CXCL1 is a negative regulator of mast cell chemotaxis to airway smooth muscle cell products in vitro

The causality between systemic inflammatory regulators and chronic respiratory diseases: A bidirectional Mendelian-randomization study

INTRODUCTION

Accumulative evidence suggests the associations between systemic inflammatory regulators and chronic respiratory diseases (CRDs). However, the intrinsic causation remains implicit. Therefore, this study aimed to examine causative associations by mendelian randomization (MR) and to identify valuable active factors.

METHODS

Based on data from the GWAS database, we performed MR analyses of 41 serum cytokines from 8,293 Finnish and European descent cohorts from GBMI and UKBB for five major CRDs. We mainly applied inverse variance weighted regression, supplemented by MR-Egger regression, weighted median, maximum likelihood, weighted mode, and simple mode algorithms. Moreover, sensitivity analyses were conducted using Cochrane's Q test, MR-Egger intercept, MR-PRESSO Global test and MR-Steiger filtering. Eventually, the consistency of MR results was assessed by leave-one-out.

RESULTS

Our results suggest that 12 genetically predicted systemic inflammatory regulators probably participate in the progression of CRDs, including four risk factors (IL-1RA, IL-4, MIP-1A, PDGF-BB) and one protective factor (IL-6) in IPF, two protective factors (SCF, SDF-1A) in COPD, and two protective factors (SCF, SDF-1A) in asthma, two protective factors (GROA, IL-2RA) were also included in asthma, whereas only one factor (HGF) was protective against bronchiectasis. Additionally, two protective factors (FGF-BASIC, G-CSF) were identified in sarcoidosis. Sensitivity analyses showed no horizontal pleiotropy and significant heterogeneity. Finally, based on the findings of inverse MR analysis, no inverse causal association was uncovered, confirming the robustness of results.

CONCLUSION

Our study unearths potential associations between systemic inflammatory modulators and common CRDs, providing new insights for inflammation-mediated CRD prevention and therapeutic approaches.

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.

New perspectives in bronchial asthma: pathological, immunological alterations, biological targets, and pharmacotherapy

Asthma is the most common, long-lasting inflammatory airway disease that affects more than 10% of the world population. It is characterized by bronchial narrowing, airway hyperresponsiveness, vasodilatation, airway edema, and stimulation of sensory nerve endings that lead to recurring events of breathlessness, wheezing, chest tightness, and coughing. It is the main reason for global morbidity and occurs as a result of the weakening of the immune system in response to exposure to allergens or environmental exposure. In asthma condition, it results in the activation of numerous inflammatory cells like the mast and dendritic cells along with the accumulation of activated eosinophils and lymphocytes at the inflammation site. The structural cells such as airway epithelial cells and smooth muscle cells release inflammatory mediators that promote the bronchial inflammation. Long-lasting bronchial inflammation can cause pathological alterations, viz. the improved thickness of the bronchial epithelium and friability of airway epithelial cells, epithelium fibrosis, hyperplasia, and hypertrophy of airway smooth muscle, angiogenesis, and mucus gland hyperplasia. The stimulation of bronchial epithelial cell would result in the release of inflammatory cytokines and chemokines that attract inflammatory cells into bronchial airways and plays an important role in asthma. Asthma patients who do not respond to marketed antiasthmatic drugs needed novel biological medications to regulate the asthmatic situation. The present review enumerates various types of asthma, etiological factors, and in vivo animal models for the induction of asthma. The underlying pathological, immunological mechanism of action, the role of inflammatory mediators, the effect of inflammation on the bronchial airways, newer treatment approaches, and novel biological targets of asthma have been discussed in this review.

Nanoparticle-based thymulin gene therapy therapeutically reverses key pathology of experimental allergic asthma

Despite long-standing efforts to enhance care for chronic asthma, symptomatic treatments remain the only option to manage this highly prevalent and debilitating disease. We demonstrate that key pathology of allergic asthma can be almost completely resolved in a therapeutic manner by inhaled gene therapy. After the disease was fully and stably established, we treated mice intratracheally with a single dose of thymulin-expressing plasmids delivered via nanoparticles engineered to have a unique ability to penetrate the airway mucus barrier. Twenty days after the treatment, we found that all key pathologic features found in the asthmatic lung, including chronic inflammation, pulmonary fibrosis, and mechanical dysregulation, were normalized. We conducted tissue- and cell-based analyses to confirm that the therapeutic intervention was mediated comprehensively by anti-inflammatory and antifibrotic effects of the therapy. We believe that our findings open a new avenue for clinical development of therapeutically effective gene therapy for chronic asthma.

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.

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.

