Biology subjects

Prakash, N.

Publications and source records attributed to Prakash, N..

10 recordsLinked to original sources

bioRxiv2026

Bivalent bispecific CD28 antibodies reinforce T-cell responsiveness and revert anergy/quiescence in patients treated with bispecific CD3 antibodies

Bispecific T-cell engagers stimulating CD3 (TCEs) rapidly gain momentum in oncological therapy. We report that single-agent TCE-treatment of cancer patients induces T cell hyporesponsiveness including abolished proliferative and lytic capacity. Single-cell RNA-sequencing identified transcriptional features of anergy/quiescence like upregulation of CBLB and BACH2, and suppression of AP 1-dependent activation programs due to isolated provision of T cell signal-1. To restore T cell functionality, we engineered bispecific costimulators (BiCos) which deliver signal-2 via highly efficient bivalent CD28-binding yet maintain strictly target-restricted activity after binding antigens expressed not only by tumor cells but also the extracellular matrix. Preclinical analyses documented that BiCos potentiate efficacy of single-agent TCE treatment with activity exceeding that of univalent Knob-into-Hole CD28-costimulators and revert T cell hyporesponsiveness. In humanized mice, BiCos induced elimination of established tumors in combination with very low doses of TCE. Finally, BiCos reversed molecular hallmark features of quiescence such as high expression of BACH2 and KLF2 in T cells of TCE-treated patients resulting in complete restoration of cellular function, thereby reinstating durable antitumor immunity.

immunology↗

bioRxiv2025

LFA-1 Interaction with GBP-130 on Plasmodium falciparum-infected Red Blood Cells mediates NK Cell Activation and Parasite Control

Natural Killer (NK) cells contribute to early immunity against Plasmodium falciparum by recognizing and eliminating infected red blood cells (iRBCs), a process mediated in part by the integrin LFA-1. However, the cognate parasite ligand for LFA-1 has remained unknown. Here, we identify Glycophorin Binding Protein-130 (PfGBP-130) as a surface-expressed ligand on iRBCs that binds the I-domain of LFA-1 (LFA-1 I). Using an LFA-1 I-Fc fusion protein, we demonstrate stage-specific binding to iRBCs, and LC-MS/MS analysis of immunopreciptates of I-Fc bound to iRBC revealed PfGBP-130 as a high-confidence interactor. Recombinant PfGBP-130 binds NK and THP-1 cells in an LFA-1-dependent manner. Co-culture assays show that PfGBP-130 promotes NK cell activation, degranulation, and facilitates contact-dependent killing of iRBCs. Neutralizing antibodies against PfGBP-130 significantly impair these responses. Our findings establish PfGBP-130 as the LFA-1 ligand on iRBCs, providing new insight into NK cell-mediated immunity in malaria and identifying a potential target for host-directed interventions.

immunology↗

bioRxiv2025

Nociceptin Orphanin F/Q Pathways are Dysregulated by Stress and Modulate Reward Learning and Motivation Across Species

Nociceptin orphanin F/Q has been implicated in stress-related depressive phenotypes. Specifically, exposure to chronic stressors upregulates nociceptin receptors (NOPR), whereas NOPR antagonism has anti-depressant/anti-anhedonic effects. The mechanisms underlying these effects remain, however, unclear. Here, we investigated the role of NOPR in depressive phenotypes alongside potentially prohedonic effects of NOPR antagonism across species. In Study 1, we evaluated whether exposure to early-life adversity (ELA) upregulated ventral tegmental area (VTA) and striatal prepronociceptin (Pnoc) gene expression in adult mice. In Study 2, we tested whether chronic social defeat altered Pnoc gene expression in reward-related regions. To establish whether direct NOPR modulation is implicated in reward-related behaviors, in Study 3, we assessed whether NOPR antagonism alters reward learning in rats. Finally, in Study 4, we tested whether NOPR antagonism boosts motivation among depressed humans. ELA induced anhedonic behavior and increased Pnoc expression in the VTA; in females (but not males), ELA increased Pnoc expression in the dorsal striatum (Study 1). Furthermore, chronic stress reduced Pnoc-expressing cells in the VTA, dorsal striatum and prefrontal cortex and susceptible rats showed reduced VTA NOPR gene (Oprl1)-expressing cells (Study 2). In a behavioral assay, a single 30-mg dose of a NOPR antagonist (BTRX-246040) boosted reward learning in rats (Study 3). Finally, in depressed humans, relative to placebo, 8-week treatment with BTRX-246040 increased incentive motivation (Study 4). Collectively, our findings indicate that chronic stressors alter Pnoc and mRNA levels of Pnoc-expressing cells in a sex-selective and region-specific manner impacting reward structures, and that NOPR antagonism shows anti-anhedonic properties.

