Biology subjects

Bhandari, P.

Publications and source records attributed to Bhandari, P..

13 recordsLinked to original sources

bioRxiv2026

Molecular MRI of Neuroinflammation in Alzheimer's Disease using a Folate-targeted Nanoprobe

Background: Neuroinflammation, driven by activated microglia, plays a central role in the pathogenesis of Alzheimer's disease (AD). Non-invasive imaging of neuroinflammation holds promise for advancing our understanding of disease mechanisms and evaluating anti-inflammatory therapeutic strategies. The folate receptor (FR), specifically its {beta} isoform, has been identified as a marker of pro-inflammatory myeloid cells in peripheral inflammatory diseases; however, its association with AD neuroinflammation remains unknown. In this work, we first determined FR expression in microglia in mouse models of AD and subsequently evaluated molecular MRI (mMRI) using a folate-targeted nanoprobe for in vivo imaging of the folate receptor expression. Methods and results: Microglial activation and FR expression in APP/PS1 and P301S transgenic mouse models of AD was measured using flow cytometry. A FR-targeted nanoprobe for mMRI was prepared by functionalizing high T1-relaxivity liposomal gadolinium nanoparticle with folic acid. Following intravenous injection, localization of the nanoprobe in the brains of aged transgenic and wild-type mice was measured using T1-weighted MRI. Post-mortem microscopy measured nanoprobe localization relative to microglia and amyloid pathology. In both mouse models, FR{beta} was significantly (p < 0.05) upregulated in pro-inflammatory microglia expressing TNF and IL-1{beta}. The folate-targeted nanoprobe demonstrated MR signal enhancement in the cortical and hippocampal regions of transgenic mice but not in wild type mice; non-targeted nanoprobe control did not demonstrate signal enhancement in brain of transgenic mice. Microscopy confirmed colocalization of FR-targeted nanoprobe with IBA1-positive microglia/macrophages and amyloid plaques. Conclusions: Pro-inflammatory microglia exhibit elevated levels of FR, and its measurement by non-invasive mMRI is a promising marker of neuroinflammation in AD.

neuroscience↗

bioRxiv2026

Large-scale dimensional behavioral profiling dissociates fear memory from locomotor confounds in mice: The necessity of baseline-normalized metrics

Fear conditioning is widely used to assess associative memory in mice, yet percent freezing conflates memory with baseline locomotor and anxiety-related traits. A systematic survey of recent studies (2020-2025) found that fewer than 1% statistically integrate locomotor activity into freezing analyses. Here, we address this gap using a large-scale dataset of >10,000 mice across >160 comparisons, including genetic mutations, pharmacological interventions and aging, tested in 15 standardized behavioral paradigms. Conventional freezing scores covaried strongly with general locomotor activity, obscuring memory-related phenotypes. Multiple factor analysis identified two principal behavioral dimensions, locomotor activity and learning/memory: conventional freezing aligned with the locomotor dimension, whereas freezing subtraction and the activity suppression ratio mapped onto the memory dimension and improved detection of synaptic plasticity phenotypes. These analyses show that baseline locomotor normalization is essential for interpreting fear conditioning as a memory assay and provide an open framework for selecting and reporting locomotor-normalized metrics.

neuroscience↗

bioRxiv2026

CCN3-derived peptide BLR-200 impairs YAP activation and attenuates bleomycin-induced skin fibrosis through blocking the generation of Sfrp2-positive fibroblasts

An autocrine pro-adhesive/pro-contractile signaling loop, through the mechanosensitive transcriptional cofactor YAP, promotes fibrosis. The CCN family of matricellular proteins modify adhesive signaling. Of these, CCN3 is antifibrotic. We show that BLR-200, a CCN3-derived peptide, has anti-fibrotic properties in the bleomycin-induced model of scleroderma skin fibrosis. In vitro, BLR-200 delayed, but did not abolish, fibroblast adhesion to collagen and nuclear YAP localization. In vivo, BLR-200 prevented/treated bleomycin-induced skin fibrosis, and reduced bleomycin-induced expression of profibrotic genes including -smooth muscle actin, CCN1 and CCN2. Lineage tracing and scRNA-seq analyses revealed that the myofibroblasts in this model were quantitatively derived from collagen-lineage Pi16+/Col15+ve fibroblasts. BLR-200 prevented myofibroblast differentiation in this model and trajectory of fibroblasts toward a Sfrp2-positive subset, a cell type associated with poor clinical outcome. BLR-200 impairs YAP activation in vitro and appearance of translationally-relevant fibroblast subtypes in vivo and is a novel anti-fibrotic agent for SSc skin fibrosis. HIGHLIGHTS-SSc skin fibrosis, a major unmet need, is driven by an activated mechanotransduction/YAP pathway; how to block this pathway clinically is unclear -members of the CCN family of matricellular proteins are adhesive signaling modifiers; herein, we identify BLR-200, a synthetic peptide derived from CCN3, based on its ability to impair, but not ablate, YAP nuclear localization and fibroblast spreading/attachment to collagen -BLR-200 blocks and treats progression of bleomycin-induced skin fibrosis -In the bleomycin model, lineage tracing analysis revealed that collagen-lineage cells are the primary source of myofibroblasts -BLR-200 blocks myofibroblast differentiation concomitant with reduced progression toward Col8a1+ve and Sfrp2+ ve fibroblasts, populations implicated in SSc pathogenesis -BLR-200 represents a novel, translationally relevant drug candidate for SSc skin fibrosis

