Systemic IL-26 correlates with improved asthma control in children sensitized to dog allergen.

BACKGROUND: Interleukin (IL)-26 is produced by T helper type 17 (Type 17) cells and exerts immunomodulatory plus antimicrobial effects. Previous studies show that local IL-26 concentrations in the airways are higher in patients with uncontrolled than in those with controlled asthma, and that this intriguing cytokine bears biomarker potential. Here, we determined how systemic IL-26 relates to allergen sensitization, asthma severity, and to IL-17 A in children. METHODS: Serum samples were obtained from children with (n = 60) and without (n = 17) sensitization to dog allergen, and IL-26 and IL-17 A protein concentrations were measured using ELISA. Self-reported history, including medication use and validated symptom-based questionnaire scores, was recorded. RESULTS: The serum concentrations of IL-26 were enhanced in allergen-sensitized subjects and correlated with those of IL-17 A in a positive manner. However, the IL-26 concentrations did not markedly differ between allergen-sensitized subjects with and without asthma, eczema, allergic rhinitis, or a history of food allergy. Notably, IL-26 concentrations correlated with increasing Asthma Control Test (ACT) scores in a positive manner and with inhaled corticosteroid in a negative manner, amongst sensitized subjects with asthma. Moreover, subjects with asthma requiring ≥ 1 course of oral corticosteroids in the preceding 12 months had decreased IL-26 concentrations. CONCLUSION: This study forwards evidence that systemic IL-26, just like IL-17 A, is involved in allergen sensitization among children. The association of systemic IL-26 with improved asthma control is compatible with the cellular sources being recruited into the airways in severe asthma, which supports that this kinocidin bears potential as a biomarker and therapeutic target.

Protein N-glycosylation in the bronchoalveolar space differs between never-smokers and long-term smokers with and without COPD.

Chronic obstructive pulmonary disease (COPD) kills millions of people annually and patients suffering from exacerbations of this disorder display high morbidity and mortality. The clinical course of COPD is associated with dysbiosis and infections, but the underlying mechanisms are poorly understood. Glycosylation of proteins play roles in regulating interactions between microbes and immune cells, and knowledge on airway glycans therefore contribute to the understanding of infections. Furthermore, glycans have biomarker potential for identifying smokers with enhanced risk for developing COPD as well as COPD subgroups. Here, we characterized the N-glycosylation in the lower airways of healthy never-smokers (HNS, n = 5) and long-term smokers (LTS) with (LTS+, n = 4) and without COPD (LTS-, n = 8). Using mass spectrometry, we identified 57 highly confident N-glycan structures whereof 38 oligomannose, complex, and paucimannose type glycans were common to BAL samples from HNS, LTS- and LTS+ groups. Hybrid type N-glycans were identified only in the LTS+ group. Qualitatively and quantitatively, HNS had lower inter-individual variation between samples compared to LTS- or LTS+. Cluster analysis of BAL N-glycosylation distinguished LTS from HNS. Correlation analysis with clinical parameters revealed that complex N-glycans were associated with health and absence of smoking whereas oligomannose N-glycans were associated with smoking and disease. The N-glycan profile from monocyte-derived macrophages differed from the BAL N-glycan profiles. In conclusion, long-term smokers display substantial alterations of N-glycosylation in the bronchoalveolar space, and the hybrid N-glycans identified only in long-term smokers with COPD deserve to be further studied as potential biomarkers.

TLR4-mediated release of heparin-binding protein in human airways: a co-stimulatory role for IL-26.

Background: Bacterial infection causes accumulation of neutrophils that release antimicrobial proteins including heparin-binding protein (HBP). In human airways, this neutrophil accumulation can be re-capitulated via intrabronchial exposure to lipopolysaccharide (LPS), a Toll-like receptor 4 (TLR4) agonist, that also causes a local increase in the neutrophil-mobilizing cytokine IL-26. Although LPS is considered a weak stimulus for HBP release ex vivo, its effect on HBP release in human airways in vivo has not been characterized. Methods: We determined whether intrabronchial exposure to LPS causes concomitant release of HBP and IL-26 in human airways, and whether IL-26 can enhance LPS-induced release of HBP in isolated human neutrophils. Results: We found that the concentration of HBP was markedly increased in bronchoalveolar lavage (BAL) fluid 12, 24, and 48 hours after LPS exposure, and that it displayed a strong and positive correlation with that of IL-26. Moreover, the concentration of HBP in conditioned media from isolated neutrophils was enhanced only after co-stimulation with LPS and IL-26. Conclusions: Taken together, our findings indicate that TLR4 stimulation causes concomitant release of HBP and IL-26 in human airways, and that IL-26 may constitute a required co-stimulant for HBP release in neutrophils, thus enabling the concerted action of HBP and IL-26 in local host defense.

Glucose Homeostasis in Relation to Neutrophil Mobilization in Smokers with COPD.

