Treg-Cell Control of a CXCL5-IL-17 Inflammatory Axis Promotes Hair-Follicle-Stem-Cell Differentiation During Skin-Barrier Repair.

Restoration of barrier-tissue integrity after injury is dependent on the function of immune cells and stem cells (SCs) residing in the tissue. In response to skin injury, hair-follicle stem cells (HFSCs), normally poised for hair generation, are recruited to the site of injury and differentiate into cells that repair damaged epithelium. We used a SC fate-mapping approach to examine the contribution of regulatory T (Treg) cells to epidermal-barrier repair after injury. Depletion of Treg cells impaired skin-barrier regeneration and was associated with a Th17 inflammatory response and failed HFSC differentiation. In this setting, damaged epithelial cells preferentially expressed the neutrophil chemoattractant CXCL5, and blockade of CXCL5 or neutrophil depletion restored barrier function and SC differentiation after epidermal injury. Thus, Treg-cell regulation of localized inflammation enables HFSC differentiation and, thereby, skin-barrier regeneration, with implications for the maintenance and repair of other barrier tissues.

The Lineage-Defining Transcription Factors SOX2 and NKX2-1 Determine Lung Cancer Cell Fate and Shape the Tumor Immune Microenvironment.

The major types of non-small-cell lung cancer (NSCLC)-squamous cell carcinoma and adenocarcinoma-have distinct immune microenvironments. We developed a genetic model of squamous NSCLC on the basis of overexpression of the transcription factor Sox2, which specifies lung basal cell fate, and loss of the tumor suppressor Lkb1 (SL mice). SL tumors recapitulated gene-expression and immune-infiltrate features of human squamous NSCLC; such features included enrichment of tumor-associated neutrophils (TANs) and decreased expression of NKX2-1, a transcriptional regulator that specifies alveolar cell fate. In Kras-driven adenocarcinomas, mis-expression of Sox2 or loss of Nkx2-1 led to TAN recruitment. TAN recruitment involved SOX2-mediated production of the chemokine CXCL5. Deletion of Nkx2-1 in SL mice (SNL) revealed that NKX2-1 suppresses SOX2-driven squamous tumorigenesis by repressing adeno-to-squamous transdifferentiation. Depletion of TANs in SNL mice reduced squamous tumors, suggesting that TANs foster squamous cell fate. Thus, lineage-defining transcription factors determine the tumor immune microenvironment, which in turn might impact the nature of the tumor.

MDA-9/Syntenin in the tumor and microenvironment defines prostate cancer bone metastasis.

Bone metastasis is a frequent and incurable consequence of advanced prostate cancer (PC). An interplay between disseminated tumor cells and heterogeneous bone resident cells in the metastatic niche initiates this process. Melanoma differentiation associated gene-9 (mda-9/Syntenin/syndecan binding protein) is a prometastatic gene expressed in multiple organs, including bone marrow-derived mesenchymal stromal cells (BM-MSCs), under both physiological and pathological conditions. We demonstrate that PDGF-AA secreted by tumor cells induces CXCL5 expression in BM-MSCs by suppressing MDA-9-dependent YAP/MST signaling. CXCL5-derived tumor cell proliferation and immune suppression are consequences of the MDA-9/CXCL5 signaling axis, promoting PC disease progression. mda-9 knockout tumor cells express less PDGF-AA and do not develop bone metastases. Our data document a previously undefined role of MDA-9/Syntenin in the tumor and microenvironment in regulating PC bone metastasis. This study provides a framework for translational strategies to ameliorate health complications and morbidity associated with advanced PC.

IL-17A-neutralizing antibody ameliorates inflammation and fibrosis in rosacea by antagonizing the CXCL5/CXCR2 axis.

