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

Maximizing the Therapeutic Effect of Endothelin Receptor Antagonists in Pulmonary Fibrosis: A Paradigm for Treating the Disease

Using a lipopolysaccharide model of acute lung injury, we previously showed that endothelin-1 (ET-1), a potent mediator of vasoconstriction, may act as a "gatekeeper" for the influx of inflammatory cells into the lung. These studies provided a rationale for testing the effect of HJP272, an endothelin receptor antagonist (ERA), in hamster models of pulmonary fibrosis induced by intratracheal instillation of either bleomycin (BLM) or amiodarone (AM). To determine the temporal effects of blocking ET-1 activity, animals were given HJP272 either 1 h before initiation of lung injury or 24 h afterward. The results indicated that pretreatment with this agent caused significant reductions in various inflammatory parameters, whereas post-treatment was ineffective. This finding suggests that ERAs are only effective at a very early stage of pulmonary fibrosis and explains their lack of success in clinical trials involving patients with this disease. Nevertheless, ERAs could serve as prophylactic agents when combined with drugs that may induce pulmonary fibrosis. Furthermore, developing a biomarker for the initial changes in the lung extracellular matrix could increase the efficacy of ERAs and other therapeutic agents in preventing the progression of the disease. While no such biomarker currently exists, we propose the ratio of free to peptide-bound desmosine, a unique crosslink of elastin, as a potential candidate for detecting the earliest modifications in lung microarchitecture associated with pulmonary fibrosis.

Desmosine as a biomarker for the emergent properties of pulmonary emphysema

Developing an effective treatment for pulmonary emphysema will require a better understanding of the molecular changes responsible for distention and rupture of alveolar walls. A potentially useful approach to studying this process involves the concept of emergence in which interactions at different levels of scale induce a phase transition comprising a spontaneous reorganization of chemical and physical systems. Recent studies in our laboratory provide evidence of this phenomenon in pulmonary emphysema by relating the emergence of airspace enlargement to the release of elastin-specific desmosine and isodesmosine (DID) crosslinks from damaged elastic fibers. When the mean alveolar diameter exceeded 400 μm, the level of peptide-free DID in human lungs was greatly increased, reflecting rapid acceleration of elastin breakdown, alveolar wall rupture, and a phase transition to an active disease state that is less responsive to treatment. Based on this finding, it is hypothesized that free DID in urine and other body fluids may serve as a biomarker for early detection of airspace enlargement, thereby facilitating timely therapeutic intervention and reducing the risk of respiratory failure.

Evaluating Novel Protein Phosphatase 2A Activators as Therapeutics for Emphysema

The activity of PP2A (protein phosphatase 2A), a serine-threonine phosphatase, is reduced by chronic cigarette smoke (SM) exposure and α-1 antitrypsin (AAT) deficiency, and chemical activation of PP2A reduces the loss of lung function in SM-exposed mice. However, the previously studied PP2A-activator tricyclic sulfonamide compound DBK-1154 has low stability to oxidative metabolism, resulting in fast clearance and low systemic exposure. Here we compare the utility of a new more stable PP2A activator, ATUX-792, versus DBK-1154 for the treatment of SM-induced emphysema. ATUX-792 was also tested in human bronchial epithelial cells and a mouse model of AAT deficiency, Serpina1a-e-knockout mice. Human bronchial epithelial cells were treated with ATUX-792 or DBK-1154, and cell viability, PP2A activity, and MAP (mitogen-activated protein) kinase phosphorylation status were examined. Wild-type mice received vehicle, DBK-1154, or ATUX-792 orally in the last 2 months of 4 months of SM exposure, and 8-month-old Serpina1a-e-knockout mice received ATUX-792 daily for 4 months. Forced oscillation and expiratory measurements and histology analysis were performed. Treatment with ATUX-792 or DBK-1154 resulted in PP2A activation, reduced MAP kinase phosphorylation, immune cell infiltration, reduced airspace enlargements, and preserved lung function. Using protein arrays and multiplex assays, PP2A activation was observed to reduce AAT-deficient and SM-induced release of CXCL5, CCL17, and CXCL16 into the airways, which coincided with reduced neutrophil lung infiltration. Our study indicates that suppression of the PP2A activity in two models of emphysema could be restored by next-generation PP2A activators to impact lung function.

The relationship between elastin cross linking and alveolar wall rupture in human pulmonary emphysema

To better define the role of mechanical forces in pulmonary emphysema, we employed methods recently developed in our laboratory to identify microscopic level relationships between airspace size and elastin-specific desmosine and isodesmosine (DID) cross links in normal and emphysematous human lungs. Free DID in wet tissue (a biomarker for elastin degradation) and total DID in formalin-fixed, paraffin-embedded (FFPE) tissue sections were measured using liquid chromatography-tandem mass spectrometry and correlated with alveolar diameter, as determined by the mean linear intercept (MLI) method. There was a positive correlation between free lung DID and MLI (P < 0.0001) in formalin-fixed lungs, and elastin breakdown was greatly accelerated when airspace diameter exceeded 400 µm. In FFPE tissue, DID density was markedly increased beyond 300 µm (P < 0.0001) and leveled off around 400 µm. Elastic fiber surface area similarly peaked at around 400 µm, but to a much lesser extent than DID density, indicating that elastin cross linking is markedly increased in response to early changes in airspace size. These findings support the hypothesis that airspace enlargement is an emergent phenomenon in which initial proliferation of DID cross links to counteract alveolar wall distention is followed by a phase transition involving rapid acceleration of elastin breakdown, alveolar wall rupture, and progression to an active disease state that is less amenable to therapeutic intervention.NEW & NOTEWORTHY The current findings support the hypothesis that airspace enlargement is an emergent phenomenon in which initial proliferation of DID cross links to counteract alveolar wall distention is followed by a phase transition involving rapid acceleration of elastin breakdown, alveolar wall rupture, and progression to an active disease state that is less amenable to therapeutic intervention.

Performance and biocompatibility of a novel inhalable dry powder formulation based on hyaluronic acid intended to protect the respiratory tract mucosa

Hyaluronic acid (HA) is a key component of the respiratory mucosa. By acting as a natural moisturizer, it provides hydration to the airways. In normal conditions, high molecular weight HA molecules form viscous gels providing a protective shield against external insults. This is particularly important in the upper airways where the HA protective barrier helps to prevent environmental agents to reach the lungs. Most respiratory diseases are characterized by inflammatory processes causing degradation of HA into small fragments which reduces the HA barrier effect and increases the risk of exposure to external insults. Dry powder inhalers (DPIs) are efficient devices used to deliver therapeutic molecules in the form of dry powder to the respiratory tract. PolmonYDEFENCE/DYFESA™ is a novel formulation based on HA delivered to the airways using the PillHaler® DPI device. In this study we report the results of in vitro inhalation performances of PolmonYDEFENCE/DYFESA™ as well as its mechanism of action in human cells. We found that the product targets the upper airways and that HA molecules form a protective barrier on cell surface. Furthermore, exposure to the device is safe in animal models. The promising pre-clinical results of this study provide the bases for future clinical investigation.