Innate and adaptive T cells in influenza disease

Research trends and key contributors in studies on influenza vaccines for children: A 20-year bibliometric analysis

Globally, there are over 3 million severe cases of influenza each year, leading to up to half a million deaths. This study provides a comprehensive analysis of the current status of children's influenza vaccine research over the past 20 years and explores potential future research trends, including improvements in vaccine coverage and strategies to address vaccine hesitancy. We extracted all research data on children's influenza vaccines from 2004 to 2024 using the Web of Science Core Collection (WOSCC). The contributions of various countries/regions, institutions, authors, and journals in this field were assessed, and research hotspots as well as promising future trends were predicted through keyword analysis using CiteSpace and VOSviewer. A total of 2,598 related publications from 2004 to 2024 were identified and collected for analysis. The United States (USA) and England emerged as the leading contributors with the highest number of published papers. AstraZeneca was identified as a key leader among research institutions, and Ambrose Christopher S was recognized as the most productive author in this field. The journals Vaccine and Human Vaccines & Immunotherapeutics stood out as the most prominent publications in this area. The keyword analysis highlighted that international research collaboration maybe a promising strategy for bridging global gaps; Addressing vaccine hesitancy could potentially increase vaccination coverage; Live attenuated vaccines, intranasal administration and universal vaccines are promising directions for future development. These insights highlight potential avenues for improving influenza vaccine coverage and inform strategies to mitigate vaccine hesitancy, crucial for protecting children and enhancing public health.

The kinetics of gene expression related to innate and adaptive immunity in the lung and spleen following Newcastle disease virus (NDV) infection in vaccinated broiler chickens employing different vaccination regimes

Newcastle disease virus (NDV) classified as an avian paramyxovirus-1 poses a significant risk to the global poultry sector. This study explored the kinetics of the innate and adaptive immune responses in chickens exposed to virulent Newcastle Disease Virus (vNDV) genotype VII. A challenge experiment was carried out with both non-vaccinated and NDV-vaccinated chickens utilizing different vaccination strategies commonly used in the industry. The four groups of vaccinated birds were administered either two doses of live NDV vaccines, live vaccines boosted with an inactivated vaccine, the rHVT-NDV-IBDV vaccine alone, or the rHVT-NDV-IBDV vaccine in conjunction with a live vaccine booster. To assess seven cytokines linked to antiviral and proinflammatory innate responses quantitative real-time polymerase chain reaction (qRT-PCR) analyses were implemented. The analyses revealed robust innate immune responses in all cytokines measured in lung and spleen tissues of the group that received both live and inactivated vaccines. Notably these increases were found to correlate with the humoral immune response within that same group. Significant transcriptional activity in the lung and spleen tissues of non-vaccinated chickens at 24 hour post-infection (pi). The most significant upregulations were identified in toll-like receptor 7 (TLR7), TLR5, interleukin 6 (IL6), chicken interferon-alpha (chIFN-α), and myxovirus resistance protein 1 (Mx1), which later exhibited a regression. The administration of both live and inactivated vaccines has proven effective in restoring the suppression or inhibition of vNDV infection across a wide range of cytokines, including TLR7, TLR5, chIFN-α, Mx1, IL6, and MHC-1. Various vaccination strategies have been shown to either mitigate or prevent cytokine storms within 24 hour pi in the lungs, spleen, or both, in certain cytokines such as chIFN-α, Mx1, and IL6. Collectively these results suggest that different vaccination strategies modify the kinetics and pathophysiological responses associated with vNDV infection in chickens.

Chicken TCRγδ+CD8α+T cells are antigen-specific and protective in H9N2 AIV infection

TCRγδ+ T cells are a major lymphocyte population of chickens, but their response or contribution to immunity against avian influenza virus (AIV) remains unknown. Here, we report an increase in the proportion and activation state of TCRγδ+CD8α+ T cells in the PBMCs of 3 chicken lines (MHC homozygous H-B2 and H-B21 lines and outbred G-WL line) with the strongest responses observed in the more resistant H-B2 chickens. H9N2 AIV infection induced mRNA upregulation of interferon (IFN)-γ and cytotoxicity-associated molecules, including, Granzyme A, Granzyme K, and perforin in sorted TCRγδ+CD8α+ T cells. Moreover, in ex vivo cultured TCRγδ+CD8α+ T cells in response to H9N2 AIV infected splenocytes, strongly indicates the activation of these cells' cytolytic potential via detection of transcription levels of cytotoxic genes with quantitative reverse transcription polymerase chain reaction (qRT-PCR), and IFN-γ protein level with ELISPOT and an intracellular cytokine staining assays. Most importantly, in vivo depletion of γδ T cells led to reduced H9N2 AIV control, which was particularly evident in the early phase of infection. Taken together, these results indicate that strong TCRγδ+CD8α+T cell response plays a critical role in protecting chicken against H9N2 AIV infection.

Design and evaluation of a poly-epitope based vaccine for the induction of influenza A virus cross-reactive CD8 + T cell responses

The availability of influenza vaccines that can induce broadly protective immune responses is highly desirable and could also mitigate the impact of future influenza pandemics. Ideally, these vaccines also induce virus-specific CD8 + T cells, which have been identified as an independent correlate of protection. In the present study, we explored the use of an artificial immunogen that comprises of twenty highly conserved influenza virus CD8 + T cell epitopes with an HLA coverage of 99.5% of the world population. The highly attenuated viral vector Modified Vaccinia virus Ankara (MVA) was used to deliver the artificial poly-epitope sequence (rMVA-PE) and by using T cell lines raised against individual epitopes, we confirmed that the epitopes are liberated from the artificial immunogen. For efficient antigen processing and presentation, the epitopes were separated by spacer sequences. Stimulation of peripheral blood mononuclear cells of HLA-typed blood donors with rMVA-PE resulted in the activation of influenza virus-specific T cell responses. Furthermore, immunization of humanized HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-knockout mice (HLA-A*02:01) with rMVA-PE induced influenza virus-specific CD8 + T cell responses. Thus, rMVA-PE proved to be immunogenic both in vitro and in vivo and constitutes a promising vaccine candidate for the induction of cross-reactive CD8 + T cell responses that could afford protection against antigenically distinct influenza A viruses (IAV) of various subtypes and species, and is currently considered for further clinical testing.

Adjuvant-free, self-assembling ferritin nanoparticle vaccine coupled with influenza virus hemagglutinin protein carrying M1 and PADRE epitopes elicits cross-protective immune responses

Introduction

Influenza viruses pose a significant threat to global public health. Several influenza pandemic outbreaks have had serious economic and public health implications. Current influenza virus vaccines generally provide strain-specific protection and must be rapidly produced annually to match the circulating viruses. Developing influenza vaccines that confer protection against a broad range of viruses will have a positive impact on public health. In this study, we aimed to develop a ferritin-based influenza nanoparticle vaccine with a broad protective spectrum to enhance the immune response against diverse influenza viruses.

Results

We generated an adjuvant-free, self-assembling nanoparticle vaccine against diverse influenza A viruses. This nanoparticle vaccine displayed multi-antigen targets on the surface of Helicobacter pylori ferritin, which consists of the ectodomain of hemagglutinin of the H3N2 virus and three tandem highly conserved influenza M1 epitopes fused with the universal helper T-cell epitope PADRE, named HMP-NP. HMP-NPs were expressed in a soluble form in the baculovirus-insect cell system and self-assembled into homogeneous nanoparticles. Animal immunization studies showed that the HMP-NP nanovaccine elicited 4-fold higher haemagglutination inhibition (HAI) titers than inactivated influenza vaccine. And neutralization titers induced by HMP-NPs against the H3N2 virus and heterologous strains of the H1N1 and H9N2 viruses were ~8, 12.4 and 16 times higher than inactivated influenza vaccine, respectively. Meanwhile, we also observed that the number of IFN-γ- and IL-4-secreting cells induced by HMP-NPs were ~2.5 times higher than inactivated influenza vaccine. Importantly, intranasal immunization with HMP-NPs, without any adjuvant, induced efficient mucosal IgA responses and conferred complete protection against the H3N2 virus, as well as partial protection against the H1N1 and H9N2 viruses and significantly reduced lung viral loads.

Discussion

Overall, our results indicated that the self-assembled nanovaccines increased the potency and breadth of the immune response against various influenza viruses and are a promising delivery platform for developing vaccines with broader protection against emerging influenza viruses and other pathogens.

