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Different inhaled allergen challenge models give reproducible results
Pulmonary Pharmacology & Therapeutics 33 (2015) 57e58
Contents lists available at ScienceDirect
Pulmonary Pharmacology & Therapeutics journal homepage: www.elsevier.com/locate/ypupt
Different inhaled allergen challenge models give reproducible results
Keywords: Allergen challenge Asthma Inhaled corticosteroids Induced sputum
The inhaled allergen challenge model causes an early asthmatic response (EAR), followed by a late asthmatic response (LAR) characterised by an increase in eosinophilic airway inflammation. The inhaled allergen challenge model has been used to study novel anti-inflammatory drugs in clinical trials [1e3]. The two most commonly used inhaled allergen challenge models are (1) the incremental dose challenge, where incremental allergen doses are delivered by a breath-activated dosimeter until an EAR is observed [4e6] and (2) the tidal breathing challenge, where predicted concentrations of allergen are inhaled during tidal breathing for 2 min from a nebuliser until an EAR is observed [3,7,8]. Allergen challenge studies are usually conducted in patients who are not taking inhaled corticosteroids (ICS), as these drugs inhibit the LAR [7,8]. However, we have recently shown that incremental dose challenges cause an LAR in asthmatics using ICS [4]. This indicates the potential of allergen challenges to be used in this patient population. Here we report a comparison of the effects of the tidal breathing and incremental allergen challenge models in asthma patients using ICS, in order to determine whether different methodologies give similar results. Fourteen asthma patients taking ICS (<1000mcg/day beclomethasone dipropionate equivalent; mean ICS dose (SD) 396.4 (240.6) mcg) who had participated in our previous study [4] (10 male and 4 female, mean age 40, mean FEV1 % predicted 89.0%, mean baseline Asthma Control Questionnaire score 1.3, mean baseline exhaled nitric oxide level 58 ppb) underwent the tidal breathing challenge at 2e24 weeks after the incremental dose challenge. The allergen used for the allergen challenges were house dust mite in 10 patients, cat in 3 patients and grass mix in 1 patient. The reason for the long duration between challenges for some patients
was busy work and social schedules. Allergen challenges, sputum collection and processing were performed as previously described [2e4,9]. Baseline sputum was collected at least 5 days prior to the allergen challenge. Sputum was collected at 24 h post-allergen challenge. Written informed consent was obtained and the local research ethics committee approved the study. The EAR and LAR were expressed as the area under curve of percentage change in FEV1 during first 2 h ((AUC)0e2h) and from 4 to 10 h ((AUC)4e10h) respectively. The mean maximum fall in FEV1 during the EAR and LAR (max EAR and max LAR respectively) were also calculated. Agreement between the two challenges was determined by paired t-tests and BlandeAltman analysis (GraphPad software, San Diego, CA, USA). The within-subject standard deviation (SD) was calculated using the difference between the means and ANOVA (SPSS v22.0, Armonk, NY, USA). Sputum eosinophil % counts were parametrically distributed. Paired t-tests were used to compare baseline and post-challenge sputum eosinophil %, and to compare results between the challenge models. p < 0.05 was considered to be statistically significant. The differences between challenges are shown in Table 1. The mean EAR and LAR values were very similar (p > 0.05 for all comparisons of AUC and maximum fall). The BlandeAltman analysis also showed a relatively small mean bias for the EAR and LAR, although the 95% limits of agreement indicate that some individual results may vary greatly. The within-subject SD are shown, and may be used for future power calculations. The incremental dose method caused an increase in the mean sputum eosinophil %: baseline mean ¼ 0.94%, post challenge mean ¼ 6.95%, p < 0.01. Similar results were obtained for the tidal breathing method: baseline mean ¼ 0.64%, post challenge mean ¼ 4.98%, p < 0.01. There were no statistically significant differences in baseline and post-challenge sputum eosinophil % between both methods. We show that the incremental and tidal breathing challenge methods cause similar changes in lung function and sputum eosinophils in asthmatics taking ICS. Both allergen challenge methodologies cause similar allergic reactions in this patient group.
Abbreviations: AUC, area under curve; EAR, early asthmatic response; ICS, inhaled corticosteroids; LAR, late asthmatic response; SD, standard deviation. http://dx.doi.org/10.1016/j.pupt.2015.06.005 1094-5539/© 2015 Elsevier Ltd. All rights reserved.
