MicroRNA-92a-CPEB3 axis protects neurons against inflammatory neurodegeneration

Neuroinflammation causes neuronal injury in multiple sclerosis (MS) and other neurological diseases. MicroRNAs (miRNAs) are important modulators of neuronal stress responses, but knowledge about their contribution to neuronal protection or damage during inflammation is limited. Here, we constructed a regulatory miRNA-mRNA network of inflamed motor neurons by leveraging cell type-specific miRNA and mRNA sequencing of mice undergoing experimental autoimmune encephalomyelitis (EAE). We found robust induction of miR-92a in inflamed spinal cord neurons and identified cytoplasmic polyadenylation element-binding protein 3 (Cpeb3) as a key target of miR-92a-mediated posttranscriptional silencing. We detected CPEB3 repression in inflamed neurons in murine EAE and human MS. Moreover, both miR-92a delivery and Cpeb3 deletion protected neuronal cultures against excitotoxicity. Supporting a detrimental effect of Cpeb3 in vivo, neuron-specific deletion in conditional Cpeb3 knockout animals led to reduced inflammation-induced clinical disability in EAE. Together, we identified a neuroprotective miR-92a-Cpeb3 axis in neuroinflammation that might serve as potential treatment target to limit inflammation-induced neuronal damage.

Human isogenic cells of the neurovascular unit exert transcriptomic cell type-specific effects on a blood-brain barrier in vitro model of late-onset Alzheimer disease

BACKGROUND

The function of the blood-brain barrier (BBB) is impaired in late-onset Alzheimer disease (LOAD), but the associated molecular mechanisms, particularly with respect to the high-risk APOE4/4 genotype, are not well understood. For this purpose, we developed a multicellular isogenic model of the neurovascular unit (NVU) based on human induced pluripotent stem cells.

METHODS

The human NVU was modeled in vitro using isogenic co-cultures of astrocytes, brain capillary endothelial-like cells (BCECs), microglia-like cells, neural stem cells (NSCs), and pericytes. Physiological and pathophysiological properties were investigated as well as the influence of each single cell type on the characteristics and function of BCECs. The barriers established by BCECs were analyzed for specific gene transcription using high-throughput quantitative PCR.

RESULTS

Co-cultures were found to tighten the barrier of BCECs and alter its transcriptomic profile under both healthy and disease conditions. In vitro differentiation of brain cell types that constitute the NVU was not affected by the LOAD background. The supportive effect of NSCs on the barrier established by BCECs was diminished under LOAD conditions. Transcriptomes of LOAD BCECs were modulated by different brain cell types. NSCs were found to have the strongest effect on BCEC gene regulation and maintenance of the BBB. Co-cultures showed cell type-specific functional contributions to BBB integrity under healthy and LOAD conditions.

CONCLUSIONS

Cell type-dependent transcriptional effects on LOAD BCECs were identified. Our study suggests that different brain cell types of the NVU have unique roles in maintaining barrier integrity that vary under healthy and LOAD conditions. .

The mechanism of macroautophagy: The movie

This animated movie presents the mechanism of macroautophagy, hereafter autophagy, by showing the molecular features of the formation of autophagosomes, the hallmark organelle of this intracellular catabolic pathway. It is based on our current knowledge and it also illustrates how autophagosomes can recognize and eliminate selected cargoes.

High-content screening of mitochondrial polarization in neural cells derived from human pluripotent stem cells

We present a high-content screening (HCS) protocol for quantifying mitochondrial activity in live neural cells from human induced pluripotent stem cells (iPSCs). The assessment is based on mitochondrial membrane potential, which is influenced by the efficiency of mitochondrial bioenergetics. We describe how to perform the analysis using both an HCS platform and the open-source software CellProfiler. The protocol can identify the mitochondrial fitness of human neurons and may be used to carry out high-throughput compound screenings in patient-derived neural cells.

For complete details on the use and execution of this protocol, please refer to Lorenz et al. (2017) and Zink et al. (2020).

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High-content screening (HCS) of live neural cells derived from human iPSCs

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Assessment of mitochondrial activity based on mitochondrial membrane potential (MMP)

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Quantification using automated microscopic image analysis

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Data analysis using both an HCS system and the open-source software CellProfiler

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

G9a dictates neuronal vulnerability to inflammatory stress via transcriptional control of ferroptosis

Neuroinflammation leads to neuronal stress responses that contribute to neuronal dysfunction and loss. However, treatments that stabilize neurons and prevent their destruction are still lacking. Here, we identify the histone methyltransferase G9a as a druggable epigenetic regulator of neuronal vulnerability to inflammation. In murine experimental autoimmune encephalomyelitis (EAE) and human multiple sclerosis (MS), we found that the G9a-catalyzed repressive epigenetic mark H3K9me2 was robustly induced by neuroinflammation. G9a activity repressed anti-ferroptotic genes, diminished intracellular glutathione levels, and triggered the iron-dependent programmed cell death pathway ferroptosis. Conversely, pharmacological treatment of EAE mice with a G9a inhibitor restored anti-ferroptotic gene expression, reduced inflammation-induced neuronal loss, and improved clinical outcome. Similarly, neuronal anti-ferroptotic gene expression was reduced in MS brain tissue and was boosted by G9a inhibition in human neuronal cultures. This study identifies G9a as a critical transcriptional enhancer of neuronal ferroptosis and potential therapeutic target to counteract inflammation-induced neurodegeneration.

