CD39 expression defines exhausted CD4+ T cells associated with poor survival and immune evasion in human gastric cancer.

Objectives: CD4+ T cell helper and regulatory function in human cancers has been well characterised. However, the definition of tumor-infiltrating CD4+ T cell exhaustion and how it contributes to the immune response and disease progression in human gastric cancer (GC) remain largely unknown. Methods: A total of 128 GC patients were enrolled in the study. The expression of CD39 and PD-1 on CD4+ T cells in the different samples was analysed by flow cytometry. GC-infiltrating CD4+ T cell subpopulations based on CD39 expression were phenotypically and functionally assessed. The role of CD39 in the immune response of GC-infiltrating T cells was investigated by inhibiting CD39 enzymatic activity. Results: In comparison with CD4+ T cells from the non-tumor tissues, significantly more GC-infiltrating CD4+ T cells expressed CD39. Most GC-infiltrating CD39+CD4+ T cells exhibited CD45RA-CCR7- effector-memory phenotype expressing more exhaustion-associated inhibitory molecules and transcription factors and produced less TNF-α, IFN-γ and cytolytic molecules than their CD39-CD4+ counterparts. Moreover, ex vivo inhibition of CD39 enzymatic activity enhanced their functional potential reflected by TNF-α and IFN-γ production. Finally, increased percentages of GC-infiltrating CD39+CD4+ T cells were positively associated with disease progression and patients' poorer overall survival. Conclusion: Our study demonstrates that CD39 expression defines GC-infiltrating CD4+ T cell exhaustion and their immunosuppressive function. Targeting CD39 may be a promising therapeutic strategy for treating GC patients.

CD39hi identifies an exhausted tumor-reactive CD8+ T cell population associated with tumor progression in human gastric cancer.

The ectonucleotidase CD39 has been regarded as a promising immune checkpoint in solid tumors. However, the expression of CD39 by tumor-infiltrating CD8+ T cells as well as their potential roles and clinical implications in human gastric cancer (GC) remain largely unknown. Here, we found that GC-infiltrating CD8+ T cells contained a fraction of CD39hi cells that constituted about 6.6% of total CD8+ T cells in tumors. These CD39hi cells enriched for GC-infiltrating CD8+ T cells with features of exhaustion in transcriptional, phenotypic, metabolic and functional profiles. Additionally, GC-infiltrating CD39hiCD8+ T cells were also identified for tumor-reactive T cells, as these cells expanded in vitro were able to recognize autologous tumor organoids and induced more tumor cell apoptosis than those of expanded their CD39int and CD39-CD8+ counterparts. Furthermore, CD39 enzymatic activity controlled GC-infiltrating CD39hiCD8+ T cell effector function, and blockade of CD39 efficiently enhanced their production of cytokines IFN-γ and TNF-α. Finally, high percentages of GC-infiltrating CD39hiCD8+ T cells correlated with tumor progression and independently predicted patients' poor overall survival. These findings provide novel insights into the association of CD39 expression level on CD8+ T cells with their features and potential clinical implications in GC, and empowering those exhausted tumor-reactive CD39hiCD8+ T cells through CD39 inhibition to circumvent the suppressor program may be an attractive therapeutic strategy against GC.

Tumor-infiltrating mast cells stimulate ICOS+ regulatory T cells through an IL-33 and IL-2 axis to promote gastric cancer progression.