Rosacea is a chronic inflammatory skin disorder that can lead to fibrosis. However, the mechanisms underlying fibrosis in the later stages of rosacea have been less thoroughly investigated. Interleukin-17A (IL-17A) has been implicated in both inflammation and organ fibrosis; however, the effectiveness and mechanism of IL-17A-neutralizing antibodies in the later stages of rosacea-related fibrosis remain unclear. In this study, we induced rosacea-like lesions in mice using LL-37 and administered IL-17A-neutralizing antibodies. The results indicated that the IL-17A-neutralizing antibodies alleviated skin damage, reduced skin thickness, and decreased the secretion of inflammatory factors (TNF-α, CAMP, TLR4, P-NF-kB), angiogenesis-related factors (CD31, VEGF), and the TGF-ß1 signaling pathway, along with factors associated with epithelial-mesenchymal transition and the deposition of fibrosis-related proteins (COL1) in the rosacea-like mouse models. Furthermore, the IL-17A-neutralizing antibodies effectively diminished the expression of IL-17, IL-17R, CXCL5, and CXCR2 in the skin. Our findings demonstrate that IL-17A-neutralizing antibodies inhibit the activation of the CXCL5/CXCR2 axis in rosacea-like skin tissue, thereby ameliorating inflammation and fibrosis associated with the condition.

Investigating the Involvement of C-X-C Motif Chemokine 5 and P2X7 Purinoceptor in Ectopic Calcification in Mouse Models of Duchenne Muscular Dystrophy.

Ectopic calcification of myofibers is an early pathogenic feature in patients and animal models of Duchenne muscular dystrophy (DMD). In previous studies using the Dmdmdx-ßgeo mouse model, we found that the dystrophin-null phenotype exacerbates this abnormality and that mineralised myofibers are surrounded by macrophages. Furthermore, the P2X7 purinoceptor, functioning in immune cells offers protection against dystrophic calcification. In the present study, by exploring transcriptomic data from Dmdmdx mice, we hypothesised these effects to be mediated by C-X-C motif chemokine 5 (CXCL5) downstream of P2X7 activation. We found that CXCL5 is upregulated in the quadriceps muscles of Dmdmdx-ßgeo mice compared to wild-type controls. In contrast, at the cell level, dystrophic (SC5) skeletal muscle cells secreted less CXCL5 chemokine than wild-type (IMO) controls. Although release from IMO cells was increased by P2X7 activation, this could not explain the elevated CXCL5 levels observed in dystrophic muscle tissue. Instead, we found that CXCL5 is released by dystrophin-null macrophages in response to P2X7 activation, suggesting that macrophages are the source of CXCL5 in dystrophic muscles. The effects of CXCL5 upon mineralisation were investigated using the Alizarin Red assay to quantify calcium deposition in vitro. In basal (low phosphate) media, CXCL5 increased calcification in IMO but not SC5 myoblasts. However, in cultures treated in high phosphate media, to mimic dysregulated phosphate metabolism occurring in DMD, CXCL5 decreased calcification in both IMO and SC5 cells. These data indicate that CXCL5 is part of a homoeostatic mechanism regulating intracellular calcium, that CXCL5 can be released by macrophages in response to the extracellular ATP damage-associated signal, and that CXCL5 can be part of a damage response to protect against ectopic calcification. This mechanism is affected by DMD gene mutations.

miR-616-3p alleviates inflammatory response by targeting C-X-C motif chemokine ligand 5.

C/EBP homologous protein (CHOP) is a key regulator in ER stress-mediated signaling pathway via PERK-dependent unfolded protein response. It has been known that microRNA-616 (miR-616) is produced from the intron of the human DDIT3 gene encoding CHOP and increased by ER stress. However, the role of miR-616 and its targets are not fully addressed yet. Here we try to identify a novel target of miR-616 in human lung epithelial cells. Microarray analysis showed that CXCL5 is the most downregulated gene by miR-616 overexpression in A549 cells. We also found that CXCL5 mRNA and protein levels were significantly reduced by miR-616 mimic in the presence or absence of TNFα, while anti-miR-616 enhanced CXCL5 expression. In addition, miR-616-3p targeting sequence in 3'UTR of CXCL5 was confirmed by luciferase reporter assay suggesting that miR-616-3p directly binds to 3'UTR of CXCL5 and inhibits CXCL5 expression. Finally, we confirmed that conditioned medium from A549 cells treated with TNFα or Streptococcus pneumoniae lysates increased intra-alveolar neutrophil infiltration in a mouse model of pulmonary inflammation, while this induction was significantly reduced in a conditioned medium from cells transfected with miR-616-3p. These results suggest that miR-616-3p can alleviate CXCL5-induced pulmonary inflammatory response via targeting 3'UTR of CXCL5 gene.

