CXCL10-CXCR3 Axis Research Articles

Renal remodeling by CXCL10-CXCR3 axis-recruited mesenchymal stem cells and subsequent IL4I1 secretion in lupus nephritis

AbstractHuman umbilical cord mesenchymal stem cells (hUC-MSCs) have shown potential as a therapeutic option for lupus nephritis (LN), particularly in patients refractory to conventional treatments. Despite extensive translational research on MSCs, the precise mechanisms by which MSCs migrate to the kidney and restore renal function remain incompletely understood. Here, we aim to clarify the spatiotemporal characteristics of hUC-MSC migration into LN kidneys and their interactions with host cells in microenvironment. This study elucidates that the migration of hUC-MSCs to the LN kidney is driven by elevated levels of CXCL10, predominantly produced by glomerular vascular endothelial cells through the IFN-γ/IRF1-KPNA4 pathway. Interestingly, the blockade of CXCL10-CXCR3 axis impedes the migration of hUC-MSCs to LN kidney and negatively impacts therapeutic outcomes. Single cell-RNA sequencing analysis underscores the importance of this axis in mediating the regulatory effects of hUC-MSCs on the renal immune environment. Furthermore, hUC-MSCs have been observed to induce and secrete interleukin 4 inducible gene 1 (IL4I1) in response to the microenvironment of LN kidney, thereby suppressing Th1 cells. Genetically ablating IL4I1 in hUC-MSCs abolishes their therapeutic effects and prevents the inhibition of CXCR3+ Th1 cell infiltration into LN kidneys. This study provides valuable insights into the significant involvement of CXCL10-CXCR3 axis in hUC-MSC migration to the LN kidneys and the subsequent remodeling of renal immune microenvironment. Regulating the CXCL10-CXCR3 axis and IL4I1 secretion may be developed as a novel therapeutic strategy to improve treatment outcomes of LN.

LAMP1 controls CXCL10-CXCR3 axis mediated inflammatory regulation of macrophage polarization during inflammatory stimulation

Increased expression of CXCL10 and its receptor CXCR3 represents an inflammatory response in cells and tissues. Macrophage polarization and autophagy are major functions in inflammatory macrophages; however, the cellular functions of the CXCL10-CXCR3 axis in macrophages are not well understood. Here, we examined the role of CXCL10-CXCR3-axis-regulated autophagy in macrophage polarization. First, in non-inflammatory macrophages, whereas CXCL10 promotes M2 polarization and inhibits M1 polarization, CXCR3 antagonist AMG487 induces the opposite macrophage polarization. Next, CXCL10 promotes the expression of autophagy proteins (Atg5-Atg12 complex, p62, LC3-II, and LAMP1) and AMG487 inhibits their expression. Knockdown of LAMP1 by short interfering RNA switches the CXCL10-induced polarization from M2 to M1 in non-inflammatory macrophages. Furthermore, in inflammatory macrophages stimulated by poly(I:C), CXCL10 induces M1 polarization and AMG487 induces M2 polarization in association with a decrease in LAMP1. Finally, AMG487 alleviates lung injury after poly(I:C) treatment in mice. In conclusion, CXCL10-CXCR3 axis differentially directs macrophage polarization in inflammatory and non-inflammatory states, and autophagy protein LAMP1 acts as the switch controlling the direction of macrophage polarization by CXCL10-CXCR3.

Abstract 1394: The CXCL10-CXCR3 axis as Jekyll and Hyde: A regulator of metastasis and immune response in osteosarcoma

