Cxcl17-/- mice develop exacerbated disease in a T cell-dependent autoimmune model

Recombinant CXCL17 Treatment Alleviates Hyperoxia-Induced Lung Apoptosis and Inflammation In Vivo and Vitro by Activating the AKT Pathway: A Possible Therapeutic Approach for Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD), caused by hyperoxia exposure, is the most common complication affecting preterm infants. The C-X-C motif chemokine ligand 17 (CXCL17) belongs to the chemokine family that plays important roles in various processes, but the function in BPD is unknown. Elevated serum CXCL17 levels were observed in human premature infants with hyperoxia-induced lung injury, suggesting that CXCL17 might be involved in BPD. To further validate our speculation, studies were conducted in a hyperoxia-induced lung injury mouse model and primary murine alveolar epithelial cells Type II (T2AEC) cells exposed to hyperoxia. RT-qPCR and western blot were used to validate CXCL17 expression in newborn mice. Hyperoxia exposure-induced lung injury was determined by assessing the lung wet-weight/dry-weight ratio and histological changes. Oxidative stress and inflammatory factors were examined by ELISA assay and RT-qPCR. Reactive oxygen species (ROS) level was evaluated by DHE staining. Apoptosis was assessed by TUNEL staining and western blot. The results showed that hyperoxia exposure increased CXCL17 levels in newborn mice pups. Hyperoxia exposure increased lung wet-weight/dry-weight ratio, increased alveolar diameter and enlarged alveoli, and reduced surfactant protein C expression. However, recombinant CXCL17 (rCXCL17) treatment alleviated hyperoxia-induced lung injury. rCXCL17 treatment inhibited hyperoxia-induced inflammation, oxidative stress, and apoptosis in neonatal mice. These results were further verified in T2AEC cells. Additionally, rCXCL17 treatment activated the AKT pathway, which is a protective pathway in BPD. Collectively, rCXCL17 alleviates hyperoxia-induced lung injury in neonatal mice by activating the AKT pathway, indicating that CXCL17 may be a promising target for BPD therapy.

CXCL17 is a proinflammatory chemokine and promotes neutrophil trafficking

CXCL17, a novel member of the CXC chemokine class, has been implicated in several human pathologies, but its role in mediating immune response is not well understood. Characteristic features of immune response include resident macrophages orchestrating successive and structured recruitment of neutrophils and monocytes to the insult site. Here, we show that Cxcl17 knockout (KO) mice, compared with the littermate wild-type control mice, were significantly impaired in peritoneal neutrophil recruitment post-lipopolysaccharide (LPS) challenge. Further, the KO mice show dysregulated Cxcl1, Cxcr2, and interleukin-6 levels, all of which directly impact neutrophil recruitment. Importantly, the KO mice showed no difference in monocyte recruitment post-LPS challenge or in peritoneal macrophage levels in both unchallenged and LPS-challenged mice. We conclude that Cxcl17 is a proinflammatory chemokine and that it plays an important role in the early proinflammatory response by promoting neutrophil recruitment to the insult site.

CXCL17 binds efficaciously to glycosaminoglycans with the potential to modulate chemokine signaling

Introduction

CXCL17 is a mucosally secreted protein, and the most recently identified human chemokine, an assignment based on protein fold prediction and chemotactic activity for leukocytes. However, these credentials have been the subject of much recent discussion and no experimental evidence has been presented regarding the definitive structure of CXCL17. In this study, we evaluated the structural and chemoattractant credentials of CXCL17 to better characterize this molecule, and gain deeper insights into its functional role as a glycosaminoglycan (GAG) binding protein.

Methods

In the absence of structural information, in silico modeling techniques assessed the likelihood of CXCL17 adopting a chemokine fold. Recombinant CXCL17 was synthesized in mammalian and prokaryotic systems. Modified Boyden chamber and real-time chemotaxis assays assessed the ability of CXCL17 to promote chemotaxis of murine splenocytes, human neutrophils, and CXCR1 transfectants. The efficacy of CXCL17 binding to GAGs was quantified with solid-phase assays and bio-layer interferometry techniques.