INTRODUCTION: In solid tumors, regulatory T cell (Treg) and mast cell perform different roles depending on the microenvironment. Nevertheless, mast cell and Treg-mediated interactions in gastric cancer (GC) are unclear, as are their regulation, function, and clinical significance. OBJECTIVE: The present study demonstrated the mechanism of tumor-infiltrating mast cells stimulating ICOS+ regulatory T cells via the IL-33/IL-2 axis to promote the growth of gastric cancer. METHODS: Analyses of 98 patients with GC were conducted to examine mast cell counts, ICOS+ Tregs, and the levels of IL-33 or IL-2. Isolated ICOS+ Treg and CD8+ T cell were stimulated, cultured and tested for their functional abilities in vitro and in vivo. RESULTS: GC patients exhibited a significantly more production of IL-33 in tumors. Mast cell stimulated by tumor-derived IL-33 exhibited a prolonged lifespan through IL-33 mediated inhibition of apoptosis. Moreover, mast cells stimulated by tumor-derived IL-33 secreted IL-2, which induced Treg expansion. These inducible Tregs displayed an activated immunosuppressive phenotype with positive expression for the inducible T cell co-stimulator (ICOS). In vitro, IL-2 from IL to 33-stimulated mast cells induced increased numbers of ICOS+ Tregs with increased immunosuppressive activity against proliferation and effector function of CD8+ T cell. In vivo, ICOS+ Tregs were treated with anti-IL-2 neutralizing antibody followed by co-injection with CD8+ T cells in GC mouse model, which showed an increased CD8+ T cell infiltration and effector molecules production, meanwhile tumor growth and progression were inhibited. Besides, reduction in GC patient survival was associated with tumor-derived ICOS+ Tregs. CONCLUSION: Our results highlight a crosstalk between GC-infiltrating mast cells and ICOS+ Tregs and provide a novel mechanism describing ICOS+ Treg expansion and induction by an IL-33/mast cell/IL-2 signaling axis in GC, and also provide functional evidence that the modulation of this immunosuppressive pathway can attenuate GC-mediated immune tolerance.

Effects of curcumin on non-alcoholic fatty liver disease: A scientific metrogy study.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases encountered in clinical practice. Curcumin can alleviate insulin resistance, inhibit oxidative stress response, reduce inflammation, reduce liver fat deposition, and effectively improve NAFLD through various modalities, inhibiting the progression into cirrhosis and fibrosis. PURPOSE: To explore the current status, hot spots, and developing trends of curcumin in NAFLD treatment through quantitative scientific analysis to serve as a reference for subsequent studies. STUDY DESIGN: A comprehensive analysis of the mechanism of action of curcumin in the treatment of NAFLD and methods to increase curcumin bioavailability using bibliometric analysis and literature review. METHODS: This study used VOSviewer software to analyze the literature related to curcumin treatment of NAFLD in the Web of Science (WOS) core set database. A comprehensive and in-depth review was conducted based on the results of scientific econometric research and literature review. RESULTS: The review observed that curcumin can activate various signaling pathways such as AMPK and NF-κB to inhibit oxidative stress and apoptosis, thereby reflecting its pharmacological effects: lowering lipid, anti-inflammatory, reducing insulin resistance, and anti-fibrosis. These mechanisms improve or even reverse the complex pathological features of lipid metabolism disorders associated with NAFLD. Curcumin also can potentially serve as a primary regulatory target for treating hepatic steatosis using gut microbiota. However, these pharmacological effects of curcumin were limited owing to its low bioavailability. CONCLUSION: This review discusses NAFLD treatment with curcumin, analyzes the reasons for its low bioavailability, and introduces models for studying and methods for improving curcumin bioavailability. As research on NAFLD grows, future research should capture the trend of basic research, pay attention to clinical research, and continuously explore the therapeutic potential of curcumin.

UPLC-Q-TOF-MS based investigation into the bioactive compounds and molecular mechanisms of Lamiophlomis Herba against hepatic fibrosis.