Prognostic marker CXCL5 in glioblastoma polyformis and its mechanism of immune invasion.

Glioblastoma multiforme (GBM) is the most aggressive brain cancer with a poor prognosis. Therefore, the correlative molecular markers and molecular mechanisms should be explored to assess the occurrence and treatment of glioma.WB and qPCR assays were used to detect the expression of CXCL5 in human GBM tissues. The relationship between CXCL5 expression and clinicopathological features was evaluated using logistic regression analysis, Wilcoxon symbolic rank test, and Kruskal-Wallis test. Univariate, multivariate Cox regression and Kaplan-Meier methods were used to assess CXCL5 and other prognostic factors of GBM. Gene set enrichment analysis (GSEA) was used to identify pathways associated with CXCL5. The correlation between CXCL5 and tumor immunoinfiltration was investigated using single sample gene set enrichment analysis (ssGSEA) of TCGA data. Cell experiments and mouse subcutaneous transplanted tumor models were used to evaluate the role of CXCL5 in GBM. WB, qPCR, immunofluorescence, and immunohistochemical assays showed that CXCL5 expression was increased in human GBM tissues. Furthermore, high CXCL5 expression was closely related to poor disease-specific survival and overall survival of GBM patients. The ssGSEA suggested that CXCL5 is closely related to the cell cycle and immune response through PPAR signaling pathway. GSEA also showed that CXCL5 expression was positively correlated with macrophage cell infiltration level and negatively correlated with cytotoxic cell infiltration level. CXCL5 may be associated with the prognosis and immunoinfiltration of GBM.

Racial differences in serum chemokines in prostate cancer patients.

BACKGROUND: This study aimed to understand the differential levels of inflammatory chemokines in association with higher prostate cancer incidence and mortality in African American (AA) men than in Caucasians (CA). METHODS: The authors used a chemokine assay to simultaneously measure 40 chemokines and cytokines levels in the serum of preoperative prostate cancer patients and healthy controls of AA and CA races. Selected chemokines (CXCL2, CXCL5, and CCL23) serum level was validated in 211 serum samples from prostate cancer patients and healthy controls. Differential expression of CXCL5 and CCL23 was analyzed using immunohistochemistry in a representative cohort of prostate tumor tissues of AA and CA races. RESULTS: Race-specific comparisons from 211 serum samples showed significantly higher levels of CXCL2 (control: 3104.0 pg/mL vs. cancer: 2451.0 pg/mL) and CXCL5 (control: 5189.0 pg/mL vs. cancer: 5459.0 pg/mL) in AA men than in CAs (CXCL2; control: 1155.0 pg/mL vs. cancer: 889.3 pg/mL, and CXCL5; control: 1183.0 pg/mL vs. cancer: 977.5 pg/mL). CCL23 differed significantly within and between the races with a lower level in AA cancer cases (454.5 vs. 966.6 pg/mL) than healthy controls (740.5 vs. 1263.0 pg/mL). Patient age, prostate-specific antigen, or Gleason scores were not significantly associated with these chemokines. Immunostaining for CXCL5 and CCL23 in a representative cohort of archival prostate tissues displayed significantly higher CXCL5 in prostate tumors than in adjacent benign tissues, whereas CCL23 was nondetectable in most of the analyzed tumor tissues. CONCLUSION: Lower levels of CCL23 in AA prostate cancer patient sera and tumor tissues and high CXCL2 and CXCL5 may contribute to aggressive prostate cancer, as often seen in AA men. The disproportionate levels of serum chemokines associated with race warrant further exploration to improve equitability in precision oncology to benefit prostate cancer patients.

Astrocytic CXCL5 hinders microglial phagocytosis of myelin debris and aggravates white matter injury in chronic cerebral ischemia.

