In vivo effects of geranylgeraniol on the development of bisphosphonate-related osteonecrosis of the jaws

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Abstract

Background

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a complication of the bisphosphonate (BP) treatment and its pathopysiology is still not fully understood. The existing preventive and treatment options require updates and more attention. Geranylgeraniol (GGOH) so far demonstrated an increased activity and viability of the cells previously treated with zoledronic acid (ZA). The aim of this study was to evaluate the in vivo effects of GGOH on the development of BRONJ.

Materials and methods

A total of 30 male Wistar rats were included in the study, divided into three groups: two experimental groups (EG1 and EG2) and a control group (CG). Rats from EG1 and EG2 were treated with 0,06 mg/kg ZA ip weekly in a duration of five weeks, while CG received saline ip. On the third week all animals underwent extraction of the lower right first molars. The rats from EG2 received a local solution of GGOH in concentration of 5 mM in the socket every day after the tooth extraction. The analyses included clinical evaluation on the wound healing and pathohistological evaluation for presence and level of osteonecrosis.

Results

EG2 showed significantly improved wound healing and tissue proliferation, when compared to EG1. EG2 significantly differed from EG1 and CG (p<0,05) for the presence of microscopical osteonecrosis (80% vs 22,2% vs 0%). Regarding to the number of empty lacunes without osteocytes and the level of necrosis, all groups demonstrated significant differences.

Conclusion

Geranylgeraniol in a form of local solution may be a promising option for prevention and treatment of BRONJ.

Introduction

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) as a complication of bisphosphonate (BP) treatment is an area of increased research interest. Although several hypotheses have been proposed (Ruggiero et al., 2014), none of them fully explain the nature and mechanism of development of the disease. However, the theory that supports the inhibition of bone resorption with mediation of osteoclastic activity is the most well researched. On the other hand, studies showed that the BPs have toxic effects on soft tissue cells, as well (Landesberg et al., 2008, Scheper et al., 2009, Walter et al., 2010, Ravosa et al., 2011, Tipton et al., 2011, Açil et al., 2012, Basso et al., 2013, Tanaka et al., 2013), indicating that the impaired wound healing and infection may play an important role in the development of BRONJ.

BRONJ has been successfully reproduced mainly in animal models, primarily rats, implementing different routes of administration, dosage of BPs and risk factors (Sonis et al., 2009, Bi et al., 2010, Aghaloo et al., 2011, Barba-Recreo et al., 2014, Jang et al., 2015, Zandi et al., 2016). Large-animal models have been introduced, as well (Allen and Burr, 2008, Allen et al., 2010; Pautke et al., 2012). Dentoalveolar trauma, i.e. tooth extraction, is one of the main factors contributing to the development of BRONJ (Ruggiero et al., 2014). A recent study showed that isolated soft tissue trauma without bone damage can also be the starting point for BRONJ (Zandi et al., 2017). Changes in pH due to infection and tooth-associated diseases have been shown that may play an important role in the developing of the disease, as well (Otto et al., 2010a, Otto et al., 2010b, Dayisoylu et al., 2014).

BPs are therapeutic agents used for treatment of several diseases and conditions that affect the bones and bone metabolism (Holen and Coleman, 2010, Major et al., 2001).

The non−nitrogen-containing BPs interfere with osteoclastic activity by producing ATP analogues (Frith et al., 1997, Roelofs et al., 2006); the nitrogen-containing BPs, which today are much more commonly used than the non−nitrogen-containing BPs, target the key enzymes in the mevalonic pathway. The nitrogen-containing BPs inhibit the farnesyl pyrophosphate (FPP) synthase and geranylgeranyl pyrophosphate (GGPP) synthase (Luckman et al., 1998). This results in impaired prenylation of the proteins and impaired activity of small GTPs Ras, Rho, Rac and Cdc42, which are critical in regulation of the cell morphology, maintenance of the cell membrane structure, cell function and survival. These dysfunctional cells alter the bone metabolism and are responsible for creating the conditions for development of BRONJ. The clinical presentation of the disease includes exposed bone or a fistula that probes to the bone in a duration no shorter than 8 weeks in patients who receive antiresorptive medications, without a history of radiation therapy (Ruggiero et al., 2014). The condition may include pain, inflammation, swelling, infection, pathologic fractures and extension of the process in the adjacent structures. Several preventive and therapeutic protocols for treatment of BRONJ have been proposed, but both therapeutic approaches─the conservative one, which recommends the use of mouth antiseptic rinses and antibiotic regimens, and the surgical one, which includes resection and reconstruction─aim to prevent infection and inflammation and to decrease the stage of the disease. So far, none of these protocols has targeted the key point in the molecular pathway where BPs act.

