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BackgroundAdvancing age is a major risk factor for respiratory viral infections. The infections are often prolonged and difficult to resolve resulting hospitalizations and mortality. The recent COVID-19 pandemic has highlighted this as elderly subjects have emerged as vulnerable populations that display increased susceptibility and severity to SARS-CoV-2. There is an urgent need to identify the probable mechanisms underlying this to protect against future outbreaks of such nature. Innate immunity is the first line of defense against viruses and its decline impacts downstream immune responses. This is because dendritic cells (DCs) and macrophages are key cellular elements of the innate immune system that can sense and respond to viruses by producing inflammatory mediators and priming CD4 and CD8 T-cell responses.ResultsWe investigated the changes in innate immune responses to SARS-CoV-2 as a function of age. Our results using human PBMCs from aged, middle-aged, and young subjects indicate that the activation of DCs and monocytes in response to SARS-CoV-2 is compromised with age. The impairment is most apparent in pDCs where both aged and middle-aged display reduced responses. The secretion of IL-29 that confers protection against respiratory viruses is also decreased in both aged and middle-aged subjects. In contrast, inflammatory mediators associated with severe COVID-19 including CXCL-8, TREM-1 are increased with age. This is also apparent in the gene expression data where pathways related host defense display an age dependent decrease with a concomitant increase in inflammatory pathways. Not only are the inflammatory pathways and mediators increased after stimulation with SARS-CoV-2 but also at homeostasis. In keeping with reduced DC activation, the induction of cytotoxic CD8 T cells is also impaired in aged subjects. However, the CD8 T cells from aged subjects display increased baseline activation in accordance with the enhanced baseline inflammation.ConclusionsOur results demonstrate a decline in protective anti-viral immune responses and increase in damaging inflammatory responses with age indicating that dysregulated innate immune responses play a significant role in the increased susceptibility of aged subjects to COVID-19. Furthermore, the dysregulation in immune responses develops early on as middle-aged demonstrate several of these changes.

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a pleiotropic cytokine, able to promote both myelopoiesis and activation of immune cells. Particularly in the lung, GM-CSF plays an important homeostatic role in the development and maintenance of alveolar macrophages, and is therefore considered to play a role in respiratory virus infections such as influenza and SARS-CoV-2, although the benefits of GM-CSF treatment in clinical studies remain inconclusive. To address this, we tested inhaled GM-CSF treatment in the Pneumonia Virus of Mice (PVM) mouse model. Our findings show that local GM-CSF therapy during PVM disease increased local neutrophilia and monocytederived cell influx, but diminished CD8+ T cells responses. Despite this, the observed effects on T cells and myeloid cells did not result in an altered clinical outcome during PVM infection. We conclude that inhaled GM-CSF therapy cannot be considered as a universal protective therapy in respiratory virus infections. [ABSTRACT FROM AUTHOR]

Immunological priming—in the context of either prior infection or vaccination—elicits protective responses against subsequent Mycobacterium tuberculosis (Mtb) infection. However, the changes that occur in the lung cellular milieu post-primary Mtb infection and their contributions to protection upon reinfection remain poorly understood. Using clinical and microbiological endpoints in a non-human primate reinfection model, we demonstrated that prior Mtb infection elicited a long-lasting protective response against subsequent Mtb exposure and was CD4+ T cell dependent. By analyzing data from primary infection, reinfection, and reinfection-CD4+ T cell-depleted granulomas, we found that the presence of CD4+ T cells during reinfection resulted in a less inflammatory lung milieu characterized by reprogrammed CD8+ T cells, reduced neutrophilia, and blunted type 1 immune signaling among myeloid cells. These results open avenues for developing vaccines and therapeutics that not only target lymphocytes but also modulate innate immune cells to limit tuberculosis (TB) disease. [Display omitted] • CD4+ T cells are required for protection against Mtb reinfection in macaques • Mtb reinfection promotes immuno-modulatory CD8+ T cell-biased immunity • Myeloid-derived cells downregulate gene networks implicated in TB susceptibility • Self-reinforcing cellular circuits balance host immunity in reinfection granulomas Th1 CD4+ T cells mediate protective anti- Mtb immunity across biological systems and organisms. Bromley, Ganchua, et al. demonstrate that CD4+ T cells regulate immune tone in TB granulomas and are necessary for immune recall and protection against reinfection. Following reinfection, CD4+ T cells facilitate the development of a growth restrictive niche via the induction of immuno-modulatory genes and cellular interaction networks. [ABSTRACT FROM AUTHOR]

Although the functions of tyrosine phosphatases in T‐cell biology have been extensively studied, our knowledge on the contribution of serine/threonine phosphatases in T cells remains poor. Protein phosphatase 2A (PP2A) is one of the most abundantly expressed serine/threonine phosphatases. It is important in thymocyte development and CD4+ T‐cell differentiation. Utilizing a genetic model in which its catalytic subunit alpha isoform (PP2A Cα) is deleted in T cells, we investigated its contribution to CD8+ T‐cell homeostasis and effector functions. Our results demonstrate that T‐cell intrinsic PP2A Cα is critically required for CD8+ T‐cell homeostasis in secondary lymphoid organs and intestinal mucosal site. Importantly, PP2A Cα–deficient CD8+ T cells exhibit reduced proliferation and survival. CD8+ T‐cell antibacterial response is strictly dependent on PP2A Cα. Expression of Bcl2 transgene rescues CD8+ T‐cell homeostasis in spleens, but not in intestinal mucosal site, nor does it restore defective antibacterial responses. Finally, proteomics and phosphoproteomics analyses reveal potential targets dependent on PP2A Cα, including mTORC1 and AKT. Thus, PP2A Cα is a key modulator of CD8+ T‐cell homeostasis and effector functions. [ABSTRACT FROM AUTHOR]

Aging is a gradual, inevitable physiologic process. The organ aging is related to the persistence of chronic inflammation, but the understanding of inflammatory state during renal aging is lacking currently. Single-cell transcriptome sequencing was performed on aging mouse kidney to reveal the molecular phenotype and composition changes of different cell types. In the early stage of aging, immune cells such as T, B cells and mononuclear macrophages increased in kidney. The molecular state of T cells in aging kidney changed and polarized. Among them, we identified a group of GZMK + CD8 + T cells with high expression of Eomes , Pdcd1 and Ifng and a group of Il17a + T cells with high expression of Il17a and Il23r. Moreover, the cytokines and inflammations can aggravate tissue damage eventually. Furthermore, we found the interaction between different types of epithelial cells and T cells increased during the renal aging. These results identify the changes of T cells in the early stage of aging kidney and suggest that GZMK+CD8+ T cells might be a potential target to ameliorate age-associated dysfunctions of kidney(Graphical Abstract). [Display omitted] • Kidney undergoes the most severe structural and functional deterioration with aging. • Organ aging is related to chronic inflammation, and persist inflammation hinders intrinsic cell repair. • Immune cells increased in the early stage of kidney aging. • The molecular state of T cells in aging kidney changed and polarized. • The crosstalk between different types of epithelial cells and immune cells increased. [ABSTRACT FROM AUTHOR]

Research is underway to develop a vaccine to prevent and cure infection from herpes simplex virus (HSV). It emphasizes the critical need for immunization to address public health issues and the shortcomings of existing treatment options. Furthermore, studies on the HSV vaccine advance the field of immunology and vaccine creation, which may help in the battle against other viral illnesses. The current lack of such a vaccine is, in part, due to herpes viral latency in sensory ganglions. Current vaccines rely on tissue-resident memory CD8+ T cells, which are known to provide protection against subsequent HSV reinfection and reactivation without correlating with other immune subsets. For that reason, there is no effective vaccine that can provide protection against latent or recurrent herpes infection. This review focuses on conventional methods for evaluating the efficacy of a herpes vaccine using differential CD8+ T cells and important unaccounted immune aspects for designing an effective vaccine against herpes. [ABSTRACT FROM AUTHOR]

