Iron overload down-regulates the expression of the HIV-1 Rev cofactor eIF5A in infected T lymphocytes

Background Changes in iron metabolism frequently accompany HIV-1 infection. However, while many clinical and in vitro studies report iron overload exacerbates the development of infection, many others have found no correlation. Therefore, the multi-faceted role of iron in HIV-1 infection remains enigmatic. Methods RT-qPCR targeting the LTR region, gag, Tat and Rev were performed to measure the levels of viral RNAs in response to iron overload. Spike-in SILAC proteomics comparing i) iron-treated, ii) HIV-1-infected and iii) HIV-1-infected/iron treated T lymphocytes was performed to define modifications in the host cell proteome. Data from quantitative proteomics were integrated with the HIV-1 Human Interaction Database for assessing any viral cofactors modulated by iron overload in infected T lymphocytes. Results Here, we demonstrate that the iron overload down-regulates HIV-1 gene expression by decreasing the levels of viral RNAs. In addition, we found that iron overload modulates the expression of many viral cofactors. Among them, the downregulation of the REV cofactor eIF5A may correlate with the iron-induced inhibition of HIV-1 gene expression. Therefore, we demonstrated that eiF5A downregulation by shRNA resulted in a significant decrease of Nef levels, thus hampering HIV-1 replication. Conclusions Our study indicates that HIV-1 cofactors influenced by iron metabolism represent potential targets for antiretroviral therapy and suggests eIF5A as a selective target for drug development

AMBRA1 regulates mitophagy by interacting with ATAD3A and promoting PINK1 stability

PINK1 accumulation at the outer mitochondrial membrane (OMM) is a key event required to signal depolarized mitochondria to the autophagy machinery. How this early step is, in turn, modulated by autophagy proteins remains less characterized. Here, we show that, upon mitochondrial depolarization, the proautophagic protein AMBRA1 is recruited to the OMM and interacts with PINK1 and ATAD3A, a transmembrane protein that mediates mitochondrial import and degradation of PINK1. Downregulation of AMBRA1 expression results in reduced levels of PINK1 due to its enhanced degradation by the mitochondrial protease LONP1, which leads to a decrease in PINK1-mediated ubiquitin phosphorylation and mitochondrial PRKN/PARKIN recruitment. Notably, ATAD3A silencing rescues defective PINK1 accumulation in AMBRA1-deficient cells upon mitochondrial damage. Overall, our findings underline an upstream contribution of AMBRA1 in the control of PINK1-PRKN mitophagy by interacting with ATAD3A and promoting PINK1 stability. This novel regulatory element may account for changes of PINK1 levels in neuropathological conditions.Abbreviations: ACTB/β-actin: actin beta; AMBRA1: autophagy and beclin 1 regulator 1; ATAD3A: ATPase family AAA domain containing 3A; BCL2L1/BCL-xL: BCL2 like 1; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; OMA1: OMA1 zinc metallopeptidase; OMM: outer mitochondrial membrane; PARL: presenilin associated rhomboid like; PARP: poly(ADP-ribose) polymerase; PD: Parkinson disease; PINK1: PTEN induced kinase 1; PRKN/PARKIN: parkin RBR E3 ubiquitin protein ligase; SDHA: succinate dehydrogenase complex flavoprotein subunit A; TOMM70: translocase of outer mitochondrial membrane 70

Covid-19 and the role of smoking: the protocol of the multicentric prospective study COSMO-IT (COvid19 and SMOking in ITaly).

The emergency caused by Covid-19 pandemic raised interest in studying lifestyles and comorbidities as important determinants of poor Covid-19 prognosis. Data on tobacco smoking, alcohol consumption and obesity are still limited, while no data are available on the role of e-cigarettes and heated tobacco products (HTP). To clarify the role of tobacco smoking and other lifestyle habits on COVID-19 severity and progression, we designed a longitudinal observational study titled COvid19 and SMOking in ITaly (COSMO-IT). About 30 Italian hospitals in North, Centre and South of Italy joined the study. Its main aims are: 1) to quantify the role of tobacco smoking and smoking cessation on the severity and progression of COVID-19 in hospitalized patients; 2) to compare smoking prevalence and severity of the disease in relation to smoking in hospitalized COVID-19 patients versus patients treated at home; 3) to quantify the association between other lifestyle factors, such as e-cigarette and HTP use, alcohol and obesity and the risk of unfavourable COVID-19 outcomes. Socio-demographic, lifestyle and medical history information will be gathered for around 3000 hospitalized and 700-1000 home-isolated, laboratory-confirmed, COVID-19 patients. Given the current absence of a vaccine against SARS-COV-2 and the lack of a specific treatment for -COVID-19, prevention strategies are of extreme importance. This project, designed to highly contribute to the international scientific debate on the role of avoidable lifestyle habits on COVID-19 severity, will provide valuable epidemiological data in order to support important recommendations to prevent COVID-19 incidence, progression and mortality

Autophagy in HCV infection: keeping fat and inflammation at bay

Hepatitis C virus (HCV) infection is one of the main causes of chronic liver disease. Viral persistence and pathogenesis rely mainly on the ability of HCV to deregulate specific host processes, including lipid metabolism and innate immunity. Recently, autophagy has emerged as a cellular pathway, playing a role in several aspects of HCV infection. This review summarizes current knowledge on the molecular mechanisms that link the HCV life cycle with autophagy machinery. In particular, we discuss the role of HCV/autophagy interaction in dysregulating inflammation and lipid homeostasis and its potential for translational applications in the treatment of HCV-infected patients

