Publications by authors named "Alain de Bruin"

110 Publications

Extracellular Vesicles: Novel Opportunities to Understand and Detect Neoplastic Diseases.

Vet Pathol 2021 Apr 5:300985821999328. Epub 2021 Apr 5.

8125Utrecht University, Utrecht, the Netherlands.

With a size range from 30 to 1000 nm, extracellular vesicles (EVs) are one of the smallest cell components able to transport biologically active molecules. They mediate intercellular communications and play a fundamental role in the maintenance of tissue homeostasis and pathogenesis in several types of diseases. In particular, EVs actively contribute to cancer initiation and progression, and there is emerging understanding of their role in creation of the metastatic niche. This fact underlies the recent exponential growth in EV research, which has improved our understanding of their specific roles in disease and their potential applications in diagnosis and therapy. EVs and their biomolecular cargo reflect the state of the diseased donor cells, and can be detected in body fluids and exploited as biomarkers in cancer and other diseases. Relatively few studies have been published on EVs in the veterinary field. This review provides an overview of the features and biology of EVs as well as recent developments in EV research including techniques for isolation and analysis, and will address the way in which the EVs released by diseased tissues can be studied and exploited in the field of veterinary pathology. Uniquely, this review emphasizes the important contribution that pathologists can make to the field of EV research: pathologists can help EV scientists in studying and confirming the role of EVs and their molecular cargo in diseased tissues and as biomarkers in liquid biopsies.
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http://dx.doi.org/10.1177/0300985821999328DOI Listing
April 2021

Corrigendum to "NF-κB p65 serine 467 phosphorylation sensitizes mice to weight gain and TNFα-or diet-induced inflammation" [Biochim. Biophys. Acta Mol. Cell Res., 1864 (2017): 1785-1798].

Biochim Biophys Acta Mol Cell Res 2021 May 11;1868(6):119008. Epub 2021 Mar 11.

Section of Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands. Electronic address:

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http://dx.doi.org/10.1016/j.bbamcr.2021.119008DOI Listing
May 2021

Acute systemic loss of Mad2 leads to intestinal atrophy in adult mice.

Sci Rep 2021 Jan 8;11(1):68. Epub 2021 Jan 8.

European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, 9713 AV, Groningen, The Netherlands.

Chromosomal instability (CIN) is a hallmark of cancer, leading to aneuploid cells. To study the role that CIN plays in tumor evolution, several mouse models have been engineered over the last 2 decades. These models have unequivocally shown that systemic high-grade CIN is embryonic lethal. We and others have previously shown that embryonic lethality can be circumvented by provoking CIN in a tissue-specific fashion. In this study, we provoke systemic high-grade CIN in adult mice as an alternative to circumvent embryonic lethality. For this, we disrupt the spindle assembly checkpoint (SAC) by alleviating Mad2 or truncating Mps1, both essential genes for SAC functioning, with or without p53 inactivation. We find that disruption of the SAC leads to rapid villous atrophy, atypia and apoptosis of the epithelia of the jejunum and ileum, substantial weight loss, and death within 2-3 weeks after the start of the CIN insult. Despite this severe intestinal phenotype, most other tissues are unaffected, except for minor abnormalities in spleen, presumably due to the lower proliferation rate in these tissues. We conclude that high-grade CIN in vivo in adult mice is most toxic to the high cell turnover intestinal epithelia.
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http://dx.doi.org/10.1038/s41598-020-80169-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7794249PMC
January 2021

Excessive E2F Transcription in Single Cancer Cells Precludes Transient Cell-Cycle Exit after DNA Damage.

Cell Rep 2020 Dec;33(9):108449

Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands. Electronic address:

E2F transcription factors control the expression of cell-cycle genes. Cancers often demonstrate enhanced E2F target gene expression, which can be explained by increased percentages of replicating cells. However, we demonstrate in human cancer biopsy specimens that individual neoplastic cells display abnormally high levels of E2F-dependent transcription. To mimic this situation, we delete the atypical E2F repressors (E2F7/8) or overexpress the E2F3 activator in untransformed cells. Cells with elevated E2F activity during S/G2 phase fail to exit the cell cycle after DNA damage and undergo mitosis. In contrast, wild-type cells complete S phase and then exit the cell cycle by activating the APC/C via repression of the E2F target Emi1. Many arrested wild-type cells eventually inactivate APC/C to execute a second round of DNA replication and mitosis, thereby becoming tetraploid. Cells with elevated E2F transcription fail to exit the cell cycle after DNA damage, which potentially causes genomic instability, promotes malignant progression, and reduces drug sensitivity.
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http://dx.doi.org/10.1016/j.celrep.2020.108449DOI Listing
December 2020

PIDDosome-induced p53-dependent ploidy restriction facilitates hepatocarcinogenesis.

EMBO Rep 2020 12 23;21(12):e50893. Epub 2020 Nov 23.

Institute of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.

Polyploidization frequently precedes tumorigenesis but also occurs during normal development in several tissues. Hepatocyte ploidy is controlled by the PIDDosome during development and regeneration. This multi-protein complex is activated by supernumerary centrosomes to induce p53 and restrict proliferation of polyploid cells, otherwise prone for chromosomal instability. PIDDosome deficiency in the liver results in drastically increased polyploidy. To investigate PIDDosome-induced p53-activation in the pathogenesis of liver cancer, we chemically induced hepatocellular carcinoma (HCC) in mice. Strikingly, PIDDosome deficiency reduced tumor number and burden, despite the inability to activate p53 in polyploid cells. Liver tumors arise primarily from cells with low ploidy, indicating an intrinsic pro-tumorigenic effect of PIDDosome-mediated ploidy restriction. These data suggest that hyperpolyploidization caused by PIDDosome deficiency protects from HCC. Moreover, high tumor cell density, as a surrogate marker of low ploidy, predicts poor survival of HCC patients receiving liver transplantation. Together, we show that the PIDDosome is a potential therapeutic target to manipulate hepatocyte polyploidization for HCC prevention and that tumor cell density may serve as a novel prognostic marker for recurrence-free survival in HCC patients.
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http://dx.doi.org/10.15252/embr.202050893DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7726793PMC
December 2020

The Beneficial Effects of Apical Sodium-Dependent Bile Acid Transporter Inactivation Depend on Dietary Fat Composition.

