Neuroprotection of microglial conditioned medium on 6-hydroxydopamine-induced neuronal death: role of transforming growth factor beta-2.
Microglia, the immune cells of the CNS, play essential roles in both physiological and pathological brain states. Here we have used an in vitro model to demonstrate neuroprotection of a 48 h-microglial conditioned medium (MCM) towards cerebellar granule neurons (CGNs) challenged with the neurotoxin 6-hydroxydopamine, which induces a Parkinson-like neurodegeneration, and to identify the protective factor(s). MCM nearly completely protects CGNs from 6-hydroxydopamine neurotoxicity and at least some of the protective factor(s) are peptidic in nature. While the fraction of the medium containing molecules < 30 kDa completely protects CGNs, fractions containing molecules < 10 kDa or > 10 kDa are not neuroprotective. We further demonstrate that microglia release high amounts of transforming growth factor-beta2 (TGF-beta2) and that its exogenous addition to the fraction of the medium not containing it (< 10 kDa) fully restores the neuroprotective action. Moreover, MCM neuroprotection is significantly counteracted by an inhibitor of TGF-beta2 transduction pathway. Our results identify TGF-beta2 as an essential neuroprotective factor released by microglia in its culture medium that requires to be fully effective the concomitant presence of other factor(s) of low molecular weight.
Polazzi
Elisabetta
E
Department of Biology, University of Bologna, Italy.
Altamira
Luis Emiliano Peña
LE
Eleuteri
Simona
S
Barbaro
Raffaella
R
Casadio
Chiara
C
Contestabile
Antonio
A
Monti
Barbara
B
D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D017628:Microglia / Q000502:physiology*; D008970:Molecular Weight; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016627:Oxidopamine / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D053781:Transforming Growth Factor beta2 / Q000502:physiology*
D017077:Culture Media, Conditioned; D018696:Neuroprotective Agents; D053781:Transforming Growth Factor beta2; D016627:Oxidopamine