Score: 9.0, Published: 2024-02-12
DOI: 10.1101/2024.02.10.579746
Nanomaterials emerged as boundless resource of innovation, but their shape and biopersistence related to respiratory toxicology raise longstanding concerns. The development of predictive safety tests for inhaled nanomaterials, however, is hampered by limited understanding of cell type-specific responses. To advance this knowledge, we used single-cell RNA-sequencing to longitudinally analyze cellular perturbations in mice, caused by three carbonaceous nanomaterials of different shape and toxicity upon pulmonary delivery. Focusing on nanomaterial-specific dynamics of lung inflammation, we found persistent depletion of alveolar macrophages by fiber-shaped nanotubes. While only little involvement was observed for alveolar macrophages during the initiation phase, they emerged, together with infiltrating monocyte-derived macrophages, as decisive factors in shifting inflammation towards resolution for spherical nanomaterials, or chronic inflammation for fibers. Fibroblasts, central for fibrosis, sensed macrophage and epithelial signals and emerged as orchestrators of nanomaterial-induced inflammation. Thus, the mode of actions identified in this study will significantly inspire the precision of future in vitro testing. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/579746v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1efdae6org.highwire.dtl.DTLVardef@c6652org.highwire.dtl.DTLVardef@11c5d5org.highwire.dtl.DTLVardef@d33fb5_HPS_FORMAT_FIGEXP M_FIG C_FIG
Score: 1.5, Published: 2024-02-14
DOI: 10.1101/2024.02.12.579996
RationalePreclinical models of electronic nicotine delivery system (ENDS; "e-cigarette") use have been rare, so there is an urgent need to develop experimental approaches to evaluate their effects. ObjectiveTo contrast the impact of inhaled nicotine across sex. MethodsMale and female Wistar rats were exposed to vapor from a propylene glycol vehicle (PG), nicotine (NIC; 1-30 mg/mL in PG), or were injected with NIC (0.1-0.8 mg/kg, s.c.), and then assessed for changes in temperature and activity. The antagonist mecamylamine (2 mg/kg) was administered prior to NIC to verify pharmacological specificity. Plasma levels of nicotine and cotinine were determined after inhalation and injection. ResultsActivity increased in females for [~]60 minutes after nicotine inhalation, and this was blocked by mecamylamine. A similar magnitude of hyperlocomotion was observed after s.c. administration. Body temperature was reduced after nicotine inhalation by female rats but mecamylamine increased this hypothermia. Increased locomotor activity was observed in male rats if inhalation was extended to 40 minutes or when multiple inhalation epochs were used per session. The temperature of male rats was not altered by nicotine. Plasma nicotine concentrations were slightly lower in male rats than in female rats after 30-minute nicotine vapor inhalation and slightly higher after nicotine injection (1.0 mg/kg, s.c.). ConclusionsNicotine inhalation increases locomotor activity in male and female rats to a similar or greater extent than by subcutaneous injection. Sex differences were observed, which may be related to lower nicotine plasma levels, lower baseline activity and/or a higher vehicle response in males.
Score: 1.2, Published: 2024-02-10
DOI: 10.1101/2024.02.07.579333
With a long evolutionary history and a need to adapt to a changing environment, cyanobacteria in freshwater systems use specialized metabolites for communication, defense, and physiological processes. However, the role that these metabolites play in differentiating species, maintaining microbial communities, and generating niche persistence and expansion is poorly understood. Furthermore, many cyanobacterial specialized metabolites and toxins present significant human health concerns due to their liver toxicity and their potential impact to drinking water. Gaps in knowledge exist with respect to changes in species diversity and toxin production during a cyanobacterial bloom (cyanoHAB) event; addressing these gaps will improve understanding of impacts to public and ecological health. In the current project, we utilized a multi-omics strategy (DNA metabarcoding and metabolomics) to determine the cyanobacterial community composition, toxin profile, and the specialized metabolite pool at three freshwater lakes in Providence, RI during summer-fall cyanoHABs. Species diversity decreased at all study sites over the course of the bloom event, and toxin production reached a maximum at the midpoint of the event. Additionally, LC-MS/MS-based molecular networking identified new toxin congeners. This work provokes intriguing questions with respect to the use of allelopathy by organisms in these systems and the presence of emerging toxic compounds that can impact public health. SYNOPSISThis study reports on cyanobacterial community succession and toxin dynamics during cyanobacterial bloom events. Results show relationships and temporal dynamics that are relevant to public health.
Score: 7.2, Published: 2024-01-28
DOI: 10.1101/2023.04.12.536537
The sodium (Na+) leak channel (NALCN) is a member of the four-domain voltage-gated cation channel family that includes the prototypical voltage-gated sodium and calcium channels (NaVs and CaVs, respectively). Unlike NaVs and CaVs, which have four lateral fenestrations that serve as routes for lipophilic compounds to enter the central cavity to modulate channel function, NALCN has bulky residues (W311, L588, M1145 and Y1436) that block these openings. Structural data suggest that oc-cluded lateral fenestrations underlie the pharmacological resistance of NALCN to lipophilic compounds, but functional evidence is lacking. To test this hypothesis, we unplugged the fenestrations of NALCN by substituting the four aforementioned resi-dues with alanine (AAAA) and compared the effects of NaV, CaV and NALCN block-ers on both wild-type (WT) and AAAA channels. Most compounds behaved in a simi-lar manner on both channels, but phenytoin and 2-aminoethoxydiphenyl borate (2-APB) elicited additional, distinct responses on AAAA channels. Further experiments using single alanine mutants revealed that phenytoin and 2-APB enter the inner cav-ity through distinct fenestrations, implying structural specificity to their modes of ac-cess. Using a combination of computational and functional approaches, we identified amino acid residues critical for 2-APB activity, supporting the existence of drug bind-ing site(s) within the pore region. Intrigued by the activity of 2-APB and its ana-logues, we tested additional compounds containing the diphenylmethane/amine moiety on WT channels. We identified compounds from existing clinically used drugs that exhibited diverse activity, thus expanding the pharmacological toolbox for NALCN. While the low potencies of active compounds reiterate the resistance of NALCN to pharmacological targeting, our findings lay the foundation for rational drug design to develop NALCN modulators with refined properties. Significance statementThe sodium leak channel (NALCN) is essential for survival: mutations cause life-threatening developmental disorders in humans. However, no treatment is currently available due to the resistance of NALCN to pharmacological targeting. One likely reason is that the lateral fenestrations, a common route for clinically used drugs to enter and block related ion channels, are occluded in NALCN. Using a combination of computational and functional approaches, we unplugged the fenestrations of NALCN which led us to the first molecularly defined drug binding site within the pore region. Besides that, we also identified additional NALCN modulators from existing clinically used therapeutics, thus expanding the pharmacological toolbox for this leak channel.