The Synergistic, Anti-Inflammatory Effects of Low-Dose Theophylline Plus Budesonide in an LPS-Induced Model of COPD

Ceri M. Davies1, William Ford1, Kenneth J. Broadley1, Elizabeth Hardaker2, Henry Danahay2, Emma Kidd1. 1Cardiff University, Division of Pharmacology, Welsh School of Pharmacy, Cardiff University, King Edward VII Avenue, Cardiff, CF10 3NB, UK, 2Novartis, Novartis Institue of Biomedical Research Horsham, Wimblehurst Road, Horsham, West Sussex, RH12 5AB, UK.

Chronic obstructive pulmonary disease (COPD) is predicted to be the third most common cause of mortality by 2020 (WHO, 2010). COPD exhibits resistance to high-dose steroid therapy (Alsaeedei et al, 2002) and recent research has focused on the beneficial effects of low-dose theophylline in up-regulating histone deacetylase (HDAC) activity and increasing steroid sensitivity in COPD (Cosio et al, 2004). This study examined whether low-dose theophylline increases the effectiveness of budesonide in a lipopolysaccharide (LPS)-induced guinea pig model of COPD

Guinea pigs (200-250g, Male, Dunkin Hartley, Charles River, N = 6) were exposed to nebulised LPS (30µg/ml) for 1 hour, every other day for nine exposures. Changes in specific airway conductance (sGaw) were measured in conscious guinea pigs by whole body plethysmography (Buxco Systems, USA) for 4 hours after exposures 1, 5 and 9 and compared to baseline readings. Budesonide (0.6 mg/ml) was nebulised for 15 minutes every day for 6 days and theophylline (5, 50 mg/kg) was administered orally twice a day for 6 days before LPS exposure on day 9. Theophylline was administered 30 minutes before budesonide was administered. Animals were killed 24 hours after the ninth exposure and a bronchoalveolar lavage was performed to determine inflammatory cell influx. Acute responses to theophylline were determined with a bronchoconstrictive dose of histamine (0.7mM). Theophylline (50, 5 mg/kg) was administered 30 minutes before receiving nebulised histamine. sGaw was measured at 0, 5 and 10 minutes after exposure and compared to baseline readings. Groups were statistically analysed using an unpaired t-test or ANOVA.

Animals challenged with LPS exhibited a significant decrease in airway function compared to saline challenged animals, expressed as area under the curve for the three recorded exposures (153.5±17.6 and 30.2±9.1% respectively, P<0.001). There was a significant (P<0.001) increase in total (2.2±0.2x107 and 2.2±0.2x106/ml), macrophage (1.1±0.1x107 and 1.8±0.2x106/ml), neutrophil (0.9±0.09x107 and 0.1±0.02x106/ml) and eosinophil (0.09±0.009x107 and 0.1±0.03x106/ml) numbers in LPS challenged animals compared to saline challenged animals. There was no significant difference in airway function or cell influx between LPS alone and LPS and vehicle-treated groups, nor when budesonide and theophylline (5, 50mg/kg) were compared with their respective vehicle controls. There was no significant difference in airway function when budesonide plus low-dose theophylline was compared to the control but there was a significant (p<0.01) reduction in total (2.4±0.2 x107 and 1.7±0.1x107/ml), neutrophil (1.1±0.083x107 and 0.7±0.03x107/ml) and lymphocyte (0.7±0.03 x106 and 0.4±0.06x106/ml) numbers. Theophylline 5mg/kg produced no significant reduction in bronchoconstriction to histamine, however, theophylline 50 mg/kg significantly reduced bronchoconstriction to histamine at 0 (-45.9±7.0 and 0.9±2.5%, P<0.001) and 5 minutes (-35.3±6 and -4.8±1.6%, P<0.01) Conclusion: Low-dose theophylline (5mg/kg) plus budesonide exhibits a synergistic, anti-inflammatory effect when combined, leading to a significant reduction in inflammation, suggesting an increase in the effectiveness of budesonide.

WHO (2010) World health organisation [online]http://www.who.int/mediacentre/factsheets/fs315/en/index.html

Alsaeedi et al (2002) The Am J Med. 113:59-65

Cosio et al (2004) J. Exp. Med. 200(5): 689-695.

This work was supported by a BBSRC/Novartis studentship to CMD