Potential role of herpes simplex virus type 1 in Alzheimer’s disease

L'étiologie de la forme sporadique de la maladie d'Alzheimer (AD) reste largement inconnue. Toutefois, une adéquation entre des facteurs environnementaux et génétiques est fortement probable. C'est ainsi que de nombreux arguments suggèrent que le virus herpes simplex de type 1 (HSV1) en infectant et en se répliquant dans le système nerveux central, puisse être un co-facteur impliqué dans le déclenchement et le développement de l'AD. Pour éprouver cette hypothèse, nous avons développé un modèle cellulaire constitué de neurones de rat infectés par HSV1 pour analyser les modifications viro-induites de leur expression génique. Il a été mis en évidence dans les neurones infectés : i) une augmentation de la production du peptide amyloïde Aβ42 et de Tau phosphorylée, ainsi que leur agrégation dans un agrésome intracellulaire ; ii) des variations du niveau de transcription de nombreux gènes très similaires à celles observées chez des patients AD. Par ailleurs, l'étude des mécanismes moléculaires de l'apoptose viro-induite dans ce modèle original a permis de mettre en évidence une corrélation entre l'activation des caspases et la production d'Aβ42 et une corrélation entre le phénomène d'apoptose avortée (abortosis) et la formation d'agrésome. De l'ensemble des ces résultats, il apparait que ce modèle cellulaire est représentatif de certains aspects des stades précoces de l'AD et conforte l'hypothèse qu'HSV1 serait un co-facteur dans la maladie d'AlzheimerThe origin of the sporadic form of the Alzheimer's disease (AD) remains still widely unknown. However, an adequacy between environmental and genetic factors is highly probable. Numerous arguments suggest that the virus herpes simplex of type 1 (HSV1) by infecting and replicating in the central nervous system, could be a co-factor involved in the AD process. To evaluate this hypothesis, we set up a model made of rat neurons infected by HSV1 in order to analyse the virally-induced modifications of their gene expression. Using this model we have shown: i) an over-production of the amyloid peptide Aß42 and of phosphorylated form of Tau accompanied by their concentration within an intracellular aggresome; ii) variations of the transcription levels of numerous genes equivalent to that observed in AD patients. Furthermore, the study of the molecular mechanisms underlying the virally-induced apoptosis allowed to point out a correlation between caspase activation and Aß42 production as well as a correlation between abortosis and aggresome formation. All together these results demonstrate that this cellular model represents, at least in part, some aspects of the early stages of AD and bring evidences that HSV1 could be a co-factor in the AD proces

Isolation of nucleoli

Nucleoli are now recognized as multi-functional nuclear domains involved in several fundamental cell processes such as ribosome biogenesis, regulation of the assembly of non-ribosomal ribonucleoprotein complexes, tRNA maturation, sequestration of protein, viral infection, and cellular ageing. Extensive proteomic analyses of these nucleolar domains after their purification have contributed to the description of their multiple biological functions. Because nucleoli are the largest and densest nuclear structures, they are easily amenable to purification from nuclei of cultured animal cells using the protocol described in this unit

HSV-1 cellular model reveals links between aggresome formation and early step of Alzheimer's disease

International audienceMany studies highlight the potential link between the chronic degenerative Alzheimer's disease and the infection by the herpes simplex virus type-1 (HSV-1). However, the molecular mechanisms making possible this HSV-1-dependent process remain to be understood. Using neuronal cells expressing the wild type form of amyloid precursor protein (APP) infected by HSV-1, we characterized a representative cellular model of the early stage of the sporadic form of the disease and unraveled a molecular mechanism sustaining this HSV-1- Alzheimer's disease interplay. Here, we show that HSV-1 induces caspase-dependent production of the 42 amino-acid long amyloid peptide (A beta 42) oligomers followed by their accumulation in neuronal cells. A beta 42 oligomers and activated caspase 3 (casp3A) concentrate into intracytoplasmic structures observed in Alzheimer's disease neuronal cells called aggresomes. This casp3A accumulation in aggresomes during HSV-1 infection limits the execution of apoptosis until its term, similarly to an abortosis-like event occurring in Alzheimer's disease neuronal cells patients. Indeed, this particular HSV-1 driven cellular context, representative of early stages of the disease, sustains a failed apoptosis mechanism that could explain the chronic amplification of A beta 42 production characteristic of Alzheimer's disease patients. Finally, we show that combination of flurbiprofen, a non-steroidal anti-inflammatory drug (NSAID), with caspase inhibitor reduced drastically HSV-1-induced A beta 42 oligomers production. This provided mechanistic insights supporting the conclusion of clinical trials showing that NSAIDs reduced Alzheimer's disease incidence in early stage of the disease. Therefore, from our study we propose that caspase-dependent production of A beta 42 oligomers together with the abortosis-like event represents a vicious circle in early Alzheimer's disease stages leading to a chronic amplification of A beta 42 oligomers that contributes to the establishment of degenerative disorder like Alzheimer's disease in patients infected by HSV-1. Interestingly this process could be targeted by an association of NSAID with caspase inhibitors

