CXCL1 inhibits airway smooth muscle cell migration through the decoy receptor Duffy antigen receptor for chemokines

A liver digital twin for in silico testing of cellular and inter-cellular mechanisms in regeneration after drug-induced damage

This communication presents a mathematical mechanism-based model of the regenerating liver after drug-induced pericentral lobule damage resolving tissue microarchitecture. The consequence of alternative hypotheses about the interplay of different cell types on regeneration was simulated. Regeneration dynamics has been quantified by the size of the damage-induced dead cell area, the hepatocyte density and the spatial-temporal profile of the different cell types. We use deviations of observed trajectories from the simulated system to identify branching points, at which the systems behavior cannot be explained by the underlying set of hypotheses anymore. Our procedure reflects a successful strategy for generating a fully digital liver twin that, among others, permits to test perturbations from the molecular up to the tissue scale. The model simulations are complementing current knowledge on liver regeneration by identifying gaps in mechanistic relationships and guiding the system toward the most informative (lacking) parameters that can be experimentally addressed.

Involvement in Tumorigenesis and Clinical Significance of CXCL1 in Reproductive Cancers: Breast Cancer, Cervical Cancer, Endometrial Cancer, Ovarian Cancer and Prostate Cancer

C-X-C motif chemokine ligand 1 (CXCL1) is a member of the CXC chemokine subfamily and a ligand for CXCR2. Its main function in the immune system is the chemoattraction of neutrophils. However, there is a lack of comprehensive reviews summarizing the significance of CXCL1 in cancer processes. To fill this gap, this work describes the clinical significance and participation of CXCL1 in cancer processes in the most important reproductive cancers: breast cancer, cervical cancer, endometrial cancer, ovarian cancer, and prostate cancer. The focus is on both clinical aspects and the significance of CXCL1 in molecular cancer processes. We describe the association of CXCL1 with clinical features of tumors, including prognosis, ER, PR and HER2 status, and TNM stage. We present the molecular contribution of CXCL1 to chemoresistance and radioresistance in selected tumors and its influence on the proliferation, migration, and invasion of tumor cells. Additionally, we present the impact of CXCL1 on the microenvironment of reproductive cancers, including its effect on angiogenesis, recruitment, and function of cancer-associated cells (macrophages, neutrophils, MDSC, and T_reg). The article concludes by summarizing the significance of introducing drugs targeting CXCL1. This paper also discusses the significance of ACKR1/DARC in reproductive cancers.

Endothelial ACKR1 is induced by neutrophil contact and down-regulated by secretion in extracellular vesicles

Atypical chemokine receptor-1 (ACKR1), previously known as the Duffy antigen receptor for chemokines, is a widely conserved cell surface protein that is expressed on erythrocytes and the endothelium of post-capillary venules. In addition to being the receptor for the parasite causing malaria, ACKR1 has been postulated to regulate innate immunity by displaying and trafficking chemokines. Intriguingly, a common mutation in its promoter leads to loss of the erythrocyte protein but leaves endothelial expression unaffected. Study of endothelial ACKR1 has been limited by the rapid down-regulation of both transcript and protein when endothelial cells are extracted and cultured from tissue. Thus, to date the study of endothelial ACKR1 has been limited to heterologous over-expression models or the use of transgenic mice. Here we report that exposure to whole blood induces ACKR1 mRNA and protein expression in cultured primary human lung microvascular endothelial cells. We found that contact with neutrophils is required for this effect. We show that NF-κB regulates ACKR1 expression and that upon removal of blood, the protein is rapidly secreted by extracellular vesicles. Finally, we confirm that endogenous ACKR1 does not signal upon stimulation with IL-8 or CXCL1. Our observations define a simple method for inducing endogenous endothelial ACKR1 protein that will facilitate further functional studies.

The Potential Importance of CXCL1 in the Physiological State and in Noncancer Diseases of the Cardiovascular System, Respiratory System and Skin

In this paper, we present a literature review of the role of CXC motif chemokine ligand 1 (CXCL1) in physiology, and in selected major non-cancer diseases of the cardiovascular system, respiratory system and skin. CXCL1, a cytokine belonging to the CXC sub-family of chemokines with CXC motif chemokine receptor 2 (CXCR2) as its main receptor, causes the migration and infiltration of neutrophils to the sites of high expression. This implicates CXCL1 in many adverse conditions associated with inflammation and the accumulation of neutrophils. The aim of this study was to describe the significance of CXCL1 in selected diseases of the cardiovascular system (atherosclerosis, atrial fibrillation, chronic ischemic heart disease, hypertension, sepsis including sepsis-associated encephalopathy and sepsis-associated acute kidney injury), the respiratory system (asthma, chronic obstructive pulmonary disease (COPD), chronic rhinosinusitis, coronavirus disease 2019 (COVID-19), influenza, lung transplantation and ischemic-reperfusion injury and tuberculosis) and the skin (wound healing, psoriasis, sunburn and xeroderma pigmentosum). Additionally, the significance of CXCL1 is described in vascular physiology, such as the effects of CXCL1 on angiogenesis and arteriogenesis.

