L-Citrulline Supplementation Restrains Ferritinophagy-Mediated Ferroptosis to Alleviate Iron Overload-Induced Thymus Oxidative Damage and Immune Dysfunction

Abstract

L-citrulline (L-cit) is a key intermediate in the urea cycle and is known to possess antioxidant and anti-inflammation characteristics. However, the role of L-cit in ameliorating oxidative damage and immune dysfunction against iron overload in the thymus remains unclear. This study explored the underlying mechanism of the antioxidant and anti-inflammation qualities of L-cit on iron overload induced in the thymus. We reported that L-cit administration could robustly alleviate thymus histological damage and reduce iron deposition, as evidenced by the elevation of the CD8+ T lymphocyte number and antioxidative capacity. Moreover, the NF-κB pathway, NCOA4-mediated ferritinophagy, and ferroptosis were attenuated. We further demonstrated that L-cit supplementation significantly elevated the mTEC1 cells’ viability and reversed LDH activity, iron levels, and lipid peroxidation caused by FAC. Importantly, NCOA4 knockdown could reduce the intracellular cytoplasmic ROS, which probably relied on the Nfr2 activation. The results subsequently indicated that NCOA4-mediated ferritinophagy was required for ferroptosis by showing that NCOA4 knockdown reduced ferroptosis and lipid ROS, accompanied with mitochondrial membrane potential elevation. Intriguingly, L-cit treatment significantly inhibited the NF-κB pathway, which might depend on restraining ferritinophagy-mediated ferroptosis. Overall, this study indicated that L-cit might target ferritinophagy-mediated ferroptosis to exert antioxidant and anti-inflammation capacities, which could be a therapeutic strategy against iron overload-induced thymus oxidative damage and immune dysfunction.

Citrulline inhibits LPS‐induced pyroptosis of RAW264.7 macrophages through NF‐κB signaling pathway

“…For example, Man et al have revealed that citrulline attenuates the progression of pre‐eclampsia by suppressing the NF‐κB pathway 33 . In addition, Ba et al have identified that citrulline inhibits ferroptosis in the thymus via inactivating the NF‐κB pathway 34 . Herein, we predicted that citrulline could combine with p65.…”

“… 33 In addition, Ba et al have identified that citrulline inhibits ferroptosis in the thymus via inactivating the NF‐κB pathway. 34 Herein, we predicted that citrulline could combine with p65. However, whether citrulline mediated the NF‐κB pathway to participate in pyroptosis in macrophages.…”

Cancer-Erythrocyte Membrane-Mimicking Fe3O4 Nanoparticles and DHJS for Ferroptosis/Immunotherapy Synergism in Tumors

“…The abnormal alteration in the mitochondrial membrane potential is not only an important marker of mitochondrial damage but also an early warning of ferroptosis . For more visual observation of cellular ferroptosis, we examined the morphology of the HOS cells by TEM.…”

“…The abnormal alteration in the mitochondrial membrane potential is not only an important marker of mitochondrial damage but also an early warning of ferroptosis. 46 For more visual observation of cellular ferroptosis, we examined the morphology of the HOS cells by TEM. The cells treated with FDPM or Fe 3 O 4 nanoparticles exhibited only evident swelling of mitochondria, which was consistent with previous reports.…”

Editorial: Ferroptosis as a novel therapeutic target for inflammation-related diseases

“…It has been demonstrated that the anti-inflammatory drug quercetin may inhibit ferroptosis, via the PI3K/AKT/mTOR pathway ( Lan et al, 2022 ). L-cit, which has anti-inflammatory properties, may target ferritin phagocytosis and mediate ferroptosis ( Ba et al, 2022 ). A review by Li et al described the active glycoside component of the medicinal plant Anoectochilus roxburghii , kinsenoside (KD), which also has potent anti-inflammatory and antioxidant properties.…”