Influenza A virus infection induces liver injury in mice

Influenza A virus dissemination and infection leads to tissue resident cell injury and dysfunction in viral sepsis

BACKGROUND

Severe respiratory viral infections can lead to viral sepsis (VS), a life-threatening condition characterized by lung and extrapulmonary organ dysfunction. However, the pathology of VS is not clear. Specifically, it is unknown how the cytokine storm and direct virus infection contribute to the damage of extrapulmonary organs.

METHODS

In this study, we established survival and lethal mouse models of VS by intranasally administering different doses of PR8/H1N1 influenza virus in C57BL/6J male mice, as well as model of bacterial sepsis (BS) caused by Streptococcus pneumoniae as references. Viraemia and extrapulmonary dissemination and infection of the virus were examined. Single-cell sequencing of the lungs and livers was performed at different days post-infection (dpi) in three groups.

FINDINGS

While bacteria can spread and colonize extensively in extrapulmonary organs, causing multiple organ injuries, IAVs mainly replicate and cause damage in pulmonary cells. Live virus can be isolated in the blood and extrapulmonary organs. Disseminating via the bloodstream, IAVs transiently infect the liver and spleen, causing liver dysfunction and spleen atrophy, without affecting kidney function, despite systematically elevated cytokine levels. Compared to BS, a more significant decrease in the proportion of alveolar macrophages, epithelial cells, endothelial cells, and fibroblasts in the lungs, as well as endothelial cells and Kupffer cells in the liver, was observed in VS. This was accompanied by a longer activated PANoptosis pathway and downregulated genes responsible for barrier function and antigen presentation in the epithelial and endothelial cells.

INTERPRETATION

Our study suggests that H1N1 influenza virus disseminates through the bloodstream and infects extrapulmonary organs to varying extents, which may lead to differential cell death, organ dysfunction, and trigger VS.

FUNDING

This research was supported by the National Natural Science Foundation of China (82241056, 82170015, 82030002, 82470007, 824B2001), the National Key R&D Program of China (2023YFC2306300), Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2021-I2M-1-048), the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine (ZYYCXTD-D-202208), New Cornerstone Science Foundation, National High Level Hospital Clinical Research Funding (2024-NHLHCRF-LX-01-0101, 2024-NHLHCRF-LX-01-0102), Beijing Research Ward Excellence Program (BRWEP2024W114060103), Noncommunicable Chronic Diseases-National Science and Technology Major Project (2023ZD0506200, 2023ZD0506203) and Special Research Fund for Central Universities, Peking Union Medical College (3332024193).

Characterization of serum metabolome and respiratory microbiota in children with influenza A virus infection

The risk of children being infected with Influenza A virus (IAV) is high, and if not treated promptly, it can lead to serious illness. Compared with control group, IAV infection decreased the contents of platelet, white blood cell, lymphocyte, eosinophil, basophil, CD3+ T cells, CD4+ T cells, CD8+ T cells, and B cells, while increasing the number of red blood cell. Additionally, IAV infection increased serum concentrations of total protein, albumin and lipase, while decreasing the contents of calcium, triglyceride, total bilirubin, direct bilirubin, indirect bilirubin and gamma-glutamyltransferase. However, the interactions between the respiratory microbiome and metabolites and their impact on IAV in children remains unclear. Ultra performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF/MS) and 16S rRNA gene sequencing were employed to analysis the respiratory microbiome and serum metabolic characteristics of 85 patients with IAV infection and age-matched 55 controls with respiratory disease who tested negative for 13 types of respiratory pathogens. The serum metabolic profile of IAV patients was significantly changed, and the purine metabolism was destroyed. Purine metabolism was also enriched in H3N2 patients compared to H1N1, with increased xanthine, deoxyguanosine, and inosine. The respiratory microbiome structure in children with IAV, including H1N1 and H3N2, was significantly different from that of the control, with significantly increased Chao index. The Mantel test revealed the correlation and consistency in the trends of Haemophilus, Ureaplasma and Inosine. This study revealed the characteristics of the respiratory microbiome and serum metabolites in pediatric patients with IAV, providing a new direction for exploring the pathogenesis of IAV in children.