BACKGROUND: Chronic cerebral ischemia induces white matter injury (WMI) contributing to cognitive decline. Both astrocytes and microglia play vital roles in the demyelination and remyelination processes, but the underlying mechanism remains unclear. This study aimed to explore the influence of the chemokine CXCL5 on WMI and cognitive decline in chronic cerebral ischemia and the underlying mechanism. METHODS: Bilateral carotid artery stenosis (BCAS) model was constructed to mimic chronic cerebral ischemia in 7-10 weeks old male mice. Astrocytic Cxcl5 conditional knockout (cKO) mice were constructed and mice with Cxcl5 overexpressing in astrocytes were generated by stereotactic injection of adeno-associated virus (AAV). WMI was evaluated by magnetic resonance imaging (MRI), electron microscopy, histological staining and western blotting. Cognitive function was examined by a series of neurobehavioral tests. The proliferation and differentiation of oligodendrocyte progenitor cells (OPCs), phagocytosis of microglia were analyzed via immunofluorescence staining, western blotting or flow cytometry. RESULTS: CXCL5 was significantly elevated in the corpus callosum (CC) and serum in BCAS model, mainly expressed in astrocytes, and Cxcl5 cKO mice displayed improved WMI and cognitive performance. Recombinant CXCL5 (rCXCL5) had no direct effect on the proliferation and differentiation of OPCs in vitro. Astrocytic specific Cxcl5 overexpression aggravated WMI and cognitive decline induced by chronic cerebral ischemia, while microglia depletion counteracted this effect. Recombinant CXCL5 remarkably hindered microglial phagocytosis of myelin debris, which was rescued by inhibition of CXCL5 receptor C-X-C motif chemokine receptor 2 (CXCR2). CONCLUSION: Our study revealed that astrocyte-derived CXCL5 aggravated WMI and cognitive decline by inhibiting microglial phagocytosis of myelin debris, suggesting a novel astrocyte-microglia circuit mediated by CXCL5-CXCR2 signaling in chronic cerebral ischemia.

CXCL5 suppression recovers neovascularization and accelerates wound healing in diabetes mellitus.

BACKGROUND: Higher chemokine C-X-C motif ligand 5 (CXCL5) level was observed in type 2 diabetes mellitus (DM) patients; however, its role in diabetic vasculopathy was not clarified. This study aimed to explore the impacts and mechanistic insights of CXCL5 in neovasculogenesis and wound healing in DM. METHODS: Endothelial progenitor cells (EPCs) and human aortic endothelial cells (HAECs) were used in vitro. Streptozotocin-induced diabetic mice and Leprdb/JNarl mice were used as type 1 and type 2 DM models. Moreover, CXCL5 knockout mice were used to generate diabetic mice. Hindlimb ischemia surgery, aortic ring assays, matrigel plug assay, and wound healing assay were conducted. RESULTS: CXCL5 concentrations were increased in plasma and EPCs culture medium from type 2 DM patients. CXCL5 neutralizing antibody upregulated vascular endothelial growth factor (VEGF)/stromal cell-derived factor-1 (SDF-1) and promoted cell function in EPCs from type 2 DM patients and high glucose-treated EPCs from non-DM subjects as well as HAECs. CXCL5 directly up-regulated interleukin (IL)-1ß/IL-6/tumor necrosis factor-α and down-regulated VEGF/SDF-1 via ERK/p65 activation through chemokine C-X-C motif receptor 2 (CXCR2). CXCL5 neutralizing antibody recovered the blood flow after hindlimb ischemia, increased circulating EPC number, and enhanced VEGF and SDF-1 expression in ischemic muscle. CXCL5 suppression promoted neovascularization and wound healing in different diabetic animal models. The above observation could also be seen in streptozotocin-induced CXCL5 knockout diabetic mice. CONCLUSIONS: CXCL5 suppression could improve neovascularization and wound healing through CXCR2 in DM. CXCL5 may be regarded as a potential therapeutic target for vascular complications of DM.

CXCL5 promotes tumorigenesis and angiogenesis of glioblastoma via JAK-STAT/NF-κb signaling pathways.

