Local Application of Pyrophosphorylated Simvastatin Prevents Experimental Periodontitis

The Development of Thermoresponsive Polymeric Simvastatin Prodrug for the Treatment of Experimental Periodontitis in Rats

Periodontitis (PD) is a severe inflammatory gum pathology that damages the periodontal soft tissue and bone. It is highly prevalent in the US, affecting more than 47% of adults. Besides routine scaling and root planing, there are few effective treatments for PD. Developed as an effective treatment for hyperlipidemia, simvastatin (SIM) is also known for its well-established anti-inflammatory and osteogenic properties, suggesting its potential utility in treating PD. Its clinical translation, however, has been impeded by its poor water-solubility, lack of osteotropicity, and side effects (e.g., hepatoxicity) associated with systemic exposure. To address these challenges, an N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based thermoresponsive polymeric prodrug of SIM (ProGel-SIM) was developed as a local therapy for PD. Its aqueous solution is free-flowing at 4 °C and transitions into a hydrogel at ∼30 °C, allowing for easy local application and retention. After a thorough characterization of its physicochemical properties, ProGel-SIM was administered weekly into the periodontal pocket of an experimental rat model of PD. At 3 weeks post initiation of the treatment, the animals were euthanized with palate isolated for μ-CT and histological analyses. When compared to dose equivalent simvastatin acid (SMA, active form of SIM) treatment, the rats in the ProGel-SIM treated group showed significantly higher periodontal bone volume (0.34 mm3 vs 0.20 mm3, P = 0.0161) and less neutrophil (PMN) infiltration (P < 0.0001) and IL-1β secretion (P = 0.0036). No measurable side effect was observed. Collectively, these results suggest that ProGel-SIM may be developed as a promising drug candidate for the effective clinical treatment of PD.

Pharmacological Therapies for the Management of Inflammatory Bone Resorption in Periodontal Disease: A Review of Preclinical Studies

Periodontitis, a highly prevalent multicausal chronic inflammatory and destructive disease, develops as a result of complex host-parasite interactions. Dysbiotic bacterial biofilm in contact with the gingival tissues initiates a cascade of inflammatory events, mediated and modulated by the host's immune response, which is characterized by increased expression of several inflammatory mediators such as cytokines and chemokines in the connective tissue. If periodontal disease (PD) is left untreated, it results in the destruction of the supporting tissues around the teeth, including periodontal ligament, cementum, and alveolar bone, which lead to a wide range of disabilities and poor quality of life, thus imposing significant burdens. This process depends on the differentiation and activity of osteoclasts, the cells responsible for reabsorbing the bone tissue. Therefore, the inhibition of differentiation or activity of these cells is a promising strategy for controlling bone resorption. Several pharmacological drugs that target osteoclasts and inflammatory cells with immunomodulatory and anti-inflammatory effects, such as bisphosphonates, anti-RANK-L antibody, strontium ranelate, cathepsin inhibitors, curcumin, flavonoids, specialized proresolving mediators, and probiotics, were already described to manage inflammatory bone resorption during experimental PD progression in preclinical studies. Meantime, a growing number of studies have described the beneficial effects of herbal products in inhibiting bone resorption in experimental PD. Therefore, this review summarizes the role of several pharmacological drugs used for PD prevention and treatment and highlights the targeted action of all those drugs with antiresorptive properties. In addition, our review provides a timely and critical appraisal for the scientific rationale use of the antiresorptive and immunomodulatory medications in preclinical studies, which will help to understand the basis for its clinical application.

A simvastatin-releasing scaffold with periodontal ligament stem cell sheets for periodontal regeneration

Simvastatin (SIM) has been documented to induce the osteogenic differentiation of periodontal ligament stem cells (PDLSCs). To establish an efficient release system for periodontal regeneration, a polycaprolactone (PCL) membrane scaffold containing SIM was electrospun and evaluated. The obtained PCL-SIM membrane scaffold showed sustained release up to 28 days, without deleterious effect on proliferation of PDLSCs on the scaffolds. PDLSCs were seeded onto scaffolds and their osteogenic differentiation was evaluated. After 21 days, expressions of collagen type I, alkaline phosphatase and bone sialoprotein genes were significantly upregulated and mineralized matrix formation was increased on the PCL-SIM scaffolds compared with the PCL scaffolds. In a heterotopic periodontal regeneration model, a cell sheet-scaffold construct was assembled by placement of multilayers of PDLSC sheets on PCL or PCL-SIM scaffolds, and these were then placed between dentin and ceramic bovine bone for subcutaneous implantation in athymic mice. After 8 weeks, the PCL-SIM membrane showed formation of significantly more ectopic cementum-like mineral on the dentin surface. These findings demonstrated that the PCL-SIM membrane scaffold promotes cementum-like tissue formation by sustained drug release, suggesting the feasibility of its therapeutic use with PDLSC sheets to improve periodontal regeneration.

