Role of proteinase-activated receptor-2 in anti-bacterial and immunomodulatory effects of interferon-γ on human neutrophils and monocytes

The Complex Role of Thrombin in Cancer and Metastasis: Focus on Interactions with the Immune System

Thrombin, a pleiotropic enzyme involved in coagulation, plays a crucial role in both procoagulant and anticoagulant pathways. Thrombin converts fibrinogen into fibrin, initiates platelet activation, and promotes clot formation. Thrombin also activates anticoagulant pathways, indirectly inhibiting factors involved in coagulation. Tissue factor triggers thrombin generation, and the overexpression of thrombin in various cancers suggests that it is involved in tumor growth, angiogenesis, and metastasis. Increased thrombin generation has been observed in cancer patients, especially those with metastases. Thrombin exerts its effects through protease-activated receptors (PARs), particularly PAR-1 and PAR-2, which are involved in cancer progression, angiogenesis, and immunological responses. Thrombin-mediated signaling promotes angiogenesis by activating endothelial cells and platelets, thereby releasing proangiogenic factors. These functions of thrombin are well recognized and have been widely described. However, in recent years, intriguing new findings concerning the association between thrombin activity and cancer development have come to light, which justifies a review of this research. In particular, there is evidence that thrombin-mediated events interact with the immune system, and may regulate its response to tumor growth. It is also worth reevaluating the impact of thrombin on thrombocytes in conjunction with its multifaceted influence on tumor progression. Understanding the role of thrombin/PAR-mediated signaling in cancer and immunological responses is crucial, particularly in the context of developing immunotherapies. In this systematic review, we focus on the impact of the thrombin-related immune system response on cancer progression.

Transcriptomic characterization of the human segmental endotoxin challenge model

Segmental instillation of lipopolysaccharide (LPS) by bronchoscopy safely induces transient airway inflammation in human lungs. This model enables investigation of pulmonary inflammatory mechanisms as well as pharmacodynamic analysis of investigational drugs. The aim of this work was to describe the transcriptomic profile of human segmental LPS challenge with contextualization to major respiratory diseases. Pre-challenge bronchoalveolar lavage (BAL) fluid and biopsies were sampled from 28 smoking, healthy participants, followed by segmental instillation of LPS and saline as control. Twenty-four hours post instillation, BAL and biopsies were collected from challenged lung segments. Total RNA of cells from BAL and biopsy samples were sequenced and analysed for differentially expressed genes (DEGs). After challenge with LPS compared with saline, 6316 DEGs were upregulated and 241 were downregulated in BAL, but only one DEG was downregulated in biopsy samples. Upregulated DEGs in BAL were related to molecular functions such as "Inflammatory response" or "chemokine receptor activity", and upregulated pro-inflammatory pathways such as "Wnt-"/"Ras-"/"JAK-STAT" "-signaling pathway". Furthermore, the segmental LPS challenge model resembled aspects of the five most prevalent respiratory diseases chronic obstructive pulmonary disease (COPD), asthma, pneumonia, tuberculosis and lung cancer and featured similarities with acute exacerbations in COPD (AECOPD) and community-acquired pneumonia. Overall, our study provides extensive information about the transcriptomic profile from BAL cells and mucosal biopsies following LPS challenge in healthy smokers. It expands the knowledge about the LPS challenge model providing potential overlap with respiratory diseases in general and infection-triggered respiratory insults such as AECOPD in particular.

Protease-activated receptor 2 enhances innate and inflammatory mechanisms induced by lipopolysaccharide in macrophages from C57BL/6 mice

OBJECTIVE

This study was conducted to investigate the effects of the synthetic PAR2 agonist peptide (PAR2-AP) SLIGRL-NH₂ on LPS-induced inflammatory mechanisms in peritoneal macrophages.

METHODS

Peritoneal macrophages obtained from C57BL/6 mice were incubated with PAR2-AP and/or LPS, and the phagocytosis of zymosan fluorescein isothiocyanate (FITC) particles; nitric oxide (NO), reactive oxygen species (ROS), and cytokine production; and inducible NO synthase (iNOS) expression in macrophages co-cultured with PAR-2-AP/LPS were evaluated.

RESULTS

Co-incubation of macrophages with PAR2AP (30 µM)/LPS (100 ng/mL) enhanced LPS-induced phagocytosis; production of NO, ROS, and the pro-inflammatory cytokines interleukin (IL)-1β, tumour necrosis factor (TNF)-α, IL-6, and C-C motif chemokine ligand (CCL)2; and iNOS expression and impaired the release of the anti-inflammatory cytokine IL-10 after 4 h of co-stimulation. In addition, PAR2AP increased the LPS-induced translocation of the p65 subunit of the pro-inflammatory transcription factor nuclear factor kappa B (NF-κB) and reduced the expression of inhibitor of NF-κB.

