Cigarette smoke exposure & ebselen treatment
Mice were placed into an 18-litre Perspex chamber (The Plastic Man,
Huntingdale, Victoria, Australia) in a standard fume cabinet (Aircare
Extraction Systems LTD, Clayton, Victoria, Australia) and exposed to
cigarette smoke generated from 9 Winfield Red Cigarettes (total
particulate matter of 419 mg m-3, 16 mg or less of
tar, 1.2 mg or less of nicotine and 15 mg or less of CO, Philip Morris,
Moorabbin, Australia) for 5 days a week for 8 weeks. Mice were exposed
to CS delivered 3 times per day with 3 cigarettes delivered at 9 AM, 12
noon and 3 PM, over a 1h time-period. CS was generated in 60 mL tidal
volumes over 10 s, via a timed draw-back to mimic normal smoking
inhalation and burn rates. We have previously shown that this CS
exposure protocol in Balb/C mice replicates key clinical traits of early
stage COPD in humans, including lung inflammation and pathology (mucous
hypersecretion and impaired lung function), increased lung and systemic
oxidative stress and comorbidities including skeletal muscle wasting
(Austin, Crack, Bozinovski, Miller & Vlahos, 2016; Chan et al., 2019;
Vlahos & Bozinovski, 2014). Thus, this model provides a robust
clinically relevant platform to test therapies for COPD and its
comorbidities. Sham-exposed mice are placed into an identical 18-liter
Perspex chamber, but do not receive cigarette smoke. Mice were weighed
every second day (prior to initial CS exposure) up to and including the
day of cull. For the ebselen treatment studies, mice were administered
10 mg kg-1 of ebselen (Sapphire Bioscience, Australia)
prepared in 5% w/v CM-cellulose in water (Sigma-Aldrich, USA) or
vehicle treated with 5% CM-cellulose in water alone. Treatments were
administered via oral gavage once daily, 1h prior to the initial CS
exposure.