Biology subjects

Porgador, A.

Publications and source records attributed to Porgador, A..

9 recordsLinked to original sources

bioRxiv2026

Spatially enforced engagement of PD-1⁺ T cells with AXL⁺ cells reprograms the tumor microenvironment and overcomes anti-PD-1 resistance

Background: AXL overexpression promotes tumor-cell plasticity, local immune suppression, and resistance to PD-1 blockade. Conventional anti-AXL and anti-PD-1 antibodies combinations act independently and do not ensure physical proximity between PD-1+ T cells and AXL+ cells within the immunosuppressive tumor microenvironment. Methods: To address this limitation, we developed a non-tandem, tetravalent IgG bispecific antibody designed to simultaneously engage PD-1 and AXL (BiTE-AXL/PD-1). Its antitumor activity was evaluated using in vitro functional assays and humanized and immunocompetent head and neck squamous cell carcinoma (HNSCC) models and compared with the combination of monospecific anti-AXL and anti-PD-1 antibodies. Spatial multiplex imaging was used to characterize treatment-associated changes in the tumor microenvironment of an anti-PD-1-resistant murine model. Results: BiTE-AXL/PD-1 enhanced T-cell activation, promoted AXL-dependent tumor-T-cell conjugation, and increased tumor-cell killing in vitro, outperforming the combination of the two monospecific antibodies. In humanized and immunocompetent HNSCC models, BiTE treatment significantly delayed tumor growth compared with the antibody combination and was well tolerated, with no overt toxicity. Spatial multiplex imaging revealed a shift from a fibroblast-dominated microenvironment characterized by exhausted CD8+ T cells toward dendritic-cell- and CD8+ T-cell-enriched niches associated with antitumor immune activity. Conclusion: BiTE-AXL/PD-1 promotes physical proximity between PD-1+ T cells and AXL+ cells, enhances antitumor immune responses, and remodels the immunosuppressive tumor microenvironment. These findings support PD-1/AXL bispecific targeting as a promising therapeutic strategy to overcome resistance to PD-1 blockade in HNSCC.

cancer biology↗

bioRxiv2026

β-endorphin primes NK cells and NK-derived Extracellular Vesicle to enhance anti-tumor cytotoxicity

Psychoneuroimmunology suggests that positive physiological states, including laughter, could affect anti-tumor immunity, but the underlying mechanisms remain unclear. Here, we investigated whether {beta}-endorphin (BE), an endogenous opioid peptide associated with positive physiological stimuli, modulates Natural Killer (NK) cell cytotoxicity and the anti-tumor activity of NK-derived extracellular vesicles (EVs). Using NK-92 cells, we assessed cytotoxicity against JIMT1 breast cancer cells, CD107a mobilization, cytotoxic activity of conditioned medium (CM), and EV yield, cargo, and function. BE enhanced NK-92-mediated killing of JIMT1 cells without increasing CD107a mobilization, suggesting that improved cytotoxicity was not driven by classical degranulation. Consistently, CM from BE-treated NK cells retained contact-independent cytotoxicity. NK-EVs were enriched in granzyme B and perforin following BE treatment exhibiting enhanced cytotoxicity against JIMT1 and BW tumor cells. BE also increased the cytotoxic activity of primary human NK cells, and BE-conditioned NK-EVs primed naive NK-92 cells for enhanced tumor killing. These findings indicate that BE enhances NK anti-tumor immunity by remodeling the cytotoxic secretome and generating EVs that act as both direct cytotoxic effectors and mediators of NK cell priming. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=119 HEIGHT=200 SRC="FIGDIR/small/741417v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1c1dfc5org.highwire.dtl.DTLVardef@14a190eorg.highwire.dtl.DTLVardef@1b32665org.highwire.dtl.DTLVardef@9db6e3_HPS_FORMAT_FIGEXP M_FIG C_FIG Proposed neuroendocrine-immune model linking positive physiological stimuli, NK cell-derived extracellular vesicles (EVs), and anti-tumor activity. Laughter is depicted as a conceptual upstream trigger of hypothalamic-pituitary signaling leading to {beta}-endorphin (BE) release. BE conditioning enhanced NK-92 cytotoxicity and the anti-tumor activity of NK-derived EVs, consistent with granzyme B and perforin enrichment and supporting EV-mediated contact-independent cancer cell killing.

cancer biology↗

bioRxiv2025

OptiRanker: an Advanced Tool for Simulation and Comparative Analysis of Drug Prioritization Algorithms in in-Vivo Trials

