Role of the coagulation system in allergic inflammation in the upper airways

The Role of Platelet-Derived Extracellular Vesicles in Immune-Mediated Thrombosis

Platelet-derived extracellular vesicles (PEVs) play important roles in hemostasis and thrombosis. There are three major types of PEVs described based on their size and characteristics, but newer types may continue to emerge owing to the ongoing improvement in the methodologies and terms used to define various types of EVs. As the literature on EVs is growing, there are continuing attempts to standardize protocols for EV isolation and reach consensus in the field. This review provides information on mechanisms of PEV production, characteristics, cellular interaction, and their pathological role, especially in autoimmune and infectious diseases. We also highlight the mechanisms through which PEVs can activate parent cells in a feedback loop.

Allergic rhinitis is associated with thromboembolic disease in pregnancy

Finding the risk factors for thromboembolic (TE) disease and preventing its development in pregnant women is important. Allergic rhinitis (AR) is a common chronic disease. We aim to find if AR is a risk factor. From 2004 to 2011, 55,057 pregnant women were recruited from a Taiwan database. They were grouped into AR and non-AR groups. The rate of TE and venous complications during pregnancy and 60 days after childbirth were compared between non-AR and the AR group. Those with AR diagnosed both before and after childbirth, meaning AR was not changed during pregnancy, the rates of TE (OR 2.64) and venous complications (OR 1.35) were higher compared to non-AR subjects. In those who underwent cesarean delivery, the rate was also higher in group 3 (OR 4.14). Those with AR before childbirth, without after, meaning AR was well controlled during pregnancy, the rate of TE was not higher than that of the non-AR subjects. Pregnant women with AR have an increased rate of TE. An increased rate of venous complications in these subjects might explain the increase in TE. If AR is well controlled during pregnancy, the rate of TE does not appear to increase.

Mechanisms and pathogenesis of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by local inflammation of the upper airways and is historically divided into 2 main phenotypes: CRS with nasal polyps and CRS without nasal polyps. Inflammation in CRS is mainly characterized by 3 endotypes based on elevation of canonical lymphocyte cytokines: type (T) 1 (T1) by TH1 cytokine IFN-γ, T2 by TH2 cutokines IL-4, IL-5, and IL-13, and T3 by TH17 cytokines including IL-17. Inflammation in both CRS without nasal polyps and CRS with nasal polyps is highly heterogeneous, and the frequency of various endotypes varies geographically around the world. This finding complicates establishment of a unified understanding of the mechanisms of pathogenesis in CRS. Sinonasal epithelium acts as a passive barrier, and epithelial barrier dysfunction is a common feature in CRS induced by endotype-specific cytokines directly and indirectly. The sinonasal epithelium also participates in both innate immunity via recognition by innate pattern-recognition receptors and promotes and regulates adaptive immunity via release of chemokines and innate cytokines including thymic stromal lymphopoietin. The purpose of this review was to discuss the contribution of the epithelium to CRS pathogenesis and to update the field regarding endotypic heterogeneity and various mechanisms for understanding pathogenesis in CRS.

17,18-Epoxyeicosatetraenoic Acid Inhibits TNF-α-Induced Inflammation in Cultured Human Airway Epithelium and LPS-Induced Murine Airway Inflammation

BACKGROUND

17,18-Epoxyeicosatetraenoic acid (17,18-EpETE), an eicosapentaenoic acid metabolite, is generated from dietary oil in the gut, and antiinflammatory activity of 17,18-EpETE was recently reported.

OBJECTIVE

To evaluate the inhibitory effects of 17,18-EpETE in airway inflammation, we examined in vitro and in vivo effects on mucus production, neutrophil infiltration, and cytokine/chemokine production in airway epithelium.

METHODS

Nasal tissue localization of G protein-coupled receptor 40 (GPR40), a receptor of 17,18-EpETE, was determined by immunohistochemical staining. Expression of GPR40 mRNA in nasal mucosa of chronic rhinosinusitis (CRS) patients and control subjects was determined by reverse transcription-polymerase chain reaction (RT-PCR). The in vitro effects on airway epithelial cells were examined using normal human bronchial epithelial cells and NCI-H292 cells. To examine the in vivo effects of 17,18-EpETE on airway inflammation, we induced goblet cell metaplasia, mucus production, and neutrophil infiltration in mouse nasal epithelium by intranasal lipopolysaccharide (LPS) instillation.

