Taxonomical and functional changes in COVID-19 faecal microbiome could be related to SARS-CoV-2 faecal load.

Since the beginning of the pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) the gastrointestinal (GI) tract has emerged as an important organ influencing the propensity to and potentially the severity of the related COVID-19 disease. However, the contribution of the SARS-CoV-2 intestinal infection on COVID-19 pathogenesis remains to be clarified. In this exploratory study, we highlighted a possible link between alterations in the composition of the gut microbiota and the levels of SARS-CoV-2 RNA in the gastrointestinal tract, which could be more important than the presence of SARS-CoV-2 in the respiratory tract, COVID-19 severity and GI symptoms. As established by metaproteomics, altered molecular functions in the microbiota profiles of high SARS-CoV-2 RNA level faeces highlight mechanisms such as inflammation-induced enterocyte damage, increased intestinal permeability and activation of immune response that may contribute to vicious cycles. Uncovering the role of this gut microbiota dysbiosis could drive the investigation of alternative therapeutic strategies to favour the clearance of the virus and potentially mitigate the effect of the SARS-CoV-2 infection.

Heterogeneity of SARS-CoV-2 virus produced in cell culture revealed by shotgun proteomics and supported by genome sequencing.

COVID-19 is the most disturbing pandemic of the past hundred years. Its causative agent, the SARS-CoV-2 virus, has been the subject of an unprecedented investigation to characterize its molecular structure and intimate functioning. While markers for its detection have been proposed and several diagnostic methodologies developed, its propensity to evolve and evade diagnostic tools and the immune response is of great concern. The recent spread of new variants with increased infectivity requires even more attention. Here, we document how shotgun proteomics can be useful for rapidly monitoring the evolution of the SARS-CoV-2 virus. We evaluated the heterogeneity of purified SARS-CoV-2 virus obtained after culturing in the Vero E6 cell line. We found that cell culture induces significant changes that are translated at the protein level, such changes being detectable by tandem mass spectrometry. Production of viral particles requires careful quality control which can be easily performed by shotgun proteomics. Although considered relatively stable so far, the SARS-CoV-2 genome turns out to be prone to frequent variations. Therefore, the sequencing of SARS-CoV-2 variants from patients reporting only the consensus genome after its amplification would deserve more attention and could benefit from more in-depth analysis of low level but crystal-clear signals, as well as complementary and rapid analysis by shotgun proteomics.

Shotgun proteomics analysis of SARS-CoV-2-infected cells and how it can optimize whole viral particle antigen production for vaccines.

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) has resulted in a pandemic and is continuing to spread rapidly around the globe. No effective vaccine is currently available to prevent COVID-19, and intense efforts are being invested worldwide into vaccine development. In this context, all technology platforms must overcome several challenges resulting from the use of an incompletely characterized new virus. These include finding the right conditions for virus amplification for the development of vaccines based on inactivated or attenuated whole viral particles. Here, we describe a shotgun tandem mass spectrometry workflow, the data produced can be used to guide optimization of the conditions for viral amplification. In parallel, we analysed the changes occurring in the host cell proteome following SARS-CoV-2 infection to glean information on the biological processes modulated by the virus that could be further explored as potential drug targets to deal with the pandemic.

Alterations in gene expression in cultured human cells after acute exposure to uranium salt: Involvement of a mineralization regulator.

The risk of exposure of workers or populations to materials, such as uranium, of nuclear fuel process origins is a major concern worldwide. Our goal is to improve the knowledge of mechanisms ruling its chemical toxicity, and to search for proteins as potential indicator of effect. Such a marker of internal damage remains to be discovered in the case of uranium. This study, based on DNA microarrays, reports a comparative gene expression analysis following acute uranium exposure of several human cell lines taken from kidneys or lungs as representative targets. Among uranium altered genes, no common gene was found between cells originating from lungs and kidney. In contrast, a set of 24 altered genes was common to two kidney cell lines. Transcriptional levels of a subset of renal genes were assessed with qRT-PCR. Furthermore, we highlighted a gene (SPP1) coding for a secreted protein (osteopontin) linked to ectopic mineralization. Immunoblotting assays showed that uranyl ions affect the excretion of osteopontin in a time- and dose-dependent manner. We consider that osteopontin, described as associated with bone resorbtion and kidney mineral stones, is a worthwhile candidate to be tested in vivo as a potential indicator of uranyl mineralization effects.

Global gene expression profiling in human lung cells exposed to cobalt.

BACKGROUND: It has been estimated that more than 1 million workers in the United States are exposed to cobalt. Occupational exposure to 59 Co occurs mainly via inhalation and leads to various lung diseases. Cobalt is classified by the IARC as a possible human carcinogen (group 2B). Although there is evidence for in vivo and in vitro toxicity, the mechanisms of cobalt-induced lung toxicity are not fully known. The purpose of this work was to identify potential signatures of acute cobalt exposure using a toxicogenomic approach. Data analysis focused on some cellular processes and protein targets that are thought to be relevant for carcinogenesis, transport and biomarker research. RESULTS: A time course transcriptome analysis was performed on A549 human pulmonary cells, leading to the identification of 85 genes which are repressed or induced in response to soluble 59 Co. A group of 29 of these genes, representing the main biological functions, was assessed by quantitative RT-PCR. The expression profiles of six of them were then tested by quantitative RT-PCR in a time-dependent manner and three modulations were confirmed by Western blotting. The 85 modulated genes include potential cobalt carriers (FBXL2, ZNT1, SLC12A5), tumor suppressors or transcription factors (MAZ, DLG1, MYC, AXL) and genes linked to the stress response (UBC, HSPCB, BNIP3L). We also identified nine genes coding for secreted proteins as candidates for biomarker research. Of those, TIMP2 was found to be down-regulated and this modulation was confirmed, in a dose-dependent manner, at protein level in the supernatant of exposed cells. CONCLUSION: Most of these genes have never been described as related to cobalt stress and provide original hypotheses for further study of the effects of this metal ion on human lung epithelial cells. A putative biomarker of cobalt toxicity was identified.

Copper-mediated homo-dimerisation for the HAH1 metallochaperone.

The HAH1 metallochaperone is a key protein implicated in copper homeostasis in human cells. Using as solid-phase based assay completed with Biacore studies, we provided evidence that HAH1 forms homo-dimers in the presence of copper. Biacore analysis allowed us to determine the kinetic parameters of this interaction, characterised by an apparent affinity constant of 6muM. Moreover, we demonstrated that copper-loaded HAH1 interacts independently with each of the six individual metal-binding domains of the copper-translocating Menkes ATPase. Finally, the homo-dimerisation of the metallochaperone was confirmed in living cells by using fluorescence resonance energy transfer. Results have been discussed in the context of intracellular copper control.