Intranasal delivery of an adenovirus-vector vaccine co-expressing a modified spike protein and a genetic adjuvant confers lasting mucosal immunity against SARS-CoV-2.

The ongoing COVID-19 pandemic caused by SARS-CoV-2 infection has threatened global health. Since the first case of infection was reported in December 2019, SARS-CoV-2 has rapidly spread worldwide and caused millions of deaths. As vaccination is the best way to protect the host from invading pathogens, several vaccines have been developed to prevent the infection of SARS-CoV-2, saving numerous lives thus far. However, SARS-CoV-2 constantly changes its antigens, resulting in escape from vaccine-induced protection, and the longevity of immunity induced by vaccines remains an issue. Additionally, traditional intramuscular COVID-19 vaccines are insufficient at evoking mucosal-specific immune responses. Because the respiratory tract is the primary route of SARS-CoV-2 entry, the need for mucosal vaccines is strong. Using an adenoviral (Ad) vector platform, we generated Ad5-S.Mod, a recombinant COVID-19 vaccine that encodes modified-spike (S) antigen and the genetic adjuvant human CXCL9. Intranasal delivery of Ad5-S.Mod elicited superior airway humoral and T-cell responses over traditional intramuscular vaccines and protected mice from lethal SARS-CoV-2 infection. cDC1 cells were required for the generation of antigen-specific CD8+ T-cell responses and CD8+ tissue-resident memory T-cell development in intranasal Ad5-S.Mod vaccinated mice. Furthermore, we confirmed the efficacy of the intranasal Ad5-S.Mod vaccine in terms of transcriptional changes and identified lung macrophages as a key supporter of maintenance of lung-resident memory T and B cells. Our study demonstrates Ad5-S.Mod has the potential to confer protective immunity against SARS-CoV-2 and that lung macrophages support the maintenance of vaccine-induced tissue-resident memory lymphocytes.

Regulation of c-SMAC formation and AKT-mTOR signaling by the TSG101-IFT20 axis in CD4+ T cells.

CD4+ T cells play major roles in the adaptive immune system, which requires antigen recognition, costimulation, and cytokines for its elaborate orchestration. Recent studies have provided new insight into the importance of the supramolecular activation cluster (SMAC), which comprises concentric circles and is involved in the amplification of CD4+ T cell activation. However, the underlying mechanism of SMAC formation remains poorly understood. Here, we performed single-cell RNA sequencing of CD4+ T cells left unstimulated and stimulated with anti-CD3 and anti-CD28 antibodies to identify novel proteins involved in their regulation. We found that intraflagellar transport 20 (IFT20), previously known as cilia-forming protein, was upregulated in antibody-stimulated CD4+ T cells compared to unstimulated CD4+ T cells. We also found that IFT20 interacted with tumor susceptibility gene 101 (TSG101), a protein that endocytoses ubiquitinated T-cell receptors. The interaction between IFT20 and TSG101 promoted SMAC formation, which led to amplification of AKT-mTOR signaling. However, IFT20-deficient CD4+ T cells showed SMAC malformation, resulting in reduced CD4+ T cell proliferation, aerobic glycolysis, and cellular respiration. Finally, mice with T-cell-specific IFT20 deficiency exhibited reduced allergen-induced airway inflammation. Thus, our data suggest that the IFT20-TSG101 axis regulates AKT-mTOR signaling via SMAC formation.

Autophagic protein ATG5 controls antiviral immunity via glycolytic reprogramming of dendritic cells against respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) is a leading cause of respiratory tract infections in infants. Macroautophagy/autophagy is a catalytic metabolic process required for cellular homeostasis. Although intracellular metabolism is important for immune responses in dendritic cells, the link between autophagy and immunometabolism remains unknown. Here, we show that the autophagy-related protein ATG5 regulates immunometabolism. Atg5-deficient mouse dendritic cells showed increased CD8A+ T-cell response and increased secretion of proinflammatory cytokines upon RSV infection. Transcriptome analysis showed that Atg5 deficiency alters the expression of metabolism-related genes. Atg5-deficient dendritic cells also showed increased activation of glycolysis and the AKT-MTOR-RPS6KB1 pathway and decreased mitochondrial activity, all of which are cellular signatures for metabolic activation. These cells also showed elevated CD8A+ T-cell priming and surface major histocompatibility complex (MHC) class I expression. Our results suggested that ATG5 regulated host immune responses by modulating dendritic cell metabolism. These findings may help develop potential antiviral therapies that alter host immunity by regulating autophagy and immunometabolism.Abbreviations : 2-DG: 2-deoxyglucose; AAK1: AP2 associated kinase 1; AKT: AKT serine/threonine kinase; AM: alveolar macrophage; ATG: autophagy; ATP: adenosine triphosphate; BAL: bronchoalveolar lavage; BMDC: bone marrow dendritic cell; CSF2/GM-CSF: colony-stimulating factor 2 (granulocyte-macrophage); CTL: cytotoxic T lymphocyte; ELISA: enzyme-linked immunosorbent assay; GFP: green fluorescent protein; GSEA: gene-set enrichment analysis; H-2Db: H-2 class I histocompatibility antigen, D-B alpha chain; H-2Kb: MHC class I H2-K-b; HIF1A: hypoxia-inducible factor 1 alpha; IFNG: interferon-gamma; IL: interleukin; ITGAX: integrin alpha X; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MHC: major histocompatibility complex; MTORC1: mammalian target of rapamycin kinase complex 1; PBS: phosphate-buffered saline; PFU: plaque-forming unit; RLR: retinoic acid-inducible-I-like receptor; ROS: reactive oxygen species; RPMI: Roswell Park Memorial Institute; RPS6KB1/S6K: ribosomal protein S6 kinase, polypeptide 1; RSV: respiratory syncytial virus; Th: T helper; TLR: toll-like receptor; Treg: regulatory T cells; UMAP: uniform manifold approximation and projection.