Results

All modeling efforts failed to support classification of CXCL17 as a chemokine based on its predicted conformation. Recombinant CXCL17 was observed to dimerize as a function of concentration, a characteristic of several chemokines. Contrary to a previous report, CXCL17 was not chemotactic for murine splenocytes, although it was a low-potency chemoattractant for human neutrophils at micromolar concentrations, several orders of magnitude higher than those required for CXCL8. As anticipated owing to its highly basic nature, CXCL17 bound to GAGs robustly, with key C-terminal motifs implicated in this process. While inactive via CXCR1, CXCL17 was found to inhibit CXCR1-mediated chemotaxis of transfectants to CXCL8 in a dose-dependent manner.

Discussion

In summary, despite finding little evidence for chemokine-like structure and function, CXCL17 readily bound GAGs, and could modulate chemotactic responses to another chemokine in vitro. We postulate that such modulation is a consequence of superior GAG binding, and that C-terminal fragments of CXCL17 may serve as prototypic inhibitors of chemokine function.

The cryptic role of CXCL17/CXCR8 axis in the pathogenesis of cancers: a review of the latest evidence

Chemokines are immune system mediators that mediate various activities and play a role in the pathogenesis of several cancers. Among these chemokines, C-X-C motif chemokine 17 (CXCL-17) is a relatively novel molecule produced along the airway epithelium in physiological and pathological conditions, and evidence shows that it plays a homeostatic role in most cases. CXCL17 has a protective role in some cancers and a pathological role in others, such as liver and lung cancer. This chemokine, along with its possible receptor termed G protein-coupled receptor 35 (GPR35) or CXCR8, are involved in recruiting myeloid cells, regulating angiogenesis, defending against pathogenic microorganisms, and numerous other mechanisms. Considering the few studies that have been performed on the dual role of CXCL17 in human malignancies, this review has investigated the possible pro-tumor and anti-tumor roles of this chemokine, as well as future treatment options in cancer therapy.

Effect of CXCL17 on Subcutaneous Preadipocytes Proliferation in Goats

The presence or absence of subcutaneous adipose accumulation will affect the energy storage, insulation resistance and metabolism of animals. Proliferation and differentiation of preadipocytes play a significant role in lipid deposition. The objective of this study was to clone the goat CXCL17 gene and investigate its potential functions on goat subcutaneous preadipocytes' proliferation by gaining or losing function in vitro. The goat CXCL17 gene was cloned by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and bioinformatics analysis was performed. The expression of the CXCL17 gene in the different goat tissues and adipocytes at different differentiation stages was detected by real-time fluorescence quantitative PCR (qPCR). The results showed that the cloned sequence of goat CXCL17 gene is 728 bp and the CDS region is 357 bp, encoding 118 amino acids. CXCL17 protein is located in nucleus, cytoplasm, mitochondria and extracellular matrix. Tissue-expression profiles revealed that CXCL17 expressed in all of the examined tissues. In visceral tissues, the highest expression level was found in lung (p < 0.01); in muscle tissues, the highest CXCL17 expression level was found in the longissimus dorsi (p < 0.01) and in adipose tissues, the highest expression level was found in subcutaneous adipose (p <0.01). Compared with those cells before differentiation, CXCL17 expression levels upregulated at 48 h (p < 0.01), 72 h (p < 0.01), 120 h (p < 0.01) and downregulated at 96 h (p < 0.01). Furthermore, the results of crystal violet staining and semi-quantitative assay showed that transfection with 1 μg CXCL17 expression plasmid reduced the cell numbers in vitro. Meanwhile, the expression of CCND1 was significantly decreased. A similar consequence happened after interfering with CXCL17 expression. However, plasmid transfected with 2 μg pEGFPN1-CXCL17 increased the number of cells in vitro. These results suggest that CXCL17 is involved in the proliferation of goat subcutaneous preadipocytes.

