An increased proportion of inflammatory cells express tumor necrosis factor alpha in idiopathic achalasia of the esophagus

Abstract

Achalasia is a motility disorder characterized by the absence of coordinated peristalsis and incomplete relaxation of the lower esophageal sphincter. The etiology remains unclear although dense inflammatory infiltrates within the myenteric plexus have been described. The nature of these infiltrating cells is unknown. The aim of this study was to evaluate the expression of proinflammatory cytokines - namely, tumor necrosis factor alpha and interleukin-2 - in the distal esophageal muscle in patients with achalasia. Lower esophageal sphincter muscle from eight patients undergoing myotomy or esophagectomy for achalasia of the esophagus were obtained at the time of surgery. Control specimens consisted of similar muscle taken from eight patients undergoing operation for cancer or Barrett's esophagus. The expression of tumor necrosis factor alpha and interleukin-2 were assessed by immunohistochemistry. The total number of inflammatory cells within the myenteric plexus were counted in five high power fields. The percentage of infiltrating cells expressing tumor necrosis factor alpha or interleukin-2 was calculated. Clinical data including demographics, preoperative lower esophageal sphincter pressure, duration of symptoms, and dysphagia score (1 = no dysphagia to 5 = dysphagia to saliva) were obtained through electronic medical records. Statistical comparisons between the groups were made using the unpaired t-test, Fisher's exact test, or Mann-Whitney U test, with a two-tailed P-value less than 0.05 being considered significant. The total number of inflammatory cells was found to be similar between the groups. A significantly higher proportion of inflammatory cells expressed tumor necrosis factor alpha in achalasia as compared with controls (22 vs. 11%; P= 0.02). A similar percentage of infiltrating cells expressed interleukin-2 (40 vs. 41%; P= 0.87). Age, gender, preoperative lower esophageal sphincter pressure, or dysphagia score were not correlated to expression of these cytokines. There was, however, a significant inverse correlation between duration of symptoms and the proportion of inflammatory cells expressing tumor necrosis factor alpha in achalasia (P= 0.007). In conclusion, a higher proportion of infiltrating inflammatory cells expressed tumor necrosis factor alpha in achalasia. Furthermore, this proportion appears to be highest early in the disease process. Further studies are required to more clearly delineate the role of tumor necrosis factor alpha in the pathogenesis of this idiopathic disease.