Transcellular thiocyanate transport by human airway epithelia
Transcellular thiocyanate transport by human airway epithelia
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DOI：
10.1113/jphysiol.2004.071548
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发表时间：
2004-11-15
影响因子：
5.5
通讯作者：
Conner, GE
中科院分区：
文献类型：
--
作者：
Fragoso, MA;Fernandez, V;Conner, GE
人气道粘膜合成并分泌乳过氧化物酶（LPO）。由于H2 O2和硫氰酸盐（SCN-）也存在，功能性LPO抗菌防御系统存在于气道中。SCN-在几种上皮分泌物中的浓度高于血清中的浓度，尽管这些分泌物中的跨上皮转运和蓄积机制尚不清楚。为了检查分泌物中SCN的积累，在开路条件下使用在空气-液体界面处再分化的人气道上皮细胞。[C-14]SCN-，在基底外侧介质中，被运输穿过上皮，并在顶面浓缩10倍。跨上皮电位的测量显示，基底外侧室相对于顶面为正（13.7 +/- 1.8 mV），因此不利于SCN-的被动运动。转运依赖于基底外侧[SCN-]和饱和（K-m，K-app = 69 +/- 25妈妈）;被抑制的顶端[SCN-]增加;并依赖于基底外侧Na+的存在。高氯酸盐（K-I，K-APP = 0.6 +/- 0.05妈妈）和碘化物（K-I，K-APP = 9 - 8妈妈）在基底侧介质可逆地抑制运输，但呋塞米没有。碘化物也被转运（K-m，K-app = 111 +/- 69 mum）。RT-PCR和免疫组化证实气道内有Na+-I-同向转运体（NIS）的表达。SCN-转运对顶端二磺酸Cl-通道阻滞剂不敏感，但对顶端格列本脲和芳氨基苯甲酸酯敏感。毛喉素和二丁酰cAMP增加运输。这些数据表明SCN-转运可能通过基底外侧NIS介导的细胞内SCN-浓缩发生，然后通过顶端通道释放，可能是囊性纤维化跨膜传导调节剂。
Human airway mucosa synthesizes and secretes lactoperoxidase (LPO). As H2O2 and thiocyanate (SCN-) are also present, a functional LPO antibacterial defence system exists in the airways. SCN- concentrations in several epithelial secretions are higher than in serum, although the mechanisms of transepithelial transport and accumulation in these secretions are unknown. To examine SCN- accumulation in secretions, human airway epithelial cells, re-differentiated at the air-liquid interface, were used in open-circuit conditions. [C-14]SCN-, in the basolateral medium, was transported across the epithelium and concentrated tenfold at the apical surface. Measurement of the transepithelial potential showed that the basolateral compartment was positive relative to the apical surface (13.7 +/- 1.8 mV) and therefore unfavourable for passive movement of SCN-. Transport was dependent on basolateral [SCN-] and saturable (K-m,K-app = 69 +/- 25 mum); was inhibited by increased apical [SCN-]; and was dependent on the presence of basolateral Na+. Perchlorate (K-i,K-app = 0.6 +/- 0.05 mum) and iodide (K-i,K-app = 9 8 mum) in the basolateral medium reversibly inhibited transport, but furosemide did not. Iodide was also transported(K-m,K-app = 111 +/- 69 mum). RT-PCR and immunohistochemistry confirmed expression of Na+-I- symporter (NIS) in the airways. SCN- transport was insensitive to apical disulphonic acid Cl- channel blockers, but sensitive to apical glibenclamide and arylaminobenzoates. Forskolin and dibutyryl cAMP increased transport. These data suggest SCN- transport may occur through basolateral NIS-mediated SCN- concentration inside cells, followed by release through an apical channel, perhaps cystic fibrosis transmembrane conductance regulator.