Inhaled LPS challenges in smokers: a study of pulmonary and systemic effects

Use of human airway smooth muscle in vitro and ex vivo to investigate drugs for the treatment of chronic obstructive respiratory disorders

Isolated airway smooth muscle has been extensively investigated since 1840 to understand the pharmacology of airway diseases. There has often been poor predictability from murine experiments to drugs evaluated in patients with asthma or chronic obstructive pulmonary disease (COPD). However, the use of isolated human airways represents a sensible strategy to optimise the development of innovative molecules for the treatment of respiratory diseases. This review aims to provide updated evidence on the current uses of isolated human airways in validated in vitro methods to investigate drugs in development for the treatment of chronic obstructive respiratory disorders. This review also provides historical notes on the pioneering pharmacological research on isolated human airway tissues, the key differences between human and animal airways, as well as the pivotal differences between human medium bronchi and small airways. Experiments carried out with isolated human bronchial tissues in vitro and ex vivo replicate many of the main anatomical, pathophysiological, mechanical and immunological characteristics of patients with asthma or COPD. In vitro models of asthma and COPD using isolated human airways can provide information that is directly translatable into humans with obstructive lung diseases. Regardless of the technique used to investigate drugs for the treatment of chronic obstructive respiratory disorders (i.e., isolated organ bath systems, videomicroscopy and wire myography), the most limiting factors to produce high-quality and repeatable data remain closely tied to the manual skills of the researcher conducting experiments and the availability of suitable tissue.

The effect of bradykinin 1 receptor antagonist BI 1026706 on pulmonary inflammation after segmental lipopolysaccharide challenge in healthy smokers

BACKGROUND

Bradykinin 1 receptor (B1R) signalling pathways may be involved in the inflammatory pathophysiology of chronic obstructive pulmonary disease (COPD). B1R signalling is induced by inflammatory stimuli or tissue injury and leads to activation and increased migration of pro-inflammatory cells. Lipopolysaccharide (LPS) lung challenge in man is an experimental method of exploring inflammation in the lung whereby interference in these pathways can help to assess pharmacologic interventions in COPD. BI 1026706, a potent B1R antagonist, was hypothesized to reduce the inflammatory activity after segmental lipopolysaccharide (LPS) challenge in humans due to decreased pulmonary cell influx.

METHODS

In a monocentric, randomized, double-blind, placebo-controlled, parallel-group, phase I trial, 57 healthy, smoking subjects were treated for 28 days with either oral BI 1026706 100 mg bid or placebo. At day 21, turbo-inversion recovery magnitude magnetic resonance imaging (TIRM MRI) was performed. On the last day of treatment, pre-challenge bronchoalveolar lavage fluid (BAL) and biopsies were sampled, followed by segmental LPS challenge (40 endotoxin units/kg body weight) and saline control instillation in different lung lobes. Twenty-four hours later, TIRM MRI was performed, then BAL and biopsies were collected from the challenged segments. In BAL samples, cells were differentiated for neutrophil numbers as the primary endpoint. Other endpoints included assessment of safety, biomarkers in BAL (e.g. interleukin-8 [IL-8], albumin and total protein), B1R expression in lung biopsies and TIRM score by MRI as a measure for the extent of pulmonary oedema.

RESULTS

After LPS, but not after saline, high numbers of inflammatory cells, predominantly neutrophils were observed in the airways. IL-8, albumin and total protein were also increased in BAL samples after LPS challenge as compared with saline control. There were no significant differences in cells or other biomarkers from BAL in volunteers treated with BI 1026706 compared with those treated with placebo. Unexpectedly, neutrophil numbers in BAL were 30% higher and MRI-derived extent of oedema was significantly higher with BI 1026706 treatment compared with placebo, 24 h after LPS challenge. Adverse events were mainly mild to moderate and not different between treatment groups.

CONCLUSIONS

Treatment with BI 1026706 for four weeks was safe and well-tolerated in healthy smoking subjects. BI 1026706 100 mg bid did not provide evidence for anti-inflammatory effects in the human bronchial LPS challenge model.

TRIAL REGISTRATION

The study was registered on January 14, 2016 at ClinicalTrials.gov (NCT02657408).

An inhibitor of RORγ for chronic pulmonary obstructive disease treatment

The role of RORγ as a transcription factor for Th17 cell differentiation and thereby regulation of IL-17 levels is well known. Increased RORγ expression along with IL-17A levels was observed in animal models, immune cells and BAL fluid of COPD patients. Increased IL-17A levels in severe COPD patients are positively correlated with decreased lung functions and increased severity symptoms and emphysema, supporting an urgency to develop novel therapies modulating IL-17 or RORγ for COPD treatment. We identified a potent RORγ inhibitor, PCCR-1 using hit to lead identification followed by extensive lead optimization by structure–activity relationship. PCCR-1 resulted in RORγ inhibition with a high degree of specificity in a biochemical assay, with > 300-fold selectivity over other isoforms of ROR. Our data suggest promising potency for IL-17A inhibition in human and canine PBMCs and mouse splenocytes with no significant impact on Th1 and Th2 cytokines. In vivo, PCCR-1 exhibited significant efficacy in the acute CS model with dose-dependent inhibition of the PD biomarkers that correlated well with the drug concentration in lung and BAL fluid, demonstrating an acceptable safety profile. This inhibitor effectively inhibited IL-17A release in whole blood and BALf samples from COPD patients. Overall, we identified a selective inhibitor of RORγ to pursue further development of novel scaffolds for COPD treatment.

