CXCR3 Ligands Research Articles

CXCR3-expressing myeloid cells recruited to the hypothalamus protect against diet-induced body mass gain and metabolic dysfunction.

Microgliosis plays a critical role in diet-induced hypothalamic inflammation. A few hours after a high-fat diet (HFD), hypothalamic microglia shift to an inflammatory phenotype, and prolonged fat consumption leads to the recruitment of bone marrow-derived cells to the hypothalamus. However, the transcriptional signatures and functions of these cells remain unclear. Using dual-reporter mice, this study reveals that CX3CR1-positive microglia exhibit minimal changes in response to a HFD, while significant transcriptional differences emerge between microglia and CCR2-positive recruited myeloid cells, particularly affecting chemotaxis. These recruited cells also show sex-specific transcriptional differences impacting neurodegeneration and thermogenesis. The chemokine receptor CXCR3 is emphasized for its role in chemotaxis, displaying notable differences between recruited cells and resident microglia, requiring further investigation. Central immunoneutralization of CXCL10, a ligand for CXCR3, resulted in increased body mass and decreased energy expenditure, especially in females. Systemic chemical inhibition of CXCR3 led to significant metabolic changes, including increased body mass, reduced energy expenditure, elevated blood leptin, glucose intolerance, and decreased insulin levels. This study elucidates the transcriptional differences between hypothalamic microglia and CCR2-positive recruited myeloid cells in diet-induced inflammation and identifies CXCR3-expressing recruited immune cells as protective in metabolic outcomes linked to HFD consumption, establishing a new concept in obesity-related hypothalamic inflammation.

CXCR3-expressing myeloid cells recruited to the hypothalamus protect against diet-induced body mass gain and metabolic dysfunction

Microgliosis plays a critical role in diet-induced hypothalamic inflammation. A few hours after a high-fat diet (HFD), hypothalamic microglia shift to an inflammatory phenotype, and prolonged fat consumption leads to the recruitment of bone marrow-derived cells to the hypothalamus. However, the transcriptional signatures and functions of these cells remain unclear. Using dual-reporter mice, this study reveals that CX3CR1-positive microglia exhibit minimal changes in response to a HFD, while significant transcriptional differences emerge between microglia and CCR2-positive recruited myeloid cells, particularly affecting chemotaxis. These recruited cells also show sex-specific transcriptional differences impacting neurodegeneration and thermogenesis. The chemokine receptor CXCR3 is emphasized for its role in chemotaxis, displaying notable differences between recruited cells and resident microglia, requiring further investigation. Central immunoneutralization of CXCL10, a ligand for CXCR3, resulted in increased body mass and decreased energy expenditure, especially in females. Systemic chemical inhibition of CXCR3 led to significant metabolic changes, including increased body mass, reduced energy expenditure, elevated blood leptin, glucose intolerance, and decreased insulin levels. This study elucidates the transcriptional differences between hypothalamic microglia and CCR2-positive recruited myeloid cells in diet-induced inflammation and identifies CXCR3-expressing recruited immune cells as protective in metabolic outcomes linked to HFD consumption, establishing a new concept in obesity-related hypothalamic inflammation.

CCR8/CCL1 and CXCR3/CXCL10 axis mediated memory T cell activations in recalcitrant drug-induced hypersensitivity patients.

As a drug-induced hypersensitivity syndrome, drug reaction with eosinophilia and systemic symptoms (DRESS) is potentially fatal. Most patients with DRESS recover within a few weeks; however, some patients may suffer from a prolonged disease course and develop autoimmune sequelae. We investigated the immune mechanism and therapeutic targets of patients with recalcitrant DRESS with a prolonged disease course. A total of 32 patients with recalcitrant DRESS with a prolonged treatment course ≥8 weeks, 28 patients with short-duration DRESS with a treatment course <2 weeks, and 26 healthy individuals were enrolled in the study for analysis. Bulk transcriptome results demonstrated that mRNA expression levels of CCR8 and CXCR3 were significantly increased in the blood samples from patients in the acute stage of prolonged DRESS (adjusted p-values: CCR8=1.50×10-9 and CXCR3=2.60×10-4, respectively, for comparison of patients with prolonged DRESS to the healthy donor group). Serum and skin lesional concentrations of CCL1 and CXCL10, as the ligands of CCR8 and CXCR3, respectively, were significantly elevated in patients with prolonged DRESS as compared to those patients with short-duration DRESS. The results from high-parameter flow cytometry and autoantibody screening also identified significant escalations of CD8+ GNLY+CXCR3+effector memory T cells, CD8+central memory T cells, CD4+CCR8+Th2 cells, and IgG-anti-HES6 autoantibodies in patients with prolonged DRESS. Furthermore, in vitro blocking assays revealed that JAK inhibitors (mainly tofacitinib and upadacitinib) significantly decreased the release of CCL1 and CXCL10, and some patients with prolonged DRESS were successfully treated with JAK inhibitors. JAK inhibitors (tofacitinib and upadacitinib) were associated with decreased concentrations of CCL1 and CXCL10, suggesting that they may attenuate CCR8/CCL1- and CXCR3/CXCL10-axis-mediated memory T cell activation, which contribute to disease pathogenesis for patients with recalcitrant DRESS and a long-term treatment course.