BACKGROUND: The tumor microenvironment contains chemokines that play a crucial role in various processes, such as tumorigenesis, inflammation, and therapy resistance, in different types of cancer. CXCL5 is a significant chemokine that has been shown to promote tumor proliferation, invasion, angiogenesis, and therapy resistance when overexpressed in various types of cancer. This research aims to investigate the impact of CXCL5 on the biological functions of glioblastoma (GBM). METHODS: The TCGA GBM and GEO databases were utilized to perform transcriptome microarray analysis and oncogenic signaling pathway analysis of CXCL5 in GBM. Validation of CXCL5 expression was performed using RT-qPCR and Western Blot. The impact of CXCL5 on cell proliferation, tumorigenesis, and angiogenesis in GBM was assessed through various methods, including cell proliferation assay, cloning assay, intracranial xenograft tumor models, and tube formation assay. Clinical prognosis was evaluated in 59 samples of gliomas with varying degrees of malignancy (grades 2, 3, and 4) and the TCGA GBM database, based on CXCL5 expression levels. The activities of the JAK-STAT and NF-κB signaling pathways were detected using Western Blot. RESULTS: The expression of CXCL5 was highly enriched in GBM. Moreover, the inhibition of CXCL5 showed a significant efficacy in suppressing cellular proliferation and angiogenesis, resulting in extended survival rates in xenograft mouse models in comparison to the control group. Notably, pretreatment with dapsone exhibited a reversal of the impact of CXCL5 on the formation of colonies and tubes in GBM cells. Elevated expression of CXCL5 was correlated with poor outcomes in GBM patients. Furthermore, the overexpression of CXCL5 has been associated with the activation of JAK-STAT and NF-κB signaling pathways. CONCLUSIONS: CXCL5 plays an important role in tumorigenesis and angiogenesis, indicating the potential for novel therapies targeting CXCL5 in GBM.

Targeting CXCL5 in Pancreatic Cancer Cells Inhibits Cancer Xenograft Growth by Reducing Proliferation and Inhibiting EMT Progression.

BACKGROUND: Pancreatic cancer (PC) is the most lethal malignant tumor, with average survival period of about 10 months. C-X-C ligand 5 (CXCL5), an important chemokine for immune cell accumulation in tumor tissues, has been reported to be involved in a variety of human cancers. However, the exact role of CXCL5 in PC progression has not been well defined. METHODS: The expression of CXCL5 in PC was analyzed based on online databases and clinical specimens immunohistochemical staining, and Western blotting of CXCL5 in PC cell lines and patient samples. The correlation between CXCL5 expression and prognosis in PC was explored. The role of CXCL5 in PC was investigated through in vitro and in vivo experiments. RESULTS: The expression of CXCL5 was significantly increased in PC tissues compared with that in pancreas tissues, and CXCL5 high expression predicts poor prognosis in PC patients. Further analyses demonstrated that overexpression of CXCL5 in PC cells was positively related to higher proliferation rate, higher migration ability, and higher EMT markers including SNAI2 and TWIST1 of tumor cells in vitro. Consistently, the knockdown of CXCL5 in PC cells harmed the proliferation rate, migration ability, and expression of EMT indexes of tumor cells in vitro. Importantly, knockdown of CXCL5 inhibited the growth of xenograft tumors in vivo. CONCLUSION: CXCL5 high expression predicts poor prognosis in PC patients. CXCL5 promotes PC cell growth and EMT process. Inhibition of CXCL5 may be a potential therapeutic approach for PC.

CXCL5-mediated recruitment of neutrophils into the peritoneal cavity of Gdf15-deficient mice protects against abdominal sepsis.

Sepsis is a life-threatening organ dysfunction condition caused by a dysregulated host response to an infection. Here we report that the circulating levels of growth and differentiation factor-15 (GDF15) are strongly increased in septic shock patients and correlate with mortality. In mice, we find that peptidoglycan is a potent ligand that signals through the TLR2-Myd88 axis for the secretion of GDF15, and that Gdf15-deficient mice are protected against abdominal sepsis due to increased chemokine CXC ligand 5 (CXCL5)-mediated recruitment of neutrophils into the peritoneum, leading to better local bacterial control. Our results identify GDF15 as a potential target to improve sepsis treatment. Its inhibition should increase neutrophil recruitment to the site of infection and consequently lead to better pathogen control and clearance.