RESULTS

GPR40 is mainly expressed in human nasal epithelial cells and submucosal gland cells. RT-PCR analysis revealed that the expression of GPR40 mRNA was increased in nasal tissues from CRS patients compared with those from control subjects. 17,18-EpETE significantly inhibited tumor necrosis factor (TNF)-α-induced production of interleukin (IL)-6 , IL-8, and mucin from cultured human airway epithelial cells dose dependently, and these antiinflammatory effects on cytokine production were abolished by GW1100, a selective GPR40 antagonist. Intraperitoneal injection or intranasal instillation of 17,18-EpETE significantly attenuated LPS-induced mucus production and neutrophil infiltration in mouse nasal epithelium. Inflammatory cytokine/chemokine production in lung tissues and bronchoalveolar lavage fluids was also inhibited.

CONCLUSION

These results indicate that 17,18-EpETE plays a regulatory role in mucus hypersecretion and neutrophil infiltration in nasal inflammation. Local or systemic administration may provide a new therapeutic approach for the treatment of intractable airway disease such as CRS.

Involvement of hemostasis in pathophysiology of RAO in horses

Recurrent Airway Obstruction (RAO), also called severe asthma or heaves, is a chronic disease in adult horses caused by aeroallergens from straw or hay. Disturbances in hemostasis (intensified coagulation and depressed fibrinolysis) are considered one of the prominent reasons of inflammatory process, injury and dysfunction of the lungs. The aim of the study was to evaluate chosen parameters of hemostasis in horses with active form of RAO. Ten RAO-horses (group R) and ten healthy horses (group C) were exposed to straw and hay allergen challenge. The prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), fibrinogen concentration (Fb), stabilized fibrin degradation product (d-dimer), antithrombin (AT), protein C and coagulation factors II through XII were assessed in plasma obtained from blood of all the horses. Exposure to aeroallergens resulted in prolongation of aPTT in both groups of animals; it was evident in the group R and moderate in the group C. There were no differences in PT and TT. Concentrations of fibrinogen and d-dimer and activity of protein C in both groups were increased but lay within or near to reference values. The activity of AT was depressed in RAO-horses. All exposed horses showed increased activity of coagulation factors II, VIII and X but they had no changes in activity of factor V. Factors VII and XII displayed a reduction in activity. The decrease in factor IX activity was noted in the group C only. Various changes were observed in activity of factor XI; in horses with RAO it was elevated but in healthy horses it was declined. The changes of the parameters tested in RAO-horses indicate the involvement of coagulation and fibrinolysis which apparently remained under control of efficient and active mechanisms of general hemostasis.

Thrombin Inhibition by Argatroban: Potential Therapeutic Benefits in COVID-19

Thrombin is a trypsin-like serine protease with multiple physiological functions. Its role in coagulation and thrombosis is well-established. Nevertheless, thrombin also plays a major role in inflammation by activating protease-activated receptors. In addition, thrombin is also involved in angiogenesis, fibrosis, and viral infections. Considering the pathogenesis of COVID-19 pandemic, thrombin inhibitors may exert multiple potential therapeutic benefits including antithrombotic, anti-inflammatory, and antiviral activities. In this review, we describe the clinical features of COVID-19, the thrombin’s roles in various pathologies, and the potential of argatroban in COVID-19 patients. Argatroban is a synthetic, small molecule, direct, competitive, and selective inhibitor of thrombin. It is approved to parenterally prevent and/or treat heparin-induced thrombocytopenia in addition to other thrombotic conditions. Argatroban also possesses anti-inflammatory and antiviral activities and has a well-established pharmacokinetics profile. It also appears to lack a significant risk of drug–drug interactions with therapeutics currently being evaluated for COVID-19. Thus, argatroban presents a substantial promise in treating severe cases of COVID-19; however, this promise is yet to be established in randomized, controlled clinical trials.

Probable Roles of Coagulation Cascade and Fibrinolysis System in the Development of Allergic Rhinitis

BACKGROUND

Dysregulation of the coagulation cascade and fibrinolysis system may play an etiologic role in many diseases. Allergic diseases such as bronchial asthma, atopic dermatitis, and conjunctivitis are also associated with fibrin accumulation caused by a change in hemostasis. However, only a few studies have dealt with the relationship between allergic rhinitis (AR) and the coagulation system.

OBJECTIVE

We investigated the difference of coagulation and fibrinolysis cascade components between an AR mouse model and a control mice.

METHODS

BALB/c mice were sensitized and challenged with ovalbumin. Multiple parameters of coagulation cascade and fibrinolysis system such as factors II, V, VII, X, and XIII; tissue-type plasminogen activator; urokinase-type plasminogen activator (u-PA); plasminogen activator inhibitor-1 (PAI-1); and fibrin were compared between the AR model group and the control group.