Blood immune profiles reveal a CXCR3/CCR5 axis of dysregulation in early sepsis

Abstract We report on a pilot study exploring whether blood immune signatures can reveal early specific indicator profiles for patients meeting sepsis criteria upon hospital admission. We analysed samples of sepsis-suspected patients (N=20) and age-spanning healthy controls (N=12), using flow cytometry-based assays. We measured inflammatory markers from plasma fractions, and immunophenotyped freshly isolated unfixed PBMCs for leukocytes subsets representation and expression of activation markers, including chemokine receptors. We found that beside IL-6 and sCD14, CXCR3 ligands (CXCL9 and CXCL10) separated sepsis-suspected patients from healthy controls. The abundance of CD4+ T cells was significantly reduced in patients, while they displayed substantial losses of CCR5-expressing monocytes and CXCR3/CCR5 double positive T cells. Post-hoc subgrouping of patients according to their sepsis diagnosis on discharge, identified CXCR3/CCR5 double expression on T cells as a separating characteristic for confirmed cases. This work suggests a potential novel axis of dysregulation affecting CXCR3 and CCR5 in early sepsis.

Cytotoxic T cells drive doxorubicin-induced cardiac fibrosis and systolic dysfunction.

Doxorubicin, the most prescribed chemotherapeutic drug, causes dose-dependent cardiotoxicity and heart failure. However, our understanding of the immune response elicited by doxorubicin is limited. Here we show that an aberrant CD8+ T cell immune response following doxorubicin-induced cardiac injury drives adverse remodeling and cardiomyopathy. Doxorubicin treatment in non-tumor-bearing mice increased circulating and cardiac IFNγ+CD8+ T cells and activated effector CD8+ T cells in lymphoid tissues. Moreover, doxorubicin promoted cardiac CD8+ T cell infiltration and depletion of CD8+ T cells in doxorubicin-treated mice decreased cardiac fibrosis and improved systolic function. Doxorubicin treatment induced ICAM-1 expression by cardiac fibroblasts resulting in enhanced CD8+ T cell adhesion and transformation, contact-dependent CD8+ degranulation and release of granzyme B. Canine lymphoma patients and human patients with hematopoietic malignancies showed increased circulating CD8+ T cells after doxorubicin treatment. In human cancer patients, T cells expressed IFNγ and CXCR3, and plasma levels of the CXCR3 ligands CXCL9 and CXCL10 correlated with decreased systolic function.

Emodin suppresses mast cell migration via modulating the JAK2/STAT3/JMJD3/CXCR3 signaling to prevent cystitis.

This study aimed to determine the preventive effects of emodin on cyclophosphamide (CYP)-induced cystitis and to explore the molecular mechanism. In vivo, mice were modeled by CYP. Before a half hour of CYP treatment, Jumonji domain-containing protein-3 (JMJD3)inhibitors (GSK-J4) and emodin were used to treat CYP model mice. Bladder samples were stained for hematoxylin-eosin and toluidine blue. Next, JMJD3 was quantified by immunofluorescence staining, RT-PCR, and Western blot. CXCR3 was quantified by Western blot and ELISA. In vitro, before stimulated by lipopolysaccharide (LPS), human bladder smooth muscle cells (hBSMCs) were transfected with pcDNA3.1-JMJD3 plasmids, shRNA-JMJD3 plasmids or pretreated with emodin. Collected cells to detect JMJD3 and CXCR3 ligands again; collected supernatant of culture for Transwell assay. Finally, as the JAK2 inhibitor, AG490 was used to pretreat LPS-induced hBSMCs. Western blot was performed to quantify proteins. Emodin inhibited mast cell migration and suppressed the expression of JMJD3, CXCR3, and CXCR3 ligands, not only in vivo but also in vitro. The pharmacological effects of emodin were similar to GSK-J4 or JMJD3 inhibition. In addition, emodin significantly downregulated the phosphorylation of JAK2 and STAT3, and inhibited JMJD3/CXCR3 axis transduction like AG490. Emodin has a preventive effect on cystitis by inhibiting mast cell migration through inhibition of the JAK2/STAT3/JMJD3/CXCR3 signaling pathway.

