Identification and quantification of thymosin β4 in human saliva and tears

Thymosin beta(4) (T beta(4)) is a ubiquitous, naturally occurring, 43-amino acid peptide that takes part in several biological activities including angiogenesis, inhibition of inflammation, wound healing, chemotaxis, and endothelial cell migration. Recent studies also indicate that T beta(4) accelerates corneal wound healing and downregulates several proinflamatory chemokines and cytokines. In this study, we sought to determine whether T beta(4) is naturally occurring in human tears and other human bodily fluids, such as saliva. Tear and saliva samples were analyzed by EIA to identify and quantify the amount of T beta(4) present. Around 10-20 samples were collected from each of three different age groups: 15-20, 25-35, and > 50 years old with n = 30 and n = 60 for tears and saliva, respectively. Exclusion criteria included the use of any topical ophthalmic or topical oral medication and/or history of ocular or oral surgery within the past 6 months. Tears were collected from both eyes using Schirmer's strips. Saliva samples were collected in sterile tubes and were then centrifuged to remove solid particles. T beta(4) was found in tear and saliva samples in all age groups. The concentrations ranged from 0.5-7 mu g/mL in tears and 0.2-3.6 mu g/mL in saliva. In both fluids, T beta(4) concentration varied with age and appeared to peak at ages 25-35 years. Studies are in progress to determine if T beta(4) levels in saliva and tears demonstrate a circadian rhythm during a 24-h period, as well as to confirm that they vary with age and to explore if they vary with diseased states. This is the first study to report the presence of T beta(4) in human tears and saliva. This finding raises the possibility that T beta(4) acts as an endogenous agent contributing to the rapid healing of corneal and oral wounds. Considering that T beta(4) facilitates reepithelialization and modulates anti-inflammatory mediators, T beta(4) could potentially be used therapeutically in the treatment of (a) ocular surface disease and injury of eye and (b) various oral disorders, such as periodontal disease.