Circulating adhesion molecules in cystic fibrosis

Pulmonary Vascular Dysfunctions in Cystic Fibrosis

Cystic fibrosis (CF) is an inherited disorder caused by a deleterious mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Given that the CFTR protein is a chloride channel expressed on a variety of cells throughout the human body, mutations in this gene impact several organs, particularly the lungs. For this very reason, research regarding CF disease and CFTR function has historically focused on the lung airway epithelium. Nevertheless, it was discovered more than two decades ago that CFTR is also expressed and functional on endothelial cells. Despite the great strides that have been made in understanding the role of CFTR in the airway epithelium, the role of CFTR in the endothelium remains unclear. Considering that the airway epithelium and endothelium work in tandem to allow gas exchange, it becomes very crucial to understand how a defective CFTR protein can impact the pulmonary vasculature and overall lung function. Fortunately, more recent research has been dedicated to elucidating the role of CFTR in the endothelium. As a result, several vascular dysfunctions associated with CF disease have come to light. Here, we summarize the current knowledge on pulmonary vascular dysfunctions in CF and discuss applicable therapies.

HIGH THROUGHPUT QUANTITATION OF HUMAN NEUTROPHIL RECRUITMENT AND FUNCTIONAL RESPONSES IN AN AIR-BLOOD BARRIER ARRAY

Dysregulated neutrophil recruitment drives many pulmonary diseases, but most preclinical screening methods are unsuited to evaluate pulmonary neutrophilia, limiting progress towards therapeutics. Namely, high throughput therapeutic screening systems typically exclude critical neutrophilic pathophysiology, including blood-to-lung recruitment, dysfunctional activation, and resulting impacts on the air-blood barrier. To meet the conflicting demands of physiological complexity and high throughput, we developed an assay of 96-well Leukocyte recruitment in an Air-Blood Barrier Array (L-ABBA-96) that enables in vivo -like neutrophil recruitment compatible with downstream phenotyping by automated flow cytometry. We modeled acute respiratory distress syndrome (ARDS) with neutrophil recruitment to 20 ng/mL epithelial-side interleukin 8 (IL-8) and found a dose dependent reduction in recruitment with physiologic doses of baricitinib, a JAK1/2 inhibitor recently FDA-approved for severe COVID-19 ARDS. Additionally, neutrophil recruitment to patient-derived cystic fibrosis sputum supernatant induced disease-mimetic recruitment and activation of healthy donor neutrophils and upregulated endothelial e-selectin. Compared to 24-well assays, the L-ABBA-96 reduces required patient sample volumes by 25 times per well and quadruples throughput per plate. Compared to microfluidic assays, the L-ABBA-96 recruits two orders of magnitude more neutrophils per well, enabling downstream flow cytometry and other standard biochemical assays. This novel pairing of high-throughput in vitro modeling of organ-level lung function with parallel high-throughput leukocyte phenotyping substantially advances opportunities for pathophysiological studies, personalized medicine, and drug testing applications.

Multimodal analysis of granulocytes, monocytes, and platelets in patients with cystic fibrosis before and after Elexacaftor-Tezacaftor-Ivacaftor treatment

Cystic fibrosis (CF) is a monogenetic disease caused by an impairment of the cystic fibrosis transmembrane conductance regulator (CFTR). CF affects multiple organs and is associated with acute and chronic inflammation. In 2020, Elexacaftor-Tezacaftor-Ivacaftor (ETI) was approved to enhance and restore the remaining CFTR functionality. This study investigates cellular innate immunity, with a focus on neutrophil activation and phenotype, comparing healthy volunteers with patients with CF before (T1, n = 13) and after six months (T2, n = 11) of ETI treatment. ETI treatment reduced sweat chloride (T1: 95 mmol/l (83|108) vs. T2: 32 mmol/l (25|62), p < 0.01, median, first|third quartile) and significantly improved pulmonal function (FEV₁ T1: 2.66 l (1.92|3.04) vs. T2: 3.69 l (3.00|4.03), p < 0.01). Moreover, there was a significant decrease in the biomarker human epididymis protein 4 (T1: 6.2 ng/ml (4.6|6.3) vs. T2: 3.0 ng/ml (2.2|3.7), p < 0.01) and a small but significant decrease in matrix metallopeptidase 9 (T1: 45.5 ng/ml (32.5|140.1) vs. T2: 28.2 ng/ml (18.2|33.6), p < 0.05). Neutrophil phenotype (CD10, CD11b, CD62L, and CD66b) and function (radical oxygen species generation, chemotactic and phagocytic activity) remained largely unaffected by ETI treatment. Likewise, monocyte phenotype and markers of platelet activation were similar at T1 and T2. In summary, the present study confirmed a positive impact on patients with CF after ETI treatment. However, neither beneficial nor harmful effects of ETI treatment on cellular innate immunity could be detected, possibly due to the study population consisting of patients with well-controlled CF.

Respiratory Infection and Inflammation in Cystic Fibrosis: A Dynamic Interplay among the Host, Microbes, and Environment for the Ages

The interplay between airway inflammation and infection is now recognized as a major factor in the pathobiology in cystic fibrosis (CF). A proinflammatory environment is seen throughout the CF airway resulting in classic marked and enduring neutrophilic infiltrations, irreversibly damaging the lung. Although this is seen to occur early, independent of infection, respiratory microbes arising at different timepoints in life and the world environment perpetuate this hyperinflammatory state. Several selective pressures have allowed for the CF gene to persist until today despite an early mortality. Comprehensive care systems, which have been a cornerstone of therapy for the past few decades, are now revolutionized by CF transmembrane conductance regulator (CTFR) modulators. The effects of these small-molecule agents cannot be overstated and can be seen as early as in utero. For an understanding of the future, this review looks into CF studies spanning the historical and present period.