A critical challenge in personalized medicine is identifying the optimal drug treatment for individual patients based on their unique biological profiles. While recent advancements have led to a surge in drug prioritization algorithms utilizing patient omics data, including regression, classification, multiple kernel learning, deep learning, and AI-based methods, objective validation remains essential to discern their effectiveness. This study introduces" OptiRanker," an innovative statistical framework designed to simulate and optimize the in vivo validation of these drug prioritization algorithms by ranking their predictive accuracy across varied conditions. OptiRanker not only mimics algorithmic predictions but also integrates them into ranked datasets, enabling the optimal selection of test subjects and drugs for trial setups. By providing a rigorous evaluation subset for ranking and comparison of high- and low-performing algorithms, OptiRanker facilitates the design of cost-effective in vivo trials tailored to efficiently assess predictive capability. This addresses a key bottleneck in personalized medicine: achieving a robust, scalable validation of computational models that can accelerate the clinical translation of promising algorithms. The efficient ranking provided by OptiRanker has the potential to advance personalized treatment strategies, ultimately leading to more effective, individualized patient care. The Python code for OptiRanker is available at the following GitHub repository: https://github.com/OhadLandau/OptiRanker.

bioinformatics↗

bioRxiv2024

Deciphering the role of the nanoscale clustering of activating and costimulatory antibodies on T cell activation

In a joint experimental and a modeling effort, we explored the regulation of T cell activation and cytotoxicity by the nanoscale clustering and surface density of activating and costimulatory antibodies. Specifically, we simulated T cells on nanolithographically patterned arrays of clusters of these antibodies, systematically varying the cluster size from intermediate to large and overall antibody density. We found that T-cell activation correlated more with global antibody density than with cluster size, such that at low density arrays were inefficient in activation, while high density arrays saturated the signal. However, when T-cells were exposed to patterns of low global densities but small, very dense clusters, full activation of T cells was achieved. These results could be rationalized using the membrane-fluctuation-model that integrates the cooperative effects between bonds with mechanical feedback from the cell activation. This insight into the spatial organization of activating ligands provides an important understanding of the mechanism of T cell activation and allows for the design of more effective T cell activation platforms for immunotherapy.

immunology↗

bioRxiv2024

Effect of the Environmental Mechanical Heterogeneity on T Cell Function

T cells, key players in the immune system, recognize antigens via T-cell receptors (TCRs) and require additional costimulatory and cytokine signals for full activation. Beyond biochemical signals, T cells also respond to mechanical cues such as tissue stiffness. Traditional ex-vivo mechanostimulating platforms, however, present a uniform mechanical environment, unlike the heterogeneous conditions T cells encounter in-vivo. This work introduces a novel mechanically heterogeneous environment, with alternating soft and stiff microdomains, to mimic the complex mechanical signals T cells face. Results show that T cells exposed to this heterogeneous environment do not average the mechanical signals but instead respond similarly to those on a homogeneously soft surface, leading to lower activation compared to those on a stiff surface. Interestingly, long-term exposure to these patterns enhances the proliferation of central memory and effector T cell phenotypes, similar to stiff environments. These findings reveal the non-linear nature of T cell mechanosensing and suggest that mechanical heterogeneity plays a critical role in modulating T cell responses, providing new insights into T cell activation and potential implications for immunotherapies.

immunology↗

bioRxiv2023

Functional binding of PD1 ligands predicts response to anti-PD1 treatment in cancer patients

Accurate predictive biomarkers of response to immune checkpoint inhibitors (ICIs) are required for better stratifying cancer patients to ICI treatments. Here, we present a new concept for a bioassay to predict the response to anti-PD1 therapies, which is based on measuring the binding functionality of PDL1 and PDL2 to their receptor, PD1. In detail, we developed a cell-based reporting system, called the Immuno-checkpoint Artificial Reporter with overexpression of PD1 (IcAR-PD1) and evaluated the PDL1 and PDL2 binding functionality in tumor cell lines, patient-derived xenografts, and in fixed-tissue tumor samples obtained from cancer patients. In a retrospective clinical study, we found that the functionality of PDL1 and PDL2 predicts response to anti-PD1, and functionality of PDL1 binding is a more effective predictor than PDL1 protein expression alone. Our findings suggest that assessing the functionality of ligand binding is superior to staining of protein expression for predicting response to ICIs. TeaserPositive clinical response of cancer patients to anti-PD1 therapy can be predicted by measuring the binding activity of PDL1 and PDL2.

immunology↗

bioRxiv2021

Fc-independent neutralization of SARS-CoV-2 by recombinant human monoclonal antibodies

