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Kumar, V.

Publications and source records attributed to Kumar, V..

At least 127 records · Page 7Linked to original sources

In vitro host transcriptomics during Cryptococcus neoformans, Cryptococcus gattii, and Candida albicans infection of South African volunteers

Cryptococcus neoformans, Cryptococcus gattii and Candida albicans are opportunistic fungal pathogens associated with infections in immunocompromised hosts. Cryptococcal meningitis (CM) is the leading fungal cause of HIV-related deaths globally, with the majority occurring in Africa. The human immune response to C. albicans infection has been studied extensively in large genomics studies whereas cryptococcal infections, despite their severity, are comparatively understudied. Here we investigated the transcriptional response of immune cells after in vitro stimulation with in vitro C. neoformans, C. gattii and C. albicans infection of peripheral blood mononuclear cells (PBMCs) collected from healthy South African volunteers. We found a lower transcriptional response to cryptococcal stimuli compared to C. albicans and unique expression signatures from all three fungal stimuli. This work provides a starting point for further studies comparing the transcriptional signature of CM in immunocompromised patients, with the goal of identifying biomarkers of disease severity and possible novel treatment targets.

genomics↗

UDP-6-glucose dehydrogenase in hormonally responsive breast cancers

Survival for metastatic breast cancer is low and thus, continued efforts to treat and prevent metastatic progression are critical. Estrogen is shown to promote aggressive phenotypes in multiple cancer models irrespective of estrogen receptor (ER) status. Similarly, UDP-Glucose 6-dehydrogenase (UGDH) a ubiquitously expressed enzyme involved in extracellular matrix precursors, as well as hormone processing increases migratory and invasive properties in cancer models. While the role of UGDH in cellular migration is defined, how it intersects with and impacts hormone signaling pathways associated with tumor progression in metastatic breast cancer has not been explored. Here we demonstrate that UGDH knockdown blunts estrogen-induced tumorigenic phenotypes (migration and colony formation) in ER+ and ER- breast cancer in vitro. Knockdown of UGDH also inhibits extravasation of ER- breast cancer ex vivo, primary tumor growth and animal survival in vivo in both ER+ and ER- breast cancer. We also use single cell RNA-sequencing to demonstrate that our findings translate to a human breast cancer clinical specimen. Our findings support the role of estrogen and UGDH in breast cancer progression provide a foundation for future studies to evaluate the role of UGDH in therapeutic resistance to improve outcomes and survival for breast cancer patients.

cancer biology↗

Learning Continuous 2D Diffusion Maps from Particle Trajectories without Data Binning

Diffusion coefficients often vary across regions, such as cellular membranes, and quantifying their variation can provide valuable insight into local membrane properties such as composition and stiffness. Toward quantifying diffusion coefficient spatial maps and uncertainties from particle tracks, we use a Bayesian method and place Gaussian Process (GP) Priors on the maps. For the sake of computational efficiency, we leverage inducing point methods on GPs arising from the mathematical structure of the data giving rise to non-conjugate likelihood-prior pairs. We analyze both synthetic data, where ground truth is known, as well as data drawn from live-cell singlemolecule imaging of membrane proteins. The resulting tool provides an unsupervised method to rigorously map diffusion coefficients continuously across membranes without data binning.

