RNA-seq to characterize estrogen receptor alpha mutation in the female rat right ventricle with pressure overload

Purpose: While women are more susceptible to pulmonary arterial hypertension (PAH) than men, their right ventricular (RV) function is better preserved. Experimental studies have identified estrogen receptor alpha (ERα) as a likely mediator for estrogen protection in the RV. However, the role of ERα in preserving RV function and remodeling during pressure overload remains poorly understood. We hypothesized that loss of functional ERα removes female protection from adverse remodeling and is permissive for development of a maladapted RV phenotype. Methods: Male and female rats with a loss-of-function mutation in ERα (ERαMut) and wildtype (WT) littermates, while at their surgical plane of anesthesia, underwent RV pressure overload by pulmonary artery banding (PAB) or a sham surgery. Results: At 10 weeks post-PAB, WT and ERαMut demonstrated RV hypertrophy. Single beat analysis and Tau Weiss calculation from RV pressure waveforms (collected during surgical plane of anesthesia) demonstrated uncoupling of the RV-pulmonary vascular circuit and diastolic dysfunction, respectively, in female, but not male, ERαMut PAB rats. Similarly, female, but not male, ERαMut exhibited increased RV fibrosis, comprised primarily of stiffer collagen type I, suggesting RV stiffening by collagen type I accumulation. RNA-sequencing in female WT and ERαMut RV revealed Kallikrein related-peptidase 10 (Klk10) and Jun Proto-Oncogene (Jun) as possible mediators of female RV protection during PAB. Conclusions: ERα in females is protective against RV-pulmonary vascular uncoupling, diastolic dysfunction, and fibrosis in response to pressure overload. ERα appears to be dispensable for RV adaptation in males. ERα may be a mediator of superior RV adaptation in female patients with PAH. 20-21 week old female wildtype (WT) and ERalpha -/- rats

【研究目的】相较于男性，女性更易罹患肺动脉高压（pulmonary arterial hypertension, PAH），但其右心室（right ventricular, RV）功能却能得到更好的保护。已有实验研究证实，雌激素受体α（estrogen receptor alpha, ERα）可能是雌激素对右心室发挥保护作用的介导因子。然而，目前对于压力超负荷状态下，ERα在维持右心室功能及抑制心室重构中的作用仍不甚明确。本研究提出假说：功能性ERα的缺失会消除女性群体的心室保护机制，进而促进不良型右心室表型的形成。
【研究方法】本研究选取携带ERα功能缺失突变的雌性与雄性大鼠（ERαMut）以及同窝野生型（wildtype, WT）大鼠，在手术麻醉状态下，通过肺动脉环扎术（pulmonary artery banding, PAB）构建右心室压力超负荷模型，或实施假手术作为对照。
【研究结果】肺动脉环扎术后10周，野生型与ERα突变大鼠均出现右心室肥厚。通过对手术麻醉状态下采集的右心室压力波形进行单搏分析与Tau Weiss计算，结果显示：仅在雌性ERα突变手术组大鼠中，观察到右心室-肺血管循环解耦联现象以及舒张功能障碍，雄性ERα突变手术组大鼠则无此类表现。同样，仅雌性ERα突变手术组大鼠出现右心室纤维化程度升高，其纤维化成分主要为硬度更高的I型胶原，提示I型胶原积累导致了右心室僵硬。对雌性野生型与ERα突变大鼠的右心室组织进行RNA测序分析，发现激肽释放酶相关肽酶10（Kallikrein related-peptidase 10, Klk10）与Jun原癌基因（Jun Proto-Oncogene, Jun）可能是雌性大鼠在肺动脉环扎术后右心室保护作用的介导因子。
【研究结论】雌性体内的ERα可在压力超负荷状态下，对右心室-肺血管循环解耦联、舒张功能障碍以及纤维化起到保护作用。对于雄性大鼠而言，ERα似乎并非右心室适应性重构所必需的因子。ERα可能是肺动脉高压女性患者右心室适应性重塑更优的介导因子。实验所用大鼠为20~21周龄的雌性野生型与ERα基因敲除（ERalpha -/-）大鼠。