Purpose: Type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) are common comorbidities in chronic obstructive pulmonary disease (COPD), but the underlying pathogenic mechanisms are poorly understood. Given that these morbidities all display increased neutrophil mobilization, the current study aimed to address whether glucose homeostasis relates to signs of neutrophil mobilization in COPD. Methods: The study population included healthy non-smokers (HNS) and long-term smokers without (LTS) and with COPD (LTS+COPD). No subject had T2DM or MetS. Serum cotinine was quantified to evaluate current smoking. Capillary blood glucose was measured after overnight fasting and during an oral glucose tolerance test (OGTT). Neutrophils were quantified in blood and bronchoalveolar lavage samples (BAL). The neutrophil-related cytokines IL-36α, -ß and -γ were quantified (ELISA) along with IL-6, IL-8, INF-γ and CXCL10 (U-Plex®) in plasma and cell-free BAL fluid (BALF). In addition, we quantified neutrophil elastase (ELISA) and net proteinase activity (substrate assay) in BALF. Results: The LTS+COPD group had lower fasting glucose, greater change in glucose during OGTT and higher neutrophil concentrations in BAL and blood compared with HNS. Fasting glucose correlated in a positive manner with blood neutrophil concentration, forced expiratory volume in 1 second/forced vital capacity ratio (FEV1/FVC) and FEV1 (% of predicted) in LTS+COPD. In this group, the concentration of IL-36α in BALF correlated in a negative manner with fasting glucose, blood neutrophil concentration and FEV1, while the CXCL10 concentration in BALF correlated in a negative manner with glucose at the end of OGTT (120 min). We observed no corresponding correlations for neutrophil elastase, net proteinase or gelatinase activity. Conclusion: In smokers with COPD, altered glucose homeostasis is associated with local and systemic signs of increased neutrophil mobilization, but not with local proteinases. This suggests that other specific aspects of neutrophil mobilization constitute pathogenic factors that affect glucose homeostasis in COPD.

Involvement of IL-26 in bronchiolitis obliterans syndrome but not in acute rejection after lung transplantation.

BACKGROUND:  The main long-term complication after lung transplantation is bronchiolitis obliterans syndrome (BOS), a deadly condition in which neutrophils may play a critical pathophysiological role. Recent studies show that the cytokine interleukin IL-26 can facilitate neutrophil recruitment in response to pro-inflammatory stimuli in the airways. In this pilot study, we characterized the local involvement of IL-26 during BOS and acute rejection (AR) in human patients. METHOD:  From a biobank containing bronchoalveolar lavage (BAL) samples from 148 lung transplant recipients (LTR), clinically-matched patient pairs were identified to minimize the influence of clinical confounders. We identified ten pairs (BOS/non-BOS) with BAL samples harvested on three occasions for our longitudinal investigation and 12 pairs of patients with and without AR. The pairs were matched for age, gender, preoperative diagnosis, type of and time after surgery. Extracellular IL-26 protein was quantified in cell-free BAL samples using an enzyme-linked immunosorbent assay. Intracellular IL-26 protein in BAL cells was determined using immunocytochemistry (ICC) and flow cytometry. RESULTS:  The median extracellular concentration of IL-26 protein was markedly increased in BAL samples from patients with BOS (p < 0.0001) but not in samples from patients with AR. Intracellular IL-26 protein was confirmed in alveolar macrophages and lymphocytes (through ICC and flow cytometry) among BAL cells obtained from BOS patients. CONCLUSIONS:  Local IL-26 seems to be involved in BOS but not AR, and macrophages as well as lymphocytes constitute cellular sources in this clinical setting. The enhancement of extracellular IL-26 protein in LTRs with BOS warrants further investigation of its potential as a target for diagnosing, monitoring, and treating BOS.

Increased cytotoxic T-cells in the airways of adults with former bronchopulmonary dysplasia.

RATIONALE: Bronchopulmonary dysplasia (BPD) in preterm-born infants is a risk factor for chronic airway obstruction in adulthood. Cytotoxic T-cells are implicated in COPD, but their involvement in BPD is not known. OBJECTIVES: To characterise the distribution of airway T-cell subsets in adults with a history of BPD. METHODS: Young adults with former BPD (n=22; median age 19.6 years), age-matched adults born preterm (n=22), patients with allergic asthma born at term (n=22) and healthy control subjects born at term (n=24) underwent bronchoalveolar lavage (BAL). T-cell subsets in BAL were analysed using flow cytometry. RESULTS: The total number of cells and the differential cell counts in BAL were similar among the study groups. The percentage of CD3+CD8+ T-cells was higher (p=0.005) and the proportion of CD3+CD4+ T-cells was reduced (p=0.01) in the BPD group, resulting in a lower CD4/CD8 ratio (p=0.007) compared to the healthy controls (median 2.2 versus 5.3). In BPD and preterm-born study subjects, both CD3+CD4+ T-cells (rs=0.38, p=0.03) and CD4/CD8 ratio (rs=0.44, p=0.01) correlated positively with forced expiratory volume in 1 s (FEV1). Furthermore, CD3+CD8+ T-cells were negatively correlated with both FEV1 and FEV1/forced vital capacity (rs= -0.44, p=0.09 and rs= -0.41, p=0.01, respectively). CONCLUSIONS: Young adults with former BPD have a T-cell subset pattern in the airways resembling features of COPD. Our findings are compatible with the hypothesis that CD3+CD8+ T-cells are involved in mechanisms behind chronic airway obstruction in these patients.

