Bone morphogenetic protein 6 (BMP6) and connective tissue growth factor (CTGF) are critical growth factors required for normal follicular development and luteal function. Cluster of Differentiation 68 (CD68) is an intraovarian marker of macrophages that plays an important role in modulating the physiological regression of the corpus luteum. The aim of this study was to investigate the effect of BMP6 on the expression of CTGF and the subsequent increase in CD68 expression as well as its underlying mechanisms. Primary and immortalized (SVOG) human granulosa cells obtained from infertile women undergoing in vitro fertilization treatment were used as cell models to conduct the in vitro experiments. Our results showed that BMP6 treatment significantly increased the expression levels of CTGF and CD68. Using BMP type I receptor inhibitors (dorsomorphin, DMH-1 and SB431542), we demonstrated that both activin receptor-like kinase (ALK)2 and ALK3 are involved in BMP6-induced stimulatory effects on the expression of CTGF and CD68. Additionally, SMAD4-knock down reversed the BMP6-induced up-regulation of CTGF and CD68, indicating that the canonical SMAD signaling pathway is required for these effects. Moreover, CTGF-knock down abolished the BMP6-induced up-regulation of CD68 expression. These findings indicate that intrafollicular CTGF mediates BMP6-induced increases in CD68 expression through the ALK2/ALK3-mediated SMAD-dependent signaling pathway.

骨形态发生蛋白 6 (BMP6) 和结缔组织生长因子 (CTGF) 是正常卵泡发育和黄体功能所需的关键生长因子。分化簇 68 (CD68) 是巨噬细胞的卵巢内标记物，在调节黄体生理消退中起重要作用。本研究的目的是研究 BMP6 对 CTGF 表达的影响以及随后 CD68 表达的增加及其潜在机制。从接受体外受精治疗的不育妇女获得的原代和永生化（SVOG）人颗粒细胞用作细胞模型进行体外实验。我们的结果表明，BMP6 处理显着增加了 CTGF 和 CD68 的表达水平。使用 BMP I 型受体抑制剂（dorsomorphin，DMH-1 和 SB431542)，我们证明激活素受体样激酶 (ALK)2 和 ALK3 都参与了 BMP6 诱导的对 CTGF 和 CD68 表达的刺激作用。此外，SMAD4 敲低逆转了 BMP6 诱导的 CTGF 和 CD68 上调，表明这些作用需要经典的 SMAD 信号通路。此外，CTGF 敲低消除了 BMP6 诱导的 CD68 表达上调。这些发现表明，滤泡内 CTGF 通过 ALK2/ALK3 介导的 SMAD 依赖性信号通路介导 BMP6 诱导的 CD68 表达增加。SMAD4 敲低逆转了 BMP6 诱导的 CTGF 和 CD68 上调，表明这些效应需要经典的 SMAD 信号通路。此外，CTGF 敲低消除了 BMP6 诱导的 CD68 表达上调。这些发现表明，滤泡内 CTGF 通过 ALK2/ALK3 介导的 SMAD 依赖性信号通路介导 BMP6 诱导的 CD68 表达增加。SMAD4 敲低逆转了 BMP6 诱导的 CTGF 和 CD68 上调，表明这些效应需要经典的 SMAD 信号通路。此外，CTGF 敲低消除了 BMP6 诱导的 CD68 表达上调。这些发现表明，滤泡内 CTGF 通过 ALK2/ALK3 介导的 SMAD 依赖性信号通路介导 BMP6 诱导的 CD68 表达增加。