Genome-wide off-target analyses of CRISPR/Cas9-mediated T-cell receptor engineering in primary human T cells.

OBJECTIVES: Exploiting the forces of human T cells for treatment has led to the current paradigm of emerging immunotherapy strategies. Genetic engineering of the T-cell receptor (TCR) redirects specificity, ablates alloreactivity and brings significant progress and off-the-shelf options to emerging adoptive T-cell transfer (ACT) approaches. Targeted CRISPR/Cas9-mediated double-strand breaks in the DNA enable knockout or knock-in engineering. METHODS: Here, we perform CRISPR/Cas9-mediated TCR knockout using a therapeutically relevant ribonucleoprotein (RNP) delivery method to assess the safety of genetically engineered T-cell products. Whole-genome sequencing was performed to analyse whether CRISPR/Cas9-mediated DNA double-strand break at the TCR locus is associated with off-target events in human primary T cells. RESULTS: TCRα chain and TCRß chain knockout leads to high on-target InDel frequency and functional knockout. None of the predicted off-target sites could be confirmed experimentally, whereas whole-genome sequencing and manual Integrative Genomics Viewer (IGV) review revealed 9 potential low-frequency off-target events genome-wide. Subsequent amplification and targeted deep sequencing in 7 of 7 evaluable loci did not confirm these low-frequency InDels. Therefore, off-target events are unlikely to be caused by the CRISPR/Cas9 engineering. CONCLUSION: The combinatorial approach of whole-genome sequencing and targeted deep sequencing confirmed highly specific genetic engineering using CRISPR/Cas9-mediated TCR knockout without potentially harmful exonic off-target effects.

A multifunctional mouse model to study the role of Samd3.

The capacity to develop immunological memory is a hallmark of the adaptive immune system. To investigate the role of Samd3 for cellular immune responses and memory development, we generated a conditional knock-out mouse including a fluorescent reporter and a huDTR cassette for conditional depletion of Samd3-expressing cells. Samd3 expression was observed in NK cells and CD8 T cells, which are known for their specific function against intracellular pathogens like viruses. After acute viral infections, Samd3 expression was enriched within memory precursor cells and the frequency of Samd3-expressing cells increased during the progression into the memory phase. Similarly, during chronic viral infections, Samd3 expression was predominantly detected within precursors of exhausted CD8 T cells that are critical for viral control. At the functional level however, Samd3-deficient CD8 T cells were not compromised in the context of acute infection with Vaccinia virus or chronic infection with Lymphocytic choriomeningitis virus. Taken together, we describe a novel multifunctional mouse model to study the role of Samd3 and Samd3-expressing cells. We found that Samd3 is specifically expressed in NK cells, memory CD8 T cells, and precursor exhausted T cells during viral infections, while the molecular function of this enigmatic gene remains further unresolved.

An Immersive Investment Game to Study Human-Robot Trust.

As robots become more advanced and capable, developing trust is an important factor of human-robot interaction and cooperation. However, as multiple environmental and social factors can influence trust, it is important to develop more elaborate scenarios and methods to measure human-robot trust. A widely used measurement of trust in social science is the investment game. In this study, we propose a scaled-up, immersive, science fiction Human-Robot Interaction (HRI) scenario for intrinsic motivation on human-robot collaboration, built upon the investment game and aimed at adapting the investment game for human-robot trust. For this purpose, we utilize two Neuro-Inspired COmpanion (NICO) - robots and a projected scenery. We investigate the applicability of our space mission experiment design to measure trust and the impact of non-verbal communication. We observe a correlation of 0.43 ( p = 0.02 ) between self-assessed trust and trust measured from the game, and a positive impact of non-verbal communication on trust ( p = 0.0008 ) and robot perception for anthropomorphism ( p = 0.007 ) and animacy ( p = 0.00002 ). We conclude that our scenario is an appropriate method to measure trust in human-robot interaction and also to study how non-verbal communication influences a human's trust in robots.

BATF3 programs CD8+ T cell memory.

Antiviral CD8+ T cell responses are characterized by an initial activation/priming of T lymphocytes followed by a massive proliferation, subset differentiation, population contraction and the development of a stable memory pool. The transcription factor BATF3 has been shown to play a central role in the development of conventional dendritic cells, which in turn are critical for optimal priming of CD8+ T cells. Here we show that BATF3 was expressed transiently within the first days after T cell priming and had long-lasting T cell-intrinsic effects. T cells that lacked Batf3 showed normal expansion and differentiation, yet succumbed to an aggravated contraction and had a diminished memory response. Vice versa, BATF3 overexpression in CD8+ T cells promoted their survival and transition to memory. Mechanistically, BATF3 regulated T cell apoptosis and longevity via the proapoptotic factor BIM. By programing CD8+ T cell survival and memory, BATF3 is a promising molecule to optimize adoptive T cell therapy in patients.