N-Acetylcysteine in Mechanically Ventilated Rats with Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome: The Effect of Intravenous Dose on Oxidative Damage and Inflammation

Treatment of acute respiratory distress syndrome (ARDS) is challenging due to its multifactorial aetiology. The benefit of antioxidant therapy was not consistently demonstrated by previous studies. We evaluated the effect of two different doses of intravenous (i.v.) N-acetylcysteine (NAC) on oxidative stress, inflammation and lung functions in the animal model of severe LPS-induced lung injury requiring mechanical ventilation. Adult Wistar rats with LPS (500 μg/kg; 2.2 mL/kg) were treated with i.v. NAC 10 mg/kg (NAC10) or 20 mg/kg (NAC20). Controls received saline. Lung functions, lung oedema, total white blood cell (WBC) count and neutrophils count in blood and bronchoalveolar lavage fluid, and tissue damage in homogenized lung were evaluated. NAC significantly improved ventilatory parameters and oxygenation, reduced lung oedema, WBC migration and alleviated oxidative stress and inflammation. NAC20 in comparison to NAC10 was more effective in reduction of oxidative damage of lipids and proteins, and inflammation almost to the baseline. In conclusion, LPS-instilled and mechanically ventilated rats may be a suitable model of ARDS to test the treatment effects at organ, systemic, cellular and molecular levels. The results together with literary data support the potential of NAC in ARDS.

Role of Atypical Chemokines and Chemokine Receptors Pathways in the Pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) represents a heightened inflammatory response in the lung generally resulting from tobacco smoking-induced recruitment and activation of inflammatory cells and/or activation of lower airway structural cells. Several mediators can modulate activation and recruitment of these cells, particularly those belonging to the chemokines (conventional and atypical) family. There is emerging evidence for complex roles of atypical chemokines and their receptors (such as high mobility group box 1 (HMGB1), antimicrobial peptides, receptor for advanced glycosylation end products (RAGE) or toll-like receptors (TLRs)) in the pathogenesis of COPD, both in the stable disease and during exacerbations. Modulators of these pathways represent potential novel therapies for COPD and many are now in preclinical development. Inhibition of only a single atypical chemokine or receptor may not block inflammatory processes because there is redundancy in this network. However, there are many animal studies that encourage studies for modulating the atypical chemokine network in COPD. Thus, few pharmaceutical companies maintain a significant interest in developing agents that target these molecules as potential antiinflammatory drugs. Antibody-based (biological) and small molecule drug (SMD)-based therapies targeting atypical chemokines and/or their receptors are mostly at the preclinical stage and their progression to clinical trials is eagerly awaited. These agents will most likely enhance our knowledge about the role of atypical chemokines in COPD pathophysiology and thereby improve COPD management.

Association of exacerbation phenotype with the sputum microbiome in chronic obstructive pulmonary disease patients during the clinically stable state

Background

Chronic obstructive pulmonary disease (COPD) is a progressive, life-threatening lung disease with increasing prevalence and incidence worldwide. Increasing evidence suggests that lung microbiomes might play a physiological role in acute exacerbations of COPD. The objective of this study was to characterize the association of the microbiota and exacerbation risk or airflow limitation in stable COPD patients.

Methods

The sputum microbiota from 78 COPD outpatients during periods of clinical stability was investigated using 16S rRNA V3-V4 amplicon sequencing. The microbiome profiles were compared between patients with different risks of exacerbation, i.e., the low risk exacerbator (LRE) or high risk exacerbator (HRE) groups, and with different airflow limitation severity, i.e., mild to moderate (FEV1 ≥ 50; PFT I) or severe to very severe (FEV1 < 50; PFT II).

Results

The bacterial diversity (Chao1 and observed OTUs) was significantly decreased in the HRE group compared to that in the LRE group. The top 3 dominant phyla in sputum were Firmicutes, Actinobacteria, and Proteobacteria, which were similar in the HRE and LRE groups. At the genus level, compared to that in the LRE group (41.24%), the proportion of Streptococcus was slightly decreased in the HRE group (28.68%) (p = 0.007). However, the bacterial diversity and the proportion of dominant bacteria at the phylum and genus levels were similar between the PFT I and PFT II groups. Furthermore, the relative abundances of Gemella morbillorum, Prevotella histicola, and Streptococcus gordonii were decreased in the HRE group compared to those in the LRE group according to linear discriminant analysis effect size (LEfSe). Microbiome network analysis suggested altered bacterial cooperative regulation in different exacerbation phenotypes. The proportions of Proteobacteria and Neisseria were negatively correlated with the FEV1/FVC value. According to functional prediction of sputum bacterial communities through Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis, genes involved in lipopolysaccharide biosynthesis and energy metabolism were enriched in the HRE group.

Conclusion

The present study revealed that the sputum microbiome changed in COPD patients with different risks of exacerbation. Additionally, the bacterial cooperative networks were altered in the HRE patients and may contribute to disease exacerbation. Our results provide evidence that sputum microbiome community dysbiosis is associated with different COPD phenotypes, and we hope that by understanding the lung microbiome, a potentially modifiable clinical factor, further targets for improved COPD therapies during the clinically stable state may be elucidated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02788-4.

