Cold pre-conditioning neuroprotection depends on TNF-α and is enhanced by blockade of interleukin-11.
Cold pre-conditioning reduces subsequent brain injury in small animals but the underlying mechanisms remain undefined. As hypothermia triggers systemic macrophage tumor necrosis factor alpha (TNF-α) production and other neural pre-conditioning stimuli depend on this cytokine, we reasoned that microglia and TNF-α would be similarly involved with cold pre-conditioning neuroprotection. Also, as slice cultures closely approximate their in vivo counterpart and include quiescent microglia, we used rat hippocampal slice cultures to confirm this hypothesis. Furthermore, inflammatory cytokine gene screening with subsequent PCR and immunostaining confirmation of targeted mRNA and related protein changes showed that cold pre-conditioning triggered a significant rise in TNF-α that localized to microglia and a significant rise in interleukin (IL)-11 that localized mainly to hippocampal pyramidal neurons and, more rarely, astrocytes. Importantly, co-stimulation with cold and IL-11, an anti-inflammatory cytokine that inhibits TNF-α expression, abrogated the otherwise evident protection. Instead, cold pre-conditioning coupled with blockade of IL-11 signaling further enhanced neuroprotection from that seen with cold pre-conditioning alone. Thus, physiological activation of brain pro-inflammatory cytokine signaling, and its amplification by inhibition of coincident anti-inflammatory cytokine signaling, may be opportune targets for the development of novel therapeutics that can mimic the protection seen in cold pre-conditioning.
Department of Neurology, The University of Chicago Medical Center, Chicago, Illinois 60637, USA.
Heidi M
HM
Mitchell
David M
DM
White
Miriam S
MS
Domowicz
Richard P
RP
Kraig
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D056547:CA1 Region, Hippocampal / Q000166:cytology; D003080:Cold Temperature; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D016207:Cytokines / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D005786:Gene Expression Regulation / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D017370:Interleukin-11 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D016202:N-Methylaspartate / Q000633:toxicity; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018696:Neuroprotective Agents / Q000494:pharmacology; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013696:Temperature; D013997:Time Factors; D046509:Tissue Culture Techniques; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
D000906:Antibodies; D016895:Culture Media, Serum-Free; D016207:Cytokines; D018690:Excitatory Amino Acid Agonists; D005904:Glial Fibrillary Acidic Protein; D017370:Interleukin-11; D018696:Neuroprotective Agents; D012333:RNA, Messenger; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D016202:N-Methylaspartate; D010751:Phosphopyruvate Hydratase