Biology subjects

Lamb, T.

Publications and source records attributed to Lamb, T..

7 recordsLinked to original sources

bioRxiv2026

Brain microvascular endothelial cell dysfunction during Plasmodium infection does not result from astrocyte-derived wingless-related integration site (Wnt)7a deficiency

Breakdown of the blood brain barrier is a key event leading to vasogenic edema that underpins pediatric cerebral malaria. Brain microvascular endothelial cells (BMECs) downregulate junction proteins in response to Plasmodium-infected red blood cells (iRBCs). Very little is known about how glial cell activation in Plasmodium infection dysregulates astrocyte-derived steady state signals that control BMEC junction expression. Astrocytes from mice infected with Plasmodium berghei ANKA (PbA) exhibit transcriptional changes dominated by interferon signaling pathways. Downregulation of wingless-related integration site (Wnt)7a transcription in astrocytes correlated with transcriptional changes in BMECs indicative of reduced {beta}-catenin activity. Incubation of the human astrocyte-like glioma cell-line CCF-STTG1 with interferon-{gamma} (IFN-{gamma}) decreased the general production of Wnt7a in response to P. falciparum iRBCs. However astrocyte conditioned medium incubated with IFN-{gamma} strengthened the barrier function in vitro when added onto monolayers the human cerebral microvascular endothelial cell line D3 (hCMEC/D3). This data suggests that the response of astrocytes during Plasmodium infection may be protective but unable to overcome dysfunctional responses of BMECs to Plasmodium iRBCs. To test this hypothesis we overexpressed Wnt7a in the brain tissue of mice using an AAV construct but this did not impart increased survival to the neurological effects of PbA infection. Therefore astrocyte responses during Plasmodium infection may not underlie the downregulation of junction proteins on BMECs leading to edema in cerebral malaria.

immunology↗

bioRxiv2025

Single-cell transcriptomics identifies a dampened neutrophil function and accentuated T-cell cytotoxicity in tobacco flavored e-cigarette exposed mouse lungs

E-cigarettes (e-cigs) are a public health concern for young adults due to their rising popularity despite evidence of harmful effects. Yet an extensive study defining the cell-specific immune changes upon exposure to flavored e-cigs remains elusive. To determine the immunological lung landscape upon acute nose-only exposure of C57BL/6J to flavored e-cig aerosols, we performed single-cell RNA sequencing (scRNA seq). Analyses of the levels of metals in the e-cig aerosol generated daily during exposure revealed a flavor-dependent variation in the day-to-day leaching of the levels of metals like Ni, Cu, K and Zn, among others. scRNA profiles of 71,725 cells generated from control and treatment groups (n=2/sex/group) found maximum dysregulation of (a) myeloid cell function in menthol (324 differentially enriched genes (DEG)) and tobacco (553 DEGs) -flavor exposed and (b) lymphoid cell function in fruit (112 DEGs)-flavored e-cig aerosol exposed mouse lungs as compared to air. Flow cytometry analyses identified marked increase in the neutrophil percentage and a decrease in the eosinophil count in menthol and tobacco-flavored e-cig aerosol exposed mouse lungs which corroborated with our scRNA seq data. We further found an: (a) increase in CD8+ T cell percentages, (b) upregulation of inflammatory genes like Stat4, Il1bos, Il1b, Il1ra and Cxcl3 and (c) enrichment of terms like T-helper cell 1cytokine function and NK cell degranulation in the lungs of e-cig aerosol exposed mouse when compared to control. Interestingly, the increase in the level of immature neutrophils characterized by Ly6G deficiency and reduction in the S100A8 (marker for neutrophil activation) using immunofluorescence in tobacco-flavored e-cig aerosol exposed mouse lung sections point towards a possible shift in the neutrophil dynamics upon exposure to e-cigs. Overall, this study identifies flavor dependent changes in myeloid and lymphoid-cell mediated responses in the mouse lungs exposed to acute nose-only e-cig aerosols and provides a resource to influence future research in select /specific cell types to understand the immunological implications of long-term use of e-cigs.

pharmacology and toxicology↗

bioRxiv2022

Nose-only Exposure to Cherry and Tobacco Flavored E-cigarettes Induced Lung Inflammation in Mice in a Sex-dependent Manner

