Cuppoletti John, Blikslager Anthony T, Chakrabarti Jayati, Nighot Prashant K, Malinowska Danuta H
Department of Molecular & Cellular Physiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0576, USA.
BMC Pharmacol. 2012 May 3;12:3. doi: 10.1186/1471-2210-12-3.
Linaclotide has been proposed as a treatment for the same gastrointestinal indications for which lubiprostone has been approved, chronic idiopathic constipation and irritable bowel syndrome with constipation. Stressors damage the epithelial cell barrier and cellular homeostasis leading to loss of these functions. Effects of active linaclotide on repair of barrier and cell function in pig jejunum after ischemia and in T84 cells after treatment with proinflammatory cytokines, interferon-γ and tumor necrosis factor-α were examined. Comparison with effects of lubiprostone, known to promote repair of barrier function was carried out.
In ischemia-damaged pig jejunum, using measurements of transepithelial resistance, (3)H-mannitol fluxes, short-circuit current (Cl(-) secretion) and occludin localization, active linaclotide failed to effectively promote repair of the epithelial barrier or recovery of short-circuit current, whereas lubiprostone promoted barrier repair and increased short-circuit current. In control pig jejunum, 1 μM linaclotide and 1 μM lubiprostone both caused similar increases in short-circuit current (Cl(-) secretion). In T84 cells, using measurements of transepithelial resistance, fluxes of fluorescent macromolecules, occludin and mitochondrial membrane potential, active linaclotide was virtually ineffective against damage caused by interferon-γ and tumor necrosis factor-α, while lubiprostone protected or promoted repair of epithelial barrier and cell function. Barrier protection/repair by lubiprostone was inhibited by methadone, a ClC-2 inhibitor. Linaclotide, but not lubiprostone increased [cGMP]i as expected and [Ca(2+)]i and linaclotide depolarized while lubiprostone hyperpolarized the T84 plasma membrane potential suggesting that lubiprostone may lead to greater cellular stability compared to linaclotide. In T84 cells, as found with linaclotide but not with lubiprostone, transepithelial resistance was slightly but significantly decreased by guanylin, STa and 8-bromo cGMP and fluorescent dextran fluxes were increased by guanylin. However the physiological implications of these small but statistically significant changes remain unclear.
Considering the physiological importance of epithelial barrier function and cell integrity and the known impact of stressors, the finding that lubiprostone, but not active linaclotide, exhibits the additional distinct property of effective protection or repair of the epithelial barrier and cell function after stress suggests potential clinical importance for patients with impaired or compromised barrier function such as might occur in IBS.
利那洛肽已被提议用于治疗鲁比前列酮已获批的相同胃肠道适应症，即慢性特发性便秘和便秘型肠易激综合征。应激源会破坏上皮细胞屏障和细胞内稳态，导致这些功能丧失。研究了活性利那洛肽对猪空肠缺血后屏障修复和细胞功能以及对经促炎细胞因子、干扰素 -γ 和肿瘤坏死因子 -α 处理后的 T84 细胞的影响。并与已知能促进屏障功能修复的鲁比前列酮的作用进行了比较。
在缺血损伤的猪空肠中，通过测量跨上皮电阻、³H - 甘露醇通量、短路电流（Cl⁻ 分泌）和闭合蛋白定位，活性利那洛肽未能有效促进上皮屏障的修复或短路电流的恢复，而鲁比前列酮促进了屏障修复并增加了短路电流。在对照猪空肠中，1 μM 利那洛肽和 1 μM 鲁比前列酮均使短路电流（Cl⁻ 分泌）出现类似增加。在 T84 细胞中，通过测量跨上皮电阻、荧光大分子通量、闭合蛋白和线粒体膜电位，活性利那洛肽对干扰素 -γ 和肿瘤坏死因子 -α 造成的损伤几乎无效，而鲁比前列酮则保护或促进了上皮屏障和细胞功能的修复。鲁比前列酮的屏障保护/修复作用被美沙酮（一种 ClC - 2 抑制剂）抑制。利那洛肽如预期那样增加了细胞内 cGMP 水平，而鲁比前列酮增加了细胞内 Ca²⁺ 水平，并且利那洛肽使 T84 质膜电位去极化，而鲁比前列酮使其超极化，这表明与利那洛肽相比，鲁比前列酮可能导致更高的细胞稳定性。在 T84 细胞中，与利那洛肽情况相同但与鲁比前列酮不同的是，鸟苷素、STa 和 8 - 溴 cGMP 使跨上皮电阻略有但显著降低，鸟苷素使荧光葡聚糖通量增加。然而，这些微小但具有统计学意义的变化的生理意义仍不清楚。
考虑到上皮屏障功能和细胞完整性的生理重要性以及应激源的已知影响，发现鲁比前列酮而非活性利那洛肽在应激后具有有效保护或修复上皮屏障和细胞功能的额外独特特性，这表明对于屏障功能受损或受到损害（如在肠易激综合征中可能发生的情况）的患者具有潜在的临床重要性。
