[Pulmonary complications of Chronic Granulomatous Disease]

Chronic Granulomatosis Disease (CGD) is an inherited immune deficiency due to a mutation in the genes coding for the subunits of the NADPH oxidase enzyme that affects the oxidative capacity of phagocytic cells. It is characterized by increased susceptibility to bacterial and fungal infections, particularly Aspergillus, as well as complications associated with hyperinflammation and granulomatous tissue infiltration. There exist two types of frequently encountered pulmonary manifestations: (1) due to their being initially pauci-symptomatic, possibly life-threatening infectious complications are often discovered at a late stage. Though their incidence has decreased through systematic anti-bacterial and anti-fungal prophylaxis, they remain a major cause of morbidity and mortality; (2) inflammatory complications consist in persistent granulomatous mass or interstitial pneumoniae, eventually requiring immunosuppressive treatment. Pulmonary complications recurring since infancy generate parenchymal and bronchial sequelae that impact functional prognosis. Hematopoietic stem cell allograft is a curative treatment; it is arguably life-sustaining and may limit the morbidity of the disease. As a result of improved pediatric management, life expectancy has increased dramatically. That said, new challenges have appeared with regard to adults: difficulties of compliance, increased inflammatory manifestations, acquired resistance to anti-infectious therapies. These different developments underscore the importance of the transition period and the need for multidisciplinary management.

Late relapse after hematopoietic stem cell transplantation for acute leukemia: a retrospective study by SFGM-TC

Late relapse (LR) after allogeneic hematopoietic stem cell transplantation (AHSCT) for acute leukemia is a rare event (nearly 4.5%) and raises the questions of prognosis and outcome after salvage therapy. We performed a retrospective multicentric study between January 1, 2010, and December 31, 2016, using data from the French national retrospective register ProMISe provided by the SFGM-TC (French Society for Bone Marrow Transplantation and Cellular Therapy). We included patients presenting with LR, defined as a relapse occurring at least 2 years after AHSCT. We used the Cox model to identify prognosis factors associated with LR. During the study period, a total of 7582 AHSCTs were performed in 29 centers, and 33.8% of patients relapsed. Among them, 319 (12.4%) were considered to have LR, representing an incidence of 4.2% for the entire cohort. The full dataset was available for 290 patients, including 250 (86.2%) with acute myeloid leukemia and 40 (13.8%) with acute lymphoid leukemia. The median interval from AHSCT to LR was 38.2 months (interquartile range [IQR], 29.2 to 49.7 months), and 27.2% of the patients had extramedullary involvement at LR (17.2% exclusively and 10% associated with medullary involvement). One-third of the patients had persistent full donor chimerism at LR. Median overall survival (OS) after LR was 19.9 months (IQR, 5.6 to 46.4 months). The most common salvage therapy was induction regimen (55.5%), with complete remission (CR) obtained in 50.7% of cases. Ninety-four patients (38.5%) underwent a second AHSCT, with a median OS of 20.4 months (IQR, 7.1 to 49.1 months). Nonrelapse mortality after second AHSCT was 18.2%. The Cox model identified the following factors as associated with delay of LR: disease status not in first CR at first HSCT (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.04 to 1.64; P = .02) and the use of post-transplantation cyclophosphamide (OR, 2.23; 95% CI, 1.21 to 4.14; P = .01). Chronic GVHD appeared to be a protective factor (OR, .64; 95% CI, .42 to .96; P = .04). The prognosis of LR is better than in early relapse, with a median OS after LR of 19.9 months. Salvage therapy associated with a second AHSCT improves outcome and is feasible, without creating excess toxicity.

Abstract B55: The alarmin IL-33 is expressed in breast cancer: An emerging role in breast cancer immunity via the activation of NK cells?

