Apolipoprotein E modulates the CNS response to injury
Publication
, Journal Article
Laskowitz, DT; Lynch, JR; Warner, DS; Pineda, J
Published in: Journal of Neurochemistry
Apolipoprotein E (apoE) plays an important role in recovery from acute brain injury. One potential mechanism for this is that apoE down‐regulates glial activation and subsequent secretion of inflammatory mediators. Following a pneumatic impact to the closed skull of anesthetized apoE deficient and wildtype mice, MRI was performed to quantify the effacement of the lateral ventricles as a radiographic surrogate for cerebral edema. At 24 hours following injury, apoE deficient animals had a greater degree of cerebral edema as compared to matched controls. This increase in edema was associated with enhanced up‐regulation of TNFα, a pro‐inflammatory cytokine believed to play an important role in mediating blood–brain barrier breakdown and the development of cerebral edema. We have previously demonstrated that a peptide derived from the receptor binding region of apoE retained the anti‐inflammatory activities of the holoprotein , and we next investigated whether a single intravenous administration of this apoE‐mimetic peptide could exert neuroprotective effects. Thirty minutes after closed head injury, mice were randomized to receive low dose peptide (203 mg/kg); high dose peptide (406 mg/kg), or vehicle. At 24 h post injury, the saline injected animals had a profound deficit in rotorod testing which was associated with weight loss. A single intravenous injection of apoE‐mimetic peptide 30 min following closed head injury protected against motor deficit, weight loss, and neurocognitive deficit in a dose dependent fashion. This suggests that apoE may modify prognosis in brain injury by down‐regulating the CNS inflammatory response, and that mimicking the biological activity of apoE may lead to novel therapeutic strategies in the setting.