IMMU-02. Targeted innovative antibody fragment-based immunotherapy for medulloblastoma

Medulloblastoma (MB) is the most common malignant pediatric brain tumor accounting for ~20 % of childhood brain tumors. One third of all MB are characterized by constitutive activation of the Sonic Hedgehog (SHH)-signaling pathway. This tumor type shows overexpression of the epidermal growth-factor receptor (EGFR), which we detected in SHH-MB patient samples, transgenic SHH MB mouse models, and MB-cell lines. In contrast, non-neoplastic cells only express EGFR at low levels. Intensive radio-/chemotherapy often leaves the young patients with significant long-term burdens including problems in brain development and cognitive deficits. Thus, there is an urgent need to develop new targeted therapies that can prevent tumor recurrence without affecting healthy cells. We selected EGFR as a potential therapy target using EGFR-specific antibody fragments (scFvs) as part of immunoconjugates, namely bispecific T-cell engagers (BiTEs) and immunotoxins (ITs). Both, the EGFR-specific BiTEs and the ITs showed specific binding and cytotoxic activity in MB cells. Effector- and target-cell specificity was demonstrated via flow cytometry for the BiTEs. BiTEs and ITs selectively killed MB-tumor cells and showed pro-apoptotic effects without unspecific effects. Furthermore, preliminary results from an innovative hiPSC-based in vitro-BBB-model suggest, that the ITs are able to cross the BBB. Finally, by having a functional cloning- and expression system for the BiTEs and ITs available, target-scFvs can be easily exchanged by novel antigens or peptides to obtain additional targeted immunotherapies. Together, these results pave the way for preclinical in vivo experiments and future clinical trials in patients with SHH MB.

The blood-brain barrier is dysregulated in COVID-19 and serves as a CNS entry route for SARS-CoV-2

Neurological complications are common in COVID-19. Although SARS-CoV-2 has been detected in patients’ brain tissues, its entry routes and resulting consequences are not well understood. Here, we show a pronounced upregulation of interferon signaling pathways of the neurovascular unit in fatal COVID-19. By investigating the susceptibility of human induced pluripotent stem cell (hiPSC)-derived brain capillary endothelial-like cells (BCECs) to SARS-CoV-2 infection, we found that BCECs were infected and recapitulated transcriptional changes detected in vivo. While BCECs were not compromised in their paracellular tightness, we found SARS-CoV-2 in the basolateral compartment in transwell assays after apical infection, suggesting active replication and transcellular transport of virus across the blood-brain barrier (BBB) in vitro. Moreover, entry of SARS-CoV-2 into BCECs could be reduced by anti-spike-, anti-angiotensin-converting enzyme 2 (ACE2)-, and anti-neuropilin-1 (NRP1)-specific antibodies or the transmembrane protease serine subtype 2 (TMPRSS2) inhibitor nafamostat. Together, our data provide strong support for SARS-CoV-2 brain entry across the BBB resulting in increased interferon signaling.

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IFNγ signaling is upregulated in COVID-19 human neurovascular unit

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SARS-CoV-2-infected hiPS-BCECs display similar upregulation of IFNγ signaling

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SARS-CoV-2 replicates in hiPS-BCECs and is released while barrier remains intact

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SARS-CoV-2 infection of hiPS-BCECs is decreased by antibodies and protease inhibitors

Culturing human iPSC-derived neural progenitor cells on nanowire arrays: mapping the impact of nanowire length and array pitch on proliferation, viability, and membrane deformation

