Antibacterial Defense of Human Airway Epithelial Cells from Chronic Obstructive Pulmonary Disease Patients Induced by Acute Exposure to Nontypeable Haemophilus influenzae: Modulation by Cigarette Smoke

Abstract

Antimicrobial proteins and peptides (AMPs) are a central component of the antibacterial activity of airway epithelial cells. It has been proposed that a decrease in antibacterial lung defense contributes to an increased susceptibility to microbial infection in smokers and patients with chronic obstructive pulmonary disease (COPD). However, whether reduced AMP expression in the epithelium contributes to this lower defense is largely unknown. We investigated the bacterial killing activity and expression of AMPs by air-liquid interface-cultured primary bronchial epithelial cells from COPD patients and non-COPD (ex-)smokers that were stimulated with nontypeable Haemophilus influenzae (NTHi). In addition, the effect of cigarette smoke on AMP expression and the activation of signaling pathways was determined. COPD cell cultures displayed reduced antibacterial activity, whereas smoke exposure suppressed the NTHi-induced expression of AMPs and further increased IL-8 expression in COPD and non-COPD cultures. Moreover, smoke exposure impaired NTHi-induced activation of NF-κB, but not MAP-kinase signaling. Our findings demonstrate that the antibacterial activity of cultured airway epithelial cells induced by acute bacterial exposure was reduced in COPD and suppressed by cigarette smoke, whereas inflammatory responses persisted. These findings help to explain the imbalance between protective antibacterial and destructive inflammatory innate immune responses in COPD.

Human lung epithelial cell cultures for analysis of inhaled toxicants: Lessons learned and future directions

“…The advantage of this option is underlined by the observation that ALI-cultured airway epithelial cells derived from patients with mild or severe asthma retain characteristics of the distorted airway epithelium present in the patients lungs, and that the phenotypic differences relate to the severity of asthma (Gras et al, 2012). Similar observations have been reported in COPD (Amatngalim et al, 2017;Staudt et al, 2014), suggesting that the lung microenvironment in these inflammatory lung diseases causes (epigenetic) changes in epithelial cells resulting in partial persistence of the phenotype in culture.…”

“…We recently showed that the ALI-differentiated cultures used in our laboratory for exposures to e.g. diesel exhaust (Zarcone et al, 2016;Zarcone et al, 2017) or cigarette smoke (Amatngalim et al, 2015;Amatngalim et al, 2017) show higher expression of various genes involved in biotransformation compared to undifferentiated cultures (Boei et al, 2016). Furthermore, we showed that undifferentiated cultures, in contrast to differentiated cultures, are incapable of metabolic conversion of a variety of different p450 substrates.…”

“…Although an extensive discussion of the various read-outs is beyond the scope of this review, it needs to be stressed that a range of other parameters are currently assessed to determine the biological effect of an inhaled toxicant in in vitro cell culture systems. These include the various -omics techniques, as illustrated by the effect of electronic cigarette liquid on the metabolome of airway epithelial cells (Aug et al, 2015), markers of oxidative stress, induction of an oxidative stress response and inflammatory response (Zarcone et al, 2016;Zarcone et al, 2017;Kuper et al, 2015;Kooter et al, 2013), induction of the integrated stress response (Zarcone et al, 2016;Zarcone et al, 2017), impairment of autophagy (Shivalingappa et al, 2015), and impairment of epithelial antimicrobial defence (Amatngalim et al, 2017;Herr et al, 2009;Wu et al, 2014). Adsorption of test compounds can be specifically addressed by using radiolabeled substances that are applied via the apical surface, as demonstrated by Reus et al using the MucilAirTM model of differentiated human bronchial epithelial cells (Reus et al, 2014).…”

Transcriptomic and barrier responses of human airway epithelial cells exposed to cannabis smoke

“…Our data demonstrating striking similarities in the epithelial immune profile in response to cannabis and tobacco, suggests that the former will impact host defences. Tobacco has been demonstrated to impact host defence peptide induction in airway epithelial cells by nontypeable Haemophilus influenzae with a concomitant increase in IL‐8 expression (Amatngalim et al, ). Our experimental dataset in this study did not include a pathogen challenge, precluding our ability confirm the tobacco smoke induced suppression of host defence peptides or to extend the results to cannabis smoke.…”

Full Complement

“…However, long-standing and dysregulated inflammation in the airways is a key feature of several states of disease, e.g., in COPD and cystic fibrosis [11][12][13]. Furthermore, without a preceding chronic airway inflammation, the host response may cause tissue damage [10,14].…”