Spatial sequestration of activated-caspase 3 in aggresomes mediates resistance of neuroblastoma cell to bortezomib treatment

Abstract Neuroblastoma (NB) is the most common pediatric tumor and is currently treated by several types of therapies including chemotherapies, such as bortezomib treatment. However, resistance to bortezomib is frequently observed by mechanisms that remain to be deciphered. Bortezomib treatment leads to caspase activation and aggresome formation. Using models of patients-derived NB cell lines with different levels of sensitivity to bortezomib, we show that the activated form of caspase 3 accumulates within aggresomes of NB resistant cells leading to an impairment of bortezomib-induced apoptosis and increased cell survival. Our findings unveil a new mechanism of resistance to chemotherapy based on an altered subcellular distribution of the executioner caspase 3. This mechanism could explain the resistance developed in NB patients treated with bortezomib, emphasizing the potential of drugs targeting aggresomes

Immunological and classical subtypes of oral premalignant lesions

International audienceOral squamous cell carcinoma (OSCC) is a major cause of cancer-associated morbidity and mortality and may develop from oral premalignant lesions (OPL). An improved molecular classification of OPL may help refining prevention strategies. We identified two main OPL gene-expression subtypes, named immunological and classical, in 86 OPL (discovery dataset). A gene expression-based score was then developed to classify OPL samples from three independent datasets, including 17 (GSE30784),13 (GSE10174) and 15 (GSE85195) OPLs, into either one of the two gene-expression subtypes. Using the single sample gene set enrichment analysis, enrichment scores for immune-related pathways were different between the two OPL subtypes. In OPL from the discovery set, loss of heterozygosities (LOH) at 3p14, 17p13, TP53, 9p21 and 8p22 and miRNA gene expression profiles were analyzed. Deconvolution of the immune infiltrate was performed using the Microenvironment Cell Populations-counter tool. A multivariate analysis revealed that decreased miRNA-142-5p expression (P = 0.0484) and lower T-cell, monocytic and myeloid dendritic cells (MDC) immune infiltration (T-cells, P = 0.0196; CD8 T cells, P = 0.0129; MDC, P = 0.0481; and monocytes, P = 0.0212) were associated with oral cancer development in the immunological subtype only. In contrast, LOH at 3p14 (P = 0.0241), 17p13 (P = 0.0348) and TP53 (P = 0.004) were associated with oral cancer development in the classical subtype only. In conclusion, we identified 2 subtypes of OPLs, namely immune and classical, which may benefit from different and specific personalized prevention interventions. ARTICLE HISTOR

Externalized Keratin 8: A Target at the Interface of Microenvironment and Intracellular Signaling in Colorectal Cancer Cells

International audienceAccumulating evidence supports the remarkable presence at the membrane surface of cancer cells of proteins, which are normally expressed in the intracellular compartment. Although these proteins, referred to as externalized proteins, represent a highly promising source of accessible and druggable targets for cancer therapy, the mechanisms via which they impact cancer biology remain largely unexplored. The aim of this study was to expose an externalized form of cytokeratin 8 (eK8) as a key player of colorectal tumorigenesis and characterize its mode of action. To achieve this, we generated a unique antagonist monoclonal antibody (D-A10 MAb) targeting an eight-amino-acid-long domain of eK8, which enabled us to ascertain the pro-tumoral activity of eK8 in both KRAS-mutant and wild-type colorectal cancers (CRC). We showed that this pro-tumoral activity involves a bidirectional eK8-dependent control of caspase-mediated apoptosis in vivo and of the plasminogen-induced invasion process in cellulo. Furthermore, we demonstrated that eK8 is anchored at the plasma membrane supporting this dual function. We, therefore, identified eK8 Cancers 2018, 10, 452 2 of 17 as an innovative therapeutic target in CRC and provided a unique MAb targeting eK8 that displays anti-neoplastic activities that could be useful to treat CRC, including those harboring KRAS mutations

COvid-19 and high-dose VITamin D supplementation TRIAL in high-risk older patients (COVIT-TRIAL): study protocol for a randomized controlled trial