DNA and protein-generated chimeric molecules for delivery of influenza viral epitopes in mouse and humanized NSG transfer models

Purified subunit viral antigens are weakly immunogenic and stimulate only the antibody but not the T cell-mediated immune response. An alternative approach to inducing protective immunity with small viral peptides may be the targeting of viral epitopes to immunocompetent cells by DNA and protein-engineered vaccines. This review will focus on DNA and protein-generated chimeric molecules carrying engineered fragments specific for activating cell surface co-receptors for inducing protective antiviral immunity. Adjuvanted protein-based vaccine or DNA constructs encoding simultaneously T- and B-cell peptide epitopes from influenza viral hemagglutinin, and scFvs specific for costimulatory immune cell receptors may induce a significant increase of anti-influenza antibody levels and strong CTL activity against virus-infected cells in a manner that mimics the natural infection. Here we summarize the development of several DNA and protein chimeric constructs carrying influenza virus HA317-41 fragment. The generated engineered molecules were used for immunization in intact murine and experimentally humanized NSG mouse models.

Identification of gene and protein signatures associated with long-term effects of COVID-19 on the immune system after patient recovery by analyzing single-cell multi-omics data using a machine learning approach

Viral infections significantly impact the immune system, and impact will persist until recovery. However, the influence of severe acute respiratory syndrome coronavirus 2 infection on the homeostatic immune status and secondary immune response in recovered patients remains unclear. To investigate these persistent alterations, we employed five feature-ranking algorithms (LASSO, MCFS, RF, CATBoost, and XGBoost), incremental feature selection, synthetic minority oversampling technique and two classification algorithms (decision tree and k-nearest neighbors) to analyze multi-omics data (surface proteins and transcriptome) from coronavirus disease 2019 (COVID-19) recovered patients and healthy controls post-influenza vaccination. The single-cell multi-omics dataset was divided into five subsets corresponding to five immune cell subtypes: B cells, CD4+ T cells, CD8+ T cells, Monocytes, and Natural Killer cells. Each cell was represented by 28,402 scRNA-seq (RNA) features, 3 Hash Tag Oligo (HTO) features, 138 Cellular indexing of transcriptomes and epitopes by sequencing (CITE) features and 23,569 Single Cell Transform (SCT) features. Some multi-omics markers were identified and effective classifiers were constructed. Our findings indicate a distinct immune status in COVID-19 recovered patients, characterized by low expression of ribosomal protein (RPS26) and high expression of immune cell surface proteins (CD33, CD48). Notably, TMEM176B, a membrane protein, was highly expressed in monocytes of COVID-19 convalescent patients. These observations aid in discerning molecular differences among immune cell subtypes and contribute to understanding the prolonged effects of COVID-19 on the immune system, which is valuable for treating infectious diseases like COVID-19.

Revisiting the dimensions of universal vaccine with special focus on COVID-19: Efficacy versus methods of designing

Even though the use of SARS-CoV-2 vaccines during the COVID-19 pandemic showed unprecedented success in a short time, it also exposed a flaw in the current vaccine design strategy to offer broad protection against emerging variants of concern. However, developing broad-spectrum vaccines is still a challenge for immunologists. The development of universal vaccines against emerging pathogens and their variants appears to be a practical solution to mitigate the economic and physical effects of the pandemic on society. Very few reports are available to explain the basic concept of universal vaccine design and development. This review provides an overview of the innate and adaptive immune responses generated against vaccination and essential insight into immune mechanisms helpful in designing universal vaccines targeting influenza viruses and coronaviruses. In addition, the characteristics, safety, and factors affecting the efficacy of universal vaccines have been discussed. Furthermore, several advancements in methods worthy of designing universal vaccines are described, including chimeric immunogens, heterologous prime-boost vaccines, reverse vaccinology, structure-based antigen design, pan-reactive antibody vaccines, conserved neutralizing epitope-based vaccines, mosaic nanoparticle-based vaccines, etc. In addition to the several advantages, significant potential constraints, such as defocusing the immune response and subdominance, are also discussed.

Immune Response to Respiratory Viral Infections

The respiratory system is constantly exposed to viral infections that are responsible for mild to severe diseases. In this narrative review, we focalized the attention on respiratory syncytial virus (RSV), influenza virus, and severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infections, responsible for high morbidity and mortality in the last decades. We reviewed the human innate and adaptive immune responses in the airways following infection, focusing on a particular population: newborns and pregnant women. The recent Coronavirus disease-2019 (COVID-19) pandemic has highlighted how our interest in viral pathologies must not decrease. Furthermore, we must increase our knowledge of infection mechanisms to improve our future defense strategies.

Integrating single-cell RNA sequencing data to genome-wide association analysis data identifies significant cell types in influenza A virus infection and COVID-19

With the global pandemic of COVID-19, the research on influenza virus has entered a new stage, but it is difficult to elucidate the pathogenesis of influenza disease. Genome-wide association studies (GWASs) have greatly shed light on the role of host genetic background in influenza pathogenesis and prognosis, whereas single-cell RNA sequencing (scRNA-seq) has enabled unprecedented resolution of cellular diversity and in vivo following influenza disease. Here, we performed a comprehensive analysis of influenza GWAS and scRNA-seq data to reveal cell types associated with influenza disease and provide clues to understanding pathogenesis. We downloaded two GWAS summary data, two scRNA-seq data on influenza disease. After defining cell types for each scRNA-seq data, we used RolyPoly and LDSC-cts to integrate GWAS and scRNA-seq. Furthermore, we analyzed scRNA-seq data from the peripheral blood mononuclear cells (PBMCs) of a healthy population to validate and compare our results. After processing the scRNA-seq data, we obtained approximately 70 000 cells and identified up to 13 cell types. For the European population analysis, we determined an association between neutrophils and influenza disease. For the East Asian population analysis, we identified an association between monocytes and influenza disease. In addition, we also identified monocytes as a significantly related cell type in a dataset of healthy human PBMCs. In this comprehensive analysis, we identified neutrophils and monocytes as influenza disease-associated cell types. More attention and validation should be given in future studies.

The gut-lung axis in influenza A: the role of gut microbiota in immune balance

Influenza A, the most common subtype, induces 3 to 5 million severe infections and 250,000 to 500,000 deaths each year. Vaccination is traditionally considered to be the best way to prevent influenza A. Yet because the Influenza A virus (IAV) is highly susceptible to antigenic drift and Antigenic shift, and because of the lag in vaccine production, this poses a significant challenge to vaccine effectiveness. Additionally, much information about the resistance of antiviral drugs, such as Oseltamivir and Baloxavir, has been reported. Therefore, the search for alternative therapies in the treatment of influenza is warranted. Recent studies have found that regulating the gut microbiota (GM) can promote the immune effects of anti-IAV via the gut-lung axis. This includes promoting IAV clearance in the early stages of infection and reducing inflammatory damage in the later stages. In this review, we first review the specific alterations in GM observed in human as well as animal models regarding IAV infection. Then we analyzed the effect of GM on host immunity against IAV, including innate immunity and subsequent adaptive immunity. Finally, our study also summarizes the effects of therapies using probiotics, prebiotics, or herbal medicine in influenza A on intestinal microecological composition and their immunomodulatory effects against IAV.

SARS-CoV-2 versus Influenza A Virus: Characteristics and Co-Treatments

For three years, the novel coronavirus disease 2019 (COVID-19) pandemic, caused by infection of the SARS-CoV-2 virus, has completely changed our lifestyles and prepared us to live with this novel pneumonia for years to come. Given that pre-existing flu is caused by the influenza A virus, we have begun unprecedently co-coping with two different respiratory diseases at the same time. Hence, we draw a comparison between SARS-CoV-2 and influenza A virus based on the general characteristics, especially the main variants’ history and the distribution of the two viruses. SARS-CoV-2 appeared to mutate more frequently and independently of locations than the influenza A virus. Furthermore, we reviewed present clinical trials on combined management against COVID-19 and influenza in order to explore better solutions against both at the same time.

No association found between late-onset inflammatory adverse events after soft tissue filler injections and the adaptive immune system

BACKGROUND

To date, it is unknown why some individuals develop late-onset inflammatory adverse events after treatment with fillers. These events may result from various factors, including an immunological response of the adaptive immune system.

OBJECTIVE

In a pilot study, we looked for evidence that is there a relation between late-onset inflammatory adverse events and the presence of immune cells surrounding the injected filler.

METHODS AND MATERIALS

We included 47 patients, of whom 20 experienced late-onset inflammatory adverse events to different fillers (inflammatory group) and 27 who did not (reference group). A biopsy was taken from the area of the adverse event. Hematoxylin-eosin staining and immunohistochemistry analysis with CD3 (T-cells) and CD68 (macrophages) on paraffin tissue sections was used to assess the biopsies.

RESULTS

Immune cells were found in biopsies obtained from 18 of 47 patients: Nine biopsies from the inflammation group and nine from the reference group. All these 18 cases showed CD68-positive immune cells. Virtually no CD3-positive immune cells were found.

CONCLUSION

Our results indicate that there is no T-cell activity in biopsies from areas with late-onset adverse events after filler injections. The macrophages found in the biopsies are probably not responsible for the inflammatory response.

New insights into human immune memory from SARS-CoV-2 infection and vaccination

Since early 2020, the world has been embroiled in an ongoing viral pandemic with SARS-CoV-2 and emerging variants resulting in mass morbidity and an estimated 6 million deaths globally. The scientific community pivoted rapidly, providing unique and innovative means to identify infected individuals, technologies to evaluate immune responses to infection and vaccination, and new therapeutic strategies to treat infected individuals. Never before has immunology been so critically at the forefront of combatting a global pandemic. It has now become evident that not just antibody responses, but formation and durability of immune memory cells following vaccination are associated with protection against severe disease from SARS-CoV-2 infection. Furthermore, the emergence of variants of concern (VoC) highlight the need for immunological markers to quantify the protective capacity of Wuhan-based vaccines. Thus, harnessing and modulating the immune response is key to successful vaccination and treatment of disease. We here review the latest knowledge about immune memory generation and durability following natural infection and vaccination, and provide insights into the attributes of immune memory that may protect from emerging variants.

Screening of crosstalk and pyroptosis-related genes linking periodontitis and osteoporosis based on bioinformatics and machine learning

Background and objective

This study aimed to identify crosstalk genes between periodontitis (PD) and osteoporosis (OP) and potential relationships between crosstalk and pyroptosis-related genes.

Methods

PD and OP datasets were downloaded from the GEO database and were performed differential expression analysis to obtain DEGs. Overlapping DEGs got crosstalk genes linking PD and OP. Pyroptosis-related genes were obtained from literature reviews. Pearson coefficients were used to calculate crosstalk and pyroptosis-related gene correlations in the PD and OP datasets. Paired genes were obtained from the intersection of correlated genes in PD and OP. PINA and STRING databases were used to conduct the crosstalk-bridge-pyroptosis genes PPI network. The clusters in which crosstalk and pyroptosis-related genes were mainly concentrated were defined as key clusters. The key clusters' hub genes and the included paired genes were identified as key crosstalk-pyroptosis genes. Using ROC curve analysis and XGBoost screened key genes. PPI subnetwork, gene-biological process and gene-pathway networks were constructed based on key genes. In addition, immune infiltration was analyzed on the PD dataset using the CIBERSORT algorithm.

Results

A total of 69 crosstalk genes were obtained. 13 paired genes and hub genes TNF and EGFR in the key clusters (cluster2, cluster8) were identified as key crosstalk-pyroptosis genes. ROC and XGBoost showed that PRKCB, GSDMD, ARMCX3, and CASP3 were more accurate in predicting disease than other key crosstalk-pyroptosis genes while better classifying properties as a whole. KEGG analysis showed that PRKCB, GSDMD, ARMCX3, and CASP3 were involved in neutrophil extracellular trap formation and MAPK signaling pathway pathways. Immune infiltration results showed that all four key genes positively correlated with plasma cells and negatively correlated with T cells follicular helper, macrophages M2, and DCs.

Conclusion

This study shows a joint mechanism between PD and OP through crosstalk and pyroptosis-related genes. The key genes PRKCB, GSDMD, ARMCX3, and CASP3 are involved in the neutrophil extracellular trap formation and MAPK signaling pathway, affecting both diseases. These findings may point the way to future research.

Anti-Interferon-γ Autoantibodies Impair T-Lymphocyte Responses in Patients with Talaromyces marneffei Infections

Background

Although anti-IFN-γ autoantibodies predispose patients to Talaromyces marneffei infection, whether this is mediated by T cell attenuation remains elusive.

Methods

Total peripheral blood mononuclear cells (PBMCs) from healthy donors or patients with T. marneffei infection were stimulated with M1₅₈₋₆₆, and immunodominant influenza H1N1 peptide, or heat-inactivated T. marneffei in the presence of serum from anti-IFN-γ autoantibody-positive patients or healthy controls. The percentages of IFN-γ⁺TNF⁺CD8⁺ T cells and IFN-γ⁺CD4⁺ T cells were determined by flow cytometry and cytokines released in the supernatant were detected by Cytometric Bead Array. Furthermore, PBMCs from patients with T. marneffei infection and healthy individuals were stimulated with IFN-γ and anti-CD3/CD28 beads, and the levels of STAT1 and STAT3 phosphorylation were detected by Western blot.

Results

The M1-reactive CD8⁺ T cells that expressed IFN-γ⁺ TNF-α⁺ of healthy controls were clearly reduced in serum with high-titer anti-IFN-γ autoantibodies. In addition, the CD4⁺ T cell response, designated by the expression of IFN-γ, against T. marneffei in PBMCs of patients were significantly decreased when cultured in high-titer anti-IFN-γ autoantibody serum culture, compared to the healthy compartments. Moreover, the release of the cytokines IFN-γ, TNF-α and IL-2 was significantly decreased, while IL-10 was significantly increased. There was no significant difference in the phosphorylation levels of STAT1 and STAT3 protein between patients and healthy controls after IFN-γ or anti-CD3/CD28 beads stimulation.

Conclusion

Anti-IFN-γ autoantibodies presence in the serum inhibited CD4⁺ Th1 and CD8⁺ T cell immune responses. There was no congenital dysfunction of STAT1 and STAT3 in anti-IFN-γ autoantibody-positive patients with T. marneffei infection. These results suggest that the production of anti-IFN-γ autoAbs impair T-lymphocyte responses.

Role of hormones in the pregnancy and sex-specific outcomes to infections with respiratory viruses

Pregnant women infected with pathogenic respiratory viruses, such as influenza A viruses (IAV) and coronaviruses, are at higher risk for mortality, hospitalization, preterm birth, and stillbirth. Several factors are likely to contribute to the susceptibility of pregnant individuals to severe lung disease including changes in pulmonary physiology, immune defenses, and effector functions of some immune cells. Pregnancy is also a physiologic state characterized by higher levels of multiple hormones that may impact the effector functions of immune cells, such as progesterone, estrogen, human chorionic gonadotropin, prolactin, and relaxin. Each of these hormones acts to support a tolerogenic immune state of pregnancy, which helps prevent fetal rejection, but may also contribute to an impaired antiviral response. In this review, we address the unique role of adaptive and innate immune cells in the control of pathogenic respiratory viruses and how pregnancy and specific hormones can impact their effector actions. We highlight viruses with sex-specific differences in infection outcomes and why pregnancy hormones may contribute to fetal protection but aid the virus at the expense of the mother's health.

Association between influenza vaccination and mortality due to COVID-19

Background

It has recently been suggested that influenza vaccination may be a factor associated with decreased COVID-19 mortality.

Methods

An age-matched case–control study based on hospital cases. We included subjects aged 18 years and older with a diagnosis of moderate to severe COVID-19. Infection was corroborated by RT-PCR test for SARS-COV-2. Deceased subjects were considered cases, controls were patients discharged due to improvement of acute symptoms. We used bivariate analysis to determine factors associated with death from COVID-19, and calculated odds ratios and 95% confidence intervals.

Results

A total of 560 patients were included in the study, 214 (38.2%) were considered cases and 346 (61.7%) controls. A significant difference was observed with the presence of type 2 diabetes mellitus [54% vs. 39.3% between cases and controls, respectively (P = 0.04)] and having received influenza vaccination (P = 0.02). Type 2 diabetes mellitus was associated with higher COVID-19 mortality [OR 1.8 (95% CI 1.2–2.5) P = 0.01], whereas having been immunised against influenza in 2019 was associated with lower mortality in this group of patients [OR 0.6 (95% CI 0.4–0.9) P = 0.02].

Conclusions

Influenza vaccination in the previous year appears to be associated with lower mortality from COVID-19; whereas type 2 diabetes mellitus is confirmed as a condition associated with higher mortality.

HLA-A*11:01-restricted CD8+ T cell immunity against influenza A and influenza B viruses in Indigenous and non-Indigenous people

HLA-A*11:01 is one of the most prevalent human leukocyte antigens (HLAs), especially in East Asian and Oceanian populations. It is also highly expressed in Indigenous people who are at high risk of severe influenza disease. As CD8⁺ T cells can provide broadly cross-reactive immunity to distinct influenza strains and subtypes, including influenza A, B and C viruses, understanding CD8⁺ T cell immunity to influenza viruses across prominent HLA types is needed to rationally design a universal influenza vaccine and generate protective immunity especially for high-risk populations. As only a handful of HLA-A*11:01-restricted CD8⁺ T cell epitopes have been described for influenza A viruses (IAVs) and epitopes for influenza B viruses (IBVs) were still unknown, we embarked on an epitope discovery study to define a CD8⁺ T cell landscape for HLA-A*11:01-expressing Indigenous and non-Indigenous Australian people. Using mass-spectrometry, we identified IAV- and IBV-derived peptides presented by HLA-A*11:01 during infection. 79 IAV and 57 IBV peptides were subsequently screened for immunogenicity in vitro with peripheral blood mononuclear cells from HLA-A*11:01-expressing Indigenous and non-Indigenous Australian donors. CD8⁺ T cell immunogenicity screening revealed two immunogenic IAV epitopes (A11/PB2_320-331 and A11/PB2_323-331) and the first HLA-A*11:01-restricted IBV epitopes (A11/M_41-49, A11/NS1_186-195 and A11/NP_511-520). The immunogenic IAV- and IBV-derived peptides were >90% conserved among their respective influenza viruses. Identification of novel immunogenic HLA-A*11:01-restricted CD8⁺ T cell epitopes has implications for understanding how CD8⁺ T cell immunity is generated towards IAVs and IBVs. These findings can inform the development of rationally designed, broadly cross-reactive influenza vaccines to ensure protection from severe influenza disease in HLA-A*11:01-expressing individuals.

Influenza A and influenza B viral infections cause significant morbidity and mortality. Established CD8⁺ T cell immunity directed at conserved viral regions provides protection against influenza viruses, drives rapid recovery, and leads to less severe clinical outcomes. Killer CD8⁺ T cells recognising viral peptides presented by HLA class I glycoproteins can provide broad immunity across distinct influenza strains and subtypes. Using immunopeptidomics, we identified novel CD8⁺ T cell targets for influenza A and influenza B viruses in the context of HLA-A*11:01, an HLA-I allomorph highly prevalent in East Asia and Oceania, including Indigenous populations. Our study provides key insights for T cell-directed vaccines and immunotherapies.

Evaluation of Human Circulating T Follicular Helper Cells in Influenza- and SARS-CoV-2-Specific B Cell Immunity

Generation of effective immune protection against viral infection and vaccination depends greatly on a successful engagement and stimulation of adaptive immune B cells and a specialized CD4⁺ T cell subset called T follicular helper cells (T_FH cells). Since T_FH cells primarily reside in lymphoid tissues, they can be challenging to study in human settings. However, a counterpart of these cells, circulating T_FH (cT_FH) cells, can be detected in peripheral blood. Assessment of cT_FH cells serves as an informative marker of humoral responses following viral infection and vaccination and can be predictive of antibody titers. Here, we describe a comprehensive flow cytometry detection method for dissecting cT_FH subsets and activation, together with the assessment of antibody-secreting cells (ASCs), from a small volume of human whole blood. This approach allows the investigation of cellular events that underpin successful immune responses following influenza and SARS-CoV-2 infection/vaccination in humans and is applicable to other viral disease settings.

Designing spatial and temporal control of vaccine responses

Vaccines are the key technology to combat existing and emerging infectious diseases. However, increasing the potency, quality and durability of the vaccine response remains a challenge. As our knowledge of the immune system deepens, it becomes clear that vaccine components must be in the right place at the right time to orchestrate a potent and durable response. Material platforms, such as nanoparticles, hydrogels and microneedles, can be engineered to spatially and temporally control the interactions of vaccine components with immune cells. Materials-based vaccination strategies can augment the immune response by improving innate immune cell activation, creating local inflammatory niches, targeting lymph node delivery and controlling the time frame of vaccine delivery, with the goal of inducing enhanced memory immunity to protect against future infections. In this Review, we highlight the biological mechanisms underlying strong humoral and cell-mediated immune responses and explore materials design strategies to manipulate and control these mechanisms.

Potentiating Lung Mucosal Immunity Through Intranasal Vaccination

Yearly administration of influenza vaccines is our best available tool for controlling influenza virus spread. However, both practical and immunological factors sometimes result in sub-optimal vaccine efficacy. The call for improved, or even universal, influenza vaccines within the field has led to development of pre-clinical and clinical vaccine candidates that aim to address limitations of current influenza vaccine approaches. Here, we consider the route of immunization as a critical factor in eliciting tissue resident memory (Trm) populations that are not a target of current licensed intramuscular vaccines. Intranasal vaccination has the potential to boost tissue resident B and T cell populations that reside within specific niches of the upper and lower respiratory tract. Within these niches, Trm cells are poised to respond rapidly to pathogen re-encounter by nature of their anatomic localization and their ability to rapidly deliver anti-pathogen effector functions. Unique features of mucosal immunity in the upper and lower respiratory tracts suggest that antigen localized to these regions is required for the elicitation of protective B and T cell immunity at these sites and will need to be considered as an important attribute of a rationally designed intranasal vaccine. Finally, we discuss outstanding questions and areas of future inquiry in the field of lung mucosal immunity.

In quest of a new therapeutic approach in COVID-19: the endocannabinoid system

The SARS-Cov-2 virus caused a high morbidity and mortality rate disease, that is the COVID-19 pandemic. Despite the unprecedented research interest in this field, the lack of specific treatments leads to severe complications in a high number of cases. Current treatment includes antivirals, corticosteroids, immunoglobulins, antimalarials, interleukin-6 inhibitors, anti-GM-CSF, convalescent plasma, immunotherapy, antibiotics, circulation support, oxygen therapy, and circulation support. Due to the limited results, until specific treatments are available, other therapeutic approaches need to be considered. The endocannabinoid system is found in multiple systems within the human body, including the immune system. Its activation can lead to beneficial results such as decreased viral entry, decreased viral replication, and a decrease in pro-inflammatory cytokines such as IL-2, IL-4, IL-6, IL-12, TNF-α, or IFN-γ. Moreover, endocannabinoid system activation can lead to an increase in anti-inflammatory cytokines, mainly represented by IL-10. Overall, the cannabinoid system can potentially reduce pulmonary inflammation, increase the immunomodulatory effect, decrease PMN infiltration, reduce fibrosis, and decrease viral replication, as well as decrease the 'cytokine storm'. Although the cannabinoid system has many mechanisms to provide certain benefits in the treatment of SARS-CoV-2 infected patients, research in this field is needed for a better understanding of the cannabinoid impact in this situation.

T-cell receptor repertoires as potential diagnostic markers for patients with COVID-19

Objective

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an ongoing global health emergency. T-cell receptors (TCRs) are crucial mediators of antiviral adaptive immunity. This study sought to comprehensively characterize the TCR repertoire changes in patients with COVID-19.

Methods

A large sample size multi-center randomized controlled trial was implemented to study the features of the TCR repertoire and identify COVID-19 disease-related TCR sequences.

Results

It was found that some T-cell receptor beta chain (TCRβ) features differed markedly between COVID-19 patients and healthy controls, including decreased repertoire diversity, longer complementarity-determining region 3 (CDR3) length, skewed utilization of the TCRβ variable gene/joining gene (TRBV/J), and a high degree of TCRβ sharing in COVID-19 patients. Moreover, this analysis showed that TCR repertoire diversity declines with aging, which may be a cause of the higher infection and mortality rates in elderly patients. Importantly, a set of TCRβ clones that can distinguish COVID-19 patients from healthy controls with high accuracy was identified. Notably, this diagnostic model demonstrates 100% specificity and 82.68% sensitivity at 0–3 days post diagnosis.

Conclusions

This study lays the foundation for immunodiagnosis and the development of medicines and vaccines for COVID-19 patients.

Likelihood of prior exposure to circulating influenza viruses resulting in cross-protection by CD8+ T cells against emergent H3N2v swine viruses infecting humans

Outbreaks of influenza in swine can result in potential threats to human public health. A notable occurrence was the emergence of swine-origin H1N1 influenza viruses in 2009. Since then, there have been several documented outbreaks of swine-origin influenza infecting humans in several countries. Sustained events have occurred when H1N1v, H1N2v, and H3N2v swine-origin viruses have infected humans visiting agricultural shows in the US. The predominant H3N2v viruses gained the matrix protein from the A(H1N1)pdm09 viruses, with reported human-to-human transmission raising fears of another pandemic. Current vaccines do not induce secondary cell-mediated immune responses, which may provide cross-protection against novel influenza A subtypes, however, population susceptibility to infection with seasonal influenza is likely to be influenced by cross-reactive CD8+ T-cells directed towards immunogenic peptides derived from viral proteins. This study involved a retrospective review of historical influenza viruses circulating in human populations from 1918 to 2020 to identify evidence of prior circulation of H3N3v immunogenic CD8+ T-cells peptides found in the NP and M1 proteins. We found evidence of prior circulation of H3N2v NP and M1 immunogenic peptides in historical influenza viruses. This provides insight into the population context in which influenza viruses emerge and may help inform immunogenic peptide selection for cytotoxic T-cell lymphocytes (CTL)-inducing influenza vaccines. Next-generation vaccines capable of eliciting CD8+ T-cell-mediated cross-protective immunity may offer a long-term alternative strategy for influenza vaccines.

Intranasal Nanoparticle Vaccination Elicits a Persistent, Polyfunctional CD4 T Cell Response in the Murine Lung Specific for a Highly Conserved Influenza Virus Antigen That Is Sufficient To Mediate Protection from Influenza Virus Challenge

Lung-localized CD4 T cells play a critical role in the control of influenza virus infection and can provide broadly protective immunity. However, current influenza vaccination strategies primarily target influenza hemagglutinin (HA) and are administered peripherally to induce neutralizing antibodies. We have used an intranasal vaccination strategy targeting the highly conserved influenza nucleoprotein (NP) to elicit broadly protective lung-localized CD4 T cell responses. The vaccine platform consists of a self-assembling nanolipoprotein particle (NLP) linked to NP with an adjuvant. We have evaluated the functionality, in vivo localization, and persistence of the T cells elicited. Our study revealed that intranasal vaccination elicits a polyfunctional subset of lung-localized CD4 T cells that persist long term. A subset of these lung CD4 T cells localize to the airway, where they can act as early responders following encounter with cognate antigen. Polyfunctional CD4 T cells isolated from airway and lung tissue produce significantly more effector cytokines IFN-γ and TNF-α, as well as cytotoxic functionality. When adoptively transferred to naive recipients, CD4 T cells from NLP:NP-immunized lung were sufficient to mediate 100% survival from lethal challenge with H1N1 influenza virus. IMPORTANCE Exploiting new, more efficacious strategies to potentiate influenza virus-specific immune responses is important, particularly for at-risk populations. We have demonstrated the promise of direct intranasal protein vaccination to establish long-lived immunity in the lung with CD4 T cells that possess features and positioning in the lung that are associated with both immediate and long-term immunity, as well as demonstrating direct protective potential.

Advances in Development and Application of Influenza Vaccines

Influenza A virus is one of the most important zoonotic pathogens that can cause severe symptoms and has the potential to cause high number of deaths and great economic loss. Vaccination is still the best option to prevent influenza virus infection. Different types of influenza vaccines, including live attenuated virus vaccines, inactivated whole virus vaccines, virosome vaccines, split-virion vaccines and subunit vaccines have been developed. However, they have several limitations, such as the relatively high manufacturing cost and long production time, moderate efficacy of some of the vaccines in certain populations, and lack of cross-reactivity. These are some of the problems that need to be solved. Here, we summarized recent advances in the development and application of different types of influenza vaccines, including the recent development of viral vectored influenza vaccines. We also described the construction of other vaccines that are based on recombinant influenza viruses as viral vectors. Information provided in this review article might lead to the development of safe and highly effective novel influenza vaccines.

CD8+ T cell landscape in Indigenous and non-Indigenous people restricted by influenza mortality-associated HLA-A*24:02 allomorph

Indigenous people worldwide are at high risk of developing severe influenza disease. HLA-A*24:02 allele, highly prevalent in Indigenous populations, is associated with influenza-induced mortality, although the basis for this association is unclear. Here, we define CD8⁺ T-cell immune landscapes against influenza A (IAV) and B (IBV) viruses in HLA-A*24:02-expressing Indigenous and non-Indigenous individuals, human tissues, influenza-infected patients and HLA-A*24:02-transgenic mice. We identify immunodominant protective CD8⁺ T-cell epitopes, one towards IAV and six towards IBV, with A24/PB2_550-558-specific CD8⁺ T cells being cross-reactive between IAV and IBV. Memory CD8⁺ T cells towards these specificities are present in blood (CD27⁺CD45RA^- phenotype) and tissues (CD103⁺CD69⁺ phenotype) of healthy individuals, and effector CD27^-CD45RA^-PD-1⁺CD38⁺CD8⁺ T cells in IAV/IBV patients. Our data show influenza-specific CD8⁺ T-cell responses in Indigenous Australians, and advocate for T-cell-mediated vaccines that target and boost the breadth of IAV/IBV-specific CD8⁺ T cells to protect high-risk HLA-A*24:02-expressing Indigenous and non-Indigenous populations from severe influenza disease.

The ubiquitin ligase Peli1 inhibits ICOS and thereby Tfh-mediated immunity

T follicular helper (Tfh) cells are crucial for regulating autoimmune inflammation and protective immunity against viral infection. However, the molecular mechanism controlling Tfh cell differentiation is poorly understood. Here, through two mixed bone marrow chimeric experiments, we identified Peli1, a T cell-enriched E3 ubiquitin ligase, as an intrinsic regulator that inhibits Tfh cell differentiation. Peli1 deficiency significantly promoted c-Rel-mediated inducible T-cell costimulator (ICOS) expression, and PELI1 mRNA expression was negatively associated with ICOS expression on human CD4⁺ T cells. Mechanistically, increased ICOS expression on Peli1-KO CD4⁺ T cells enhanced the activation of PI3K-AKT signaling and thus suppressed the expression of Klf2, a transcription factor that inhibits Tfh differentiation. Therefore, reconstitution of Klf2 abolished the differences in Tfh differentiation and germinal center reaction between WT and Peli1-KO cells. As a consequence, Peli1-deficient CD4⁺ T cells promoted lupus-like autoimmunity but protected against H1N1 influenza virus infection in mouse models. Collectively, our findings established Peli1 as a critical negative regulator of Tfh differentiation and indicated that targeting Peli1 may have beneficial therapeutic effects in Tfh-related autoimmunity or infectious diseases.

Clinical Analysis of Primary Nephrotic Syndrome Complicated by Plastic Bronchitis in Children

OBJECTIVE

To summarize the clinical features of primary nephrotic syndrome (PNS) complicated by plastic bronchitis (PB) in children to provide guidance for treatment.

METHODS

We conducted a retrospective review of the clinical data of 25 children hospitalized with NS complicated by PB in our Hospital between 10/2016 and 03/2019, and summarized the clinical manifestations, imaging and fiberoptic bronchoscopy (FOB) examinations, treatment course and outcome of them.

RESULTS

1). The 25 children, with a nephrotic syndrome (NS) course of one to 36 months, were all diagnosed with PB after FOB, among which 8 cases (32%) had respiratory failure and required ventilatory support. All of them started with respiratory symptoms such as fever and cough, and then suffered from dyspnea and progressive aggravation after 1-3 day(s) of onset, with rapid occurrence of bidirectional dyspnea and even respiratory failure in severe cases. 2). Laboratory test for pathogens: influenza A virus H1N1 (11 cases), influenza B virus (9 cases), adenovirus (3 cases) and mycoplasma pneumoniae (2 cases). There was no statistically significant difference (P>0.05) between children with common NS complicated by influenza virus (IV) infection (not accompanied by dyspnea) and those with kidney disease who developed PB in the white blood cell count, lymphocyte count, the inflammatory biomarkers C-reactive protein (CRP), procalcitonin (PCT) and humoral immunity (IgG level), yet the total IgG level was found significantly higher and the blood albumin level lower in the latter (P<0.05). 3). The 25 children were all examined with the FOB and treated with lavage, 15 of which had typical bronchial tree-like casts and 10 broken and stringy casts. Based on histopathological classification, all children were of Type I. 4). Twenty children (80%) with influenza were administered the antiviral drug Oseltamivir, 20 (80%) were treated with antibiotics, oral hormones were replaced with the same dosage of intravenous Methylprednisolone for 5 cases (20%), and 20 (80%) were intravenously administered gamma globulins (400-500 mg/kg x 3 days). These children showed a remarkable improvement after treatment and there were no deaths.

CONCLUSION

NS children are at high risk of influenza virus infection. Children with a severe case of NS are more susceptible to PB. If symptoms like shortness of breath, wheezing and progressive bidirectional dyspnea occur, FOB examination and lavage treatment should be performed as early as possible. Hyper-IgE-emia and hypoproteinemia may be the high risk factors for PNS complicated by PB in children. ZIEL: Ziel der Studie war es, durch Zusammenfassung der klinischen Merkmale des primären nephrotischen Syndroms (PNS) mit komplizierender plastischer Bronchitis (PB) im Kindesalter eine Orientierungshilfe für die Therapie der Erkrankung zu geben.

METHODIK

Wir führten eine retrospektive Prüfung der klinischen Daten von 25 Kindern durch, die zwischen Oktober 2016 und März 2019 in unser Krankhaus aufgenommen wurden, und erstellten eine Zusammenfassung der klinischen Symptome, Untersuchungen mit bildgebenden Verfahren und fiberoptischer Bronchoskopie (FOB), des Therapieverlaufs und des Outcomes der Patienten.