The use of passively-administered neutralizing antibodies is a promising approach for the prevention and treatment of SARS-CoV-2 infection. Antibody-mediated protection may involve immune system recruitment through Fc-dependent activation of effector cells and the complement system. However, the role of Fc-mediated functions in the efficacious in vivo neutralization of SARS-CoV-2 is not yet clear. Delineating the role this process plays in antibody-mediated protection will have a great impact on the design of such therapeutics. Here, the Fc of two highly potent SARS-CoV-2 neutralizing human monoclonal antibodies, targeting distinct domains of the spike, was engineered to abrogate their Fc-dependent functions. The protective activity of these antibodies was tested against lethal SARS-CoV-2 infections in K18-hACE2 transgenic mice, both before or two days post-exposure in comparison to their original, Fc-active antibodies. Antibody treatment with both Fc-variants similarly rescued the mice from death, reduced viral load and prevented signs of morbidity. In addition, surviving animals developed a significant endogenous immune response towards the virus. Taken together, this work provides important insight regarding the contribution of Fc-effector functions in antibody-mediated protection, which should aid in future design of effective antibody-based therapies.

immunology↗

bioRxiv2020

Molecular Scale Spatio-Chemical Control of the Activating-Inhibitory Signal Integration in NK Cells

The role of the spatial juxtaposition between activating and inhibitory receptors in cytotoxic lymphocytes has been strongly debated in the context of the inhibition of immune signaling. The challenge in addressing this problem was so far a lack of experimental tools which can simultaneously manipulate different signaling molecules. Here, we circumvent this challenge by introducing a nanoengineered multifunctional cell niche, in which activating and inhibitory ligands are positioned with molecular-scale variability and control, and applied it to elucidate the role of the spatial juxtaposition between ligands for NKG2D and KIR2DL1 - activating and inhibitory receptors in Natural Killer (NK) cells - in KIR2DL1-mediated inhibition of NKG2D signaling. We realized the niche by a nanopatterning of nanodots of different metals with molecular scale registry in one lithographic step, followed by a novel ternary functionalization of the fabricated bi-metallic pattern and its background to with three distinct biochemical moieties. We found, that within the probed range, the 40 nm gap between the activating and inhibitory ligands provided an optimal inhibition condition. Supported by theoretical modeling and simulations we interpret these findings as a consequence of the size and conformational flexibility of the ligands in their spatial interaction. Our findings provide an important insight onto the spatial mechanism of the inhibitory immune checkpoints, whose understanding is both fundamentally important, and essential for the rational design of future immunotherapies. Furthermore, our approach is highly versatile and paves the way to numerous complex molecular platforms aimed at revealing molecular mechanisms through which receptors integrate their signals.

immunology↗

bioRxiv2020

Mechanical Regulation of the Cytotoxic Activity of Natural Killer Cells

Mechanosensing has been recently explored for T cells and B cells and is believed to be part of their activation mechanism. Here, we explore the mechanosensing of the third type of lymphocytes - Natural Killer (NK) cells, by showing that they modulate their immune activity in response to changes in the stiffness of a stimulating surface. Interestingly, we found that this immune response is bell-shaped, and peaks for a stiffness of a few hundreds of kPa. This bell-shape behavior was observed only for surfaces functionalized with the activating ligand MHC class I polypeptide-related sequence A (MICA), but not for control surfaces lacking immunoactive functionalities. We found that stiffness does not affect uniformly all cells but increases the size of a little group of extra-active cells, which in turn contribute to the overall activation effect of the entire cell population. We further imaged the clustering of costimulatory adapter protein DAP10 on NK cell membrane and found that it shows the same bell -shape dependence to surface stiffness. Based on these findings, we propose a catch-bond-based model for the mechanoregulation of NK cell cytotoxic activity, through interaction of NKG2D activating receptors with MICA. Our findings reveal what seems to be "the tip of iceberg" of mechanosensation of NK cells, and provides an important insight on the mechanism of their immune signaling. Statement of SignificanceThe mechanical sensing of immune lymphocytes was recently demonstrated for T cells and B cells, but not for the third type of lymphocytes - Natural Killer (NK) cells. Interestingly, previous reports on lymphocyte mechanosensing were controversial, and showed either positive or negative changes in their immune activity with environmental stiffness, depending on the stiffness range. In this paper, we directly demonstrated that NK cells modulate their response with the stiffness of the stimulating surface, and this modulation has a bell-shape trend. We found that there is a strong correlation between the response to stiffness and clustering of adaptor proteins. Upon this correlation, we proposed a mechanosensing model based on the catch-bond nature of activating ligand-receptor complexes in NK cells.

immunology↗