Objective

2

To explore the establishment and validation of a guinea pig model of post-infecious cough with the cold-fluid retention in the lung syndrome.

Methods

2

Eighteen experimental guinea pigs were randomly divided into a blank group， a cough with cold-fluid group， and a traditional Chinese medicine （TCM） group， with six guinea pigs in each group. Except for the blank group， guinea pigs were subjected to smoke exposure， intranasal lipopolysaccharide instillation， and citric acid aerosol inhalation to

establish a post-infectious cough disease model. Based on this， combined cold exposure and administration of ice water were applied for 14 days to induce the cold-fluid retention in the lung syndrome. On the day following model establishment， the TCM group was given

Shufeng Wenfei Zhike Granules

（疏风温肺止咳颗粒） at a dose of 5.5 g/（kg·d） by gavage， while the blank group and the cough with cold-fluid group received equal volume of distilled water. All groups were treated once daily for 7 consecutive days. On the day after intervention， the general condition of the guinea pigs was observed. Citric acid challenge was used to induce coughing， and the number of coughs within 5 minutes was recorded. Lung tissue pathological changes were examined by hematoxylin-eosin （HE） staining. Enzyme-linked immunosorbent assay （ELISA） was used to measure serum inflammatory cytokines， including interleukin-1β （IL-1β） and interleukin-8 （IL-8）， as well as protein levels of the transient receptor potential ankyrin 1 （TRPA1） pathway and airway neurogenic inflammation-related factors， including substance P （SP） and neurokinin A （NKA）， in bronchoalveolar lavage fluid. The mRNA expression levels of

TRPA1

，

SP

， and

NKA

in tracheal and lung tissues were detected by reverse transcription polymerase chain reaction （RT-PCR）.

Results

2

Compared with the blank group， the guinea pigs in the cough with cold-fluid group showed significant lethargy， coughing， white mucous secretions from the mouth and nose， lukewarm limbs， curled and inactive posture， disheveled and dull hair with shedding， pale ears， mouth， and lips， and loose stools. These manifestations were alleviated in the TCM group compared with the cough with cold-fluid group. HE staining showed thickening of the alveolar walls with extensive inflammatory cell infiltration， narrowed bronchial lumens， partial disruption of bronchial walls， and epithelial cell shedding in the cough with cold-fluid group.

In the TCM group， bronchial wall thickening and inflammatory cell infiltration were observed， but overall pathological changes were improved when compared with the cough with cold-fluid group. Compared with the blank group， the cough with cold-fluid group showed a signi-ficantly increased number of induced coughs， elevated serum levels of IL-8 and IL-1β， and increased protein and mRNA expression of TRPA1， SP， and NKA in bronchoalveolar lavage fluid， tracheal tissue， and lung tissue （

P

＜0.01）. Compared with the cough with cold-fluid group， the TCM group showed a significantly reduced number of induced coughs， decreased serum levels of IL-8 and IL-1β， and reduced protein and mRNA expression of TRPA1， SP， and NKA in bronchoalveolar lavage fluid， tracheal tissue， and lung tissue （

P

＜0.01）.

Conclusion

2

A combined approach of smoke exposure， intranasal lipopolysaccharide instillation， and citric acid aerosol inhalation， together with cold stimulation and ice-water administration， can be used to establish a disease-syndrome combined model of post-infectious cough with the cold-fluid retention in the lung syndrome.