Gene expression comparison reveals distinct basal expression of HOX members and differential TNF-induced response between brain- and spinal cord-derived microvascular endothelial cells

Constitutive DAMPs in CNS injury: From preclinical insights to clinical perspectives

Damage-associated molecular patterns (DAMPs) are endogenous molecules released in tissues upon cellular damage and necrosis, acting to initiate sterile inflammation. Constitutive DAMPs (cDAMPs) have the particularity to be present within the intracellular compartments of healthy cells, where they exert diverse functions such as regulation of gene expression and cellular homeostasis. However, after injury to the central nervous system (CNS), cDAMPs are rapidly released by stressed, damaged or dying neuronal, glial and endothelial cells, and can trigger inflammation without undergoing structural modifications. Several cDAMPs have been described in the injured CNS, such as interleukin (IL)-1α, IL-33, nucleotides (e.g. ATP), and high-mobility group box protein 1. Once in the extracellular milieu, these molecules are recognized by the remaining surviving cells through specific DAMP-sensing receptors, thereby inducing a cascade of molecular events leading to the production and release of proinflammatory cytokines and chemokines, as well as cell adhesion molecules. The ensuing immune response is necessary to eliminate cellular debris caused by the injury, allowing for damage containment. However, seeing as some molecules associated with the inflammatory response are toxic to surviving resident CNS cells, secondary damage occurs, aggravating injury and exacerbating neurological and behavioral deficits. Thus, a better understanding of these cDAMPs, as well as their receptors and downstream signaling pathways, could lead to identification of novel therapeutic targets for treating CNS injuries such as SCI, TBI, and stroke. In this review, we summarize the recent literature on cDAMPs, their specific functions, and the therapeutic potential of interfering with cDAMPs or their signaling pathways.

Identification and experimental verification of senescence-related gene signatures and molecular subtypes in idiopathic pulmonary arterial hypertension

Evidences illustrate that cell senescence contributes to the development of pulmonary arterial hypertension. However, the molecular mechanisms remain unclear. Since there may be different senescence subtypes between PAH patients, consistent senescence-related genes (SRGs) were utilized for consistent clustering by unsupervised clustering methods. Senescence is inextricably linked to the immune system, and the immune cells in each cluster were estimated by ssGSEA. To further screen out more important SRGs, machine learning algorithms were used for identification and their diagnostic value was assessed by ROC curves. The expression of hub genes were verified in vivo and in vitro. Transcriptome analysis was used to assess the effects of silence of hub gene on different pathways. Three senescence molecular subtypes were identified by consensus clustering. Compared with cluster A and B, most immune cells and checkpoint genes were higher in cluster C. Thus, we identified senescence cluster C as the immune subtype. The ROC curves of IGF1, HOXB7, and YWHAZ were remarkable in both datasets. The expression of these genes was increased in vitro. Western blot and immunohistochemical analyses revealed that YWHAZ expression was also increased. Our transcriptome analysis showed autophagy-related genes were significantly elevated after silence of YWHAZ. Our research provided several prospective SRGs and molecular subtypes. Silence of YWHAZ may contribute to the clearance of senescent endothelial cells by activating autophagy.

Microvascular endothelial cells derived from spinal cord promote spinal cord injury repair

