中文摘要：

目的探讨牛乳铁蛋白（bLF）在体外对大鼠空肠上皮细胞株（IEC-6）细胞增殖和对脂多糖（LPS）诱导的细胞炎性反应的影响及机制。方法体外培养IEC-6细胞，四甲基偶氮唑蓝（MTT）法检测不同浓度bLF时IEC-6细胞的活性，5-溴脱氧尿苷（Brdu）标记检测bLF对细胞增殖能力的影响，荧光定量PCR及酶联免疫吸附试验（ELISA）法检测白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）、白细胞介素-8（IL-8）和肿瘤坏死因子-α（TNF-α）的mRNA水平，Western blot检测bLF对LPS诱导的炎症信号通路中丝裂原活化蛋白激酶（MAPK）及核因子-κB（NF-κB）水平。结果bLF在体外可促进IEC-6细胞活性和增生能力，并呈浓度依赖效应（F＝3.825、5.861，均P〈0.05），当处理质量浓度为100 mg/L时，IEC-6细胞活性和增殖能力逐渐增强（q＝5.240、3.765，均P〈0.05）。应用100 mg/L质量浓度的bLF预处理IEC-6细胞可明显降低IL-1β、IL-6及TNF-α 的mRNA表达水平（q＝14.28、10.12、16.45，均P〈0.001），并降低IL-6和TNF-α蛋白的表达（q＝15.06、6.74，均P〈0.001）。与单独LPS组相比，应用100 mg/L质量浓度的bLF预处理IEC-6细胞可使MAPK/NF-κB通路的激活水平下降（q＝12.96、18.54，均P〈0.001）。结论bLF在体外可促进大鼠IEC-6细胞活性及增殖能力，并通过抑制MAPK/NF-κB信号通路起到抑制LPS诱导的炎性反应的作用。

英文摘要：

Objective To evaluate the effects and mechanisms of bovine lactoferrin （bLF） on cell viability, proliferation, and the protective roles in intestinal epithelial cell - 6 （ IEC - 6 ） treated by lipopolysaccharide （LPS）. Methods The rat jejunum epithelial cell lines IEC - 6 were cultured in vitro. The effects of bLF on cell viability and proliferation in IEC - 6 cells were detected by 3 - （4,5 - dimethyl - 2 - thiazolyl） - 2,5 - diphenyl - 2 - H - tetrazolium bromide （MTT） assay and 5 - Bromo - deoxyuridine （Brdu） assay, respectively. Inflammatory cytokines and their mRNA of interleukin - 1β （ IL - 1β）, interleukin - 6 （ IL - 6）, tumor necrosis factor - α （ TNF -α） and interleukin - 8 （IL- 8） were analyzed by real- time PCR and enzyme- linked immunosorbent assay（ELISA）. Western blot was used to measure the levels of mitogen - activated protein kinase （MAPK） activation and nuclear factor kappa β （ NF - kB ） nuclear translocation. Results Dose dependent effects of bLF on cell viability and proliferation were observed in IEC -6 cells in vitro（ F = 3. 825,5. 861, all P 〈 0.05 ）, especially in a dose of 100 mg/L, and bLF significantly stimulated cell viability and proliferation compared with non - treatment group （ q = 5. 240,3. 765, all P 〈 0.05 ）. The mRNA levels of IL - 1β, IL - 6 and TNF - α were decreased by co - stimulation of bLF and LPS compared with the LPS treatments alone in IEC - 6 cells in vitro（ q = 14.28,10.12,16.45, all P 〈 0. 001 ）. The secretion of IL - 6 and TNF - α was also decreased by co -stimulation of bLF and LPS （q = 15.06,6.74 ,all P 〈0.01 ）. In vitro, bLF treatment at dose of 100 mg/L could inhibit the activation of MAPK/NF - KB signal pathway induced by LPS （ q = 12.96,18.54, all P 〈0. 001 ）. Conclusion In vitro, bLF can promote IEC - 6 viability and proliferation, and have anti - inflammatory effects via inhibited activation of MAPK/NF - kB nuclear translocation.