The helminth defense molecules (HDM) are a family of immune regulatory peptides exclusively expressed by trematode worms. We have previously demonstrated that in vivo FhHDM-1, the archetypal member of the HDMs, regulated macrophage responses to inflammatory ligands, thereby ameliorating the progression of immune-mediated tissue damage in several murine models of inflammatory disease. Accordingly, we postulated that an understanding of the structure-function relationship of the HDMs would facilitate the identification of the minimal bioactive peptide, which would represent a more synthesizable, cost-effective, potent biotherapeutic. Thus, using a combination of bioinformatics, structural analyses, and cellular assays we discovered a 40 amino acid peptide derivative termed FhHDM-1.C2. This peptide contains a 12 amino acid motif at its N-terminus, which facilitates cellular interaction and uptake, and an amphipathic alpha-helix within the C-terminus, which is necessary for lysosomal vATPase inhibitory activity, with both regions linked by a short unstructured segment. The FhHDM-1.C2 peptide exhibits enhanced regulation of macrophage function, compared with the full-length FhHDM-1, and potent prevention of the progression of relapsing-remitting-experimental autoimmune encephalomyelitis (EAE) when administered prophylactically or therapeutically. The protective effect of FhHDM-1.C2 is not associated with global immune suppression, which places the HDMs peptides as an improved class of biotherapeutics for the treatment of inflammatory diseases. Comparing the HDMs from several zoonotic trematodes revealed a similar capacity for immune regulation. These important new advances into the structure-function relationship of the lead HDM peptide, FhHDM-1, encourage further prospecting and screening of the broader trematode family of peptides for the discovery of novel and potent immune-biotherapeutics.

Sepsis results from a dysregulated host immune response to infection and is responsible for similar to 11 million deaths each year. In the laboratory, many aspects of sepsis can be replicated using a cecal ligation and puncture model, which is considered the most clinically relevant rodent model of sepsis. In the present study, histological and biomarker multiplex analyses revealed that the cecal ligation and puncture model initiated a large-scale inflammatory response in mice by 24 h, with evidence of acute organ damage by 48-72 h. While many typical proinflammatory cytokine/chemokines were systemically elevated, a specific array including IL-10, eotaxin, MIP-1 alpha, MIP-1 beta, MCP-1, and RANTES noticeably increased just prior to animals reaching the humane endpoint. Treatment of mice with 10 mu g of a synthetic 68-amino acid peptide derived from an immunomodulatory molecule secreted by a parasitic worm of humans and livestock, F. hepatica, termed F. hepatica helminth defense molecule, potently suppressed the systemic inflammatory profile, protected mice against acute kidney injury, and improved survival between 48 and 72 h after procedure. These results suggest that the anti-inflammatory parasite-derived F. hepatica helminth defense molecule peptide has potential as a biotherapeutic treatment for sepsis.

Cellular senescence has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). The mechanisms of senescence in the bronchial epithelium, however, remain largely unknown. In this study, we aimed to elucidate whether cellular senescence in COPD epithelial cells contributes to the pathogenesis of the disease and investigated the potential molecular mechanisms involved. Single-cell RNA sequencing was performed on well-differentiated primary bronchial epithelial cells from patients with COPD and healthy subjects. We evaluated the abundance and distribution of senescence markers in key epithelial differentiated subtypes and senescence-associated secretory phenotype involved in airway epithelial dysfunction. The effects of IFN-pathway inhibitors on cellular senescence were also investigated. There was increased expression of cellular senescence genes in the COPD cohort, which was predominantly in basal and club cells. Enhanced expression of cellular senescence markers, p16 and p21, was observed in COPD cultures, which was histologically confirmed in the lung tissue of patients with COPD. There was also a notable increase in IFN-β and IFN-γ. Senescence-associated secretory phenotype productions were increased in COPD and were attenuated by JAK-STAT or cGAS-STING pathway inhibitors (baricitinib or C-176). These inhibitors also effectively suppressed expression of senescence markers. COPD bronchial epithelium displays a senescence-driven phenotype which is mediated by Type I/II IFNs. Inhibition of JAK-STAT or STING-cGAS IFN pathways may represent targets to alleviate cellular senescence and chronic inflammation in COPD.