Background/Aim: Oral squamous cell carcinoma (OSCC) presents a significant health challenge, requiring effective treatments. Magnolol, a compound with potential anticancer properties, warrants investigation in OSCC treatment. Here, we aimed to assess the efficacy of magnolol in inhibiting progression of OSCC and to explore the underlying mechanisms of its action. Materials and Methods: We evaluated the effect of magnolol on tumor progression using the MOC1- bearing orthotopic model. We examined its impact on pathology and toxicity through hematoxylin and eosin (H&E) staining, immunohistochemistry (IHC), and biochemical analysis. We also investigated the immunoregulatory effects of magnolol in the MOC1-bearing model using flow cytometry. Results: At high doses, magnolol significantly reduced tumor volume (p<0.0001 for comparisons between treated with magnolol and untreated groups) and weight loss by 70% in vivo. It also induced caspase-dependent apoptosis, evidenced by 2.42-, 2-, and 2.2- fold increases in the expression of caspase-3, -8, and -9, respectively, in mouse tumors treated with high 60 mg/kg of magnolol compared to untreated (p<0.0001 for all comparisons). Magnolol demonstrated no toxicity, maintaining body weight and normal biochemical parameters, including liver and kidney function. Pathological evaluations showed no adverse effects on organs in all treatment groups. Moreover, high doses of magnolol enhanced natural killer cells (by 3%), dendritic cells (20-25%), and cytotoxic T cells (20-40%) while reducing myeloid-derived suppressor cells and regulatory T cells by 1.5 times. Conclusion: Magnolol demonstrates potential as a therapeutic agent for OSCC, offering antitumor efficacy and immunomodulatory benefits. [ABSTRACT FROM AUTHOR]

Abstract CD8+ T lymphocytes are critical in the immune response against neoplasms, yet the prognostic relevance of CD8+ T cell-associated genes in hepatocellular carcinoma (HCC) is not fully understood. We sourced single-cell RNA-sequencing (scRNA-seq) and bulk RNA-seq data for HCC from the GSE98638 dataset and The Cancer Genome Atlas (TCGA) repository. We utilized Weighted Gene Correlation Network Analysis (WGCNA) to identify CD8+ T cell-related genes. A clinical prognostic model for risk stratification was then constructed via Cox-Lasso regression analysis. The Immunophenotypic Score (IPS) was utilized to evaluate the potential of immunotherapeutic interventions in the categorized cohorts. Validation of the expression of CD8+ T cell-associated risk genes was performed using quantitative reverse transcription PCR (qRT-PCR). Integrating scRNA-seq with RNA-seq data, we identified five CD8+ T cell-related signature genes: IKBKE, ATP1B3, MSC, ADA, and BATF. Notably, HCC patients in the high-risk group had markedly decreased overall survival. Elevated infiltration levels of CD8+ T cells, B cells, and macrophages were observed in the high-risk group. Moreover, there was a positive correlation between the risk score and immune checkpoints (ICPs), including PDCD1, CD274, and CTLA4. Patients within the high-risk group subject to PD1 and CTLA4 blockade exhibited higher IPS levels. Additionally, the expression of the five risk genes was upregulated in HCC cell lines and tissues compared to normal cells and tissues. Our findings establish a prognostic signature based on CD8+ T cells, offering a potent predictive model for clinical outcomes and responsiveness to immunotherapy in HCC patients.

IL-27, a member of the IL-6/IL-12 cytokine superfamily, is primarily secreted by antigen presenting cells, specifically by dendric cells, macrophages and B cells. IL-27 has antiviral activities and modulates both innate and adaptive immune responses against viruses. The role of IL-27 in the setting of viral infections is not well defined and both pro-inflammatory and anti-inflammatory functions have been described. Here, we discuss the latest advancements in the role of IL-27 in several viral infection models of human disease. We highlight important aspects of IL-27 expression regulation, the critical cell sources at different stages of the infection and their impact in cellmediated immunity. Lastly,we discuss the need to better define the antiviral andmodulatory (pro-inflammatory vs anti-inflammatory) properties of IL-27 in the context of human chronic viral infections. [ABSTRACT FROM AUTHOR]

CD8+ T lymphocytes are critical in the immune response against neoplasms, yet the prognostic relevance of CD8+ T cell-associated genes in hepatocellular carcinoma (HCC) is not fully understood. We sourced single-cell RNA-sequencing (scRNA-seq) and bulk RNA-seq data for HCC from the GSE98638 dataset and The Cancer Genome Atlas (TCGA) repository. We utilized Weighted Gene Correlation Network Analysis (WGCNA) to identify CD8+ T cell-related genes. A clinical prognostic model for risk stratification was then constructed via Cox-Lasso regression analysis. The Immunophenotypic Score (IPS) was utilized to evaluate the potential of immunotherapeutic interventions in the categorized cohorts. Validation of the expression of CD8+ T cell-associated risk genes was performed using quantitative reverse transcription PCR (qRT-PCR). Integrating scRNA-seq with RNA-seq data, we identified five CD8+ T cell-related signature genes: IKBKE, ATP1B3, MSC, ADA, and BATF. Notably, HCC patients in the high-risk group had markedly decreased overall survival. Elevated infiltration levels of CD8+ T cells, B cells, and macrophages were observed in the high-risk group. Moreover, there was a positive correlation between the risk score and immune checkpoints (ICPs), including PDCD1, CD274, and CTLA4. Patients within the high-risk group subject to PD1 and CTLA4 blockade exhibited higher IPS levels. Additionally, the expression of the five risk genes was upregulated in HCC cell lines and tissues compared to normal cells and tissues. Our findings establish a prognostic signature based on CD8+ T cells, offering a potent predictive model for clinical outcomes and responsiveness to immunotherapy in HCC patients. [ABSTRACT FROM AUTHOR]

Background: The impact of chronic hepatic infection on antigen non-specific immune cells in circulation remains poorly understood. We reported lasting global hyperfunction of peripheral CD8 T cells in HCV-infected individuals with cirrhosis. Whether gene expression patterns in bulk CD8 T cells are associated with the severity of liver fibrosis in HCV infection is not known. Methods: RNA sequencing of blood CD8 T cells from treatment naïve, HCV infected individuals with minimal (Metavir F0-1 ≤ 7.0 kPa) or advanced fibrosis or cirrhosis (F4 ≥ 12.5 kPa), before and after direct-acting antiviral therapy, was performed. CD8 T cell function was assessed by flow cytometry. Results: In CD8 T cells from pre-DAA patients with advanced compared to minimal fibrosis, Gene Ontology analysis and Gene Set Enrichment Analysis identified differential gene expression related to cellular function and metabolism, including upregulated Hedgehog (Hh) signaling, IFN-a, -g, TGF-b response genes, apoptosis, apical surface pathways, phospholipase signaling, phosphatidyl-choline/inositol activity, and second-messenger-mediated signaling. In contrast, genes in pathways associated with nuclear processes, RNA transport, cytoskeletal dynamics, cMyc/E2F regulation, oxidative phosphorylation, and mTOR signaling, were reduced. Hh signaling pathway was the top featured gene set upregulated in cirrhotics, wherein hallmark genes GLI1 and PTCH1 ranked highly. Inhibition of Smo-dependent Hh signaling ablated the expression of IFN-g and perforin in stimulated CD8 T cells from chronic HCV-infected patients with advanced compared to minimal fibrosis. CD8 T cell gene expression profiles post-DAA remained clustered with pre-DAA profiles and disparately between advanced and minimal fibrosis, suggesting a persistent perturbation of gene expression long after viral clearance. Conclusions: This analysis of bulk CD8 T cell gene expression in chronic HCV infection suggests considerable reprogramming of the CD8 T cell pool in the cirrhotic state. Increased Hh signaling in cirrhosis may contribute to generalized CD8 T cell hyperfunction observed in chronic HCV infection. Understanding the lasting nature of immune cell dysfunction may help mitigate remaining clinical challenges after HCV clearance and more generally, improve long term outcomes for individuals with severe liver disease. [ABSTRACT FROM AUTHOR]

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a pleiotropic cytokine, able to promote both myelopoiesis and activation of immune cells. Particularly in the lung, GM-CSF plays an important homeostatic role in the development and maintenance of alveolar macrophages, and is therefore considered to play a role in respiratory virus infections such as influenza and SARS-CoV-2, although the benefits of GM-CSF treatment in clinical studies remain inconclusive. To address this, we tested inhaled GM-CSF treatment in the Pneumonia Virus of Mice (PVM) mouse model. Our findings show that local GM-CSF therapy during PVM disease increased local neutrophilia and monocyte-derived cell influx, but diminished CD8+ T cells responses. Despite this, the observed effects on T cells and myeloid cells did not result in an altered clinical outcome during PVM infection. We conclude that inhaled GM-CSF therapy cannot be considered as a universal protective therapy in respiratory virus infections.