Age-Related Progression of Microvascular Dysfunction in Cystic Fibrosis: New Detection Ways and Clinical Outcomes

There are concerns about altered vascular functions that could play an important role in the pathogenesis and influence the severity of chronic disease, however, increased cardiovascular risk in paediatric cystic fibrosis (CF) has not been yet fully understood. Aim was to analyse vascular disease risk and investigate changes over times in CF and controls. We prospectively enrolled 22 CF subjects (a median age of 16.07 years), and 22 healthy demographically matched controls (a median age of 17.28 years) and determined endothelial function. We utilised a combined diagnostic approach by measuring the plethysmographic Reactive Hyperemia Index (RHI) as the post-to preocclusive endothelium-dependent changes of vascular tone, and biomarkers that are known to be related to endothelial dysfunction (ED): asymmetric dimethyl arginine (ADMA), high-sensitive CRP (hsCRP), VCAM-1 and E-selectin. RHI values were significantly lower in CF young adults (p<0.005). HsCRP (p<0.005), E-selectin (p<0.001) and VCAM-1 (p<0.001) were significantly increased in CF patients since childhood. The findings have provided a detailed account of the ongoing process of microvascular dysfunction with gradual progression with the age of CF patients, making them further at risk of advanced vascular disease. Elevations of biomarkers in CF children with not yet demonstrated RHI changes but with significantly reduced RHI in adulthood and lipid profile changes indicate the possible occurrence of ED with CF-related specific risk factors over time and will enable us to provide the best possible support.

Transcriptomic analysis of CFTR-impaired endothelial cells reveals a pro-inflammatory phenotype

Cystic fibrosis (CF) is a life-threatening disorder characterised by decreased pulmonary mucociliary and pathogen clearance, and an exaggerated inflammatory response leading to progressive lung damage. CF is caused by bi-allelic pathogenic variants of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a chloride channel. CFTR is expressed in endothelial cells (ECs) and EC dysfunction has been reported in CF patients, but a role for this ion channel in ECs regarding CF disease progression is poorly described.We used an unbiased RNA sequencing approach in complementary models of CFTR silencing and blockade (by the CFTR inhibitor CFTRinh-172) in human ECs to characterise the changes upon CFTR impairment. Key findings were further validated in vitro and in vivo in CFTR-knockout mice and ex vivo in CF patient-derived ECs.Both models of CFTR impairment revealed that EC proliferation, migration and autophagy were downregulated. Remarkably though, defective CFTR function led to EC activation and a persisting pro-inflammatory state of the endothelium with increased leukocyte adhesion. Further validation in CFTR-knockout mice revealed enhanced leukocyte extravasation in lung and liver parenchyma associated with increased levels of EC activation markers. In addition, CF patient-derived ECs displayed increased EC activation markers and leukocyte adhesion, which was partially rescued by the CFTR modulators VX-770 and VX-809.Our integrated analysis thus suggests that ECs are no innocent bystanders in CF pathology, but rather may contribute to the exaggerated inflammatory phenotype, raising the question of whether normalisation of vascular inflammation might be a novel therapeutic strategy to ameliorate the disease severity of CF.

Neutrophil dysfunction in cystic fibrosis

BACKGROUND

Excessive neutrophil inflammation is the hallmark of cystic fibrosis (CF) airway disease. Novel technologies for characterizing neutrophil dysfunction may provide insight into the nature of these abnormalities, revealing a greater mechanistic understanding and new avenues for CF therapies that target these mechanisms.

METHODS

Blood was collected from individuals with CF in the outpatient clinic, CF individuals hospitalized for a pulmonary exacerbation, and non-CF controls. Using microfluidic assays and advanced imaging technologies, we characterized 1) spontaneous neutrophil migration using microfluidic motility mazes, 2) neutrophil migration to and phagocytosis of Staphylococcal aureus particles in a microfluidic arena, 3) neutrophil swarming on Candida albicans clusters, and 4) Pseudomonas aeruginosa-induced neutrophil transepithelial migration using micro-optical coherence technology (µOCT).

RESULTS

Participants included 44 individuals: 16 Outpatient CF, 13 Hospitalized CF, and 15 Non-CF individuals. While no differences were seen with spontaneous migration, CF neutrophils migrated towards S. aureus particles more quickly than non-CF neutrophils (p < 0.05). CF neutrophils, especially Hospitalized CF neutrophils, generated significantly larger aggregates around S. aureus particles over time. Hospitalized CF neutrophils were more likely to have dysfunctional swarming (p < 0.01) and less efficient clearing of C. albicans (p < 0.0001). When comparing trans-epithelial migration towards Pseudomonas aeruginosa epithelial infection, Outpatient CF neutrophils displayed an increase in the magnitude of transmigration and adherence to the epithelium (p < 0.05).

CONCLUSIONS

Advanced technologies for characterizing CF neutrophil function reveal significantly altered migratory responses, cell-to-cell clustering, and microbe containment. Future investigations will probe mechanistic basis for abnormal responses in CF to identify potential avenues for novel anti-inflammatory therapeutics.

Opportunistic bacteria confer the ability to ferment prebiotic starch in the adult cystic fibrosis gut

Chronic disruption of the intestinal microbiota in adult cystic fibrosis (CF) patients is associated with local and systemic inflammation, and has been linked to the risk of serious comorbidities. Supplementation with high amylose maize starch (HAMS) might provide clinical benefit by promoting commensal bacteria and the biosynthesis of immunomodulatory metabolites. However, whether the disrupted CF gut microbiota has the capacity to utilise these substrates is not known. We combined metagenomic sequencing, in vitro fermentation, amplicon sequencing, and metabolomics to define the characteristics of the faecal microbiota in adult CF patients and assess HAMS fermentation capacity. Compared to healthy controls, the faecal metagenome of adult CF patients had reduced bacterial diversity and prevalence of commensal fermentative clades. In vitro fermentation models seeded with CF faecal slurries exhibited reduced acetate levels compared to healthy control reactions, but comparable levels of butyrate and propionate. While the commensal genus Faecalibacterium was strongly associated with short chain fatty acid (SCFA) production by healthy microbiota, it was displaced in this role by Clostridium sensu stricto 1 in the microbiota of CF patients. A subset of CF reactions exhibited enterococcal overgrowth, resulting in lactate accumulation and reduced SCFA biosynthesis. The addition of healthy microbiota to CF faecal slurries failed to displace predominant CF taxa, or substantially influence metabolite biosynthesis. Despite significant microbiota disruption, the adult CF gut microbiota retains the capacity to exploit HAMS. Our findings highlight the potential for taxa associated with the altered CF gut microbiotato mediate prebiotic effects in microbial systems subject to ongoing perturbation, irrespective of the depletion of common commensal clades.

Neutrophil Membrane Cholesterol Content is a Key Factor in Cystic Fibrosis Lung Disease

Background

Identification of mechanisms promoting neutrophil trafficking to the lungs of patients with cystic fibrosis (CF) is a challenge for next generation therapeutics. Cholesterol, a structural component of neutrophil plasma membranes influences cell adhesion, a key step in transmigration. The effect of chronic inflammation on neutrophil membrane cholesterol content in patients with CF (PWCF) remains unclear. To address this we examined neutrophils of PWCF to evaluate the cause and consequence of altered membrane cholesterol and identified the effects of lung transplantation and ion channel potentiator therapy on the cellular mechanisms responsible for perturbed membrane cholesterol and increased cell adhesion.

