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Human Vγ9Vδ2 T cells recognize pyrophosphates produced by microbes and transformed cells and play a role in anti-infective immunity and tumor surveillance. Toll-like receptors (TLR) are pattern recognition receptors in innate immune cells which sense microbial structures including nucleic acids. Given that γδ T cells are in clinical development for application in cellular cancer immunotherapy and TLR ligands have potent adjuvant activity, we investigated the co-stimulatory role of selected TLR ligands in γδ T-cell activation. Here we have used recently described RNA ligands for TLR7 and TLR8 together with Vγ9Vδ2 T-cell specific pyrophosphate antigens to analyze the rapid cytokine induction in Vδ2 T cells as well as the accessory cell requirements. While TLR8- as well as TLR7/8-specific RNA did not induce IFN-γ in Vδ2 T cells on their own, they provided strong co-stimulation for Vδ2 T cells within peripheral blood mononuclear cells in the presence of additional T-cell receptor activation. In contrast, TLR7 ligands were ineffective. Purified γδ T cells did not directly respond to TLR8 co-stimulation but required the presence of monocytes. Further experiments revealed a critical role of IL-1β and IL-18, and to a slightly lesser extent of IL-12p70, in the co-stimulation of Vδ2 T cells by TLR8 and TLR7/8 RNA ligands. Results of intracellular cytokine expression were validated by ELISA analysis of cytokines in cell culture supernatants. The cell context-dependent adjuvant activity of TLR8 and TLR7/8 RNA ligands described here might be important for the future optimization of γδ T-cell based cancer immunotherapy. [ABSTRACT FROM AUTHOR]

γδ T cells share characteristics of innate and adaptive immune cells and are involved in a broad spectrum of pro-inflammatory functions. Nonetheless, there is accumulating evidence that γδ T cells also exhibit regulatory functions. In this review, we describe the different phenotypes of regulatory γδ T cells in correlation with the identified mechanisms of suppression. [ABSTRACT FROM AUTHOR]

Purpose: Physical activity can impact the immune system in different ways, e.g. by alteration of the humoral and cellular immune response. Physical activity at medium intensity enhances numbers of cytotoxic T cells, NK cells and macrophages in healthy people. The aim of this study was to compare the effects of endurance and resistance training on the immune system in breast cancer patients during adjuvant chemotherapy.Methods: In a prospective, controlled and randomized intervention exploratory trial, 12-week supervised endurance or resistance training were compared with usual care twice a week. Endpoints were the absolute numbers of the immune cells such as CD3+ T lymphocytes including CD4+- and CD8+, αβ T cells, γδT cells, CD3−/CD16+/56+ NK cells and CD19+ B cells, before and after 12 weeks of treatment. Cell numbers were analyzed using fluorescence-activated cell sorting.Results: Despite different physical interventions in all groups immune cell count decreased in CD3 T cells including TCR αβ and CD4 T cells, NK cells and CD19 B cells 12 weeks after initiation of chemotherapy and start of the physical intervention program, while the reduction of γδ T cells and CD8 T cells is less prominent in the RT and UC group.Conclusion: Chemotherapy led to a decrease in nearly all measured immune cells. In this study, physical intervention with endurance or resistance training did not suppress cellular immunity any further. Larger multicenter trials are needed to evaluate the exact impact of sports intervention on immune cell subpopulations. [ABSTRACT FROM AUTHOR]