Radiotherapy (RT) treatment is an important strategy for the management of non-small cell lung cancer (NSCLC). Local recurrence amongst patients with late-stage NSCLC remains a challenge. The loss of PTEN has been associated with radio-resistance. This study aimed to examine the efficacy of RT combined with ataxia telangiectasia-mutated Rad3-related (ATR) inhibition using Ceralasertib in phosphatase and tensin homolog (PTEN)-depleted NSCLC cells and to assess early inflammatory responses indicative of radiation pneumonitis (RP) after combined-modality treatment. Small hairpin RNA (shRNA) transfections were used to generate H460 and A549 PTEN-depleted models. Ceralasertib was evaluated as a single agent and in combination with RT in vitro and in vivo. Histological staining was used to assess immune cell infiltration in pneumonitis-prone C3H/NeJ mice. Here, we report that the inhibition of ATR in combination with RT caused a significant reduction in PTEN-depleted NSCLC cells, with delayed DNA repair and reduced cell viability, as shown by an increase in cells in Sub G1. Combination treatment in vivo significantly inhibited H460 PTEN-depleted tumour growth in comparison to H460 non-targeting PTEN-expressing (NT) cell-line-derived xenografts (CDXs). Additionally, there was no significant increase in infiltrating macrophages or neutrophils except at 4 weeks, whereby combination treatment significantly increased macrophage levels relative to RT alone. Overall, our study demonstrates that ceralasertib and RT combined preferentially sensitises PTEN-depleted NSCLC models in vitro and in vivo, with no impact on early inflammatory response indicative of RP. These findings provide a rationale for evaluating ATR inhibition in combination with RT in NSCLC patients with PTEN mutations.

Mesenchymal stromal cells (MSCs) are multipotent adult stem cells which possess immunomodulatory and repair capabilities. In this study, we investigated whether MSC therapy could modulate inflammation and lung damage in the lungs of Scnn1b-transgenic mice overexpressing the β-subunit of the epithelial sodium channel (β-ENaC), a model with features of Cystic Fibrosis lung disease. Human bone marrow derived MSC cells were intravenously delivered to mice, prior to collection of bronchoalveolar lavage (BALF) and tissue. BALF analysis revealed a significant reduction in inflammatory cells after MSC administration, with both monocytic cells and neutrophils significantly reduced. Pro-inflammatory cytokines keratinocyte-derived chemokine (KC) and osteopontin were also significantly reduced. Histological tissue analysis revealed a reduction in emphysema in Scnn1b-TG mice treated with MSCs and consistent with these findings, improvements in lung function after MSC therapy were observed. Furthermore, MSCs enhanced Ki67 staining in alveolar cells, which may indicate regeneration of the destroyed parenchyma. Mechanistically, restoration of peroxisome proliferator-activated receptor-γ (PPARγ) expression and its transcriptional program were identified after MSC treatment. Our data demonstrate that MSC therapy can reduce inflammation, damage, and lung function decline in the chronically inflamed lung of Scnn1b-Tg mice, suggesting that MSCs may provide an effective tool in the treatment of muco-obstructive diseases such as cystic fibrosis.

Secretory leukocyte protease inhibitor (SLPI) is an important cationic protein involved in innate airway immunity and highly expressed in mucosal secretions, shown to target and inhibit neutrophil elastase (NE), cathepsin G and trypsin activity to limit proteolytic activity. In addition to the potent anti-protease activity, SLPI has been demonstrated to exert a direct anti-inflammatory effect, which is mediated via increased inhibition and competitive binding of NF-κB, regulating immune responses through limiting transcription of pro-inflammatory gene targets. In muco-obstructive lung disorders, such as Chronic Obstructive Pulmonary Disease (COPD) and Cystic Fibrosis (CF), there is an observed elevation in airway SLPI protein concentrations as a result of increased lung inflammation and disease progression. However, studies have identified COPD patients presenting with diminished SLPI concentrations. Furthermore, there is a decrease in SLPI concentrations through cleavage and subsequent inactivation by NE degradation in Pseudomonas aeruginosa infected people with CF (pwCF). These observations suggest reduced SLPI protein levels may contribute to the compromising of airway immunity indicating a potential role of decreased SLPI levels in the pathogenesis of muco-obstructive lung disease. The Beta Epithelial Na+ Channel transgenic (ENaC-Tg) mouse model phenotype exhibits characteristics which replicate the pathological features observed in conditions such as COPD and CF, including mucus accumulation, alterations in airway morphology and increased pulmonary inflammation. To evaluate the effect of SLPI in muco-obstructive pulmonary disease, ENaC-Tg mice were crossed with SLPI knock-out (SLPI-/-) mice, generating a ENaC-Tg/SLPI-/- colony to further investigate the role of SLPI in chronic lung disease and determine the effect of its ablation on disease pathogenesis.