Methodology

PWCF homozygous for the ΔF508 mutation or heterozygous for the G551D mutation were recruited (n = 48). Membrane protein expression was investigated by mass spectrometry. The effect of lung transplantation or ivacaftor therapy was assessed by ELISAs, and calcium fluorometric and μ-calpain assays.

Findings

Membranes of CF neutrophils contain less cholesterol, yet increased integrin CD11b expression, and respond to inflammatory induced endoplasmic reticulum (ER) stress by activating μ-calpain. In vivo and in vitro, increased μ-calpain activity resulted in proteolysis of the membrane cholesterol trafficking protein caveolin-1. The critical role of caveolin-1 for adequate membrane cholesterol content was confirmed in caveolin-1 knock-out mice. Lung transplant therapy or treatment of PWCF with ivacaftor, reduced levels of circulating inflammatory mediators and actuated increased caveolin-1 and membrane cholesterol, with concurrent normalized neutrophil adhesion.

Interpretation

Results demonstrate an auxiliary benefit of lung transplant and potentiator therapy, evident by a reduction in circulating inflammation and controlled neutrophil adhesion.

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This study explored neutrophil adhesion in cystic fibrosis.

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Altered membrane cholesterol lead to increased adhesion.

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Circulating inflammatory mediators caused increased calpain activity and reduced membrane cholesterol content.

In patients with cystic fibrosis (CF), chronic inflammation in the circulation, in part originating from the pulmonary compartment, leads to decreased membrane cholesterol in circulating neutrophils, resulting in increased cell adhesion. The mechanism of action involves proteolytic down-regulation of the cholesterol trafficking protein caveolin-1. The overall effect of lung transplant therapy, or CFTR potentiator treatment, was to significantly diminish the circulating inflammatory burden thereby permitting caveolin-1 expression, with concomitant decreased CF cell adhesion and significant clinical improvement.

Increased Soluble VCAM-1 and Normal P-Selectin in Cystic Fibrosis: a Cross-Sectional Study

Purpose

As life expectancy in cystic fibrosis (CF) increases, questions regarding its potential impact on cardiovascular health arise. Soluble vascular cell adhesion molecule 1 (sVCAM-1), P-selectin (sP-selectin) are proposed as biomarkers of cardiovascular disease. We aimed to: compare their concentrations in clinically stable CF patients and healthy subjects (HS) and verify whether they independently correlate with CF characteristics.

Methods

Serum sVCAM-1 and sP-selectin levels were measured using ELISA. CF was characterized using: forced expiratory volume in 1 s, exocrine pancreatic and CF-related liver disease status, Pseudomonas aeruginosa colonization, serum high-sensitivity C-reactive protein, and body mass index (BMI). CFTR genotypes were classified as severe (classes I and II) or other.

Results

108 CF patients and 51 healthy subjects volunteered for the study. In the CF group BMI was lower (median [IQR]: 20.5 kg/m² [18.4–22.2] vs. 21.6 kg/m² [19.9–23.4], p = 0.02) and hsCRP levels were higher (3.6 mg/L [1.1–7.1] vs. 0.5 mg/dL [0.3–1.0], p < 10⁻¹⁰). While sVCAM-1 concentrations were greater in CF patients (1018 ng/mL [851–1279] vs. 861 ng/mL [806–979], p < 10⁻⁴), sP-selectin levels did not differ (155 ng/mL [129–188] vs. 156 ng/mL [144–177], p = 0.48). None of the multivariable regression models was valid for the prediction of sVCAM-1 and sP-selectin in CF.

Conclusions

We found higher sVCAM-1 concentrations in CF patients than in healthy subjects, which were not explained by CF characteristics. Further research is required to check whether sVCAM-1 is a marker of microangiopathy in CF.

Association between inhaler use and risk of haemoptysis in patients with non-cystic fibrosis bronchiectasis

BACKGROUND AND OBJECTIVE

Inhaled medications have been widely applied to patients with airflow limiting non-cystic fibrosis (non-CF) bronchiectasis. However, the association between the use of inhalers and the development of haemoptysis has rarely been explored. The objective of this study was to assess the association between the risk of haemoptysis and the use of inhalers in patients with non-CF bronchiectasis.

METHODS

A nested case-control study was performed using a national claims database from 1 January 2009 to 31 December 2011. Inhalers including inhaled corticosteroids (ICS), long-acting β2 agonists (LABA), long-acting muscarinic antagonists (LAMA), short-acting β2 agonists (SABA), short-acting muscarinic antagonists (SAMA) and their combinations were tested for the risk of clinically significant haemoptysis events.

RESULTS

Among the 62 530 eligible new users of inhalers with non-CF bronchiectasis, 6180 patients with haemoptysis and 27 486 strictly matched controls were selected. In the unadjusted analyses, SAMA, LAMA, SABA and ICS/LABA significantly increased the risk of haemoptysis. After adjustment for other inhaled respiratory medications, comorbidities, health-care utilization and concomitant medications, SAMA, SABA and LAMA consistently increased the risk of haemoptysis (SAMA: odds ratio (OR), 1.6; 95% confidence interval (CI), 1.1-1.4; LAMA: OR, 1.2; 95% CI: 1.1-1.2; SABA: OR, 1.2; 95% CI: 1.1-1.2). The association between anticholinergics (SAMA and LAMA) and risk of haemoptysis showed a dose-dependent trend (P for trend, <0.001).

CONCLUSIONS

The use of SABA and inhaled anticholinergics in patients with non-CF bronchiectasis increased the risk of haemoptysis. The risk-benefit ratio of inhaled bronchodilators should be considered in the haemoptysis-susceptible population.

Cystic fibrosis transmembrane conductance regulator is involved in polyphenol-induced swelling of the endothelial glycocalyx

Previous studies show that polyphenol-rich compounds can induce a swelling of the endothelial glycocalyx (eGC). Our goal was to reveal the mechanism behind the eGC-swelling. As polyphenols are potent modulators of fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel, the hypothesis was tested whether polyphenol-induced increase in CFTR activity is responsible for the eGC-swelling. The impact of the polyphenols resveratrol, (-)-epicatechin, and quercetin on nanomechanics of living endothelial GM7373 cells was monitored by AFM-nanoindentation. The tested polyphenols lead to eGC-swelling with a simultaneous decrease in cortical stiffness. EGC-swelling, but not the change in cortical stiffness, was prevented by the inhibition of CFTR. Polyphenol-induced eGC-swelling could be mimicked by cytochalasin D, an actin-depolymerizing agent. Thus, in the vascular endothelium, polyphenols induce eGC-swelling by softening cortical actin and activating CFTR. Our findings imply that CFTR plays an important role in the maintenance of vascular homeostasis and may explain the vasoprotective properties of polyphenols.

