Hormone replacement therapy for postmenopausal atherosclerosis is offset by late age iron deposition

Deferasirox improved iron homeostasis and hematopoiesis in ovariectomized rats with iron accumulation

Menopause is a natural biological aging process characterized by the loss of ovarian follicular function and decrease estrogen levels. These hormonal fluctuations are associated with increased iron levels, which ultimately lead to iron accumulation. This study aims to investigate the effects of Deferasirox on iron homeostasis and hematopoiesis in ovariectomized rats with iron accumulation. Sixty-four female Wistar rats were divided into eight groups and underwent ovariectomy surgery to simulate menopause. Iron accumulation was induced through the injection of ammonium ferric citrate. Deferasirox was administered at doses of 50 mg/kg and 100 mg/kg. Hematological parameters, iron profile, antioxidant markers, oxidative stress indicators, histopathological evaluation of uterine, bone, bone marrow, liver, and spleen tissues, flow cytometric analysis of hematopoietic CD markers, and relative expression of Hamp, Pu.1, Gata1, and Gdf11 genes were analyzed. Deferasirox treatment improved histopathological changes in the uterine tissue of ovariectomized rats with iron accumulation, increased the number of white blood cells, and reduced serum iron levels, TIBC, ferritin, and transferrin saturation percentage. It also increased serum antioxidant capacity and reduced oxidative stress markers. Deferasirox had a positive effect on femur bone, hematopoietic cell count, volume of hematopoietic and adipose tissues in bone marrow, extramedullary hematopoiesis in the liver and spleen, and influenced the relative expression of Hamp, Pu.1, Gata1, and Gdf11 genes related to hematopoiesis and iron metabolism. In conclusion, Deferasirox effectively manages iron homeostasis and hematopoiesis in ovariectomized rats with iron accumulation and suppresses oxidative stress.

TGFβ2-Driven Ferritin Degradation and Subsequent Ferroptosis Underlie Salivary Gland Dysfunction in Postmenopausal Conditions

Despite the high incidence of dry mouth in postmenopausal women, its underlying mechanisms and therapeutic interventions remain underexplored. Using ovariectomized (OVX) mouse models, here this study identifies ferroptosis, an iron-dependent regulated cell death, as a central mechanism driving postmenopausal salivary gland (SG) dysfunction. In the OVX-SGs, TGFβ signaling pathway is enhanced with the aberrant TGFβ2 expression in SG mesenchymal cells. Intriguingly, TGFβ2 treatment reduces iron-storing ferritin levels, leading to lipid peroxidation and ferroptotic death in SG epithelial organoids (SGOs). Mechanistically, TGFβ2 promotes the autophagy-mediated ferritin degradation, so-called ferritinophagy. A notable overexpression of the type III TGFβ receptor (TβRIII) is found in the OVX-SGs and TGFβ2-treated SGOs, while the silencing of TβRIII mitigates the ferroptosis-mediated deleterious effects of TGFβ2 on SGOs. Finally, administration of ferroptosis inhibitor, Liproxstatin-1 (Lip-1), improves saliva secretion in OVX mice. Present findings collectively suggest a link between TGFβ signaling, ferroptosis, and SG injury, offering new therapeutic avenues for postmenopausal xerostomia.

Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages

Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.

Iron and atherosclerosis: Lessons learned from rabbits relevant to human disease

The role of iron in promoting atherosclerosis, and hence the cardiovascular, neurodegenerative and other diseases that result from atherosclerosis, has been fiercely controversial. Many studies have been carried out on various rodent models of atherosclerosis, especially on apoE-knockout (apoE-/-) mice, which develop atherosclerosis more readily than normal mice. These apoE-/- mouse studies generally support a role for iron in atherosclerosis development, although there are conflicting results. The purpose of the current article is to describe studies on another animal model that is not genetically manipulated; New Zealand White (NZW) rabbits fed a high-cholesterol diet. This may be a better model than the apoE-/- mice for human atherosclerosis, although it has been given much less attention. Studies on NZW rabbits support the view that iron promotes atherosclerosis, although some uncertainties remain, which need to be resolved by further experimentation.

Iron gets in the way

Accumulation of iron with age may inhibit the benefits of hormone replacement therapy on cardiovascular disease in late postmenopause.