Mast Cells Induce Blood Brain Barrier Damage in SCD by Causing Endoplasmic Reticulum Stress in the Endothelium

Mast cell extracellular trap formation underlies vascular and neural injury and hyperalgesia in sickle cell disease

Sickle cell disease (SCD) is the most common inherited monogenetic disorder. Chronic and acute pain are hallmark features of SCD involving neural and vascular injury and inflammation. Mast cells reside in the vicinity of nerve fibers and vasculature, but how they influence these structures remains unknown. We therefore examined the mechanism of mast cell activation in a sickle microenvironment replete with cell-free heme and inflammation. Mast cells exposed to this environment showed an explosion of nuclear contents with the release of citrullinated histones, suggestive of mast cell extracellular trap (MCET) release. MCETs interacted directly with the vasculature and nerve fibers, a cause of vascular and neural injury in sickle cell mice. MCET formation was dependent upon peptidylarginine deiminase 4 (PAD4). Inhibition of PAD4 ameliorated vasoocclusion, chronic and acute hyperalgesia, and inflammation in sickle mice. PAD4 activation may also underlie neutrophil trap formation in SCD, thus providing a novel target to treat the sequelae of vascular and neural injury in SCD.

COVID-19 and Long COVID: Disruption of the Neurovascular Unit, Blood-Brain Barrier, and Tight Junctions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), could affect brain structure and function. SARS-CoV-2 can enter the brain through different routes, including the olfactory, trigeminal, and vagus nerves, and through blood and immunocytes. SARS-CoV-2 may also enter the brain from the peripheral blood through a disrupted blood-brain barrier (BBB). The neurovascular unit in the brain, composed of neurons, astrocytes, endothelial cells, and pericytes, protects brain parenchyma by regulating the entry of substances from the blood. The endothelial cells, pericytes, and astrocytes highly express angiotensin converting enzyme 2 (ACE2), indicating that the BBB can be disturbed by SARS-CoV-2 and lead to derangements of tight junction and adherens junction proteins. This leads to increased BBB permeability, leakage of blood components, and movement of immune cells into the brain parenchyma. SARS-CoV-2 may also cross microvascular endothelial cells through an ACE2 receptor-associated pathway. The exact mechanism of BBB dysregulation in COVID-19/neuro-COVID is not clearly known, nor is the development of long COVID. Various blood biomarkers could indicate disease severity and neurologic complications in COVID-19 and help objectively diagnose those developing long COVID. This review highlights the importance of neurovascular and BBB disruption, as well as some potentially useful biomarkers in COVID-19, and long COVID/neuro-COVID.

Novel insights on the probable mechanism associated with histamine oral model-inducing neuropathological and behavioral toxicity in rats

Histamine (HIS) is an important chemical mediator that causes vasodilation and contributes to anaphylactic reactions. Recently, HIS is an understudied neurotransmitter in the central nervous system, and its potential role in neuroinflammation and neurodegeneration is a critical area of research. So, the study's goal is to investigate the consequences of repeated oral intake of HIS on the rat's brain and explore the mechanistic way of its neurotoxicity. Thirty male rats were divided into three groups (n = 10). The following treatments were administered orally to all rats every day for 14 days. Group (1) was given distilled water, whereas groups (2 & 3) were given HIS at dosage levels 250 and 500 mg/kg body weight (BWT), respectively. Brain tissue samples were collected at 7- and 14-days from the beginning of the experiment. Our results revealed that continuous oral administration of HIS at both doses for 14 days significantly reduced the BWT and induced severe neurobehavioral changes, including depression, dullness, lethargy, tremors, abnormal walking, and loss of spatial learning and memory in rats. In all HIS receiving groups, HPLC data showed a considerable raise in the HIS contents of the brain. Additionally, the daily consumption of HIS causes oxidative stress that is dose- and time-dependent which is characterized by elevation of malondialdehyde levels along with reduction of catalase activity and reduced glutathione levels. The neuropathological lesions were commonly observed in the cerebrum, striatum, and cerebellum and confirmed by the immunohistochemistry staining that demonstrating moderate to strong caspase-3 and inducible nitric oxide synthase expressions in all HIS receiving groups, mainly those receiving 500 mg/kg HIS. NF-κB, TNF-α, and IL-1β gene levels were also upregulated at 7- and 14-days in all HIS groups, particularly in those getting 500 mg/kg. We concluded that ROS-induced apoptosis and inflammation was the essential mechanism involved in HIS-mediated neurobehavioral toxicity and histopathology.