Mol Nutr Food Res 2020 Oct 20:e2000750. Epub 2020 Oct 20.

Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen, 9713 GZ, The Netherlands.

Scope: The apical sodium-dependent bile acid transporter (ASBT, SLC10A2) is important in the enterohepatic cycling of bile acids and thereby in the intestinal absorption of lipids. ASBT inhibition has been shown to improve aspects of the metabolic syndrome, but the underlying mechanisms have remained unclear. Here, the effect of ASBT inhibition on the uptake of specific fatty acids and its consequences for diet-induced obesity and non-alcoholic fatty liver disease (NAFLD) are investigated.

Methods: Intestinal fat absorption is determined in mice receiving an ASBT inhibitor and in Asbt mice. Metabolic disease development is determined in Asbt mice receiving a low-fat control diet (LFD) or high-fat diet (HFD) rich in saturated fatty acids (SFAs) or PUFAs.

Results: Both ASBT inhibition and Asbt gene inactivation reduce total fat absorption, particularly of SFAs. Asbt gene inactivation lowers bodyweight gain, improves insulin sensitivity, and decreases the NAFLD activity score upon feeding a HFD rich in SFAs, but not in PUFAs.

Conclusions: The beneficial metabolic effects of ASBT inactivation on diet-induced obesity depend on decreased intestinal absorption of SFAs, and thus on the dietary fatty acid composition. These findings highlight the importance of dietary fatty acid composition in the therapeutic effects of ASBT inhibition.
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http://dx.doi.org/10.1002/mnfr.202000750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7757219PMC
October 2020

Spontaneous liver disease in wild-type C57BL/6JOlaHsd mice fed semisynthetic diet.

PLoS One 2020 21;15(9):e0232069. Epub 2020 Sep 21.

Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Mouse models are frequently used to study mechanisms of human diseases. Recently, we observed a spontaneous bimodal variation in liver weight in C57BL/6JOlaHsd mice fed a semisynthetic diet. We now characterized the spontaneous variation in liver weight and its relationship with parameters of hepatic lipid and bile acid (BA) metabolism. In male C57BL/6JOlaHsd mice fed AIN-93G from birth to postnatal day (PN)70, we measured plasma BA, lipids, Very low-density lipoprotein (VLDL)-triglyceride (TG) secretion, and hepatic mRNA expression patterns. Mice were sacrificed at PN21, PN42, PN63 and PN70. Liver weight distribution was bimodal at PN70. Mice could be subdivided into two nonoverlapping groups based on liver weight: 0.6 SD 0.1 g (approximately one-third of mice, small liver; SL), and 1.0 SD 0.1 g (normal liver; NL; p<0.05). Liver histology showed a higher steatosis grade, inflammation score, more mitotic figures and more fibrosis in the SL versus the NL group. Plasma BA concentration was 14-fold higher in SL (p<0.001). VLDL-TG secretion rate was lower in SL mice, both absolutely (-66%, p<0.001) and upon correction for liver weight (-44%, p<0.001). Mice that would later have the SL-phenotype showed lower food efficiency ratios during PN21-28, suggesting the cause of the SL phenotype is present at weaning (PN21). Our data show that approximately one-third of C57BL/6JOlaHsd mice fed semisynthetic diet develop spontaneous liver disease with aberrant histology and parameters of hepatic lipid, bile acid and lipoprotein metabolism. Study designs involving this mouse strain on semisynthetic diets need to take the SL phenotype into account. Plasma lipids may serve as markers for the identification of the SL phenotype.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0232069PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7505464PMC
October 2020

Impaired Hepatic Vitamin A Metabolism in NAFLD Mice Leading to Vitamin A Accumulation in Hepatocytes.

Cell Mol Gastroenterol Hepatol 2021 19;11(1):309-325.e3. Epub 2020 Jul 19.

Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; Laboratory Medicine, Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands. Electronic address:

Background & Aims: Systemic retinol (vitamin A) homeostasis is controlled by the liver, involving close collaboration between hepatocytes and hepatic stellate cells (HSCs). Genetic variants in retinol metabolism (PNPLA3 and HSD17B13) are associated with non-alcoholic fatty liver disease (NAFLD) and disease progression. Still, little mechanistic details are known about hepatic vitamin A metabolism in NAFLD, which may affect carbohydrate and lipid metabolism, inflammation, oxidative stress and the development of fibrosis and cancer, e.g. all risk factors of NAFLD.

Methods: Here, we analyzed vitamin A metabolism in 2 mouse models of NAFLD; mice fed a high-fat, high-cholesterol (HFC) diet and Leptin mutant (ob/ob) mice.

Results: Hepatic retinol and retinol binding protein 4 (RBP4) levels were significantly reduced in both mouse models of NAFLD. In contrast, hepatic retinyl palmitate levels (the vitamin A storage form) were significantly elevated in these mice. Transcriptome analysis revealed a hyperdynamic state of hepatic vitamin A metabolism, with enhanced retinol storage and metabolism (upregulated Lrat, Dgat1, Pnpla3, Raldh's and RAR/RXR-target genes) in fatty livers, in conjunction with induced hepatic inflammation (upregulated Cd68, Tnfα, Nos2, Il1β, Il-6) and fibrosis (upregulated Col1a1, Acta2, Tgfβ, Timp1). Autofluorescence analyses revealed prominent vitamin A accumulation in hepatocytes rather than HSC in HFC-fed mice. Palmitic acid exposure increased Lrat mRNA levels in primary rat hepatocytes and promoted retinyl palmitate accumulation when co-treated with retinol, which was not detected for similarly-treated primary rat HSCs.

Conclusion: NAFLD leads to cell type-specific rearrangements in retinol metabolism leading to vitamin A accumulation in hepatocytes. This may promote disease progression and/or affect therapeutic approaches targeting nuclear receptors.
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http://dx.doi.org/10.1016/j.jcmgh.2020.07.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7768561PMC
July 2020

Loss of c-Jun N-terminal Kinase 1 and 2 Function in Liver Epithelial Cells Triggers Biliary Hyperproliferation Resembling Cholangiocarcinoma.

