Over the last few years, immunotherapy for HIV in general and therapeutic vaccination in particular, has received a tremendous boost, both in preclinical research and in clinical applications. This ...interest is based on the evidence that the immune system plays a crucial role in controlling HIV infection, as shown for long-term non-progressors and elite controllers, and that immune responses can be manipulated towards targeting conserved epitopes. So far, the most successful approach has been vaccination with autologous dendritic cells (DCs) loaded ex vivo with antigens and activation signals. Although this approach offers much promise, it also comes with significant drawbacks such as the requirement of a specialized infrastructure and expertise, as well as major challenges for logistics and storage, making it extremely time consuming and costly. Therefore, methods are being developed to avoid the use of ex vivo generated, autologous DCs. One of these methods is based on mRNA for therapeutic vaccination. mRNA has proven to be a very promising vaccine platform, as the coding information for any desired protein, including antigens and activation signals, can be generated in a very short period of time, showing promise both as an off-the-shelf therapy and as a personalized approach. However, an important drawback of this approach is the short half-life of native mRNA, due to the presence of ambient RNases. In addition, proper immunization requires that the antigens are expressed, processed and presented at the right immunological site (e.g. the lymphoid tissues). An ambivalent aspect of mRNA as a vaccine is its capacity to induce type I interferons, which can have beneficial adjuvant effects, but also deleterious effects on mRNA stability and translation. Thus, proper formulation of the mRNA is crucially important. Many approaches for RNA formulation have already been tested, with mixed success. In this review we discuss the state-of-the-art and future trends for mRNA-nanoparticle formulations for HIV vaccination, both in the prophylactic and in the therapeutic setting.
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T lymphocytes (T cells) are major players of the adaptive immune response. Naive T cells are primed in the presence of cytokines, leading to polarization into distinct T‐cell subsets with specific ...functions. These subsets are classified based on their T‐cell receptor profile, expression of transcription factors, surface cytokine and chemokine receptors, and their cytokine production, which together determine their specific function. This review provides an overview of the various T‐cell subsets and their function in several inflammatory skin disorders ranging from allergic inflammation to skin tumors. Moreover, we highlight similarities of T‐cell responses across different skin disorders, demonstrating the presence of similar and opposing functions for the different T‐cell subsets. Finally, we discuss the effects of currently available and promising therapeutic approaches to harness T cells in inflammatory skin diseases for which efficacy next to unwanted side effects provide new insights into the pathophysiology of skin disorders.
Human CD83 is a marker molecule for mature dendritic cells (DC) and is also expressed on activated B and T cells. Although CD83 has been implicated in immune responses, its function on DC and T cells ...remains unclear. In this study, we wanted to assess the role of CD83 expressed on DC and T cells in the immune response. Down‐regulation of CD83 expression on human DC through RNA interference (RNAi) results in a less potent induction of allogeneic T cell proliferation, reduced IFN‐γ secretion by established T cells and decreased capacity in the priming of functional tumor antigen‐specific CD8+ T lymphocytes. In addition, CD83 mRNA‐electroporated DC are stronger T cell stimulators. However, CD83 overexpression on Melan‐A/MART‐1‐specific tumor‐infiltrating lymphocytes (TIL) circumvents the need for CD83 expression on DC. Co‐culture of immature DC with TIL or K562 cells overexpressing CD83 results in the production of enhanced levels of pro‐inflammatory cytokines, whereas this production is less pronounced or even absent in co‐cultures with non‐modified TIL or K562 cells. In conclusion, we demonstrate that CD83 expression on T cells and DC modulates the immune response by activating DC and by delivering costimulatory signals for the stimulation of naive and memory T cells, respectively.
Review on the impact of the cell death mechanism induced in tumor cells by oncolytic viruses on the ensuing anti‐tumor immune response.
Our understanding of the mechanisms responsible for cancer ...development has increased enormously over the last decades. However, for many cancers, this has not been translated into a significant improvement in overall survival, and overall mortality remains high. Treatment for many malignancies remains based on surgery, chemotherapy, and radiotherapy. Significant progress has been made toward the development of more specific, more potent, and less invasive treatment modalities, but such targeted therapies remain the exception for most cancers. Thus, cancer therapies based on a different mechanism of action should be explored. The immune system plays an important role in keeping tumor growth at bay. However, in many cases, these responses are not strong enough to keep tumor growth under control. Thus, immunotherapy aims to boost the immune system to suppress tumor growth efficiently. This has been demonstrated by the recent successes of immune checkpoint therapy in several cancers. Oncolytic viruses (OVs) are another exciting class of immunotherapy agent. As well as replicating selectively within and killing tumor cells, OVs are able to elicit potent anti‐tumor immune responses. Therapeutic vaccination with OVs, also referred to as cancer virotherapy, can thus be tailored to elicit vigorous cellular immune responses and even target individual malignancies in a personalized manner. In this review, we will describe the intricate link among oncolytic virotherapy, tumor immunology, and immunogenic cell death (ICD) and discuss ways to harness optimally their potential for future cancer therapy.
