Gene-expression profiling of individuals resilient to Alzheimer's disease reveals higher expression of genes related to metallothionein and mitochondrial processes and no changes in the unfolded protein response.

Some individuals show a discrepancy between cognition and the amount of neuropathological changes characteristic for Alzheimer's disease (AD). This phenomenon has been referred to as 'resilience'. The molecular and cellular underpinnings of resilience remain poorly understood. To obtain an unbiased understanding of the molecular changes underlying resilience, we investigated global changes in gene expression in the superior frontal gyrus of a cohort of cognitively and pathologically well-defined AD patients, resilient individuals and age-matched controls (n = 11-12 per group). 897 genes were significantly altered between AD and control, 1121 between resilient and control and 6 between resilient and AD. Gene set enrichment analysis (GSEA) revealed that the expression of metallothionein (MT) and of genes related to mitochondrial processes was higher in the resilient donors. Weighted gene co-expression network analysis (WGCNA) identified gene modules related to the unfolded protein response, mitochondrial processes and synaptic signaling to be differentially associated with resilience or dementia. As changes in MT, mitochondria, heat shock proteins and the unfolded protein response (UPR) were the most pronounced changes in the GSEA and/or WGCNA, immunohistochemistry was used to further validate these processes. MT was significantly increased in astrocytes in resilient individuals. A higher proportion of the mitochondrial gene MT-CO1 was detected outside the cell body versus inside the cell body in the resilient compared to the control group and there were higher levels of heat shock protein 70 (HSP70) and X-box-binding protein 1 spliced (XBP1s), two proteins related to heat shock proteins and the UPR, in the AD donors. Finally, we show evidence for putative sex-specific alterations in resilience, including gene expression differences related to autophagy in females compared to males. Taken together, these results show possible mechanisms involving MTs, mitochondrial processes and the UPR by which individuals might maintain cognition despite the presence of AD pathology.

A conserved complex lipid signature marks human muscle aging and responds to short-term exercise.

Studies in preclinical models suggest that complex lipids, such as phospholipids, play a role in the regulation of longevity. However, identification of universally conserved complex lipid changes that occur during aging, and how these respond to interventions, is lacking. Here, to comprehensively map how complex lipids change during aging, we profiled ten tissues in young versus aged mice using a lipidomics platform. Strikingly, from >1,200 unique lipids, we found a tissue-wide accumulation of bis(monoacylglycero)phosphate (BMP) during mouse aging. To investigate translational value, we assessed muscle tissue of young and older people, and found a similar marked BMP accumulation in the human aging lipidome. Furthermore, we found that a healthy-aging intervention consisting of moderate-to-vigorous exercise was able to lower BMP levels in postmenopausal female research participants. Our work implicates complex lipid biology as central to aging, identifying a conserved aging lipid signature of BMP accumulation that is modifiable upon a short-term healthy-aging intervention.

Profiling of microglia nodules in multiple sclerosis reveals propensity for lesion formation.

Microglia nodules (HLA-DR+ cell clusters) are associated with brain pathology. In this post-mortem study, we investigated whether they represent the first stage of multiple sclerosis (MS) lesion formation. We show that microglia nodules are associated with more severe MS pathology. Compared to microglia nodules in stroke, those in MS show enhanced expression of genes previously found upregulated in MS lesions. Furthermore, genes associated with lipid metabolism, presence of T and B cells, production of immunoglobulins and cytokines, activation of the complement cascade, and metabolic stress are upregulated in microglia nodules in MS. Compared to stroke, they more frequently phagocytose oxidized phospholipids and possess a more tubular mitochondrial network. Strikingly, in MS, some microglia nodules encapsulate partially demyelinated axons. Taken together, we propose that activation of microglia nodules in MS by cytokines and immunoglobulins, together with phagocytosis of oxidized phospholipids, may lead to a microglia phenotype prone to MS lesion formation.

In Vitro 3D Spheroid Culture System Displays Sustained T Cell-dependent CLL Proliferation and Survival.

