Effect of saliva on buccal keratinocytes from Behcet's patients

Behcet's disease is a chronic multi-system inflammatory disorder where major recurrent aphthous oral ulceration occurs in 97-100% of patients and is characterized by slow healing and inevitable scarring. Objectives: To investigate the effect of Behcet's patients' saliva on buccal epithelial proliferative responses and growth factor release. Methods: Buccal scrapes and whole unstimulated saliva were collected from Behcet's patients (BD, n=11) and healthy control volunteers (HC, n=15) with informed consent. Cells were isolated from scrapes, resuspended in serum free keratinocyte medium (SFM) and seeded at 5000 cells/well. Whole unstimulated saliva was centrifuged and filtered (0.2µm). Cellular proliferation (MTT assay) and growth factor release from BD and HC cells were examined post 24-hours incubation with or without their respective saliva. Vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), platelet derived growth factor (PDGF-BB) were measured using ELISA. Results: BD and HC epithelial cells demonstrated similar proliferative capacity in SFM. Addition of saliva significantly stimulated cellular proliferation only in the case of HC cells (p<0.05). HC cells demonstrated EGF utilisation from the medium (SFM, 918± 40pg/ml versus HC, 493± 17pg/ml) which was not observed with BD cells (908±55pg/ml). Again, addition of saliva showed an effect only on HC cells (EGF=1035.41±62.53). For PDGF, HC cells release was significantly greater than BD (p<0.05); addition of saliva demonstrated no effect in either case. VEGF levels were similar between sample groups, and were increased significantly with the addition of saliva (p< 0.0005). Conclusions: These results indicate some dysregulation in growth factor activities in Behcet's disease. Of particular note was that HC cells appeared to utilise EGF present in SFM; whereas EGF levels remain unchanged in the presence of BD cells, suggesting an inability to process EGF. We thereby hypothesise that BD epithelial cells may contain a defective EGF receptor.