IDDF2024-ABS-0227 Differential nurogenesis status unveils distinct neurodegenerative mechanism among achalasia subtypes

<h3>Background</h3> Achalasia is an acquired esophageal neurodegenerative disorder, characterized by selective loss of inhibitory neurons in the myenteric plexus of the lower esophageal sphincter (LES). The Enteric neural precursor cell (ENPC) is essential in maintaining neurogenesis, but its role in achalasia pathogenesis is unknown. This study aimed to explore the neurogenesis status in LES among achalasia patients. <h3>Methods</h3> LES specimens from 59 patients with achalasia who underwent peroral endoscopic myotomy (POEM) and from 10 control patients with esophageal cancer were examined. Double-labeled immunohistochemistry staining was performed to evaluate Nestin-expressing ENPC and axons innervation in LES. Immunohistochemistry values were compared between groups and correlated with clinical variables, including demographics, disease duration, Eckardt score, manometric parameters and treatment outcome. <h3>Results</h3> Nestin-positive ENPCs (IDDF2024-ABS-0227 Figure 1. Nestin-positive ENPCs in LES specimens of achalasia and controls) and immature PGP9.5- and nNOS-labeled axons (IDDF2024-ABS-0227 Figure 2. Immature PGP9.5- and nNOS-labeled axons in achalasia and controls) were observed in both achalasia and control. A significant reduction of Nestin-positive cells, PGP9.5- and nNOS-labeled axons was observed in achalasia (IDDF2024-ABS-0227 Table 1). The number of Nestin-positive cells significantly correlated with axons innervation, confirming their roles in neurogenesis (IDDF2024-ABS-0227 Table 2). The number of Nestin-positive cells, immature total axons (Nestin+PGP9.5+) and immature nitrergic axons (Nestin+nNOS+) were different among achalasia subtypes (IDDF2024-ABS-0227 Table 1). Type 2 achalasia exhibited a more severe loss of both ENPC and axons innervation, while type 1 achalasia was characterized by retained ENPC and immature nitrergic axons, along with severe depletion of mature axons (Nestin-nNOS+) (IDDF2024-ABS-0227 Figure 3. Comparisons of total axons and immature axons between achalasia subtypes). <h3>Conclusions</h3> Neurogenesis was generally impaired in achalasia, as evidenced by the decreased number of Nestin-positive ENPC. Neurodegeneration in type 2 achalasia might result from the loss of ENPC, while maturation disorders of nitrergic neurons were observed in type 1 achalasia. The pathophysiology of each manometric subtype was possibly distinct.