FROM THE CLINICAL EDITOR

Many vascular problems clinically can be attributed to a dysregulation of endothelial glycocalyx (eGC). The underlying mechanism however remains unclear. In this article, the authors used nanoindentation and showed that polyphenols could swell the endothelial glycocalyx and alter its function. This investigative method can lead to further mechanistic studies of other molecular pathways.

Inflammation, oxidative stress, and cardiovascular disease risk factors in adults with cystic fibrosis

Cystic fibrosis (CF) represents one of a number of localized lung and non-lung diseases with an intense chronic inflammatory component associated with evidence of systemic oxidative stress. Many of these chronic inflammatory diseases are accompanied by an array of atherosclerotic processes and cardiovascular disease (CVD), another condition strongly related to inflammation and oxidative stress. As a consequence of a dramatic increase in long-lived patients with CF in recent decades, the specter of CVD must be considered in these patients who are now reaching middle age and beyond. Buttressed by recent data documenting that CF patients exhibit evidence of endothelial dysfunction, a recognized precursor of atherosclerosis and CVD, the spectrum of risk factors for CVD in CF is reviewed here. Epidemiological data further characterizing the presence and extent of atherogenic processes in CF patients would seem important to obtain. Such studies should further inform and offer mechanistic insights into how other chronic inflammatory diseases potentiate the processes leading to CVDs.

Systematic review of blood biomarkers in cystic fibrosis pulmonary exacerbations

BACKGROUND

Biomarkers reflective of disease activity in cystic fibrosis (CF) have the potential to improve patient care, particularly during CF pulmonary exacerbations (CFPEs). Although blood-based biomarkers have been studied in CFPE for nearly 3 decades, none have been integrated into routine clinical practice. To facilitate progress in this area, we performed a systematic review evaluating blood-based biomarkers during CFPE.

METHODS

MEDLINE, EMBASE, and CENTRAL were searched to identify relevant studies published from January 1995 to August 2012. We included all full-text studies examining systemic (blood-based) biomarkers to aid in the diagnosis of CFPE, predict outcomes of CFPE, and/or monitor the response to CFPE treatment.

RESULTS

Seventy-eight unique blood-based biomarkers have been studied to date, mainly inflammatory cytokines, acute phase reactants, and markers of oxidative stress. C-reactive protein (CRP) consistently correlated with disease activity, with a statistically significant increase from stable to exacerbation state in five of six studies, and changes in response to CFPE treatment, with a statistically significant decrease from the beginning to the end of CFPE treatment in 18 of 20 studies. Other promising biomarkers of CFPE disease activity include neutrophil elastase antiproteinase complex, IL-6, myeloperoxidase (MPO), lactoferrin, and calprotectin.

CONCLUSIONS

Although there are several blood-based biomarkers with evidence for application within the CFPE setting, CRP has been the most widely studied biomarker demonstrating the potential for clinical usefulness. Further validation studies and clinical trials are required to determine whether blood-based biomarkers can be used to ultimately improve health outcomes in the setting of a CFPE.

Short- and long-term antibiotic treatment reduces airway and systemic inflammation in non-cystic fibrosis bronchiectasis

RATIONALE

The vicious cycle hypothesis of bronchiectasis argues that bacterial colonization leads to airway inflammation and progressive lung damage. The logical extension of this hypothesis is that acute or chronic antibiotic therapy should improve airway inflammation and clinical outcome. There are little data to support this hypothesis in patients with non-cystic fibrosis (CF) bronchiectasis.

OBJECTIVES

To determine whether acute or chronic antibiotic therapy improves airway inflammation and clinical outcome in non-CF bronchiectasis.

METHODS

The relationship between bacterial load and airway and systemic inflammation was investigated in 385 stable patients, 15 stable patients treated with intravenous antibiotics, and 34 patients with an exacerbation of bronchiectasis treated with intravenous antibiotics. Long-term antibiotic therapy was investigated using samples from a 12-month controlled trial of nebulized gentamicin.

MEASUREMENTS AND MAIN RESULTS

In stable patients, there was a direct relationship between airway bacterial load and markers of airway inflammation (P < 0.0001 for all analyses). High bacterial loads were associated with higher serum intercellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 (P < 0.05 above bacterial load ≥1 × 10(7) cfu/ml). In stable patients, there was a direct relationship between bacterial load and the risk of subsequent exacerbations (odds ratio, 1.20; 95% confidence interval, 1.11-1.29; P < 0.0001) and severe exacerbations (odds ratio, 1.11; 95% confidence interval, 1.01-1.21; P = 0.02). Short- and long-term antibiotic treatments were associated with reductions in bacterial load, airways, and systemic inflammation.

CONCLUSIONS

High airway bacterial loads in non-CF bronchiectasis are associated with airway and systemic inflammation and a greater risk of exacerbations. Short- and long-term antibiotic therapy reduce markers of airways and systemic inflammation.

ExoU modulates soluble and membrane-bound ICAM-1 in Pseudomonas aeruginosa-infected endothelial cells

ExoU, a Pseudomonas aeruginosa cytotoxin injected via the type III secretion system into host cells, possesses eicosanoid-mediated proinflammatory properties due to its phospholipase A(2) (PLA(2)) activity. This report addressed the question whether ExoU may modulate the expression of adhesion molecules in host cells, therefore contributing to the recruitment of leukocyte into infected tissues. ExoU was shown to down-regulate membrane-bound ICAM-1 (mICAM-1) and up-regulate the release of soluble ICAM-1 (sICAM-1) from P. aeruginosa-infected endothelial cells. The modulation of ICAM-1 depended on the direct effect of the ExoU PLA(2) activity and involved the cyclooxygenase (COX) pathway. No differences in mICAM-1 and sICAM-1 mRNA levels were observed when cultures were infected with the ExoU-producing PA103 strain or the mutant PA103DeltaexoU, suggesting that ExoU may proteolytically cleave mICAM-1, producing sICAM-1 in a COX-dependent pathway.