neuroscience↗

bioRxiv2025

Hypoxia modulates human pulmonary arterial adventitial fibroblast phenotype through HIF-1α activation

Hypoxic pulmonary hypertension (HPH) develops in association with diseases characterized by low oxygen levels leading to pulmonary artery (PA) narrowing and death. Hypoxia has been linked to increased PA collagen and changes in PA adventitial fibroblast (PAAF) metabolism. However, the mechanisms by which hypoxia regulates PAAF function are unknown. Hypoxia-inducible factor-1 (HIF-1) is a subunit of a transcription factor that is degraded in normoxia but stabilized in hypoxia and is involved in extracellular matrix remodeling by fibroblasts. We examined the role of hypoxia and HIF-1 in regulating PAAF function. Human PAAF (HPAAF) were cultured in normoxic and hypoxic conditions. Cells were further treated with HIF1- inhibitor or no drug. Protein expression, mRNA expression, enzyme activity, and metabolite concentration were examined. Male C57BL6/J mice were exposed to 0 or 10 days of hypoxia after which right ventricular hemodynamics and tissue metabolism were assessed. Hypoxia led to an increase in collagen content and decrease in matrix metalloproteinase-2 (MMP2) activity. HIF-1 inhibition limited collagen accumulation and restored MMP2 activity. HPAAF demonstrated elevated lactic acid concentration and decreased ATP in hypoxia. HIF-1 inhibition blunted these effects. Mice exposed to hypoxia developed significant elevation in right ventricle systolic pressures and had decreased ATP levels in pulmonary tissue. This study investigated the mechanisms by which hypoxia drives HPAAF-mediated collagen accumulation and metabolic changes. We identify the key role of HIF-1 in regulating changes. These findings provide important insights into understanding HPAAF-mediated PA remodeling and help identify possible novel therapeutic targets.

bioengineering↗

bioRxiv2023

Experimental safety testing confirms that the NSAID nimesulide is toxic to Gyps vultures in India

Population declines of Gyps vultures throughout South Asia were caused by unintentional poisoning by the NSAID diclofenac, which was subsequently banned. However, other vulture-toxic NSAIDs are available, including nimesulide, which, in experiments carried out in South Africa, was shown to be toxic to Gyps vultures. We report on safety-testing of nimesulide carried out on Himalayan Griffons G. himalayensis. We gave two vultures a dose of nimesulide by oral gavage at the maximum level of exposure, with two controls dosed with benzyl alcohol. In the two tested birds, plasma nimesulide concentrations peaked after six hours, while serum uric acid concentrations increased steadily up until 24 hours post-treatment, after which both birds died, displaying severe visceral gout. The control birds showed no adverse clinical or biochemical signs. We confirm that nimesulide is toxic to Gyps vultures. Veterinary use of nimesulide should be banned in all Gyps vulture range countries in the region.

pharmacology and toxicology↗

bioRxiv2023

Hardwired to attack: Transcriptionally defined amygdala subpopulations play distinct roles in innate social behaviors.