Mudaliar S, A. Phillips S, R. Henry R. Adipose tissue from subjects with type 2 diabetes exhibits impaired capillary formation in response to GROα: involvement of MMPs-2 and -9

Type 2 Diabetes (T2D) is associated with impaired vascularization of adipose tissue (AT) . IL8, GROα and IL15 are pro-angiogenic myokines, secreted at elevated levels by T2D myotubes. We explored the direct impact of these myokines on AT vascularization. AT explants from subjects with T2D and without diabetes (non-diabetic, ND) were treated with rIL8, rGROα and rIL15 in concentrations equal to those in conditioned media (CM) from T2D and ND myotubes, and sprout formation evaluated. Endothelial cells (EC) were isolated from T2D and ND-AT, treated with rGROα and tube formation evaluated. Finally, we investigated the involvement of MMP-2 and -9 in vascularization. ND and T2D concentrations of IL8 or IL15   caused similar stimulation of sprout formation in ND- and T2D-AT. GROα exerted a similar effect in ND-AT. When T2D-AT explants were exposed to GROα, sprout formation in response to T2D concentrations was reduced compared to ND. Exposure of EC from T2D-AT to GROα at T2D concentrations resulted in reduced tube formation. Reduced responses to GROα in T2D-AT and EC were also seen for secretion of MMP-2 and -9. The data indicate that skeletal muscle can potentially regulate AT vascularization, with T2D-AT having impairments in sensitivity to GROα, while responding normally to IL8 and IL15.

CXCL1: Gene, Promoter, Regulation of Expression, mRNA Stability, Regulation of Activity in the Intercellular Space

CXCL1 is one of the most important chemokines, part of a group of chemotactic cytokines involved in the development of many inflammatory diseases. It activates CXCR2 and, at high levels, CXCR1. The expression of CXCL1 is elevated in inflammatory reactions and also has important functions in physiology, including the induction of angiogenesis and recruitment of neutrophils. Due to a lack of reviews that precisely describe the regulation of CXCL1 expression and function, in this paper, we present the mechanisms of CXCL1 expression regulation with a special focus on cancer. We concentrate on the regulation of CXCL1 expression through the regulation of CXCL1 transcription and mRNA stability, including the involvement of NF-κB, p53, the effect of miRNAs and cytokines such as IFN-γ, IL-1β, IL-17, TGF-β and TNF-α. We also describe the mechanisms regulating CXCL1 activity in the extracellular space, including proteolytic processing, CXCL1 dimerization and the influence of the ACKR1/DARC receptor on CXCL1 localization. Finally, we explain the role of CXCL1 in cancer and possible therapeutic approaches directed against this chemokine.

Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia

Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.

Cytokine Levels in Inner Ear Fluid of Young and Aged Mice as Molecular Biomarkers of Noise-Induced Hearing Loss

Sensorineural hearing loss (SNHL) is the most common sensory deficit worldwide, frequently caused by noise trauma and aging, with inflammation being implicated in both pathologies. Here, we provide the first direct measurements of proinflammatory cytokines in inner ear fluid, perilymph, of adolescent and 2-year-old mice. The perilymph of adolescent mice exposed to the noise intensity resulting in permanent auditory threshold elevations had significantly increased levels of IL-6, TNF-α, and CXCL1 6 h after exposure, with CXCL1 levels being most elevated (19.3 ± 6.2 fold). We next provide the first immunohistochemical localization of CXCL1 in specific cochlear supporting cells, and its presumed receptor, Duffy antigen receptor for chemokines (DARC), in hair cells and spiral ganglion neurons. Our results demonstrate the feasibility of molecular diagnostics of SNHL using only 0.5 μL of perilymph, and motivate future sub-μL based diagnostics of human SNHL based on liquid biopsy of the inner ear to guide therapy, promote hearing protection, and monitor response to treatment.

