Activation of hypoxia-inducible factor-1α in rat brain after perinatal anoxia: role of body temperature

Deciphering the Protective Role of HIF-1α Downregulation on HIBD through the MALAT1/miR-140-5p/TGFBR1/NF-κB Signaling Pathway

Hypoxic-ischemic brain damage (HIBD) in neonates is a substantial cause of mortality and neurodevelopmental impairment, with the exact molecular mechanisms still being elucidated. The involvement of HIF-1α, MALAT1, miR-140-5p, TGFBR1, and the NF-κB signaling pathway in such injury cascades is of increasing research interest due to their pivotal roles in cellular and pathological processes. This study aimed to explore how HIF-1α regulates the MALAT1/miR-140-5p/TGFBR1/NF-κB signaling axis to participate in the molecular mechanisms of HIBD in neonatal rats. Utilizing bioinformatic analyses and a suite of experimental approaches, the study delineated interactions and regulatory relationships among the molecules. Knockdown of HIF-1α was shown to mitigate brain tissue damage in a neonatal HIBD rat model through the MALAT1/miR-140-5p/TGFBR1/NF-κB signaling axis, revealing a protective effect achieved by inhibiting hippocampal neuron apoptosis and potentially guiding the way toward therapeutic interventions in HIBD. This study implicates the HIF-1α mediated regulation of the MALAT1/miR-140-5p/TGFBR1/NF-κB signaling axis in the pathological development of HIBD, offering insights into novel potential interventional strategies.

Exposure to fine particulate matter 2.5 from wood combustion smoke causes vascular changes in placenta and reduce fetal size

During gestation, maternal blood flow to the umbilical cord and placenta increases, facilitating efficient nutrient absorption, waste elimination, and effective gas exchange for the developing fetus. However, the effects of exposure to wood smoke during this period on these processes are unknown. We hypothesize that exposure to PM2.5, primarily sourced from wood combustion for home heating, affects placental vascular morphophysiology and fetal size. We used exposure chambers that received either filtered or unfiltered air. Female rats were exposed to PM2.5 during pre-gestational and/or gestational stages. Twenty-one days post-fertilization, placentas were collected via cesarean section. In these placentas, oxygen diffusion capacity was measured, and the expression of angiogenic factors was analyzed using qPCR and immunohistochemistry. In groups exposed to PM2.5 during pre-gestational and/or gestational stages, a decrease in fetal weight, crown-rump length, theoretical and specific diffusion capacity, and an increase in HIF-1α expression were observed. In groups exposed exclusively to PM2.5 during the pre-gestational stage, there was an increase in the expression of placental genes Flt-1, Kdr, and PIGF. Additionally, in the placental labyrinth region, the expression of angiogenic factors was elevated. Changes in angiogenesis and angiogenic factors reflect adaptations to hypoxia, impacting fetal growth and oxygen supply. In conclusion, this study demonstrates that exposure to PM2.5, emitted from wood smoke, in both pre-gestational and gestational stages, affects fetal development and placental health. This underscores the importance of addressing air pollution in areas with high levels of wood smoke, which poses a significant health risk to pregnant women and their fetuses.

Indole-3-carbinol ameliorated the neurodevelopmental deficits in neonatal anoxic injury in rats

