The new missense G376V-TDP-43 variant induces late-onset distal myopathy but not amyotrophic lateral sclerosis

TAR DNA binding protein of 43 kDa (TDP-43)-positive inclusions in neurons are a hallmark of several neurodegenerative diseases including familial amyotrophic lateral sclerosis (fALS) caused by pathogenic TARDBP variants as well as more common non-Mendelian sporadic ALS (sALS). Here we report a G376V-TDP-43 missense variant in the C-terminal prion-like domain of the protein in two French families affected by an autosomal dominant myopathy but not fulfilling diagnostic criteria for ALS. Patients from both families presented with progressive weakness and atrophy of distal muscles, starting in their fifth to seventh decade. Muscle biopsies revealed a degenerative myopathy characterized by accumulation of rimmed (autophagic) vacuoles, disruption of sarcomere integrity and severe myofibrillar disorganization. The G376V variant altered a highly conserved amino acid residue and was absent in databases on human genome variation. Variant pathogenicity was supported by in silico analyses and functional studies. The G376V mutant increased the formation of cytoplasmic TDP-43 condensates in cell culture models, promoted assembly into high molecular weight oligomers and aggregates in vitro, and altered morphology of TDP-43 condensates arising from phase separation. Moreover, the variant led to the formation of cytoplasmic TDP-43 condensates in patient-derived myoblasts and induced abnormal mRNA splicing in patient muscle tissue. The identification of individuals with TDP-43-related myopathy, but not ALS, implies that TARDBP missense variants may have more pleiotropic effects than previously anticipated and support a primary role for TDP-43 in skeletal muscle pathophysiology. We propose to include TARDBP screening in the genetic work-up of patients with late-onset distal myopathy. Further research is warranted to examine the precise pathogenic mechanisms of TARDBP variants causing either a neurodegenerative or myopathic phenotype.

Impact of lens autofluorescence and opacification on retinal imaging

BACKGROUND

Retinal imaging, including fundus autofluorescence (FAF), strongly depends on the clearness of the optical media. Lens status is crucial since the ageing lens has both light-blocking and autofluorescence (AF) properties that distort image analysis. Here, we report both lens opacification and AF metrics and the effect on automated image quality assessment.

METHODS

227 subjects (range: 19-89 years old) received quantitative AF of the lens (LQAF), Scheimpflug, anterior chamber optical coherence tomography as well as blue/green FAF (BAF/GAF), and infrared (IR) imaging. LQAF values, the Pentacam Nucleus Staging score and the relative lens reflectivity were extracted to estimate lens opacification. Mean opinion scores of FAF and IR image quality were compiled by medical readers. A regression model for predicting image quality was developed using a convolutional neural network (CNN). Correlation analysis was conducted to assess the association of lens scores, with retinal image quality derived from human or CNN annotations.

RESULTS

Retinal image quality was generally high across all imaging modalities (IR (8.25±1.99) >GAF >BAF (6.6±3.13)). CNN image quality prediction was excellent (average mean absolute error (MAE) 0.9). Predictions were comparable to human grading. Overall, LQAF showed the highest correlation with image quality grading criteria for all imaging modalities (eg, Pearson correlation±CI -0.35 (-0.50 to 0.18) for BAF/LQAF). BAF image quality was most vulnerable to an increase in lenticular metrics, while IR (-0.19 (-0.38 to 0.01)) demonstrated the highest resilience.

CONCLUSION

The use of CNN-based retinal image quality assessment achieved excellent results. The study highlights the vulnerability of BAF to lenticular remodelling. These results can aid in the development of cut-off values for clinical studies, ensuring reliable data collection for the monitoring of retinal diseases.