Abstract The CXCL10-CXCR3 axis is known to promote tumor growth and metastasis via autocrine signaling, while it can also elicit anti-tumor responses by paracrine signaling. However, its roles are still elusive in osteosarcoma (OS), the most common malignant bone tumor in children. In this study, we utilized in vitro assays, mouse models, and gene expression analysis to characterize the roles of the CXCL10-CXCR3 axis in OS. To understand the autocrine signaling, we performed in vitro phenotypic assays on three OS cell lines with and without CXCL10. The results showed that the chemokine increased AKT phosphorylation and tumor cell migration. Using a CRISPR-based CXCR3 deletion mutant, we demonstrated that the lack of the receptor inhibited OS tumor growth and pulmonary metastasis in an orthotopic xenograft mouse model. The results indicate that the CXCL10-CXCR3 axis is sufficient and necessary to promote aggressive phenotypes in OS via autocrine signaling. Next, using gene expression datasets from two cohorts of OS patients, we showed that high expression of CXCL10 or its cognate receptor CXCR3 was associated with a better prognosis. Since CXCL10 is known to recruit CXCR3+ immune cells to fight against cancer, we further found that the expression of the T cell marker CD3D was associated with a better prognosis. These results suggest that the chemokine may also play a protective role in osteosarcoma by recruiting anti-tumor immune cells via paracrine signaling. Lastly, we have previously reported that a high circulating level of CXCL10 correlates with a poor prognosis in osteosarcoma patients. In this study, we demonstrated that increasing the circulating CXCL10 level in immunodeficient orthotopic xenograft mouse models of OS did not significantly promote the development of pulmonary metastases, suggesting circulating CXCL10 may exert its chemotactic effect mainly on immune cells, not on tumor cells. Taken together, we propose a model that tumor expression of CXCL10 promotes osteosarcoma growth and metastasis development via autocrine signaling. The increase of the local level of CXCL10 attracts CXCR3+ immune cells to the tumor site and promotes anti-tumor function via paracrine signaling. Metastatic cells colonize the lungs and cause tissue damage and inflammation, which increases the production of CXCL10 in the circulation. The higher circulating CXCL10 recruits T cells away from the primary tumor site and indicates the occurrence of metastasis and, hence, correlates with a worse outcome in patients. Our research highlights the importance of understanding the opposite effects of CXCL10 on tumor and immune cells as well as in the tumor microenvironment and circulation. Identification of the mechanistic differences in the CXCL10-CXCR3 signaling between tumor and immune cells will provide a novel therapeutic approach against tumor cells while promoting anti-tumor immune response in OS. Citation Format: Benjamin B. Gyau, Xiang Chen, Junyan Wang, Margaret A. Clement, Angela M. Major, Jun Xu, M. John Hicks, Tsz-Kwong Man. The CXCL10-CXCR3 axis as Jekyll and Hyde: A regulator of metastasis and immune response in osteosarcoma [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 1394.

Abstract 727: FGFR4 promotes colon cancer progression through CAF activation via the CXCL10-CXCR3 axis

Abstract Cancer-associated fibroblasts (CAFs) contribute to cancer progression via crosstalk with cancer and immune cells in the tumor microenvironment (TME). Despite the significant role of CAF, the understanding of the trigger mechanisms of cancer-mediated CAF activation remains unclear. We previously reported the mechanism by which FGFR4 in colon cancer secretes amphiregulin (AREG), resulting in anti-EGFR chemoresistance. It motivated us to investigate whether FGFR4 overexpressing tumors may change the TME, so we explored the mechanism of CAF activation under the FGFR4 signaling pathway. CAF was isolated from BALB/C mice after injecting 1 × 106 CT-26/EV or FGFR4 cells using microbeads and conditioned media (CM) was prepared by filtering after 48h cancer cell culture with serum-free medium In mice model, CT-26/FGFR4 showed more significant tumor progression and CAF abundance (α-SMA, FAP, PDGFR, and vimentin) than CT-26/EV. Additionally, CT26/FGFR4-derived CAFs showed significantly increased invasiveness and contractility, indicating the highly activated status of CAFs. In order to verify the effect of cancer secretome from FGFR4 in cancer cells, normal fibroblast (NIH/3T3) were co-cultured with either stable cancer cells or CM. As a result, CT-26/FGFR4 cells robustly induced the expression of CAF markers in NIH/3T3 cells, indicating the promotion of CAF differentiation from resting fibroblasts. Also, CT-26/FGFR4-derived CM significantly promoted further activation of CAFs compared to CT-26/EV-derived CM. Taken together, FGFR4 contributes not only to CAF differentiation but also to CAF activation via secretome. Next, we performed RNA seq of CT-26/EV and CT-26/FGFR4 cells and identified the upregulated genes related with the interferon (IFN) signaling. Among these genes, we identified IFNβ and CXCL10 as targetable molecules via the activation of TLR3-TBK-IRF and IFN-STAT-CXCL10 signaling pathways. These results were confirmed by RT-PCR and western blot assay. Secreted CXCL10 induced gene expression of CAF markers in fibroblast and increased CAF functions such as migration, invasion and contractibility, reflecting CAF activation. Blocking antibodies and knocking down of CXCL10 inhibited the cancer secretome-mediated CAF markers. The blockade of CXCR3, which is the CXCL10 cognate receptor, also showed an inhibitory effect on the FGFR4-overexpressing cancer-educated CAF. In human colon cancer specimens, the expression of FGFR4, CXCL10, and CAF markers showed a positive correlation with each other. Finally, dual inhibition of FGFR4 and CXCR3 in tumor mouse model suppressed the tumor growth, accompanied by CAF suppression. Our findings reveal the novel mechanism of FGFR4 leading CAF differentiation/activation in TME via the CXCL10-CXCR3 axis. This suggests that FGFR4/CXCR3 inhibitor could be used as a potential therapeutic strategy to attenuate CAF in stromal dominant tumors. Citation Format: Sang-Hee Cho, Hyunjin Bang, Eun-Gene Sun, Ji-Na Choi, Mi-Ra Park, Hyun-Jeong Shim, Jun-Eul Hwang, Woo-Kyun Bae, Ik Joo Chung. FGFR4 promotes colon cancer progression through CAF activation via the CXCL10-CXCR3 axis [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 727.

