Artikel
Glioma associated microglial MMP9 expression is upregulated by TLR2 receptor activation and sensitive to minocycline
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Autoren
Veröffentlicht: | 13. Mai 2014 |
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Gliederung
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Objective: Analysis of MMP-9 regulation by microglial TLRs in mouse and human glioma samples and the role of the MAPK blocker minocycline in inhibition of GAMs.
Method: We determined MMP-9 regulation by RT-PCR, qPCR, westernblotting (WB), gelatinase zymography in a microglia WT, in MyD88 knockout and in different TLR knockout mouse cultures (TRL KO 1, 2, 4, 6, 7, 9) and in human samples. We sorted human microglia/macrophages from fresh human GBM samples by magnetic sorting for CD11b+ cells and analyzed these samples after minocycline treatment. Finally we performed a survival study using glioma implanted mice treated with minocycline or control.
Results: MMP-9 is predominantly expressed by GAMs in mouse and human glioma tissue but not by glioma cells. Supernatant from glioma cells induced the expression of MMP-9 in cultured microglial cells. Using mice deficient for toll-like receptors 1, 2, 4, 6, 7 and 9 we identified TLR2/6 as a responsible signalling pathway for glioma-induced upregulation of microglial MMP-9. In addition, TLR2 deficiency attenuated the upregulation of microglial MMP-9 in the mouse experimental glioma model. Moreover, glioma supernatant triggered an upregulation of TLR2 in microglia. Both, the upregulation of MMP-9 and TLR2 was attenuated by the antibiotic minocycline and a p38 MAPK antagonist. Minocycline also extended the survival rate of glioma bearing mice when added to the drinking water.
Conclusions: Glioma cells change the phenotype of glioma associated microglia/macrophages in a complex fashion in humans and mice using TLR2 as an important signalling pathway to induce MMP-9 expression in GAMs. Furthermore, minocycline proves to be a potential candidate for adjuvant glioma therapy.