Chronic lymphocytic leukemia (CLL) cells are highly dependent on microenvironmental cells and signals. The lymph node (LN) is the critical site of in vivo CLL proliferation and development of resistance to both chemotherapy and targeted agents. We present a new model that incorporates key aspects of the CLL LN, which enables investigation of CLL cells in the context of a protective niche. We describe a three-dimensional (3D) in vitro culture system using ultra-low attachment plates to create spheroids of CLL cells derived from peripheral blood. Starting from CLL:T cell ratios as observed in LN samples, CLL activation was induced by either direct stimulation and/or indirectly via T cells. Compared with two-dimensional cultures, 3D cultures promoted CLL proliferation in a T cell-dependent manner, and enabled expansion for up to 7 weeks, including the formation of follicle-like structures after several weeks of culture. This model enables high-throughput drug screening, of which we describe response to Btk inhibition, venetoclax resistance, and T cell-mediated cytotoxicity as examples. In summary, we present the first LN-mimicking in vitro 3D culture for primary CLL, which enables readouts such as real-time drug screens, kinetic growth assays, and spatial localization. This is the first in vitro CLL system that allows testing of response and resistance to venetoclax and Bruton's tyrosine kinase inhibitors in the context of the tumor microenvironment, thereby opening up new possibilities for clinically useful applications.

CRB1 is required for recycling by RAB11A+ vesicles in human retinal organoids.

CRB1 gene mutations can cause early- or late-onset retinitis pigmentosa, Leber congenital amaurosis, or maculopathy. Recapitulating human CRB1 phenotypes in animal models has proven challenging, necessitating the development of alternatives. We generated human induced pluripotent stem cell (iPSC)-derived retinal organoids of patients with retinitis pigmentosa caused by biallelic CRB1 mutations and evaluated them against autologous gene-corrected hiPSCs and hiPSCs from healthy individuals. Patient organoids show decreased levels of CRB1 and NOTCH1 expression at the retinal outer limiting membrane. Proximity ligation assays show that human CRB1 and NOTCH1 can interact via their extracellular domains. CRB1 patient organoids feature increased levels of WDFY1+ vesicles, fewer RAB11A+ recycling endosomes, decreased VPS35 retromer complex components, and more degradative endolysosomal compartments relative to isogenic control organoids. Taken together, our data demonstrate that patient-derived retinal organoids enable modeling of retinal degeneration and highlight the importance of CRB1 in early endosome maturation receptor recycling in the retina.

Chronic lymphocytic leukemia presence impairs antigen-specific CD8+ T-cell responses through epigenetic reprogramming towards short-lived effectors.

T-cell dysregulation in chronic lymphocytic leukemia (CLL) associates with low response rates to autologous T cell-based therapies. How CLL affects antigen-specific T-cell responses remains largely unknown. We investigated (epi)genetic and functional consequences of antigen-specific T-cell responses in presence of CLL in vitro and in an adoptive-transfer murine model. Already at steady-state, antigen-experienced patient-derived T cells were skewed towards short-lived effector cells (SLEC) at the expense of memory-precursor effector cells (MPEC). Stimulation of these T cells in vitro showed rapid induction of effector genes and suppression of key memory transcription factors only in presence of CLL cells, indicating epigenetic regulation. This was investigated in vivo by following antigen-specific responses of naïve OT-I CD8+ cells to mCMV-OVA in presence/absence of TCL1 B-cell leukemia. Presence of leukemia resulted in increased SLEC formation, with disturbed inflammatory cytokine production. Chromatin and transcriptome profiling revealed strong epigenetic modifications, leading to activation of an effector and silencing of a memory profile through presence of CLL cells. Secondary challenge in vivo confirmed dysfunctional memory responses by antigen-experienced OT-I cells generated in presence of CLL. Altogether, we show that presence of CLL induces a short-lived effector phenotype and impaired memory responses by epigenetic reprogramming during primary responses.

Osteopontin associates with brain TRM-cell transcriptome and compartmentalization in donors with and without multiple sclerosis.

The human brain is populated by perivascular T cells with a tissue-resident memory T (TRM)-cell phenotype, which in multiple sclerosis (MS) associate with lesions. We investigated the transcriptional and functional profile of freshly isolated T cells from white and gray matter. RNA sequencing of CD8+ and CD4+ CD69+ T cells revealed TRM-cell signatures. Notably, gene expression hardly differed between lesional and normal-appearing white matter T cells in MS brains. Genes up-regulated in brain TRM cells were MS4A1 (CD20) and SPP1 (osteopontin, OPN). OPN is also abundantly expressed by microglia and has been shown to inhibit T cell activity. In line with their parenchymal localization and the increased presence of OPN in active MS lesions, we noticed a reduced production of inflammatory cytokines IL-2, TNF, and IFNγ by lesion-derived CD8+ and CD4+ T cells ex vivo. Our study reports traits of brain TRM cells and reveals their tight control in MS lesions.