BACKGROUND: Lamiophlomis Herba (LH) is a valuable traditional medicinal plant found on the Qinghai-Tibetan Plateau that promotes blood circulation, removes blood stasis, and has antibacterial and anti-inflammatory properties. The main components of LH are iridoid glycosides, phenethyl alcohol glycosides, flavonoids, and polysaccharides. PURPOSE: To investigate the mechanism of the anti-liver fibrosis effects of LH and screen for its bioactive compounds. STUDY DESIGN: Screening LH marker components and validating the LH anti-liver fibrosis mechanism. METHODS: The active ingredients of LH were identified using UPLC-Q-TOF-MS, and HotMap combined with principal components analysis (PCA) was used to screen for marker components. Network pharmacology and molecular docking techniques were used to predict the potential anti-fibrotic targets of LH. Immunofluorescence, enzyme-linked immunosorbent assay (ELISA), real-time PCR (RT-PCR), and western blotting were used for experimental validation and mechanistic studies. RESULTS: Fifteen compounds that actively contributed to the cluster were identified as marker compounds. Acteoside, 8-O-acetyl shanzhiside methyl ester (8-O-ASME), Luteolin, Shanzhiside Methyl ester (SME), Loganin, Loganate were the main active components. Network pharmacology and molecular docking studies have shown that LH might improve liver fibrosis, inflammation, and oxidative stress, which might be related to key targets such as PTGS2, MAPK, EGFR, AKT1, SRC, Fn1, Col3a1, Col1a1, and PC-III. The results of ELISA, RT-PCR and western blot experiments showed that Acteoside, 8-O-ASME, Luteolin, SME, Loganin, Loganate, and the LH group could reduce the levels of fibronectin, Col1a1, Col3a1, α-SMA, Col-Ⅳ, LN, and PC-Ⅲ. CONCLUSION: LH improves liver fibrosis induced by HSC-T6 cells and inhibits the deposition of extracellular matrix (ECM) in hepatocytes, resulting in a decrease in the degree of liver fibrosis and a good anti-liver fibrosis effect.

Tubulointerstitial nephritis antigen-like 1 is a novel matricellular protein that promotes gastric bacterial colonization and gastritis in the setting of Helicobacter pylori infection.

The interaction between the gastric epithelium and immune cells plays key roles in H. pylori-associated pathology. Here, we demonstrate a procolonization and proinflammatory role of tubulointerstitial nephritis antigen-like 1 (TINAGL1), a newly discovered matricellular protein, in H. pylori infection. Increased TINAGL1 production by gastric epithelial cells (GECs) in the infected gastric mucosa was synergistically induced by H. pylori and IL-1ß via the ERK-SP1 pathway in a cagA-dependent manner. Elevated human gastric TINAGL1 correlated with H. pylori colonization and the severity of gastritis, and mouse TINAGL1 derived from non-bone marrow-derived cells promoted bacterial colonization and inflammation. Importantly, H. pylori colonization and inflammation were attenuated in Tinagl1-/- and Tinagl1ΔGEC mice and were increased in mice injected with mouse TINAGL1. Mechanistically, TINAGL1 suppressed CCL21 expression and promoted CCL2 production in GECs by directly binding to integrin α5ß1 to inhibit ERK and activate the NF-κB pathway, respectively, which not only led to decreased gastric influx of moDCs via CCL21-CCR7-dependent migration and, as a direct consequence, reduced the bacterial clearance capacity of the H. pylori-specific Th1 response, thereby promoting H. pylori colonization, but also resulted in increased gastric influx of Ly6Chigh monocytes via CCL2-CCR2-dependent migration. In turn, TINAGL1 induced the production of the proinflammatory protein S100A11 by Ly6Chigh monocytes, promoting H. pylori-associated gastritis. In summary, we identified a model in which TINAGL1 collectively ensures H. pylori persistence and promotes gastritis.

Artesunate inhibits PDE4 leading to intracellular cAMP accumulation, reduced ERK/MAPK signaling, and blockade of influenza A virus vRNP nuclear export.

Influenza A viruses (IAV) have been a major cause of mortality. Given the potential for future deadly pandemics, effective drugs are needed for the treatment of severe influenzas, such as those caused by H5N1 IAV. The anti-malaria drugs artemisinin and its derivates, including artesunate (AS), have been reported to have broad antiviral activities. Here, we showed AS's antiviral activity against H5N1, H1N1, H3N2 and oseltamivir-resistant influenza A(H1N1)virus in vitro. Moreover, we showed that AS treatment significantly protected mice from lethal challenges with H1N1 and H5N1 IAV. Strikingly, the combination of AS and peramivir treatment significantly improved survival outcomes compared to their monotherapy with either AS or peramivir. Furthermore, we demonstrated mechanistically that AS affected the later stages of IAV replication and limited nuclear export of viral ribonucleoprotein (vRNP) complexes. In A549 cells, we demonstrated for the first time that AS treatment induced cAMP accumulation via inhibiting PDE4, and consequently reduced ERK phosphorylation and blocked IAV vRNP export, and thus suppressed IAV replication. These AS's effects were reversed by the pre-treatment with a cAMP inhibitor SQ22536. Our findings suggest that AS could serve as a novel IAV inhibitor by interfering vRNP nuclear export to prevent and treat IAV infection.

