Protective effect of rhEPO on tight junctions of cerebral microvascular endothelial cells early following traumatic brain injury in rats

Transcriptomic and bioinformatics analysis of the mechanism by which erythropoietin promotes recovery from traumatic brain injury in mice

Recent studies have found that erythropoietin promotes the recovery of neurological function after traumatic brain injury. However, the precise mechanism of action remains unclear. In this study, we induced moderate traumatic brain injury in mice by intraperitoneal injection of erythropoietin for 3 consecutive days. RNA sequencing detected a total of 4065 differentially expressed RNAs, including 1059 mRNAs, 92 microRNAs, 799 long non-coding RNAs, and 2115 circular RNAs. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses revealed that the coding and non-coding RNAs that were differentially expressed after traumatic brain injury and treatment with erythropoietin play roles in the axon guidance pathway, Wnt pathway, and MAPK pathway. Constructing competing endogenous RNA networks showed that regulatory relationship between the differentially expressed non-coding RNAs and mRNAs. Because the axon guidance pathway was repeatedly enriched, the expression of Wnt5a and Ephb6, key factors in the axonal guidance pathway, was assessed. Ephb6 expression decreased and Wnt5a expression increased after traumatic brain injury, and these effects were reversed by treatment with erythropoietin. These findings suggest that erythropoietin can promote recovery of nerve function after traumatic brain injury through the axon guidance pathway.

Carvacrol decreases blood-brain barrier permeability post-diffuse traumatic brain injury in rats

Previously, we showed that Satureja Khuzestanica Jamzad essential oil (SKEO) and its major component, carvacrol (CAR), 5-isopropyl-2-methylphenol, has anti-inflammatory, anti-apoptotic, and anti-edematous properties after experimental traumatic brain injury (TBI) in rats. CAR, predominantly found in Lamiaceae family (Satureja and Oregano), is lipophilic, allowing diffusion across the blood-brain barrier (BBB). These experiments test the hypothesis that acute treatment with CAR after TBI can attenuate oxidative stress and BBB permeability associated with CAR's anti-edematous traits. Rats were divided into six groups and injured using Marmarou weight drop: Sham, TBI, TBI + Vehicle, TBI + CAR (100 and 200 mg/kg) and CAR200-naive treated rats. Intraperitoneal injection of vehicle or CAR was administered thirty minutes after TBI induction. 24 h post-injury, brain edema, BBB permeability, BBB-related protein levels, and oxidative capacity were measured. Data showed CAR 200 mg/kg treatment decreased brain edema and prevented BBB permeability. CAR200 decreased malondialdehyde (MDA) and reactive oxygen species (ROS) and increased superoxide dismutase (SOD) and total antioxidative capacity (T-AOC), indicating the mechanism of BBB protection is, in part, through antioxidant activity. Also, CAR 200 mg/kg treatment suppressed matrix metalloproteinase-9 (MMP-9) expression and increased ZO-1, occludin, and claudin-5 levels. These data indicate that CAR can promote antioxidant activity and decrease post-injury BBB permeability, further supporting CAR as a potential early therapeutic intervention that is inexpensive and more readily available worldwide. However, more experiments are required to determine CAR's long-term impact on TBI pathophysiology.

Further Evidence of Neuroprotective Effects of Recombinant Human Erythropoietin and Growth Hormone in Hypoxic Brain Injury in Neonatal Mice

Experimental in vivo data have recently shown complementary neuroprotective actions of rhEPO and growth hormone (rhGH) in a neonatal murine model of hypoxic brain injury. Here, we hypothesized that rhGH and rhEPO mediate stabilization of the blood−brain barrier (BBB) and regenerative vascular effects in hypoxic injury to the developing brain. Using an established model of neonatal hypoxia, neonatal mice (P7) were treated i.p. with rhGH (4000 µg/kg) or rhEPO (5000 IU/kg) 0/12/24 h after hypoxic exposure. After a regeneration period of 48 h or 7 d, cerebral mRNA expression of Vegf-A, its receptors and co-receptors, and selected tight junction proteins were determined using qRT-PCR and ELISA. Vessel structures were assessed by Pecam-1 and occludin (Ocln) IHC. While Vegf-A expression increased significantly with rhGH treatment (p < 0.01), expression of the Vegfr and TEK receptor tyrosine kinase (Tie-2) system remained unchanged. RhEPO increased Vegf-A (p < 0.05) and Angpt-2 (p < 0.05) expression. While hypoxia reduced the mean vessel area in the parietal cortex compared to controls (p < 0.05), rhGH and rhEPO prevented this reduction after 48 h of regeneration. Hypoxia significantly reduced the Ocln+ fraction of cortical vascular endothelial cells. Ocln signal intensity increased in the cortex in response to rhGH (p < 0.05) and in the cortex and hippocampus in response to rhEPO (p < 0.05). Our data indicate that rhGH and rhEPO have protective effects on hypoxia-induced BBB disruption and regenerative vascular effects during the post-hypoxic period in the developing brain.

