The specific metabolome profiling of patients infected by SARS-COV-2 supports the key role of tryptophan-nicotinamide pathway and cytosine metabolism.

The biological mechanisms involved in SARS-CoV-2 infection are only partially understood. Thus we explored the plasma metabolome of patients infected with SARS-CoV-2 to search for diagnostic and/or prognostic biomarkers and to improve the knowledge of metabolic disturbance in this infection. We analyzed the plasma metabolome of 55 patients infected with SARS-CoV-2 and 45 controls by LC-HRMS at the time of viral diagnosis (D0). We first evaluated the ability to predict the diagnosis from the metabotype at D0 in an independent population. Next, we assessed the feasibility of predicting the disease evolution at the 7th and 15th day. Plasma metabolome allowed us to generate a discriminant multivariate model to predict the diagnosis of SARS-CoV-2 in an independent population (accuracy > 74%, sensitivity, specificity > 75%). We identified the role of the cytosine and tryptophan-nicotinamide pathways in this discrimination. However, metabolomic exploration modestly explained the disease evolution. Here, we present the first metabolomic study in SARS-CoV-2 patients which showed a high reliable prediction of early diagnosis. We have highlighted the role of the tryptophan-nicotinamide pathway clearly linked to inflammatory signals and microbiota, and the involvement of cytosine, previously described as a coordinator of cell metabolism in SARS-CoV-2. These findings could open new therapeutic perspectives as indirect targets.

Low IDL-B and high LDL-1 subfraction levels in serum of ALS patients.

INTRODUCTION: Converging evidence highlights that lipid metabolism plays a key role in ALS pathophysiology. Dyslipidemia has been described in ALS patients and may be protective but peripheral lipoprotein subclasses have never been studied. MATERIAL AND METHODS: We collected sera from 30 ALS patients and 30 gender and age-matched controls. We analyzed 11 distinct lipoprotein subclasses by linear polyacrylamide gel electrophoresis (Lipoprint, Quantimetrix Corporation, USA). We also measured lipoprotein (a), apolipoprotein B, and apolipoprotein E levels. RESULTS: ALS patients had significant higher total cholesterol, HDL-cholesterol, and LDL-cholesterol levels than controls (p<0.0001, p=0.0007, and p=0.0065, respectively). The LDL-1 subfraction concentration was higher (1.03±0.41 vs. 0.71±0.28mmol/L; p=0.0006) and the IDL-B subfraction lower (6.5±2% vs. 8.0±2%; p=0.001) in ALS patients than controls. DISCUSSION: Our preliminary work confirmed the association between ALS and dyslipidemia. The low IDL-B levels may explain the hepatic steatosis frequently reported in ALS. The high levels of the cholesterol-rich LDL-1 subfraction is consistent with previously reported hypercholesterolemia. CONCLUSION: This study describes, for the first time, the distribution of serum lipoproteins in ALS patients, with low IDL-B and high LDL-1 subfraction level.

Biological follow-up in amyotrophic lateral sclerosis: decrease in creatinine levels and increase in ferritin levels predict poor prognosis.

BACKGROUND AND PURPOSE: Amyotrophic lateral sclerosis (ALS) is a fatal disorder of the motor neuron system, with a median survival of 2 to 4 years and a wide variety of prognosis. Thus, there is a critical need for diagnosis and prognosis biomarkers to improve the care of patients in routine practice. In this study, we aimed to determine prognostic value of routine biochemical markers in sporadic ALS (SALS). METHODS: We retrospectively collected clinical and biological data obtained during the systematic routine monitoring of 216 sporadic ALS patients. The main outcomes were disease duration and annual decline of Revised ALS Functional Rating Scale (ALSFRS-R). Changes to these biological variables over time were assessed, in link with disease progression. RESULTS: We found that concentrations of creatinine (P=0.0166) and ferritin (P=0.0306) changed significantly during the progression of ALS. A reduction of creatinine levels and an increase of ferritin levels were associated with disease progression. Multivariate analysis showed that early variation of ferritin was an independent predictive factor of patient survival (P=0.0048). CONCLUSION: Changes to ferritin and creatinine levels with time are associated with ALS progression. This is the first study describing the changes to these biological variables during ALS progression.