Myeloid CD40 deficiency reduces atherosclerosis by impairing macrophages' transition into a pro-inflammatory state.

AIMS: CD40 and its ligand, CD40L, play a critical role in driving atherosclerotic plaque development. Disrupted CD40-signalling reduces experimental atherosclerosis and induces a favourable stable plaque phenotype. We recently showed that small molecule-based inhibition of CD40-tumour necrosis factor receptor associated factor-6 interactions attenuates atherosclerosis in hyperlipidaemic mice via macrophage-driven mechanisms. The present study aims to detail the function of myeloid CD40 in atherosclerosis using myeloid-specific CD40-deficient mice. METHOD AND RESULTS: Cd40flox/flox and LysM-cre Cd40flox/flox mice on an Apoe-/- background were generated (CD40wt and CD40mac-/-, respectively). Atherosclerotic lesion size, as well as plaque macrophage content, was reduced in CD40mac-/- compared to CD40wt mice, and their plaques displayed a reduction in necrotic core size. Transcriptomics analysis of the CD40mac-/- atherosclerotic aorta revealed downregulated pathways of immune pathways and inflammatory responses. Loss of CD40 in macrophages changed the representation of aortic macrophage subsets. Mass cytometry analysis revealed a higher content of a subset of alternative or resident-like CD206+CD209b- macrophages in the atherosclerotic aorta of CD40mac-/- compared to CD40wt mice. RNA-sequencing of bone marrow-derived macrophages of CD40mac-/- mice demonstrated upregulation of genes associated with alternatively activated macrophages (including Folr2, Thbs1, Sdc1, and Tns1). CONCLUSIONS: We here show that absence of CD40 signalling in myeloid cells reduces atherosclerosis and limits systemic inflammation by preventing a shift in macrophage polarization towards pro-inflammatory states. Our study confirms the merit of macrophage-targeted inhibition of CD40 as a valuable therapeutic strategy to combat atherosclerosis.

SMG1, a nonsense-mediated mRNA decay (NMD) regulator, as a candidate therapeutic target in multiple myeloma.

Early data suggested that CC-115, a clinical molecule, already known to inhibit the mammalian target of rapamycin kinase (TORK) and DNA-dependent protein kinase (DNA-PK) may have additional targets beyond TORK and DNA-PK. Therefore, we aimed to identify such target(s) and investigate a potential therapeutic applicability. Functional profiling of 141 cancer cell lines revealed inhibition of kinase suppressor of morphogenesis in genitalia 1 (SMG1), a key regulator of the RNA degradation mechanism nonsense-mediated mRNA decay (NMD), as an additional target of CC-115. CC-115 treatment showed a dose-dependent increase of SMG1-mediated NMD transcripts. A subset of cell lines, including multiple myeloma (MM) cell lines sensitive to the endoplasmic reticulum stress-inducing compound thapsigargin, were highly susceptible to SMG1 inhibition. CC-115 caused the induction of UPR transcripts and cell death by mitochondrial apoptosis, requiring the presence of BAX/BAK and caspase activity. Superior antitumor activity of CC-115 over TORK inhibitors in primary human MM cells and three xenograft mouse models appeared to be via inhibition of SMG1. Our data support further development of SMG1 inhibitors as possible therapeutics in MM.

A public antibody class recognizes an S2 epitope exposed on open conformations of SARS-CoV-2 spike.

Delineating the origins and properties of antibodies elicited by SARS-CoV-2 infection and vaccination is critical for understanding their benefits and potential shortcomings. Therefore, we investigate the SARS-CoV-2 spike (S)-reactive B cell repertoire in unexposed individuals by flow cytometry and single-cell sequencing. We show that ∼82% of SARS-CoV-2 S-reactive B cells harbor a naive phenotype, which represents an unusually high fraction of total human naive B cells (∼0.1%). Approximately 10% of these naive S-reactive B cells share an IGHV1-69/IGKV3-11 B cell receptor pairing, an enrichment of 18-fold compared to the complete naive repertoire. Following SARS-CoV-2 infection, we report an average 37-fold enrichment of IGHV1-69/IGKV3-11 B cell receptor pairing in the S-reactive memory B cells compared to the unselected memory repertoire. This class of B cells targets a previously undefined non-neutralizing epitope on the S2 subunit that becomes exposed on S proteins used in approved vaccines when they transition away from the native pre-fusion state because of instability. These findings can help guide the improvement of SARS-CoV-2 vaccines.