Hepatol Commun 2020 Jun 16;4(6):834-851. Epub 2020 Apr 16.

Department of Internal Medicine III University Hospital RWTH Aachen Aachen Germany.

Targeted inhibition of the c-Jun N-terminal kinases (JNKs) has shown therapeutic potential in intrahepatic cholangiocarcinoma (CCA)-related tumorigenesis. However, the cell-type-specific role and mechanisms triggered by JNK in liver parenchymal cells during CCA remain largely unknown. Here, we aimed to investigate the relevance of JNK1 and JNK2 function in hepatocytes in two different models of experimental carcinogenesis, the dethylnitrosamine (DEN) model and in nuclear factor kappa B essential modulator (NEMO) mice, focusing on liver damage, cell death, compensatory proliferation, fibrogenesis, and tumor development. Moreover, regulation of essential genes was assessed by reverse transcription polymerase chain reaction, immunoblottings, and immunostainings. Additionally, specific inhibition in hepatocytes of NEMO/JNK1 mice was performed using small interfering (si) RNA (si) nanodelivery. Finally, active signaling pathways were blocked using specific inhibitors. Compound deletion of and in hepatocytes diminished hepatocellular carcinoma (HCC) in both the DEN model and in NEMO mice but in contrast caused massive proliferation of the biliary ducts. Indeed, deficiency in hepatocytes of NEMO (NEMO/JNK) animals caused elevated fibrosis, increased apoptosis, increased compensatory proliferation, and elevated inflammatory cytokines expression but reduced HCC. Furthermore, si treatment in NEMO/JNK1 mice recapitulated the phenotype of NEMO/JNK mice. Next, we sought to investigate the impact of molecular pathways in response to compound JNK deficiency in NEMO mice. We found that NEMO/JNK livers exhibited overexpression of the interleukin-6/signal transducer and activator of transcription 3 pathway in addition to epidermal growth factor receptor (EGFR)-rapidly accelerated fibrosarcoma (Raf)-mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) cascade. The functional relevance was tested by administering lapatinib, which is a dual tyrosine kinase inhibitor of erythroblastic oncogene B-2 (ErbB2) and EGFR signaling, to NEMO/JNK mice. Lapatinib effectively inhibited cystogenesis, improved transaminases, and effectively blocked EGFR-Raf-MEK-ERK signaling. : We define a novel function of JNK1/2 in cholangiocyte hyperproliferation. This opens new therapeutic avenues devised to inhibit pathways of cholangiocarcinogenesis.
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http://dx.doi.org/10.1002/hep4.1495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7262317PMC
June 2020

and act redundantly for ovarian-to-testicular fate reprogramming in the absence of in mouse sex reversals.

Elife 2020 05 26;9. Epub 2020 May 26.

Université Côte d'Azur, CNRS, Inserm, iBV, Nice, France.

In mammals, testicular differentiation is initiated by transcription factors SRY and SOX9 in XY gonads, and ovarian differentiation involves R-spondin1 (RSPO1) mediated activation of WNT/β-catenin signaling in XX gonads. Accordingly, the absence of in XX humans and mice leads to testicular differentiation and female-to-male sex reversal in a manner that does not require or in mice. Here we show that an alternate testis-differentiating factor exists and that this factor is . Specifically, genetic ablation of and prevents ovarian-to-testicular reprogramming observed in XX loss-of-function mice. Consequently, triple mutant gonads developed as atrophied ovaries. Thus, SOX8 alone can compensate for the loss of SOX9 for Sertoli cell differentiation during female-to-male sex reversal.
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http://dx.doi.org/10.7554/eLife.53972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7250573PMC
May 2020

L-Selectin/CD62L is a Key Driver of Non-Alcoholic Steatohepatitis in Mice and Men.

Cells 2020 04 29;9(5). Epub 2020 Apr 29.

Department of Internal Medicine III, University Hospital, 52074 RWTH Aachen, Germany.

CD62L (L-Selectin) dependent lymphocyte infiltration is known to induce inflammatory bowel disease (IBD), while its function in the liver, especially in non-alcoholic steatohepatitis (NASH), remains unclear. We here investigated the functional role of CD62L in NASH in humans as well as in two mouse models of steatohepatitis. Hepatic expression of a soluble form of CD62L (sCD62L) was measured in patients with steatosis and NASH. Furthermore, CD62L mice were fed with a methionine and choline deficient (MCD) diet for 4 weeks or with a high fat diet (HFD) for 24 weeks. Patients with NASH displayed increased serum levels of sCD62L. Hepatic CD62L expression was higher in patients with steatosis and increased dramatically in NASH patients. Interestingly, compared to wild type (WT) mice, MCD and HFD-treated CD62L mice were protected from diet-induced steatohepatitis. This was reflected by less fat accumulation in hepatocytes and a dampened manifestation of the metabolic syndrome with an improved insulin resistance and decreased cholesterol and triglyceride levels. Consistent with ameliorated disease, CD62L animals exhibited an enhanced hepatic infiltration of Treg cells and a strong activation of an anti-oxidative stress response. Those changes finally resulted in less fibrosis in CD62L mice. Additionally, this effect could be reproduced in a therapeutic setting by administrating an anti-CD62L blocking antibody. CD62L expression in humans and mice correlates with disease activity of steatohepatitis. CD62L knockout and anti-CD62L-treated mice are protected from diet-induced steatohepatitis suggesting that CD62L is a promising target for therapeutic interventions in NASH.
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http://dx.doi.org/10.3390/cells9051106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7290433PMC
April 2020

E2F7 Is a Potent Inhibitor of Liver Tumor Growth in Adult Mice.

Hepatology 2021 Jan;73(1):303-317

Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.

Background And Aims: Up-regulation of the E2F-dependent transcriptional network has been identified in nearly every human malignancy and is an important driver of tumorigenesis. Two members of the E2F family, E2F7 and E2F8, are potent repressors of E2F-dependent transcription. They are atypical in that they do not bind to dimerization partner proteins and are not controlled by retinoblastoma protein. The physiological relevance of E2F7 and E2F8 remains incompletely understood, largely because tools to manipulate their activity in vivo have been lacking.

