Extracellular ATP has been described to be involved in inflammatory cytokine production by human testicular peritubular cells (HTPCs). The ectonucleotidases ENTPD1 and NT5E degrade ATP and have been reported in rodent testicular peritubular cells. We hypothesized that if a similar situation exists in human testis, ATP metabolites may contribute to cytokine production. Indeed, ENTPD1 and NT5E were found in situ and in vitro in HTPCs. Malachite green assays confirmed enzyme activities in HTPCs. Pharmacological inhibition of ENTPD1 (by POM-1) significantly reduced pro-inflammatory cytokines evoked by ATP treatment, suggesting that metabolites of ATP, including adenosine, are likely involved. We focused on adenosine and detected three of the four known adenosine receptors in HTPCs. One, A2B, was also found in situ in peritubular cells of human testicular sections. The A2B agonist BAY60-6583 significantly elevated levels of IL6 and CXCL8, a result also obtained with adenosine and its analogue NECA. Results of siRNA-mediated A2B down-regulation support a role of this receptor. In mouse peritubular cells, in contrast to HTPCs, all four of the known adenosine receptors were detected; when challenged with adenosine, cytokine expression levels significantly increased. Organotypic short-term testis cultures yielded comparable results and indicate an overall pro-inflammatory action of adenosine in the mouse testis. If transferable to the in vivo situation, our results may implicate that interference with the generation of ATP metabolites or interference with adenosine receptors could reduce inflammatory events in the testis. These novel insights may provide new avenues for treatment of sterile inflammation in male subfertility and infertility.

中文翻译：

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睾丸腺苷作为促炎分子：睾丸管周细胞的作用

细胞外 ATP 已被描述为参与人睾丸管周细胞 (HTPC) 产生炎性细胞因子。外核苷酸酶 ENTPD1 和 NT5E 降解 ATP，并已在啮齿动物睾丸管周细胞中报道。我们假设如果人类睾丸中存在类似情况，则 ATP 代谢物可能有助于细胞因子的产生。事实上，ENTPD1 和 NT5E 在 HTPCs 中原位和体外被发现。孔雀石绿测定证实了 HTPC 中的酶活性。ENTPD1（通过 POM-1）的药理学抑制显着降低了由 ATP 处理引起的促炎细胞因子，这表明可能涉及 ATP 的代谢物，包括腺苷。我们专注于腺苷并检测到 HTPC 中四种已知的腺苷受体中的三种。一、A2B、也在人睾丸切片的管周细胞中原位发现。A2B 激动剂 BAY60-6583 显着提高了 IL6 和 CXCL8 的水平，腺苷及其类似物 NECA 也获得了这一结果。siRNA 介导的 A2B 下调的结果支持该受体的作用。在小鼠管周细胞中，与 HTPC 相比，检测到所有四种已知的腺苷受体。当用腺苷攻击时，细胞因子表达水平显着增加。器官型短期睾丸培养产生了类似的结果，表明腺苷在小鼠睾丸中具有整体促炎作用。如果可以转移到体内情况，我们的结果可能暗示干扰 ATP 代谢物的产生或干扰腺苷受体可以减少睾丸中的炎症事件。