Neonatal anoxia is linked to long-lasting neurodevelopmental deficits. Due to the lack of pharmacological intervention to treat neonatal anoxia, there is interest in finding new molecules for its treatment. Indole-3-carbinol (I3C) has shown neuroprotective effects in some disease conditions. However, the neuroprotective role of I3C in neonatal anoxia has not been explored. Consequently, we have investigated the effect of I3C on neonatal anoxia-induced brain injury and neurodevelopmental deficits. Rat pups after 30 h of birth were subjected to two episodes of anoxia (10 min in each) at a time interval of 24 h by flowing 100% nitrogen. I3C was administered within 30 min of the second episode of anoxia on a postnatal day (PND) 3 and continued for PND 9. Neurodevelopmental deficits, cortical mitochondrial membrane potential (MMP), opening of mitochondrial permeability transition pore (MPTP), electron transport chain (ETC) enzyme activities, oxidative stress, hypoxia-inducible factor-1α (HIF-1α) levels, histopathological changes, and apoptosis were measured. I3C treatment dose-dependently ameliorated the neurodevelopmental deficits and somatic growth in anoxic pups. I3C improved mitochondrial function by enhancing the MMP, mitochondrial ETC enzymes, and antioxidants. It blocked the MPTP opening and release of cytochrome C in anoxic pups. Further, I3C reduced the elevated cortical HIF-1α in neonatal anoxic pups. Furthermore, I3C ameliorated histopathological abnormalities and mitochondrial-mediated apoptotic indicators Cyt C, caspase-9, and caspase-3. Our study concludes that I3C improved neuronal development in anoxic pups by enhancing mitochondrial function, reducing HIF-1α, and mitigating apoptosis.

Hypoxia-inducible factor-1α is involved in the response to heat stress in lactating dairy cows

Hypoxia-inducible factor-1α (HIF-1α) is important in maintaining cellular oxygen homeostasis and cellular heat tolerance. To explore the role of HIF-1α in the response to heat stress (HS) in dairy cows, 16 Chinese Holstein cows (milk yield: 32 ± 4 kg/d, days in milk: 272 ± 7 d, parity: 2-3) were used to collect coccygeal vein blood and milk samples when cows were under mild (temperature-humidity index = 77) and moderate HS (temperature-humidity index = 84), respectively. Compared to cows under mild HS, the respiratory rate (P < 0.01), rectal temperature (P < 0.01), and blood concentrations of heat shock protein (HSP)70 (P < 0.01) and HSP27 (P < 0.01) were higher, but oxygen saturation (P = 0.02) and hemoglobin (P < 0.01) were lower in cows under moderate HS. Blood HIF-1α concentration was greater (P < 0.01) during moderate HS, indicating that HIF-1α is involved in lactating cows' response to HS. To confirm these findings, we collected coccygeal vein blood and milk samples from 59 dairy cows under moderate HS. The HIF-1α levels were correlated with the levels of heat shock transcription factor (HSF) (r = 0.7857, P < 0.01), HSP70 (r = 0.4543, P < 0.01) and HSP27 (r = 0.8782, P < 0.01). A comparison of 15 cows with higher HIF-1α (>482 ng/L) and 15 cows with lower HIF-1α levels (<439 ng/L) showed that reactive oxidative species were higher (P = 0.02), but superoxide dismutase (P < 0.01), total antioxidation capacity (P = 0.02) and glutathione peroxidase (P < 0.01) were lower in higher HIF-1α cows. These results suggested that HIF-1α may be indicative of the risk of oxidative stress in heat-stressed cows and may participate in the response of cows to HS by synergistically activating the expression of the HSP family with HSF.

Erythropoietin regulates signaling pathways associated with neuroprotective events

Erythropoietin is a cytokine that binds to the Erythropoietin receptor and regulates the formation of erythroid cells during erythropoiesis in the bone marrow. However, many other organs and tissues express Erythropoietin and its receptor, such as the Nervous System, which principally regulates tissue protection. In the Central Nervous System, Erythropoietin is principally expressed by astrocytes, while neurons mainly express Erythropoietin receptors. Moreover, Erythropoietin acts as a pleiotropic molecule with neuroprotective effects, and its mechanisms of signal transduction pathways are defined, and there is a growing interest in its therapeutic potential. This review focuses on the role of Erythropoietin and its relationship with HIF1, PI3/Akt, GSK3B, JAK/STAT, and MAPKs signaling pathways that leads to cell survival after injury in the Central Nervous System. Knowledge of these signaling systems comprehensively could better guide EPO treatment to restoring different SNC alterations mediated by different insults.

