The serum angiotensin converting enzyme and lysozyme levels in patients with ocular involvement of autoimmune and infectious diseases

BACKGROUND Increased serum levels of angiotensin converting enzyme and lysozyme are considered as inflammatory markers for diagnosis of sarcoidosis which is an autoimmune inflammatory disease. The purpose of this study is to evaluate the significance of differences in serum angiotensin converting enzyme and lysozyme levels of patients with ocular involvement of other autoimmune inflammatory and infectious diseases. METHODS This is a prospective study involving patients with ankylosing spondylitis, behcet's disease, presumed sarcoidosis, presumed latent tuberculosis, presumed latent syphilis, and control group. The serum levels of angiotensin converting enzyme and lysozyme were analyzed by enzyme-linked immunosorbent assay. Bonnferoni analysis was used to assess pairwise comparisons between the groups. RESULTS There was a significant increase in serum angiotensin converting enzyme level in patients with presumed sarcoidosis compared to ankylosing spondylitis (p = 0.0001), behcet's disease (p = 0.0001), presumed latent tuberculosis (p = 0.0001), presumed latent syphilis (p = 0.0001), and control group (p = 0.0001). The increase in serum lysozyme level was significant for patients with presumed sarcoidosis with respect to ankylosing spondylitis (p = 0.0001), behcet's disease, (p = 0.0001) presumed latent tuberculosis (p = 0.001), presumed latent syphilis (p = 0.033), and control group (p = 0.0001). CONCLUSION Elevated serum angiotensin converting enzyme levels are significant for patients with presumed sarcoidosis compared to ocular involvement of other autoimmune diseases such as behcet's disease and ankylosing spondylitis, and ocular involvement of infectious diseases such as presumed latent tuberculosis and presumed latent syphilis. However, elevated serum lysozyme level might be also detected in ocular involvement of infectious diseases such as presumed latent tuberculosis and presumed latent syphilis. TRIAL REGISTRATION TRIAL REGISTRATION NUMBER NCT02627209. Date of registration: 12/09/2015.