Differential diagnosis between multiple sclerosis and leukodystrophies - A scoping review.

Multiple Sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system (CNS) characterized by damage to the myelin sheaths of oligodendrocytes. Currently, there is no specific biomarker to identify the disease; however, a diagnostic criterion has been established based on patient's clinical, laboratory, and imaging characteristics, which assists in identifying this condition. The primary method for diagnosing MS is the McDonald criteria, first described in 2001 and revised in the years 2005, 2012, and 2017. These criteria have been continuously reviewed to enhance specificity and sensitivity in the diagnosis of MS, thereby reducing errors in its differential diagnosis. An important differential diagnosis that shares overlapping features with MS, mainly the progressive forms, are leukodystrophies with demyelination as underlying pathology. Leukodystrophies comprise a rare group of genetically determined disorders that lead to either demyelination or hypomyelination of the central nervous system that can result neuroimaging changes as well as clinical findings similar to those observed in MS. Thus, systematic evaluation encompassing clinical presentation, neuroimaging findings, and laboratory metrics proves indispensable for a differential diagnosis. As such, this study aimed to establish, clearly and objectively, the similarities and differences between MS and the main demyelinating leukodystrophies. The study analyzed the parameters of the McDonald criteria, including clinical, laboratory, and magnetic resonance imaging aspects, as found in patients with leukodystrophies through scoping literature review. The data were compared with the determinations of the revised 2017 McDonald criteria to facilitate the differential diagnosis of these diseases in clinical practice.

Impact of Immune Checkpoint Inhibitors on the Course of Multiple Sclerosis.

OBJECTIVES: Immune checkpoint inhibitors (ICIs) are increasingly used in cancer treatment. Their mechanism of action raises the question of possible exacerbation of preexisting multiple sclerosis (MS). The aim of our study was to assess the risk of increased MS activity, defined by the occurrence of a relapse and/or a new MRI lesion, after ICI initiation. METHODS: This French multicentric study collected retrospective and prospective data on patients with MS treated with ICIs after a cancer diagnosis. RESULTS: We identified 18 patients with a median age of 48 years. Three of them (17%), all aged 50 years or younger, with a relapsing-remitting course, showed clinical and/or radiologic signs of MS activity 3 to 6 months after ICI initiation. They had stopped disease-modifying treatment (DMT) several months earlier, at the time of cancer diagnosis. Only one had both clinical and MRI activity, with mild severity and complete recovery. DISCUSSION: Our study suggests that the overall risk of MS activity under ICI is low and could be mainly driven by DMT discontinuation, as in MS in general. Although larger studies are needed for better risk assessment in younger patients with more active disease, ICI should be considered when needed in patients with MS.

Starch deficiency in tomato causes transcriptional reprogramming that modulates fruit development, metabolism, and stress responses.

Tomato (Solanum lycopersicum) fruit store carbon as starch during early development and mobilize it at the onset of ripening. Starch accumulation has been suggested to buffer fluctuations in carbon supply to the fruit under abiotic stress, and contribute to sugar levels in ripe fruit. However, the role of starch accumulation and metabolism during fruit development is still unclear. Here we show that the tomato mutant adpressa (adp) harbors a mutation in a gene encoding the small subunit of ADP-glucose pyrophosphorylase that abolishes starch synthesis. The disruption of starch biosynthesis causes major transcriptional and metabolic remodeling in adp fruit but only minor effects on fruit size and ripening. Changes in gene expression and metabolite profiles indicate that the lack of carbon flow into starch increases levels of soluble sugars during fruit growth, triggers a readjustment of central carbohydrate and lipid metabolism, and activates growth and stress protection pathways. Accordingly, adp fruits are remarkably resistant to blossom-end rot, a common physiological disorder induced by environmental stress. Our results provide insights into the effects of perturbations of carbohydrate metabolism on tomato fruit development, with potential implications for the enhancement of protective mechanisms against abiotic stress in fleshy fruit.

Spatiotemporal dynamics of the tomato fruit transcriptome under prolonged water stress.

Water availability influences all aspects of plant growth and development; however, most studies of plant responses to drought have focused on vegetative organs, notably roots and leaves. Far less is known about the molecular bases of drought acclimation responses in fruits, which are complex organs with distinct tissue types. To obtain a more comprehensive picture of the molecular mechanisms governing fruit development under drought, we profiled the transcriptomes of a spectrum of fruit tissues from tomato (Solanum lycopersicum), spanning early growth through ripening and collected from plants grown under varying intensities of water stress. In addition, we compared transcriptional changes in fruit with those in leaves to highlight different and conserved transcriptome signatures in vegetative and reproductive organs. We observed extensive and diverse genetic reprogramming in different fruit tissues and leaves, each associated with a unique response to drought acclimation. These included major transcriptional shifts in the placenta of growing fruit and in the seeds of ripe fruit related to cell growth and epigenetic regulation, respectively. Changes in metabolic and hormonal pathways, such as those related to starch, carotenoids, jasmonic acid, and ethylene metabolism, were associated with distinct fruit tissues and developmental stages. Gene coexpression network analysis provided further insights into the tissue-specific regulation of distinct responses to water stress. Our data highlight the spatiotemporal specificity of drought responses in tomato fruit and indicate known and unrevealed molecular regulatory mechanisms involved in drought acclimation, during both vegetative and reproductive stages of development.

