Non-permissive human conventional CD1c+ dendritic cells enable trans-infection of human primary renal tubular epithelial cells and protect BK polyomavirus from neutralization.

The BK polyomavirus (BKPyV) is a ubiquitous human virus that persists in the renourinary epithelium. Immunosuppression can lead to BKPyV reactivation in the first year post-transplantation in kidney transplant recipients (KTRs) and hematopoietic stem cell transplant recipients. In KTRs, persistent DNAemia has been correlated to the occurrence of polyomavirus-associated nephropathy (PVAN) that can lead to graft loss if not properly controlled. Based on recent observations that conventional dendritic cells (cDCs) specifically infiltrate PVAN lesions, we hypothesized that those cells could play a role in BKPyV infection. We first demonstrated that monocyte-derived dendritic cells (MDDCs), an in vitro model for mDCs, captured BKPyV particles through an unconventional GRAF-1 endocytic pathway. Neither BKPyV particles nor BKPyV-infected cells were shown to activate MDDCs. Endocytosed virions were efficiently transmitted to permissive cells and protected from the antibody-mediated neutralization. Finally, we demonstrated that freshly isolated CD1c+ mDCs from the blood and kidney parenchyma behaved similarly to MDDCs thus extending our results to cells of clinical relevance. This study sheds light on a potential unprecedented CD1c+ mDC involvement in the BKPyV infection as a promoter of viral spreading.

gH625 Cell-Penetrating Peptide Promotes the Endosomal Escape of Nanovectorized siRNA in a Triple-Negative Breast Cancer Cell Line.

The use of small interfering RNA (siRNA) to regulate oncogenes appears as a promising strategy in the context of cancer therapy, especially if they are vectorized by a smart delivery system. In this study, we investigated the cellular trafficking of a siRNA nanovector (called CS-MSN) functionalized with the cell-penetrating peptide gH625 in a triple-negative breast cancer model. With complementary techniques, we showed that siRNA nanovectors were internalized by both clathrin- and caveolae-mediated endocytosis. The presence of gH625 at the surface of the siRNA nanovector did not modify the entry pathway of CS-MSN, but it increased the amount of siRNA found inside the cells. Results suggested an escape of siRNA from endosomes, which is enhanced by the presence of the peptide gH625, whereas nanoparticles continued their trafficking into lysosomes. The efficiency of CS-MSN to inhibit the GFP in MDA-MB-231 cells was 1.7-fold higher than that of the nanovectors without gH625.

Small Molecule-Based Fluorescent Organic Nanoassemblies with Strong Hydrogen Bonding Networks for Fine Tuning and Monitoring Drug Delivery in Cancer Cells.

Bright supramolecular fluorescent organic nanoassemblies (FONs), based on strongly polar red-emissive benzothiadiazole fluorophores containing acidic units, are fabricated to serve as theranostic tools with large colloidal stability in the absence of a polymer or surfactant. High architectural cohesion is ensured by the multiple hydrogen-bonding networks, reinforced by the dipolar and hydrophobic interactions developed between the dyes. Such interactions are harnessed to ensure high payload encapsulation and efficient trapping of hydrophobic and hydrogen-bonding drugs like doxorubicin, as shown by steady state and time-resolved measurements. Fine tuning of the drug release in cancer cells is achieved by adjusting the structure and combination of the fluorophore acidic units. Notably delayed drug delivery is observed by confocal microscopy compared to the entrance of hydrosoluble doxorubicin, demonstrating the absence of undesirable burst release outside the cells by using FONs. Since FON-constituting fluorophores exhibit a large emission shift from red to green when dissociating in contact with the lipid cellular content, drug delivery could advantageously be followed by dual-color spectral detection, independently of the drug staining potentiality.

An intermediate level of CD161 expression defines a novel activated, inflammatory, and pathogenic subset of CD8+ T cells involved in multiple sclerosis.

