title: Neuronal TGF-beta1 mediates IL-9/mast cell interaction and exacerbates excitotoxicity in newborn mice.
abstract: Intraneocortical injection of ibotenate, a glutamate analog, in newborn mice produces damage mimicking lesions observed in human infants with cerebral palsy. Previous research using this model has demonstrated that pretreatment with IL-9, a Th2 cytokine, significantly exacerbated excitotoxic brain lesions. The goal of this study is to identify the underlying pathophysiological mechanism of lesion formation. Pretreatment with TGF-beta1 produced the same effects as IL-9 on ibotenate-induced lesions. IL-9 effects were abolished when a specific TGF-beta1 neutralizing antibody is administered at the same time. Real-time PCR, Western blot, and immunohistochemistry showed that pretreatment with IL-9 increased TGF-beta1 neocortical expression. In vitro studies using real-time PCR and immunocytochemistry demonstrated that neurons were a major contributor in IL-9-induced increase of TGF-beta1. In c-Kit mast cell-deficient mice, TGF-beta1 failed to exacerbate excitotoxic brain lesions, suggesting a key role of mast cells in TGF-beta1 effects. A specific inhibitor of mast cell degranulation and histamine receptor blockers abrogated TGF-beta1 effects on excitotoxic lesions, providing further evidence of mast cell involvement and the role of mast cell-derived histamine. Finally, in vitro studies using a mast cell line showed that TGF-beta1 increased histamine in the supernatant. In aggregate, these data support the notion that neuronal TGF-beta1 plays a key role in the IL-9/mast cell interaction, which leads to an exacerbation of neonatal excitotoxic damage through an increased extracellular histamine concentration. The identification of this pathway, if confirmed in human neonates, might have important implications for understanding and preventing cerebral palsy.
authors.affiliation: INSERM E 9935 and Service de Neurologie Pédiatrique, Hôpital Robert Debré, 75019 Paris, France.
authors.forename: Bettina
authors.initials: B
authors.lastname: Mesplès
authors.forename: Romain H
authors.initials: RH
authors.lastname: Fontaine
authors.forename: Vincent
authors.initials: V
authors.lastname: Lelièvre
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Launay
authors.forename: Pierre
authors.initials: P
authors.lastname: Gressens
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D002547:Cerebral Palsy / Q000276:immunology* / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D005260:Female; D006632:Histamine / Q000378:metabolism; D006633:Histamine Antagonists / Q000494:pharmacology; D016906:Interleukin-9 / Q000276:immunology / Q000633:toxicity*; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009410:Nerve Degeneration / Q000139:chemically induced / Q000276:immunology* / Q000378:metabolism; D009474:Neurons / Q000276:immunology / Q000378:metabolism; D009498:Neurotoxins / Q000276:immunology / Q000378:metabolism; D011968:Receptors, Histamine / Q000187:drug effects / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D053773:Transforming Growth Factor beta1
chemical_list: D000906:Antibodies; D006633:Histamine Antagonists; D016906:Interleukin-9; D009498:Neurotoxins; D011968:Receptors, Histamine; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D006632:Histamine