Anti-neutrophil antibody enhances the neuroprotective effects of G-CSF by decreasing number of neutrophils in hypoxic ischemic neonatal rat model

Abstract

Objectives Neonatal hypoxia ischemia (HI) is an injury that can lead to neurological impairments such as behavioral and learning disabilities. Granulocyte-colony stimulating factor (G-CSF) has been demonstrated to be neuroprotective in ischemic stroke however it has also been shown to induce neutrophilia, ultimately exacerbating neuronal injury. Our hypothesis is that coadministration of anti-neutrophil antibody (Ab) with G-CSF will decrease blood neutrophil counts thereby reducing infarct volume and improving neurological function post HI brain injury. Methods Rat pups were subjected to unilateral carotid artery ligation followed by 2.5h of hypoxia. Animals were randomly assigned to five groups: Sham (n=15), Vehicle (HI, n=15), HI with G-CSF treatment (n=15), HI with G-CSF+Ab treatment (n=15), and HI with Ab treatment (n=15). Ab (325μg/kg) was administered intraperitoneally while G-CSF (50μg/kg) was administered subcutaneously 1h post HI followed by daily injections for 3 consecutive days. Animals were euthanized at 96h post HI for blood neutrophil counts and brain infarct volume measurements as well as at 5 weeks for neurological function testing and brain weight measurements. Lung and spleen weights at both time points were further analyzed. Results The G-CSF treatment group showed tendencies to reduce infarct volume and improve neurological function while significantly increasing neutrophil counts. On the other hand, the G-CSF+Ab group significantly reduced infarct volume, improved neurological function and decreased neutrophil counts. The Ab alone group showed reversal of the neuroprotective effects of the G-CSF+Ab group. No significant differences were found in peripheral organ weights between groups. Conclusion Our data suggest that coadministration of G-CSF with Ab not only prevented brain atrophy but also significantly improved neurological function by decreasing blood neutrophil counts. Hence the neuroprotective effects of G-CSF may be further enhanced if neutrophilia is avoided.

Tetramethylpyrazine inhibits neutrophil activation following permanent cerebral ischemia in rats

“…Although the onset varies, the intracerebral neutrophil infiltration is found in all types of cerebral ischemic injury [8]. Accumulating evidence suggests this intracerebral neutrophil infiltration has potentially damaging pro-inflammatory consequences in cerebral ischemia and highlights a crucial role of neutrophils in the prevention and treatment of stroke [5,7,9,10]. A recent study also showed that neutrophils and neutrophil-derived iNOS contribute to ischemic brain injury [26].…”

“…The recruitment of neutrophils to brain parenchyma is found in ischemic brain injury [8]. The neutrophil-to-lymphocyte ratio is a prognostic marker in ischemic cerebrovascular diseases and the depletion or functional inhibition of neutrophils leads to decreased neuroinflammation and neuronal apoptosis in stroke subjects [5,7,9,10]. Despite the potential compromise of the bloodbrain barrier (BBB) in ischemic brain injury, this structure still remains a determinant barrier of therapeutic drug feasibility.…”

Brain-immune interactions in perinatal hypoxic-ischemic brain injury

“…In term infants with HIE, the significantly elevated number of peripheral neutrophils in the first 96 hours of life is associated with the poor neurodevelopmental outcomes (Morkos et al , 2007). A recent study suggests that the neuroprotective effects of granulocyte colony-stimulating factor (G-CSF) may be further enhanced if the peripheral neutrophils are depleted in a rat neonatal HI model (Doycheva et al , 2014). Hence, neutrophils contribute to the exacerbation of neonatal brain damage, even though they do not rapidly accumulate in the developing brain after hypoxia-ischemia.…”

“…However, it promotes the development of neutrophilic granulocytes and leads to neutrophilia, which may ultimately exacerbate neuronal injury. Doycheva et al have demonstrated that administration of anti-neutrophil antibody with GCSF after cerebral hypoxia-ischemia reduces the brain injury and significantly improves neurological function by decreasing blood neutrophil accumulation in a neonatal rat model (Doycheva et al , 2014). Thus, anti-neutrophil strategies would be more effective in neonatal rats when co-administration of anti-neutrophil antibody with other anti-inflammatory and/or antiapoptotic candidates, such as G-CSF.…”

Early applications of granulocyte colony-stimulating factor (G-CSF) can stabilize the blood-optic nerve barrier and further ameliorate optic nerve inflammation in a rat model of anterior ischemic optic neuropathy (rAION)

“…Ischemic-brain-injury models have demonstrated that G-CSF treatment can reduce neuroinflammation, neutrophil infiltration, infarct volume and blood–brain barrier (BBB) disruption (Lee et al, 2005; Doycheva et al, 2014; Li et al, 2015). Evidence from rAION models suggests that reducing inflammation and ON edema in the acute phase may be effective in protecting neurons from degeneration (Goldenberg-Cohen et al, 2005; Slater et al, 2008; Zhang et al, 2009, 2010; Touitou et al, 2013; Chang et al, 2014; Lee et al, 2014).…”