Identification and quantification of thymosin beta4 in human saliva and tears.

Thymosin beta(4) (Tbeta(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 Tbeta(4) accelerates corneal wound healing and downregulates several proinflamatory chemokines and cytokines. In this study, we sought to determine whether Tbeta(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 Tbeta(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. Tbeta(4) was found in tear and saliva samples in all age groups. The concentrations ranged from 0.5-7 mug/mL in tears and 0.2-3.6 mug/mL in saliva. In both fluids, Tbeta(4) concentration varied with age and appeared to peak at ages 25-35 years. Studies are in progress to determine if Tbeta(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 Tbeta(4) in human tears and saliva. This finding raises the possibility that Tbeta(4) acts as an endogenous agent contributing to the rapid healing of corneal and oral wounds. Considering that Tbeta(4) facilitates reepithelialization and modulates anti-inflammatory mediators, Tbeta(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.

Thymosin beta(4) reduces lethality and down-regulates inflammatory mediators in endotoxin-induced septic shock.

Thymosin beta(4) (Tbeta(4)), a highly conserved peptide with immunomodulatory properties, is the major actin-sequestering peptide in mammalian cells. Recent studies have established that Tbeta(4) can accelerate wound healing in full thickness skin wounds and following burn injuries to the cornea. In the eye studies, the accelerated healing due to Tbeta(4) was accompanied by a significant reduction in polymorphonuclear leukocyte (PMN) infiltration and a several-fold decrease in interleukin-1beta (p< or =0.015) and 6-keto-prostaglandin F(1alpha) (6-keto-PGF1alpha, p< or =0.05). Given the recognized role of proinflammatory cytokines in septic shock and of extracellular F- and G-actin in the pathophysiology of multiple organ dysfunction, we have investigated the role of Tbeta(4) in sepsis. We report that an LD(50) dose of LPS (24 mg/kg) in rats resulted in a significant reduction of Tbeta(4) levels in the blood. Furthermore, administration of 100 microg of Tbeta(4) immediately following and at 2 and 4 h after an LD(50) dose of LPS (60 mg/kg) in mice significantly reduced mortality rates (p< or =0.024) and lowered blood levels of a number of inflammatory cytokines, eicosanoids, and other molecules that are highly elevated following endotoxin administration. In studies in human subjects given low doses of endotoxin (4 ng/kg LPS) and in patients with septic shock, we have also observed significant decreases in blood levels of Tbeta(4). The rapid disappearance of Tbeta(4) in the blood following LPS administration or during septic shock suggests that Tbeta(4) may be involved in early events leading to activation of the inflammatory cascade and ultimately the clinical sequelae of sepsis. The results of this study indicate that Tbeta(4) may have utility in the clinic in the treatment of septic shock and in syndromes associated with actin toxicities.