The pro-inflammatory and calcification effects of DMP-1 on pulp fibroblasts. Implications for the prevention of dental pulp calcifc metamorphosis

  • Author / Creator
    Abd-Elmeguid, Ashraf A.E.
  • Traumatic dental injuries are very common in the first and second decades of life. Trauma, if severe, could result in irreversible changes such as root resorption and/or partial or complete pulp obliteration by hard tissue. Dental pulp calcific metamorphosis is the rapid calcification of the pulp soft tissue in response to trauma. It is characterised by the deposition of dentin-like and bone-like tissues inside the dental pulp. Total avulsion of teeth represents almost 16% of dental traumatic injuries where the replantation of teeth back into their socket is the first treatment of choice. Inflammatory cells and osteoclasts were reported in teeth replantation cases, highlighting the role of inflammation in this type of calcification. Accordingly, the hypothesis of the current research was that dental pulp calcification and inflammation are closely integrated mechanisms. The immuno-histochemical localisation of a calcification molecule, dentin matrix protein (DMP-1), in pulp inflammation was performed. This was followed by determining its possible role in mediating inflammation by testing its induction of interleukin-6 (IL-6) and IL-8 expression in pulp fibroblasts. This proinflammatory effect is enhanced using lipopolysaccharide (LPS). The inhibitor of p38 mitogen activated protein kinase (p38MAPK) (SB-203580) blocked this effect. Osteopontin (OPN) and osteocalcin (OCN) were also examined for their expression in pulp inflammation using western blot and immuno-histochemistry respectively. Vascular endothelial growth factor (VEGF) increased in response to OPN stimulation of pulp cells. DMP-1 induced the expression of OPN, OCN, alkaline phosphatase (AP) and VEGF. p38MAPK inhibitor decreased DMP-1- induced OPN, AP and VEGF to their normal expression. Recombinant human DMP-1 showed marked calcification of ferret dental pulp chambers and DMP-1 was localised at 2 and 6 weeks following the replantation of ferret premolars. In vivo blocking of the inflammatory effect of DMP-1 using p38MAPK inhibitor significantly decreased calcification inside the dental pulp at 2 and 6 weeks post replantation. It is concluded that the DMP-1 is involved in the development of calcific metamorphosis partly through its pro inflammatory effect. DMP-1 also promoted pulp cells proliferation, pro-inflammation, and angiogenesis. Our data demonstrate a novel therapeutic strategy by which dental pulp inflammation and calcification are prevented at the same time.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Medical Sciences-Dentistry
  • Supervisor / co-supervisor and their department(s)
    • Yu, Donald (Dentistry). Moqbel, Redwan (Pulmonary Medicine UofA, Immunology Uof Mannitoba)
  • Examining committee members and their departments
    • Huang, George (Endodontics, Boston Unversity)
    • Kline, Loren (Dentistry)
    • Eggert, Michael (Dentistry)
    • Vliagoftis, Harissios (Pulmonary Medicine)
    • Lacy, Paige (Pulmonary Medicine)