An early glycolysis burst in microglia regulates mitochondrial dysfunction in oligodendrocytes under neuroinflammation.

Metabolism and energy processes governing oligodendrocyte function during neuroinflammatory disease are of great interest. However, how varied cellular environments affect oligodendrocyte activity during neuroinflammation is unknown. We demonstrate that activated microglial energy metabolism controls oligodendrocyte mitochondrial respiration and activity. Lipopolysaccharide/interferon gamma promote glycolysis and decrease mitochondrial respiration and myelin protein synthesis in rat brain glial cells. Enriched microglia showed an early burst in glycolysis. In microglia-conditioned medium, oligodendrocytes did not respire and expressed less myelin. SCENITH revealed metabolic derangement in microglia and O4-positive oligodendrocytes in endotoxemia and experimental autoimmune encephalitogenic models. The early burst of glycolysis in microglia was mediated by PDPK1 and protein kinase B/AKT signaling. We found that microglia-produced NO and itaconate, a tricarboxylic acid bifurcated metabolite, reduced mitochondrial respiration in oligodendrocytes. During inflammation, we discovered a signaling pathway in microglia that could be used as a therapeutic target to restore mitochondrial function in oligodendrocytes and induce remyelination.

Pro-resolution lipid mediator maresin-1 ameliorates inflammation, promotes neuroprotection, and prevents disease progression in experimental models of multiple sclerosis.

Multiple sclerosis (MS) is the most common inflammatory neurodegenerative disease in young adults, resulting in neurological defects and disability. The endogenous mechanisms to resolve inflammation are intact but become defective in patients, resulting in lack of resolution mediators and unresolved chronic inflammation. Docosahexaenoic acid (DHA) metabolism being impaired in MS, we hypothesize that supplementing its downstream metabolite maresin 1 (MaR1) will alleviate inflammation and demyelination in preclinical mouse model of MS; experimental allergic encephalomyelitis (EAE). Restoration of MaR1 by its exogenous administration in EAE mice propagated inflammatory resolution and had a protective effect on neurological deficits, prevented disease progression, and reduced disease severity by reducing immune cell infiltration (CD4+IL17+ and CD4+IFN-γ+) into the CNS. It significantly reduced the proinflammatory cytokine IL17 and promoted an anti-inflammatory response via IL10 and IL4. Neutralization of IL10 abolished the protective effect of MaR1 in EAE confirming IL10 is mediating MaR1 effect in EAE. Furthermore, it improved the pathophysiology and exerted neuroprotective effects by mitigating disease signs in EAE as evidenced by lower levels of NFL in the plasma of treated group compared to control and higher MBP expression in the brain from the MaR1 treated mice, decreased inflammatory infiltrates, and less demyelination and vacuolization in the spinal cord tissue sections of treated mice. SCENITH data confirmed that MaR1 maintains myelin by regulating oligodendrocyte metabolism. Also, it induces metabolic reprogramming in infiltrating CD4 cells and macrophages, which modulate their phenotype. Metabolic changes induced macrophages by MaR1 restores the impaired efferocytosis in EAE, promoting clearance of damaged myelin and dead cells; thereby lowering the disability with disease course. Overall, MaR1 supplementation has anti-inflammatory and neuroprotective effects in preclinical animal models and induces metabolic reprogramming in disease associated cell-types, promotes efferocytosis, implying that it could be a new therapeutic molecule in MS and other autoimmune diseases. Highlights: Inflammation is dysregulated in EAE due to impaired synthesis of DHA derived proresolving lipid mediator MaR1.Administration of the resolution agonist MaR1 propagates resolution processes and improves neurological outcome in RR model of EAE.MaR1 ameliorates clinical signs of EAE by attenuating pro-inflammatory cytokine IL17 mediated response and promoting anti-inflammatory response through IL10.MaR1 supplementation improves the pathophysiology in EAE and shows neuroprotection as indicated by the lower levels of NFL in the plasma and higher expression of MBP in the brain of treated mice.MaR1 induces metabolic reprogramming in disease-associated cell types.MaR1 promotes efferocytosis in EAE through metabolic reprogramming of macrophages. Significance: Inflammatory process is a protective response to several challenges like injury or infection. However, it must resolve over time to maintain tissue homeostasis. Impaired or delayed resolution leads to damaging effects, including chronic inflammation, tissue damage, and disease progression as occurs in multiple sclerosis (MS). We report that inflammation is dysregulated in preclinical animal model of MS, experimental autoimmune encephalomyelitis (EAE), partially due to impaired synthesis of proresolving lipid mediators. We show that the administration of the resolution agonist known as maresin 1 (MaR1) in EAE actively propagates resolution processes and improves neurological outcome. We conclude that MaR1 is a potential interventional candidate to attenuate dysregulated inflammation and to restore neurological deficits in EAE.