Antiviral Effect of Ginsenosides rk1 against Influenza a Virus Infection by Targeting the Hemagglutinin 1-Mediated Virus Attachment.

Influenza A virus (IAV) infections have been a serious hazard to public health everywhere. With the growing concern of drug-resistant IAV strains, there is an urgent need for novel anti-IAV medications, especially those with alternative mechanisms of action. Hemagglutinin (HA), an IAV glycoprotein, plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a good target for developing anti-IAV drugs. Panax ginseng is a widely used herb in traditional medicine with extensive biological effects in various disease models, and its extract was reported to show protection in IAV-infected mice. However, the main effective anti-IAV constituents in panax ginseng remain unclear. Here, we report that ginsenoside rk1 (G-rk1) and G-rg5, out of the 23 screened ginsenosides, exhibit significant antiviral effects against 3 different IAV subtypes (H1N1, H5N1, and H3N2) in vitro. Mechanistically, G-rk1 blocked IAV binding to sialic acid in a hemagglutination inhibition (HAI) assay and an indirect ELISA assay; more importantly, we showed that G-rk1 interacted with HA1 in a dose-dependent manner in a surface plasmon resonance (SPR) analysis. Furthermore, G-rk1 treatment by intranasal inoculation effectively reduced the weight loss and mortality of mice challenged with a lethal dose of influenza virus A/Puerto Rico/8/34 (PR8). In conclusion, our findings reveal for the first time that G-rk1 possesses potent anti-IAV effects in vitro and in vivo. We have also identified and characterized with a direct binding assay a novel ginseng-derived IAV HA1 inhibitor for the first time, which could present potential approaches to prevent and treat IAV infections.

Extracellular vesicles as next generation immunotherapeutics.

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

The medicinal value of tea drinking in the management of COVID-19.

Corona Virus Disease 2019 (COVID-19) is presently the largest international public health event, individuals infected by the virus not only have symptoms such as fever, dry cough, and lung infection at the time of onset, but also possibly have sequelae in the cardiovascular system, respiratory system, nervous system, mental health and other aspects. However, numerous studies have depicted that the active ingredients in tea show good antiviral effects and can treat various diseases by regulating multiple pathways, and the therapeutic effects are associated with the categories of chemical components in tea. In this review, the differences in the content of key active ingredients in different types of tea are summarized. In addition, we also highlighted their effects on COVID-19 and connected sequelae, further demonstrating the possibility of developing a formulation for the prevention and treatment of COVID-19 and its sequelae through tea extracts. We have a tendency to suggest forestalling and treating COVID-19 and its sequelae through scientific tea drinking.