HGG-49. INTERNEURONS THAT BITE: A CELLULAR DELIVERY SYSTEM FOR PEDIATRIC HIGH-GRADE GLIOMA

Abstract BACKGROUND High-grade gliomas (HGG) represent the leading cause of cancer-related mortality in children due to a lack of curative therapies. Challenges of cellular therapies in brain tumors include the lack of unique tumor antigens, downregulation of targeted antigens, and immune suppressive tumor microenvironment. To circumvent these obstacles, we devised a cellular delivery system using post-mitotic migratory cortical inhibitory interneuron precursors (MCIPs) to deliver therapeutic payloads in an antigen-independent manner. Notably, HGGs secrete the same chemoattractants stimulating long-distance MCIP migration as during normal fetal development, leading to the hypothesis that MCIPs would preferentially migrate to HGG cells. METHODS MCIP to HGG cell migration was assessed in vitro using transwell migration assays, and in vivo via stereotactic injection of MCIP and glioma xenografts in nude mice. As proof of principle, MCIPs were equipped with an EGFR or CD19 control bispecific T-cell engager (BiTE) which activates T-cells upon their linkage to the tumor cells resulting in glioma elimination. Equipped MCIPs were co-cultured with HGG cells and CD8 T-cells at an effector to target ratio of 4:1. Results were validated in vivo via xenografts of HGG, MCIPs, and either a single dose of CD8 T-cells or repeated T-cell dosing via intraventricular cannula. Survival was evaluated via Kaplan-Meier curves. RESULTS MCIPs migrated preferentially to the majority of HGG cell lines in vitro and in vivo. This migration was mediated, at least in part, via CXCR4 ligands. MCIPs secreting an EGFR-BiTE potently killed HGG cells in vitro versus CD19-BiTE controls. Furthermore, nude mice xenografted with HGG and EGFR-expressing MCIPs experienced prolonged survival versus controls. CONCLUSION These data suggest that MCIPs form a viable cellular delivery system and can be equipped with various agents targeting HGG. Modified MCIPs could be differentiated from induced pluripotent stem cells and injected into the resection cavity margins to eliminate residual cells.

Chemokines and Cytokines in Immunotherapy of Melanoma and Other Tumors: From Biomarkers to Therapeutic Targets.

Chemokines and cytokines represent an emerging field of immunotherapy research. They are responsible for the crosstalk and chemoattraction of immune cells and tumor cells. For instance, CXCL9/10/11 chemoattract effector CD8+ T cells to the tumor microenvironment, making an argument for their promising role as biomarkers for a favorable outcome. The cytokine Interleukin-15 (IL-15) can promote the chemokine expression of CXCR3 ligands but also XCL1, contributing to an important DC-T cell interaction. Recruited cytotoxic T cells can be clonally expanded by IL-2. Delivering or inducing these chemokines and cytokines can result in tumor shrinkage and might synergize with immune checkpoint inhibition. In addition, blocking specific chemokine and cytokine receptors such as CCR2, CCR4 or Il-6R can reduce the recruitment of tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs) or regulatory T cells (Tregs). Efforts to target these chemokines and cytokines have the potential to personalize cancer immunotherapy further and address patients that are not yet responsive because of immune cell exclusion. Targeting cytokines such as IL-6 and IL-15 is currently being evaluated in clinical trials in combination with immune checkpoint-blocking antibodies for the treatment of metastatic melanoma. The improved overall survival of melanoma patients might outweigh potential risks such as autoimmunity. However, off-target toxicity needs to be elucidated.

