Selenium-GPX4 axis protects follicular helper T cells from ferroptosis.

Follicular helper T (TFH) cells are a specialized subset of CD4+ T cells that essentially support germinal center responses where high-affinity and long-lived humoral immunity is generated. The regulation of TFH cell survival remains unclear. Here we report that TFH cells show intensified lipid peroxidation and altered mitochondrial morphology, resembling the features of ferroptosis, a form of programmed cell death that is driven by iron-dependent accumulation of lipid peroxidation. Glutathione peroxidase 4 (GPX4) is the major lipid peroxidation scavenger and is necessary for TFH cell survival. The deletion of GPX4 in T cells selectively abrogated TFH cells and germinal center responses in immunized mice. Selenium supplementation enhanced GPX4 expression in T cells, increased TFH cell numbers and promoted antibody responses in immunized mice and young adults after influenza vaccination. Our findings reveal the central role of the selenium-GPX4-ferroptosis axis in regulating TFH homeostasis, which can be targeted to enhance TFH cell function in infection and following vaccination.

Efficacy of melatonin for sleep disturbance in middle-aged primary insomnia: a double-blind, randomised clinical trial.

BACKGROUND: The aim of this study was to determine the efficacy of exogenous melatonin supplementation for sleep disturbances in patients with middle-aged primary insomnia. METHODS: This is a randomized double-blind, placebo-controlled parallel study. Participants were recruited from Tianlin community, Xuhui district, Shanghai. Ninety-seven consecutive middle-aged patients with primary insomnia were randomized to receive 3 mg fast-release melatonin (n = 51) or placebo (n = 46) for four-weeks. Objective sleep parameters tested by overnight polysomnography, subjective sleep performance and daytime somnolence obtained from the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI) and Epworth Sleepiness Scale (ESS) were obtained at baseline and after treatment. Treatment was taken daily 1 h before bedtime. Serious adverse events and side-effects were monitored. RESULTS: Melatonin supplementation significantly decreased early wake time [-30.63min (95% CI, -53.92 to -7.34); P = 0.001] and percentage of N2 sleep [-7.07% (95% CI, -13.47% to -0.68%); P = 0.031]. However, melatonin had no significant effect on other objective sleep parameters including sleep latency, sleep efficiency, wake during the sleep and percent of N1, N3 and REM sleep. Melatonin had no effect on insomnia symptoms and severity on the PSQI [1.53(95% CI, -0.55 to 3.61); p = 0.504]; ISI [0.81 (95% CI, -2.27 to 3.88); p = 0.165] and ESS [-0.83 (95% CI, -3.53 to 1.88); p = 0.147]. No serious adverse events were reported. CONCLUSIONS: Melatonin supplementation over a four-week period is effective and safe in improving some aspects of objective sleep quality such as total sleep time, percentage of rapid eye movement and early morning wake time in middle-aged patients with insomnia. TRIAL REGISTRATION: Identifier: ChiCTR-TRC-13003997; Prospectively registered on 2 December 2013.