Several lines of evidence support a key role for CD8+ T cells in central nervous system tissue damage of patients with multiple sclerosis. However, the precise phenotype of the circulating CD8+ T cells that may be recruited from the peripheral blood to invade the CNS remains largely undefined to date. It has been suggested that IL-17 secreting CD8 (Tc17) T cells may be involved, and in humans these cells are characterized by the expression of CD161. We focused our study on a unique and recently described subset of CD8 T cells characterized by an intermediate expression of CD161 as its role in neuroinflammation has not been investigated to date. The frequency, phenotype, and function of CD8+ T cells with an intermediate CD161 expression level were characterized ex-vivo, in vitro, and in situ using RNAseq, RT-PCR, flow cytometry, TCR sequencing, and immunohistofluorescence of cells derived from healthy volunteers (n = 61), MS subjects (n = 90), as well as inflammatory (n = 15) and non-inflammatory controls (n = 6). We report here that CD8+CD161int T cells present characteristics of effector cells, up-regulate cell-adhesion molecules and have an increased ability to cross the blood-brain barrier and to secrete IL-17, IFNγ, GM-CSF, and IL-22. We further demonstrate that these cells are recruited and enriched in the CNS of MS subjects where they produce IL-17. In the peripheral blood, RNAseq, RT-PCR, high-throughput TCR repertoire analyses, and flow cytometry confirmed an increased effector and transmigration pattern of these cells in MS patients, with the presence of supernumerary clones compared to healthy controls. Our data demonstrate that intermediate levels of CD161 expression identifies activated and effector CD8+ T cells with pathogenic properties that are recruited to MS lesions. This suggests that CD161 may represent a biomarker and a valid target for the treatment of neuroinflammation.

Alternative Splice Transcripts for MHC Class I-like MICA Encode Novel NKG2D Ligands with Agonist or Antagonist Functions.

MHC class I chain-related proteins A and B (MICA and MICB) and UL16-binding proteins are ligands of the activating NKG2D receptor involved in cancer and immune surveillance of infection. Structurally, MICA/B proteins contain an α3 domain, whereas UL16-binding proteins do not. We identified novel alternative splice transcripts for MICA encoding five novel MICA isoforms: MICA-A, -B1, -B2, -C, and -D. Alternative splicing associates with MICA*015 and *017 and results from a point deletion (G) in the 5' splice donor site of MICA intron 4 leading to exon 3 and exon 4 skipping and/or deletions. These changes delete the α3 domain in all isoforms, and the α2 domain in the majority of isoforms (A, B1, C, and D). Endothelial and hematopoietic cells contained endogenous alternative splice transcripts and isoforms. MICA-B1, -B2, and -D bound NKG2D by surface plasmon resonance and were expressed at the cell surface. Functionally, MICA-B2 contains two extracellular domains (α1 and α2) and is a novel potent agonist ligand for NKG2D. We found that MICA-D is a new truncated form of MICA with weak affinity for NKG2D despite lacking α2 and α3 domains. MICA-D may functionally impair NKG2D activation by competing with full-length MICA or MICA-B2 for NKG2D engagement. Our study established NKG2D binding for recombinant MICA-B1 but found no function for this isoform. New truncated MICA isoforms exhibit a range of functions that may drive unexpected immune mechanisms and provide new tools for immunotherapy.

IL-15.IL-15Rα complex shedding following trans-presentation is essential for the survival of IL-15 responding NK and T cells.

