Discussion
The process of nasal epithelization after ESS is closely related to the recovery of symptoms. A previous study19 showed that nasal irrigation with saline containing sodium hyaluronate improves postoperative nasal symptoms and accelerated the process of nasal epithelization. However, the evaluation indexes were subjective symptom score and endoscopic score in patients 6 weeks after the operation, with no direct evaluation of ciliary function recovery. In our study, we used subjective symptom score and endoscopic score in patients as the primary statistical index. We also collected the nasal mucosa of patients for SEM analysis as a direct index of mucosal epithelization and ciliary recovery. Our results showed the reduction of VAS, obstruction and rhinorrhea scores for general symptom in rh-bFGF nasal experimental group were significantly greater than in the control group, and SNOT-22 score reduction was significantly greater in the rh-bFGF nasal-drop group compared to the control group 2 weeks after ESS, indicating that intranasal use of rh-bFGF exerts obvious effects on rapid recovery of symptoms in ESS postoperative patients. What’s more, a significant reduction was found in in rh-bFGF experimental groups at 6 months and 1 year which indicated that rh-bFGF may exert an persistent effect on its recovery. We performed a one-year recurrence and efficacy evaluation, considering that epithelial damage of the nasal cavity is an important factor causing the onset of sinusitis, we can predict that promoting epithelialization and ciliary growth during the early stage is helpful for reducing recurrence and polyp regeneration.
Th2-type CRS was associated with eosinophils and asthma. Studies11,12 have shown that eosinophilic-associated CRS presents more severe postoperative mucosal edema and polypoid changes than non-eosinophilic CRS. In our study, one year follow-up data for the eosinophilic CRS patients showed that the reduction in VAS scores in the rh-bFGF nasal-drop group was greater than in the control group. Moreover, the reduction in the L-K score in the rh-bFGF nasal-spray group was greater than that in the control group. This suggests that rh-bFGF may also contribute to the rapid recovery of eosinophilic sinusitis patients. However, this trend was not obvious in rh-bFGF experimental groups of non-eosinophilic patients compared with control group. We analyzed the reason for this difference between eosinophilic and non-eosinophilic CRSwNP, which was attributed to the poorer ciliary coverage and sever epithelial damage in eosinophilic CRSwNP. Therefore, we consider that rh-bFGF may improve the prognosis of patients with CRSwNP by promoting ciliary growth and epithelial repair.
To further verify the mechanism of rh-bFGF on the rapid recovery of ESS patients, epithelial cells of the experimental and the control groups were examined by SEM. 2 weeks and 1 month after ESS, rh-bFGF nasal-spray and rh-bFGF nasal-drop group exhibited a higher ciliary coverage compared with control group. CP110, Foxj1 and Tap73 have already been proven as ciliogenesis-associated makers20. The expression of these three genes has been marked decreased in rh-bFGF experimental groups compared with control group at 2 weeks and 1 month after ESS, which was consistent with the result of SEM. These results suggest that the outstanding improvement of postoperative nasal obstruction, rhinorrhea, as well as the endoscope L-K score, were also associated with rapid epithelialization and ciliary coverage.
The method of nasal administration is another highlight of our research design. Previous studies21,22 have shown that changing the administration method of local nasal corticosteroids may affect the symptoms. Therefore, we designed a nasal-drop experiment group. The reduction in the VAS score for general symptoms in the rh-bFGF experimental groups was significantly greater than in the control group. In terms of epithelialization and ciliary growth post-operation, the rh-bFGF experimental groups may have the same effect on ethmoid mucosa cilia growth, whereas mucosa from patients in the control group had significantly less ciliated coverage. Therefore, the overall effect of the nasal-drop group was better than that of the nasal-spray group. This may be attributed to position drainage, which enables rh-bFGF to reach the mucous of the ethmoid roof and frontal recess.