Cellular senescence is a state of permanent cell cycle arrest triggered by various intrinsic and extrinsic stressors. Cellular senescence results in impaired tissue repair and remodeling, loss of physiological integrity, organ dysfunction, and changes in the secretome. The systemic accumulation of senescence cells has been observed in many age-related diseases. Likewise, cellular senescence has been implicated as a risk factor and driving mechanism in chronic obstructive pulmonary disease (COPD) pathogenesis. Airway epithelium exhibits hallmark features of senescence in COPD including activation of the p53/p21WAF1/CIP1 and p16INK4A/RB pathways, leading to cell cycle arrest. Airway epithelial senescent cells secrete an array of inflammatory mediators, the so-called senescence-associated secretory phenotype (SASP), leading to a persistent low-grade chronic inflammation in COPD. SASP further promotes senescence in an autocrine and paracrine manner, potentially contributing to the onset and progression of COPD. In addition, cellular senescence in COPD airway epithelium is associated with telomere dysfunction, DNA damage, and oxidative stress. This review discusses the potential mechanisms of airway epithelial cell senescence in COPD, the impact of cellular senescence on the development and severity of the disease, and highlights potential targets for modulating cellular senescence in airway epithelium as a potential therapeutic approach in COPD.

The constitutive proteasome and its inflammation-driven derivative, the immunoproteasome (IP), perform important intracellular proteolytic functions, including terminal protein degradation and antigen processing. However, the IP is increasingly recognised as being present in the extracellular space during pathology, though its mechanisms of release and functions are unknown. The lungs of patients with acute respiratory distress syndrome (ARDS) are flooded with complex oedema fluid and characterising the pathogenic components within this extracellular environment may help identify therapeutic targets. We hypothesised that extracellular IP is a feature of and plays a role in ARDS. We show that the levels and activity of IP are elevated in bronchoalveolar lavage fluid from patients with ARDS, the human healthy volunteer LPS model and the murine inhaled LPS model. Furthermore, in a series of in vitro experiments, we demonstrate that IP is released constitutively from macrophage-like cells and primary human macrophages. Importantly, this release can be augmented by activation of the NLRP3 and AIM2 inflammasomes. Using both pharmacological and genetic strategies we show that targeting the inflammasome pathway abrogates IP release from macrophages, confirming the importance of this pathway in IP release. We next sought to identify extracellular substrates of IP, the cleavage of which might contribute to the inflamed environment of the lung in ARDS. We report that IP is able to cleave several anti-inflammatory proteins that are present in the ARDS lung, including antiproteases and the phospholipid-binding protein Annexin A1. In conclusion, extracellular IP is a feature in human ARDS and models of ARDS. We have identified a potential mechanism of release of IP, which is closely linked to inflammasome activation, and postulate that extracellular IP may play a pro-inflammatory role in the acutely inflamed lung.

Inhalation therapy using nebulisers is an attractive non-invasive route for drug delivery, particularly for the treatment of lung infections with anti-inflammatory and anti-microbial compounds. This study evaluated the suitability of three snake-derived peptides (termed Sn1b, SnE1 and SnE1-F), which we have recently shown have potent anti-inflammatory and bacteriostatic activities, for nebulisation using a vibrating mesh nebuliser (VMN). The effect of nebulisation on peptide concentration, stability and function were assessed, prior to progression to aerodynamic particle size distribution, and in vitro drug delivery in simulated adult spontaneous breathing and mechanical ventilated patient models. When nebulised, all three peptides exhibited similar functions to their non-nebulised counterparts and were found to be respirable during simulated mechanical ventilation. Based on the assessment of the droplet distributions of nebulised peptides using a Next Generation Impactor (NGI) demonstrated that if administered in vivo each peptide would likely be delivered to the lower airways. These data suggest that nebulisation using a VMN is a viable means of anti-microbial / anti-inflammatory peptide delivery targeting microbial respiratory infections, and possibly even systemic infections.