Targeting CXCR4 impaired T regulatory function through PTEN in renal cancer patients

BackgroundTregs trafficking is controlled by CXCR4. In Renal Cell Carcinoma (RCC), the effect of the new CXCR4 antagonist, R54, was explored in peripheral blood (PB)-Tregs isolated from primary RCC patients.MethodsPB-Tregs were isolated from 77 RCC patients and 38 healthy donors (HDs). CFSE-T effector-Tregs suppression assay, IL-35, IFN-γ, IL-10, TGF-β1 secretion, and Nrp-1+Tregs frequency were evaluated. Tregs were characterised for CTLA-4, PD-1, CD40L, PTEN, CD25, TGF-β1, FOXP3, DNMT1 transcriptional profile. PTEN-pAKT signalling was evaluated in the presence of R54 and/or triciribine (TCB), an AKT inhibitor. Methylation of TSDR (Treg-Specific-Demethylated-Region) was conducted.ResultsR54 impaired PB-RCC-Tregs function, reduced Nrp-1+Tregs frequency, the release of IL-35, IL-10, and TGF-β1, while increased IFN-γ Teff-secretion. The CXCR4 ligand, CXCL12, recruited CD25+PTEN+Tregs in RCC while R54 significantly reduced it. IL-2/PMA activates Tregs reducing pAKT+Tregs while R54 increases it. The AKT inhibitor, TCB, prevented the increase in pAKT+Tregs R54-mediated. Moreover, R54 significantly reduced FOXP3-TSDR demethylation with DNMT1 and FOXP3 downregulation.ConclusionR54 impairs Tregs function in primary RCC patients targeting PTEN/PI3K/AKT pathway, reducing TSDR demethylation and FOXP3 and DNMT1 expression. Thus, CXCR4 targeting is a strategy to inhibit Tregs activity in the RCC tumour microenvironment.

Abstract 722: A cancer-associated fibroblast model to discover mechanisms of growth, survival, and treatment sensitivity in PAX3/7-FKHR fusion-positive alveolar rhabdomyosarcoma

Abstract Introduction: Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma. Among various subtypes, alveolar RMS (ARMS) is generally more aggressive and usually carries the fusion transcription factor, PAX3/7-FKHR. High-risk ARMS has an extremely poor prognosis, with ~25% five-year survival. Hence, novel therapeutic approaches are urgently needed. However, potential therapies are often hindered by the immunosuppressive tumor microenvironment (TME) associated with sarcomas. The TME is highly dynamic and includes fibroblasts, immune cells, and extracellular matrix. Cancer-associated fibroblasts (CAFs) may promote tumor growth and survival by secreting distinct factors to regulate proliferation, metastasis, and resistance to therapy. In this study, we investigated mechanisms involved in this phenomenon and identified a novel therapeutic strategy targeting the TME of ARMS. Methods: Cells were isolated from a PAX3-FKHR fusion-positive ARMS tumor specimen, following ethics approval and informed consent. The PAX3-FKHR fusion status and mesenchymal biomarkers were analyzed by immunoblotting. The patient’s CAFs (designated KCCF14), RMS lines (RD, RH30, RH41), and control fibroblasts (BJ, HS68, WI-38) were cultured in vitro and their respective supernatant media was harvested for subsequent experiments. Cell proliferation and viability were determined by hemocytometer and alamar blue assay, respectively. The scratch wound healing assay was used to assess cell migration. Cytokine analysis was performed with a 96-plex array. For drug screening, cells were treated with a panel of CXCR4 antagonists to generate dose-response curves. Results: KCCF14 CAFs isolated from an ARMS tumor exhibit elongated spindle morphology and are positive for mesenchymal biomarkers, including PDGFR-β and smooth muscle α-actin. As expected, these cells lack characteristics of the patient’s tumor, notably the expression of PAX3-FKHR fusion and N-myc. KCCF14-conditioned media significantly enhances ARMS cell proliferation and migration in a concentration-dependent manner. Analysis of the conditioned media revealed upregulation of key growth factors and cytokines, including PDGF-AA, VEGF-A, MCP-1, and IL-11, that promote tumor aggressiveness through proliferative signaling, angiogenesis, activation of migration, and immune evasion. Because SDF-1 (CXCR4 ligand) was also increased, we tested targeted inhibition of CXCR4, which induced cytotoxicity with increased sensitivity (IC50 = 0.5 µM) in KCCF14 cells compared to control fibroblasts. Conclusions: This study provides, for the first time, findings from a continuously growing CAF model system for RMS. Our data describes key tumor growth and survival mechanisms supported by the TME and establishes a method to identify treatments with novel therapeutic strategies. Citation Format: Patrick Sipila, Son Tran, Chunfen Zhang, Anne–Marie Langevin, Aru Narendran. A cancer-associated fibroblast model to discover mechanisms of growth, survival, and treatment sensitivity in PAX3/7-FKHR fusion-positive alveolar rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 722.