Summary: Background: Mouse models that recapitulate key features of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection are important tools for understanding complex interactions between host genetics, immune responses, and SARS-CoV-2 pathogenesis. Little is known about how predominantly cellular (Th1 type) versus humoral (Th2 type) immune responses influence SARS-CoV-2 dynamics, including infectivity and disease course. Methods: We generated knock-in (KI) mice expressing human ACE2 (hACE2) and/or human TMPRSS2 (hTMPRSS2) on Th1-biased (C57BL/6; B6) and Th2-biased (BALB/c) genetic backgrounds. Mice were infected intranasally with SARS-CoV-2 Delta (B.1.617.2) or Omicron BA.1 (B.1.1.529) variants, followed by assessment of disease course, respiratory tract infection, lung histopathology, and humoral and cellular immune responses. Findings: In both B6 and BALB/c mice, hACE2 expression was required for infection of the lungs with Delta, but not Omicron BA.1. Disease severity was greater in Omicron BA.1-infected hTMPRSS2-KI and double-KI BALB/c mice compared with B6 mice, and in Delta-infected double-KI B6 and BALB/c mice compared with hACE2-KI mice. hACE2-KI B6 mice developed more severe lung pathology and more robust SARS-CoV-2-specific splenic CD8 T cell responses compared with hACE2-KI BALB/c mice. There were no notable differences between the two genetic backgrounds in plasma cell, germinal center B cell, or antibody responses to SARS-CoV-2. Interpretation: SARS-CoV-2 Delta and Omicron BA.1 infection, disease course, and CD8 T cell response are influenced by the host genetic background. These humanized mice hold promise as important tools for investigating the mechanisms underlying the heterogeneity of SARS-CoV-2-induced pathogenesis and immune response. Funding: This work was funded by NIH U19 AI142790-02S1, the GHR Foundation, the Arvin Gottleib Foundation, and the Overton family (to SS and EOS); Prebys Foundation (to SS); NIH R44 AI157900 (to KJ); and by an American Association of Immunologists Career Reentry Fellowship (FASB).

Wei Liao,1,2,&ast; Jiaxuan Lu,3,&ast; Yuyuan Xu,4,&ast; Chulin Yang,1,5 Hongjie Chen,4 Shaohang Cai,4 Lili Liu,1,6 Shuwei Chen1,5 1State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China; 2Department of Intensive Care Unit, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China; 3Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China; 4Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, People’s Republic of China; 5Department of Head and Neck Surgery, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China; 6Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Shaohang Cai, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, People’s Republic of China, Email shaohangcai@foxmail.com Shuwei Chen, Department of Head and Neck Surgery, Sun Yat-sen University Cancer Center, Dongfeng East Road, Guangzhou, 510060, People’s Republic of China, Email chenshuw@sysucc.org.cnBackground: To compare and analyze the presence of CD4+ and CD8 + lymphocyte infiltrates in Oral squamous cell carcinoma (OSCC) tissue versus adjacent tissue and their clinical significance.Methods: We enrolled a total of 152 patients diagnosed with OSCC, all of whom had confirmed diagnoses through pathological reports. Clinical and demographics data were extracted from medical records. Tissue microarrays were constructed and immunohistochemical staining for CD4 and CD8 was performed.Findings: The average number of infiltrating CD4+ T cells in OSCC tumor tissue was 1026.22± 1163.36 cells/mm2, which did not significantly differ from the count in adjacent tissue, which was 1163.36± 1013.23 cells/mm2. However, the number of CD8+ T cell infiltration in tumor tissue was significantly higher than in adjacent tissue (655.25± 705.70 vs 504.56± 659.26 cells/mm2, p = 0.026). We observed that, among patients who consumed alcohol, the CD4+ T cell infiltration in tumor tissue being significantly lower than that in adjacent tissue (P=0.036). Moreover, the CD8+ T cell infiltration in cancer tissue was significantly higher than in adjacent tissue for T1-2 patients (p=0.005). Patients with higher CD8+ T cell in tumor tissue exhibited significantly improved overall survival (p = 0.043). Multivariate analyses revealed that alcohol consumption had a significant impact on the number of CD4+T lymphocytes in tumor tissue (OR = 0.403, P = 0.033) while T stage was the independent factor affecting CD8+ T lymphocyte infiltration in tumor tissue (OR = 0.459, P = 0.031).Interpretation: OSCC patients with a higher number of CD8+ T lymphocyte infiltration in tumor tissue exhibited an improved prognosis.Keywords: microenvironment, OSCC, CD8 T cells, CD4 T cells, prognosis

In the face of the ever-present burden of emerging and reemerging infectious diseases, there is a growing need to comprehensively assess individual- and population-level immunity to vaccine-preventable diseases (VPDs). Many of these efforts, however, focus exclusively on antibody-mediated immunity, ignoring the role of T cells. Aimed at clinicians, public health practioners, and others who play central roles in human vaccine research but do not have formal training in immunology, we review how vaccines against infectious diseases elicit T cell responses, what types of vaccines elicit T cell responses, and how T cell responses are measured. We then use examples to demonstrate six ways that T cells contribute to protection from VPD, including directly mediating protection, enabling antibody responses, reducing disease severity, increasing cross-reactivity, improving durability, and protecting special populations. We conclude with a discussion of challenges and solutions to more widespread consideration of T cell responses in clinical vaccinology.

The release of CCL5 and CXCL10 is essential for recruiting cytotoxic immune cells into the tumor microenvironment and enhancing the efficacy of cancer immunotherapy. Type I IFNs, particularly IFNβ, activate signaling pathways that induce the expression of these chemokines. In our recent study, we explored the impact and underlying mechanisms of inhibiting the kinase activity of VPS34, a key lipid kinase in the autophagy/endosomal trafficking system, on the expression of CCL5 and CXCL10 in preclinical cancer mouse models. Using NanoString gene expression technology, we analyzed tumors from mice treated with the VPS34 inhibitor SB02024 and demonstrated that the expression of CCL5 and CXCL10 is increased through a cGAS-STING-dependent mechanism within cancer cells. In vitro, both pharmacological inhibition and genetic targeting of VPS34 enhance cGAS-STING-mediated expression and secretion of CCL5 and CXCL10 across various tumor cell types. In vivo, treatment with the VPS34 inhibitor SB02024 enhances the positive effects of the STING agonist ADU-S100 in melanoma tumor-bearing mice. Thus, our study suggests that VPS34 inhibitors could be used to enhance STING-based anticancer therapies.Abbreviations CCL5 (C-C motif chemokine 5); CXCL10 (C-X-C motif chemokine 10); IFN (interferon); VPS34 (vacuolar protein sorting 34); cGAS (cyclic GMP-AMP Synthase); STING (stimulator of interferon genes protein); cGAMP (2′3′-cyclic guanosine monophosphate–adenosine monophosphate).

We have recently demonstrated that inhibiting VPS34 enhances T-cell-recruiting chemokines through the activation of the cGAS/STING pathway using the STING agonist ADU-S100. Combining VPS34 inhibitors with ADU-S100 increased cytokine release and improved tumor control in mouse models, suggesting a potential synergy between VPS34 inhibition and therapies based on STING agonists.

ABSTRACTCytotoxic T lymphocytes are key for controlling viral infection. Unravelling CD8+ T cell-mediated immunity to distinct influenza virus strains and subtypes across prominent HLA types is relevant for combating seasonal infections and emerging new variants. Using an immunopeptidomics approach, naturally presented influenza A virus-derived ligands restricted to HLA-A*24:02, HLA-A*68:01, HLA-B*07:02, and HLA-B*51:01 molecules were identified. Functional characterization revealed multifunctional memory CD8+ T cell responses for nine out of sixteen peptides. Peptide presentation kinetics was optimal around 12 h post infection and presentation of immunodominant epitopes shortly after infection was not always persistent. Assessment of immunogenic epitopes revealed that they are highly conserved across the major zoonotic reservoirs and may contain a single substitution in the vicinity of the anchor residues. These findings demonstrate how the identified epitopes promote T cell pools, possibly cross-protective in individuals and can be potential targets for vaccination.

