Iqbal Majid, Ho Hay Lam, Petropoulos Sophie, Moisiadis Vasilis G, Gibb William, Matthews Stephen G
Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
PLoS One. 2012;7(8):e43022. doi: 10.1371/journal.pone.0043022. Epub 2012 Aug 13.
Placental P-glycoprotein (P-gp) acts to protect the developing fetus from exogenous compounds. This protection declines with advancing gestation leaving the fetus and fetal brain vulnerable to these compounds and potential teratogens in maternal circulation. This vulnerability may be more pronounced in pregnancies complicated by infection, which is common during pregnancy. Pro-inflammatory cytokines (released during infection) have been shown to be potent inhibitors of P-gp, but nothing is known regarding their effects at the developing blood-brain barrier (BBB). We hypothesized that P-gp function and expression in endothelial cells of the developing BBB will be inhibited by pro-inflammatory cytokines. We have derived brain endothelial cell (BEC) cultures from various stages of development of the guinea pig: gestational day (GD) 50, 65 (term ~68 days) and postnatal day (PND) 14. Once these cultures reached confluence, BECs were treated with various doses (10(0)-10(4 )pg/mL) of pro-inflammatory cytokines: interleukin-1β (IL-1β), interleukin-6 (IL-6) or tumor necrosis factor- α (TNF-α). P-gp function or abcb1 mRNA (encodes P-gp) expression was assessed following treatment. Incubation of GD50 BECs with IL-1β, IL-6 or TNF-α resulted in no change in P-gp function. GD65 BECs displayed a dose-dependent decrease in function with all cytokines tested; maximal effects at 42%, 65% and 34% with IL-1β, IL-6 and TNF-α treatment, respectively (P<0.01). Inhibition of P-gp function by IL-1β, IL-6 and TNF-α was even greater in PND14 BECs; maximal effects at 36% (P<0.01), 84% (P<0.05) and 55% (P<0.01), respectively. Cytokine-induced reductions in P-gp function were associated with decreased abcb1 mRNA expression. These data suggest that BBB P-gp function is increasingly responsive to the inhibitory effects of pro-inflammatory cytokines, with increasing developmental age. Thus, women who experience infection and take prescription medication during pregnancy may expose the developing fetal brain to greater amounts of exogenous compounds - many of which are considered potentially teratogenic.
胎盘P-糖蛋白（P-gp）可保护发育中的胎儿免受外源性化合物的影响。随着孕期的推进，这种保护作用会减弱，使胎儿及其脑部易受母体循环中的这些化合物及潜在致畸原的影响。在并发感染的妊娠中，这种易感性可能更为明显，而感染在孕期很常见。促炎细胞因子（在感染期间释放）已被证明是P-gp的强效抑制剂，但关于它们对发育中的血脑屏障（BBB）的影响却一无所知。我们推测，促炎细胞因子会抑制发育中的血脑屏障内皮细胞中P-gp的功能和表达。我们从豚鼠发育的不同阶段获得了脑内皮细胞（BEC）培养物：妊娠第50天、第65天（足月约68天）和出生后第14天。这些培养物汇合后，用不同剂量（10⁰ - 10⁴ pg/mL）的促炎细胞因子处理BEC：白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）或肿瘤坏死因子-α（TNF-α）。处理后评估P-gp功能或abcb1 mRNA（编码P-gp）的表达。用IL-1β、IL-6或TNF-α孵育妊娠第50天的BEC后，P-gp功能无变化。妊娠第65天的BEC在所有测试细胞因子作用下功能呈剂量依赖性下降；用IL-1β、IL-6和TNF-α处理时，最大效应分别为42%、65%和34%（P<0.01）。IL-1β、IL-6和TNF-α对出生后第14天BEC的P-gp功能抑制作用更大；最大效应分别为36%（P<0.01）、84%（P<0.05）和55%（P<0.01）。细胞因子诱导的P-gp功能降低与abcb1 mRNA表达减少有关。这些数据表明，随着发育年龄的增加，血脑屏障P-gp功能对促炎细胞因子抑制作用的反应越来越敏感。因此，孕期感染并服用处方药的女性可能会使发育中的胎儿脑部接触到更多外源性化合物——其中许多被认为具有潜在致畸性。