Hospitalized children with influenza A before, during and after COVID-19 pandemic: a retrospective cohort study

CONTEXT

Since the outbreak of COVID-19 in late 2019, the transmission dynamics and clinical presentation patterns of influenza A (Flu A) virus have undergone changes.

OBJECTIVES

This article conducted a comparative analysis in clinical characteristics and laboratory results of pediatric patients with Flu A before, during, and after the COVID-19 pandemic.

METHODS

The medical records of 885 children hospitalized with Flu A virus infection at a tertiary hospital in Guangdong Province, China, were retrospectively analyzed. Flu A was confirmed in these cases using a direct immunofluorescence antigen assay. The clinical data for this study span from January 1, 2018, to May 31, 2023.

RESULTS

In our study, we observed a total of 340 cases before the COVID-19 pandemic, 196 cases during the pandemic, and 349 cases after the pandemic. Patients after the pandemic had a higher median age on admission (5.66 years, range 3.41-7.70) and exhibited more respiratory symptoms such as cough, sore throat, and nasal stuffiness. The length of hospital stay was longer, and there was a higher percentage of patients with fever duration ≥ 5 days among Flu A patients during the pandemic. Compared to before and during the COVID-19 pandemic, Flu A patients after the pandemic showed significantly reduced white blood cell (WBC) and platelet (PLT) counts (P < 0.001), along with elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in laboratory indexes (P < 0.001). Furthermore, more hospitalized children after the pandemic were diagnosed with benign acute childhood myositis (BACM).

CONCLUSION

Our research results indicates a significant decrease in Flu A cases during the COVID-19 pandemic, and hospitalized children with Flu A have more severe clinical symptoms after the COVID-19 pandemic. These findings have implications for public health policy and clinical management of Flu A cases.

CLINICAL TRIAL NUMBER

Not applicable.

Foot-and-mouth disease virus 2B protein antagonizes STING-induced antiviral activity by targeting YTHDF2

Foot-and-mouth disease virus (FMDV) infection modulates the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) pathways to inhibit the innate immune responses in the host. However, the mechanism by which FMDV antagonizes the DNA-induced signaling pathway remains to be clarified. In this study, we determined that FMDV infection inhibited stimulator of interferon genes (STING) at the levels of both mRNA and protein expression, and FMDV 2B and 3Cpro proteins promoted STING decline. FMDV 3Cpro induced the decrease in STING depending on its protease activity. FMDV 2B reduced STING expression by disrupting its mRNA level. Mechanistically, 2B inhibited the mRNA of STING by recruiting YTH m6A RNA-binding protein 2 (YTHDF2) to bind to STING mRNA, repressing the generation of FMDV-induced type-I interferon and facilitating virus replication. This effect was triggered by residue 105 of 2B. The 2B K105A mutant FMDV was successfully rescued, and further studies showed that the pathogenicity was attenuated by mutation at site K105 of FMDV 2B. YTHDF2 also promoted FMDV replication through interferon-dependent and interferon-independent pathways. Moreover, YTHDF2-deficient mice showed stronger resistance to FMDV infection. Our study reveals a potential mechanism for FMDV 2B negatively modulating innate immunity at transcriptional levels, promoting the understanding of immune evasion and YTHDF2 function in the FMDV infection process.

Foot-and-mouth disease virus VP1 degrades YTHDF2 through autophagy to regulate IRF3 activity for viral replication

