy and fewer side effects by controlling drug release. The cornerstone of successful periodontitis therapy is to select an appropriate bioactive agent and route of administration. In this context, this review highlights applications of LDDS with different properties in the treatment of periodontitis with or without systemic diseases, in order to reveal existing challenges and future research directions.

Blending of PLGA-PEG-PLGA for Improving the Erosion and Drug Release Profile of PCL Microspheres

BACKGROUND

PCL has a long history as an industrialized biomaterial for preparing microspheres, but its hydrophobic property and slow degradation rate often cause drug degeneration, quite slow drug release rate and undesirable tri-phasic release profile.

MATERIALS AND METHODS

In this study, we used the blending material of PLGA-PEG-PLGA and PCL to prepare microspheres. The microspheres degradation and drug release behaviors were evaluated through their molecular weight reduction rate, mass loss rate, morphology erosion and drug release profile. The hydrophilic PLGA-PEG-PLGA is expected to improve the degradation and drug release behaviors of PCL microspheres.

RESULTS

Microspheres in blending materials exhibited faster erosion rates than pure PCL microspheres, forming holes much quickly on the particle's surface for the drug to diffuse out. A higher proportion of PLGA-PEG-PLGA caused faster degradation and erosion rates. The blending microspheres showed much faster drug release rates than pure PCL microspheres.

CONCLUSION

With blending of 25wt% PLGA-PEG-PLGA, the release rate of microspheres speeded up significantly, while, with a further increase of PLGA-PEG-PLGA proportion (50%, 75%, 100%), it accelerated a little. The microspheres with PCL/PLGA-PEG-PLGA of 1/1 exhibited a linear-like drug release profile. The results could be a guideline for preparing microspheres based on blending materials to obtain a desirable release.

Biodegradable engineered fiber scaffolds fabricated by electrospinning for periodontal tissue regeneration

Considering the specificity of periodontium and the unique advantages of electrospinning, this technology has been used to fabricate biodegradable tissue engineering materials for functional periodontal regeneration. For better biomedical quality, a continuous technological progress of electrospinning has been performed. Based on property of materials (natural, synthetic or composites) and additive novel methods (drug loading, surface modification, structure adjustment or 3 D technique), various novel membranes and scaffolds that could not only relief inflammation but also influence the biological behaviors of cells have been fabricated to achieve more effective periodontal regeneration. This review provides an overview of the usage of electrospinning materials in treatments of periodontitis, in order to get to know the existing research situation and find treatment breakthroughs of the periodontal diseases.

Emerging Applications of Drug Delivery Systems in Oral Infectious Diseases Prevention and Treatment

The oral cavity is a unique complex ecosystem colonized with huge numbers of microorganism species. Oral cavities are closely associated with oral health and sequentially with systemic health. Many factors might cause the shift of composition of oral microbiota, thus leading to the dysbiosis of oral micro-environment and oral infectious diseases. Local therapies and dental hygiene procedures are the main kinds of treatment. Currently, oral drug delivery systems (DDS) have drawn great attention, and are considered as important adjuvant therapy for oral infectious diseases. DDS are devices that could transport and release the therapeutic drugs or bioactive agents to a certain site and a certain rate in vivo. They could significantly increase the therapeutic effect and reduce the side effect compared with traditional medicine. In the review, emerging recent applications of DDS in the treatment for oral infectious diseases have been summarized, including dental caries, periodontitis, peri-implantitis and oral candidiasis. Furthermore, oral stimuli-responsive DDS, also known as "smart" DDS, have been reported recently, which could react to oral environment and provide more accurate drug delivery or release. In this article, oral smart DDS have also been reviewed. The limits have been discussed, and the research potential demonstrates good prospects.

Mangiferin alleviates experimental peri-implantitis via suppressing interleukin-6 production and Toll-like receptor 2 signaling pathway

BACKGROUND

TLR2 (Toll-like receptor 2) signaling and its downstream proinflammatory cytokines are considered to be important in the progression of peri-implantitis. A natural medicine, mangiferin has exhibited modulatory effect on TLR2 signaling and anti-inflammatory effects on different diseases. The objective of the present study is to investigate the effect of mangiferin on peri-implantitis and the potential mechanisms by administering this drug to an experimental peri-implantitis mouse model.