Neural regeneration after spinal cord injury (SCI) closely relates to the microvascular endothelial cell (MEC)-mediated neurovascular unit formation. However, the effects of central nerve system-derived MECs on neovascularization and neurogenesis, and potential signaling involved therein, are unclear. Here, we established a primary spinal cord-derived MECs (SCMECs) isolation with high cell yield and purity to describe the differences with brain-derived MECs (BMECs) and their therapeutic effects on SCI. Transcriptomics and proteomics revealed differentially expressed genes and proteins in SCMECs were involved in angiogenesis, immunity, metabolism, and cell adhesion molecular signaling was the only signaling pathway enriched of top 10 in differentially expressed genes and proteins KEGG analysis. SCMECs and BMECs could be induced angiogenesis by different stiffness stimulation of PEG hydrogels with elastic modulus 50-1650 Pa for SCMECs and 50-300 Pa for BMECs, respectively. Moreover, SCMECs and BMECs promoted spinal cord or brain-derived NSC (SNSC/BNSC) proliferation, migration, and differentiation at different levels. At certain dose, SCMECs in combination with the NeuroRegen scaffold, showed higher effectiveness in the promotion of vascular reconstruction. The potential underlying mechanism of this phenomenon may through VEGF/AKT/eNOS- signaling pathway, and consequently accelerated neuronal regeneration and functional recovery of SCI rats compared to BMECs. Our findings suggested a promising role of SCMECs in restoring vascularization and neural regeneration.

TNF-α and IL-1β Modulate Blood-Brain Barrier Permeability and Decrease Amyloid-β Peptide Efflux in a Human Blood-Brain Barrier Model

The blood-brain barrier (BBB) is a selective barrier and a functional gatekeeper for the central nervous system (CNS), essential for maintaining brain homeostasis. The BBB is composed of specialized brain endothelial cells (BECs) lining the brain capillaries. The tight junctions formed by BECs regulate paracellular transport, whereas transcellular transport is regulated by specialized transporters, pumps and receptors. Cytokine-induced neuroinflammation, such as the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), appear to play a role in BBB dysfunction and contribute to the progression of Alzheimer’s disease (AD) by contributing to amyloid-β (Aβ) peptide accumulation. Here, we investigated whether TNF-α and IL-1β modulate the permeability of the BBB and alter Aβ peptide transport across BECs. We used a human BBB in vitro model based on the use of brain-like endothelial cells (BLECs) obtained from endothelial cells derived from CD34+ stem cells cocultivated with brain pericytes. We demonstrated that TNF-α and IL-1β differentially induced changes in BLECs’ permeability by inducing alterations in the organization of junctional complexes as well as in transcelluar trafficking. Further, TNF-α and IL-1β act directly on BLECs by decreasing LRP1 and BCRP protein expression as well as the specific efflux of Aβ peptide. These results provide mechanisms by which CNS inflammation might modulate BBB permeability and promote Aβ peptide accumulation. A future therapeutic intervention targeting vascular inflammation at the BBB may have the therapeutic potential to slow down the progression of AD.

Blocking the EGFR/p38/NF-κB signaling pathway alleviates disruption of BSCB and subsequent inflammation after spinal cord injury

Epidermal growth factor receptor (EGFR) activation is involved in blood spinal cord barrier (BSCB) disruption and secondary injury after spinal cord injury (SCI). However, the underlying mechanisms of EGFR activation mediating BSCB disruption and secondary injury after SCI remain unclear. An in vitro model of oxygen and glucose deprivation/reoxygenation (OGD/R) induced BSCB damage and in vivo rat SCI model were employed to define the role of EGFR/p38/NF-κB signal pathway activation and its induced inflammatory injury in main cellular components of BSCB. Genetic regulation (lentivirus delivered shRNA and overexpression system) or chemical intervention (agonist or inhibitor) were applied to activate or inactivate EGFR and p38 in astrocytes and microvascular endothelial cells (MEC) under which conditions, the expression of pro-inflammatory factors (TNF-α, iNOS, COX-2, and IL-1β), tight junction (TJ) protein (ZO-1 and occludin), nuclear translocation of NF-κB and permeability of BSCB were analyzed. The pEGFR was increased in astrocytes and MEC which induced the activation of EGFR and p38 and NF-κB nuclear translocation. The activation of EGFR and p38 increased the TNF-α, iNOS, COX-2, and IL-1β responsible for the inflammatory injury and reduced the ZO-1 and occludin which caused BSCB disruption. While EGFR or p38 inactivation inhibited NF-κB nuclear translocation, and markedly attenuated the production of pro-inflammatory factors and the loss of TJ protein. This study suggests that the EGFR activation in main cellular components of BSCB after SCI mediates BSCB disruption and secondary inflammatory injury via the EGFR/p38/NF-κB pathway.