RESULTS

The symptom scores and eosinophil counts were higher in the AR group than in the control group ( P < .01). The mRNA expression level of u-PA ( P = .040) was significantly lower, and the expression levels of factor II ( P = .038) and factor X ( P = .036) were significantly higher, in the AR group. Immunohistochemical staining revealed that most of the fibrinolysis system and coagulation cascade components were localized to the epithelium, endothelium, and submucosal glands of the nasal mucosa. u-PA was downregulated in the AR group, whereas fibrin deposition was more prominent in the AR group than in the control group.

CONCLUSION

In AR, particular components of the coagulation cascade were increased and fibrinolysis system was decreased compared to normal control. This difference may be associated with the fibrin deposition in the mucosa of AR mouse model.

A proteomics analysis reveals that A2M might be regulated by STAT3 in persistent allergic rhinitis

BACKGROUND

Proteomics tools can be used to identify the differentially expressed proteins related to allergic rhinitis (AR). However, the large numbers of proteins related to AR have not yet been explored using an advanced quantitative proteomics approach, known as isobaric tags for relative and absolute quantitation (iTRAQ).

OBJECTIVES

To identify differentially expressed proteins in persistent AR patients and to explore the regulatory signalling pathways involving the identified proteins.

METHODS

Forty-five persistent AR patients and 20 healthy controls were recruited for this study. iTRAQ was used to identify the proteins that were differentially expressed between these two groups, and a bioinformatics analysis was then conducted to identify the signalling pathways associated with the identified proteins. Immunofluorescence labelling was performed to detect alpha-2-macroglobulin (A2M), STAT3, p-STAT3 and IL17 in the nasal mucosa.

RESULTS

A total of 133 differentially expressed proteins were identified. We then determined the top 10 regulatory pathways associated with these proteins and found that the blood coagulation pathway had the most significant association. A2M, a protein involved in the blood coagulation pathway, was found to be differentially expressed in the serum of AR patients. The bioinformatics analysis indicated that STAT3 is an upstream transcription factor that might regulate A2M expression. An immunofluorescence study further confirmed that STAT3 and A2M are co-localized in nasal mucosa cells. Additionally, A2M, STAT3, p-STAT3, and IL17 are elevated in AR patients. The expressional level of A2M is positively related to IL17 and the symptom of the congestion in AR subjects.

CONCLUSIONS

The blood coagulation pathway may be a key regulatory network pathway contributing to the allergic inflammatory response in AR patients. A2M, which is regulated by STAT3, may be an important protein in the pathogenesis of allergic rhinitis in AR patients.

Thrombin and activated coagulation factor X stimulate the release of cytokines and fibronectin from nasal polyp fibroblasts via protease-activated receptors

BACKGROUND

Nasal epithelial cells and infiltrating eosinophils express tissue factor, and high thrombin activity and excess fibrin deposition are found in nasal secretion and in nasal polyp from patients with chronic rhinosinusitis with nasal polyp (CRSwNP). Activated coagulation factors play important roles not only in thrombosis but also in inflammation through interaction with protease-activated receptors (PAR). However, little is known about the effects of activated coagulation factors on the release of cytokines and extracellular matrix from nasal polyp fibroblasts (NPF).

PURPOSE

The purpose of this study was to analyze the expression of PARs, which are receptors for activated coagulation factors, on NPFs and to determine the roles of thrombin and activated coagulation factor X (FXa) in the release of cytokines and fibronectin from NPFs.

METHODS

NPFs were obtained from patients with CRSwNP, and the messenger RNA (mRNA) and protein expression of PARs in these NPFs were examined. We then investigated whether thrombin or FXa stimulates the release of transforming growth factor (TGF) beta 1, fibronectin, eotaxin-1, interleukin (IL) 6, or IL-8 from cultured NPFs. The effects of PAR agonists on the release of cytokines and fibronectin were also examined.

RESULTS

NPFs expressed the mRNA and proteins of all four PARs: PAR-1, PAR-2, PAR-3, and PAR-4. Both thrombin and FXa significantly stimulated the release of TGF beta 1, fibronectin, eotaxin-1, IL-6, and IL-8 from cultured NPFs. PAR-1 and PAR-2 agonists stimulated the secretion of TGF beta 1, fibronectin, eotaxin-1, IL-6, and IL-8. PAR-3 agonist stimulated the release of TGF beta 1, fibronectin, and eotaxin-1. PAR-4 agonist did not induce the release of these molecules.

CONCLUSION

NPFs play important roles in the pathophysiology of CRSwNP such as in nasal polyp formation and inflammatory cell infiltration by releasing cytokines and extracellular matrix proteins. Activated coagulation factors, thrombin and FXa, stimulate the release of these cytokines and fibronectin from NPFs via PARs.