Toosendanin activates caspase-1 and induces maturation of IL-1ß to inhibit type 2 porcine reproductive and respiratory syndrome virus replication via an IFI16-dependent pathway.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a prevalent and endemic swine pathogen which causes significant economic losses in the global swine industry. Multiple vaccines have been developed to prevent PRRSV infection. However, they provide limited protection. Moreover, no effective therapeutic drugs are yet available. Therefore, there is an urgent need to develop novel antiviral strategies to prevent PRRSV infection and transmission. Here we report that Toosendanin (TSN), a tetracyclic triterpene found in the bark or fruits of Melia toosendan Sieb. et Zucc., strongly suppressed type 2 PRRSV replication in vitro in Marc-145 cells and ex vivo in primary porcine alveolar macrophages (PAMs) at sub-micromolar concentrations. The results of transcriptomics revealed that TSN up-regulated the expression of IFI16 in Marc-145 cells. Furthermore, we found that IFI16 silencing enhanced the replication of PRRSV in Marc-145 cells and that the anti-PRRSV activity of TSN was dampened by IFI16 silencing, suggesting that the inhibition of TSN against PRRSV replication is IFI16-dependent. In addition, we showed that TSN activated caspase-1 and induced maturation of IL-1ß in an IFI16-dependent pathway. To verify the role of IL-1ß in PRRSV infection, we analyzed the effect of exogenous rmIL-1ß on PRRSV replication, and the results showed that exogenous IL-1ß significantly inhibited PRRSV replication in Marc-145 cells and PAMs in a dose-dependent manner. Altogether, our findings indicate that TSN significantly inhibits PRRSV replication at very low concentrations (EC50: 0.16-0.20 µM) and may provide opportunities for developing novel anti-PRRSV agents.

Animal models for studying coronavirus infections and developing antiviral agents and vaccines.

In addition to severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), SARS-CoV-2 has become the third deadly coronavirus that infects humans and causes the new coronavirus disease (COVID-19). COVID-19 has already caused more than six million deaths worldwide and it is likely the biggest pandemic of this century faced by mankind. Although many studies on SARS-CoV-2 have been conducted, a detailed understanding of SARS-CoV-2 and COVID-19 is still lacking. Animal models are indispensable for studying its pathogenesis and developing vaccines and antivirals. In this review, we analyze animal models of coronavirus infections and explore their applications on antivirals and vaccines.

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/PB2320-331 and A11/PB2323-331) and the first HLA-A*11:01-restricted IBV epitopes (A11/M41-49, A11/NS1186-195 and A11/NP511-520). 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.

Distribution, phenotype, functional and clinical relevance of CD8+CD103+ tissue-resident memory T cells in human gastric cancer.

CD8+CD103+ tissue-resident memory T cells (TRMs) are involved in tumor immune response and linked to favorable clinical outcome in human cancer. However, the distribution, phenotype, functional properties and clinical relevance of these cells in gastric cancer (GC) remain elusive. Here, our data show that, in comparison to non-tumor tissues, the percentages of CD8+CD103+ TRMs in tumors are significantly decreased. Most tumor-infiltrating CD8+CD103+ TRMs are CD45RA-CCR7- effector-memory cells with higher PD-1 and 4-1BB expression than those from non-tumor tissues. Further, tumor-infiltrating CD8+CD103+ TRMs show impaired cytolytic capacity due to decreased granzyme B and perforin expression. Moreover, ex vivo PD-1 blockade could restore the cytolytic capacity of tumor-infiltrating CD8+CD103+ TRMs, and such anti-PD-1-mediated reinvigoration of CD8+CD103+ TRMs could be further enhanced by 4-1BB co-stimulation. Finally, lower levels of Tumor-infiltrating CD8+CD103+ TRMs are positively correlated with GC progression and poor patients' survival. Our data suggest that restoring CD8+CD103+ TRM function by combining PD-1 blockade and 4-1BB co-stimulation may be a promising strategy for treating GC.