A comprehensive review of chemokine CXC17 (VCC1) in cancer, infection, and inflammation

A crucial component of the immune system are chemokiness. Chemokine's dysregulation has been linked to a number of pathological diseases. Recently, CXCL17, a chemokine belonging to the CXC subfamily, was identified. With regard to a number of physiological conditions and disorders, CXCL17 either has homeostatic or pathogenic effects. Some research suggests that CXCL17 is an orphan ligand, despite the fact that G protein-coupled receptor (GPR) 35 has been suggested as a possible receptor for CXCL17. Since CXCL17 is primarily secreted by mucosal epithelia, such as those in the digestive and respiratory tracts, under physiological circumstances, this chemokine is referred to as a mucosal chemokine. Macrophages and monocytes are the cells that express GPR35 and hence react to CXCL17. In homeostatic conditions, this chemokine has anti-inflammatory, antibacterial, and chemotactic properties. CXCL17 promotes angiogenesis, metastasis, and cell proliferation in pathologic circumstances like malignancies. However, other studies suggest that CXCL17 may have anti-tumor properties. Additionally, studies have shown that CXCL17 may have a role in conditions such as idiopathic pulmonary fibrosis, multiple sclerosis, asthma, and systemic sclerosis. Additionally, deregulation of CXCL17 in some diseases may serve as a biomarker for diagnosis and prognosis. Clarifying the underlying mechanism of CXCL17's activity in homeostatic and pathological situations may thus increase our understanding of its role and hold promise for the development of novel treatment strategies.

Expression and clinical significance of CXCL17 and GPR35 in endometrial carcinoma

Endometrial carcinoma is one of the most common gynecologic malignancies. CXCL17-CXCR8 (GPR35) axis is reported to play an indispensability role in tumors. Our purpose is to screen possible prognostic and immune-related factors in endometrial carcinoma by detecting the mRNA and protein expression of CXCL17 and CXCR8. We use the qRT-PCR method to test the mRNA expression of CXCL17 and CXCR8 in 35 pairs of endometrial carcinoma and adjacent tissue. The protein expression of CXCL17 and CXCR8 in 30 cases of normal proliferative endometrium, 30 cases of endometrial atypical hyperplasia and 50 cases of endometrial carcinoma was detected by tissue microarray immunohistochemistry. There was no significant difference in the positive expression rate between endometrial adenocarcinoma tissue and endometrial atypical hyperplasia tissue (P > 0.05). But significantly better than normal proliferative tissue (P < 0.001). Correlation analysis of CXCR8 and CXCL17 in endometrial carcinoma showed a positive correlation (r = 0.9123, P < 0.0001). For patients with endometrial cancer, the overall survival (OS) of patients with high CXCL17 expression was significantly higher than that low CXCL17 expression (log-rank test, P < 0.0001), whereas CXCR8 had no statistical significance. But the expression of CXCR8 is an independent prognostic factor of OS in endometrial carcinoma patients. Our study showed that CXCL17 and CXCR8 may be involved in the occurrence and development of endometrial cancer. High expression of CXCL17 may be used as a biomarker for predicting survival. Because CXCL17 and CXCL18 are related to lymphocytes and immune regulation, they are expected to become potential targets for immunotherapy.

CXCL17 Is a Specific Diagnostic Biomarker for Severe Pandemic Influenza A(H1N1) That Predicts Poor Clinical Outcome

