Inhibition of myelin-cleaving poteolytic activities by interferon-beta in rat astrocyte cultures. Comparative analysis between gelatinases and calpain-II

Zika virus dysregulates the expression of astrocytic genes involved in neurodevelopment

Zika virus (ZIKV) is a kind of flavivirus emerged in French Polynesia and Brazil, and has led to a worldwide public health concern since 2016. ZIKV infection causes various neurological conditions, which are associated with fetus brain development or peripheral and central nervous systems (PNS/CNS) functional problems. To date, no vaccine or any specific antiviral therapy against ZIKV infection are available. It urgently needs efforts to explore the underlying molecular mechanisms of ZIKV-induced neural pathogenesis. ZIKV favorably infects neural and glial cells specifically astrocytes, consequently dysregulating gene expression and pathways with impairment of process neural cells. In this study, we applied a model for ZIKV replication in mouse primary astrocytes (MPAs) and profiled temporal alterations in the host transcriptomes upon ZIKV infection. Among the RNA-sequencing data of 27,812 genes, we examined 710 genes were significantly differentially expressed by ZIKV, which lead to dysregulation of numerous functions including neurons development and migration, glial cells differentiation, myelinations, astrocytes projection, neurogenesis, and brain development, along with multiple pathways including Hippo signaling pathway, tight junction, PI3K-Akt signaling pathway, and focal adhesion. Furthermore, we confirmed the dysregulation of the selected genes in MPAs and human astroglioma U251 cells. We found that PTBP1, LIF, GHR, and PTBP3 were upregulated while EDNRB and MBP were downregulated upon ZIKV infection. The current study highlights the ZIKV-mediated potential genes associated with neurodevelopment or related diseases.

Zika virus (ZIKV) infection causes serious neurological disorders of central and peripheral nervous system, and fetal brain development disorders including microcephaly. There are still uncovered explorations for the underlying molecular mechanism of ZIKV-infected pathogenesis. This study reveals a series of dysregulation of neuropathic genes mRNA and protein expression in mouse and human astrocytes upon ZIKV infection. As an ideal ZIKV infection model in mouse primary astrocytes (MPAs), RNA-seq was performed to profile transcriptome alteration by ZIKV infection. Bioinformatics analysis demonstrated the significant alterations of the 710 genes that were linked to glial cell differentiation and projection, neurogenesis and migration of neurons, myelination, as well as synaptic control. Among the top selected differentially expressed genes, such as PTBP1, LIF, GHR, PTBP3, EDNRB, and MBP, the mRNA and protein expressions were confirmed to identify the dysregulation of the transcriptome in MPAs upon ZIKV infection. Furthermore, ZIKV infection altered the mRNA and protein expression of these astrocytic genes involved in neurodevelopment in U251 cells following the analysis of the transcriptome. In conclusion, the alteration of astrocytic gene functions or associated-pathways suggest a novel clue of a mechanism involved in the ZIKV-induced neurodevelopment disorders.

Neuroprotective potential of isothiocyanates in an in vitro model of neuroinflammation

Isothiocyanates (ITCs), present as glucosinolate precursors in cruciferous vegetables, have shown anti-inflammatory, antioxidant and anticarcinogenic activities. Here, we compared the effects of three different ITCs on ROS production and on the expression of matrix metalloproteinase (MMP)-2 and -9, which represent important pathogenetic factors of various neurological diseases. Primary cultures of rat astrocytes were activated by LPS and simultaneously treated with different doses of Allyl isothiocyanate (AITC), 2-Phenethyl isothiocyanate (PEITC) and 2-Sulforaphane (SFN). Results showed that SFN and PEITC were able to counteract ROS production induced by H₂O₂. The zymographic analysis of cell culture supernatants evidenced that PEITC and SFN were the most effective inhibitors of MMP-9, whereas, only SFN significantly inhibited MMP-2 activity. PCR analysis showed that all the ITCs used significantly inhibited both MMP-2 and MMP-9 expression. The investigation on the mitogen-activated protein kinase (MAPK) signaling pathway demonstrated that ITCs modulate MMP transcription by inhibition of extracellular-regulated protein kinase (ERK) activity. Results of this study suggest that ITCs could be promising nutraceutical agents for the prevention and complementary treatment of neurological diseases associated with MMP involvement.