Enzymatic Activity of HPGD in Treg Cells Suppresses Tconv Cells to Maintain Adipose Tissue Homeostasis and Prevent Metabolic Dysfunction.

Regulatory T cells (Treg cells) are important for preventing autoimmunity and maintaining tissue homeostasis, but whether Treg cells can adopt tissue- or immune-context-specific suppressive mechanisms is unclear. Here, we found that the enzyme hydroxyprostaglandin dehydrogenase (HPGD), which catabolizes prostaglandin E2 (PGE2) into the metabolite 15-keto PGE2, was highly expressed in Treg cells, particularly those in visceral adipose tissue (VAT). Nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ)-induced HPGD expression in VAT Treg cells, and consequential Treg-cell-mediated generation of 15-keto PGE2 suppressed conventional T cell activation and proliferation. Conditional deletion of Hpgd in mouse Treg cells resulted in the accumulation of functionally impaired Treg cells specifically in VAT, causing local inflammation and systemic insulin resistance. Consistent with this mechanism, humans with type 2 diabetes showed decreased HPGD expression in Treg cells. These data indicate that HPGD-mediated suppression is a tissue- and context-dependent suppressive mechanism used by Treg cells to maintain adipose tissue homeostasis.

TALEN-mediated genome engineering to generate targeted mice.

Genetic mouse models are critical for biomedical research to understand gene function and pathophysiology. In the last years, the generation of genetic mouse models has been revolutionized by the emergence of transcription activator-like effector nucleases (TALENs). TALENs are programmable, sequence-specific DNA-binding proteins fused to a non-specific endonuclease domain used as powerful tools for site-specific induction of DNA double-strand breaks. These result in disruption of the gene product of the targeted locus by mutations induced during repair by error-prone non-homologous end-joining. Alternatively, these DNA double-strand breaks can be exploited to integrate a user-defined sequence by homologous recombination if an appropriate repair plasmid is provided. In this review, we highlight the major technological improvements for genome editing in murine oocytes which have been achieved using TALENs, discuss current limitations of the technology, suggest strategies to broadly apply TALENs, and describe possible future directions to facilitate gene editing in murine oocytes.

Efficient genome engineering by targeted homologous recombination in mouse embryos using transcription activator-like effector nucleases.

Generation of mouse models by introducing transgenes using homologous recombination is critical for understanding fundamental biology and pathology of human diseases. Here we investigate whether artificial transcription activator-like effector nucleases (TALENs)-powerful tools that induce DNA double-strand breaks at specific genomic locations-can be combined with a targeting vector to induce homologous recombination for the introduction of a transgene in embryonic stem cells and fertilized murine oocytes. We describe the generation of a conditional mouse model using TALENs, which introduce double-strand breaks at the genomic locus of the special AT-rich sequence-binding protein-1 in combination with a large 14.4 kb targeting template vector. We report successful germline transmission of this allele and demonstrate its recombination in primary cells in the presence of Cre-recombinase. These results suggest that TALEN-assisted induction of DNA double-strand breaks can facilitate homologous recombination of complex targeting constructs directly in oocytes.

The Drosophila Arf GEF Steppke controls MAPK activation in EGFR signaling.

Guanine nucleotide exchange factors (GEFs) of the cytohesin protein family are regulators of GDP/GTP exchange for members of the ADP ribosylation factor (Arf) of small GTPases. They have been identified as modulators of various receptor tyrosine kinase signaling pathways including the insulin, the vascular epidermal growth factor (VEGF) and the epidermal growth factor (EGF) pathways. These pathways control many cellular functions, including cell proliferation and differentiation, and their misregulation is often associated with cancerogenesis. In vivo studies on cytohesins using genetic loss of function alleles are lacking, however, since knockout mouse models are not available yet. We have recently identified mutants for the single cytohesin Steppke (Step) in Drosophila and we could demonstrate an essential role of Step in the insulin signaling cascade. In the present study, we provide in vivo evidence for a role of Step in EGFR signaling during wing and eye development. By analyzing step mutants, transgenic RNA interference (RNAi) and overexpression lines for tissue specific as well as clonal analysis, we found that Step acts downstream of the EGFR and is required for the activation of mitogen-activated protein kinase (MAPK) and the induction of EGFR target genes. We further demonstrate that step transcription is induced by EGFR signaling whereas it is negatively regulated by insulin signaling. Furthermore, genetic studies and biochemical analysis show that Step interacts with the Connector Enhancer of KSR (CNK). We propose that Step may be part of a larger signaling scaffold coordinating receptor tyrosine kinase-dependent MAPK activation.