Otsuki K, Yoda A, Toma Y, Shimizu Y, Saito H, Yanaihara T
Department of Obstetrics and Gynecology, Showa University School of Medicine, Tokyo, Japan.
Adv Exp Med Biol. 1998;443:267-71. doi: 10.1007/978-1-4757-9068-9_33.
Lactoferrin (Lf) has been found in most biological fluids including amniotic fluid and cervical mucoids in pregnant women, and released from neutrophils in response to the inflammation. As Lf possesses antimicrobial properties, it is widely considered to be an important component of the host defence against microbial infections. It is known that premature labor is caused by amniotic infection with the increase of prostaglandin production. High concentration of the inflammatory cytokines: interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) in the amniotic fluid has been known. However, changes of Lf in amniotic fluid with infection has not been reported. In the present study, Lf concentrations in amniotic fluid were measured under the intra-uterine infections state and the biological significance of Lf was investigated. The effects of Lf on the IL-6 and IL-6mRNA production in cultured amnion cells were also investigated. The concentrations of Lf and IL-6 in amniotic fluid with CAM were 8.76 +/- 0.65 micrograms/ml and 6.92 +/- 4.88 ng/ml (n = 28) respectively and both were significantly higher (p < 0.01) than those without CAM [0.86 +/- 0.81 microgram/ml and 0.34 +/- 0.25 ng/ml (n = 31)]. Significant positive correlation (r = 0.91, p < 0.01) between Lf and IL-6 levels in amniotic fluid was found. IL-6 production induced by lipopolysaccharide (LPS) (100 ng/ml) in cultured amnion cells was significantly inhibited (p < 0.05) under the physiological concentration of Lf in amnion. Total RNA was extracted from the amniotic cells by guianizine solution. RT-PCR procedure and product analysis were performed from one microgram aliquote of total RNA. beta-actin was used as an international standard and c-DNA samples were followed by 30 cycles of PCR. RT-PCR product of IL-6 mRNA was detected by Southern hybridization. Expression of IL-6 mRNA was inhibited by the addition of Lf. From the results, the possibility that Lf might suppress amniotic IL-6 production under the condition of amniotic infection is suggested. It is also suggested that Lf might act as self defence mechanism from intra-uterine infection.
乳铁蛋白（Lf）已在包括孕妇羊水和宫颈黏液在内的大多数生物体液中被发现，并在炎症反应时从中性粒细胞中释放出来。由于Lf具有抗菌特性，它被广泛认为是宿主抵御微生物感染的重要组成部分。已知早产是由羊膜感染导致前列腺素产生增加引起的。羊水内炎症细胞因子白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）、肿瘤坏死因子-α（TNF-α）浓度升高已为人所知。然而，感染时羊水中Lf的变化尚未见报道。在本研究中，测定了宫内感染状态下羊水内Lf的浓度，并研究了Lf的生物学意义。还研究了Lf对培养的羊膜细胞中IL-6及IL-6mRNA产生的影响。伴有绒毛膜羊膜炎（CAM）的羊水中Lf和IL-6的浓度分别为8.76±0.65微克/毫升和6.92±4.88纳克/毫升（n = 28），两者均显著高于无CAM者[0.86±0.81微克/毫升和0.34±0.25纳克/毫升（n = 31）]（p < 0.01）。发现羊水中Lf与IL-6水平之间存在显著正相关（r = 0.91，p < 0.01）。在羊膜中生理浓度的Lf作用下，脂多糖（LPS）（100纳克/毫升）诱导培养的羊膜细胞产生IL-6受到显著抑制（p < 0.叭）。用胍盐溶液从羊膜细胞中提取总RNA。从1微克总RNA等分试样进行逆转录-聚合酶链反应（RT-PCR）操作及产物分析。以β-肌动蛋白作为内参，c-DNA样本进行30个循环的PCR。通过Southern杂交检测IL-6mRNA的RT-PCR产物。添加Lf可抑制IL-6mRNA的表达。从结果来看，提示在羊膜感染情况下Lf可能抑制羊水IL-6的产生。还提示Lf可能作为抵御宫内感染的一种自我防御机制。