The nasal mucosal late allergic reaction to grass pollen involves type 2 inflammation (IL-5 and IL-13), the inflammasome (IL-1β), and complement

Non-invasive mucosal sampling (nasosorption and nasal curettage) was used following nasal allergen challenge with grass pollen in subjects with allergic rhinitis, in order to define the molecular basis of the late allergic reaction (LAR). It was found that the nasal LAR to grass pollen involves parallel changes in pathways of type 2 inflammation (IL-4, IL-5 and IL-13), inflammasome-related (IL-1β), and complement and circadian-associated genes. A grass pollen nasal spray was given to subjects with hay fever followed by serial sampling, in which cytokines and chemokines were measured in absorbed nasal mucosal lining fluid, and global gene expression (transcriptomics) assessed in nasal mucosal curettage samples. Twelve of 19 subjects responded with elevations in interleukin (IL)-5, IL-13, IL-1β and MIP-1β/CCL4 protein levels in the late phase. In addition, in these individuals whole-genome expression profiling showed upregulation of type 2 inflammation involving eosinophils and IL-4, IL-5 and IL-13; neutrophil recruitment with IL-1α and IL-1β; the alternative pathway of complement (factor P and C5aR); and prominent effects on circadian-associated transcription regulators. Baseline IL-33 mRNA strongly correlated with these late-phase responses, whereas a single oral dose of prednisone dose-dependently reversed most nasal allergen challenge-induced cytokine and transcript responses. This study shows that the LAR to grass pollen involves a range of inflammatory pathways and suggests potential new biomarkers and therapeutic targets. Furthermore, the marked variation in mucosal inflammatory events between different patients suggests that in the future precision mucosal sampling may enable rational specific therapy.

Tissue factor and tissue factor pathway inhibitor in nasal mucosa and nasal secretions of chronic rhinosinusitis with nasal polyp

BACKGROUND

Activation of the coagulation system with an increase in thrombin generation is involved in the pathogenesis of tissue remodeling in chronic rhinosinusitis (CRS). Tissue factor (TF) is an important protein for initiation of the extrinsic coagulation pathway, and TF pathway inhibitor (TFPI) is a regulator of TF-induced coagulation. This study was conducted to elucidate the roles of TF and TFPI in the pathogenesis of CRS.

METHODS

Tissue localization of TF, TFPI, and fibrin was determined by immunostaining of nasal polyps and inferior turbinates obtained during endonasal surgery in patients with CRS with nasal polyp (CRSwNP). Nasal secretions were collected from patients with CRSwNP, allergic rhinitis, and from control patients. The concentrations of TF and TFPI were measured in nasal secretions from each group. The concentrations of TF and TFPI released into culture medium by normal human nasal epithelial cells treated with thrombin, protease-activated receptor 1 agonist peptide, or tumor necrosis factor α were also measured.

RESULTS

TF expression was localized in nasal epithelial cells and in infiltrating eosinophils of nasal mucosa. TFPI expression was localized in nasal epithelial cells, and fibrin deposition was observed in nasal secretions and the lamina propria of nasal polyps. Nasal secretions contained significant concentrations of TF and TFPI. The concentration of TFPI in nasal secretions correlated positively with thrombin activity and the concentration of thrombin-antithrombin III complex. Treatment with thrombin, protease-activated receptor 1 agonist peptide, or tumor necrosis factor α stimulated significant release of TF and TFPI from cultured nasal epithelial cells.

CONCLUSIONS

By upregulating the coagulation system, TF and TFPI play an important role in the pathogenesis of CRSwNP.

Epidermal Growth Factor Receptor Inhibitor Ag1478 Inhibits Mucus Hypersecretion in Airway Epithelium

Background

Mucus hypersecretion and neutrophil infiltration are important characteristics of airway inflammation. Epidermal growth factor receptor (EGFR) transactivation induces mucus and inflammatory cytokine secretion from airway epithelial cells. To elucidate the roles of EGFR in airway inflammation, the in vitro effects on mucin production and interleukin (IL) 8 secretion from cultured airway epithelial cells and the in vivo effects on mucus hypersecretion and neutrophil infiltration in rat nasal mucosa of the EGFR tyrosine kinase inhibitor AG1478 were examined.

Methods

The in vitro effects of AG1478 treatment of cultured NCI-H292 cells on lipopolysaccharide (LPS) induced or tumor necrosis factor (TNF) a induced MUC5AC mucin and IL-8 secretion were evaluated. Hypertrophic and metaplastic changes of goblet cells, mucus production and neutrophil infiltration in rat nasal epithelium were induced by intranasal instillation of LPS in vivo, and the inhibitory effects of AG1478 by intraperitoneal injection or intranasal instillation were examined.

