Project description:Alveolar macrophages maintain lung homeostasis and are critical for host defense to respiratory pathogens, including influenza virus. Yet how aging impacts alveolar macrophages remains unclear. Here, we found that aging reduces the proliferation and concentration of alveolar macrophages under basal conditions in mice. Transcriptomic analysis revealed that aging induces a down regulation in cell cycling pathways in alveolar macrophages. Functionally, aging impaired the capacity of alveolar macrophages to phagocytose in vivo, and also increased influenza virus-induced lung damage, morbidity and mortality. Depleting alveolar macrophages indicated that these cells were critical for accelerated mortality during influenza viral lung infection with aging. Adoptive transfer experiments demonstrated that aging impaired the ability of alveolar macrophages to reduce lung damage after influenza viral infection. Thus, our study has revealed that aging impairs alveolar macrophages to resolve damageand increases mortality after influenza viral infection.
Project description:Resident memory B (BRM) cells develop and persist in the lungs of influenza infected mice and humans but their contribution to recall responses following rechallenge has not been defined. We used scRNA-seq to identify early changes in lung immune cell composition and gene expression following secondary influenza infection and tested the effect of alveolar macrophage depletion (using intranasally delivered CLL). We found an alveolar macrophage dependent upregulation of IFNG-associated pathways after influenza rechallenge, that included increased expression of CXCL9, CXCL10 and CCL5 in myeloid cells.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:The importance of unanchored Ub in innate immunity has been shown only for a limited number of unanchored Ub-interactors. We investigated what additional cellular factors interact with unanchored Ub and whether unanchored Ub plays a broader role in innate immunity. To identify unanchored Ub-interacting factors from murine lungs, we used His-tagged recombinant poly-Ub chains as bait. These chains were mixed with lung tissue lysates and protein complexes were isolated with Ni-NTA beads. Sample elutions were subjected to mass spectrometry (LC-MSMS) analysis.
Project description:This project is based upon the fundamental observation that alveolar macrophage-derived extracellular vesicles (AM-EVs), when internalized by neighboring epithelial cells, inhibit their infection by influenza virus. This inhibitory activity of AM-EVs is abolished when AMs are treated with cigarette smoke extract (CSE). We chose to survey the AM-EV proteome in an effort to identify candidate proteins whose abundance within EVs was downregulated by CSE treatment of AMs, thus explaining the ability of CSE to abrogate the inhibitory activity against influenza.
Project description:CD47 is an ubiquitously expressed surface molecule that has a significant impact on immune responses. However, its role for antiviral immunity is not fully understood. We can show that CD47 has an inhibitory role in influenza virus defense, since CD47-deficient mice (CD47-/-) display an increased viral clearance during influenza virus infection. This effect is strongly associated with alveolar macrophages, yet the underlying mechanisms are unclear. Thus, to assess the precise impact of CD47 on antiviral action of alveolar macrophages, transcriptional analysis of ex vivo isolated alveolar macrophages from CD47-/- and WT mice were performed isolated 3dpi. Surprisingly, instead of classical antiviral mediators, an increased expression of both hemoglobin α and hemoglobin β was found in CD47 deficient compared to WT alveolar macrophages upon influenza A virus infection. Importantly, antiviral activity of hemoglobin was already shown for other viruses and thus, CD47 might limit influenza virus defense via the regulation of hemoglobin, which could act as a modulator of the antiviral immune response during the infection.
Project description:BACKGROUND: Long terminal repeat (LTR) retrotransposons make up a large fraction of the typical mammalian genome. They comprise about 8% of the human genome and approximately 10% of the mouse genome. On account of their abundance, LTR retrotransposons are believed to hold major significance for genome structure and function. Recent advances in genome sequencing of a variety of model organisms has provided an unprecedented opportunity to evaluate better the diversity of LTR retrotransposons resident in eukaryotic genomes. RESULTS: Using a new data-mining program, LTR_STRUC, in conjunction with conventional techniques, we have mined the GenBank mouse (Mus musculus) database and the more complete Ensembl mouse dataset for LTR retrotransposons. We report here that the M. musculus genome contains at least 21 separate families of LTR retrotransposons; 13 of these families are described here for the first time. CONCLUSIONS: All families of mouse LTR retrotransposons are members of the gypsy-like superfamily of retroviral-like elements. Several different families of unrelated non-autonomous elements were identified, suggesting that the evolution of non-autonomy may be a common event. High sequence similarity between several LTR retrotransposons identified in this study and those found in distantly-related species suggests that horizontal transfer has been a significant factor in the evolution of mouse LTR retrotransposons.
Project description:Copy number variation is an important dimension of genetic diversity and has implications in development and disease. As an important model organism, the mouse is a prime candidate for copy number variant (CNV) characterization, but this has yet to be completed for a large sample size. Here we report CNV analysis of publicly available, high-density microarray data files for 351 mouse tail samples, including 290 mice that had not been characterized for CNVs previously.We found 9634 putative autosomal CNVs across the samples affecting 6.87% of the mouse reference genome. We find significant differences in the degree of CNV uniqueness (single sample occurrence) and the nature of CNV-gene overlap between wild-caught mice and classical laboratory strains. CNV-gene overlap was associated with lipid metabolism, pheromone response and olfaction compared to immunity, carbohydrate metabolism and amino-acid metabolism for wild-caught mice and classical laboratory strains, respectively. Using two subspecies of wild-caught Mus musculus, we identified putative CNVs unique to those subspecies and show this diversity is better captured by wild-derived laboratory strains than by the classical laboratory strains. A total of 9 genic copy number variable regions (CNVRs) were selected for experimental confirmation by droplet digital PCR (ddPCR).The analysis we present is a comprehensive, genome-wide analysis of CNVs in Mus musculus, which increases the number of known variants in the species and will accelerate the identification of novel variants in future studies.