miR-29a-5p Alleviates Traumatic Brain Injury- (TBI-) Induced Permeability Disruption via Regulating NLRP3 Pathway

Objective

Inactivation of NLRP3 inflammasome plays a role in reducing the permeability of endothelial cells and improving blood-brain barrier (BBB) dysfunction following traumatic brain injury (TBI). However, the mechanism controlling NLRP3 inflammasome activation remains unclear. This study is aimed at defining the role of miR-29a-5p in NLRP3 inflammasome activation and permeability of endothelial cells under TBI.

Methods

The scratch injury model on brain bEnd.3 microvascular endothelial cells was used as in vitro TBI model cells. Effects of miR-29a mimics and inhibitors on TBI model cells were observed by examining their action on FITC, TEER, and protein contents of ZO-1 and occludin, and cell permeability-associated protein. Luciferase reporter assay evaluated miR-29a-5p targeting to NLRP3. ELISA examined of IL-1β and IL-18 levels. miR-29a-5p mimic was injected into TBI mouse and its effect on BBB, indicated by Evans blue (EB) staining assay and cerebral water content, and NLRP3 activation was examined.

Results

miR-29a-3p and miR-29a-5p mimics decrease the concentration of FITC, and increase TEER and the protein contents of ZO-1 and occludin in TBI model cells. miR-29a-5p silencing disrupted the permeability of mouse bEnd.3 cells. miR-29a-5p targets to NLRP3 through the binding on its 3′UTR and negatively regulates its expression in TBI model cells. NLRP3 inhibition and miR-29a-5p silencing together caused significantly decreased FITC concentration and increased TEER value and release of IL-1β and IL-18. miR-29a-5p mimic alleviated the BBB and cerebral water content and inactivates NLRP3 in the mouse TBI model.

Conclusions

miR-29a-5p mimics protect TBI-induced increased endothelial cell permeability and BBB dysfunction via suppressing NLRP3 expression and activation.

A novel ex vivo porcine model of acid-induced esophageal damage for preliminary functional evaluations of anti-gastroesophageal reflux disease medical devices

Aim

The aim of the study was to set up a porcine ex vivo model of acid-induced damage and to evaluate its performance by means of multichannel intraluminal impedance and pH (MII-pH) live recording, histology, and Evans blue (EB) permeability assay.

Materials and Methods

Thirteen esophagi, collected at a slaughterhouse, were ablated of their sphincters, pinned upright on a support, and placed in a thermostatic hood at 37°C with two infusion tubes and an MII-pH probe inserted in the top end. Three esophagi (histology controls) were only left in the hood for 3.5 h before sampling, while the remaining organs underwent the experimental protocol including saline infusion and recovery recording, and acid solution infusion and recovery recording.

Results

MII-pH analysis highlighted a significantly stronger decrease during acid infusion when compared to saline, but a better post-infusion recovery for saline solution. At the end of the protocol, MII was still statistically lower than baseline. The acid-damaged esophagi significantly absorbed more EB dye, and histology revealed strong mucosal exfoliation.

Conclusion

The proposed model of esophageal acid damage seems to be repeatable, reliable, and achievable using organs collected at the slaughterhouse. MII recording proved to have good sensitivity in detecting mucosal alterations also in ex vivo trials.

Barrier Effect of a New Topical Agent on Damaged Esophageal Mucosa: Experimental Study on an ex vivo Swine Model

PURPOSE

AL2106 is a new medical device based on a mixture of chondroitin sulphate in a xyloglucan and glycerol solution made to maximize its bioadhesive capability to the esophageal mucosa. The aim of the present study was twofold to evaluate the AL2106 protective effect on the esophageal mucosa when exposed to an acidic solution mimicking gastric reflux and to assess the resilience of this effect to saline washing.