Social behaviors are innate and supported by dedicated neural circuits, but it remains unclear whether these circuits are developmentally hardwired or established through social experience. Here, we revealed distinct response patterns and functions in social behavior of medial amygdala (MeA) cells originating from two embryonically parcellated developmental lineages. MeA cells in male mice that express the transcription factor Foxp2 (MeAFoxp2) are specialized for processing male conspecific cues even before puberty and are essential for adult inter-male aggression. In contrast, MeA cells derived from the Dbx1-lineage (MeADbx1) respond broadly to social cues and are non-essential for male aggression. Furthermore, MeAFoxp2 and MeADbx1 cells show differential anatomical and functional connectivity. Altogether, our results support a developmentally hardwired aggression circuit at the level of the MeA and we propose a lineage-based circuit organization by which a cells embryonic transcription factor profile determines its social information representation and behavior relevance during adulthood. HighlightsO_LIMeAFoxp2 cells in male mice show highly specific responses to male conspecific cues and during attack while MeADbx1 cells are broadly tuned to social cues. C_LIO_LIThe male-specific response of MeAFoxp2 cells is present in naive adult males and adult social experience refines the response by increasing its trial-to-trial reliability and temporal precision. C_LIO_LIMeAFoxp2 cells show biased response to males even before puberty. C_LIO_LIActivation of MeAFoxp2, but not MeADbx1, cells promote inter-male aggression in naive male mice. C_LIO_LIInactivation of MeAFoxp2, but not MeADbx1, cells suppresses inter-male aggression. C_LIO_LIMeAFoxp2 and MeADbx1 cells show differential connectivity at both the input and output levels. C_LI

neuroscience↗

bioRxiv2022

Molecular diversity and connectivity of accessory olfactory system neurons

Olfaction is the primary sensory modality by which most vertebrate species interpret environmental cues for appropriate behavioral outputs. The olfactory system is subdivided into main (MOS) and accessory (AOS) components which process volatile and non-volatile cues. While much is known regarding the molecular diversity of neurons that comprise the MOS, less is known about the AOS. Here, focusing on the AOS which is largely comprised of the peripheral vomeronasal organ (VNO), the accessory olfactory bulb (AOB) and the medial subnucleus of the amygdala (MeA), we studied the molecular diversity and neuronal subtype connectivity of this interconnected circuit. We show that populations of neurons of the AOS can be molecularly subdivided based on their current or prior expression of the transcription factors Foxp2 or Dbx1. We show that the majority of AOB neurons that project directly to the MeA are of the Foxp2-lineage. Using single cell patch clamp electrophysiology, we further reveal that in addition to sex-specific differences across lineage, the relative contributions of excitatory and inhibitory inputs to MeA Foxp2-lineage neurons differ between sexes. Together, this work uncovers a novel molecular diversity of AOS neurons and lineage- and sex-differences in patterns of connectivity.

neuroscience↗

bioRxiv2020

Intercellular Arc signaling regulates vasodilation

Injury responses require communication between different cell types in the skin. Sensory neurons contribute to inflammation and can secrete signaling molecules that affect non-neuronal cells. Despite the pervasive role of translational regulation in nociception, the contribution of activity-dependent protein synthesis to inflammation is not well understood. To address this problem, we examined the landscape of nascent translation in DRG neurons treated with inflammatory mediators using ribosome profiling. We identified the activity-dependent gene, Arc, as a target of privileged translation in vitro and in vivo. Inflammatory cues promote local translation of Arc in the skin. Arc deficient mice display exaggerated paw temperatures and vasodilation in response to an inflammatory challenge. Since Arc has recently been shown to be released from neurons in extracellular vesicles, we hypothesized that intercellular Arc signaling regulates the inflammatory response in skin. We found that the excessive thermal responses and vasodilation observed in Arc defective mice are rescued by injection of Arc-containing extracellular vesicles into the skin. Our findings suggest that activity-dependent production of Arc in afferent fibers regulates neurogenic inflammation through intercellular signaling. HIGHLIGHTSO_LIRibosome profiling identifies Arc as a target of activity-dependent translation C_LIO_LIArc is present in the DRG, spinal cord, and skin C_LIO_LIInduced Arc biosynthesis in skin requires the presence of afferent fibers C_LIO_LIArc-deficient mice have exaggerated inflammation that is rescued by Arc-containing extracellular vesicles C_LI

neuroscience↗

bioRxiv2020

Canonical Wnt-signaling modulates the tempo of dendritic growth of adult-born hippocampal neurons