Abstract
Background
Combination antiretroviral therapy (cART) has dramatically extended the life expectancy of people living with HIV-1 and improved their quality of life. There is nevertheless no ...cure for HIV-1 infection since HIV-1 persists in viral reservoirs of latently infected CD4
+
T cells. cART does not eradicate HIV-1 reservoirs or restore cytotoxic natural killer (NK) cells which are dramatically reduced by HIV-1 infection, and express the checkpoint inhibitors NKG2A or KIR2DL upregulated after HIV-1 infection. Cytotoxic NK cells expressing the homing receptor CXCR5 were recently described as key subsets controlling viral replication.
Methods
We designed and evaluated the potency of “Natural killer activating Multimeric immunotherapeutic compleXes”, called as NaMiX, combining multimers of the IL-15/IL-15Rα complex with an anti-NKG2A or an anti-KIR single-chain fragment variable (scFv) to kill HIV-1 infected CD4
+
T cells. The oligomerization domain of the C4 binding protein was used to associate the IL-15/IL-15Rα complex to the scFv of each checkpoint inhibitor as well as to multimerize each entity into a heptamer (α form) or a dimer (β form). Each α or β form was compared in different in vitro models using one-way ANOVA and post-hoc Tukey’s tests before evaluation in humanized NSG tg-huIL-15 mice having functional NK cells.
Results
All NaMiX significantly enhanced the cytolytic activity of NK and CD8
+
T cells against Raji tumour cells and HIV-1
+
ACH-2 cells by increasing degranulation, release of granzyme B, perforin and IFN-γ. Targeting NKG2A had a stronger effect than targeting KIR2DL due to higher expression of NKG2A on NK cells. In viral inhibition assays, NaMiX initially increased viral replication of CD4
+
T cells which was subsequently inhibited by cytotoxic NK cells. Importantly, anti-NKG2A NaMiX enhanced activation, cytotoxicity, IFN-γ production and CXCR5 expression of NK cells from HIV-1 positive individuals. In humanized NSG tg-huIL-15 mice, we confirmed enhanced activation, degranulation, cytotoxicity of NK cells, and killing of HIV-1 infected cells from mice injected with the anti-NKG2A.α NaMiX, as compared to control mice, as well as decreased total HIV-1 DNA in the lung.
Conclusions
NK cell-mediated killing of HIV-1 infected cells by NaMiX represents a promising approach to support HIV-1 cure strategies.
Recently, a paradigm shift has been established for oncolytic viruses (OVs) as it was shown that the immune system plays an important role in the specific killing of tumor cells by OVs. OVs have the ...intrinsic capacity to provide the right signals to trigger anti-tumor immune responses, on the one hand by delivering virus-derived innate signals and on the other hand by inducing immunogenic cell death (ICD), which is accompanied by the release of various damage-associated molecules from infected tumor cells. Here, we determined the ICD-inducing capacity of Talimogene laherparepvec (T-VEC), a herpes simplex virus type 1 based OV, and benchmarked this to other previously described ICD (e.g., doxorubicin) and non-ICD inducing agents (cisplatin). Furthermore, we studied the capability of T-VEC to induce the maturation of human BDCA-1
myeloid dendritic cells (myDCs). We found that T-VEC treatment exerts direct and indirect anti-tumor effects as it induces tumor cell death that coincides with the release of hallmark mediators of ICD, while simultaneously contributing to the maturation of BDCA-1
myDCs. These results unequivocally cement OVs in the category of cancer immunotherapy.
Abstract
Background
Mechanical isolation of the stromal vascular fraction (SVF) separates the stromal component from the parenchymal cells. Emulsification is currently the most commonly used ...disaggregation method and is effective in disrupting adipocytes and fragmenting the extracellular matrix (ECM). Subsequent push-through filtration of emulsified adipose tissue removes parts of the ECM that are not sufficiently micronized, thereby further liquifying the tissue.
Objectives
The aim of this study was to investigate whether filtration over a 500-µm mesh filter might affect the SVF and adipose-derived mesenchymal stem cell (MSC) quantity in emulsified lipoaspirate samples by removing ECM fragments.
Methods
Eleven lipoaspirate samples from healthy nonobese women were harvested and emulsified in 30 passes. One-half of the sample was filtered through a 500-µm mesh filter and the other half was left unfiltered. Paired samples were processed and analyzed by flow cytometry to identify cellular viability, and SVF and MSC yield.
Results
Push-through filtration reduced the number of SVF cells by a mean standard deviation of 39.65% 5.67% (P < .01). It also significantly reduced MSC counts by 48.28% 6.72% (P < .01). Filtration did not significantly affect viability (P = .118).
Conclusions
Retention of fibrous remnants by push-through filters removed ECM containing the SVF and MSCs from emulsified lipoaspirates. Processing methods should aim either to further micronize the lipoaspirate before filtering or not to filter the samples at all, to preserve both the cellular component carried within the ECM and the inductive properties of the ECM itself.
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