Candidate Plasma Biomarkers to Detect Anthracycline-Related Cardiomyopathy in Childhood Cancer Survivors: A Case Control Study in the Dutch Childhood Cancer Survivor Study.

Background Plasma biomarkers may aid in the detection of anthracycline-related cardiomyopathy (ACMP). However, the currently available biomarkers have limited diagnostic value in long-term childhood cancer survivors. This study sought to identify diagnostic plasma biomarkers for ACMP in childhood cancer survivors. Methods and Results We measured 275 plasma proteins in 28 ACMP cases with left ventricular ejection fraction <45%, 29 anthracycline-treated controls with left ventricular ejection fraction ≥53% matched on sex, time after cancer, and anthracycline dose, and 29 patients with genetically determined dilated cardiomyopathy with left ventricular ejection fraction <45%. Multivariable linear regression was used to identify differentially expressed proteins. Elastic net model, including clinical characteristics, was used to assess discrimination of proteins diagnostic for ACMP. NT-proBNP (N-terminal pro-B-type natriuretic peptide) and the inflammatory markers CCL19 (C-C motif chemokine ligands 19) and CCL20, PSPD (pulmonary surfactant protein-D), and PTN (pleiotrophin) were significantly upregulated in ACMP compared with controls. An elastic net model selected 45 proteins, including NT-proBNP, CCL19, CCL20 and PSPD, but not PTN, that discriminated ACMP cases from controls with an area under the receiver operating characteristic curve (AUC) of 0.78. This model was not superior to a model including NT-proBNP and clinical characteristics (AUC=0.75; P=0.766). However, when excluding 8 ACMP cases with heart failure, the full model was superior to that including only NT-proBNP and clinical characteristics (AUC=0.75 versus AUC=0.50; P=0.022). The same 45 proteins also showed good discrimination between dilated cardiomyopathy and controls (AUC=0.89), underscoring their association with cardiomyopathy. Conclusions We identified 3 specific inflammatory proteins as candidate plasma biomarkers for ACMP in long-term childhood cancer survivors and demonstrated protein overlap with dilated cardiomyopathy.

Gamma-H2AX Foci Decay Ratio as a Stronger Predictive Factor of Late Radiation Toxicity Than Dose-Volume Parameters in a Prospective Cohort of Prostate Cancer Patients.

PURPOSE: Late radiation toxicity is a major dose-limiting factor in curative cancer radiation therapy. Previous studies identified several risk factors for late radiation toxicity, including both dose-volume factors and genetic predisposition. Herein, we investigated the contribution of genetic predisposition, particularly compared with dose-volume factors, to the risk of late radiation toxicity in patients treated with highly conformal radiation therapy. METHODS AND MATERIALS: We included 179 patients with prostate cancer who underwent treatment with curative external beam radiation therapy between 2009 and 2013. Toxicity was graded according to the Common Terminology Criteria for Adverse Events version 4.0. Transcriptional responsiveness of homologous recombination repair genes and γ-H2AX foci decay ratios (FDRs) were determined in ex vivo irradiated lymphocytes in a previous analysis. Dose-volume parameters were retrieved by delineating the organs at risk (OARs) on CT planning images. Associations between risk factors and grade ≥2 urinary and bowel late radiation toxicities were assessed using univariable and multivariable logistic regression analyses. The analyses were performed using the highest toxicity grade recorded during the follow-up per patient. RESULTS: The median follow-up period was 31 months. One hundred and one patients (56%) developed grade ≥2 late radiation toxicity. Cumulative rates for urinary and bowel grade ≥2 late toxicities were 46% and 17%, respectively. In the multivariable analysis, factors significantly associated with grade ≥2 late toxicity were transurethral resection of the prostate (P = .013), γ-H2AX FDR <3.41 (P = .008), and rectum V70 >11.52% (P = .017). CONCLUSIONS: Our results suggest that impaired DNA double-strand break repair in lymphocytes, as quantified by γ-H2AX FDR, is the most critical determining factor of late radiation toxicity. The limited influence of dose-volume parameters could be due to the use of increasingly conformal techniques, leading to improved dose-volume parameters of the organs at risk.