cell biology↗

bioRxiv2025

Serosurveillance Studies of Peste des Petits Ruminants (PPR) Virus in Sheep and Goats in South Asia: A Systematic Review and Meta-analysis

BackgroundPeste des Petits Ruminants (PPR), also known as the goat plague, is one of the WOAH-listed A, highly contagious and economically important viral transboundary animal diseases affecting small ruminants, and having a significant impact on the global livestock industry and international animal traffic. ObjectiveThe present study aimed to use a systematic approach to assess the pooled seroprevalence of PPRV in sheep and goats in South Asia, through a systematic review and meta-analysis of published data. MethodsA thorough search on various databases was performed to identify published research articles published between January 2000 and June 2025 reporting the seroprevalence of PPRV in small ruminants in South Asia. The articles were chosen on the basis of specific inclusion and exclusion criteria. Since the heterogeneity among the studies was significant, the pooled seroprevalence was estimated via a random effects meta-analysis model, using Stata (v19) and R software (v4.5.0). ResultsIn sheep and goats, the estimated pooled seroprevalence of PPR was 42.4% (95% CI: 35.0-49.9), whereas it was 41.8% (95% CI: 33.7-50.1) in goats and 44.5% (95% CI: 37.0- 52.0) in sheep. Subgroup analysis revealed that the pooled seroprevalence of PPRV in sheep and goat by country and vaccination status was greater in Nepal (57.0%, 95% CI: 8.4-97.7) and in vaccinated animals (57.5%, 95% CI: 47.9-66.9). ConclusionThis study highlights the need for coordinated actions, including vaccination, surveillance, and strict biosecurity, to control and eradicate the disease effectively. Moreover, authorities should adopt evidence-based strategies to support the global goal of eradicating PPR by 2030, as recommended by the WOAH.

microbiology↗

bioRxiv2024

Accelerated amyloid deposition in SARS-CoV-2 infected mouse models of Alzheimer's disease

Familial Alzheimers disease (AD) involving known AD causing genes accounts for a small fraction of cases, the vast majority are sporadic. Neuroinflammation, secondary to viral infection, has been suggested as an initiating or accelerating factor. In this work we tested the hypothesis that SARS-CoV-2 (SCV2) viral infection accelerates the development of AD pathology in mouse models of AD. We profiled transcriptomic changes using transgenic APP/PSEN1 and P301S mouse models that develop AD pathology and k18hACE2 mice that express the humanized ACE2 receptor used by SCV2 to enter cells. This study identified the interferon and chemokine responses constituting key shared pathways between SCV2 infection and the development of AD pathology. Two transgenic mouse models of AD: APP/PSEN1 (develops amyloid pathology) and 3xTg AD (develops both amyloid and tau pathology) were crossed with k18-hACE2 mice to generate hybrid hACE2-3xTg and hACE2-APP/PSEN1 mice. Neuroinflammation and amyloid deposition in the brain of infected mice were imaged in vivo using molecular MRI (mMRI) probes and confirmed postmortem by histopathology. Results show that 11-14-month-old SCV2 infected hACE2-3xTg mice exhibit neuroinflammation 10 days post infection and 4-5-month-old hACE2-APP/PS1 hybrid mice develop amyloid deposits, while age-matched uninfected mice exhibit neither phenotype. This suggests that SCV2 infection could induce or accelerate AD when risk factors are present.

neuroscience↗

bioRxiv2022

Transport and utilization of glycogen breakdown products by Gardnerella spp. from the human vaginal microbiome