CXCL5 Promotes Acetaminophen-Induced Hepatotoxicity by Activating Kupffer Cells.

Kupffer cells (KCs) play a key part in the pathological process of acetaminophen (APAP)-induced acute liver injury (ALI), the leading cause of acute liver failure in the world. CXC motif chemokine ligand 5 (CXCL5) exerts proinflammatory effects in acute respiratory distress syndrome and arthritis. In the current study, we aim to reveal the effects of CXCL5 on the activation of KCs and the role of CXCL5 in the pathogenesis of APAP-induced hepatotoxicity. The in vivo study, conducted on mice intraperitoneally injected with APAP (300 mg/kg) to establish the ALI model and then treated with Anti-CXCL5 mAb at 30 min and 12 h after the APAP challenge, showed that CXCL5 expression significantly increased in injured livers, and Anti-CXCL5 mAb mitigated the degree of APAP-evoked ALI in mice which was proven through biochemicals and histological examination. Also, neutralization of CXCL5 had no significant effect on APAP metabolism in the liver but exhibited anti-inflammatory effects and ameliorated hepatocellular death in the injured liver. The in vitro data displayed that recombinant mouse CXCL5 treatment promoted APAP-induced cellular toxicity in primary hepatocytes co-cultured with KCs, compared with single-cultured hepatocytes. Consistent with the result, we found that the Anti-CXCL5 mAb gradient decreased LPS-induced expression of inflammatory cytokines in single-cultured KCs. Therefore, CXCL5 could stimulate KCs to produce inflammatory mediators, therefore damaging hepatocytes from APAP toxicity.

ETV2 Enhances CXCL5 Secretion from Endothelial Cells, Leading to the Promotion of Vascular Smooth Muscle Cell Migration.

Abnormal communication between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) promotes vascular diseases, including atherogenesis. ETS variant transcription factor 2 (ETV2) plays a substantial role in pathological angiogenesis and the reprogramming of ECs; however, the role of ETV2 in the communication between ECs and VSMCs has not been revealed. To investigate the interactive role of ETV2 in the EC to VSMC phenotype, we first showed that treatment with a conditioned medium from ETV2-overexpressed ECs (Ad-ETV2 CM) significantly increased VSMC migration. The cytokine array showed altered levels of several cytokines in Ad-ETV2 CM compared with those in normal CM. We found that C-X-C motif chemokine 5 (CXCL5) promoted VSMC migration using the Boyden chamber and wound healing assays. In addition, an inhibitor of C-X-C motif chemokine receptor 2 (CXCR2) (the receptor for CXCL5) significantly inhibited this process. Gelatin zymography showed that the activities of matrix metalloproteinase (MMP)-2 and MMP-9 increased in the media of VSMCs treated with Ad-ETV2 CM. Western blotting revealed a positive correlation between Akt/p38/c-Jun phosphorylation and CXCL5 concentration. The inhibition of Akt and p38-c-Jun effectively blocked CXCL5-induced VSMC migration. In conclusion, CXCL5 from ECs induced by ETV2 promotes VSMC migration via MMP upregulation and the activation of Akt and p38/c-Jun.

Serum CXCL5 Detects Early Hepatocellular Carcinoma and Indicates Tumor Progression.

Chemokines or chemotactic cytokines play a pivotal role in the immune pathogenesis of liver cirrhosis and hepatocellular carcinoma (HCC). Nevertheless, comprehensive cytokine profiling data across different etiologies of liver diseases are lacking. Chemokines might serve as diagnostic and prognostic biomarkers. In our study, we analyzed serum concentrations of 12 inflammation-related chemokines in a cohort of patients (n = 222) with cirrhosis of different etiologies and/or HCC. We compared 97 patients with cirrhosis and treatment-naïve HCC to the chemokine profile of 125 patients with cirrhosis but confirmed absence of HCC. Nine out of twelve chemokines were significantly elevated in sera of cirrhotic patients with HCC compared to HCC-free cirrhosis controls (CCL2, CCL11, CCL17, CCL20, CXCL1, CXCL5, CXCL9, CXCL10, CXCL11). Among those, CXCL5, CXCL9, CXCL10, and CXCL11 were significantly elevated in patients with early HCC according to the Barcelona Clinic Liver Cancer (BCLC) stages 0/A compared to cirrhotic controls without HCC. In patients with HCC, CXCL5 serum levels were associated with tumor progression, and levels of CCL20 and CXCL8 with macrovascular invasion. Importantly, our study identified CXCL5, CXCL9, and CXCL10 as universal HCC markers, independent from underlying etiology of cirrhosis. In conclusion, regardless of the underlying liver disease, patients with cirrhosis share an HCC-specific chemokine profile. CXCL5 may serve as a diagnostic biomarker in cirrhotic patients for early HCC detection as well as for tumor progression.