CXCL1 stimulates migration and invasion in ER‑negative breast cancer cells via activation of the ERK/MMP2/9 signaling axis

Chemokine (C‑X‑C motif) ligand 1 (CXCL1), a member of the CXC chemokine family, has been reported to be a critical factor in inflammatory diseases and tumor progression; however, its functions and molecular mechanisms in estrogen receptor α (ER)‑negative breast cancer (BC) remain largely unknown. The present study demonstrated that CXCL1 was upregulated in ER‑negative BC tissues and cell lines compared with ER‑positive tissues and cell lines. Treatment with recombinant human CXCL1 protein promoted ER‑negative BC cell migration and invasion in a dose‑dependent manner, and stimulated the activation of phosphorylated (p)‑ extracellular signal‑regulated kinase (ERK)1/2, but not p‑STAT3 or p‑AKT. Conversely, knockdown of CXCL1 in BC cells attenuated these effects. Additionally, CXCL1 increased the expression of matrix metalloproteinase (MMP)2/9 via the ERK1/2 pathway. Inhibition of MEK1/2 by its antagonist U0126 reversed the effects of CXCL1 on MMP2/9 expression. Furthermore, immunohistochemical analysis revealed a strong positive association between CXCL1 and p‑ERK1/2 expression levels in BC tissues. In conclusion, the present study demonstrated that CXCL1 is highly expressed in ER‑negative BC, and stimulates BC cell migration and invasion via the ERK/MMP2/9 pathway. Therefore, CXCL1 may serve as a potential therapeutic target in ER‑negative BC.

Airway remodelling and inflammation in asthma are dependent on the extracellular matrix protein fibulin-1c

Asthma is a chronic inflammatory disease of the airways. It is characterized by allergic airway inflammation, airway remodelling, and airway hyperresponsiveness (AHR). Asthma patients, in particular those with chronic or severe asthma, have airway remodelling that is associated with the accumulation of extracellular matrix (ECM) proteins, such as collagens. Fibulin-1 (Fbln1) is an important ECM protein that stabilizes collagen and other ECM proteins. The level of Fbln1c, one of the four Fbln1 variants, which predominates in both humans and mice, is increased in the serum and airways fluids in asthma but its function is unclear. We show that the level of Fbln1c was increased in the lungs of mice with house dust mite (HDM)-induced chronic allergic airway disease (AAD). Genetic deletion of Fbln1c and therapeutic inhibition of Fbln1c in mice with chronic AAD reduced airway collagen deposition, and protected against AHR. Fbln1c-deficient (Fbln1c^-/- ) mice had reduced mucin (MUC) 5 AC levels, but not MUC5B levels, in the airways as compared with wild-type (WT) mice. Fbln1c interacted with fibronectin and periostin that was linked to collagen deposition around the small airways. Fbln1c^-/- mice with AAD also had reduced numbers of α-smooth muscle actin-positive cells around the airways and reduced airway contractility as compared with WT mice. After HDM challenge, these mice also had fewer airway inflammatory cells, reduced interleukin (IL)-5, IL-13, IL-33, tumour necrosis factor (TNF) and CXCL1 levels in the lungs, and reduced IL-5, IL-33 and TNF levels in lung-draining lymph nodes. Therapeutic targeting of Fbln1c reduced the numbers of GATA3-positive Th2 cells in the lymph nodes and lungs after chronic HDM challenge. Treatment also reduced the secretion of IL-5 and IL-13 from co-cultured dendritic cells and T cells restimulated with HDM extract. Human epithelial cells cultured with Fbln1c peptide produced more CXCL1 mRNA than medium-treated controls. Our data show that Fbln1c may be a therapeutic target in chronic asthma. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

CXCL6 is an important paracrine factor in the pro-angiogenic human cardiac progenitor-like cell secretome

Studies in recent years have established that the principal effects in cardiac cell therapy are associated with paracrine/autocrine factors. We combined several complementary techniques to define human cardiac progenitor cell (CPC) secretome constituted by 914 proteins/genes; 51% of these are associated with the exosomal compartment. To define the set of proteins specifically or highly differentially secreted by CPC, we compared human mesenchymal stem cells and dermal fibroblasts; the study defined a group of growth factors, cytokines and chemokines expressed at high to medium levels by CPC. Among them, IL-1, GROa (CXCL1), CXCL6 (GCP2) and IL-8 are examples whose expression was confirmed by most techniques used. ELISA showed that CXCL6 is significantly overexpressed in CPC conditioned medium (CM) (18- to 26-fold) and western blot confirmed expression of its receptors CXCR1 and CXCR2. Addition of anti-CXCL6 completely abolished migration in CPC-CM compared with anti-CXCR2, which promoted partial inhibition, and anti-CXCR1, which was inefficient. Anti-CXCL6 also significantly inhibited CPC CM angiogenic activity. In vivo evaluation also supported a relevant role for angiogenesis. Altogether, these results suggest a notable angiogenic potential in CPC-CM and identify CXCL6 as an important paracrine factor for CPC that signals mainly through CXCR2.