Multiple Gardnerella species frequently co-occur in vaginal microbiomes, and several factors including competition for nutrients such as glycogen could determine their population structure. Although Gardnerella spp. can hydrolyze glycogen to produce glucose, maltose, maltotriose and maltotetraose, how these sugars are transported and utilized for growth is unknown. We determined the distribution of genes encoding transporter proteins associated with the uptake of glucose, maltose, and malto-oligosaccharides and maltodextrins among Gardnerella species. A total of five different ABC transporters were identified in Gardnerella spp. of which MusEFGK2I and MalXFGK were conserved across all 15 Gardnerella isolates. RafEFGK and TMSP (trehalose, maltose, sucrose and palatinose) operons were specific to G. vaginalis while the MalEFG transporter was identified in G. leopoldii only. Although no glucose specific sugar-symporters were identified, putative glucose/galactose porters and components of a phosphotransferase system were identified. In laboratory experiments, all Gardnerella isolates grew more in the presence of glucose, maltose, maltotriose and maltotetraose compared to un-supplemented media. In addition, most isolates (10/15) showed significantly more growth on maltotetraose compared to glucose (Kruskal Wallis, P < 0.05) suggesting their preference for longer chain malto-oligosaccharides. Our findings show that although putative MusEFGK2I and MalXFGK transporters are found in all Gardnerella spp., some species-specific transporters are also present. Observed distribution of genes encoding transporter systems was consistent with laboratory observations that Gardnerella spp. grow better on longer chain malto-oligosaccharides. ImportanceIncreased abundance of Gardnerella spp. is a diagnostic characteristic of bacterial vaginosis, an imbalance in the human vaginal microbiome associated with troubling symptoms and negative reproductive health outcomes, including increased transmission of sexually transmitted infections and preterm birth. Competition for nutrients is likely an important factor in causing dramatic shifts in the vaginal microbial community. Gardnerella produces enzymes to digest glycogen, an important nutrient source for vaginal bacteria, but little is known about the mechanisms in Gardnerella for uptake of the products of this digestion, or whether Gardnerella use some or all of the products. Our results indicate that Gardnerella may have evolved to preferentially use a subset of the glycogen breakdown products, which would help them reduce direct competition with some other bacteria in the vagina.

microbiology↗

bioRxiv2022

A two-pool mechanism of vesicle release in medial habenula terminals underlies GABAB receptor-mediated potentiation

GABAB receptor (GBR) activation inhibits neurotransmitter release in axon terminals in the brain, except in medial habenula (MHb) terminals, which show robust potentiation. However, mechanisms underlying this enigmatic potentiation remain elusive. Here, we report that GBR activation induces a transition from tonic to phasic release accompanied by a 4-fold increase in readily releasable pool (RRP) size in MHb terminals, mirrored by a similar increase in the docked vesicle number at the presynaptic active zone (AZ). The tonic and phasic release vesicles have distinct coupling distances. We identified two vesicle-associated molecules, synaptoporin and CAPS2, selectively involved in tonic and phasic release, respectively. Synaptoporin mediates augmentation of tonic release and CAPS2 stabilizes readily releasable vesicles during phasic release. A newly developed "Flash and Freeze-fracture" method revealed selective recruitment of CAPS2 to the AZ during phasic release. Thus, we propose a novel two-pool mechanism underlying the GBR-mediated potentiation of release from MHb terminals.

neuroscience↗

bioRxiv2022

Glycogen degrading activities of catalytic domains of α-amylase and α-amylase-pullulanase enzymes conserved in Gardnerella spp. from the vaginal microbiome