The IFN-γ-CXCL9/CXCL10-CXCR3 axis in vitiligo: Pathological mechanism and treatment.

Vitiligo is a disease featuring distinct white patches that result from melanocyte destruction. The overall pathogenesis of vitiligo remains to be elucidated. Nevertheless, considerable research indicates that adaptive immune activation plays a key role in this process. Specifically, the interferon-gamma (IFN-γ), C-X-C motif chemokine ligands (CXCL9/10), and C-X-C motif chemokine receptor (CXCR3) signaling axis, collectively referred to as IFN-γ-CXCL9/10-CXCR3 or ICC axis, has emerged as a key mediator responsible for the recruitment of autoimmune CXCR3+ CD8+ T cells. These cells serve as executioners of melanocytes by promoting their detachment and apoptosis. Moreover, IFN-γ is generated by activated T cells to create a positive feedback loop, exacerbating the autoimmune response. This review not only delves into the mechanistic insights of the ICC axis but also explores the significant immunological effects of associated cytokines and their receptors. Additionally, the review provides a thorough comparison of existing and emerging treatment options that target the ICC axis for managing vitiligo. This review aims to foster further advancements in basic research within related fields and facilitate a deeper understanding of alternative treatment strategies targeting different elements of the axis.

Deciphering the immune modulation through deep transcriptomic profiling and therapeutic implications of DNA damage repair pattern in hepatocellular carcinoma

AimsDNA damage repair (DDR) plays a pivotal role in hepatocellular carcinoma (HCC), driving oncogenesis, progression, and therapeutic response. However, the mechanisms of DDR mediated immune cells and immuno-modulatory pathways in HCC are yet ill-defined. MethodsOur study introduces an innovative deep machine learning framework for precise DDR assessment, utilizing single-cell RNA sequencing (scRNA-seq) and bulk RNA-seq data. Single-cell RNA sequencing data were obtained and in total 85,628 cells of primary or post-immunotherapy cases were analyzed. Large-scale HCC datasets, including 1027 patients in house together with public datasets, were used for 101 machine-learning models and a novel DDR feature was derived at single-cell resolution (DDRscore). Druggable targets were predicted using the reverse phase protein array (RPPA) proteomic profiling of 169 HCC patients and RNA-seq data from 22 liver cancer cell lines. ResultsOur investigation reveals a dynamic interplay of DDR with natural killer cells and B cells in the primary HCC microenvironment, shaping a tumor-promoting immune milieu through metabolic programming. Analysis of HCC post-immunotherapy demonstrates elevated DDR levels that induces epithelial-mesenchymal transition and fibroblast-like transformation, reshaping the fibrotic tumor microenvironment. Conversely, attenuated DDR promotes antigen cross-presentation by dendritic cells and CD8+ T cells, modulating the inflammatory tumor microenvironment. Regulatory network analysis identifies the CXCL10-CXCR3 axis as a key determinant of immunotherapeutic response in low DDR HCC, potentially regulated by transcription factors GATA3, REL, and TBX21. Using machine learning techniques by combining bulk RNA-seq data in house together with public datasets, we introduce DDRscore, a robust consensus DDR scoring system to predict overall survival and resistance to PD-1 therapy in HCC patients. Finally, we identify BRAF as a potential therapeutic target for high DDRscore patients. ConclusionOur comprehensive findings advance our understanding of DDR and the tumor microenvironment in HCC, providing insights into immune regulatory mechanisms mediated via DDR pathways.