Crosstalk between tumor-associated macrophages and tumor cells promotes chemoresistance via CXCL5/PI3K/AKT/mTOR pathway in gastric cancer.

BACKGROUND: 5-fluorouracil (5-FU)-based chemotherapy regimen has been widely used for the treatment of gastric cancer, but meanwhile the development of chemotherapeutic resistance remains a major clinical challenge. Tumor microenvironment (TME) frequently correlates with the development of chemoresistance in human cancer. As a major component of TME, the role of tumor-associated macrophages (TAMs) in the chemoresistance of gastric cancer has not been fully elucidated. METHODS: Immunohistochemistry (IHC) was applied to detect the density of TAMs in clinical samples of 103 patients with gastric cancer who had undergone 5-FU-based neoadjuvant chemotherapy. 5-FU-resistant gastric cell lines MKN45-R and HGC27-R were established, macrophages were then separately co-cultured with MKN45-R, HGC27-R cells and their parental cells. The effect of gastric cancer cells on the polarization of macrophages, the biological function of M2-polaried macrophages and the mechanism for promoting 5-FU-resistance were investigated. Then the correlation between the expression of CXC motif chemokine ligand 5 (CXCL5) and the infiltration of hemoglobin scavenger receptor (CD163) positive and mannose receptor (CD206) positive macrophages was analyzed, the prognostic value of CXCL5 expression in clinical samples was further explored. RESULTS: The high infiltration of macrophages marked by CD68 in gastric cancer samples was significantly associated with the resistance of gastric cancer to chemotherapy. Gastric cancer cells could modulate macrophages to M2-like polarization through indirect co-culture, and chemoresistant cells were more efficient in inducing macrophages polarization to M2 phenotype. Co-culturing M2-polarized macrophages in turn enhanced 5-FU-resistance of gastric cancer cells, and it was further verified that CXCL5 derived from M2-polarized macrophages promoted chemoresistance through activing the PI3K/AKT/mTOR pathway. Besides, high level of CXCL5 could recruit monocytes to form more M2-polarized macrophages. Clinically, high expression of CXCL5 in gastric cancer samples was associated with the high infiltration of CD163 positive macrophages and CD206 positive macrophages, and patients with high expression of CXCL5 presented lower overall survival (OS) rates than those with low expression of CXCL5. CONCLUSION: Interaction between TAMs and gastric cancer cells promoted chemoresistance in gastric cancer via CXCL5/PI3K/AKT/mTOR pathway. Thus, targeting TAMs and blocking the cell-cell crosstalk between TAMs and gastric cancer cells may represent prospective therapeutic strategies for patients with gastric cancer.

Crosstalk between head and neck cancer cells and lymphatic endothelial cells promotes tumor metastasis via CXCL5-CXCR2 signaling.

Head and neck squamous cell carcinoma (HNSCC) metastasizes to the locoregional lymph nodes at high rates and is related to poor clinical outcomes. However, the mechanism by which cancer cells migrate to the lymph nodes is unclear. To address this, we established a conditioned medium culture system for HNSCC cells and lymphatic endothelial cells (LECs) and investigated their crosstalk. Stimulation with tumor-conditioned medium (TCM) activated LECs, resulting in a robust increase in cell proliferation to induce lymphatic hyperplasia. Further, stimulation of HNSCC cells with activated LEC Conditioned media (TCM-LEC CM) induced cell invasion. Among various chemokines, CXCL5 promoted the invasion of TCM-LEC CM-treated HNSCC cells. The level of CXCL5 protein was higher in cancer tissues than those in normal tissues from HNSCC patients. Furthermore, treatment with SB225002, a CXCR2 (CXCL5 receptor) inhibitor, resulted in decreased lymph node metastasis in vivo. In conclusion, inhibition of CXCL5-CXCR2 signaling between cancer cells and LECs suppresses cancer cell invasion and metastasis in vitro and in vivo. This novel therapeutic strategy might be a practical approach to the clinical management of HNSCC.

