Endothelial cell stimulating angiogenesis factor--a new biological marker for disease activity in ankylosing...

Endothelial cell stimulating angiogenesis factor (ESAF) is raised in conditions of neovascularization, such as may occur at the endochondral surface of the bone growth plate or in association with syndesmophyte formation. Syndesmophytes are formed in response to chronic enthesitis. Twenty unselected patients with AS were studied and enthesitis was measured clinically using a previously validated enthesitis index. Biochemical and haematological markers of disease activity were measured along with ESAF. Radiographs were scored for the degree of sacroiliitis and syndesmophyte formation and all these measurements were correlated to the enthesitis index. ESAF was raised in AS compared with normal controls. ESAF correlated positively with the enthesitis index but not with any of the biochemical or haematological indices. Higher levels of ESAF were found in those with more advanced sacroiliitis. High ESAF activity may be reflecting the angiogenic process involved in new bone formation associated with sacroiliitis and syndesmophyte formation. ESAF may be a biochemical marker for disease activity in AS.