The CXCL10-CXCR3 axis plays an important role in Kawasaki disease.

The precise pathogenesis of Kawasaki disease remains unknown. In an attempt to elucidate the pathogenesis of KD through the analysis of acquired immunity, we comprehensively examined the immunophenotypic changes in immune cells such as lymphocytes and monocytes along with various cytokines, focusing on differences between pre- and post- treatment samples. We found high levels of CXCL9 and CXCL10 chemokines that decreased with treatment, which coincided with a post-treatment expansion of Th1 cells expressing CXCR3. Our results show that the CXCL10-CXCR3 axis plays an important role in the pathogenesis of KD.

CXCL10 deficiency limits macrophage infiltration, preserves lung matrix, and enables lung growth in bronchopulmonary dysplasia

Preterm infants with oxygen supplementation are at high risk for bronchopulmonary dysplasia (BPD), a neonatal chronic lung disease. Inflammation with macrophage activation is central to the pathogenesis of BPD. CXCL10, a chemotactic and pro-inflammatory chemokine, is elevated in the lungs of infants evolving BPD and in hyperoxia-based BPD in mice. Here, we tested if CXCL10 deficiency preserves lung growth after neonatal hyperoxia by preventing macrophage activation. To this end, we exposed Cxcl10 knockout (Cxcl10−/−) and wild-type mice to an experimental model of hyperoxia (85% O2)-induced neonatal lung injury and subsequent regeneration. In addition, cultured primary human macrophages and murine macrophages (J744A.1) were treated with CXCL10 and/or CXCR3 antagonist. Our transcriptomic analysis identified CXCL10 as a central hub in the inflammatory network of neonatal mouse lungs after hyperoxia. Quantitative histomorphometric analysis revealed that Cxcl10−/− mice are in part protected from reduced alveolar. These findings were related to the preserved spatial distribution of elastic fibers, reduced collagen deposition, and protection from macrophage recruitment/infiltration to the lungs in Cxcl10−/− mice during acute injury and regeneration. Complimentary, studies with cultured human and murine macrophages showed that hyperoxia induces Cxcl10 expression that in turn triggers M1-like activation and migration of macrophages through CXCR3. Finally, we demonstrated a temporal increase of macrophage-related CXCL10 in the lungs of infants with BPD. In conclusion, our data demonstrate macrophage-derived CXCL10 in experimental and clinical BPD that drives macrophage chemotaxis through CXCR3, causing pro-fibrotic lung remodeling and arrest of alveolarization. Thus, targeting the CXCL10-CXCR3 axis could offer a new therapeutic avenue for BPD.

Phagocytosis by macrophages promotes pancreatic β cell mass reduction after parturition in mice

Elucidating the mechanism(s) modulating appropriate tissue size is a critical biological issue. Pancreatic β cells increase during pregnancy via cellular proliferation, but how β cells promptly decrease to the original amount after parturition remains unclear. Herein, we demonstrate the role and mechanism of macrophage accumulation in this process. In the final stage of pregnancy, HTR1D signaling upregulates murine β cell CXCL10, thereby promoting macrophage accumulation in pancreatic islets via the CXCL10-CXCR3 axis. Blocking this mechanism by administering an HTR1D antagonist or the CXCR3 antibody and depleting islet macrophages inhibited postpartum β cell mass reduction. β cells engulfed by macrophages increased in postpartum islets, but Annexin V administration suppressed this engulfment and the postpartum β cell mass reduction, indicating the accumulated macrophages to phagocytose β cells. This mechanism contributes to both maintenance of appropriate β cell mass and glucose homeostasis promptly adapting to reduced systemic insulin demand after parturition.

Role of the transcription factor Fli-1 on the CXCL10/CXCR3 Axis.