Interleukin (IL)-33 is an alarmin belonging to the IL-1 family. Through its receptor ST2, IL-33 promotes both type 1 and type 2 immune responses depending on i) the type of responding cells and ii) the microenvironment in damaged tissues. Paradoxical roles of IL-33 have been reported in the context of cancer. Indeed, experimental models of murine mammary carcinoma and clinical observations from breast cancer (BC) patients suggest a protumoral role for IL-33, while antitumor effects of IL-33 via T cell and NK cell activation have also been described in mice. These observations prompted us to revisit the role of IL-33/ST2 axis in BC immunity by investigating the expression of IL-33 in tumors and its impact on Natural Killer (NK) cells biology, which exert anti-tumoral properties via cytokine production and cytotoxic function. Using immunohistochemistry (IHC) as well as mRNA expression analyses (RTqPCR or in silico analyses using public transcriptomic datasets from human breast tumors), we observed that IL-33 is expressed at higher levels in i) Ductal carcinoma in situ (DCIS) compared to invasive breast cancer (IBC), especially in the stroma and ii) triple-negative BC. In situ, IL-33 was found to be expressed in endothelial cells and scattered cells within the stroma of breast tumors. Furthermore, we showed that IL-33, in combination with IL-12, i) potentiates greatly the production of IFN-γ (x1000) by NK cells, in an ST2-dependent manner, ii) induces CD25 and CD69 on their surface, iii) stimulates intracellular NFκB/p38MAPK/mTOR signaling pathways, and iii) increases their natural cytotoxicity towards K562 target cells as well as their proliferation. Importantly, we have some evidence that IL-33 activates a subset of CD56intermediate NK cells. Altogether, our observations are in favor of an NK-mediated antitumor role of IL-33 in cancer that we are currently investigating in a mouse tumor model in vivo.

Citation Format: Elena Blanc, Anais Eberhardt, Jennifer Herbulot, Céline Le Beux, Amelie Colombe, Anne-Pierre Morel, Pierre Saintigny, Emilie Charrier, Antoine Marcais, Isabelle Treilleux, Thierry Walzer, Christophe Caux, Nathalie Bendriss-Vermare. The alarmin IL-33 is expressed in breast cancer: An emerging role in breast cancer immunity via the activation of NK cells? [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B55.

MicroRNAs of the miR-290-295 Family Maintain Bivalency in Mouse Embryonic Stem Cells

Numerous developmentally regulated genes in mouse embryonic stem cells (ESCs) are marked by both active (H3K4me3)- and polycomb group (PcG)-mediated repressive (H3K27me3) histone modifications. This bivalent state is thought to be important for transcriptional poising, but the mechanisms that regulate bivalent genes and the bivalent state remain incompletely understood. Examining the contribution of microRNAs (miRNAs) to the regulation of bivalent genes, we found that the miRNA biogenesis enzyme DICER was required for the binding of the PRC2 core components EZH2 and SUZ12, and for the presence of the PRC2-mediated histone modification H3K27me3 at many bivalent genes. Genes that lost bivalency were preferentially upregulated at the mRNA and protein levels. Finally, reconstituting Dicer-deficient ESCs with ESC miRNAs restored bivalent gene repression and PRC2 binding at formerly bivalent genes. Therefore, miRNAs regulate bivalent genes and the bivalent state itself.

microRNA-mediated regulation of mTOR complex components facilitates discrimination between activation and anergy in CD4 T cells

Using Dicer-deficient CD4 T cells, Marcais et al. show that microRNAs regulate the expression of mTOR components that are needed to discriminate between activating and anergy-inducing stimuli.

T cell receptor (TCR) signals can elicit full activation with acquisition of effector functions or a state of anergy. Here, we ask whether microRNAs affect the interpretation of TCR signaling. We find that Dicer-deficient CD4 T cells fail to correctly discriminate between activating and anergy-inducing stimuli and produce IL-2 in the absence of co-stimulation. Excess IL-2 production by Dicer-deficient CD4 T cells was sufficient to override anergy induction in WT T cells and to restore inducible Foxp3 expression in Il2-deficient CD4 T cells. Phosphorylation of Akt on S473 and of S6 ribosomal protein was increased and sustained in Dicer-deficient CD4 T cells, indicating elevated mTOR activity. The mTOR components Mtor and Rictor were posttranscriptionally deregulated, and the microRNAs Let-7 and miR-16 targeted the Mtor and Rictor mRNAs. Remarkably, returning Mtor and Rictor to normal levels by deleting one allele of Mtor and one allele of Rictor was sufficient to reduce Akt S473 phosphorylation and to reduce co-stimulation–independent IL-2 production in Dicer-deficient CD4 T cells. These results show that microRNAs regulate the expression of mTOR components in T cells, and that this regulation is critical for the modulation of mTOR activity. Hence, microRNAs contribute to the discrimination between T cell activation and anergy.

