Biology subjects

Sharma, K.

Publications and source records attributed to Sharma, K..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

Monocyte-derived macrophage recruitment mediated by TRPV1 is required for eardrum wound healing

The tympanic membrane (TM), or eardrum, is a thin, sensitive tissue critical for hearing by vibrating and transmitting sound waves to the inner ear. TM perforation and development of otitis media and conductive hearing loss are commonly seen in the clinic. In this study, we demonstrate the role of TRPV1 signaling mediated macrophage recruitment and angiogenesis in TM repair. By creating a wounded TM mouse model with a perforation in the anteroinferior region of the pars tensa -- a region in humans often damaged in traumatic injury, we observed a massive accumulation of macrophages in the vicinity of the acutely wounded TM. Using 5-Ethynyl-2-deoxyuridine pause labeling and a chimeric bone marrow transplant model, we found that most of the recruited macrophages did not originate from local tissue-resident macrophages but rather from blood-circulating monocytes. Parallel to macrophage recruitment, angiogenesis was observed near the wound on day 3 after perforation and further progressed by day 7. The angiogenic process was strongly associated with the recruited macrophages, as macrophage depletion resulted in a notable reduction in angiogenesis. At the transcriptional level, we found that macrophages facilitate angiogenesis through several signaling pathways. Additionally, we identified direct intercellular communication between macrophages and endothelial cells mediated by phosphoprotein 1 signaling. Furthermore, Gene Ontology analysis of bulk RNA sequencing data from TMs revealed that the macrophage recruitment is associated with neuroinflammatory responses. Using a fluorescence reporter mouse driven by TRPV1, we discovered that the TM contains rich sensory nerve fibers expressing TRPV1. A genetic mutation in the Trpv1 gene resulted in a marked decrease in the expression of neuroinflammatory genes, such as Tac1. This decrease subsequently resulted in reduced macrophage recruitment, impaired angiogenesis, and delayed wound healing. Together, these findings highlight the crucial role of TRPV1 signaling in monocyte migration and macrophage-related angiogenesis, both of which are crucial for facilitating healing of the TM. These results also open new opportunities for clinical interventions. Targeting TRPV1 signaling could enhance TM immunity, improve blood circulation, promote the repair of damaged TM, and ultimately prevent middle ear infections.

cell biology↗

bioRxiv2025

Star-Shaped Glatiramer Acetate Mitigates Pulmonary Dysfunction and Brain Neurodegeneration in a Murine Model of Cryptococcus-Associated IRIS

Cryptococcal-associated immune reconstitution inflammatory syndrome (C-IRIS) is a clinical worsening or new presentation of cryptococcal disease following the initiation of antiretroviral therapy. C-IRIS is primarily driven by an influx of pathological CD4+ T cells, which triggers a hyperinflammatory response. The murine model of C-IRIS is a way to study the disease in mice and understand how the immune system triggers life-threatening outcomes in patients. We previously developed a murine C-IRIS model and demonstrated that C-IRIS is triggered by pathological CD4+ T cells, particularly Th1 cells, in the brain, which triggers neurodegeneration and pulmonary dysfunction. Using this unique mouse model, we tested the therapeutic effect of a star-shaped glatiramer acetate (sGA), which is a more effective isomeric form than linear GA. Here, we observed that sGA suppresses Th1 differentiation in the lung tissues, reducing CD4+ T cell and Th1 cell count. It also reduced microglia populations in the brain. Together, these changes improved respiratory dysfunction caused by C-IRIS, lowered mortality rate, and reduced brain neurodegeneration. These findings suggest that sGA could be an effective therapeutic strategy for managing C-IRIS.

immunology↗

bioRxiv2024

Cryo-EM structures of engineered Shiga toxin-based immunogens capable of eliciting neutralizing antibodies with therapeutic potential against Hemolytic Uremic Syndrome

