Inhalation of growth factors and apo-transferrin to protect and repair the hypoxic-ischemic brain

Mfat-1 ameliorates cachexia after hypoxic-ischemic brain damage in mice by protecting the hypothalamus-pituitary-adrenal axis

AIMS

Cachexia, a metabolic syndrome, affects 21 % of patients suffering from ischemic encephalopathy. However, the specific mechanism and prevention measures are still unclear. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been proven to reduce inflammatory cytokine levels during ischemic events, but whether they have a protective effect against cachexia after hypoxic-ischemic brain damage (HIBD) remains unclear.

MAIN METHODS

C57BL/6J wild-type and mfat-1 transgenic male mice were treated with and without HIBD. One day after HIBD, the epididymal white fat, gastrocnemius muscle and hypothalamus were weighed and analyzed the phenotypic changes. RNA sequencing was applied to gastrocnemius muscle to identify differential genes and pathways in HIBD groups. The effect of HPA axis on cachexia post-HIBD was examined via adrenalectomy, dexamethasone (0.1 mg/kg), and corticosterone injection (100 mg/kg).

KEY FINDINGS

The results showed that the incidence of cachexia in mfat-1 mice, which produce high proportion of n-3 PUFAs, was significantly lower than that in wild-type mice post-HIBD. Cachexia-related factors, such as inflammation, muscle atrophy and lipid metabolism were significantly improved in mfat-1 HIBD. RNA sequencing revealed that catabolic and proteasome pathways were significantly downregulated. In hypothalamus, inflammatory cytokines, lipid peroxidation levels were reduced. Corticosterone, glucocorticoid receptor, and dexamethasone suppression test all showed that mfat-1 improved the dysfunction of the HPA axis post-HIBD. The present study elucidated for the first time that mfat-1 reduced HIBD-induced hyperactivation of the HPA axis in mice by reducing inflammation and oxidative stress and contributed to the reduction of metabolic imbalance in peripheral tissues.

SIGNIFICANCE

Our study provides mechanistic information for the development of intervention strategies to prevent cachexia.

Short-Chain Fatty Acids Reduce Oligodendrocyte Precursor Cells Loss by Inhibiting the Activation of Astrocytes via the SGK1/IL-6 Signalling Pathway

Short-chain fatty acids (SCFAs) are known to be actively involved in neurological diseases, but their roles in hypoxic-ischaemic brain injury (HIBI) are unclear. In this study, a rat model of HIBI was established, and this study measured the changes in IL-6 and NOD-like receptor thermal protein domain associated protein 3 (NLRP3), in addition to proliferation and apoptosis indicators of oligodendrocyte precursor cells (OPCs). The mechanism of action of SCFA on astrocytes was also investigated. Astrocytes were subjected to hypoxia in vitro, and OPCs were treated with IL-6. The results showed that SCFAs significantly alleviated HIBI-induced activation of astrocytes and loss of OPCs. SCFA pretreatment (1) downregulated the expression of NLRP3, IL-6, CCL2, and IP-10; (2) had no effect on the proliferation of OPCs; (3) ameliorated the abnormal expression of Bax and Bcl-2; and (4) regulated IL-6 expression via the SGK1-related pathway in astrocytes. Our findings revealed that SCFAs alleviated the loss of OPCs by regulating astrocyte activation through the SGK1/IL-6 signalling pathway.

Pharmacological Neuroprotection of the Preterm Brain: Current Evidence and Perspectives

Despite improvements in viability, the long-term neurodevelopmental outcomes of preterm babies remain serious concern as a significant percentage of these infants develop neurological and/or intellectual impairment, and they are also at increased risk of psychiatric illnesses later in life. The current challenge is to develop neuroprotective approaches to improve adverse outcomes in preterm survivors. The purpose of this review was to provide an overview of the current evidence on pharmacological agents targeting the neuroprotection of the preterm brain. Among them, magnesium sulfate, given antenatally to pregnant women with imminent preterm birth before 30 to 34 weeks of gestation, as well as caffeine administered to preterm infants after birth, exhibited neuroprotective effects for human preterm brain. Erythropoietin treatment of preterm infants did not result in neuroprotection at 2 years of age in two out of three published large randomized controlled trials; however, long-term follow-up of these infants is needed to come to definite conclusions. Further studies are also required to assess whether melatonin, neurosteroids, inhaled nitric oxide, allopurinol, or dietary supplements (omega-3 fatty acids, choline, curcumin, etc.) could be implemented as neuroprotectants in clinical practice. Furthermore, other pharmacological agents showing promising signs of neuroprotective efficacy in preclinical studies (growth factors, hyaluronidase inhibitors or treatment, antidiabetic drugs, cannabidiol, histamine-H3 receptor antagonists, etc.), as well as stem cell- or exosomal-based therapies and nanomedicine, may prove useful in the future as potential neuroprotective approaches for human preterm brain. KEY POINTS: · Magnesium and caffeine have neuroprotective effects for the preterm brain.. · Follow-up of infants treated with erythropoietin is needed.. · Neuroprotective efficacy of several drugs in animals needs to be shown in humans..