The transcription factor Fli-1, a member of the ETS family of transcription factors, is implicated in the pathogenesis of lupus disease. Reduced Fli-1 expression in lupus mice leads to decreased renal Cxcl10 mRNA levels and renal infiltrating CXCR3+ T cells that parallels reduced renal inflammatory cell infiltration and renal damage. Inflammatory chemokine CXCL10 is critical for attracting inflammatory cells expressing the chemokine receptor CXCR3. The CXCL10/CXCR3 axis plays a role in the pathogenesis of various inflammatory diseases including lupus. Our data here demonstrate that renal CXCL10 protein levels are significantly lower in Fli-1 heterozygous MRL/lpr mice compared to wild-type MRL/lpr mice. Knockdown of Fli-1 significantly reduced CXCL10 secretion in mouse and human endothelial cells, and human mesangial cells, upon LPS or TNFα stimulation. The Fli-1 inhibitor, Camptothecin, significantly reduced CXCL10 production in human monocyte cells upon interferon stimulation. Four putative Ets binding sites in the Cxcl10 promoter showed significant enrichment for FLI-1; however, FLI-1 did not directly drive transcription from the human or mouse promoters, suggesting FLI-1 may regulate CXCL10 expression indirectly. Our results also suggest that the DNA binding domain of FLI-1 is necessary for regulation of human hCXCR3 promotor activity in human T cells and interactions with co-activators. Together, these results support a role for FLI-1 in modulating the CXCL10-CXCR3 axis by directly or indirectly regulating the expression of both genes to impact lupus disease development. Signaling pathways or drugs that reduce FLI-1 expression may offer novel approaches to lupus treatment.

Abstract 1307: The effect of circulating CXCL10 on osteosarcoma metastasis using orthotopic xenograft mouse models

Abstract Osteosarcoma is the most common malignant bone tumor in children. Despite the use of chemotherapy and surgery, the survival of patients with metastasis is still dismal. We have previously reported that a high serum level of CXCL10 is associated with a poor prognosis and metastasis in osteosarcoma, suggesting that the chemokine may affect the development of metastasis. Nonetheless, the effect of endocrine signaling of CXCL10 is largely unknown. It is unclear if the prognostic effect of circulating CXCL10 is due to its metastasis-promoting effect or if CXCL10 is merely a biomarker. In this study, we employed orthotopic xenograft mouse models to examine the effect of circulating CXCL10 with respect to metastasis. We first injected luciferase-labeled 143B osteosarcoma cells into the tibia of NOD/SCID mice to generate an orthotopic xenograft mouse model. When the tumor was detectable by bioluminescence, we injected 1.5ug of CXCL10 protein or saline intravenously via the tail vein every day for two weeks. The development of pulmonary metastasis was monitored by bioluminescence. The mice were sacrificed at the endpoint when bioluminescence was detected in the lungs. The mouse lungs were then resected and examined by H&E staining for the detection of metastatic nodules. The mice in the experimental and control groups that developed lung metastases were compared. The results showed that no significant difference was observed between the two groups. The experiment was repeated one more time and similar results were observed. To investigate the influence of the cell line background, we analyzed another osteosarcoma cell line, MG63.3. No significant difference in metastasis development was observed between the mice injected with CXCL10 and the mice injected with saline. The results indicate that a higher level of circulating CXCL10 alone was not sufficient to promote pulmonary metastases in the orthotopic xenograft mouse models. We also showed that AKT phosphorylation was upregulated in the osteosarcoma cell lines incubated with CXCL10, ruling out that the CXCL10 protein used was biologically inactive. In summary, our results suggest that although an increased circulating level of CXCL10 is associated with a poor prognosis in osteosarcoma patients, it does not promote the development of pulmonary metastasis in xenograft mouse models. Circulating CXCL10 may only act as a prognostic biomarker, but not a metastatic driver. Alternatively, the CXCL10-CXCR3 axis may be necessary, but not sufficient, to cause metastasis. Citation Format: Xiang Chen, Margaret Clement, John Hicks, Tsz Kwong Man. The effect of circulating CXCL10 on osteosarcoma metastasis using orthotopic xenograft mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1307.