New perspective on mechanism in muscle toxicity of ochratoxin A: Model of juvenile grass carp (Ctenopharyngodon idella)

Ochratoxin A (OTA) is a common fungal toxin that pollutes raw materials of aquatic feeds (such as corn, soybean meal, and wheat). This study explored the effects of OTA through diet on muscle toxicity in juvenile grass carp (Ctenopharyngodon idella). The following results were obtained for the muscle. (1) With an increase in dietary OTA, the residue of OTA in muscle increased, muscle fiber diameter and density decreased, and even muscle fiber breakage. (2) OTA caused oxidative stress by downregulating GPx1 (a, b) and Trx via inhibited the PGC1-α/Nrf2 signaling pathway. (3) OTA exacerbated endoplasmic reticulum stress in the muscle by causing endoplasmic reticulum expansion (results of transmission electron microscopy) and upregulating the expression of GRP78, eIF2α, ATF6, PERK, and CHOP. (4) OTA reduced muscle fiber diameter by inhibiting protein synthesis (AKT, TOR, and S6K1) and promoting the mRNA expression of protein degradation-related genes (MURF1, MAFBX, and FoxO3a), as well as by reducing AKT and promoting the immunofluorescence expression of FoxO3. (5) OTA inhibits collagen deposition by downregulating TGF-β1, TGF-βR1, Smad2, Smad3, Smad4, CTGF, TIMP, PHD, and LOX mRNA expressions as well as the CTGF immunofluorescence expression. Moreover, based on the GSH and collagen content contents, the upper safe dose for OTA-induced toxicity was 963.6 and 1129.6 μg/kg diet, respectively. Using the example of OTA, our research has provided new insights that raise concerns about the quality of aquatic products by exploring muscle toxicity caused by mycotoxins.

IL-1β-pretreated bone mesenchymal stem cell-derived exosomes alleviate septic endoplasmic reticulum stress via regulating SIRT1/ERK pathway

Background

Endoplasmic reticulum (ER) plays a crucial role in the development of organ injury caused by sepsis. Therefore, it is highly important to devise strategies that specially target ER stress for the treatment of sepsis. Previous research has shown that priming chemokines can enhance the therapeutic effects of mesenchymal stem cells (MSCs). In this study, we aimed to investigate the function and mechanism of exosomes derived from MSCs that were pretreated with IL-1β (IB-exos) in the context of septic ER stress.

Methods

Mouse bone MSCs were preconditioned with or without IL-1β and the supernatant was used for exosome extraction. In vitro sepsis cell mode was induced by treating HUVECs with LPS, while in vivo sepsis model was established through cecal ligation and puncture (CLP) operation in mice. Cell viability, apoptosis, motility, and tube formation were assessed using the EDU proliferation assay, flow cytometry analysis, migration assay, and tube formation assay, respectively. The molecular mechanism was investigated using ELISA, qRT-PCR, Western blot, and immunofluorescence staining.

Results

Pretreatment with IL-1β enhanced the positive impact of MSC-exos on the viability, apoptosis, motility, and tube formation ability of HUVECs. The administration of LPS or CLP increased ER stress response, but this effect was blocked by the treatment of IB-exos. Additionally, IB-exos reversed the inhibitory effects of LPS or CLP on the expression levels of SIRT1 and ERK phosphorylation. Knockdown of SIRT1 counteracted the effects of IB-exos on HUVEC cellular function and ER stress. In a mouse model, the injection of IB-exos mitigated sepsis-induced lung injury by inhibiting ER stress response through the activation of SIRT1.

Conclusion

IB-exos have been found to alleviate sepsis-induced lung injury via inhibiting ER stress through the SIRT1/ERK pathway. These findings indicated that IB-exos could potentially be used as a strategy to mitigate lung injury caused by sepsis.

Peripheral surgery triggers mast cells activation: Focusing on neuroinflammation

Peripheral surgery can lead to a systemic aseptic inflammatory response comprising several mediators aiming at restoring tissue homeostasis. It induces inflammatory mechanisms through neuroimmune interaction between the periphery and to brain which also plays a critical role in causing cognitive impairments. Accumulating scientific evidence revealed that acute neuroinflammation of the brain triggered by peripheral surgery that causes peripheral inflammation leads to transmitting signals into the brain through immune cells. Mast cells (MCs) play an important role in the acute neuroinflammation induced by peripheral surgical trauma. After peripheral surgery, brain-resident MCs can be rapidly activated followed by releasing histamine, tryptase, and other inflammatory mediators. These mediators then interact with other immune cells in the peripheral and amplify the signal into the brain by disrupting BBB and activating principle innate immune cells of brain including microglia, astrocytes, and vascular endothelial cells, which release abundant inflammatory mediators and in turn accelerate the activation of brain MCs, amplify the cascade effect of neuroinflammatory response. Surgical stress may induce HPA axis activation by releasing corticotropin-releasing hormone (CRH) subsequently influence the activation of brain MCs, thus resulting in impaired synaptic plasticity. Herein, we discuss the better understating of MCs mediated neuroinflammation mechanisms after peripheral surgery and potential therapeutic targets for controlling inflammatory cascades.