Flavoring chemicals utilized in electronic nicotine delivery systems (ENDS) have been shown to result in an increase in cellular inflammation, meanwhile, the effects of fruit and tobacco flavors on lung inflammation by nose-only exposures to mice are relatively unknown. We hypothesized that C57BL/6J mice exposed to flavored e-cigarettes would result in an increase in lung inflammation. C57BL/6J mice were exposed to air, propylene glycol/vegetable glycerin (PG/VG), and e-liquids "Apple", "Cherry", "Strawberry", "Wintergreen", and "Smooth & Mild Tobacco", for one hour per day for a three day exposure. Quantification of flavoring chemicals was measured by proton nuclear magnetic resonance spectroscopy (1H NMR), differential cell counts by flow cytometry, pro-inflammatory cytokines/chemokines by ELISA, and matrix metalloproteinase levels by western blot. Exposure to PG/VG, Apple, and Smooth & Mild Tobacco resulted in an increase in neutrophil cell count in lung bronchoalveolar lavage fluid (BALF). Strawberry exposure increased KC levels in BALF while in lung homogenate KC levels were increased in PG/VG, Cherry, and Smooth & Mild Tobacco exposure. Exposure to PG/VG and Cherry increased IL-6 levels and in all exposed mice there was a male-specific decrease in MCP-1 levels in lung homogenate. Mice exposed to PG/VG, Apple, Cherry, and Wintergreen resulted in an increase in MMP2 levels. Our results indicate that female mice exposed to cherry flavored e-liquids and male mice exposed to tobacco flavored e-liquids resulted in an increase in inflammation, while exposure to mint flavored e-liquids resulted in a decrease in inflammatory cytokine and an increase in tissue repair proteins. This study revealed that flavored-based e-cigarette exposure elicited sex-specific alterations in lung inflammation, with cherry flavors/benzaldehyde eliciting female-specific increases in inflammation. This highlights the toxicity of flavored chemicals and the further need for regulation of flavoring chemicals.

pharmacology and toxicology↗

bioRxiv2020

Pulmonary toxicity and inflammatory response of e-cigarettes containing medium-chain triglyceride oil and vitamin E acetate: Implications in the pathogenesis of EVALI but independent of SARS-COV-2 COVID-19 related proteins

Recently, there has been an outbreak associated with the use of e-cigarette or vaping products, associated lung injury (EVALI). The primary components of vaping products, vitamin E acetate (VEA) and medium-chain triglycerides (MCT) may be responsible for acute lung toxicity. Currently, little information is available on the physiological and biological effects of exposure to these products. We hypothesized that these e-cig cartridges and their constituents (VEA and MCT) induce pulmonary toxicity, mediated by oxidative damage and inflammatory responses, leading to acute lung injury. We studied the potential mechanisms of cartridge aerosol induced inflammatory response by evaluating the generation of reactive oxygen species by MCT, VEA, and cartridges, and their effects on the inflammatory state of pulmonary epithelium and immune cells both in vitro and in vivo. Cells exposed to these aerosols generated reactive oxygen species, caused cytotoxicity, induced epithelial barrier dysfunction, and elicited an inflammatory response. Using a murine model, the parameters of acute toxicity to aerosol inhalation were assessed. Infiltration of neutrophils and lymphocytes was accompanied by significant increases in IL-6, eotaxin, and G-CSF in the bronchoalveolar lavage fluid (BALF). In mouse plasma, eicosanoid inflammatory mediators, leukotrienes, were significantly increased. Plasma from e-cig users also showed increased levels of hydroxyeicosatetraenoic acid (HETEs) and various eicosanoids. Exposure to e-cig cartridge aerosols showed the most significant effects and toxicity compared to MCT and VEA. In addition, we determined at SARS-COV-2 related proteins and found no impact associated with aerosol exposures from these tested cartridges. Overall, this study demonstrates acute exposure to specific e-cig cartridges induces in vitro cytotoxicity, barrier dysfunction, and inflammation and in vivo mouse exposure induces acute inflammation with elevated pro-inflammatory markers in the pathogenesis of EVALI.Competing Interest StatementThe authors have declared no competing interest.View Full Text

pharmacology and toxicology↗

bioRxiv2020

A Bayesian phase 2 model based adaptive design to optimise antivenom dosing: application to a dose-finding trial for a novel Russell's viper antivenom in Myanmar