Many viruses, including foot-and-mouth disease virus (FMDV), can promote the degradation of host proteins through macroautophagy/autophagy, thereby promoting viral replication. However, the regulatory mechanism between autophagy and innate immune responses is not fully understood during FMDV infection. Here, we found that the host GTPBP4/NOG1 (GTP binding protein 4) is a negative regulator of innate immune responses. GTPBP4 deficiency promotes the antiviral innate immune response, resulting in the ability of GTPBP4 to promote FMDV replication. Meanwhile, GTPBP4-deficient mice are more resistant to FMDV infection. To antagonize the host's antiviral immunity, FMDV structural protein VP1 promotes the expression of GTPBP4, and the 209th site of VP1 is responsible for this effect. Mechanically, FMDV VP1 promotes autophagy during virus infection and interacts with and degrades YTHDF2 (YTH N6-methyladenosine RNA binding protein F2) in an AKT-MTOR-dependent autophagy pathway, resulting in an increase in GTPBP4 mRNA and protein levels. Increased GTPBP4 inhibits IRF3 binding to the Ifnb/Ifn-β promoter, suppressing FMDV-induced type I interferon production. In conclusion, our study revealed an underlying mechanism of how VP1 negatively regulates innate immunity through the autophagy pathway, which would contribute to understanding the negative regulation of host innate immune responses and the function of GTPBP4 and YTHDF2 during FMDV infection.Abbreviation: 3-MA:3-methyladenine; ACTB: actin beta; ATG: autophagy related; ChIP:chromatin immunoprecipitation; CQ: chloroquine; DAPI:4',6-diamidino-2-phenylindole; dpi: days post-infection; EV71:enterovirus 71; FMDV: foot-and-mouth disease virus; GTPBP4/NOG1: GTPbinding protein 4; HIF1A: hypoxia inducible factor 1 subunit alpha;hpt:hours post-transfection; IFNB/IFN-β:interferon beta; IRF3: interferon regulatory factor 3; MAP1LC3/LC3:microtubule associated protein 1 light chain 3; MAVS: mitochondriaantiviral signaling protein; MOI: multiplicity of infection; MTOR:mechanistic target of rapamycin kinase; m6A: N(6)-methyladenosine;qPCR:quantitativePCR; SIRT3:sirtuin 3; SQSTM1/p62: sequestosome 1; STING1: stimulator ofinterferon response cGAMP interactor 1; siRNA: small interfering RNA;TBK1: TANK binding kinase 1; TCID50:50% tissue culture infectious doses; ULK1: unc-51 like autophagyactivating kinase 1; UTR: untranslated region; WT: wild type; YTHDF2:YTH N6-methyladenosine RNA binding protein F2.

The Application of Aptamer and Research Progress in Liver Disease

Aptamers, as a kind of small-molecule nucleic acid, have attracted much attention since their discovery. Compared with biological reagents such as antibodies, aptamers have the advantages of small molecular weight, low immunogenicity, low cost, and easy modification. At present, aptamers are mainly used in disease biomarker discovery, disease diagnosis, treatment, and targeted drug delivery vectors. In the process of screening and optimizing aptamers, it is found that there are still many problems need to be solved such as the design of the library, optimization of screening conditions, the truncation of screened aptamer, and the stability and toxicity of the aptamer. In recent years, the incidence of liver-related diseases is increasing year by year and the treatment measures are relatively lacking, which has attracted the people's attention in the application of aptamers in liver diseases. This article mainly summarizes the research status of aptamers in disease diagnosis and treatment, especially focusing on the application of aptamers in liver diseases, showing the crucial significance of aptamers in the diagnosis and treatment of liver diseases, and the use of Discovery Studio software to find the binding target and sequence of aptamers, and explore their possible interaction sites.

NOG1 downregulates type I interferon production by targeting phosphorylated interferon regulatory factor 3

The innate immune system is the first line of the host's defense, and studying the mechanisms of the negative regulation of interferon (IFN) signaling is important for maintaining the balance of innate immune responses. Here, we found that the host GTP-binding protein 4 (NOG1) is a negative regulator of innate immune responses. Overexpression of NOG1 inhibited viral RNA- and DNA-mediated signaling pathways, and NOG1 deficiency promoted the antiviral innate immune response, resulting in the ability of NOG1 to promote viral replication. Vesicular stomatitis virus (VSV) and herpes simplex virus type 1 (HSV-1) infection induced a higher level of IFN-β protein in NOG1 deficient mice. Meanwhile, NOG1-deficient mice were more resistant to VSV and HSV-1 infection. NOG1 inhibited type I IFN production by targeting IRF3. NOG1 was also found to interact with phosphorylated IFN regulatory factor 3 (IRF3) to impair its DNA binding activity, thereby downregulating the transcription of IFN-β and downstream IFN-stimulated genes (ISGs). The GTP binding domain of NOG1 is responsible for this process. In conclusion, our study reveals an underlying mechanism of how NOG1 negatively regulates IFN-β by targeting IRF3, which uncovers a novel role of NOG1 in host innate immunity.