Doxorubicin-Induced Cognitive Impairment: The Mechanistic Insights

Chemotherapy can significantly prolong the survival of patients with breast cancer; Nevertheless, the majority of patients receiving chemotherapy such as doxorubicin may have cognitive deficits that manifest as impairments in learning, reasoning, attention, and memory. The phenomenon of chemotherapy-induced cognitive decline is termed as chemotherapy-related cognitive impairment (CRCI) or chemo-brain. Doxorubicin (DOX), a commonly used drug in adjuvant chemotherapy for patients with breast cancer, has been reported to induce chemo-brain through a variety of mechanisms including DNA damage, oxidative stress, inflammation, dysregulation of apoptosis and autophagy, changes in neurotransmitter levels, mitochondrial dysfunction, glial cell interactions, neurogenesis inhibition, and epigenetic factors. These mechanisms do not operate independently but are inter-related, coordinately contributing to the development of chemo-brain. Here we review the relationships of these mechanisms and pathways in attempt to provide mechanistic insights into the doxorubicin-induced cognitive impairment.

CircRNA 001372 Reduces Inflammation in Propofol-Induced Neuroinflammation and Neural Apoptosis through PIK3CA/Akt/NF-κB by miRNA-148b-3p

Objectives: To investigate effects of circular RNA (circRNA) 001372 and its antagonist miRNAs-148b-3p on propofol-induced neurotoxicity and neuroinflammation in rat brain and pheochromocytoma cells.Methods: Sprague Dawley rats in propofol model group (n = 6) were intraperitoneal injected with propofol (50 mg/kg) and in sham control group (n = 6) without any treatment. Twenty-four h later, brain tissues were acquired during pentobarbital anesthesia. PC-12 cells were transfected with or without circRNA001372 mimics, circRNA001372 inhibitor, negative mimics or miRNA-148b-3p for 48 h and then treated with propofol (100 μM) for 48 h. Quantitative reverse transcription PCR and gene chips were used for detecting levels of circRNA001372, Haemotoxylin and Eosin staining for cell morphology, MTT for cell viability, flow cytometry for apoptosis, enzyme-linked immunosorbent assay for lactate dehydrogenase (LDH), interleukin-1β (IL-1β), IL-6, IL17 and IL-18, and Western blots for phosphoinositide 3-kinase (PI3K), Akt, phosphorylated Akt, and nuclear factor (NF) κB, dual-light luminescent reporter gene assay for luciferase reporter.Results: The propofol anesthesia in rats decreases levels of circRNA001372 and increases levels of cytokines including IL-1β, IL-6, IL17 and IL-18, resulting in the neurocyte damage in brain. In propofol-treated PC-12 cells, the inhibition of circRNA001372 increases apoptosis and cell damage makers, including LDH, IL-1β, IL-6, IL17, IL-18, resulting in the reduction of cell viability, which have been revised after over-expression of circRNA001372. MiRNA-148b-3p reduces circRNA001372-incresed PI3K and pAKt levels but enhances the circRNA001372-decreased NFκB level.Conclusions: CircRNA001372 suppresses propofol-induced neurotoxicity and neuroinflammation through PI3K/Akt/NF-κB signaling pathway in rat brain and neurocytes. MiRNA-148b-3p antagonizes the effects of circRNA001372.

