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An orchestrated cellular network, including adaptive lymphocytes and group 3 innate lymphoid cells (ILC3s), maintains intestinal barrier integrity and homeostasis. T cells can monitor environmental insults through constitutive circulation, scanning tissues and forming immunological contacts, a process named immunosurveillance. In contrast, the dynamics of intestinal ILC3s are unknown. Using intravital imaging, we observed that villus ILC3s were largely immotile at steady state but acquired migratory ‘patrolling’ attributes and enhanced cytokine expression in response to inflammation. We showed that T cells, the chemokine CCL25 and bacterial ligands regulated intestinal ILC3 behavior and that loss of patrolling behavior by interleukin-22 (IL-22)-producing ILC3s altered the intestinal barrier through increased epithelial cell death. Collectively, we identified notable differences between the behavior of ILC3s and T cells, with a prominent adaptation of intestinal ILC3s toward mucosal immunosurveillance after inflammation.

International audience; Natural Killer (NK) cells are innate effectors armed with cytotoxic and cytokine-secreting capacities whose spontaneous anti-tumor activity is key to numerous immunotherapeutic strategies. However, current mouse models fail to mirror the extensive human immune system variation that exists in the normal population which may impact on NK cell-based therapies. We performed a comprehensive profiling of NK cells in the Collaborative Cross (CC), a collection of novel recombinant inbred mouse strains whose genetic diversity matches that of humans, thereby providing a unique and highly diverse small animal model for the study of immune variation. We demonstrate that NK cells from CC lines displayed a breadth of phenotypic and functional variation reminiscent of that reported for humans with regards to cell numbers, key marker expression and functional capacities. We took advantage of the vast genetic diversity of the CC and identified 9 genomic loci through quantitative trait locus mapping driving these phenotypic variations. SNP haplotype-patterns and variant effect analyses identified candidate genes associated with lung NK cell numbers, frequencies of CD94+NK cells, and expression levels of NKp46. Thus, we demonstrate that the CC represents an outstanding resource to study NK cell diversity and its regulation by hostgenetics.

Group 2 innate lymphoid cells (ILC2s) represent innate homologs of type 2 helper T cells (TH2) that participate in immune defense and tissue homeostasis through production of type 2 cytokines. While T lymphocytes metabolically adapt to microenvironmental changes, knowledge of human ILC2 metabolism is limited, and its key regulators are unknown. Here, we show that circulating ‘naive’ ILC2s have an unexpected metabolic profile with a higher level of oxidative phosphorylation (OXPHOS) than natural killer (NK) cells. Accordingly, ILC2s are severely reduced in individuals with mitochondrial disease (MD) and impaired OXPHOS. Metabolomic and nutrient receptor analysis revealed ILC2 uptake of amino acids to sustain OXPHOS at steady state. Following activation with interleukin-33 (IL-33), ILC2s became highly proliferative, relying on glycolysis and mammalian target of rapamycin (mTOR) to produce IL-13 while continuing to fuel OXPHOS with amino acids to maintain cellular fitness and proliferation. Our results suggest that proliferation and function are metabolically uncoupled in human ILC2s, offering new strategies to target ILC2s in disease settings., ILC2 metabolism has been largely unexplored. Di Santo and colleagues examine metabolic profiles from naive and cytokine-activated ILC2s and find that IL-33-triggered ILC2s rely on distinct metabolic pathways to sustain proliferation and function.

To study gene functions specifically in NKp46+ cells we developed novel Cre mice allowing for conditional gene targeting in cells expressing Ncr1 (encoding NKp46). We generated transgenic Ncr1greenCre mice carrying an EGFPcre fusion under the control of a proximal Ncr1 promoter that faithfully directed EGFPcre expression to NKp46+ cells from lymphoid and nonlymphoid tissues. This approach allowed for direct detection of Cre-expressing NKp46+ cells via their GFP signature by flow cytometry and histology. Cre was functional as evidenced by the NKp46+ cell-specific expression of RFP in Ncr1greenCreRosa-dtRFP reporter mice. We generated Ncr1greenCreIl2rgfl/fl mice that lack NKp46+ cells in an otherwise intact hematopoietic environment. Il2rg encodes the common gamma chain (γc), which is an essential receptor subunit for cytokines (IL-2, -4, -7, -9, -15, and -21) that stimulate lymphocyte development and function. In Ncr1greenCreIl2rgfl/fl mice, NK cells are severely reduced and the few remaining NKp46+ cells escaping γc deletion failed to express GFP. Using this new NK-cell-deficient model, we demonstrate that the homeostasis of NKp46+ cells from all tissues (including the recently described intraepithelial ILC1 subset) requires Il2rg. Finally, Ncr1greenCreIl2rgfl/fl mice are unable to reject B16 lung metastases demonstrating the essential role of NKp46+ cells in antimelanoma immune responses.