Core circadian clock genes Per1 and Per2 regulate the rhythm in photoreceptor outer segment phagocytosis.

Retinal photoreceptors undergo daily renewal of their distal outer segments, a process indispensable for maintaining retinal health. Photoreceptor outer segment (POS) phagocytosis occurs as a daily peak, roughly about 1 hour after light onset. However, the underlying cellular and molecular mechanisms which initiate this process are still unknown. Here we show that, under constant darkness, mice deficient for core circadian clock genes (Per1 and Per2) lack a daily peak in POS phagocytosis. By qPCR analysis, we found that core clock genes were rhythmic over 24 hours in both WT and Per1, Per2 double mutant whole retinas. More precise transcriptomics analysis of laser capture microdissected WT photoreceptors revealed no differentially expressed genes between time points preceding and during the peak of POS phagocytosis. In contrast, we found that microdissected WT retinal pigment epithelium (RPE) had a number of genes that were differentially expressed at the peak phagocytic time point compared to adjacent ones. We also found a number of differentially expressed genes in Per1, Per2 double mutant RPE compared to WT ones at the peak phagocytic time point. Finally, based on STRING analysis, we found a group of interacting genes that potentially drive POS phagocytosis in the RPE. This potential pathway consists of genes such as: Pacsin1, Syp, Camk2b, and Camk2d among others. Our findings indicate that Per1 and Per2 are necessary clock components for driving POS phagocytosis and suggest that this process is transcriptionally driven by the RPE.

Time-Resolved Profiling Reveals ATF3 as a Novel Mediator of Endocrine Resistance in Breast Cancer.

Breast cancer is one of the leading causes of death for women worldwide. Patients whose tumors express Estrogen Receptor α account for around 70% of cases and are mostly treated with targeted endocrine therapy. However, depending on the degree of severity of the disease at diagnosis, 10 to 40% of these tumors eventually relapse due to resistance development. Even though recent novel approaches as the combination with CDK4/6 inhibitors increased the overall survival of relapsing patients, this remains relatively short and there is a urgent need to find alternative targetable pathways. In this study we profiled the early phases of the resistance development process to uncover drivers of this phenomenon. Time-resolved analysis revealed that ATF3, a member of the ATF/CREB family of transcription factors, acts as a novel regulator of the response to therapy via rewiring of central signaling processes towards the adaptation to endocrine treatment. ATF3 was found to be essential in controlling crucial processes such as proliferation, cell cycle, and apoptosis during the early response to treatment through the regulation of MAPK/AKT signaling pathways. Its essential role was confirmed in vivo in a mouse model, and elevated expression of ATF3 was verified in patient datasets, adding clinical relevance to our findings. This study proposes ATF3 as a novel mediator of endocrine resistance development in breast cancer and elucidates its role in the regulation of downstream pathways activities.

Core-clock genes Period 1 and 2 regulate visual cascade and cell cycle components during mouse eye development.

The retinas from Period 1 (Per1) and Period 2 (Per2) double-mutant mice (Per1-/-Per2Brdm1) display abnormal blue-cone distribution associated with a reduction in cone opsin mRNA and protein levels, up to 1 year of age. To reveal the molecular mechanisms by which Per1 and Per2 control retina development, we analyzed genome-wide gene expression differences between wild-type (WT) and Per1-/-Per2Brdm1 mice across ocular developmental stages (E15, E18 and P3). All clock genes displayed changes in transcript levels along with normal eye development. RNA-Seq data show major gene expression changes between WT and mutant eyes, with the number of differentially expressed genes (DEG) increasing with developmental age. Functional annotation of the genes showed that the most significant changes in expression levels in mutant mice involve molecular pathways relating to circadian rhythm signaling at E15 and E18. At P3, the visual cascade and the cell cycle were respectively higher and lower expressed compared to WT eyes. Overall, our study provides new insights into signaling pathways -phototransduction and cell cycle- controlled by the circadian clock in the eye during development.

Multi-Omic Approach to Identify Phenotypic Modifiers Underlying Cerebral Demyelination in X-Linked Adrenoleukodystrophy.

