CPU86017 and its isomers improve hypoxic pulmonary hypertension by attenuating increased ETA receptor expression and extracellular matrix accumulation

Remodeling of the pulmonary artery is a major feature of pulmonary artery hypertension, and CPU86017, a derivative of berberine, is known to effectively alleviate hypoxic pulmonary hypertension (HPH). CPU86017 is a racemate, possessing two chiral centers: 7N and 13aC. We have compared the effects of four CPU86017 isomers, SS [(+)-7S, 13aS-CPU86017], SR [(-)-7S, 13aR-CPU86017], RR [(-)-7R, 13aR-CPU86017] and RS [(+)-7R, 13aS-CPU86017], on HPH. Sprague-Dawley rats were exposed to hypoxic conditions (10 +/- 0.5% O-2 for 8 h per day) for 4 weeks and treated with CPU86017, SS, SR, RR or RS (4 mg/kg, subcutaneously) from day 15 to 28. After 4 weeks of exposure to hypoxia, remodeling of the right ventricle and the small pulmonary arteries (< 150 mu m) was very pronounced, and extra-cellular matrix (ECM) had been excessively produced in association with abnormal mRNA and protein expression of matrix metalloproteinase 9 (MMP9) and mRNA of tissue inhibitor of matrix metalloproteinase 1 and 2 (TIMP1, TIMP2). Expression of endothelin receptor A was upregulated, while that connexin 40 was downregulated. The administration of CPU86017 and its four isomers attenuated the changes, with the isomer RS exhibiting the most favorable effect on HPH rats. We propose that an activated endothelin pathway associated with an unbalanced MMP-TIMP system may contribute to the over-accumulation of ECM and the remodeling of the pulmonary arterioles in HPH. CPU86017 and its four isomers attenuate ECM accumulation and vascular remodeling by normalizing both the MMP-TIMP system and the ET system. The RS isomer is superior to the racemate CPU86017 in attenuating HPH.