On the issue of diagnostic value of determining the level of receptors and their ligands in blood in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) occupies the first place in the structure of mortality due to oncological diseases. Late diagnosis worsens the effectiveness of its treatment. There are no informative biomarkers that allow us to judge the prevalence of the tumor process, especially in the early stages of NSCLC. To determine the level of CXCL5, CXCL8, CXCR1 and CXCR2 in the peripheral blood of patients with NSCLC to assess the possibility of their use in the diagnosis of the disease. The material was the blood of 218 patients with NSCLC, 19 patients with lung hamartoma and 42 healthy people. The concentration of CXCL5, CXCL8, and SCC in blood serum was determined by enzyme immunoassay, the CYFRA 21-1 level was determined by immunochemiluminescence analysis. The proportion of leukocytes equipped with CXCR1 and CXCR2 receptors and the fluorescence intensity of receptor complexes with antibodies (MFI) in them were measured by flow cytometry. MFI CXCR1 in granulocytes and the proportion of lymphocytes supplied CXCR2, increased in the blood already at stage I of NSCLC and showed an even more significant increase in subsequent stages. The level of these indicators was correlatively related to the stages and characteristics of NSCLC. Measuring the level of MFI CXCR1 in the blood serum makes it possible to diagnose the early stages of NSCLC with a sensitivity of 87.4% (specificity - 73.8%). Determination of the proportion of lymphocytes equipped with CXCR2 demonstrates comparable diagnostic sensitivity (87.2%) and specificity of 66.7% in the detection of stages I-II of NSCLC. MFI CXCR1 in granulocytes can also be used to differentiate stages I and II of NSCLC (diagnostic sensitivity - 75,3%, specificity - 69,6%). The sensitivity of determining for this purpose the proportion of lymphocytes equipped with CXCR2 is 75.0% with a specificity of 71.7%. In 89.7% of patients with stages III-IV NSCLC, the MFI CXCR1 in granulocytes exceeds the threshold value of 47.8 (specificity - 74.8%). Diagnostic sensitivity of determining the proportion of lymphocytes for this purpose was 90.7%.

Chronic restraint stress promotes the mobilization and recruitment of myeloid-derived suppressor cells through ß-adrenergic-activated CXCL5-CXCR2-Erk signaling cascades.

Myeloid-derived suppressor cells (MDSCs) play an important role in tumor immune escape. Recent studies have shown that MDSCs contribute to tumor progression under psychological stress, but the underlying mechanism of MDSCs mobilization and recruitment remains largely unknown. In the present study, a chronic restraint stress paradigm was applied to the H22 hepatocellular carcinoma (HCC) bearing mice to mimic the psychological stress. We observed that chronic restraint stress significantly promoted HCC growth, as well as the mobilization of MDSCs to spleen and tumor sites from bone marrow. Meanwhile, chronic restraint stress enhanced the expression of C-X-C motif chemokine receptor 2 (CXCR2) and pErk1/2 in bone marrow MDSCs, together with elevated chemokine (C-X-C motif) ligand 5 (CXCL5) expression in tumor tissues. In vitro, the treatments of MDSCs with epinephrine (EPI) and norepinephrine (NE) but not corticosterone (CORT)-treated H22 conditioned medium obviously inhibited T-cell proliferation, as well as enhanced CXCR2 expression and extracellular signal-regulated kinase (Erk) phosphorylation. In vivo, ß-adrenergic blockade with propranolol almost completely reversed the accelerated tumor growth induced by chronic restraint stress and inactivated CXCL5-CXCR2-Erk signaling pathway. Our findings support the crucial role of ß-adrenergic signaling cascade in the mobilization and recruitment of MDSCs under chronic restraint stress.