biophysics↗

P66Shc Mediates SUMO2-induced Endothelial Dysfunction

BackgroundSumoylation is a post-translational modification that can regulate different physiological functions. Increased sumoylation, specifically conjugation of SUMO2/3 (small ubiquitin-like modifier 2/3), is detrimental to vascular health. However, the molecular mechanism mediating this effect is poorly understood. MethodsWe used cell-based assays and mass spectrometry to show that p66Shc is a direct target of SUMO2 and SUMO2 regulates p66Shc function via lysine-81 modification. To determine the effects of SUMO2-p66ShcK81 on vascular function, we generated p66ShcK81R knockin mice and crossbred to LDLr-/- mice to induce hyperlipidemia. Next, to determine p66ShcK81-SUMO2ylation-induced changes in endothelial cell signaling, we performed mass spectrometry followed by Ingenuity Pathway Analysis. ResultsOur data reveal that p66Shc mediates the effects of SUMO2 on endothelial cells. Mass spectrometry identified that SUMO2 modified lysine-81 in the unique collagen homology-2 domain of p66Shc. SUMO2ylation of p66Shc increased phosphorylation at serine-36, causing it to translocate to the mitochondria, a step critical for oxidative function of p66Shc. Notably, sumoylation-deficient p66Shc (p66ShcK81R) was resistant to SUMO2-induced p66ShcS36 phosphorylation and mitochondrial translocation. P66ShcK81R knockin mice were resistant to endothelial dysfunction induced by SUMO2ylation and hyperlipidemia. Ingenuity Pathway Analysis revealed multiple signaling pathways regulated by p66ShcK81-SUMO2ylation in endothelial cells, highlighting JAK-STAT as a major pathway affected by SUMO2-p66ShcK81. ConclusionsCollectively, our work reveals SUMO2-p66Shc signaling as a fundamental regulator of vascular endothelial function. We discovered that p66ShcK81 is an upstream modification regulating p66Shc signaling and mediates hyperlipidemia-induced endothelial dysfunction and oxidative stress.

cell biology↗

Evolution of human pair bonds as a consequence of male-biased mating sex ratios?

Compared to our closest primate relatives, human life history involves greater longevity, which includes a distinctive postmenopausal life stage. The extension of the human lifes-pan (and continued fertility in old males) without lengthening female fertility directly changes the ratio of fertile males to fertile females, called the adult sex ratio (ASR). Additionally, this affects a more fine-grained ratio, the operational sex ratio (OSR), defined as the ratio of males to females currently able to conceive. Here, we construct an ODE model with minimal age structure, in which males compete for paternities using either a multiple-mating or mate-guarding strategy. Our focus is on investigating the differences of strategy choice between populations with chimpanzee-like and human-like life histories. By simulating the system, we determine the dominant strategy and its dependence on various parameter combinations. We introduce a new measure we call the lifetime paternity opportunities (LPO) of a given male strategy. The LPO directly calculates the payoffs of different male strategies and hence enables us to predict when strategies may shift. Our results show that an increase in OSR and ASR correlates well with a change in the dominant strategy from multiple mating to guarding.

evolutionary biology↗

Drosophila Asap regulates cellular protrusions via dArf6-dependent actin regulatory pathway

Membrane protrusions are fundamental to cellular functions like migration, adhesion, and communication and depend upon the dynamic reorganization of the cytoskeleton. The GAP-dependent GTP hydrolysis of Arf proteins regulates actin-dependent membrane remodeling. Here, we show that the dAsap regulates membrane protrusions in S2R+ cells by a mechanism that critically relies on its ArfGAP domain and re-localization of actin regulators, SCAR, and Ena. While our data reinforce the preference of dAsap for Arf1 GTP hydrolysis in vitro, we demonstrate that induction of membrane protrusions in S2R+ cells depends on Arf6 inactivation. This study furthers our understanding of how dAsap-dependent GTP hydrolysis maintains a balance between active and inactive states of dArf6 to regulate cell shape.

cell biology↗

Wnt target gene Ascl4 is dispensable for skin appendage development

The development of skin appendages, including hair follicles, teeth and mammary glands is initiated through the formation of the placode - a local thickening of the epithelium. The Wnt/{beta}-catenin signaling cascade is an evolutionary conserved pathway with an essential role in placode morphogenesis, but its downstream targets and their exact functions remain ill defined. In this study, we identify Achaete-scute complex-like 4 (Ascl4) as a novel target of the Wnt/{beta}-catenin pathway and demonstrate its expression pattern in the signaling centers of developing hair follicles and teeth. Ascl transcription factors belong to the superfamily of basic helix-loop-helix transcriptional regulators involved in cell fate determination in many tissues. However, their specific role in the developing skin remains largely unknown. We report that Ascl4 null mice have no overt phenotype. Absence of Ascl4 did not impair hair follicle morphogenesis or hair shaft formation suggesting that it is non-essential for hair follicle development. No tooth or mammary gland abnormalities were detected either. We suggest that other transcription factors may functionally compensate for the absence of Ascl4, but further research is warranted to assess this possibility.