Approach And Results: Here, we generated transgenic mice with doxycycline-controlled transcriptional activation of E2f7 and E2f8 and induced their expression during postnatal development, in adulthood, and in the context of cancer. Systemic induction of E2f7 and, to lesser extent, E2f8 transgenes in juvenile mice impaired cell proliferation, caused replication stress, DNA damage, and apoptosis, and inhibited animal growth. In adult mice, however, E2F7 and E2F8 induction was well tolerated, yet profoundly interfered with DNA replication, DNA integrity, and cell proliferation in diethylnitrosamine-induced liver tumors.

Conclusion: Collectively, our findings demonstrate that atypical E2Fs can override cell-cycle entry and progression governed by other E2F family members and suggest that this property can be exploited to inhibit proliferation of neoplastic hepatocytes when growth and development have subsided during adulthood.
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http://dx.doi.org/10.1002/hep.31259DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898887PMC
January 2021

Local endothelial DNA repair deficiency causes aging-resembling endothelial-specific dysfunction.

Clin Sci (Lond) 2020 04;134(7):727-746

Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.

We previously identified genomic instability as a causative factor for vascular aging. In the present study, we determined which vascular aging outcomes are due to local endothelial DNA damage, which was accomplished by genetic removal of ERCC1 (excision repair cross-complementation group 1) DNA repair in mice (EC-knockout (EC-KO) mice). EC-KO showed a progressive decrease in microvascular dilation of the skin, increased microvascular leakage in the kidney, decreased lung perfusion, and increased aortic stiffness compared with wild-type (WT). EC-KO showed expression of DNA damage and potential senescence marker p21 exclusively in the endothelium, as demonstrated in aorta. Also the kidney showed p21-positive cells. Vasodilator responses measured in organ baths were decreased in aorta, iliac and coronary artery EC-KO compared with WT, of which coronary artery was the earliest to be affected. Nitric oxide-mediated endothelium-dependent vasodilation was abolished in aorta and coronary artery, whereas endothelium-derived hyperpolarization and responses to exogenous nitric oxide (NO) were intact. EC-KO showed increased superoxide production compared with WT, as measured in lung tissue, rich in endothelial cells (ECs). Arterial systolic blood pressure (BP) was increased at 3 months, but normal at 5 months, at which age cardiac output (CO) was decreased. Since no further signs of cardiac dysfunction were detected, this decrease might be an adaptation to prevent an increase in BP. In summary, a selective DNA repair defect in the endothelium produces features of age-related endothelial dysfunction, largely attributed to loss of endothelium-derived NO. Increased superoxide generation might contribute to the observed changes affecting end organ perfusion, as demonstrated in kidney and lung.
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http://dx.doi.org/10.1042/CS20190124DOI Listing
April 2020

Hepatic Carbohydrate Response Element Binding Protein Activation Limits Nonalcoholic Fatty Liver Disease Development in a Mouse Model for Glycogen Storage Disease Type 1a.

Hepatology 2020 11 30;72(5):1638-1653. Epub 2020 Oct 30.

Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.

Background And Aims: Glycogen storage disease (GSD) type 1a is an inborn error of metabolism caused by defective glucose-6-phosphatase catalytic subunit (G6PC) activity. Patients with GSD 1a exhibit severe hepatomegaly due to glycogen and triglyceride (TG) accumulation in the liver. We have shown that the activity of carbohydrate response element binding protein (ChREBP), a key regulator of glycolysis and de novo lipogenesis, is increased in GSD 1a. In the current study, we assessed the contribution of ChREBP to nonalcoholic fatty liver disease (NAFLD) development in a mouse model for hepatic GSD 1a.

Approach And Results: Liver-specific G6pc-knockout (L-G6pc ) mice were treated with adeno-associated viruses (AAVs) 2 or 8 directed against short hairpin ChREBP to normalize hepatic ChREBP activity to levels observed in wild-type mice receiving AAV8-scrambled short hairpin RNA (shSCR). Hepatic ChREBP knockdown markedly increased liver weight and hepatocyte size in L-G6pc mice. This was associated with hepatic accumulation of G6P, glycogen, and lipids, whereas the expression of glycolytic and lipogenic genes was reduced. Enzyme activities, flux measurements, hepatic metabolite analysis and very low density lipoprotein (VLDL)-TG secretion assays revealed that hepatic ChREBP knockdown reduced downstream glycolysis and de novo lipogenesis but also strongly suppressed hepatic VLDL lipidation, hence promoting the storage of "old fat." Interestingly, enhanced VLDL-TG secretion in shSCR-treated L-G6pc mice associated with a ChREBP-dependent induction of the VLDL lipidation proteins microsomal TG transfer protein and transmembrane 6 superfamily member 2 (TM6SF2), the latter being confirmed by ChIP-qPCR.

Conclusions: Attenuation of hepatic ChREBP induction in GSD 1a liver aggravates hepatomegaly because of further accumulation of glycogen and lipids as a result of reduced glycolysis and suppressed VLDL-TG secretion. TM6SF2, critical for VLDL formation, was identified as a ChREBP target in mouse liver. Altogether, our data show that enhanced ChREBP activity limits NAFLD development in GSD 1a by balancing hepatic TG production and secretion.
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http://dx.doi.org/10.1002/hep.31198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7702155PMC
November 2020

OTULIN Prevents Liver Inflammation and Hepatocellular Carcinoma by Inhibiting FADD- and RIPK1 Kinase-Mediated Hepatocyte Apoptosis.

Cell Rep 2020 02;30(7):2237-2247.e6

VIB Center for Inflammation Research, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9052 Ghent, Belgium. Electronic address:

Inflammatory signaling pathways are tightly regulated to avoid chronic inflammation and the development of disease. OTULIN is a deubiquitinating enzyme that controls inflammation by cleaving linear ubiquitin chains generated by the linear ubiquitin chain assembly complex. Here, we show that ablation of OTULIN in liver parenchymal cells in mice causes severe liver disease which is characterized by liver inflammation, hepatocyte apoptosis, and compensatory hepatocyte proliferation, leading to steatohepatitis, fibrosis, and hepatocellular carcinoma (HCC). Genetic ablation of Fas-associated death domain (FADD) completely rescues and knockin expression of kinase inactive receptor-interacting protein kinase 1 (RIPK1) significantly protects mice from developing liver disease, demonstrating that apoptosis of OTULIN-deficient hepatocytes triggers disease pathogenesis in this model. Finally, we demonstrate that type I interferons contribute to disease in hepatocyte-specific OTULIN-deficient mice. Our study reveals the critical importance of OTULIN in protecting hepatocytes from death, thereby preventing the development of chronic liver inflammation and HCC.
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http://dx.doi.org/10.1016/j.celrep.2020.01.028DOI Listing
February 2020

TEG011 persistence averts extramedullary tumor growth without exerting off-target toxicity against healthy tissues in a humanized HLA-A*24:02 transgenic mice.

