Antibacterial and antibiofilm properties of two cyclic dipeptides produced by a new desert Streptomyces sp. HG-17 strain against multidrug-resistant pathogenic bacteria.

INTRODUCTION: The emergence of multidrug-resistant bacteria and biofilms requires discovering new antimicrobial agents from unexplored environments. OBJECTIVES: This study aims to isolate and characterize a new actinobacterial strain from the Hoggar Mountains in southern Algeria and evaluate its ability to produce bioactive molecules with potential antibacterial and antibiofilm activities. METHODS: A novel halotolerant actinobacterial strain, designated HG-17, was isolated from the Hoggar Mountains, and identified based on phenotypic characterizations, 16S rDNA sequence analysis, and phylogenetic analysis. The antibacterial and antibiofilm activities of the strain were assessed, and the presence of biosynthetic genes (PKS-I and NRPS) was confirmed. Two active compounds, HG-7 and HG-9, were extracted butanol solvent, purified by HPLC, and their chemical structures were elucidated using ESI mass spectrometry and NMR spectroscopy. RESULTS: The strain HG-17 was identified as Streptomyces purpureus NBRC with 98.8% similarity. It exhibited strong activity against multidrug-resistant and biofilm-forming bacteria. The two purified active compounds, HG-7 and HG-9, were identified as cyclo-(d-cis-hydroxyproline-l-phenylalanine) and cyclo-(l-prolone-l-tyrosine), respectively. The minimum inhibitory concentrations (MICs) of HG-7 and HG-9 ranged from 3 to 15 µg/mL, comparable to the MICs of tetracycline (8 to 15 µg/mL). Their minimum biofilm inhibitory concentration (MBIC 50%) showed good inhibition from 48.0 to 52.0% at concentrations of 1 to 7 µg/mL against the tested bacteria. CONCLUSION: This is the first report of cyclo-(d-cis-hydroxyproline-l-phenylalanine) and cyclo-(l-prolone-l-tyrosine) antibiotics from S. purpureus and their anti-multi-drug-resistant and biofilm-forming bacteria. These results indicate that both antibiotics could be used as effective therapeutics to control infections associated with multidrug-resistant bacteria.

Single-cell spatial explorer: easy exploration of spatial and multimodal transcriptomics.

BACKGROUND: The development of single-cell technologies yields large datasets of information as diverse and multimodal as transcriptomes, immunophenotypes, and spatial position from tissue sections in the so-called 'spatial transcriptomics'. Currently however, user-friendly, powerful, and free algorithmic tools for straightforward analysis of spatial transcriptomic datasets are scarce. RESULTS: Here, we introduce Single-Cell Spatial Explorer, an open-source software for multimodal exploration of spatial transcriptomics, examplified with 9 human and murine tissues datasets from 4 different technologies. CONCLUSIONS: Single-Cell Spatial Explorer is a very powerful, versatile, and interoperable tool for spatial transcriptomics analysis.

A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion.

Thousands of transiting exoplanets have been discovered, but spectral analysis of their atmospheres has so far been dominated by a small number of exoplanets and data spanning relatively narrow wavelength ranges (such as 1.1-1.7 micrometres). Recent studies show that some hot-Jupiter exoplanets have much weaker water absorption features in their near-infrared spectra than predicted. The low amplitude of water signatures could be explained by very low water abundances, which may be a sign that water was depleted in the protoplanetary disk at the planet's formation location, but it is unclear whether this level of depletion can actually occur. Alternatively, these weak signals could be the result of obscuration by clouds or hazes, as found in some optical spectra. Here we report results from a comparative study of ten hot Jupiters covering the wavelength range 0.3-5 micrometres, which allows us to resolve both the optical scattering and infrared molecular absorption spectroscopically. Our results reveal a diverse group of hot Jupiters that exhibit a continuum from clear to cloudy atmospheres. We find that the difference between the planetary radius measured at optical and infrared wavelengths is an effective metric for distinguishing different atmosphere types. The difference correlates with the spectral strength of water, so that strong water absorption lines are seen in clear-atmosphere planets and the weakest features are associated with clouds and hazes. This result strongly suggests that primordial water depletion during formation is unlikely and that clouds and hazes are the cause of weaker spectral signatures.

A New Saharan Strain of Streptomyces sp. GSB-11 Produces Maculosin and N-acetyltyramine Active Against Multidrug-Resistant Pathogenic Bacteria.