The Duffy antigen receptor for chemokines regulates asthma pathophysiology

BACKGROUND

The Duffy antigen receptor for chemokines (DARC) is an atypical receptor that regulates pro-inflammatory cytokines. However, the role of DARC in asthma pathophysiology is unknown.

OBJECTIVE

To determine the role of DARC in allergic airways disease in mice, and the association between DARC single nucleotide polymorphisms (SNPs) and clinical outcomes in patients with asthma.

METHODS

Mice with targeted disruption of the Darc gene (Darc∆E2 ) or WT mice were challenged over 3 weeks with house dust mite (HDM) antigen. Allergic airways disease was assessed 24 hours and 7 days following the final challenge. Additionally, associations between DARC SNPs and clinical outcomes were analysed in a cohort of poorly controlled asthmatics.

RESULTS

Total airway inflammation following HDM did not differ between Darc∆E2 and WT mice. At 24 hours, Darc∆E2 mice had increased airway hyperresponsiveness; however, at 7 days airway hyperresponsiveness had completely resolved in Darc∆E2 but persisted in WT mice. In poorly controlled asthmatics, DARC SNPs were associated with worse asthma control at randomization and subsequent increased risk of healthcare utilization (odds ratio 3.13(1.37-7.27), P=.0062).

CONCLUSIONS AND CLINICAL RELEVANCE

Our animal model and human patient data suggest a novel role for DARC in the temporal regulation in asthma pathophysiology and symptoms.

Overview and potential unifying themes of the atypical chemokine receptor family

Chemokines modulate immune responses through their ability to orchestrate the migration of target cells. Chemokines directly induce cell migration through a distinct set of 7 transmembrane domain G protein-coupled receptors but are also recognized by a small subfamily of atypical chemokine receptors, characterized by their inability to support chemotactic activity. Atypical chemokine receptors are now emerging as crucial regulatory components of chemokine networks in a wide range of physiologic and pathologic contexts. Although a new nomenclature has been approved recently to reflect their functional distinction from their conventional counterparts, a systematic view of this subfamily is still missing. This review discusses their biochemical and immunologic properties to identify potential unifying themes in this emerging family.

Differential Effects of Insulin-Like Growth Factor Binding Protein-6 (IGFBP-6) on Migration of Two Ovarian Cancer Cell Lines

INTRODUCTION

IGFBP-6 inhibits angiogenesis as well as proliferation and survival of rhabdomyosarcoma cells. However, it promotes migration of these cells in an IGF-independent manner. The IGF system is implicated in ovarian cancer, so we studied the effects of IGFBP-6 in ovarian cancer cells.

METHODS

The effects of wild type (wt) and a non-IGF-binding mutant (m) of IGFBP-6 on migration of HEY and SKOV3 ovarian cancer cells, which, respectively, represent aggressive and transitional cancers, were studied. ERK and JNK phosphorylation were measured by Western blotting.

RESULTS

IGF-II, wt-, and mIGFBP-6 each promoted SKOV3 cell migration by 77-98% (p < 0.01). In contrast, IGF-II also increased HEY cell migration to 155 ± 13% of control (p < 0.001), but wt-IGFBP-6 and mIGFBP-6 decreased migration to 62 ± 5 and 66 ± 3%, respectively (p < 0.001). In these cells, coincubation of IGF-II with wt but not mIGFBP-6 increased migration. MAP kinase pathways are involved in IGFBP-6-induced rhabdomyosarcoma cell migration, so activation of these pathways was studied in HEY and SKOV3 cells. Wt and mIGFBP-6 increased ERK phosphorylation by 62-99% in both cell lines (p < 0.05). Wt-IGFBP-6 also increased JNK phosphorylation by 139-153% in both cell lines (p < 0.05), but the effect of mIGFBP-6 was less clear. ERK and JNK inhibitors partially inhibited the migratory effects of wt and mIGFBP-6 in SKOV3 cells, whereas the ERK inhibitor partially restored wt and mIGFBP-6-induced inhibition of HEY cell migration. The JNK inhibitor had a lesser effect on the actions of wtIGFBP-6 and no effect on the actions of mIGFBP-6 in HEY cells.

CONCLUSION

IGFBP-6 has opposing effects on migration of HEY and SKOV3 ovarian cancer cells, but activates MAP kinase pathways in both. Delineating the pathways underlying the differential effects on migration will increase our understanding of ovarian cancer metastasis and shed new light on the IGF-independent effects of IGFBP-6.