Nanowire arrays used as cell culture substrates build a potent tool for advanced biological applications such as cargo delivery and biosensing. The unique topography of nanowire arrays, however, renders them a challenging growth environment for cells and explains why only basic cell lines have been employed in existing studies. Here, we present the culturing of human induced pluripotent stem cell-derived neural progenitor cells on rectangularly arranged nanowire arrays: In detail, we mapped the impact on proliferation, viability, and topography-induced membrane deformation across a multitude of array pitches (1, 3, 5, 10 μm) and nanowire lengths (1.5, 3, 5 μm). Against the intuitive expectation, a reduced proliferation was found on the arrays with the smallest array pitch of 1 μm and long NWs. Typically, cells settle in a fakir-like state on such densely-spaced nanowires and thus experience no substantial stress caused by nanowires indenting the cell membrane. However, imaging of F-actin showed a distinct reorganization of the cytoskeleton along the nanowire tips in the case of small array pitches interfering with regular proliferation. For larger pitches, the cell numbers depend on the NW lengths but proliferation generally continued although heavy deformations of the cell membrane were observed caused by the encapsulation of the nanowires. Moreover, we noticed a strong interaction of the nanowires with the nucleus in terms of squeezing and indenting. Remarkably, the cell viability is maintained at about 85% despite the massive deformation of the cells. Considering the enormous potential of human induced stem cells to study neurodegenerative diseases and the high cellular viability combined with a strong interaction with nanowire arrays, we believe that our results pave the way to apply nanowire arrays to human stem cells for future applications in stem cell research and regenerative medicine.

Droplet-based vitrification of adherent human induced pluripotent stem cells on alginate microcarrier influenced by adhesion time and matrix elasticity

The gold standard in cryopreservation is still conventional slow freezing of single cells or small aggregates in suspension, although major cell loss and limitation to non-specialised cell types in stem cell technology are known drawbacks. The requirement for rapidly available therapeutic and diagnostic cell types is increasing constantly. In the case of human induced pluripotent stem cells (hiPSCs) or their derivates, more sophisticated cryopreservation protocols are needed to address this demand. These should allow a preservation in their physiological, adherent state, an efficient re-cultivation and upscaling upon thawing towards high-throughput applications in cell therapies or disease modelling in drug discovery. Here, we present a novel vitrification-based method for adherent hiPSCs, designed for automated handling by microfluidic approaches and with ready-to-use potential e.g. in suspension-based bioreactors after thawing. Modifiable alginate microcarriers serve as a growth surface for adherent hiPSCs that were cultured in a suspension-based bioreactor and subsequently cryopreserved via droplet-based vitrification in comparison to conventional slow freezing. Soft (0.35%) versus stiff (0.65%) alginate microcarriers in concert with adhesion time variation have been examined. Findings revealed specific optimal conditions leading to an adhesion time and growth surface (matrix) elasticity dependent hypothesis on cryo-induced damaging regimes for adherent cell types. Deviations from the found optimum parameters give rise to membrane ruptures assessed via SEM and major cell loss after adherent vitrification. Applying the optimal conditions, droplet-based vitrification was superior to conventional slow freezing. A decreased microcarrier stiffness was found to outperform stiffer material regarding cell recovery, whereas the stemness characteristics of rewarmed hiPSCs were preserved.

Human iPSC-Derived Blood-Brain Barrier Models: Valuable Tools for Preclinical Drug Discovery and Development?

Translating basic biological knowledge into applications remains a key issue for effectively tackling neurodegenerative, neuroinflammatory, or neuroendocrine disorders. Efficient delivery of therapeutics across the neuroprotective blood-brain barrier (BBB) still poses a demanding challenge for drug development targeting central nervous system diseases. Validated in vitro models of the BBB could facilitate effective testing of drug candidates targeting the brain early in the drug discovery process during lead generation. We here review the potential of mono- or (isogenic) co-culture BBB models based on brain capillary endothelial cells (BCECs) derived from human-induced pluripotent stem cells (hiPSCs), and compare them to several available BBB in vitro models from primary human or non-human cells and to rodent in vivo models, as well as to classical and widely used barrier models [Caco-2, parallel artificial membrane permeability assay (PAMPA)]. In particular, we are discussing the features and predictivity of these models and how hiPSC-derived BBB models could impact future discovery and development of novel CNS-targeting therapeutics. © 2020 The Authors.

Targeting autophagy in disease: established and new strategies

Macroautophagy/autophagy is an evolutionarily conserved pathway responsible for clearing cytosolic aggregated proteins, damaged organelles or invading microorganisms. Dysfunctional autophagy leads to pathological accumulation of the cargo, which has been linked to a range of human diseases, including neurodegenerative diseases, infectious and autoimmune diseases and various forms of cancer. Cumulative work in animal models, application of genetic tools and pharmacologically active compounds, has suggested the potential therapeutic value of autophagy modulation in disease, as diverse as Huntington, Salmonella infection, or pancreatic cancer. Autophagy activation versus inhibition strategies are being explored, while the role of autophagy in pathophysiology is being studied in parallel. However, the progress of preclinical and clinical development of autophagy modulators has been greatly hampered by the paucity of selective pharmacological agents and biomarkers to dissect their precise impact on various forms of autophagy and cellular responses. Here, we summarize established and new strategies in autophagy-related drug discovery and indicate a path toward establishing a more efficient discovery of autophagy-selective pharmacological agents. With this knowledge at hand, modern concepts for therapeutic exploitation of autophagy might become more plausible.