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is a serious disease that causes renal failure predominantly in children. Despite its significant impact, there are currently no licensed vaccines or effective therapies available. The B subunits of Shiga toxins 1 and 2 (Stx1B and Stx2B) are suitable targets for developing neutralizing antibodies, but their pentameric assembly is unstable when isolated from the whole toxin. Taking advantage of the oligomeric symmetry shared between Stx1B and Stx2B with the lumazine synthase from Brucella spp. (BLS), we have previously engineered the chimeric toxoids BLS-Stx1B and BLS-Stx2B as immunogens to generate therapeutic equine polyclonal antibodies. The resulting product (INM004) has successfully passed phases 1 and 2 clinical trials, and a phase 3 has been launched in Argentina and seven European countries. In this work, we present the cryo-EM structures of BLS-Stx1B and BLS-Stx2B, which confirm that these engineered immunogens effectively stabilize the StxB pentamers. Moreover, our results reveal that both chimeric constructs present high flexibility at their extremes, corresponding to motions of the StxBs with respect to the BLS core. Additionally, we present structural evidence of the interaction between the chimeras and polyclonal Fab (pFab) fragments derived from INM004, demonstrating that the elicited neutralizing antibodies block most of the interaction surface of the toxins with their cellular receptors. These findings further validate this promising antibody-based therapy for mitigating STEC-HUS and demonstrate that the BLS-Stx1B and BLS-Stx2B chimeras are potential candidates for developing a human vaccine.

immunology↗

bioRxiv2024

Molecular basis of the urate transporter URAT1 inhibition by gout drugs

Hyperuricemia is a condition when uric acid, a waste product of purine metabolism, accumulates in the blood1. Untreated hyperuricemia can lead to crystal formation of monosodium urate in the joints, causing a painful inflammatory disease known as gout. These conditions are associated with many other diseases and affect a significant and increasing proportion of the population2-4. The human urate transporter 1 (URAT1) is responsible for the reabsorption of [~]90% of uric acid in the kidneys back into the blood, making it a primary target for treating hyperuricemia and gout5. Despite decades of research and development, clinically available URAT1 inhibitors have limitations because the molecular basis of URAT1 inhibition by gout drugs remains unknown5. Here we present cryo-electron microscopy structures of URAT1 alone and in complex with three clinically relevant inhibitors: benzbromarone, lesinurad, and the novel compound TD-3. Together with functional experiments and molecular dynamics simulations, we reveal that these inhibitors bind selectively to URAT1 in inward-open states. Furthermore, we discover differences in the inhibitor dependent URAT1 conformations as well as interaction networks, which contribute to drug specificity. Our findings illuminate a general theme for URAT1 inhibition, paving the way for the design of next-generation URAT1 inhibitors in the treatment of gout and hyperuricemia.

biophysics↗

bioRxiv2024

ATP Citrate Lyase Supports Cardiac Function and NAD+/NADH Balance And Is Depressed in Human Heart Failure

BackgroundATP-citrate lyase (ACLY) converts citrate into acetyl-CoA and oxaloacetate in the cytosol. It plays a prominent role in lipogenesis and fat accumulation coupled to excess glucose, and its inhibition is approved for treating hyperlipidemia. In RNAseq analysis of human failing myocardium, we found ACLY gene expression is reduced; however the impact this might have on cardiac function and/or metabolism has not been previously studied. As new ACLY inhibitors are in development for cancer and other disorders, such understanding has added importance. MethodsCardiomyocytes, ex-vivo beating hearts, and in vivo hearts with ACLY inhibited by selective pharmacologic (BMS303141, ACLYi) or genetic suppression, were studied. Regulation of ACLY gene/protein expression, and effects of ACLYi on function, cytotoxicity, tricarboxylic acid (TCA)-cycle metabolism, and redox and NAD+/NADH balance were assessed. Mice with cardiac ACLY knockdown induced by AAV9-acly-shRNA or cardiomyocyte tamoxifen-inducible Acly knockdown were studied. ResultsAcly gene expression was reduced more in obese patients with heart failure and preserved EF (HFpEF) than HF with reduced EF. In vivo pressure-overload and in vitro hormonal stress increased ACLY protein expression, whereas it declined upon fatty-acid exposure. Acute ACLYi (1-hr) dose-dependently induced cytotoxicity in adult and neonatal cardiomyocytes, and caused substantial reduction of systolic and diastolic function in myocytes and ex-vivo beating hearts. In the latter, ATP/ADP ratio also fell and lactate increased. U13C-glucose tracing revealed an ACLY-dependent TCA-bypass circuit in myocytes, where citrate generated in mitochondria is transported to the cytosol, metabolized by ACLY and then converted to malate to re-enter mitochondria, bypassing several NADH-generating steps. ACLYi lowered NAD+/NADH ratio and restoring this balance ameliorated cardiomyocyte toxicity. Oxidative stress was undetected with ACLYi. Adult hearts following 8-weeks of reduced cardiac and/or cardiomyocyte ACLY downregulation exhibited ventricular dilation and reduced function that was prevented by NAD augmentation. Cardiac dysfunction from ACLY knockdown was worse in hearts subjected to sustained pressure-overload, supporting a role in stress responses. ConclusionsACLY supports normal cardiac function through maintenance of the NAD+/NADH balance and is upregulated by hemodynamic and hormonal stress, but depressed by lipid excess. ACLY levels are most reduced in human HFpEF with obesity potentially worsening cardio-metabolic reserve.