The Effect of Modified Porcine Surfactant Alone or in Combination with Polymyxin B on Lung Homeostasis in LPS-Challenged and Mechanically Ventilated Adult Rats

The study aimed to prove the hypothesis that exogenous surfactant and an antibiotic polymyxin B (PxB) can more effectively reduce lipopolysaccharide (LPS)-induced acute lung injury (ALI) than surfactant treatment alone, and to evaluate the effect of this treatment on the gene expression of surfactant proteins (SPs). Anesthetized rats were intratracheally instilled with different doses of LPS to induce ALI. Animals with LPS 500 μg/kg have been treated with exogenous surfactant (poractant alfa, Curosurf^®, 50 mg PL/kg b.w.) or surfactant with PxB 1% w.w. (PSUR + PxB) and mechanically ventilated for 5 hrs. LPS at 500 μg/kg increased lung edema, oxidative stress, and the levels of proinflammatory mediators in lung tissue and bronchoalveolar lavage fluid (BALF). PSUR reduced lung edema and oxidative stress in the lungs and IL-6 in BALF. This effect was further potentiated by PxB added to PSUR. Exogenous surfactant enhanced the gene expression of SP-A, SP-B, and SP-C, however, gene expression for all SPs was reduced after treatment with PSUR + PxB. In mechanically ventilated rats with LPS-induced ALI, the positive effect of exogenous surfactant on inflammation and oxidative stress was potentiated with PxB. Due to the tendency for reduced SPs gene expression after surfactant/PxB treatment topical use of PxB should be considered with caution.

Like Cures Like: Pharmacological Activity of Anti-Inflammatory Lipopolysaccharides From Gut Microbiome

Gut microbiome maintains local gut integrity and systemic host homeostasis, where optimal control of intestinal lipopolysaccharides (LPS) activity may play an important role. LPS mainly produced from gut microbiota are a group of lipid-polysaccharide chemical complexes existing in the outer membrane of Gram-negative bacteria. Traditionally, LPS mostly produced from Proteobacteria are well known for their ability in inducing strong inflammatory responses (proinflammatory LPS, abbreviated as P-LPS), leading to septic shock or even death in animals and humans. Although the basic structures and chemical properties of P-LPS derived from different bacterial species generally show similarity, subtle and differential immune activation activities are observed. On the other hand, frequently ignored, a group of LPS molecules mainly produced by certain microbiota bacteria such as Bacteroidetes show blunt or even antagonistic activity in initiating pro-inflammatory responses (anti-inflammatory LPS, abbreviated as A-LPS). In this review, besides the immune activation properties of P-LPS, we also focus on the description of anti-inflammatory effects of A-LPS, and their potential antagonistic mechanism. We address the possibility of using native or engineered A-LPS for immune modulation in prevention or even treatment of P-LPS induced chronic inflammation related diseases. Understanding the exquisite interactive relationship between structure-activity correlation of P- and A-LPS not only contributes to molecular understanding of immunomodulation and homeostasis, but also re-animates the development of novel LPS-based pharmacological strategy for prevention and therapy of chronic inflammation related diseases.

Use of autologous 99mTechnetium-labelled neutrophils to quantify lung neutrophil clearance in COPD

Rationale

There is a need to develop imaging protocols which assess neutrophilic inflammation in the lung.

Aim

To quantify whole lung neutrophil accumulation in (1) healthy volunteers (HV) following inhaled lipopolysaccharide (LPS) or saline and (2) patients with COPD using radiolabelled autologous neutrophils and single-photon emission computed tomography/CT (SPECT/CT).

Methods

20 patients with COPD (Global initiative for chronic obstructive lung disease (GOLD) stages 2–3) and 18 HVs were studied. HVs received inhaled saline (n=6) or LPS (50 µg, n=12) prior to the injection of radiolabelled cells. Neutrophils were isolated using dextran sedimentation and Percoll plasma gradients and labelled with ^99mTechnetium (Tc)-hexamethylpropyleneamine oxime. SPECT was performed over the thorax/upper abdomen at 45 min, 2 hours, 4 hours and 6 hours. Circulating biomarkers were measured prechallenge and post challenge. Blood neutrophil clearance in the lung was determined using Patlak-Rutland graphical analysis.

Results

There was increased accumulation of ^99mTc-neutrophils in the lungs of patients with COPD and LPS-challenged subjects compared with saline-challenged subjects (saline: 0.0006±0.0003 mL/min/mL lung blood distribution volume [mean ±1 SD]; COPD: 0.0022±0.0010 mL/min/mL [p<0.001]; LPS: 0.0025±0.0008 mL/min/mL [p<0.001]). The accumulation of labelled neutrophils in 10 patients with COPD who underwent repeat radiolabelling/imaging 7–10 days later was highly reproducible (0.0022±0.0010 mL/min/mL vs 0.0023±0.0009 mL/min/mL). Baseline interleukin (IL)-6 levels in patients with COPD were elevated compared with HVs (1.5±1.06 pg/mL [mean ±1 SD] vs 0.4±0.24 pg/mL). LPS challenge increased the circulating IL-6 levels (7.5±2.72 pg/mL) 9 hours post challenge.

Conclusions

This study shows the ability to quantify ‘whole lung’ neutrophil accumulation in HVs following LPS inhalation and in subjects with COPD using autologous radiolabelled neutrophils and SPECT/CT imaging. Moreover, the reproducibility observed supports the feasibility of using this approach to determine the efficacy of therapeutic agents aimed at altering neutrophil migration to the lungs.

The dose response of inhaled LPS challenge in healthy subjects

Lipopolysaccharide (LPS) inhalation causes neutrophilic airway inflammation. We used LPS produced to Good Manufacturing Practice (GMP) standards to characterise the dose response. A total of 15 healthy non-smoking subjects inhaled 5-, 15- and 50-µg LPS. Whole blood cell counts and serum C-reactive protein (CRP) were measured at baseline and up to 24 h post challenge. Sputum was induced at baseline and 6 h post challenge for cell counts and quantification of myeloperoxidase (MPO), interleukin (IL)-1β, IL-6, IL-8 and tumour necrosis factor α (TNF-α) in supernatants. LPS inhalation was well tolerated. Blood neutrophil counts increased at 6 h post LPS with all doses. Serum CRP significantly increased with 15- and 50-µg LPS. All LPS doses significantly increased sputum neutrophil percentage ( P < 0.001). IL-1β, IL-6 and TNF-α were significantly increased in sputum supernatant following challenge with 50-µg LPS, there was no change in MPO or IL-8. The 50-µg LPS was well tolerated and produced a robust inflammatory response. This study supports the use of 50-µg GMP-grade LPS as a suitable challenge agent in clinical trials.

