SALIVARY EGF REGULATES EOSINOPHIL-DERIVED TGF-ALPHA EXPRESSION IN HAMSTER ORAL WOUNDS

Using hamster as an oral wound healing model, we examined eosinophils and their expression of transforming growth factor-alpha (TGF-alpha) a nd transforming growth factor-beta 1 (TGF-beta 1). Oral wounds healed approximately two times faster than their cutaneous counterparts. Eosi nophils infiltrated prominently into oral wounds; however, unlike the dual expression of TGF-alpha and TGF-beta 1 in skin wounds, oral wound -associated eosinophils expressed TGF-beta 1, but not TGF-alpha. Becau se saliva is present in oral environments and contains epidermal growt h factor (EGF) and TGF-alpha, sialoadenectomy was performed in this mo del to determine whether the lack of TGF-alpha expression by eosinophi ls in oral wounds is due to the presence of salivary EGF and/or TGF-al pha. We found that eosinophils in sialoadenectomized hamsters did expr ess TGF-alpha during oral wound healing but that such expression was s uppressed when EGF was added to their drinking water. Taken together, our findings suggest that eosinophil-derived TGF-alpha and salivary TG F-alpha/EGF may have complementary roles in contributing to TGF-alpha in oral wound healing.