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WY. Lee et al. / Pulmonary Pharmacology & Therapeutics 33 (2015) 57e58
Table 1 Comparison and reproducibility of the tidal breathing challenge and incremental dose challenge. Allergen challenge
EAR(AUC)0e2a DFEV1%.hr Max EAR(DFEV1%)0e2a LAR (AUC)4e10a DFEV1%.hr Max LAR(DFEV1%)4e10a
p value
Incremental dose
Tidal breathing
24.0 28.1 82.9 23.9
23.4 27.0 92.7 25.4
(±10.6) (±5.8) (±49.7) (±9.4)
(±12.1) (±8.5) (±75.3) (±12.3)
BlandeAltman analysis Mean difference (95% limits of agreement)
0.87 0.75 0.57 0.67
0.62 (27.25e28.50) 1.16 (24.37e26.69) 9.84 (133.50e113.80) 1.52 (27.15e24.11)
Within subject SD (calculated from difference of means)
Within subject SD (calculated from ANOVA)
14.2 13.0 63.1 13.1
9.6 8.6 42.3 8.7
a Parametric data presented as mean (standard deviation) and analysed using paired t-test. Agreement between measures of EAR and LAR, and the AUC for the allergen challenges is presented by BlandeAltman analysis.
Acknowledgements We would like to thank Julie Morris and Sigrid Whiteside for the statistical advice, and the Medicines Evaluation Unit for funding the study. References [1] D. Singh, F. Petavy, A.J. Macdonald, A.L. Lazaar, B.J. O'Connor, The inhaled phosphodiesterase 4 inhibitor GSK256066 reduces allergen challenge responses in asthma, Respir. Res. 11 (2010) 26. [2] D. Singh, D. Richards, R.G. Knowles, S. Schwartz, A. Woodcock, S. Langley, B.J. O'Connor, Selective inducible nitric oxide synthase inhibition has no effect on allergen challenge in asthma, Am. J. Respir. Crit. Care Med. 176 (2007) 988e993. [3] D.W. Cockcroft, K.Y. Murdock, J. Kirby, F. Hargreave, Prediction of airway reponsiveness to allergen from skin sensitivity to allergen and airway hyperesponsiveness to histamine, Am. Rev. Respir. Dis. 135 (1987) 254e257. [4] WY. Lee, T. Southworth, S. Booth, D. Singh, High and low dose allergen challenges in asthma patients using inhaled corticosteroids, Br. J. Clin. Pharmacol. 79 (2015) 523e532. [5] D. Singh, P. Cadden, M. Hunter, L. Pearce Collins, M. Perkins, R. Pettipher, E. Townsend, S. Vinall, B. O'Connor, Inhibition of the asthmatic allergen challenge response by the CRTH2 antagonist OC000459, Eur. Respir. J. 41 (2013) 46e52. [6] B.R. Leaker, D. Singh, F.Y. Ali, P.J. Barnes, B. O'Connor, The effect of the novel phosphodiesterase-4 inhibitor MEM 1414 on the allergen induced responses in mild asthma, BMC Pulm. Med. 14 (2014) 166. [7] J.C. Kidney, L.P. Boulet, F.E. Hargreave, F. Deschesnes, V.A. Swystun, P.M. O'Byrne, N. Choudry, M.M. Morris, B. Jennings, N. Andersson, A. Andreasson, D.W. Cockcroft, Evaluation of single-dose inhaled corticosteroid
activity with an allergen challenge model, J. Allergy Clin. Immunol. 100 (1997) 65e70. [8] M. Duong, G. Gauvreau, R. Watson, G. Obminski, T. Strinich, M. Evans, K. Howie, K. Killian, P.M. O'Byrne, The effects of inhaled budesonide and formoterol in combination and alone when given directly after allergen challenge, J. Allergy Clin. Immunol. 119 (2007) 322e327. [9] M. Bafadhel, M. McCormick, S. Saha, S. McKenna, M. Shelley, B. Hargadon, V. Mistry, C. Reid, D. Parker, P. Dodson, M. Jenkins, A. Lloyd, P. Rugman, P. Newbold, C.E. Brightling, Profiling of sputum inflammatory mediators in asthma and chronic obstructive pulmonary disease, Respiration 83 (2012) 36e44.