Multi-resistant bacterial pathogens are a major public health problem for treating nosocomial infections owing to their high resistance to antibiotics. The objective of this research was to characterize the bioactive molecules secreted by a novel moderately halophilic actinobacterium strain, designated GSB-11, exhibiting a strong antagonistic activity against several multidrug-resistant pathogenic bacteria. This potential strain was identified by phenotypic, genotypic (16S rRNA), and phylogenetic analyses. GSB-11 was related to "Streptomyces acrimycini" NBRC 12736 T with 99.59% similarity. Molecular screening by PCR assay demonstrated that the strain possesses two biosynthetic genes coding for NRPS and PKS-II. Two active compounds GSB11-6 and GSB11-7 were extracted from the cell-free culture supernatant of Bennett medium and purified using reversed-phase HPLC. According to spectrometric (mass spectrum) and spectroscopic (1H NMR, 13C NMR, 1H-1H COSY, and 1H-13C HMBC) spectra analyses, the compounds GSB11-6 and GSB11-7 were identified to be maculosin and N-acetyltyramine, respectively. Their minimum inhibitory concentrations (MIC) revealed interesting values against certain multidrug-resistant pathogenic bacteria. They were between 5 and 15 mg/mL for GSB11-6, 10 and 30 mg/mL for GSB11-7. To our best knowledge, this is the first study of these active substances isolated from "Streptomyces acrimycini" showing an interesting antibacterial activity. Therefore, these essential compounds could be candidates for future research against multidrug-resistant bacteria.

Single-cell RNA sequencing unveils the shared and the distinct cytotoxic hallmarks of human TCRVδ1 and TCRVδ2 γδ T lymphocytes.

γδ T lymphocytes represent ∼1% of human peripheral blood mononuclear cells and even more cells in most tissues of vertebrates. Although they have important anticancer functions, most current single-cell RNA sequencing (scRNA-seq) studies do not identify γδ T lymphocytes because their transcriptomes at the single-cell level are unknown. Here we show that high-resolution clustering of large scRNA-seq datasets and a combination of gene signatures allow the specific detection of human γδ T lymphocytes and identification of their T cell receptor (TCR)Vδ1 and TCRVδ2 subsets in large datasets from complex cell mixtures. In t-distributed stochastic neighbor embedding plots from blood and tumor samples, the few γδ T lymphocytes appear collectively embedded between cytotoxic CD8 T and NK cells. Their TCRVδ1 and TCRVδ2 subsets form close yet distinct subclusters, respectively neighboring NK and CD8 T cells because of expression of shared and distinct cytotoxic maturation genes. Similar pseudotime maturation trajectories of TCRVδ1 and TCRVδ2 γδ T lymphocytes were discovered, unveiling in both subsets an unattended pool of terminally differentiated effector memory cells with preserved proliferative capacity, a finding confirmed by in vitro proliferation assays. Overall, the single-cell transcriptomes of thousands of individual γδ T lymphocytes from different CMV+ and CMV- donors reflect cytotoxic maturation stages driven by the immunological history of donors. This landmark study establishes the rationale for identification, subtyping, and deep characterization of human γδ T lymphocytes in further scRNA-seq studies of complex tissues in physiological and disease conditions.

Single-Cell Signature Explorer for comprehensive visualization of single cell signatures across scRNA-seq datasets.

The momentum of scRNA-seq datasets prompts for simple and powerful tools exploring their meaningful signatures. Here we present Single-Cell_Signature_Explorer (https://sites.google.com/site/fredsoftwares/products/single-cell-signature-explorer), the first method for qualitative and high-throughput scoring of any gene set-based signature at the single cell level and its visualization using t-SNE or UMAP. By scanning datasets for single or combined signatures, it rapidly maps any multi-gene feature, exemplified here with signatures of cell lineages, biological hallmarks and metabolic pathways in large scRNAseq datasets of human PBMC, melanoma, lung cancer and adult testis.

Mzabimycins A and B, novel intracellular angucycline antibiotics produced by Streptomyces sp. PAL114 in synthetic medium containing L-tryptophan.