The development of AZD7624 for prevention of exacerbations in COPD: a randomized controlled trial

Background

p38 mitogen-activated protein kinase (MAPK) plays a central role in the regulation and activation of pro-inflammatory mediators. COPD patients have increased levels of activated p38 MAPK, which correlate with increased lung function impairment, alveolar wall inflammation, and COPD exacerbations.

Objectives

These studies aimed to assess the effect of p38 inhibition with AZD7624 in healthy volunteers and patients with COPD. The principal hypothesis was that decreasing lung inflammation via inhibition of p38α would reduce exacerbations and improve quality of life for COPD patients at high risk for acute exacerbations.

Methods

The p38 isoform most relevant to lung inflammation was assessed using an in situ proximity ligation assay in severe COPD patients and donor controls. Volunteers aged 18–55 years were randomized into the lipopolysaccharide (LPS) challenge study, which investigated the effect of a single dose of AZD7624 vs placebo on inflammatory biomarkers. The Proof of Principle study randomized patients aged 40–85 years with a diagnosis of COPD for >1 year to AZD7624 or placebo to assess the effect of p38 inhibition in decreasing the rate of exacerbations.

Results

The p38 isoform most relevant to lung inflammation was p38α, and AZD7624 specifically inhibited p38α and p38β isoforms in human alveolar macrophages. Thirty volunteers were randomized in the LPS challenge study. AZD7624 reduced the increase from baseline in sputum neutrophils and TNF-α by 56.6% and 85.4%, respectively (p<0.001). In the 213 patients randomized into the Proof of Principle study, there was no statistically significant difference between AZD7624 and placebo when comparing the number of days to the first moderate or severe exacerbation or early dropout.

Conclusion

Although p38α is upregulated in the lungs of COPD patients, AZD7624, an isoform-specific inhaled p38 MAPK inhibitor, failed to show any benefit in patients with COPD.

Realising the potential of various inhaled airway challenge agents through improved delivery to the lungs

Inhaled airway challenges provoke bronchoconstriction in susceptible subjects and are a pivotal tool in the diagnosis and monitoring of obstructive lung diseases, both in the clinic and in the development of new respiratory medicines. This article reviews the main challenge agents that are in use today (methacholine, mannitol, adenosine, allergens, endotoxin) and emphasises the importance of controlling how these agents are administered. There is a danger that the optimal value of these challenge agents may not be realised due to suboptimal inhaled delivery; thus considerations for effective and reproducible challenge delivery are provided. This article seeks to increase awareness of the importance of precise delivery of inhaled agents used to challenge the airways for diagnosis and research, and is intended as a stepping stone towards much-needed standardisation and harmonisation in the administration of inhaled airway challenge agents.

Steroid sparing effects of doxofylline

Glucocorticosteroids are widely used in the treatment of asthma and chronic obstructive pulmonary disease (COPD). However, there are growing concerns about the side effect profile of this class of drug, particularly an increased risk of pneumonia. Over the last two decades there have been many attempts to find drugs to allow a reduction of glucocorticosteroids, including xanthines such as theophylline. Use of xanthines has been shown to lead to a reduction in the requirement for glucocorticosteroids, although xanthines also have a narrow therapeutic window limiting their wider use. Doxofylline is another xanthine that has been shown to be of clinical benefit in patients with asthma or COPD, but to have a wider therapeutic window than theophylline. In the present study we have demonstrated that doxofylline produces a clear steroid sparing effect in both an allergic and a non-allergic model of lung inflammation. Thus, we have shown that concomitant treatment with a low dose of doxofylline and a low dose of the glucocorticosteroid dexamethasone (that alone had no effect) significantly reduced both allergen-induced eosinophil infiltration into the lungs of allergic mice, and lipopolysaccharide (LPS)-induced neutrophil infiltration into the lung, equivalent to a higher dose of each drug. Our results suggest that doxofylline demonstrates significant anti-inflammatory activity in the lung which can result in significant steroid sparing activity.

Evaluation of New Drugs for Asthma and COPD: Endpoints, Biomarkers and Clinical Trial Design

There remains a considerable need to develop novel therapies for patients with asthma and chronic obstructive pulmonary disease (COPD). The greatest challenge at the moment is measuring the effects of novel anti-inflammatory drugs, as these drugs often cause only small effects on lung function. Measurements that demonstrate the pharmacological and clinical effects of these drugs are needed. Furthermore, we now recognise that only subgroups of patients are likely to respond to these novel drugs, so using biomarkers to determine the clinical phenotype most suitable for such therapies is important. An endotype is a subtype of a (clinical) condition defined by a distinct pathophysiological mechanism. An endotype-driven approach may be more helpful in drug development, enabling drugs to be targeted specifically towards specific biological mechanisms rather than clinical characteristics. This requires the development of biomarkers to define endotypes and/or to measure drug effects. This newer approach should continue alongside efforts to optimise the measurement of clinical endpoints, including patient-reported outcome measurements, required by drug regulatory authorities.

