Lung hyaluronan levels are decreased in alpha-1 antiprotease deficiency COPD

A 28-day clinical trial of aerosolized hyaluronan in alpha-1 antiprotease deficiency COPD using desmosine as a surrogate marker for drug efficacy

INTRODUCTION

A previous 2-week clinical trial of aerosolized hyaluronan (HA) in COPD showed a rapid reduction in lung elastic fiber breakdown, as measured by sputum levels of the unique elastin crosslinks, desmosine and isodesmosine (DID). To further assess the therapeutic efficacy of HA and the utility of DID as surrogate markers for the development of pulmonary emphysema, we have conducted a 28-day randomized, double-blind, placebo-controlled, phase 2 trial of HA involving 27 subjects with alpha-1 antiprotease deficiency COPD.

METHODS

The study drug consisted of a 3 ml inhalation solution containing 0.03% HA with an average molecular weight of 150 kDa that was self-administered twice daily. DID levels were measured in urine, sputum, and plasma using tandem mass spectrometry.

RESULTS

Free urine DID in the HA group showed a significant negative correlation with time between days 14 and 35 (r = -1.0, p = 0.023) and was statistically significantly decreased from baseline at day 35 (15.4 vs 14.2 ng/mg creatinine, p = 0.035). A marked decrease in sputum DID was also seen in the HA group between days 1 and 28 (0.96 vs 0.18 ng/mg protein), but the difference was not significant, possibly due to the small number of adequate specimens. Plasma DID remained unchanged following HA treatment and no significant reductions in urine, sputum, or plasma DID were seen in the placebo group.

CONCLUSIONS

The results support additional clinical trials to further evaluate the therapeutic effect of HA and the use of DID as a real-time marker of drug efficacy.

Inhaled high molecular weight hyaluronan ameliorates respiratory failure in acute COPD exacerbation: a pilot study

Background

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) carry significant morbidity and mortality. AECOPD treatment remains limited. High molecular weight hyaluronan (HMW-HA) is a glycosaminoglycan sugar, which is a physiological constituent of the lung extracellular matrix and has notable anti-inflammatory and hydrating properties.

Research question

We hypothesized that inhaled HMW-HA will improve outcomes in AECOPD.

Methods

We conducted a single center, randomized, placebo-controlled, double-blind study to investigate the effect of inhaled HMW-HA in patients with severe AECOPD necessitating non-invasive positive-pressure ventilation (NIPPV). Primary endpoint was time until liberation from NIPPV.

Results

Out of 44 screened patients, 41 were included in the study (21 for placebo and 20 for HMW-HA). Patients treated with HMW-HA had significantly shorter duration of NIPPV. HMW-HA treated patients also had lower measured peak airway pressures on the ventilator and lower systemic inflammation markers after liberation from NIPPV. In vitro testing showed that HMW-HA significantly improved mucociliary transport in air–liquid interface cultures of primary bronchial cells from COPD patients and healthy primary cells exposed to cigarette smoke extract.

Interpretation

Inhaled HMW-HA shortens the duration of respiratory failure and need for non-invasive ventilation in patients with AECOPD. Beneficial effects of HMW-HA on mucociliary clearance and inflammation may account for some of the effects (NCT02674880, www.clinicaltrials.gov).

Use of Hyaluronic Acid (HA) in Chronic Airway Diseases

Hyaluronic acid (HA) is a key component of the extracellular matrix of the lungs. A unique attribute of HA is its water-retaining properties, so HA has a major role in the regulation of fluid balance in the lung interstitium. Hyaluronic acid has been widely used in the treatment of eyes, ears, joints and skin disorders, but in the last years, it has been also proposed in the treatment of certain lung diseases, including airway diseases, due to its anti-inflammatory and water-binding capacities. Hyaluronic acid aerosol decreases the severity of elastase-induced emphysema in murine models, prevents bronchoconstriction in asthmatics and improves some functional parameters in chronic obstructive pulmonary disease (COPD) patients. Due to the protection of HA against bronchoconstriction and its hydration properties, inhaled HA would increase the volume of airway surface liquid, resulting in mucus hydration, increased mucous transport and less mucous plugging of the airways. In addition, it has been seen in human studies that the treatment with nebulised HA improves the tolerability of nebulised hypertonic saline (even at 6% or 7% of concentration), which has been demonstrated to be an effective treatment in bronchial secretion management in patients with cystic fibrosis and bronchiectasis. Our objective is to review the role of HA treatment in the management of chronic airway diseases.