Ferroptosis is involved in hypoxic-ischemic brain damage in neonatal rats

Ferroptosis is an iron-dependent form of regulated cell death, which is driven by loss of activity of the lipid repair enzyme glutathione peroxidase 4 (GPX4) and subsequent accumulation of lipid peroxidation. Ferroptosis is implicated in various diseases involving neuronal injury. However, the role of ferroptosis in hypoxic-ischemic brain damage (HIBD) has not been elucidated. The objectives of this study were to evaluate whether ferroptosis is involved in hypoxic-ischemic brain damage and its mechanisms through the HIBD model. A 7-day-old male Sprague-Dawley neonatal rat HIBD model was established by blocking the left common carotid artery. Laser speckle contrast imaging, immunohistochemical staining, transmission electron microscopy were used to measure the effects of ferroptosis on HIBD. Brain tissue on the damaged side in the HIBD group showed atrophied, even liquefied, glial cells increased, and blood perfusion was significantly reduced. The HIBD group insult significantly increased reactive oxygen species levels, as well as the protein levels of iron metabolism-related proteins transferrin receptor (TFRC), ferritin heavy chain (FHC), and ferritin light chain (FLC), while reducing the levels of Solute Carrier Family 7 Member 11 (SLC7A11), glutathione (GSH), and GPX4. These changes resulted in diminished cellular antioxidant capacity and mitochondrial damage, causing neuronal ferroptosis in the cerebral cortex. We conclude that ferroptosis plays a role in HIBD in neonatal rats. Ferroptosis-related mechanisms such as abnormalities in iron metabolism, amino acid metabolism, and lipid peroxidation regulation play important roles in HIBD.

Transferrin Non-Viral Gene Therapy for Treatment of Retinal Degeneration

Dysregulation of iron metabolism is observed in animal models of retinitis pigmentosa (RP) and in patients with age-related macular degeneration (AMD), possibly contributing to oxidative damage of the retina. Transferrin (TF), an endogenous iron chelator, was proposed as a therapeutic candidate. Here, the efficacy of TF non-viral gene therapy based on the electrotransfection of pEYS611, a plasmid encoding human TF, into the ciliary muscle was evaluated in several rat models of retinal degeneration. pEYS611 administration allowed for the sustained intraocular production of TF for at least 3 and 6 months in rats and rabbits, respectively. In the photo-oxidative damage model, pEYS611 protected both retinal structure and function more efficiently than carnosic acid, a natural antioxidant, reduced microglial infiltration in the outer retina and preserved the integrity of the outer retinal barrier. pEYS611 also protected photoreceptors from N-methyl-N-nitrosourea-induced apoptosis. Finally, pEYS611 delayed structural and functional degeneration in the RCS rat model of RP while malondialdehyde (MDA) ocular content, a biomarker of oxidative stress, was decreased. The neuroprotective benefits of TF non-viral gene delivery in retinal degenerative disease models further validates iron overload as a therapeutic target and supports the continued development of pEY611 for treatment of RP and dry AMD.

Combination therapy of apo-transferrin and thyroid hormones enhances remyelination

The current study presents two different approaches with a view to elucidating the interaction between thyroid hormones (TH) and apo-transferrin (aTf) and their role in myelination and remyelination. First, in vitro assays were conducted to determine the single and combined effects of aTf and triiodothyronine (T3) on oligodendroglial cell lineage proliferation and oligodendrocyte (OLG) maturation in primary cultures. Results revealed higher proliferation rates upon single aTf treatment but Control values upon T3 and aTf + T3 treatments. In addition, both aTf and T3 accelerated OLG maturation, with the greatest effects being exerted by combined aTf + T3 administration in terms of both myelin basic protein (MBP) expression and morphological complexity. Second, in vivo assays were carried out to establish single and combined effects of aTf and T3, as well as TH receptor (THR) inhibitor I-850, on remyelination following a CPZ-induced demyelination protocol. Results showed an increase in myelin deposition and the number of mature remyelinating OLG upon single treatments, but a synergic effect upon combined aTf + T3 treatment which was prevented by THR inhibition. It may be thus concluded that combined treatment yielded the most beneficial effects on OLG maturation parameters in vitro and remyelinating capacity in vivo when compared to single treatments. These findings may help explore the development of new target molecules in the treatment of demyelinating diseases.