In Humanized Sickle Cell Mice, Imatinib Protects Against Sickle Cell-Related Injury

Drug repurposing is a valuable strategy for rare diseases. Sickle cell disease (SCD) is a rare hereditary hemolytic anemia accompanied by acute and chronic painful episodes, most often in the context of vaso-occlusive crisis (VOC). Although progress in the knowledge of pathophysiology of SCD have allowed the development of new therapeutic options, a large fraction of patients still exhibits unmet therapeutic needs, with persistence of VOCs and chronic disease progression. Here, we show that imatinib, an oral tyrosine kinase inhibitor developed for the treatment of chronic myelogenous leukemia, acts as multimodal therapy targeting signal transduction pathways involved in the pathogenesis of both anemia and inflammatory vasculopathy of humanized murine model for SCD. In addition, imatinib inhibits the platelet-derived growth factor-B-dependent pathway, interfering with the profibrotic response to hypoxia/reperfusion injury, used to mimic acute VOCs. Our data indicate that imatinib might be considered as possible new therapeutic tool for chronic treatment of SCD.

Mast cells inhibit colorectal cancer development by inducing ER stress through secreting Cystatin C

Mast cells (MCs) are abundantly distributed in the human intestinal mucosa and submucosa. However, their roles and mechanisms in the development of colorectal cancer (CRC) are still unclear. In the present research, we found that the infiltration density of MCs in CRC tissues was positively correlated with improved patients' prognoses. Moreover, MCs suppressed the growth and induced the apoptosis of CRC cells in vitro and in vivo but had no effect on normal colonic epithelial cells. The present study revealed that MCs specifically induced endoplasmic reticulum stress (ERS) and activated the unfolded protein response (UPR) in CRC cells but not in normal cells, which led to the suppression of CRC development in vivo. Furthermore, we found that the secreted Cystatin C protein was the key factor for the MC-induced ERS in CRC cells. This work is of significance for uncovering the antitumor function of MCs in CRC progression and identifying the potential of CRC to respond to MC-targeted immunotherapy.

Brain Pericytes Acquire Stemness via the Nrf2-Dependent Antioxidant System

Pericytes (PCs) are a mural support cell population elongated at intervals along the walls of capillaries. Recent studies reported that PCs are multipotent cells that are activated in response to tissue injury and contribute to the regenerative process. Using a C.B-17 mouse model of ischemic stroke, it has been proposed that normal brain pericytes (nPCs) are converted to ischemic pericytes (iPCs), some of which function as multipotent stem cells. Furthermore, oxygen-glucose deprivation (OGD) promoted mesenchymal-epithelial transition in nPCs; however, nestin was not induced under OGD conditions. Therefore, further studies are needed to elucidate the PC reprogramming phenomenon. We herein isolated nPCs from the cortex of C.B-17 mice, and compared the traits of iPCs and nPCs. The results obtained showed that nPCs and iPCs shared common pericytic markers. Furthermore, intercellular levels of reactive oxygen species and the nuclear accumulation of nuclear factor erythroid-2-related factor 2 (Nrf2), a key player in antioxidant defenses, were higher in iPCs than in nPCs. OGD/reoxygenation and a treatment with tBHQ, an Nrf2 inducer, increased nestin levels in nPCs. Moreover, epithelial marker levels, including nestin, Sox2, and CDH1 (E-cadherin) mRNAs, were elevated in Nrf2-overexpressing PCs, which formed neurosphere-like cell clusters that differentiated into Tuj1-positive neurons. The present results demonstrate that oxidative stress and Nrf2 are required for the generation of stem cells after stroke and will contribute to the development of novel therapeutic strategies for ischemic stroke.

