ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2006) 12 P45

Oxidative stress induced by TNF-alpha and glucose in an osteoblastic model and therapeutic implications of minocycline

M Soory1 & A Tilakaratne2


1King’s College London Dental Institute, London, United Kingdom; 2Faculty of Dental Science, University of Peradeniya, Peradeniya, Sri Lanka.


Objective

This study investigates the oxidative effects of tumour necrosis factor alpha (TNF) and glucose (G) in a cell culture model of osteoblasts and the modifying role of minocycline (M), using a steroid marker of wound healing (5 alpha- dihydrotestosterone: DHT). This model simulates chronic inflammation and hyperglycaemia, relevant to chronic inflammatory periodontal disease in uncontrolled diabetics and prospects of adjunctive management, using minocycline.

Method

Monolayer cultures of MG63 human osteoblasts were established in Eagle’s MEM in multiwell plates. They were incubated with 14C- testosterone in the presence or absence of optimal concentrations of TNF20 ng, G1000, M25 micrograms/ml, alone and in combination for 24 h in a humidified tissue culture incubator. The medium was then eluted, solvent extracted for formed metabolites and separated by thin layer chromatography in a benzene acetone solvent system 4:1 v/v. The metabolites were then quantified using a radioisotope scanner.

Results

The metabolites formed were diols, DHT and 4-androstenedione. There were 63% reductions in the yields of DHT in response to TNF and G alone, while M stimulated yields by 71% compared with controls (n=8; P<0.0001). The combination of TNF+G resulted in 27% less DHT than either alone. When M was added to this combination, there was a 3-fold increase in the yield of DHT, over TNF+G (n=8; P<0.0001). Yields of 4-androstenedione were inversely proportional to those of DHT, less so with the combination of TNF+G. The yields of diols were significantly decreased in response to agents compared with controls, again less so with the combination TNF+G.

Conclusion

TNF and G induced oxidative responses in cultured osteoblasts which were overcome by minocycline in this hyperglycaemic model. This can be extrapolated to the ‘in vivo’ situation, reinforcing therapeutic efficacy of minocycline for adjunctive management of uncontrolled periodontal disease in diabetic patients, in keeping with previously reported antioxidant properties of minocycline.

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