The Antimalaria Drug Artesunate Inhibits Porcine Reproductive and Respiratory Syndrome Virus Replication by Activating AMPK and Nrf2/HO-1 Signaling Pathways.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses to the pork industry worldwide. Currently, vaccine strategies provide limited protection against PRRSV transmission, and no effective drug is commercially available. Therefore, there is an urgent need to develop novel antiviral strategies to prevent PRRSV pandemics. This study showed that artesunate (AS), one of the antimalarial drugs, potently suppressed PRRSV replication in Marc-145 cells and ex vivo primary porcine alveolar macrophages (PAMs) at micromolar concentrations. Furthermore, we demonstrated that this suppression was closely associated with AS-activated AMPK (energy homeostasis) and Nrf2/HO-1 (inflammation) signaling pathways. AS treatment promoted p-AMPK, Nrf2, and HO-1 expression and, thus, inhibited PRRSV replication in Marc-145 and PAM cells in a time- and dose-dependent manner. These effects of AS were reversed when the AMPK or HO-1 gene was silenced by short interfering RNA. In addition, we demonstrated that AMPK works upstream of Nrf2/HO-1, as its activation by AS is AMPK dependent. Adenosine phosphate analysis showed that AS activates AMPK via improving the AMP/ADP-to-ATP ratio rather than direct interaction with AMPK. Altogether, our findings indicate that AS is a promising novel therapeutic for controlling PRRSV and that its anti-PRRSV mechanism, which involves the functional link between energy homeostasis and inflammation suppression pathways, may provide opportunities for developing novel antiviral agents. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) infections have continuously threatened the pork industry worldwide. Vaccination strategies provide very limited protection against PRRSV infection, and no effective drug is commercially available. We show that artesunate (AS), one of the antimalarial drugs, is a potent inhibitor against PRRSV replication in Marc-145 cells and ex vivo primary porcine alveolar macrophages (PAMs). Furthermore, we demonstrate that AS inhibits PRRSV replication via activation of AMPK-dependent Nrf2/HO-1 signaling pathways, revealing a novel link between energy homeostasis (AMPK) and inflammation suppression (Nrf2/HO-1) during viral infection. Therefore, we believe that AS may be a promising novel therapeutics for controlling PRRSV, and its anti-PRRSV mechanism may provide a strategy to develop novel antiviral agents.

FasL+ PD-L2+ Identifies a Novel Immunosuppressive Neutrophil Population in Human Gastric Cancer That Promotes Disease Progression.

Neutrophils constitute abundant cellular components in human gastric cancer (GC) tissues, but their protumorigenic subset in pathogenesis of GC progression is unclear. Here, it is found that patients with GC show significantly higher neutrophil infiltration in tumors that is regulated by CXCL12-CXCR4 chemotaxis. These tumor-infiltrating neutrophils express high level immunosuppressive molecules FasL and PD-L2, and this FasL+ PD-L2+ neutrophil subset with a unique phenotype constitutes at least 20% of all neutrophils in advanced GC and predicts poor patient survival. Tumor induces neutrophils to express FasL and PD-L2 proteins with similar phenotype to those in GC tumors in both time-dependent and dose-dependent manners. Mechanistically, Th17 cell-derived IL-17A and tumor cell-derived G-CSF can significantly induce neutrophil FasL and PD-L2 expression via activating ERK-NF-κB and JAK-STAT3 signaling pathway, respectively. Importantly, upon over-expressing FasL and PD-L2, neutrophils acquire immunosuppressive functions on tumor-specific CD8+ T-cells and promote the growth and progression of human GC tumors in vitro and in vivo, which can be reversed by blocking FasL and PD-L2 on these neutrophils. Thus, the work identifies a novel protumorigenic FasL+ PD-L2+ neutrophil subset in GC and provides new insights for human cancer immunosuppression and anti-cancer therapies targeting these pathogenic cells.

Broad-Based Influenza-Specific CD8+ T Cell Response without the Typical Immunodominance Hierarchy and Its Potential Implication.

Syngeneic murine systems have pre-fixed MHC, making them an imperfect model for investigating the impact of MHC polymorphism on immunodominance in influenza A virus (IAV) infections. To date, there are few studies focusing on MHC allelic differences and its impact on immunodominance even though it is well documented that an individual's HLA plays a significant role in determining immunodominance hierarchy. Here, we describe a broad-based CD8+ T cell response in a healthy individual to IAV infection rather than a typical immunodominance hierarchy. We used a systematic antigen screen approach combined with epitope prediction to study such a broad CD8+ T cell response to IAV infection. We show CD8+ T cell responses to nine IAV proteins and identify their minimal epitope sequences. These epitopes are restricted to HLA-B*44:03, HLA-A*24:02 and HLA-A*33:03 and seven out of the nine epitopes are novel (NP319-330# (known and demonstrated minimal epitope positions are subscripted; otherwise, amino acid positions are shown as normal text (for example NP 319-330 or NP 313-330)), M1124-134, M27-15, NA337-346, PB239-49, HA445-453 and NS1195-203). Additionally, most of these novel epitopes are highly conserved among H1N1 and H3N2 strains that circulated in Australia and other parts of the world.

