Immunofluorescence studies of lung tissue in cystic fibrosis

Fibrinogen on extracellular vesicles derived from polyhexamethylene guanidine phosphate-exposed mice induces inflammatory effects via integrin β

Polyhexamethylene guanidine phosphate (PHMG-p), used as a humidifier disinfectant, causes interstitial lung disease, obliterative bronchiolitis, and lung fibrosis; however, little is known about its effect on intercellular interactions. Extracellular vesicles (EVs), which carry diverse compounds including proteins, RNA, and DNA to mediate cell-to-cell communication through their paracrine effects, have been highlighted as novel factors in lung fibrogenesis. This study aimed to identify the effect of proteins on small EVs (sEVs) from bronchoalveolar lavage fluid (BALF) of the recipient cells after PHMG-p exposure. A week after intratracheal administration of PHMG-p, sEVs were isolated from BALF of tissue showing overexpressed inflammatory and fibrosis markers. To investigate the role of sEVs in inflammation, naïve macrophages were cultured with sEVs, which induced their activation. To identify sEV proteins that are associated with these responses, proteomics analysis was performed. In the gene ontology analysis, coagulation, fibrinolysis, and hemostasis were associated with the upregulated proteins in sEVs. The highest increase was observed in fibrinogen levels, which was also related to those gene ontologies. We validated role of exosomal fibrinogen in inflammation using recombinant fibrinogen and an inhibitor of the integrin, which is the binding receptor for fibrinogen. Overall, we elucidated that increased fibrinogen levels in the early sEVs-PHMG activated inflammatory response during early fibrosis. These results suggest that sEVs from the BALF of PHMG-p-exposed mice could aggravate fibrogenesis by activating naïve macrophages via various proteins in the sEVs, Furthermore, this finding will be broadening the spectrum of communicating mediators.

Are elevated plasma fibrinogen associated with lung function? An 8-year follow-up of the ELSA study

Background

Fibrinogen is an important biomarker of inflammation, but findings from longitudinal studies that correlated fibrinogen with lung function in older adults are inconsistent.

Aim

To investigate the relationship between fibrinogen plasma levels and lung function impairment later in life.

Methods

Longitudinal analysis of 2,150 participants of the English Longitudinal Study of Ageing (ELSA) aged 50 years and older. Associations between changes in plasma fibrinogen between waves 2 (2004–05) and 4 (2008–09) and lung function in wave 6 (2012–13) were performed using multiple linear regression adjusted by potential confounders.

Results

Regarding the fibrinogen profile, 18.5% of the participants presented higher levels in both waves. In the adjusted models, the maintenance of high fibrinogen levels was associated with a significant reduction of lung function only for men. FEV₁ showed a reduction of 0.17L, FVC of 0.22L, and the percentages predicted were 5.16% for FEV₁ and 6.21% for FVC compared to those that maintained normal levels of fibrinogen.

Discussion

To the best of our knowledge, this was the first study investigating the relationship between changes in fibrinogen levels over a long follow-up period and lung function in older adults without pre-existing chronic diseases. ELSA has information on critical demographic and clinical parameters, which allowed to adjust for potential confounding factors.

Conclusion

It was found that the persistence of high levels of plasma fibrinogen in older English men, but not women, is associated with lung function decline. Therefore, plasma fibrinogen showed to be an important biomarker of pulmonary dysfunction in this population.

Mechanisms of endothelial cell dysfunction in cystic fibrosis

Although cystic fibrosis (CF) patients exhibit signs of endothelial perturbation, the functions of the cystic fibrosis conductance regulator (CFTR) in vascular endothelial cells (EC) are poorly defined. We sought to uncover biological activities of endothelial CFTR, relevant for vascular homeostasis and inflammation. We examined cells from human umbilical cords (HUVEC) and pulmonary artery isolated from non-cystic fibrosis (PAEC) and CF human lungs (CF-PAEC), under static conditions or physiological shear. CFTR activity, clearly detected in HUVEC and PAEC, was markedly reduced in CF-PAEC. CFTR blockade increased endothelial permeability to macromolecules and reduced trans‑endothelial electrical resistance (TEER). Consistent with this, CF-PAEC displayed lower TEER compared to PAEC. Under shear, CFTR blockade reduced VE-cadherin and p120 catenin membrane expression and triggered the formation of paxillin- and vinculin-enriched membrane blebs that evolved in shrinking of the cell body and disruption of cell-cell contacts. These changes were accompanied by enhanced release of microvesicles, which displayed reduced capability to stimulate proliferation in recipient EC. CFTR blockade also suppressed insulin-induced NO generation by EC, likely by inhibiting eNOS and AKT phosphorylation, whereas it enhanced IL-8 release. Remarkably, phosphodiesterase inhibitors in combination with a β₂ adrenergic receptor agonist corrected functional and morphological changes triggered by CFTR dysfunction in EC. Our results uncover regulatory functions of CFTR in EC, suggesting a physiological role of CFTR in the maintenance EC homeostasis and its involvement in pathogenetic aspects of CF. Moreover, our findings open avenues for novel pharmacology to control endothelial dysfunction and its consequences in CF.

