Inflammatory events in hippocampal slice cultures prime neuronal susceptibility to excitotoxic injury: a crucial role of P2X7 receptor-mediated IL-1beta release.
We investigated the consequences of transient application of specific stimuli mimicking inflammation to hippocampal tissue on microglia activation and neuronal cell vulnerability to a subsequent excitotoxic insult. Two-week-old organotypic hippocampal slice cultures, from 7-day-old C57BL/6 donor mice, were exposed for 3 h to lipopolysaccharide (LPS; 10 ng/mL) followed by 3 h co-incubation with 1 mM ATP, or 100 microM 2'3'-O-(4-benzoyl-benzoyl) adenosine 5'-triphosphate triethylammonium, a selective P2X(7) receptor agonist. These treatments in combination, but not individually, induced a pronounced activation and apoptotic-like death of macrophage antigen-1 (MAC-1)-positive microglia associated with a massive release of interleukin (IL)-1beta exceeding that induced by LPS alone. Antagonists of P2X(7) receptors prevented these effects. Transient pre-exposure of slice cultures to a combination of LPS and P2X(7) receptor agonists, but not either one or the other alone, significantly exacerbated CA3 pyramidal cell loss induced by subsequent 12 h exposure to 8 microM alpha-amino-3-hydroxy-5-methyl-4-isoxazole propinate (AMPA). Potentiation of AMPA toxicity was prevented when IL-1beta production or its receptor signaling were blocked by an inhibitor of interleukin-converting-enzyme or IL-1 receptor antagonist during application of LPS + ATP. The same treatments did not prevent microglia apoptosis-like death. These findings show that transient exposure to specific pro-inflammatory stimuli in brain tissue can prime neuronal susceptibility to a subsequent excitotoxic insult. P2X(7) receptor stimulation, and the consequent IL-1beta release, is mandatory for exacerbation of neuronal loss. These mechanisms may contribute to determine cell death/survival in acute and chronic neurodegenerative conditions associated with inflammatory events.
Bernardino
Liliana
L
Department of Neuroscience, Mario Negri Institute for Pharmacological Research, Milan, Italy.
Balosso
Silvia
S
Ravizza
Teresa
T
Marchi
Nicola
N
Ku
George
G
Randle
John C
JC
Malva
João O
JO
Vezzani
Annamaria
A
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D004357:Drug Synergism; D004660:Encephalitis / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D053590:Interleukin 1 Receptor Antagonist Protein / Q000494:pharmacology; D053583:Interleukin-1beta / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000378:metabolism; D009410:Nerve Degeneration / Q000139:chemically induced / Q000276:immunology / Q000378:metabolism*; D009498:Neurotoxins / Q000633:toxicity*; D009924:Organ Culture Techniques; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7
D018690:Excitatory Amino Acid Agonists; D053590:Interleukin 1 Receptor Antagonist Protein; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D009498:Neurotoxins; C546469:P2rx7 protein, mouse; D017472:Receptors, Interleukin-1; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate