Conservation of T cell epitopes between seasonal influenza viruses and the novel influenza A H7N9 virus

A novel avian influenza A(H7N9) virus recently emerged in the Yangtze River delta and caused diseases, often severe, in over 130 people. This H7N9 virus appeared to infect humans with greater ease than previous avian influenza virus subtypes such as H5N1 and H9N2. While there are other potential explanations for this large number of human infections with an avian influenza virus, we investigated whether a lack of conserved T-cell epitopes between endemic H1N1 and H3N2 influenza viruses and the novel H7N9 virus contributes to this observation. Here we demonstrate that a number of T cell epitopes are conserved between endemic H1N1 and H3N2 viruses and H7N9 virus. Most of these conserved epitopes are from viral internal proteins. The extent of conservation between endemic human seasonal influenza and avian influenza H7N9 was comparable to that with the highly pathogenic avian influenza H5N1. Thus, the ease of inter-species transmission of H7N9 viruses(compared with avian H5N1 viruses) cannot be attributed to the lack of conservation of such T cell epitopes. On the contrary, our findings predict significant T-cell based cross-reactions in the human population to the novel H7N9 virus. Our findings also have implications for H7N9 virus vaccine design.

Superior antibody and membrane protein‑specific T‑cell responses to CoronaVac by intradermal versus intramuscular routes in adolescents

Background Optimising the immunogenicity of COVID-19 vaccines to improve their protection against disease is necessary.Fractional dosing by intradermal(ID)administration has been shown to be equally immunogenic as intramuscular(IM)administration for several vaccines,but the immunogenicity of ID inactivated whole severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)at the full dose is unknown.This study(NCT04800133)investigated the superiority of antibody and T-cell responses of full-dose CoronaVac by ID over IM administration in adolescents.Methods Participants aged 11–17 years received two doses of IM or ID vaccine,followed by the 3rd dose 13–42 days later.Humoral and cellular immunogenicity outcomes were measured post-dose 2(IM-CC versus ID-CC)and post-dose 3(IMCCC versus ID-CCC).Doses 2 and 3 were administered to 173 and 104 adolescents,respectively.Results Spike protein(S)immunoglobulin G(IgG),S-receptor-binding domain(RBD)IgG,S IgG Fcγreceptor IIIa(FcγRIIIa)-binding,SNM[sum of individual(S),nucleocapsid protein(N),and membrane protein(M)peptide pool]-specific interleukin-2(IL-2)+CD4^(+),SNM-specific IL-2^(+)CD8^(+),S-specific IL-2^(+)CD8^(+),N-specific IL-2^(+)CD4^(+),N-specific IL-2^(+)CD8^(+)and M-specific IL-2^(+)CD4^(+)responses fulfilled the superior and non-inferior criteria for ID-CC compared to IM-CC,whereas IgG avidity was inferior.For ID-CCC,S-RBD IgG,surrogate virus neutralisation test,90%plaque reduction neutralisation titre(PRNT90),PRNT50,S IgG avidity,S IgG FcγRIIIa-binding,M-specific IL-2^(+)CD4^(+),interferon-γ+CD8^(+)and IL-2^(+)CD8^(+)responses were superior and non-inferior to IM-CCC.The estimated vaccine efficacies were 49%,52%,66%and 79%for IM-CC,ID-CC,IM-CCC and ID-CCC,respectively.The ID groups reported more local,mild adverse reactions.Conclusion This is the first study to demonstrate superior antibody and M-specific T-cell responses by ID inactivated SARSCoV-2 vaccination and serves as the basis for future research to improve the immunogenicity of inactivated vaccines.

Glucose metabolism controls humanγδ-cell-mediated tumor immunosurveillance in diabetes

Patients with type 2 diabetes mellitus(T2DM)have an increased risk of cancer.The effect of glucose metabolism onγδT cells and their impact on tumor surveillance remain unknown.Here,we showed that high glucose induced Warburg effect type of bioenergetic profle in Vy9vδ2 T cells,leading to excessive lactate accumulation,which further inhibited lytic granule secretion by impairing the traffcking of cytolytic machinery to the Vy9vδ2 T-cell-tumor synapse by suppressing AMPK activation and resulted in the loss of antitumor activity in vitro,in vivo and in patients.Strikingly,activating the AMPK pathway through glucose control or metformin treatment reversed the metabolic abnormalities and restored the antitumor activity of Vy9vδ2 T cells.These results suggest that the impaired antitumor activity of Vy9vδ2 T cells induced by dysregulated glucose metabolism may contribute to the increased cancer risk in T2DM patients and that metabolic reprogramming by targeting the AMPK pathway with metformin may improve tumor immunosurveillance.

Avian influenza virus directly infects human natural killer cells and inhibits cell activity

Natural killer （NK） cell is a key component of innate immunity and plays an important role in host defense against virus infection by directly destroying infected cells. Influenza is a respiratory disease transmitted in the early phase of virus infection. Evasion of host innate immunity including NK cells is critical for the virus to expand and establish a successful acute infection. Previously, we showed that human influenza HIN1 virus infects NK cells and induces cell apoptosis, as well as inhibits NK cell activity. In this study, we further demonstrated that avian influenza virus also directly targeted NK cells as an immunoevasion strategy. The avian virus infected human NK cells and induced cell apoptosis. In addition, avian influenza virion and HA protein inhibited NK cell cytotoxicity. This novel strategy has obvious advantages for avian influenza virus, allowing the virus sufficient time to expand and subsequent spread before the onset of the specific immune response. Our findings provide an important clue for the immunopathogenesis of avian influenza, and also suggest that direct targeting NK cells may be a common strategy used by both human and avian influenza viruses to evade NK cell immunity.

CD40-activated B cells are more potent than immature dendritic cells to induce and expand CD41 regulatory T cells

CD4^(+)regulatory T cells(Tregs)play an important role in maintaining immune tolerance by suppressing pathologic immune responses.,The generation of large numbers of antigen-specific Tregs ex vivo is critical for the development of clinical immunotherapy based on the adoptive transfer of Tregs.Both CD40-activated B cells(CD40-B)and immature dendritic cells(imDCs)have been used as professional antigen-presenting cells(APCs)to generate antigen-specific Tregs.However,the efficiencies of CD40-B and imDCs to generate CD4^(+)Tregs have not been compared directly and the mechanism driving the generation of these Tregs remains largely unknown.In this study,we found that CD40-B exhibited mature phenotypes and were more able to induce and expand CD4^(high)"CD25^(+)Tregs than imDCs.Moreover,Tregs induced by CD40-B had greater suppressive capacity than those induced by imDCs.The generation of CD4^(high)CD25^(+)Tregs by CD40-B and imDCs is cell-cell contact dependent and partially relies on the expression of human leukocyte antigen(HLA)-DR and CD80/86.Differences in CD4^(high)CD25^(+)Treg generation efficiency were largely explained by the production of endogenous IL-2 by CD40-B.Our results suggest that CD40-B is better able to generate large numbers of antigen-specific Tregs than imDCs.Additionally,using CD40-B to generate Tregs may accelerate the clinical use of Treg-based immunotherapy in the treatment of allograft rejection,graft versus host disease(GVHD)and autoimmune diseases.

Exosomes derived from nasopharyngeal carcinoma cells induce IL-6 production from macrophages to promote tumorigenesis

Chronic inflammation in the tumor microenvironment can promotes tumorigenesis.Various immune cells,including macrophages,can infiltrate into the tumor microenvironment and secrete abundant inflammatory cytokines.1 Interleukin-6(IL-6)is a major inflammatory cytokine that is widely involved in the tumorigenesis of many cancers,including nasopharyngeal carcinoma(NPC).2 In NPC patients,serum IL-6 was elevated and positively correlated with poor prognosis,suggesting that IL-6 may play a critical role in NPC progression.2,3 Indeed,previous studies demonstrated that IL-6 could activate signal transducer and activator of transcription 3(STAT3)and promote the proliferation,migration,and invasion of NPC cells.2 However,the mechanism underlying the upregulation of IL-6 in NPC remains elusive.

Antibody and T cell responses against wild-type and Omicron SARS-CoV-2 after third-dose BNT162b2 in adolescents

The high effectiveness of the third dose of BNT162b2 in healthy adolescents against Omicron BA.1 has been reported in some studies,but immune responses conferring this protection are not yet elucidated.In this analysis,our study(NCT04800133)aims to evaluate the humoral and cellular responses against wild-type and Omicron(BA.1,BA.2 and/or BA.5)SARS-CoV-2 before and after a third dose of BNT162b2 in healthy adolescents.At 5 months after 2 doses,S IgG,S IgG Fc receptor-binding,and neutralising antibody responses waned significantly,yet neutralising antibodies remained detectable in all tested adolescents and S IgG avidity increased from 1 month after 2 doses.The antibody responses and S-specific IFN-γ^(+)and IL-2^(+)CD8^(+)T cell responses were significantly boosted in healthy adolescents after a homologous third dose of BNT162b2.Compared to adults,humoral responses for the third dose were non-inferior or superior in adolescents.The S-specific IFN-γ^(+)and IL-2^(+)CD4^(+)and CD8^(+)T cell responses in adolescents and adults were comparable or non-inferior.Interestingly,after 3 doses,adolescents had preserved S IgG,S IgG avidity,S IgG FcγRIIIa-binding,against Omicron BA.2,as well as preserved cellular responses against BA.1 S and moderate neutralisation levels against BA.1,BA.2 and BA.5.Sera from 100 and 96%of adolescents tested at 1 and 5 months after two doses could also neutralise BA.1.Our study found high antibody and T cell responses,including potent cross-variant reactivity,after three doses of BNT162b2 vaccine in adolescents in its current formulation,suggesting that current vaccines can be protective against symptomatic Omicron disease.

Allogeneic Vγ9Vδ2 T-cell immunotherapy exhibits promising clinical safety and prolongs the survival of patients with late-stage lung or liver cancer

Vγ9Vδ2 T cells are promising candidates for cellular tumor immunotherapy.Due to their HLA-independent mode of action,allogeneic Vγ9Vδ2 T cells can be considered for clinical application.To apply allogeneic Vγ9Vδ2 T cells in adoptive immunotherapy,the methodology used to obtain adequate cell numbers with optimal effector function in vitro needs to be optimized,and clinical safety and efficacy also need to be proven.Therefore,we developed a novel formula to improve the expansion of peripheralγδT cells from healthy donors.Then,we used a humanized mouse model to validate the therapeutic efficacy of expandedγδT cells in vivo;furthermore,the expandedγδT cells were adoptively transferred into late-stage liver and lung cancer patients.We found that the expanded cells possessed significantly improved immune effector functions,including proliferation,differentiation,and cancer cell killing,both in vitro and in the humanized mouse model.Furthermore,a phase I clinical trial in 132 late-stage cancer patients with a total of 414 cell infusions unequivocally validated the clinical safety of allogeneic Vγ9Vδ2 T cells.Among these 132 patients,8 liver cancer patients and 10 lung cancer patients who received≥5 cell infusions showed greatly prolonged survival,which preliminarily verified the efficacy of allogeneic Vγ9Vδ2 T-cell therapy.Our clinical studies underscore the safety and efficacy of allogeneic Vγ9Vδ2 T-cell immunotherapy,which will inspire further clinical investigations and eventually benefit cancer patients.

Uncompromised NK cell activation is essential for virus-specific CTL activity during acute influenza virus infection

Natural killer (NK) cells are indispensable components of both the innate and adaptive immune response. However,their precise roles in the cross-talk between innate and adaptive immunity during influenza virus infection remaincontroversial. By comparing NK cell dynamics and activity under a sub-lethal dose and high dose of influenza virusinfection, we showed that influenza virus PR8 directly infected NK cells during natural infection, which wasconsistent with our previous findings obtained from an in vitro investigation of human NK cells. The impairments incytotoxicity and IFN-γ production by spleen NK cells following high-dose infection were accompanied by decreasedvirus-specific killing mediated by cytotoxic T lymphocytes (CTLs). Importantly, the weakened CTL activity could bereversed by adoptive transfer of spleen NK cells harvested from low-dose-infected mice but not healthy donors.Taken together, our data provide direct evidence supporting the contribution of NK cells to antiviral T-cellresponses. This study also indicates that a novel NK-targeted immune evasion strategy is used by influenza virusto shrink both innate and adaptive immune responses.

Single-cell RNA Sequencing Deciphers Immune Landscape of Human Recurrent Miscarriage

Introduction Pregnancy is a mysterious biological process that presents great challenges to the maternal immune system.In the early 1950s,the‘‘fetal allograft”concept was described for the first time by Peter Medawar,and the unique immunology of the maternal-fetal interface was recognized[1].Correct and precise interaction between mother and fetus plays an important role during pregnancy process,such as the apposition,adhesion,implantation,and growth of embryo in uterus[2].In 1991,Colbern and Main proposed that the maternal immune cells directly interact with placenta but not the fetus[3].Therefore,information concerning the cross-talk between maternal immune cells and placenta during normal pregnancy will provide clues to explore the underlying mechanism of pathological pregnancy.Immune cells,such as natural killer(NK),macrophage,T,and dendritic cells,have been demonstrated to play important roles during normal pregnancy[4].With the development of single-cell RNA sequencing(scRNA-seq)technologies,researchers are devoted to providing a whole picture about the immune cellular composition and inter-cellular communication events during normal pregnancy[5,6].These foundational studies reveal that immune cell subsets,which are classified based on different markers at high resolution,exert specific function during pregnancy establishment.However,the panoramic analysis of immune subsets at high resolution in pathological pregnancy remains lacking.

LIGHT of pulmonary NKT cells annihilates tissue protective alveolar macrophages in augmenting severe influenza pneumonia

CD1d-restricted natural killer T(NKT)cells are innate-like T lymphocytes with protective or pathogenic roles in the development of influenza pneumonia.Here,we show that lung-infiltrated and activated NKT cells are the major cellular source of LIGHT/TNFSF14,which determines the severity of pulmonary pneumonia by highly deteriorative influenza A virus(IAV)infection.Compared to wild-type mice,LIGHT^(-/-)mice exhibit much lower morbidity and mortality to IAV,due to alleviated lung damage and reduced apoptosis of alveolar macrophages(AMs).LIGHT preferentially promotes cell death of lymphotoxin β receptors positive(LTβR^(+))AMs but not herpesvirus entry mediator positive(HVEM^(+))AMs.Therefore,these results suggest that NKT-derived LIGHT augments cell death of the tissue protective AMs in exacerbating lung pathology and susceptibility to fatal influenza infection.Suppression of LIGHT signaling might be a viable option in the treatment of influenza-associated acute respiratory distress syndrome.

Human Vγ9Vδ2-T cells efficiently kill influenzavirus-infected lung alveolar epithelial cells

γδ-T cells play an indispensable role in host defense against different viruses, including influenza A virus. However, whether these cells have cytotoxic activity against influenza virus-infected lung alveolar epithelial cells and subsequently contribute to virus clearance remains unknown. Using influenza virus-infected A549 cells, human lung alveolar epithelial cells, we investigated the cytotoxic activity of aminobisphosphonate pamidronate （PAM）-expanded human Vγ9Vδ2-T cells and their underlying mechanisms. We found that PAM could selectively activate and expand human Vγ9Vδ2-T cells. PAM-expanded human Vγ9Vδ2-T cells efficiently killed influenza virus-infected lung alveolar epithelial cells and inhibited virus replication. The cytotoxic activity of PAM-expanded Vγ9Vδ2-T cells was dependent on cell-to-cell contact and required NKG2D activation. Perforin-granzyme B, tumor-necrosis factor-related apoptosis-inducing ligand （TRAIL） and Fas-Fas ligand （FasL） pathways were involved in their cytotoxicity. Our study suggests that targeting γδ2-T cells by PAM can potentially offer an alternative option for the treatment of influenza virus.

CD137 costimulation enhances the antiviral activity of Vγ9Vδ2-T cells against influenza virus

Influenza epidemics and pandemics are constant threats to global public health.Although strategies including vaccines and antiviral drugs have achieved great advances in controlling influenza virus infection,the efficacy of these strategies is limited by the highly frequent mutations in the viral genome and the emergence of drug-resistant strains.Our previous study indicated that boosting the immunity of human Vγ9Vδ2-T cells with the phosphoantigen pamidronate could be a therapeutic strategy to treat seasonal and avian influenza virus infections.However,one notable drawback ofγδ-T cell-based immunotherapy is the rapid exhaustion of proliferation and effector responses due to repeated treatments with phosphoantigens.Here,we found that the expression of CD137 was inducible in Vγ9Vδ2-T cells following antigenic stimulation.CD137^(+)Vγ9Vδ2-T cells displayed more potent antiviral activity against influenza virus than their CD137−counterparts in vitro and in Rag2^(-/-)γc^(-/-)mice.We further demonstrated that CD137 costimulation was essential for Vγ9Vδ2-T cell activation,proliferation,survival and effector functions.In humanized mice reconstituted with human peripheral blood mononuclear cells,CD137 costimulation with a recombinant human CD137L protein boosted the therapeutic effects of pamidronate against influenza virus.Our study provides a novel strategy of targeting CD137 to improve the efficacy of Vγ9Vδ2-T cell-based immunotherapy.

Vγ9Vδ2-T lymphocytes have impaired antiviral function in small-for-gestational-age and preterm neonates

Preterm and small-for-gestational-age （SGA） neonates are vulnerable groups that are susceptible to various microbial infections. Vγ9Vδ2-T cells are critical components of the host immune system and have been demonstrated to play an important role in the defense against viral infection in adults. However, the characteristics of Vγ9Vδ2-T cells in children, especially the preterm and SGA populations, are poorly understood. Here, we examined the frequency and antiviral function of Vγ9Vδ2-T cells in neonates, including preterm, SGA and full-term babies. When compared to adults, neonates had a significantly lower percentage of Vγ9Vδ2-T cells in the blood. Upon influenza virus stimulation, neonatalVγ9Vδ2-T cells, especially from preterm and SGA babies, showed markedly decreased and delayed antiviral cytokine responses than those of adults. In addition, the antiviral responses of neonatal Vγ9Vδ2-T cells were positively correlated with gestational age and birth weight. Finally, a weaker expansion ofVγ9Vδ2-T cells by isopentenyl pyrophosphate （IPP） was shown in neonates than the expansion in adults. Our data suggest that the depressed antiviral activity and decreased frequency of Vγ9Vδ2-T cells may likely account for the high susceptibility to microbial infection in neonates, particularly in preterm and SGA babies. Improving Vγ9Vδ2-T -cell function of neonates may provide a new way to defend against virus infection.

mpaired NK cell antiviral cytokine response against nfluenza virus in small-for-gestational-age neonates

The neonates, particularly small-for-gestational-age （SGA） ones, are susceptible to various microbial infections. Natural killer （NK） cells are critical components of host innate immunity system and the main source of the inflammatory cytokines, which provide critical protection during the early phase of viral infections before the development of an appropriate adaptive immune response. However, little is known about the antiviral effects of NK cells in neonates especially the SGA population. Herein, a prospective descriptive study was performed to determine the differences of NK cell immunity among adults, appropriate-for gestational-age （AGA） and SGA neonates. Adults have much higher NK cell number in peripheral blood than that in cord blood from neonates. In response to influenza virus stimulation, neonatal NK cells, especially SGA baby cells, expressed significantly lower antiviral cytokines including perforin, interferon （IFN）-7 and tumor-necrosis factor （TNF）-α responses than adult NK cells. In addition, the antiviral cytokine responses of NK cells were positively correlated with neonatal birth weight. Our data suggested that the depressed antiviral activity and less frequency of NK cells are likely to be responsible for the high susceptibility to microbial infection in neonates, at least in part. Improving the function of innate immunity may provide a new way to defend virus infection.