MixMir: microRNA motif discovery from gene expression data using mixed linear models

microRNAs (miRNAs) are a class of ∼22nt non-coding RNAs that potentially regulate over 60% of human protein-coding genes. miRNA activity is highly specific, differing between cell types, developmental stages and environmental conditions, so the identification of active miRNAs in a given sample is of great interest. Here we present a novel computational approach for analyzing both mRNA sequence and gene expression data, called MixMir. Our method corrects for 3' UTR background sequence similarity between transcripts, which is known to correlate with mRNA transcript abundance. We demonstrate that after accounting for kmer sequence similarities in 3' UTRs, a statistical linear model based on motif presence/absence can effectively discover active miRNAs in a sample. MixMir utilizes fast software implementations for solving mixed linear models, which are widely used in genome-wide association studies (GWASs). Essentially we use 3' UTR sequence similarity in place of population cryptic relatedness in the GWAS problem. Compared to similar methods such as miReduce, Sylamer and cWords, we found that MixMir performed better at discovering true miRNA motifs in three mouse Dicer-knockout experiments from different tissues, two of which were collected by our group. We confirmed these results on protein and mRNA expression data obtained from miRNA transfection experiments in human cell lines. MixMir can be freely downloaded from https://github.com/ldiao/MixMir.

[Management of endocrine dysfunctions after allogeneic hematopoietic stem cell transplantation: a report of the SFGM-TC on gonadal failure and fertility]

In the attempt to harmonize clinical practices between different French transplantation centers, the French Society of Bone Marrow Transplantation and Cell Therapy (SFGM-TC) set up the third annual series of workshops which brought together practitioners from all member centers and took place in October 2012 in Lille. Here we report our results and recommendations regarding the management of short and long-term endocrine dysfunction following allogeneic stem cell transplantation. The key aim of this workshop was to give an overview gonadal failure, fertility preservation and post-transplant.

[Management of endocrine dysfunctions after allogeneic hematopoietic stem cell transplantation: a report of the SFGM-TC on adrenal insufficiency and osteoporosis]

In the attempt to harmonize clinical practices between different French transplantation centers, the French Society of Bone Marrow Transplantation and Cell Therapy (SFGM-TC) set up the third annual series of workshops which brought together practitioners from all member centers and took place in October 2012 in Lille. Here we report our results and recommendations regarding the management of short and long-term endocrine dysfunction following allogeneic stem cell transplantation. The key aim of this workshop was to give an overview on secondary adrenal insufficiency and osteoporosis post-transplant.

Dicer-dependent microRNA pathway controls invariant NKT cell development

Invariant NK T (iNKT) cells are a separate lineage of T lymphocytes with innate effector functions. They express an invariant TCR specific for lipids presented by CD1d and their development and effector differentiation rely on a unique gene expression program. We asked whether this program includes microRNAs, small noncoding RNAs that regulate gene expression posttranscriptionally and play a key role in the control of cellular differentiation programs. To this aim, we investigated iNKT cell development in mice in which Dicer, the RNase III enzyme that generates functional microRNAs, is deleted in cortical thymocytes. We find that Dicer deletion results in a substantial reduction of iNKT cells in thymus and their disappearance from the periphery, unlike mainstream T cells. Without Dicer, iNKT cells do not complete their innate effector differentiation and display a defective homeostasis due to increased cell death. Differentiation and homeostasis of iNKT cells require Dicer in a cell-autonomous fashion. Furthermore, we identify a miRNA profile specific for iNKT cells, which exhibits features of activated/effector T lymphocytes, consistent with the idea that iNKT cells undergo agonist thymic selection. Together, these results define a critical role of the Dicer-dependent miRNA pathway in the physiology of iNKT cells.