Salubrinal induces fetal hemoglobin expression via the stress-signaling pathway in human sickle erythroid progenitors and sickle cell disease mice

Sickle cell disease (SCD) is an inherited blood disorder caused by a mutation in the HBB gene leading to hemoglobin S production and polymerization under hypoxia conditions leading to vaso-occlusion, chronic hemolysis, and progressive organ damage. This disease affects ~100,000 people in the United States and millions worldwide. An effective therapy for SCD is fetal hemoglobin (HbF) induction by pharmacologic agents such as hydroxyurea, the only Food and Drug Administration-approved drug for this purpose. Therefore, the goal of our study was to determine whether salubrinal (SAL), a selective protein phosphatase 1 inhibitor, induces HbF expression through the stress-signaling pathway by activation of p-eIF2α and ATF4 trans-activation in the γ-globin gene promoter. Sickle erythroid progenitors treated with 24μM SAL increased F-cells levels 1.4-fold (p = 0.021) and produced an 80% decrease in reactive oxygen species. Western blot analysis showed SAL enhanced HbF protein by 1.6-fold (p = 0.0441), along with dose-dependent increases of p-eIF2α and ATF4 levels. Subsequent treatment of SCD mice by a single intraperitoneal injection of SAL (5mg/kg) produced peak plasma concentrations at 6 hours. Chronic treatments of SCD mice with SAL mediated a 2.3-fold increase in F-cells (p = 0.0013) and decreased sickle erythrocytes supporting in vivo HbF induction.

Endoplasmic Reticulum Stress in Chemotherapy-Induced Peripheral Neuropathy: Emerging Role of Phytochemicals

Chemotherapy-induced peripheral neuropathy (CIPN) is a significant dose-limiting long-term sequela in cancer patients undergoing treatment, often leading to discontinuation of treatment. No established therapy exists to prevent and/or ameliorate CIPN. Reactive oxygen species (ROS) and mitochondrial dysregulation have been proposed to underlie the pathobiology of CIPN. However, interventions to prevent and treat CIPN are largely ineffective. Additional factors and mechanism-based targets need to be identified to develop novel strategies to target CIPN. The role of oxidative stress appears to be central, but the contribution of endoplasmic reticulum (ER) stress remains under-examined in the pathobiology of CIPN. This review describes the significance of ER stress and its contribution to CIPN, the protective role of herbal agents in countering ER stress in nervous system-associated disorders, and their possible repurposing for preventing CIPN.

P2X Receptor-Dependent Modulation of Mast Cell and Glial Cell Activities in Neuroinflammation

Localisation of mast cells (MCs) at the abluminal side of blood vessels in the brain favours their interaction with glial cells, neurons, and endothelial cells, resulting in the activation of these cells and the release of pro-inflammatory mediators. In turn, stimulation of glial cells, such as microglia, astrocytes, and oligodendrocytes may result in the modulation of MC activities. MCs, microglia, astrocytes, and oligodendrocytes all express P2X receptors (P2XRs) family members that are selectively engaged by ATP. As increased concentrations of extracellular adenosine 5′-triphosphate (ATP) are present in the brain in neuropathological conditions, P2XR activation in MCs and glial cells contributes to the control of their communication and amplification of the inflammatory response. In this review we discuss P2XR-mediated MC activation, its bi-directional effect on microglia, astrocytes and oligodendrocytes and role in neuroinflammation.

Pain in sickle cell disease: current and potential translational therapies

Pain is a major comorbidity of sickle cell disease (SCD). Patients with SCD may suffer from both acute and chronic pain. Acute pain is caused by recurrent and unpredictable episodes of vaso-occlusive crises (VOC), whereas the exact etiology of chronic pain is still unknown. Opioids are the mainstay for pain treatment, but the opioid epidemic has significantly altered access to prescription opioids and has brought concerns over their long-term use into the forefront, which have negatively impacted the treatment of sickle pain. Opioids remain potent analgesics but growing opioid-phobia has led to the realization of an unmet need to develop nonopioid therapies that can provide relief for severe sickle pain. This realization has contributed to the approval of 3 different drugs by the Food and Drug Administration (FDA) for the treatment of SCD, particularly to reduce VOC and/or have an impact on the pathobiology of SCD. In this review, we outline the challenges and need for validation of side-effects of opioids and provide an update on the development of mechanism-based translational therapies, specifically targeting pain in SCD.

P-selectin-deficient mice to study pathophysiology of sickle cell disease

P-selectin–deficient SCD mice are protected from lung vaso-occlusion. P-selectin–deficient SCD mice will be useful in assessing the benefits of anti–P-selectin therapy in diverse complications of SCD.