Pulmonary Surfactant and Bacterial Lipopolysaccharide: The Interaction and its Functional Consequences

The respiratory system is constantly exposed to pathogens which enter the lungs by inhalation or via blood stream. Lipopolysaccharide (LPS), also named endotoxin, can reach the airspaces as the major component of the outer membrane of Gram-negative bacteria, and lead to local inflammation and systemic toxicity. LPS affects alveolar type II (ATII) cells and pulmonary surfactant and although surfactant molecule has the effective protective mechanisms, excessive amount of LPS interacts with surfactant film and leads to its inactivation. From immunological point of view, surfactant specific proteins (SPs) SP-A and SP-D are best characterized, however, there is increasing evidence on the involvement of SP-B and SP-C and certain phospholipids in immune reactions. In animal models, the instillation of LPS to the respiratory system induces acute lung injury (ALI). It is of clinical importance that endotoxin-induced lung injury can be favorably influenced by intratracheal instillation of exogenous surfactant. The beneficial effect of this treatment was confirmed for both natural porcine and synthetic surfactants. It is believed that the surfactant preparations have anti-inflammatory properties through regulating cytokine production by inflammatory cells. The mechanism by which LPS interferes with ATII cells and surfactant layer, and its consequences are discussed below.

Inflammation induced by inhaled lipopolysaccharide depends on particle size in healthy volunteers

AIMS

In drug development, the anti-inflammatory properties of new molecules in the lung are currently tested using the inhaled lipopolysaccharide (LPS) model. The total and regional lung bioavailability of inhaled particles depends significantly on their size. The objective of the present study was to compare inflammatory responses in healthy volunteers after the inhalation of LPS of varying droplet size.

METHODS

Three nebulizers were characterized by different droplet size distributions [mean mass median aerodynamic diameters: Microcirrus (2.0 μm), MB2 (3.2 μm) and Pari (7.9 μm)]. Participants inhaled three boluses of a 20 μg (technetium 99 m-labelled) solution of LPS, randomly delivered by each nebulizer. We measured the lung deposition of the nebulized LPS by gamma-scintigraphy, while blood and sputum biomarkers were evaluated before and after challenges.

RESULTS

MB2 and Pari achieved greater lung deposition than Microcirrus [171.5 (±72.9) and 217.6 (±97.8) counts pixel^-1 , respectively, vs. 67.9 (±20.6) counts pixel^-1 ; P < 0.01]. MB2 and Pari caused higher levels of blood C-reactive protein and more total cells and neutrophils in sputum compared with Microcirrus (P < 0.05). C-reactive protein levels correlated positively with lung deposition (P < 0.01).

CONCLUSIONS

Inhalation of large droplets of LPS gave rise to greater lung deposition and induced a more pronounced systemic and bronchial inflammatory response than small droplets. The systemic inflammatory response correlated with lung deposition. NCT01081392.

Mixed exposure to bacterial lipopolysaccharide and seafood proteases augments inflammatory signalling in an airway epithelial cell model (A549)

Seafood industry workers exhibit increased prevalence of respiratory symptoms due to exposure to bioaerosols containing a mixture of bioactive agents. In this study, a human pulmonary epithelial cell model (A549) was exposed to mixtures of bacterial lipopolysaccharide (LPS) and protease-activated receptor-2 (PAR-2) agonists H-Ser-Leu-Ile-Gly-Lys-Val-NH₂ (SLIGKV-NH₂), purified salmon ( Salmo salar) trypsin or purified king crab ( Paralithodes camtschaticus) trypsin. The inflammatory response was measured based on nuclear factor-kappa B (NF-κB) activation of transcription in a luciferase reporter gene assay and interleukin 8 (IL-8) secretion in an enzyme-linked immunosorbent assay. We observed that mixtures of SLIGKV-NH₂ or trypsins with LPS augmented the activation of NF-κB and secretion of IL-8. The effect on IL-8 secretion was synergistic when both trypsins and LPS were used in the lower concentration range. The results demonstrate that exposure to mixtures of agents that are relevant to seafood industry workplaces may lead to increased inflammatory signalling compared with exposure to the individual agents alone. Furthermore, the results indicate that synergism may occur with the combined exposure to seafood trypsins and LPS and is most likely to occur when exposure to either agent is low.

Characterization of the inflammatory response to inhaled lipopolysaccharide in mild to moderate chronic obstructive pulmonary disease

AIMS

Lipopolysaccharide (LPS) inhalation causes increased airway and systemic inflammation. We investigated LPS inhalation in patients with chronic obstructive pulmonary disease (COPD) as a model of bacterial exacerbations. We studied safety, changes in sputum and systemic biomarkers. We have also investigated interleukin (IL)-17 concentrations in this model.

METHODS

Twelve COPD patients inhaled 5 μg LPS. Safety was monitored over 24 h. Sputum was induced at baseline, 6 and 24 h for cells and IL-8, IL-17, neutrophil elastase, monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1β (MIP-1β) in supernatants. Serum was collected at baseline, 4, 8 and 24 h for IL-6, C-reactive protein (CRP) and Clara cell protein (CC-16) concentrations. Peripheral blood mononuclear cells (PBMCs) were isolated at baseline and 4 h for systemic IL-17 analysis.

RESULTS

LPS 5 μg was well tolerated. The greatest FEV1 change was 11.7% (mean) at 1 h (95% CI 5.1-18.2%). There was a large range in maximal fall (2.5-37.7%). Total sputum cell count and neutrophil count significantly increased 6 and 24 h post-LPS. There was no change in sputum supernatant mediators. IL-6, CRP and CC-16 increased post-inhalation, with different temporal patterns. CD4+ and CD8+ cell associated IL-17 significantly increased at 4 h.

CONCLUSIONS

Inhaled LPS in COPD patients safely causes increased airway and systemic inflammation. This may be a model for studying COPD exacerbations.

