Nuclear localization of Toll-like receptor 5 in Barrett's esophagus and esophageal adenocarcinoma is associated with metastatic behavior.

Toll-like receptor 5 (TLR5) recognizes bacterial flagellin. Increased cytoplasmic and nuclear expression of some TLRs has been previously reported in dysplasia in Barrett's esophagus and various malignant lesions in association with survival and metastasis. We assessed nuclear expression of TLR5 in Barrett's esophagus and esophageal adenocarcinoma (n = 94) by immunohistochemistry and immunofluorescent staining. Nuclear expression was observed in the majority of studied lesions with high variation in the proportion of positive nuclei. Expression in lymph node metastases was significantly higher than in esophageal lesions (p < 0.05), except for intestinal metaplasia and low-grade dysplasia. Furthermore, nuclear expression of TLR5 was associated with the presence of lymph node metastases (p = 0.033). In conclusion, we report nuclear TLR5 expression in Barrett's esophagus and adenocarcinoma. Abundance of positive nuclei in association with lymph node metastases suggests that TLR5 is involved in the pathogenesis and dissemination of esophageal adenocarcinoma through as-yet-uncharacterized mechanisms.