developmental biology↗

Highly Accurate and Precise Determination of Mouse Mass Using Computer Vision

1Changes in body mass are a key indicator of health and disease in humans and model organisms. Animal body mass is routinely monitored in husbandry and preclinical studies. In rodent studies, the current best method requires manually weighing the animal on a balance which has at least two consequences. First, direct handling of the animal induces stress and can have confounding effects on studies. Second, the acquired mass is static and not amenable to continuous assessment, and rapid mass changes can be missed. A noninvasive and continuous method of monitoring animal mass would have utility in multiple areas of biomedical research. Here, we test the feasibility of determining mouse body mass using video data. We combine computer vision methods with statistical modeling to demonstrate the feasibility of our approach. Our methods determine mouse mass with 4.8% error across highly genetically diverse mouse strains, with varied coat colors and mass. This error is low enough to replace manual weighing with image-based assessment in most mouse studies. We conclude that visual determination of rodent mass using video enables noninvasive and continuous monitoring and can improve animal welfare and preclinical studies.

genetics↗

Prognostic relevance of correlated co-expression of coding and noncoding RNAs in cervical cancers

Human papillomavirus (HPV) drives cervical cancer (CaCx) pathogenesis and viral oncoproteins jeopardize global gene expression in such cancers. We aimed to identify differentially expressed coding (DEcGs) and long noncoding (sense intronic and Natural Antisense Transcripts) RNA genes (DElncGs) in HPV16-positive CaCx patients (N=44) compared to HPV-negative normal individuals (N=34). Thereby, employing strand-specific RNA-seq, we determined the relationships between DEcGs and DElncGs and their clinical implications. Gene set enrichment and protein-protein interaction analyses of DEcGs revealed enrichment of processes crucial for abortive virus life cycle and cancer progression. The DEcGs formed 16 gene clusters, portraying cancer-related functions. We recorded significantly correlated co-expression of 79 DElncGs with DEcGs at proximal genomic loci, and 24 such pairs portrayed significantly altered correlation coefficients among patients, compared to normal individuals. Of these, 6 DEcGs belonged to 5 gene clusters, one of which was survival-associated. Out of the 24 correlated DEcG: DElncG pairs, 3 pairs were identified, where expression of both members was significantly associated with patient overall survival. Besides being prognostically relevant, disruption of the significant correlative relationships of such gene pairs in CaCx bears immense potential for patient-targeted therapy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/573593v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@19091c8org.highwire.dtl.DTLVardef@52fbeaorg.highwire.dtl.DTLVardef@18ecf3org.highwire.dtl.DTLVardef@6c5e30_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO A schematic representation of the analyses undertaken to draw insights on the biological relevance of joint analysis of co-expressed and significantly correlated DElncGs and DEcGs considering the ncNATs and sense intronic DElncGs, in HPV16-positive CaCx patients compared with HPV-negative normal individuals. C_FIG

cancer biology↗

AOPWIKI-EXPLORER: An Interactive Graph-based Query Engine leveraging Large Language Models

BackgroundAdverse Outcome Pathways (AOPs) provide a basis for non-animal testing, by outlining and encoding the cascade of molecular and cellular events initiated upon stressor exposure, leading to adverse effects. AOPs are therefore considered an integral part of the New Approach Methodology (NAMs) to human health risk assessment. Over the last few years, the scientific community has shown immense interest in developing AOPs with crowdsourcing, with the results of those efforts being archived in the AOP wiki: a centralized repository coordinated by the OECD, which hosts nearly 512 AOPs. However, the AOP-wiki platform currently lacks a versatile querying system, which would enable developers to integrate and explore the AOP network data in a manner that would permit their practical use in risk assessment. ImplementationThis work proposes to expose the full potential of the AOP wiki archive by adapting its data into a Labeled Property Graph (LPG) database. In addition, the solution provides both database-specific query and natural language query interfaces to support retrieval and integration of the graph data, including the ability to chain stepwise queries. To evaluate the platform, a case study is presented, with three levels of use case scenarios (simple, moderate, and complex query). This tool is freely available on GitHub (InSilicoVida/AOPWiki-explorer) for wider community usability and further enhancement. ConclusionsThe presented query engine increases the potential of AOP exploration, by reducing the time, human resources, and technical ability needed to make practical use of the data they contain. Also, its dynamic prompt generation capability, will lead to precise query generation as the interaction increases. We, therefore, anticipate that the approach will be integral to the future realisation of new approach methodologies in chemical risk assessment.

