Characterisation of innate lymphoid cell populations at different sites in mice with defective T cell immunity

Abstract

Background: Innate lymphoid cells (ILCs) have now been identified within most tissues of the body and current evidence indicates that this family of cells play a fundamental role in maintaining tissue homeostasis. However, few studies have compared the ILC populations between several tissues. Methods: We sought to generate a comprehensive characterisation of the ILC populations in different tissues of C57BL/6 WT and genetically modified mice targeting costimulatory pathways, using transcription factor expression to define specific groups. Results: Consistent with studies individually describing the ILC composition in different tissues, our analysis revealed different ILC groups dominate the ILC population in different tissues. Additionally, we observed a population of IL-7Rα +Id2 + cells lacking expression of lineage markers but also lacking expression of GATA-3, RORgt or T-bet. This population was most evident in ear skin where it outnumbered the defined ILC groups, however, further experiments demonstrated that detection of these cells was influenced by how the tissue was digested, raising concerns as to its real nature. Since both ILC2 and ILC3 express ICOS, we then investigated the requirement for ICOS:ICOSL interactions in the homeostasis of ILC populations at these sites. Surprisingly, no significant differences were detected in the number of ILC1, ILC2 or ILC3 between WT and ICOSL -/- mice in any tissue, indicating that this pathway is not required for ILC homeostasis at these sites. These data were compared with CD80 -/-CD86 -/- mice given evidence of CD28 expression by some ILC and ILC crosstalk with activated T cells. Notably, the absence of CD28 ligands resulted in a significant increase in ILC2 and ILC3 numbers in the intestine. Conclusions: Together, these data provide new insight into ILC composition in different tissues in both WT and genetically modified mice where key costimulatory pathways are genetically deleted, providing a useful resource for further research into ILC biology.

Dynamic changes in intrathymic ILC populations during murine neonatal development

“…Notably, a population of ILC based on IL-7Rα expression in the absence of expression of an extensive panel of lineage markers was also observed ( Fig. 1F-H), consistent with a recent report identifying such cells in multiple tissues [14]. In this report, prolonged enzymatic digestion was shown to increase the frequency of these cells prompting concerns as to their exact nature; however, here the thymus was disaggregated using only mechanical means.…”

“…Mann-Whitney U-test (comparing two samples) or a one-way ANOVA (comparing three or more samples) was used for statistical analysis where *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001. In all graphs, the bar represents the median, n = 9 for day 1, n = 7 for day 7, n = 7 for day 14, and n = 7 for adulthood (apart from in F-H, where n = 8 for day 7 and n = 6 for day 14), with data (in panels B, C, D, E, G, H, I, and J) pooled from at least two independent experiments at each age. Full gating strategy for all flow cytometry data identifying thymic ILC populations is shown in Supporting Information of Id2 creERT2 × ROSA mT/mG mice after tamoxifen administration by oral gavage ( Fig.…”

The Influence of Innate Lymphoid Cells and Unconventional T Cells in Chronic Inflammatory Lung Disease

“…Under homeostatic conditions, the immune cell make-up of the mouse lung is predominantly conventional lymphocytes and myeloid cells, although NK cells and all three ILC subsets have also been identified in the airways, albeit at much lower frequencies (3, 4). The ILC2 population is thought to be tissue-resident and thus are the predominant helper-type ILCs in the steady-state mouse lung (3, 5).…”

Development of Type 2 Innate Lymphoid Cells Is Selectively Inhibited by Sustained E Protein Activity

“…2e), meaning that CD27 − ST2 − ILCs contain the ILC3 population but are not exclusively ILC3s. NKp46 and CCR6 have been used to classify ILC3s in small intestine preparations, but it has been shown that most ILC3s in the lung are NKp46 − , and only 20% are CCR6 + (32). We confirmed these results while trying to optimize our surface staining approach.…”