aDivision of Nephrology, University of Washington Medical Center, Seattle, Washington, USA bDivision of Nephrology, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München-Innenstadt, Munich, Germany cExcellence Centre for Research, Transfer and High Education for the Development of De Novo Therapies (DENOTHE), University of Florence, Florence, Italy.
Curr Opin Nephrol Hypertens. 2013 May;22(3):302-9. doi: 10.1097/MNH.0b013e32835fefd4.
We have summarized recently published glomerular parietal epithelial cell (PEC) research, focusing on their roles in glomerular development and physiology, and in certain glomerular diseases. The rationale is that PECs have been largely ignored until the recent availability of cell lineage tracing studies, human and murine PEC culture systems, and potential therapeutic interventions of PECs.
Several new paradigms involving PECs have emerged demonstrating their significant contribution to glomerular physiology and numerous glomerular diseases. A subset of PECs serving as podocyte progenitors have been identified in normal human glomeruli. They provide a source for podocytes in adolescent mice, and their numbers increase in states of podocyte depletion. PEC progenitor number is increased by retinoids and angiotensin-converting enzyme inhibition. However, dysregulated growth of PEC progenitors leads to pseudo-crescent and crescent formation. In focal segmental glomerulosclerosis, considered a podocyte disease, activated PECs increase extracellular matrix production, which leads to synechial attachment and, when they move to the glomerular tuft, to segmental glomerulosclerosis. Finally, PECs might be adversely affected in proteinuric states by undergoing apoptosis.
PECs play a critical role in glomerular repair through their progenitor function, but under certain circumstances paradoxically contribute to deterioration by augmenting scarring and crescent formation.
我们总结了最近发表的关于肾小球壁层上皮细胞（PEC）的研究，重点介绍了它们在肾小球发育和生理以及某些肾小球疾病中的作用。其理论依据是，直到最近，利用细胞谱系追踪研究、人和鼠 PEC 培养系统以及潜在的 PEC 治疗干预措施，PEC 才得到广泛研究。
涉及 PEC 的几个新范例已经出现，这些范例表明它们对肾小球生理学和许多肾小球疾病有重大贡献。在正常人类肾小球中已经确定了一小部分作为足细胞祖细胞的 PEC。它们为青春期小鼠的足细胞提供了来源，并且在足细胞耗竭的情况下其数量增加。视黄酸和血管紧张素转换酶抑制可增加 PEC 祖细胞的数量。然而，PEC 祖细胞的生长失调会导致假新月体和新月体的形成。在局灶节段性肾小球硬化症（被认为是一种足细胞疾病）中，激活的 PEC 会增加细胞外基质的产生，导致细胞连接，并在它们迁移到肾小球簇时导致节段性肾小球硬化症。最后，PEC 可能会在蛋白尿状态下通过凋亡而受到不利影响。
PEC 通过其祖细胞功能在肾小球修复中发挥关键作用，但在某些情况下，通过增加瘢痕形成和新月体形成，反而会导致恶化。
