Objectives: To measure inducible human HSP70 in the serum and saliva of BD patients and healthy volunteers (HV) and HSP70 specific IgG antibodies.
Methods: Saliva samples were collected from BD patients (n=57) and healthy volunteers (HV n=19) according to UK Ethics approval. Saliva was centrifuged and stored at -20°C. Plasma samples (BD, N=25; HV, n=12) were separated from whole EDTA blood following density gradient centrifugation and stored at -20°C. Inducible HSP70 was assayed in saliva and plasma using a high sensitivity ELISA. The results are expressed in ng/ml. IgG antibodies were analysed by indirect ELISA using recombinant human HSP70. The results are expressed as end point titre where the background cut off was 0.2 OD units. Statistical analysis was carried out using one way ANOVA, Student's t test and Mann-Whitney-U tests.
Results:The level of HSP70 in BD saliva was significantly higher than in HV (Mann-Whitney-U p<0.001). There was no significant difference between the levels of HSP70 in the serum of BD vs. HV (p=0.9015). Similarly, the levels of HSP70 in HV saliva and serum were not significantly different. However, there was a marked elevation in the BD saliva compared with serum (p<0.0001). IgG antibody responses to recombinant Human HSP70 were also significantly elevated in BD vs. HV (p<0.001).
Conclusion: Behçet's disease shows many of the hallmarks of autoimmunity but is often described as an autoinflammatory condition. This is the first evidence that inducible HSP70 is elevated in the saliva of BD patients compared with HV and may contribute to a pro-inflammatory milieu driving the oral manifestations of the disease.