Gardnerella spp. are associated with bacterial vaginosis, in which normally dominant lactobacilli are replaced with facultative and anaerobic bacteria including Gardnerella spp. Co-occurrence of multiple species of Gardnerella is common in the vagina and competition for nutrients such as glycogen likely contributes to the differential abundances of Gardnerella spp. Glycogen must be digested into smaller components for uptake; a process that depends on the combined action of glycogen degrading enzymes. In this study, the ability of culture supernatants of 15 isolates of Gardnerella spp. to produce glucose, maltose, maltotriose and maltotetraose from glycogen was demonstrated. Carbohydrate active enzymes were identified bioinformatically in Gardnerella proteomes using dbCAN2. Identified proteins included a single domain -amylase (EC 3.2.1.1) (encoded by all 15 isolates) and an -amylase-pullulanase (EC 3.2.1.41) containing amylase, carbohydrate binding modules and pullulanase domains (14/15 isolates). To verify the sequence-based functional predictions, the amylase and pullulanase domains of the -amylase-pullulanase, and the single domain -amylase were each produced in E. coli. The -amylase domain from the -amylase-pullulanase released maltose, maltotriose and maltotetraose from glycogen, and the pullulanase domain released maltotriose from pullulan and maltose from glycogen, demonstrating that the Gardnerella -amylase-pullulanase is capable of hydrolyzing -1,4 and -1,6 glycosidic bonds. Similarly, the single domain -amylase protein also produced maltose, maltotriose and maltotetraose from glycogen. Our findings show that Gardnerella spp. produce extracellular amylase enzymes as public goods that can digest glycogen into maltose, maltotriose and maltotetraose that can be used by the vaginal microbiota. ImportanceIncreased abundance of Gardnerella spp. is a diagnostic characteristic of bacterial vaginosis, an imbalance in the human vaginal microbiome associated with troubling symptoms, and negative reproductive health outcomes, including increased transmission of sexually transmitted infections and preterm birth. Competition for nutrients is likely an important factor in causing dramatic shifts in the vaginal microbial community but little is known about the contribution of bacterial enzymes to the metabolism of glycogen, a major food source available to vaginal bacteria. The significance of our research is characterizing the activity of enzymes conserved in Gardnerella species that contribute to the ability of these bacteria to utilize glycogen.

microbiology↗

bioRxiv2022

Visualization of Retroplacental Clear Space Disruption in a Mouse Model of Placental Accreta

IntroductionPrior preclinical studies established the utility of liposomal nanoparticle blood-pool contrast agents in visualizing the retroplacental clear space (RPCS), a marker of normal placentation, while sparing fetuses from exposure because the agent does not cross the placental barrier. In this work we characterized RPCS disruption in a mouse model of placenta accreta spectrum (PAS) using these agents. MethodsContrast-enhanced MRI (CE-MRI) and computed tomography (CE-CT) using liposomal nanoparticles bearing gadolinium (liposomal-Gd) and iodine were performed in pregnant Gab3-/- and wild type (WT) mice at day 16 of gestation. CE-MRI was performed on a 1T scanner using a 2D T1-weighted sequence (100x100x600 {micro}m3 voxels) and CE-CT was performed at a higher resolution (70x70x70 {micro}m3 voxels). Animals were euthanized post-imaging and feto-placental units (FPUs) were harvested for histological examination. RPCS conspicuity was scored through blinded assessment of images. ResultsPregnant Gab3-/- mice show elevated rates of complicated pregnancy. Contrast-enhanced imaging demonstrated frank infiltration of the RPCS of Gab3-/- FPUs. RPCS in Gab3-/- FPUs was smaller in volume, demonstrated a heterogeneous signal profile, and received lower conspicuity scores than WT FPUs. Histology confirmed in vivo findings and demonstrated staining consistent with a thinner RPCS in Gab3-/- FPUs. DiscussionImaging of the Gab3-/- mouse model at late gestation with liposomal contrast agents enabled in vivo characterization of morphological differences in the RPCS that could cause the observed pregnancy complications. An MRI-based method for visualizing the RPCS would be valuable for early detection of invasive placentation.

developmental biology↗

bioRxiv2022

Multi-modal Imaging of Disease Progression in TH-MYCN Mouse Models of Neuroblastoma

MYCN is a major driver for neuroblastoma (NB) and the tyrosine hydroxylase (TH)-MYCN transgenic mouse model is extensively used for preclinical NB studies. However, spatio-temporal NB progression in the TH-MYCN model has not been studied, and questions remain about the value of implanted models as a surrogate for transgenic mice. In this work, we used magnetic resonance imaging (MRI) to study tumor progression and nanoparticle contrast-enhanced computed tomography (n-CECT) to assess tumor vascular architecture in TH-MYCN transgenic mice (2-7 weeks of age) and TH-MYCN+/+-derived orthotopic allograft and syngeneic mice (2-5 weeks post-tumor implantation). Tumors in TH-MYCN transgenic mice became evident in the abdominal paraspinal region at week 5. A delayed thoracic paraspinal mass became evident at week 6 and most mice succumbed by week 7. In allograft and syngeneic mice, single mass tumor growth was restricted to the peritoneal cavity. N-CECT revealed a predominantly microvascular network in TH-MYCN tumors while implanted tumors exhibited heterogeneous and tortuous vessels. N-CECT quantitative analysis demonstrated high vascularity (tumor fractional blood volume ~ 0.12) in all models. Multi-modal imaging of TH-MYCN transgenic and implanted models revealed differences in growth patterns and vascular architecture that should be considered in designing preclinical studies.