METHODS

Maxillary left first, second, and third molars of mice were extracted, and dental implants were placed in the region of the maxillary left second molars. Then, peri-implantitis was induced by tying ligatures around implants, and mangiferin was given orally to the mice. After 6-week mangiferin treatment, bone loss around the implants was detected using micro-computerized tomography (micro-CT). Alveolar bone and inflammatory infiltrate in peri-implant tissues were examined using hematoxylin and eosin (H&E) staining. Production of interleukin-6 (IL6), a TLR2 downstream proinflammatory cytokine, in the tissue surrounding implants was measured using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis. IL6 protein expression and TLR2 signaling pathway activation in peri-implant tissues were detected using western blot analysis.

RESULTS

Micro-CT demonstrated reduced bone loss in peri-implantitis upon mangiferin administration. Additionally, H&E staining showed more alveolar bone and less inflammatory infiltrate in peri-implant tissues after mangiferin application. Moreover, qRT-PCR analysis demonstrated lower levels of IL6 gene expression, and western blot analysis showed decreased protein expression of IL6 and TLR2, and suppressed phosphorylation of TLR2 downstream nuclear factor-κB, p38 mitogen-activated protein kinase, and c-Jun N-terminal kinase after mangiferin treatment.

CONCLUSIONS

These results suggest the suppressive effect of mangiferin on bone damage and inflammatory infiltrate in peri-implantitis. These therapeutic effects may be associated with inhibited IL6 production and reduced TLR2 signaling activation in peri-implant tissues.

Drug Delivery Systems for Vitamin D Supplementation and Therapy

Vitamin D (VD) is a fat-soluble prohormone well known for its role in regulating calcium and phosphate metabolism. It has been clinically used for many years to prevent rickets in children, osteomalacia, and osteoporosis in adults. VD insufficiency is a common medical condition, and many supplements are available in the market in order to increase serum 25-hydroxy VD levels to recommended amounts. Over the course of the last decades, it has become increasingly clear that calcitriol, an active form of VD, regulates multiple cellular processes with effects on normal and malignant cell growth and differentiation, and on the immune and cardiovascular function. Increasing evidence supports the role of the VD system in cancer prevention and therapy. Due to many pleiotropic and beneficial effects in extra-skeletal disorders, VD has gained potential and become an interesting active for encapsulation into drug delivery systems. The purpose of this review is to present the diversity of drug delivery systems that have been reported for VD or VD derivatives in an orderly manner across the following categories: Oral administration, application on the skin, cancer prevention/therapy, and other diseases or routes of administration.

Suppression of NLRP3 inflammasome improves alveolar bone defect healing in diabetic rats

Background

Excessive inflammatory response under hyperglycemia can impair alveolar bone defect healing under diabetic conditions. NLRP3 (NACHT [nucleotide-binding oligomerization], LRR [leucine-rich repeat], and PYD [pyrin domain] domains-containing protein 3) inflammasome has been considered to play a crucial role in the inflammatory response, but its correlation with the impaired alveolar bone repair in diabetes still remains unclarified. The objective of the current study is to investigate the effect of NLRP3 inflammasome inhibition by a lentiviral short hairpin RNA (shRNA) targeting NLRP3 on alveolar bone defect healing in diabetic rats.

Methods

Diabetes was induced in rats by high-fat diet and streptozotocin injection, and alveolar bone defects in both maxillae were created by surgery. Then, the lentiviral shRNA targeting NLRP3 was applied in the defect. Eight weeks after surgery, the alveolar bone regeneration was examined using hematoxylin and eosin (H&E) staining, and the gene expression in the bone healing site was detected using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis and western blot analysis.

Results

H&E staining showed that treatment with lentiviral shRNA targeting NLRP3 could increase the bone regeneration score in the alveolar bone defect of diabetic rats. Additionally, qRT-PCR analysis and western blot analysis of the bone defect demonstrated that this shRNA inhibited the expression of NLRP3, apoptosis-associated speck-like protein containing a CARD, caspase-1, and proinflammatory cytokine interleukin-1β and increased the expression of osteogenic markers Runt-related transcription factor 2 and osteocalcin.

Conclusions

Our findings suggested that inhibition of NLRP3 inflammasome could improve alveolar bone defect healing in diabetic rats. The beneficial effect may correlate with reduced proinflammatory cytokine production and increased osteogenic gene expression in hyperglycemia.

Electronic supplementary material

The online version of this article (10.1186/s13018-019-1215-9) contains supplementary material, which is available to authorized users.

