Stites S W, Nelson M E, Wesselius L J
Department of Medicine, University of Kansas School of Medicine, Kansas City, USA.
Chest. 1995 Jun;107(6):1681-5. doi: 10.1378/chest.107.6.1681.
Transferrin serves as the primary iron transport protein in serum, but it also is present in the lower respiratory tract where it has antioxidant and antibacterial properties. Prior studies indicate that patients with respiratory failure (RF) due to ARDS have increased concentrations of transferrin in the lower respiratory tract, which is attributed to increased lung vascular permeability. It is unclear whether mechanical ventilation contributes to increased lung transferrin content in patients with ARDS, although mechanical ventilation may increase lung microvascular permeability. To assess whether mechanical ventilation in patients with RF due to causes other than ARDS is also associated with increased respiratory tract concentrations of transferrin, we compared transferrin concentrations in serum and lung lavage fluid obtained from 12 mechanically ventilated patients with RF attributable to COPD, 6 patients with ARDS, and 15 healthy volunteers. Serum transferrin concentrations in patients with RF due to COPD were variable, but mean concentrations were similar to those in control subjects (336 +/- 58 vs 307 +/- 9 [SE] mg/dL), whereas serum transferrin concentrations were decreased in patients with ARDS (182 +/- 68 mg/dL; p < 0.05). Compared with control subjects, lavage fluid recovered from patients with RF due to COPD contained significantly decreased concentrations of transferrin (1.56 +/- 0.24 vs 4.27 +/- 0.44 micrograms/mL; p < 0.001), whereas transferrin concentrations in lavage fluid recovered from patients with ARDS were increased (15.72 +/- 2.01 micrograms/mL; p < 0.001). Transferrin concentrations of lavage fluid also were decreased in COPD patients when normalized for lavage fluid protein content (4.35 +/- 0.72 vs 19.96 +/- 3.13 micrograms/mg in control subjects, p < 0.001). These data indicate that mechanical ventilation of patients with COPD is associated with decreased lung transferrin concentrations, in contrast to an increased transferrin concentration found in patients with ARDS. Decreased transferrin concentrations in the lower respiratory tract may decrease defenses against oxidant injury and bacterial infection in patients with RF due to COPD.
转铁蛋白是血清中主要的铁转运蛋白，但它也存在于下呼吸道，在那里具有抗氧化和抗菌特性。先前的研究表明，因急性呼吸窘迫综合征（ARDS）导致呼吸衰竭（RF）的患者下呼吸道中转铁蛋白浓度升高，这归因于肺血管通透性增加。目前尚不清楚机械通气是否会导致ARDS患者肺转铁蛋白含量增加，尽管机械通气可能会增加肺微血管通透性。为了评估因ARDS以外的原因导致RF的患者进行机械通气是否也与呼吸道转铁蛋白浓度增加有关，我们比较了12例因慢性阻塞性肺疾病（COPD）导致RF的机械通气患者、6例ARDS患者和15名健康志愿者血清及肺灌洗液中的转铁蛋白浓度。因COPD导致RF的患者血清转铁蛋白浓度各不相同，但平均浓度与对照组相似（336±58 vs 307±9[SE]mg/dL），而ARDS患者的血清转铁蛋白浓度降低（182±68 mg/dL；p<0.05）。与对照组相比，因COPD导致RF的患者回收的灌洗液中转铁蛋白浓度显著降低（1.56±0.24 vs 4.27±0.44微克/毫升；p<0.001），而ARDS患者回收的灌洗液中转铁蛋白浓度升高（15.72±2.01微克/毫升；p<0.001）。当以灌洗液蛋白含量进行标准化时，COPD患者灌洗液中的转铁蛋白浓度也降低（4.35±0.72 vs对照组的19.96±3.13微克/毫克，p<0.001）。这些数据表明，与ARDS患者转铁蛋白浓度升高相反，COPD患者进行机械通气与肺转铁蛋白浓度降低有关。下呼吸道转铁蛋白浓度降低可能会降低因COPD导致RF的患者对抗氧化损伤和细菌感染的防御能力。
