Neuroinflammation is a complex inflammatory process in the central nervous system, which is sought to play an important defensive role against various pathogens, toxins or factors that induce neurodegeneration. The onset of neurodegenerative diseases and various microbial infections are counted as stimuli that can challenge the host immune system and trigger the development of neuroinflammation. The homeostatic nature of neuroinflammation is essential to maintain the neuroplasticity. Neuroinflammation is regulated by the activity of neuronal, glial, and endothelial cells within the neurovascular unit, which serves as a “platform” for the coordinated action of pro- and anti-inflammatory mechanisms. Production of inflammatory mediators (cytokines, chemokines, reactive oxygen species) by brain resident cells or cells migrating from the peripheral blood, results in the impairment of blood-brain barrier integrity, thereby further affecting the course of local inflammation. In this review, we analyzed the most recent data on the central nervous system inflammation and focused on major mechanisms of neurovascular unit dysfunction caused by neuroinflammation and infections.

Currently, there is a considerable interest to the assessment of blood-brain barrier (BBB) development as a part of cerebral angiogenesis developmental program. Embryonic and adult angiogenesis in the brain is governed by the coordinated activity of endothelial progenitor cells, brain microvascular endothelial cells, and non-endothelial cells contributing to the establishment of the BBB (pericytes, astrocytes, neurons). Metabolic and functional plasticity of endothelial progenitor cells controls their timely recruitment, precise homing to the brain microvessels, and efficient support of brain angiogenesis. Deciphering endothelial progenitor cells physiology would provide novel engineering approaches to establish adequate microfluidically-supported BBB models and brain microphysiological systems for translational studies.

BackgroundLipopolysaccharide (LPS) is one of the main constituents of the cell wall of gram-negative bacteria. As an endotoxin, LPS induces neuroinflammation, which is associated with the blood-brain barrier impairment. Lactate is a metabolite with some significant physiological functions within the neurovascular unit/blood-brain barrier (BBB). Accumulation of extracellular and cerebrospinal fluid lactate is a specific feature of bacterial meningitis. However, the role of lactate production, transport, and sensing by lactate receptors GPR81 in the pathogenesis of bacterial neuroinflammation is still unknown.MethodsIn this study, we analyzed effects of LPS on the expression of GPR81 and MCT-1 and proliferation of cerebral endothelial cells in the BBB model in vitro. We used molecular profiling methods to measure the expression of GPR81, MCT-1, IL-1β, and Ki67 in the cerebral endothelium after treatment with different concentrations of LPS followed by measuring the level of extracellular lactate, transendothelial electric resistance, and permeability of the endothelial cell layer.ResultsOur findings showed that exposure to LPS results in neuroinflammatory changes associated with decreased expression of GPR81 and MCT-1 in endothelial cells, as well as overproduction of IL-1β and elevation of lactate concentrations in the extracellular space in a dose-dependent manner. LPS treatment reduced JAM tight junction protein expression in cerebral endothelial cells and altered BBB structural integrity in vitro.ConclusionThe impairment of lactate reception and transport might contribute to the alterations of BBB structural and functional integrity caused by LPS-mediated neuroinflammation.Electronic supplementary materialThe online version of this article (10.1186/s12974-018-1233-2) contains supplementary material, which is available to authorized users.

The contribution of astrocytes and microglia to the regulation of neuroplasticity or neurovascular unit (NVU) is based on the coordinated secretion of gliotransmitters and cytokines and the release and uptake of metabolites. Blood-brain barrier (BBB) integrity and angiogenesis are influenced by perivascular cells contacting with the abluminal side of brain microvessel endothelial cells (pericytes, astrocytes) or by immune cells existing (microglia) or invading the NVU (macrophages) under pathologic conditions. The release of gliotransmitters or cytokines by activated astroglial and microglial cells is provided by distinct mechanisms, affects intercellular communication, and results in the establishment of microenvironment controlling BBB permeability and neuroinflammation. Glial glutamate transporters and connexin and pannexin hemichannels working in the tight functional coupling with the purinergic system serve as promising molecular targets for manipulating the intercellular communications that control BBB permeability in brain pathologies associated with excessive angiogenesis, cerebrovascular remodeling, and BBB-mediated neuroinflammation. Substantial progress in deciphering the molecular mechanisms underlying the (patho)physiology of perivascular glia provides promising approaches to novel clinically relevant therapies for brain disorders. The present review summarizes the current understandings on the secretory machinery expressed in glial cells (glutamate transporters, connexin and pannexin hemichannels, exocytosis mechanisms, membrane-derived microvesicles, and inflammasomes) and the role of secreted gliotransmitters and cytokines in the regulation of NVU and BBB permeability in (patho)physiologic conditions.

Рисунок 1. Экспрессия маркеров ангиогенеза в клетках ГЭБ in vitro при использовании FM19G11 (А) и GSI-I (Б). * -статистическая значимость между контрольной и опытной группами (p<0,05).

No abstract

Цель исследования. Изучить влияние индукторов нейровоспаления вирусного генеза на экспрессию NLRP3 и структурную целостность эндотелиальных клеток головного мозга in vitro. Материал и методы. Исследование проведено на клеточной культуре церебральных эндотелиоцитов. Источником клеток служил головной мозг крыс линии Wistar. К культуре эндотелиальных клеток добавляли полиинозиновую-полицитидиловую кислоту (РolyI:C)-20 мкг/мл. В качестве группы сравнения использовали культуру эндотелиоцитов, к которым в культуральную среду добавляли спинномозговую жидкость, полученную от пациента с энтеровирусным менингитом (100 мкл). Ликвор был стандартизирован по концентрации белка методом Лоури. Концентрация белка составила 1 мкг/мл. В качестве контроля использовались эндотелиоциты, культивируемые в стандартной культуральной среде. Культивирование осуществляли с использованием культуральных вставок для 12-луночных планшетов. Через 24 и 72 ч культивирования во всех группах регистрировали трансэндотелиальное сопротивление. Через 24 ч оценивали экспрессию молекул NLRP3 с использованием двойного непрямого метода иммуноферментного окрашивания согласно протоколу производителя. Первичные антитела к NLRP3 (Abcam, США, ab51952)-разведение 1 : 100. Вторичные антитела меченые Alexa Fluor 488 (Abcam, США, ab150117)разведение 1 : 200. Визуализация проводилась с помощью конфокальной лазерной микроскопии на микроскопе Olympus FV10i (Olympus, Япония). Результаты. Через 24 ч культивирования эндотелиоцитов с PolyI:C и вирусным ликвором наблюдается снижение показателей трансэндотелиального сопротивления по сравнению с контролем. Через 72 ч трансэндотелиальное сопротивление оставалось значимо более низким по сравнению с группой контроля. Установлено, что количество эндотелиальных клеток, экспрессирующих молекулу NLRP3, максимально в культуре с добавлением патологического ликвора. После инкубации клеток с PolyI:C количество NLRP3-иммунопозитивных эндотелиоцитов увеличилось по сравнению с контролем, но было ниже, чем в группе сравнения.

No abstract