function.Surgically resected sinonasal tissues and explanted donor lungs were used to validate findings.Results: scRNA-seq analysis completed for 9 healthy subjects and 10 PwCF revealed persistent differences between PwCF receiving HEMT and healthy controls.Substantial neutrophilic inflammation was prominent in the CF sinonasal mucosa, indicated by excess neutrophils with CF-specific programming and high pro-inflammatory gene expression in virtually all epithelial cell types.The CF epithelium continues to exhibit evidence of remodeling based on gene expression signatures consistent with immature ciliated cells and mucous and squamous cell metaplasia.The underlying CF basal cell stem pool contained a different proportion of proliferating, resting, and differentiating cells than the healthy samples.Trajectory analysis suggests that cellular differentiation pathways remain altered in CF, potentially because of an increase in injury repair.Computational prediction of cell-cell signaling relationships revealed changes in Notch, Wnt, and other signaling pathways that control epithelial differentiation.Evidence of aberrant cell signaling and epithelial cells with altered structure and programming were also detectable in histological sections of sinonasal tissue.ALI cultures derived from CF sinonasal airway epithelial cells isolated after 6 months of HEMT remained detectably different from healthy controls, with less differentiation capacity and barrier function.Conclusions: Despite considerable clinical improvements at 6 months, airway epithelial inflammation and dysfunction are not fully rectified when HEMT is initiated in adults with existing airway disease.Unraveling the molecular mechanisms driving these responses will have implications for the long-term use of HEMT, especially in an aging population of PwCF.

Cellular senescence has been implicated in COPD pathogenesis. Severe COPD is associated with exacerbations, hospitalisations and increased mortality. Airway inflammation and emphysema present many overlapping hallmark characteristics of senescence. However, features of bronchial epithelial senescence in severe COPD inflammation and in virus-induced exacerbations are not well understood. To address this, we characterised well-differentiated primary bronchial epithelial cells (WD-PBECs) derived from severe COPD patients undergoing lung transplantation and compared them to age-matched healthy controls using the air-liquid interface (ALI) culture model. Single-cell RNA-sequencing was carried out to identify the transcriptomes of the two cultures before and after rhinovirus infection. Expression of senescence markers and senescence-associated secretory phenotype (SASP) were analysed. The senescence markers p16-INK4A, p21Waf1/Cip1 and p53 were increased in COPD cultures compared with healthy controls. HRV infection further exacerbates SASP in COPD. A series of interferon-associated genes which upregulated in healthy subjects in response to rhinovirus infection were completely lost in infected COPD cultures. There were dramatically reduced levels of IL29 (IFNλ) in HRV infected COPD compared with healthy subjects. Our data demonstrate that the epithelium in severe COPD displays a senescent phenotype in terms of increased expression of senescent markers and SASP associated inflammatory response. After HRV infection there was further heightened COPD inflammation by elevated secretion of SASP and, importantly, there was impaired interferon anti-viral responses in COPD.

The constitutive proteasome and its inflammation-driven derivative, the immunoproteasome (IP), perform important intracellular proteolytic functions. However, the IP is increasingly recognised as being present in the extracellular space during pathology, though its mechanisms of release and functions are unknown. We hypothesised that extracellular IP is a feature of, and plays a role in, the acute respiratory distress syndrome (ARDS). We show that the levels and activity of IP are elevated in bronchoalveolar lavage fluid from patients with ARDS, the human healthy volunteer LPS model and the murine inhaled LPS model. In a series of in vitro experiments, we demonstrate that IP is released constitutively from macrophages, though this release can be exacerbated by activation of the NLRP3 and AIM2 inflammasomes, and that IP release can be abrogated by pharmacological or genetic targeting of the inflammasome pathway. We have found that direct instillation of IP alone into the lungs of mice does not induce inflammation. However, when administered in combination with bacterial endotoxin, IP appears to alter the inflammatory cell population within the lung. We plan to further characterise these changes in order to understand the role of extracellular IP in ARDS. Closely linked to this, since the extracellular substrates of IP are not known, identifying such targets represents a key aspect of our future work. In conclusion, extracellular IP is a feature in human ARDS and murine ARDS-like disease. We have identified a potential mechanism of release of IP, which is closely linked to inflammasome activation, and are exploring the relevance of extracellular IP in the acutely inflamed lung.