Cystic fibrosis (CF) airway epithelium is constantly subjected to injury events due to chronic infection and inflammation. Moreover, abnormalities in CF airway epithelium repair have been described and contribute to the lung function decline seen in CF patients. In the last past years, it has been proposed that anoctamin 1 (ANO1), a Ca2+-activated Cl− channel, might offset the CFTR deficiency but this protein has not been characterized in CF airways. Interestingly, recent evidence indicates a role for ANO1 in cell proliferation and tumor growth. Our aims were to study non-CF and CF bronchial epithelial repair and to determine whether ANO1 is involved in airway epithelial repair. Here, we showed, with human bronchial epithelial cell lines and primary cells, that both cell proliferation and migration during epithelial repair are delayed in CF compared to non-CF cells. We then demonstrated that ANO1 Cl− channel activity was significantly decreased in CF versus non-CF cells. To explain this decreased Cl− channel activity in CF context, we compared ANO1 expression in non-CF vs. CF bronchial epithelial cell lines and primary cells, in lung explants from wild-type vs. F508del mice and non-CF vs. CF patients. In all these models, ANO1 expression was markedly lower in CF compared to non-CF. Finally, we established that ANO1 inhibition or overexpression was associated respectively with decreases and increases in cell proliferation and migration. In summary, our study demonstrates involvement of ANO1 decreased activity and expression in abnormal CF airway epithelial repair and suggests that ANO1 correction may improve this process.

Duchenne muscular dystrophy is characterized by muscular atrophy, fibrosis, and fat accumulation. Several groups have demonstrated that in the mdx mouse, the exon-skipping strategy can restore a quasi-dystrophin in almost 100% of the muscle fibers. On the other hand, inhibition of the myostatin pathway in adult mice has been described to enhance muscle growth and improve muscle force. Our aim was to combine these two strategies to evaluate a possible additive effect. We have chosen to inhibit the myostatin pathway using the technique of RNA interference directed against the myostatin receptor AcvRIIb mRNA (sh-AcvRIIb). The restoration of a quasi-dystrophin was mediated by the vectorized U7 exon-skipping technique (U7-DYS). Adeno-associated vectors carrying either the sh-AcvrIIb construct alone, the U7-DYS construct alone, or a combination of both constructs were injected in the tibialis anterior (TA) muscle of dystrophic mdx mice. We show that even if each separate approach has some effects on muscle physiology, the combination of the dystrophin rescue and the downregulation of the myostatin receptor is required to massively improve both the tetanic force and the specific force. This study provides a novel pharmacogenetic strategy for treatment of certain neuromuscular diseases associated with muscle wasting.

Group 3 innate lymphoid cells (ILC3) actively participate in mucosal defense and homeostasis through prompt secretion of IL-17A, IL-22, and IFN-γ. Reports identify two ILC3 lineages: a CCR6+T-bet− subset that appears early in embryonic development and promotes lymphoid organogenesis and a CCR6−T-bet+ subset that emerges after microbial colonization and harbors NKp46+ ILC3. We demonstrate that NKp46 expression in the ILC3 subset is highly unstable. Cell fate mapping using Ncr1CreGFP × Rosa26RFP mice revealed the existence of an intestinal RFP+ ILC3 subset (Ncr1FM) lacking NKp46 expression at the transcript and protein levels. Ncr1FM ILC3 produced more IL-22 and were distinguishable from NKp46+ ILC3 by differential CD117, CD49a, DNAX accessory molecule-1, and, surprisingly, CCR6 expression. Ncr1FM ILC3 emerged after birth and persisted in adult mice following broad-spectrum antibiotic treatment. These results identify an unexpected phenotypic instability within NKp46+ ILC3 that suggests a major role for environmental signals in tuning ILC3 functional plasticity.

