Improvement of Mucosal Pathology of the Sinuses after Exposure to Sulfur Dioxide by Nebulization of S-Carboxymethylcysteine

Abstract

Since s-carboxymethylcysteine (S-CMC) can directly enhance the ciliary activity in the maxillary sinus mucosa of patients with chronic sinusitis in the absence of significant organic changes of ciliated cells, the nebulization therapy using this medicine might be more effective in the treatment of chronic sinusitis than oral administration of the medicine. The safety of using 0.5–10% of S-SMC as a medicine for nebulization has been experimentally established. The present study was designed to experimentally examine the effectiveness of nebulization using 0.5–10% of S-CMC solution in the treatment of experimental chronic sinusitis in rabbits recurrently exposed to 20 ppm of sulfur dioxide. Thirty-three healthy rabbits were used; 3 of them were used as controls. The remaining 30 were exposed to 20 ppm of sulfur dioxide for 4 h a day for 4 successive weeks. Twelve animals were not treated with any medication during the post-exposure period, and sacrificed at 24 h or 15 days after completion of the final exposure to sulfur dioxide. The remaining 18 animals were treated with nebulization using 10%, 5% or 0.5% of S-CMC solution for 20 min a day for 14 successive days after the final exposure to sulfur dioxide, and they were sacrificed at 24 h after the final nebulization using S-CMC. At the time of sacrifice, the ciliary activity and the morphology of the sinus mucosa were observed to assess the effectiveness of S-CMC nebulization. In the animals sacrificed 24 h after the final exposure, the mucosa of the sinus demonstrated marked epithelial cell injuries, and the ciliary activity was extremely reduced. Complete recovery of the epithelium and the ciliary activity was not recognized in the animals sacrificed 15 days after completion of the exposure. By contrast, epithelial recovery was more accelerated in the animals treated with S-CMC nebulization during the 14 days after the exposure. In the animals treated with 0.5% of S-CMC, the ciliary activity was inferior to that of the control animals, and the epithelial repair was not complete. In the animals treated with 10% of S-CMC, however, ciliary activity and epithelial morphology were completely recovered. In conclusion, our study suggests that clinical application of 10% of S-CMC nebulization may provide otolaryngologists with a new tool in the treatment of sinus diseases such as chronic sinusitis.

Key Words:

• s-carboxymethylcysteine
• chronic sinusitis
• ciliary activity
• electron microscopy
• maxillary sinus
• nebulization
• sulfur dioxide.