The coronavirus disease (COVID-19) pandemic, which has been driven by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, has caused significant morbidity and mortality worldwide. With a range of clinical responses from asymptomatic to severe, it has particularly targeted the elderly and those suffering from underlying disease conditions. Individuals with chronic obstructive pulmonary disease (COPD) are susceptible to a range of respiratory viral infections, and it is therefore not surprising that COPD is a risk factor for hospitalization, mechanical ventilation, severe disease, and mortality in COVID-19 (1). The effects of the COVID-19 pandemic have been globally devastating; however, as new viral strains emerge and population immunity increases, focus has turned to those groups with greater risk of developing severe disease determined early in the pandemic with risk factors including age, sociodemographic status, and preexisting comorbid conditions (2). Preexisting chronic respiratory diseases, such as asthma, interstitial lung disease, and COPD, are associated with increased risk of poor outcome although the mechanisms remain poorly described (3). The use of primary bronchial epithelial cells (PBECs) from individuals with a range of lung conditions has proved useful in understanding altered responses in these cells at baseline and following infection to delineate disease mechanisms (4). New insights published in this Journal by Johansen and colleagues (pp. 712–729), provide experimental evidence supporting increased susceptibility and severity of infection in patients with COPD, using a well-defined air–liquid interface model of PBECs from patients with COPD and healthy volunteers (5). The use of such patient-derived cell models provides amuch clearer path to translation than cell line or murinemodels of disease, although it will be interesting to see how these findings translate to viral infection of type-II pneumocytes (AT2), which are tied to the development of acute respiratory distress syndrome. This will, of course, be technically challenging, but the use of alveosphere culture models may help to address this to some extent (6). Arguably, the pivotal finding from the study by Johansen and colleagues, in addition to the diminished interferon and enhanced proinflammatory response of COPD PBECs after infection, is the discovery of a protease–antiprotease imbalance that may predispose these cells to an increased degree of infection by the SARS-CoV-2 virus andmay explain, to some degree, why individuals with COPD are at greater risk of infection by this virus and severe disease (5). It is well established that some viruses, for example HIV and hepatitis C, use a variety of endogenous and therapeutically relevant viral proteases to enter or replicate within host cells (7). In addition, host proteases that assist in this process have also been identified, and expression of a number of these were elevated in COPD PBECs. Notably, furin-like proteases and TMPRSS2 (transmembrane serine protease 2) enable the initial stage of SARS-CoV-2 entry into cells (8). CTSL (cathepsin L) and CTSB (cathepsin B) may also play a role in SARS-CoV-2 virus entry, suggesting that more than one host cysteinyl cathepsin protease may be involved (9). Furthermore, a range of other proteases may also participate in SARS-CoV-2 cell entry, including trypsin-like proteases andmembers of the coagulation cascade including plasmin (10, 11). In addition to elevated TMPRSS2 and CTSB, a significant finding by Johansen and colleagues is the demonstration of decreased expression of the serine protease inhibitors (serpins) leukocyte elastase inhibitor (SERPINB1), SERPINB4, and SERPINB6 in COPD PBECs, which may facilitate greater uptake of SARS-CoV-2 in these cells. Although it is not clear if TMPRSS2 activity is inhibited by any of the serpins highlighted in this study, decreased concentrations of these antiproteases may be indicative of the presence of other dysregulated proteases in COPD PBECs, which may also facilitate SARS-CoV-2 uptake and replication. In support of these findings, it has recently been demonstrated that other members of the serpin family, a-1-antitrypsin (serpin A1), plasminogen activator inhibitor 1 (serpin E1), and glia-derived nexin (serpin E2), may also reduce SARS-CoV-2 infection via inhibition of TMPRSS2-mediated spike protein cleavage (12). It will be interesting to establish if SARS-CoV-2modulates serpin expression in target cells to facilitate uptake and replication of the virus. This study confirms the importance of using patient-derived cells to gain insight into the pathogenesis of COVID-19. Despite the importance of cell lines and healthy primary cells in establishing viralcellular interactions, the current study underscores the importance of evaluating cells from diseased tissue as the demonstration of elevated expression of proteases and diminished levels of antiprotease protection in this disease setting (COPD) can only really be appreciated by using patient-derived cells. As suggested by Johansen and colleagues, the targeting of proteases such as TMPRSS2 andmembers of the cysteinyl cathepsin familymay be warranted in the fight against COVID-19 infection. However, it should also bementioned that the field of viral protease inhibitor research has yielded the development of drugs that successfully target the HIV-1 protease and the hepatitis CNS3 protease (7). SARS-CoV-2 has its own repertoire of proteases required for replication within the cell, including the main protease (M sometimes called 3CL) and the papain-like protease (PL), and attempts to target these proteases are underway (13). As can be appreciated from clinicaltrials.gov, a significant number of clinical trials are in process, or have been completed, to target proteases in COVID-19, primarily TMPRSS2 and SARS-CoV-2 proteases, and include the use of aprotinin, camostat mesylate, a-1-antitrypsin and This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0. For commercial usage and reprints, please e-mail Diane Gern (dgern@thoracic.org).