Interleukin (IL)-15 and its specific receptor chain, IL-15Rα, support the development of various effector cells, including NK and CD8 T cells via a mechanism called trans-presentation. Whereas the dynamic of trans-presentation has been shown to involve the recycling of IL-15Rα by presenting cells, the way responding cells integrate, or take advantage of this process has not been evaluated yet. To address this question, we set up a trans-presentation model using a membrane-bound IL-15.IL-15Rα fusion protein, and found that IL-15 is detectable within responding cells following IL-15 trans-presentation. The role of the proteolytic cleavage of IL-15Rα in this process was investigated by generating an uncleavable form of IL-15Rα. We showed that IL-15 entry into responding cells necessitates the cleavage of IL-15.IL-15Rα complex from the surface of IL-15 presenting cells, and observed that IL-15Rα cleavage is associated with a decrease of the duration of Stat5 signaling. Once separated from presenting cells, responding cells are able to recycle IL-15.IL-15Rα complexes via intracellular compartments, for residual proliferation in a time-limited manner. These studies define an unprecedented cytokine pathway in which the IL-15.IL-15Rα complex cleaved from presenting cells allows responding cells to internalize, store and use IL-15.IL-15Rα complex for their own proliferation and survival.

Anti-CD28 Antibody and Belatacept Exert Differential Effects on Mechanisms of Renal Allograft Rejection.

Belatacept is a biologic that targets CD80/86 and prevents its interaction with CD28 and its alternative ligand, cytotoxic T lymphocyte antigen 4 (CTLA-4). Clinical experience in kidney transplantation has revealed a high incidence of rejection with belatacept, especially with intensive regimens, suggesting that blocking CTLA-4 is deleterious. We performed a head to head assessment of FR104 (n=5), a selective pegylated Fab' antibody fragment antagonist of CD28 that does not block the CTLA-4 pathway, and belatacept (n=5) in kidney allotransplantation in baboons. The biologics were supplemented with an initial 1-month treatment with low-dose tacrolimus. In cases of acute rejection, animals also received steroids. In the belatacept group, four of five recipients developed severe, steroid-resistant acute cellular rejection, whereas FR104-treated animals did not. Assessment of regulatory T cell-specific demethylated region methylation status in 1-month biopsy samples revealed a nonsignificant trend for higher regulatory T cell frequencies in FR104-treated animals. Transcriptional analysis did not reveal significant differences in Th17 cytokines but did reveal higher levels of IL-21, the main cytokine secreted by CD4 T follicular helper (Tfh) cells, in belatacept-treated animals. In vitro, FR104 controlled the proliferative response of human preexisting Tfh cells more efficiently than belatacept. In mice, selective CD28 blockade also controlled Tfh memory cell responses to KLH stimulation more efficiently than CD80/86 blockade. Our data reveal that selective CD28 blockade and belatacept exert different effects on mechanisms of renal allograft rejection, particularly at the level of Tfh cell stimulation.

Neuropathologic, phenotypic and functional analyses of Mucosal Associated Invariant T cells in Multiple Sclerosis.

BACKGROUND: The involvement of Mucosal Associated Invariant T (MAIT) cells, which are anti-microbial semi-invariant T cells, remains elusive in Multiple Sclerosis (MS). OBJECTIVE: Deciphering the potential involvement of MAIT cells in the MS inflammatory process. METHODS: By flow cytometry, blood MAIT cells from similar cohorts of MS patients and healthy volunteers (HV) were compared for frequency, phenotype, activation potential after in vitro TCR engagement by bacterial ligands and transmigration abilities through an in vitro model of blood-brain barrier. MS CNS samples were also studied by immunofluorescent staining and quantitative PCR. RESULTS AND CONCLUSION: Blood MAIT cells from relapsing-remitting MS patients and HV presented similar frequency, ex vivo effector phenotype and activation abilities. MAIT cells represented 0.5% of the total infiltrating T cells on 39 MS CNS lesions. This is low as compared to blood frequency (p<0.001), but consistent with their low transmigration rate. Finally, transcriptional over-expression of MR1 - which presents cognate antigens to MAIT cells - and of the activating cytokines IL-18 and IL-23 was evidenced in MS lesions, suggesting that the CNS microenvironment is suited to activate the few infiltrating MAIT cells. Taken together, these data place MAIT cells from MS patients as minor components of the inflammatory pathological process.

Key implication of CD277/butyrophilin-3 (BTN3A) in cellular stress sensing by a major human γδ T-cell subset.