J Leukoc Biol 2020 06 5;107(6):1069-1079. Epub 2020 Feb 5.

Department of Hematology and Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.

γδT cells play an important role in cancer immunosurveillance and are able to distinguish malignant cells from their healthy counterparts via their γδTCR. This characteristic makes γδT cells an attractive candidate for therapeutic application in cancer immunotherapy. Previously, we have identified a novel CD8α-dependent tumor-specific allo-HLA-A*24:02-restricted Vγ5Vδ1TCR with potential therapeutic value when used to engineer αβT cells from HLA-A*24:02 harboring individuals. αβT cells engineered to express this defined Vγ5Vδ1TCR (TEG011) have been suggested to recognize spatial changes in HLA-A*24:02 present selectively on tumor cells but not their healthy counterparts. However, in vivo efficacy and toxicity studies of TEG011 are still limited. Therefore, we extend the efficacy and toxicity studies as well as the dynamics of TEG011 in vivo in a humanized HLA-A*24:02 transgenic NSG (NSG-A24:02) mouse model to allow the preparation of a first-in-men clinical safety package for adoptive transfer of TEG011. Mice treated with TEG011 did not exhibit any graft-versus-host disease-like symptoms and extensive analysis of pathologic changes in NSG-A24:02 mice did not show any off-target toxicity of TEG011. However, loss of persistence of TEG011 in tumor-bearing mice was associated with the outgrowth of extramedullary tumor masses as also observed for mock-treated mice. In conclusion, TEG011 is well tolerated without harming HLA-A*24:02 expressing healthy tissues, and TEG011 persistence seems to be crucial for long-term tumor control in vivo.
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http://dx.doi.org/10.1002/JLB.5MA0120-228RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7722393PMC
June 2020

E2F-Family Members Engage the PIDDosome to Limit Hepatocyte Ploidy in Liver Development and Regeneration.

Dev Cell 2020 02 23;52(3):335-349.e7. Epub 2020 Jan 23.

Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, 1090 Vienna, Austria; CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria. Electronic address:

E2F transcription factors control the cytokinesis machinery and thereby ploidy in hepatocytes. If or how these proteins limit proliferation of polyploid cells with extra centrosomes remains unknown. Here, we show that the PIDDosome, a signaling platform essential for caspase-2-activation, limits hepatocyte ploidy and is instructed by the E2F network to control p53 in the developing as well as regenerating liver. Casp2 and Pidd1 act as direct transcriptional targets of E2F1 and its antagonists, E2F7 and E2F8, that together co-regulate PIDDosome expression during juvenile liver growth and regeneration. Of note, whereas hepatocyte aneuploidy correlates with the basal ploidy state, the degree of aneuploidy itself is not limited by PIDDosome-dependent p53 activation. Finally, we provide evidence that the same signaling network is engaged to control ploidy in the human liver after resection. Our study defines the PIDDosome as a primary target to manipulate hepatocyte ploidy and proliferation rates in the regenerating liver.
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http://dx.doi.org/10.1016/j.devcel.2019.12.016DOI Listing
February 2020

Transcriptome analysis suggests a compensatory role of the cofactors coenzyme A and NAD in medium-chain acyl-CoA dehydrogenase knockout mice.

Sci Rep 2019 10 10;9(1):14539. Epub 2019 Oct 10.

Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

During fasting, mitochondrial fatty-acid β-oxidation (mFAO) is essential for the generation of glucose by the liver. Children with a loss-of-function deficiency in the mFAO enzyme medium-chain acyl-Coenzyme A dehydrogenase (MCAD) are at serious risk of life-threatening low blood glucose levels during fasting in combination with intercurrent disease. However, a subset of these children remains asymptomatic throughout life. In MCAD-deficient (MCAD-KO) mice, glucose levels are similar to those of wild-type (WT) mice, even during fasting. We investigated if metabolic adaptations in the liver may underlie the robustness of this KO mouse. WT and KO mice were given a high- or low-fat diet and subsequently fasted. We analyzed histology, mitochondrial function, targeted mitochondrial proteomics, and transcriptome in liver tissue. Loss of MCAD led to a decreased capacity to oxidize octanoyl-CoA. This was not compensated for by altered protein levels of the short- and long-chain isoenzymes SCAD and LCAD. In the transcriptome, we identified subtle adaptations in the expression of genes encoding enzymes catalyzing CoA- and NAD(P)(H)-involving reactions and of genes involved in detoxification mechanisms. We discuss how these processes may contribute to robustness in MCAD-KO mice and potentially also in asymptomatic human subjects with a complete loss of MCAD activity.
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http://dx.doi.org/10.1038/s41598-019-50758-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6787083PMC
October 2019

Safety evaluation of conditionally immortalized cells for renal replacement therapy.

Oncotarget 2019 Sep 3;10(51):5332-5348. Epub 2019 Sep 3.

Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.