The C-X-C motif chemokine ligand 17 (CXCL17) is chemotactic for myeloid cells, exhibits bactericidal activity, and exerts anti-viral functions. This chemokine is constitutively expressed in the respiratory tract, suggesting a role in lung defenses. However, little is known about the participation of CXCL17 against relevant respiratory pathogens in humans. Here, we evaluated the serum levels and lung tissue expression pattern of CXCL17 in a cohort of patients with severe pandemic influenza A(H1N1) from Mexico City. Peripheral blood samples obtained on admission and seven days after hospitalization were processed for determinations of serum CXCL17 levels by enzyme-linked immunosorbent assay (ELISA). The expression of CXCL17 was assessed by immunohistochemistry (IHQ) in lung autopsy specimens from patients that succumbed to the disease. Serum CXCL17 levels were also analyzed in two additional comparative cohorts of coronavirus disease 2019 (COVID-19) and pulmonary tuberculosis (TB) patients. Additionally, the expression of CXCL17 was tested in lung autopsy specimens from COVID-19 patients. A total of 122 patients were enrolled in the study, from which 68 had pandemic influenza A(H1N1), 24 had COVID-19, and 30 with PTB. CXCL17 was detected in post-mortem lung specimens from patients that died of pandemic influenza A(H1N1) and COVID-19. Interestingly, serum levels of CXCL17 were increased only in patients with pandemic influenza A(H1N1), but not COVID-19 and PTB. CXCL17 not only differentiated pandemic influenza A(H1N1) from other respiratory infections but showed prognostic value for influenza-associated mortality and renal failure in machine-learning algorithms and regression analyses. Using cell culture assays, we also identified that human alveolar A549 cells and peripheral blood monocyte-derived macrophages increase their CXCL17 production capacity after influenza A(H1N1) pdm09 virus infection. Our results for the first time demonstrate an induction of CXCL17 specifically during pandemic influenza A(H1N1), but not COVID-19 and PTB in humans. These findings could be of great utility to differentiate influenza and COVID-19 and to predict poor prognosis specially at settings of high incidence of pandemic A(H1N1). Future studies on the role of CXCL17 not only in severe pandemic influenza, but also in seasonal influenza, COVID-19, and PTB are required to validate our results.

Immune Escape in Prostate Cancer: Known and Predicted Mechanisms and Targets

Complex immune evasion mechanisms and lack of biomarkers predicting responsiveness to immune checkpoint blockade therapies compromise immunotherapy's therapeutic efficacy for patients with prostate cancer. The authors review established and nominated immune evasion mechanisms in prostate cancer and discuss how the precise treatment strategies can be developed to improve efficacy of immunotherapy.

Mucosal chemokine CXCL17: What is known and not known

CXCL17, the last described chemokine, has recently been found to be abundantly and specifically expressed in mucosal sites, while its receptor is still not well determined. Accumulative studies indicate that CXCL17 could potentially exhibit chemotactic, anti-inflammatory, antimicrobial activities under multiple biological conditions. However, the mechanism by which it contributes to the physiological and pathological processes within specific mucosal tissues is still far from being fully elucidated. In this present review, we therefore summarize the current available evidence of CXCL17 with specific emphasis on its biological role and pathophysiological significance, in order to aid in the advancement of CXCL17-related studies.

The protective and pathogenic roles of CXCL17 in human health and disease: Potential in respiratory medicine

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C-X-C motif chemokine 17 (CXCL17), plays a functional role in maintaining homeostasis at mucosal barriers.

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CXCL17 expression is associated with both disease progression and protection in various diseases.

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The multifactorial mechanistic properties of CXCL17 could be exploited as a therapeutic target

C-X-C motif chemokine 17 (CXCL-17) is a novel chemokine that plays a functional role maintaining homeostasis at distinct mucosal barriers, including regulation of myeloid-cell recruitment, angiogenesis, and control of microorganisms. Particularly, CXCL17 is produced along the epithelium of the airways both at steady state and under inflammatory conditions. While increased CXCL17 expression is associated with disease progression in pulmonary fibrosis, asthma, and lung/hepatic cancer, it is thought to play a protective role in pancreatic cancer, autoimmune encephalomyelitis and viral infections. Thus, there is emerging evidence pointing to both a harmful and protective role for CXCL17 in human health and disease, with therapeutic potential for translational applications. In this review, we provide an overview of the discovery, characteristics and functions of CXCL17 emphasizing its clinical potential in respiratory disorders.