Abstract 3749: The evaluation of expression level of Cxcl12 gene in peripheral blood samples of breast cancer patients

Abstract Breast cancer, like many other cancer types, is linked to the activation and overexpression of CXCR4. The overexpression of CXCR4 is associated with factors such as tumor growth, angiogenesis, increased metastasis, and therapeutic resistance. Similarly, CXCL12, a specific ligand for CXCR4, plays a significant role in tumorigenesis processes, including survival, migration, and microenvironmental interactions. The CXCL12/CXCR4 signaling pathway has been found to impact the development and progression of breast cancer, regulating proliferation, motility, and metastasis. Hence, molecules within the CXCL12/CXCR4 signaling pathway hold promise for determining breast cancer prognosis, treatment monitoring, and serving as therapeutic agents. The study, conducted at the Istanbul University Institute of Oncology, obtained ethical approval from the Istanbul Faculty of Medicine Ethics Committee. Genetic materials from 300 breast cancer patients and 150 control subjects underwent standard testing, matched based on crucial parameters. Real-time PCR with the MIC qPCR Cycler was statistically analyzed using GraphPad Prism (p &amp;lt; 0.05). Descriptive statistics were presented for categorical and quantitative variables, while the Kolmogorov-Smirnov test assessed the normal distribution of quantitative variables. Statistical comparisons between groups were performed using the Mann-Whitney U test and the Kruskal-Wallis test. was used for calculations. Notably, among the three genes—LASP1, CXCL12, and CXCR4—LASP1 exhibited the highest mean expression level at 11.64 with a considerable standard deviation of 11.80. In contrast, CXCL12 had a much lower mean expression level at 2.96 and a tighter distribution, and CXCR4 displayed the lowest mean expression level at 0.37 with a standard deviation of 0.74. The analysis of diagnostic groups indicated no significant differences in mean LASP1 and CXCL12 levels, but a significant variance in mean CXCR4 levels (p&amp;lt;0.001). Specifically, CXCR4 expression in group Breast and ovarian cancer was notably lower compared to Breast cancer, Bilateral Breast cancer, and Breast and Other cancer, while group Breast cancer exhibited significantly lower CXCR4 expression compared to groups Bilateral Breast cancer and Breast and Other cancer. However, there was no significant difference in CXCR4 expression between groups of Bilateral Breast cancer and Breast and Other cancer. These findings reveal distinct expression patterns of CXCR4 across diagnostic groups, suggesting potential implications for diagnostic categorization and underlying molecular pathways in breast cancer. Understanding these expression disparities could be crucial in deciphering the molecular intricacies influencing disease progression and treatment responses. Citation Format: Arash Adamnejad Ghafour, Seref Bugra Tuncer. The evaluation of expression level of Cxcl12 gene in peripheral blood samples of breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3749.

Circulating exosome long non-coding RNAs are associated with atrial structural remodeling by increasing systemic inflammation in atrial fibrillation patients.

Atrial fibrillation (AF) is the most common cardiac arrhythmia with severe clinical sequelae, but its genetic characteristic implicated in pathogenesis has not been completely clarified. Accumulating evidence has indicated that circulating exosomes and their carried cargoes, such as long non-coding RNAs (lncRNAs), involve in the progress of multiple cardiovascular diseases. However, their potential role as clinical biomarkers in AF diagnosis and prognosis remains unknown. Herein, we conducted the sequence and bioinformatic analysis of circulating exosomes harvested from AF and sinus rhythm patients. A total of 53 differentially expressed lncRNAs were identified, and a total of 6 significantly changed lncRNAs (fold change > 2.0), including NR0046235, NR003045, NONHSAT167247.1, NONHSAT202361.1, NONHSAT205820.1 and NONHSAT200958.1, were verified by qRT-PCR in 215 participants. Moreover, these circulating exosome lncRNA levels were different between paroxysmal and persistent AF patients, which were dramatically associated with abnormal hemodynamics and atrial diameter. Furthermore, we observed that the area under ROC curve (AUC) of six lncRNAs combination for diagnosis of persistent AF was 80.34%. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment pathway analysis indicated these exosome lncRNAs mainly concerning response to chemokine-chemokine receptor interaction, which induced activated inflammation and structural remodeling. In addition, increased plasma levels of CXCR3 ligands, including CXCL4, CXCL9, CXCL10 and CXCL11, were accumulated in AF patient tissues. Our study provides the transcriptome profile revealing pattern of circulating exosome lncRNAs in atrial structural remodeling, which bring valuable insights into improving prognosis and therapeutic targets for AF.