cancer biology↗

bioRxiv2020

Characterization of an α-glucosidase enzyme conserved in Gardnerella spp. isolated from the human vaginal microbiome

Gardnerella spp. in the vaginal microbiome are associated with bacterial vaginosis, a dysbiosis in which a lactobacilli dominant microbial community is replaced with mixed aerobic and anaerobic bacteria including Gardnerella species. The co-occurrence of multiple Gardnerella species in the vaginal environment is common, but different species are dominant in different women. Competition for nutrients, particularly glycogen present in the vaginal environment, could play an important role in determining the microbial community structure. Digestion of glycogen into products that can be taken up and further processed by bacteria requires the combined activities of several enzymes collectively known as amylases, which belong to glycoside hydrolase family 13 (GH13) within the CAZy classification system. GH13 is a large and diverse family of proteins, making prediction of their activities challenging. SACCHARIS annotation of the GH13 family in Gardnerella resulted in identification of protein domains belonging to eight subfamilies. Phylogenetic analysis of predicted amylase sequences from 26 Gardnerella genomes demonstrated that a putative -glucosidase-encoding sequence, CG400_06090, was conserved in all species in the genus. The predicted -glucosidase enzyme was expressed, purified and functionally characterized. The enzyme was active on a variety of maltooligosaccharides over a broad pH range (4.0 - 8) with maximum activity at pH 7. The Km, kcat and kcat/Km values for the substrate 4-nitrophenyl -D-glucopyranoside were 8.3 M, 0.96 min-1 and 0.11 M-1min-1 respectively. Glucose was released from maltose, maltotriose, maltotetraose and maltopentaose, but no products were detected on thin layer chromatography when the enzyme was incubated with glycogen. Our findings show that Gardnerella spp. produce an -glucosidase enzyme that may contribute to the complex and multistep process of glycogen metabolism by releasing glucose from maltooligosaccharides.

microbiology↗

bioRxiv2020

GABAB receptor auxiliary subunits modulate Cav2.3-mediated release from medial habenula terminals

The connection from medial habenula (MHb) to interpeduncular nucleus is critical for aversion- and addiction-related behaviors. This pathway is unique in selective expression of R-type voltage-gated Ca2+ channels (Cav2.3) in its terminals, and robust potentiation of release via presynaptic GABAB receptors (GBRs). To understand the mechanism underlying this peculiar GBR effect, we examined the presynaptic localization and function of Cav2.3, GBR, and its auxiliary subunits, K+-channel tetramerization domain-containing (KCTD) proteins. We found selective co-expression of KCTD12b and Cav2.3 at the presynaptic active zone. GBR-mediated potentiation remained intact in KCTD12b KO mice but lasted significantly shorter. This impairment was associated with increased release and an insertion of KCTD8 into the active zone. In heterologous cells, we found direct binding of KCTD8 and KCTD12b to Cav2.3, and potentiation of Cav2.3 currents by KCTD8. The unexpected interaction of Cav2.3 with KCTDs therefore provides a means to scale synaptic strength independent of GBR activation.

neuroscience↗

bioRxiv2017

Necrosis triggered by Mycobacterium tuberculosis alters macrophage triglyceride metabolism and inflammatory response in a DGAT1-dependent manner

Tuberculosis granulomas represent a site of controlling bacterial dissemination at the cost of host tissue damage. Within the heterogenous array of TB granulomas, some contain triglyceride (TG) rich foamy macrophages, the etiology and function of which remains largely unexplained. Here we show that necrosis of tuberculosis lesions and M. tuberculosis (Mtb) infected macrophages elicits a bystander response of triglyceride storage. We elucidate a role for the RD1 region of mycobacterial genome to be a key player in this phenomenon. TG storage in necrosis associated foamy macrophages promoted the pro-inflammatory state of macrophages while silencing expression of diacylglycerol O-acyltransferase (DGAT1) suppressed expression of pro-inflammatory genes. Surprisingly, acute infection with Mtb led to lipolysis of host TG, rather than synthesis, suggesting mobilization of triglyceride stored within macrophage lipid droplets to be involved in the inflammatory response to infection. Our data is likely to open new avenues for management of the inflammatory response during infection.

immunology↗