Abbreviations: ALS: amyotrophic lateral sclerosis; AMPK: AMP-activated protein kinase; ATG: autophagy-related gene; AUTAC: autophagy-targeting chimera; CNS: central nervous system; CQ: chloroquine; GABARAP: gamma-aminobutyric acid type A receptor-associated protein; HCQ: hydroxychloroquine; LYTAC: lysosome targeting chimera; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NDD: neurodegenerative disease; PDAC: pancreatic ductal adenocarcinoma; PE: phosphatidylethanolamine; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; PROTAC: proteolysis-targeting chimera; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1.

Neuronal metabotropic glutamate receptor 8 protects against neurodegeneration in CNS inflammation

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with continuous neuronal loss. Treatment of clinical progression remains challenging due to lack of insights into inflammation-induced neurodegenerative pathways. Here, we show that an imbalance in the neuronal receptor interactome is driving glutamate excitotoxicity in neurons of MS patients and identify the MS risk-associated metabotropic glutamate receptor 8 (GRM8) as a decisive modulator. Mechanistically, GRM8 activation counteracted neuronal cAMP accumulation, thereby directly desensitizing the inositol 1,4,5-trisphosphate receptor (IP3R). This profoundly limited glutamate-induced calcium release from the endoplasmic reticulum and subsequent cell death. Notably, we found Grm8-deficient neurons to be more prone to glutamate excitotoxicity, whereas pharmacological activation of GRM8 augmented neuroprotection in mouse and human neurons as well as in a preclinical mouse model of MS. Thus, we demonstrate that GRM8 conveys neuronal resilience to CNS inflammation and is a promising neuroprotective target with broad therapeutic implications.

Enhancing mitochondrial activity in neurons protects against neurodegeneration in a mouse model of multiple sclerosis

While transcripts of neuronal mitochondrial genes are strongly suppressed in central nervous system inflammation, it is unknown whether this results in mitochondrial dysfunction and whether an increase of mitochondrial function can rescue neurodegeneration. Here, we show that predominantly genes of the electron transport chain are suppressed in inflamed mouse neurons, resulting in impaired mitochondrial complex IV activity. This was associated with post-translational inactivation of the transcriptional co-regulator proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In mice, neuronal overexpression of Ppargc1a, which encodes for PGC-1α, led to increased numbers of mitochondria, complex IV activity, and maximum respiratory capacity. Moreover, Ppargc1a-overexpressing neurons showed a higher mitochondrial membrane potential that related to an improved calcium buffering capacity. Accordingly, neuronal deletion of Ppargc1a aggravated neurodegeneration during experimental autoimmune encephalomyelitis, while neuronal overexpression of Ppargc1a ameliorated it. Our study provides systemic insights into mitochondrial dysfunction in neurons during inflammation and commends elevation of mitochondrial activity as a promising neuroprotective strategy.

An automated and high-throughput-screening compatible pluripotent stem cell-based test platform for developmental and reproductive toxicity assessment of small molecule compounds

The embryonic stem cell test (EST) represents the only validated and accepted in vitro system for the detection and classification of compounds according to their developmental and reproductive teratogenic potency. The widespread implementation of the EST, however, in particular for routine application in pharmaceutical development, has not been achieved so far. Several drawbacks still limit the high-throughput screening of potential drug candidates in this format: The long assay period, the use of non-homogeneous viability assays, the low throughput analysis of marker protein expression and the compatibility of the assay procedures to automation. We have therefore introduced several advancements into the EST workflow: A reduction of the assay period, an introduction of homogeneous viability assays, and a straightforward analysis of marker proteins by flow cytometry and high content imaging to assess the impact of small molecules on differentiation capacity. Most importantly, essential parts of the assay procedure have been adapted to lab automation in 96-well format, thus enabling the interrogation of several compounds in parallel. In addition, extensive investigations were performed to explore the predictive capacity of this next-generation EST, by testing a set of well-known embryotoxicants that encompasses the full range of chemical-inherent embryotoxic potencies possible. Due to these significant improvements, the augmented workflow provides a basis for a sensitive, more rapid, and reproducible high throughput screening compatible platform to predict in vivo developmental toxicity from in vitro data which paves the road towards application in an industrial setting.

Graphical abstract

Interfacing human induced pluripotent stem cell-derived neurons with designed nanowire arrays as a future platform for medical applications

Nanostructured substrates such as nanowire arrays form a powerful tool for building next-generation medical devices.