molecular biology↗

bioRxiv2024

The sensory shark: high-quality phenotypic, genomic and transcriptomic data for the small spotted catshark Scyliorhinus canicula reveal the molecular bases of sensory organ evolution in jawed vertebrates

Cartilaginous fishes (chimaeras and elasmobranchs -sharks, skates and rays) hold a key phylogenetic position to explore the origin and diversifications of jawed vertebrates. Here, we report and integrate reference genomic, transcriptomic and morphological data in the small-spotted catshark Scyliorhinus canicula to shed light on the evolution of sensory organs. We first characterise general aspects of the catshark genome, confirming the high conservation of genome organisation across cartilaginous fishes, and investigate population genomic signatures. Taking advantage of a dense sampling of transcriptomic data, we also identify gene signatures for all major organs, including chondrichthyan specializations, and evaluate expression diversifications between paralogs within major gene families involved in sensory functions. Finally, we combine these data with 3D synchrotron imaging and in situ gene expression analyses to explore chondrichthyan-specific traits and more general evolutionary trends of sensory systems. This approach brings to light, among others, novel markers of the ampullae of Lorenzini electro-sensory cells, a duplication hotspot for crystallin genes conserved in jawed vertebrates, and a new metazoan clade of the Transient-receptor potential (TRP) family. These resources and results, obtained in an experimentally tractable chondrichthyan model, open new avenues to integrate multiomics analyses for the study of elasmobranchs and jawed vertebrates.

evolutionary biology↗

bioRxiv2024

HIV-1 infection is associated with depletion of germinal center B cells and a decrease in IgA+ plasma cells in the GI tract

Gastrointestinal (GI) B cells and plasma cells (PCs) are critical to mucosal homeostasis and the host response to HIV-1 infection. Here, high resolution mapping of human B cells and PCs sampled from the colon and ileum during both viremic and suppressed HIV-1 infection identified a reduction in germinal center (GC) B cells and follicular dendritic cells (FDCs) during HIV-1 viremia. IgA+ PCs are the major cellular output of intestinal GCs and were significantly reduced during viremic HIV-1 infection. PC-associated transcriptional perturbations, including type I interferon signaling, persisted in antiretroviral therapy (ART)-treated individuals, suggesting ongoing disruption of the intestinal immune milieu during ART. GI humoral immune perturbations were associated with changes in the intestinal microbiome composition and systemic inflammation. These findings highlight a key immune defect in the GI mucosa due to HIV-1 viremia. One Sentence SummaryIntestinal germinal center B cell reduction in HIV-1 infection linked to reduced IgA+ plasma cells and systemic inflammation.