Jupytope: computational extraction of structural properties of viral epitopes

Epitope residues located on viral surface proteins are of immense interest in immunology and related applications such as vaccine development, disease diagnosis and drug design. Most tools rely on sequence-based statistical comparisons, such as information entropy of residue positions in aligned columns to infer location and properties of epitope sites. To facilitate cross-structural comparisons of epitopes on viral surface proteins, a python-based extraction tool implemented with Jupyter notebook is presented (Jupytope). Given a viral antigen structure of interest, a list of known epitope sites and a reference structure, the corresponding epitope structural properties can quickly be obtained. The tool integrates biopython modules for commonly used software such as NACCESS, DSSP as well as residue depth and outputs a list of structure-derived properties such as dihedral angles, solvent accessibility, residue depth and secondary structure that can be saved in several convenient data formats. To ensure correct spatial alignment, Jupytope takes a list of given epitope sites and their corresponding reference structure and aligns them before extracting the desired properties. Examples are demonstrated for epitopes of Influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) viral strains. The extracted properties assist detection of two Influenza subtypes and show potential in distinguishing between four major clades of SARS-CoV2, as compared with randomized labels. The tool will facilitate analytical and predictive works on viral epitopes through the extracted structural information. Jupytope and extracted datasets are available at https://github.com/shamimarashid/Jupytope.

Detection of Virus-Related Sequences Associated With Potential Etiologies of Hepatitis in Liver Tissue Samples From Rats, Mice, Shrews, and Bats

Hepatitis is a major global health concern. However, the etiology of 10-20% hepatitis cases remains unclear. Some hepatitis-associated viruses, like the hepatitis E virus, are zoonotic pathogens. Rats, shrews, and bats are reservoirs for many zoonotic pathogens. Therefore, understanding the virome in the liver of these animals is important for the investigation of the etiologies of hepatitis and monitoring the emerging zoonotic viruses. In this study, viral metagenomics and PCR methods were used to investigate viral communities in rats, mice, house shrews, and bats livers. Viral metagenomic analysis showed a diverse set of sequences in liver samples, comprising: sequences related to herpesviruses, orthomyxoviruses, anelloviruses, hepeviruses, hepadnaviruses, flaviviruses, parvoviruses, and picornaviruses. Using PCR methods, we first detected hepatovirus sequences in Hipposideros larvatus (3.85%). We also reported the first detection of Zika virus-related sequences in rats and house shrews. Sequences related to influenza A virus and herpesviruses were detected in liver. Higher detection rates of pegivirus sequences were found in liver tissue and serum samples from rats (7.85% and 15.79%, respectively) than from house shrews. Torque teno virus sequences had higher detection rates in the serum samples of rats and house shrews (52.72% and 5.26%, respectively) than in the liver. Near-full length genomes of pegivirus and torque teno virus were amplified. This study is the first to compare the viral communities in the liver of bats, rats, mice, and house shrews. Its findings expand our understanding of the virome in the liver of these animals and provide an insight into hepatitis-related viruses.

Is COVID-19-induced liver injury different from other RNA viruses?‎

Coronavirus disease 2019 is a pandemic disease caused by a novel RNA coronavirus, SARS coronavirus 2 (SARS-CoV-2), which is implicated in the respiratory system. SARS-CoV-2 also targets extrapulmonary systems, including the gastrointestinal tract, liver, central nervous system and others. SARS-CoV-2, like other RNA viruses, targets the liver and produces liver injury. This literature review showed that SARS-CoV-2-induced liver injury is different from other RNA viruses by a transient elevation of hepatic enzymes and does not progress to liver fibrosis or other unfavorable events. Moreover, SARS-CoV-2-induced liver injury usually occurs in the presence of risk factors, such as nonalcoholic liver fatty disease. This review highlights the important differences between RNA viruses inducing liver injury taking into consideration the clinical, biochemical, histopathological, postmortem findings and the chronicity of liver injury that ultimately leads to liver fibrosis and hepatocellular carcinoma.

