Regulation of therapeutic hypothermia on inflammatory cytokines, microglia polarization, migration and functional recovery after ischemic stroke in mice

Abstract

Stroke is a leading threat to human life and health in the US and around the globe, while very few effective treatments are available for stroke patients. Preclinical and clinical studies have shown that therapeutic hypothermia (TH) is a potential treatment for stroke. Using novel neurotensin receptor 1 (NTR1) agonists, we have demonstrated pharmacologically induced hypothermia and protective effects against brain damages after ischemic stroke, hemorrhage stroke, and traumatic brain injury (TBI) in rodent models. To further characterize the mechanism of TH-induced brain protection, we examined the effect of TH (at ±33°C for 6 hrs) induced by the NTR1 agonist HPI-201 or physical (ice/cold air) cooling on inflammatory responses after ischemic stroke in mice and oxygen glucose deprivation (OGD) in cortical neuronal cultures. Seven days after focal cortical ischemia, microglia activation in the penumbra reached a peak level, which was significantly attenuated by TH treatments commenced 30 min after stroke. The TH treatment decreased the expression of M1 type reactive factors including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-12, IL-23, and inducible nitric oxide synthase (iNOS) measured by RT-PCR and Western blot analyses. Meanwhile, TH treatments increased the expression of M2 type reactive factors including IL-10, Fizz1, Ym1, and arginase-1. In the ischemic brain and in cortical neuronal/BV2 microglia cultures subjected to OGD, TH attenuated the expression of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α), two key chemokines in the regulation of microglia activation and infiltration. Consistently, physical cooling during OGD significantly decreased microglia migration 16 hrs after OGD. Finally, TH improved functional recovery at 1, 3, and 7 days after stroke. This study reveals the first evidence for hypothermia mediated regulation on inflammatory factor expression, microglia polarization, migration and indicates that the anti-inflammatory effect is an important mechanism underlying the brain protective effects of a TH therapy.

Protective effects of GPR37 via regulation of inflammation and multiple cell death pathways after ischemic stroke in mice

“…Real-time RT-PCR was used to detect the expression of mRNA. Total RNA was extracted from samples using Trizol (Thermo Fisher Scientific) as previously described by Lee et al (34). The RNA samples were reverse transcribed to cDNA in 20 ml of a reaction mixture containing 20-times RT buffer and 20-times RT enzyme mix according to the manufacturer's instruction (Thermo Fisher Scientific) at 37°C for 60 min as previously described by Lee et al (35).…”

Anti-inflammatory and anti-apoptotic effects of the combination of Ligusticum chuanxiong and Radix Paeoniae against focal cerebral ischaemia via TLR4/MyD88/MAPK/NF-κB signalling pathway in MCAO rats

“…Stroke has become a leading cause of adult death and disability, and approximately 15 million people are subjected to ischaemic strokes in the world each year. [1,2] Ischaemic stroke is associated with various pathophysiological mechanisms, such as oxidative damage, blood-brain barrier (BBB) disruption, inflammatory reaction and neuronal apoptosis. [3,4] Previous researches have reported that the progress of neuronal injury and cerebral infarction result from the postischaemic inflammation and apoptosis.…”

Longitudinal MRI evaluation of neuroprotective effects of pharmacologically induced hypothermia in experimental ischemic stroke

“…Previous investigations evaluated the duration of hypothermia for achieving therapeutic effect after stroke. For the PIH treatment, we previously compared the neuroprotective effect of 6 hrs and 24 hrs hypothermia and did not observe additional benefits by the prolonged treatment [29]. There was no rebound over the basal body temperature after the PIH treatment.…”

“…Therefore, NTR1 agonist by targeting the central thermoregulatory system could have synergistic effects of temperature reduction and associated neuroprotective benefits. We recently reported that the PIH therapy significantly suppressed inflammatory responses in stroke mice, such as reducing inflammatory factors and microglia activation [29]. The anti-inflammation effect and functional benefits lasted for 14–21 days after stroke.…”

“…HPI-201 is a novel neurotensin receptor 1 (NTR1) agonist. Recent studies have demonstrated it is effective in inducing therapeutic hypothermia, reducing inflammatory response, brain injury and promote long-term functional recovery after ischemic, hemorrhagic stroke and traumatic brain injury (TBI) [15, 16, 29, 30]. The main aim of the present study is to longitudinally examine HPI201 induced therapeutic effects on acute ischemic stroke using MRI.…”