NF1+/- Hematopoietic Cells Accelerate Malignant Peripheral Nerve Sheath Tumor Development without Altering Chemotherapy Response

Haploinsufficiency in the tumor suppressor NF1 contributes to the pathobiology of neurofibromatosis type 1, but a related role has not been established in malignant peripheral nerve sheath tumors (MPNST) where NF1 mutations also occur. Patients with NF1-associated MPNST appear to have worse outcomes than patients with sporadic MPNST, but the mechanism underlying this correlation is not understood. To define the impact of stromal genetics on the biology of this malignancy, we developed unique mouse models that reflect the genetics of patient-associated MPNST. Specifically, we used adenovirus-Cre injections to generate MPNST in Nf1Flox/Flox; Ink4a/ArfFlox/Flox and Nf1Flox/-; Ink4a/ArfFlox/Flox paired littermate mice to model tumors from NF1-wild-type and NF1-associated patients, respectively. In these models, Nf1 haploinsufficiency in hematopoietic cells accelerated tumor onset and increased levels of tumor-infiltrating immune cells comprised of CD11b+ cells, monocytes, and mast cells. We observed that mast cells were also enriched in human NF1-associated MPNST. In a coclinical trial to examine how the tumor microenvironment influences the response to multiagent chemotherapy, we found that stromal Nf1 status had no effect. Taken together, our results clarify the role of the NF1-haploinsufficient tumor microenvironment in MPNST. Cancer Res; 77(16); 4486-97. ©2017 AACR.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Developments in the field of allergy in 2014 through the eyes of Clinical and Experimental Allergy

The pathogenesis of asthma continues to be a major topic of interest to our authors with reviews and original papers on the role of viruses, mechanisms of inflammation, biomarkers, and phenotypes of asthma being major topics. A number of papers described new treatments for asthma focusing on blocking the Th2 response reflecting the fact that two decades of work in this area is finally bearing fruit. The pathogenesis of chronic rhinosinusitis is a growing area of interest, but there has been less on the genetics of airways disease than in previous years possibly reflecting the degree of rigour (and therefore a smaller body of work), with which these sorts of studies are now being undertaken. There continues to be a wide range of papers dealing with mechanisms of allergic disease ranging from clinical-based studies to basic research and the use of in vivo animal models especially mice. As before, mechanisms and new approaches to immunotherapy are common themes. Several were published in the allergens section investigating modification of allergens to increase their effectiveness and reduce the risk of adverse events. Risk factors for allergic disease was a common theme in the epidemiology section and food allergy a common theme in clinical allergy with papers on the development of protocols to induce tolerance and attempts to find biomarkers to distinguish sensitization from allergic disease. This was another exciting year for the editors, and we hope the readers of the journal.

Pharmacological Therapy of Bronchial Asthma: The Role of Biologicals

Bronchial asthma is a heterogeneous, complex, chronic inflammatory and obstructive pulmonary disease driven by various pathways to present with different phenotypes. A small proportion of asthmatics (5-10%) suffer from severe asthma with symptoms that cannot be controlled by guideline therapy with high doses of inhaled steroids plus a second controller, such as long-acting β2 agonists (LABA) or leukotriene receptor antagonists, or even systemic steroids. The discovery and characterization of the pathways that drive different asthma phenotypes have opened up new therapeutic avenues for asthma treatment. The approval of the humanized anti-IgE antibody omalizumab for the treatment of severe allergic asthma has paved the way for other cytokine-targeting therapies, particularly those targeting interleukin (IL)-4, IL-5, IL-9, IL-13, IL-17, and IL-23 and the epithelium-derived cytokines IL-25, IL-33, and thymic stromal lymphopoietin. Knowledge of the molecular basis of asthma phenotypes has helped, and continues to help, the development of novel biologicals that target a diverse array of phenotype-specific molecular targets in patients suffering from severe asthma. This review summarizes potential therapeutic approaches that are likely to show clinical efficacy in the near future, focusing on biologicals as promising novel therapies for severe asthma.

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

Airway smooth muscle cell (ASMC) migration is an important mechanism postulated to play a role in airway remodeling in asthma. CXCL1 chemokine has been linked to tissue growth and metastasis. In this study, we present a detailed examination of the inhibitory effect of CXCL1 on human primary ASMC migration and the role of the decoy receptor, Duffy AgR for chemokines (DARC), in this inhibition. Western blots and pathway inhibitors showed that this phenomenon was mediated by activation of the ERK-1/2 MAPK pathway, but not p38 MAPK or PI3K, suggesting a biased selection in the signaling mechanism. Despite being known as a nonsignaling receptor, small interference RNA knockdown of DARC showed that ERK-1/2 MAPK activation was significantly dependent on DARC functionality, which, in turn, was dependent on the presence of heat shock protein 90 subunit α. Interestingly, DARC- or heat shock protein 90 subunit α-deficient ASMCs responded to CXCL1 stimulation by enhancing p38 MAPK activation and ASMC migration through the CXCR2 receptor. In conclusion, we demonstrated DARC's ability to facilitate CXCL1 inhibition of ASMC migration through modulation of the ERK-1/2 MAPK-signaling pathway.

Regulation of pulmonary inflammation by mesenchymal cells

Pulmonary inflammation and tissue remodelling are common elements of chronic respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and pulmonary hypertension (PH). In disease, pulmonary mesenchymal cells not only contribute to tissue remodelling, but also have an important role in pulmonary inflammation. This review will describe the immunomodulatory functions of pulmonary mesenchymal cells, such as airway smooth muscle (ASM) cells and lung fibroblasts, in chronic respiratory disease. An important theme of the review is that pulmonary mesenchymal cells not only respond to inflammatory mediators, but also produce their own mediators, whether pro-inflammatory or pro-resolving, which influence the quantity and quality of the lung immune response. The notion that defective pro-inflammatory or pro-resolving signalling in these cells potentially contributes to disease progression is also discussed. Finally, the concept of specifically targeting pulmonary mesenchymal cell immunomodulatory function to improve therapeutic control of chronic respiratory disease is considered.