Prognostic Significance of End-Stage Liver Diseases, Respiratory Tract Infection, and Chronic Kidney Diseases in Symptomatic Acute Hepatitis E

Symptomatic hepatitis E virus (HEV) infection is sporadic, and usually occurs in a limited number of infected patients, which hinders the investigation of risk factors for clinical outcomes in patients with acute HEV infection. A retrospective cohort study enrolling 1913 patients with symptomatic acute hepatitis E in Beijing 302 Hospital from January 1, 2001 to December 31, 2018 was conducted. The baseline characteristics, clinical features and laboratory data of these HEV infection cases were analyzed. Albumin (ALB), platelet (PLT), alanine aminotransferase (ALT), total bilirubin (T-BiL), international normalized ratio (INR) and serum creatinine (SCR) levels, along with the model for end-stage liver disease (MELD) score, hospitalization days, co-morbidity number and mortality were taken as major parameters for comparing the clinical manifestations in our study. We found that not all pre-existing chronic liver diseases exacerbate clinical manifestations of acute hepatitis E. Alcoholic hepatitis, fatty liver hepatitis, hepatic cyst, drug-induced hepatitis and hepatocellular carcinoma were not significantly associated with mortality of HEV patients. Among all of the comorbidities, end-stage liver diseases (ESLDs, including ascites, cirrhosis, hepatic coma and hepatorenal syndrome), respiratory tract infection and chronic kidney diseases (CKDs, including renal insufficiency and renal failure) were found to remarkably increase the mortality of patients with symptomatic HEV infection. Furthermore, the severity evaluation indexes (SEI), such as MELD score, duration of hospital stay, and co-morbidity number in HEV patients with underlying comorbidities were much worse than that of their counterparts without relevant comorbidities.

Beneficial effect of Indigo Naturalis on acute lung injury induced by influenza A virus

Background

Infections induced by influenza viruses, as well as coronavirus disease 19 (COVID-19) pandemic induced by severe acute respiratory coronavirus 2 (SARS-CoV-2) led to acute lung injury (ALI) and multi organ failure, during which traditional Chinese medicine (TCM) played an important role in treatment of the pandemic. The study aimed to investigate the effect of Indigo Naturalis on ALI induced by influenza A virus (IAV) in mice.

Method

The anti-influenza and anti-inflammatory properties of aqueous extract of Indigo Naturalis (INAE) were evaluated in vitro. BALB/c mice inoculated intranasally with IAV (H1N1) were treated intragastrically with INAE (40, 80 and 160 mg/kg/day) 2 h later for 4 or 7 days. Animal lifespan and mortality were recorded. Expression of high mobility group box-1 protein (HMGB-1) and toll-like receptor 4 (TLR4) were evaluated through immunohistological staining. Inflammatory cytokines were also monitored by ELISA.

Result

INAE inhibited virus replication on Madin-Darby canine kidney (MDCK) cells and decreased nitric oxide (NO) production from lipopolysaccharide (LPS)-stimulated peritoneal macrophages in vitro. The results showed that oral administration of 160 mg/kg of INAE significantly improved the lifespan (P < 0.01) and survival rate of IAV infected mice, improved lung injury and lowered viral replication in lung tissue (P < 0.01). Treatment with INAE (40, 80 and 160 mg/kg) significantly increased liver weight and liver index (P < 0.05), as well as weight and organ index of thymus and spleen at 160 mg/kg (P < 0.05). Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) levels were reduced by INAE administration (P < 0.05). The expression of HMGB-1 and TLR4 in lung tissue were also suppressed. The increased production of myeloperoxidase (MPO) and methylene dioxyamphetamine (MDA) in lung tissue were inhibited by INAE treatment (P < 0.05). Treatment with INAE reduced the high levels of interferon α (IFN-α), interferon β (IFN-β), monocyte chemoattractant protein-1 (MCP-1), regulated upon activation normal T cell expressed and secreted factor (RANTES), interferon induced protein-10 (IP-10), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) (P < 0.05), with increased production of interferon γ (IFN-γ) and interleukin-10 (IL-10) (P < 0.05).

