bims-mevinf 2024-08-11 papers

iScience. 2024 Aug 16. 27(8): 110424

Influenza A virus infection activates STAT3 to enhance SREBP2 expression, cholesterol biosynthesis, and virus replication.

Jingting Zhang, Yunhan Wu, Yujie Wang, Penggang Liu, Kaituo Liu, Jing Sun, Pinghu Zhang, Xiaoquan Wang, Xiufan Liu, Xiulong Xu.

Cellular cholesterol plays an important role in influenza A virus (IAV) endocytosis and replication. However, how IAV infection regulates cholesterol biosynthesis remains poorly understood. Here, we report that IAV infection activates SREBP2 and induces the expression of HMGCR, a rate-limiting enzyme in cholesterol synthesis pathway. SREBP2 deficiency suppresses IAV-induced HMGCR expression and virus replication. Mechanistically, IAV infection activates JAK2 and STAT3, inhibition of JAK2 and STAT3 activity by their inhibitors or by gene knockout downregulates IAV-induced SREBP2 and HMGCR expression and IAV replication, reduces the content of cellular cholesterol and virus binding to host cells. Exogenous cholesterol reverses the inhibitory effect of S3I-201 and STAT3 deficiency on virus replication. STAT3 or JAK2 overexpression increases the expression of SREBP2 and its downstream target genes, leading to increased IAV replication. These observations collectively suggest that STAT3 activation facilitates IAV replication by inducing SREBP2 expression and increasing cholesterol biosynthesis.

Keywords: Genetics; Virology

DOI: https://doi.org/10.1016/j.isci.2024.110424

Mol Biol Cell. 2024 Aug 07. mbcE24050236

Proviral role of ATG2 autophagy related protein in tomato bushy stunt virus replication through bulk phospholipid transfer into the viral replication organelle.

Yuanrong Kang, Judit Pogany, Peter D Nagy.

Subversion of cellular membranes and membrane proliferation are used by positive-strand RNA viruses to build viral replication organelles (VROs) that support virus replication. The biogenesis of the membranous VROs requires major changes in lipid metabolism and lipid transfer in infected cells. In this work, we show that tomato bushy stunt virus (TBSV) hijacks Atg2 autophagy related protein with bulk lipid transfer activity into VROs via interaction with TBSV p33 replication protein. Deletion of Atg2 in yeast and knockdown of Atg2 in Nicotiana benthamiana resulted in decreased TBSV replication. We found that subversion of Atg2 by TBSV was important to enrich VRO membranes with phosphatidylethanolamine (PE), phosphatidylserine (PS) and PI(3)P phosphoinositide. Interestingly, inhibition of authophagy did not affect efficient recruitment of Atg2 into VROs and over-expression of Atg2 enhanced TBSV replication, indicating autophagy-independent subversion of Atg2 by TBSV. These findings suggest that the pro-viral function of Atg2 lipid transfer protein is in VRO membrane proliferation. In addition, we find that Atg2 interacting partner Atg9 with membrane lipid scramblase activity is also co-opted for tombusvirus replication. Altogether, subversion of Atg2 bridge-type lipid transfer protein provides a new mechanism for tombusviruses to greatly expand VRO membranes to support robust viral replication.

DOI: https://doi.org/10.1091/mbc.E24-05-0236

Front Immunol. 2024 ;15 1435180

Signals from intestinal microbiota mediate the crosstalk between the lung-gut axis in an influenza infection mouse model.

Yijia Zhang, Youdi Wan, Xin Xin, Yixuan Qiao, Wenna Qiao, Jihui Ping, Juan Su.