Microbiota-Host Immunity Communication in Neurodegenerative Disorders: Bioengineering Challenges for In Vitro Modeling

Human microbiota communicates with its host by secreting signaling metabolites, enzymes, or structural components. Its homeostasis strongly influences the modulation of human tissue barriers and immune system. Dysbiosis-induced peripheral immunity response can propagate bacterial and pro-inflammatory signals to the whole body, including the brain. This immune-mediated communication may contribute to several neurodegenerative disorders, as Alzheimer's disease. In fact, neurodegeneration is associated with dysbiosis and neuroinflammation. The interplay between the microbial communities and the brain is complex and bidirectional, and a great deal of interest is emerging to define the exact mechanisms. This review focuses on microbiota-immunity-central nervous system (CNS) communication and shows how gut and oral microbiota populations trigger immune cells, propagating inflammation from the periphery to the cerebral parenchyma, thus contributing to the onset and progression of neurodegeneration. Moreover, an overview of the technological challenges with in vitro modeling of the microbiota-immunity-CNS axis, offering interesting technological hints about the most advanced solutions and current technologies is provided.

Stroke in SARS-CoV-2 Infection: A Pictorial Overview of the Pathoetiology

Since the early days of the pandemic, there have been several reports of cerebrovascular complications during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Numerous studies proposed a role for SARS-CoV-2 in igniting stroke. In this review, we focused on the pathoetiology of stroke among the infected patients. We pictured the results of the SARS-CoV-2 invasion to the central nervous system (CNS) via neuronal and hematogenous routes, in addition to viral infection in peripheral tissues with extensive crosstalk with the CNS. SARS-CoV-2 infection results in pro-inflammatory cytokine and chemokine release and activation of the immune system, COVID-19-associated coagulopathy, endotheliitis and vasculitis, hypoxia, imbalance in the renin-angiotensin system, and cardiovascular complications that all may lead to the incidence of stroke. Critically ill patients, those with pre-existing comorbidities and patients taking certain medications, such as drugs with elevated risk for arrhythmia or thrombophilia, are more susceptible to a stroke after SARS-CoV-2 infection. By providing a pictorial narrative review, we illustrated these associations in detail to broaden the scope of our understanding of stroke in SARS-CoV-2-infected patients. We also discussed the role of antiplatelets and anticoagulants for stroke prevention and the need for a personalized approach among patients with SARS-CoV-2 infection.

Protective effect of syringic acid via restoring cells biomechanics and organelle structure in human lens epithelial cells

We have previously reported that syringic acid (SA) extracted from D. aurantiacum var. denneanum (kerr) may be used to prevent diabetic cataract (DC). However, the underlying mechanisms through which SA prevents DC in human lens epithelial cells (HLECs) remained unclear. In the present study, we employed single-molecule optics technologies, including transmission electron microscopy (TEM), atomic force microscopy (AFM), laser scanning confocal microscopy (LSCM) and Raman spectroscopy, to monitor the effect of SA on HLECs biomechanics and organelle structure in real-time. TEM suggested that SA improved the ultrastructure of HLECs with regard to nuclear chromatin condensation and reducing mitochondrial swelling and degeneration, which may aid in the maintenance of HLECs integrity in the presence of glucose. AFM revealed a reduced surface roughness and stiffness following SA treatment, suggesting an improved viscoelasticity of HELCs. Raman spectrometry and LSCM further revealed that these changes were related to a modification of cell liquidity and cytoskeletal structure by SA. Taken together, these results provide insights into the effects of SA on the biomechanics of HLECs and further strengthen the evidence for its potential use as a novel therapeutic strategy for DC prevention.

Microfluidics in Sickle Cell Disease Research: State of the Art and a Perspective Beyond the Flow Problem

Sickle cell disease (SCD) is the monogenic hemoglobinopathy where mutated sickle hemoglobin molecules polymerize to form long fibers under deoxygenated state and deform red blood cells (RBCs) into predominantly sickle form. Sickled RBCs stick to the vascular bed and obstruct blood flow in extreme conditions, leading to acute painful vaso-occlusion crises (VOCs) – the leading cause of mortality in SCD. Being a blood disorder of deformed RBCs, SCD manifests a wide-range of organ-specific clinical complications of life (in addition to chronic pain) such as stroke, acute chest syndrome (ACS) and pulmonary hypertension in the lung, nephropathy, auto-splenectomy, and splenomegaly, hand-foot syndrome, leg ulcer, stress erythropoiesis, osteonecrosis and osteoporosis. The physiological inception for VOC was initially thought to be only a fluid flow problem in microvascular space originated from increased viscosity due to aggregates of sickled RBCs; however, over the last three decades, multiple molecular and cellular mechanisms have been identified that aid the VOC in vivo. Activation of adhesion molecules in vascular endothelium and on RBC membranes, activated neutrophils and platelets, increased viscosity of the blood, and fluid physics driving sickled and deformed RBCs to the vascular wall (known as margination of flow) – all of these come together to orchestrate VOC. Microfluidic technology in sickle research was primarily adopted to benefit from mimicking the microvascular network to observe RBC flow under low oxygen conditions as models of VOC. However, over the last decade, microfluidics has evolved as a valuable tool to extract biophysical characteristics of sickle red cells, measure deformability of sickle red cells under simulated oxygen gradient and shear, drug testing, in vitro models of intercellular interaction on endothelialized or adhesion molecule-functionalized channels to understand adhesion in sickle microenvironment, characterizing biomechanics and microrheology, biomarker identification, and last but not least, for developing point-of-care diagnostic technologies for low resource setting. Several of these platforms have already demonstrated true potential to be translated from bench to bedside. Emerging microfluidics-based technologies for studying heterotypic cell–cell interactions, organ-on-chip application and drug dosage screening can be employed to sickle research field due to their wide-ranging advantages.