Conclusion

The results showed that INAE alleviated IAV induced ALI in mice. The mechanisms of INAE were associated with its anti-influenza, anti-inflammatory and anti-oxidation properties. Indigo Naturalis might have clinical potential to treat ALI induced by IAV.

A cost-effectiveness analysis of South Africa's seasonal influenza vaccination programme

BACKGROUND

Seasonal influenza imposes a significant health and economic burden in South Africa, particularly in populations vulnerable to severe consequences of influenza. This study assesses the cost-effectiveness of South Africa's seasonal influenza vaccination strategy, which involves vaccinating vulnerable populations with trivalent inactivated influenza vaccine (TIV) during routine facility visits. Vulnerable populations included in our analysis are persons aged ≥ 65 years; pregnant women; persons living with HIV/AIDS (PLWHA), persons of any age with underlying medical conditions (UMC) and children aged 6-59 months.

METHOD

We employed the World Health Organisation's (WHO) Cost Effectiveness Tool for Seasonal Influenza Vaccination (CETSIV), a decision tree model, to evaluate the 2018 seasonal influenza vaccination campaign from a public healthcare provider and societal perspective. CETSIV was populated with existing country-specific demographic, epidemiologic and coverage data to estimate incremental cost-effectiveness ratios (ICERs) by comparing costs and benefits of the influenza vaccination programme to no vaccination.

RESULTS

The highest number of clinical events (influenza cases, outpatient visits, hospitalisation and deaths) were averted in PLWHA and persons with other UMCs. Using a cost-effectiveness threshold of US$ 3400 per quality-adjusted life year (QALY), our findings suggest that the vaccination programme is cost-effective for all vulnerable populations except for children aged 6-59 months. ICERs ranged from ~US$ 1 750 /QALY in PLWHA to ~US$ 7500/QALY in children. In probabilistic sensitivity analyses, the vaccination programme was cost-effective in pregnant women, PLWHA, persons with UMCs and persons aged ≥65 years in >80% of simulations. These findings were robust to changes in many model inputs but were most sensitive to uncertainty in estimates of influenza-associated illness burden.

CONCLUSION

South Africa's seasonal influenza vaccination strategy of opportunistically targeting vulnerable populations during routine visits is cost-effective. A budget impact analysis will be useful for supporting future expansions of the programme.

Impact of COVID-19 on liver function: results from an internal medicine unit in Northern Italy

Little is known regarding coronavirus disease 2019 (COVID-19) clinical spectrum in non-Asian populations. We herein describe the impact of COVID-19 on liver function in 100 COVID-19 consecutive patients (median age 70 years, range 25-97; 79 males) who were admitted to our internal medicine unit in March 2020. We retrospectively assessed liver function tests, taking into account demographic characteristics and clinical outcome. A patient was considered as having liver injury when alanine aminotransferase (ALT) was > 50 mU/ml, gamma-glutamyl transpeptidase (GGT) > 50 mU/ml, or total bilirubin > 1.1 mg/dl. Spearman correlation coefficient for laboratory data and bivariable analysis for mortality and/or need for intensive care were assessed. A minority of patients (18.6%) were obese, and most patients were non- or moderate-drinkers (88.5%). Liver function tests were altered in 62.4% of patients, and improved during follow-up. None of the seven patients with known chronic liver disease had liver decompensation. Only one patient developed acute liver failure. In patients with altered liver function tests, PaO2/FiO2 < 200 was associated with greater mortality and need for intensive care (HR 2.34, 95% CI 1.07-5.11, p = 0.033). To conclude, a high prevalence of altered liver function tests was noticed in Italian patients with COVID-19, and this was associated with worse outcomes when developing severe acute respiratory distress syndrome.