CXCL17 is an allosteric inhibitor of CXCR4 through a mechanism of action involving glycosaminoglycans.

CXCL17 is a chemokine principally expressed by mucosal tissues, where it facilitates chemotaxis of monocytes, dendritic cells, and macrophages and has antimicrobial properties. CXCL17 is also implicated in the pathology of inflammatory disorders and progression of several cancers, and its expression is increased during viral infections of the lung. However, the exact role of CXCL17 in health and disease requires further investigation, and there is a need for confirmed molecular targets mediating CXCL17 functional responses. Using a range of bioluminescence resonance energy transfer (BRET)-based assays, here we demonstrated that CXCL17 inhibited CXCR4-mediated signaling and ligand binding. Moreover, CXCL17 interacted with neuropillin-1, a VEGFR2 coreceptor. In addition, we found that CXCL17 only inhibited CXCR4 ligand binding in intact cells and demonstrated that this effect was mimicked by known glycosaminoglycan binders, surfen and protamine sulfate. Disruption of putative GAG binding domains in CXCL17 prevented CXCR4 binding. This indicated that CXCL17 inhibited CXCR4 by a mechanism of action that potentially required the presence of a glycosaminoglycan-containing accessory protein. Together, our results revealed that CXCL17 is an endogenous inhibitor of CXCR4 and represents the next step in our understanding of the function of CXCL17 and regulation of CXCR4 signaling.

CXCL12+ dermal fibroblasts promote neutrophil recruitment and host defense by recognition of IL-17.

The skin provides an essential barrier for host defense through rapid action of multiple resident and recruited cell types, but the complex communication network governing these processes is incompletely understood. To define these cell-cell interactions more clearly, we performed an unbiased network analysis of mouse skin during invasive S. aureus infection and revealed a dominant role for CXCL12+ fibroblast subsets in neutrophil communication. These subsets predominantly reside in the reticular dermis, express adipocyte lineage markers, detect IL-17 and TNFα, and promote robust neutrophil recruitment through NFKBIZ-dependent release of CXCR2 ligands and CXCL12. Targeted deletion of Il17ra in mouse fibroblasts resulted in greatly reduced neutrophil recruitment and increased infection by S. aureus. Analogous human CXCL12+ fibroblast subsets abundantly express neutrophil chemotactic factors in psoriatic skin that are subsequently decreased upon therapeutic targeting of IL-17. These findings show that CXCL12+ dermal immune acting fibroblast subsets play a critical role in cutaneous neutrophil recruitment and host defense.

GPCR kinases differentially modulate biased signaling downstream of CXCR3 depending on their subcellular localization.

Some G protein-coupled receptors (GPCRs) demonstrate biased signaling such that ligands of the same receptor exclusively or preferentially activate certain downstream signaling pathways over others. This phenomenon may result from ligand-specific receptor phosphorylation by GPCR kinases (GRKs). GPCR signaling can also exhibit location bias because GPCRs traffic to and signal from subcellular compartments in addition to the plasma membrane. Here, we investigated whether GRKs contributed to location bias in GPCR signaling. GRKs translocated to endosomes after stimulation of the chemokine receptor CXCR3 or other GPCRs in cultured cells. GRK2, GRK3, GRK5, and GRK6 showed distinct patterns of recruitment to the plasma membrane and to endosomes depending on the identity of the biased ligand used to activate CXCR3. Analysis of engineered forms of GRKs that localized to either the plasma membrane or endosomes demonstrated that biased CXCR3 ligands elicited different signaling profiles that depended on the subcellular location of the GRK. Each GRK exerted a distinct effect on the regulation of CXCR3 engagement of β-arrestin, internalization, and activation of the downstream effector kinase ERK. Our work highlights a role for GRKs in location-biased GPCR signaling and demonstrates the complex interactions between ligands, GRKs, and cellular location that contribute to biased signaling.

Intratumoral delivery of a highly active form of XCL1 enhances antitumor CTL responses through recruitment of CXCL9-expressing conventional type-1 dendritic cells.