Alpha-T-catenin is expressed in peripheral nerves as a constituent of Schwann cell adherens junctions

The adherens junction component, alpha-T-catenin (αTcat) is an established contributor to cardiomyocyte junction structure and function, but recent genomic studies link CTNNA3 polymorphisms to diseases with no clear cardiac underpinning, including asthma, autism and multiple sclerosis, suggesting causal contributions from a different cell-type. We show Ctnna3 mRNA is highly expressed in peripheral nerves (e.g. vagus and sciatic), where αTcat protein enriches at paranodes and myelin incisure adherens junctions of Schwann cells. We validate αTcat immunodetection specificity using a new Ctnna3-knock-out fluorescence reporter mouse line yet find no obvious Schwann cell loss-of-function morphology at the light microscopic level. CTNNA3/Ctnna3 mRNA is also abundantly detected in oligodendrocytes of the central nervous system via public databases, supporting a general role for αTcat in these unique cell-cell junctions. These data suggest that the wide range of diseases linked to CTNNA3 may be through its role in maintaining neuroglial functions of central and peripheral nervous systems. This article has a corresponding First Person interview with the co-first authors of the paper.

A hypomorphic mutation in Pold1 disrupts the coordination of embryo size expansion and morphogenesis during gastrulation

Formation of a properly sized and patterned embryo during gastrulation requires a well-coordinated interplay between cell proliferation, lineage specification and tissue morphogenesis. Following transient physical or pharmacological manipulations of embryo size, pre-gastrulation mouse embryos show remarkable plasticity to recover and resume normal development. However, it remains unclear how mechanisms driving lineage specification and morphogenesis respond to defects in cell proliferation during and after gastrulation. Null mutations in DNA replication or cell-cycle-related genes frequently lead to cell-cycle arrest and reduced cell proliferation, resulting in developmental arrest before the onset of gastrulation; such early lethality precludes studies aiming to determine the impact of cell proliferation on lineage specification and morphogenesis during gastrulation. From an unbiased ENU mutagenesis screen, we discovered a mouse mutant, tiny siren (tyrn), that carries a hypomorphic mutation producing an aspartate to tyrosine (D939Y) substitution in Pold1, the catalytic subunit of DNA polymerase δ. Impaired cell proliferation in the tyrn mutant leaves anterior-posterior patterning unperturbed during gastrulation but results in reduced embryo size and severe morphogenetic defects. Our analyses show that the successful execution of morphogenetic events during gastrulation requires that lineage specification and the ordered production of differentiated cell types occur in concordance with embryonic growth.

Toll-like receptor 7/8 agonist R848 alters the immune tumor microenvironment and enhances SBRT-induced antitumor efficacy in murine models of pancreatic cancer

BACKGROUND

Stereotactic body radiotherapy (SBRT) has been increasingly used as adjuvant therapy in pancreatic ductal adenocarcinoma (PDAC), and induces immunogenic cell death, which leads to the release of tumor antigen and damage-associated molecular patterns. However, this induction often fails to generate sufficient response to overcome pre-existing tumor microenvironment (TME) immunosuppression. Toll-like receptor (TLR) 7/8 ligands, such as R848, can amplify the effect of tumor vaccines, with recent evidence showing its antitumor effect in pancreatic cancer by modulating the immunosuppressive TME. Therefore, we hypothesized that the combination of R848 and SBRT would improve local and systemic antitumor immune responses by potentiating the antitumor effects of SBRT and reversing the immunosuppressive nature of the PDAC TME.

METHODS

Using murine models of orthotopic PDAC, we assessed the combination of intravenous TLR7/8 agonist R848 and local SBRT on tumor growth and immune response in primary pancreatic tumors. Additionally, we employed a hepatic metastatic model to investigate if the combination of SBRT targeting only the primary pancreatic tumor and systemic R848 is effective in controlling established liver metastases.

RESULTS

We demonstrated that intravenous administration of the TLR7/8 agonist R848, in combination with local SBRT, leads to superior tumor control compared with either treatment alone. The combination of R848 and SBRT results in significant immune activation of the pancreatic TME, including increased tumor antigen-specific CD8+ T cells, decreased regulatory T cells, and enhanced antigen-presenting cells maturation, as well as increased interferon gamma, granzyme B, and CCL5 along with decreased levels of interleukin 4 (IL-4), IL-6, and IL-10. Importantly, the combination of SBRT and systemic R848 also resulted in similar immunostimulatory changes in liver metastases, leading to improved metastatic control. CD8+ T cell depletion studies highlighted the necessity of these effector cells at both the local and hepatic metastatic sites. T cell receptor (TCR) clonotype analysis indicated that systemic R848 not only diversified the TCR repertoire but also conditioned the metastatic foci to facilitate entry of CD8+ T cells generated by SBRT therapy.

