Sertoli cell toxicant injury and mechanisms of testicular germ cell apoptosis

支持细胞毒性损伤及睾丸生殖细胞凋亡机制

• 批准号: 8968836
• 负责人: JOHN H RICHBURG
• 金额: $ 33.55万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2019-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8968836
• 关键词: Accounting; Acute; Age; Antibodies; Antigens; Apoptosis; Blood-Testis Barrier; CCL2 gene; Cells; Chemicals; Data; Dendritic Cells; Development; Endotoxins; Environment; Exposure to; Foundations; Funding; Gelatinase A; Germ Cells; Goals; Health; Human; ITGAM gene; Immune; Immune Tolerance; Immune system; Inbred F344 Rats; Individual; Infiltration; Inflammation; Inflammatory; Injury; Interferons; Interleukin-1; Leukocytes; Lipopolysaccharides; Monocyte Chemoattractant Protein-1; Monocyte Chemoattractant Proteins; Mus; Natural Killer Cells; Organ; Pathogenesis; Pathway interactions; Predisposition; Production; Proteins; Rattus; Recruitment Activity; Reproductive Health; Research; Research Proposals; Risk; Role; Signal Pathway; Signal Transduction; Source; TNF gene; Testing; Testis; Time; Tissue Inhibitor of Metalloproteinases; Tissues; Toxic effect; Work; age related; aged; cell injury; chemokine; consumer product; cytokine; in vivo; inhibitor/antagonist; insight; interstitial; macrophage; male; mono-(2-ethylhexyl)phthalate; monocyte; neutrophil; novel; paracrine; phthalates; postnatal; prevent; research study; response; sertoli cell; toxicant

DESCRIPTION (provided by applicant): The goal of this project is to decipher the cellular signals that instigate leukocyte infiltration into the testis after exposure to mono-(2-ethylhexyl) phthalate (MEHP) and to determine the functional significance of these cells in the pathogenesis of MEHP-induced germ cell apoptosis. We have previously revealed a paracrine interaction between Sertoli cells (SCs) and germ cells (GCs) that initiates GCs to undergo apoptosis via FasL- Fas signaling. Central to this pathway is the inhibition of TIMP2 (tissue inhibitor of metalloproteinase 2) production by SCs after MEHP exposure. This allows for the consequent activation of matrix metalloproteinase 2 (MMP2) in the adluminal space that both generates a soluble form of tumor necrosis factor-? (sTNF?) as well as cause a disorganization of proteins that compose the blood-testis barrier (BTB) between adjacent SCs. A preliminary characterization of Fischer rat testis after MEHP (1 g/kg, p.o.) treatment at two peripubertal ages (PND 28 and 35) showed a robust infiltration of CD11b+ immunoreactive cells in the interstitial space prior to the peak induction of GC apoptosis. The CD11b antibody recognizes an antigen expressed on macrophages, neutrophils, monocytes, natural killer and dendritic cells. Intriguingly, we observed that the most pronounced infiltration of these cells occurs in peripubertal aged rats versus mature rats; and that C57BL/6J mice at both ages do not have a significant infiltration in response to MEHP exposure. The differential species and age- dependent sensitivity to MEHP-induced testicular injury is well recognized, although the mechanisms that account for these differences remain unresolved. Further, preliminary studies also show a dramatic increase in the expression of monocyte chemoattractant protein-1 (MCP-1) in peritubular myoid cells (PTMCs) in testis from PND 28 rats, but not in mature rats. MCP-1 is a prototypical chemokine for signaling the influx of leukocytes into tissues and is itself secreted in response to cytokines such as sTNF?, IL-1?, Il-1? and/or interferon-?. Taken together, our previous work and preliminary data, have led to the development of the hypothesis that MEHP-induced SC injury incites the production of cytokines, such as sTNF?, that trigger PTMCs to release chemokines that initiate the infiltration of leukocytes into the testis and act to enhance the extent of GC apoptosis. Moreover, a provocative underlying hypothesis of this proposal is that leukocytes account, in part, for the mechanism of the observed age- and species-dependent sensitivity to MEHP. To test these hypotheses, the first specific aim will use both acute and repeated MEHP treatments to characterize the leukocyte subtypes and timing of their influx into the testis following exposure. In the second aim, the chemokines and cytokines elicited, as well as their specific cellular source in the testis, will be examined. In the last ai, the functional significance of testis leukocyte infiltration in the pathogenesis of MEHP-induced injury will be directly tested. It is predicted that insights gained from this work will be useful or predicting susceptible individuals and preventing human reproductive health risks this class of chemicals.

描述（由申请人提供）：该项目的目标是破译暴露于单（2-乙基己基）后促使白细胞浸润到睾丸的细胞信号 邻苯二甲酸盐（MEHP）并确定这些细胞在 MEHP 诱导的生殖细胞凋亡发病机制中的功能意义。我们之前已经揭示了支持细胞（SC）和生殖细胞（GC）之间的旁分泌相互作用，通过 FasL-Fas 信号传导启动 GC 经历细胞凋亡。该途径的核心是 MEHP 暴露后 SC 抑制 TIMP2（金属蛋白酶组织抑制剂 2）的产生。这使得腔内基质金属蛋白酶 2 (MMP2) 被激活，两者都产生可溶形式的肿瘤坏死因子 -? (sTNF？) 还会导致构成相邻 SC 之间血睾屏障 (BTB) 的蛋白质混乱。 Fischer 大鼠睾丸在两个青春期前年龄（PND 28 和 35）经 MEHP（1 g/kg，口服）治疗后的初步特征显示，在 GC 凋亡诱导达到峰值之前，间质中 CD11b+ 免疫反应性细胞大量浸润。 CD11b 抗体可识别巨噬细胞、中性粒细胞、单核细胞、自然杀伤细胞和树突细胞上表达的抗原。有趣的是，我们观察到，与成熟大鼠相比，这些细胞的浸润最明显发生在青春期周围的老年大鼠中。并且两个年龄段的 C57BL/6J 小鼠均未出现 MEHP 暴露反应的显着浸润。 MEHP 引起的睾丸损伤的物种差异和年龄依赖性敏感性已得到广泛认可，但造成这些差异的机制仍未解决。此外，初步研究还显示，PND 28 大鼠睾丸的管周肌样细胞 (PTMC) 中单核细胞趋化蛋白-1 (MCP-1) 的表达显着增加，但在成熟大鼠中则没有。 MCP-1 是一种典型的趋化因子，用于发出白细胞流入组织的信号，并且其本身响应 sTNF?、IL-1?、Il-1? 等细胞因子而分泌。和/或干扰素-？总而言之，我们之前的工作和初步数据导致了这样的假设：MEHP 诱导的 SC 损伤会刺激细胞因子的产生，例如 sTNF？，从而触发 PTMC 释放趋化因子，从而启动白细胞浸润到睾丸并发挥作用 增强GC细胞凋亡的程度。此外，该提议的一个令人兴奋的基本假设是，白细胞部分解释了观察到的年龄和物种依赖性对 MEHP 的敏感性的机制。为了检验这些假设，第一个具体目标将使用急性和重复 MEHP 治疗来表征白细胞亚型及其在暴露后流入睾丸的时间。在第二个目标中，将检查引起的趋化因子和细胞因子，以及它们在睾丸中的特定细胞来源。在最后的 ai 中，将直接检验睾丸白细胞浸润在 MEHP 诱导损伤发病机制中的功能意义。据预测，从这项工作中获得的见解将有助于预测易感个体并预防此类化学品对人类生殖健康的风险。