The effectiveness of erythromycin in reducing stent-related tissue hyperplasia: An experimental study with a rat esophageal model

Background: Erythromycin is not only a potent antibiotic; it also has effects of reduction of inflammation and suppression of protein synthesis. Purpose: To evaluate the impact of erythromycin on tissue hyperplasia after stent placement in a rat esophageal model. Material and Methods: A total of 21 rats were included. After placement of self-expanding stents in the mid esophagus, the rats were divided into two experimental groups and one control group. The rats in the experimental groups received daily intraperitoneal injections of erythromycin for 5 weeks; 4 mg/kg (group A, n = 7) and 8 mg/kg (group B, n = 7). Those in the control group (n = 7) received 1 mL of saline intraperitoneally. After sacrifice, histologic analysis was done for thickness of the papillary projection, granulation tissue area, percentage of granulation tissue area, and degree of inflammatory cell infiltration. The statistical significance of differences between groups was assessed by Mann-Whitney U test. Results: Tissue hyperplasia as reflected in thickness of papillary projection, granulation tissue area, and percentage of granulation tissue area, was higher in the control group than in the experimental groups, although there was no statistical significance (P = 1.00, 0.332, and 0.263, respectively). However, degree of inflammatory cell infiltration was significantly lower in the experimental groups than the control group (P = 0.025), and the higher dosage of erythromycin reduced inflammatory cell infiltration significantly (P = 0.037). Conclusion: Intraperitoneal administration of erythromycin is very effective in reducing inflammation after stent placement in a rat esophageal model but has no significant effect on granulation tissue formation.