bioinformatics↗

Whole Genome Sequencing and Assembly of the House Sparrow, Passer domesticus

The common house sparrow, Passer domesticus is a small bird belonging to the family Passeridae. Here, we provide high-quality whole genome sequence data along with assembly for the house sparrow. The final genome assembly was assembled using a Shovill/SPAdes/MASURCA/BUSCO workflow, consisting of contigs spanning 268193 bases and coalescing around a 922 MB sized reference genome. We employed rigorous statistical thresholds to check the coverage, as the Passer genome showed considerable similarity to Gallus gallus (chicken) and Taeniopygia guttata (Zebra finch) genomes, also providing a functional annotation. This new annotated genome assembly will be a valuable resource as a reference for comparative and population genomic analyses of passerine, avian, and vertebrate evolution. SignificanceAvian evolution has been of great interest in the context of extinction. Annotating the genomes such as passerines would be of significant interest as we could understand the behavior/foraging traits and further explore their evolutionary landscape. In this work, we provide a full genome sequence of Indian house sparrow, viz. Passer domesticus which will serve as a useful resource in understanding the adaptability, evolution, geography, allee effects and circadian rhythms.

evolutionary biology↗

An explainable model using Graph-Wavelet for predicting biophysical properties of proteins and measuring mutational effects

Proteins hold multispectral patterns of different kinds of physicochemical features of amino acids in their structures, which can help understand proteins behavior. Here, we propose a method based on the graph-wavelet transform of signals of features of amino acids in protein residue networks derived from their structures to achieve their abstract numerical representations. Such abstract representations of protein structures hand in hand with amino-acid features can be used for different purposes, such as modelling the biophysical property of proteins. Our method outperformed graph-Fourier and convolutional neural-network-based methods in predicting the biophysical properties of proteins. Even though our method does not predict deleterious mutations, it can summarize the effect of an amino acid based on its location and neighbourhood in protein-structure using graph-wavelet to estimate its influence on the biophysical property of proteins. Such an estimate of the influence of amino-acid has the potential to explain the mechanism of the effect of deleterious non-synonymous mutations. Thus, our approach can reveal patterns of distribution of amino-acid properties in the structure of the protein in the context of a biophysical property for better classification and more insightful understanding.

bioinformatics↗

The stress-induced lincRNA JUNI is a critical factor for cancer cell survival whose interactome is a prognostic signature in clear cell renal cell carcinoma

Cancer cells rely on adaptive mechanisms to survive the multiple stressors they encounter, including replication stress, toxic metabolic products and exposure to genotoxic drugs. Understanding the factors involved in these stress responses is crucial for developing effective treatments. Here, we describe a previously unstudied long non-coding RNA (lncRNA), JUNI (JUN-DT, LINC01135), which is regulated by MAPK and responsive to stress. JUNI positively regulates the expression of its neighboring gene JUN, a key transducer of signals that regulate multiple transcriptional outputs. Our findings reveal that silencing JUNI sensitizes cancer cells to chemotherapeutic drugs or UV radiation, and that its prolonged silencing leads to cell death regardless of stress exposure, highlighting the pro-survival importance of JUNI. We identified 57 proteins that interact with JUNI and found that the activity of one of them, the MAPK phosphatase and inhibitor DUSP14, is inhibited by JUNI. This effect results in c-Jun induction following exposure of cancer cells to UV radiation and promotes cellular survival. Although JUNI regulates c-Jun and its downstream targets, the pro-survival effects in cells not exposed to stress are only partially dependent on c-Jun regulation. JUNI expression levels significantly correlate with patients survival across 11 different types of cancer. Interestingly, the correlation of DUSP14 expression levels with patients survival in nine of these tumors is coherently inverse, indicating contradicting effects that are relevant not only for c-Jun induction and cellular survival but also in human cancer. Notably, we observed particularly significant antagonistic correlations in clear cell renal cell carcinoma (ccRCC) (p=5.7E-05 for JUNI and p=2.9E- 05 for Dusp14). In fact, the expression levels of 76% of JUNI-interacting proteins predict the prognosis of ccRCC patients significantly. Furthermore, a combined hazard ratio calculation demonstrates that this gene combination serves as a highly specific prognostic signature for ccRCC. Overall, our findings reveal a new important factor in stress signaling and cellular survival that is involved in ccRCC.

