Project description:Perinatal hypoxia-ischemia remains the primary cause of acute neonatal brain injury, leading to a high mortality rate and long-term neurological deficits, such as behavioral, social, attentional, cognitive and functional motor deficits. An ever-increasing body of evidence shows that the immune response to acute cerebral hypoxia-ischemia is a major contributor to the pathophysiology of neonatal brain injury. Hypoxia-ischemia provokes an intravascular inflammatory cascade that is further augmented by the activation of resident immune cells and the cerebral infiltration of peripheral immune cells response to cellular damages in the brain parenchyma. This prolonged and/or inappropriate neuroinflammation leads to secondary brain tissue injury. Yet, the long-term effects of immune activation, especially the adaptive immune response, on the hypoxic-ischemic brain still remain unclear. The focus of this review is to summarize recent advances in the understanding of post-hypoxic-ischemic neuroinflammation triggered by the innate and adaptive immune responses and to discuss how these mechanisms modulate the brain vulnerability to injury. A greater understanding of the reciprocal interactions between the hypoxic-ischemic brain and the immune system will open new avenues for potential immunomodulatory therapy in the treatment of neonatal brain injury.
Project description:Inflammation is a critical factor for development of hypoxic-ischemic (HI) brain injury. Interleukin-18 (IL-18) is a proinflammatory cytokine expressed in microglia and processed by caspase-1. Our aim was to characterize the expression of IL-18 and its receptor in relation to caspase-1 and IL-1beta after HI and to evaluate to what extent IL-18 contributes to HI brain injury. Seven-day-old rats were subjected to HI, and brain tissue was sampled at different time points (3 hr to 14 d) after insult. The mRNA for IL-18 and caspase-1 were analyzed with reverse transcriptase PCR, protein was analyzed by Western blot (IL-18, caspase-1) or ELISA (IL-1beta), and the regional distribution was assessed by immunohistochemistry. HI was also induced in C57BL/6 mice, and brain injury in IL-18-deficient animals was compared with that in wild-type animals. The expression of mRNA/protein for caspase-1 and IL-18 in brain homogenates increased progressively at 12 hr to 14 d after HI, whereas IL-1beta peaked at 8 hr. A widespread expression of caspase-1 and IL-18 protein in microglia was found in the HI hemisphere. The IL-18 receptor was expressed on neurons of the cerebral cortex and thalamus. IL-1beta was primarily found in microglia in the habenular nucleus of the thalamus. The infarct volume was reduced by 21% (p = 0.01), and the neuropathology score was significantly decreased in the cerebral cortex (-35%), hippocampus (-22%), striatum (-18%), and thalamus (-17%) in mice with IL-18 deficiency compared with wild-type mice. In conclusion, we found that IL-18 expression in microglia was markedly increased after HI and that IL-18 appears to be important for the development of HI brain injury.
Project description:Hypoxic-ischemic encephalopathy (HIE) is a major cause of mortality and morbidity in neonates, with an estimated global incidence of 3/1,000 live births. HIE brain damage is associated with an inflammatory response and oxidative stress, resulting in the activation of cell death pathways. At present, therapeutic hypothermia is the only clinically approved treatment available for HIE. This approach, however, is only partially effective. Therefore, there is an unmet clinical need for the development of novel therapeutic interventions for the treatment of HIE. Curcumin is an antioxidant reactive oxygen species scavenger, with reported anti-tumor and anti-inflammatory activity. Curcumin has been shown to attenuate mitochondrial dysfunction, stabilize the cell membrane, stimulate proliferation, and reduce injury severity in adult models of spinal cord injury, cancer, and cardiovascular disease. The role of curcumin in neonatal HIE has not been widely studied due to its low bioavailability and limited aqueous solubility. The aim of this study was to investigate the effect of curcumin treatment in neonatal HIE, including time of administration and dose-dependent effects. Our results indicate that curcumin administration prior to HIE in neonatal mice elevated cell and tissue loss, as well as glial activation compared to HI alone. However, immediate post-treatment with curcumin was significantly neuroprotective, reducing grey and white matter tissue loss, TUNEL+ cell death, microglia activation, reactive astrogliosis, and iNOS oxidative stress when compared to vehicle-treated littermates. This effect was dose-dependent, with 200 μg/g body weight as the optimal dose-regimen, and was maintained when curcumin treatment was delayed by 60 or 120 min post-HI. Cell proliferation measurements showed no changes between curcumin and HI alone, suggesting that the protective effects of curcumin on the neonatal brain following HI are most likely due to curcumin's anti-inflammatory and antioxidant properties, as seen in the reduced glial and iNOS activity. In conclusion, this study suggests curcumin as a potent neuroprotective agent with potential for the treatment of HIE. The delayed application of curcumin further increases its clinical relevance.