Human peripheral Vγ9Vδ2 T cells are activated by phosphorylated metabolites (phosphoagonists [PAg]) of the mammalian mevalonate or the microbial desoxyxylulose-phosphate pathways accumulated by infected or metabolically distressed cells. The underlying mechanisms are unknown. We show that treatment of nonsusceptible target cells with antibody 20.1 against CD277, a member of the extended B7 superfamily related to butyrophilin, mimics PAg-induced Vγ9Vδ2 T-cell activation and that the Vγ9Vδ2 T-cell receptor is implicated in this effect. Vγ9Vδ2 T-cell activation can be abrogated by exposing susceptible cells (tumor and mycobacteria-infected cells, or aminobisphosphonate-treated cells with up-regulated PAg levels) to antibody 103.2 against CD277. CD277 knockdown and domain-shuffling approaches confirm the key implication of the CD277 isoform BTN3A1 in PAg sensing by Vγ9Vδ2 T cells. Fluorescence recovery after photobleaching (FRAP) experiments support a causal link between intracellular PAg accumulation, decreased BTN3A1 membrane mobility, and ensuing Vγ9Vδ2 T-cell activation. This study demonstrates a novel role played by B7-like molecules in human γδ T-cell antigenic activation and paves the way for new strategies to improve the efficiency of immunotherapies using Vγ9Vδ2 T cells.

Human Vgamma9Vdelta2 T cells: from signals to functions.

Human Vgamma9Vdelta2 T cells, a major innate-like peripheral T cell subset, are thought to play in vivo a key role in innate and adaptive immune responses to infection agents and tumors. Vgamma9Vdelta2 T cell activation is tightly regulated by a variety of activating or inhibitory receptors which are specific for constitutively expressed or stress-modulated ligands. However, the mechanisms and signal transduction pathways regulating their broad effector functions, such as cytotoxicity and cytokine responses, remain poorly understood. Here we provide an updated overview of the activation modalities of Vgamma9Vdelta2 T cells by highlighting the respective role played by T cell receptor (TCR) versus non-TCR stimuli, and focus on recent studies showing how Vgamma9Vdelta2 T cells integrate the numerous activating and inhibitory signals and translate them into a particular effector and biological function. A better understanding of these critical issues should help optimize immunotherapeutic approaches targeting Vgamma9Vdelta2 T cells.

The molecular basis for modulation of human Vγ9Vδ2 T cell responses by CD277/butyrophilin-3 (BTN3A)-specific antibodies.

Human Vγ9Vδ2 T cells are well known for their rapid and potent response to infection and tumorigenesis when in the presence of endogenous or exogenous phosphoisoprenoids. However, the molecular mechanisms behind the activation of this γδ T cell population remains unclear. Evidence pointing to a role for the CD277/butyrophilin-3 (BTN3A) molecules in this response led us to investigate the structures of these molecules and their modifications upon binding to an agonist antibody (20.1) that mimics phosphoisoprenoid-mediated Vγ9Vδ2 activation and an antagonist antibody (103.2) that inhibits this reactivity. We find that the three BTN3A isoforms: BTN3A1, BTN3A2, and BTN3A3, have high structural homology to the B7 superfamily of proteins and exist as V-shaped homodimers in solution, associating through the membrane proximal C-type Ig domain. The 20.1 and 103.2 antibodies bind to separate epitopes on the BTN3A Ig-V domain with high affinity but likely with different valencies based on their binding orientation. These structures directly complement functional studies of this system that demonstrate that BTN3A1 is necessary for Vγ9Vδ2 activation and begin to unravel the extracellular events that occur during stimulation through the Vγ9Vδ2 T cell receptor.

Click-electrochemistry for the rapid labeling of virus, bacteria and cell surfaces.

