A pilot study of spray cryotherapy effects on airway secretions

Spray cryotherapy (SCT) is a new transbronchial approach that disrupts epithelial cells by freezing. However, there are limited data addressing the effect of SCT on airway secretion. The aim of this study was to evaluate if SCT effect on airway secretion and the possible mechanism in canines. Fifteen labradors were randomly scheduled SCT or sham operation. Six labradors were scheduled SCT for a short-time observation, and six for a long-time observation, the remaining three received sham operation as control. Lung tissues were harvested for PAS staining. Mucin, MUC5AC and acetylcholine in bronchoalveolar lavage fluid (BALF) were analyzed by enzyme-linked immunosorbent assay (ELISA). CHRM3 and Mucin 5AC (MUC5AC) expressions in the lung tissues were analyzed by immunohistochemistry. MUC5AC mRNA expression was analyzed by rt-PCR. From 0 day to 30 days after SCT, the ratio of PAS positive cells to total bronchial epithelial cells, the average optical density of MUC5AC + by immunohistochemistry, the protein expression of MUC5AC, acetylcholine in BALF decreased compared with that of control group (p < 0.05). The average optical density of CHRM3+ by immunohistochemistry were decreased from 0 day to 7 days after SCT (p < 0.05) compared with control group. In conclusion, SCT was able to reduce the PAS-, MUC5AC- and CHRM3-positive cells in the lung tissue and acetylcholine in BALF, suggesting that SCT may prove to be a beneficial way in mucus excessive production in airway and acetylcholine-CHRM3 pathway may one possible mechanism.