Project description:AimNeonatal hypoxic-ischemia (HI) due to insufficient oxygen supply and blood flow during the prenatal and postnatal periods can cause cerebral palsy, a serious developmental condition. The purpose of this study was to investigate the efficacy of combining constraint-induced movement therapy (CIMT) and electroacupuncture to treat rat neonatal HI brain injury.MethodsThe left common carotid arteries of postnatal day 7 rats were ligated to induce HI brain injury, and the neonates were kept in a hypoxia chamber containing 8% oxygen for 2 hrs. Electroacupuncture at Baihui (GV 20) and Zusanli (ST 36) was performed concurrently with CIMT 3 weeks after HI induction for 4 weeks.ResultsMotor asymmetry after HI was significantly improved in the CIMT and electroacupuncture combination group, but HI lesion size was not improved. The combination of CIMT and electroacupuncture after HI injury increases NeuN and decreases GFAP levels in the cerebral cortex, suggesting that this combination treatment inversely regulates neurons and astrocytes. In addition, the combination treatment group reduced the level of cleaved caspase-3, a crucial mediator of apoptosis, in the cortex.ConclusionsOur findings indicate that a combination of CIMT and electroacupuncture is an effective method to treat hemiplegia due to neonatal HI brain injury.
Project description:Perinatal hypoxic-ischemic brain injury is a common problem with potentially devastating impact on neurodevelopmental outcomes. While therapeutic hypothermia, the first available treatment for this disease, reduces the risk of death or major neurodevelopmental disability, the risk of major neurologic morbidity following HI remains significant. Basic research has identified cellular mechanisms that mediate neuronal death. This article reviews the cellular processes induced that lead to brain injury following HI, and identify treatments currently under investigation for potential translation to clinical trials.
Project description:Newborns suffering from hypoxia-ischemia (HI) brain injury still lack effective treatment. Proline-rich tyrosine kinase 2 (Pyk2) is a non-receptor tyrosine kinase, which is highly correlated with transient ischemic brain injury in adult. In this study, we investigated the role of Pyk2 in neonatal HI brain injury. HI was induced in postnatal day 7 mouse pups by unilateral common carotid artery ligation followed by hypoxic exposure. Pyk2 interference lentivirus (LV-Pyk2 shRNA) was constructed and injected into unilateral cerebral ventricle of neonatal mice before HI. Infarct volume, pathological changes, and neurological behaviors were assessed on postnatal day 8-14. We showed that the phosphorylation level of Pyk2 was significantly increased in neonatal brain after HI, whereas LV-Pyk2 shRNA injection significantly attenuated acute HI brain damage and improved neurobehavioral outcomes. In oxygen-glucose deprivation-treated cultured cortical neurons, Pyk2 inhibition significantly alleviated NMDA receptor-mediated excitotoxicity; similar results were also observed in neonatal HI brain injury. We demonstrated that Pyk2 inhibition contributes to the long-term cerebrovascular recovery assessed by laser speckle contrast imaging, but cognitive function was not obviously improved as evaluated in Morris water maze and novel object recognition tests. Thus, we constructed lentiviral LV-HIF-Pyk2 shRNA, through which HIF-1α promoter-mediated interference of Pyk2 would occur during the anoxic environment. Intracerebroventricular injection of LV-HIF-Pyk2 shRNA significantly improved long-term recovery of cognitive function in HI-treated neonatal mice. In conclusion, this study demonstrates that Pyk2 interference protects neonatal brain from hypoxic-ischemic injury. HIF-1α promoter-mediated hypoxia conditional control is a useful tool to distinguish between hypoxic period and normal period. Pyk2 is a promising drug target for potential treatment of neonatal HI brain injury.