Modulation of HOXA9 after skeletal muscle denervation and reinnervation

Homeobox A9 (HOXA9), the expression of which is promoted by mixed lineage leukemia 1 (MLL1) and WD-40 repeat protein 5 (WDR5), is a homeodomain-containing transcription factor that plays an essential role in regulating stem cell activity. HOXA9 has been found to inhibit skeletal muscle regeneration and delay recovery after muscle wounding in aged mice, but little is known about its role in denervated/reinnervated muscles. We performed detailed time-dependent expression analyses of HOXA9 and its promoters, MLL1 and WDR5, in rat gastrocnemius muscles after the following three types of sciatic nerve surgeries: nerve transection (denervation), end-to-end repair (repair), and sham operation (sham). Then, the specific mechanisms of HOXA9 were detected in vitro by transfecting primary satellite cells with empty pIRES2-DsRed2, pIRES2-DsRed2-HOXA9, empty pPLK/GFP-Puro, and pPLK/GFP-Puro-HOXA9 small hairpin RNA (shRNA) plasmids. We found, for the first time, that HOXA9 protein expression simultaneously increased with increasing denervated muscle atrophy severity and that upregulated MLL1 and WDR5 expression was partly associated with denervation. Indeed, in vitro experiments revealed that HOXA9 inhibited myogenic differentiation, affected the best known atrophic signaling pathways, and promoted apoptosis but did not eliminate the differentiation potential of primary satellite cells. HOXA9 may promote denervated muscle atrophy by regulating the activity of satellite cells.

TGFB1-Mediated Gliosis in Multiple Sclerosis Spinal Cords Is Favored by the Regionalized Expression of HOXA5 and the Age-Dependent Decline in Androgen Receptor Ligands

In multiple sclerosis (MS) patients with a progressive form of the disease, spinal cord (SC) functions slowly deteriorate beyond age 40. We previously showed that in the SC of these patients, large areas of incomplete demyelination extend distance away from plaque borders and are characterized by a unique progliotic TGFB1 (Transforming Growth Factor Beta 1) genomic signature. Here, we attempted to determine whether region- and age-specific physiological parameters could promote the progression of SC periplaques in MS patients beyond age 40. An analysis of transcriptomics databases showed that, under physiological conditions, a set of 10 homeobox (HOX) genes are highly significantly overexpressed in the human SC as compared to distinct brain regions. Among these HOX genes, a survey of the human proteome showed that only HOXA5 encodes a protein which interacts with a member of the TGF-beta signaling pathway, namely SMAD1 (SMAD family member 1). Moreover, HOXA5 was previously found to promote the TGF-beta pathway. Interestingly, SMAD1 is also a protein partner of the androgen receptor (AR) and an unsupervised analysis of gene ontology terms indicates that the AR pathway antagonizes the TGF-beta/SMAD pathway. Retrieval of promoter analysis data further confirmed that AR negatively regulates the transcription of several members of the TGF-beta/SMAD pathway. On this basis, we propose that in progressive MS patients, the physiological SC overexpression of HOXA5 combined with the age-dependent decline in AR ligands may favor the slow progression of TGFB1-mediated gliosis. Potential therapeutic implications are discussed.

Long-Term Pantethine Treatment Counteracts Pathologic Gene Dysregulation and Decreases Alzheimer's Disease Pathogenesis in a Transgenic Mouse Model

The low-molecular weight thiol pantethine, known as a hypolipidemic and hypocholesterolemic agent, is the major precursor of co-enzyme A. We have previously shown that pantethine treatment reduces amyloid-β (Aβ)-induced IL-1β release and alleviates pathological metabolic changes in primary astrocyte cultures. These properties of pantethine prompted us to investigate its potential benefits in vivo in the 5XFAD (Tg) mouse model of Alzheimer's disease (AD).1.5-month-old Tg and wild-type (WT) male mice were submitted to intraperitoneal administration of pantethine or saline control solution for 5.5 months. The effects of such treatments were investigated by performing behavioral tests and evaluating astrogliosis, microgliosis, Αβ deposition, and whole genome expression arrays, using RNAs extracted from the mice hippocampi. We observed that long-term pantethine treatment significantly reduced glial reactivity and Αβ deposition, and abrogated behavioral alteration in Tg mice. Moreover, the transcriptomic profiles revealed that after pantethine treatment, the expression of genes differentially expressed in Tg mice, and in particular those known to be related to AD, were significantly alleviated. Most of the genes overexpressed in Tg compared to WT were involved in inflammation, complement activation, and phagocytosis and were found repressed upon pantethine treatment. In contrast, pantethine restored the expression of a significant number of genes involved in the regulation of Αβ processing and synaptic activities, which were downregulated in Tg mice. Altogether, our data support a beneficial role for long-term pantethine treatment in preserving CNS crucial functions altered by Aβ pathogenesis in Tg mice and highlight the potential efficiency of pantethine to alleviate AD pathology.