Immuno-Responsive Gene-1: A mitochondrial gene regulates pathogenic Th17 in CNS autoimmunity mouse model.

Pathogenic Th17 cells are crucial to CNS autoimmune diseases like multiple sclerosis (MS), though their control by endogenous mechanisms is unknown. RNAseq analysis of brain glial cells identified immuno-responsive gene 1 (Irg1), a mitochondrial-related enzyme-coding gene, as one of the highly upregulated gene under inflammatory conditions which were further validated in the spinal cord of animals with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Moreover, Irg1 mRNA and protein levels in myeloid, CD4, and B cells were higher in the EAE group, raising questions about its function in CNS autoimmunity. We observed that Irg1 knockout (KO) mice exhibited severe EAE disease and greater mononuclear cell infiltration, including triple-positive CD4 cells expressing IL17a, GM-CSF, and IFNγ. Lack of Irg1 in macrophages led to higher levels of Class II expression and polarized myelin primed CD4 cells into pathogenic Th17 cells through the NLRP3/IL1ß axis. Our findings show that Irg1 in macrophages plays an important role in the formation of pathogenic Th17 cells, emphasizing its potential as a therapy for autoimmune diseases, including MS.

Temporal transcriptome analysis of neuronal commitment reveals the preeminent role of the divergent lncRNA biotype and a critical candidate gene during differentiation.

lncRNA genes can be genic or "intergenic". "Genic" RNAs can be further divided into six biotypes. Through genome-wide analysis of a publicly available data set on corticogenesis, we found that the divergent lncRNA (XH) biotype, comprising the lncRNA and the coding gene being in opposite directions in a head-to-head manner, was most prominent during neural commitment. Within this biotype, a coding gene/divergent RNA pair of the BASP1 gene and the uncharacterized RNA loc285696 (hitherto referred as BASP1-AS1) formed a major HUB gene during neuronal differentiation. Experimental validation during the in vitro differentiation of human neural progenitor cells (hNPCs) showed that BASP1-AS1 regulates the expression of its adjacent coding gene, BASP1. Both transcripts increased sharply on the first day of neuronal differentiation of hNPCs, to fall steadily thereafter, reaching very low levels in differentiated neurons. BASP1-AS1 RNA and the BASP1 gene formed a molecular complex that also included the transcription factor TCF12. TCF12 is coded by the DYX1 locus, associated with inherited dyslexia and neurodevelopmental defects. Knockdown of BASP1-AS1, BASP1, or TCF12 impaired the neuronal differentiation of hNPCs, as seen by reduction in DCX and TUJ1-positive cells and by reduced neurite length. There was also increased cell proliferation. A common set of critical genes was affected by the three molecules in the complex. Our study thus identified the role of the XH biotype and a novel mediator of neuronal differentiation-the complex of BASP1-AS1, BASP1, and TCF12. It also linked a neuronal differentiation pathway to inherited dyslexia.

Shared Transcriptional Signatures in Major Depressive Disorder and Mouse Chronic Stress Models.

BACKGROUND: Most of our knowledge of the biological basis of major depressive disorder (MDD) is derived from studies of chronic stress models in rodents. While these models capture certain aspects of the behavioral and neuroendocrine features of MDD, the extent to which they reproduce the molecular pathology of the human syndrome remains unknown. METHODS: We systematically compared transcriptional signatures in two brain regions implicated in depression-medial prefrontal cortex and nucleus accumbens-of humans with MDD and of 3 chronic stress models in mice: chronic variable stress, adult social isolation, and chronic social defeat stress. We used differential expression analysis combined with weighted gene coexpression network analysis to create interspecies gene networks and assess the capacity of each stress paradigm to recapitulate the transcriptional organization of gene networks in human MDD. RESULTS: Our results show significant overlap between transcriptional alterations in medial prefrontal cortex and nucleus accumbens in human MDD and the 3 mouse chronic stress models, with each of the chronic stress paradigms capturing distinct aspects of MDD abnormalities. Chronic variable stress and adult social isolation better reproduce differentially expressed genes, while chronic social defeat stress and adult social isolation better reproduce gene networks characteristic of human MDD. We also identified several gene networks and their constituent genes that are most significantly associated with human MDD and mouse stress models. CONCLUSIONS: This study demonstrates the ability of 3 chronic stress models in mice to recapitulate distinct aspects of the broad molecular pathology of human MDD, with no one mouse model apparently better than another.