X-linked adrenoleukodystrophy (ALD) is a peroxisomal metabolic disorder with a highly complex clinical presentation. ALD is caused by mutations in the ABCD1 gene, and is characterized by the accumulation of very long-chain fatty acids in plasma and tissues. Disease-causing mutations are 'loss of function' mutations, with no prognostic value with respect to the clinical outcome of an individual. All male patients with ALD develop spinal cord disease and a peripheral neuropathy in adulthood, although age of onset is highly variable. However, the lifetime prevalence to develop progressive white matter lesions, termed cerebral ALD (CALD), is only about 60%. Early identification of transition to CALD is critical since it can be halted by allogeneic hematopoietic stem cell therapy only in an early stage. The primary goal of this study is to identify molecular markers which may be prognostic of cerebral demyelination from a simple blood sample, with the hope that blood-based assays can replace the current protocols for diagnosis. We collected six well-characterized brother pairs affected by ALD and discordant for the presence of CALD and performed multi-omic profiling of blood samples including genome, epigenome, transcriptome, metabolome/lipidome, and proteome profiling. In our analysis we identify discordant genomic alleles present across all families as well as differentially abundant molecular features across the omics technologies. The analysis was focused on univariate modeling to discriminate the two phenotypic groups, but was unable to identify statistically significant candidate molecular markers. Our study highlights the issues caused by a large amount of inter-individual variation, and supports the emerging hypothesis that cerebral demyelination is a complex mix of environmental factors and/or heterogeneous genomic alleles. We confirm previous observations about the role of immune response, specifically auto-immunity and the potential role of PFN1 protein overabundance in CALD in a subset of the families. We envision our methodology as well as dataset has utility to the field for reproducing previous or enabling future modifier investigations.

Candidate methylation sites associated with endocrine therapy resistance in ER+/HER2- breast cancer.

BACKGROUND: Estrogen receptor (ER) positive breast cancer is often effectively treated with drugs that inhibit ER signaling, i.e., tamoxifen (TAM) and aromatase inhibitors (AIs). However, 30% of ER+ breast cancer patients develop resistance to therapy leading to tumour recurrence. Changes in the methylation profile have been implicated as one of the mechanisms through which therapy resistance develops. Therefore, we aimed to identify methylation loci associated with endocrine therapy resistance. METHODS: We used genome-wide DNA methylation profiles of primary ER+/HER2- tumours from The Cancer Genome Atlas in combination with curated data on survival and treatment to predict development of endocrine resistance. Association of individual DNA methylation markers with survival was assessed using Cox proportional hazards models in a cohort of ER+/HER2- tumours (N = 552) and two sub-cohorts corresponding to the endocrine treatment (AI or TAM) that patients received (N = 210 and N = 172, respectively). We also identified multivariable methylation signatures associated with survival using Cox proportional hazards models with elastic net regularization. Individual markers and multivariable signatures were compared with DNA methylation profiles generated in a time course experiment using the T47D ER+ breast cancer cell line treated with tamoxifen or deprived from estrogen. RESULTS: We identified 134, 5 and 1 CpGs for which DNA methylation is significantly associated with survival in the ER+/HER2-, TAM and AI cohorts respectively. Multi-locus signatures consisted of 203, 36 and 178 CpGs and showed a large overlap with the corresponding single-locus signatures. The methylation signatures were associated with survival independently of tumour stage, age, AI treatment, and luminal status. The single-locus signature for the TAM cohort was conserved among the loci that were differentially methylated in endocrine-resistant T47D cells. Similarly, multi-locus signatures for the ER+/HER2- and AI cohorts were conserved in endocrine-resistant T47D cells. Also at the gene set level, several sets related to endocrine therapy and resistance were enriched in both survival and T47D signatures. CONCLUSIONS: We identified individual and multivariable DNA methylation markers associated with therapy resistance independently of luminal status. Our results suggest that these markers identified from primary tumours prior to endocrine treatment are associated with development of endocrine resistance.

Functional Differences Between EBV- and CMV-Specific CD8+ T cells Demonstrate Heterogeneity of T cell Dysfunction in CLL.