The autophagy Protein Atg5 Plays a Crucial Role in the Maintenance and Reconstitution Ability of Hematopoietic Stem Cells.

Hematopoietic stem cells (HSCs) in bone marrow are pluripotent cells that can constitute the hematopoiesis system through self-renewal and differentiation into immune cells and red blood cells. To ensure a competent hematopoietic system for life, the maintenance of HSCs is tightly regulated. Although autophagy, a self-degradation pathway for cell homeostasis, is essential for hematopoiesis, the role of autophagy key protein Atg5 in HSCs has not been thoroughly investigated. In this study, we found that Atg5 deficiency in hematopoietic cells causes survival defects, resulting in severe lymphopenia and anemia in mice. In addition, the absolute numbers of HSCs and multiple-lineage progenitor cells were significantly decreased, and abnormal erythroid development resulted in reduced erythrocytes in blood of Vav_Atg5-/- mice. The proliferation of Lin-Sca-1+c-Kit+ HSCs was aberrant in bone marrow of Vav_Atg5-/- mice, and mature progenitors and terminally differentiated cells were also significantly altered. Furthermore, the reconstitution ability of HSCs in bone marrow chimeric mice was significantly decreased in the presence of Atg5 deficiency in HSCs. Mechanistically, impairment of autophagy-mediated clearance of damaged mitochondria was the underlying cause of the HSC functional defects. Taken together, these results define the crucial role of Atg5 in the maintenance and the reconstitution ability of HSCs.

Single mucosal vaccination targeting nucleoprotein provides broad protection against two lineages of influenza B virus.

Nucleoprotein is highly conserved among each type of influenza viruses (A and B) and has received significant attention as a good target for universal influenza vaccine. In this study, we determined whether a recombinant adenovirus encoding nucleoprotein of type B influenza virus (rAd/B-NP) confers protection against influenza virus infection in mice. We also identified a cytotoxic T lymphocyte epitope in the nucleoprotein to determine B-NP-specific CD8 T-cell responses. We found that B-NP-specific CD8 T cells induced by rAd/B-NP immunization played a major role in protection following influenza B virus infection using CD8 knockout mice. To assess the effects of the administration routes on protective immunity, we immunized mice with rAd/B-NP via intranasal or intramuscular routes. Both groups showed strong NP-specific humoral and CD8 T-cell responses, but only intranasal immunization provided complete protection against both lineages of influenza B virus challenge. Intranasal but not intramuscular administration established resident memory CD8 T cells in the airway and lung parenchyma, which were required for efficient protection. Furthermore, rAd/B-NP in combination with rAd/A-NP protected mice against lethal infection with both influenza A and B viruses. These findings demonstrate that rAd/B-NP could be further developed as a universal vaccine against influenza.

Vibrio vulnificus quorum-sensing molecule cyclo(Phe-Pro) inhibits RIG-I-mediated antiviral innate immunity.

The recognition of pathogen-derived ligands by pattern recognition receptors activates the innate immune response, but the potential interaction of quorum-sensing (QS) signaling molecules with host anti-viral defenses remains largely unknown. Here we show that the Vibrio vulnificus QS molecule cyclo(Phe-Pro) (cFP) inhibits interferon (IFN)-ß production by interfering with retinoic-acid-inducible gene-I (RIG-I) activation. Binding of cFP to the RIG-I 2CARD domain induces a conformational change in RIG-I, preventing the TRIM25-mediated ubiquitination to abrogate IFN production. cFP enhances susceptibility to hepatitis C virus (HCV), as well as Sendai and influenza viruses, each known to be sensed by RIG-I but did not affect the melanoma-differentiation-associated gene 5 (MDA5)-recognition of norovirus. Our results reveal an inter-kingdom network between bacteria, viruses and host that dysregulates host innate responses via a microbial quorum-sensing molecule modulating the response to viral infection.

Intratumoral depletion of regulatory T cells using CD25-targeted photodynamic therapy in a mouse melanoma model induces antitumoral immune responses.

Tumor immunotherapy aims to overcome the immunosuppressive microenvironment within tumors, and various approaches have been developed. Tumor-associated T regulatory cells (Tregs) suppress the activation and expansion of tumor antigen-specific effector T cells, thus, providing a permissive environment for tumor growth. Therefore, optimal strategies need to be established to deplete tumor-infiltrated Tregs because systemic depletion of Tregs can result in reduced anti-tumor effector cells and autoimmunity. Here, to selectively deplete Tregs in tumors, we intratumorally injected anti-CD25 antibodies conjugated to Chlorin e6 (Ce6), a photosensitizer that absorbs light to generate reactive oxygen species. Local depletion of tumor-associated Tregs with photodynamic therapy (PDT) inhibited tumor growth, which was likely due to the altered tumor immune microenvironment that was characterized by increased infiltration of CD8+ effector T cells and the expression of IFN-γ and CD107a, which is a cytolytic granule exocytosis marker in tumor tissues. Furthermore, PDT-induced intratumoral Treg depletion did not influence adaptive immune responses in a murine influenza infection model. Thus, our results show that intratumoral Treg-targeted PDT could specifically modulate tumor microenvironments by depleting Tregs and could be used as a novel cancer immunotherapy technique.