Dissociation between systemic and pulmonary anti-inflammatory effects of dexamethasone in humans

Aims

The local pulmonary inflammatory response has a different temporal and qualitative profile compared with the systemic inflammatory response. Although glucocorticoids substantially downregulate the systemic release of acute‐phase mediators, it is not clear whether they have comparable inhibitory effects in the human lung compartment. Therefore, we compared the anti‐inflammatory effects of a pure glucocorticoid agonist, dexamethasone, on bronchoalveolar lavage and blood cytokine concentrations in response to bronchially instilled endotoxin.

Methods

In this randomized, double‐blind and placebo‐controlled trial, 24 volunteers received dexamethasone or placebo and had endotoxin instilled into a lung segment and saline instilled into a contralateral segment, followed by bronchoalveolar lavage.

Results

Bronchially instilled endotoxin induced a local and systemic inflammatory response. Dexamethasone strongly blunted the systemic interleukin (IL) 6 and C‐reactive protein release. In sharp contrast, dexamethasone left the local release of acute‐phase mediators in the lungs virtually unchanged: bronchoalveolar lavage levels of IL‐6 were only 18% lower and levels of IL‐8 were even higher with dexamethasone compared with placebo, although the differences between treatments were not statistically significant (P = 0.07 and P = 0.08, respectively). However, dexamethasone had inhibitory effects on pulmonary protein extravasation and neutrophil migration.

Conclusions

The present study demonstrated a remarkable dissociation between the systemic anti‐inflammatory effects of glucocorticoids and its protective effects on capillary leak on the one hand and surprisingly low anti‐inflammatory effects in the lungs on the other.

Inter- and intrasubject variability of the inflammatory response to segmental endotoxin challenge in healthy volunteers

Segmental endotoxin challenge with lipopolysaccharide (LPS) can be used as a pharmacodynamic model to safely induce a transient airway inflammation in the peripheral lung of healthy subjects and to test the anti-inflammatory efficacy of investigational new drugs. In contrast to whole lung LPS challenge only a fraction of the dose is required that can be precisely administered to a specific lung region and a vehicle challenged segment as an intra-subject control can be included. The aim of this study was to assess the intra- and inter-individual variability of the response to segmental LPS challenge for the appropriate design and power calculation of future clinical trials. Two cohorts with 10 subjects each underwent two segmental LPS challenges within five weeks. The inflammatory response was evaluated in bronchoalveolar lavage (BAL) fluid at 6 (cohort 1) and 24 h (cohort 2) both in the LPS and in a vehicle challenged segment, as well as in plasma for up to 26 h post LPS challenge. While the cytokine response was more pronounced at 6 h, the influx of neutrophils and monocytes dominated at 24 h; e.g. neutrophils increased from a median (inter-quartile range, IQR) of 0.14 (0.16) and 0.09 (0.08)x10(4) cells/mL BAL fluid at baseline to 10.2 (17.1) and 19.3 (15.9)x10(4) cells/mL 24 h after the two separate challenges. The within-subject variability was higher than the between-subject variability for most of the markers. However, sample size estimations based on the variability of outcome variables found lower or equal numbers with cross-over designs compared to parallel group designs for cellular markers at 24 h and cytokine variables at 6 h. The segmental LPS challenge model was safe. Future study designs have to balance between burden to the study subjects (4 versus 2 bronchoscopies), variability (within-versus between-subject), and the desired outcome variable (cells versus chemo/cytokine).

Indoor and outdoor exposure to ultrafine, fine and microbiologically derived particulate matter related to cardiovascular and respiratory effects in a panel of elderly urban citizens

To explore associations of exposure to ambient and indoor air particulate and bio-aerosol pollutants with cardiovascular and respiratory disease markers, we utilized seven repeated measurements from 48 elderly subjects participating in a 4-week home air filtration study. Microvascular function (MVF), lung function, blood leukocyte counts, monocyte adhesion molecule expression, C-reactive protein, Clara cell protein (CC16) and surfactant protein-D (SPD) were examined in relation to exposure preceding each measurement. Exposure assessment included 48-h urban background monitoring of PM10, PM2.5 and particle number concentration (PNC), weekly measurements of PM2.5 in living- and bedroom, 24-h measurements of indoor PNC three times, and bio-aerosol components in settled dust on a 2-week basis. Statistically significant inverse associations included: MVF with outdoor PNC; granulocyte counts with PM2.5; CD31 expression with dust fungi; SPD with dust endotoxin. Significant positive associations included: MVF with dust bacteria; monocyte expression of CD11 with PM2.5 in the bedroom and dust bacteria and endotoxin, CD31 expression with dust serine protease; serum CC16 with dust NAGase. Multiple comparisons demand cautious interpretation of results, which suggest that outdoor PNC have adverse effects on MVF, and outdoor and indoor PM2.5 and bio-aerosols are associated with markers of inflammation and lung cell integrity.

Surfactant protein D, Club cell protein 16, Pulmonary and activation-regulated chemokine, C-reactive protein, and Fibrinogen biomarker variation in chronic obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is a multifaceted condition that cannot be fully described by the severity of airway obstruction. The limitations of spirometry and clinical history have prompted researchers to investigate a multitude of surrogate biomarkers of disease for the assessment of patients, prediction of risk, and guidance of treatment. The aim of this review is to provide a comprehensive summary of observations for a selection of recently investigated pulmonary inflammatory biomarkers (Surfactant protein D (SP-D), Club cell protein 16 (CC-16), and Pulmonary and activation-regulated chemokine (PARC/CCL-18)) and systemic inflammatory biomarkers (C-reactive protein (CRP) and fibrinogen) with COPD. The relevance of these biomarkers for COPD is discussed in terms of their biological plausibility, their independent association to disease and hard clinical outcomes, their modification by interventions, and whether changes in clinical outcomes are reflected by changes in the biomarker.

