Search

Semaphorin-3A (SEMA3A) functions as a chemorepulsive signal during development and can affect T cells by altering their filamentous actin (F-actin) cytoskeleton. The exact extent of these effects on tumour-specific T cells are not completely understood. Here we demonstrate that Neuropilin-1 (NRP1) and Plexin-A1 and Plexin-A4 are upregulated on stimulated CD8+ T cells, allowing tumour-derived SEMA3A to inhibit T cell migration and assembly of the immunological synapse. Deletion of NRP1 in both CD4+ and CD8+ T cells enhance CD8+ T-cell infiltration into tumours and restricted tumour growth in animal models. Conversely, over-expression of SEMA3A inhibit CD8+ T-cell infiltration. We further show that SEMA3A affects CD8+ T cell F-actin, leading to inhibition of immune synapse formation and motility. Examining a clear cell renal cell carcinoma patient cohort, we find that SEMA3A expression is associated with reduced survival, and that T-cells appear trapped in SEMA3A rich regions. Our study establishes SEMA3A as an inhibitor of effector CD8+ T cell tumour infiltration, suggesting that blocking NRP1 could improve T cell function in tumours. Interactions between Semaphorin-3A (SEMA3A) and Neuropilin-1 (NRP1) and Plexin-A1 and Plexin-A4 have been shown to affect T cell development. Here the authors investigate how these interactions affect CD8+ T cells in tumour immunity, showing that NRP-1, Plexin-A1 and Plexin-A4 are upregulated on T cells allowing tumour derived SEMA3A to inhibit CD8+ T cell migration and function. [ABSTRACT FROM AUTHOR]

Pathogen-specific CD8+ T cell responses restricted by the nonpolymorphic nonclassical class Ib molecule human leukocyte antigen E (HLA-E) are rarely reported in viral infections. The natural HLA-E ligand is a signal peptide derived from classical class Ia HLA molecules that interact with the NKG2/CD94 receptors to regulate natural killer cell functions, but pathogen-derived peptides can also be presented by HLA-E. Here, we describe five peptides from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that elicited HLA-E–restricted CD8+ T cell responses in convalescent patients with coronavirus disease 2019. These T cell responses were identified in the blood at frequencies similar to those reported for classical HLA-Ia–restricted anti–SARS-CoV-2 CD8+ T cells. HLA-E peptide–specific CD8+ T cell clones, which expressed diverse T cell receptors, suppressed SARS-CoV-2 replication in Calu-3 human lung epithelial cells. SARS-CoV-2 infection markedly down-regulated classical HLA class I expression in Calu-3 cells and primary reconstituted human airway epithelial cells, whereas HLA-E expression was not affected, enabling T cell recognition. Thus, HLA-E–restricted T cells could contribute to the control of SARS-CoV-2 infection alongside classical T cells. Editor's summary: CD8+ T cells expressing HLA-E have been reported in viral infection; however, it is unclear whether they contribute to the immune response against SARS-CoV-2. Yang et al. generated five stable HLA-E peptide tetramers to evaluate CD8+ T cell responses to SARS-CoV-2. HLA-E–restricted CD8+ T cells were detected at levels comparable to conventional HLA-Ia–restricted T cells in SARS-CoV-2 convalescent individuals. These HLA-E–specific CD8+ T cell clones recognized SARS-CoV-2–infected cells and suppressed viral replication. SARS-CoV-2 infection caused downregulation of classical HLA-Ia but not HLA-E in cell lines and primary human airway epithelial cells. These findings suggest that SARS-CoV-2–specific HLA-E–restricted CD8+ T cells may be advantageous when classically restricted T cells are disturbed during SARS-CoV-2 infection. —Hannah Isles [ABSTRACT FROM AUTHOR]