Integrative analysis of the lncRNA-associated ceRNA network reveals lncRNAs as potential prognostic biomarkers in human muscle-invasive bladder cancer

Background

Long noncoding RNAs (lncRNAs) play important roles in competing endogenous RNA (ceRNA) networks involved in the development and progression of various cancers, including muscle-invasive bladder cancer (MIBC).

Purpose

This study aims to construct the lncRNA-associated ceRNA network and identify lncRNA signatures correlated with the clinical features of MIBC tissue samples from The Cancer Genome Atlas (TGCA) database.

Methods

The differential expression profiles of MIBC associated lncRNAs, miRNAs and mRNAs were obtained from TCGA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to determine the principal functions of significantly dysregulated mRNAs. The dysregulated lncRNA-associated ceRNA network of MIBC was constructed based on the bioinformatics data, and the correlations between lncRNA expression and clinical features were analyzed using a weighted gene coexpression network analysis (WGCNA). Six cancer specific lncRNAs from the ceRNA network were randomly selected to detect their expression in 32 paired MIBC tissue samples and 5 bladder cancer cell lines using quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The ceRNA network was constructed with 30 lncRNAs, 13 miRNAs and 32 mRNAs. Seventeen lncRNAs in the ceRNA network correlated with certain clinical features, and only 1 lncRNA (MIR137HG) correlated with the overall survival (OS) of patients with MIBC (log-rank test P<0.05). GO and KEGG analyses revealed roles for the potential mRNA targets of MIR137HG in epithelial cell differentiation and the peroxisome proliferator-activated receptor (PPAR) and tumor necrosis factor (TNF) signaling pathways. The expression data from TCGA were highly consistent with the verification results of the MIBC tissue samples and bladder cancer cell lines.

Conclusion

These findings improve our understanding of the regulatory mechanism of the lncRNA-miRNA-mRNA ceRNA network and reveal potential lncRNAs as prognostic biomarkers of MIBC.

Human ES-derived MSCs correct TNF-α-mediated alterations in a blood-brain barrier model

Background

Immune cell trafficking into the CNS is considered to contribute to pathogenesis in MS and its animal model, EAE. Disruption of the blood–brain barrier (BBB) is a hallmark of these pathologies and a potential target of therapeutics. Human embryonic stem cell-derived mesenchymal stem/stromal cells (hES-MSCs) have shown superior therapeutic efficacy, compared to bone marrow-derived MSCs, in reducing clinical symptoms and neuropathology of EAE. However, it has not yet been reported whether hES-MSCs inhibit and/or repair the BBB damage associated with neuroinflammation that accompanies EAE.

Methods

BMECs were cultured on Transwell inserts as a BBB model for all the experiments. Disruption of BBB models was induced by TNF-α, a pro-inflammatory cytokine that is a hallmark of acute and chronic neuroinflammation.

Results

Results indicated that hES-MSCs reversed the TNF-α-induced changes in tight junction proteins, permeability, transendothelial electrical resistance, and expression of adhesion molecules, especially when these cells were placed in direct contact with BMEC.

Conclusions

hES-MSCs and/or products derived from them could potentially serve as novel therapeutics to repair BBB disturbances in MS.

