Multicellular Crosstalk Between Exosomes and the Neurovascular Unit After Cerebral Ischemia. Therapeutic Implications

Restorative strategies after stroke are focused on the remodeling of cerebral endothelial cells and brain parenchymal cells. The latter, i.e., neurons, neural precursor cells and glial cells, synergistically interact with endothelial cells in the ischemic brain, providing a neurovascular unit (NVU) remodeling that can be used as target for stroke therapies. Intercellular communication and signaling within the NVU, the multicellular brain-vessel-blood interface, including its highly selective blood-brain barrier, are fundamental to the central nervous system homeostasis and function. Emerging research designates cell-derived extracellular vesicles and especially the nano-sized exosomes, as a complex mean of cell-to-cell communication, with potential use for clinical applications. Through their richness in active molecules and biological information (e.g., proteins, lipids, genetic material), exosomes contribute to intercellular signaling, a condition particularly required in the central nervous system. Cerebral endothelial cells, perivascular astrocytes, pericytes, microglia and neurons, all part of the NVU, have been shown to release and uptake exosomes. Also, exosomes cross the blood-brain and blood-cerebrospinal fluid barriers, allowing communication between periphery and brain, in normal and disease conditions. As such exosomes might be a powerful diagnostic tool and a promising therapeutic shuttle of natural nanoparticles, but also a means of disease spreading (e.g., immune system modulation, pro-inflammatory action, propagation of neurodegenerative factors). This review highlights the importance of exosomes in mediating the intercellular crosstalk within the NVU and reveals the restorative therapeutic potential of exosomes harvested from multipotent mesenchymal stem cells in ischemic stroke, a frequent neurologic condition lacking an efficient therapy

Vasculature Remodeling in a Rat Model of Cerebral Ischemia. The Fate of the BrdU-Labeled Cells Prior to Stroke

Despite the clinical significance of post-stroke angiogenesis, a detailed phenotypic analysis of pre-stroke vascular remodeling and post-stroke angiogenesis had not yet been done in a model of focal ischemia. In this study, using BrdU-labeling of proliferating cells and immunofluorescence of pre- and post-stroke rats, we found that, (i) BrdU administered before stroke was incorporated preferentially into the nuclei of endothelial cells lining the lumen of existing blood vessels and newly born neurons in the dentate gyrus but not in the subventricular zone or proliferating microglia, (ii) BrdU injection prior to stroke led to the patchy distribution of the newly incorporated endothelial cells into existing blood vessels of the adult rat brain, (iii) BrdU injection prior to stroke specifically labeled neuronal precursors cells in a region of soft tissue beyond the inhibitory scar, which seems to be permissive to regenerative events, (iv) BrdU injection after stroke led to labeling of endothelial cells crossing or detaching from the disintegrating blood vessels and their incorporation into new blood vessels in the stroke region, scar tissue and the region beyond, (v) BrdU injection after stroke led to specific incorporation of BrdU-positive nuclei into the “pinwheel” architecture of the ventricular epithelium, (vi) blood vessels in remote areas relative to the infarct core and in the contralateral non-lesioned cortex, showed co-labeled BrdU/RECA+ endothelial cells shortly after the BrdU injection, which strongly suggests a bone marrow origin of the endothelial cells. In the damaged cortex, a BrdU/prolyl 4-hydroxylase beta double labeling in the close proximity to collagen IV-labeled basement membrane, suggests that, in addition to bone marrow derived endothelial cells, the disintegrating vascular wall itself could also be a source of proliferating endothelial cells, (vii) By day 28 after stroke, new blood vessels were observed in the perilesional area and the scar tissue region, which is generally considered to be resistant to regenerative events. Finally, (viii) vigorous angiogenesis was also detected in a region of soft tissue, also called “islet of regeneration,” located next to the inhibitory scar.Conclusion: BrdU administered prior to, and after stroke, allows to investigate brain vasculature remodeling in the adult brain