Conventional type 1 dendritic cells (cDC1s) play a crucial role in antitumor immunity through the induction and activation of tumor-specific CD8+ cytotoxic T cells (CTLs). The chemokine XCL1 is a major chemotactic factor for cDC1s and its receptor XCR1 is selectively expressed on cDC1s. Here, we investigated the effect of intratumoral delivery of a highly active form of murine XCL1 (mXCL1-V21C/A59C) on cDC1-mediated antitumor immunity using a hydrophilic gel patch. The hydrophilic gel patch containing mXCL1-V21C/A59C increased cDC1 accumulation in the tumor masses and promoted their migration to the regional lymph nodes, resulting in enhanced induction of tumor-specific CTLs. Tumor-infiltrating cDC1s not only expressed XCR1 but also produced CXCL9, a ligand for CXCR3 which is highly expressed on CTLs and NK cells. Consequently, CTLs and NK cells were increased in the tumor masses of mice treated with mXCL1-V21C/A59C, while immunosuppressive cells such as monocyte-derived suppressive cells and regulatory T cells were decreased. We also confirmed that anti-CXCL9 treatment decreased the tumor infiltration of CTLs. The intratumoral delivery of mXCL1-V21C/A59C significantly decreased tumor growth and prolonged survival in E.G7-OVA and B16-F10 tumor-bearing mice. Furthermore, the antitumor effect of mXCL1-V21CA59C was enhanced in combination with anti-programmed cell death protein 1 treatment. Finally, using The Cancer Genome Atlas database, we found that XCL1 expression was positively correlated with tumor-infiltrating cDC1s and a better prognosis in melanoma patients. Collectively, our findings provide a novel therapeutic approach to enhance tumor-specific CTL responses through the selective recruitment of CXCL9-expressing cDC1s into the tumor masses.

Pharmacological Characterization and Radiolabeling of VUF15485, a High-Affinity Small-Molecule Agonist for the Atypical Chemokine Receptor ACKR3.

Atypical chemokine receptor 3 (ACKR3), formerly referred to as CXCR7, is considered to be an interesting drug target. In this study, we report on the synthesis, pharmacological characterization and radiolabeling of VUF15485, a new ACKR3 small-molecule agonist, that will serve as an important new tool to study this β-arrestin-biased chemokine receptor. VUF15485 binds with nanomolar affinity (pIC50 = 8.3) to human ACKR3, as measured in [125I]CXCL12 competition binding experiments. Moreover, in a bioluminescence resonance energy transfer-based β-arrestin2 recruitment assay VUF15485 acts as a potent ACKR3 agonist (pEC50 = 7.6) and shows a similar extent of receptor activation compared with CXCL12 when using a newly developed, fluorescence resonance energy transfer-based ACKR3 conformational sensor. Moreover, the ACKR3 agonist VUF15485, tested against a (atypical) chemokine receptor panel (agonist and antagonist mode), proves to be selective for ACKR3. VUF15485 labeled with tritium at one of its methoxy groups ([3H]VUF15485), binds ACKR3 saturably and with high affinity (K d = 8.2 nM). Additionally, [3H]VUF15485 shows rapid binding kinetics and consequently a short residence time (<2 minutes) for binding to ACKR3. The selectivity of [3H]VUF15485 for ACKR3, was confirmed by binding studies, whereupon CXCR3, CXCR4, and ACKR3 small-molecule ligands were competed for binding against the radiolabeled agonist. Interestingly, the chemokine ligands CXCL11 and CXCL12 are not able to displace the binding of [3H]VUF15485 to ACKR3. The radiolabeled VUF15485 was subsequently used to evaluate its binding pocket. Site-directed mutagenesis and docking studies using a recently solved cryo-EM structure propose that VUF15485 binds in the major and the minor binding pocket of ACKR3. SIGNIFICANCE STATEMENT: The atypical chemokine receptor atypical chemokine receptor 3 (ACKR3) is considered an interesting drug target in relation to cancer and multiple sclerosis. The study reports on new chemical biology tools for ACKR3, i.e., a new agonist that can also be radiolabeled and a new ACKR3 conformational sensor, that both can be used to directly study the interaction of ACKR3 ligands with the G protein-coupled receptor.

CXCR4 Is a Potential Target for Anti-HIV Gene Therapy.