Noncontrast assessment of blood-brain barrier permeability to water: Shorter acquisition, test-retest reproducibility, and comparison with contrast-based method

PURPOSE

Assessment of the blood-brain barrier (BBB) permeability without the need for contrast agent is desirable, and the ability to measure the permeability to small molecules such as water may further increase the sensitivity in detecting diseases. This study proposed a time-efficient, noncontrast method to measure BBB permeability to water, evaluated its test-retest reproducibility, and compared it with a contrast agent-based method.

METHODS

A single-delay water extraction with phase-contrast arterial spin tagging (WEPCAST) method was devised in which spatial profile of the signal along the superior sagittal sinus was used to estimate bolus arrival time, and the WEPCAST signal at the corresponding location was used to compute water extraction fraction, which was combined with global cerebral blood flow to estimate BBB permeability surface area product to water. The reliability of WEPCAST sequence was examined in terms of intrasession, intersession, and inter-vendor (Philips [Ingenia, Best, the Netherlands] and Siemens [Prisma, Erlangen, Germany]) reproducibility. Finally, we compared this new technique to a contrast agent-based method.

RESULTS

Single-delay WEPCAST reduced the scan duration from approximately 20 min to 5 min. Extract fraction values estimated from single-delay WEPCAST showed good consistency with the multi-delay method (R = 0.82, P = .004). Group-averaged permeability surface area product values were found to be 137.5 ± 9.3 mL/100 g/min. Intrasession, intersession, and inter-vendor coefficient of variation of the permeability surface area product values were 6.6 ± 4.5%, 6.9 ± 3.7%, and 8.9 ± 3.0%, respectively. Finally, permeability surface area product obtained from WEPCAST MRI showed a significant correlation with that from the contrast-based method (R = .73, P = .02).

CONCLUSION

Single-delay WEPCAST MRI can measure BBB permeability to water within 5 min with an intrasession, intersession, and inter-vendor test-retest reproducibility of 6% to 9%. This method may provide a useful marker of BBB breakdown in clinical studies.

Considerations for Cannabis Use to Treat Pain in Sickle Cell Disease

Pain in Sickle Cell Disease (SCD) is a major comorbidity and unique with acute pain due to recurrent and episodic vaso-occlusive crises as well as chronic pain, which can span an individual's entire life. Opioids are the mainstay treatment for pain in SCD. Due to recent health crises raised by adverse effects including deaths from opioid use, pain management in SCD is adversely affected. Cannabis and its products are most widely used for pain in multiple conditions and also by patients with SCD on their own. With the availability of "Medical Cannabis" and approval to use cannabis as medicine across majority of States in the United States as well as over-the-counter preparations, cannabis products are being used increasingly for SCD. The reliability of many of these products remains questionable, which poses a major health risk to the vulnerable individuals seeking pain relief. Therefore, this review provides up to date insights into available categories of cannabis-based treatment strategies, their mechanism of action and pre-clinical and clinical outcomes in SCD. It provides evidence for the benefits and risks of cannabis use in SCD and cautions about the unreliable and unvalidated products that may be adulterated with life-threatening non-cannabis compounds.