Project description:Recent studies have shown that chlorogenic acid (CGA), which is present in coffee, has protective effects on the nervous system. However, its role in neonatal hypoxic-ischemic brain injury remains unclear. In this study, we established a newborn mouse model of hypoxic-ischemic brain injury using a modified Rice-Vannucci method and performed intraperitoneal injection of CGA. We found that CGA intervention effectively reduced the volume of cerebral infarct, alleviated cerebral edema, restored brain tissue structure after injury, and promoted axon growth in injured brain tissue. Moreover, CGA pretreatment alleviated oxygen-glucose deprivation damage of primary neurons and promoted neuron survival. In addition, changes in ferroptosis-related proteins caused by hypoxic-ischemic brain injury were partially reversed by CGA. Furthermore, CGA intervention upregulated the expression of the key ferroptosis factor glutathione peroxidase 4 and its upstream glutamate/cystine antiporter related factors SLC7A11 and SLC3A2. In summary, our findings reveal that CGA alleviates hypoxic-ischemic brain injury in neonatal mice by reducing ferroptosis, providing new ideas for the treatment of neonatal hypoxic-ischemic brain injury.
Project description:Each year, more than two million babies die or evolve to permanent invalidating sequelae worldwide because of Hypoxic-Ischemic Brain Injury (HIBI). There is no current treatment for that condition except for therapeutic hypothermia, which benefits only a select group of newborns. Preclinical studies offer solid evidence of the neuroprotective effects of Cannabidiol (CBD) when administered after diffuse or focal HI insults to newborn pigs and rodents. Such effects are observable in the short and long term as demonstrated by functional, neuroimaging, histologic and biochemical studies, and are related to the modulation of excitotoxicity, inflammation and oxidative stress-the major components of HIBI pathophysiology. CBD protects neuronal and glial cells, with a remarkable effect on preserving normal myelinogenesis. From a translational point of view CBD is a valuable tool for HIBI management since it is safe and effective. It is administered by the parenteral route a posteriori with a broad therapeutic time window. Those findings consolidate CBD as a promising treatment for neonatal HIBI, which is to be demonstrated in clinical trials currently in progress.
Project description:Hypoxic-ischemic brain injury (HIBI) leads to depletion of ATP, mitochondrial dysfunction, and enhanced oxidant formation. Measurement of acylcarnitines may provide insight into mitochondrial dysfunction. Plasma acylcarnitine levels are altered in neonates after an HIBI, but individual acylcarnitine levels in the brain have not been evaluated. Additionally, it is unknown if plasma acylcarnitines reflect brain acylcarnitine changes. In this study, postnatal day 9 CD1 mouse pups were randomized to HIBI induced by carotid artery ligation, followed by 30 min at 8% oxygen, or to sham surgery and normoxia, with subgroups for tissue collection at 30 min, 24 h, or 72 h after injury (12 animals/group). Plasma, liver, muscle, and brain (dissected into the cortex, cerebellum, and striatum/thalamus) tissues were collected for acylcarnitine analysis by LC-MS. At 30 min after HIBI, acylcarnitine levels were significantly increased, but the differences resolved by 24 h. Palmitoylcarnitine was increased in the cortex, muscle, and plasma, and stearoylcarnitine in the cortex, striatum/thalamus, and cerebellum. Other acylcarnitines were elevated only in the muscle and plasma. In conclusion, although plasma acylcarnitine results in this study mimic those seen previously in humans, our data suggest that the plasma acylcarnitine profile was more reflective of muscle changes than brain changes. Acylcarnitine metabolism may be a target for therapeutic intervention after neonatal HIBI, though the lack of change after 30 min suggests a limited therapeutic window.