An enhanced charge-driven intranasal delivery of nicardipine attenuates brain injury after intracerebral hemorrhage

Intranasal drug delivery provided an alternative and effective approach for the intervention of an intracerebral hemorrhage (ICH). However, the short retention time at the absorption site and slow drug transport in intranasal gel influence the drug bioavailability and outcome of ICH. Herein, we fabricated a novel intranasal gel with oriented drug migration utilizing a charge-driven strategy to attenuate brain injury after ICH. Nicardipine hydrochloride (NCD) was entrapped in chitosan nanoparticles (CS NPs) and dispersed in an HAMC gel. Subsequently, one side of the gel was coated with a positively charged film. The oriented migration of CS NPs in the HAMC gel was determined, and the drug bioavailability was also enhanced. Furthermore, a blood-induced ICH rat model was established to evaluate the therapeutic effect of CS NPs + HAMC composites. Intranasal administration of the CS NPs + HAMC (+) composite showed a stronger neuroprotective effect in terms of brain edema reduction and neural apoptosis inhibition compared to the CS NPs + HAMC composite. These results suggested that the oriented and rapid drug transport from nose to brain can be achieved using the charge-driven strategy, and this intranasal drug delivery system has the potential to provide a new therapeutic strategy for the treatment of ICH.

The Combination of Human Urinary Kallidinogenase and Mild Hypothermia Protects Adult Rats Against Hypoxic-Ischemic Encephalopathy-Induced Injury by Promoting Angiogenesis and Regeneration

Objectives: Human Urinary Kallidinogenase (HUK) is a tissue kallikrein that plays neuroprotective role in ischemic conditions via different mechanisms. Mild hypothermia (MH) is another robust neuroprotectant that reduces mortality but does not profoundly ameliorate the neurological outcome in hypoxic-ischemic encephalopathy (HIE) patients. However, whether the combination of HUK and MH can be used as a promising neuroprotective treatment in HIE is unknown. Methods: One-hundred and forty-four adult Wistar rats were randomly divided into five groups: Sham, HIE, HUK, MH and a combination of HUK and MH treatment. The HIE rat model was established by right carotid dissection followed by hypoxia aspiration. The survival curve was created within 7 days, and the neurological severity scores (NSS) were assessed at days 0, 1, 3, and 7. Nissl staining, Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), immunofluorescent staining and western blotting were used to evaluate neuronal survival, apoptosis and necrosis, tight-junction proteins Claudin-1 and Zonula occludens-1 (ZO-1), vascular endothelial growth factor (VEGF), doublecortex (DCX), bradykinin receptor B1 (BDKRB1), BDKRB2 and Ki67 staining. Results: The combined treatment rescued all HIE rats from death and had a best survival curve compared to HIE. The Combination also reduced the NSS scores after HIE at days 7, better than HUK or MH alone. The combination of HUK and MH reserved more cells in Nissl staining and inhibited neuronal apoptosis and necrosis as well as significantly attenuated HIE-induced decreases in claudin-1, ZO-1, cyclin D1 and BDKRB1/B2 in comparison to HUK or MH treatment alone. Moreover, the combined treatment increased the expression of VEGF and DCX as well as the number of Ki67-labeled cells. Conclusions: This study demonstrates that both HUK and MH are neuroprotective after HIE insult; however, the combined therapy with HUK and MH enhanced the efficiency and efficacy of either therapy alone in the treatment of HIE, at least partially by promoting angiogenesis and regeneration and rescuing tight-junction loss. The combination of HUK and MH seems to be a feasible and promising clinical strategy to alleviate cerebral injury following HIE insult. Highlights: -The combination of HUK and MH distinctly reduces neurological dysfunction in HIE rats.-HUK enhances the neuroprotective effects of MH in HIE.-MH attenuates tight-junction disruption, upregulates the BDKR B1/2, DCX and cyclin D1.-The combination of MH and HUK enhances the expressions of MH/HUK mediated-BDKR B1/2, DCX, cyclin D1 and Ki67 positive cells.

Helium preconditioning protects the brain against hypoxia/ischemia injury via improving the neurovascular niche in a neonatal rat model

This study aimed to investigate whether helium preconditioning (He-PC) is able to exert neuroprotective effects via improving focal neurovascular niche in a neonatal rat hypoxia/ischemia (HI) brain injury model. Seven day old rat pups were divided into control group, HI group and He-PC group. HI was induced by exposure to 8% oxygen for 90min one day after preconditioning with 70% helium-30% oxygen for three 5-min periods. At 3 and 7 days, the brain was collected for the detection of inflammation related factors (tumor necrosis factor α [TNF-α], interleukin-1β [IL-1β], IL-10) and growth/neurotrophic factors (brain-derived neurotrophic factor [BDNF], basic fibroblast growth factor [bFGF] and nerve growth factor [NGF]); at 7 days, neurobehaviors were evaluated, and the brain was collected for the detection of mRNA expression of vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1) by PCR, protein expression of angiogenesis related molecules (VEGF, Ang-1, Tie-2 and Flt-1) by Western blotting and microvessel density (MCD) by immunohistochemistry for vWF. Results showed He-PC was able to reduce TNF-α and IL-1β, further increase IL-10, BDNF, bFGF and NGF, elevate the mRNA expression of VEGF and Ang-1, increase the protein expression of VEGF, Ang-1, Tie-2 and Flt-1, promote angiogenesis and improve neurobehaviors as compared to HI group. These findings suggest that He-PC may improve the post-stroke neurovascular niche to exert neuroprotective effects on neonatal HI brain injury.