In our previous studies, the production of four bioactive molecules by Streptomyces sp. PAL114 in complex ISP2 broth medium has been described. Three of these molecules belong to the angucycline family. In this study, two novel antibiotics belonging to the same family were produced by strain PAL114 on M2 synthetic medium containing L-tryptophan as precursor. These antibiotics, named mzabimycins A and B, were intracellular and produced only in the presence of L-tryptophan. After four days of culturing PAL114 in the M2 medium, the bioactive compounds were extracted from mycelium with methanol and then analyzed by HPLC on reverse phase C18 column. Two active purplish blue fractions were purified. The chemical structures of these molecules were determined on the basis of spectroscopic and spectrometric analyses (1H and 13C NMR, and mass spectra). They were identified to be novel angucycline derivative antibiotics. The pure molecules showed activity against some pathogenic Gram-positive bacteria which have multiple antibiotic resistance, such as Staphylococcus aureus MRSA 639c and Listeria monocytogenes ATCC 13932.

Antimicrobial activities of novel bipyridine compounds produced by a new strain of Saccharothrix isolated from Saharan soil.

The actinobacterium strain ABH26 closely related to Saccharothrix xinjiangensis, isolated from an Algerian Saharan soil sample, exhibited highly antagonist activity against Gram-positive bacteria, yeasts and filamentous fungi. Its ability to produce antimicrobial compounds was investigated using several solid culture media. The highest antimicrobial activity was obtained on Bennett medium. The antibiotics secreted by strain ABH26 on Bennett medium were extracted by methanol and purified by reverse-phase HPLC using a C18 column. The chemical structures of the compounds were determined after spectroscopic (1H NMR, 13C NMR, 1H-1H COSY and 1H-13C HMBC spectra), and spectrometric (mass spectrum) analyses. Two new cyanogriside antibiotics named cyanogriside I (1) and cyanogriside J (2), were characterized along with three known caerulomycins, caerulomycin A (3), caerulomycin F (4) and caerulomycinonitrile (5). This is the first report of cyanogrisides and caerulomycins production by a member of the Saccharothrix genus. The minimum inhibitory concentrations (MIC) of these antibiotics were determined against pathogenic microorganisms.

Streptomyces sp. AT37 isolated from a Saharan soil produces a furanone derivative active against multidrug-resistant Staphylococcus aureus.

A novel actinobacterium strain, named AT37, showed a strong activity against some multidrug-resistant Staphylococcus aureus, including methicillin-resistant S. aureus MRSA ATCC 43300, other clinical isolates of MRSA and vancomycin resistant S. aureus VRSA S1. The strain AT37 was isolated from a Saharan soil by a dilution agar plating method using chitin-vitamin agar medium supplemented with rifampicin. The morphological and chemical studies indicated that this strain belonged to the genus Streptomyces. Its 16S rRNA gene sequence was determined and a database search indicated that it was closely associated with the type strain of Streptomyces novaecaesareae NBRC 13368T with 99.6% of similarity. However, the comparison of the morphological and the physiological characteristics of the strain with those of the nearest species showed significant differences. The strain AT37 secreted the antibiotic optimally during mid-stationary phase of growth. One active compound (AT37-1) was extracted from the culture broth with dichloromethane, separated on silica gel plates and purified by HPLC. Based on spectroscopic analysis of UV-Visible, infrared, and 1H and 13C NMR spectra and spectrometric analysis, the chemical structure of the compound AT37-1 was identified as 5-[(5E,7E,11E)-2,10-dihydroxy-9,11-dimethyl-5,7,11-tridecatrien-1-yl]-2-hydroxy-2-(1-hydroxyethyl)-4-methyl-3(2H)-furanone. Minimum inhibitory concentrations and minimum biofilm inhibitory concentration (MBIC50) of this compound showed significant activity against multidrug-resistant S. aureus with 15-30 and 10-15 µg/mL, respectively.

Cyclic dinucleotides modulate human T-cell response through monocyte cell death.

Cyclic dinucleotides, a class of microbial messengers, have been recently identified in bacteria, but their activity in humans remains largely unknown. Here, we have studied the function of cyclic dinucleotides in humans. We found that c-di-AMP and cGAMP, two adenosine-based cyclic dinucleotides, activated T lymphocytes in an unusual manner through monocyte cell death. c-di-AMP and cGAMP induced the selective apoptosis of human monocytes, and T lymphocytes were activated by the direct contact with these dying monocytes. The ensuing T-cell response comprised cell-cycle exit, phenotypic maturation into effector memory cells and proliferation arrest, but not cell death. This quiescence was transient since T cells remained fully responsive to further restimulation. Together, our results depict a novel activation pattern for human T lymphocytes: a transient quiescence induced by c-di-AMP- or cGAMP-primed apoptotic monocytes.

