Iron overload induces cerebral endothelial senescence in aged mice and in primary culture in a sex-dependent manner

Investigation the mechanism of iron overload-induced colonic inflammation following ferric citrate exposure

Iron overload occurs due to excessive iron intake compared to the body's demand, leading to iron deposition and impairment of multiple organ functions. Our previous study demonstrated that chronic oral administration of ferric citrate (FC) caused colonic inflammatory injury. However, the precise mechanism underlying this inflammatory response remains unclear. The current study aims to investigate the mechanism by which iron overload induced by FC exposure leads to colonic inflammation. To accomplish this, mice were orally exposed to three different concentrations of FC (71 mg/kg/bw (L), 143 mg/kg/bw (M) and 286 mg/kg/bw (H)) for continuous 16 weeks, with the control group receiving ultrapure water (C). Exposure to FC caused disturbances in the excretory system, altered colonic flora alpha diversity, and enriched pathogenic bacteria, such as Mucispirillum, Helicobacter, Desulfovibrio, and Shigella. These changes led to structural disorders of the colonic flora and an inflammatory response phenotype characterized by inflammatory cells infiltration, atrophy of intestinal glands, and irregular thickening of the intestinal wall. Mechanistic studies revealed that FC-exposure activated the NF-κB signaling pathway by up-regulating TLR4, MyD88, and NF-κB mRNA levels and protein expression. This activation resulted in increased production of pro-inflammatory cytokines, further contributing to the colonic inflammation. Additionally, in vitro experiments in SW480 cells confirmed the activation of NF-κB signaling pathway by FC exposure, consistent with the in vivo findings. The significance of this study lies in its elucidation of the mechanism by which iron overload caused by FC exposure leads to colonic inflammation. By identifying the role of pathogenic bacteria and the NF-κB signaling pathway, this study could potentially offer a crucial theoretical foundation for the research on iron overload, as well as provide valuable insights for clinical iron supplementation.

n-3 polyunsaturated fatty acids delay intervertebral disc degeneration by inhibiting nuclear receptor coactivator 4-mediated iron overload

n-3 polyunsaturated fatty acids (PUFAs) are closely related to the progression of numerous chronic inflammatory diseases, but the role of n-3 PUFAs in the intervertebral disc degeneration (IVDD) remains unclear. In this study, male C57BL/6 wildtype mice (WT group, n = 30) and fat-1 transgenic mice (TG group, n = 30) were randomly selected to construct the IVDD model. The results demonstrated that the optimized composition of PUFAs in the TG mice had a significant impact on delaying IVDD and cellular senescence of intervertebral disc (IVD). Mechanismly, n-3 PUFAs inhibited IVD senescence by alleviating NCOA4-mediated iron overload. NCOA4 overexpression promoted iron overload and weakened the pro-proliferation and anti-senescence effect of DHA on the IVD cells. Furthermore, this study futher revealed n-3 PUFAs downregulated NCOA4 expression by inactiviting the LGR5/β-catenin signaling pathway. This study provides an important theoretical basis for preventing and treating IVDD and low back pain.

HIF-1α Induced by Hypoxia Promotes Peripheral Nerve Injury Recovery Through Regulating Ferroptosis in DRG Neuron

Peripheral nerve injury (PNI) usually has a poor effect on functional recovery and severely declines the patient's quality of life. Our prior findings indicated that hypoxia remarkably promoted nerve regeneration of rats with sciatic nerve transection. However, the underlying molecular mechanisms of hypoxia in functional recovery of PNI still remain elusive. In this research, we tried to explain the functional roles and mechanisms of hypoxia and the hypoxia-inducible factor-1α (HIF-1α) in PNI. Our results indicated that hypoxia promoted proliferation and migration of dorsal root ganglia (DRG) and increased the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Mechanistically, hypoxia suppressed ferroptosis through activating HIF-1α in DRG neurons. Gain and loss of function studies were performed to evaluate the regulatory roles of HIF-1α in ferroptosis and neuron recovery. The results revealed that up-regulation of HIF-1α enhanced the expression of solute carrier family membrane 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) and increased the contents of cysteine and glutathione, while inhibiting the accumulation of reactive oxygen species (ROS). Our findings provided novel light on the mechanism of ferroptosis involved in PNI and manifest hypoxia as a potential therapeutic strategy for PNI recovery.