Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL/CPM), Faculty of Pharmacy, University of Lisbon, Avenida Professor Gama Pinto, 1649-003, Lisbon, Portugal.
Neurochem Res. 2013 Mar;38(3):644-59. doi: 10.1007/s11064-012-0963-2. Epub 2013 Jan 3.
Hyperbilirubinemia remains one of the most frequent clinical diagnoses in the neonatal period. This condition may lead to the deposition of unconjugated bilirubin (UCB) in the central nervous system, causing nerve cell damage by molecular and cellular mechanisms that are still being clarified. To date, all the studies regarding bilirubin-induced neurological dysfunction were performed in monotypic nerve cell cultures. The use of co-cultures, where astrocyte-containing culture inserts are placed on the top of neuron cultures, provides the means to directly evaluate the cross-talk between these two different cell types. Therefore, this study was designed to evaluate whether protective or detrimental effects are produced by astrocytes over UCB-induced neurodegeneration. Our experimental model used an indirect co-culture system where neuron-to-astrocyte signaling was established concomitantly with the 24 h exposure to UCB. In this model astrocytes abrogated the well-known UCB-induced neurotoxic effects by preventing the loss of cell viability, dysfunction and death by apoptosis, as well as the impairment of neuritic outgrowth. To this protection it may have accounted the induced expression of the multidrug resistance-associated protein 1 and the 3.5-fold increase in the values of S100B, when communication between both cells was established independently of UCB presence. In addition, the presence of astrocytes in the neuronal environment preserved the UCB-induced increase in glutamate levels, but raised the basal concentrations of nitric oxide and TNF-α although no UCB effects were noticed. Our data suggest that bidirectional signalling during astrocyte-neuron recognition exerts pro-survival effects, stimulates neuritogenesis and sustains neuronal homeostasis, thus protecting cells from the immediate UCB injury. These findings may help explain why irreversible brain damage usually develops only after the first day of post-natal life.
高胆红素血症仍然是新生儿期最常见的临床诊断之一。这种情况可能导致未结合胆红素（UCB）在中枢神经系统中沉积，通过分子和细胞机制导致神经细胞损伤，这些机制仍在阐明之中。迄今为止，所有关于胆红素诱导的神经功能障碍的研究都是在单一神经细胞培养物中进行的。使用共培养物，即将含有星形胶质细胞的培养物插入物放在神经元培养物的顶部，可以直接评估这两种不同细胞类型之间的串扰。因此，本研究旨在评估星形胶质细胞是否对 UCB 诱导的神经退行性变产生保护或有害作用。我们的实验模型使用间接共培养系统，其中神经元-星形胶质细胞信号传导与 UCB 暴露 24 小时同时建立。在该模型中，星形胶质细胞通过防止细胞活力丧失、功能障碍和凋亡导致的细胞死亡，以及神经突生长受损，从而消除了众所周知的 UCB 诱导的神经毒性作用。这种保护作用可能归因于多药耐药相关蛋白 1 的诱导表达，以及当两种细胞之间的通讯独立于 UCB 存在时，S100B 值增加了 3.5 倍。此外，星形胶质细胞存在于神经元环境中，可维持 UCB 诱导的谷氨酸水平升高，但提高了基础一氧化氮和 TNF-α浓度，尽管未观察到 UCB 作用。我们的数据表明，星形胶质细胞-神经元识别过程中的双向信号传递发挥了促生存作用，刺激了神经突生成并维持了神经元的内稳态，从而保护细胞免受 UCB 的即时损伤。这些发现可能有助于解释为什么不可逆的脑损伤通常仅在出生后第一天后才会发展。