The proliferation and interleukin-2 production of CD4CD25 αβ T cells were inhibited in a cell-contact manner by Vδ2 γδ T cells. The transcription factor Helios was constitutively expressed in about one-third of circulating γδ T cells and was upregulated by CD28-signaling. Our data suggest that Helios could serve as a marker for differential activation status rather than for regulatory T cells (Treg). Our findings also indicate that the interaction of CD86 on activated Vδ2 T cells and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) on activated αβ T cells mediated the suppression because the suppressive effect was abolished by blocking the CD86:CTLA-4 interaction. Pre-treatment of Vδ2 T cells with Toll-like receptor 2 ligands enhanced phosphorylation of MAPKs, Akt, and NF-κB and partially abrogated the suppressive capacity, whereas on co-cultured responder T cells inhibitory molecules were downregulated and Akt and NF-κB phosphorylation was restored. Our results suggest that the regulation of αβ T cell proliferation by activated Vδ2 T cells might contribute to fine-tuning of αβ T cell responses. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLR) are pattern-recognition receptors that recognize a broad variety of structurally conserved molecules derived from microbes. The recognition of TLR ligands functions as a primary sensor of the innate immune system, leading to subsequent indirect activation of the adaptive immunity as well as none-immune cells. However, TLR are also expressed by several T cell subsets, and the respective ligands can directly modulate their effector functions. The present review summarizes the recent findings of γδ T cell modulation by TLR ligands. TLR1/2/6, 3, and 5 ligands can act directly in combination with T cell receptor (TCR) stimulation to enhance cytokine/chemokine production of freshly isolated human γδ T cells. In contrast to human γδ T cells, murine and bovine γδ T cells can directly respond to TLR2 ligands with increased proliferation and cytokine production in a TCR-independent manner. Indirect stimulatory effects on IFN-γ production of human and murine γδ T cells via TLR-ligand activated dendritic cells have been described for TLR2, 3, 4, 7, and 9 ligands. In addition, TLR3 and 7 ligands indirectly increase tumor cell lysis by human γδ T cells, whereas ligation of TLR8 abolishes the suppressive activity of human tumor-infiltrating Vδ1 γδ T cells on αβ T cells and dendritic cells. Taken together, these data suggest that TLR-mediated signals received by γδ T cells enhance the initiation of adaptive immune responses during bacterial and viral infection directly or indirectly. Moreover, TLR ligands enhance cytotoxic tumor responses of γδ T cells and regulate the suppressive capacity of γδ T cells. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factor (VEGF) antagonists are currently the therapy of choice for age-related macular degeneration. Here we compared the effects of FDA-approved Ranibizumab and off-label used Bevacizumab on RPE cells, investigating their respective uptake by RPE cells over time. Primary porcine RPE cells were treated with Bevacizumab or Ranibizumab, respectively. Uptake of the respective VEGF-antagonists was assessed with confocal laser scanning microscopy and flow cytometry. Cell death was assessed with MTT assay and VEGF secretion was measured with ELISA. When clinical doses were applied for 1 h, Bevacizumab was taken up by RPE cells as assessed by confocal laser scanning microscopy and flow cytometry. After 24 h of incubation, and further assessed after 1d, 5d, and 7d, Bevacizumab was detected in RPE cells where it accumulated over time. The presence of Bevacizumab within RPE cells after 7d was confirmed by flow cytometry. While some Ranibizumab was found in RPE cells after 1 h of incubation when assessed with confocal laser microscopy but not by flow cytometry, no signal above control was detected after 1d, 5d, or 7d. Neither substance induced significant cell death after 7 days and no inhibitory effect on VEGF secretion was observed after day 3 of culture. Bevacizumab, but not Ranibizumab, accumulates in RPE cells over time, implying substantial differences between these two drugs. [ABSTRACT FROM AUTHOR]

A numerically small subset of human T lymphocytes expresses a γδ T cell receptor (TCR). These γδ T cells share certain effector functions with αβ T cells as well as with NK cells and NKT cells. The major peripheral blood γδ T cell subset in healthy adults expresses a Vγ9Vδ2 TCR, which recognizes small phosphorylated metabolites referred to as phosphoantigens. Vδ1 γδ T cells mainly occur in the intestine. They recognize the stress-induced MICA/B and CD1c. Furthermore, γδ T cells express a variety of NK cell and pattern-recognition receptors which are responsible for the “fine-tuning” of effector functions. In recent years, γδ T cells start to emerge as a rewarding target for immunotherapeutic strategies against viral infections and cancer. A better understanding of factors that modulate γδ T cell function will further eluminate the potential of these cells. [ABSTRACT FROM AUTHOR]

Signaling of the pleiotropic cytokine Interleukin-6 (IL-6) via its soluble IL-6R (sIL-6R) has been termed trans-signaling and is thought to be responsible for the pro-inflammatory properties of IL-6. The sIL-6R can be generated by alternative mRNA splicing or proteolytic cleavage of the membrane-bound IL-6R. However, which stimuli induce sIL-6R release and which endogenous signaling pathways are required for this process is poorly understood. Here, we show that activation of Toll-like receptor 2 (TLR2) on primary human peripheral blood mononuclear cells (PBMCs) and on the monocytic cell line THP-1 induces expression and secretion of IL-6 and the generation of sIL-6R. We show by flow cytometry that monocytes are a PBMC subset that expresses TLR2 in conjunction with the IL-6R and are the major cellular source for both IL-6 and sIL-6R. Mechanistically, we find that the metalloproteases ADAM10 and ADAM17 are responsible for cleavage of the IL-6R and therefore sIL-6R generation. Finally, we identify the Extracellular-signal Regulated Kinase (ERK) cascade as a critical pathway that differentially regulates both IL-6 and sIL-6R generation in monocytes. [ABSTRACT FROM AUTHOR]