Thermoresponsive Hydrogel-Based Local Delivery of Simvastatin for the Treatment of Periodontitis

Except for routine scaling and root planing, there are few effective nonsurgical therapeutic interventions for periodontitis and associated alveolar bone loss. Simvastatin (SIM), one of the 3-hydroxy-3-methylglutaryl-cosenzyme A reductase inhibitors, which is known for its capacity as a lipid-lowering medication, has been proven to be an effective anti-inflammatory and bone anabolic agent that has shown promising benefits in mitigating periodontal bone loss. The local delivery of SIM into the periodontal pocket, however, has been challenging due to SIM's poor water solubility and its lack of osteotropicity. To overcome these issues, we report a novel SIM formulation of a thermoresponsive, osteotropic, injectable hydrogel (PF127) based on pyrophosphorolated pluronic F127 (F127-PPi). After mixing F127-PPi with F127 at a 1:1 ratio, the resulting PF127 was used to dissolve free SIM to generate the SIM-loaded formulation. The thermoresponsive hydrogel's rheologic behavior, erosion and SIM release kinetics, osteotropic property, and biocompatibility were evaluated in vitro. The therapeutic efficacy of SIM-loaded PF127 hydrogel on periodontal bone preservation and inflammation resolution was validated in a ligature-induced periodontitis rat model. Given that SIM is already an approved medication for hyperlipidemia, the data presented here support the translational potential of the SIM-loaded PF127 hydrogel for better clinical management of periodontitis and associated pathologies.

GSK3 inhibitor-loaded osteotropic Pluronic hydrogel effectively mitigates periodontal tissue damage associated with experimental periodontitis

Periodontitis is a chronic inflammatory disease caused by complex interactions between the host immune system and pathogens that affect the integrity of periodontium. To prevent disease progression and thus preserve alveolar bone structure, simultaneous anti-inflammatory and osteogenic intervention are essential. Hence, a glycogen synthase kinase 3 beta inhibitor (BIO) was selected as a potent inflammation modulator and osteogenic agent to achieve this treatment objective. BIO's lack of osteotropicity, poor water solubility, and potential long-term systemic side effects, however, have hampered its clinical applications. To address these limitations, pyrophosphorylated Pluronic F127 (F127-PPi) was synthesized and mixed with regular F127 to prepare an injectable and thermoresponsive hydrogel formulation (PF127) of BIO, which could adhere to hard tissue and gradually release BIO to exert its therapeutic effects locally. Comparing to F127 hydrogel, PF127 hydrogels exhibited stronger binding to hydroxyapatite (HA). Additionally, BIO's solubility in PF127 solution was dramatically improved over F127 solution and the improvement was proportional to the polymer concentration. When evaluated on a rat model of periodontitis, PF127-BIO hydrogel treatment was found to be very effective in preserving alveolar bone and ligament, and preventing periodontal inflammation, as shown by the micro-CT and histological data, respectively. Altogether, these findings suggested that the thermoresponsive PF127 hydrogel is an effective local drug delivery system for better clinical management of periodontitis and associated pathologies.

Preparation, Physicochemical Characterisation and DoE Optimisation of a Spray-Dried Dry Emulsion Platform for Delivery of a Poorly Soluble Drug, Simvastatin

In the presented study, insight into the development and optimisation of the dry emulsion formulation and spray drying process is provided. The aim was to facilitate the dissolution of the poorly soluble, highly lipophilic drug, simvastatin, by forming spray-dried dry emulsion particles having adequate powder flow properties, while assuring sufficient drug content. Simvastatin and a mixture of caprylic, capric triglyceride and 1-oleoyl-rac-glycerol were employed as a model drug and solubilising oils, respectively. A matrix of the dry emulsions was composed at a fixed ratio mixture of mannitol and HPMC. Tween 20 was used in low amounts as the primary emulsion stabiliser. To facilitate process optimisation, a DoE surface response design was used to study the influence of formulation and process parameters on the particle size distribution, powder bulk properties, emulsion reconstitution ability, drug stability and process yield of spray-dried products. Two-fluid nozzle geometry was identified, studied and confirmed to be important for most product critical quality attributes. Models obtained after the study showed acceptable coefficients of determination and provided good insight in the relationship governing the process and product characteristics. Five model optimised products showed adequate process yield, suitable particle size distribution, good reconstitution ability and improved dissolution profile, when compared to a non-lipid-based tablet and the pure drug. However, the obtained dry emulsion powders exhibited poor flow character according to the Carr index. The optimised product was further analysed with NMR during lipolysis to gain insight into the species formed during digestion and the kinetics of their formation.