Crosstalk between Inflammation and the BBB in Stroke

The blood-brain barrier (BBB), which is located at the interface between the central nervous system (CNS) and the circulatory system, is instrumental in establishing and maintaining the microenvironmental homeostasis of the CNS. BBB disruption following stroke promotes inflammation by enabling leukocytes, T cells and other immune cells to migrate via both the paracellular and transcellular routes across the BBB and to infiltrate the CNS parenchyma. Leukocytes promote the removal of necrotic tissues and neuronal recovery, but they also aggravate BBB injury and exacerbate stroke outcomes, especially after late reperfusion. Moreover, the swelling of astrocyte endfeet is thought to contribute to the ‘no-reflow’ phenomenon observed after cerebral ischemia, that is, blood flow cannot return to capillaries after recanalization of large blood vessels. Pericyte recruitment and subsequent coverage of endothelial cells (ECs) alleviate BBB disruption, which causes the transmigration of inflammatory cells across the BBB to be a dynamic process. Furthermore, interneurons and perivascular microglia also make contacts with ECs, astrocytes and pericytes to establish the neurovascular unit. BBB-derived factors after cerebral ischemia triggered microglial activation. During the later stage of injury, microglia remain associated with brain ECs and contribute to repair mechanisms, including postinjury angiogenesis, by acquiring a protective phenotype, which possibly occurs through the release of microglia-derived soluble factors. Taken together, we reviewed dynamic and bidirectional crosstalk between inflammation and the BBB during stroke and revealed targeted interventions based on the crosstalk between inflammation and the BBB, which will provide novel insights for developing new therapeutic strategies.

Astragaloside IV Reduces Cerebral Ischemia/Reperfusion-Induced Blood-Brain Barrier Permeability in Rats by Inhibiting ER Stress-Mediated Apoptosis

Background

Previous studies proved that AS-IV could prevent blood-brain barrier (BBB) against an increase in permeability. However, its underlying molecular mechanism has not been enlightened yet. The aim of the study is to reveal the potential protective mechanism of astragaloside IV (AS-IV) on the blood-brain barrier after ischemia-reperfusion.

Methods

In vivo, AS-IV neurological protection was measured by Long's five-point scale and 2,3,5-triphenyltetrazolium chloride staining. AS-IV protection for BBB was observed by Evans blue extravasation technique. Endoplasmic reticulum stress and apoptosis-related protein levels were measured by western blot with AS-IV intervention. In vitro, cell apoptosis was analyzed by western blot and flow cytometry.Endoplasmic reticulum stress-related protein levels were quantified through western blot.

Results

AS-IV treatment could decrease the infarct size in rats' brain and protect the BBB against Evans blue permeating through brain, after ischemia/reperfusion, significantly. Further, ischemia/reperfusion or oxygen-glucose deprivation/reperfusion was found to have an increase in endothelial cell apoptosis proteins, such as Bax, Bcl-2, and caspase-3, and endoplasmic reticulum stress-associated proteins, such as phosphorylated PERK and eIF2α, Bip, and CHOP, which were attenuated by AS-IV treatment.

Conclusions

AS-IV can effectively protect the blood-brain barrier and reduce the area of cerebral infarction via inhibiting endoplasmic reticulum stress-mediated apoptosis in endothelial cells.

The multifaceted role of ischemia/reperfusion in sickle cell anemia

Sickle cell anemia is a unique disease dominated by hemolytic anemia and vaso-occlusive events. The latter trigger a version of ischemia/reperfusion (I/R) pathobiology that is singular in its origin, cyclicity, complexity, instability, perpetuity, and breadth of clinical consequences. Specific clinical features are probably attributable to local I/R injury (e.g., stroke syndromes) or remote organ injury (e.g., acute chest syndrome) or the systematization of inflammation (e.g., multifocal arteriopathy). Indeed, by fashioning an underlying template of endothelial dysfunction and vulnerability, the robust inflammatory systematization no doubt contributes to all sickle pathology. In this Review, we highlight I/R-targeting therapeutics shown to improve microvascular blood flow in sickle transgenic mice undergoing I/R, and we suggest how such insights might be translated into human therapeutic strategies.

Age-dependent characterization of carotid and cerebral artery geometries in a transgenic mouse model of sickle cell anemia using ultrasound and microcomputed tomography

To define morphological changes in carotid and cerebral arteries in sickle cell transgenic mice (SS) as they age, a combination of ultrasound and microcomputed tomography of plastinated arteries was used to quantify arterial dimensions and changes in mice 4, 12, and 24 weeks of age. 12-week SS mice had significantly larger common carotid artery diameters than AS mice, which continued through to the extracranial and intracranial portions of the internal carotid artery (ICA). There were also side specific differences in diameters between the left and right vessels. Significant ICA tapering along its length occurred by 12- and 24-weeks in SS mice, decreasing by as much as 70%. Significant narrowing along the length was also measured in SS anterior cerebral arteries at 12- and 24-weeks, but not AS. Collectively, these findings indicate that sickle cell anemia induces arterial remodeling in 12- and 24-weeks old mice. Catalog of measurements are also provided for the common carotid, internal carotid, anterior cerebral, and middle cerebral arteries for AS and SS genotypes, as a reference for other investigators using mathematical and computational models of age-dependent arterial complications caused by sickle cell anemia.