Influenza virus infection selectively triggers the accumulation and persistence of more potent Helios-expressing Foxp3+ regulatory T cells in the lungs.

Foxp3+ regulatory T cells (Tregs) represent a special lineage of CD4+ T cells. Analysis of Treg response during primary and secondary influenza virus infection clearly demonstrates a robust accumulation of Tregs into the infected lungs and the existence of a population of long-lived antigen-specific memory Tregs in the same tissues after resolution of the infection. However, it remains unknown whether these Tregs co-express Helios, a member of the Ikaros transcription factor family. In this study, Foxp3+ Helios+ and Foxp3+ Helios- Tregs in the lungs, mLNs and spleens of influenza virus-infected and uninfected control mice were tracked. The data show that while there is a co-existence of Foxp3+ Helios+ and Foxp3+ Helios- Tregs in the tissues, the accumulated Tregs in the lungs and lung-draining mediastinal lymph nodes (mLNs) of the infected mice are highly enriched for Foxp3+ Helios+ cells. It was further demonstrated that, after the clearance of primary infection, Foxp3+ Helios+ cells have the ability to persist in the tissues over their Helios- counterparts. More importantly, Foxp3+ Helios+ Tregs accumulated in an accelerated kinetics during recall response to reinfection. In vitro analysis of Treg suppressive function revealed that Foxp3+ Helios+ Tregs are more capable of suppressing influenza virus-specific CD8+ T cell activation, cytokine production and proliferation. Together, the data provide new insights into Treg responses during primary and secondary influenza virus infection and suggest that Foxp3+ Helios+ Tregs predominantly drive the Treg responses.

Immune cellular networks underlying recovery from influenza virus infection in acute hospitalized patients.

How innate and adaptive immune responses work in concert to resolve influenza disease is yet to be fully investigated in one single study. Here, we utilize longitudinal samples from patients hospitalized with acute influenza to understand these immune responses. We report the dynamics of 18 important immune parameters, related to clinical, genetic and virological factors, in influenza patients across different severity levels. Influenza disease correlates with increases in IL-6/IL-8/MIP-1α/ß cytokines and lower antibody responses. Robust activation of circulating T follicular helper cells correlates with peak antibody-secreting cells and influenza heamaglutinin-specific memory B-cell numbers, which phenotypically differs from vaccination-induced B-cell responses. Numbers of influenza-specific CD8+ or CD4+ T cells increase early in disease and retain an activated phenotype during patient recovery. We report the characterisation of immune cellular networks underlying recovery from influenza infection which are highly relevant to other infectious diseases.

CD8+ T cells specific for an immunodominant SARS-CoV-2 nucleocapsid epitope cross-react with selective seasonal coronaviruses.

Efforts are being made worldwide to understand the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, including the impact of T cell immunity and cross-recognition with seasonal coronaviruses. Screening of SARS-CoV-2 peptide pools revealed that the nucleocapsid (N) protein induced an immunodominant response in HLA-B7+ COVID-19-recovered individuals that was also detectable in unexposed donors. A single N-encoded epitope that was highly conserved across circulating coronaviruses drove this immunodominant response. In vitro peptide stimulation and crystal structure analyses revealed T cell-mediated cross-reactivity toward circulating OC43 and HKU-1 betacoronaviruses but not 229E or NL63 alphacoronaviruses because of different peptide conformations. T cell receptor (TCR) sequencing indicated that cross-reactivity was driven by private TCR repertoires with a bias for TRBV27 and a long CDR3ß loop. Our findings demonstrate the basis of selective T cell cross-reactivity for an immunodominant SARS-CoV-2 epitope and its homologs from seasonal coronaviruses, suggesting long-lasting protective immunity.