Results

AG1478 (1-1000 nM) significantly inhibited both LPS-induced and TNF-α-induced secretion of MUC5AC and IL-8 from cultured NCI-H292 cells in a dose-dependent manner. The expression of MUC5AC and IL-8 messenger RNAs was also significantly inhibited. Intranasal instillation of AG1478 one hour after intranasal LPS instillation significantly inhibited LPS-induced goblet cell metaplasia, mucus production, and neutrophil infiltration in rat nasal epithelium, as did intraperitoneal injection of AG1478 one hour before LPS instillation.

Conclusions

These results indicated that EGFR transactivation plays an important role in mucin and IL-8 secretion from airway epithelial cells. Intranasal instillation of an EGFR tyrosine kinase inhibitor may be a new therapeutic approach for the treatment of upper airway inflammation.

Chronic Rhinosinusitis and the Coagulation System

Chronic rhinosinusitis (CRS) is one of the most common chronic diseases in adults and severely affects quality of life in patients. Although various etiologic and pathogenic mechanisms of CRS have been proposed, the causes of CRS remain uncertain. Abnormalities in the coagulation cascade may play an etiologic role in many diseases, such as asthma and other inflammatory conditions. While studies on the relationship between asthma and dysregulated coagulation have been reported, the role of the coagulation system in the pathogenesis of CRS has only been considered following recent reports. Excessive fibrin deposition is seen in nasal polyp (NP) tissue from patients with chronic rhinosinusitis with nasal polyp (CRSwNP) and is associated with activation of thrombin, reduction of tissue plasminogen activator (t-PA) and upregulation of coagulation factor XIII-A (FXIII-A), all events that can contribute to fibrin deposition and crosslinking. These findings were reproduced in a murine model of NP that was recently established. Elucidation of the mechanisms of fibrin deposition may enhance our understanding of tissue remodeling in the pathophysiology of NP and provide new targets for the treatment of CRSwNP.

Eosinophil-epithelial cell interactions stimulate the production of MUC5AC mucin and profibrotic cytokines involved in airway tissue remodeling

BACKGROUND

Predominant eosinophil infiltration and tissue remodeling are common characteristics of chronic airway inflammation such as nasal polyposis and bronchial asthma. This study was designed to elucidate the role of eosinophils in tissue remodeling of chronic airway inflammation; eosinophil-epithelial interactions were examined by the coculture of airway epithelial cell line NCI-H292 with the eosinophilic cell line EoL-1 or with human blood eosinophils.

METHODS

The coculture-induced production of MUC5AC mucin, platelet-derived growth factor AB (PDGF-AB), vascular endothelial growth factor (VEGF), transforming growth factor (TGF) beta1, and interleukin-8 (IL-8) were evaluated by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction.

RESULTS

Eosinophil-epithelial interactions significantly stimulated the secretion of MUC5AC, PDGF-AB, VEGF, TGF-beta1, and IL-8 in culture supernatants. The epidermal growth factor receptor tyrosine kinase inhibitor AG1478 inhibited the coculture-induced secretion of MUC5AC, PDGF-AB, VEGF, and IL-8. Neutralizing antibodies directed against TGF-alpha or amphiregulin and pan-metalloproteinase inhibitor GM6001 inhibited the coculture-induced secretion of MUC5AC and amphiregulin from the cocultured NCI-H292 cells. Coculture of NCI-H292 cells with peripheral blood eosinophils also significantly stimulated MUC5AC production.

CONCLUSION

The results of this study indicate that eosinophil-epithelial cell interactions are important in the pathogenesis of tissue remodeling of eosinophil-predominant airway inflammation such as occurs in nasal polyposis and bronchial asthma.

Thrombin promotes airway remodeling via protease-activated receptor-1 and transforming growth factor-β1 in ovalbumin-allergic rats

BACKGROUND

Protease-activated receptor-1 (PAR-1) is widely distributed in platelets and involved in coagulation cascade activated by thrombin. In this study, we intend to explore the role of PAR-1 in the process of thrombin-inducing transforming growth factor-β1 (TGF-β1) to promote airway remodeling in ovalbumin (OVA)-allergic rats.

MATERIALS AND METHODS

A rat model of chronic asthma was set up by systemic sensitization and repeated challenge to OVA. The doses of thrombin, recombinant hirudin, PAR-1 inhibitor ER-112780-06 varied for different groups. We evaluated the bronchoalveolar lavage fluid (BALF) concentration of thrombin in these groups. The protein and gene expression of PAR-1 was assessed and the expression of TGF-β1 was also detected.