Wha-Yong Lee*, Thomas Southworth, Dave Singh The University of Manchester, Manchester Academic Health Science Centre, Medicines Evaluation Unit, University Hospital South Manchester NHS Foundation Trust, NIHR South Manchester Respiratory and Allergy Clinical Research Facility, Manchester, UK *
Corresponding author. The University of Manchester, Manchester Academic Health Science Centre, Medicines Evaluation Unit, University Hospital South Manchester NHS Foundation Trust, NIHR South Manchester Respiratory and Allergy Clinical Research Facility, Manchester M23 9LT, UK. E-mail address: [email protected] (WY. Lee). 24 June 2015 Available online 30 June 2015
Contents lists available at ScienceDirect
Pulmonary Pharmacology & Therapeutics journal homepage: www.elsevier.com/locate/ypupt
Different inhaled allergen challenge models give reproducible results
Keywords: Allergen challenge Asthma Inhaled corticosteroids Induced sputum
The inhaled allergen challenge model causes an early asthmatic response (EAR), followed by a late asthmatic response (LAR) characterised by an increase in eosinophilic airway inflammation. The inhaled allergen challenge model has been used to study novel anti-inflammatory drugs in clinical trials [1e3]. The two most commonly used inhaled allergen challenge models are (1) the incremental dose challenge, where incremental allergen doses are delivered by a breath-activated dosimeter until an EAR is observed [4e6] and (2) the tidal breathing challenge, where predicted concentrations of allergen are inhaled during tidal breathing for 2 min from a nebuliser until an EAR is observed [3,7,8]. Allergen challenge studies are usually conducted in patients who are not taking inhaled corticosteroids (ICS), as these drugs inhibit the LAR [7,8]. However, we have recently shown that incremental dose challenges cause an LAR in asthmatics using ICS [4]. This indicates the potential of allergen challenges to be used in this patient population. Here we report a comparison of the effects of the tidal breathing and incremental allergen challenge models in asthma patients using ICS, in order to determine whether different methodologies give similar results. Fourteen asthma patients taking ICS (<1000mcg/day beclomethasone dipropionate equivalent; mean ICS dose (SD) 396.4 (240.6) mcg) who had participated in our previous study [4] (10 male and 4 female, mean age 40, mean FEV1 % predicted 89.0%, mean baseline Asthma Control Questionnaire score 1.3, mean baseline exhaled nitric oxide level 58 ppb) underwent the tidal breathing challenge at 2e24 weeks after the incremental dose challenge. The allergen used for the allergen challenges were house dust mite in 10 patients, cat in 3 patients and grass mix in 1 patient. The reason for the long duration between challenges for some patients
was busy work and social schedules. Allergen challenges, sputum collection and processing were performed as previously described [2e4,9]. Baseline sputum was collected at least 5 days prior to the allergen challenge. Sputum was collected at 24 h post-allergen challenge. Written informed consent was obtained and the local research ethics committee approved the study. The EAR and LAR were expressed as the area under curve of percentage change in FEV1 during first 2 h ((AUC)0e2h) and from 4 to 10 h ((AUC)4e10h) respectively. The mean maximum fall in FEV1 during the EAR and LAR (max EAR and max LAR respectively) were also calculated. Agreement between the two challenges was determined by paired t-tests and BlandeAltman analysis (GraphPad software, San Diego, CA, USA). The within-subject standard deviation (SD) was calculated using the difference between the means and ANOVA (SPSS v22.0, Armonk, NY, USA). Sputum eosinophil % counts were parametrically distributed. Paired t-tests were used to compare baseline and post-challenge sputum eosinophil %, and to compare results between the challenge models. p < 0.05 was considered to be statistically significant. The differences between challenges are shown in Table 1. The mean EAR and LAR values were very similar (p > 0.05 for all comparisons of AUC and maximum fall). The BlandeAltman analysis also showed a relatively small mean bias for the EAR and LAR, although the 95% limits of agreement indicate that some individual results may vary greatly. The within-subject SD are shown, and may be used for future power calculations. The incremental dose method caused an increase in the mean sputum eosinophil %: baseline mean ¼ 0.94%, post challenge mean ¼ 6.95%, p < 0.01. Similar results were obtained for the tidal breathing method: baseline mean ¼ 0.64%, post challenge mean ¼ 4.98%, p < 0.01. There were no statistically significant differences in baseline and post-challenge sputum eosinophil % between both methods. We show that the incremental and tidal breathing challenge methods cause similar changes in lung function and sputum eosinophils in asthmatics taking ICS. Both allergen challenge methodologies cause similar allergic reactions in this patient group.
Abbreviations: AUC, area under curve; EAR, early asthmatic response; ICS, inhaled corticosteroids; LAR, late asthmatic response; SD, standard deviation. http://dx.doi.org/10.1016/j.pupt.2015.06.005 1094-5539/© 2015 Elsevier Ltd. All rights reserved.
