title: Nitric oxide-mediated cytotoxic effect induced by zoledronic acid treatment on human gingival fibroblasts.
abstract: OBJECTIVE
  The aim of our work was to evaluate the role of nitric oxide (NO) in the in vitro response of human gingival fibroblasts (HGFs) to 1, 5, 10, and 100 μM doses of zoledronic acid (ZA), a bisphosphonate largely used in the clinical practice and for which several adverse effects are reported.
  
  
  METHODS
  Phase contrast microscopy and live/dead staining were used to evaluate HGFs morphology; cell viability, collagen type I and interleukin 6 (IL-6) secretion were evaluated by 3-[4,5-dimethyl-thiazol-2-yl-]-2,5-diphenyl tetrazolium bromide (MTT) and enzyme-linked immunosorbent assay (ELISA) assays. Reactive oxygen species (ROS) production and mitochondrial membrane potential were evaluated by flow cytometry; NO production and NOS activity by spectrophotometric analysis; endothelial NOS (eNOS) and neuronal NOS (nNOS) expression by immunofluorescence.
  
  
  RESULTS
  Viable fibroblasts are evidenced in control sample while floating dead cells and cells close to detachment phase in ZA-treated sample, in agreement with decreased level of collagen type I. Control sample shows higher number of viable cells respect to ZA-treated one and ROS production increases when ZA is added. Released NO in ZA-treated sample appears higher and NO overproduction is related to increased nNOS activity. IL-6 secretion level is higher in ZA-treated sample than in control one.
  
  
  CONCLUSIONS
  Our results suggest ROS involvement in NO overproduction, due to nNOS recruitment, both at low and high doses. In turn, NO release seems to be able to trigger the inflammatory response only when high doses are administered, thus confirming the ZA cytotoxic effect on HGFs.
  
  
  CONCLUSIONS
  The knowledge of ZA-mediated cytotoxicity mechanisms on HGFs allows to better understand drug pharmacological activity.
authors.affiliation: Section of Human Anatomy, Department of Pharmacy, University "G. d'Annunzio", Chieti Pescara, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: De Colli
authors.forename: Susi
authors.initials: S
authors.lastname: Zara
authors.forename: Viviana
authors.initials: V
authors.lastname: di Giacomo
authors.forename: Antonia
authors.initials: A
authors.lastname: Patruno
authors.forename: Guya Diletta
authors.initials: GD
authors.lastname: Marconi
authors.forename: Marialucia
authors.initials: M
authors.lastname: Gallorini
authors.forename: Vincenzo Luca
authors.initials: VL
authors.lastname: Zizzari
authors.forename: Giulia
authors.initials: G
authors.lastname: Tetè
authors.forename: Amelia
authors.initials: A
authors.lastname: Cataldi
mesh_terms: D000328:Adult; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D024042:Collagen Type I / Q000378:metabolism; D004164:Diphosphonates / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000187:drug effects*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005881:Gingiva / Q000166:cytology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D015850:Interleukin-6 / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology*; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D004164:Diphosphonates; D007093:Imidazoles; D015850:Interleukin-6; D009569:Nitric Oxide; D000077211:Zoledronic Acid