Tumor Necrosis Factor-α Impairs Kisspeptin Signaling in Human Gonadotropin-Releasing Hormone Primary Neurons

Context: Inflammatory pathways may impair central regulatory networks involving gonadotropinreleasing hormone (GnRH) neuron activity. Studies in humans are limited by the lack of human GnRH neuron cell lines. Objective: To establish an in vitro model of human GnRH neurons and analyze the effects of proinflammatory cytokines. Design: The primary human fetal hypothalamic cells (hfHypo) were isolated from 12-week-old fetuses. Responsiveness to kisspeptin, the main GnRH neurons' physiological regulator, was evaluated for biological characterization. Tumor necrosis factor alpha (TNF-alpha) was used as a proinflammatory stimulus. Main OutcomeMeasures: Expression of specific GnRH neuronmarkers by quantitative reverse transcription-polymerase chain reaction, flow cytometry, and immunocytochemistry analyses; and GnRH-releasing ability and electrophysiological changes in response to kisspeptin. Results: The primary hfHypo showed a high percentage of GnRH-positive cells (80%), expressing a functional kisspeptin receptor (KISS1R) and able to release GnRH in response to kisspeptin. TNF-alpha exposure determined a specific inflammatory intracellular signaling and reduced GnRH secretion, KISS1R expression, and kisspeptin-induced depolarizing effect. Moreover, hfHypo possessed a primary cilium, whose assembly was inhibited by TNF-alpha. Conclusion: The hfHypo cells represent a novel tool for investigations on human GnRH neuron biology. TNF-alpha directly affects GnRH neuron function by interfering with KISS1R expression and ciliogenesis, thereby impairing kisspeptin signaling.