Electronic supplementary material

The online version of this article (10.1186/s12987-019-0138-5) contains supplementary material, which is available to authorized users.

Subcutaneous Maturation of Neural Stem Cell-Loaded Hydrogels Forms Region-Specific Neuroepithelium

A combinatorial approach integrating stem cells and capable of exploiting available cues is likely needed to regenerate lost neural tissues and ultimately restore neurologic functions. This study investigates the effects of the subcutaneous maturation of adult-derived neural stem cell (aNSCs) seeded into biomaterial constructs on aNSC differentiation and ultimate regional neuronal identity as a first step toward a future spinal cord injury treatment. To achieve this, we encapsulated rat aNSCs in chitosan-based hydrogels functionalized with immobilized azide-tagged interferon-γ inside a chitosan conduit. Then, we implanted these constructs in the subcutaneous tissues in the backs of rats in the cervical, thoracic, and lumbar regions for 4, 6, and 8 weeks. After harvesting the scaffolds, we analyzed cell differentiation qualitatively using immunohistochemical analysis and quantitatively using RT-qPCR. Results revealed that the hydrogels supported aNSC survival and differentiation up to 4 weeks in the subcutaneous environment as marked by the expression of several neurogenesis markers. Most interesting, the aNSCs expressed region-specific Hox genes corresponding to their region of implantation. This study lays the groundwork for further translational work to recapitulate the potentially undiscovered patterning cues in the subcutaneous tissue and provide support for the conceptual premise that our bioengineering approach can form caudalized region-specific neuroepithelium.

The microenvironment following oxygen glucose deprivation/re-oxygenation-induced BSCB damage in vitro

OBJECTIVE

To characterize the microenvironment following blood-spinal cord barrier (BSCB) damage and to evaluate the role of BSCB disruption in secondary damage of spinal cord injury (SCI).

METHODS

A model of BSCB damage was established by co-culture of primary microvascular endothelial cells and glial cells obtained from rat spinal cord tissue followed by oxygen glucose deprivation/re-oxygenation (OGD/R). Permeability was evaluated by measuring the transendothelial electrical resistance (TEER) and the leakage test of Fluorescein isothiocyanate-dextran (FITC-dextran). The expression of tight junction (TJ) proteins (occludin and zonula occludens-1 (ZO-1) were evaluated by Western blot and immunofluorescence microscopy. Proinflammatory factors (TNF-α, iNOS, COX-2 and IL-1β), leukocyte chemotactic factors (MIP-1α, MIP-1β) and leukocyte adhesion factors (ICAM-1, VCAM-1) were detected in the culture medium under different conditions by enzyme-linked immuno sorbent assay (ELISA).

RESULTS

The model of BSCB damage induced by OGD/R was successfully constructed. The maximum BSCB permeability occurred 6-12 hours but not within the first 3 h after OGD/R-induced damage. Likewise, the most significant period of TJ protein loss was also detected 6-12 hours after induction. During the hyper-acute period (3 h) following OGD/R-induced damage of BSCB, leukocyte chemotactic factors and leukocyte adhesion factors were significantly increased in the BSCB model. Pro-inflammation factors (TNF-α, IL-1β, iNOS, COX-2), leukocyte chemotactic factors (MIP-1α, MIP-1β) and leukocyte adhesion factors (ICAM-1, VCAM-1) were also sharply produced during the acute period (3-6 hours) and maintained plateau levels 6-12 hours following OGD/R-induced damage, which overlapped with the period of BSCB permeability maximum. A negative linear correlation was observed between the abundance of proinflammatory factors and the expression of TJ proteins (ZO-1 and occludin) and transepithelial electrical resistance (TEER), and a positive linear correlation was found with transendothelial FITC-dextran.

CONCLUSIONS

Secondary damage continues after primary BSCB damage induced by OGD/R, exhibiting close ties with inflammation injury.