immunology↗

bioRxiv2024

Quinolinic acid links kidney injury to brain toxicity

Kidney dysfunction often leads to neurological impairment, yet the complex kidney-brain relationship remains elusive. We employed spatial and bulk metabolomics to investigate a mouse model of rapid kidney failure induced by mouse double minute 2 (Mdm2) conditional deletion in the kidney tubules to interrogate kidney and brain metabolism. Pathway enrichment analysis of focused plasma metabolomics panel pinpointed tryptophan metabolism as the most altered pathway with kidney failure. Spatial metabolomics showed toxic tryptophan metabolites in the kidneys and brains, revealing a novel connection between advanced kidney disease and accelerated kynurenine degradation. In particular, the excitotoxic metabolite quinolinic acid was localized in ependymal cells adjacent to the ventricle in the setting of kidney failure. These findings were associated with brain inflammation and cell death. A separate mouse model of acute kidney injury also had an increase in circulating toxic tryptophan metabolites along with altered brain inflammation. Patients with advanced CKD similarly demonstrated elevated plasma kynurenine metabolites and quinolinic acid was uniquely correlated with fatigue and reduced quality of life in humans. Overall, our study identifies the kynurenine pathway as a bridge between kidney decline, systemic inflammation, and brain toxicity, offering potential avenues for diagnosis and treatment of neurological issues in kidney disease.

molecular biology↗

bioRxiv2024

Enhanced stimulus-induced and stimulus-free gamma in open-eye meditators

Visual stimuli induce "narrowband" gamma oscillations (30-70 Hz) that are linked to attention/binding and attenuate with aging and neurodegeneration. In contrast, meditation increases power in a broad frequency range (>25 Hz). However, the effect of meditation on stimulus-induced gamma is unknown. We recorded EEG from meditators and controls performing open-eye meditation while gamma-inducing stimuli were presented before, during and after meditation. We found that stimulus-induced gamma, like stimulus-free gamma, was stronger in meditators. Interestingly, both gamma signatures co-existed during meditation but were unrelated and prominent in occipital and fronto-temporal regions, respectively. Further, power spectral density (PSD) slope, which becomes shallower with aging, was steeper for meditators. Meditation could boost inhibitory mechanisms leading to stronger gamma and steeper PSDs, potentially providing protection against aging and neurodegeneration. One line summaryStimulus-induced and stimulus-free gamma are stronger in open-eye meditators.

neuroscience↗

bioRxiv2024

Translating Ethiopian potato seed networks: Identifying strategic intervention points for managing bacterial wilt and other diseases

ContextInformal seed trade can exacerbate crop disease epidemics. Potato production across Ethiopia is threatened by the spread of seedborne pests and pathogens, particularly by bacterial wilt, caused by the Ralstonia solanacearum Species Complex (RSSC). The RSSC is commonly dispersed through informal trade of seed potato, with the potential to move long distances across Ethiopia and among trading countries. Efficient disease testing programs and formal seed systems can reduce the risk of disease expansion in a countrys potato cropping system. ObjectiveIn this study, we characterized networks of potato value chain actors. We also identified candidate locations for disease surveillance and management interventions for improved seed systems, and locations at high risk for bacterial wilt establishment. We propose strategies to reduce the spread of bacterial wilt via infected seed. MethodsWe surveyed seed potato stakeholders to characterize interaction networks of potato value chain actors with a special focus on stakeholders engaged in seed potato quality assurance. We collected data regarding Ethiopias potato seed systems and analyzed the risk of spread of RSSC and other pathogens across the country through expert knowledge elicitation. Network metrics were used to characterize the informal seed trade system across Ethiopia, simulating pathogen spread across a network through scenario analyses. We characterized potato exports and imports to identify the risk of bacterial wilt movement through Ethiopias formal trading partners and neighboring countries where bacterial wilt has not yet been reported. ResultsWare potato farmers and traders were reported to have weak communication with other stakeholders in the potato value chain. In network analyses and simulated epidemics, locations in Agew Awi, Gamo, Gofa, Kembata and Tembaro zones were identified as candidate priorities for national surveillance of pathogen invasion and expansion through management interventions and formal seed system development. Ethiopia has formal trade with Sudan, Southern Sudan, Russia, and other countries where bacterial wilt has not been reported. Ethiopia may be at risk of reintroduction of the RSSC from countries where it is present, like Kenya and India. SignificanceImproving seed systems to manage R. solanacearum and other seedborne pathogens is important for supporting food security and the livelihoods of smallholder farmers in Ethiopia. Implementing surveillance systems and management programs in locations like those identified in Agew Awi, Gamo, Gofa, Kembata, and Tembaro zones, and improving the communication between ware potato traders and other stakeholders, can help to strengthen informal trade of seed potato and mitigate bacterial wilt spread in infected seed.