Introduction: Innate immune training is a metabolic, functional, and epigenetic long-term reprogramming of innate cells triggered by different stimuli. This imprinting also reaches hematopoietic precursors in the bone marrow to sustain a memory-like phenotype. Dendritic cells (DCs) can exhibit memory-like responses, enhanced upon subsequent exposure to a pathogen; however, whether this imprinting is lineage and stimulus-restricted is still being determined. Nevertheless, the functional consequences of DCs training on the adaptive and protective immune response against non-infectious diseases remain unresolved. Methods: We evaluated the effect of the nontoxic cholera B subunit (CTB), LPS and LTA in the induction of trained immunity in murine DCs revealed byTNFa and LDH expression, through confocal microscopy. Additionally, we obtained bone marrow DCs (BMDCs) from mice treated with CTB, LPS, and LTA and evaluated training features in DCs and their antigen-presenting cell capability using multiparametric cytometry. Finally, we design an experimental melanoma mouse model to demonstrate protection induced by CTB-trained DCs in vivo. Results: CTB-trained DCs exhibit increased expression of TNFa, and metabolic reprogramming indicated by LDH expression. Moreover, CTB training has an imprint on DC precursors, increasing the number and antigen-presenting function in BMDCs. We found that training by CTB stimulates the recruitment of DC precursors and DCs infiltration at the skin and lymph nodes. Interestingly, training-induced by CTB promotes a highly co-stimulatory phenotype in tumor-infiltrating DCs (CD86+) and a heightened functionality of exhausted CD8 T cells (Ki67+, GZMB+), which were associated with a protective response against melanoma challenge in vivo. Conclusion: Our work indicates that CTB can induce innate immune training on DCs, which turns into an efficient adaptive immune response in the melanoma model and might be a potential immunotherapeutic approach for tumor growth control. [ABSTRACT FROM AUTHOR]

Tumor cell-derived extracellular vesicles (EVs) play a crucial role in mediating immune responses by carrying and presenting tumor antigens. Here, we suggested that melanoma EVs triggered cytotoxic CD8 T cell-mediated inhibition of tumor growth and metastasis. Our results indicated that immunization of mice with melanoma EVs inhibited melanoma growth and metastasis while increasing CD8 T cells and serum interferon γ (IFN-γ) in vivo. In vitro experiments showed that melanoma EV stimulates dendritic cells (DCs) maturation, and mature dendritic cells induce T lymphocyte activation. Thus, tumor cell-derived EVs can generate anti-tumor immunity in a prophylactic setting and may be potential candidates for cell-free tumor vaccines. [Display omitted] • Melanoma extracellular vesicles inhibit autologous tumor growth and metastasis. • Melanoma extracellular vesicles increase CD8 T cell levels and interferon γ expression in vivo. • Melanoma extracellular vesicles stimulate dendritic cell maturation and further induce T cell activation. [ABSTRACT FROM AUTHOR]

As severe acute respiratory coronavirus 2 (SARS-CoV-2) variants continue to emerge, it is important to characterize immune responses against variants which can inform on protection efficacies following booster vaccination. In this study, neutralizing breadth and antigen-specific CD8+ T cell responses were analyzed in both infection-naïve and infection-experienced individuals following administration of a booster bivalent Wuhan-Hu-1+BA.4/5 Comirnaty® mRNA vaccine. Significantly higher neutralizing titers were found after this vaccination compared to the pre-third booster vaccination time point. Further, neutralizing breadth to omicron variants, including BA.1, BA.2, BA.5, BQ.1 and XBB.1, was found to be boosted following bivalent vaccination. SARS-CoV-2-specific CD8+ T cells were identified, but with no evidence that frequencies were increased following booster vaccinations. Spike protein-specific CD8+ T cells were the only responses detected after vaccination and non-spike-specific CD8+ T cells were only detected after infection. Both spikespecific and non-spike-specificCD8+ T cells were found at much lower frequencies than CD8+ T cells specific to cytomegalovirus (CMV), Epstein-Barr virus (EBV) and influenza (Flu). Taken together, these results show that the bivalent Wuhan-Hu-1 +BA.4/5 Comirnaty® mRNA vaccine boosted the breadth of neutralization to newer SARS-CoV-2 variants and that vaccination is able to induce spike protein-specific CD8+ T cell responses, which are maintained longitudinally. [ABSTRACT FROM AUTHOR]

Corona Virus Disease 19 (COVID-19) has been a major pandemic impacting a huge population worldwide, and it continues to present serious health threats, necessitating the development of novel protective nutraceuticals. Biobran/MGN-3, an arabinoxylan rice bran, is a potent immunomodulator for both humans and animals that has recently been demonstrated to protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. We here investigate Biobran/MGN-3′s potential to enhance an antiviral immune response in humans. Peripheral blood mononuclear cells (PBMCs) derived from eight subjects taking Biobran/MGN-3 (age 55–65 years) and eight age-matched control subjects were stimulated with irradiated SARS-CoV-2 virus and then subjected to immuno-phenotyping and multiplex cytokine/chemokine assays. Results showed that PBMCs from subjects supplemented with Biobran/MGN-3 had significantly increased activation of plasmacytoid dendritic cells (pDCs) coupled with increased IFN-α secretion. We also observed higher baseline expression of HLA-DR (human leukocyte antigen-DR isotype) on dendritic cells (DCs) and increased secretion of chemokines and cytokines, as well as a substantial increase in cytotoxic T cell generation for subjects taking Biobran/MGN-3. Our results suggest that Biobran/MGN-3 primes immunity and therefore may be used for boosting immune responses against SARS-CoV-2 infections and other diseases, particularly in high-risk populations such as the elderly. [ABSTRACT FROM AUTHOR]

IL-27, a member of the IL-6/IL-12 cytokine superfamily, is primarily secreted by antigen presenting cells, specifically by dendric cells, macrophages and B cells. IL-27 has antiviral activities and modulates both innate and adaptive immune responses against viruses. The role of IL-27 in the setting of viral infections is not well defined and both pro-inflammatory and anti-inflammatory functions have been described. Here, we discuss the latest advancements in the role of IL-27 in several viral infection models of human disease. We highlight important aspects of IL-27 expression regulation, the critical cell sources at different stages of the infection and their impact in cell mediated immunity. Lastly, we discuss the need to better define the antiviral and modulatory (pro-inflammatory vs anti-inflammatory) properties of IL-27 in the context of human chronic viral infections.

Abstract Background Unlike conventional T cells, innate and virtual-memory CD8 T cells in naïve mice acquire their memory phenotypes and functions in the absence of antigenic encounters in a cytokine-dependent manner. The relevant cytokines include interleukin-4 (IL-4), type I interferon, and interleukin-15 (IL-15). Moreover, exogenous IL-4 can also induce de novo generation and/or expansion of the virtual-memory CD8 T cell population. In this study, we investigated whether exogenous IL-4 could enhance the immune response to a viral infection. Results In vivo administration of IL-4 and an anti-IL-4 antibody complex (IL-4C) increased CXCR3 expression in both memory and naïve phenotype CD8 T cells in the absence of antigenic stimulation, and protected mice from lethal influenza infection. Flow cytometric analysis of lung-infiltrating immune cells on day 5 after virus infection revealed higher numbers of antigen-specific and bystander CD8 T cells in IL-4C-treated mice than in control mice. In particular, the bystander CD8 T cells were a naïve or evident memory phenotypes. Crucially, an anti-CXCR3 blocking antibody abrogated this IL-4C effect, reflecting that the increased accumulation of CD8 T cells in the lungs after IL-4C treatment is dependent on CXCR3. Conclusions These data demonstrate that exogenous IL-4C plays a protective role by enhancing CXCR3-dependent migration of CD8 T cells into influenza-infected lungs.

