School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia.
Inflamm Bowel Dis. 2010 Aug;16(8):1340-51. doi: 10.1002/ibd.21241.
We have previously demonstrated that inhibition of dipeptidyl peptidase (DP) activity partially attenuates dextran sulfate sodium (DSS) colitis in mice. The aim of this study was to further investigate the mechanisms of this protection.
Wildtype (WT) and DPIV(-/-) mice consumed 2% DSS in drinking water for 6 days to induce colitis. Mice were treated with saline or the DP inhibitors Ile-Pyrr-(2-CN)*TFA or Ile-Thia. DP mRNA and enzyme levels were measured in the colon. Glucagon-like peptide (GLP)-2 and GLP-1 concentrations were determined by radioimmunoassay, regulatory T-cells (Tregs) by fluorescence activated cell sorting (FACS) on FOXp3+T cells in blood, and neutrophil infiltration assessed by myeloperoxidase (MPO) assay.
DP8 and DP2 mRNA levels were increased (P < 0.05) in WT+saline mice compared to untreated WT mice with colitis. Cytoplasmic DP enzyme activity was increased (P < 0.05) in DPIV(-/-) mice at day 6 of DSS, while DP2 activity was increased (P < 0.05) in WT mice with colitis. GLP-1 (63%) and GLP-2 (50%) concentrations increased in WT+Ile-Pyrr-(2-CN)*TFA mice compared to day-0 controls. MPO activity was lower in WT+Ile-Thia and WT+Ile-Pyrr-(2-CN)*TFA treated mice compared to WT+saline (P < 0.001) at day 6 colitis.
DP expression and activity are differentially regulated during DSS colitis, suggesting a pathophysiological role for these enzymes in human inflammatory bowel disease (IBD). DP inhibitors impaired neutrophil recruitment and maintenance of the Treg population during DSS-colitis, providing further preclinical evidence for the potential therapeutic use of these inhibitors in IBD. Finally, DPIV appears to play a critical role in mediating the protective effect of DP inhibitors.
我们之前已经证明，抑制二肽基肽酶（DP）活性可部分减轻葡聚糖硫酸钠（DSS）诱导的小鼠结肠炎。本研究的目的是进一步研究这种保护作用的机制。
野生型（WT）和 DPIV（-/-）小鼠饮用 2% DSS 饮用水 6 天以诱导结肠炎。用生理盐水或 DP 抑制剂 Ile-Pyrr-（2-CN）*TFA 或 Ile-Thia 处理小鼠。测量结肠中的 DP mRNA 和酶水平。通过放射免疫测定法测定胰高血糖素样肽（GLP）-2 和 GLP-1 浓度，通过血液中 FOXp3+T 细胞的荧光激活细胞分选（FACS）测定调节性 T 细胞（Tregs），并通过髓过氧化物酶（MPO）测定法评估中性粒细胞浸润。
与未治疗的 WT 结肠炎小鼠相比，WT+盐水组小鼠的 DP8 和 DP2 mRNA 水平升高（P <0.05）。在 DSS 第 6 天，DPIV（-/-）小鼠的细胞质 DP 酶活性升高（P <0.05），而 WT 结肠炎小鼠的 DP2 活性升高（P <0.05）。与第 0 天对照相比，WT+Ile-Pyrr-（2-CN）*TFA 小鼠的 GLP-1（63%）和 GLP-2（50%）浓度升高。与 WT+盐水组相比，WT+Ile-Thia 和 WT+Ile-Pyrr-（2-CN）*TFA 治疗的小鼠在第 6 天结肠炎时 MPO 活性更低（P <0.001）。
DP 的表达和活性在 DSS 结肠炎期间呈差异调节，提示这些酶在人类炎症性肠病（IBD）中的病理生理作用。DP 抑制剂在 DSS-结肠炎期间损害中性粒细胞募集和 Treg 群体的维持，为这些抑制剂在 IBD 中的潜在治疗用途提供了进一步的临床前证据。最后，DPIV 似乎在介导 DP 抑制剂的保护作用中发挥关键作用。