CONCLUSIONS

These findings suggest that systemic administration of TLR7/8 agonists in combination with SBRT may be a promising avenue for metastatic PDAC treatment.

Temperature-induced reorganisation of Schistocephalus solidus (Cestoda) proteome during the transition to the warm-blooded host

The protein composition of the cestode Schistocephalus solidus was measured in an experiment simulating the trophic transmission of the parasite from a cold-blooded to a warm-blooded host. The first hour of host colonisation was studied in a model experiment, in which sticklebacks Gasterosteus aculeatus infected with S. solidus were heated at 40°C for 1 h. As a result, a decrease in the content of one tegument protein was detected in the plerocercoids of S. solidus. Sexual maturation of the parasites was initiated in an experiment where S. solidus larvae were taken from fish and cultured in vitro at 40°C for 48 h. Temperature-independent changes in the parasite proteome were investigated by incubating plerocercoids at 22°C for 48 h in culture medium. Analysis of the proteome allowed us to distinguish the temperature-induced genes of S. solidus, as well as to specify the molecular markers of the plerocercoid and adult worms. The main conclusion of the study is that the key enzymes of long-term metabolic changes (glycogen consumption, protein production, etc.) in parasites during colonisation of a warm-blooded host are induced by temperature.

Regulation of NANOG and SOX2 expression by activin A and a canonical WNT agonist in bovine embryonic stem cells and blastocysts

Bovine embryonic stem cells (ESC) have features associated with the primed pluripotent state including low expression of one of the core pluripotency transcription factors, NANOG. It has been reported that NANOG expression can be upregulated in porcine ESC by treatment with activin A and the WNT agonist CHIR99021. Accordingly, it was tested whether expression of NANOG and another pluripotency factor SOX2 could be stimulated by activin A and the WNT agonist CHIR99021. Immunoreactive NANOG and SOX2 were analyzed for bovine ESC lines derived under conditions in which activin A and CHIR99021 were added singly or in combination. Activin A enhanced NANOG expression but also reduced SOX2 expression. CHIR99021 depressed expression of both NANOG and SOX2. In a second experiment, activin A enhanced blastocyst development while CHIR99021 treatment impaired blastocyst formation and reduced number of blastomeres. Activin A treatment decreased blastomeres in the blastocyst that were positive for either NANOG or SOX2 but increased those that were CDX2+ and that were GATA6+ outside the inner cell mass. CHIR99021 reduced SOX2+ and NANOG+ blastomeres without affecting the number or percent of blastomeres that were CDX2+ and GATA6+. Results indicate activation of activin A signaling stimulates NANOG expression during self-renewal of bovine ESC but suppresses cells expressing pluripotency markers in the blastocyst and increases cells expressing CDX2. Actions of activin A to promote blastocyst development may involve its role in promoting trophectoderm formation. Furthermore, results demonstrate the negative role of canonical WNT signaling in cattle for pluripotency marker expression in ESC and in formation of the inner cell mass and epiblast during embryonic development. This article has an associated First Person interview with the first author of the paper.

Summary of Utah Project on Exfoliation Syndrome (UPEXS): using a large database to identify systemic comorbidities

The purpose of the Utah Project on Exfoliation Syndrome (UPEXS) is to identify associations between exfoliation syndrome (XFS) and other diseases that share the commonality of abnormalities in elastin and Lysyl Oxidase-Like 1 gene regulation. The UPEXS is unique because it uses the Utah Population Database, which is linked to the Utah genealogy, that contains a compilation of large pedigrees of most families in the state of Utah that go back multiple generations (3 to ≥11). The health and medical records of these family members are linked to vital records and can be used effectively in studies focused on genetic disorders like XFS, where familial clustering of a disorder is a trend. There is increasing evidence that patients with XFS have a higher risk of certain systemic disorders that reflect the systemic tissue abnormalities of XFS. Epidemiological studies focused on patients with XFS have shown that there is an increased risk of these individuals developing other pathologies that have abnormalities in extracellular matrix metabolism and repair. UPEXS has focused on suspected comorbidities that involve abnormalities in elastin maintenance, a protein that plays a role in the makeup of the extracellular matrix. In this paper, the results from the analysis of chronic obstructive pulmonary disease, inguinal hernias, pelvic organ prolapse, obstructive sleep apnoea and atrial fibrillation are summarised along with the utility of using such a large dataset.