In adult hippocampal neurogenesis neural stem/progenitor cells generate new dentate granule neurons that contribute to hippocampal plasticity. The establishment of a morphologically defined dendritic arbor is central to the functional integration of adult-born neurons. Here, we investigated the role of canonical Wnt/{beta}-catenin-signaling in dendritogenesis of adult-born neurons. We show that canonical Wnt-signaling follows a biphasic pattern, with high activity in stem/progenitor cells, attenuation in early immature neurons, and re-activation during maturation, and demonstrate that the biphasic activity pattern is required for proper dendrite development. Increasing {beta}-catenin-signaling in maturing neurons of young adult mice transiently accelerated dendritic growth, but eventually resulted in dendritic defects and excessive spine numbers. In middle-aged mice, in which protracted dendrite and spine development was paralleled by lower canonical Wnt-signaling activity, enhancement of {beta}-catenin-signaling restored dendritic growth and spine formation to levels observed in young adult animals. Our data indicate that precise timing and strength of {beta}-catenin-signaling is essential for the correct functional integration of adult-born neurons and suggest Wnt/{beta}-catenin-signaling as a pathway to ameliorate deficits in adult neurogenesis during aging.

neuroscience↗

bioRxiv2019

Serotonergic plasticity in the dorsal raphe nucleus characterizes susceptibility and resilience to anhedonia

Chronic stress induces anhedonia in susceptible, but not resilient individuals, a phenomenon observed in humans as well as animal models, but the molecular mechanisms underlying susceptibility and resilience are not well understood. We hypothesized that the serotonergic system, which is implicated in stress, reward and antidepressant therapy, may play a role. We found that plasticity of the serotonergic system contributes to the differential vulnerability to stress displayed by susceptible and resilient animals. Stress-induced anhedonia was assessed in adult male rats using social defeat and intracranial self-stimulation (ICSS), while changes in serotonergic phenotype were investigated using immunohistochemistry and in situ hybridization. Susceptible, but not resilient, rats displayed an increased number of neurons expressing the biosynthetic enzyme for serotonin, tryptophan-hydroxylase-2 (TPH2), in the ventral subnucleus of the dorsal raphe nucleus (DRv). Further, a decrease in the number of DRv glutamatergic neurons was observed in all stressed animals. This neurotransmitter plasticity is dependent on DR activity, as was revealed by chemogenetic manipulation of the central amygdala, a stress-sensitive nucleus that forms a major input to the DR. Activation of amygdalar corticotropin releasing hormone (CRH)+ neurons abolished the increase in DRv TPH2+ neurons and ameliorated stress-induced anhedonia in susceptible animals. These findings show that activation of amygdalar projections induces resilience, and suppresses the gain of serotonergic phenotype in the DR that is characteristic of susceptible animals. This molecular signature of vulnerability to stress-induced anhedonia and the active nature of resilience could be a target of new treatments for stress-related disorders like depression.\n\nSIGNIFICANCE STATEMENTDepression and other mental disorders can be induced by chronic or traumatic stressors. However, some individuals are resilient and do not develop depression in response to chronic stress. A complete picture of the molecular differences between susceptible and resilient individuals is necessary to understand how plasticity of limbic circuits is associated with the pathophysiology of stress-related disorders. Using a rodent model, our study identifies a novel molecular marker of susceptibility to stress-induced anhedonia, a core symptom of depression, and a means to modulate it. These findings will guide further investigation into cellular and circuit mechanisms of resilience, and the development of new treatments for depression.

neuroscience↗