End-stage kidney disease represents irreversible kidney failure. Dialysis and transplantation, two main treatment options currently available, present various drawbacks and complications. Innovative cell-based therapies, such as a bioartificial kidney, have not reached the clinic yet, mostly due to safety and/or functional issues. Here, we assessed the safety of conditionally immortalized proximal tubule epithelial cells (ciPTECs) for bioartificial kidney application, by using assays and athymic nude rats. We demonstrate that these cells do not possess key properties of oncogenically transformed cells, including anchorage-independent growth, lack of contact inhibition and apoptosis-resistance. In late-passage cells we did observe complex chromosomal abnormalities favoring near-tetraploidy, indicating chromosomal instability. However, time-lapse imaging of ciPTEC-OAT1, confined to a 3D extracellular matrix (ECM)-based environment, revealed that the cells were largely non-invasive. Furthermore, we determined the viral integration sites of SV40 Large T antigen (SV40T), human telomerase (hTERT) and OAT1 (SLC22A6), the transgenes used for immortalization and cell function enhancement. All integrations sites were found to be located in the intronic regions of endogenous genes. Among these genes, early endosome antigen 1 (EEA1) involved in endocytosis, and BCL2 Like 1 (BCL2L1) known for its role in regulating apoptosis, were identified. Nevertheless, both gene products appeared to be functionally intact. Finally, after subcutaneous injection in athymic nude rats we show that ciPTEC-OAT1 lack tumorigenic and oncogenic effects , confirming the findings. Taken together, this study lays an important foundation towards bioartificial kidney (BAK) development by confirming the safety of the cell line intended for incorporation.
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http://dx.doi.org/10.18632/oncotarget.27152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6731099PMC
September 2019

Cyclin F-dependent degradation of E2F7 is critical for DNA repair and G2-phase progression.

EMBO J 2019 10 2;38(20):e101430. Epub 2019 Sep 2.

Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.

E2F7 and E2F8 act as tumor suppressors via transcriptional repression of genes involved in S-phase entry and progression. Previously, we demonstrated that these atypical E2Fs are degraded by APC/C during G1 phase of the cell cycle. However, the mechanism driving the downregulation of atypical E2Fs during G2 phase is unknown. Here, we show that E2F7 is targeted for degradation by the E3 ubiquitin ligase SCF during G2. Cyclin F binds via its cyclin domain to a conserved C-terminal CY motif on E2F7. An E2F7 mutant unable to interact with SCF remains stable during G2. Furthermore, SCF can also interact and induce degradation of E2F8. However, this does not require the cyclin domain of SCF nor the CY motifs in the C-terminus of E2F8, implying a different regulatory mechanism than for E2F7. Importantly, depletion of cyclin F causes an atypical-E2F-dependent delay of the G2/M transition, accompanied by reduced expression of E2F target genes involved in DNA repair. Live cell imaging of DNA damage revealed that cyclin F-dependent regulation of atypical E2Fs is critical for efficient DNA repair and cell cycle progression.
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http://dx.doi.org/10.15252/embj.2018101430DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6792010PMC
October 2019

Programming effects of an early life diet containing large phospholipid-coated lipid globules are transient under continuous exposure to a high-fat diet.

Br J Nutr 2019 12;122(12):1321-1328

Department of Pediatrics, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands.

Breast-feeding is associated with a lower risk of developing obesity during childhood and adulthood compared with feeding infant milk formula (IMF). Previous studies have shown that an experimental IMF (eIMF; comprising Nuturis®) programmed mouse pups for a lower body weight and fat mass gain in adulthood when challenged with a high-fat diet (HFD) compared with a control IMF (cIMF). Nuturis has a lipid composition and structure more similar to breast milk. Here, the long-term effects were tested of a similar eIMF, but with an adapted lipid composition and a cIMF, on body weight, glucose homoeostasis, liver and adipose tissue. Nutrient composition was similar for the eIMF and cIMF; the lipid fractions comprised approximately 50 % milk fat. C57BL/6JOlaHsd mice were fed cIMF or eIMF from postnatal day (PN) 16-42 followed by an HFD until PN168. Feeding eIMF v. cIMF in early life resulted in a lower body weight (-9 %) and body fat deposition (-14 %) in adulthood (PN105). The effect appeared transient, as from PN126 onwards, after 12 weeks' HFD, eIMF-fed mice caught up on controls and body and fat weights became comparable between groups. Glucose and energy metabolism were similar between groups. At dissection (PN168), eIMF-fed mice showed larger (+27 %) epididymal fat depots and a lower (-26 %) liver weight without clear morphological aberrations. Our data suggest the size and coating but not the lipid composition of IMF fat globules underlie the programming effect observed. Prolonged exposure to an HFD challenge partly overrules the programming effect of early diet.
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http://dx.doi.org/10.1017/S0007114519002083DOI Listing
December 2019

Molecular pathways of senescence regulate placental structure and function.

EMBO J 2019 09 19;38(18):e100849. Epub 2019 Aug 19.

Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel.

The placenta is an autonomous organ that maintains fetal growth and development. Its multinucleated syncytiotrophoblast layer, providing fetal nourishment during gestation, exhibits characteristics of cellular senescence. We show that in human placentas from pregnancies with intrauterine growth restriction, these characteristics are decreased. To elucidate the functions of pathways regulating senescence in syncytiotrophoblast, we used dynamic contrast-enhanced MRI in mice with attenuated senescence programs. This approach revealed an altered dynamics in placentas of p53 , Cdkn2a , and Cdkn2a ;p53 mice, accompanied by histopathological changes in placental labyrinths. Human primary syncytiotrophoblast upregulated senescence markers and molecular pathways associated with cell-cycle inhibition and senescence-associated secretory phenotype. The pathways and components of the secretory phenotype were compromised in mouse placentas with attenuated senescence and in human placentas from pregnancies with intrauterine growth restriction. We propose that molecular mediators of senescence regulate placental structure and function, through both cell-autonomous and non-autonomous mechanisms.
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http://dx.doi.org/10.15252/embj.2018100849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6745498PMC
September 2019

The Influence of Different Fat Sources on Steatohepatitis and Fibrosis Development in the Western Diet Mouse Model of Non-alcoholic Steatohepatitis (NASH).

Front Physiol 2019 25;10:770. Epub 2019 Jun 25.

Department of Internal Medicine III, University Hospital RWTH Aachen, Aachen, Germany.