Automated real-time monitoring of human pluripotent stem cell aggregation in stirred tank reactors

The culture of human induced pluripotent stem cells (hiPSCs) at large scale becomes feasible with the aid of scalable suspension setups in continuously stirred tank reactors (CSTRs). Innovative monitoring options and emerging automated process control strategies allow for the necessary highly defined culture conditions. Next to standard process characteristics such as oxygen consumption, pH, and metabolite turnover, a reproducible and steady formation of hiPSC aggregates is vital for process scalability. In this regard, we developed a hiPSC-specific suspension culture unit consisting of a fully monitored CSTR system integrated into a custom-designed and fully automated incubator. As a step towards cost-effective hiPSC suspension culture and to pave the way for flexibility at a large scale, we constructed and utilized tailored miniature CSTRs that are largely made from three-dimensional (3D) printed polylactic acid (PLA) filament, which is a low-cost material used in fused deposition modelling. Further, the monitoring tool for hiPSC suspension cultures utilizes in situ microscopic imaging to visualize hiPSC aggregation in real-time to a statistically significant degree while omitting the need for time-intensive sampling. Suitability of our culture unit, especially concerning the developed hiPSC-specific CSTR system, was proven by demonstrating pluripotency of CSTR-cultured hiPSCs at RNA (including PluriTest) and protein level.

Driving next-generation autophagy researchers towards translation (DRIVE), an international PhD training program on autophagy

The European autophagy consortium Driving next-generation autophagy researchers towards translation (DRIVE) held its kick-off meeting in Groningen on the 14th and 15th of June 2018. This Marie Skłodowska-Curie Early Training Network was approved under the European Union's Horizon 2020 Research and Innovation Program and is funded for 4 years. Within DRIVE, 14 European research teams from academia and industry will train 15 PhD students through applied, cross-disciplinary and collaborative macroautophagy/autophagy research. The goal of DRIVE is to stimulate applied approaches in autophagy research and provide training towards translation, while advancing our knowledge on autophagy in specific physiological and pathological states. The strong focus on translation will prepare the PhD students to be at the forefront to exploit autophagy for the development of therapies directly benefitting patients. Thereby, DRIVE will contribute to filling the educational gap that currently exists between academia and industry, and will prepare its PhD students for alternative and highly flexible professional paths.

Generation of two human isogenic iPSC lines from fetal dermal fibroblasts

Two isogenic hiPSC lines, ZIPi013-B and ZIPi013-E, were generated by reprogramming fetal dermal fibroblasts with episomal vectors. Previously, the same fetal fibroblasts were reprogrammed multiple times in a study comparing other reprogramming methods. As a consequence, the genomes have been sequenced multiple times. Both new cell lines offer the opportunity to study basic stem cell biology and model human disease. They can be applied as reference cell lines for creating isogenic clones bearing disease mutations on a well-characterized genomic background, as both cell lines have demonstrated excellent differentiation capacity in multiple labs. Resource table.

Metabolomic Profiles for Primary Progressive Multiple Sclerosis Stratification and Disease Course Monitoring

Primary progressive multiple sclerosis (PPMS) shows a highly variable disease progression with poor prognosis and a characteristic accumulation of disabilities in patients. These hallmarks of PPMS make it difficult to diagnose and currently impossible to efficiently treat. This study aimed to identify plasma metabolite profiles that allow diagnosis of PPMS and its differentiation from the relapsing-remitting subtype (RRMS), primary neurodegenerative disease (Parkinson’s disease, PD), and healthy controls (HCs) and that significantly change during the disease course and could serve as surrogate markers of multiple sclerosis (MS)-associated neurodegeneration over time. We applied untargeted high-resolution metabolomics to plasma samples to identify PPMS-specific signatures, validated our findings in independent sex- and age-matched PPMS and HC cohorts and built discriminatory models by partial least square discriminant analysis (PLS-DA). This signature was compared to sex- and age-matched RRMS patients, to patients with PD and HC. Finally, we investigated these metabolites in a longitudinal cohort of PPMS patients over a 24-month period. PLS-DA yielded predictive models for classification along with a set of 20 PPMS-specific informative metabolite markers. These metabolites suggest disease-specific alterations in glycerophospholipid and linoleic acid pathways. Notably, the glycerophospholipid LysoPC(20:0) significantly decreased during the observation period. These findings show potential for diagnosis and disease course monitoring, and might serve as biomarkers to assess treatment efficacy in future clinical trials for neuroprotective MS therapies.

A standardised frankincense extract reduces disease activity in relapsing-remitting multiple sclerosis (the SABA phase IIa trial)

OBJECTIVE

To investigate whether oral administration of a standardised frankincense extract (SFE) is safe and reduces disease activity in patients with relapsing-remitting multiple sclerosis (RRMS).

METHODS

We performed an investigator-initiated, bicentric phase IIa, open-label, baseline-to-treatment pilot study with an oral SFE in patients with RRMS (NCT01450124). After a 4-month baseline observation phase, patients were treated for 8 months with an option to extend treatment for up to 36 months. The primary outcome measures were the number and volume of contrast-enhancing lesions (CEL) measured in MRI during the 4-month treatment period compared with the 4-month baseline period. Eighty patients were screened at two centres, 38 patients were included in the trial, 28 completed the 8-month treatment period and 18 of these participated in the extension period.