Recurrent exacerbations affect FEV(1) decline in adult patients with cystic fibrosis

Obstructive lung disease is the major cause of morbidity and mortality in cystic fibrosis (CF). To identify risk factors contributing to FEV(1) decline in CF patients, we carried out a retrospective analysis of clinical and pulmonary function data in a population of CF patients followed up for 5 years and studied the correlation between clinical data and FEV(1) decline. Fifty-one adult CF patients were studied. The FEV(1) decline was related to the following clinical characteristics: CFTR genotype, age, gender, weight, height, age at diagnosis, baseline FEV(1), pancreatic function, presence of airway infection, pancreatic insufficiency and diabetes, number of exacerbations/year and intravenous (i.v.) antibiotic courses/year. Both the number of exacerbations/year and the number of i.v. antibiotic courses/year were strongly related to the FEV(1) decline. Patients with airway infection or with diabetes had significantly lower FEV(1) values during the study as compared with non-infected patients or patients without diabetes; however, both the presence of airway infection or diabetes did not affect the FEV(1) decline. These results suggest that the aggressive treatment of disease exacerbations is crucial for delaying lung function decline in CF.

Tumor Necrosis Factor-α in Airway Secretions from Cystic Fibrosis Patients Upregulate Endothelial Adhesion Molecules and Induce Airway Epithelial Cell Apoptosis: Implications for Cystic Fibrosis Lung Disease

Airway inflammation plays a crucial role in lung damage in cystic fibrosis (CF) and is characterized by a persistent influx of neutrophils into the airways. We hypothesized that the high levels of inflammatory products that accumulate in the microenvironment of the CF lung contribute to induce the persistent neutrophil recruitment and the airway epithelial damage. Thus, we evaluated the in vitro effect of sputum sol phase (SSP) from CF patients on a) adhesion molecule expression by human microvascular endothelial cells (HMECs) and b) apoptosis of human bronchial epithelial cells (HBECs), both wild-type and CFTR-defective. SSP was obtained from 7 clinically stable adult CF patients and 8 patients with an acute exacerbation. HMECs and HBECs were cultured in the absence or presence of SSP. Cell adhesion molecule expression was assessed by flow cytometry and cell death by the detection of histone-associated DNA fragments, caspase activation, and cytochrome c release. SSP obtained from CF patients, especially at the time of an acute exacerbation, induced a) an upregulation of endothelial adhesion molecules on cultured HMECs that was associated with an increase of neutrophil adhesion to these cells, and was mediated at least in part by TNF-α and IL-1 and b) apoptosis of airway epithelial cells, mainly activated by TNF-α pathway. These results suggest that the high concentrations of inflammatory mediators in CF airways contribute both to the chronic neutrophil influx and the airway damage, and support the crucial role of early anti-inflammatory treatment in the disease.

Effect of zinc supplementation on respiratory tract infections in children with cystic fibrosis

Zinc (Zn) has significant anti-oxidant and anti-inflammatory activity. Zn deficiency can occur in subsets of patients with cystic fibrosis (CF) especially those with malabsorption and impaired growth. Although supplemental Zn has significantly reduced infections in various disorders, its efficacy has not been thoroughly investigated in CF. We performed a double blind placebo controlled pilot study to investigate the effect of daily 30 mg elemental Zn for 1 year on the rate of respiratory tract infections (RTIs), use of antibiotics and plasma cytokines in 26 children with CF (ages 7-18 years). Plasma Zn, Cu, inflammatory cytokines and ex vivo generation of IL-2 were measured at baseline and at the end of the study. The number of days of oral antibiotics was lower in Zn treated patients compared to placebo (P = 0.05). However, compared to placebo, the effect of Zn was greater in patients who exhibited low plasma Zn at baseline (P = 0.02) than those who had plasma Zn levels identical to normal subjects (P = 0.55). Zn supplementation was marginally effective in reducing percentage increase in plasma IL-6 and IL-8 while increasing the percentage change in ex vivo generation of IL-2 in isolated mononuclear cell. In conclusion, oral intake of 30 mg/day of Zn reduced the number of days of oral antibiotics used to treat RTIs in children with CF. A higher daily Zn dose may be needed to decrease RTIs and modify immune responses.

ICAM-1 expression on conjunctival epithelial cells in patients with cystic fibrosis

BACKGROUND

Cystic fibrosis is one of the most common lethal genetic conditions. The defect is due to mutations in a gene on chromosome 7, named the cystic fibrosis transmembrane regulator (CFTR), which functions as a chloride channel in epithelial membranes It is presumed that the disease affects all secretory epithelia including the eye. The objective of this study is to investigate the expression of intercellular adhesion molecule-1 (ICAM-1) by conjunctival epithelial cells of patients with cystic fibrosis and the correlation between of the expression of ICAM-1 and the grade of cystic fibrosis severity.

METHODS

Impression cytology specimens were collected in 24 patients with cystic fibrosis. Cells were processed for flow cytometry, by using monoclonal antibodies to ICAM-1.

RESULTS

A significant increase of ICAM-1 expression on epithelial cells was found in patients with cystic fibrosis when compared with normal eyes. A positive correlation between the ICAM-1 expression and severe clinical status of CF patients was also observed.

CONCLUSIONS

Our findings suggest that the inflammation appears to have a role in the pathogenesis of the ocular surface changes in patients with cystic fibrosis. ICAM-1 expression on conjunctival epithelial cells may be a marker of the inflammatory status in cystic fibrosis patients. The method described here reveal good repeatability and reliability for the analysis of the inflammatory markers on conjunctival epithelial cells and can be a useful tool in evaluating of the ocular findings and treatment interventions in patients with cystic fibrosis.