For most antivenoms there is little information from clinical studies to infer the relationship between dose and efficacy or dose and toxicity. Antivenom dose-finding studies usually recruit too few patients (e.g. less than 20) relative to clinically significant event rates (e.g. 5%). Model based adaptive dose-finding studies make efficient use of accrued patient data by using information across dosing levels, and converge rapidly to the contextually defined optimal dose. Adequate sample sizes for adaptive dose-finding trials can be determined by simulation studies. We propose a model based, Bayesian phase 2 type, adaptive clinical trial design for the characterisation of optimal initial antivenom doses in contexts where both efficacy and toxicity are measured as binary endpoints. This design is illustrated in the context of dose-finding for Daboia siamensis (Eastern Russells viper) envenoming in Myanmar. The design formalises the optimal initial dose of antivenom as the dose closest to that giving a pre-specified desired efficacy, but resulting in less than a pre-specified maximum toxicity. For Russells viper efficacy is defined as the restoration of blood coagulability within six hours, and toxicity is defined as anaphylaxis. Comprehensive simulation studies compared the expected behaviour of the model based design to a simpler rule based design (a modified 3+3 design). The model based design can identify the optimal dose after fewer patients than the rule based design. Open source code for the simulations can be used to calculate sample sizes under a priori beliefs of efficacy and toxicity. Antivenom dose-finding trials would benefit from using standard model based adaptive designs. Dose-finding trials where rare events (e.g. 5% occurrence) are of clinical importance necessitate larger sample sizes than current practice. We will apply the model based design to determine a safe and efficacious dose for a novel lyophilised antivenom to treat Daboia siamensis envenoming in Myanmar. Author summarySnakebite envenoming is one of the most neglected tropical diseases relative to its mortality and morbidity. Antivenoms are the only known effective treatment for snake-bite envenoming but are frequently responsible for high rates of adverse reactions. Clinical development of antivenoms rarely follows the iterative phases of clinical development applied to other drugs. Dosing is typically based on pre-clinical testing. Here we propose a Bayesian model based adaptive design for clinical trials aiming to determine the optimal dose of antivenom needed. Optimality is defined using safety and efficacy thresholds contextual to the study. This design can be applied to all antivenoms which have binary efficacy and toxicity endpoints. Our design formally specifies a desired efficacy and a maximum tolerated toxicity. We use simulation studies to characterise the sample size necessary to determine the optimal dose in different scenarios. The simulation studies highlight the advantages of a model based design over simpler rule based alternatives. We intend to use this design to determine an effective and safe dose of the new lyophilised viper antivenom currently in use to treat Russells viper envenoming in Myanmar.

pharmacology and toxicology↗

bioRxiv2018

Generation of human neural retina transcriptome atlas by single cell RNA sequencing

The retina is a highly specialized neural tissue that senses light and initiates image processing. Although the functional organisation of specific cells within the retina has been well-studied, the molecular profile of many cell types remains unclear in humans. To comprehensively profile cell types in the human retina, we performed single cell RNA-sequencing on 20,009 cells obtained post-mortem from three donors and compiled a reference transcriptome atlas. Using unsupervised clustering analysis, we identified 18 transcriptionally distinct clusters representing all known retinal cells: rod photoreceptors, cone photoreceptors, Muller glia cells, bipolar cells, amacrine cells, retinal ganglion cells, horizontal cells, retinal astrocytes and microglia. Notably, our data captured molecular profiles for healthy and early degenerating rod photoreceptors, and revealed a novel role of MALAT1 in putative rod degeneration. We also demonstrated the use of this retina transcriptome atlas to benchmark pluripotent stem cell-derived cone photoreceptors and an adult Muller glia cell line. This work provides an important reference with unprecedented insights into the transcriptional landscape of human retinal cells, which is fundamental to our understanding of retinal biology and disease.

systems biology↗

bioRxiv2018

Unraveling rice tolerance mechanisms against Schizotetranychus oryzae mite infestation

Infestation of Schizotetranychus oryzae (Acari: Tetranychidae) causes great losses in rice productivity. Infestation in Puita INTA-CL cultivar reduced the number of seeds/plant, percentage of full seeds, 1,000 seeds weight, and seed length, whereas infestation in IRGA423 increased 1,000 seeds weight and seed length. Reduction in seed weight/plant caused by infestation was higher in Puita INTA-CL than IRGA423. Thus, Puita INTA-CL was established as susceptible, and IRGA423 as tolerant to S. oryzae infestation. Photosynthetic parameters were less affected by infestation in IRGA423 than in Puita INTA-CL. Infestation also caused accumulation of H2O2, decreased cell membrane integrity and accelerated senescence in leaves of Puita INTA-CL, while leaves of IRGA423 presented higher levels of phenolics compounds. Using proteomic analysis, we identified proteins related to plant defense, such as jasmonate synthesis, and related to other mechanisms of tolerance such as oxidative stress, photosynthesis, and DNA structure maintenance, more abundant in IRGA423 after seven days of infestation. We detected higher levels of silicon (as amorphous silica cells) in leaves of infested IRGA423 plants compared to Puita INTA-CL, an element previously linked to plant defense. Our data shows that IRGA423 presents tolerance to S. oryzae infestation, and that multiple mechanisms might be employed by this cultivar.\n\nHighlightThis is the first report evaluating the defense responses (tolerance and susceptiblity) of two contrasting rice cultivars to Schizotetranychus oryzae mite infestation.

plant biology↗