Mucin Binding to Moraxella catarrhalis during Airway Inflammation Is Dependent on Sialic Acid.

Chronic obstructive pulmonary disease (COPD) is associated with colonization by bacterial pathogens and repeated airway infections, leading to exacerbations and impaired lung function. The highly glycosylated mucins in the mucus lining the airways are an important part of the host defense against pathogens. However, mucus accumulation can contribute to COPD pathology. Here, we examined whether inflammation is associated with glycosylation changes that affect interactions between airway mucins and pathogens. We isolated mucins from lower airway samples (n = 4-9) from long-term smokers with and without COPD and from never-smokers. The most abundant terminal glycan moiety was N-acetylneuraminic acid (Neu5Ac) among smokers with and without COPD and N-acetyl-hexoseamine among never-smokers. Moraxella catarrhalis bound to MUC5 mucins from smokers with and without COPD. M. catarrhalis binding correlated with inflammatory parameters and Neu5Ac content. M. catarrhalis binding was abolished by enzymatic removal of Neu5Ac. Furthermore, M. catarrhalis bound to α2,6 sialyl-lactose, suggesting that α2,6 sialic acid contributes to M. catarrhalis binding to mucins. Furthermore, we detected more M. catarrhalis binding to mucins from patients with pneumonia than to those from control subjects (n = 8-13), and this binding correlated with C-reactive protein and Neu5Ac levels. These results suggest a key role of inflammation-induced Neu5Ac in the adhesion of M. catarrhalis to airway mucins. The inflammation-induced ability of MUC5 mucins to bind M. catarrhalis is likely a host defense mechanism in the healthy lung, although it cannot be excluded that impaired mucociliary clearance limits the effectiveness of this defense in patients with COPD.

IL-36 Cytokines Promote Inflammation in the Lungs of Long-Term Smokers.

Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory lung disease with high morbidity and mortality. The IL-36 family are proinflammatory cytokines that are known to shape innate immune responses, including those critical to bacterial pneumonia. The objective of this study was to determine whether IL-36 cytokines promote a proinflammatory milieu in the lungs of long-term smokers with and without COPD. Concentrations of IL-36 cytokines were measured in plasma and BAL fluid from subjects in a pilot study (n = 23) of long-term smokers with and without COPD in vivo and from a variety of lung cells (from 3-5 donors) stimulated with bacteria or cigarette smoke components in vitro. Pulmonary macrophages were stimulated with IL-36 cytokines in vitro, and chemokine and cytokine production was assessed. IL-36α and IL-36γ are produced to varying degrees in murine and human lung cells in response to bacterial stimuli and cigarette smoke components in vitro. Moreover, whereas IL-36γ production is upregulated early after cigarette smoke stimulation and wanes over time, IL-36α production requires a longer duration of exposure. IL-36α and IL-36γ are enhanced systemically and locally in long-term smokers with and without COPD, and local IL-36α concentrations display a positive correlation with declining ventilatory lung function and increasing proinflammatory cytokine concentrations. In vitro, IL-36α and IL-36γ induce proinflammatory chemokines and cytokines in a concentration-dependent fashion that requires IL-36R and MyD88. IL-36 cytokine production is altered in long-term smokers with and without COPD and contributes to shaping a proinflammatory milieu in the lungs.

Increased CD11b and Decreased CD62L in Blood and Airway Neutrophils from Long-Term Smokers with and without COPD.

There is incomplete mechanistic understanding of the mobilization of neutrophils in the systemic and local compartment in smokers with chronic obstructive pulmonary disease (COPD). In this pilot study, we characterized how the adhesion molecules CD11b and CD62L, surface markers indicative of priming, are altered as neutrophils extravasate, and whether surface density of CD11b and CD62L differs between long-term tobacco smokers (LTS) with and without COPD compared with healthy never-smokers (HNS). Unstimulated blood neutrophils from LTS with (n = 5) and without (n = 9) COPD displayed lower surface density of CD62L compared with HNS (n = 8). In addition, surface density of CD11b was higher in bronchoalveolar lavage (BAL) neutrophils from LTS without COPD compared with those with COPD and HNS. Moreover, in BAL neutrophils from all study groups, CD62L was lower compared with matched blood neutrophils. In addition, BAL neutrophils responded with a further decrease in CD62L to ex vivo TNF stimulation. Thus, neutrophils in the airway lumen display a higher state of priming than systemic neutrophils and bear the potential to be further primed by local cytokines even with no smoking or the presence of COPD, findings that may represent a universal host defense mechanism against local bacteria. Moreover, systemic neutrophils are primed in LTS regardless of COPD. Further studies in larger materials are warranted to determine whether the priming of neutrophils is protective against COPD or merely preceding it.