Rosuvastatin Prevents the Exacerbation of Atherosclerosis in Ligature-Induced Periodontal Disease Mouse Model

Periodontitis is a local and systemic inflammatory condition and a risk factor of atherosclerosis, but no studies investigated the effect of a statin on atherogenesis affected by severe periodontitis. In this study, we investigated the effect of rosuvastatin (RSV) on atherogenesis in Apolipoprotein E-deficient mice receiving silk ligature placement around the maxillary second molars. Mice with the ligature placement developed severe periodontitis and vascular inflammation. RSV significantly inhibited the development of periodontitis and vascular inflammation and remarkably blocked the increased lipid deposition and the atherogenic gene expression in the arterial wall and aortic sinus induced by severe periodontitis. To understand the mechanistic effect of RSV on periodontitis-associated atherogenesis, we investigated the in vitro effect of RSV on various effect of TNF-α, a major proinflammatory cytokine for periodontitis and atherogenesis. We found that RSV notably inhibited the TNF-α-induced osteoclast formation, endothelial cell phenotypic changes, foam cell formation, and the expression of CD47 and other oncogenes in arterial smooth muscle cells. Taken together, our study indicates that RSV prevents the exacerbation of atherosclerosis induced periodontitis by inhibiting local, systemic and vascular inflammation, as well as the expression of CD47 from arterial smooth muscle cells in mice.

Contribution of Statins towards Periodontal Treatment: A Review

The pleiotropic effects of statins have been evaluated to assess their potential benefit in the treatment of various inflammatory and immune-mediated diseases including periodontitis. Herein, the adjunctive use of statins in periodontal therapy in vitro, in vivo, and in clinical trials was reviewed. Statins act through several pathways to modulate inflammation, immune response, bone metabolism, and bacterial clearance. They control periodontal inflammation through inhibition of proinflammatory cytokines and promotion of anti-inflammatory and/or proresolution molecule release, mainly, through the ERK, MAPK, PI3-Akt, and NF-κB pathways. Moreover, they are able to modulate the host response activated by bacterial challenge, to prevent inflammation-mediated bone resorption and to promote bone formation. Furthermore, they reduce bacterial growth, disrupt bacterial membrane stability, and increase bacterial clearance, thus averting the exacerbation of infection. Local statin delivery as adjunct to both nonsurgical and surgical periodontal therapies results in better periodontal treatment outcomes compared to systemic delivery. Moreover, combination of statin therapy with other regenerative agents improves periodontal healing response. Therefore, statins could be proposed as a potential adjuvant to periodontal therapy. However, optimization of the combination of their dose, type, and carrier could be instrumental in achieving the best treatment response.

Identification of Genes Differentially Expressed in Simvastatin-Induced Alveolar Bone Formation

Local delivery of simvastatin (SIM) has exhibited potential in preventing inflammation and limiting bone loss associated with experimental periodontitis. The primary aim of this study was to analyze transcriptome changes that may contribute to SIM's reduction of periodontal inflammation and bone loss. We evaluate the global genetic profile and signaling mechanisms induced by SIM on experimental periodontitis bone loss and inflammation. Twenty mature female Sprague Dawley rats were subjected to ligature-induced experimental periodontitis around maxillary second molars (M2) either unilaterally (one side untreated, n = 10) or bilaterally (n = 10). After the ligature removal at day 7, sites were injected with either carrier, pyrophosphate (PPi ×3), 1.5-mg SIM-dose equivalent SIM-pyrophosphate prodrug, or no injection. Three days after ligature removal, animals were euthanized; the M1-M2 interproximal was evaluated with μCT, histology, and protein expression. M2 palatal gingiva was harvested for RNA sequencing. Although ligature alone caused upregulation of proinflammatory and bone catabolic genes and proteins, seen in human periodontitis, SIM-PPi upregulated anti-inflammatory (IL-10, IL-1 receptor-like 1) and bone anabolic (insulin-like growth factor, osteocrin, fibroblast growth factor, and Wnt/ β-catenin) genes. The PPi carrier alone did not have these effects. Genetic profile and signaling mechanism data may help identify enhanced pharmacotherapeutic approaches to limit or regenerate periodontitis bone loss. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.