👤 Thomas A Leonard

Air pollution particles exacerbate allergic asthma and can enhance inflammatory responses to allergen exposure, but the cellular mechanisms involved remain incompletely defined. We examined how diesel exhaust particles (DEP) enhance house-dust-mite (HDM) inflammatory responses within the lung and characterised potential mechanisms that may contribute to enhanced type 2 (T2) inflammatory responses. In mice subjected to repeated intranasal exposures, DEP alone had modest effects, whereas DEP + HDM markedly increased type-2 inflammatory indicators (Serum IgE; Airway Il13, Il4 & Tslp) and eosinophilia alongside expansion of Th2 cells. Bulk transcriptomics showed far stronger differential expression in luminal airway cells than tissue, with a DEP + HDM-specific signature enriched for mast cells, alternatively activated macrophages (AAM), and B-cells in the lumen. Combined single-cell proteomic and transcriptomic profiling identified an expanded Cd11c⁺, SiglecF⁻, Apoe⁺, Gpnmb⁺ monocyte-derived macrophage subset (RM.Gp2), which showed increased type 2 chemokines Ccl8 and Ccl24 with DEP + HDM compared to HDM alone. Trajectory analysis placed RM.Gp2 downstream of Ccr2⁺ monocyte derived population, and protein/mRNA data supported a Ccl2-Ccr2-dependent influx that enlarges the RM.Gp2 pool. High-content imaging confirmed increased RM.Mo and RM.Gp2 numbers and higher total luminal Ccl8/Ccl24. F4/80⁺ luminal airway macrophages isolated from DEP pre-treated mice, demonstrated enhanced upregulation of Ccl8 and Ccl24 mRNA in response to ex vivo Il-4/Il-13 treatment, compared to macrophages isolated from control mice. Examination of an additional particle type (CeO Our data suggests that pollutant particles such as DEP may contribute to enhanced HDM induced type 2 inflammation by expanding Ccr2-dependent monocyte-derived macrophages into the airway lumen and licensing a Th2-cytokine-responsive chemokine programme (Ccl8- Ccr8 to recruit Th2 cells; Ccl24-Ccr3 to recruit eosinophils). These findings identify luminal recruited macrophages as important targets in allergic inflammation within the lung, providing insight into potential mechanisms from which exposure and disease mitigation strategies may be developed. Show less

Recreational sedentary screen time (rSST) is the most prevalent form of discretionary sedentary behavior and is strongly linked to poor health outcomes. However, the relationship between time spent in rSST and other 24-h behaviors is not well understood. The purpose of this study was to examine between- and within-day associations between rSST and other 24-h behaviors that include other non-rSST sedentary time (other-SED), standing (STAND), light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and total sleep (SLEEP). Baseline data from participants randomized to the StandUPTV study, an intervention aimed to reduce rSST in adults, were included. All 24-h behaviors were assessed continuously for 7-days. The activPAL device was used to assess rSST, other-SED, STAND, LPA, and MPVA; SLEEP was assessed using a GENEactiv accelerometer. rSST was collected using Wi-Fi plugs to capture TV time and tablet app usage. A multilevel modelling approach was used to assess bidirectional associations between rSST (total, daytime, evening) and 24-h behaviors at the between-person (across persons) and within-person (across days) levels, adjusting for age, sex, chronotype, education level, and week versus weekend day. The results were scaled hourly for interpretation. On average, 8.0 ± 1.6 days of continuous daily 24-h behavior data were included from 94 participants (age [M ± SD: 42.3 ± 11.5] years; 82% female; 78% White; BMI [M ± SD: 29.8 ± 7.8] kg/m This is the first known analysis of the bidirectional relationship between rSST and 24-h behaviors. The negative association between rSST and other-SED suggests that rSST may displace rather than contribute to more cumulative sedentary time. These findings advocate that contexts of sedentary behavior should be considered as distinct behavioral targets in intervention development. Future interventions targeting rSST reduction should also include strategies to reduce total sedentary time. NCT04464993. Show less

Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK) are a class of fusion protein-driven, poor prognosis leukemias. Leukemias harboring FGFR1 fusions have previously been referred to as 8p11.2 myeloproliferative syndrome (EMS) or stem cell leukemia/lymphoma (SCLL) and are currently referred to as Myeloid/lymphoid neoplasms with FGFR1 rearrangement based on the most recent WHO classification system. To identify new therapeutic options for MLN-TK patients, we evaluated clinical and Show less