Fibrinogen binding to ICAM-1 promotes EGFR-dependent mucin production in human airway epithelial cells

Mucous hypersecretion is a serious feature of chronic airway diseases such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. Although mucins are produced via activation of an EGF receptor (EGFR) signaling cascade, the mechanisms leading to exaggerated mucin production in mucous hypersecretory diseases are unknown. Because expression of ICAM-1 and of the ICAM-1 ligand fibrinogen is increased in the airways of subjects with mucous hypersecretory diseases, we hypothesized that fibrinogen binding to ICAM-1 could increase EGFR-dependent mucin production in human airway (NCI-H292) epithelial cells. Consistent with this hypothesis, we found that an ICAM-1 neutralizing antibody and an ICAM-1(8-22) peptide that binds fibrinogen decreased mucin production induced by the EGFR ligand transforming growth factor (TGF)-alpha dose-dependently. Exogenous fibrinogen and a fibrinogen(117-133) peptide that binds ICAM-1 rescued mucin production in cells treated with the ICAM-1(8-22) peptide. Surprisingly, the ICAM-1(8-22) peptide increased EGFR phosphotyrosine and phospho-ERK1/2 in cells treated with TGF-alpha. The ICAM-1(8-22) peptide-induced increases in EGFR phosphotyrosine and phospho-ERK1/2 were prevented by exogenous fibrinogen, by the fibrinogen(117-133) peptide, and by selective inhibitors of phospholipase C (PLC), protein kinase C (PKC)-alpha/beta, and metalloproteases. These results suggest that fibrinogen binding to ICAM-1 promotes mucin production by decreasing TGF-alpha-induced EGFR and ERK1/2 activation and that the fibrinogen-ICAM-1-dependent decrease in EGFR and ERK1/2 activation occurs via inhibition of an early positive feedback pathway involving PLC- and PKC-alpha/beta-dependent metalloprotease activation and subsequent metalloprotease-dependent EGFR reactivation.

Anti-interleukin 8 autoantibody:interleukin 8 immune complexes visualized by laser confocal microscopy in injured lung

CONTEXT

Anti-interleukin 8 autoantibody:interleukin 8 (anti-IL-8 autoantibody:IL-8) complexes are present in lung fluids of patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS), and levels of these complexes correlate with progression to and the outcome of ARDS. Fc gammaRIIa, an immunoglobulin G (IgG) receptor, mediates proinflammatory activity of the complexes.

OBJECTIVE

To evaluate lung tissues from patients with ARDS for presence of anti-IL-8 autoantibody:IL-8 complexes and to establish whether the complexes associate with Fc gammaRIIa.

DESIGN

Lung tissue sections from 3 patients with ARDS and sections of normal lung tissues from 3 patients were stained with antibodies against IL-8 and IgG to detect immune complexes and with antibody against Fc gammaRIIa. In some experiments, sections were blocked with anti-Fc gamma RIIa antibody before staining. Samples were analyzed using confocal microscopy.

RESULTS

Interleukin 8 costained with IgG and Fc gammaRIIa in lung tissues from patients with ARDS but not in control tissues, suggesting that anti-IL-8 autoantibody:IL-8 complexes are deposited in lungs of patients with ARDS via Fc gammaRIIa. Further, colocalization between IL-8 and Fc gammaRIIa could be blocked by anti-Fc gammaRIIa.

CONCLUSIONS

Our data demonstrate that anti-IL-8 autoantibody:IL-8 complexes are present in lung tissues of patients with ARDS, and are attached to Fc gammaRIIa.