Abstract
<b><i>Introduction:</i></b> Esophageal achalasia is a typical esophageal motility disorder (EMD). Although viral infections have been hypothesized to play a role in the pathogenesis of esophageal achalasia, its etiology remains unclear. This study used esophageal muscle layer specimens collected during per-oral endoscopic myotomy (POEM) procedures to investigate the association between esophageal achalasia and esophagogastric junction outflow obstruction (EGJOO) and pattern recognition receptors. <b><i>Methods:</i></b> Patients with esophageal achalasia and EGJOO who underwent POEM were allocated to the EMD group. Biopsies of the inner circular muscle were conducted during the POEM procedure. The control group comprised individuals diagnosed with esophageal squamous cell carcinoma who underwent surgical resection. Expression of pattern recognition receptors, including Toll-like receptor (TLR) 7, was examined by polymerase chain reaction. Immunohistochemical staining was performed to determine TLR7 expression sites in the esophageal muscle layer, and the relationship between TLR7 mRNA expression and clinical score was investigated. <b><i>Results:</i></b> Our analysis revealed a notable upregulation of TLR7 mRNA levels within the muscle layer of esophageal achalasia and EGJOO, in contrast to those of control specimens. In contrast, the correlation between TLR7 and clinical score was not significant. Immunohistochemical staining revealed increased numbers of TLR7-expressing macrophages between the muscle layers. <b><i>Conclusions:</i></b> TLR7-expressing macrophages are involved in the innate immune response underlying esophageal achalasia and EGJOO. This result will lead to the elucidation of new pathogenetic mechanisms and the development of novel therapeutic targets.