Non-alcoholic steatohepatitis (NASH) is the leading cause of chronic liver injury and the third most common reason for liver transplantations in Western countries. It is unclear so far how different fat sources in Western diets (WD) influence the development of NASH. Our study investigates the impact of non-trans fat (NTF) and corn oil (Corn) as fat source in a WD mouse model of steatohepatitis on disease development and progression. C57BL/6J wildtype (WT) mice were fed "standard" WD (WD-Std), WD-NTF or WD-Corn for 24 weeks. WT animals treated with WD-NTF exhibit distinct features of the metabolic syndrome compared to WD-Std and WD-Corn. This becomes evident by a worsened insulin resistance and elevated serum ALT, cholesterol and triglyceride (TG) levels compared to WD-Corn. Animals fed WD-Corn on the contrary tend to a weakened disease progression in the described parameters. After 24 weeks feeding with WD-NTF and WD-Std, WD-Corn lead to a comparable steatohepatitis initiation by histomorphological changes and immune cell infiltration compared to WD-Std. Immune cell infiltration results in a significant increase in mRNA expression of the pro-inflammatory cytokines IL-6 and TNF-α, which is more pronounced in WD-NTF compared to WD-Std and WD-Corn. Interestingly the fat source has no impact on the composition of accumulating fat within liver tissue as determined by matrix-assisted laser desorption/ionization mass spectrometry imaging of multiple lipid classes. The described effects of different fat sources on the development of steatohepatitis finally resulted in variations in fibrosis development. Animals treated with WD-NTF displayed massive collagen accumulation, whereas WD-Corn even seems to protect from extracellular matrix deposition. Noteworthy, WD-Corn provokes massive histomorphological modifications in epididymal white adipose tissue (eWAT) and severe accumulation of extracellular matrix which are not apparent in WD-Std and WD-NTF treatment. Different fat sources in WD-Std contribute to strong steatohepatitis development in WT mice after 24 weeks treatment. Surprisingly, corn oil provokes histomorphological changes in eWAT tissue. Accordingly, both WD-NTF and WD-Corn appear suitable as alternative dietary treatment to replace "standard" WD-Std as a diet mouse model of steatohepatitis whereas WD-Corn leads to strong changes in eWAT morphology.
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http://dx.doi.org/10.3389/fphys.2019.00770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6603084PMC
June 2019

[Rubber granules on synthetic turf pitches: safe or not safe for children?]

Ned Tijdschr Geneeskd 2019 07 5;163. Epub 2019 Jul 5.

Universitair Medisch Centrum Groningen-Rijksuniversiteit Groningen, afd. Kindergeneeskunde, Groningen.

Rubber granules from old car tyres used in synthetic turf pitches contain a significant number of carcinogenic and endocrine-disrupting chemicals. In 2017 the Dutch National Institute for Public Health and the Environment (RIVM) and the European Chemical Agency (ECHA) concluded that the risks for children are negligible. However, their reports contain some scientific inaccuracies and omissions which may have led them to underestimate the risks for children. It is therefore premature to conclude that it is safe for children to play on synthetic turf pitches with rubber granules. It is now primarily up to the parents to decide whether or not playing sports is acceptable in these circumstances. The Dutch government should, in accordance with ECHA recommendations, advise parents that their children ought to avoid hand-and-mouth contact with these granules as much as possible.
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July 2019

C/EBPβ-LIP induces cancer-type metabolic reprogramming by regulating the /LIN28B circuit in mice.

Commun Biol 2019 14;2:208. Epub 2019 Jun 14.

1European Research Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, University of Groningen, 9700 AD Groningen, The Netherlands.

The transcription factors LAP1, LAP2 and LIP are derived from the -mRNA through the use of alternative start codons. High LIP expression has been associated with human cancer and increased cancer incidence in mice. However, how LIP contributes to cellular transformation is poorly understood. Here we present that LIP induces aerobic glycolysis and mitochondrial respiration reminiscent of cancer metabolism. We show that LIP-induced metabolic programming is dependent on the RNA-binding protein LIN28B, a translational regulator of glycolytic and mitochondrial enzymes with known oncogenic function. LIP activates LIN28B through repression of the microRNA family that targets the -mRNA. Transgenic mice overexpressing LIP have reduced levels of and increased LIN28B expression, which is associated with metabolic reprogramming as shown in primary bone marrow cells, and with hyperplasia in the skin. This study establishes LIP as an inducer of cancer-type metabolic reprogramming and as a regulator of the /LIN28B regulatory circuit.
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http://dx.doi.org/10.1038/s42003-019-0461-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572810PMC
May 2020

Ccne1 Overexpression Causes Chromosome Instability in Liver Cells and Liver Tumor Development in Mice.

Gastroenterology 2019 07 13;157(1):210-226.e12. Epub 2019 Mar 13.

Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota; Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address:

Background & Aims: The CCNE1 locus, which encodes cyclin E1, is amplified in many types of cancer cells and is activated in hepatocellular carcinomas (HCCs) from patients infected with hepatitis B virus or adeno-associated virus type 2, due to integration of the virus nearby. We investigated cell-cycle and oncogenic effects of cyclin E1 overexpression in tissues of mice.

Methods: We generated mice with doxycycline-inducible expression of Ccne1 (Ccne1 mice) and activated overexpression of cyclin E1 from age 3 weeks onward. At 14 months of age, livers were collected from mice that overexpress cyclin E1 and nontransgenic mice (controls) and analyzed for tumor burden and by histology. Mouse embryonic fibroblasts (MEFs) and hepatocytes from Ccne1 and control mice were analyzed to determine the extent to which cyclin E1 overexpression perturbs S-phase entry, DNA replication, and numbers and structures of chromosomes. Tissues from 4-month-old Ccne1 and control mice (at that age were free of tumors) were analyzed for chromosome alterations, to investigate the mechanisms by which cyclin E1 predisposes hepatocytes to transformation.

Results: Ccne1 mice developed more hepatocellular adenomas and HCCs than control mice. Tumors developed only in livers of Ccne1 mice, despite high levels of cyclin E1 in other tissues. Ccne1 MEFs had defects that promoted chromosome missegregation and aneuploidy, including incomplete replication of DNA, centrosome amplification, and formation of nonperpendicular mitotic spindles. Whereas Ccne1 mice accumulated near-diploid aneuploid cells in multiple tissues and organs, polyploidization was observed only in hepatocytes, with losses and gains of whole chromosomes, DNA damage, and oxidative stress.