Acquired T cell dysfunction is a hallmark of chronic lymphocytic leukemia (CLL), and is linked to an increased risk of infections, but also reduced immune surveillance and disappointing responses to autologous T cell-based immunotherapy. The mechanisms of T cell dysfunction in CLL are not well understood. Studying immunity against chronic viruses allows for detailed analysis of the effect of CLL on T cells chronically exposed to a specific antigen. Cytomegalovirus (CMV) reactivations are rare in CLL, which corroborates with preserved CMV-specific T cell function. Epstein-Barr virus (EBV) is another herpesvirus that results in chronic infection, but unlike CMV, is characterized by subclinical reactivations in CLL patients. Since both herpesviruses induce strong CD8+ T cell responses, but have different clinical outcomes, studying these specific T cells may shed light on the mechanisms of CLL-induced T cell dysfunction. We first analyzed the phenotype of EBV-specific CD8+ T cells in CLL and healthy controls, and found that in CLL EBV-specific CD8+ T cells are in an advanced differentiation state with higher expression of inhibitory receptors. Secondly, CLL-derived EBV-specific CD8+ T cells show reduced cytotoxic potential, in contrast to CMV-specific T cells. Finally, we performed transcriptome analysis to visualize differential modulation by CLL of these T cell subsets. While T cell activation and differentiation genes are unaffected, in EBV-specific T cells expression of genes involved in synapse formation and T cell exhaustion is altered. Our findings on the heterogeneity of antigen specific T cell function in CLL aids in understanding immune-dysregulation in this disease.

Genome-wide expression profiling reveals increased stability and mitochondrial energy metabolism of the human liver cell line HepaRG-CAR.

Human liver cell line HepaRG is a well-known source of human hepatocyte-like cells which, however, displays limited biotransformation and a tendency to transform after 20 passages. The new HepaRG-CAR cell line overexpressing constitutive androstane receptor (CAR, NR1I3), a regulator of detoxification and energy metabolism outperforms the parental HepaRG cell line in various liver functions. To further characterize this cell line and assess its stability we compared HepaRG-CAR with HepaRG cells at different passages for their expression profile, ammonia and lactate metabolism, bile acid and reactive oxygen species (ROS) production. Transcriptomic profiling of HepaRG-CAR vs. HepaRG early-passage revealed downregulation of hypoxia, glycolysis and proliferation and upregulation of oxidative phosphorylation genesets. In addition CAR overexpression downregulated the mTORC1 signaling pathway, which, as mediator of proliferation and metabolic reprogramming, may play an important role in the establishment of the HepaRG-CAR phenotype. The ammonia and lactate metabolism and bile acid production of HepaRG-CAR cells was stable for 10 additional passages compared to HepaRG cells. Interestingly, bile acid production was 4.5-fold higher in HepaRG-CAR vs. HepaRG cells, whereas lactate and ROS production were 2.7- and 2.0-fold lower, respectively. Principal component analysis showed clustering of HepaRG-CAR (early- and late-passage) and HepaRG early-passage and not with HepaRG late-passage indicating that passaging exerted larger effect on the transcriptional profile of HepaRG than HepaRG-CAR cells. In conclusion, overexpression of CAR in HepaRG cells improves their bile acid production, mitochondrial energy metabolism, and stability, with the latter possibly due to reduced ROS production, resulting in an optimized source of human hepatocytes.

A Conserved Mito-Cytosolic Translational Balance Links Two Longevity Pathways.

Slowing down translation in either the cytosol or the mitochondria is a conserved longevity mechanism. Here, we found a non-interventional natural correlation of mitochondrial and cytosolic ribosomal proteins (RPs) in mouse population genetics, suggesting a translational balance. Inhibiting mitochondrial translation in C. elegans through mrps-5 RNAi repressed cytosolic translation. Transcriptomics integrated with proteomics revealed that this inhibition specifically reduced translational efficiency of mRNAs required in growth pathways while increasing stress response mRNAs. The repression of cytosolic translation and extension of lifespan from mrps-5 RNAi were dependent on atf-5/ATF4 and independent from metabolic phenotypes. We found the translational balance to be conserved in mammalian cells upon inhibiting mitochondrial translation pharmacologically with doxycycline. Lastly, extending this in vivo, doxycycline repressed cytosolic translation in the livers of germ-free mice. These data demonstrate that inhibiting mitochondrial translation initiates an atf-5/ATF4-dependent cascade leading to coordinated repression of cytosolic translation, which could be targeted to promote longevity.