First-in-man phase 1 clinical trial of gene therapy for advanced pancreatic cancer: safety, biodistribution, and preliminary clinical findings.

This phase 1 trial was aimed to determine the safety, pharmacokinetics, and preliminary clinical activity of CYL-02, a nonviral gene therapy product that sensitizes pancreatic cancer cells to chemotherapy. CYL-02 was administrated using endoscopic ultrasound in 22 patients with pancreatic cancer that concomitantly received chemotherapy (gemcitabine). The maximum-tolerated dose (MTD) exceeded the maximal feasible dose of CYL-02 and was not identified. Treatment-related toxicities were mild, without serious adverse events. Pharmacokinetic analysis revealed a dose-dependent increase in CYL-02 DNA exposure in blood and tumors, while therapeutic RNAs were detected in tumors. No objective response was observed, but nine patients showed stable disease up to 6 months following treatment and two of these patients experienced long-term survival. Panels of plasmatic microRNAs and proteins were identified as predictive of gene therapy efficacy. We demonstrate that CYL-02 nonviral gene therapy has a favorable safety profile and is well tolerated in patients. We characterize CYL-02 biodistribution and demonstrate therapeutic gene expression in tumors. Treated patients experienced stability of disease and predictive biomarkers of response to treatment were identified. These promising results warrant further evaluation in phase 2 clinical trial.

Pancreatic preneoplastic lesions plasma signatures and biomarkers based on proteome profiling of mouse models.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies with a mortality that is almost identical to incidence. Because early detected PDAC is potentially curable, blood-based biomarkers that could detect currently developing neoplasia would improve patient survival and management. PDAC develops from pancreatic intraepithelial neoplasia (PanIN) lesions, graded from low grade (PanIN1) to high grade (PanIN3). We made the hypothesis that specific proteomic signatures from each precancerous stage exist and are detectable in plasma. METHODS: We explored the peptide profiles of microdissected PanIN cells and of plasma samples corresponding to the different PanIN grade from genetically engineered mouse models of PDAC using capillary electrophoresis coupled to mass spectrometry (CE-MS) and Chip-MS/MS. RESULTS: We successfully characterised differential peptides profiles from PanIN microdissected cells. We found that plasma from tumor-bearing mice and age-matched controls exhibit discriminative peptide signatures. We also determined plasma peptide signatures corresponding to low- and high-grade precancerous step present in the mice pancreas using the two mass spectrometry technologies. Importantly, we identified biomarkers specific of PanIN3. CONCLUSIONS: We demonstrate that benign and advanced PanIN lesions display distinct plasma peptide patterns. This strongly supports the perspectives of developing a non-invasive screening test for prediction and early detection of PDAC.

Chronic hyperinsulinemia does not increase the production rate of high-density lipoprotein apolipoprotein AI: evidence from a kinetic study in patients with insulinoma.

OBJECTIVE: In vitro studies showed that insulin stimulates the production of apolipoprotein AI (apoAI). Thus, we hypothesized that chronic hyperinsulinemia could contribute to the increase in the production of high-density lipoprotein apoAI that is observed in metabolic syndrome. APPROACH AND RESULTS: We performed an in vivo kinetic study with stable isotope in 7 patients with insulinoma who showed hyperinsulinemia but no insulin resistance, 8 patients with insulin resistance, and 16 controls. Insulinemia was 3.1× (P<0.01) higher in patients with insulinoma or insulin resistance than in controls in the fasting state and, respectively, 3.5× and 2.6× (P<0.05) higher in the fed state. The high-density lipoprotein apoAI pool size was smaller in patients with insulin resistance than in controls (49.3 ± 5.4 versus 59.6 ± 7.7 mg · kg(-1); P<0.01), whereas both the high-density lipoprotein apoAI fractional catabolic rate and the high-density lipoprotein apoAI production rate were higher (0.30 ± 0.07 versus 0.20 ± 0.04 pool · d(-1); P<0.0001 and 14.6 ± 1.5 versus 11.5 ± 1.9 mg · kg(-1) · d(-1); P<0.01, respectively). In contrast, no significant difference was observed for these parameters between patients with insulinoma and controls. In patients with insulinoma, the apoAI pool size tended to be greater than in patients with insulin resistance (56.3 ± 8.6 versus 49.3 ± 5.4 mg · kg(-1); P=0.078), whereas both the apoAI fractional catabolic rate and the production rate were lower (0.20 ± 0.06 versus 0.30 ± 0.07 pool · d(-1); P<0.01 and 11.1 ± 1.6 versus 14.6 ± 1.5 mg·kg(-1) · d(-1); P<0.01, respectively). The apoAI fractional catabolic rate was the only variable associated with the apoAI production rate in multivariate analysis and explained 80% of its variance. CONCLUSIONS: Chronic endogenous hyperinsulinemia does not induce any increase in the apoAI production rate, which seems to be more dependent on the apoAI fractional catabolic rate.

