Expression Of Substance P(SP) And Vasoactive Intestinal Peptide(VIP) In Vocal Fold Polyps

Objective:The objective of this study was investigation and quantitative analysis of the expression of substance P (SP) and vasoactive intestinal peptid (VIP) in vocal fold polypus and normal tissue of vocal folds to probe the pathogeny of vocal fold polyp, understand the roles of SP and VIP in the pathogenesis of vocal cord polypus and their mutual relations, and provide a theoretical basis for clinical prevention and treatment of vocal cord polypus. Materials and Methods:40 patients without other vocal cord lesions who were undergone polypectomy were enrolled in this study for the experimental group. The specimens of vocal cord polyps were diagnosed by pathologists. Specimens of normal vocal fold were obtained from 20 autopsy cases for the control group. All samples were stained with hematoxylin-eosin, and immunohistochemical staining of SP and VIP were performed with monoclonal antibodies by Max Vision^TM method, and then the average value of Positive units that SP and VIP had expressed in vocal fold polyps and normal tissue of vocal folds was analyzed by means of quantitative analysis of computer images. Results:SP and VIP's expression were faint in the normal vocal fold. In the vocal cord polyp tissues, strong immunostaining for SP and VIP was found in the epithelial cells, inflammatory cells, fibroblasts, vascular endothelial cells and glandular cells.The average value of SP positive units (40.4833±5.83513)in the vocal cord polyp group was higher than the normal vocal group (34.1300±5.56434), there was statistically significant difference (p<0.05); The average value of VIP positive units (47.5144±6.98540) in the vocal cord polyp group was higher than the normal vocal group (24.2522±8.22501), there was statistically significant difference (p<0.01). The average values of SP and VIP positive units in the vocal cord polyp group were analyzed with scatter,the two variables were not linear trend shown that there was no correlation between them. Conclusion:When various reasons lead to repeated injury of the vocal cords, the vocal cord tissue's secretion of SP and VIP increase, the effect may be:(1) SP can directly act on the SP-specific receptors on vascular endothelial cells and cause to endothelium-dependent effect. Meanwhile, it can indirectly act on artery and make vasodilator effect by stimulating the mastocyte to release histamine. Then plasma is extravasation and vocal cord become congestion and edema. VIP has the same vasodilator effet as SP, and it can stimulate the expression of vascular endothelial growth factor, which would further maintain the local blood vessel network. and cause to tissue's edema. The increase in blood supply would be to the advantage of the polyp, maintaining its growth. (2)SP and VIP can induce the releasing of mediators of inflammation and lead to chronic inflammation together.Then cause the inflammation cells infiltration, the vascular endothelial basement membrane broken, vasopermeability increasing and plasma protein exfiltration. Many intravascular mass pass the broken basement membrane and result in the lamina propria of vocal cord mucosa hydropsia, expanding and the hydrostatic pressure heightening. The basement membrane's intrinsical equalization of pressure has been destroied and the formation speed of vocal cord polyps become quickly. This is also the inflammatory reaction's theory proof and neurogenic inflammation's characteristic. (3)SP and VIP may play an important role of increasing glandular organ's secretion and saccular dilatation. (4) SP can promote fibroblastic cells hyperplasy, enhance fibroblastic cells hyperplasy reaction which are induced by IL-1 and lead to hyaline degeneration. The arrangement of lamina propria became disorder, the lamellar structure disappear and polypus formation.