Gessi Marco, Monego Giovanni, Lauriola Libero, Maggiano Nicola, Ranelletti Franco O
Department of Pathology, Catholic University, Rome, Italy.
J Histochem Cytochem. 2005 Aug;53(8):955-62. doi: 10.1369/jhc.4A6548.2005. Epub 2005 May 6.
Parathyroid hormone-related peptide (hPTHrP) is expressed in human tissues and regulates cellular proliferation, differentiation, and apoptosis by an autocrine/paracrine loop. In rodent thymus, both parathormone and parathyroid hormone-related peptide (PTHrP) are expressed by thymic epithelial cells (TECs). The present study demonstrated by RT-PCR and immunohistochemistry that hPTHrP and parathyroid hormone-related peptide receptor type 1 (PTHR1) were expressed in human thymus at both RNA and protein levels. hPTHrP was expressed mainly in the thymic medulla by epithelial (cytokeratin-positive), mature dendritic (CD40+/86+) and plasmacytoid interleukin (IL)-3Ralpha1 cells. This protein was also present in some cells forming Hassall's bodies and a few subcapsular and cortical TECs. PTHR1 was expressed by scattered subcapsular and cortical TECs and by rare TECs in the medulla. Thymocytes did not express either hPTHrP or PTHR1. Primary cultures of human TECs revealed the presence of both hPTHrP and PTHR1 mRNAs, confirming the capacity of TECs to synthesize both peptides. Moreover, synthetic (1-39) hPTHrP peptide administered on cultured TECs induced the expression of IL-6 mRNA, suggesting that hPTHrP can regulate thymic functions by inducing in TECs the expression of IL-6, which is involved in the development and maturation of thymocytes.
甲状旁腺激素相关肽（hPTHrP）在人体组织中表达，并通过自分泌/旁分泌环路调节细胞增殖、分化和凋亡。在啮齿动物胸腺中，甲状旁腺激素和甲状旁腺激素相关肽（PTHrP）均由胸腺上皮细胞（TECs）表达。本研究通过逆转录聚合酶链反应（RT-PCR）和免疫组织化学证明，hPTHrP和1型甲状旁腺激素相关肽受体（PTHR1）在人胸腺中均有RNA和蛋白质水平的表达。hPTHrP主要在上皮细胞（细胞角蛋白阳性）、成熟树突状细胞（CD40+/86+）和浆细胞样白细胞介素（IL）-3Rα1细胞中表达于胸腺髓质。该蛋白也存在于一些形成哈氏小体的细胞以及少数被膜下和皮质TECs中。PTHR1由散在的被膜下和皮质TECs以及髓质中罕见的TECs表达。胸腺细胞不表达hPTHrP或PTHR1。人TECs的原代培养显示存在hPTHrP和PTHR1 mRNA，证实了TECs合成这两种肽的能力。此外，在培养的TECs上施用合成的（1-39）hPTHrP肽可诱导IL-6 mRNA的表达，提示hPTHrP可通过诱导TECs中IL-6的表达来调节胸腺功能，IL-6参与胸腺细胞的发育和成熟。