MATERIALS AND METHODS

A porcine ex vivo model was used and the effects of the new medical device were compared to a sodium alginate suspension (SAS) already present on the market which was assumed as reference. Mucosal damage was induced in 19 porcine esophagi by perfusion with an acidic solution added with pepsin, and Evans blue dye (EBD) tissue uptake was used as an indicator of mucosal permeability. The EBD penetration, expressed as EBD µg/g of dry tissue, was assessed in specimens of untreated damaged mucosa and in specimens treated with AL2106 or SAS. The same evaluation was carried out after washing with normal saline.

RESULTS

Both topical agents tested significantly reduced the EBD uptake by more than 60% (AL2106 8.4±4.5, SAS 3.6±2.7 vs control 23.2±13.1, p<0.01). The saline washing did not cause any significant reduction in the protective effect of AL2106 (8.6±5.9), while it significantly reduced that of SAS (5.9±4.3, p<0.05).

CONCLUSION

The new AL2106 medical device showed a good barrier effect against a reflux-like damaging solution and preserved this effect after the mucosal washing test, thus suggesting its possible relevance for the treatment of gastroesophageal reflux disease.

Treating brain diseases using systemic parenterally-administered protein therapeutics: Dysfunction of the brain barriers and potential strategies

The parenteral administration of protein therapeutics is increasingly gaining importance for the treatment of human diseases. However, the presence of practically impermeable blood-brain barriers greatly restricts access of such pharmaceutics to the brain. Treating brain disorders with proteins thus remains a great challenge, and the slow clinical translation of these therapeutics may be largely ascribed to the lack of appropriate brain delivery system. Exploring new approaches to deliver proteins to the brain by circumventing physiological barriers is thus of great interest. Moreover, parallel advances in the molecular neurosciences are important for better characterizing blood-brain interfaces, particularly under different pathological conditions (e.g., stroke, multiple sclerosis, Parkinson's disease, and Alzheimer's disease). This review presents the current state of knowledge of the structure and the function of the main physiological barriers of the brain, the mechanisms of transport across these interfaces, as well as alterations to these concomitant with brain disorders. Further, the different strategies to promote protein delivery into the brain are presented, including the use of molecular Trojan horses, the formulation of nanosystems conjugated/loaded with proteins, protein-engineering technologies, the conjugation of proteins to polymers, and the modulation of intercellular junctions. Additionally, therapeutic approaches for brain diseases that do not involve targeting to the brain are presented (i.e., sink and scavenging mechanisms).

Brain injury-induced dysfunction of the blood brain barrier as a risk for dementia

The blood-brain barrier (BBB) is a complex and dynamic physiological interface between brain parenchyma and cerebral vasculature. It is composed of closely interacting cells and signaling molecules that regulate movement of solutes, ions, nutrients, macromolecules, and immune cells into the brain and removal of products of normal and abnormal brain cell metabolism. Dysfunction of multiple components of the BBB occurs in aging, inflammatory diseases, traumatic brain injury (TBI, severe or mild repetitive), and in chronic degenerative dementing disorders for which aging, inflammation, and TBI are considered risk factors. BBB permeability changes after TBI result in leakage of serum proteins, influx of immune cells, perivascular inflammation, as well as impairment of efflux transporter systems and accumulation of aggregation-prone molecules involved in hallmark pathologies of neurodegenerative diseases with dementia. In addition, cerebral vascular dysfunction with persistent alterations in cerebral blood flow and neurovascular coupling contribute to brain ischemia, neuronal degeneration, and synaptic dysfunction. While the idea of TBI as a risk factor for dementia is supported by many shared pathological features, it remains a hypothesis that needs further testing in experimental models and in human studies. The current review focusses on pathological mechanisms shared between TBI and neurodegenerative disorders characterized by accumulation of pathological protein aggregates, such as Alzheimer's disease and chronic traumatic encephalopathy. We discuss critical knowledge gaps in the field that need to be explored to clarify the relationship between TBI and risk for dementia and emphasize the need for longitudinal in vivo studies using imaging and biomarkers of BBB dysfunction in people with single or multiple TBI.