ERGEBNISSE

1). Bei den 25 Kindern bestand ein nephrotisches Syndrom (NS) über einen Zeitraum von einem bis 36 Monaten. Bei allen Patienten wurde die Diagnose PB nach FOB gestellt, wobei in 8 Fällen (32%) eine beatmungspflichtige respiratorische Insuffizienz vorlag. Alle Patienten zeigten anfänglich Symptome einer Atemwegserkrankung wie Fieber und Husten, gefolgt von Atemnot und progredienter Verschlechterung 1 bis 3 Tage nach Erkrankungsbeginn. Dabei kam es rasch zum Auftreten bidirektionaler Atemnot, in schweren Fällen bis hin zur respiratorischen Insuffizienz. 2). Laboruntersuchung auf Erreger: Influenza-A-Virus H1N1 (11 Fälle), Influenza-B-Virus (9 Fälle), Adenovirus (3 Fälle) und Mycoplasma pneumoniae (2 Fälle). Es fand sich kein statistisch signifikanter Unterschied (P>0,05) zwischen Kindern, die ein "gewöhnliches" NS mit komplizierender Influenza-Virus (IV)-Infektion (ohne begleitende Atemnot) aufwiesen, und Kindern mit Nierenerkrankung, die eine PB entwickelten, hinsichtlich der Leukozyten- und Lymphozytenwerte sowie der Entzündungsmarker C-reaktives Protein (CRP), Procalcitonin (PCT) und humorale Immunität (IgG-Wert). Allerdings wurde bei der letzteren Patientengruppe ein signifikant höherer Gesamt-IgG-Wert und ein signifikant niedriger Albumin-Spiegel im Blut nachgewiesen (P<0.05). 3). Bei allen 25 Kindern erfolgte eine FOB und Therapie mit Lavage, bei 15 Kinder fanden sich typische verzweigte Ausgüsse der Bronchialäste und bei 10 Patienten desintegrierte und zähe Ausgüsse. Gemäß der histopathologischen Klassifikation waren alle Kinder vom Typ I. 4). Zwanzig Kinder (80%) mit Influenza erhielten das Virostatikum Oseltamivir, 20 Kinder (80%) eine Antibiotikatherapie, in 5 Fällen (20%) wurden oral gegebene Hormone durch intravenös in derselben Dosis verabreichtes Methylprednisolon ersetzt und 20 Kinder (80%) erhielten intravenös verabreichte Gammaglobuline (400-500 mg/kg Körpergewicht x 3 Tage). Diese Kinder zeigten eine bemerkenswerte Verbesserung nach der Therapie und es traten keine Todesfälle auf.

SCHLUSSFOLGERUNG

Bei Kindern mit NS besteht ein hohes Risiko für eine Influenza-Virus-Infektion. Kinder mit schwerem NS sind anfälliger für PB. Bei Auftreten von Symptomen wie Atemnot, Giemen und Brummern sowie progredienter bidirektionaler Dyspnoe sollte baldmöglichst eine FOB-Untersuchung und eine therapeutische Lavage durchgeführt werden. Erhöhte IgE-Werte im Blut und Hypoproteinämie stellen möglicherweise Risikofaktoren für PNS mit komplizierender PB im Kindesalter dar.

Leukocyte trafficking to the lungs and beyond: lessons from influenza for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). Understanding of the fundamental processes underlying the versatile clinical manifestations of COVID-19 is incomplete without comprehension of how different immune cells are recruited to various compartments of virus-infected lungs, and how this recruitment differs among individuals with different levels of disease severity. As in other respiratory infections, leukocyte recruitment to the respiratory system in people with COVID-19 is orchestrated by specific leukocyte trafficking molecules, and when uncontrolled and excessive it results in various pathological complications, both in the lungs and in other organs. In the absence of experimental data from physiologically relevant animal models, our knowledge of the trafficking signals displayed by distinct vascular beds and epithelial cell layers in response to infection by SARS-CoV-2 is still incomplete. However, SARS-CoV-2 and influenza virus elicit partially conserved inflammatory responses in the different respiratory epithelial cells encountered early in infection and may trigger partially overlapping combinations of trafficking signals in nearby blood vessels. Here, we review the molecular signals orchestrating leukocyte trafficking to airway and lung compartments during primary pneumotropic influenza virus infections and discuss potential similarities to distinct courses of primary SARS-CoV-2 infections. We also discuss how an imbalance in vascular activation by leukocytes outside the airways and lungs may contribute to extrapulmonary inflammatory complications in subsets of patients with COVID-19. These multiple molecular pathways are potential targets for therapeutic interventions in patients with severe COVID-19.

Influenza in Children

Influenza poses a significant disease burden on children worldwide, with high rates of hospitalization and substantial morbidity and mortality. Although the clinical presentation of influenza in children has similarities to that seen in adults, there are unique aspects to how children present with infection that are important to recognize. In addition, children play a significant role in viral transmission within communities. Growing evidence supports the idea that early influenza infection can uniquely establish lasting immunologic memory, making an understanding of how viral immunity develops in this population critical to better protect children from infection and to facilitate efforts to develop a more universally protective influenza vaccine.

Establishing a Multicolor Flow Cytometry to Characterize Cellular Immune Response in Chickens Following H7N9 Avian Influenza Virus Infection

Avian influenza virus (AIV) emerged and has continued to re-emerge, continuously posing great threats to animal and human health. The detection of hemagglutination inhibition (HI) or virus neutralization antibodies (NA) is essential for assessing immune protection against AIV. However, the HI/NA-independent immune protection is constantly observed in vaccines’ development against H7N9 subtype AIV and other subtypes in chickens and mammals, necessitating the analysis of the cellular immune response. Here, we established a multi-parameter flow cytometry to examine the innate and adaptive cellular immune responses in chickens after intranasal infection with low pathogenicity H7N9 AIV. This assay allowed us to comprehensively define chicken macrophages, dendritic cells, and their MHC-II expression, NK cells, γδ T cells, B cells, and distinct T cell subsets in steady state and during infection. We found that NK cells and KUL01⁺ cells significantly increased after H7N9 infection, especially in the lung, and the KUL01⁺ cells upregulated MHC-II and CD11c expression. Additionally, the percentages and numbers of γδ T cells and CD8 T cells significantly increased and exhibited an activated phenotype with significant upregulation of CD25 expression in the lung but not in the spleen and blood. Furthermore, B cells showed increased in the lung but decreased in the blood and spleen in terms of the percentages or/and numbers, suggesting these cells may be recruited from the periphery after H7N9 infection. Our study firstly disclosed that H7N9 infection induced local and systemic cellular immune responses in chickens, the natural host of AIV, and that the flow cytometric assay developed in this study is useful for analyzing the cellular immune responses to AIVs and other avian infectious diseases and defining the correlates of immune protection.

Risk factors for hospital-acquired influenza A and patient characteristics: a matched case-control study

BACKGROUND

While hospital-acquired influenza A results in an additional cost burden and considerable mortality in patients, its risk factors are unknown. We aimed to describe the characteristics of patients vulnerable to hospital-acquired influenza A and to identify its risk factors to assist clinicians control hospital-acquired infections and reduce the burden of treatment.

METHODS

A case-control study was conducted among hospitalized patients aged ≥18 years at a tertiary level teaching hospital during the 2018-2019 influenza A season. Patient data were retrieved from hospital-based electronic medical records. Hospital-acquired influenza A was defined as a case of influenza A diagnosed 7 days or more after admission, in a patient with no evidence of influenza A infection on admission. The controls without influenza A were selected among patients exposed to the same setting and time period. We identified risk factors using conditional logistic regression and described the characteristics of hospital-acquired influenza A by comparing the clinical data of infected patients and the controls.

RESULTS

Of the 412 hospitalized patients with influenza A from all the departments in the study hospital, 93 (22.6%) cases were classified as hospital-acquired. The most common comorbidities of the 93 cases were hypertension (41.9%), coronary heart disease (21.5%), and cerebrovascular disease (20.4%). Before the onset of hospital-acquired influenza A, patients presented more lymphocytopenia (51.6% vs 35.5%, P = 0.027), hypoalbuminemia (78.5% vs 57.0%, P = 0.002), and pleural effusion (26.9% vs 9.7%, P = 0.002) than the matched controls. Infected patients also had longer hospital stays (18 days vs 14 days, P = 0.002), and higher mortality rates (10.8% vs 2.2%, P = 0.017) than the matched controls. Lymphocytopenia (odds ratio [OR]: 3.11; 95% confidence interval [CI]: 1.24-7.80; P = 0.016), hypoalbuminemia (OR: 2.24; 95% CI: 1.10-4.57; P = 0.027), and pleural effusion (OR: 3.09; 95% CI: 1.26-7.58; P = 0.014) were independently associated with hospital-acquired influenza A.

CONCLUSIONS

Lymphocytopenia, hypoalbuminemia and pleural effusion are independent risk factors that can help identify patients at high risk of hospital-acquired influenza A, which can extend hospital stay and is associated with a high mortality.

Role of γδ T cells in controlling viral infections with a focus on influenza virus: implications for designing novel therapeutic approaches

BACKGROUND

Influenza virus infection is among the most detrimental threats to the health of humans and some animals, infecting millions of people annually all around the world and in many thousands of cases giving rise to pneumonia and death. All those health crises happen despite previous and recent developments in anti-influenza vaccination, suggesting the need for employing more sophisticated methods to control this malign infection. Main body The innate immunity modules are at the forefront of combating against influenza infection in the respiratory tract, among which, innate T cells, particularly gamma-delta (γδ) T cells, play a critical role in filling the gap needed for adaptive immune cells maturation, linking the innate and adaptive immunity together. Upon infection with influenza virus, production of cytokines and chemokines including CCL3, CCL4, and CCL5 from respiratory epithelium recruits γδ T cells at the site of infection in a CCR5 receptor-dependent fashion. Next, γδ T cells become activated in response to influenza virus infection and produce large amounts of proinflammatory cytokines, especially IL-17A. Regardless of γδ T cells' roles in triggering the adaptive arm of the immune system, they also protect the respiratory epithelium by cytolytic and non-cytolytic antiviral mechanisms, as well as by enhancing neutrophils and natural killer cells recruitment to the infection site.