Comparing the reporting and conduct quality of exercise and pharmacological randomised controlled trials: a systematic review

OBJECTIVE

Evaluate the quality of exercise randomised controlled trial (RCT) reporting and conduct in clinical populations (ie, adults with or at risk of chronic conditions) and compare with matched pharmacological RCTs.

DESIGN

Systematic review.

DATA SOURCES

Embase (Elsevier), PubMed (NLM) and CINAHL (EBSCO).

STUDY SELECTION

RCTs of exercise in clinical populations with matching pharmacological RCTs published in leading clinical, medical and specialist journals with impact factors ≥15.

REVIEW METHODS

Overall RCT quality was evaluated by two independent reviewers using three research reporting guidelines (ie, Consolidated Standards of Reporting Trials (CONSORT; pharmacological RCTs)/CONSORT for non-pharmacological treatments; exercise RCTs), CONSORT-Harms, Template for Intervention Description and Replication) and two risk of bias assessment (research conduct) tools (ie, Cochrane Risk of Bias, Jadad Scale). We compared research reporting and conduct quality within exercise RCTs with matched pharmacological RCTs, and examined factors associated with quality in exercise and pharmacological RCTs, separately.

FINDINGS

Forty-eight exercise RCTs (11 658 patients; median sample n=138) and 48 matched pharmacological RCTs were evaluated (18 501 patients; median sample n=160). RCTs were conducted primarily in cardiovascular medicine (43%) or oncology (31%). Overall quality score (composite of all research reporting and conduct quality scores; primary endpoint) for exercise RCTs was 58% (median score 46 of 80; IQR: 39-51) compared with 77% (53 of 68; IQR: 47-58) in the matched pharmacological RCTs (p≤0.001). Individual quality scores for trial reporting and conduct were lower in exercise RCTs compared with matched pharmacological RCTs (p≤0.03). Factors associated with higher overall quality scores for exercise RCTs were journal impact factor (≥25), sample size (≥152) and publication year (≥2013).

CONCLUSIONS AND RELEVANCE

Research reporting and conduct quality within exercise RCTs is inferior to matched pharmacological RCTs. Suboptimal RCT reporting and conduct impact the fidelity, interpretation, and reproducibility of exercise trials and, ultimately, implementation of exercise in clinical populations.

PROSPERO REGISTRATION NUMBER

CRD42018095033.

Recessive, gain-of-function toxicity in an APOL1 BAC transgenic mouse model mirrors human APOL1 kidney disease

People of recent sub-Saharan African ancestry develop kidney failure much more frequently than other groups. A large fraction of this disparity is due to two coding sequence variants in the APOL1 gene. Inheriting two copies of these APOL1 risk variants, known as G1 and G2, causes high rates of focal segmental glomerulosclerosis (FSGS), HIV-associated nephropathy and hypertension-associated end-stage kidney disease. Disease risk follows a recessive mode of inheritance, which is puzzling given the considerable data that G1 and G2 are toxic gain-of-function variants. We developed coisogenic bacterial artificial chromosome (BAC) transgenic mice harboring either the wild-type (G0), G1 or G2 forms of human APOL1. Expression of interferon gamma (IFN-γ) via plasmid tail vein injection results in upregulation of APOL1 protein levels together with robust induction of heavy proteinuria and glomerulosclerosis in G1/G1 and G2/G2 but not G0/G0 mice. The disease phenotype was greater in G2/G2 mice. Neither heterozygous (G1/G0 or G2/G0) risk variant mice nor hemizygous (G1/-, G2/-) mice had significant kidney injury in response to IFN-γ, although the heterozygous mice had a greater proteinuric response than the hemizygous mice, suggesting that the lack of significant disease in humans heterozygous for G1 or G2 is not due to G0 rescue of G1 or G2 toxicity. Studies using additional mice (multicopy G2 and a non-isogenic G0 mouse) supported the notion that disease is largely a function of the level of risk variant APOL1 expression. Together, these findings shed light on the recessive nature of APOL1-nephropathy and present an important model for future studies.

