Prof. Hermona Soreq

Molecular Mechanisms Regulating LPS-Induced Inflammation in the Brain

Lykhmus, O, Mishra N, Koval L, Kalashnyk O, Gergalova G, Uspenska K, Komisarenko S, Soreq H, Skok M.  2016.  

Abstract:

Neuro-inflammation, one of the pathogenic causes of neurodegenerative diseases, is regulated through the cholinergic anti-inflammatory pathway via the alpha7 nicotinic acetylcholine receptor (alpha7 nAChR). We previously showed that either bacterial lipopolysaccharide (LPS) or immunization with the alpha7(1-208) nAChR fragment decrease alpha7 nAChRs density in the mouse brain, exacerbating chronic inflammation, beta-amyloid accumulation and episodic memory decline, which mimic the early stages of Alzheimer's disease (AD). To study the molecular mechanisms underlying the LPS and antibody effects in the brain, we employed an in vivo model of acute LPS-induced inflammation and an in vitro model of cultured glioblastoma U373 cells. Here, we report that LPS challenge decreased the levels of alpha7 nAChR RNA and protein and of acetylcholinesterase (AChE) RNA and activity in distinct mouse brain regions, sensitized brain mitochondria to the apoptogenic effect of Ca(2+) and modified brain microRNA profiles, including the cholinergic-regulatory CholinomiRs-132/212, in favor of anti-inflammatory and pro-apoptotic ones. Adding alpha7(1-208)-specific antibodies to the LPS challenge prevented elevation of both the anti-inflammatory and pro-apoptotic miRNAs while supporting the resistance of brain mitochondria to Ca(2+) and maintaining alpha7 nAChR/AChE decreases. In U373 cells, alpha7-specific antibodies and LPS both stimulated interleukin-6 production through the p38/Src-dependent pathway. Our findings demonstrate that acute LPS-induced inflammation induces the cholinergic anti-inflammatory pathway in the brain, that alpha7 nAChR down-regulation limits this pathway, and that alpha7-specific antibodies aggravate neuroinflammation by inducing the pro-inflammatory interleukin-6 and dampening anti-inflammatory miRNAs; however, these antibodies may protect brain mitochondria and decrease the levels of pro-apoptotic miRNAs, preventing LPS-induced neurodegeneration.

Journal:

Front Mol Neurosci

Volume:

9

Pagination:

19