Irradiation Induced Activation of cGAS/STING Signaling Promotes Macrophage Anti-Tumor Activity via CXCL9, CXCL10-CXCR3 Axis

<h3>Purpose/Objective(s)</h3> Irradiation induced abundant dsDNA fragments, which can stimulate tumor immune responses by DNA sensing pathway. However, the underlying mechanism, mainly involved immune cells remains unknown. Herein we discovered that macrophage was the main immune cell involved in cGAS/STING DNA sensing pathway induced anti-tumor immune response, and macrophage derived CXCL9, CXCL10 played an important role in infiltration of T cells in tumor via CXCL9, CXCL10-CXCR3 axis. <h3>Materials/Methods</h3> cGAS knockout mice (cGAS-/- mice) and STING-deficient mice were used in the study. Xenograft tumor mouse model was established for in vivo study, using murine hepatoma cell line H22 or ovalbumin (OVA)-expressing H22. Irradiation locally delivered to the tumor area at 8 Gy/day for 3 days using a micro-CT/micro irradiator. <h3>Results</h3> Macrophage was found recruitment to the irradiated tumor site after irradiation. Using C57BL/6J mice bearing xenograft H22 tumors, we found cGAS-/- mice showed higher growth rate after irradiation comparing to tumors growing on wild type mice (WT mice). Using a both sides subcutaneous H22-OVA tumor mouse model, we found a substantial increased OVA-specific CD8+ T cells within the DLN(draining lymph node) of right irradiated tumor of WT mice, but low level within the right DLN of the irradiated tumor of STING-deficient mice and the no-irradiated right tumors of STING-deficient mice or WT mice, which confirmed that cGAS/STING pathway was involved in the radiation-mediated immunomodulation and promoted the radiation-induced adaptive anti-tumor immune activation. We also noted macrophage depletion partial reverse antitumor effect of irradiation in WT tumors, while no significant difference is observed in cGAS^−/− tumor, which revealed macrophage was the main immune cell involved in cGAS/STING DNA sensing pathway induced anti-tumor immune response. Further mechanism study revealed macrophage derived CXCL9, CXCL10 was induced by radiation in a cGAS/STING pathway dependent manner. Intraperitoneal injection of anti-CXCL9, CXCL10 significantly reduce the anti-tumor effect of irradiation in WT mice, but not in STING-deficient mice, these observations suggested macrophage derived CXCL9, CXCL10 were involved in infiltration of T cells in tumor via CXCL9, CXCL10-CXCR3 axis. <h3>Conclusion</h3> cGAS/STING pathway is crucial in the radiation-induced adaptive anti-tumor immune activation. macrophage derived CXCL9, CXCL10, which induced by radiation in a cGAS/STING pathway dependent manner, mediated infiltration of T cells in tumor via CXCL9, CXCL10- CXCR3 axis.

What Is Currently Known about the Role of CXCL10 in SARS-CoV-2 Infection?

Dysregulation of the immune response plays an important role in the progression of SARS-CoV-2 infection. A “cytokine storm”, which is a phenomenon associated with uncontrolled production of large amounts of cytokines, very often affects patients with COVID-19. Elevated activity of chemotactic cytokines, called chemokines, can lead to serious consequences. CXCL10 has an ability to activate its receptor CXCR3, predominantly expressed on macrophages, T lymphocytes, dendritic cells, natural killer cells, and B cells. So, it has been suggested that the chemokine CXCL10, through CXCR3, is associated with inflammatory diseases and may be involved in the development of COVID-19. Therefore, in this review paper, we focus on the role of CXCL10 overactivity in the pathogenesis of COVID-19. We performed an extensive literature search for our investigation using the MEDLINE/PubMed database. Increased concentrations of CXCL10 were observed in COVID-19. Elevated levels of CXCL10 were reported to be associated with a severe course and disease progression. Published studies revealed that CXCL10 may be a very good predictive biomarker of patient outcome in COVID-19, and that markedly elevated CXCL10 levels are connected with ARDS and neurological complications. It has been observed that an effective treatment for SARS-CoV-2 leads to inhibition of “cytokine storm”, as well as reduction of CXCL10 concentrations. It seems that modulation of the CXCL10–CXCR3 axis may be an effective therapeutic target of COVID-19. This review describes the potential role of CXCL10 in the pathogenesis of COVID-19, as well as its potential immune–therapeutic significance. However, future studies should aim to confirm the prognostic, clinical, and therapeutic role of CXCL10 in SARS-CoV-2 infection.

Dual G9A/EZH2 Inhibition Stimulates Antitumor Immune Response in Ovarian High-Grade Serous Carcinoma.

Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumor immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10-CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells while suppressing tumor-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1-005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1-005 improved the survival of mice bearing Trp53-/- null ID8 ovarian tumors and resulted in tumor burden reduction. These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumor growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development.