EPO activates PI3K-IKKα-CDK1 signaling pathway to promote the proliferation of Glial Cells under hypoxia environment

Erythropoietin (EPO), supports the function and survival of neurons through astrocytes and has a protective role in neonatal asphyxia brain injury; yet, its mechanism of action remains unclear. As a neuroprotective factor, EPO is also used in the treatment of various diseases, such as neurodegenerative diseases, Parkinson's disease, traumatic brain injury, by decreasing inflammatory reaction, resisting apoptosis, and lowering oxidative stress. The aim of this study was to examine the effect and mechanism of EPO on promoting human brain glial cell proliferation under hypoxia in vitro. Under CoC12-induced hypoxia, after adding EPO, high-throughput sequencing was used to screen out meaningful up-regulated and significant differentially expressed genes PI3K, IKKα CDK1 related to proliferation, and make further verification by qPCR and western blotting. Under hypoxia, EPO promoted cell proliferation and the expression of PI3K while this effect was inhibited (along with a decrease of downstream genes IKKα and CDK1 decreased) after adding PI3K inhibitor to cell culture. EPO can promote cell proliferation and CDK1 expression, while after inhibiting CDK1 expression, the promotion of EPO on cell proliferation was eliminated. These data proved that EPO promotes the proliferation of U251 cells by activating the PI3K-IKKα-CDK1 signaling pathway under CoC12-induced hypoxia.

The Immunopathogenesis of Neuroinvasive Lesions of SARS-CoV-2 Infection in COVID-19 Patients

The new coronavirus disease COVID-19 was identified in December 2019. It subsequently spread across the world with over 125 M reported cases and 2.75 M deaths in 190 countries. COVID-19 causes severe respiratory distress; however, recent studies have reported neurological consequences of infection by the COVID-19 virus SARS-CoV-2 even in subjects with mild infection and no initial neurological effects. It is likely that the virus uses the olfactory nerve to reach the CNS and that this transport mechanism enables virus access to areas of the brain stem that regulates respiratory rhythm and may even trigger cell death by alteration of these neuronal nuclei. In addition, the long-term neuronal effects of COVID-19 suggest a role for SARS-CoV-2 in the development or progression of neurodegerative disease as a result of inflammation and/or hypercoagulation. In this review recent findings on the mechanism(s) by which SARS-CoV-2 accesses the CNS and induces neurological dysregulation are summarized.

Multitarget neuroprotection by quercetin: Changes in gene expression in two perinatal asphyxia models

Hypoxic-ischemic encephalopathy (HIE) causes mortality and long-term neurologic morbidities in newborns, affecting pathways related to energy failure, excitotoxicity and oxidative stress that often lead to cell death. The whole process of HIE injury is coupled to changes in the expression of a great array of proteins. A nanoliposomal preparation of the flavonoid quercetin has been shown to exert neuroprotective effects in perinatal asphyxia models. This study aimed to identify neonatal HIE markers and explore the effect of quercetin administration in two perinatal asphyxia models: newborn rats and piglets. In the rat model, nanoliposomal quercetin administration reduced mortality after asphyxia. In the piglet model, quercetin partially overrode the reduction of HIF-1α mRNA levels in the cortex induced by asphyxia. Quercetin administration also reduced increased level of HO-1 mRNA in asphyctic piglets. These results suggest that quercetin neuroprotection might be involved in the regulation of HIF-1α, HO-1 and their targets. A proteomic approach revealed that the glycolytic pathway is strongly regulated by quercetin in both species. We also identified a set of proteins differentially expressed that could be further considered as markers. In piglets, this set includes Acidic Leucine-rich nuclear phosphoprotein 32 (ANP32A), associated with nervous system differentiation, proteins related with death pathways and alpha-enolase which can be converted to neuron-specific enolase, a glycolytic enzyme that may promote neuroprotection. In newborn rats, other promising proteins associated with neurogenesis and neuroprotection emerged, such as dihydropyrimidinase-related proteins, catalytic and regulatory subunits of phosphatases and heterogeneous nuclear ribonucleoprotein K (hnRNPK). Our results show that a nanoliposomal preparation of quercetin, with protective effect in two HIE mammal models, modulates the expression of proteins involved in energy metabolism and other putative neuroprotective signals in the cortex. Identification of these signals could reveal potential molecular pathways involved in disease onset and the novel quercetin neuroprotective strategy.