Systems-level conservation of the proximal TCR signaling network of mice and humans.

We exploited traceable gene tagging in primary human T cells to establish the composition and dynamics of seven canonical TCR-induced protein signaling complexes (signalosomes) using affinity purification coupled with mass spectrometry (AP-MS). It unveiled how the LAT adaptor assembles higher-order molecular condensates and revealed that the proximal TCR-signaling network has a high degree of qualitative and quantitative conservation between human CD4+ and CD8+ T cells. Such systems-level conservation also extended across human and mouse T cells and unexpectedly encompassed protein-protein interaction stoichiometry. Independently of evolutionary considerations, our study suggests that a drug targeting the proximal TCR signaling network should behave similarly when applied to human and mouse T cells. However, considering that signaling differences likely exist between the distal TCR-signaling pathway of human and mouse, our fast-track AP-MS approach should be favored to determine the mechanism of action of drugs targeting human T cell activation. An opportunity is illustrated here using an inhibitor of the LCK protein tyrosine kinase as a proof-of-concept.

Functional Mapping of Adhesiveness on Live Cells Reveals How Guidance Phenotypes Can Emerge From Complex Spatiotemporal Integrin Regulation.

Immune cells have the ubiquitous capability to migrate disregarding the adhesion properties of the environment, which requires a versatile adaptation of their adhesiveness mediated by integrins, a family of specialized adhesion proteins. Each subtype of integrins has several ligands and several affinity states controlled by internal and external stimuli. However, probing cell adhesion properties on live cells without perturbing cell motility is highly challenging, especially in vivo. Here, we developed a novel in vitro method using micron-size beads pulled by flow to functionally probe the local surface adhesiveness of live and motile cells. This method allowed a functional mapping of the adhesiveness mediated by VLA-4 and LFA-1 integrins on the trailing and leading edges of live human T lymphocytes. We show that cell polarization processes enhance integrin-mediated adhesiveness toward cell rear for VLA-4 and cell front for LFA-1. Furthermore, an inhibiting crosstalk of LFA-1 toward VLA-4 and an activating crosstalk of VLA-4 toward LFA-1 were found to modulate cell adhesiveness with a long-distance effect across the cell. These combined signaling processes directly support the bistable model that explains the emergence of the versatile guidance of lymphocyte under flow. Molecularly, Sharpin, an LFA-1 inhibitor in lymphocyte uropod, was found involved in the LFA-1 deadhesion of lymphocytes; however, both Sharpin and Myosin inhibition had a rather modest impact on adhesiveness. Quantitative 3D immunostaining identified high-affinity LFA-1 and VLA-4 densities at around 50 and 100 molecules/µm2 in basal adherent zones, respectively. Interestingly, a latent adhesiveness of dorsal zones was not grasped by immunostaining but assessed by direct functional assays with beads. The combination of live functional assays, molecular imaging, and genome editing is instrumental to characterizing the spatiotemporal regulation of integrin-mediated adhesiveness at molecular and cell scales, which opens a new perspective to decipher sophisticated phenotypes of motility and guidance.

The Balance in T Follicular Helper Cell Subsets Is Altered in Neuromyelitis Optica Spectrum Disorder Patients and Restored by Rituximab.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare and severe auto-immune disease of the central nervous system driven by pathogenic antibodies mainly directed against aquaporin-4 (AQP4-Ab). Treatment of NMOSD currently relies on immunosuppressants (mycophenolate mofetil, azathioprine) or B-cell-depleting therapy (rituximab). B-cell differentiation into antibody-producing cells requires T follicular helper cells (Tfh). There are several Tfh subsets that differentially affect B-cell differentiation; Tfh2 and Tfh17 subsets strongly support B-cell differentiation. By contrast, Tfh1 lack this capacity and T follicular regulatory cells (Tfr), inhibit B-cell differentiation into antibody-producing cells. We performed a broad characterization of circulating Tfh subsets in 25 NMOSD patients and analyzed the impact of different treatments on these subsets. Untreated NMOSD patients presented a Tfh polarization toward excessive B-helper Tfh subsets with an increase of Tfh17 and (Tfh2+Tfh17)/Tfh1 ratio and a decrease of Tfr and Tfh1. Rituximab restored the Tfh polarization to that of healthy controls. There was a trend toward a similar result for azathioprine and mycophenolate mofetil. Our results suggest that NMOSD patients present an impaired balance in Tfh subsets favoring B-cell differentiation which may explain the sustained antibody production. These findings provide new insights into the pathophysiology of NMOSD, and further suggest that Tfh and Tfr subsets could be considered as potential therapeutic target in NMOSD because of their upstream role in antibody production.