CXCL10 could drive longer duration of mechanical ventilation during COVID-19 ARDS

BackgroundCOVID-19-related ARDS has unique features when compared with ARDS from other origins, suggesting a distinctive inflammatory pathogenesis. Data regarding the host response within the lung are sparse. The objective is to compare alveolar and systemic inflammation response patterns, mitochondrial alarmin release, and outcomes according to ARDS etiology (i.e., COVID-19 vs. non-COVID-19).MethodsBronchoalveolar lavage fluid and plasma were obtained from 7 control, 7 non-COVID-19 ARDS, and 14 COVID-19 ARDS patients. Clinical data, plasma, and epithelial lining fluid (ELF) concentrations of 45 inflammatory mediators and cell-free mitochondrial DNA were measured and compared.ResultsCOVID-19 ARDS patients required mechanical ventilation (MV) for significantly longer, even after adjustment for potential confounders. There was a trend toward higher concentrations of plasma CCL5, CXCL2, CXCL10, CD40 ligand, IL-10, and GM-CSF, and ELF concentrations of CXCL1, CXCL10, granzyme B, TRAIL, and EGF in the COVID-19 ARDS group compared with the non-COVID-19 ARDS group. Plasma and ELF CXCL10 concentrations were independently associated with the number of ventilator-free days, without correlation between ELF CXCL-10 and viral load. Mitochondrial DNA plasma and ELF concentrations were elevated in all ARDS patients, with no differences between the two groups. ELF concentrations of mitochondrial DNA were correlated with alveolar cell counts, as well as IL-8 and IL-1β concentrations.ConclusionCXCL10 could be one key mediator involved in the dysregulated immune response. It should be evaluated as a candidate biomarker that may predict the duration of MV in COVID-19 ARDS patients. Targeting the CXCL10-CXCR3 axis could also be considered as a new therapeutic approach.Trial registrationClinicalTrials.gov, NCT03955887

Inflammatory Activation of Astrocytes Facilitates Melanoma Brain Tropism via the CXCL10-CXCR3 Signaling Axis

Melanoma is the deadliest skin cancer due to its high rate of metastasis, frequently to the brain. Brain metastases are incurable; therefore, understanding melanoma brain metastasis is of great clinical importance. We used a mouse model of spontaneous melanoma brain metastasis to study the interactions of melanomas with the brain microenvironment. We find that CXCL10 is upregulated in metastasis-associated astrocytes in mice and humans and is functionally important for the chemoattraction of melanoma cells. Moreover, CXCR3, the receptor for CXCL10, is upregulated in brain-tropic melanoma cells. Targeting melanoma expression of CXCR3 by nanoparticle-mediated siRNA delivery or by shRNA transduction inhibits melanoma cell migration and attenuates brain metastasis invivo. These findings suggest that the instigation of pro-inflammatory signaling in astrocytes is hijacked by brain-metastasizing tumor cells to promote their metastatic capacity and that the CXCL10-CXCR3 axis may be a potential therapeutic target for the prevention of melanoma brain metastasis.

CCR5 deficiency enhances hepatic innate immune cell recruitment and inflammation in a murine model of acutehepatitis B infection.

Human genetic studies demonstrate a link between the 32-bp deletion that produces a nonfunctional CCR5 receptor and enhanced recovery from acute hepatitis B virus (HBV) infection. To investigate the role of CCR5 in immune responses to acute HBV, we intravenously infected Ccr5+/+ (WT) and Ccr5-/- (KO) mice with a replication-incompetent adenovirus containing the overlapping HBV1.3 construct (AdHBV), or vector control. At day 3 following AdHBV infection, analysis of intrahepatic leukocytes (IHL) showed KO mice had increased CD11b+ NK cells compared to WT (18.2% versus 7.6% of live IHL, P<0.01). These CD11b+ NK cells were nonresident (CD49a- ) and had capacity to degranulate and produce IFN-γ following stimulation. At day 3, plasma CXCL10 was significantly increased in KO, but not WT, mice receiving AdHBV as compared to vector control, while CXCR3 expression on hepatic CD11b+ NK cells in AdHBV-treated KO mice was significantly lower than that in uninfected mice, suggesting these NK cells are recruited along the CXCL10-CXCR3 axis. At days 7 and 14, no differences between genotypes were observed in number, or HBV-specific function, of intrahepatic CD8+ T cells. Instead, at day 14, KO mice had increased intrahepatic proinflammatory monocytes compared to WT mice (17.56% versus 6.57% of live IHL, P=0.014), corresponding with an increase in plasma alanine aminotransferase and intrahepatic IL-1β observed in KO mice. Taken together, these findings demonstrate that loss of CCR5 signaling drives a more robust inflammatory liver microenvironment early in acute HBV infection via enrichment of hepatic innate immune cells.

