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Background The heterodimer interleukin (IL)-17A/F is elevated in the lungs in chronic respiratory disease such as severe asthma, along with the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). Although IL-17A/F and TNF-α are known to functionally cooperate to exacerbate airway inflammation, proteins altered by their interaction in the lungs are not fully elucidated. Results We used Slow Off-rate Modified Aptamer-based proteomic array to identify proteins that are uniquely and/or synergistically enhanced by concurrent stimulation with IL-17A/F and TNF-α in human bronchial epithelial cells (HBEC). The abundance of 38 proteins was significantly enhanced by the combination of IL-17A/F and TNF-α, compared to either cytokine alone. Four out of seven proteins that were increased > 2-fold were those that promote neutrophil migration; host defence peptides (HDP; Lipocalin-2 (LCN-2) and Elafin) and chemokines (IL-8, GROα). We independently confirmed the synergistic increase of these four proteins by western blots and ELISA. We also functionally confirmed that factors secreted by HBEC stimulated with the combination of IL-17A/F and TNF-α uniquely enhances neutrophil migration. We further showed that PI3K and PKC pathways selectively control IL-17A/F + TNF-α-mediated synergistic production of HDPs LCN-2 and Elafin, but not chemokines IL-8 and GROα. Using a murine model of airway inflammation, we demonstrated enhancement of IL-17A/F, TNF-α, LCN-2 and neutrophil chemokine KC in the lungs, thus corroborating our findings in-vivo. Conclusion This study identifies proteins and signaling mediated by concurrent IL-17A/F and TNF-α exposure in the lungs, relevant to respiratory diseases characterized by chronic inflammation, especially neutrophilic airway inflammation such as severe asthma.

Cationic host defence peptides (CHDPs), also known as antimicrobial peptides, exhibit a wide range of activities contributing to immune responses and resolution of infections. CHDPs are expressed across diverse species, are generally amphipathic with less than 50 amino acids in length, and differ significantly in sequence and structure. This chapter focuses on the role of these peptides in immunity. CHDPs are known to function in both innate and adaptive immune responses. These peptides exert both pro-and anti-inflammatory properties, which are likely context dependent based on cell and tissue type, concentration of the peptides, and its interaction with other factors in the microenvironment. Furthermore, the crosstalk between CHDPs and the microbiome and how this may influence mucosal immunity is a rapidly emerging field of research. Overall, the immunomodulatory functions of CHDPs play an important role in the control of infections, regulation of inflammation, and maintaining immune homeostasis. It is thus not surprising that dysregulation of expression of CHDPs is implicated in the susceptibility, pathology, and progression of various diseases. In this chapter, we summarize the immunomodulatory functions of CHDPs, its clinical relevance, and the translational opportunities that these peptides provide for the development of new therapies.

Rationale Smoking and inflammation contribute to the pathogenesis of chronic obstructive pulmonary disease (COPD), which involves changes in extracellular matrix. This is thought to contribute to airway remodeling and airflow obstruction. We have previously observed that long-term treatment with inhaled corticosteroids can not only reduce bronchial inflammation, but can also attenuate lung function decline in moderate-severe COPD. We hypothesized that inhaled corticosteroids and current smoking modulate bronchial extracellular matrix components in COPD. Objective To compare major extracellular matrix components (elastic fibers; proteoglycans [versican, decorin]; collagens type I and III) in bronchial biopsies 1) after 30-months inhaled steroids treatment or placebo; and 2) between current and ex-smokers with COPD. Methods We included 64 moderate-severe, steroid-naive COPD patients (24/40 (ex)-smokers, 62±7 years, 46 (31–54) packyears, post-bronchodilator forced expiratory volume in one second (FEV1) 62±9% predicted) at baseline in this randomized, controlled trial. 19 and 13 patients received 30-months treatment with fluticasone or placebo, respectively. Bronchial biopsies collected at baseline and after 30 months were studied using (immuno)histochemistry to evaluate extracellular matrix content. Percentage and density of stained area were calculated by digital image analysis. Results 30-Months inhaled steroids increased the percentage stained area of versican (9.6% [CI 0.9 to 18.3%]; p = 0.03) and collagen III (20.6% [CI 3.8 to 37.4%]; p = 0.02) compared to placebo. Increased collagen I staining density correlated with increased post-bronchodilator FEV1 after inhaled steroids treatment (Rs = 0.45, p = 0.04). There were no differences between smokers and ex-smokers with COPD in percentages and densities for all extracellular matrix proteins. Conclusions These data show that long-term inhaled corticosteroids treatment partially changes the composition of extracellular matrix in moderate-severe COPD. This is associated with increased lung function, suggesting that long-term inhaled steroids modulate airway remodeling thereby potentially preventing airway collapse in COPD. Smoking status is not associated with bronchial extracellular matrix proteins. Trial Registration ClinicalTrials.gov NCT00158847