An important regulator of innate and adaptive airway immunity, the primary function of Secretory Leukocyte Protease Inhibitor (SLPI) is considered to be the inhibition of damaging neutrophil elastase activity. In addition to anti-proteolytic activity, SLPI expresses both anti-microbial and anti-inflammatory properties, through action on NF-kB. Although elevated in chronic lung diseases such as Chronic Obstructive Pulmonary Disease, lower concentrations of SLPI are associated with frequent exacerbations of muco-obstructive disorders. In this study we evaluated a role for SLPI in the development of airway pathogenesis and mucus obstruction in chronic lung disease. A murine model of chronic lung disease, the β-epithelial sodium channel-overexpressing transgenic (ENaC) mouse was crossed with SLPI null (SLPI−/−) strains to generate four genotypes: Wild Type (WT), SLPI−/−, ENaC and ENaC/SLPI−/−. At juvenile (2-3 weeks) and adult (8-14 weeks) ages mice were assessed for mucus plugging, inflammatory cell counts and protease activity. Genetic deletion of SLPI resulted in increased lung inflammatory cell counts in adult WT and ENaC mice, while no effect was identified in juvenile ENaC/SLPI−/− mice. In addition, decreased airway mucus volume and plugging was observed in adult ENaC/SLPI−/− mice, but not juvenile mice. However, genetic deletion of SLPI was shown to increase protease activity in juvenile ENaC/SLPI−/− mice alone. These data suggest genetic deletion of SLPI decreases mucus plugging in adult ENaC mice, while increasing immune cell infiltration. However, ablation of SLPI in juvenile strains of ENaC mice results in increased lung protease activity.

inhibitors to ameliorate lung disease has had a difficult history with limited success to date. However, recent studies have shownmore success including the use of a-1-antitrypsin to slow the progression of emphysema in patients with a-1-antitrypsin deficiency (RAPID trial) (14) and the use of the cathepsin C inhibitor, brensocatib, which has shown some success in patients with bronchiectasis (15). In conclusion, future therapeutic strategies to treat COVID-19 infection could incorporate the use of viral and host-directed protease inhibitors, and the development, and repurposing, of protease inhibitors to this end should be a focus of COVID-19 treatment strategies.