Making human T cells see HIV-1: Cytomegalovirus (CMV)–based vaccines protect rhesus macaques from simian immunodeficiency virus infection by inducing atypical CD8+ T cell responses restricted to the rhesus HLA-E homolog. However, it is unclear whether these atypical CD8+ T cell responses might translate to human immunodeficiency virus (HIV) when using a vaccine based on a human CMV vector. Here, Yang et al. showed that HIV-1 Gag-specific, HLA-E–restricted CD8+ T cell clones could be generated in vitro from naïve T cells taken from HIV-1 uninfected people. These CD8+ T cell clones were able to suppress HIV-1–infected CD4+ target cells. These data indicate that HIV-1–specific, HLA-E–restricted CD8+ T cell clones can be generated in humans and that a human CMV vector–based vaccine for HIV may generate protective CD8+ T cell responses. Human leukocyte antigen-E (HLA-E) normally presents an HLA class Ia signal peptide to the NKG2A/C-CD94 regulatory receptors on natural killer (NK) cells and T cell subsets. Rhesus macaques immunized with a cytomegalovirus-vectored simian immunodeficiency virus (SIV) vaccine generated Mamu-E (HLA-E homolog)–restricted T cell responses that mediated post-challenge SIV replication arrest in >50% of animals. However, HIV-1–specific, HLA-E–restricted T cells have not been observed in HIV-1–infected individuals. Here, HLA-E–restricted, HIV-1–specific CD8+ T cells were primed in vitro. These T cell clones and allogeneic CD8+ T cells transduced with their T cell receptors suppressed HIV-1 replication in CD4+ T cells in vitro. Vaccine induction of efficacious HLA-E–restricted HIV-1–specific T cells should therefore be possible. [ABSTRACT FROM AUTHOR]

Despite the fact that the biological function of cluster of differentiation (CD)133 remains unclear, this glycoprotein is currently used in the identification and isolation of tumor-initiating cells from certain malignant tumors, including pancreatic cancer. In the present study, the involvement of mucin 1 (MUC1) in the signaling pathways of a highly tumorigenic CD133+ cellular subpopulation sorted from the pancreatic cancer cell line HPAF-II was evaluated. The expression of MUC1-cytoplasmic domain (MUC1-CD) and oncogenic signaling transducers (epidermal growth factor receptor, protein kinase C delta, glycogen synthase kinase 3 beta and growth factor receptor-bound protein 2), as well as the association between MUC1 and β-catenin, were characterized in HPAF-II CD133+ and CD133low cell subpopulations and in tumor xenografts generated from these cells. Compared with HPAF CD133low cells, HPAF-II CD133+ cancer cells exhibited increased tumorigenic potential in immunocompromised mice, which was associated with overexpression of MUC1 and with the accordingly altered expression profile of MUC1-associated signaling partners. Additionally, MUC1-CD/β-catenin interactions were increased both in the HPAF-II CD133+ cell subpopulation and derived tumor xenografts compared with HPAF CD133low cells. These results suggest that, in comparison with HPAF CD133low cells, CD133+ cells exhibit higher expression of MUC1, which contributes to their tumorigenic phenotype through increased interaction between MUC1-CD and β-catenin, which in turn modulates oncogenic signaling cascades. [ABSTRACT FROM AUTHOR]

Human leukocyte antigen-E (HLA-E) normally presents an HLA class Ia signal peptide to the NKG2A/C-CD94 regulatory receptors on natural killer (NK) cells and T cell subsets. Rhesus macaques immunized with a cytomegalovirus-vectored simian immunodeficiency virus (SIV) vaccine generated Mamu-E (HLA-E homolog)-restricted T cell responses that mediated post-challenge SIV replication arrest in >50% of animals. However, HIV-1-specific, HLA-E-restricted T cells have not been observed in HIV-1-infected individuals. Here, HLA-E-restricted, HIV-1-specific CD8 + T cells were primed in vitro. These T cell clones and allogeneic CD8 + T cells transduced with their T cell receptors suppressed HIV-1 replication in CD4 + T cells in vitro. Vaccine induction of efficacious HLA-E-restricted HIV-1-specific T cells should therefore be possible., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)