Anti‐annexin V antibodies in neuro‐Behçet patients: clinical significance and relation to disease activity

Behçet's disease (BD) is a chronic, relapsing vasculitis of unknown etiology and involvement of parenchymal central nervous system (CNS) (neuro-BD) is a serious complication and leading cause of mortality. Treatment of neuro-BD remains largely empirical, and may not adequately control the disease.1 Annexins are a group of highly conserved proteins which exert several regulatory functions on cell biology. They are involved in numerous cell processes, including vesicle trafficking, calcium signaling, cell growth, division and apoptosis. Auto-antibodies directed toward annexin I, II, V and XI have been reported, but their roles and their clinical correlates are controversial.2 It has been suggested that lymphocytes in patients with BD are relatively resistant to apoptosis mediated by anti-Fas antibody. These apoptosis-resistant, or long-lived, lymphocytes may be involved in the chronic and recurrent intraocular inflammation seen in these patients.3 Annexin V has a high affinity for phospholipids, playing a pivotal role in the regulation of coagulation cascade and its antibodies were found in patients with arterial or venous thrombosis, especially those with autoimmune rheumatic diseases.2 The aim of this study was to measure the level of serum anti-annexin V antibodies in BD patients and to study their significance in relation to neurological manifestations. Fifty-three BD patients (44 male and nine female) satisfying the International Study Group for Behçet's Disease new set of diagnostic criteria,4 were included in the present study. They were recruited consecutively from the Rheumatology and Neurology Departments and outpatient clinics, Cairo University Hospitals with a mean age of 35.54 ± 8.85 years and mean disease duration of 8.33 ± 5.84 years. Thirty age- and sex-matched healthy volunteers serving as controls with a mean age of 32.87 ± 5.05 years were also included. Full history-taking, clinical examination and skin pathergy tests were carried out for all patients, and investigations including lipid profile were performed for both patients and controls. Medications received by the patients were considered and patients receiving corticosteroids for management of their disease were not excluded. Disease activity was assessed using the Behçet Disease Current Activity Form (BDCAF)5 score. The patients were divided into two groups: group I including those with neurological manifestations (neuro-BD) and group II for those without. Assessment of serum immunoglobulin G (IgG) anti-annexin V antibody titres were performed using the zymutest anti-Annexin IgG ELISA kit (Hyphen-BioMed, Neuville-Sur-Oise, France). The study was approved by the local university ethics committee and the study conforms to the provisions of the 1995 Declaration of Helsinki. All patients gave their informed consent prior to their inclusion in the study. Statistical Package for Social Science (SPSS) program version 15 (SPSS Inc., Chicago, IL, USA) was used for analysis of data. Data was presented as mean ± standard deviation (SD). Mann–Whitney test was used for analysis of two quantitative data. Spearman's correlation was used for detection of the relation between two variables. P-value was considered significant at < 0.05. The study included 53 BD patients, 21 (39.62%) with neuro-BD and 32 without. The neurological manifestations were due to CNS involvement in the form of headache present in 16, cerebral thrombosis in 13, hemiplegia in eight, intracranial hemorrhage in five, ataxia in five and seizures in three. Their demographic, clinical and laboratory features are presented in Table 1. Serum anti-annexin antibody V was significantly higher in BD patients (49.24 ± 14.93 AU/mL) compared to the control (7.32 ± 3.42 AU/mL) and obviously higher in those with neuro- BD (56.08 ± 17.09 AU/mL) compared to those without (44.75 ± 11.53 AU/mL) (P = 0.012) as presented in Fig. 1. The disease activity score (BDCAF) was significantly higher in those with neuro-BD (2.9 ± 1.51) compared to those without (1.97 ± 1.36) (P = 0.027). High-density lipoprotein was significantly higher in women (81.33 ± 11.12 mg/dL) compared to men (61.18 ± 15.93 mg/dL) (P < 0.0001). There was a tendency to a higher annexin level in men (49.61 ± 15.31 AU/mL) compared to women (47.42 ± 13.58 AU/mL) (P = 0.67). Serum annexin levels in BD patients significantly correlated with disease activity (BDCAF) (r = 0.57, P = 0.0001), steroid dose (r = 0.31, P = 0.025), creatinine (r = 0.33, P = 0.016) and age (r = 0.44, P = 0.001). In the current study, serum anti-annexin antibody V was significantly higher in BD patients compared to controls. It has been proposed that thrombosis in BD is due to disruption of the annexin V shield by antibodies. Measuring these antibodies may be of value in confirming the diagnosis and evaluating the risk of venous and arterial thrombosis in BD patients. Annexin V plays a potent antithrombotic role and the increased level of its antibodies may add to the explanation of the significantly increased level in those with neurological manifestations with a thrombotic pathogenesis.6 In the present study, serum anti-annexin V antibodies were significantly higher in neuro-BD patients compared to those without. Moreover, the disease activity score (BDCAF) was significantly higher in neuro-BD patients. In agreement with this finding, it has been found that apoptosis, as presented by annexin V, is one of the mechanisms contributing to neuronal degeneration in ischemic stroke.7 It has also been suggested that high levels of free fatty acids induce oxidative stress damage in human brain microvascular endothelial cells and result in apoptosis.8 Serum annexin level in BD patients significantly correlated with disease activity, steroid dose, creatinine and age. It has been reported that apoptosis of T-lymphocytes, as expressed by annexin V, showed a significant correlation with stress and age.9 In another study, apoptosis as resembled by annexin V was increased with active phases of the disease and was reduced in remission.10 In conclusion, anti-annexin antibodies could be considered as a risk for developing neurological manifestations in BD patients. In addition to its known role as an indicator of apoptosis, it could also be well thought of as a marker of disease activity. Larger-scale multicentre longitudinal studies are required together with other extended investigations on the brain and nervous system to confirm its role in the pathogenesis of neuro-BD. This would throw light on considering medications with anti-apoptotic effect among the management armamentarium in BD. None.