Biology subjects

Salanga, C.

Publications and source records attributed to Salanga, C..

4 recordsLinked to original sources

bioRxiv2025

Exploiting the CXCR3/CXCL10 pathway to override tumor immune suppression by enhancing immune trafficking and effector cell priming in head and neck squamous cell carcinoma

The immune-suppressive nature of the tumor microenvironment (TME) has limited the impact of immune checkpoint blockade in many cancers, often by restricting the infiltration and activation of anti-tumoral CD8+ T, CD4+ T, and NK cells. Here, we utilized murine models of head and neck squamous cell carcinoma and demonstrated that intratumoral (IT) delivery of CXCL10 drives tumor elimination and inhibits recurrence. CD8+ T cells recruited to tumors display enhanced activation, increased tumor antigen specificity, and decreased markers of T cell exhaustion, indicating that CXCL10 not only directs cell migration, but also enhances T cell effector functions. Despite delivery of CXCL10 into tumors, CD8+ and CD4+ T cells also show enhanced presence and proliferation in tumor-draining lymph nodes (TdLNs), consistent with antigen presentation and trafficking of these cells between tumors and TdLNs. CXCL10 also stunts angiogenesis and lymphangiogenesis within the TME, which likely contributes to its antitumoral effects. Finally, enhanced tumor clearance was observed by combining IT CXCL10 and anti-PD-1. Together, these findings provide the rationale for the clinical evaluation of CXCL10 as a strategy to enhance the efficacy of immunotherapy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/650529v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@4d0f3borg.highwire.dtl.DTLVardef@122f4e6org.highwire.dtl.DTLVardef@1fc50a0org.highwire.dtl.DTLVardef@117a05_HPS_FORMAT_FIGEXP M_FIG C_FIG SUMMARYCXCL10 suppresses tumor growth and promotes immune memory by recruiting T and NK cells into the tumor microenvironment, promoting tumor-specific antigen recognition and effector functions, slowing T cell exhaustion, and inhibiting angiogenesis. CXCL10 directly and indirectly mobilizes an immune cell network that together supports an anti-tumoral microenvironment.

cancer biology↗

bioRxiv2023

Molecular determinants of antagonist interactions with chemokine receptors CCR2 and CCR5

By driving monocyte chemotaxis, the chemokine receptor CCR2 shapes inflammatory responses and the formation of tumor microenvironments. This makes it a promising target in inflammation and immuno-oncology; however, despite extensive efforts, there are no FDA-approved CCR2-targeting therapeutics. Cited challenges include the redundancy of the chemokine system, suboptimal properties of compound candidates, and species differences that confound the translation of results from animals to humans. Structure-based drug design can rationalize and accelerate the discovery and optimization of CCR2 antagonists to address these challenges. The prerequisites for such efforts include an atomic-level understanding of the molecular determinants of action of existing antagonists. In this study, using molecular docking and artificial-intelligence-powered compound library screening, we uncover the structural principles of small molecule antagonism and selectivity towards CCR2 and its sister receptor CCR5. CCR2 orthosteric inhibitors are shown to universally occupy an inactive-state-specific tunnel between receptor helices 1 and 7; we also discover an unexpected role for an extra-helical groove accessible through this tunnel, suggesting its potential as a new targetable interface for CCR2 and CCR5 modulation. By contrast, only shape complementarity and limited helix 8 hydrogen bonding govern the binding of various chemotypes of allosteric antagonists. CCR2 residues S1012.63 and V2446.36 are implicated as determinants of CCR2/CCR5 and human/mouse orthosteric and allosteric antagonist selectivity, respectively, and the role of S1012.63 is corroborated through experimental gain-of-function mutagenesis. We establish a critical role of induced fit in antagonist recognition, reveal strong chemotype selectivity of existing structures, and demonstrate the high predictive potential of a new deep-learning-based compound scoring function. Finally, this study expands the available CCR2 structural landscape with computationally generated chemotype-specific models well-suited for structure-based antagonist design.

pharmacology and toxicology↗

bioRxiv2023

Ligand-Dependent Mechanisms of C-C Chemokine Receptor 5 (CCR5) Trafficking Revealed by APEX2 Proximity Labeling Proteomics

CC chemokine receptor 5 (CCR5) promotes inflammatory responses by driving cell migration and scavenging chemokine to shape directional chemokine gradients. A CCR5 inhibitor has been approved for blocking HIV entry into cells. However, targeting CCR5 for the treatment of other diseases has had limited success, likely because of the complexity of CCR5 pharmacology and biology. CCR5 is activated by natural and engineered chemokines that elicit distinct signaling and trafficking responses, including receptor sequestration inside the cell. Intracellular sequestration may be therapeutically exploitable as a strategy for receptor inhibition, but the mechanisms by which different ligands promote receptor retention in the cell versus presence on the cell membrane are poorly understood. We employed live cell ascorbic acid peroxidase (APEX2) proximity labeling and quantitative mass spectrometry proteomics for unbiased discovery of temporally resolved protein neighborhoods of CCR5 following stimulation with its endogenous agonist, CCL5, and two CCL5 variants that promote intracellular retention of the receptor. Along with targeted pharmacological assays, the data reveal distinct ligand-dependent CCR5 trafficking patterns with temporal and spatial resolution. All three chemokines internalize CCR5 via {beta}-arrestin-dependent, clathrin-mediated endocytosis but to different extents, with different kinetics and varying dependencies on GPCR kinase subtypes. The agonists differ in their ability to target the receptor to lysosomes for degradation, as well as to the Golgi compartment and the trans-Golgi network, and these trafficking patterns translate into distinct levels of ligand scavenging. The results provide insight into the cellular mechanisms behind CCR5 intracellular sequestration and suggest how trafficking can be exploited for the development of functional antagonists of CCR5. Significance StatementCCR5 plays a crucial role in the immune system and is important in numerous physiological and pathological processes such as inflammation, cancer and transmission of HIV. It responds to different ligands with distinct signaling and trafficking behaviors; notably some ligands induce retention of the receptor inside the cell. Using time-resolved proximity labeling proteomics and targeted pharmacological experiments, this study reveals the cellular basis for receptor sequestration that can be exploited as a therapeutic strategy for inhibiting CCR5 function.

cell biology↗

bioRxiv2022

Chemokine CXCL4 interactions with extracellular matrix proteoglycans mediate wide-spread non-receptor mediated immune cell recruitment

Leukocyte recruitment from the vasculature into tissues is a crucial component of the immune system, but is also key to inflammatory disease. Chemokines are central to this process but have yet to be therapeutically targeted during inflammation, due to a lack of mechanistic understanding. Specifically, CXCL4 (PF4) has no established receptor that explains its function. Here we use biophysical, in vitro and in vivo techniques to determine the mechanism underlying CXCL4 mediated leukocyte recruitment. We demonstrate that CXCL4 binds to glycosaminoglycan (GAG) sugars within the endothelial extracellular matrix resulting in increased vascular permeability and non-specific recruitment of a range of leukocytes. Furthermore, GAG sulphation confers selectivity onto chemokine localisation. These findings represent a new understanding of chemokine biology, providing novel mechanisms for future therapeutic targeting. One sentence summaryCXCL4 binds to extracellular matrix proteoglycans resulting in increased vascular permeability and recruitment of a wide range of different leukocytes via a non-canonical mechanism.

immunology↗