58
WY. Lee et al. / Pulmonary Pharmacology & Therapeutics 33 (2015) 57e58
Table 1 Comparison and reproducibility of the tidal breathing challenge and incremental dose challenge. Allergen challenge
EAR(AUC)0e2a DFEV1%.hr Max EAR(DFEV1%)0e2a LAR (AUC)4e10a DFEV1%.hr Max LAR(DFEV1%)4e10a
p value
Incremental dose
Tidal breathing
24.0 28.1 82.9 23.9
23.4 27.0 92.7 25.4
(±10.6) (±5.8) (±49.7) (±9.4)
(±12.1) (±8.5) (±75.3) (±12.3)
BlandeAltman analysis Mean difference (95% limits of agreement)
0.87 0.75 0.57 0.67
0.62 (27.25e28.50) 1.16 (24.37e26.69) 9.84 (133.50e113.80) 1.52 (27.15e24.11)
Within subject SD (calculated from difference of means)
Within subject SD (calculated from ANOVA)
14.2 13.0 63.1 13.1
9.6 8.6 42.3 8.7
a Parametric data presented as mean (standard deviation) and analysed using paired t-test. Agreement between measures of EAR and LAR, and the AUC for the allergen challenges is presented by BlandeAltman analysis.
Acknowledgements We would like to thank Julie Morris and Sigrid Whiteside for the statistical advice, and the Medicines Evaluation Unit for funding the study. References [1] D. Singh, F. Petavy, A.J. Macdonald, A.L. Lazaar, B.J. O'Connor, The inhaled phosphodiesterase 4 inhibitor GSK256066 reduces allergen challenge responses in asthma, Respir. Res. 11 (2010) 26. [2] D. Singh, D. Richards, R.G. Knowles, S. Schwartz, A. Woodcock, S. Langley, B.J. O'Connor, Selective inducible nitric oxide synthase inhibition has no effect on allergen challenge in asthma, Am. J. Respir. Crit. Care Med. 176 (2007) 988e993. [3] D.W. Cockcroft, K.Y. Murdock, J. Kirby, F. Hargreave, Prediction of airway reponsiveness to allergen from skin sensitivity to allergen and airway hyperesponsiveness to histamine, Am. Rev. Respir. Dis. 135 (1987) 254e257. [4] WY. Lee, T. Southworth, S. Booth, D. Singh, High and low dose allergen challenges in asthma patients using inhaled corticosteroids, Br. J. Clin. Pharmacol. 79 (2015) 523e532. [5] D. Singh, P. Cadden, M. Hunter, L. Pearce Collins, M. Perkins, R. Pettipher, E. Townsend, S. Vinall, B. O'Connor, Inhibition of the asthmatic allergen challenge response by the CRTH2 antagonist OC000459, Eur. Respir. J. 41 (2013) 46e52. [6] B.R. Leaker, D. Singh, F.Y. Ali, P.J. Barnes, B. O'Connor, The effect of the novel phosphodiesterase-4 inhibitor MEM 1414 on the allergen induced responses in mild asthma, BMC Pulm. Med. 14 (2014) 166. [7] J.C. Kidney, L.P. Boulet, F.E. Hargreave, F. Deschesnes, V.A. Swystun, P.M. O'Byrne, N. Choudry, M.M. Morris, B. Jennings, N. Andersson, A. Andreasson, D.W. Cockcroft, Evaluation of single-dose inhaled corticosteroid
activity with an allergen challenge model, J. Allergy Clin. Immunol. 100 (1997) 65e70. [8] M. Duong, G. Gauvreau, R. Watson, G. Obminski, T. Strinich, M. Evans, K. Howie, K. Killian, P.M. O'Byrne, The effects of inhaled budesonide and formoterol in combination and alone when given directly after allergen challenge, J. Allergy Clin. Immunol. 119 (2007) 322e327. [9] M. Bafadhel, M. McCormick, S. Saha, S. McKenna, M. Shelley, B. Hargadon, V. Mistry, C. Reid, D. Parker, P. Dodson, M. Jenkins, A. Lloyd, P. Rugman, P. Newbold, C.E. Brightling, Profiling of sputum inflammatory mediators in asthma and chronic obstructive pulmonary disease, Respiration 83 (2012) 36e44.
Wha-Yong Lee*, Thomas Southworth, Dave Singh The University of Manchester, Manchester Academic Health Science Centre, Medicines Evaluation Unit, University Hospital South Manchester NHS Foundation Trust, NIHR South Manchester Respiratory and Allergy Clinical Research Facility, Manchester, UK *
Corresponding author. The University of Manchester, Manchester Academic Health Science Centre, Medicines Evaluation Unit, University Hospital South Manchester NHS Foundation Trust, NIHR South Manchester Respiratory and Allergy Clinical Research Facility, Manchester M23 9LT, UK. E-mail address: [email protected] (WY. Lee). 24 June 2015 Available online 30 June 2015