RESULTS

The PAR-1 mRNA level and the protein level were higher in the airway of asthmatic rats than those of normal rats, and were significantly increased by thrombin treatment but decreased by thrombin-inhibitor treatment. Airway remodeling was strengthened by thrombin but weakened by thrombin inhibitor and PAR-1 antagonist. Expression of TGF-β1 protein in asthmatic rats was significantly increased by thrombin treatment and decreased by thrombin-inhibitor treatment and PAR-1 antagonist treatment.

CONCLUSION

The expression of PAR-1 is regulated by thrombin that induces the expression of TGF-β1 to promote airway remodeling via PAR-1 in OVA-allergic rats.

Links between allergy and cardiovascular or hemostatic system

In addition to a well-known immunologic background of atherosclerosis and influences of inflammation on arterial and venous thrombosis, there is growing evidence for the presence of links between allergy and vascular or thrombotic disorders. In this interpretative review, five pretty well-documented areas of such overlap are described and discussed, including: (1) links between atherosclerosis and immunoglobulin E or atopy, (2) mutual effects of blood lipids and allergy, (3) influence of atopy and related disorders on venous thromboembolism, (4) the role of platelets in allergic diseases, and (5) the functions of protein C system in atopic disorders.

Dose-dependent differential effects of thrombin in allergic bronchial asthma

BACKGROUND

Apart from its role in the coagulation system, thrombin plays an important role in the inflammatory response through its protease-activated receptors (PARs). However, the role of thrombin in the immune response is not clear.

OBJECTIVE

To evaluate whether thrombin has a modulatory role in allergic bronchial asthma.

METHODS

Bronchial asthma was induced in mice by intraperitoneal sensitization and inhalation challenge with ovalbumin. Thrombin or its inhibitors were administered by inhalation before each allergen challenge.

RESULTS

Mice with low but sustained coagulation activation had reduced allergic inflammation, and allergic asthma was inhibited by low doses of thrombin but worsened by high doses. Allergic asthma was worsened by antithrombin, argatroban, hirudin, and anti-thrombomodulin antibody. Mice with a higher level of an inhibitor of both thrombin and activated protein C had worse disease. Heterozygous PAR-1 mice had less allergic inflammation, but PAR-1 agonist worsened it. Allergic bronchial inflammation was worsened in mice that received adoptive transfer of PAR-1 agonist-treated Th2 cells as compared with controls. Low levels of thrombin suppressed the maturation and secretion of cytokines in dendritic cells, but high levels enhanced this.

CONCLUSIONS

The effects of thrombin on allergic asthma are dose-dependent, with detrimental effects at high doses and protective effects at low doses. These data demonstrate that thrombin modulates the outcome in allergic bronchial asthma.

The effect of heparin on antigen-induced mucus hypersecretion in the nasal epithelium of sensitized rats

BACKGROUND

Heparin is a potential anti-inflammatory drug for allergic airway inflammation. To elucidate the effects of heparin on allergic inflammation, we examined the in vivo effects of heparin on antigen-induced mucus hypersecretion and infiltration of eosinophils and neutrophils in the nasal epithelium of sensitized rats.

METHODS

We induced hypertrophic and metaplastic changes of goblet cells in the nasal epithelium of ovalbumin (OVA)-sensitized rats by intranasal challenge with OVA. The effects of intranasal instillation with low molecular weight heparin (LMWH; 1-1000IU/0.1ml) on mucus production and eosinophil/neutrophil infiltration were examined.

RESULTS

Intranasal instillation with low-dose LMWH (1-10IU/0.1ml) at 30 minutes before OVA instillation stimulated OVA-induced mucus production in the nasal epithelium of sensitized rats, whereas treatment with 100IU/0.1ml LMWH showed no effect. Intranasal instillation with high-dose LMWH (1000IU/0.1ml) significantly inhibited OVA-induced mucus production. Intranasal instillation with LMWH (1-1000IU/0.1ml) dose-dependently inhibited eosinophil and neutrophil infiltration into the rat nasal mucosa.

CONCLUSIONS

These results indicate that heparin inhibits mucus hypersecretion and infiltration of eosinophils and neutrophils in allergic inflammation, though the inhibitory effect against mucus production is obtained in high-dose heparin. Intranasal instillation with high-dose heparin may provide a new therapeutic strategy for the treatment of nasal allergic inflammation.

Asthma and coagulation

Asthma is a chronic airway disease characterized by paroxysmal airflow obstruction evoked by irritative stimuli on a background of allergic lung inflammation. Currently, there is no cure for asthma, only symptomatic treatment. In recent years, our understanding of the involvement of coagulation and anticoagulant pathways, the fibrinolytic system, and platelets in the pathophysiology of asthma has increased considerably. Asthma is associated with a procoagulant state in the bronchoalveolar space, further aggravated by impaired local activities of the anticoagulant protein C system and fibrinolysis. Protease-activated receptors have been implicated as the molecular link between coagulation and allergic inflammation in asthma. This review summarizes current knowledge of the impact of the disturbed hemostatic balance in the lungs on asthma severity and manifestations and identifies new possible targets for asthma treatment.

