Research
Effect of anti-inflammatory agents on transforming growth factor beta over-expressing mouse brains: a model revised
1 Laboratoire de Recherches Cérébrovasculaires, CNRS FRE 2363, Paris, France
2 Génétique des Maladies Cérébrovasculaires, INSERM E365, Paris, France
3 Center for Dementia Research, Nathan Kline Institute, New York University School of Medicine, Orangeburg, New York, U.S.A
4 Neurologie Expérimentale et Thérapeutique, INSERM U289, Hôpital de la Pitié-Salpêtrière, Paris, France
5 Department of Neurology, University of Bonn, Germany
6 Department of Neurosciences, Alzheimer Research Laboratory, Case Western Reserve University, School of Medicine, Cleveland, Ohio, U.S.A
7 Department of Anesthesiology, College of Medicine, University of Illinois at Chicago, U.S.A
Journal of Neuroinflammation 2004, 1:11 doi:10.1186/1742-2094-1-11
Published: 2 July 2004Abstract
Background
The over-expression of transforming growth factor β-1(TGF-β1) has been reported to cause hydrocephalus, glia activation, and vascular amyloidβ (Aβ) deposition in mouse brains. Since these phenomena partially mimic the cerebral amyloid angiopathy (CAA) concomitant to Alzheimer's disease, the findings in TGF-β1 over-expressing mice prompted the hypothesis that CAA could be caused or enhanced by the abnormal production of TGF-β1. This idea was in accordance with the view that chronic inflammation contributes to Alzheimer's disease, and drew attention to the therapeutic potential of anti-inflammatory drugs for the treatment of Aβ-elicited CAA. We thus studied the effect of anti-inflammatory drug administration in TGF-β1-induced pathology.
Methods
Two-month-old TGF-β1 mice and littermate controls were orally administered pioglitazone, a peroxisome proliferator-activated receptor-γ agonist, or ibuprofen, a non steroidal anti-inflammatory agent, for two months. Glia activation was assessed by immunohistochemistry and western blot analysis; Aβ precursor protein (APP) by western blot analysis; Aβ deposition by immunohistochemistry, thioflavin-S staining and ELISA; and hydrocephalus by measurements of ventricle size on autoradiographies of brain sections. Results are expressed as means ± SD. Data comparisons were carried with the Student's T test when two groups were compared, or ANOVA analysis when more than three groups were analyzed.
Results
Animals displayed glia activation, hydrocephalus and a robust thioflavin-S-positive vascular deposition. Unexpectedly, these deposits contained no Aβ or serum amyloid P component, a common constituent of amyloid deposits. The thioflavin-S-positive material thus remains to be identified. Pioglitazone decreased glia activation and basal levels of Aβ42- with no change in APP contents – while it increased hydrocephalus, and had no effect on the thioflavin-S deposits. Ibuprofen mimicked the reduction of glia activation caused by pioglitazone and the lack of effect on the thioflavin-S-labeled deposits.
Conclusions
i) TGF-β1 over-expressing mice may not be an appropriate model of Aβ-elicited CAA; and ii) pioglitazone has paradoxical effects on TGF-β1-induced pathology suggesting that anti-inflammatory therapy may reduce the damage resulting from active glia, but not from vascular alterations or hydrocephalus. Identification of the thioflavin-S-positive material will facilitate the full appraisal of the clinical implication of the effects of anti-inflammatory drugs, and provide a more thorough understanding of TGF-β1 actions in brain.