cell biology↗

Senescence of endplate osteoclasts induces sensory innervation and spinal pain

Spinal pain affects individuals of all ages and is the most common musculoskeletal problem globally. Its clinical management remains a challenge as the underlying mechanisms leading to it are still unclear. Here, we report that significantly increased numbers of senescent osteoclasts (SnOCs) are observed in mouse models of spinal hypersensitivity, like lumbar spine instability (LSI) or aging, compared to controls. The larger population of SnOCs is associated with induced sensory nerve innervation, as well as the growth of H-type vessels, in the porous endplate. We show that deletion of senescent cells by administration of the senolytic drug Navitoclax (ABT263) results in significantly less spinal hypersensitivity, spinal degeneration, porosity of the endplate, sensory nerve innervation and H-type vessel growth in the endplate. We also show that there is significantly increased SnOC-mediated secretion of Netrin-1 and NGF, two well-established sensory nerve growth factors, compared to non-senescent OCs. These findings suggest that pharmacological elimination of SnOCs may be a potent therapy to treat spinal pain.

cell biology↗

Beadex, the Drosophila LIM only protein, is required for the growth of the larval neuromuscular junction and sensorimotor activities

The appropriate growth of the neurons, accurate organization of their synapses, and successful neurotransmission are indispensable for sensorimotor activities. These processes are highly dynamic and tightly regulated. Extensive genetic, molecular, physiological, and behavioural studies have identified many molecular players and investigated their roles in various neuromuscular processes. In this paper, we show that Beadex (Bx), the Drosophila LIM only (LMO) protein, is required for motor activities and neuromuscular growth of Drosophila. Bx7, a null allele, adult flies are flightless, with reduced walking and jumping activities. The larvae of Bx7, and the RNAi-mediated neuronal-specific knockdown of Bx show drastically reduced crawling behaviour, a diminished synaptic span of the neuromuscular junctions and an increased spontaneous neuronal firing with altered motor patterns in the central pattern generators (CPGs). Microarray studies identified multiple targets of Beadex that are involved in different cellular and molecular pathways, including those associated with the cytoskeleton and mitochondria, that could be responsible for the observed neuromuscular defects. With genetic interaction studies, we further show that Highwire (Hiw), a negative regulator of synaptic growth at the NMJs, negatively regulates Bx, as the latters deficiency was able to rescue the phenotype of the Hiw null mutant, HiwDN. Thus, our data indicates that Beadex functions downstream of Hiw to regulate the larval synaptic growth and physiology.

developmental biology↗

Complex relationship among vessel diameter, shear stress and blood pressure controlling vessel pruning during angiogenesis

Blood vessel pruning during angiogenesis is the optimization process of the branching pattern to improve the transport properties of a vascular network. Recent studies show that part of endothelial cells (ECs) subjected to lower shear stress migrate toward vessels with higher shear stress in opposition to the blood flow for vessel regression. While dynamic changes of blood flow and local mechano-stress could coordinately modulate EC migration for vessel regression within the closed circulatory system, the effect of complexity of haemodynamic forces and vessel properties on vessel pruning remains elusive. Here, we reconstructed a 3-dimentsional (3D) vessel structure from 2D confocal images of the growing vessels in the mouse retina, and numerically obtained the local information of blood flow, shear stress and blood pressure in the vasculature. Moreover, we developed a predictive model for vessel pruning based on machine learning. We found that the combination of shear stress and blood pressure with vessel radius was tightly corelated to vessel pruning sites. Our results highlighted that orchestrated contribution of local haemodynamic parameters was important for the vessel pruning. Authors SummaryBlood vessel networks formed by angiogenic vessel growth subsequently undergo extensive vascular remodeling process by regression of selected vascular branches. Optimization of the branching pattern in the vasculature is critical to ensure sufficient blood supply throughout the entire tissue. Recent studies have highlighted a strong relationship between the vessel remodeling and the shear stress acting on the vessel wall. However, its detailed mechanisms remain elusive due to the difficulties of estimating local haemodynamic parameters and relating them to vessel remodeling. Here, we have numerically simulated local haemodynamic parameters within the vascular network of the postnatal day 6 (P6) mouse retinal vasculature. Then, the relationship among the local shear stress, blood pressure, and vessel radius with the vessel pruning was examined. Moreover, we developed a predictive model for the vessel pruning based on the local haemodynamic parameters by a machine learning technique. Importantly, our results indicate that the combination of shear stress and blood pressure with vessel radius is tightly correlated to vessel pruning sites. Given the ongoing clinical approach to suppress tumor growth via blood vessel normalization, our results provide important knowledge for developing future medicine such as nanomedicine based on drug delivery systems.