1,25-dihydroxyvitamin-D3 promotes neutrophil apoptosis in periodontitis with type 2 diabetes mellitus patients via the p38/MAPK pathway

BACKGROUND

Abnormal neutrophils are involved in many chronic endocrine diseases, including type 2 diabetes mellitus (T2DM), and in periodontitis (PD), which is a chronic inflammatory disease in which neutrophils play a vital role. The p38 mitogen-activated protein kinase (MAPK) signaling pathway participates in the apoptosis of many inflammatory cells. Additionally, 1,25-dihydroxyvitamin-D3 (1,25VitD3) as a regulator can induce responses to infection and tumor cell apoptosis. However, the effect of 1,25VitD3 in the pathogenic relationship between T2DM and PD remains unclear. The aim of this study was to assess the effect of 1,25VitD3 on neutrophil apoptosis in patients with T2DM and PD and the p38-MAPK-relevant signaling pathway mechanism in this process in vitro.

METHODS

Neutrophils were stained with Wright's stain, and apoptosis was detected by flow cytometry and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining. Apoptosis- and p38-related mRNAs and proteins were examined by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blotting and ELISA. The internal relationships were analyzed using a linear regression equation and Pearson's correlation coefficient.

RESULTS

The highest rate of neutrophil apoptosis occurred in cultures treated with 10 mol/L 1,25VitD3 in the T2DM-PD group. The apoptosis rate in the T2DM-PD-p38 inhibitor group was higher than that in the healthy control group. Western blot, ELISA and qRT-PCR results showed that the mRNA and protein expression profiles of Caspase-3 and Bax were highly up-regulated and that Bcl-2 was down-regulated in the T2DM-PD-p38 inhibitor group. The expression levels of apoptotic mRNAs and proteins in the T2DM and T2DM-PD groups were significantly higher than those in the T2DM-p38 and T2DM-PD-p38 inhibitor groups. 1,25VitD3-induced neutrophil apoptosis and phosphorylated p38 (p-p38) expression were partially inhibited by the p38 inhibitor. Expression levels of apoptosis-related genes and p-p38 in neutrophils were positively associated with increasing concentrations of 1,25VitD3. p-p38 protein expression was positively associated with the level of serum 1,25VitD3.

CONCLUSION

1,25VitD3 could promote peripheral blood neutrophil apoptosis in patients with T2DM and PD through activation of the p38-MAPK signaling pathway in vitro.

Vitamin D attenuates human gingival fibroblast inflammatory cytokine production following advanced glycation end product interaction with receptors for AGE

BACKGROUND AND OBJECTIVES

Vitamin D [1,25(OH)₂ D₃ or 1,25D3] is critical in musculoskeletal health, inflammation, immune response, and glucose metabolism. Patients with vitamin D deficiency may be at higher risk of diabetes and periodontitis. Diabetic patients exhibit exacerbated inflammation and more periodontal destruction. Advanced glycation end products (AGEs), formed during diabetic hyperglycemia, activate inflammatory pathways in periodontitis. Human gingival fibroblasts (HGFs) express receptors for AGEs (RAGEs) and can contribute to inflammation.

OBJECTIVES

Determine whether glycated human serum albumin (G-HSA) augments HGF IL-6 and IL-8 production, and whether treatment with 1,25D3 attenuates cytokine production following stimulation with G-HSA + IL-1β and/or IL-17.

MATERIAL AND METHODS

HGFs were incubated ±G-HSA or normal human serum albumin (HSA), ±IL-1β and/or IL-17, ±1,25D3. Cytokines were measured by ELISA. Neutralizing anti-RAGE was used to assess AGE-RAGE interaction. Endotoxin was measured using the ToxinSensor™ System. Data were expressed as mean ± standard deviation and analyzed using a one-way analysis of variance (ANOVA) and Scheffe's F procedure for post hoc comparisons.

RESULTS

G-HSA or IL-1β, but not HSA, significantly stimulated IL-6 and IL-8 production. G-HSA or HSA when combined with IL-1β or IL-1β + IL-17 synergistically stimulated IL-6 and IL-8. Neutralizing anti-RAGE inhibited IL-6 and IL-8 produced by cells stimulated with IL-1β + G-HSA but not (+HSA). Synergism caused by HSA did not appear to be mediated by endotoxin since its levels in G-HSA and HSA were not sufficient to stimulate fibroblasts. Vitamin D inhibited IL-6 and IL-8 production stimulated by G-HSA or HSA + IL-1β or IL-1β + IL-17.

CONCLUSIONS

Results suggest that the "perioprotective" effects of vitamin D are related to its ability to regulate inflammatory cytokine production by HGFs following AGE-RAGE interaction.