Chemokine CXCL10/CXCR3 signaling contributes to neuropathic pain in spinal cord and dorsal root ganglia after chronic constriction injury in rats

Inflammatory cytokines and chemokines play essential roles in the occurrence and persistence of neuropathic pain (NP). Chronic constriction injury (CCI) enhances the activation of p-ERK, which is involved in neuropathic pain. Although the chemokine CXCL10 and its receptor CXCR3 are implicated in the pathophysiology of itch, it is largely unexplored for neuropathic pain. In this study, we determined the role of the CXCL10-CXCR3 axis in NP using a well-established CCI model. CCI significantly induced mechanical allodynia and thermal hyperalgesia. Following the pain course, a significant increase of CXCL10 and CXCR3 in both dorsal root ganglion (DRG) neurons and spinal cord (SC) neurons was detected in rats. Furthermore, intrathecal injection of CXCR3 inhibitor AMG487 was found to attenuate pain hypersensitivity in a dose-dependent manner in CCI. The expression of p-ERK was also depressed after intrathecal injection of AMG487 associated with a significant laxation of hyperalgesia, which demonstrated that the interaction of CXCL10/CXCR3 possibly took part in neuropathic pain by regulating p-ERK signaling in the SC. Overall, these findings demonstrate that the CXCL10/CXCR3 signaling pathway is critical in CCI.

Therapy-Educated Mesenchymal Stem Cells Enrich for Tumor-Initiating Cells.

Stromal cells residing in the tumor microenvironment contribute to the development of therapy resistance. Here we show that chemotherapy-educated mesenchymal stem cells (MSC) promote therapy resistance via cross-talk with tumor-initiating cells (TIC), a resistant tumor cell subset that initiates tumorigenesis and metastasis. In response to gemcitabine chemotherapy, MSCs colonized pancreatic adenocarcinomas in large numbers and resided in close proximity to TICs. Furthermore, gemcitabine-educated MSCs promoted the enrichment of TICs in vitro and enhance tumor growth in vivo These effects were dependent on the secretion of CXCL10 by gemcitabine-educated MSCs and subsequent activation of the CXCL10-CXCR3 axis in TICs. In an orthotopic pancreatic tumor model, targeting TICs using nanovesicles (called nanoghosts) derived from MSC membranes and loaded with a CXCR3 antagonist enhanced therapy outcome and delayed tumor regrowth when administered in combination with gemcitabine. Overall, our results establish a mechanism through which MSCs promote chemoresistance, and propose a novel drug delivery system to target TICs and overcome this resistance.Significance: These results establish a mechanism by which mesenchyme stem cells in the tumor microenvironment promote chemoresistance, and they propose a novel drug delivery system to overcome this challenge. Cancer Res; 78(5); 1253-65. ©2018 AACR.

Brain Endothelial- and Epithelial-Specific Interferon Receptor Chain 1 Drives Virus-Induced Sickness Behavior and Cognitive Impairment

Sickness behavior and cognitive dysfunction occur frequently by unknown mechanisms in virus-infected individuals with malignancies treated with type I interferons (IFNs) and in patients with autoimmune disorders. We found that during sickness behavior, single-stranded RNA viruses, double-stranded RNA ligands, and IFNs shared pathways involving engagement of melanoma differentiation-associated protein 5 (MDA5), retinoic acid-inducible gene 1 (RIG-I), and mitochondrial antiviral signaling protein (MAVS), and subsequently induced IFN responses specifically in brain endothelia and epithelia of mice. Behavioral alterations were specifically dependent on brain endothelial and epithelial IFN receptor chain 1 (IFNAR). Using gene profiling, we identified that the endothelia-derived chemokine ligand CXCL10 mediated behavioral changes through impairment of synaptic plasticity. These results identified brain endothelial and epithelial cells as natural gatekeepers for virus-induced sickness behavior, demonstrated tissue specific IFNAR engagement, and established the CXCL10-CXCR3 axis as target for the treatment of behavioral changes during virus infection and type I IFN therapy.