Research is underway to develop a vaccine to prevent and cure infection from herpes simplex virus (HSV). It emphasizes the critical need for immunization to address public health issues and the shortcomings of existing treatment options. Furthermore, studies on the HSV vaccine advance the field of immunology and vaccine creation, which may help in the battle against other viral illnesses. The current lack of such a vaccine is, in part, due to herpes viral latency in sensory ganglions. Current vaccines rely on tissue-resident memory CD8+ T cells, which are known to provide protection against subsequent HSV reinfection and reactivation without correlating with other immune subsets. For that reason, there is no effective vaccine that can provide protection against latent or recurrent herpes infection. This review focuses on conventional methods for evaluating the efficacy of a herpes vaccine using differential CD8+ T cells and important unaccounted immune aspects for designing an effective vaccine against herpes.

Valganciclovir (VGC) was used in a randomized clinical trial in patients with disseminated Kaposi Sarcoma/human immunodeficiency virus (DKS/HIV) as add-on therapy to evaluate the proinflammatory axis tumor necrosis factor (TNF) and its receptors (TNFRs) in T cells. Two treatment schedules were used: an experimental regime (ER) and a conventional treatment (CT). Mononuclear cells from patients with DKS/HIV were obtained at baseline (W0), 4 (W4), and 12 weeks (W12). Ten DKS/HIV patients received CT (antiretroviral therapy [cART]) and 10 ER (valganciclovir [VGC] initially, plus cART at the fourth week). HIV+ without KS and HIV− patient groups were included as controls. Correlation between T-cell subsets and HHV-8 viral load (VL) and a multivariate linear regression was performed. Data showed that DKS/HIV patients have an increased frequency of CD8+ T cells, which display a high density of CD8 expression. The ER scheme increases naïve and central memory CD4+ T cells at W4 and W12 of follow-up and induces a balanced distribution of activated CD4+ T-cell subsets. Moreover, ER decreases solTNFR2 since W4 and CT decreased the transmembrane forms of TNF axis molecules. Although CT induces a positive correlation between HHV-8 VL and TNFRs, the use of ER positively correlates with TNF and TNFRs levels through follow-up and a moderate correlation with HHV-8 VL and TNF soluble levels. In conclusion, VGC, as an add-on therapy in DKS/HIV patients, gradually modulates the activation of CD4+ T-cell subsets and the TNF/TNFRs axis, suggesting a better regulation of the inflammatory status. Experimental regiment includes 4 weeks of valganciclovir before starting the antiretroviral therapy in DKS/HIV patients. Experimental regime (ER) induces a homogeneous distribution of activated CD4+ T cells and modulates efficiently the tumor necrosis factor (TNF) receptors (TNFR1 and TNFR2) levels. ER can provide a clinical benefit because an exacerbated inflammatory process could be avoided. Graphical Abstract [ABSTRACT FROM AUTHOR]

Cerebral malaria is the deadliest complication that can arise from Plasmodium infection. CD8 T-cell engagement of brain vasculature is a putative mechanism of neuropathology in cerebral malaria. To define contributions of brain endothelial cell major histocompatibility complex (MHC) class I antigen-presentation to CD8 T cells in establishing cerebral malaria pathology, we developed novel H-2Kb LoxP and H-2Db LoxP mice crossed with Cdh5-Cre mice to achieve targeted deletion of discrete class I molecules, specifically from brain endothelium. This strategy allowed us to avoid off-target effects on iron homeostasis and class I-like molecules, which are known to perturb Plasmodium infection. This is the first endothelial-specific ablation of individual class-I molecules enabling us to interrogate these molecular interactions. In these studies, we interrogated human and mouse transcriptomics data to compare antigen presentation capacity during cerebral malaria. Using the Plasmodium berghei ANKA model of experimental cerebral malaria (ECM), we observed that H-2Kb and H-2Db class I molecules regulate distinct patterns of disease onset, CD8 T-cell infiltration, targeted cell death and regional blood–brain barrier disruption. Strikingly, ablation of either molecule from brain endothelial cells resulted in reduced CD8 T-cell activation, attenuated T-cell interaction with brain vasculature, lessened targeted cell death, preserved blood–brain barrier integrity and prevention of ECM and the death of the animal. We were able to show that these events were brain-specific through the use of parabiosis and created the novel technique of dual small animal MRI to simultaneously scan conjoined parabionts during infection. These data demonstrate that interactions of CD8 T cells with discrete MHC class I molecules on brain endothelium differentially regulate development of ECM neuropathology. Therefore, targeting MHC class I interactions therapeutically may hold potential for treatment of cases of severe malaria. [ABSTRACT FROM AUTHOR]

How individual T cells compete for and respond to IL‐2 at the molecular level, and, as a consequence, how this shapes population dynamics and the selection of high‐affinity clones is still poorly understood. Here we describe how the RNA binding protein ZFP36L1, acts as a sensor of TCR affinity to promote clonal expansion of high‐affinity CD8 T cells. As part of an incoherent feed‐forward loop, ZFP36L1 has a nonredundant role in suppressing multiple negative regulators of cytokine signaling and mediating a selection mechanism based on competition for IL‐2. We suggest that ZFP36L1 acts as a sensor of antigen affinity and establishes the dominance of high‐affinity T cells by installing a hierarchical response to IL‐2. [ABSTRACT FROM AUTHOR]

The phenomenon of intercellular transfer of cellular material, including membranes, cytoplasm, and even organelles, has been observed for decades. The functional impact and molecular mechanisms of such transfer in the immune system remain largely elusive due to the absence of a robust in vivo model. Here, we introduce a new tumor mouse model, where tumor cells express the soluble ultra-bright fluorescent protein ZsGreen, which allows detection and measurement of intercellular transfer of cytoplasm from tumor cells to infiltrating immune cells. We found that in addition to various types of myeloid lineage cells, a large fraction of T regulatory cells and effector CD8 T cells acquire tumor material. Based on the distribution of tumor-derived ZsGreen, the majority of T cells integrate captured cytoplasm into their own, while most myeloid cells store tumor material in granules. Furthermore, scRNA-seq analysis revealed significant alterations in transcriptomes of T cells that acquired tumor cell cytoplasm, suggesting potential impact on T cell function. We identified that the participation of T cells in intercellular transfer requires cell-cell contact and is strictly dependent on the activation status of T lymphocytes. Finally, we propose to name the described phenomenon of intercellular transfer for tumor infiltrating T cells the "mosquito effect". [ABSTRACT FROM AUTHOR]

The advent and clinical success of immune checkpoint inhibitors Ipilimumab, Nivolumab and Pembrolizumab has had a seismic impact on our drug discovery focus and rationale. Novel extrinsic targets that enhance immune responses to cancer are actively being pursued, while tumor intrinsic targets that render cancer cells more sensitive to the immune system have joined traditional intrinsic targets (e.g. directly cytotoxic) in the drug discovery pipeline. The phosphatase PTPN2 (TC‐PTP) and its paralog PTPN1 (PTP‐1B) are negative regulators of several cytokine signaling pathways and T cell receptor (TCR) signaling. In a recent publication, Baumgartner et al. demonstrate the pre‐clinical efficacy of a first‐in‐class dual PTPN1/N2 active site inhibitor (ABBV‐CLS‐484/AC484) in cancer models. [ABSTRACT FROM AUTHOR]

We have developed a 31‐color panel to define the steady‐state phenotype of T cells in human peripheral blood (Table 1). The panel presented here was optimized using cryopreserved peripheral blood mononuclear cells (PBMC). The markers included in this panel were chosen in order to characterize the steady‐state phenotype of T cells and includes markers (CD45RA, CD45RO, CCR7, CD95) to distinguish the main subsets (e.g., naïve, TEM, TCM, TEMRA, TSCM etc.) of CD4, CD8, and γδ T cells. This panel also includes markers for the identification of differentiation status (CD27, CD28), activation/antigen experience status (CD11a, CD49d, CD38, HLA‐DR, CD56, and CD39), co‐inhibitory marker expression (PD‐1, TIM‐3), and CD4 T helper subsets (CXCR3, CXCR5, CCR4, CCR6, Foxp3, CD25, and CD127). This optimized panel provides a broad assessment of the steady‐state phenotype of human T cells. [ABSTRACT FROM AUTHOR]