The relationship between irritable bowel syndrome and psychiatric disorders: from molecular changes to clinical manifestations

Irritable bowel syndrome (IBS) is a functional syndrome characterized by chronic abdominal pain accompanied by altered bowel habits. Although generally considered a functional disorder, there is now substantial evidence that IBS is associated with a poor quality of life and significant negative impact on work and social domains. Neuroimaging studies documented changes in the prefrontal cortex, ventro-lateral and posterior parietal cortex and thalami, and implicate alteration of brain circuits involved in attention, emotion and pain modulation. Emerging data reveals the interaction between psychiatric disorders including generalized anxiety disorder, panic disorder, major depressive disorder, bipolar disorder, and schizophrenia and IBS, which suggests that this association should not be ignored when developing strategies for screening and treatment. Psychological, social and genetic factors appear to be important in the development of IBS symptomatology through several mechanisms: alteration of HPA axis modulation, enhanced perception of visceral stimuli or psychological vulnerability. Elucidating the molecular mechanisms of IBS with or without psychiatric comorbidities is crucial for elucidating the pathophysiology and for the identification of new therapeutical targets in IBS

The Role of Oxidative Stress and the Effects of Antioxidants on the Incidence of Infectious Complications of Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is characterized by a predominant humoral immune deficiency predisposing the patients to infections. Oxidative stress leads to an increased immunoglobulin k light chain production in B cells and contributes to the antibodies’ deficiency and hypogammaglobulinemia. Aim of the Study. To evaluate the global oxidative status in patients with CLL and to determine whether the administration of antioxidants decreases complications due to infections. Patients and Method. We studied 84 patients with CLL stratified by Binet staging. Free oxygen radicals and antioxidant status were determined by the FORT and FORD test, respectively, at diagnosis and in the presence of infections. The patients were distributed in two groups: group A, treated only with antileukemic treatment, and group B, treated with antileukemic treatment and antioxidants. Results. By FORD and FORT assay, all patients had at diagnosis a low antioxidant capacity, and high levels of hydroperoxides. Infectious complications were more frequent in group A (B/C stages of disease) than in group B. Administrations of antioxidants stimulated the immune response and decreased infectious complications in CLL. Conclusions. Administrations of antioxidants and a healthy life style may improve the quality of life of patients with CLL and reduce the risk of infectious complications

Microglial morphology in the somatosensory cortex across lifespan. A quantitative study

Background: Microglia are long-lived cells that constantly monitor their microenvironment. To accomplish this task, they constantly change their morphology both in the short and long term under physiological conditions. This makes the process of quantifying physiological microglial morphology difficult. Results: By using a semi-manual and a semi-automatic method to assess fine changes in cortical microglia morphology, we were able to quantify microglia changes in number, surveillance and branch tree starting from the fifth postnatal day to 2 years of life. We were able to identify a fluctuating behavior of most analyzed parameters characterized by a rapid cellular maturation, followed by a long period of relative stable morphology during the adult life with a final convergence to an aged phenotype. Detailed cellular arborization analysis revealed age-induced differences in microglia morphology, with mean branch length and the number of terminal processes changing constantly over time. Conclusions: Our study provides insight into microglia morphology changes across lifespan under physiological conditions. We were able to highlight, that due to the dynamic nature of microglia several morphological parameters are needed to establish the physiological state of these cells

Nanodrugs for the treatment of ischemic stroke: A systematic review

Ischemic stroke, a significant neurovascular disorder, currently lacks effective restorative medication. However, recently developed nanomedicines bring renewed promise for alleviating ischemia’s effects and facilitating the healing of neurological and physical functions. The aim of this systematic review was to evaluate the efficacy of nanotherapies in animal models of stroke and their potential impact on future stroke therapies. We also assessed the scientific quality of current research focused on nanoparticle-based treatments for ischemic stroke in animal models. We summarized the effectiveness of nanotherapies in these models, considering multiple factors such as their anti-inflammatory, antioxidant, and angiogenetic properties, as well as their safety and biodistribution. We conclude that the application of nanomedicines may reduce infarct size and improve neurological function post-stroke without causing significant organ toxicity.University of Medicine and Pharmacy of Craiova ; European Social Fun