Redox signalling and regulation of the blood-brain barrier

Neurological disorders are associated with increased oxidative stress. Reactive oxidants damage tissue and promote cell death, but it is apparent that oxidants can have more subtle effects on cell function through the modulation of redox-sensitive signalling pathways. Cells of the blood-brain barrier regulate the brain microenvironment but become dysfunctional during neurological disease. The blood-brain barrier is maintained by many cell types, and is modulated by redox-sensitive pathways, ranging from the cytoskeletal elements responsible for establishing a barrier, to growth factor and cytokine signalling pathways that influence neurovascular cells. During neurological disease, blood-brain barrier cells are exposed to exogenously generated oxidants from immune cells, as well as increasing endogenously oxidant production. These oxidants impair the function of the blood-brain barrier, leading to increased leakage and reduced blood flow. Reducing the impact of oxidants on the function of blood-brain barrier cells may provide new strategies for delaying the progression of neurological disease.

Innate immune cells, major protagonists of sickle cell disease pathophysiology

Sickle cell disease (SCD), considered the most common monogenic disease worldwide, is a severe hemoglobin disorder. Although the genetic and molecular bases have long been characterized, the pathophysiology remains incompletely elucidated and therapeutic options are limited. It has been increasingly suggested that innate immune cells, including monocytes, neutrophils, invariant natural killer T cells, platelets and mast cells, have a role in promoting inflammation, adhesion and pain in SCD. Here we provide a thorough review of the involvement of these novel, major protagonists in SCD pathophysiology, highlighting recent evidence for innovative therapeutic perspectives.

Calming Down Mast Cells with Ketotifen: A Potential Strategy for Multiple Sclerosis Therapy?

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) characterized by extensive inflammation, demyelination, axonal loss and gliosis. Evidence indicates that mast cells contribute to immunopathogenesis of both MS and experimental autoimmune encephalomyelitis (EAE), which is the most employed animal model to study this disease. Considering the inflammatory potential of mast cells, their presence at the CNS and their stabilization by certain drugs, we investigated the effect of ketotifen fumarate (Ket) on EAE development. EAE was induced in C57BL/6 mice by immunization with MOG35-55 and the animals were injected daily with Ket from the seventh to the 17th day after disease induction. This early intervention with Ket significantly reduced disease prevalence and severity. The protective effect was concomitant with less NLRP3 inflammasome activation, rebalanced oxidative stress and also reduced T cell infiltration at the CNS. Even though Ket administration did not alter mast cell percentage at the CNS, it decreased the local CPA3 and CMA1 mRNA expression that are enzymes typically produced by these cells. Evaluation of the CNS-barrier permeability indicated that Ket clearly restored the permeability levels of this barrier. Ket also triggered an evident lymphadenomegaly due to accumulation of T cells that produced higher levels of encephalitogenic cytokines in response to in vitro stimulation with MOG. Altogether these findings reinforce the concept that mast cells are particularly relevant in MS immunopathogenesis and that Ket, a known stabilizer of their activity, has the potential to be used in MS control.

Phenazine methosulphate-treated red blood cells activate NF-κB and upregulate endothelial ICAM-1 expression

Although enhanced Red Blood Cell (RBC) - Endothelial Cell (EC) interaction, as well as RBC induced EC activation, have been extensively studied in several RBC-linked pathologies, the specific individual effects of oxidatively modified RBC on EC activation has not yet been documented. However, increasing evidence in both experimental and clinical studies suggests that oxidatively modified RBC could be considered potential pathogenic determinants in several acute and chronic diseases displaying systemic oxidative stress. Therefore, the present study aimed to explore the specific effects of oxidized RBC interaction with endothelial cells on intracellular signaling pathways that promote EC activation. RBC were exposed to oxidative stress induced by phenazine methosulphate (PMS). It is shown that the interaction of oxidatively modified RBC with cultured human umbilical vein endothelial cells (HUVEC) results in: a) EC activation as indicated by the increased surface expression of intercellular adhesion molecule -1 (ICAM-1); b) the activation of transcription factor NF-κB, an indicator of cellular oxidant stress. These results emphasize the specific contribution of oxidatively modified RBC interaction to EC activation and their possible pathological role in vascular diseases and oxidative stress.