ecology↗

bioRxiv2024

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↗

bioRxiv2024

Stimulus-induced gamma sources weaken but not shrink with healthy aging in human EEG

Aging alters brain structure and function, and studying such changes may help understand the neural basis underlying aging and devise interventions to detect deviations from healthy progression. Electroencephalogram (EEG) offers an effective way to study healthy aging owing to its high temporal resolution and affordability. Recent studies have shown that narrow- band stimulus-induced gamma oscillations (20-70 Hz) in EEG, induced with cartesian gratings in a fixation task paradigm, weaken with healthy aging and onset of Alzheimers Disease (AD) while remaining highly reproducible for a given subject, and thus hold promise as potential biomarkers. However, functional connectivity (FC) sometimes changes in a different way compared to sensor power with aging. This difference could be potentially addressed by studying how underlying gamma sources change with aging, since either a reduction in source power or a shrinkage of the sources (or both) could reduce the power in the sensors but may have different effects on other measures such as FC. We therefore reconstructed EEG gamma sources through a linear inverse method called exact Low-resolution Tomography Analysis (eLORETA) on a large (N=217) cohort of healthy elderly subjects (>50 years). We further characterized gamma distribution in cortical space as an exponential fall-off from a seed voxel with maximal gamma source power to delineate a reduction in magnitude versus shrinkage. We found significant reduction in magnitude but not shrinkage with healthy aging. Overall, our results shed light on changes in EEG gamma source distribution with healthy aging, which could provide clues about underlying neural mechanisms.

neuroscience↗

bioRxiv2023

Fluvoxamine maleate ameliorates Alzheimer disease pathology by mitigating amyloid-beta load and neuroinflammation in 5XFAD mice

BackgroundAlzheimer pathology (AD) is accompanied by the deposition of amyloid beta (A{beta}) and chronic neuroinflammation, where NLRP3 inflammasome is particularly involved. In this study, we found that the OCD drug fluvoxamine maleate (FXN) can potently ameliorate AD pathology in 5XFAD mice by autophagy-mediated clearance of A{beta} and inhibition of NLRP3 inflammasome. MethodsWe used mice primary astrocytes to establish the mechanism of action of FXN against NLRP3 inflammasome by using various techniques like ELISA, Western blotting, confocal microscopy, Immunofluorescence, etc. The validation of the anti-AD activity of FXN was done in transgenic 5XFAD mice after two months of treatment followed by behavior analysis and studying inflammatory and autophagy proteins along with immunohistochemistry analysis for A{beta} load in the hippocampi. ResultsOur data showed that FXN induces autophagy to inhibit NF-{kappa}B and NLRP3 inflammasome at a low concentration of 78 nM apart from directly inhibiting NLRP3 inflammasome in primary astrocytes. FXN activated the PRKAA2 pathway through CAMKK2 signaling, which led to the induction of autophagy in primary astrocytes. FXN inhibited the ATP-mediated NLRP3 inflammasome through autophagic degradation of NF-{kappa}B and thus caused the downregulation of pro-IL-1{beta} and NLRP3. The anti-NLRP3 inflammasome effect of FXN was reversed when autophagy was inhibited either by genetic knockdown of the PRKAA2 pathway or by bafilomycin A1. Furthermore, FXN treatment led to improved AD pathology in 5XFAD mice, which displayed a significant improvement in multiple behavior parameters like working memory and neuromuscular coordination and they behaved more like wild-type animals. We found that FXN improved behavior in 5XFAD mice by clearing the A{beta} deposits from the hippocampi along with a significant reduction in multiple inflammatory proteins, including NF-{kappa}B, GFAP, IBA1, IL-1{beta}, TNF-, and IL-6 associated with NF-{kappa}B and NLRP3 inflammasome in the brain. Moreover, these changes were accompanied by increased expression of autophagic proteins. ConclusionOur data suggest that to ameliorate AD pathology, FXN simultaneously targets two key pathological features of AD that is A{beta} deposits and neuroinflammation. Being an approved drug, FXN can be pushed as a potential drug candidate for human studies against AD.

neuroscience↗

bioRxiv2023

Extreme in Every Way: Exceedingly Low Genetic Diversity in Snow Leopards Due to Persistently Small Population Size