RESULTS

The SFE significantly reduced the median number of monthly CELs from 1.00 (IQR 0.75-3.38) to 0.50 (IQR 0.00-1.13; difference -0.625, 95% CI -1.25 to -0.50; P<0.0001) at months 5-8. We observed significantly less brain atrophy as assessed by parenchymal brain volume change (P=0.0081). Adverse events were generally mild (57.7%) or moderate (38.6%) and comprised mainly gastrointestinal symptoms and minor infections. Mechanistic studies showed a significant increase in regulatory CD4+ T cell markers and a significant decrease in interleukin-17A-producing CD8+ T cells indicating a distinct mechanism of action of the study drug.

INTERPRETATION

The oral SFE was safe, tolerated well and exhibited beneficial effects on RRMS disease activity warranting further investigation in a controlled phase IIb or III trial.

CLINICAL TRIAL REGISTRATION

NCT01450124; Results.

T Cell Phenotype and T Cell Receptor Repertoire in Patients with Major Depressive Disorder

While a link between inflammation and the development of neuropsychiatric disorders, including major depressive disorder (MDD) is supported by a growing body of evidence, little is known about the contribution of aberrant adaptive immunity in this context. Here, we conducted in-depth characterization of T cell phenotype and T cell receptor (TCR) repertoire in MDD. For this cross-sectional case–control study, we recruited antidepressant-free patients with MDD without any somatic or psychiatric comorbidities (n = 20), who were individually matched for sex, age, body mass index, and smoking status to a non-depressed control subject (n = 20). T cell phenotype and repertoire were interrogated using a combination of flow cytometry, gene expression analysis, and next generation sequencing. T cells from MDD patients showed significantly lower surface expression of the chemokine receptors CXCR3 and CCR6, which are known to be central to T cell differentiation and trafficking. In addition, we observed a shift within the CD4⁺ T cell compartment characterized by a higher frequency of CD4⁺CD25^highCD127^low/− cells and higher FOXP3 mRNA expression in purified CD4⁺ T cells obtained from patients with MDD. Finally, flow cytometry-based TCR Vβ repertoire analysis indicated a less diverse CD4⁺ T cell repertoire in MDD, which was corroborated by next generation sequencing of the TCR β chain CDR3 region. Overall, these results suggest that T cell phenotype and TCR utilization are skewed on several levels in patients with MDD. Our study identifies putative cellular and molecular signatures of dysregulated adaptive immunity and reinforces the notion that T cells are a pathophysiologically relevant cell population in this disorder.

Evaluation of MYBPC3 trans-Splicing and Gene Replacement as Therapeutic Options in Human iPSC-Derived Cardiomyocytes

Gene therapy is a promising option for severe forms of genetic diseases. We previously provided evidence for the feasibility of trans-splicing, exon skipping, and gene replacement in a mouse model of hypertrophic cardiomyopathy (HCM) carrying a mutation in MYBPC3, encoding cardiac myosin-binding protein C (cMyBP-C). Here we used human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from an HCM patient carrying a heterozygous c.1358-1359insC MYBPC3 mutation and from a healthy donor. HCM hiPSC-CMs exhibited ∼50% lower MYBPC3 mRNA and cMyBP-C protein levels than control, no truncated cMyBP-C, larger cell size, and altered gene expression, thus reproducing human HCM features. We evaluated RNA trans-splicing and gene replacement after transducing hiPSC-CMs with adeno-associated virus. trans-splicing with 5' or 3' pre-trans-splicing molecules represented ∼1% of total MYBPC3 transcripts in healthy hiPSC-CMs. In contrast, gene replacement with the full-length MYBPC3 cDNA resulted in ∼2.5-fold higher MYBPC3 mRNA levels in HCM and control hiPSC-CMs. This restored the cMyBP-C level to 81% of the control level, suppressed hypertrophy, and partially restored gene expression to control level in HCM cells. This study provides evidence for (1) the feasibility of trans-splicing, although with low efficiency, and (2) efficient gene replacement in hiPSC-CMs with a MYBPC3 mutation.

Rapid establishment of the European Bank for induced Pluripotent Stem Cells (EBiSC) - the Hot Start experience

A fast track "Hot Start" process was implemented to launch the European Bank for Induced Pluripotent Stem Cells (EBiSC) to provide early release of a range of established control and disease linked human induced pluripotent stem cell (hiPSC) lines. Established practice amongst consortium members was surveyed to arrive at harmonised and publically accessible Standard Operations Procedures (SOPs) for tissue procurement, bio-sample tracking, iPSC expansion, cryopreservation, qualification and distribution to the research community. These were implemented to create a quality managed foundational collection of lines and associated data made available for distribution. Here we report on the successful outcome of this experience and work flow for banking and facilitating access to an otherwise disparate European resource, with lessons to benefit the international research community. ETOC: The report focuses on the EBiSC experience of rapidly establishing an operational capacity to procure, bank and distribute a foundational collection of established hiPSC lines. It validates the feasibility and defines the challenges of harnessing and integrating the capability and productivity of centres across Europe using commonly available resources currently in the field.