Background Investigations into both the pathophysiology and therapeutic targets in muscle dystrophies have been hampered by the limited proliferative capacity of human myoblasts. Isolation of reliable and stable immortalized cell lines from patient biopsies is a powerful tool for investigating pathological mechanisms, including those associated with muscle aging, and for developing innovative gene-based, cell-based or pharmacological biotherapies. Methods Using transduction with both telomerase-expressing and cyclin-dependent kinase 4-expressing vectors, we were able to generate a battery of immortalized human muscle stem-cell lines from patients with various neuromuscular disorders. Results The immortalized human cell lines from patients with Duchenne muscular dystrophy, facioscapulohumeral muscular dystrophy, oculopharyngeal muscular dystrophy, congenital muscular dystrophy, and limb-girdle muscular dystrophy type 2B had greatly increased proliferative capacity, and maintained their potential to differentiate both in vitro and in vivo after transplantation into regenerating muscle of immunodeficient mice. Conclusions Dystrophic cellular models are required as a supplement to animal models to assess cellular mechanisms, such as signaling defects, or to perform high-throughput screening for therapeutic molecules. These investigations have been conducted for many years on cells derived from animals, and would greatly benefit from having human cell models with prolonged proliferative capacity. Furthermore, the possibility to assess in vivo the regenerative capacity of these cells extends their potential use. The innovative cellular tools derived from several different neuromuscular diseases as described in this report will allow investigation of the pathophysiology of these disorders and assessment of new therapeutic strategies.

12-O-tetradecanoyl phorbol-13-acetate-induced sequence 7/interferon related development regulator 1 (Tis7/IFRD1) has been recently identified as a modifier gene in lung inflammatory disease severity in patients with cystic fibrosis (CF), based upon its capacity to regulate inflammatory activities in neutrophils. In CF patients, the F508del mutation in the Cftr gene encoding a chloride channel, the CF transmembrane conductance regulator (CFTR) in airway epithelial cells results in an exaggerated inflammatory response of these cells. At present, it is unknown whether the Tis7/IFRD1 gene product is expressed in airway epithelial cells. We therefore investigated the possibility there is an intrinsic alteration in Tis7/IFRD1 protein level in cells lacking CFTR function in tracheal homogenates of F508del-CFTR mice and in a F508del-CFTR human bronchial epithelial cell line (CFBE41o− cells). When Tis7/IFRD1 protein was detectable, trachea from F508del-CFTR mice showed a reduction in the level of Tis7/IFRD1 protein compared to wild-type control littermates. A significant reduction of IFRD1 protein level was found in CFBE41o− cells compared to normal bronchial epithelial cells 16HBE14o−. Surprisingly, messenger RNA level of IFRD1 in CFBE41o− cells was found elevated. Treating CFBE41o− cells with the antioxidant glutathione rescued the IFRD1 protein level closer to control level and also reduced the pro-inflammatory cytokine IL-8 release. This work provides evidence for the first time of reduced level of IFRD1 protein in murine and human F508del-CFTR airway epithelial cell models, possibly mediated in response to oxidative stress which might contribute to the exaggerated inflammatory airway response observed in CF patients homozygous for the F508del mutation.

Cystic fibrosis (CF) is caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene which is a Cl− channel and a regulator of the epithelial Na+ channel (ENaC). We have recently shown that newborn CFTR-deficient mice exhibit abnormalities of the tracheal cartilage leading to altered ventilation ( Bonvin et al., 2008 ). However, the mechanism by which a lack of CFTR causes tracheal cartilage defects remains unknown. The main goal of the present study was to determine whether the development of airway cartilage defects is related to ENac channel dysfunction. We thus performed macroscopic analysis of the trachea and explored ventilatory function in adult βENaC-overexpressing (βENaC-Tg) mice with airway Na+ hyperabsorption and “CF-lung” lung disease, at 2 and 5 month of age. Only minor cartilaginous abnormalities were observed in 8 out of 16 βENaC-Tg mice and in 2 out of 20 littermate controls. Breathing pattern was progressively altered in βENaC-Tg mice as evidenced by a significant decrease in respiratory frequency. Our results suggest that Na+ hyperabsorption alone is not a major contributor to the development of tracheal malformation observed in CF mice and that breathing pattern changes in βENaC-Tg mice likely reflect airflow limitation due to airway mucus obstruction.

Duchenne Muscular Dystrophy (DMD) is the most severe degenerative disorder of skeletal and cardiac muscle. DMD patients show a progressive muscle weakness which begins in early childhood. Our goal is to stop this continuous muscle wasting.