Background: Primary achalasia is a rare disorder but a significant cause of esophageal motor dysfunction. The pathophysiology of achalasia is still unknown, although an autoimmune etiology is suspected.
Objectives: To examine the presence of autoantibodies against autonomic nervous system receptors among primary achalasia patients.
Methods: In this observational cross-sectional study, we measure the levels of serum autoantibodies targeting G protein-coupled receptors of the autonomic nervous system, including adrenergic, muscarinic, endothelin, and angiotensin receptors. The study included 40 primary achalasia patients and 40 healthy controls without known history of achalasia, autoimmune diseases, or symptoms of an esophageal motility disorder.
Results: A statistically significant low level of autoantibodies against the M2 muscarinic receptor was observed in the serum of primary achalasia patients compared with the control group (P < 0.009). When exploring the two common achalasia types, a statistically significant low level of autoantibodies against type M1, M2, and M5 muscarinic receptors was observed among type 2 achalasia patients compared to patients with type 1 achalasia.
Conclusions: The finding of reduced levels of autoantibodies targeting the M2 muscarinic receptor in the serum of primary achalasia patients provides a valuable insight into the underlying pathogenesis of the disease.