The human immunodeficiency virus (HIV) epidemic is a global issue. The estimated number of people with HIV is 39,000,000 to date. Antiviral therapy is the primary approach to treat the infection. However, it does not allow for a complete elimination of the pathogen. The advances in modern gene therapy methods open up new possibilities of effective therapy. One of these areas of possibility is the development of technologies to prevent virus penetration into the cell. Currently, a number of technologies aimed at either the prevention of virus binding to the CCR5 coreceptor or its knockout are undergoing various stages of clinical trials. Since HIV can also utilize the CXCR4 coreceptor, technologies to modify this receptor are also required. Standard knockout of CXCR4 is impossible due to its physiological significance. This review presents an analysis of interactions between individual amino acids in CXCR4 and physiological ligands and HIV gp120. It also discusses potential targets for gene therapy approaches aimed at modifying the coreceptor.

Abstract A031: Biotherapeutic strategies targeting the CXCR2 axis for depletion of myeloid-derived suppressor cells in pancreatic ductal adenocarcinoma

Abstract Pancreatic Ductal Adenocarcinoma (PDAC) has a 5-year survival rate of only 10%, and limited treatment options exist. Immune checkpoint inhibitors are effective in a variety of cancer types; however, the complex immunosuppressive tumor microenvironment (TME) of PDAC is a significant barrier to immunotherapy. Myeloid-derived suppressor cells (MDSCs) are abundant in PDAC tumors from humans and mouse models. MDSCs suppress effector T cell function and promote the expansion of other immunosuppressive cell types. This led us to hypothesize that targeting tumor MDSCs would be an effective therapeutic strategy for PDAC and enhance the efficacy of T cell based immunotherapy. Our preliminary data and the work from others shows that CXCR2 ligands such as CXCL8/IL-8, CXCL5/ENA78, and CXCL1/GROα are the most abundant soluble factors secreted by PDAC cells. CXCR2 ligands are critical for the homing of myeloid cells to sites of injury in cutaneous wound healing, suggesting that dysregulated secretion of CXCR2 chemokines in PDAC may mimic a wound healing response that attracts myeloid cells and promotes the expansion of MDSCs and an immunosuppressive TME. To test this hypothesis, we have designed and produced multiple drug-conjugated CXCR2 ligand-based engineered proteins to target and eliminate MDSCs from PDAC tumors. We are referring to these novel biotherapeutic molecules as Ligand Drug Conjugates (LDCs). We have demonstrated binding, internalization, induction of signaling, and cytotoxicity of these LDCs to CXCR2 expressing myeloid cells. Our data suggests that our engineered proteins are superior binders and activators of CXCR2 axis signaling compared to WT CXCR2 ligands. Utilizing CXCR2 knockin models we demonstrated that the cytotoxicity of our LDCs is CXCR2 dependent. In vivo, we are utilizing the KPC (LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre) mouse model of PDAC, which we've shown in preliminary studies to, like human PDAC, support an abundance of MDSCs in tumors as well as secondary lymphoid organs such as the spleen. We anticipate that this study will demonstrate the therapeutic potential and actionability of targeting MDSCs and will provide novel biotherapeutic drug candidates that will ultimately improve immunotherapy outcomes in patients with PDAC. Citation Format: Benjamin N. Christopher, Lety Reyes, Reeder Robinson, Lena Golick, Nathan Dolloff. Biotherapeutic strategies targeting the CXCR2 axis for depletion of myeloid-derived suppressor cells in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A031.

The Role of CXCR3 in Nervous System-Related Diseases.

Inflammatory chemokines are a group of G-protein receptor ligands characterized by conserved cysteine residues, which can be divided into four main subfamilies: CC, CXC, XC, and CX3C. The C-X-C chemokine receptor (CXCR) 3 and its ligands, C-X-C chemokine ligands (CXCLs), are widely expressed in both the peripheral nervous system (PNS) and central nervous system (CNS). This comprehensive literature review aims to examine the functions and pathways of CXCR3 and its ligands in nervous system-related diseases. In summary, while the related pathways and the expression levels of CXCR3 and its ligands are varied among different cells in PNS and CNS, the MPAK pathway is the core via which CXCR3 exerts physiological functions. It is not only the core pathway of CXCR3 after activation but also participates in the expression of CXCR3 ligands in the nervous system. In addition, despite CXCR3 being a common inflammatory chemokine receptor, there is no consensus on its precise roles in various diseases. This uncertainty may be attributable to distinct inflammatory characteristics, that inflammation simultaneously possesses the dual properties of damage induction and repair facilitation.