The dorsal blastopore lip is a source of signals inducing planar cell polarity in the Xenopus neural plate

Coordinated polarization of cells in the tissue plane, known as planar cell polarity (PCP), is associated with a signaling pathway critical for the control of morphogenetic processes. Although the segregation of PCP components to opposite cell borders is believed to play a critical role in this pathway, whether PCP derives from egg polarity or preexistent long-range gradient, or forms in response to a localized cue, remains a challenging question. Here we investigate the Xenopus neural plate, a tissue that has been previously shown to exhibit PCP. By imaging Vangl2 and Prickle3, we show that PCP is progressively acquired in the neural plate and requires a signal from the posterior region of the embryo. Tissue transplantations indicated that PCP is triggered in the neural plate by a planar cue from the dorsal blastopore lip. The PCP cue did not depend on the orientation of the graft and was distinct from neural inducers. These observations suggest that neuroectodermal PCP is not instructed by a preexisting molecular gradient but induced by a signal from the dorsal blastopore lip.

The 100 most-cited papers on age-related macular degeneration: a bibliographic perspective

The 100 most-cited papers on age-related macular degeneration (AMD) were analysed using a bibliographic study. The bibliographic databases of the Institute for Scientific Information Web of Knowledge were searched, limited to research articles published between 1965 and 2020 in peer-reviewed journals. The papers were ranked in order of number of citations since publication. Five of the top 10 (and 3 of the top 4) papers reported randomised clinical trial results for either anti-vascular endothelial growth factor agents or nutritional supplements. Four of the top 10 papers reported genotype-phenotype associations between AMD and variants in Complement Factor H. This bibliographic study provides perspective and insight into many of the most influential contributions in the understanding and management of AMD and its evolution over time.

The transcription factor Maz is essential for normal eye development

Wnt/β-catenin signaling has an essential role in eye development. Faulty regulation of this pathway results in ocular malformations, owing to defects in cell-fate determination and differentiation. Herein, we show that disruption of Maz, the gene encoding Myc-associated zinc-finger transcription factor, produces developmental eye defects in mice and humans. Expression of key genes involved in the Wnt cascade, Sfrp2, Wnt2b and Fzd4, was significantly increased in mice with targeted inactivation of Maz, resulting in abnormal peripheral eye formation with reduced proliferation of the progenitor cells in the region. Paradoxically, the Wnt reporter TCF-Lef1 displayed a significant downregulation in Maz-deficient eyes. Molecular analysis indicates that Maz is necessary for the activation of the Wnt/β-catenin pathway and participates in the network controlling ciliary margin patterning. Copy-number variations and single-nucleotide variants of MAZ were identified in humans that result in abnormal ocular development. The data support MAZ as a key contributor to the eye comorbidities associated with chromosome 16p11.2 copy-number variants and as a transcriptional regulator of ocular development.

Microtubule assembly and pole coalescence: early steps in Caenorhabditiselegans oocyte meiosis I spindle assembly

How oocytes assemble bipolar meiotic spindles in the absence of centrosomes as microtubule organizing centers remains poorly understood. We have used live cell imaging in Caenorhabditis elegans to investigate requirements for the nuclear lamina and for conserved regulators of microtubule dynamics during oocyte meiosis I spindle assembly, assessing these requirements with respect to recently identified spindle assembly steps. We show that the nuclear lamina is required for microtubule bundles to form a peripheral cage-like structure that appears shortly after oocyte nuclear envelope breakdown and surrounds the oocyte chromosomes, although bipolar spindles still assembled in its absence. Although two conserved regulators of microtubule nucleation, RAN-1 and γ-tubulin, are not required for bipolar spindle assembly, both contribute to normal levels of spindle-associated microtubules and spindle assembly dynamics. Finally, the XMAP215 ortholog ZYG-9 and the nearly identical minus-end directed kinesins KLP-15/16 are required for proper assembly of the early cage-like structure of microtubule bundles, and for early spindle pole foci to coalesce into a bipolar structure. Our results provide a framework for assigning molecular mechanisms to recently described steps in C. elegans oocyte meiosis I spindle assembly.

