Correlation of anti-γ/ε nicotinic acetylcholine receptor antibody levels with anti-desmoglein 1,3 antibody levels and disease severity in pemphigus vulgaris

Background A role for nondesmoglein antigens in the pathogenesis of pemphigus vulgaris (PV) has been suggested in several studies. Acetylcholine receptors (AchR), are one of the most important groups of these antigens. However, the exact role of both antimuscarinic (m) and nicotinic (n) AchR antibodies (Abs) is still controversial. Aim To evaluate anti-desmoglein (Dsg)1, Dsg 3 and anti-gamma/epsilon nAchR Abs values in patients with PV before and 3 months after rituximab (RTX) treatment, and to assess their correlation with disease severity. Methods In total, 75 patients with PV (26 men, 49 women) who were planned to receive RTX were enrolled. Disease activity was assessed by using the Pemphigus Disease Area Index (PDAI). Using ELISA, anti-Dsg1,3 and anti-gamma/epsilon nAchR Abs were determined at baseline and 3 months after RTX treatment. Results At baseline, 53.33% patients had positive values for anti-Dsg1, 89.33% for anti-Dsg3 and 13.33% for anti-gamma/epsilon nAchR Abs. All patients with positive anti-gamma/epsilon nAchR Abs had the mucocutaneous phenotype. PDAI, anti-Dsg1,3 and anti-gamma/epsilon nAchR values were dramatically decreased 3 months after RTX infusion (P < 0.001). There was a significant positive correlation between disease activity and anti-gamma/epsilon nAchR values at baseline (P = 0.04), whereas no significant correlation was observed between anti-Dsg1,3 and anti-gamma/epsilon nAchR values at baseline and 3 months after RTX infusion. Conclusion The reduction in anti-gamma/epsilon nAchR Abs with clinical improvement in this study may suggest a synergic role for anti-gamma/epsilon nAchR Abs with anti-Dsg1,3 Abs, or it could be an epiphenomenon.