CONCLUSION

This study provides evidence of a role for PAR2 in macrophage response triggered by LPS enhancing the phagocytic activity and NO, ROS, and cytokine production, resulting in the initial and adequate macrophage response required for their innate response mechanisms.

Peripheral blood intermediate monocyte protease-activated receptor-2 expression increases during asthma exacerbations and after inhalation allergen challenge

BACKGROUND

Myeloid cells, especially dendritic cells and macrophages, play important roles in asthma pathophysiology. Monocytes (Mo) and macrophages express protease-activated receptor-2 (PAR-2), a proinflammatory serine protease receptor implicated in the pathophysiology of allergic airway inflammation. We have revealed that patients with severe asthma and those with a history of frequent asthma exacerbations exhibit increased PAR-2 expression on peripheral blood monocytes.

OBJECTIVE

To determine PAR-2 expression on peripheral blood intermediate monocytes (IMMo) in subjects with increased airway inflammation, either as a result of an asthma exacerbation or after an inhalation allergen challenge.

METHODS

A total of 16 adults who presented to the emergency department with asthma exacerbations were recruited after giving an informed consent. After 2 weeks, 10 patients returned for follow-up. A total of 11 patients with mild asthma treated only with as-needed bronchodilators were recruited and underwent inhalation allergen challenge after providing an informed consent. Immune cell profiling was performed by whole blood flow cytometry in both groups of patients.

RESULTS

PAR-2 expression in peripheral blood IMMo increased in patients with an asthma exacerbation compared with those with stable disease, but this expression decreased after treatment of the asthma exacerbation. Subjects with mild asthma had an increase in percentages of IMMo expressing PAR-2 after an allergen challenge. Patients who presented to the emergency department had lower dendritic cell and dendritic cell subset numbers in peripheral blood during exacerbation compared with after treatment.

CONCLUSION

Increased PAR-2 expression on Mo during periods of increased airway inflammation may initiate a positive feedback loop leading to systemic inflammatory changes.

A role for mast cells and mast cell tryptase in driving neutrophil recruitment in LPS-induced lung inflammation via protease-activated receptor 2 in mice

OBJECTIVE

This study aims to investigate the role of protease-activated receptor (PAR) 2 and mast cell (MC) tryptase in LPS-induced lung inflammation and neutrophil recruitment in the lungs of C57BL/6 mice.

METHODS

C57BL/6 mice were pretreated with the PAR2 antagonist ENMD-1068, compound 48/80 or aprotinin prior to intranasal instillation of MC tryptase or LPS. Blood leukocytes, C-X-C motif chemokine ligand (CXCL) 1 production leukocytes recovered from bronchoalveolar lavage fluid (BALF), and histopathological analysis of the lung were evaluated 4 h later. Furthermore, we performed experiments to determine intracellular calcium signaling in RAW 264.7 cells stimulated with LPS in the presence or absence of a protease inhibitor cocktail or ENMD-1068 and evaluated PAR2 expression in the lungs of LPS-treated mice.

RESULTS

Pharmacological blockade of PAR2 or inhibition of proteases reduced neutrophils recovered in BALF and LPS-induced calcium signaling. PAR2 blockade impaired LPS-induced lung inflammation, PAR2 expression in the lung and CXCL1 release in BALF, and increased circulating blood neutrophils. Intranasal instillation of MC tryptase increased the number of neutrophils recovered in BALF, and MC depletion with compound 48/80 impaired LPS-induced neutrophil migration.

CONCLUSION

Our study provides, for the first time, evidence of a pivotal role for MCs and MC tryptase in neutrophil migration, lung inflammation and macrophage activation triggered by LPS, by a mechanism dependent on PAR2 activation.

Use of Nasopancreatic Drainage for Severe Post-endoscopic Retrograde Cholangiopancreatography Pancreatitis: A Case Series

Five patients complaining of severe pain due to severe post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP) underwent nasopancreatic drainage (NPD) placement. Pain relief was achieved on the second, fourth, and fifth day in three, one, and one patients, respectively. Four patients underwent pancreatic juice culture; all were positive. Our results suggest that NPD can relieve severe PEP with severe pain. Bacteria-induced protease-activated receptor-2 activation may be associated with PEP.

