The relationship between cough response and airway inflammation in guinea pigs sensitized and challenged with ovalbumin

AIM: To investigate the effects of intensity of eosinophilic airway inflammation on cough response in guinea pigs sensitized and challenged with ovalbumin. METHODS: 34 sensitized guinea pigs were challenged with the aerosol of either saline (group A,n= 7) or 0.04% (group B,n= 7),0.2% (group C,n= 8) and 1% (group D,n= 12) of ovalbumin. 24 hours later,cough response to inhaled capsaicin and airway responsiveness to inhaled methacholine (PC_ 150 ) were measured. Total cell number and differentials in bronchoalveolar lavage were analyzed. RESULTS: After challenge,one animal in group C and five animals in group D died from severe wheezing. With ascending concentration of ovalbumin,cough frequency induced by inhaled capsaicin increased from (6±2) times/3 min in group A to (22±4) times/3 min in group D( P 0.05). PC_ 150 ,which did not change in group B,increased in both group C and group D significantly in addition to an increase in total cell number and eosinophils in bronchoalveolar lavage. Cough response to inhaled capsaicin was positively correlated with total cell number ( r= 0.84,P 0.01) and eosinophils ( r= 0.78,P 0.01) in bronchoalveolar lavage,and negatively correlated with PC_ 150 ( r= -0.78,P 0.01). There was a negative correlation between PC_ 150 and total cell number ( r= -0.80,P 0.01) or eosinophils ( r= -0.85,P 0.01). CONCLUSION: Cough response in sensitized guinea pigs is enhanced and finally develops into wheezing with a progress in eosinophilic airway inflammation.