Introduction: Introduction: The influenza virus primarily targets the respiratory tract, yet both the respiratory and intestinal systems suffer damage during infection. The connection between lung and intestinal damage remains unclear.
Methods: Our experiment employs 16S rRNA technology and Liquid Chromatography-Mass Spectrometry (LC-MS) to detect the impact of influenza virus infection on the fecal content and metabolites in mice. Additionally, it investigates the effect of influenza virus infection on intestinal damage and its underlying mechanisms through HE staining, Western blot, Q-PCR, and flow cytometry.
Results: Our study found that influenza virus infection caused significant damage to both the lungs and intestines, with the virus detected exclusively in the lungs. Antibiotic treatment worsened the severity of lung and intestinal damage. Moreover, mRNA levels of Toll-like receptor 7 (TLR7) and Interferon-b (IFN-b) significantly increased in the lungs post-infection. Analysis of intestinal microbiota revealed notable shifts in composition after influenza infection, including increased Enterobacteriaceae and decreased Lactobacillaceae. Conversely, antibiotic treatment reduced microbial diversity, notably affecting Firmicutes, Proteobacteria, and Bacteroidetes. Metabolomics showed altered amino acid metabolism pathways due to influenza infection and antibiotics. Abnormal expression of indoleamine 2,3-dioxygenase 1 (IDO1) in the colon disrupted the balance between helper T17 cells (Th17) and regulatory T cells (Treg cells) in the intestine. Mice infected with the influenza virus and supplemented with tryptophan and Lactobacillus showed reduced lung and intestinal damage, decreased Enterobacteriaceae levels in the intestine, and decreased IDO1 activity.
Discussion: Overall, influenza infection caused damage to lung and intestinal tissues, disrupted intestinal microbiota and metabolites, and affected Th17/Treg balance. Antibiotic treatment exacerbated these effects. Supplementation with tryptophan and Lactobacillus improved lung and intestinal health, highlighting a new understanding of the lung-intestine connection in influenza-induced intestinal disease.

Keywords: Lactobacillus; gut-lung axis; influenza A virus; intestinal microbiota; tryptophan metabolism

DOI: https://doi.org/10.3389/fimmu.2024.1435180

Metabolomics. 2024 Aug 03. 20(5): 92

Characterising the urinary acylcarnitine and amino acid profiles of HIV/TB co-infection, using LC-MS metabolomics.

Charles Pretorius, Laneke Luies.

INTRODUCTION: The human immunodeficiency virus (HIV) and tuberculosis (TB) co-infection presents significant challenges due to the complex interplay between these diseases, leading to exacerbated metabolic disturbances. Understanding these metabolic profiles is crucial for improving diagnostic and therapeutic approaches.
OBJECTIVE: This study aimed to characterise the urinary acylcarnitine and amino acid profiles, including 5-hydroxyindoleacetic acid (5-HIAA), in patients co-infected with HIV and TB using targeted liquid chromatography mass spectrometry (LC-MS) metabolomics.
METHODS: Urine samples, categorised into HIV, TB, HIV/TB co-infected, and healthy controls, were analysed using HPLC-MS/MS. Statistical analyses included one-way ANOVA and a Kruskal-Wallis test to determine significant differences in the acylcarnitine and amino acid profiles between groups.
RESULTS: The study revealed significant metabolic alterations, especially in TB and co-infected groups. Elevated levels of medium-chain acylcarnitines indicated increased fatty acid oxidation, commonly associated with cachexia in TB. Altered amino acid profiles suggested disruptions in protein and glucose metabolism, indicating a shift towards diabetes-like metabolic states. Notably, TB was identified as a primary driver of these changes, affecting protein turnover, and impacting energy metabolism in co-infected patients.
CONCLUSION: The metabolic profiling of HIV/TB co-infection highlights the profound impact of TB on metabolic pathways, which may exacerbate the clinical complexities of co-infection. Understanding these metabolic disruptions can guide the development of targeted treatments and improve management strategies, ultimately enhancing the clinical outcomes for these patients. Further research is required to validate these findings and explore their implications in larger, diverse populations.

Keywords: 5-HIAA; Acylcarnitines; Amino acids; HIV/TB co-infection; LC–MS; Metabolomics

DOI: https://doi.org/10.1007/s11306-024-02161-8

Hepatol Int. 2024 Aug 08.