Arc/Arg3.1 governs inflammatory dendritic cell migration from the skin and thereby controls T cell activation

Skin-migratory dendritic cells (migDCs) are pivotal antigen-presenting cells that continuously transport antigens to draining lymph nodes and regulate immune responses. However, identification of migDCs is complicated by the lack of distinguishing markers, and it remains unclear which molecules determine their migratory capacity during inflammation. We show that, in the skin, the neuronal plasticity molecule activity-regulated cytoskeleton-associated protein/activity-regulated gene 3.1 (Arc/Arg3.1) was strictly confined to migDCs. Mechanistically, Arc/Arg3.1 was required for accelerated DC migration during inflammation because it regulated actin dynamics through nonmuscle myosin II. Accordingly, Arc/Arg3.1-dependent DC migration was critical for mounting T cell responses in experimental autoimmune encephalomyelitis and allergic contact dermatitis. Thus, Arc/Arg3.1 was restricted to migDCs in the skin and drove fast DC migration by exclusively coordinating cytoskeletal changes in response to inflammatory challenges. These findings commend Arc/Arg3.1 as a universal switch in migDCs that may be exploited to selectively modify immune responses.

Molecular Characterization of the NLRC4 Expression in Relation to Interleukin-18 Levels

BACKGROUND

Interleukin-18 (IL-18) is a pleiotropic cytokine centrally involved in the cytokine cascade with complex immunomodulatory functions in innate and acquired immunity. Circulating IL-18 concentrations are associated with type 2 diabetes mellitus, cardiovascular events, and diverse inflammatory and autoimmune disorders.

METHODS AND RESULTS

To identify causal variants affecting circulating IL-18 concentrations, we applied various omics and molecular biology approaches. By genome-wide association study, we confirmed association of IL-18 levels with a single nucleotide polymorphism in the untranslated exon 2 of the inflammasome component NLRC4 (NLR family, caspase recruitment domain-containing 4) gene on chromosome 2 (rs385076; P=2.4 × 10(-45)). Subsequent molecular analyses by gene expression analysis and reporter gene assays indicated an effect of rs385076 on NLRC4 expression and differential isoform usage by modulating binding of the transcription factor PU.1.

CONCLUSIONS

Our study provides evidence for the functional causality of single nucleotide polymorphism rs385076 within the NLRC4 gene in relation to IL-18 activation.

A multiple sclerosis-associated variant of CBLB links genetic risk with type I IFN function

Multiple sclerosis (MS) is an autoimmune disease of the CNS, and autoreactive CD4(+) T cells are considered important for its pathogenesis. The etiology of MS involves a complex genetic trait and environmental triggers that include viral infections, particularly the EBV. Among the risk alleles that have repeatedly been identified by genome-wide association studies, three are located near the Casitas B-lineage lymphoma proto-oncogene b gene (CBLB). The CBLB protein (CBL-B) is a key regulator of peripheral immune tolerance by limiting T cell activation and expansion and hence T cell-mediated autoimmunity through its ubiquitin E3-ligase activity. In this study, we show that CBL-B expression is reduced in CD4(+) T cells from relapsing-remitting MS (RR-MS) patients during relapse. The MS risk-related single nucleotide polymorphism of CBLB rs12487066 is associated with diminished CBL-B expression levels and alters the effects of type I IFNs on human CD4(+) T cell proliferation. Mechanistically, the CBLB rs12487066 risk allele mediates increased binding of the transcription factor C/EBPβ and reduced CBL-B expression in human CD4(+) T cells. Our data suggest a role of the CBLB rs12487066 variant in the interactions of a genetic risk factor and IFN function during viral infections in MS.

Functional role of the interaction between polysialic acid and myristoylated alanine-rich C kinase substrate at the plasma membrane

Polysialic acid (PSA) is a homopolymeric glycan that plays crucial roles in the developing and adult nervous system. So far only a few PSA-binding proteins have been identified. Here, we identify myristoylated alanine-rich C kinase substrate (MARCKS) as novel PSA binding partner. Binding assays showed a direct interaction between PSA and a peptide comprising the effector domain of MARCKS (MARCKS-ED). Co-immunoprecipitation of PSA-carrying neural cell adhesion molecule (PSA-NCAM) with MARCKS and co-immunostaining of MARCKS and PSA at the cell membrane of hippocampal neurons confirm the interaction between PSA and MARCKS. Co-localization and an intimate interaction of PSA and MARCKS at the cell surface was seen by confocal microscopy and fluorescence resonance energy transfer (FRET) analysis after the addition of fluorescently labeled PSA or PSA-NCAM to live CHO cells or hippocampal neurons expressing MARCKS as a fusion protein with green fluorescent protein (GFP). Cross-linking experiments showed that extracellularly applied PSA or PSA-NCAM and intracellularly expressed MARCKS-GFP are in close contact, suggesting that PSA and MARCKS interact with each other at the plasma membrane from opposite sides. Insertion of PSA and MARCKS-ED peptide into lipid bilayers from opposite sides alters the electric properties of the bilayer confirming the notion that PSA and the effector domain of MARCKS interact at and/or within the plane of the membrane. The MARCKS-ED peptide abolished PSA-induced enhancement of neurite outgrowth from cultured hippocampal neurons indicating an important functional role for the interaction between MARCKS and PSA in the developing and adult nervous system.