CONCLUSION

In this review, we explored varied strategies of γδ T cells in defense to influenza virus infection and how they can potentially provide balanced protective immune responses against infected cells. The results may provide a potential window for the incorporation of intact or engineered γδ T cells for developing novel antiviral approaches or for immunotherapeutic purposes.

Thrombo-inflammatory features predicting mortality in patients with COVID-19: The FAD-85 score

BACKGROUND

The roles of inflammation and hypercoagulation in predicting outcomes of coronavirus disease 2019 (COVID-19) are unclear.

METHODS

Adult patients diagnosed with COVID-19 from 28 January 2020 to 4 March 2020 in Tongji Hospital, Wuhan were recruited. Data on related parameters were collected. Univariate analysis and multivariable binary logistic regression were used to explore predictors of critical illness and mortality.

RESULTS

In total, 199 and 44 patients were enrolled in the training and testing sets, respectively. Elevated ferritin, tumor necrosis factor-α and D-dimer and decreased albumin concentration were associated with disease severity. Older age, elevated ferritin and elevated interleukin-6 were associated with 28-day mortality. The FAD-85 score, defined as age + 0.01 * ferritin +D-dimer, was used to predict risk of mortality. The sensitivity, specificity and accuracy of FAD-85 were 86.4%, 81.8% and 86.4%, respectively. A nomogram was established using age, ferritin and D-dimer to predict the risk of 28-day mortality.

CONCLUSIONS

Thrombo-inflammatory parameters provide key information on the severity and prognosis of COVID-19 and can be used as references for clinical treatment to correct inflammatory and coagulation abnormalities.

Innate and adaptive immunity toward influenza B viruses

Despite annual vaccination, influenza B viruses (IBV) cause significant disease with substantial health and socio-economic impacts. Novel vaccination strategies inducing broadly protective and long-lasting immunity across IBV lineages are needed. However, as immune responses toward IBV are largely understudied, host–virus interactions and protective immune mechanisms need to be defined to rationally design such vaccines. Here, we summarize recent advances in our understanding of immunological mechanisms underpinning protection from IBV. We discuss how innate antiviral host factors inhibit IBV replication and the ways by which IBV escapes such restriction. We review the specificity of broadly cross-reactive antibodies and universal T cells, and the mechanisms by which they mediate protection. We highlight important knowledge gaps needing to be addressed to design improved IBV vaccines.

Viral burden, inflammatory milieu and CD8+ T-cell responses to influenza virus in a second-generation thiazolide (RM-5061) and oseltamivir combination therapy study

Background

Influenza viruses cause significant morbidity and mortality, especially in young children, elderly, pregnant women and individuals with co‐morbidities. Patients with severe influenza disease are typically treated with one neuraminidase inhibitor, oseltamivir or zanamivir. These antivirals need to be taken early to be most effective and often lead to the emergence of drug resistance and/or decreased drug susceptibility. Combining oseltamivir with another antiviral with an alternative mode of action has the potential to improve clinical effectiveness and reduce drug resistance.

Methods

In this study, we utilized a host‐targeting molecule RM‐5061, a second‐generation thiazolide, in combination with oseltamivir to determine whether these compounds could reduce viral burden and understand their effects on the immune response to influenza virus infection in mice, compared with either monotherapy or placebo.

Results

The combination of RM‐5061 and OST administered for 5 days after influenza infection reduced viral burden at day 5 post‐infection, when compared to placebo and RM‐5061 monotherapy, but was not significantly different from oseltamivir monotherapy. The inflammatory cytokine milieu was also reduced in animals which received a combination therapy when compared to RM‐5061 and placebo‐treated animals. Antiviral treatment in all groups led to a reduction in CD8⁺ T‐cell responses in the BAL when compared to placebo.

Conclusions

To our knowledge, this is the first time a combination of a host‐targeting compound, RM‐5061, and neuraminidase inhibitor, OST, has been tested in vivo. This antiviral combination was safe in mice and led to reduced inflammatory responses following viral infection when compared to untreated animals.

Characteristics of inflammatory factors and lymphocyte subsets in patients with severe COVID-19

To investigate the inflammatory factors and lymphocyte subsets which play an important role in the course of severe coronavirus disease 2019 (COVID-19). A total of 27 patients with severe COVID-19 who were admitted to Tongji Hospital in Wuhan from 1 to 21 February 2020 were recruited to the study. The characteristics of interleukin-1β (IL-1β), IL-2 receptor (IL-2R), IL-6, IL-8, IL-10, tumor necrosis factor-α (TNF)-α, C-reactive protein (CRP), serum ferritin and procalcitonin (PCT), and lymphocyte subsets of these patients were retrospectively compared before and after treatment. Before treatment, there was no significant difference in most inflammatory factors (IL-1β, IL-2R, IL-6, IL-8, IL-10, CRP, and serum ferritin) between male and female patients. Levels of IL-2R, IL-6, TNF-α, and CRP decreased significantly after treatment, followed by IL-8, IL-10, and PCT. Serum ferritin was increased in all patients before treatment but did not decrease significantly after treatment. IL-1β was normal in most patients before treatment. Lymphopenia was common among these patients with severe COVID-19. Analysis of lymphocyte subsets showed that CD4+ and particularly CD8+ T lymphocytes increased significantly after treatment. However, B lymphocytes and natural killer cells showed no significant changes after treatment. A pro-inflammatory response and decreased level of T lymphocytes were associated with severe COVID-19.

Predicting Illness Severity and Short-Term Outcomes of COVID-19: A Retrospective Cohort Study in China

Among 417 COVID-19 patients in Shenzhen, demographic characteristics, clinical manifestations and baseline laboratory tests showed significant differences between mild-moderate cohort and severe-critical cohort.Based on these differences, a convenient mathematical model was established to predict the illness severity of COVID-19. The model includes four parameters: age, BMI, CD4⁺ lymphocytes and IL-6 levels. The AUC of the model is 0.911.The high risk factors for developing to severe COVID-19 are: age ≥ 55 years, BMI > 27 kg / m², IL-6 ≥ 20 pg / ml, CD4⁺ T cell ≤ 400 count / μ L.Among 249 discharged COVID-19 patients, those who recovered after 20 days had a lower count of platelet, a higher level of estimated glomerular filtration rate, and higher level of interleukin-6 and myoglobin than those who recovered within 20 days.

Dendritic Cells Targeting Lactobacillus plantarum Strain NC8 with a Surface-Displayed Single-Chain Variable Fragment of CD11c Induce an Antigen-Specific Protective Cellular Immune Response

Influenza A virus (H1N1) is an acute, highly contagious respiratory virus. The use of lactic acid bacteria (LAB) to deliver mucosal vaccines against influenza virus infection is a research hot spot. In this study, two recombinant Lactobacillus plantarum strains expressing hemagglutinin (HA) alone or coexpressing aCD11c-HA to target HA protein to dendritic cells (DCs) by fusion to an anti-CD11c single-chain antibody (aCD11c) were constructed. The activation of bone marrow dendritic cells (BMDCs) by recombinant strains and the interaction of activated BMDCs and sorted CD4⁺ or CD8⁺ T cells were evaluated through flow cytometry in vitro, and cellular supernatants were assessed by using an enzyme-linked immunosorbent assay kit. The results demonstrated that, compared to the HA strain, the aCD11c-HA strain significantly increased the activation of BMDCs and increased the production of CD4⁺ gamma interferon-positive (IFN-γ⁺) T cells, CD8⁺ IFN-γ⁺ T cells, and IFN-γ in the cell culture supernatant in vitro Consistent with these results, the aCD11c-HA strain clearly increased the activation and maturation of DCs, the HA-specific responses of CD4⁺ IFN-γ⁺ T cells, CD8⁺ IFN-γ⁺ T cells, and CD8⁺ CD107a⁺ T cells, and the proliferation of T cells in the spleen, finally increasing the levels of specific antibodies and neutralizing antibodies in mice. In addition, the protection of immunized mice was observed after viral infection, as evidenced by improved weight loss, survival, and lung pathology. The adoptive transfer of CD8⁺ T cells from the aCD11c-HA mice to NOD/Lt-SCID mice resulted in a certain level of protection after influenza virus infection, highlighting the efficacy of the aCD11c targeting strategy.