Introduction: The avidity of the T-cell receptor (TCR) for antigenic peptides presented by the MHC (pMHC) on cells is an essential parameter for efficient T cell-mediated immunity. Yet, whether the TCR-ligand avidity can drive the clonal evolution of virus antigen-specific CD8 T cells, and how this process is determined in latent Cytomegalovirus (CMV)- against Epstein-Barr virus (EBV)-mediated infection remains largely unknown. Methods: To address these issues, we quantified monomeric TCR-pMHC dissociation rates on CMV- and EBV-specific individual TCRαβ clonotypes and polyclonal CD8 T cell populations in healthy donors over a follow-up time of 15-18 years. The parameters involved during the long-term persistence of virusspecific T cell clonotypes were further evaluated by gene expression profiling, phenotype and functional analyses. Results: Within CMV/pp65-specific T cell repertoires, a progressive contraction of clonotypes with high TCR-pMHC avidity and low CD8 binding dependency was observed, leading to an overall avidity decline during long-term antigen exposure. We identified a unique transcriptional signature preferentially expressed by high-avidity CMV/pp65-specific T cell clonotypes, including the inhibitory receptor LILRB1. Interestingly, T cell clonotypes of high-avidity showed higher LILRB1 expression than the low-avidity ones and LILRB1 blockade moderately increased T cell proliferation. Similar findings were made for CD8 T cell repertoires specific for the CMV/IE-1 epitope. There was a gradual in vivo loss of high-avidity T cells with time for both CMV specificities, corresponding to virus-specific CD8 T cells expressing enhanced LILRB1 levels. In sharp contrast, the EBV/BMFL1-specific T cell clonal composition and distribution, once established, displayed an exceptional stability, unrelated to TCR-pMHC binding avidity or LILRB1 expression. Conclusions: These findings reveal an overall long-term avidity decline of CMVbut not EBV-specific T cell clonal repertoires, highlighting the differing role played by TCR-ligand avidity over the course of these two latent herpesvirus infections. Our data further suggest that the inhibitor receptor LILRB1 potentially restricts the clonal expansion of high-avidity CMV-specific T cell clonotypes during latent infection. We propose that the mechanisms regulating the longterm outcome of CMV- and EBV-specific memory CD8 T cell clonotypes in humans are distinct. [ABSTRACT FROM AUTHOR]

Background: Unlike conventional T cells, innate and virtual-memory CD8 T cells in naïve mice acquire their memory phenotypes and functions in the absence of antigenic encounters in a cytokine-dependent manner. The relevant cytokines include interleukin-4 (IL-4), type I interferon, and interleukin-15 (IL-15). Moreover, exogenous IL-4 can also induce de novo generation and/or expansion of the virtual-memory CD8 T cell population. In this study, we investigated whether exogenous IL-4 could enhance the immune response to a viral infection. Results: In vivo administration of IL-4 and an anti-IL-4 antibody complex (IL-4C) increased CXCR3 expression in both memory and naïve phenotype CD8 T cells in the absence of antigenic stimulation, and protected mice from lethal influenza infection. Flow cytometric analysis of lung-infiltrating immune cells on day 5 after virus infection revealed higher numbers of antigen-specific and bystander CD8 T cells in IL-4C-treated mice than in control mice. In particular, the bystander CD8 T cells were a naïve or evident memory phenotypes. Crucially, an anti-CXCR3 blocking antibody abrogated this IL-4C effect, reflecting that the increased accumulation of CD8 T cells in the lungs after IL-4C treatment is dependent on CXCR3. Conclusions: These data demonstrate that exogenous IL-4C plays a protective role by enhancing CXCR3-dependent migration of CD8 T cells into influenza-infected lungs. [ABSTRACT FROM AUTHOR]

IntroductionChronic Pelvic Pain Syndrome or Chronic Prostatitis (CPPS/CP) is the most prevalent urologic affliction among young adult men. It is a challenging condition to treat, which significantly decreases patient quality of life, mostly because of its still uncertain aetiology. In that regard, an autoimmune origin is a prominent supported theory. Indeed, studies in patients and in rodent models of Experimental Autoimmune Prostatitis (EAP) have provided compelling evidence suggesting a key role of CD4 Th1 cells in disease pathogenesis. However, the implication of other prominent effectors of the immune system, such as CD8 T cells, has yet to be studied.MethodsWe herein analyzed the induction of prostatitis and the development of chronic pelvic pain in EAP using CD8 T cell-deficient animals.ResultsWe found similarly elevated PA-specific immune responses, with high frequencies of specific IFNg+CD4+ and IL17+CD4+ T cells in prostate draining lymph nodes from PA-immunized either CD8 KO or wild type animals with respect to controls. Moreover, these peripheral immune responses were paralleled by the development of significant chronic pelvic pain, and accompanied by prostate histological lesions, characterized by hemorrhage, epithelial cell desquamation, marked periglandular leukocyte infiltration, and increased collagen deposition in both, PA-immunized CD8 KO and wild type animals. As expected, control animals did not develop prostate histological lesions.DiscussionOur results indicate that CD8 T cells do not play a major role in EAP pathogenesis and chronic pelvic pain development. Moreover, our results corroborate the previous notion that a CD4 Th1 associated immune response drives the induction of prostate tissue inflammation and the development of chronic pelvic pain.

IntroductionInnate immune training is a metabolic, functional, and epigenetic long-term reprogramming of innate cells triggered by different stimuli. This imprinting also reaches hematopoietic precursors in the bone marrow to sustain a memory-like phenotype. Dendritic cells (DCs) can exhibit memory-like responses, enhanced upon subsequent exposure to a pathogen; however, whether this imprinting is lineage and stimulus-restricted is still being determined. Nevertheless, the functional consequences of DCs training on the adaptive and protective immune response against non-infectious diseases remain unresolved.MethodsWe evaluated the effect of the nontoxic cholera B subunit (CTB), LPS and LTA in the induction of trained immunity in murine DCs revealed by TNFa and LDH expression, through confocal microscopy. Additionally, we obtained bone marrow DCs (BMDCs) from mice treated with CTB, LPS, and LTA and evaluated training features in DCs and their antigen-presenting cell capability using multiparametric cytometry. Finally, we design an experimental melanoma mouse model to demonstrate protection induced by CTB-trained DCs in vivo.ResultsCTB-trained DCs exhibit increased expression of TNFa, and metabolic reprogramming indicated by LDH expression. Moreover, CTB training has an imprint on DC precursors, increasing the number and antigen-presenting function in BMDCs. We found that training by CTB stimulates the recruitment of DC precursors and DCs infiltration at the skin and lymph nodes. Interestingly, training-induced by CTB promotes a highly co-stimulatory phenotype in tumor-infiltrating DCs (CD86+) and a heightened functionality of exhausted CD8 T cells (Ki67+, GZMB+), which were associated with a protective response against melanoma challenge in vivo.ConclusionOur work indicates that CTB can induce innate immune training on DCs, which turns into an efficient adaptive immune response in the melanoma model and might be a potential immunotherapeutic approach for tumor growth control.

As severe acute respiratory coronavirus 2 (SARS-CoV-2) variants continue to emerge, it is important to characterize immune responses against variants which can inform on protection efficacies following booster vaccination. In this study, neutralizing breadth and antigen-specific CD8+ T cell responses were analyzed in both infection-naïve and infection-experienced individuals following administration of a booster bivalent Wuhan-Hu-1+BA.4/5 Comirnaty® mRNA vaccine. Significantly higher neutralizing titers were found after this vaccination compared to the pre-third booster vaccination time point. Further, neutralizing breadth to omicron variants, including BA.1, BA.2, BA.5, BQ.1 and XBB.1, was found to be boosted following bivalent vaccination. SARS-CoV-2-specific CD8+ T cells were identified, but with no evidence that frequencies were increased following booster vaccinations. Spike protein-specific CD8+ T cells were the only responses detected after vaccination and non-spike-specific CD8+ T cells were only detected after infection. Both spike-specific and non-spike-specific CD8+ T cells were found at much lower frequencies than CD8+ T cells specific to cytomegalovirus (CMV), Epstein-Barr virus (EBV) and influenza (Flu). Taken together, these results show that the bivalent Wuhan-Hu-1+BA.4/5 Comirnaty® mRNA vaccine boosted the breadth of neutralization to newer SARS-CoV-2 variants and that vaccination is able to induce spike protein-specific CD8+ T cell responses, which are maintained longitudinally.