Curbing false discovery rates in interpretation of genome-wide expression profiles.

Fisher's exact test is widely used in biomedical research, particularly in genomic profile analysis. Since in most databases, the frequency distribution of genes is right skewed, we show here that its use can lead to excessive false-positive discoveries. We propose to apply Zelen's exact test on a stratification of the gene set; this solves the false discovery problem, and should avoid misleading interpretations of lists of genes produced by various genome-wide analysis technologies.

The PPARα pathway in Vγ9Vδ2 T cell anergy.

Phosphoantigens (PAgs) activate Vγ9Vδ2 T lymphocytes, inducing their potent and rapid response in vitro and in vivo. However, humans and nonhuman primates that receive repeated injections of PAgs progressively lose their Vγ9Vδ2 T cell response to them. To elucidate the molecular mechanisms of this in vivo desensitization, we analyzed the transcriptome of circulating Vγ9Vδ2 T cells from macaques injected with PAg. We showed that three PAg injections induced the activation of the PPARα pathway in Vγ9Vδ2 T cells. Thus, we analyzed the in vitro response of Vγ9Vδ2 T cells stimulated with a PPARα agonist. We demonstrated that in vitro PPARα pathway activation led to the inhibition of the BrHPP-induced activation and proliferation of human Vγ9Vδ2 T cells. Since the PPARα pathway is involved in the antigen-selective desensitization of human Vγ9Vδ2 T cells, the use of PPARα inhibitors could enhance cancer immunotherapy based on Vγ9Vδ2 T cells.

Cytidine Deaminase Resolves Replicative Stress and Protects Pancreatic Cancer from DNA-Targeting Drugs.

Cytidine deaminase (CDA) functions in the pyrimidine salvage pathway for DNA and RNA syntheses and has been shown to protect cancer cells from deoxycytidine-based chemotherapies. In this study, we observed that CDA was overexpressed in pancreatic adenocarcinoma from patients at baseline and was essential for experimental tumor growth. Mechanistic investigations revealed that CDA localized to replication forks where it increased replication speed, improved replication fork restart efficiency, reduced endogenous replication stress, minimized DNA breaks, and regulated genetic stability during DNA replication. In cellular pancreatic cancer models, high CDA expression correlated with resistance to DNA-damaging agents. Silencing CDA in patient-derived primary cultures in vitro and in orthotopic xenografts in vivo increased replication stress and sensitized pancreatic adenocarcinoma cells to oxaliplatin. This study sheds light on the role of CDA in pancreatic adenocarcinoma, offering insights into how this tumor type modulates replication stress. These findings suggest that CDA expression could potentially predict therapeutic efficacy and that targeting CDA induces intolerable levels of replication stress in cancer cells, particularly when combined with DNA-targeted therapies. SIGNIFICANCE: Cytidine deaminase reduces replication stress and regulates DNA replication to confer resistance to DNA-damaging drugs in pancreatic cancer, unveiling a molecular vulnerability that could enhance treatment response.

Characterization of the arabinogalactan protein 31 (AGP31) of Arabidopsis thaliana: new advances on the Hyp-O-glycosylation of the Pro-rich domain.