Experimental and investigational drugs for the treatment of alpha-1 antitrypsin deficiency

Introduction: Alpha-1 antitrypsin deficiency (AATD) is most often associated with chronic lung disease, early onset emphysema, and liver disease. The standard of care in lung disease due to AATD is alpha-1 antitrypsin augmentation but there are several new and emerging treatment options under investigation for both lung and liver manifestations. Areas covered: We review therapeutic approaches to lung and liver disease in alpha-1 antitrypsin deficiency (AATD) and the agents in clinical development according to their mode of action. The focus is on products in clinical trials, but data from pre-clinical studies are described where relevant, particularly where progression to trials appears likely. Expert opinion: Clinical trials directed at lung and liver disease separately are now taking place. Multimodality treatment may be the future, but this could be limited by treatment costs. The next 5-10 years may reveal new guidance on when to use therapeutics for slowing disease progression with personalized treatment regimes coming to the forefront.

COPD Pathogenesis: Finding the Common in the Complex

Developing an effective treatment for COPD, and especially pulmonary emphysema, will require an understanding of how fundamental changes at the molecular level affect the macroscopic structure of the lung. Currently, there is no accepted model that encompasses the biochemical and mechanical processes responsible for pulmonary airspace enlargement. We propose that pulmonary emphysematous changes may be more accurately described as an emergent phenomenon, involving alterations at the molecular level that eventually reach a critical structural threshold where uneven mechanical forces produce alveolar wall rupture, accompanied by advanced clinical signs of COPD. The coupling of emergent morphologic changes with biomarkers to detect the process, and counteract it therapeutically, represents a practical approach to the disease.

Chronic Obstructive Pulmonary Disease. A Biomarker and a Potential Therapy

This article assesses developments in cardiorespiratory medicine since the Nobel Prize in Physiology or Medicine was awarded in 1956 for advancements in the study of cardiorespiratory disease. In chronic obstructive pulmonary disease, advances were accelerated by the discovery of a genetically determined cause for pulmonary emphysema in the genetic abnormality alpha-1 antitrypsin deficiency. This causes a deficiency of the inhibitor of neutrophil elastase, which results in increased degradation of lung elastin and the development of pulmonary emphysema. This discovery gave focus to two amino acids that reside only in body elastin, desmosine and isodesmosine, which can be measured as biomarkers of elastin degradation in body fluids with increased accuracy and sensitivity. Studies of this biomarker have shown that augmentation therapy in alpha-1 antitrypsin deficiency does decrease lung and body elastic tissue degradation and in the RAPID (Randomized, Placebo-controlled Trial of Augmentation Therapy in Alpha-1 Proteinase Inhibitor Deficiency) Study, over 4 years, showed a preservation of lung density by computer tomography correlating with decreases in plasma levels of desmosine and isodesmosine. This insight indicates the potential of agents that prevent lung elastin degradation. Such an agent is hyaluronan aerosol, which is deficient in post mortem lungs with chronic obstructive pulmonary disease and has been shown to block elastin degradation, possibly by a barrier function. Thus it would appear that hyaluronan could have therapeutic potential in chronic obstructive pulmonary disease.

The Therapeutic Potential of Hyaluronan in COPD

Insights into the clinical course of COPD indicate the need for new therapies for this condition. The discovery of alpha-1 antitrypsin deficiency (AATD) led to the protease-antiprotease imbalance hypothesis, which was applied to COPD related to AATD as well as COPD not related to AATD. The discovery of AATD brought recognition to the importance of elastin fibers in maintaining lung matrix structure. Two cross-linking amino acids, desmosine and isodesmosine (DI), are unique to mature elastin and can serve as biomarkers of the degradation of elastin. The intravenous augmentation treatment and lung density in severe alpha-1 antitrypsin deficiency (RAPID) study shows a correlation of an anatomic index of COPD (on CT imaging) correlating with a chemical indicator of matrix injury in COPD, DI. The results suggest that preservation of lung elastin structure may slow the progression of COPD. Hyaluronan aerosol decreases the severity of elastase-induced emphysema in animals and has induced reductions in DI levels in preliminary human studies. Hyaluronan deserves further development as a therapy for COPD.