Snow leopards (Panthera uncia) serve as an umbrella species whose conservation benefits their high-elevation Asian habitat. Their numbers are believed to be in decline due to numerous Anthropogenic threats; however, their conservation is hindered by numerous knowledge gaps. They are the least studied genetically of all big cat species with more to learn regarding their population structure, historical population size, and current levels of genetic diversity. Here, we use whole-genome sequencing data for 41 snow leopards (37 newly sequenced) to offer new insights into these unresolved questions. Among our samples, we find evidence of a primary genetic divide between the northern and southern part of the range around the Dzungarian Basin, as previously identified, and a secondary divide south of Kyrgyzstan around the Taklamakan Desert. Most noteworthy, we find that snow leopards have the lowest genetic diversity of any big cat species, due to a persistently small population size (relative to other big cat species) throughout their evolutionary history rather than recent inbreeding. Without a large population size or ample standing genetic variation to help buffer them from any forthcoming Anthropogenic challenges, snow leopard persistence may be more tenuous than currently appreciated.

evolutionary biology↗

bioRxiv2023

Lack of Purple Acid Phosphatase SlPAP26b compromises the phosphorous starvation response in tomato independent of SlPHR1 and SlPHL1

The scarcity of soil phosphorus (P), an essential macronutrient, often limits plant growth and development. Enhanced secretion of intracellular and secretory acid phosphatases is essential to maintain cellular inorganic P (Pi) homeostasis in plants. Herein, using transcriptomics and proteomics approach, we observed upregulation of several purple acid phosphatases (PAPs), including SlPAP1, SlPAP10b, SlPAP12, SlPAP15, SlPAP17b, SlPAP26a, and SlPAP26b in Pi-deficient tomato seedlings. Higher transcript levels of SlPAP17b and SlPAP26b in the older senescing leaves than the younger leaves indicated active involvement of these PAPs in Pi remobilization. Subsequent detailed characterization of SlPAP17b, SlPAP26a, and SlPAP26b revealed a prominent role of SlPAP26b in Pi homeostasis. Silencing of SlPAP26b led to an exacerbated P starvation response as these plants exhibited smaller shoots, lower soluble Pi, total P levels, and higher sucrose than their EV controls under Pi deprivation. SlPAP26b-silenced plants also showed misregulation of P starvation inducible genes such as phosphate transporters and glycerolipid remodellers, even under Pi-sufficient conditions. Whereas SlPAP26b levels were induced by external sucrose, its expression was found to be independent of the Myb class master regulators of P starvation response, SlPHR1 and SlPHL1. Altogether, this study identifies a prominent role of SlPAP26b in the Pi compensation network in tomato seedlings.

plant biology↗

bioRxiv2023

Essential oil terpenes may inhibit steroidogenic cytochrome P450 activities.

Endocrine-disrupting chemicals (EDCs) may impact the development of Prostate Cancer (PCa) by altering the steroid metabolism. Although their exact mechanism of action in controlling tumor growth is not known, EDCs may inhibit steroidogenic enzymes such as Cytochrome P450 c17 (CYP17A1) or aromatase (CYP19A1) involved in the production of Androgens or Estrogens. High levels of circulating androgens are linked to PCa in men and Polycystic Ovary Syndrome (PCOS) in women. Essential Oils or their metabolites (EOs) like lavender oil and tea tree oil have been reported to act as potential EDCs and contribute towards sex steroid imbalance in case of prepubertal gynecomastia in boys and premature thelarche in girls due to the regular exposure to lavender-based fragrances among Hispanic population. We screened a range of EO components to determine their effects on CYP17A1 and CYP19A1 Computational docking was performed to predict the binding of EOs with CYP17A1 and CYP19A1 and functional assays were done using the radiolabeled substrates or Liquid Chromatography high-resolution Mass Spectrometry and cell viability assays were carried out in LNCaP cells. Many of the tested compounds bind close to the active site of CYP17A1, and (+)-Cedrol had the best binding with CYP17A1 and CYP19A1. Eucalyptol, Dihydro-{beta}-Ionone & (-)--pinene showed 20% to 40% inhibition of dehydroepiandrosterone production; and some compounds also effected CYP19A1. Extensive use of these EOs in various beauty and hygiene products is common, but only a limited knowledge about their potential detrimental side effects exists. Our results suggest that prolonged exposure to some of these essential oils may result in steroid imbalances. On the other hand, due to their effect on lowering androgen output, ability to bind at the active site of steroidogenic cytochrome P450s, these compounds may provide design ideas for the novel compounds against hyperandrogenic disorders such as PCa and PCOS.