Dual-etiology MAFLD: the interactions between viral hepatitis B, viral hepatitis C, alcohol, and MAFLD.

Chun-Jen Liu, Wai Kay Seto, Ming-Lung Yu.

Metabolic dysfunction-associated fatty liver disease (MAFLD) and viral hepatitis due to chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection are common liver diseases worldwide. Excessive alcohol consumption and alcoholic liver disease (ALD) are also emerging health problems. Therefore, in clinical practice, we may encounter subjects with dual etiology of liver diseases such as coexisting MAFLD/HBV, MAFLD/HCV, and MAFLD/ALD. In this review, we summarize the epidemiology, clinical features, and mutual interactions of MAFLD with coexisting HBV, HCV, or ALD. The impact of MAFLD on the progression of liver diseases and treatment outcomes in patients with chronic viral hepatitis and the clinical questions to be addressed regarding dual MAFLD and ALD are also discussed.

Keywords: Alcoholic liver disease; Fatty liver; Hepatitis B virus; Hepatitis C virus; Steatohepatitis; Steatosis

DOI: https://doi.org/10.1007/s12072-024-10699-x

mBio. 2024 Aug 08. e0107724

SARS-CoV-2 spike fusion peptide trans interaction with phosphatidylserine lipid triggers membrane fusion for viral entry.

Puspangana Singh, Purba Pahari, Srija Mukherjee, Sharmistha Karmakar, Markus Hoffmann, Taraknath Mandal, Dibyendu Kumar Das.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike is the fusion machine for host cell entry. Still, the mechanism by which spike protein interacts with the target lipid membrane to facilitate membrane fusion during entry is not fully understood. Here, using steady-state membrane fusion and single-molecule fluorescence resonance energy transfer imaging of spike trimers on the surface of SARS-CoV-2 pseudovirion, we directly show that spike protein interacts with phosphatidylserine (PS) lipid in the target membrane for mediating fusion. We observed that the fusion peptide of the spike S2 domain interacts with the PS lipid of the target membrane. Low pH and Ca2+ trigger the spike conformational change and bring fusion peptide in close proximity to the PS lipid of the membrane. The binding of the spike with PS lipid of its viral membrane (cis interaction) impedes the fusion activation. PS on the target membrane promotes spike binding via trans interaction, prevents the cis interaction, and accelerates fusion. Sequestering or absence of PS lipid abrogates the spike-mediated fusion process and restricts SARS-CoV-2 infectivity. We found that PS-dependent interaction for fusion is conserved across all the SARS-CoV-2 spike variants of concern (D614G, Alpha, Beta, Delta, and Omicron). Our study suggests that PS lipid is indispensable for SARS-CoV-2 spike-mediated virus and target membrane fusion for entry, and restricting PS interaction with spike inhibits the SARS-CoV-2 spike-mediated entry. Therefore, PS is an important cofactor and acts as a molecular beacon in the target membrane for SARS-CoV-2 entry.
IMPORTANCE: The role of lipids in the host cell target membrane for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry is not clear. We do not know whether SARS-CoV-2 spike protein has any specificity in terms of lipid for membrane fusion reaction. Here, using in vitro reconstitution of membrane fusion assay and single-molecule fluorescence resonance energy transfer imaging of SARS-CoV-2 spike trimers on the surface of the virion, we have demonstrated that phosphatidylserine (PS) lipid plays a key role in SARS-CoV-2 spike-mediated membrane fusion reaction for entry. Membrane-externalized PS lipid strongly promotes spike-mediated membrane fusion and COVID-19 infection. Blocking externalized PS lipid with PS-binding protein or in the absence of PS, SARS-CoV-2 spike-mediated fusion is strongly inhibited. Therefore, PS is an important target for restricting viral entry and intervening spike, and PS interaction presents new targets for COVID-19 interventions.

Keywords: SARS-CoV-2; conformational dynamics; lipid; membrane fusion; smFRET; virus entry

DOI: https://doi.org/10.1128/mbio.01077-24