Gadd45b mediates depressive-like role through DNA demethylation.

Animal studies using chronic social defeat stress (CSDS) in mice showed that brain-derived neurotrophic factor (BDNF) signaling in the mesolimbic dopamine (DA) circuit is important for the development of social aversion. However, the downstream molecular targets after BDNF release from ventral tegmental area (VTA) DA terminals are unknown. Here, we show that depressive-like behaviors induced by CSDS are mediated in part by Gadd45b downstream of BDNF signaling in the nucleus accumbens (NAc). We show that Gadd45b mRNA levels are increased in susceptible but not resilient mice. Intra-NAc infusion of BDNF or optical stimulation of VTA DA terminals in NAc enhanced Gadd45b expression levels in the NAc. Importantly, Gadd45b downregulation reversed social avoidance in susceptible mice. Together, these data suggest that Gadd45b in NAc contributes to susceptibility to social stress. In addition, we investigated the function of Gadd45b in demethylating CpG islands of representative gene targets, which have been associated with a depressive phenotype in humans and animal models. We found that Gadd45b downregulation changes DNA methylation levels in a phenotype-, gene-, and locus-specific fashion. Together, these results highlight the contribution of Gadd45b and changes in DNA methylation in mediating the effects of social stress in the mesolimbic DA circuit.

Identification of lncRNAs Associated With Neuroblastoma in Cross-Sectional Databases: Potential Biomarkers.

Long non-coding RNAs (lncRNAs) have emerged as an important regulatory control in biological systems. Though the field of lncRNA has been progressing rapidly, a complete understanding of the role of lncRNAs in neuroblastoma pathogenesis is still lacking. To identify the abrogated lncRNAs in primary neuroblastoma and in the metastasized as well as the relapsed form of neuroblastoma, we analyzed an RNA-seq dataset on neuroblastoma that is available online to identify the lncRNAs that could potentially be contributing to the biology of neuroblastoma. The identified lncRNAs were further scrutinized using a publicly available epigenetic dataset of neuroblastoma and a cancer database. After this cross-sectional study, we were able to identify three significant lncRNAs, CASC15, PPP1R26-AS1, and USP3-AS1, which could serve as potential biomarkers in clinical studies of neuroblastoma pathogenesis.

Identification and epigenetic analysis of divergent long non-coding RNAs in multilineage differentiation of human Neural Progenitor Cells.

Long non-coding RNAs have emerged as an important regulatory layer in biological systems. Of the various types of lncRNAs, one class (designated as divergent RNAs/XH), which is in head-to-head overlap with the coding genes, has emerged as a critical biotype that regulates development and cellular differentiation. This work aimed to analyze previously published data on differential expression, epigenetic and network analysis in order to demonstrate the association of divergent lncRNAs, a specific biotype with the differentiation of human neural progenitor cells (hNPCs). We have analyzed various available RNAseq databases that address the neuronal and astrocytic differentiation of hNPCs and identified differentially expressed lncRNAs (DELs) during cell-fate determination. Key DELs identified from the databases were experimentally verified by us in our in-vitro hNPC differentiation system. We also analyzed the change in promoter activity using ChIP-seq datasets of the histone markers H3K4me3 (activation) and H3K27me3 (inactivation) of these DELs. Additionally, we explored the change in the euchromatinization state of DELs (by analyzing DNase-seq data) during lineage-specific differentiation of hNPCs and performed their network analysis. We were able to identify differences between neuronal and astrocytic differentiation of hNPCs at the level of divergent DELs epigenetic markers, DNAase hypersensitive sites and gene expression network. Divergent lncRNAs are more involved in neuronal rather than astrocytic differentiation, while the sense downstream lncRNA biotype appears to be more involved in astrocytic differentiation. By studying the lncRNA involvement of distinct biotypes, we have been able to indicate the preferential role of a particular biotype during lineage-specific differentiation.