Crosstalk between phosphorylation and multi-site arginine/lysine methylation in C/EBPs

C/EBPs are implied in an amazing number of cellular functions: C/EBPs regulate tissue and cell type specific gene expression, proliferation, and differentiation control. C/EBPs assist in energy metabolism, female reproduction, innate immunity, inflammation, senescence, and the development of neoplasms. How can C/EBPs fulfill so many functions? Here we discuss that C/EBPs are extensively modified by methylation of arginine and lysine side chains and that regulated methylation profoundly affects the activity of C/EBPs.

A differential proteome screening system for post-translational modification-dependent transcription factor interactions

Post-translational modifications (PTMs) of transcription factors alter interactions with co-regulators and epigenetic modifiers. For example, members of the C/EBP transcription factor family are extensively methylated on arginine and lysine residues in short, conserved, modular domains, implying modification-dependent cofactor docking. Here we describe array peptide screening (APS), a systematic and differential approach to detect PTM-dependent interactions in the human proteome using chemically synthesized, biotinylated peptides coupled to fluorophore-labeled streptavidin. Peptides with and without a modified residue are applied in parallel to bacterial expression libraries in an arrayed format. Interactions are detected and quantified by laser scanning to reveal proteins that differentially bind to nonmodified or modified peptides. We have previously used this method to investigate the effect of arginine methylation of C/EBPβ peptides. The method enables determination of PTM-dependent transcription factor interactions, quantification of relative binding affinities and rapid protein classification, all independently of the transactivation potential of peptides or cellular abundance of interactors. The protocol provides a cost-effective alternative to mass spectrometric approaches and takes 3-4 d to complete.

Targets of the Tal1 transcription factor in erythrocytes: E2 ubiquitin conjugase regulation by Tal1

The Tal1 transcription factor is essential for the development of the hematopoietic system and plays a role during definitive erythropoiesis in the adult. Despite the importance of Tal1 in erythropoiesis, only a small number of erythroid differentiation target genes are known. A chromatin precipitation and cloning approach was established to uncover novel Tal1 target genes in erythropoiesis. The BirA tag/BirA ligase biotinylation system in combination with streptavidin chromatin precipitation (Strep-CP) was used to co-precipitate genomic DNA bound to Tal1. Tal1 was found to bind in the vicinity of 31 genes including the E2-ubiquitin conjugase UBE2H gene. Binding of Tal1 to UBE2H was confirmed by chromatin immunoprecipitation. UBE2H expression is increased during erythroid differentiation of hCD34(+) cells. Tal1 expression activated UBE2H expression, whereas Tal1 knock-down reduced UBE2H expression and ubiquitin transfer activity. This study identifies parts of the ubiquitinylation machinery as a cellular target downstream of the transcription factor Tal1 and provides novel insights into Tal1-regulated erythropoiesis.

G9a-mediated lysine methylation alters the function of CCAAT/enhancer-binding protein-beta

The functional capacity of the transcriptional regulatory CCAAT/enhancer-binding protein-beta (C/EBPbeta) is governed by protein interactions and post-translational protein modifications. In a proteome-wide interaction screen, the histone-lysine N-methyltransferase, H3 lysine 9-specific 3 (G9a), was found to directly interact with the C/EBPbeta transactivation domain (TAD). Binding between G9a and C/EBPbeta was confirmed by glutathione S-transferase pulldown and co-immunoprecipitation. Metabolic labeling showed that C/EBPbeta is post-translationally modified by methylation in vivo. A conserved lysine residue in the C/EBPbeta TAD served as a substrate for G9a-mediated methylation. G9a, but not a methyltransferase-defective G9a mutant, abrogated the transactivation potential of wild type C/EBPbeta. A C/EBPbeta TAD mutant that contained a lysine-to-alanine exchange was resistant to G9a-mediated inhibition. Moreover, the same mutation conferred super-activation of a chromatin-embedded, endogenous C/EBPbeta target gene. Our data identify C/EBPbeta as a direct substrate of G9a-mediated post-translational modification that alters the functional properties of C/EBPbeta during gene regulation.