Evaluation of the immunoreactivity of nerve growth factor and tropomyosin receptor kinase A in the esophagus of noninfected and infected individuals with Trypanosoma cruzi.

Megaesophagus is one of the major manifestations of the chronic phase of Chagas disease. Its primary symptom is generally dysphagia due to disturbance in the lower esophageal sphincter. Microscopically, the affected organ presents denervation, which has been considered as consequence of an inflammatory process that begins at the acute phase and persists in the chronic phase. Inflammatory infiltrates are composed of lymphocytes, macrophages, natural killer cells, mast cells, and eosinophils. In this study, we evaluated the immunoreactivity of nerve growth factor (NGF), and of its receptor tropomyosin receptor kinase A (TrkA), molecules that are well known for having a relevant role in neuroimmune communication in the gastrointestinal tract. Esophageal samples obtained via autopsy or surgery procedures from six noninfected individuals, six infected individuals without megaesophagus, and six infected individuals with megaesophagus were analyzed. Infected individuals without megaesophagus presented increased numbers of NGF immunoreactive (IR) mast cells and increased areas of TrkA-IR epithelial cells and inner muscle cells. Infected individuals with megaesophagus showed increased numbers of NGF-IR eosinophils and mast cells, TrkA-IR eosinophils and mast cells, increased area of NGF-IR epithelial cells, and increased areas of TrkA-IR epithelials cells and inner muscle cells. The data presented here point to the participation of NGF and its TrkA receptor in the pathology of chagasic megaesophagus.