Long-term treatment with chloroquine increases lifespan in middle-aged male mice possibly via autophagy modulation, proteasome inhibition and glycogen metabolism

Previous studies have shown that the polyamine spermidine increased the maximum life span in C. elegans and the median life span in mice. Since spermidine increases autophagy, we asked if treatment with chloroquine, an inhibitor of autophagy, would shorten the lifespan of mice. Recently, chloroquine has intensively been discussed as a treatment option for COVID-19 patients. To rule out unfavorable long-term effects on longevity, we examined the effect of chronic treatment with chloroquine given in the drinking water on the lifespan and organ pathology of male middle-aged NMRI mice. We report that, surprisingly, daily treatment with chloroquine extended the median life span by 11.4% and the maximum life span of the middle-aged male NMRI mice by 11.8%. Subsequent experiments show that the chloroquine-induced lifespan elevation is associated with dose-dependent increase in LC3B-II, a marker of autophagosomes, in the liver and heart that was confirmed by transmission electron microscopy. Quite intriguingly, chloroquine treatment was also associated with a decrease in glycogenolysis in the liver suggesting a compensatory mechanism to provide energy to the cell. Accumulation of autophagosomes was paralleled by an inhibition of proteasome-dependent proteolysis in the liver and the heart as well as with decreased serum levels of insulin growth factor binding protein-3 (IGFBP3), a protein associated with longevity. We propose that inhibition of proteasome activity in conjunction with an increased number of autophagosomes and decreased levels of IGFBP3 might play a central role in lifespan extension by chloroquine in male NMRI mice.UEFISCDI (EU Horizon 2020 Research and Innovation Programme), Consiliul National al Cercetarii Stiintifice (CNCS), Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii (UEFISCDI

Preconditioned extracellular vesicles from hypoxic microglia reduce poststroke AQP4 depolarization, disturbed cerebrospinal fluid flow, astrogliosis, and neuroinflammation

Background: Stroke stimulates reactive astrogliosis, aquaporin 4 (AQP4) depolarization and neuroinflammation. Preconditioned extracellular vesicles (EVs) from microglia exposed to hypoxia, in turn, reduce poststroke brain injury. Nevertheless, the underlying mechanisms of such effects are elusive, especially with regards to inflammation, AQP4 polarization, and cerebrospinal fluid (CSF) flow. Methods: Primary microglia and astrocytes were exposed to oxygen-glucose deprivation (OGD) injury. For analyzing the role of AQP4 expression patterns under hypoxic conditions, a co-culture model of astrocytes and microglia was established. Further studies applied a stroke model, where some mice also received an intracisternal tracer infusion of rhodamine B. As such, these in vivo studies involved the analysis of AQP4 polarization, CSF flow, astrogliosis, and neuroinflammation as well as ischemia-induced brain injury. Results: Preconditioned EVs decreased periinfarct AQP4 depolarization, brain edema, astrogliosis, and inflammation in stroke mice. Likewise, EVs promoted postischemic CSF flow and cerebral blood perfusion, and neurological recovery. Under in vitro conditions, hypoxia stimulated M2 microglia polarization, whereas EVs augmented M2 microglia polarization and repressed M1 microglia polarization even further. In line with this, astrocytes displayed upregulated AQP4 clustering and proinflammatory cytokine levels when exposed to OGD, which was reversed by preconditioned EVs. Reduced AQP4 depolarization due to EVs, however, was not a consequence of unspecific inflammatory regulation, since LPS-induced inflammation in co-culture models of astrocytes and microglia did not result in altered AQP4 expression patterns in astrocytes. Conclusions: These findings show that hypoxic microglia may participate in protecting against stroke-induced brain damage by regulating poststroke inflammation, astrogliosis, AQP4 depolarization, and CSF flow due to EV release