Invading species along with increased anthropogenization may lead to hybridization events between wild species and closely related domesticates. As a consequence, wild species may carry introgressed alleles from domestic species, which is generally assumed to yield adverse effects in wild populations. The opposite evolutionary consequence, adaptive introgression, where introgressed genes are positively selected in the wild species, is possible but has rarely been documented. Grey wolves (Canis lupus) are widely distributed across the Holarctic and frequently coexist with their close relative, the domestic dog (C. familiaris). Despite ample opportunity, hybridization rarely occurs in most populations. Here we studied the geographically isolated grey wolves of the Iberian Peninsula, who have coexisted with a large population of loosely controlled dogs for thousands of years in a human-modified landscape. We assessed the extent and impact of dog introgression on the current Iberian grey wolf population by analysing 150 whole genomes of Iberian and other Eurasian grey wolves as well as dogs originating from across Europe and western Siberia. We identified almost no recent introgression and a small (< 5%) overall ancient dog ancestry. Using a combination of single scan statistics and ancestry enrichment estimates, we identified positive selection on six genes (DAPP1, NSMCE4A, MPPED2, PCDH9, MBTPS1, and CDH13) for which wild Iberian wolves carry alleles introgressed from dogs. The genes with introgressed and positively selected alleles include functions in immune response and brain functions, which may explain some of the unique behavioural phenotypes in Iberian wolves such as their reduced dispersal compared to other wolf populations. Show less

Corpus callosum malformations are associated with a broad range of neurodevelopmental diseases. We report that de novo mutations in MAST1 cause mega-corpus-callosum syndrome with cerebellar hypoplasia and cortical malformations (MCC-CH-CM) in the absence of megalencephaly. We show that MAST1 is a microtubule-associated protein that is predominantly expressed in post-mitotic neurons and is present in both dendritic and axonal compartments. We further show that Mast1 null animals are phenotypically normal, whereas the deletion of a single amino acid (L278del) recapitulates the distinct neurological phenotype observed in patients. In animals harboring Mast1 microdeletions, we find that the PI3K/AKT3/mTOR pathway is unperturbed, whereas Mast2 and Mast3 levels are diminished, indicative of a dominant-negative mode of action. Finally, we report that de novo MAST1 substitutions are present in patients with autism and microcephaly, raising the prospect that mutations in this gene give rise to a spectrum of neurodevelopmental diseases. Show less

T lymphocytes play a central role in controlling adaptive immune responses. IL-2 critically regulates both T cell growth and death and is involved in maintaining peripheral tolerance, but the molecules involved in these and other IL-2 actions are only partially known. We now provide a comprehensive compendium of the genes expressed in T cells and of those regulated by IL-2 based on a combination of DNA microarrays and serial analysis of gene expression (SAGE). The newly identified IL-2 target genes include many genes previously linked to apoptosis in other cellular systems that may contribute to IL-2-dependent survival functions. We also studied the mRNA expression of known regulators of signaling pathways for their induction in response to IL-2 in order to identify potential novel positive and/or negative feedback regulators of IL-2 signaling. We show that IL-2 regulates only a limited number of these genes. These include suppressors of cytokine signaling (SOCS) 1, SOCS2, dual-specificity phosphatase (DUSP) 5, DUSP6 and non-receptor type phosphatase-7 (PTPN7). Additionally, we provide evidence that many genes expressed in T cells locate in chromosomal clusters, and that select IL-2-regulated genes are located in at least two clusters, one at 5q31, a known cytokine gene cluster, and the other at 6p21.3, a region that contains genes encoding the tumor necrosis factor (TNF) superfamily members TNF, LT-alpha and LT-beta. Show less

Rapid glutamatergic synaptic transmission is mediated by ionotropic glutamate receptors and depends on their precise localization at postsynaptic membranes opposing the presynaptic neurotransmitter release sites. Postsynaptic localization of N-methyl-D-aspartate-type glutamate receptors may be mediated by the synapse-associated proteins (SAPs) SAP90, SAP102, and chapsyn-110. SAPs contain three PDZ domains that can interact with the C termini of proteins such as N-methyl-D-aspartate receptor subunits that carry a serine or threonine at the -2 position and a valine, isoleucine, or leucine at the very C terminus (position 0). We now show that SAP97, a SAP whose function at the synapse has been unclear, is associated with alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptors. AMPA receptors are probably tetramers and are formed by two or more of the four AMPA receptor subunits GluR1-4. GluR1 possesses a C-terminal consensus sequence for interactions with PDZ domains of SAPs. SAP97 was present in AMPA receptor complexes immunoprecipitated from detergent extracts of rat brain. After treatment of rat brain membrane fractions with the cross-linker dithiobis(succinimidylpropionate) and solubilization with sodium dodecylsulfate, SAP97 was associated with GluR1 but not GluR2 or GluR3. In vitro experiments with recombinant proteins indicate that SAP97 specifically associates with the C terminus of GluR1 but not other AMPA receptor subunits. Our findings suggest that SAP97 may be involved in localizing AMPA receptors at postsynaptic sites through its interaction with the GluR1 subunit. Show less