pharmacology and toxicology↗

bioRxiv2023

Bacterial pore-forming toxin pneumolysin drives pathogenicity through shed toxin-loaded host extracellular vesicles

Streptococcus pneumoniae is a global priority respiratory pathogen that kills over a million people annually and produces the pore-forming cytotoxin, pneumolysin (PLY). Host cells expel membrane assembled toxin by shedding microvesicles, but the composition and pathophysiological sequelae of the toxin-induced host extracellular vesicles (EVs) are unknown. Here, we found that EVs shed from PLY-challenged monocytes (PLY-EVs) harbor membrane-bound toxin that induced cytotoxicity upon fusion with recipient cells. EVs from human monocytes challenged with recombinant PLY as well as PLY-expressing pneumococcal strains, but not the isogenic PLY mutant, primed dendritic cells and evoked higher pro-inflammatory cytokines upon infection. Proteomic analysis revealed that PLY-EVs are enriched for key antimicrobial and inflammatory host proteins such as IFI16, NLRC4, PTX3 and MMP9. In vivo, zebrafish and mice administered with PLY-EVs showed mortality, pericardial edema, tissue damage and inflammation. Our findings show that host EVs bearing the cytotoxin PLY constitute a previously unexplored mechanism of pneumococcal pathogenesis.

microbiology↗

bioRxiv2023

Ketogenic diet alters microglial morphology and changes the hippocampal lipidomic profile distinctively in stress susceptible versus resistant male mice upon repeated social defeat

Psychological stress confers an increased risk for several diseases including psychiatric conditions. The susceptibility to psychological stress is modulated by various factors, many of them being modifiable lifestyle choices. The ketogenic diet (KD) has emerged as a dietary regime that offers positive outcomes on mood and health status. Psychological stress and elevated inflammation are common features of neuropsychiatric disorders such as certain types of major depressive disorder. KD has been attributed anti-inflammatory properties that could underlie its beneficial consequences on the brain and behavior. Microglia are the main drivers of inflammation in the central nervous system. They are known to respond to both dietary changes and psychological stress, notably by modifying their production of cytokines and relationships among the brain parenchyma. To assess the interactions between KD and the stress response, including effects on microglia, we examined adult male mice on control diet (CD) versus KD that underwent 10 days of repeated social defeat (RSD) or remained non-stressed (controls; CTRLs). Through a social interaction test, stressed mice were classified as susceptible (SUS) or resistant (RES) to RSD. The mouse population fed a KD tended to have a higher proportion of individuals classified as RES following RSD. Microglial morphology and ultrastructure were then analyzed in the ventral hippocampus CA1, a brain region known to present structural alterations as a response to psychological stress. Distinct changes in microglial soma and arborization linked to the KD, SUS and RES phenotypes were revealed. Ultrastructural analysis by electron microscopy showed a clear reduction of cellular stress markers in microglia from KD fed animals. Furthermore, ultrastructural analysis showed that microglial contacts with synaptic elements were reduced in the SUS compared to the RES and CTRL groups. Hippocampal lipidomic analyses lastly identified a distinct lipid profile in SUS animals compared to CTRLs. These key differences, combined with the distinct microglial responses to diet and stress, indicate that unique metabolic changes may underlie the stress susceptibility phenotypes. Altogether, our results reveal novel mechanisms by which a KD might improve the resistance to psychological stress. HighlightsO_LIKetogenic diet tends to promote resistance to psychological stress C_LIO_LIHippocampal microglia show morphological adaptations to stress and diet C_LIO_LIMicroglia of stress-susceptible mice make less synaptic contacts C_LIO_LIMicroglia of ketogenic diet-fed mice show less signs of cellular stress C_LIO_LILipids are differentially regulated in the hippocampi of susceptible mice C_LI

neuroscience↗