Role of thrombin in chronic rhinosinusitis-associated tissue remodeling

BACKGROUND

Thrombin, the effector enzyme of the coagulation system, has been reported to promote inflammatory responses in nasal diseases through its protease-activated receptors (PARs). Chronic rhinosinusitis (CRS) is characterized by increased deposition of extracellular matrix proteins, tissue remodeling, and formation of nasal polyps. The role of thrombin in chronic nasal inflammation-associated tissue remodeling still has not been appraised. This study was conducted to elucidate the role of thrombin in the pathogenesis of CRS.

METHODS

Nasal secretion was collected from patients with CRS with nasal polyp (CRSwNP) with asthma (n = 9), CRSwNP without asthma (n = 10), allergic rhinitis (n = 7), and control patients (n = 3). The concentrations of thrombin, thrombin-antithrombin (TAT) complex, and vascular endothelial growth factor (VEGF) were evaluated by enzyme immunoassays. The concentration of thrombin and TAT complex was measured in nasal secretion from each group of patients, and VEGF was measured in culture medium from airway epithelial cells treated with thrombin or thrombin receptor agonist peptide.

RESULTS

Thrombin and TAT complex were significantly increased in nasal secretion of patients with CRSwNPs with asthma compared with the control group. Thrombin and PAR-1 agonist peptide significantly stimulated VEGF secretion from cultured human airway epithelial cells.

CONCLUSION

The results of this study showed that there is increased activation of the coagulation system in the nasal mucosa of CRS patients and that thrombin may play a role in nasal polyp formation by stimulating VEGF production from airway epithelial cells.

Heparin inhibits mucus hypersecretion in airway epithelial cells

BACKGROUND

Heparin is one of the most important anticoagulant drugs. It has been known that heparin also possesses anti-inflammatory activities. Mucus hypersecretion is an important characteristic of airway inflammation. However, little is known about the regulatory effects of heparin on mucus hypersecretion in airway epithelial cells. To elucidate the anti-inflammatory function of heparin in airway epithelial cells, we examined the in vivo effects of heparin on mucus hypersecretion and neutrophil infiltration in rat nasal epithelium. We also examined the in vitro effects of heparin on mucin production and IL-8 secretion from cultured human airway epithelial cells.

METHODS

We induced hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium by intranasal lipopolysaccharide (LPS) instillation. The effects of intranasal instillation with heparin on mucus production and neutrophil infiltration were examined. in vitro effects of heparin on airway epithelial cells were examined using cultured NCI-H292 cells. Mucus secretion was evaluated by enzyme-linked immunosorbent assay using an anti-MUC5AC monoclonal antibody.

RESULTS

Intranasal instillation with unfractionated heparin (UFH; 100 IU/0.1 mL) or low molecular weight heparin (LMWH; 100 IU/0.1 mL) at 30 minutes before LPS instillation significantly inhibited LPS-induced mucus production and neutrophil infiltration in rat nasal epithelium. UFH or LMWH inhibited tumor necrosis factor alpha (10 ng/mL)-induced secretion of MUC5AC and IL-8 from NCI-H292 cells in a dose-dependent manner (0.01-10 IU/mL). MUC5AC mRNA expression was also significantly inhibited.

CONCLUSION

These results indicate that heparin inhibits airway mucus hypersecretion in airway epithelial cells directly and indirectly through the suppression of IL-8 secretion and neutrophil infiltration.

Role of thrombin-activatable fibrinolysis inhibitor in allergic bronchial asthma

BACKGROUND

Bronchial asthma is an inflammatory disease of the airways. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a carboxypeptidase that besides inhibiting fibrinolysis, also regulates inflammatory processes. The only validated substrate known for TAFI is fibrin. In the present study we evaluated the role of TAFI in bronchial asthma by comparing the development of allergic bronchial asthma between wild-type (WT) and TAFI-deficient mice (KO).

METHODS

Asthmatic inflammation was induced by sensitization and challenge with ovalbumin in WT (WT/OVA) and TAFI KO (KO/OVA) mice. WT mice (WT/SAL) and TAFI KO (KO/SAL) were used as controls. Cytokines, markers of inflammation, and coagulation were measured in bronchoalveolar lavage fluid (BALF).