Methods for direct covalent ligation of microorganism surfaces remain poorly reported, and mostly based on metabolic engineering for bacteria and cells functionalization. While effective, a faster method avoiding the bio-incorporation step would be highly complementary. Here, we used N-methylluminol (NML), a fully tyrosine-selective protein anchoring group after one-electron oxidation, to label the surface of viruses, living bacteria and cells. The functionalization was performed electrochemically and in situ by applying an electric potential to aqueous buffered solutions of tagged NML containing the viruses, bacteria or cells. The broad applicability of the click-electrochemistry method was explored on recombinant adeno-associated viruses (rAAV2), Escherichia coli (Gram-) and Staphyloccocus epidermidis (Gram + ) bacterial strains, and HEK293 and HeLa eukaryotic cell lines. Surface electro-conjugation was achieved in minutes to yield functionalized rAAV2 that conserved both structural integrity and infectivity properties, and living bacteria and cell lines that were still alive and able to divide.

NKG2D costimulates human V gamma 9V delta 2 T cell antitumor cytotoxicity through protein kinase C theta-dependent modulation of early TCR-induced calcium and transduction signals.

Human Vgamma9Vdelta2 T cells, a major innate-like peripheral T cell subset, are thought to play in vivo an important role in innate and adaptive immune responses to infection agents and tumors. However, the mechanisms regulating their broad effector functions, such as cytotoxicity and cytokine responses, remain poorly understood. In this study, we used single-cell calcium video imaging to analyze the early intracellular events associated with TCR-induced Vgamma9Vdelta2 T cell functional responses. When compared with other human T cell subsets, including NKT and Vdelta2(neg) gammadelta T cells, TCR/CD3-activated Vgamma9Vdelta2 T cells displayed an unusually delayed and sustained intracellular calcium mobilization, which was dramatically quickened and shortened on costimulation by NKG2D, a main activating NKR regulating gammadelta T cell tumor cytolysis. Importantly, the protein kinase C transduction pathway was identified as a main regulator of the NKG2D-mediated costimulation of antitumor Vgamma9Vdelta2 cytolytic responses. Therefore, this study identifies a new mechanism regulating Vgamma9Vdelta2 T cell functional plasticity through fine-tuning of early signal transduction events.

Neuropilin-1 modulates the 3D invasive properties of glioblastoma stem-like cells.

Glioblastoma multiforme (GBM) is a rare, yet devastating, primary brain tumor in adults. Current treatments remain generally ineffective and GBM almost invariably recurs, resulting in median survival of 15 months. This high malignancy sources notably from the resilience and invasive capabilities of tumor cells. Within GBM, exists a population of self-sustaining transformed cells with stem-like properties (GSCs), which are thought to be responsible for tumor initiation, growth, and invasion, as well as recurrence. In the tumor microenvironment, GSCs might be found in the vicinity of brain endothelial cells, which provide a protective habitat. Likewise, these resistant, quiescent GSCs may accumulate in hypoxic zones, away from the perivascular niche, or travel towards the healthy brain parenchyma, by eminently co-opting neuro-vascular tracks. Herein, we established an ex vivo model to explore GSC invasive behavior. We found that patient-derived cells massively invade the collagen matrix. In addition, we described that the glycoprotein Neuropilin-1 (NRP1) contributes to GSC spreading and invasion. Indeed, both RNA interference-mediated silencing and CRISPR-mediated gene editing deletion of NRP1 strongly impaired the 3D invasive properties of patient-derived GSCs and their close localization to the brain blood vessels. Of note, other typical features of GSCs, such as expansion and self-renewal were maintained. From a mechanistic standpoint, this biological effect might rely on the expression of the ß3 subunit integrin cell-extracellular matrix adhesive receptor. Our data, therefore, propose a reliable approach to explore invasive properties of patient glioma cells ex vivo and identify NRP1 as a mediator in this malignant process.

Impact of RAFT chain transfer agents on the polymeric shell density of magneto-fluorescent nanoparticles and their cellular uptake.

