Effect of TRPV4 Antagonist GSK2798745 on Chlorine Gas-Induced Acute Lung Injury in a Swine Model.

As a regulator of alveolo-capillary barrier integrity, Transient Receptor Potential Vanilloid 4 (TRPV4) antagonism represents a promising strategy for reducing pulmonary edema secondary to chemical inhalation. In an experimental model of acute lung injury induced by exposure of anesthetized swine to chlorine gas by mechanical ventilation, the dose-dependent effects of TRPV4 inhibitor GSK2798745 were evaluated. Pulmonary function and oxygenation were measured hourly; airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, and histopathology were assessed 24 h post-exposure. Exposure to 240 parts per million (ppm) chlorine gas for ≥50 min resulted in acute lung injury characterized by sustained changes in the ratio of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen concentration (PaO2/FiO2), oxygenation index, peak inspiratory pressure, dynamic lung compliance, and respiratory system resistance over 24 h. Chlorine exposure also heightened airway response to methacholine and increased wet-to-dry lung weight ratios at 24 h. Following 55-min chlorine gas exposure, GSK2798745 marginally improved PaO2/FiO2, but did not impact lung function, airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, or histopathology. In summary, in this swine model of chlorine gas-induced acute lung injury, GSK2798745 did not demonstrate a clinically relevant improvement of key disease endpoints.

A Robust Pneumonia Model in Immunocompetent Rodents to Evaluate Antibacterial Efficacy against S. pneumoniae, H. influenzae, K. pneumoniae, P. aeruginosa or A. baumannii.

Efficacy of candidate antibacterial treatments must be demonstrated in animal models of infection as part of the discovery and development process, preferably in models which mimic the intended clinical indication. A method for inducing robust lung infections in immunocompetent rats and mice is described which allows for the assessment of treatments in a model of serious pneumonia caused by S. pneumoniae, H. influenzae, P. aeruginosa, K. pneumoniae or A. baumannii. Animals are anesthetized, and an agar-based inoculum is deposited deep into the lung via nonsurgical intratracheal intubation. The resulting infection is consistent, reproducible, and stable for at least 48 h and up to 96 h for most isolates. Studies with marketed antibacterials have demonstrated good correlation between in vivo efficacy and in vitro susceptibility, and concordance between pharmacokinetic/pharmacodynamic targets determined in this model and clinically accepted targets has been observed. Although there is an initial time investment when learning the technique, it can be performed quickly and efficiently once proficiency is achieved. Benefits of the model include elimination of the neutropenic requirement, increased robustness and reproducibility, ability to study more pathogens and isolates, improved flexibility in study design and establishment of a challenging infection in an immunocompetent host.