The use of chitosan/PLA nano-fibers by emulsion eletrospinning for periodontal tissue engineering

OBJECTIVE

In this study, nanofibrous scaffolds base on pure polylactic acid (PLA) and chitosan/PLA blends were fabricated by emulsion eletrospinning. By modulating their mechanical and biological properties, cell-compatible and biodegradable scaffolds were developed for periodontal bone regeneration.

METHODS

Pure PLA and different weight ratios of chitosan nano-particle/PLA nano-fibers were fabricated by emulsion eletrospinning. Scanning electron microscope (SEM) was performed to observe the morphology of nano-fibers. Mechanical properties of nano-fibers were tested by single fiber strength tester. Hydrophilic/hydrophobic nature of the nano-fibers was observed by stereomicroscope. In vitro degradation was also tested. Cells were seeded on nano-fibers scaffolds. Changes in cell adhesion, proliferation and osteogenic differentiation were tested by MTT assay and Alizarin Red S staining. Reverse transcription-polymerase chain reaction (RT-PCR) assay was used to evaluate the expression of (Toll-like receptor 4) TLR4, IL-6, IL-8, IL-1β, OPG, RUNX2 mRNA.

RESULTS

It is shown that the mean diameter of nano-fibers is about 200 nm. The mean diameter of chitosan nano-particles is about 50 nm. The combination of chitosan nano-particles enhanced the mechanical properties of pure PLA nano-fibers. By adding a certain amount of chitosan nano-particles, it promoted cell adhesion. It also promoted the osteogenic differentiation of bone marrow stem cells (BMSCs) by elevating the expression of osteogenic marker genes such as BSP, Ocn, collagen I, and OPN and enhanced ECM mineralization. Nonetheless, it caused higher expression of inflammatory mediators and TLR4 of human periodontal ligament cells (hPDLCs).

CONCLUSION

The combination of chitosan nano-particles enhanced the mechanical properties of pure PLA nano-fibers and increased its hydrophilicity. Pure PLA nano-fibers scaffold facilitated BMSCs proliferation. Adding an appropriate amount of chitosan nano-particles may promote its properties of cell proliferation and osteogenic differentiation. The higher expression of inflammatory mediators caused by nano-fibers may be regulated via TLR4 pathway.

A novel multi-tiered experimental approach unfolding the mechanisms behind cyclodextrin-vitamin inclusion complexes for enhanced vitamin solubility and stability

This study was conducted to provide a mechanistic account for understanding the synthesis, characterization and solubility phenomena of vitamin complexes with cyclodextrins (CD) for enhanced solubility and stability employing experimental and in silico molecular modeling strategies. New geometric, molecular and energetic analyses were pursued to explicate experimentally derived cholecalciferol complexes. Various CD molecules (α-, β-, γ-, and hydroxypropyl β-) were complexed with three vitamins: cholecalciferol, ascorbic acid and α-tocopherol. The Inclusion Efficiency (IE%) was computed for each CD-vitamin complex. The highest IE% achieved for a cholecalciferol complex was for 'βCDD₃-8', after utilizing a unique CD:cholecalciferol molar synthesis ratio of 2.5:1, never before reported as successful. 2HPβCD-cholecalciferol, γCD-cholecalciferol and α-tocopherol inclusion complexes (IC's) reached maximal IE% with a CD:vitamin molar ratio of 5:1. The results demonstrate that IE%, thermal stability, concentration, carrier solubility, molecular mechanics and intended release profile are key factors to consider when synthesizing vitamin-CD complexes. Phase-solubility data provided insights into the design of formulations with IC's that may provide analogous oral vitamin release profiles even when hydrophobic and hydrophilic vitamins are co-incorporated. Static lattice atomistic simulations were able to validate experimentally derived cholecalciferol IE phenomena and are invaluable parameters when approaching formulation strategies using CD's for improved solubility and efficacy of vitamins.

Preparation and Evaluations of Mangiferin-Loaded PLGA Scaffolds for Alveolar Bone Repair Treatment Under the Diabetic Condition