Anti-TNF inhibits the airways neutrophilic inflammation induced by inhaled endotoxin in human

BACKGROUND

Inhaled endotoxin induces airways'neutrophilia, in human. TNF-a being a key cytokine in the response to endotoxin, the effect of anti-TNF on the endotoxin-induced neutrophilic response was evaluated among healthy volunteers.

METHODS

Among a population of 30 healthy subjects, an induced-sputum was collected 2 weeks before, and 24 hours after an inhalation of 20 mcg endotoxin (E. coli 026:B6). Then, the subjects were randomized into 3 parallel groups treated with control, oral methylprednisolone 20 mg/day during 7 days or anti-TNF (adalimumab, Humira®, Abbott) 40 mg s.c.. One week later, an induced-sputum was sampled, 24 hours after an inhalation of endotoxin.

RESULTS

After endotoxin inhalation, the number of total cells, neutrophils and macrophages was significantly increased (p <0.001). Compared to the response to endotoxin among the control group, anti-TNF inhibited the endotoxin-induced neutrophil influx, both in relative (51.3 (±6.4)% versus 26.2 (±5.3)%, p <0.002) and in absolute values (1321 (443-3935) cells/mcL versus 247 (68-906) cells/mcL, p <0.02). The endotoxin-induced neutrophilic response was not significantly modified among the control group and oral corticosteroid group.

CONCLUSIONS

While oral corticosteroid had no effect, anti-TNF inhibited the neutrophil influx in sputum, induced by inhalation of endotoxin, in human subject. The endotoxin model could be an early predictor of clinical efficacy of novel therapeutics.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02252809 (EudraCT2008-005526-37).

Factors influencing the measurement of plasma/serum surfactant protein D levels by ELISA

Background

Extensive variations in human surfactant protein D (SP-D) levels in circulation as measured by ELISA exist in the published literature. In order to determine the source of these variations, factors influencing the measurement by ELISA were explored.

Materials and Methods

Peripheral blood from healthy individuals was collected into various vacutainers during the same blood draw. Recombinant SP-D was diluted into different matrices and used for a standard curve. Samples were analyzed by capture ELISA using one of two distinct detection antibodies.

Results

The type of matrix had some effects on detection of recombinant SP-D. The type of anticoagulant used and dilution factor had very little effect, except for in plasma collected in EDTA vacutainers. The extent of variation in published values seemed to be due to the ELISA configuration employed, and, in agreement with this, we found that by switching the detection antibody, there was a 50% decrease in the extrapolated SP-D value of serum and plasma samples. Storage of samples resulted in slight changes in measured SP-D levels.

Conclusions

The ELISA configuration employed to measure circulating levels of SP-D has a significant effect on the extrapolated values. In both configurations tested, the use of EDTA as a coagulant resulted in inconsistent values, and we, therefore, suggest the avoidance of this anticoagulant when assaying for SP-D by ELISA. While the demonstrated effects of several factors on measurement of SP-D may not account for all the disparities amongst the previous studies, they stress that variations in methodologies for measuring the same protein can result in very inconsistent results.

Efficacy and safety of RPL554, a dual PDE3 and PDE4 inhibitor, in healthy volunteers and in patients with asthma or chronic obstructive pulmonary disease: findings from four clinical trials

BACKGROUND

Many patients with asthma or chronic obstructive pulmonary disease (COPD) routinely receive a combination of an inhaled bronchodilator and anti-inflammatory glucocorticosteroid, but those with severe disease often respond poorly to these classes of drug. We assessed the efficacy and safety of a novel inhaled dual phosphodiesterase 3 (PDE3) and PDE4 inhibitor, RPL554 for its ability to act as a bronchodilator and anti-inflammatory drug.

METHODS

Between February, 2009, and January, 2013, we undertook four proof-of-concept clinical trials in the Netherlands, Italy, and the UK. Nebulised RPL554 was examined in study 1 for safety in 18 healthy men who were randomly assigned (1:1:1) to receive an inhaled dose of RPL554 (0·003 mg/kg or 0·009 mg/kg) or placebo by a computer-generated randomisation table. Subsequently, six non-smoking men with mild allergic asthma received single doses of RPL554 (three received 0·009 mg/kg and three received 0·018 mg/kg) in an open-label, adaptive study, and then ten men with mild allergic asthma were randomly assigned to receive placebo or RPL554 (0·018 mg/kg) by a computer-generated randomisation table for an assessment of safety, bronchodilation, and bronchoprotection. Study 2 examined the reproducibility of the bronchodilator response to a daily dose of nebulised RPL554 (0·018 mg/kg) for 6 consecutive days in a single-blind (patients masked), placebo-controlled study in 12 men with clinically stable asthma. The safety and bronchodilator effect of RPL554 (0·018 mg/kg) was assessed in study 3, an open-label, placebo-controlled crossover trial, in 12 men with mild-to-moderate COPD. In study 4, a placebo-controlled crossover trial, the effect of RPL554 (0·018 mg/kg) on lipopolysaccharide-induced inflammatory cell infiltration in induced sputum was investigated in 21 healthy men. In studies 3 and 4, randomisation was done by computer-generated permutation with a block size of two for study 3 and four for study 4. Unless otherwise stated, participants and clinicians were masked to treatment assignment. Analyses were by intention to treat. All trials were registered with EudraCT, numbers 2008-005048-17, 2011-001698-22, 2010-023573-18, and 2012-000742-34.