Geranylgeraniol (GGOH) is an isoprenoid that is converted to GGPP in the mevalonic pathway. The result of BPs action is inhibition of GGOH (Crick et al., 1997). Only a few studies in which GGOH was added to cells that were previously treated with zoledronic acid (ZA), a potent amino BP, have been performed. These cell cultures studies show a considerable level of reversal of the toxicity caused by the ZA after adding GGOH for different periods of time (Cozin et al., 2011; Ziebart et al., 2011, Pabst et al., 2015). So far, there is only one animal model that has evaluated the influence of GGOH on the developing of BRONJ, and it showed significant improvement in the tested parameters (Nagaoka et al., 2015).

The motives for this research were the lack of literature data and studies that support the positive effects of GGOH observed in the cell studies, and the possibility to find a more effective preventive measure against BRONJ.

The aim of this study is to evaluate the effects of GGOH on the soft and bone tissues involved in BRONJ, in a rat animal model.

Section snippets

Material and methods

Thirty male white laboratory Wistar rats, weighing 150–300 g and 4 months of age, were included in the study. The animal care and all the procedures were according to EU Directive for animal experiments. The study was approved by the Ethics Committees in the Faculty of Dental Medicine and Faculty of Natural Sciences and Mathematics in Skopje, Republic of Macedonia. The rats were carried from the accredited laboratory for work with experimental animals in the Institute of Biology, Faculty of

Results

All the rats tolerated the experiment well, except one, which died at the time of the surgery. The weight of the animals was maintained at the average level during the whole experiment.

Discussion

In order to evaluate the effects of GGOH on the development of BRONJ, a rat animal model was developed in the present study, similarly to previously published studies. The ZA was used because it is the most potent and mostly used intravenous BP, while at the same time it is associated with the highest risk of developing of BRONJ (Russell and Rogers, 1999, Ruggiero et al., 2014). The incidence of 80% of microscopically proven BRONJ in the rats in the group treated with ZA and subjected to tooth

Conclusion

In this study, the administration of local solution of GGOH improved wound healing and decreased the occurrence and level of bone necrosis in rats previously treated with ZA and tooth extraction. This study shows that GGOH in vivo reduces the influence of highly potent nitrogen-containing BPs on the soft and bone tissues. Therefore, GGOH may be considered as a promising option for prevention and treatment of BRONJ. Further research on the optimal conditions of the medication delivery is

Funding

The study was self-funded by the authors. No external funding or sponsorship was provided.

Conflicts of interest

The authors declare that they have no conflicts of interest in regard to this work.

References (40)

  • S. Otto et al.

    Osteonecrosis of the jaw: effect of bisphosphonate type, local concentration, and acidic milieu on the pathomechanism

    J Oral Maxillofac Surg

    (2010)
  • S. Otto et al.

    Bisphosphonate-related osteonecrosis of the jaw: is pH the missing part in the pathogenesis puzzle?

    J Oral Maxillofac Surg

    (2010)
  • A.M. Pabst et al.

    The influence of geranylgeraniol on human oral keratinocytes after bisphosphonate treatment: an in vitro study

    J Craniomaxillofac Surg

    (2015)
  • C. Pautke et al.

    Bisphosphonate related osteonecrosis of the jaw: a minipig large animal model

    Bone

    (2012)
  • M.J. Ravosa et al.

    Bisphosphonate effects on the behavior of oral epithelial cells and oral fibroblasts

    Arch Oral Biol

    (2011)
  • S.L. Ruggiero et al.

    American Association of Oral and Maxillofacial Surgeons position paper on medication-related osteonecrosis of the jaw─2014 update

    J Oral Maxillofac Surg

    (2014)
  • R.G. Russell et al.

    Bisphosphonates: from the laboratory to the clinic and back again

    Bone

    (1999)
  • S.T. Sonis et al.

    Bony changes in the jaws of rats treated with zoledronic acid and dexamethasone before dental extractions mimic bisphosphonate-related osteonecrosis in cancer patients

    Oral Oncol

    (2009)
  • Y. Tanaka et al.

    In vitro cytotoxicity of zoledronate (nitrogen-containing bisphosphonate: NBP) and/or etidronate (non-BP) in tumour cells and periodontal cells

    Arch Oral Biol

    (2013)
  • M. Zandi et al.

    The starting point for bisphosphonate-related osteonecrosis of the jaw: alveolar bone or oral mucosa? A randomized, controlled experimental study

    J Craniomaxillofac Surg

    (2017)
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    Majka Tereza 43, 1000, Skopje, Macedonia.

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