Molecular Effects of FDA-Approved Multiple Sclerosis Drugs on Glial Cells and Neurons of the Central Nervous System

Multiple sclerosis (MS) is characterized by peripheral and central inflammatory features, as well as demyelination and neurodegeneration. The available Food and Drug Administration (FDA)-approved drugs for MS have been designed to suppress the peripheral immune system. In addition, however, the effects of these drugs may be partially attributed to their influence on glial cells and neurons of the central nervous system (CNS). We here describe the molecular effects of the traditional and more recent FDA-approved MS drugs Fingolimod, Dimethyl Fumarate, Glatiramer Acetate, Interferon-β, Teriflunomide, Laquinimod, Natalizumab, Alemtuzumab and Ocrelizumab on microglia, astrocytes, neurons and oligodendrocytes. Furthermore, we point to a possible common molecular effect of these drugs, namely a key role for NFκB signaling, causing a switch from pro-inflammatory microglia and astrocytes to anti-inflammatory phenotypes of these CNS cell types that recently emerged as central players in MS pathogenesis. This notion argues for the need to further explore the molecular mechanisms underlying MS drug action.

Perspectives and New Aspects of Metalloproteinases' Inhibitors in the Therapy of CNS Disorders: From Chemistry to Medicine

Matrix metalloproteinases (MMPs) play a key role in remodeling of the extracellular matrix (ECM) and, at the same time, influence cell differentiation, migration, proliferation, and survival. Their importance in a variety of human diseases including cancer, rheumatoid arthritis, pulmonary emphysema and fibrotic disorders has been known for many years but special attention should be paid on the role of MMPs in the central nervous system (CNS) disorders. Till now, there are not many well documented physiological MMP target proteins in the brain but only some pathological ones. Numerous neurodegenerative diseases are a consequence of or result in disturbed remodeling of brain ECM, therefore proper action of MMPs as well as control of their activity may play crucial roles in the development of these diseases. In the present review, we discuss the role of metalloproteinase inhibitors, from the wellknown natural endogenous tissue inhibitors of metalloproteinases (TIMPs) to the exogenous synthetic ones like (4-phenoxyphenylsulfonyl)methylthiirane (SB-3CT), tetracyclines, batimastat (BB-94) and FN-439. As the MMP-TIMP system has been well described in physiological development as well as in pathological conditions mainly in neoplastic diseases, the knowledge about the enzymatic system in mammalian brain tissue still remains poorly understood in this context. Therefore, we focus on MMPs inhibition in the context of the physiological function of the adult brain as well as pathological conditions including neurodegenerative diseases, brain injuries, and others.

In vitro effect of antiretroviral drugs on cultured primary astrocytes: analysis of neurotoxicity and matrix metalloproteinase inhibition

There is little information available on the possible toxic effects that antiretroviral (ARV) drugs used for the treatment of human immunodeficiency virus (HIV)-infected subjects, may have on the central nervous system (CNS) resident cells. Moreover, it remains unclear whether the efficacy of the ARV drugs may also be due to their ability to exert extravirological effects on factors responsible for the development of HIV brain injury, e.g., matrix metalloproteinases (MMPs). This study investigates the toxicity of three different ARV drugs and on their ability to modulate levels and expression of gelatinases A (MMP-2) and B (MMP-9) in astrocytes. Primary cultures of rat astrocytes were activated by exposure to lipopolysaccaride (LPS) and simultaneously treated with darunavir, maraviroc, or raltegravir, used alone or in combination. Among the tested drugs, maraviroc was the less toxic for astrocytes. At toxic concentration (TC₅₀ ), the studied drugs induced the production of reactive oxygen species (ROS), suggesting that the oxidative stress may represent a mechanism of ARV toxicity. As assessed by gelatin zymography and RT-PCR, the single antiretroviral drugs reduced levels and expression of both MMP-2 and MMP-9 through the inhibition of the signaling transduction pathway of extracellular signal-regulated kinase1/2, which is involved in the regulation of MMP-9 gene. A synergistic inhibition of MMP-2 and MMP-9 was observed with combinations of the studied ARV drugs. The present results indicate that maraviroc, darunavir, and raltegravir, through their ability to inhibit MMP-2 and MMP-9 at doses non-toxic for astrocytes, might have a great potential for the management of HIV-associated neurological complications.