CD8 T cells mediate protection against intracellular pathogens and tumors. However, persistent antigen during chronic infections or cancer leads to T cell exhaustion, suboptimal functionality, and reduced protective capacity. Despite considerable work interrogating the transcriptional regulation of exhausted CD8 T cells (TEX), the posttranscriptional control of TEX remains poorly understood. Here, we interrogated the role of microRNAs (miRs) in CD8 T cells responding to acutely resolved or chronic viral infection and identified miR-29a as a key regulator of TEX. Enforced expression of miR-29a improved CD8 T cell responses during chronic viral infection and antagonized exhaustion. miR-29a inhibited exhaustion-driving transcriptional pathways, including inflammatory and T cell receptor signaling, and regulated ribosomal biogenesis. As a result, miR-29a fostered a memory-like CD8 T cell differentiation state during chronic infection. Thus, we identify miR-29a as a key regulator of TEX and define mechanisms by which miR-29a can divert exhaustion toward a more beneficial memory-like CD8 T cell differentiation state.

BackgroundDysregulated immune response in trauma and sepsis leads to the abnormal activation of the complement and coagulation systems. Mannose-binding lectin (MBL)-associated serine protease-1 (MASP-1) activates the lectin pathway of the complement system and mediates proinflammatory and procoagulant reactions. However, the potential effects of MASP-1 in trauma and sepsis have not yet been explored.MethodsWe obtained five sepsis, two trauma, and one sepsis and trauma RNA-sequencing dataset from the Gene Expression Omnibus (GEO) database and conducted a comprehensive evaluation of the expression pattern, biological functions, and diagnostic value of MASP-1 in trauma and sepsis. Additionally, we investigated the association between MASP-1 expression and clinicopathological characteristics of trauma and sepsis. Furthermore, we collected clinical specimens to preliminarily validate the expression level and diagnostic efficacy of MASP-1 as well as the correlation of MASP-1 with clinical features of trauma and sepsis. Subsequently, we conducted a correlation analysis among MASP-1, immune cell infiltration, and immune and molecular pathways. Finally, we mechanistically analyzed the relationship among MASP-1, specific immune cells, and pivotal molecular pathways.ResultsMASP-1 expression was significantly upregulated in the trauma/sepsis samples compared to the control samples in the GEO datasets. MASP-1 exhibited excellent diagnostic values (AUC > 0.7) in multiple datasets and at multiple time points and could efficiently distinguish trauma/sepsis samples from the control samples. Moreover, MASP-1 expression was significantly positively correlated with the severity of the disease (APACHE-II, CRP, and neutrophil levels). These results were further validated by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Functional enrichment analysis revealed that MASP-1 primarily promotes trauma and sepsis via the immune-related signaling pathway. MASP-1 was significantly correlated with the infiltration of specific immune cells (such as B cells, CD8 T cells, neutrophils, macrophages, and infiltrating lymphocytes) and immune and molecular pathways (such as checkpoint, HLA, IL6/JAK/STAT3 signaling, necrosis, T-cell co-inhibition, and T-cell co-stimulation). Finally, analysis of the transcription and single-cell data revealed that MASP-1 was specifically expressed in T cells, and further correlation analysis revealed a close correlation between MASP-1 expression, proportion of CD8 T cells, and IL6/JAK/STAT3 signaling scores.ConclusionOur results suggest that MASP-1 can serve as an immune-related biomarker for the diagnosis and disease severity of trauma and sepsis. It may activate the IL6 JAK-STAT3 signaling pathway and promote CD8 T-cell depletion to trigger traumatic sepsis.

The phenomenon of intercellular transfer of cellular material, including membranes, cytoplasm, and even organelles, has been observed for decades. The functional impact and molecular mechanisms of such transfer in the immune system remain largely elusive due to the absence of a robust in vivo model. Here, we introduce a new tumor mouse model, where tumor cells express the soluble ultra-bright fluorescent protein ZsGreen, which allows detection and measurement of intercellular transfer of cytoplasm from tumor cells to infiltrating immune cells. We found that in addition to various types of myeloid lineage cells, a large fraction of T regulatory cells and effector CD8 T cells acquire tumor material. Based on the distribution of tumor-derived ZsGreen, the majority of T cells integrate captured cytoplasm into their own, while most myeloid cells store tumor material in granules. Furthermore, scRNA-seq analysis revealed significant alterations in transcriptomes of T cells that acquired tumor cell cytoplasm, suggesting potential impact on T cell function. We identified that the participation of T cells in intercellular transfer requires cell-cell contact and is strictly dependent on the activation status of T lymphocytes. Finally, we propose to name the described phenomenon of intercellular transfer for tumor infiltrating T cells the “mosquito effect”.

ABSTRACTRadiation therapy (RT) combined with CTLA4 blockers converts immunosuppressed (cold) mouse triple negative breast cancers (TNBCs) into immune infiltrated (hot) lesions. We have recently shown that targeting the myeloid compartment to improve dendritic cell activation is required for most TNBC-bearing mice to achieve superior therapeutic responses to RT plus CTLA4 inhibitors.

ABSTRACTThe expression of viral antigens in chronic hepatitis B virus (HBV) infection drives continuous liver inflammation, one of the main risk factors to develop liver cancer. HBV developed immune-suppressive functions to escape from the host immune system, but their link to liver tumor development is not well understood. Here, we analyzed if and how HBV surface antigen (HBs) expression in combined hepatocellular-cholangiocarcinoma (cHCC/iCCA) cells influences their antigenicity for CD8 T cells. We randomly isolated liver tumor tissues from AlfpCre+-Trp53fl/fl/Alb-HBs+ tg mice and established primary carcinoma cell lines (pCCL) that showed a bilineal (CK7+/HNF4α+) cHCC/iCCA phenotype. These pCCL uniformly expressed HBs (HBshi), and low levels of MHC-I (MHC-Ilo), and were transiently convertible to a high antigenicity (MHC-Ihi) phenotype by IFN-γ treatment. HBshi/pCCL induced HBs/(Kb/S190–197)-specific CD8 T cells and developed slow-growing tumors in subcutaneously transplanted C57Bl/6J (B6) mice. Interestingly, pCCL-ex cells, established from HBshi/pCCL-induced and re-explanted tumors in B6 but not those in immune-deficient Rag1−/− mice showed major alterations, like an MHC-Ihi phenotype, a prominent growth-biased gene expression signature, a significantly decreased HBs expression (HBslo) and a switch to fast-growing tumors in re-transplanted B6 or PD-1−/− hosts with an unlocked PD-1/PD-L1 control system. CD8 T cell-mediated elimination of HBshi/pCCL, together with the attenuation of the negative restraints of HBs in the tumor cells, like ER-stress, reveals a novel mechanism to unleash highly aggressive HBslo/pCCL-ex immune-escape variants. Under certain conditions, HBs-specific CD8 T-cell responses thus potentiate tumor growth, an aspect that should be considered for therapeutic vaccination strategies against chronic HBV infection and liver tumors.