The aim of the present study was to prepare and evaluate a sustained-release mangiferin scaffold for improving alveolar bone defect repair in diabetes. Mangiferin-loaded poly(D,L-lactide-co-glycolide) (PLGA) scaffolds were prepared using a freeze-drying technique with ice particles as the porogen material. The produced scaffolds were examined using a scanning electron microscope (SEM). Drug content and drug release were detected using a spectrophotometer. Degradation behaviors were monitored as a measure of weight loss and examined using SEM. Then, the scaffolds were incubated with rat bone marrow stromal cells under the diabetic condition in vitro, and cell viability was assessed using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Afterward, the scaffolds were implanted into alveolar bone defects of diabetic rats, and bone repair was examined using hematoxylin and eosin staining. The fabricated scaffolds showed porous structures, with average pore size range from 111.35 to 169.45 μm. A higher PLGA concentration led to decreased average pore size. A lower PLGA concentration or a higher mangiferin concentration resulted in increased drug content. The prepared scaffolds released mangiferin in a sustained manner with relatively low initial burst during 10 weeks. Their degradation ratios gradually increased as degradation proceeded. The mangiferin-loaded scaffolds attenuated cell viability decrease under the diabetic condition in vitro. Moreover, they increased histological scorings of bone regeneration and improved delayed alveolar bone defect healing in diabetic rats. These results suggest that the produced mangiferin-loaded scaffolds may provide a potential approach in the treatment of impaired alveolar bone healing in diabetes.

Inhibitory effect of 1,25-dihydroxyvitamin D3 on Porphyromonas gingivalis-induced inflammation and bone resorption in vivo

OBJECTIVE

To investigate whether intragastric administration of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) could inhibit the bone resorption and inflammation in a mouse calvarial model infected by Porphyromonas gingivalis (P. gingivalis).

DESIGN

Live P. gingivalis ATCC 33277 was injected once daily for 6days into the subcutaneous tissue overlying the calvaria in mice. At the same time, 1,25(OH)₂D₃ (50μg/kg per day) was administered by gavage for 9days, starting 3d before the infection. Mice were killed under ether anesthesia 8h after the last injection of P. gingivalis. Micro-computed tomography scanning was used to evaluate calvarial bone loss. Tartrate-resistant acid phosphatase was used to detect osteoclast activity. Real-time PCR was used to assess the mRNA expressions of OPG, RANKL, c-Fos, NFATc1, CTSK and TRAP in calvarial bone and IL-6, IL-10, IL-1β, IL-12p40 and TNF-α in soft tissue. The levels of serum IL-6, IL-10 were determined by ELISA.

RESULTS

1,25(OH)₂D₃ treatment apparently attenuated bone resorption in P. gingivalis-induced mouse calvarial model and markedly reduced the number of osteoclasts. The expression levels of RANKL and osteoclast-related genes such as c-Fos, NFATc1, CTSK and TRAP were also decreased by 1,25(OH)₂D₃. Besides, 1,25(OH)₂D₃ inhibited the expression of pro-inflammatory cytokines IL-6, IL-12p40 and TNF-α and enormously elevated the expression of anti-inflammatory cytokine IL-10.

CONCLUSION

1,25(OH)₂D₃ may decrease bone resorption in vivo via suppressing the expression of osteoclast-related genes and its anti-inflammatory properties.

Efficacy of local delivery of ardipusilloside I using biodegradable implants against cerebral tumor growth

Ardipusilloside I (ADS-I) is a natural compound that can be isolated from the Chinese medicinal herb Ardisiapusilla A.DC, and has been reported to inhibit the growth of glioblastoma cells in cultures. This study was designed to test its efficacy by the delivery using biodegradable implants against glioblastoma in vivo. ADS-I was incorporated into polymer microspheres, which were prepared by a mixture of poly (D, L-lactic acid) and poly (D, L-lactic-co-glycolic acid) polymers and then fabricated into wafers. The anti-glioma activities of ADS-I-loaded wafers were examined by methylthiazol tetrazolium (MTT) assay in cultured rat C6 glioma cells, and by magnetic resonance imaging (MRI) and survival monitoring in C6 glioma-bearing rats. Here, we showed that ADS-I-loaded wafers sustained ADS-I release in vitro for 36 days in Higuchi model of kinetics, and had the same cytotoxic activity as ADS-I in the solution against the growth of C6 glioma cells in cultures. In C6 glioma-bearing rats, ADS-I wafer implants inhibited tumor growth in a dose-dependent matter, and were more effective than the same dosage of ADS-I in the solution. The tumor suppression efficacies of ADS-I wafer implants were positively correlated with an increase in tumor cell apoptosis and prolonged animal survival, and were associated with a decrease in vascular endothelial growth factor, C-reactive protein, tumor necrosis factor-α and interleukin-6, and an increase in interleukin-2 expression. In conclusion, this study demonstrates significant efficacy of local delivery of ADS-I using polymer implants against glioma tumor growth in vivo, suggesting the potential of ADS-I-loaded wafers for glioma treatment.