Cerebral Microvascular Injury: A Potentially Treatable Endophenotype of Traumatic Brain Injury-Induced Neurodegeneration

Traumatic brain injury (TBI) is one the most common human afflictions, contributing to long-term disability in survivors. Emerging data indicate that functional improvement or deterioration can occur years after TBI. In this regard, TBI is recognized as risk factor for late-life neurodegenerative disorders. TBI encompasses a heterogeneous disease process in which diverse injury subtypes and multiple molecular mechanisms overlap. To develop precision medicine approaches where specific pathobiological processes are targeted by mechanistically appropriate therapies, techniques to identify and measure these subtypes are needed. Traumatic microvascular injury is a common but relatively understudied TBI endophenotype. In this review, we describe evidence of microvascular dysfunction in human and animal TBI, explore the role of vascular dysfunction in neurodegenerative disease, and discuss potential opportunities for vascular-directed therapies in ameliorating TBI-related neurodegeneration. We discuss the therapeutic potential of vascular-directed therapies in TBI and the use and limitations of preclinical models to explore these therapies.

The effects of rhEPO intervention for perinatal intrauterine herpes virus infection on preventing brain injury in preterm infants

The ability of recombinant human erythropoietin (rhEPO) to protect preterm infants against perinatal intrauterine herpes virus infection-induced brain injury was studied. In total, 120 women infected with perinatal intrauterine herpes virus were randomized into four groups: A, B, C and D, and were given 1,500 IU (mother, pre-partum), 3,000 IU (mother, pre-partum), 250 IU/kg (infant, post-natal), and no rhEPO, respectively. Hemoglobin (Hb), reticulocyte (Ret), hematocrit (Hct), neuron specific enolase (NSE), myelin basic protein (MBP), and S100 protein B (S100B) levels were measured immediately (T₀) and at 1 week (T₁), 2 weeks (T₂), and 4 weeks (T₃) post-delivery. Linear regression analysis was performed to analyze inter-indicator correlation, and ROC risk models were established to determine the predictive value of Hb, Ret and Hct for brain injury immediately after delivery. The brain injury incidence rate of group A (10%) was significantly lower than group D (33.3%) and group B (6.7%) significantly lower than groups C (26.7%) and D. At T₀, Hb, Ret and Hct in groups A and B were significantly higher than in group C and D, while from T₁ to T₃, groups A, B and C showed significantly higher values than group D. NSE, MBP and S100B showed an inverse trend, with groups A and B lower at T₀ and groups A, B and C lower from T₁-T₃. Hb and NSE, MBP and S100B were negatively correlated, while no correlation was found between Ret and NSE, MBP and S100B. Finally, Hct and NSE, MBP and S100B were negatively correlated. The optimal cut-off values for Hb and Hct for brain injury diagnosis immediately post-partum were 170 g/l (sensitivity 99%, specificity 95.7%) and 28.5% (sensitivity 79.4%, specificity 100%), respectively. Ret did not show predictive value. In conclusion, pre-partum rhEPO treatment showed greater protective effects than post-natal administration, and this may be the regulation of Hb and Hct levels in post-natal preterm infants. In addition, a dose-dependent effect was displayed.

Biofluid Proteomics and Biomarkers in Traumatic Brain Injury

Traumatic brain injury (TBI) is an injury to the brain caused by an external mechanical force, affecting millions of people worldwide. The disease course and prognosis are often unpredictable, and it can be challenging to determine an early diagnosis in case of mild injury as well as to accurately phenotype the injury. There is currently no cure for TBI-drugs having failed repeatedly in clinical trials-but an intense effort has been put to identify effective neuroprotective treatment. The detection of novel biomarkers, to understand more of the disease mechanism, facilitates early diagnosis, predicts disease progression, and develops molecularly targeted therapies that would be of high clinical interest. Over the last decade, there has been an increasing effort and initiative toward finding TBI-specific biomarker candidates. One promising strategy has been to use state-of-the-art neuroproteomics approaches to assess clinical biofluids and compare the cerebrospinal fluid (CSF) and blood proteome between TBI and control patients or between different subgroups of TBI. In this chapter, we summarize and discuss the status of biofluid proteomics in TBI, with a particular focus on the latest findings.