Sequential actions of EOMES and T-BET promote stepwise maturation of natural killer cells.

EOMES and T-BET are related T-box transcription factors that control natural killer (NK) cell development. Here we demonstrate that EOMES and T-BET regulate largely distinct gene sets during this process. EOMES is dominantly expressed in immature NK cells and drives early lineage specification by inducing hallmark receptors and functions. By contrast, T-BET is dominant in mature NK cells, where it induces responsiveness to IL-12 and represses the cell cycle, likely through transcriptional repressors. Regardless, many genes with distinct functions are co-regulated by the two transcription factors. By generating two gene-modified mice facilitating chromatin immunoprecipitation of endogenous EOMES and T-BET, we show a strong overlap in their DNA binding targets, as well as extensive epigenetic changes during NK cell differentiation. Our data thus suggest that EOMES and T-BET may distinctly govern, via differential expression and co-factors recruitment, NK cell maturation by inserting partially overlapping epigenetic regulations.

Cerpegin-derived furo[3,4-c]pyridine-3,4(1H,5H)-diones enhance cellular response to interferons by de novo pyrimidine biosynthesis inhibition.

There is an increasing interest in the field of cancer therapy for small compounds targeting pyrimidine biosynthesis, and in particular dihydroorotate dehydrogenase (DHODH), the fourth enzyme of this metabolic pathway. Three available DHODH structures, featuring three different known inhibitors, were used as templates to screen in silico an original chemical library from Erevan University. This process led to the identification of P1788, a compound chemically related to the alkaloid cerpegin, as a new class of pyrimidine biosynthesis inhibitors. In line with previous reports, we investigated the effect of P1788 on the cellular innate immune response. Here we show that pyrimidine depletion by P1788 amplifies cellular response to both type-I and type II interferons, but also induces DNA damage as assessed by γH2AX staining. Moreover, the addition of inhibitors of the DNA damage response led to the suppression of the P1788 stimulatory effects on the interferon pathway. This demonstrates that components of the DNA damage response are bridging the inhibition of pyrimidine biosynthesis by P1788 to the interferon signaling pathway. Altogether, these results provide new insights on the mode of action of novel pyrimidine biosynthesis inhibitors and their development for cancer therapies.

Identification of Primary Natural Killer Cell Modulators by Chemical Library Screening with a Luciferase-Based Functional Assay.

Natural killer (NK) cells are essential players of the innate immune response that secrete cytolytic factors and cytokines such as IFN-γ when contacting virus-infected or tumor cells. They represent prime targets in immunotherapy as defects in NK cell functions are hallmarks of many pathological conditions, such as cancer and chronic infections. The functional screening of chemical libraries or biologics would greatly help identify new modulators of NK cell activity, but commonly used methods such as flow cytometry are not easily scalable to high-throughput settings. Here we describe an efficient assay to measure the natural cytotoxicity of primary NK cells where the bioluminescent enzyme NanoLuc is constitutively expressed in the cytoplasm of target cells and is released in co-culture supernatants when lysis occurs. We fully characterized this assay using either purified NK cells or total peripheral blood mononuclear cells (PBMCs), including some patient samples, as effector cells. A pilot screen was also performed on a library of 782 metabolites, xenobiotics, and common drugs, which identified dextrometorphan and diphenhydramine as novel NK cell inhibitors. Finally, this assay was further improved by developing a dual-reporter cell line to simultaneously measure NK cell cytotoxicity and IFN-γ secretion in a single well, extending the potential of this system.

Chemical pollution and innate antiviral immunity: Dangerous Liaisons ?

Environmental pollution is of concern to civil society and as the problem intensifies, there is increasing pressure on politicians and polluters to assess and mitigate this risk. In addition, the emergence (or re-emergence) of viral pathologies such as dengue or chikungunya has also become a major concern requiring appropriate measures. Unfortunately, these two issues may well collide with unpredictable consequences in the next decades. Indeed, a growing number of studies suggests that organic pollutants could alter the innate antiviral response, including the type I interferon system (IFN-I). Such interactions could have significant consequences on the susceptibility of populations to viral infections, but also modify responses and protection induced by vaccines or favor the development of autoimmune diseases. The purpose of this review is to take stock of the known interactions between organic pollutants and the IFN-I response, and to present questions that should be addressed in the future in order to better assess this risk.

[Chemical pollution and innate antiviral immunity: Dangerous Liaisons?]. / Pollution chimique et immunité innée antivirale : des liaisons dangereuses ?

Environmental pollution is of concern to civil society and as the problem intensifies, there is increasing pressure on politicians and polluters to assess and mitigate this risk. In addition, the emergence (or re-emergence) of viral pathologies such as dengue or chikungunya has also become a major concern requiring appropriate measures. Unfortunately, these two issues may well collide with unpredictable consequences in the next decades. Indeed, a growing number of studies suggests that organic pollutants could alter the innate antiviral response, including the type I interferon system (IFN-I). Such interactions could have significant consequences on the susceptibility of populations to viral infections, but also modify responses and protection induced by vaccines or favor the development of autoimmune diseases. The purpose of this review is to take stock of the known interactions between organic pollutants and the IFN-I response, and to present questions that should be addressed in the future in order to better assess this risk.