Sosne Gabriel, Albeiruti Abdul-Rahman, Hollis Brian, Siddiqi Atif, Ellenberg David, Kurpakus-Wheater Michelle
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Scott Hall 8314, 540 E. Canfield Avenue, Detroit, MI 48201, USA.
Exp Eye Res. 2006 Sep;83(3):502-7. doi: 10.1016/j.exer.2006.02.001. Epub 2006 Apr 21.
Thymosin beta-4 (Tbeta(4)) is known to promote ocular wound healing, to decrease ocular inflammation, and to have anti-apoptotic effects on corneal epithelium. In this study, the effect of Tbeta(4) on the survival of human ocular surface epithelial cells exposed to benzalkonium chloride (BAK) was measured. Human conjunctival epithelial cells (HC0597) or human corneal epithelial cells (HCET) were treated with 0%, 0.001%, 0.01%, or 0.1% BAK for 15 min. After 3 or 24h of recovery in culture medium containing 1 microg/ml Tbeta(4), a dosage that has been demonstrated effective in several published studies, DNA synthesis was measured using a colorimetric BrdU incorporation assay. Both conjunctival and corneal epithelial DNA synthesis was inhibited by BAK in a dose-dependent manner. Tbeta(4) did not protect the epithelial cells from BAK-induced inhibition of proliferation. To assess the ability of Tbeta(4) to prevent apoptosis, epithelial cells were treated with 0.01% BAK+Tbeta(4) and cell death was measured using a colorimetric assay. BAK-induced apoptosis increased throughout the duration of the assay, which was carried out to 5 days in culture. Treatment of HC0597 cells with Tbeta(4) significantly inhibited the apoptosis shown to be initiated by BAK. Treatment of non-transformed human corneal epithelial cells (HCEC) with Tbeta(4) also significantly inhibited the apoptosis shown to be initiated by BAK at later times in culture. Ocular solutions containing BAK as a preservative are typically used for extended periods of time. This study suggests that Tbeta(4) may be able to overcome the apoptotic side effect of BAK, and may be a useful additive to solutions containing this preservative.
胸腺素β-4（Tbeta(4)）已知可促进眼部伤口愈合、减轻眼部炎症，并对角膜上皮具有抗凋亡作用。在本研究中，测定了Tbeta(4)对暴露于苯扎氯铵（BAK）的人眼表上皮细胞存活的影响。将人结膜上皮细胞（HC0597）或人角膜上皮细胞（HCET）用0%、0.001%、0.01%或0.1%的BAK处理15分钟。在含有1微克/毫升Tbeta(4)（这一剂量在多项已发表研究中已证明有效）的培养基中恢复培养3或24小时后，使用比色法BrdU掺入试验测量DNA合成。结膜和角膜上皮的DNA合成均被BAK以剂量依赖性方式抑制。Tbeta(4)不能保护上皮细胞免受BAK诱导的增殖抑制。为评估Tbeta(4)预防凋亡的能力，上皮细胞用0.01% BAK + Tbeta(4)处理，并使用比色法测定细胞死亡情况。在整个长达5天的培养试验期间，BAK诱导的凋亡不断增加。用Tbeta(4)处理HC0597细胞可显著抑制由BAK引发的凋亡。用Tbeta(4)处理未转化的人角膜上皮细胞（HCEC）在培养后期也可显著抑制由BAK引发的凋亡。含有BAK作为防腐剂的眼用溶液通常会长期使用。本研究表明，Tbeta(4)可能能够克服BAK的凋亡副作用，并且可能是含有这种防腐剂的溶液的一种有用添加剂。