The impact of nanoparticle surface chemistry on cell interactions and especially cell uptake has become evident over the last few years in nanomedicine. Since PEG polymers have proved to be ideal tools for attaining stealthiness and favor escape from the in vivo mononuclear phagocytotic system, the accurate control of their geometry is of primary importance and can be achieved through reversible addition-fragmentation transfer (RAFT) polymerization. In this study, we demonstrate that the residual groups of the chain transfer agents (CTAs) introduced in the main chain exert a significant impact on the cellular internalization of functionalized nanoparticles. High-resolution magic angle spinning 1H NMR spectroscopy and fluorescence spectroscopy permitted by the magneto-fluorescence properties of nanoassemblies (NAs) revealed the compaction of the PEG comb-like shell incorporating CTAs with a long alkyl chain, without changing the overall surface potential. As a consequence of the capability of alkyl units to self-assemble at the NA surface while hardly contributing more than 0.5% to the total polyelectrolyte weight, denser PEGylated NAs showed notably less internalization in all cells of the tumor microenvironment (tumor cells, macrophages and healthy cells). Interestingly, such differentiated uptake is also observed between pro-inflammatory M1-like and immunosuppressive M2-like macrophages, with the latter more efficiently phagocytizing NAs coated with a less compact PEGylated shell. In contrast, the NA diffusion inside multicellular spheroids, used to mimic solid tumors, appeared to be independent of the NA coating. These results provide a novel effort-saving approach where the sole variation of the chemical nature of CTAs in RAFT PEGylated polymers strikingly modulate the cell uptake of nanoparticles upon the organization of their surface coating and open the pathway toward selectively addressing macrophage populations for cancer immunotherapy.

A functional network of highly pure enteric neurons in a dish.

The enteric nervous system (ENS) is the intrinsic nervous system that innervates the entire digestive tract and regulates major digestive functions. Recent evidence has shown that functions of the ENS critically rely on enteric neuronal connectivity; however, experimental models to decipher the underlying mechanisms are limited. Compared to the central nervous system, for which pure neuronal cultures have been developed for decades and are recognized as a reference in the field of neuroscience, an equivalent model for enteric neurons is lacking. In this study, we developed a novel model of highly pure rat embryonic enteric neurons with dense and functional synaptic networks. The methodology is simple and relatively fast. We characterized enteric neurons using immunohistochemical, morphological, and electrophysiological approaches. In particular, we demonstrated the applicability of this culture model to multi-electrode array technology as a new approach for monitoring enteric neuronal network activity. This in vitro model of highly pure enteric neurons represents a valuable new tool for better understanding the mechanisms involved in the establishment and maintenance of enteric neuron synaptic connectivity and functional networks.

Integrated pseudotime analysis of human pre-implantation embryo single-cell transcriptomes reveals the dynamics of lineage specification.

Understanding lineage specification during human pre-implantation development is a gateway to improving assisted reproductive technologies and stem cell research. Here we employ pseudotime analysis of single-cell RNA sequencing (scRNA-seq) data to reconstruct early mouse and human embryo development. Using time-lapse imaging of annotated embryos, we provide an integrated, ordered, and continuous analysis of transcriptomics changes throughout human development. We reveal that human trophectoderm/inner cell mass transcriptomes diverge at the transition from the B2 to the B3 blastocyst stage, just before blastocyst expansion. We explore the dynamics of the fate markers IFI16 and GATA4 and show that they gradually become mutually exclusive upon establishment of epiblast and primitive endoderm fates, respectively. We also provide evidence that NR2F2 marks trophectoderm maturation, initiating from the polar side, and subsequently spreads to all cells after implantation. Our study pinpoints the precise timing of lineage specification events in the human embryo and identifies transcriptomics hallmarks and cell fate markers.

γ9δ2T cell diversity and the receptor interface with tumor cells.

