Mast Cells Are Identified in the Lung Parenchyma of Wild Mice, Which Can Be Recapitulated in Naturalized Laboratory Mice

Abstract

BackgroundIt is well documented that laboratory mice bred and maintained in ultra-hygienic specific pathogen-free (SPF) barriers display reduced richness and complexity of microbiota compared with wild mice. The laboratory mice profoundly lack lung parenchymal mast cells. Hence, we aimed to investigate the lung distribution of mast cells in free-living wild mice.MethodsWild house mice were trapped in South-Eastern Norway and Hemtabad, West Bengal, India. C57BL/6 laboratory mice were bred in a purposefully built, closed environment with bedding material obtained from the natural environment in order to normalize the gut microbiota of these laboratory mice to that of the wild mice, and the offspring were collected for study at eight weeks of age.ResultsMast cells were easily identified at a substantial density in the lung parenchymal tissues of wild mice from both Norway and India, which stands in clear contrast to the rare distribution of lung parenchymal mast cells in the conventional laboratory SPF mice. Consistently, wild mice also expressed higher pulmonary levels of stem cell factor, a critical growth factor for mast cell survival. Higher levels of histamine were recorded in the lung tissues of the wild mice. Interestingly, “naturalized” C57BL/6 laboratory mice which spent their entire life in a semi-natural environment developed lung parenchymal mast cells at an appreciable density.ConclusionOur observations support that environmental factors, possibly through modulation of microbiota, may impact the tissue distribution of mast cells in mouse lung parenchyma.

From germ-free to wild: modulating microbiome complexity to understand mucosal immunology

“…These include: (i) introducing fecal matter from wild mice to GF mice by oral gavage; 112 (ii) transferring embryos from lab mice to wild surrogate dams to generate "wildlings"; 111 (iii) "re-wilding" laboratory mice by housing them in an outside enclosure that recapitulates the habitat of wild mice; 122 or (iv) housing them with bedding from their natural environment. 123 Each approach results in genetically identical laboratory mice with wild microbiomes that can be stably transferred and maintained over generations, thus facilitating microbiome diversification while preventing confounding results from genetic variability. Although similar, their resulting microbiomes may not fully converge with those of wild mice, as has been described for wildlings, 111 possibly due to differences in host genomes and diets.…”

“…It is possible that these differences are sufficient to shape the local innate immune cell landscape, as mast cells are enriched in the lung parenchyma of wild but not SPF mice. 123 Yeh et al found that housing SPF mice in a semi-natural environment consisting of farmhouse-sourced bedding was sufficient to increase mast cell recruitment to the lung. 123 Although environmental components played a role in driving this phenotype, microbial communities present in the mice, or the bedding were not characterized in this study.…”

“…123 Yeh et al found that housing SPF mice in a semi-natural environment consisting of farmhouse-sourced bedding was sufficient to increase mast cell recruitment to the lung. 123 Although environmental components played a role in driving this phenotype, microbial communities present in the mice, or the bedding were not characterized in this study. Mast cells play a key role in IgE-mediated allergic responses and are present in abundance in the human lung parenchyma.…”

Human placental extracts suppress mast cell activation and induce mast cell apoptosis

“…For some of the PCA assays, Evans blue was obviated and ear tissues were sectioned and analyzed with toluidine blue staining for revealing mast cell morphology as previously described [18]. Or alternatively, the ear sections were processed for histamine analysis as previously described [19]. Brie y, the sections were incubated with the rabbit anti-histamine antibody (Fine Test, Wuhan, China), and then with horseradish peroxidase-linked anti-rabbit and anti-mouse universal secondary antibodies (Solarbio, Beijing, China).…”

In Vivo RNA Delivery to Hematopoietic Stem and Progenitor Cells via Targeted Lipid Nanoparticles

“…Other than being highly expressed on mast cells, CD117 is expressed on interstitial Cajal cells of the intestine and melanocytes of the skin . However, CD117 is reported to be expressed at very low levels in the lungs , suggesting that the strong luminescence signal in the lungs is a result of nonspecific binding from the antibody. Further work is needed to identify the specific cell type that is being transfected in the lungs and whether there is a specific receptor that is interacting with the antibody.…”