High-resolution spatiotemporal transcriptome mapping of tomato fruit development and ripening.

Tomato (Solanum lycopersicum) is an established model for studying fruit biology; however, most studies of tomato fruit growth and ripening are based on homogenized pericarp, and do not consider the internal tissues, or the expression signatures of individual cell and tissue types. We present a spatiotemporally resolved transcriptome analysis of tomato fruit ontogeny, using laser microdissection (LM) or hand dissection coupled with RNA-Seq analysis. Regulatory and structural gene networks, including families of transcription factors and hormone synthesis and signaling pathways, are defined across tissue and developmental spectra. The ripening program is revealed as comprising gradients of gene expression, initiating in internal tissues then radiating outward, and basipetally along a latitudinal axis. We also identify spatial variations in the patterns of epigenetic control superimposed on ripening gradients. Functional studies elucidate previously masked regulatory phenomena and relationships, including those associated with fruit quality traits, such as texture, color, aroma, and metabolite profiles.

The Tomato Expression Atlas.

SUMMARY: With the development of new high-throughput DNA sequencing technologies and decreasing costs, large gene expression datasets are being generated at an accelerating rate, but can be complex to visualize. New, more interactive and intuitive tools are needed to visualize the spatiotemporal context of expression data and help elucidate gene function. Using tomato fruit as a model, we have developed the Tomato Expression Atlas to facilitate effective data analysis, allowing the simultaneous visualization of groups of genes at a cell/tissue level of resolution within an organ, enhancing hypothesis development and testing in addition to candidate gene identification. This atlas can be adapted to different types of expression data from diverse multicellular species. AVAILABILITY AND IMPLEMENTATION: The Tomato Expression Atlas is available at http://tea.solgenomics.net/ . Source code is available at https://github.com/solgenomics/Tea . CONTACT: jr286@cornell.edu or lam87@cornell.edu. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Laser microdissection of tomato fruit cell and tissue types for transcriptome profiling.

This protocol enables transcriptome profiling of specific cell or tissue types that are isolated from tomato using laser microdissection (LM). To prepare tissue for LM, fruit samples are first fixed in optimal cutting temperature (OCT) medium and frozen in molds. The tissue is then sectioned using a cryostat before being dissected using an LM instrument. The RNAs contained in the harvested cells are purified and subjected to two rounds of amplification to yield sufficient quantities of RNA to generate cDNA libraries. Unlike several other techniques that are used to isolate specific cell types, LM has the advantage of being readily applied to any plant species without having to generate transgenic plants. Using the protocols described here, LM-mediated cell-type transcriptomic analysis of two samples requires ∼8 d from tissue harvest to RNA sequencing (RNA-seq), whereas each additional sample, up to a total of 12 samples, requires ∼1 additional day for the LM step. RNA obtained using this method has been successfully used for deep-coverage transcriptome profiling, which is a particularly effective strategy for identifying genes that are differentially expressed between cell or tissue types.

Arabidopsis FORGETTER1 mediates stress-induced chromatin memory through nucleosome remodeling.

Plants as sessile organisms can adapt to environmental stress to mitigate its adverse effects. As part of such adaptation they maintain an active memory of heat stress for several days that promotes a more efficient response to recurring stress. We show that this heat stress memory requires the activity of the FORGETTER1 (FGT1) locus, with fgt1 mutants displaying reduced maintenance of heat-induced gene expression. FGT1 encodes the Arabidopsis thaliana orthologue of Strawberry notch (Sno), and the protein globally associates with the promoter regions of actively expressed genes in a heat-dependent fashion. FGT1 interacts with chromatin remodelers of the SWI/SNF and ISWI families, which also display reduced heat stress memory. Genomic targets of the BRM remodeler overlap significantly with FGT1 targets. Accordingly, nucleosome dynamics at loci with altered maintenance of heat-induced expression are affected in fgt1. Together, our results suggest that by modulating nucleosome occupancy, FGT1 mediates stress-induced chromatin memory.

Water limitation and rootstock genotype interact to alter grape berry metabolism through transcriptome reprogramming.