Advances in cellular models to explore the pathophysiology of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disorder, is fatal for most patients less than 3 years from when the first symptoms appear. The aetiologies for sporadic and most familial forms of ALS are unknown, but genetic factors are increasingly recognized as causal in a subset of patients. Studies of disease physiology suggest roles for oxidative stress, glutamate-mediated excitotoxicity or protein aggregation; how these pathways interact in the complex pathophysiology of ALS awaits elucidation. Cellular models are being used to examine disease mechanisms. Recent advances include the availability of expanded cell types, from neuronal or glial cell culture to motoneuron-astrocyte co-culture genetically or environmentally modified. Cell culture experiments confirmed the central role of glial cells in ALS. The recent adaptation of induced pluripotent stem cells (iPSC) for ALS modeling could allow a broader perspective and is expected to generate new hypotheses, related particularly to mechanisms underlying genetic factors. Cellular models have provided meaningful advances in the understanding of ALS, but, to date, complete characterization of in vitro models is only partially described. Consensus on methodological approaches, strategies for validation and techniques that allow rapid adaptation to new genetic or environmental influences is needed. In this article, we review the principal cellular models being employed in ALS and highlight their contribution to the understanding of disease mechanisms. We conclude with recommendations on means to enhance the robustness and generalizability of the different concepts for experimental ALS.

Serum calprotectin as a biomarker for Crohn's disease.

BACKGROUND AND AIMS: In Crohn's disease, correlation between clinical assessment and disease activity at tissue level is weak. Our aim was to evaluate the value of serum calprotectin as a biomarker for Crohn's disease. METHODS: The STORI trial patients (n=115) were studied at baseline, in clinical remission before infliximab withdrawal, or at the time of relapse after infliximab withdrawal. Forty healthy controls were also studied. Serum calprotectin level was measured by ELISA. Data were analyzed through correlation analyses, Kaplan Meier curves and Cox model, using available Crohn's Disease Activity Index (CDAI), Crohn's Disease Endoscopic Index of Severity (CDEIS), fecal calprotectin and C-reactive protein levels (hsCRP). RESULTS: Median serum calprotectin was 8892 ng/mL (range: 410-125,000 ng/mL) in Crohn disease patients as compared with 1318 ng/mL (range: 215.8-3770 ng/mL) in controls (P<0.0001). Serum calprotectin was significantly higher for active disease (median=19,584 ng/mL) than for inactive disease (median=8353 ng/mL) (P<0.0001). Serum calprotectin correlated with hsCRP (r=0.4092, P<0.0001) and CDAI (r=0.4442, P<0.0001), but not with CDEIS, on the contrary to fecal calprotectin (r=0.6458, 0.5515, 0.2577 with P<0.0001, P<0.0001, P=0.019 respectively). In multivariate analysis, serum calprotectin used as a discrete variable (threshold: 5675 ng/ml), appeared complementary to hsCRP (>5 mg/l) and fecal calprotectin (>250 µg/g) to predict relapse after infliximab withdrawal (P=0.0173, 0.0024 and 0.0002; HR: 3.191, 3.561 and 4.120). CONCLUSIONS: As a CD biomarker, serum calprotectin has a similar profile as hsCRP. It is also complementary to fecal calprotectin and hsCRP for prediction of relapse after infliximab withdrawal.

[Alphavirus derived vector, still a relevant system through new mobilisation procedure]. / Les vecteurs dérivés des alphavirus, un système toujours pertinent grâce à de nouveaux modes de vectorisation.