Viral inhibition of IL-1- and neutrophil elastase-induced inflammatory responses in bronchial epithelial cells

Previously, we elucidated the intracellular mechanisms by which neutrophil elastase (NE) up-regulates inflammatory gene expression in bronchial epithelial cells. In this study, we examine the effects of both IL-1 and NE on inflammatory gene expression in 16HBE14o- bronchial epithelial cells and investigate approaches to abrogate these inflammatory responses. IL-1 induced IL-8 protein production in time- and dose-dependent fashions, an important observation given that IL-8 is a potent neutrophil chemoattractant and a key inflammatory mediator. IL-1 and NE were shown to activate the p38 MAPK pathway in 16HBE14o- cells. Western blot analysis demonstrated IL-1R-associated kinase 1 (IRAK-1) degradation in response to stimulation with both IL-1 and NE. In addition, the expression of dominant negative IRAK-1 (IRAK-1delta), IRAK-2delta, or IRAK-4delta inhibited IL-1- and NE-induced NF-kappaB-linked reporter gene expression. Dominant negative versions of the intracellular adaptor proteins MyD88 (MyD88delta) and MyD88 adaptor-like (Mal P/H) abrogated NE-induced NF-kappaB reporter gene expression. In contrast, only MyD88delta was found to inhibit IL-1-induced NF-kappaB reporter activity. We also investigated the vaccinia virus proteins, A46R and A52R, which have been shown to antagonize IL-1 signaling. Transfection with A46R or A52R cDNA inhibited IL-1- and NE-induced NF-kappaB and IL-8R gene expression and IL-8 protein production in primary and transformed bronchial epithelial cells. Furthermore, cytokine array studies demonstrated that IL-1 and NE can up-regulate the expression of IL-6, oncostatin M, epithelial cell-derived neutrophil activating peptide-78, growth-related oncogene family members, vascular endothelial growth factor, and GM-CSF, with induction of these proteins inhibited by the viral proteins. These findings identify vaccinia virus proteins as possible therapeutic agents for the manifestations of several inflammatory lung diseases.

Pyocyanin and its precursor phenazine-1-carboxylic acid increase IL-8 and intercellular adhesion molecule-1 expression in human airway epithelial cells by oxidant-dependent mechanisms

Pseudomonas aeruginosa secretes numerous factors that alter host cell function and may contribute to disease pathogenesis. Among recognized virulence factors is the redox-active phenazine pyocyanin. We have recently demonstrated that the precursor for pyocyanin, phenazine-1-carboxylic acid (PCA), increases oxidant formation and alters gene expression in human airway epithelial cells. We report in this work that PCA and pyocyanin increase expression of ICAM-1 both in vivo and in vitro. Moreover, phenazines enhanced cytokine-dependent increases in IL-8 and ICAM-1. Antioxidant intervention studies indicated both similarities and differences between PCA and pyocyanin. The thiol antioxidant N-acetyl cysteine, extracellular catalase, and inducible NO synthase inhibitors inhibited ICAM-1 and IL-8 increases in response to both phenazines. However, pyocyanin was significantly more sensitive to N-acetylcysteine inhibition. Interestingly, hydroxyl radical scavengers inhibited the response to pyocyanin, but not to PCA. These studies suggest that P. aeruginosa phenazines coordinately up-regulate chemokines (IL-8) and adhesion molecules (ICAM-1) by mechanisms that are, at least in part, oxidant dependent. However, results indicate that the mechanisms by which PCA and pyocyanin exert their effects are not identical, and not all antioxidant interventions are equally effective in inhibiting phenazine-mediated proinflammatory effects.

Adherence of airway neutrophils and inflammatory response are increased in CF airway epithelial cell-neutrophil interactions

Persistent presence of PMN in airways is the hallmark of CF. Our aim was to assess PMN adherence, percentage of apoptotic airway PMN (aPMN), and IL-6 and IL-8 production when aPMN are in contact with airway epithelial cells. Before coculture, freshly isolated CF aPMN have greater spontaneous and TNF-alpha-induced apoptosis compared with blood PMN from the same CF patients and from aPMN of non-CF patients. We then examined cocultures of PMN isolated from CF and non-CF airways with bronchial epithelial cells bearing mutated cftr compared with cftr-corrected bronchial epithelial cells. After 18-h coculture, the number of CF aPMN adhered on cftr-deficient bronchial epithelial cells was 2.3-fold higher compared with the coculture of non-CF aPMN adhered on cftr-corrected bronchial epithelial cells. The percentage of CF apoptotic aPMN (9.5 +/- 0.2%) adhered on cftr-deficient bronchial epithelial cells was similar to the percentage of non-CF apoptotic aPMN adhered on cftr-corrected bronchial epithelial cells (10.3 +/- 0.7%). IL-6 and IL-8 levels were enhanced 6.5- and 2.9-fold, respectively, in coculture of CF aPMN adhered on cftr-deficient bronchial epithelial cells compared with coculture of non-CF aPMN adhered on cftr-corrected bronchial epithelial cells. Moreover, blocking surface adhesion molecules ICAM-1, VCAM-1, and E-selectin on cftr-deficient bronchial epithelial cells with specific MAbs inhibited the adherence of CF aPMN by 64, 51, and 50%, respectively. Our data suggest that in CF patients a high number of nonapoptotic PMN adhered on airway epithelium associated with elevated IL-6 and IL-8 levels may contribute to sustained and exaggerated inflammatory response in CF airways.

Circulating adhesion molecules in allergic and non-allergic asthma

Circulating forms of adhesion molecules (intercellular-adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin ) are related to the turnover of these molecules on the cell surface. In contrast to the other molecules, the levels of E-selectin probably exclusively reflect the activity of endothelial cells. The aim of this study was to compare levels of circulating adhesion molecules in patients with allergic (AA) and non-allergic asthma (NA) and to relate the levels of soluble adhesion molecules to methacholine responsiveness and lung function. The study comprised 19 patients with AA, 15 patients with NA and 17 healthy subjects. Soluble adhesion molecules, spirometry, methacholine responsiveness and peak flow variability was measured. The group of patients with AA had higher levels of sE-selectin than the reference group (P=0.046). Serum levels of sE-selectin correlated significantly with bronchial responsiveness (r=0.76) and peak flow variability (r=0.75) (P<0.01) in the NA but not in the AA group. All adhesion molecules in AA (P<0.05-<0.001), but only sE-selectin in NA (P<0.05), were correlated to airway conductance. sVCAM-1 was reduced by inhaled steroids (P<0.01). Our results indicate that endothelial cells are activated in asthma and that this activity has a bearing on airflow variability and bronchial responsiveness in NA.

Elevated levels of circulating adhesion molecules in patients with active pulmonary tuberculosis

OBJECTIVE

Recent studies have indicated the importance of cell adhesion molecules in the pathogenesis of various inflammatory lung diseases. Our study was designed to determine whether five soluble adhesion molecules including soluble L-, E- and P-selectin (sL-, sE- and sP-selectin), intercellular adhesion molecule-1 (sICAM-1), and vascular cell adhesion molecule-1 (sVCAM-1) in serum reflect the severity of active pulmonary tuberculosis (TB), and whether there is a distinct profile of these soluble molecules in this disease.