BackgroundRespiratory viral infections are closely associated with COPD exacerbations, hospitalisations, and significant morbidity and mortality. The consequences of the persisting inflammation and differentiation status in virus associated severe disease is not fully understood. The aim of this study was to evaluate barrier function, cellular architecture, the inflammatory response in severe COPD bronchial epithelium to human rhinovirus (HRV) induced pathological changes and innate immune responses.MethodsWell-differentiated primary bronchial epithelial cells (WD-PBECs) derived from severe COPD patients and age-matched healthy controls were cultured in the air-liquid interface (ALI) model. The differentiation phenotype, epithelial barrier integrity, pathological response and cytokine secreting profile of these cultures before and after HRV infection were investigated.ResultsWD-PBECs derived from severe COPD patients showed aberrant epithelium differentiation with a decreased proportion of ciliated cells but increased numbers of club cells and goblet cells compared with healthy controls. Tight junction integrity was compromised in both cultures following HRV infection, with heightened disruptions in COPD cultures. HRV induced increased epithelial cell sloughing, apoptosis and mucus hypersecretion in COPD cultures compared with healthy controls. A Th1/Th2 imbalance and a strong interferon and pro-inflammatory cytokine response was also observed in COPD cultures, characterized by increased levels of IFNγ, IFNβ, IP-10, IL-10 and decreased TSLP and IL-13 cytokine levels prior to HRV infection. Significantly enhanced basolateral secretion of eotaxin 3, IL-6, IL-8, GM-CSF were also observed in both mock and HRV infected COPD cultures compared with corresponding healthy controls. In response to HRV infection, all cultures displayed elevated levels of IFNλ1 (IL-29), IP-10 and TNFα compared with mock infected cultures. Interestingly, HRV infection dramatically reduced IFNλ levels in COPD cultures compared with healthy subjects.ConclusionAn altered differentiation phenotype and cytokine response as seen in severe COPD WD-PBECs may contribute to increased disease susceptibility and an enhanced inflammatory response to HRV infection.

The advent of Cystic fibrosis transmembrane receptor (CFTR) modulators in 2012 was a critical event in the history of cystic fibrosis (CF) treatment. Unlike traditional therapies that target downstream effects of CFTR dysfunction, CFTR modulators aim to correct the underlying defect at the protein level. These genotype-specific therapies are now available for an increasing number of CF patients, transforming the way we view the condition from a life-limiting disease to one that can be effectively managed. Several studies have demonstrated the vast improvement CFTR modulators have on normalization of sweat chloride, CFTR function, clinical endpoints, and frequency of pulmonary exacerbation. However, their impact on other aspects of the disease, such as pathogenic burden and airway infection, remain under explored. Frequent airway infections as a result of increased susceptibility and impaired innate immune response are a serious problem within CF, often leading to accelerated decline in lung function and disease progression. Current evidence suggests that CFTR modulators are unable to eradicate pathogenic organisms in those with already established lung disease. However, this may not be the case for those with relatively low levels of disease progression and conserved microbial diversity, such as young patients. Furthermore, it remains unknown whether the restorative effects exerted by CFTR modulators extend to immune cells, such as phagocytes, which have the potential to modulate the response of people with CF (pwCF) to infection. Throughout this review, we look at the potential impact of CFTR modulators on airway infection in CF and their ability to shape impaired pulmonary defences to pathogens.

Rationale: Although the cysteine protease cathepsin S has been implicated in the pathogenesis of several inflammatory lung diseases, its role has not been examined in the context of acute respiratory distress syndrome, a condition that still lacks specific and effective pharmacological treatments. Objectives: To characterize the status of cathepsin S in acute lung inflammation and examine the role of cathepsin S in disease pathogenesis. Methods: Human and mouse model BAL fluid samples were analyzed for the presence and activity of cathepsin S and its endogenous inhibitors. Recombinant cathepsin S was instilled directly into the lungs of mice. The effects of cathepsin S knockout and pharmacological inhibition were examined in two models of acute lung injury. Protease-activated receptor-1 antagonism was used to test a possible mechanism for cathepsin S-mediated inflammation. Measurements and Main Results: Pulmonary cathepsin S concentrations and activity were elevated in acute respiratory distress syndrome, a phenotype possibly exacerbated by the loss of the endogenous antiprotease cystatin SN. Direct cathepsin S instillation into the lungs induced key pathologies of acute respiratory distress syndrome, including neutrophilia and alveolar leakage. Conversely, in murine models of acute lung injury, genetic knockdown and prophylactic or therapeutic inhibition of cathepsin S reduced neutrophil recruitment and protein leakage. Cathepsin S may partly mediate its pathogenic effects via protease-activated receptor-1, because antagonism of this receptor abrogated cathepsin S-induced airway inflammation. Conclusions: Cathepsin S contributes to acute lung injury and may represent a novel therapeutic target for acute respiratory distress syndrome.