A pilot clinical trial to determine the safety and efficacy of aerosolized hyaluronan as a treatment for COPD

A novel therapy for COPD involving the use of aerosolized hyaluronan (HA) was tested on a small cohort of COPD patients to determine both its safety and efficacy in reducing levels of desmosine and isodesmosine (DID), biomarkers for elastin degradation. In a 2-week, randomized, double-blind trial, 8 patients receiving 150 kDa HA (mean molecular weight) and 3 others given placebo did not show significant adverse effects with regard to spirometry, electrocardiograms, and hematological indices. Furthermore, measurements of DID in plasma from HA-treated patients indicated a progressive decrease over a 3-week period following initiation of treatment (r=−0.98; p=0.02), whereas patients receiving placebo showed no reduction in DID (r=−0.70; p=0.30). Measurements of sputum in the HA-treated group also revealed a progressive decrease in DID (r=−0.97; p=0.03), but this finding was limited by the absence of similar measurements in the placebo group. Nevertheless, the results of this small, pilot study support a longer-term trial of HA in a larger population of COPD patients.

The Pattern of Elastic Fiber Breakdown in Bleomycin-Induced Pulmonary Fibrosis May Reflect Microarchitectural Changes

INTRODUCTION

Desmosine and isodesmosine (DID) are unique elastin crosslinks that may serve as biomarkers for elastic fiber degradation in chronic obstructive pulmonary disease. Previously, our laboratory found that the ratio of free to peptide-bound DID in bronchoalveolar lavage fluid (BALF) showed a significant positive correlation with the extent of airspace enlargement in an elastase model of pulmonary emphysema. To further evaluate this hypothesis, our laboratory measured this ratio in a bleomycin (BLM) model of pulmonary fibrosis, which involved different microarchitectural changes than those associated with pulmonary emphysema.

METHODS

Syrian hamsters were instilled intratracheally with 1.0 unit BLM in 0.2 ml of normal saline (controls received the vehicle alone), and BALF was analyzed for both free and total DID, using a combination of liquid chromatography and tandem mass spectrometry.

RESULTS

Total BALF DID was significantly increased in hamsters receiving BLM at 1 week post-treatment (92 vs 13 pg/ml; p < 0.001), consistent with elastic fiber degradation. However, in contrast to elastase-induced emphysema, free/bound DID was lower in BLM-treated animals compared to controls at both 1 week (0.76 vs 0.84) and 2 weeks post-treatment (0.69 vs 0.86), though the differences were not statistically significant.

CONCLUSIONS

These results indicate that it may be possible to identify specific pulmonary microarchitecture changes, based on the ratio of free to peptide-bound DID. It is speculated that the proportionate decrease in free DID in BLM-induced fibrosis may be due to preservation of intact elastic fibers as the lung injury progresses.

Hyaluronan as a therapeutic target in human diseases

Accumulation and turnover of extracellular matrix is a hallmark of tissue injury, repair and remodeling in human diseases. Hyaluronan is a major component of the extracellular matrix and plays an important role in regulating tissue injury and repair, and controlling disease outcomes. The function of hyaluronan depends on its size, location, and interactions with binding partners. While fragmented hyaluronan stimulates the expression of an array of genes by a variety of cell types regulating inflammatory responses and tissue repair, cell surface hyaluronan provides protection against tissue damage from the environment and promotes regeneration and repair. The interactions of hyaluronan and its binding proteins participate in the pathogenesis of many human diseases. Thus, targeting hyaluronan and its interactions with cells and proteins may provide new approaches to developing therapeutics for inflammatory and fibrosing diseases. This review focuses on the role of hyaluronan in biological and pathological processes, and as a potential therapeutic target in human diseases.

The role of hyaluronan in the pathobiology and treatment of respiratory disease

Hyaluronan, a ubiquitous naturally occurring glycosaminoglycan, is a major component of the extracellular matrix, where it participates in biological processes that include water homeostasis, cell-matrix signaling, tissue healing, inflammation, angiogenesis, and cell proliferation and migration. There are emerging data that hyaluronan and its degradation products have an important role in the pathobiology of the respiratory tract. We review the role of hyaluronan in respiratory diseases and present evidence from published literature and from clinical practice supporting hyaluronan as a novel treatment for respiratory diseases. Preliminary data show that aerosolized exogenous hyaluronan has beneficial activity against airway inflammation, protects against bronchial hyperreactivity and remodeling, and disrupts the biofilm associated with chronic infection. This suggests a role in airway diseases with a predominant inflammatory component such as rhinosinusitis, asthma, chronic obstructive pulmonary disease, cystic fibrosis, and primary ciliary dyskinesia. The potential for hyaluronan to complement conventional therapy will become clearer when data are available from controlled trials in larger patient populations.