METHODOLOGY

Using enzyme-linked immunosorbent assays, we measured the serum levels of these five soluble adhesion molecules in 31 patients with active TB and 11 healthy volunteers.

RESULTS

Serum levels of sE-selectin, sP-selectin and sICAM-1, but not sL-selectin or sVCAM-1, were significantly higher in patients with active TB than in the control subjects (P < 0.001, each). Significant correlations were detected only between serum levels of sE-selectin and sP-selectin, sE-selectin and sICAM-1, and sP-selectin and sICAM-1. There was a significant correlation between the Gaffky scale result (a scale assessing the number of mycobacteria bacilli present) and all of the above adhesion molecules, except for sL-selectin. Serum levels of sE-selectin, sL-selectin and sICAM-1 also correlated with the CXR radiological score. Higher levels of sL-selectin and sICAM-1 were detected in the serum of patients with radiological cavity formation compared to those without. The ESR, C-reactive protein and circulating neutrophil counts all correlated significantly with sE-selectin, sP-selectin, sICAM-1 and sVCAM-1.

CONCLUSION

The results suggest that there is a distinct profile of soluble adhesion molecules in active pulmonary TB and that sE-selectin, sP-selectin, and especially sICAM-1 appear to be the most sensitive clinical measures of disease severity.

Expression of S100A12 (EN-RAGE) in cystic fibrosis

BACKGROUND

Chronic airway inflammation and recurrent infections are a core phenomenon in cystic fibrosis (CF). Diagnosing acute infectious exacerbations is difficult in the presence of chronic inflammatory processes. S100A12 exhibits proinflammatory functions via interaction with the multiligand receptor for advanced glycation end products. Blocking this interaction inhibits inflammatory processes in mice.

METHODS

The expression of S100A12 in lung specimens of patients with end stage lung disease of CF was investigated, and S100A12 levels in the serum of patients with acute infectious exacerbations of CF were measured.

RESULTS

Immunohistochemical studies of CF lung biopsy specimens revealed a significant expression of S100A12 by infiltrating neutrophils. High S100A12 levels were found in the sputum of patients with CF, and serum levels of S100A12 during acute infectious exacerbations were significantly increased compared with healthy controls (median 225 ng/ml v 46 ng/ml). After treatment with intravenous antibiotics the mean S100A12 level decreased significantly. There was also a significant difference between S100A12 levels in patients with acute infectious exacerbations and 18 outpatients without exacerbations (median 225 ng/ml v 105 ng/ml).

CONCLUSIONS

S100A12 is extensively expressed at local sites of inflammation in CF. It is a serum marker for acute infectious exacerbations. High local expression of S100A12 suggests that this protein has a proinflammatory role during airway inflammation and may serve as a novel target for anti-inflammatory treatments.

The influence of tobacco smoking on adhesion molecule profiles

Sequential interactions between several adhesion molecules and their ligands regulate lymphocyte circulation and leukocyte recruitment to inflammatory foci. Adhesion molecules are, therefore, central and critical components of the immune and inflammatory system. We review the evidence that tobacco smoking dysregulates specific components of the adhesion cascade, which may be a common factor in several smoking-induced diseases. Smoking causes inappropriate leukocyte activation, leukocyte-endothelial adhesion, and neutrophil entrapment in the microvasculature, which may help initiate local tissue destruction. Appropriate inflammatory reactions may thus be compromised. In addition to smoke-induced alterations to membrane bound endothelial and leukocyte adhesion molecule expression, which may help explain the above phenomena, smoking has a profound influence on circulating adhesion molecule profiles, most notably sICAM-1 and specific sCD44 variants. Elevated concentrations of soluble adhesion molecules may simply reflect ongoing inflammatory processes. However, increasing evidence suggests that specific soluble adhesion molecules are immunomodulatory, and that alterations to soluble adhesion molecule profiles may represent a significant risk factor for several diverse diseases. This evidence is discussed herein.

Soluble adhesion molecules, cytokines and cellular markers in serum in patients with acute infections

The aim of this study was to evaluate the diagnostic capacity of a number of blood components such as soluble adhesion molecules, interleukin-6 (IL-6), myeloperoxidase (MPO) and lysozyme in the distinction of acute bacterial and viral infections. Blood was taken from 115 acutely infected patients at admission before any treatment and in some cases on several consecutive days. 35 of the patients had a definite viral cause for their infection and 66 a bacterial cause. All variables were raised in patients with acute bacterial infections. Soluble vascular cell adhesion molecule-1 (sVCAM-1), sE-selectin, lysozyme and MPO were also raised in acute viral infections, but for sE-selectin and MPO less so than in bacterial infections. Evaluation of the diagnostic power showed that for MPO and IL-6 at cut-offs of 1300 microg/l and 100 ng/l, respectively, the positive predictive value was 97% and 100% and the negative predictive value 78% and 76%, respectively, in the classification of acute bacterial infections. In the distinction between viral or bacterial causes of acute infections in otherwise healthy subjects serum measurements of MPO and IL-6 are valuable tools and should be considered as diagnostic aids in the routine setting. The soluble adhesion molecules did not offer any further information in this respect.

Quantitative analysis of inflammatory cells infiltrating the cystic fibrosis airway mucosa

Airway inflammation represents a hallmark of the cystic fibrosis (CF) disease. However, the mucosal distribution of immune cells along the CF airways has not been clearly defined, particularly in intermediate bronchi and distal bronchioles. We analysed lung tissues collected at the time of transplantation from homozygous DeltaF508+/+CF patients versus non-CF donors. Using immunohistochemistry, the distribution of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin, polymorphonuclear neutrophils (PMN), mast cells, CD3+ T cells, including the CD4+ and CD8+ subsets, CD20+ B cells, CD38+ plasma cells and CD68+ macrophages, was analysed at lobar, segmental and distal levels of the bronchial tree. Using image cytometry, the number of cells per mm2 was assessed in the depth of the bronchial wall. In CF airways, alterations mainly consisted in lesions of the surface epithelium. Numerous immune cells were heterogeneously distributed all along the bronchial tree and mainly located in the mucosa, beneath the surface epithelium. Compared to non-CF donors, the lymphoid aggregates formed by B cells were significantly larger all along the CF airways (P = 0.001). The number of T lymphocytes was higher at the CF distal level (P = 0.035), where we observed an intense tissue damage. PMN preferentially accumulated (P = 0.033) in the CF surface epithelium, which overexpressed ICAM-1 but not VCAM-1 and E-selectin. These results highlight the nature of the inflammatory infiltrate in the CF airway mucosa and emphasize a prominent implication of PMN, B and T lymphocytes in the CF disease.

