Biology subjects

Bosnjak, B.

Publications and source records attributed to Bosnjak, B..

4 recordsLinked to original sources

bioRxiv2024

Different CMV-specific effector T cell subtypes are associated with age, CMV serostatus, and increased systolic blood pressure

Cytomegalovirus (CMV) infection is one of the most common infections in humans, and CMV antigens are the major drivers of repetitive T-cell stimulation as a part of a well-adapted immune response in immunocompetent individuals. With higher age, the recurrent clonal expansion of CMV-specific T cells results in high frequencies of CMV-specific effector T cells. CMV seropositivity has also been linked to arterial stiffness and an increased risk of developing cardiovascular diseases (CVD). The RESIST Senior Individuals (SI) cohort is a population-based cohort with focus on the elderly, established to shed light on the age-related changes of the immune system and the accompanied reduced capability to fight infectious diseases. Here we investigated the frequency and phenotype of CMVpp65-specific CD8+ T cells in the circulation of individuals of different age groups by means of MHC-I tetramer staining and their associations with age and associated factors such as serostatus and blood pressure. In the SI cohort, the frequency of CMV-specific T cells within the CD8+ T cell fraction was increased with age, as previously reported. We add to previous knowledge by showing that this frequency is associated with the total percentage and absolute counts of CD8+ and CD4+CD8+ double-positive T cells within leukocytes. Systolic blood pressure (SBP) and history of CVD correlated with the frequency of CMV-specific CD8+ T cells. Focusing on CMV-specific T cell subtypes, we show here that the frequencies of TEM and CD27-expressing TEMRA cells were associated with higher age. TEM and CD27- TEMRA cell frequencies were increased in donors with high CMV-IgG titers. Furthermore, SBP significantly correlated with CMV-specific effector CD8+ T cells, which was mostly reflected by CD27- TEMRA cells. In conclusion, different effector T-cell subtypes were associated with age, serostatus and SBP, suggesting that it is not age per se that renders elderly CMV-positive individuals susceptible to CVD, but the immune response to CMV. Our study suggests that detailed immunophenotyping may identify individuals whose immune systems are strongly influenced by the response to CMV, leading to health consequences and impairing healthy aging.

immunology↗

bioRxiv2024

Protective function of ex vivo expanded CD8 T cells in a mouse model of adoptive therapy for cytomegalovirus infection depends on integrin beta 1 but not CXCR3, CTLA4, or PD-1 expression

The adoptive transfer of virus-specific T cells (VSTs) represents a therapeutic option for viral infection treatment in immunocompromised patients. Before administration, ex vivo culture enables VST expansion. However, it is unclear how ex vivo expansion affects the circulation, homing, and intra-tissue migration of administered VSTs. We established a model of VST immunotherapy of acute cytomegalovirus infection using adoptive transfer of ex vivo expanded OT-I CD8 T cells (recognizing SIINFEKL peptide) into Rag2-/- mice infected with murine cytomegalovirus (MCMV) encoding for the SIINFEKL peptide. Ex vivo expansion induced an effector T cell phenotype and affected the expression of integrins and chemokine receptors. CRISPR/Cas9-mediated gene deletions enabled us to address the role of selected genes in the homing of VSTs following intravenous administration. We found that deletion of Itgb1, encoding for integrin beta 1, prevented OT-I cells from entering infected organs and drastically reduced their number in blood, suggesting that adoptively transferred VSTs primarily expand in the infected tissues. In contrast, Cxcr3-/- OT-I cells provided equal protection as their Cxcr3+/+ counterparts, indicating that this chemokine receptor does not contribute to VST entry into infected organs. Further, Pdcd1 and Ctla4 deletion did not impair the transferred OT-I cells ability to protect mice from MCMV, arguing against quick exhaustion of VSTs with an effector T cell phenotype. Together, these data indicate that ex vivo expansion affects migration and activation properties of VSTs and suggest that future clinical evaluation of adoptive T cell therapy efficacy should include homing molecule expression assessment.

immunology↗

bioRxiv2022

MHC class Ia molecules facilitate MCK2-dependent MCMV infection of macrophages and virus dissemination to the salivary gland

Murine cytomegalovirus (MCMV) infection of macrophages relies on MCMV-encoded chemokine 2 (MCK2) through one or more unknown cellular receptors while infection of fibroblast occurs independent of MCK2 and is mediated by cell-expressed neuropilin 1. Applying a CRISPR screen, we now identified that the MHC-Ia/Beta-2-microglobulin (B2m) complex serves as an entry port for MCK2-mediated infection of macrophages. Further analyses revealed that MCK2-dependent infection requires expression of the MHC-Ia haplotypes H-2b and H-2d but not H-2k. The importance of the MCK2-MHC-I-pathway for primary infection and viral dissemination was highlighted by experiments with B2m-deficient mice, which lack surface expression of MHC-I molecules. In those mice, intranasally administered MCK2-proficient MCMV could not infect alveolar macrophages and subsequently failed to disseminate into the salivary glands. The identified molecular pathway used by MCMV to infect lung resident macrophages provides essential knowledge for understanding cytomegalovirus-induced pathogenesis, tissue targeting, and virus dissemination.

immunology↗

bioRxiv2021

Immunogenicity and efficacy of the COVID-19 candidate vector vaccine MVA SARS 2 S in preclinical vaccination

The severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) has emerged as the infectious agent causing the pandemic coronavirus disease 2019 (COVID-19) with dramatic consequences for global human health and economics. Previously, we reached clinical evaluation with our vector vaccine based on vaccinia virus MVA against the Middle East respiratory syndrome coronavirus (MERS-CoV), which causes an infection in humans similar to SARS and COVID-19. Here, we describe the construction and preclinical characterization of a recombinant MVA expressing full-length SARS-CoV-2 spike (S) protein (MVA-SARS-2-S). Genetic stability and growth characteristics of MVA-SARS-2-S, plus its robust synthesis of S antigen, make it a suitable candidate vaccine for industrial scale production. Vaccinated mice produced S antigen-specific CD8+ T cells and serum antibodies binding to S glycoprotein that neutralized SARS-CoV-2. Prime-boost vaccination with MVA-SARS-2-S protected mice sensitized with a human ACE2-expressing adenovirus from SARS-CoV-2 infection. MVA-SARS-2-S is currently being investigated in a phase I clinical trial as aspirant for developing a safe and efficacious vaccine against COVID-19. Significance StatementThe highly attenuated vaccinia virus MVA is licensed as smallpox vaccine, and as vector it is a component of the approved Adenovirus-MVA-based prime-boost vaccine against Ebola virus disease. Here we provide results from testing the COVID-19 candidate vaccine MVA-SARS-2-S, a poxvirus-based vector vaccine that proceeded to clinical evaluation. When administered by intramuscular inoculation, MVA-SARS-2-S expresses and safely delivers the full-length SARS-CoV-2 spike (S) protein, inducing balanced SARS-CoV-2-specific cellular and humoral immunity, and protective efficacy in vaccinated mice. Substantial clinical experience has already been gained with MVA vectors using homologous and heterologous prime-boost applications, including the immunization of children and immunocompromised individuals. Thus, MVA-SARS-2-S represents an important resource for developing further optimized COVID-19 vaccines.

microbiology↗