developmental biology↗

Cooperative activities of dICA69 N-BAR and dCIP4 F-BAR domain proteins regulate membrane tubule organization in vivo

Intracellular membrane tubules play a crucial role in diverse cellular processes, and their regulation is facilitated by Bin-Amphiphysin-Rvs (BAR) domain-containing proteins. This study investigates the roles of dICA69N-BAR and dCIP4F-BAR in vivo, focusing on their impact on in vivo tubule organization. Through cell culture and immunofluorescence staining, we observed co-localization of endogenous dICA69 with dCIP4-induced membrane tubules, indicating their potential recruitment for tubule formation and maintenance. Additionally, dCIP4-positive tubules exhibit enrichment of actin regulatory proteins such as Wasp, SCAR, Arp2, Arp3, and Syndapin. Overexpressing dICA69N-BAR in S2R+ cells reveals distinct punctate patterns in the perinuclear region. An earlier study indicated that F-BAR proteins spontaneously segregate from the N-BAR domain-containing proteins during membrane tubule formation. In contrast, our observation supports a model in which different BAR-domain family members can associate with the same tubule and cooperate to fine-tune the tubule width. Moreover, our analysis highlights how dCIP4F-BAR facilitates the redistribution of dICA69N-BAR punctae, leading to altered patterns within the cells. These cooperative activities of dICA69N-BAR and dCIP4F-BAR are vital for the precise organization of intracellular tubules. Understanding the underlying mechanisms governing this cooperation provides valuable insights into cellular dynamics and the organization of membrane tubules. The implications extend to various physiological and pathological conditions related to intracellular membrane dynamics.

cell biology↗

Identification of state-specific proteomic and transcriptomic signatures of microglia-derived extracellular vesicles

Microglia are resident immune cells of the brain that play important roles in mediating inflammatory responses in several neurological diseases via direct and indirect mechanisms. One indirect mechanism may involve extracellular vesicle (EV) release, so that the molecular cargo transported by microglia-derived EVs can have functional effects by facilitating intercellular communication. The molecular composition of microglia-derived EVs, and how microglial activation states impacts EV composition and EV-mediated effects in neuroinflammation, remain poorly understood. We hypothesize that microglia-derived EVs have unique molecular profiles that are determined by microglial activation state. Using size-exclusion chromatography to purify EVs from BV2 microglia, combined with proteomic (label-free quantitative mass spectrometry or LFQ-MS) and transcriptomic (mRNA and non-coding RNA seq) methods, we obtained comprehensive molecular profiles of microglia-derived EVs. LFQ-MS identified several classic EV proteins (tetraspanins, ESCRT machinery, and heat shock proteins), in addition to over 200 proteins not previously reported in the literature. Unique mRNA and microRNA signatures of microglia-derived EVs were also identified. After treating BV2 microglia with lipopolysaccharide (LPS), interleukin-10, or transforming growth factor beta, to mimic pro-inflammatory, anti-inflammatory, or homeostatic states, respectively, LFQ-MS and RNA seq revealed novel state-specific proteomic and transcriptomic signatures of microglia-derived EVs. Particularly, LPS treatment had the most profound impact on proteomic and transcriptomic compositions of microglia-derived EVs. Furthermore, we found that EVs derived from LPS-activated microglia were able to induce pro-inflammatory transcriptomic changes in resting responder microglia, confirming the ability of microglia-derived EVs to relay functionally-relevant inflammatory signals. These comprehensive microglia-EV molecular datasets represent important resources for the neuroscience and glial communities, and provide novel insights into the role of microglia-derived EVs in neuroinflammation.

neuroscience↗