Proteins are important actors in plant cell walls because they contribute to their architecture and their dynamics. Among them, hydroxyproline (Hyp)-rich glycoproteins constitute a complex family of O-glycoproteins with various structures and functions. In this study, we characterized an atypical Hyp-rich glycoprotein, AGP31 (arabinogalactan protein 31), which displays a multidomain organization unique in Arabidopsis thaliana, consisting of a short arabinogalactan protein (AGP) motif, a His stretch, a Pro-rich domain, and a C-terminal PAC (PRP-AGP containing Cys) domain. The use of various mass spectrometry strategies was innovative and powerful: it permitted us to locate Hyp residues, to demonstrate the presence of carbohydrates, and to refine their distribution over the Pro-rich domain. Most Hyp were isolated within repeated motifs such as KAOV, KSOV, K(PO/OP)T, K(PO/OP)V, T(PO/OP)V, and Y(PO/OP)T. A few extensin-like motifs with contiguous Hyp (SOOA and SOOT) were also found. The Pro-rich domain was shown to carry Gal residues on isolated Hyp but also Ara residues. The existence of new type Hyp-O-Gal/Ara-rich motifs not recognized by the ß-glucosyl Yariv reagent but interacting with the peanut agglutinin lectin was proposed. In addition, the N-terminal short AGP motif was assumed to be substituted by arabinogalactans. Altogether, AGP31 was found to be highly heterogeneous in cell walls because arabinogalactans could be absent, Hyp-O-Gal/Ara-rich motifs of different sizes were observed, and truncated forms missing the C-terminal PAC domain were found, suggesting degradation in muro and/or partial glycosylation prior to secretion.

The gene expression profile of phosphoantigen-specific human γδ T lymphocytes is a blend of αß T-cell and NK-cell signatures.

Global transcriptional technologies have revolutionised the study of lymphoid cell populations, but human γδ T lymphocytes specific for phosphoantigens remain far less deeply characterised by these methods despite the great therapeutic potential of these cells. Here we analyse the transcriptome of circulating TCRVγ(+) γδ T cells isolated from healthy individuals, and their relation with those from other lymphoid cell subsets. We report that the gene signature of phosphoantigen-specific TCRVγ(+) γδ T cells is a hybrid of those from αß T and NK cells, with more 'NK-cell' genes than αß T cells have and more 'T-cell' genes than NK cells. The expression profile of TCRVγ(+) γδ T cells stimulated with phosphoantigen recapitulates their immediate physiological functions: Th1 cytokine, chemokine and cytotoxic activities reflect their high mitotic activity at later time points and do not indicate antigen-presenting functions. Finally, such hallmarks make the transcriptome of γδ T cells, whether resting or clonally expanding, clearly distinctive from that of NK/T or peripheral T-cell lymphomas of the γδ subtype.

The proteome and transcriptome of stress granules and P bodies during human T lymphocyte activation.

Stress granules (SGs) and processing bodies (PBs) are membraneless cytoplasmic assemblies regulating mRNAs under environmental stress such as viral infections, neurological disorders, or cancer. Upon antigen stimulation, T lymphocytes mediate their immune functions under regulatory mechanisms involving SGs and PBs. However, the impact of T cell activation on such complexes in terms of formation, constitution, and relationship remains unknown. Here, by combining proteomic, transcriptomic, and immunofluorescence approaches, we simultaneously characterized the SGs and PBs from primary human T lymphocytes pre and post stimulation. The identification of the proteomes and transcriptomes of SGs and PBs indicate an unanticipated molecular and functional complementarity. Notwithstanding, these granules keep distinct spatial organizations and abilities to interact with mRNAs. This comprehensive characterization of the RNP granule proteomic and transcriptomic landscapes provides a unique resource for future investigations on SGs and PBs in T lymphocytes.

Phosphoantigens overcome human TCRVgamma9+ gammadelta Cell immunosuppression by TGF-beta: relevance for cancer immunotherapy.

Human gammadelta cells expressing TCRVgamma9 are HLA-unrestricted CTLs with high relevance for cancer immunotherapy. Many tumor cell types produce TGF-beta, however, a cytokine strongly immunosuppressive for conventional T CD4, CD8, and NK cells. Whether TGF-beta also inhibits TCRVgamma9+ lymphocytes was unknown. Because phosphoantigens (PAgs), such as bromohydrin pyrophosphate, selectively activate the antitumor functions of TCRVgamma9+ T cells, in this study, we investigated whether TGF-beta modulates these functions. We report that TGF-beta does not block activation of TCRVgamma9+ T cells but inhibits their PAg/IL-2-induced proliferation and maturation into effector cells and finally reduces the cytotoxic activity of these gammadelta T cells when exposed to lymphoma target cells. TGF-beta did not bias their differentiation pattern toward gammadelta Th17 or gammadelta regulatory T cells. Nevertheless, increasing doses of PAg stimulus countered TGF-beta inhibition. So, although TGF-beta impairs TCRVgamma9+ gammadelta cells like other cytolytic lymphocytes, PAg alone or combined to therapeutic mAb has the ability to bypass its immunosuppressive activity.