Cytotoxicity Study on Luminescent Nanocrystals Containing Phospholipid Micelles in Primary Cultures of Rat Astrocytes

Luminescent colloidal nanocrystals (NCs) are emerging as a new tool in neuroscience field, representing superior optical probes for cellular imaging and medical diagnosis of neurological disorders with respect to organic fluorophores. However, only a limited number of studies have, so far, explored NC applications in primary neurons, glia and related cells. Indeed astrocytes, as resident cells in the central nervous system (CNS), play an important pathogenic role in several neurodegenerative and neuroinflammatory diseases, therefore enhanced imaging tools for their thorough investigation are strongly amenable. Here, a comprehensive and systematic study on the in vitro toxicological effect of core-shell type luminescent CdSe@ZnS NCs incorporated in polyethylene glycol (PEG) terminated phospholipid micelles on primary cultures of rat astrocytes was carried out. Cytotoxicity response of empty micelles based on PEG modified phospholipids was compared to that of their NC containing counterpart, in order to investigate the effect on cell viability of both inorganic NCs and micelles protecting NC surface. Furthermore, since the surface charge and chemistry influence cell interaction and toxicity, effect of two different functional groups terminating PEG-modified phospholipid micelles, namely amine and carboxyl group, respectively, was evaluated against bare micelles, showing that carboxyl group was less toxic. The ability of PEG-lipid micelles to be internalized into the cells was qualitatively and quantitatively assessed by fluorescence microscopy and photoluminescence (PL) assay. The results of the experiments clearly demonstrate that, once incorporated into the micelles, a low, not toxic, concentration of NCs is sufficient to be distinctly detected within cells. The overall study provides essential indications to define the optimal experimental conditions to effectively and profitably use the proposed luminescent colloidal NCs as optical probe for future in vivo experiments.

Inhibitory Effect of Aqueous Extracts from Marine Sponges on the Activity and Expression of Gelatinases A (MMP-2) and B (MMP-9) in Rat Astrocyte Cultures

The aim of this study was to evaluate whether water soluble compounds present in aqueous extracts from seven Mediterranean demosponges exert biological activity towards matrix metalloproteinases (MMPs), which represent important pathogenic factors of human diseases. Aqueous extracts were tested on LPS-activated cultured rat astrocytes, and levels and expression of MMP-2 and MMP-9 were assessed by zymography and RT-PCR, respectively. Our results demonstrated that the studied extracts contain water soluble compounds able to inhibit MMP-2 and MMP-9 activity and expression. We also compared the anti-MMP activities present in aqueous extracts from wild and reared specimens of Tethya aurantium and T. citrina. The results obtained revealed that the reared sponges maintain the production of bioactive compounds with inhibitory effect on MMP-2 and MMP-9 for all the duration of the rearing period. Taken together, our results indicate that the aqueous extracts from the selected Mediterranean demosponges possess a variety of water-soluble bioactive compounds, which are able to inhibit MMPs at different levels. The presence of biological activity in aqueous extracts from reared specimens of T. aurantium and T. citrina strongly encourage sponge aquaculture as a valid option to supply sponge biomass for drug development on a large scale.

Matrix metalloproteinases and their pathological upregulation in multiple sclerosis: an overview

Matrix metalloproteinases (MMPs) are a family of extracellular proteases associated with extracellular matrix remodeling. They are involved in many physiological and reparative processes. MMPs can break down all extracellular constituents; therefore, their expression is very tightly regulated and their abnormal activity or over production has been linked to many diseases including multiple sclerosis (MS) which is a leading cause of non-traumatic disability in young adults in North America. Recently many studies, both in animals and humans, have been conducted to better elucidate the underlying causes, mechanisms and pathophysiology of MS. In this review, we discuss the potential role of pathological upregulation of MMPs in MS and future challenges which if properly addressed might help in development of potential cure for this disease.

FAD synthesis and degradation in the nucleus create a local flavin cofactor pool

FAD is a redox cofactor ensuring the activity of many flavoenzymes mainly located in mitochondria but also relevant for nuclear redox activities. The last enzyme in the metabolic pathway producing FAD is FAD synthase (EC 2.7.7.2), a protein known to be localized both in cytosol and in mitochondria. FAD degradation to riboflavin occurs via still poorly characterized enzymes, possibly belonging to the NUDIX hydrolase family. By confocal microscopy and immunoblotting experiments, we demonstrate here the existence of FAD synthase in the nucleus of different experimental rat models. HPLC experiments demonstrated that isolated rat liver nuclei contain ∼300 pmol of FAD·mg(-1) protein, which was mainly protein-bound FAD. A mean FAD synthesis rate of 18.1 pmol·min(-1)·mg(-1) protein was estimated by both HPLC and continuous coupled enzymatic spectrophotometric assays. Rat liver nuclei were also shown to be endowed with a FAD pyrophosphatase that hydrolyzes FAD with an optimum at alkaline pH and is significantly inhibited by adenylate-containing nucleotides. The coordinate activity of these FAD forming and degrading enzymes provides a potential mechanism by which a dynamic pool of flavin cofactor is created in the nucleus. These data, which significantly add to the biochemical comprehension of flavin metabolism and its subcellular compartmentation, may also provide the basis for a more detailed comprehension of the role of flavin homeostasis in biologically and clinically relevant epigenetic events.