To examine the density and the distribution of corneal Langerhans cells (LCs) and to compare the results with dry-eye related parameters and disease activity in ankylosing spondylitis(AS).Methods
Twenty four AS patients (mean age: 41.8±9.8 years) with various degree of disease activity and twenty four healthy subjects (mean age: 47.9 ± 16.4 years) were enrolled. Ocular surface disease index (OSDI), lid parallel conjunctival folds (LIPCOF), tear break up time (TBUT), and Schirmer test (ST) were evaluated. In addition, central and peripheral LCs numbers and Langerhans cell morphology (LCM) were assessed with in vivo laser confocal microscopy.Results
Tear production was greatly suppressed in patients with more severe systemic inflammation according to the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and C-reactive protein (CRP) (BASDAI≤4.0 vs BASDAI>4.0 10.2±8.5 vs 4.0±5.3; CRP≤5.0 vs CRP>5.0 17.2±4.2 vs 3.9±5.5 p<0.05 for all). LCs densities and central LCM were greater in AS patients than in the controls (LC density: 77.5±44.9 vs 23.8±33.8 and central LCM: 1.7±0.7 vs 0.95±0.75 p<0.05 for all).Conclusion
Greater corneal LC density and LCM may reflect an increased activation of the corneal innate immune system, which correlates with the systemic activity of AS even without ocular symptoms. Higher systemic inflammation might impair tear production, and it might partly explain the dry eye mechanism.