Vitamin D plays an active role in the modulation of innate and adaptive immune responses as well as in the protection against respiratory pathogens, e.g. by increasing expression of the antimicrobial peptide hCAP18/LL-37. The main aim of this thesis was to elucidate the role of inflammation on the protective effects of vitamin D on respiratory host defense responses in chronic inflammatory lung diseases such as chronic obstructive pulmonary disease (COPD). Airway epithelial host defense responses in COPD patients are defective and these patients are therefore more susceptible to respiratory infections. In this thesis we have shown that exposure to cigarette smoke, a main risk factor for COPD, reduced expression of certain host defense mediators by affecting end-stage airway epithelial differentiation and might explains why COPD patients are more susceptible to respiratory infections. We have further demonstrated in the studies presented in this thesis that certain airway inflammatory mediators could possibly interfere with vitamin D metabolism by promoting expression of vitamin D degrading enzyme CYP24A1, thereby reducing local levels of vitamin D and accompanying protective antimicrobial and anti-inflammatory actions. These new insights may yield possible new strategies to target CYP24A1 that enhance local levels and signaling of vitamin D to increase protection against exacerbations in COPD patients.

Bronchopulmonary dysplasia is the most common complication when premature birth occurs at less than 28 weeks gestational age. The general aim of this thesis is to explore the therapeutic potential of interventions in signaling pathways, involved in lung development and oxidative stress-induced lung injury, to prevent or attenuate BPD in a neonatal rat model, in which experimental BPD is induced by exposure to hyperoxia. The therapeutic potential of the targeting compounds of signaling pathways was investigated by studying their beneficial effects on contributing factors to severe experimental BPD pathology, including aberrant alveolar and vascular development, inflammation, fibrosis, coagulation, vascular remodeling, pulmonary arterial hypertension and right ventricular hypertrophy. We found ⑴angiotensin II type 2 receptor ligand PD123319 attenuates hyperoxia-induced lung and heart injury at a low dose in newborn rats; ⑵ Metformin attenuates hyperoxia-induced lung injury in neonatal rats by reducing the inflammatory response; ⑶ Deficiency or inhibition of lysophosphatidic acid receptor 1 protects against hyperoxia-induced lung injury in neonatal rats; ⑷Adult lysophosphatidic acid receptor 1-deficient rats with hyperoxia-induced neonatal chronic lung disease are protected against lipopolysaccharide-induced acute lung injury; ⑸ Bone morphogenetic protein 9 protects against neonatal hyperoxia-induced impairment of alveolarization and pulmonary inflammation.

In this thesis, the role of the liver and lungs in atherosclerosis development were studied. The liver plays an important role in lipid metabolism and inflammation, the two main processes involved in atherogenesis. We show that continuous enhanced inflammation in hepatocytes increased the hepatic production of VLDL and aggravated atherosclerosis development in hyperlipidemic APOE*3-Leiden (E3L) mice as compared to control E3L mice. Poor lung function, most commonly caused by chronic obstructive pulmonary disease (COPD), is a risk factor for atherosclerosis development. To this end, we investigated whether elastase-induced alveolar wall destruction, a model for COPD, would worsen atherosclerosis development in E3L mice. No difference in atherosclerotic lesion size was observed between mice after elastase or vehicle instillation, indicating that alveolar destruction per se is not responsible for the increased risk for atherosclerosis in COPD patients. Furthermore, we studied the anti-atherosclerotic effects of resveratrol which can be found in red wine and Asian medicinal herbs. Hyperlipidemic E3L.CETP mice were fed a diet without (control) or with resveratrol, atorvastatin, or both. Resveratrol protected against atherosclerosis development, but did not add to the anti-atherogenic effects of atorvastatin. Finally, the clinical implications and future perspectives of these results are discussed.