Interdisciplinary Life Sciences Graduate Program, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, USA.
Center for Molecular Carcinogenesis and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, USA.
Toxicol Sci. 2024 Jun 26;200(1):70-78. doi: 10.1093/toxsci/kfae043.
Peritubular macrophages (PTMφ) are predominantly localized near spermatogonial stem cells in the testis. We previously revealed that exposure of peripubertal male Fischer rats to mono-(2-ethylhexyl) phthalate (MEHP) leads to increased PTMφs in the testis. The mechanisms that trigger increases in PTMφs in the testis are poorly understood. However, MEHP exposure is known to both induce spermatocyte apoptosis and to perturb the blood-testis barrier (BTB). This study aims to elucidate the association between the disruption of BTB and the increases of PTMφs in the testis by comparing the effects observed with MEHP to 2 other testicular toxicants with variable effects on the BTB and subtype of germ cell undergoing apoptosis. Methoxyacetic acid (MAA) acts directly on spermatocytes and does not affect BTB function, whereas cadmium chloride (CdCl2) induces profound injury to BTB. The results indicated that MAA exposure significantly increased spermatocyte apoptosis, whereas no significant changes in the numbers of PTMφs in the testis occurred. In contrast, CdCl2 exposure disrupted BTB function and increased the abundance of PTMφs in the testis. To further investigate whether MEHP-induced changes in BTB integrity accounted for the increase in PTMφs, a plasmid for LG3/4/5, the functional component of laminin-alpha 2, was overexpressed in the testis to stabilize BTB integrity before MEHP exposure. The results showed that LG3/4/5 overexpression substantially reduced the ability of MEHP to compromise BTB integrity and prevented the increase in PTMφ numbers after MEHP exposure. These results indicate that BTB disruption is necessary to increase PTMφs in the testis induced by toxicants.
小管周细胞（PTMφ）主要定位于睾丸内精原干细胞附近。我们之前的研究表明，青春期前雄性 Fischer 大鼠暴露于邻苯二甲酸单（2-乙基己基）酯（MEHP）会导致睾丸中 PTMφ 的增加。触发睾丸中 PTMφ 增加的机制尚未完全了解。然而，已知 MEHP 暴露既会诱导精母细胞凋亡，又会扰乱血睾屏障（BTB）。本研究旨在通过将 MEHP 的作用与对 BTB 和经历凋亡的生殖细胞亚群具有不同影响的另外 2 种睾丸毒物的作用进行比较，阐明 BTB 破坏与睾丸中 PTMφ 增加之间的关联。甲氧基乙酸（MAA）直接作用于精母细胞，不影响 BTB 功能，而氯化镉（CdCl2）则会对 BTB 造成严重损伤。结果表明，MAA 暴露会显著增加精母细胞凋亡，而睾丸中 PTMφ 的数量没有明显变化。相比之下，CdCl2 暴露会破坏 BTB 功能并增加睾丸中 PTMφ 的丰度。为了进一步研究 MEHP 引起的 BTB 完整性变化是否导致 PTMφ 增加，在 MEHP 暴露之前，在睾丸中过表达 LG3/4/5（层粘连蛋白-α2 的功能成分）质粒以稳定 BTB 完整性。结果表明，LG3/4/5 过表达可显著降低 MEHP 破坏 BTB 完整性的能力，并防止 MEHP 暴露后 PTMφ 数量增加。这些结果表明，BTB 破坏是导致毒物诱导睾丸中 PTMφ 增加所必需的。