International audienceAbstract Background With the lack of effective therapy, chemoprevention, and vaccination against SARS-CoV-2, focusing on the immediate repurposing of existing drugs gives hope of curbing the COVID-19 pandemic. A recent unbiased genomics-guided tracing of the SARS-CoV-2 targets in human cells identified vitamin D among the three top-scoring molecules manifesting potential infection mitigation patterns. Growing pre-clinical and epidemiological observational data support this assumption. We hypothesized that vitamin D supplementation may improve the prognosis of COVID-19. The aim of this trial is to compare the effect of a single oral high dose of cholecalciferol versus a single oral standard dose on all-cause 14-day mortality rate in COVID-19 older adults at higher risk of worsening. Methods The COVIT-TRIAL study is an open-label, multicenter, randomized controlled superiority trial. Patients aged ≥ 65 years with COVID-19 (diagnosed within the preceding 3 days with RT-PCR and/or chest CT scan) and at least one worsening risk factor at the time of inclusion (i.e., age ≥ 75 years, or SpO2 ≤ 94% in room air, or PaO2/FiO2 ≤ 300 mmHg), having no contraindications to vitamin D supplementation, and having received no vitamin D supplementation > 800 IU/day during the preceding month are recruited. Participants are randomized either to high-dose cholecalciferol (two 200,000 IU drinking vials at once on the day of inclusion) or to standard-dose cholecalciferol (one 50,000 IU drinking vial on the day of inclusion). Two hundred sixty participants are recruited and followed up for 28 days. The primary outcome measure is all-cause mortality within 14 days of inclusion. Secondary outcomes are the score changes on the World Health Organization Ordinal Scale for Clinical Improvement (OSCI) scale for COVID-19, and the between-group comparison of safety. These outcomes are assessed at baseline, day 14, and day 28, together with the serum concentrations of 25(OH)D, creatinine, calcium, and albumin at baseline and day 7. Discussion COVIT-TRIAL is to our knowledge the first randomized controlled trial testing the effect of vitamin D supplementation on the prognosis of COVID-19 in high-risk older patients. High-dose vitamin D supplementation may be an effective, well-tolerated, and easily and immediately accessible treatment for COVID-19, the incidence of which increases dramatically and for which there are currently no scientifically validated treatments. Trial registration ClinicalTrials.gov NCT04344041 . Registered on 14 April 2020 Trial status Recruiting. Recruitment is expected to be completed in April 2021

p53 acts as a safeguard of translational control by regulating fibrillarin and rRNA methylation in cancer

SummaryRibosomes are specialized entities that participate in regulation of gene expression through their rRNAs carrying ribozyme activity. Ribosome biogenesis is overactivated in p53-inactivated cancer cells, although involvement of p53 on ribosome quality is unknown. Here, we show that p53 represses expression of the rRNA methyl-transferase fibrillarin (FBL) by binding directly to FBL. High levels of FBL are accompanied by modifications of the rRNA methylation pattern, impairment of translational fidelity, and an increase of internal ribosome entry site (IRES)-dependent translation initiation of key cancer genes. FBL overexpression contributes to tumorigenesis and is associated with poor survival in patients with breast cancer. Thus, p53 acts as a safeguard of protein synthesis by regulating FBL and the subsequent quality and intrinsic activity of ribosomes

Low incidence of SARS-CoV-2, risk factors of mortality and the course of illness in the French national cohort of dialysis patients

International audienceThe aim of this study was to estimate the incidence of COVID-19 disease in the French national population of dialysis patients, their course of illness and to identify the risk factors associated with mortality. Our study included all patients on dialysis recorded in the French REIN Registry in April 2020. Clinical characteristics at last follow-up and the evolution of COVID-19 illness severity over time were recorded for diagnosed cases (either suspicious clinical symptoms, characteristic signs on the chest scan or a positive reverse transcription polymerase chain reaction) for SARS-CoV-2. A total of 1,621 infected patients were reported on the REIN registry from March 16th, 2020 to May 4th, 2020. Of these, 344 died. The prevalence of COVID-19 patients varied from less than 1% to 10% between regions. The probability of being a case was higher in males, patients with diabetes, those in need of assistance for transfer or treated at a self-care unit. Dialysis at home was associated with a lower probability of being infected as was being a smoker, a former smoker, having an active malignancy, or peripheral vascular disease. Mortality in diagnosed cases (21%) was associated with the same causes as in the general population. Higher age, hypoalbuminemia and the presence of an ischemic heart disease were statistically independently associated with a higher risk of death. Being treated at a selfcare unit was associated with a lower risk. Thus, our study showed a relatively low frequency of COVID-19 among dialysis patients contrary to what might have been assumed