10 research outputs found
Replicating viral vector platform exploits alarmin signals for potent CD8+ T cell-mediated tumour immunotherapy
Viral infections lead to alarmin release and elicit potent cytotoxic effector
T lymphocyte (CTLeff) responses. Conversely, the induction of protective
tumour-specific CTLeff and their recruitment into the tumour remain
challenging tasks. Here we show that lymphocytic choriomeningitis virus (LCMV)
can be engineered to serve as a replication competent, stably-attenuated
immunotherapy vector (artLCMV). artLCMV delivers tumour-associated antigens to
dendritic cells for efficient CTL priming. Unlike replication-deficient
vectors, artLCMV targets also lymphoid tissue stroma cells expressing the
alarmin interleukin-33. By triggering interleukin-33 signals, artLCMV elicits
CTLeff responses of higher magnitude and functionality than those induced by
replication-deficient vectors. Superior anti-tumour efficacy of artLCMV
immunotherapy depends on interleukin-33 signalling, and a massive CTLeff
influx triggers an inflammatory conversion of the tumour microenvironment. Our
observations suggest that replicating viral delivery systems can release
alarmins for improved anti-tumour efficacy. These mechanistic insights may
outweigh safety concerns around replicating viral vectors in cancer
immunotherapy
Specific fibroblastic niches in secondary lymphoid organs orchestrate distinct Notch-regulated immune responses.
Fibroblast-like cells of secondary lymphoid organs (SLO) are important for tissue architecture. In addition, they regulate lymphocyte compartmentalization through the secretion of chemokines, and participate in the orchestration of appropriate cell-cell interactions required for adaptive immunity. Here, we provide data demonstrating the functional importance of SLO fibroblasts during Notch-mediated lineage specification and immune response. Genetic ablation of the Notch ligand Delta-like (DL)1 identified splenic fibroblasts rather than hematopoietic or endothelial cells as niche cells, allowing Notch 2-driven differentiation of marginal zone B cells and of Esam(+) dendritic cells. Moreover, conditional inactivation of DL4 in lymph node fibroblasts resulted in impaired follicular helper T cell differentiation and, consequently, in reduced numbers of germinal center B cells and absence of high-affinity antibodies. Our data demonstrate previously unknown roles for DL ligand-expressing fibroblasts in SLO niches as drivers of multiple Notch-mediated immune differentiation processes
Interleukin-33 and vaccine vectors in virus-host balance
The aims of my thesis were threefold.
Firstly, we wanted to decipher the role of IL-33 in adaptive immunity against acute and chronic viral infection.
Secondly, we aimed at investigating the cellular source of IL-33 and the impact thereof on T cell responses to chronic viral infection.
Thirdly, we intended to develop genetically and phenotypically stable transgene- expressing replication-competent arenaviruses
The Nucleoprotein Is Required for Lymphocytic Choriomeningitis Virus-Based Vaccine Vector Immunogenicity
Recombinant glycoprotein-deficient lymphocytic choriomeningitis virus-based vaccine vectors (rLCMV/ΔGP) are potent CD8(+) T cell inducers. To investigate the underlying molecular requirements, we generated a nucleoprotein-deficient vector counterpart (rLCMV/ΔNP). NP but not GP is a minimal trans-acting factor for viral transcription and genome replication. We found that, unlike rLCMV/ΔGP, rLCMV/ΔNP failed to elicit detectable CD8(+) T cell responses unless NP was trans complemented in a transgenic host. Hence, NP-dependent intracellular gene expression is essential for LCMV vector immunogenicity
Antisense oligonucleotide targeting CD39 improves anti-tumor T cell immunity
Abstract Background Cancer cells are known to develop mechanisms to circumvent effective anti-tumor immunity. The two ectonucleotidases CD39 and CD73 are promising drug targets, as they act in concert to convert extracellular immune-stimulating ATP to adenosine. CD39 is expressed by different immune cell populations as well as cancer cells of different tumor types and supports the tumor in escaping immune recognition and destruction. Thus, increasing extracellular ATP and simultaneously reducing adenosine concentrations in the tumor can lead to effective anti-tumor immunity. Methods We designed locked nucleic acid (LNA)-modified antisense oligonucleotides (ASOs) with specificity for human or mouse CD39 that do not need a transfection reagent or delivery system for efficient target knockdown. Knockdown efficacy of ASOs on mRNA and protein level was investigated in cancer cell lines and in primary human T cells. The effect of CD39 knockdown on ATP-degrading activity was evaluated by