Proteomic analysis identifies the RNA helicase DDX3X as a host target against SARS-CoV-2 infection

COVID-19 is currently a highly pressing health threat and therapeutic strategies to mitigate the infection impact are urgently needed. Characterization of the SARS-CoV-2 interactome in infected cells may represent a powerful tool to identify cellular proteins hijacked by viruses for their life cycle and develop host-oriented antiviral therapeutics. Here we report the proteomic characterization of host proteins interacting with SARS-CoV-2 Nucleoprotein in infected Vero E6 cells. We identified 24 high-confidence proteins mainly playing a role in RNA metabolism and translation, including RNA helicases and scaffold proteins involved in the formation of stress granules, cytoplasmic aggregates of messenger ribonucleoproteins that accumulate as a result of stress-induced translation arrest. Analysis of stress granules upon SARS-CoV-2 infection showed that these structures are not induced in infected cells, neither eIF2α phosphorylation, an upstream event leading to stress-induced translation inhibition. Notably, we found that G3BP1, a stress granule component that associates with the Nucleoprotein, is required for efficient SARS-CoV-2 replication. Moreover, we showed that the Nucleoprotein-interacting RNA helicase DDX3X colocalizes with viral RNA foci and its inhibition by small molecules or small interfering RNAs significantly reduces viral replication. Altogether, these results indicate that SARS-CoV-2 subverts the stress granule machinery and exploits G3BP1 and DDX3X for its replication cycle, offering groundwork for future development of host-directed therapies

Negative regulation of MAVS‐mediated antiviral signaling by the mitochondrial protein LRPPRC during HCV infection

Hepatitis C virus (HCV) is highly efficient in establishing a chronic infection, having evolved multiple strategies to suppress the host antiviral responses. The HCV non-structural 5A (NS5A) protein, in addition to its role in viral replication and assembly, has long been known to hamper the interferon (IFN) response. However, the mechanism of this inhibitory activity of NS5A remains partly characterized. In a functional proteomic screening carried out in HCV replicon cells, we identified the mitochondrial protein LRPPRC as an NS5A binding factor. Notably, we found that downregulation of LRPPRC expression results in a significant inhibition of HCV infection, which is associated to an increased activation of the IFN response. Moreover, we showed that LRPPRC acts as a negative regulator of the mitochondrial-mediated antiviral immunity, by interacting with MAVS and inhibiting its association with TRAF3 and TRAF6. Finally, we demonstrated that NS5A is able to interfere with MAVS activity in a LRPPRC-dependent manner. Overall, our results indicate that NS5A contributes to the inhibition of innate immune pathways during HCV infection by exploiting the ability of LRPPRC to inhibit MAVS-regulated antiviral signaling. This article is protected by copyright. All rights reserved

Chylothorax found in a patient with COVID-19

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its clinical spectrum ranges from mild to moderate or severe illness. A 78-year-old male was presented at emergency department with dyspnoea, dry cough and severe asthenia. The nasopharyngeal swab by real-time polymerase chain reaction confirmed a SARS-CoV-2 infection. The x-ray and the thoracic ultrasound revealed right pleural effusion. A diagnostic-therapeutic thoracentesis drained fluid identified as chylothorax. Subsequently, the patient underwent a chest computed tomography which showed the radiological hallmarks of COVID-19 and in the following weeks he underwent a chest magnetic resonance imaging to obtain a better view of mediastinal and lymphatic structures, which showed a partial thrombosis affecting the origin of superior vena cava and the distal tract of the right subclavian vein. For this reason, anticoagulant therapy was optimized and in the following weeks the patient was discharged for clinical and radiological improvement. This case demonstrates chylothorax as a possible and uncommon complication of COVID-19

High Levels of TRIM5α Are Associated with Xenophagy in HIV-1-Infected Long-Term Nonprogressors

Autophagy is a lysosomal-dependent degradative mechanism essential in maintaining cellular homeostasis, but it is also considered an ancient form of innate eukaryotic fighting against invading microorganisms. Mounting evidence has shown that HIV-1 is a critical target of autophagy that plays a role in HIV-1 replication and disease progression. In a special subset of HIV-1-infected patients that spontaneously and durably maintain extremely low viral replication, namely, long-term nonprogressors (LTNP), the resistance to HIV-1-induced pathogenesis is accompanied, in vivo, by a significant increase in the autophagic activity in peripheral blood mononuclear cells. Recently, a new player in the battle of autophagy against HIV-1 has been identified, namely, tripartite motif protein 5α (TRIM5α). In vitro data demonstrated that TRIM5α directly recognizes HIV-1 and targets it for autophagic destruction, thus protecting cells against HIV-1 infection. In this paper, we analyzed the involvement of this factor in the control of HIV-1 infection through autophagy, in vivo, in LTNP. The results obtained showed significantly higher levels of TRIM5α expression in cells from LTNP with respect to HIV-1-infected normal progressor patients. Interestingly, the colocalization of TRIM5α and HIV-1 proteins in autophagic vacuoles in LTNP cells suggested the participation of TRIM5α in the autophagy containment of HIV-1 in LTNP. Altogether, our results point to a protective role of TRIM5α in the successful control of the chronic viral infection in HIV-1-controllers through the autophagy mechanism. In our opinion, these findings could be relevant in fighting against HIV-1 disease, because autophagy inducers might be employed in combination with antiretroviral drugs