Conclusions: Livers, but not other tissues of mice with inducible overexpression of cyclin E1, develop tumors. More hepatocytes from the cyclin E1-overexpressing mice were polyploid than from control mice, and had losses or gains of whole chromosomes, DNA damage, and oxidative stress; all of these have been observed in human HCC cells. The increased risk of HCC in patients with hepatitis B virus or adeno-associated virus type 2 infection might involve activation of cyclin E1 and its effects on chromosomes and genomes of liver cells.
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http://dx.doi.org/10.1053/j.gastro.2019.03.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800187PMC
July 2019

Evaluating in vivo efficacy - toxicity profile of TEG001 in humanized mice xenografts against primary human AML disease and healthy hematopoietic cells.

J Immunother Cancer 2019 03 12;7(1):69. Epub 2019 Mar 12.

Department of Hematology and Laboratory of Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.

Background: γ9δ2T cells, which express Vγ9 and Vδ2 chains of the T cell receptor (TCR), mediate cancer immune surveillance by sensing early metabolic changes in malignant leukemic blast and not their healthy hematopoietic stem counterparts via the γ9δ2TCR targeting joined conformational and spatial changes of CD277 at the cell membrane (CD277J). This concept led to the development of next generation CAR-T cells, so-called TEGs: αβT cells Engineered to express a defined γδTCR. The high affinity γ9δ2TCR clone 5 has recently been selected within the TEG format as a clinical candidate (TEG001). However, exploring safety and efficacy against a target, which reflects an early metabolic change in tumor cells, remains challenging given the lack of appropriate tools. Therefore, we tested whether TEG001 is able to eliminate established leukemia in a primary disease model, without harming other parts of the healthy hematopoiesis in vivo.

Methods: Separate sets of NSG mice were respectively injected with primary human acute myeloid leukemia (AML) blasts and cord blood-derived human progenitor cells from healthy donors. These mice were then treated with TEG001 and mock cells. Tumor burden and human cells engraftment were measured in peripheral blood and followed up over time by quantifying for absolute cell number by flow cytometry. Statistical analysis was performed using non-parametric 2-tailed Mann-Whitney t-test.

Results: We successfully engrafted primary AML blasts and healthy hematopoietic cells after 6-8 weeks. Here we report that metabolic cancer targeting through TEG001 eradicated established primary leukemic blasts in vivo, while healthy hematopoietic compartments derived from human cord-blood remained unharmed in spite of TEGs persistence up to 50 days after infusion. No additional signs of off-target toxicity were observed in any other tissues.

Conclusion: Within the limitations of humanized PD-X models, targeting CD277J by TEG001 is safe and efficient. Therefore, we have initiated clinical testing of TEG001 in a phase I first-in-human clinical trial (NTR6541; date of registration 25 July 2017).
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http://dx.doi.org/10.1186/s40425-019-0558-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6419469PMC
March 2019

LED-phototherapy does not induce oxidative DNA damage in hyperbilirubinemic Gunn rats.

Pediatr Res 2019 06 9;85(7):1041-1047. Epub 2019 Mar 9.

Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Background: Phototherapy (PT) is the standard treatment of neonatal unconjugated hyperbilirubinemia. Fluorescent tube (FT)-emitted PT light is known to induce oxidative DNA damage in neonates. Nowadays, however, FTs have largely been replaced by light-emitting diodes (LEDs) for delivering PT. Until now, it is unknown whether LED-PT causes oxidative DNA damage. We aim to determine whether LED-PT induces oxidative DNA damage in hyperbilirubinemic rats.

Methods: Adult Gunn rats, with genetically unconjugated hyperbilirubinemia, received LED-PT in the clinically relevant doses of 10 or 30 µW/cm/nm. Urine was collected at 0, 24, and 48 h of PT. A group of young Gunn rats received intensive LED-PT of 100 µW/cm/nm for 24 h. Urine was collected every 8 h and analyzed for the levels of oxidative DNA damage marker 8-hydroxy-2'deoxyguanosine (8-OHdG) and creatinine. DNA damage was evaluated by immunohistochemistry (γH2AX) of skin and spleen samples.

Results: LED-PT of 10 and 30 µW/cm/nm did not affect urinary concentrations of 8-OHdG and creatinine or the 8-OHdG/creatinine ratio. Likewise, intensive LED-PT did not affect the 8-OHdG/creatinine ratio or the number of γH2AX-positive cells in the skin or spleen.

Conclusions: Our results show that LED-PT does not induce oxidative DNA damage in hyperbilirubinemic Gunn rats either at clinically relevant or intensive dosages.
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http://dx.doi.org/10.1038/s41390-019-0367-yDOI Listing
June 2019

MyD88-dependent signaling in non-parenchymal cells promotes liver carcinogenesis.

Carcinogenesis 2020 04;41(2):171-181

Department of Internal Medicine III, University Hospital RWTH Aachen, Aachen Pauwelsstrasse, Germany.

In Western countries, a rising incidence of obesity and type 2 diabetes correlates with an increase of non-alcoholic steatohepatitis (NASH)-a major risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). NASH is associated with chronic liver injury, triggering hepatocyte death and enhanced translocation of intestinal bacteria, leading to persistent liver inflammation through activation of Toll-like receptors and their adapter protein myeloid differentiation factor 88 (MyD88). Therefore, we investigated the role of MyD88 during progression from NASH to HCC using a mouse model of chronic liver injury (hepatocyte-specific deletion of nuclear factor κB essential modulator, Nemo; NemoΔhepa). NemoΔhepa; NemoΔhepa/MyD88-/- and NemoΔhepa/MyD88Δhepa were generated and the impact on liver disease progression was investigated. Ubiquitous MyD88 ablation (NemoΔhepa/MyD88-/-) aggravated the degree of liver damage, accompanied by an overall decrease in inflammation, whereas infiltrating macrophages and natural killer cells were elevated. At a later stage, MyD88 deficiency impaired HCC formation. In contrast, hepatocyte-specific MyD88 deletion (NemoΔhepa/MyD88Δhepa) did not affect disease progression. These results suggest that signaling of Toll-like receptors through MyD88 in non-parenchymal liver cells is required for carcinogenesis during chronic liver injury. Hence, blocking MyD88 signaling may offer a therapeutic option to prevent HCC formation in patients with NASH.
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http://dx.doi.org/10.1093/carcin/bgy173DOI Listing
April 2020