HCMV vCXCL1 Binds Several Chemokine Receptors and Preferentially Attracts Neutrophils over NK Cells by Interacting with CXCR2

HCMV is a highly sophisticated virus that has developed various mechanisms for immune evasion and viral dissemination throughout the body (partially mediated by neutrophils). NK cells play an important role in elimination of HCMV-infected cells. Both neutrophils and NK cells utilize similar sets of chemokine receptors to traffic, to and from, various organs. However, the mechanisms by which HCMV attracts neutrophils and not NK cells are largely unknown. Here, we show a unique viral protein, vCXCL1, which targets three chemokine receptors: CXCR1 and CXCR2 expressed on neutrophils and CXCR1 and CX3CR1 expressed on NK cells. Although vCXCL1 attracted both cell types, neutrophils migrated faster and more efficiently than NK cells through the binding of CXCR2. Therefore, we propose that HCMV has developed vCXCL1 to orchestrate its rapid systemic dissemination through preferential attraction of neutrophils and uses alternative mechanisms to counteract the later attraction of NK cells.

Increased Protease-Activated Receptor-2 (PAR-2) Expression on CD14++CD16+ Peripheral Blood Monocytes of Patients with Severe Asthma

BACKGROUND

Protease-Activated Receptor-2 (PAR-2), a G protein coupled receptor activated by serine proteases, is widely expressed in humans and is involved in inflammation. PAR-2 activation in the airways plays an important role in the development of allergic airway inflammation. PAR-2 expression is known to be upregulated in the epithelium of asthmatic subjects, but its expression on immune and inflammatory cells in patients with asthma has not been studied.

METHODS

We recruited 12 severe and 24 mild/moderate asthmatics from the University of Alberta Hospital Asthma Clinics and collected baseline demographic information, medication use and parameters of asthma severity. PAR-2 expression on blood inflammatory cells was analyzed by flow cytometry.

RESULTS

Subjects with severe asthma had higher PAR-2 expression on CD14++CD16+ monocytes (intermediate monocytes) and also higher percentage of CD14++CD16+PAR-2+ monocytes (intermediate monocytes expressing PAR-2) in blood compared to subjects with mild/moderate asthma. Receiver operating characteristics (ROC) curve analysis showed that the percent of CD14++CD16+PAR-2+ in peripheral blood was able to discriminate between patients with severe and those with mild/moderate asthma with high sensitivity and specificity. In addition, among the whole populations, subjects with a history of asthma exacerbations over the last year had higher percent of CD14++CD16+ PAR-2+ cells in peripheral blood compared to subjects without exacerbations.

CONCLUSIONS

PAR-2 expression is increased on CD14++CD16+ monocytes in the peripheral blood of subjects with severe asthma and may be a biomarker of asthma severity. Our data suggest that PAR-2 -mediated activation of CD14++CD16+ monocytes may play a role in the pathogenesis of severe asthma.

Genetic variations in monocyte chemoattractant protein-1 and susceptibility to ovarian cancer

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine which plays critical roles in regulating host immune responses. Researches have shown that MCP-1 may greatly participate in the development of different cancers. In the current study, we investigated the effect of MCP-1 on ovarian cancer by examining the association between MCP-1 genetic polymorphisms and the susceptibility to ovarian cancer. MCP-1 -2158A/G and MCP-1 -362C/G polymorphisms were examined in ovarian cancer patients and healthy controls by using polymerase chain reaction-restriction fragment length polymorphism analysis. Results showed that percentages of MCP-1 -2158GG genotype and G allele were significantly higher in ovarian cancer patients than in controls (odd ratio (OR) = 1.87; 95 % confidence interval (CI), 1.19-2.76; P = 0.012 and OR = 1.47; 95 % CI, 1.11-1.79; P = 0.003; data were adjusted for age and smoking status). The MCP-1 -362GG genotype also revealed increased number in patients. Stratification analyses presented that ovarian cancer cases with serous-papillary type had significantly increased percentage of -362GG genotype than those with other types (13.1 versus 5.0 %, P = 0.032; data were adjusted for age and smoking status). Also, we evaluated the relation between these two polymorphisms and serum level of MCP-1. We identified that the subjects with MCP-1 -2158AG and GG genotypes had clearly increased serum level of MCP-1 than those with AA genotype. These data suggest that MCP-1 may be involved in the pathogenesis of ovarian cancer.

