Foster David R, Landowski Christopher P, Zheng Xiaomei, Amidon Gordon L, Welage Lynda S
Department of Pharmacy Practice, Purdue University School of Pharmacy and Pharmaceutical Sciences, West Lafayette, IN, United States.
Pharmacol Res. 2009 Mar;59(3):215-20. doi: 10.1016/j.phrs.2008.11.001. Epub 2008 Nov 25.
The di/tri-peptide transporter h-PEPT1 plays an important role in the oral absorption of di/tri-peptides and numerous drugs. Inflammatory conditions may influence intestinal xenobiotic transporter function; however, the effects of inflammation on h-PEPT1 have not been well described. This study was conducted to determine the effects of the inflammatory cytokine interferon-gamma (IFN-gamma) on h-PEPT1 mediated dipeptide absorption. Caco-2 monolayers were grown on permeable supports. The effective apical-to-basolateral permeability (P(eff)) of glycylsarcosine (Gly-Sar) was measured following incubation with IFN-gamma or control media. Additional experiments were conducted at 4 degrees C, and with escalating concentrations of Gly-Sar. h-PEPT1 expression was determined using semiquantitative RT-PCR. IFN-gamma 50 ng/ml increased Gly-Sar P(eff) 28.6% compared to controls (p=0.03). In experiments conducted at 4 degrees C, Gly-Sar P(eff) decreased 39.6% in IFN-gamma treated cells (p=0.003) and 28.4% in controls (p=0.006). In controls and IFN-gamma treated cells, concentration dependent transport was seen with escalating concentrations of Gly-Sar. Compared to controls, IFN-gamma 50 and 100 ng/ml increased h-PEPT1 mRNA expression by 14.2% and 11.5%, respectively (p=0.019). In summary, IFN-gamma increases h-PEPT1 expression and permeation of the dipeptide Gly-Sar in Caco-2 monolayers. These findings imply that intestinal absorption of peptides and peptidomimetic drugs may be increased in certain inflammatory conditions.
二肽/三肽转运体h-PEPT1在二肽/三肽及众多药物的口服吸收中发挥着重要作用。炎症状态可能会影响肠道外源性物质转运体的功能；然而，炎症对h-PEPT1的影响尚未得到充分描述。本研究旨在确定炎性细胞因子γ-干扰素（IFN-γ）对h-PEPT1介导的二肽吸收的影响。将Caco-2单层细胞培养在可渗透支持物上。在与IFN-γ或对照培养基孵育后，测量甘氨酰肌氨酸（Gly-Sar）的有效顶侧至基底侧渗透率（P(eff)）。在4℃下进行了额外实验，并使用了浓度递增的Gly-Sar。使用半定量RT-PCR测定h-PEPT1的表达。与对照组相比，50 ng/ml的IFN-γ使Gly-Sar的P(eff)增加了28.6%（p=0.03）。在4℃进行的实验中，IFN-γ处理的细胞中Gly-Sar的P(eff)下降了39.6%（p=0.003），对照组下降了28.4%（p=0.006）。在对照组和IFN-γ处理的细胞中，随着Gly-Sar浓度的增加，观察到浓度依赖性转运。与对照组相比，50和100 ng/ml的IFN-γ分别使h-PEPT1 mRNA表达增加了14.2%和11.5%（p=0.019）。总之，IFN-γ增加了Caco-2单层细胞中h-PEPT1的表达及二肽Gly-Sar的渗透。这些发现表明，在某些炎症状态下，肽类和拟肽药物的肠道吸收可能会增加。