The effect of chronic azithromycin therapy on soluble endothelium-derived adhesion molecules in patients with coronary artery disease

In patients with coronary artery disease (CAD), azithromycin therapy is associated with decreased cytokine levels and overall reduction of inflammation. Chlamydia pneumoniae (C.Pn) is a common pathogen that may be an important factor in the development and progression of atherosclerosis. Cell-adhesion molecules have an important role in recruitment of inflammatory cells during plaque development and are expressed by endothelial cells on activation. We sought to define the effect of treatment with azithromycin on circulating levels of soluble vascular cell-adhesion molecule (VCAM-I), intercellular adhesion molecule (ICAM-1), and E-selectin in patients with CAD. Plasma concentrations of VCAM-1, ICAM-1, and E-selectin were measured in 40 patients with documented CAD and a positive (> or = 1:16) immunoglobulin G (IgG) titer against C.Pn, 20 subjects with normal coronary arteries, and 14 healthy volunteers. Patients were assigned randomly to receive either 500 mg/wk of azithromycin or placebo for 3 months. Serum samples were obtained at baseline, at 3 months, and during the follow-up visit at 6 months. Patients with documented CAD exhibited elevation of VCAM-1 (535 +/- 227 ng/ ml; p = 0.0001) and E-selectin (69 +/- 29 ng/ml; p = 0.006), but not ICAM-1 (321 +/- 65 ng/ml) concentrations as compared with the patients with angiographically proven normal coronary arteries (252 +/- 80; 50 +/- 22; and 311 +/- 40 ng/ml) and healthy controls (110 +/- 18; 29 +/- 2; and 238 +/- 47 ng/ml, respectively). Prolonged treatment with azithromycin did not significantly affect the plasma levels of soluble VCAM-1, ICAM-1, and E-selectin. Soluble markers of endothelial activation are markedly increased in patients with documented CAD as compared with those with normal coronary arteries and healthy controls. Despite substantial heterogeneity in plasma E-selectin, ICAM-1, and VCAM-1 levels, long-term azithromycin treatment did not affect plasma levels of these adhesion molecules, indicative of endothelial activation, over a period of 6 months.

Potential mechanisms of susceptibility to periodontitis in tobacco smokers

Tobacco smoking is probably the most important, controllable environmental risk factor in periodontitis. It results in changes in the vascular, inflammatory, immune and healing responses. The degree of exposure to tobacco smoking can be measured in pack years or by measuring serum cotinine and nicotine levels. In a previous paper we reported elevated levels of serum soluble intercellular adhesion molecule-1 (sICAM-1) in smokers, regardless of periodontal status. Elevated sICAM-1 has been found to be a risk marker for cardiovascular disease. In the present paper we report the short-term effects of an episode of smoking on blood flow and levels of sICAM-1. Human volunteers included non-smokers, light smokers and heavy smokers. Relative blood flow was monitored in the gingivae and forehead skin using a laser Doppler flowmeter and serum levels of sICAM-1, cotinine and nicotine measured before during and up to 60 min following an episode of smoking. We could not provide evidence to support the theory that there is localized vasoconstriction within the gingival tissues. In contrast, there was a significant increase in blood flow in the forehead skin of light smokers which was not observed in non-smoking controls or in heavy smokers, suggesting a long-term tolerance in this latter group. The level of sICAM-1 remained unchanged during this episode, further suggesting a long-term effect. In a parallel group of subjects, we were able to demonstrate a direct significant correlation between sICAM and serum cotinine levels. These observations may be relevant to aetiological mechanisms in periodontitis and other smoking-associated diseases.

Release of soluble ICAM-1 from human lung fibroblasts, aortic smooth muscle cells, dermal microvascular endothelial cells, bronchial epithelial cells, and keratinocytes

We determined effects of IL-1alpha, TNFalpha and IFNgamma on sICAM-1 release in culture media from human aortic smooth muscle cells (AOSMC), dermal microvascular endothelial cells (DMEC), keratinocytes (KC), bronchial epithelial cells (BEC) and lung fibroblasts (LF) as determined by ELISA. Under basal conditions of cultures for 20 h, low concentrations of sICAM-1 were only detected in the culture media of two (DMEC and BEC) of these cell types. IL-1alpha, TNFalpha and IFNgamma stimulated sICAM-1 from these cells. IFNgamma stimulated more shedding from AOSMC, BEC and KC than IL-1alpha or TNFalpha. TNFalpha enhanced more sICAM-1 release from DEMC than from AOSMC, BEC and LF. IL-1alpha and IFNgamma or TNFalpha and IFNgamma acted synergistically to enhance shedding of sICAM-1 from these cells. The levels sICAM-1 in pathophysiological conditions may influence leukocyte-vascular cell interactions to block leukocyte transmigration to tissue injury sites as a negative feedback mechanism.

Pierre Y. Proteolytic Cleavage of ICAM-1 by Human Neutrophil Elastase

Human leukocyte elastase (HLE) participates in tissue destruction in a number of inflammatory disorders, including rheumatoid arthritis and cystic fibrosis. Since HLE has been shown to bind to Mac-1, and ICAM-1 plays a key role during the recruitment and the activation of leukocytes at inflamed sites, we investigated the capacity of HLE to cleave ICAM-1. Flow-cytometric analyses showed a dose-dependent cleavage of ICAM-1 by HLE on different human cell lines. The cleavage was completely inhibited by α1-antitrypsin, a natural HLE protease inhibitor. The ability of HLE to degrade ICAM-1 was further confirmed by electrophoretic analysis using a soluble form of ICAM-1 (D1-D5). Enzymatic removal of N-linked glycosylation did not significantly modulate ICAM-1 cleavage by HLE, while removal of sialic acid residues partially reduced the sensitivity of ICAM-1 to HLE. We further showed that sputum of cystic fibrosis patients contains high levels of HLE activity capable of cleavage of cell surface ICAM-1. The cleavage induced by incubation of cells with the sputum sample was totally inhibited by α1-antitrypsin and the specific peptidic HLE inhibitor N-methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone. Moreover, the cleavage of ICAM-1 was concomitant to that of CD4 at the surface of the same cell, at the same amplitude, and at all HLE concentrations. The capacity of HLE to modulate the expression of ICAM-1 on the surface of leukocytes by proteolytic cleavage brings support to the hypothesis that overproduction of HLE can cause severe immunologic lung disorders by affecting intercellular adhesion.