Influenza, a One Health paradigm--novel therapeutic strategies to fight a zoonotic pathogen with pandemic potential

Influenza virus is a paradigm for a pathogen that frequently crosses the species barrier from animals to humans, causing severe disease in the human population. This ranges from frequent epidemics to occasional pandemic outbreaks with millions of death. All previous pandemics in humans were caused by animal viruses or virus reassortants carrying animal virus genes, underlining that the fight against influenza requires a One Health approach integrating human and veterinary medicine. Furthermore, the fundamental question of what enables a flu pathogen to jump from animals to humans can only be tackled in a transdisciplinary approach between virologists, immunologists and cell biologists. To address this need the German FluResearchNet was established as a first nationwide influenza research network that virtually integrates all national expertise in the field of influenza to unravel viral and host determinants of pathogenicity and species transmission and to explore novel avenues of antiviral intervention. Here we focus on the various novel anti-flu approaches that were developed as part of the FluResearchNet activities.

Proteinase-activated receptor-2 agonist activates anti-influenza mechanisms and modulates IFNγ-induced antiviral pathways in human neutrophils

Proteinase-activated receptor-2 (PAR₂) is expressed by human leukocytes and participates in the development of inflammatory diseases. Recent studies demonstrated an ability of PAR₂ agonist to enhance IFNγ-induced antiviral responses of human leukocytes. However, the precise cellular antiviral defense mechanisms triggered in leukocytes after stimulation with IFNγ and/or PAR₂ agonist remain elusive. Therefore, we aimed to identify neutrophil defense mechanisms involved in antiviral resistance. Here we demonstrated that PAR₂ agonist enhanced IFNγ-related reduction of influenza A virus (IAV) replication in human neutrophils. PAR₂-mediated decrease in IAV replication was associated with reduced NS-1 transcription. Moreover, PAR₂-dependent neutrophil activation resulted in enhanced myeloperoxidase degranulation and extracellular myeloperoxidase disrupted IAV. The production of ROS was elevated in response to PAR₂ activation. Interestingly, IFNγ did not influence both effects: PAR₂ agonist-triggered myeloperoxidase (MPO) release and reactive oxygen species (ROS) production, which are known to limit IAV infections. In contrast, orthomyxovirus resistance gene A (MxA) protein expression was synergistically elevated through PAR₂ agonist and IFNγ in neutrophils. Altogether, these findings emphasize two PAR₂-controlled antiviral mechanisms that are independent of or modulated by IFNγ.

The viral KSHV chemokine vMIP-II inhibits the migration of Naive and activated human NK cells by antagonizing two distinct chemokine receptors

Natural killer (NK) cells are innate immune cells able to rapidly kill virus-infected and tumor cells. Two NK cell populations are found in the blood; the majority (90%) expresses the CD16 receptor and also express the CD56 protein in intermediate levels (CD56^Dim CD16^Pos) while the remaining 10% are CD16 negative and express CD56 in high levels (CD56^Bright CD16^Neg). NK cells also reside in some tissues and traffic to various infected organs through the usage of different chemokines and chemokine receptors. Kaposi's sarcoma-associated herpesvirus (KSHV) is a human virus that has developed numerous sophisticated and versatile strategies to escape the attack of immune cells such as NK cells. Here, we investigate whether the KSHV derived cytokine (vIL-6) and chemokines (vMIP-I, vMIP-II, vMIP-III) affect NK cell activity. Using transwell migration assays, KSHV infected cells, as well as fusion and recombinant proteins, we show that out of the four cytokine/chemokines encoded by KSHV, vMIP-II is the only one that binds to the majority of NK cells, affecting their migration. We demonstrate that vMIP-II binds to two different receptors, CX3CR1 and CCR5, expressed by naïve CD56^Dim CD16^Pos NK cells and activated NK cells, respectively. Furthermore, we show that the binding of vMIP-II to CX3CR1 and CCR5 blocks the binding of the natural ligands of these receptors, Fractalkine (Fck) and RANTES, respectively. Finally, we show that vMIP-II inhibits the migration of naïve and activated NK cells towards Fck and RANTES. Thus, we present here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.

NK cells belong to the innate immune system, able to rapidly kill tumors and various pathogens. They reside in the blood and in various tissues and traffic to different infected organs through the usage of different chemokines and chemokine receptors. KSHV is a master of immune evasion, and around a quarter of the KSHV encoded genes are dedicated to interfere with immune cell recognition. Here, we investigate the role played by the KSHV derived cytokine and chemokines (vIL-6, vMIP-I, vMIP-II, vMIP-III) in modulating NK cell activity. We show that vMIP-II binds and inhibits the activity of two different receptors, CX3CR1 and CCR5, expressed by naïve NK cells and by activated NK cells, respectively. Thus, we demonstrate here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.