Upper and Lower Extremity Measurement of Tissue Sodium and Fat Content in Patients with Lipedema

OBJECTIVE

The aim of this study is to compare tissue sodium and fat content in the upper and lower extremities of participants with lipedema versus controls using magnetic resonance imaging (MRI).

METHODS

MRI was performed at 3.0 T in females with lipedema (n = 15, age = 43.2 ± 10.0 years, BMI = 30.3 ± 4.4 kg/m² ) and controls without lipedema (n = 14, age = 42.8 ± 13.2 years, BMI = 28.8 ± 4.4 kg/m² ). Participants were assessed for pain and disease stage. Sodium MRI was performed in the forearm and calf to quantify regional tissue sodium content (TSC, mmol/L). Chemical-shift-encoded water-fat MRI was performed in identical regions for measurement of fat/water (ratio).

RESULTS

In the calf, skin TSC (16.3 ± 2.6 vs. 14.4 ± 2.2 mmol/L, P = 0.04), muscle TSC (20.3 ± 3.0 vs. 18.3 ± 1.7 mmol/L, P = 0.03), and fat/water (1.03 ± 0.37 vs. 0.56 ± 0.21 ratio, P < 0.001) were significantly higher in participants with lipedema versus control participants. In the forearm, skin TSC (13.4 ± 3.3 vs. 12.0 ± 2.3 mmol/L, P = 0.2, Cohen's d = 0.50) and fat/water (0.65 ± 0.24 vs. 0.48 ± 0.24 ratio, P = 0.07, Cohen's d = 0.68) demonstrated moderate effect sizes in participants with lipedema versus control participants. Calf skin TSC was significantly correlated with pain (Spearman's rho = 0.55, P = 0.03) and disease stage (Spearman's rho = 0.82, P < 0.001) among participants with lipedema.

CONCLUSIONS

MRI-measured tissue sodium and fat content are significantly higher in the lower extremities, but not upper extremities, of patients with lipedema compared with BMI-matched controls.

Ultra-low-dose PET reconstruction using generative adversarial network with feature matching and task-specific perceptual loss

PURPOSE

Our goal was to use a generative adversarial network (GAN) with feature matching and task-specific perceptual loss to synthesize standard-dose amyloid Positron emission tomography (PET) images of high quality and including accurate pathological features from ultra-low-dose PET images only.

METHODS

Forty PET datasets from 39 participants were acquired with a simultaneous PET/MRI scanner following injection of 330 ± 30 MBq of the amyloid radiotracer 18F-florbetaben. The raw list-mode PET data were reconstructed as the standard-dose ground truth and were randomly undersampled by a factor of 100 to reconstruct 1% low-dose PET scans. A 2D encoder-decoder network was implemented as the generator to synthesize a standard-dose image and a discriminator was used to evaluate them. The two networks contested with each other to achieve high-visual quality PET from the ultra-low-dose PET. Multi-slice inputs were used to reduce noise by providing the network with 2.5D information. Feature matching was applied to reduce hallucinated structures. Task-specific perceptual loss was designed to maintain the correct pathological features. The image quality was evaluated by peak signal-to-noise ratio (PSNR), structural similarity (SSIM), and root mean square error (RMSE) metrics with and without each of these modules. Two expert radiologists were asked to score image quality on a 5-point scale and identified the amyloid status (positive or negative).

RESULTS

With only low-dose PET as input, the proposed method significantly outperformed Chen et al.'s method (Chen et al. Radiology. 2018;290:649-656) (which shows the best performance in this task) with the same input (PET-only model) by 1.87 dB in PSNR, 2.04% in SSIM, and 24.75% in RMSE. It also achieved comparable results to Chen et al.'s method which used additional magnetic resonance imaging (MRI) inputs (PET-MR model). Experts' reading results showed that the proposed method could achieve better overall image quality and maintain better pathological features indicating amyloid status than both PET-only and PET-MR models proposed by Chen et al. CONCLUSION: Standard-dose amyloid PET images can be synthesized from ultra-low-dose images using GAN. Applying adversarial learning, feature matching, and task-specific perceptual loss are essential to ensure image quality and the preservation of pathological features.