Effect of mandibular advancement device treatment on HIF-1α, EPO and VEGF in the myocardium of obstructive sleep apnea-hypopnea syndrome rabbits

The aim of this study was to investigate the effects of mandibular advancement device (MAD) therapy for obstructive sleep apnea-hypopnea syndrome (OSAHS) on hypoxia-inducible factor-1α (HIF-1α), erythropoietin (EPO) and vascular endothelial growth factor (VEGF) in myocardial tissue. New Zealand rabbits were used to develop OSAHS and MAD models. Cone beam computed tomography (CBCT) of the upper airway and polysomnography (PSG) recordings were performed with the animals in the supine position. All of the animals were induced to sleep in a supine position for 4-6 h each day and were observed continuously for 8 weeks. The myocardial tissue of the three groups was dissected to measure the expression of HIF-1α, EPO and VEGF. The results showed that there was higher expression of HIF-1α, EPO and VEGF in the OSAHS group than those in the MAD and control groups. MAD treatment significantly downregulated the expression of HIF-1α, EPO and VEGF in the OSAHS animals. We concluded that MAD treatment could significantly downregulate the increased expression of HIF-1α, EPO and VEGF in OSAHS rabbits, improving their myocardial function.

Decreased body temperature during anoxia affects the endogenous BDNF level in tertiary phase of injury

Asphyxia before, during, or after birth is an important cause of perinatal mortality and morbidity. The mechanism underlying neurological damage resulting from anoxia episode is complex and is not limited to the anoxia episode. Although the benefits of therapeutic hypothermia in secondary failure of oxidative metabolism have long been known, the principle of this therapy in tertiary phase of repair and reorganization have not yet to be fully elucidated. Currently brain-derived neurotrophic factor (BDNF) is also considered to be beneficial to neuronal survival. Therefore, our experiments aimed at determining the effects of low body temperature during simulated perinatal anoxia on the level of the neurotrophic brain-derived factor (BDNF) and on the correlation between the level of BDNF (proBDNF and mBDNF) and the level of active caspase-3 (marker of apoptosis) in developing brain in tertiary phase after exposure. The results demonstrated that the ability of BDNF to inhibit caspase-3 activation and subsequent apoptosis likely accounts in large part for its protection against neuronal damage only in rats maintaining the low body temperature.

Thermal conditions during neonatal anoxia affect the endogenous level of brain-derived neurotrophic factor

Anoxia during delivery is a complication that can disturb infant brain development leading to various types of neurological disorders. Our studies have shown that increased body temperature of newborn rats of both sexes intensifies the postanoxic oxidative stress and prevents triggering the endogenous adaptive response such as HIF-1α activation. Currently, brain-derived neurotrophic factor-BDNF is considered to be a modulator of neuronal plasticity. In the developing brain, mature BDNF and its precursor exhibit prosurvival action through the TrkB receptor and proapoptotic functions binding to p75^NTR , respectively. The aim of our experiments was to check the effects of body temperature on the postanoxic level of BDNF and on the expression of its receptors as well as on the marker of apoptosis-caspase-3 in the rat brain. Two-day-old Wistar Han rats (male/female ratio, 1:1) were exposed to anoxia in 100% nitrogen atmosphere for 10 min in different thermal conditions, which allowed them to regulate their rectal temperature at the following levels: normothermic-33°C; hyperthermic-37°C; and extremely hyperthermic-39°C. Thermal conditions during neonatal anoxia affected the level of proBDNF, BDNF as well as their receptors and caspase-3 in the forebrain. The increased BDNF protein level followed by decreased caspase-3 protein level was probably dependent on body temperature under anoxic conditions and was observed only in rats maintaining decreased body temperature. The positive effect of BDNF was not observed under hyperthermic conditions. Moreover, BDNF level changes correlated with body temperature probably affected the learning and spatial memory in juvenile rats.