• T cells in the chronically infected brain express metabotropic glutamate receptors. • Using flow cytometry and scRNAseq analysis, mGluR expressing T cells are a defined subset of CD8+ T cells with a memory phenotype. • Production of IFN-g depends on mGluR stimulation. Within the brain, a pro-inflammatory response is essential to prevent clinical disease due to Toxoplasma gondii reactivation. Infection in the immunocompromised leads to lethal Toxoplasmic encephalitis while in the immunocompetent, there is persistent low-grade inflammation which is devoid of clinical symptoms. This signifies that there is a well-balanced and regulated inflammatory response to T. gondii in the brain. T cells are the dominant immune cells that prevent clinical disease, and this is mediated through the secretion of effector molecules such as perforins and IFN-γ. The presence of cognate antigen, the expression of survival cytokines, and the alteration of the epigenetic landscape drive the development of memory T cells. However, specific extrinsic signals that promote the formation and maintenance of memory T cells within tissue are poorly understood. During chronic infection, there is an increase in extracellular glutamate that, due to its function as an excitatory neurotransmitter, is normally tightly controlled in the CNS. Here we demonstrate that CD8+ T cells from the T. gondii -infected brain parenchyma are enriched for metabotropic glutamate receptors (mGluR's). Characterization studies determined that mGluR+ expression by CD8+ T cells defines a distinct memory population at the transcriptional and protein level. Finally, using receptor antagonists and agonists we demonstrate mGluR signaling is required for optimal CD8+ T cell production of the effector cytokine IFNγ. This work suggests that glutamate is an important environmental signal of inflammation that promotes T cell function. Understanding glutamate's influence on T cells in the brain can provide insights into the mechanisms that govern protective immunity against CNS-infiltrating pathogens and neuroinflammation. [ABSTRACT FROM AUTHOR]

Simple Summary: Immunotherapy is an innovative treatment that is highly effective against certain cancers, such as skin and lung cancer. However, for colorectal cancer, one of the most prevalent cancers, it does not benefit most patients. Recent research suggests that by treating liver metastases first, immunotherapy might become effective for those with colorectal cancer. This review delves into the current evidence supporting this strategy, aiming to understand its underlying mechanisms and determine the best way to implement it. If this approach gains widespread acceptance, it could revolutionize how we treat colorectal cancer patients. Immunotherapy has revolutionized the treatment of several cancers, including melanoma and lung cancer. However, for colorectal cancer, it is ineffective for 95% of patients with microsatellite-stable disease. Recent evidence suggests that the liver's immune microenvironment plays a pivotal role in limiting the effectiveness of immunotherapy. There is also evidence to show that targeting liver metastases with locoregional therapies, such as surgery or irradiation, could potentiate immunotherapy for these patients. This review presents evidence from preclinical studies regarding the underlying mechanisms and from clinical studies that support this approach. Furthermore, we outline potential directions for future clinical trials. This innovative strategy could potentially establish immunotherapy as an effective treatment for MS-stable colorectal cancer patients, which are currently considered resistant. [ABSTRACT FROM AUTHOR]

IL-1R integrates signals from IL-1α and IL-1β, and it is widely expressed across tissues and immune cell types. While the expression pattern and function of IL-1R within the innate immune system is well studied, its role in adaptive immunity, particularly within the CD8 T cell compartment, remains underexplored. Here, we show that CD8 T cells dynamically upregulate IL-1R1 levels during priming by APCs, which correlates with their proliferation status and the acquisition of an effector phenotype. Notably, this IL-1 sensitivity persists in memory CD8 T cells of both mice and humans, influencing effector cytokine production upon TCR reactivation. Furthermore, our study highlights that antiviral effector and tissue-resident CD8 T cell responses against influenza A virus infection become impaired in the absence of IL-1 signaling. Altogether, these data support the exploitation of IL-1 activity in the context of T cell vaccination strategies and warrant consideration of the impact of clinical IL-1 inhibition on the rollout of T cell immunity. [ABSTRACT FROM AUTHOR]

CD8 T cells are important tools for protection against intracellularly replicating pathogens such as viruses. Previous studies showed that a discrete population of HLADR and CD38-expressing CD8 T cells expands massively during the acute febrile phase of human dengue virus infection--but very few of these cells secrete IFNγ upon in vitro stimulation with dengue peptides. To gain a better understanding of what other cytokines/chemokines do these massively expanding HLADR+CD38+ CD8 T cells express, we performed RNA seq of sorted HLADR+CD38+ CD8 T cell subsets after peptide stimulation. A majority of these peptide-stimulated HLADR+CD38+ CD8 T cells were CD69- IFNγ-, nearly a third were CD69+ IFNγ-, whereas very few (<10%) were CD69+ IFNγ+. The CD69- IFNγ- subset was enriched for the expression of key genes implicated in the negative regulation of T cell receptor (TCR) signaling and T-cell exhaustion, attraction of B cells and other lymphocytes, and cytokines related to Tc17/T-reg lineages or those that are implicated in immunosuppression/immunomodulatory and anti-inflammatory activities and angiogenesis. The CD69+ IFNγ- subset showed enriched transcription of key genes implicated in cytotoxic effector functions as well as costimulatory and signaling adaptors implicated in fine balancing of T cell receptor signaling. The CD69+ IFNγ+ subset largely shared the transcriptional profile with the CD69+ IFNγsubset--but with relatively more pronounced expression along with additional genes such as chemokines XCL1/XCL2. Our findings showing distinct functional subsets among these massively expanding CD8 T cells in dengue CD8 T cells warrant further studies to carefully examine the precise role of these T cell subsets in protection against dengue. [ABSTRACT FROM AUTHOR]

Introduction: Immunotherapies have shown great promise, but are not effective for all tumors types and are effective in less than 3% of patients with pancreatic ductal adenocarcinomas (PDAC). To make an immune treatment that is effective for more cancer patients and those with PDAC specifically, we genetically engineered Salmonella to deliver exogenous antigens directly into the cytoplasm of tumor cells. We hypothesized that intracellular delivery of an exogenous immunization antigen would activate antigen-specific CD8 T cells and reduce tumors in immunized mice. Methods: To test this hypothesis, we administered intracellular delivering (ID) Salmonella that deliver ovalbumin as a model antigen into tumor-bearing, ovalbumin-vaccinated mice. ID Salmonella delivers antigens by autonomously lysing in cells after the induction of cell invasion. Results: We showed that the delivered ovalbumin disperses throughout the cytoplasm of cells in culture and in tumors. This delivery into the cytoplasm is essential for antigen cross-presentation. We showed that co-culture of ovalbumin-recipient cancer cells with ovalbumin-specific CD8 T cells triggered a cytotoxic T cell response. After the adoptive transfer of OT-I CD8 T cells, intracellular delivery of ovalbumin reduced tumor growth and eliminated tumors. This effect was dependent on the presence of the ovalbumin-specific Tcells. Following vaccination with the exogenous antigen in mice, intracellular delivery of the antigen cleared 43% of established KPC pancreatic tumors, increased survival, and prevented tumor re-implantation. Discussion: This response in the immunosuppressive KPC model demonstrates the potential to treat tumors that do not respond to checkpoint inhibitors, and the response to re-challenge indicates that new immunity was established against intrinsic tumor antigens. In the clinic, ID Salmonella could be used to deliver a protein antigen from a childhood immunization to refocus pre-existing T cell immunity against tumors. As an off-the-shelf immunotherapy, this bacterial system has the potential to be effective in a broad range of cancer patients. [ABSTRACT FROM AUTHOR]

Coronary artery disease (CAD) is a major cause of death worldwide. The role of CD8+ T cells in CAD is unknown. Recent studies suggest a breakdown of tolerance in atherosclerosis, resulting in active T cell receptor (TCR) engagement with self-antigens. We hypothesized that TCR engagement would leave characteristic gene expression signatures. In a single cell RNA-sequencing analysis of CD8+ T cells from 30 patients with CAD and 30 controls we found significant enrichment of TCR signaling pathways in CAD+ subjects, suggesting recent TCR engagement. We also found significant enrichment of cytotoxic and exhaustion pathways in CAD cases compared to controls. Highly significant upregulation of TCR signaling in CAD indicates that CD8 T cells reactive to atherosclerosis antigens are prominent in the blood of CAD cases compared to controls. [ABSTRACT FROM AUTHOR]

CD8+ T cells are end effectors of cancer immunity. Most forms of effective cancer immunotherapy involve CD8+ T cell effector function. Here, we review the current understanding of T cell function in cancer, focusing on key CD8+ T cell subtypes and states. We discuss factors that influence CD8+ T cell differentiation and function in cancer through a framework that incorporates the classic three-signal model and a fourth signal—metabolism—and also consider the impact of the tumor microenvironment from a T cell perspective. We argue for the notion of immunotherapies as "pro-drugs" that act to augment or modulate T cells, which ultimately serve as the drug in vivo , and for the importance of overall immune health in cancer treatment and prevention. The progress in understanding T cell function in cancer has and will continue to improve harnessing of the immune system across broader tumor types to benefit more patients. CD8+ T cells are "end effectors" of cancer immunity. Wherry, Kaech, and colleagues review the current understanding of CD8+ T cell differentiation and function in cancer, discussing recent advances within a four-signal framework that incorporates T cell metabolism and the impact of the tumor microenvironment. [ABSTRACT FROM AUTHOR]