Gegen Qinlian Decoction Downregulates the TLR7 Signalling Pathway to Control Influenza A Virus Infection

ETHNOPHARMACOLOGICAL RELEVANCE

In recent years, Gegen Qinlian decoction (GQD) has been applied to treat influenza virus infection, and its clinical effectiveness has been shown. However, the potential mechanism by which GQD acts on influenza A virus (IAV) has not been fully elucidated. Traditional Chinese medicine (TCM) formulas are well known to have multiple targets and effects. Our previous experiments examined the mechanism by which TCM can be used to treat influenza from the perspective of the influenza immune mechanism.

AIM OF THE STUDY

To explore the possible mechanism by which GQD affects mice infected with the FM1 strain of influenza virus.

MATERIALS AND METHODS

Forty-eight C57BL/6 mice were divided randomly into four groups: a normal control (NG) group, an IAV infection (VG) group, an IAV + oseltamivir (30.44 mg/kg) treatment (VO) group, and an IAV + GQD (9.74 g/kg) treatment (VQ) group. We also grouped forty-eight Toll-like receptor 7 knockout (TLR7-/-) mice in the same manner. The pulmonary mRNA expression of TLR7, myeloid differentiation factor 88 (MyD88), and nuclear factor (NF)-κB p65 was measured by RT-qPCR, and the pulmonary protein expression of TLR7, MyD88, and NF-κB p65 was measured by western blot. The proportions of T helper (Th) 1, Th2, Th17 and regulatory T (Treg) cells were measured by flow cytometry.

RESULTS

IAV infection led to low body weights and high viral load. Compared with those in the NG group, the mRNA expression levels of TLR7, MyD88, and NF-κB p65 in the VG group were upregulated (P < 0.05). However, the mRNA and protein expression levels of TLR7, MyD88, and NF-κB p65 were lower in the VO and VQ groups than in the VG group (P < 0.05). IAV infection led to increased proportions of Th1/Th2 and Th17/Treg cells in the VG group. In the VO and VQ groups, both Th2 and Th1 cell numbers were increased, resulting in a lower Th1/Th2 proportion than that in the VG group.

CONCLUSIONS

GQD downregulated the expression of some key TLR signalling pathway factors. GQD also affected the differentiation of CD4+ T cells, thereby exerting a protective systemic effect on influenza virus infection. In conclusion, GQD activated a balanced inflammatory response in the host to limit immune pathological injury and improve clinical and survival outcomes.

Neutrophil-to-Lymphocyte and Platelet-to-Lymphocyte Ratios in COVID-19 Patients and Control Group and Relationship with Disease Prognosis

BACKGROUND

The present study aimed to compare the complete blood count (CBC) indices between COVID-19 patients and the control group, and assess the relationship of these indices with COVID-19 prognosis.

METHODS

COVID-19 patients (confirmed by PCR or CT-Scan) who visited Imam Hospital in Sari were selected in this case-control study. The control group was selected from Tabari cohort population matched with the case group in terms of gender and age. CBC, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and outcome of the disease (in the case group) were assessed in this study.

RESULTS

The number of participants were 527 in both case and control groups, of which, 232 (44%) were females in each arms. Platelet count, lymphocyte count, and hemoglobin concentration were also higher in the control group (P=0.000). NLR and PLR were significantly higher in COVID-19 patients compared to the control group (P=0.000). NLR had a significant relationship with the severity of the disease. NLR was two times higher in the patients who died of COVID-19 than those who recovered (P=0.000). ROC curve analysis for diagnostic values of NLR and PLR showed that the areas under the ROC curves for NLR and PLR were 0.703 (95% CI: 0.64-0.76) and 0.535 (95% CI: 0.46-06), respectively.

CONCLUSION

NLR can be used as a prognostic marker for COVID-19 given the significant difference of NLR between those who died and recovered from COVID-19.

APOBEC-mediated DNA alterations: A possible new mechanism of carcinogenesis in EBV-positive gastric cancer

Mechanisms of viral oncogenesis are diverse and include the off-target activity of enzymes expressed by the infected cells, which evolved to target viral genomes for controlling their infection. Among these enzymes, the single-strand DNA editing capability of APOBECs represent a well-conserved viral infection response that can also cause untoward mutations in the host DNA. Here we show, after evaluating somatic single-nucleotide variations and transcriptome data in 240 gastric cancer samples, a positive correlation between APOBEC3s mRNA-expression and the APOBEC-mutation signature, both increased in EBV+ tumors. The correlation was reinforced by the observation of APOBEC mutations preferentially occurring in the genomic loci of the most active transcripts. This EBV infection and APOBEC3 mutation-signature axis were confirmed in a validation cohort of 112 gastric cancer patients. Our findings suggest that APOBEC3 upregulation in EBV+ cancer may boost the mutation load, providing further clues to the mechanisms of EBV-induced gastric carcinogenesis. After further validation, this EBV-APOBEC axis may prove to be a secondary driving force in the mutational evolution of EBV+ gastric tumors, whose consequences in terms of prognosis and treatment implications should be vetted.

Clinical Features Predicting Mortality Risk in Patients With Viral Pneumonia: The MuLBSTA Score

Objective

The aim of this study was to further clarify clinical characteristics and predict mortality risk among patients with viral pneumonia.

Methods

A total of 528 patients with viral pneumonia at RuiJin hospital in Shanghai from May 2015 to May 2019 were recruited. Multiplex real-time RT-PCR was used to detect respiratory viruses. Demographic information, comorbidities, routine laboratory examinations, immunological indexes, etiological detections, radiological images and treatment were collected on admission.

Results

76 (14.4%) patients died within 90 days in hospital. A predictive MuLBSTA score was calculated on the basis of a multivariate logistic regression model in order to predict mortality with a weighted score that included multilobular infiltrates (OR = 5.20, 95% CI 1.41–12.52, p = 0.010; 5 points), lymphocyte ≤ 0.8^∗10⁹/L (OR = 4.53, 95% CI 2.55–8.05, p < 0.001; 4 points), bacterial coinfection (OR = 3.71, 95% CI 2.11–6.51, p < 0.001; 4 points), acute-smoker (OR = 3.19, 95% CI 1.34–6.26, p = 0.001; 3 points), quit-smoker (OR = 2.18, 95% CI 0.99–4.82, p = 0.054; 2 points), hypertension (OR = 2.39, 95% CI 1.55–4.26, p = 0.003; 2 points) and age ≥60 years (OR = 2.14, 95% CI 1.04–4.39, p = 0.038; 2 points). 12 points was used as a cut-off value for mortality risk stratification. This model showed sensitivity of 0.776, specificity of 0.778 and a better predictive ability than CURB-65 (AUROC = 0.773 vs. 0.717, p < 0.001).

Conclusion

Here, we designed an easy-to-use clinically predictive tool for assessing 90-day mortality risk of viral pneumonia. It can accurately stratify hospitalized patients with viral pneumonia into relevant risk categories and could provide guidance to make further clinical decisions.

Influenza Pathogenesis: The Effect of Host Factors on Severity of Disease

Influenza viruses continue to be a major global health threat. Severity and clinical outcome of influenza disease is determined by both viral and host factors. Viral factors have long been the subject of intense research and many molecular determinants have been identified. However, research into the host factors that protect or predispose to severe and fatal influenza A virus infections is lagging. The goal of this review is to highlight the recent insights into host determinants of influenza pathogenesis.

With a Little Help from T Follicular Helper Friends: Humoral Immunity to Influenza Vaccination

Influenza remains a global and unpredictable threat. Annual vaccination against influenza A and B viruses promotes the induction of Abs and memory B cells, which can provide strain-specific protection against subsequent infections. The formation of effective memory B cell and Ab responses is highly dependent on the germinal center reaction, a well-orchestrated process involving B cells and a specialized CD4⁺ T cell subset called T follicular helper (Tfh) cells. As Tfh cells predominantly reside within B cell follicles in secondary lymphoid organs, they are challenging to study in humans. Recent identification of a circulating counterpart of Tfh cells has allowed us to better understand the contribution of these circulating Tfh cells during human immune responses. In this article, we summarize the role of human Tfh cells during humoral immune responses and discuss the contribution of Tfh cells in promoting immunity to influenza viruses in healthy cohorts and high-risk groups.

Is a Universal Influenza Virus Vaccine Possible?

Influenza viruses remain a severe burden to human health because of their contribution to overall morbidity and mortality. Current seasonal influenza virus vaccines do not provide sufficient protection to alleviate the annual impact of influenza and cannot confer protection against potentially pandemic influenza viruses. The lack of protection is due to rapid changes of the viral epitopes targeted by the vaccine and the often suboptimal immunogenicity of current immunization strategies. Major efforts to improve vaccination approaches are under way. The development of a universal influenza virus vaccine may be possible by combining the lessons learned from redirecting the immune response toward conserved viral epitopes, as well as the use of adjuvants and novel vaccination platforms.