γ9δ2T cells play a major role in cancer immune surveillance, yet the clinical translation of their in vitro promise remains challenging. To address limitations of previous clinical attempts using expanded γ9δ2T cells, we explored the clonal diversity of γ9δ2T cell repertoires and characterized their target. We demonstrated that only a fraction of expanded γ9δ2T cells was active against cancer cells and that activity of the parental clone, or functional avidity of selected γ9δ2 T cell receptors (γ9δ2TCRs), was not associated with clonal frequency. Furthermore, we analyzed the target-receptor interface and provided a 2-receptor, 3-ligand model. We found that activation was initiated by binding of the γ9δ2TCR to BTN2A1 through the regions between CDR2 and CDR3 of the TCR γ chain and modulated by the affinity of the CDR3 region of the TCRδ chain, which was phosphoantigen independent (pAg independent) and did not depend on CD277. CD277 was secondary, serving as a mandatory coactivating ligand. We found that binding of CD277 to its putative ligand did not depend on the presence of γ9δ2TCR, did depend on usage of the intracellular CD277, created pAg-dependent proximity to BTN2A1, enhanced cell-cell conjugate formation, and stabilized the immunological synapse (IS). This process critically depended on the affinity of the γ9δ2TCR and required membrane flexibility of the γ9δ2TCR and CD277, facilitating their polarization and high-density recruitment during IS formation.

Hybrid Azo-fluorophore Organic Nanoparticles as Emissive Turn-on Probes for Cellular Endocytosis.

The development of fluorescent organic nanoparticles, serving as bioimaging agents or drug cargos, represents a buoyant field of investigations. Nevertheless, their ulterior fate and structural integrity after cell uptake remain elusive. Toward this aim, we have elaborated original photoactive organic nanoparticles (dTEM ∼ 35-50 nm wide) with an off-on signal upon cellular internalization. Such nanoparticles are based on the noncovalent association of red-emitting benzothiadiazole (BDZ) derivatives and azo dyes, acting as fluorescence quenchers. Upon varying the azo/BDZ ratio, we found that quantitative emission quenching could be obtained with only a 0.2:1 azo/BDZ ratio and originated from exergonic oxidative and reductive photoinduced electron transfer from the azo units (ΔelG0 = -0.21 and -0.29 eV, respectively). Such results revisited the origin of emission quenching, often confusedly ascribed to Förster resonance energy transfer. A nonlinear and sharp drop of the emission intensity with the increase in the azo unit density n was observed and presents comparable evolution to a n-1/3 mathematical law. Thorough biological examinations involving cancer cells prove a receptor-independent endocytosis pathway, leading to progressive cell lighting upon nanoparticle accumulation in the late endosomal/lysosomal compartments. Complete emission recovery of the initially quenched azo/BDZ nanosystems could be achieved by using mefloquine, which caused endosomal/lysosomal disruption, and release of their content in the cytoplasm. Such results demonstrate that the dotlike emission from endosomes actually stems from fully dissociated individual dyes and not integer nanoparticles. They conclude on the high spatial confinement promoted by organelles and finally question its severe impact on functional compounds or nanoparticles whose properties are strongly distance dependent.

Bridging innate and adaptive immunity through gammadelta T-dendritic cell crosstalk.

Like Natural Killer cells, gammadelta T cells and Natural Killer T cells display several innate-like features that confer them a broad reactivity against tumors and pathogens. By recognizing stress-induced conserved antigens upregulated a wide array of physiopathological contexts, these lymphoid subsets develop strong and early responses to a broad set of targets. One of the most exciting roles possibly played in vivo by non-conventional T lymphocytes, which exhibit a biased natural memory phenotype, is active regulation of adaptive immune responses through interactions with antigen presenting cells (APCs), such as dendritic cells. Here we will review recent studies reporting functional interactions between gammadelta T cells and APC and a possible involvement of these lymphocytes in bridging innate and adaptative immunity along infections and tumor development. Our discussion will focus on human gammadelta T cells and more specifically on Vgamma9Vdelta2 T cells, a major subset found in human peripheral blood.