Grapevine is a perennial crop often cultivated by grafting a scion cultivar on a suitable rootstock. Rootstocks influence scions, particularly with regard to water uptake and vigor. Therefore, one of the possibilities to adapt viticulture to the extended drought stress periods is to select rootstocks conferring increased tolerance to drought. However, the molecular mechanisms associated with the ability of rootstock/scion combination to influence grape berry metabolism under drought stress are still poorly understood. The transcriptomic changes induced by drought stress in grape berries (cv. Pinot noir) from vines grafted on either 110R (drought-tolerant) or 125AA (drought-sensitive) rootstock were compared. The experiments were conducted in the vineyard for two years and two grape berry developmental stages (50% and 100% veraison). The genome-wide microarray approach showed that water stress strongly impacts gene expression in the berries, through ontology categories that cover cell wall metabolism, primary and secondary metabolism, signaling, stress, and hormones, and that some of these effects strongly depend on the rootstock genotype. Indeed, under drought stress, berries from vines grafted on 110R displayed a different transcriptional response compared to 125AA-concerning genes related to jasmonate (JA), phenylpropanoid metabolism, and pathogenesis-related proteins. The data also suggest a link between JA and secondary metabolism in water-stressed berries. Overall, genes related to secondary metabolism and JA are more induced and/or less repressed by drought stress in the berries grafted on the drought-sensitive rootstock 125AA. These rootstock-dependent gene expression changes are relevant for berry composition and sensory properties.

The basic leucine zipper transcription factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 is an important transcriptional regulator of abscisic acid-dependent grape berry ripening processes.

In grape (Vitis vinifera), abscisic acid (ABA) accumulates during fruit ripening and is thought to play a pivotal role in this process, but the molecular basis of this control is poorly understood. This work characterizes ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a grape basic leucine zipper transcription factor belonging to a phylogenetic subgroup previously shown to be involved in ABA and abiotic stress signaling in other plant species. VvABF2 transcripts mainly accumulated in the berry, from the onset of ripening to the harvesting stage, and were up-regulated by ABA. Microarray analysis of transgenic grape cells overexpressing VvABF2 showed that this transcription factor up-regulates and/or modifies existing networks related to ABA responses. In addition, grape cells overexpressing VvABF2 exhibited enhanced responses to ABA treatment compared with control cells. Among the VvABF2-mediated responses highlighted in this study, the synthesis of phenolic compounds and cell wall softening were the most strongly affected. VvABF2 overexpression strongly increased the accumulation of stilbenes that play a role in plant defense and human health (resveratrol and piceid). In addition, the firmness of fruits from tomato (Solanum lycopersicum) plants overexpressing VvABF2 was strongly reduced. These data indicate that VvABF2 is an important transcriptional regulator of ABA-dependent grape berry ripening.

The grape berry-specific basic helix-loop-helix transcription factor VvCEB1 affects cell size.

The development of fleshy fruits involves complex physiological and biochemical changes. After fertilization, fruit growth usually begins with cell division, continues with both cell division and expansion, allowing fruit set to occur, and ends with cell expansion only. In spite of the economical importance of grapevine, the molecular mechanisms controlling berry growth are not fully understood. The present work identified and characterized Vitis vinifera cell elongation bHLH protein (VvCEB1), a basic helix-loop-helix (bHLH) transcription factor controlling cell expansion in grape. VvCEB1 was expressed specifically in berry-expanding tissues with a maximum around veraison. The study of VvCEB1 promoter activity in tomato confirmed its specific fruit expression during the expansion phase. Overexpression of VvCEB1 in grape embryos showed that this protein stimulates cell expansion and affects the expression of genes involved in cell expansion, including genes of auxin metabolism and signalling. Taken together, these data show that VvCEB1 is a fruit-specific bHLH transcription factor involved in grape berry development.

Tryptophan regulates thaxtomin A and indole-3-acetic acid production in Streptomyces scabiei and modifies its interactions with radish seedlings.

The virulence of Streptomyces scabiei, the causal agent of common scab, depends mainly on the production of the toxin thaxtomin A. S. scabiei also produces indole-3-acetic acid (IAA) but the role of this hormone in the interaction between pathogenic streptomycetes and plants has not yet been elucidated. Tryptophan is a biosynthetic precursor of both IAA and thaxtomin A. In this study, the effect of tryptophan on thaxtomin A and IAA production as well as its effect on the transcription of the corresponding biosynthetic genes in S. scabiei has been analyzed. In vitro IAA production depended on the availability of tryptophan. However, addition of this amino acid to the culture medium inhibited the biosynthesis of thaxtomin A. Expression of thaxtomin A biosynthetic genes nos and txtA were strongly repressed in the presence of tryptophan; however, modulation of the expression was not observed for the IAA biosynthetic genes iaaM and iaaH. The effects of an exogenous tryptophan supply on S. scabiei virulence were assessed on radish seedlings. Addition of tryptophan reduced symptoms on inoculated radish roots compared with seedlings grown in the absence of the bacterium, by way of inhibition of thaxtomin A production and increase of IAA biosynthesis.