RESULTS

Airway hyperresponsiveness was worse in KO/OVA mice than in WT/OVA mice or control mice. Markers of lung injury were significantly increased in BALF from KO/OVA mice compared to WT/OVA mice. Airway hyperresponsiveness and the BALF concentrations of IL-5 and osteopontin were significantly increased in KO/OVA mice compared to WT/OVA mice. Treatment of WT/OVA and KO/OVA mice with a C5a receptor antagonist significantly decreased hyperresponsiveness along with the BALF concentrations of total protein and C5a compared to untreated asthmatic mice.

CONCLUSION

The results of this study suggest that TAFI plays a protective role in the pathogenesis of allergic inflammation probably by inhibiting the complement system.

The roles of thrombin and protease-activated receptors in inflammation

Inflammation and coagulation constitute two host defence systems with complementary physiological roles in limiting tissue damage, restoring homeostasis and eliminating invading pathogens, functions reliant on effective regulation of both processes at a variety of levels. Dysfunctional activation or regulation of either pathway may lead to pathology and contribute to human diseases as diverse as myocardial infarction and septic shock. The serine protease thrombin, a key protein in the coagulation pathway, can activate cellular signalling directly via proteolytic cleavage of the N-terminal domain of a family of G protein-coupled receptors or indirectly through the generation of molecules such as activated protein C. These events transmit signals to many cell types and can elicit the production of various pro-inflammatory mediators such as cytokines, chemokines and growth factors, thereby influencing cell activation, differentiation, survival and migration. This review discusses recent progress in understanding how thrombin and protease-activated receptors influence biological processes, highlighting the detrimental and protective cellular effects of thrombin and its signalling pathways.

Receptor-promoted exocytosis of airway epithelial mucin granules containing a spectrum of adenine nucleotides

Purinergic regulation of airway innate defence activities is in part achieved by the release of nucleotides from epithelial cells. However, the mechanisms of airway epithelial nucleotide release are poorly understood. We have previously demonstrated that ATP is released from ionomycin-stimulated airway epithelial goblet cells coordinately with mucin exocytosis, suggesting that ATP is released as a co-cargo molecule from mucin-containing granules. We now demonstrate that protease-activated-receptor (PAR) agonists also stimulate the simultaneous release of mucins and ATP from airway epithelial cells. PAR-mediated mucin and ATP release were dependent on intracellular Ca(2+) and actin cytoskeleton reorganization since BAPTA AM, cytochalasin D, and inhibitors of Rho and myosin light chain kinases blocked both responses. To test the hypothesis that ATP is co-released with mucin from mucin granules, we measured the nucleotide composition of isolated mucin granules purified based on their MUC5AC and VAMP-8 content by density gradients. Mucin granules contained ATP, but the levels of ADP and AMP within granules exceeded by nearly 10-fold that of ATP. Consistent with this finding, apical secretions from PAR-stimulated cells contained relatively high levels of ADP/AMP, which could not be accounted for solely based on ATP release and hydrolysis. Thus, mucin granules contribute to ATP release and also are a source of extracellular ADP and AMP. Direct release of ADP/AMP from mucin granules is likely to provide a major source of airway surface adenosine to signal in a paracrine faction ciliated cell A(2b) receptors to activate ion/water secretion and appropriately hydrate goblet cell-released mucins.

The protein C pathway in tissue inflammation and injury: pathogenic role and therapeutic implications

Inflammation and coagulation are closely linked interdependent processes. Under physiologic conditions, the tissue microcirculation functions in anticoagulant and anti-inflammatory fashions. However, when inflammation occurs, coagulation is also set in motion and actively participates in enhancing inflammation. Recently, novel and unexpected roles of hemostasis in the humoral and cellular components of innate immunity have been described. In particular, the protein C system, besides its well-recognized role in anticoagulation, plays a crucial role in inflammation. Indeed, the protein C system is now emerging as a novel participant in the pathogenesis of acute and chronic inflammatory diseases, such as sepsis, asthma, inflammatory bowel disease, atherosclerosis, and lung and heart inflammation, and may emerge as unexpected therapeutic targets for intervention.

The protein C pathway in tissue inflammation and injury: pathogenic role and therapeutic implications

Inflammation and coagulation are closely linked interdependent processes. Under physiologic conditions, the tissue microcirculation functions in anticoagulant and anti-inflammatory fashions. However, when inflammation occurs, coagulation is also set in motion and actively participates in enhancing inflammation. Recently, novel and unexpected roles of hemostasis in the humoral and cellular components of innate immunity have been described. In particular, the protein C system, besides its well-recognized role in anticoagulation, plays a crucial role in inflammation. Indeed, the protein C system is now emerging as a novel participant in the pathogenesis of acute and chronic inflammatory diseases, such as sepsis, asthma, inflammatory bowel disease, atherosclerosis, and lung and heart inflammation, and may emerge as unexpected therapeutic targets for intervention.