FINDINGS

Safety was a primary endpoint of studies 1 and 3 and a secondary endpoint of studies 2 and 4. Overall, RPL554 was well tolerated, and adverse events were generally mild and of equal frequency between placebo and active treatment groups. Efficacy was a primary endpoint of study 2 and a secondary endpoint of studies 1 and 3. Study 1 measured change in forced expiratory volume in 1 s (FEV1) and provocative concentration of methacholine causing a 20% fall in FEV1 (PC20MCh) in participants with asthma. RPL554 produced rapid bronchodilation in patients with asthma with an FEV1 increase at 1 h of 520 mL (95% CI 320-720; p<0·0001), which was a 14% increase from placebo, and increased the PC20MCh by 1·5 doubling doses (95% CI 0·63-2·28; p=0·004) compared with placebo. The primary endpoint of study 2 was maximum FEV1 reached during 6 h after dosing with RPL554 in patients with asthma. RPL554 produced a similar maximum mean increase in FEV1 from placebo on day 1 (555 mL, 95% CI 442-668), day 3 (505 mL, 392-618), and day 6 (485 mL, 371-598; overall p<0·0001). A secondary endpoint of study 3 (patients with COPD) was the increase from baseline in FEV1. RPL554 produced bronchodilation with a mean maximum FEV1 increase of 17·2% (SE 5·2). In healthy individuals (study 4), the primary endpoint was percentage change in neutrophil counts in induced sputum 6 h after lipopolysaccharide challenge. RPL554 (0·018 mg/kg) did not significantly reduce the percentage of neutrophils in sputum (80·3% in the RPL554 group vs 84·2% in the placebo group; difference -3·9%, 95% CI -9·4 to 1·6, p=0·15), since RPL554 significantly reduced neutrophils (p=0·002) and total cells (p=0·002) to a similar degree.

INTERPRETATION

In four exploratory studies, inhaled RPL554 is an effective and well tolerated bronchodilator, bronchoprotector, and anti-inflammatory drug and further studies will establish the full potential of this new drug for the treatment of patients with COPD or asthma.

FUNDING

Verona Pharma.

Lipopolysaccharide induces endoplasmic store Ca2+-dependent inflammatory responses in lung microvessels

The pulmonary microvasculature plays a critical role in endotoxin-induced acute lung injury. However, the relevant signaling remain unclear. Specifically the role of endothelial Ca²⁺ in the induction of endotoxin-mediated responses in lung microvessels remains undefined. Toward elucidating this, we used the isolated blood-perfused rat lung preparation. We loaded microvessels with the Ca²⁺ indicator, Fura 2 AM and then determined Ca²⁺ responses to infusions of lipopolysaccharide (LPS) into the microvessels. LPS induced a more than two-fold increase in the amplitude of cytosolic Ca²⁺ oscillations. Inhibiting inositol 1,4,5 trisphosphate receptors on endoplasmic reticulum (ER) Ca²⁺ stores with Xestospongin C (XeC), blocked the LPS-induced increase in the Ca²⁺ oscillation amplitude. However, XeC did not affect entry of external Ca²⁺ via plasma membrane Ca²⁺ channels in lung microvascular endothelial cells. This suggested that LPS augmented the oscillations via release of Ca²⁺ from ER stores. In addition, XeC also blocked LPS-mediated activation and nuclear translocation of nuclear factor-kappa B in lung microvessels. Further, inhibiting ER Ca²⁺ release blunted increases in intercellular adhesion molecule-1 expression and retention of naïve leukocytes in LPS-treated microvessels. Taken together, the data suggest that LPS-mediated Ca²⁺ release from ER stores underlies nuclear factor-kappa B activation and downstream inflammatory signaling in lung microvessels. Thus, we show for the first time a role for inositol 1,4,5 trisphosphate-mediated ER Ca²⁺ release in the induction of LPS responses in pulmonary microvascular endothelium. Mechanisms that blunt this signaling may mitigate endotoxin-induced morbidity.

Low-dose endotoxin inhalation in healthy volunteers--a challenge model for early clinical drug development

BACKGROUND

Inhalation of endotoxin (LPS) induces a predominantly neutrophilic airway inflammation and has been used as model to test the anti-inflammatory activity of novel drugs. In the past, a dose exceeding 15-50 μg was generally needed to induce a sufficient inflammatory response. For human studies, regulatory authorities in some countries now request the use of GMP-grade LPS, which is of limited availability. It was therefore the aim of this study to test the effect and reproducibility of a low-dose LPS challenge (20,000 E.U.; 2 μg) using a flow- and volume-controlled inhalation technique to increase LPS deposition.

METHODS

Two to four weeks after a baseline sputum induction, 12 non-smoking healthy volunteers inhaled LPS on three occasions, separated by at least 4 weeks. To modulate the inflammatory effect of LPS, a 5-day PDE4 inhibitor (Roflumilast) treatment preceded the last challenge. Six hours after each LPS inhalation, sputum induction was performed.

RESULTS

The low-dose LPS inhalation was well tolerated and increased the mean percentage of sputum neutrophils from 25% to 72%. After the second LPS challenge, 62% neutrophils and an increased percentage of monocytes were observed. The LPS induced influx of neutrophils and the cumulative inflammatory response compared with baseline were reproducible. Treatment with Roflumilast for 5 days did not have a significant effect on sputum composition.

CONCLUSION

The controlled inhalation of 2 μg GMP-grade LPS is sufficient to induce a significant neutrophilic airway inflammation in healthy volunteers. Repeated low-dose LPS challenges potentially result in a small shift of the neutrophil/monocyte ratio; however, the cumulative response is reproducible, enabling the use of this model for "proof-of-concept" studies for anti-inflammatory compounds during early drug development.