measuring levels of ATP in tumor cell supernatants and analysis of T cell proliferation in the presence of extracellular ATP. The in vivo effects of CD39-specific ASOs on target expression, anti-tumor immune responses and on tumor growth were analyzed in syngeneic mouse tumor models using multi-color flow cytometry. Results CD39-specific ASOs suppressed expression of CD39 mRNA and protein in different murine and human cancer cell lines and in primary human T cells. Degradation of extracellular ATP was strongly reduced by CD39-specific ASOs. Strikingly, CD39 knockdown by ASOs was associated with improved CD8+ T cell proliferation. Treatment of tumor-bearing mice with CD39-specific ASOs led to dose-dependent reduction of CD39-protein expression in regulatory T cells (Tregs) and tumor-associated macrophages. Moreover, frequency of intratumoral Tregs was substantially reduced in CD39 ASO-treated mice. As a consequence, the ratio of CD8+ T cells to Tregs in tumors was improved, while PD-1 expression was induced in CD39 ASO-treated intratumoral CD8+ T cells. Consequently, CD39 ASO treatment demonstrated potent reduction in tumor growth in combination with anti-PD-1 treatment. Conclusion Targeting of CD39 by ASOs represents a promising state-of-the art therapeutic approach to improve immune responses against tumors
The alarmin interleukin-33 drives protective antiviral CD8⁺ T cell responses
Pathogen-associated molecular patterns decisively influence antiviral immune responses, whereas the contribution of endogenous signals of tissue damage, also known as damage-associated molecular patterns or alarmins, remains ill defined. We show that interleukin-33 (IL-33), an alarmin released from necrotic cells, is necessary for potent CD8(+) T cell (CTL) responses to replicating, prototypic RNA and DNA viruses in mice. IL-33 signaled through its receptor on activated CTLs, enhanced clonal expansion in a CTL-intrinsic fashion, determined plurifunctional effector cell differentiation, and was necessary for virus control. Moreover, recombinant IL-33 augmented vaccine-induced CTL responses. Radio-resistant cells of the splenic T cell zone produced IL-33, and efficient CTL responses required IL-33 from radio-resistant cells but not from hematopoietic cells. Thus, alarmin release by radio-resistant cells orchestrates protective antiviral CTL responses
Heterologous arenavirus vector prime-boost overrules self-tolerance for efficient tumor-specific CD8 T cell attack
Therapeutic vaccination regimens inducing clinically effective tumor-specific CD8+ T lymphocyte (CTL) responses are an unmet medical need. We engineer two distantly related arenaviruses, Pichinde virus and lymphocytic choriomeningitis virus, for therapeutic cancer vaccination. In mice, life-replicating vector formats of these two viruses delivering a self-antigen in a heterologous prime-boost regimen induce tumor-specific CTL responses up to 50% of the circulating CD8 T cell pool. This CTL attack eliminates established solid tumors in a significant proportion of animals, accompanied by protection against tumor rechallenge. The magnitude of CTL responses is alarmin driven and requires combining two genealogically distantly related arenaviruses. Vector-neutralizing antibodies do not inhibit booster immunizations by the same vector or by closely related vectors. Rather, CTL immunodominance hierarchies favor vector backbone-targeted responses at the expense of self-reactive CTLs. These findings establish an arenavirus-based immunotherapy regimen that allows reshuffling of immunodominance hierarchies and breaking self-directed tolerance for efficient tumor control
Interleukin-33-Activated Islet-Resident Innate Lymphoid Cells Promote Insulin Secretion through Myeloid Cell Retinoic Acid Production
Pancreatic-islet inflammation contributes to the failure of β cell insulin secretion during obesity and type 2 diabetes. However, little is known about the nature and function of resident immune cells in this context or in homeostasis. Here we show that interleukin (IL)-33 was produced by islet mesenchymal cells and enhanced by a diabetes milieu (glucose, IL-1β, and palmitate). IL-33 promoted β cell function through islet-resident group 2 innate lymphoid cells (ILC2s) that elicited retinoic acid (RA)-producing capacities in macrophages and dendritic cells via the secretion of IL-13 and colony-stimulating factor 2. In turn, local RA signaled to the β cells to increase insulin secretion. This IL-33-ILC2 axis was activated after acute β cell stress but was defective during chronic obesity. Accordingly, IL-33 injections rescued islet function in obese mice. Our findings provide evidence that an immunometabolic crosstalk between islet-derived IL-33, ILC2s, and myeloid cells fosters insulin secretion