Among eukaryotic cell-expression-systems, the one derived from alphaviruses, including Semliki forest virus (SFV), offers an efficient method for protein production in mammalian cells. Despite this efficacy, twenty years after their discovery alphaviruses vectors remain poorly used. Alphavirus vectors exist as naked RNA vectors or as recombinant particles. The use of costly RNA-based replicons, and the fact that production of recombinant particles is a complex process to carry out, have hampered the attractiveness of the methods. Lastly, the apoptotic signals induced by alphavirus vectors replication leads to a rapid death of the producing cells. This feature, which can be detrimental in vitro, is advantageously exploited for in vivo applications. Besides laboratory applications, alphavirus vectors have been explored in rare phase I clinical trials, for vaccine development and cancer gene therapy, therefore, alphavirus vector will benefit from the advent of new, biosafety-efficient, methods for particles production. Most of the recent advances in the field proposed an heterologous mobilisation of alphavirus replicon. While increasing biosafety aspects, new methods are also simpler regarding the genesis of recombinant particles. In the present review, we overview the alphavirus life cycle with a special attention to the features influencing vector design and utility.

[An anicteric cholectasis and nephrotic syndrome: AL amyloïdosis in a 51 years-old man]. / Une cholestase anictérique associée à un syndrome néphrotique chez un homme de 51 ans: découverte d'une amylose AL.

Amyloidosis is a multiple-organ disease for which the diagnosis is often confusing and thereby delayed. Here, we present an archetypal case illustrating such difficulties. A 51 years-old man presented a mixed dyslipemia in November 2002, in June 2004 he has finally been diagnosed with a primary AL-amyloidosis. Within these two years, the arising of a non-icteric cholestasis and a nephrotic syndrome have triggered the search for a disease related to a multiple-organ protein deposition. Confirmation of the AL-amyloidosis was obtained through an histological examination, including direct immuno-fluorescence. Amyloidosis is a life threatening disease that need to be diagnosed at an early stage, in order to maximise the therapeutic expectations. The average survival after the diagnosis of AL-amyloidosis is 5% at 10 years. Often, treatments are initiated late in the course of the disease, at a time when organ lesion are constituted, severely affecting the prognosis.

Semliki Forest virus-derived virus-like particles: characterization of their production and transduction pathways.

A procedure for the mobilization of Semliki Forest virus (SFV)-derived replicons using virus-like particles (VLPs) has been recently proposed. VLPs were obtained from 293T cells co-expressing the vesicular stomatitis virus glycoprotein (VSV-G) and a modified SFV replicon. Advantages of SFV VLPs include improved safety with a lack of sequence homology between components and reducing the risk of recombination events that could lead to the formation of autonomous particles. Characterization of SFV VLPs reveals a discrepancy in their ability to infect cells reported to be permissive. Furthermore, it was noted that not all viral envelopes were able to promote VLP release equally from transfected cells. These observations encouraged the examination of the molecular mechanisms supporting the different steps of VLP assembly and transduction. The use of a VSV-G related pathway for VLP entry into target cells was demonstrated; it was also observed that an internal ribosome entry site may not be adapted to control transgene expression in all cells. Finally, the need for a membrane-binding domain to obtain a fully active SFV replication complex and VLP formation was documented.

Cellular factors influencing Semliki Forest Virus vector biology.

Viral vectors are currently the best tools for gene delivery in a therapeutic setting, especially for in vivo use. Alphaviruses, a family of positive singlestranded RNA viruses, have been engineered to allow the formation of a highly efficient replicon. Using these replicons, it is possible to generate recombinant particles. Parental viruses and recombinant vectors share certain pathways while interacting with their target cells. In this review, we describe the consecutive events leading to transduction, and transgene expression, in view of the cellular factors that affect each individual step. Classical virology will benefit from the knowledge accumulated studying vectors, and such work will shed light on crosstalk between intruding viruses and their hosts. Ultimately, these data should help the design of vectors adapted to specific target cells.