Association of Increased Epstein-Barr Virus Reactivation With Imbalanced Immunity and Myenteric Neuron Loss in Achalasia.

Background And Aim: Viral infection has been postulated as a potential etiology of achalasia, yet the definitive role of viral involvement remains elusive. This study aims to elucidate virus infections and to analyze their relationships with clinical characteristics, immunological alterations, and neuron loss.

Methods: We investigated viral infections in achalasia patients (n = 288) and controls (n = 71). Propensity score matching (PSM) was employed to mitigate selection bias. Flow cytometry and ELISA were performed to characterize the immunological changes. In situ hybridization and immunofluorescence staining were used to detect viral infections within lower esophageal sphincter (LES).

Results: No significant differences in the infection rates of HSV-1, HSV-2, CMV, or EBV were detected between two groups. Notably, EBV reactivation was greater in patients with achalasia than in controls (15.3% vs. 5.6%, p = 0.032), especially in Type I achalasia (21.0% vs. 5.6%, p = 0.008). Following PSM, EBV reactivation was associated with an increase in B cells (p = 0.001), a decrease in NK cells (p = 0.005), and lower levels of IL-6 (p = 0.02) and IL-8 (p = 0.05). Additionally, EBV reactivation group presented a greater EBV infection rate in LES (68.8% vs. 31.3%, p = 0.034), which was associated with increased neuron loss. EBV infection was detected in B and T cells of the LES, rather than neurons.

Conclusions: Although relatively low, our findings reveal an increased frequency of EBV reactivation in patients with achalasia, which may be associated with imbalanced immunity and neuron loss in LES in these subpopulations. This study provides novel insights into the role of EBV reactivation in achalasia.