Neely, E. B. | Search bioRxiv

bioRxiv2026

Iron-deficiency in the tumor microenvironment reprograms tumor-immune interactions in a sex biased manner

BackgroundGlioblastoma (GBM) is a sex-biased disease characterized by higher incidence and poorer survival in males. These sex differences are primarily driven by metabolic and immune signatures, with iron metabolism playing a major role. While iron is essential for tumor cell proliferation, it is also critical for T cell recruitment and function within the tumor microenvironment (TME). Clinical data indicates that iron deficiency impacts GBM survival in a sex-biased manner; however, the underlying mechanisms remain unexplored. MethodsWe employed a FTH1 heterozygous knockdown mouse model to induce tumor iron deficiency in GBM-bearing mice. TME dynamics were interrogated using flow cytometry and spatial transcriptomics (10X Xenium) to analyze immune infiltration, localization, and ligand-receptor signaling between GBM and immune cells. ResultsFTH1 knockdown resulted in iron deficiency in the GBM TME. Iron deficiency altered the TME dynamics in a sex biased manner. FTH1 knockdown in females caused an anti-inflammatory, cytokine deficient TME which failed to recruit CD4 and CD8 T cells. In males, FTH1 knockdown caused a proinflammatory environment by activating the innate immune response. Additionally, FTH1 knockdown increased the density of TAMs in the immediate surrounding of GBM cells in a sex biased manner. ConclusionThese results demonstrate that tumor iron plays a sex-biased role in immune infiltration and anti-tumor immunity.

cancer biology↗

bioRxiv2025

Extracellular vesicles released from endothelial cells of the blood-brain barrier mediate brain Iron accumulation during LPS-induced brain Inflammation

IntroductionBrain inflammation leads to an increase in the amount of iron in brain tissue; however, studies do not address the source of the iron that could lead to the accumulation. Most of the brain iron uptake is mediated through the blood-brain barrier (BBB), but studies have not examined whether inflammation increases or decreases iron flux across the BBB. Our recent in vitro study discovered a novel alternate mechanism that iron transport across the BBB is mediated via the extracellular vesicles (EVs). Herein, we investigated the impact of brain inflammation on iron release and iron transport via EVs from the brain microvasculature (BMV). MethodsFor this study, we developed an in vivo brain inflammation model. We induced brain inflammation in three-month-old C57BL/6 by intracerebroventricular injection of lipopolysaccharide (LPS,12g/mice). For in vitro, we used human blood-brain barrier endothelial cells derived from human-induced pluripotent stem cells (hiPSCs). We separated the BMV from brain parenchyma by using density gradient centrifugation. To inhibit the EVs synthesis, we injected intraperitoneally for 21 days GW4869 (60g/mice), an inhibitor of neutral sphingomyelinase 2, a key regulatory enzyme necessary for EV formation. The brain EVs were isolated by ultracentrifugation. We measured the BMV and parenchyma iron concentration by Inductively coupled plasma mass spectrometry (ICP-MS). Furthermore, we performed immunoblotting to measure the protein expression in BMV and EVs. ResultsThe LPS injection activated microglia and astrocytes as well as increased the brain proinflammatory cytokines compared to the control mice. Furthermore, brain inflammation increased the iron levels in the brain parenchyma but decreased the iron levels in BMV. Brain inflammation was associated with the degradation of ferroportin (FPN1), an iron exporter, in the BMV. CD63, an EVs membrane protein, was increased in the BMV and associated with increased FTH1-iron release via EVs from BMVs to the brain. Moreover, brain inflammation induced iron deficiency in BMV as evidenced by an increase in the transferrin receptor and decreased FTH1, suggestive of increased iron uptake. Pharmacological reduction of EVs by GW4869 reduced iron accumulation in the inflamed brain parenchyma compared to control mice. ConclusionThis is the first study to demonstrate that EV inhibition decreases iron in the brain. Degradation of FPN1 in the BMV during inflammation did not limit iron accumulation but there was an increase in FTH1-iron-enriched EVs indicating these are responsible for brain iron accumulation during inflammation. Thus, in summary, we have discovered a novel mechanism that involves BMV-released EVs enriched with iron that is the mechanism for brain iron accumulation during inflammation.

neuroscience↗

bioRxiv2017

Inhibition of the Platelet-activating factor receptor for the treatment of Amyotrophic Lateral Sclerosis?

Cerebrospinal Fluids (CSF) of Amyotrophic Lateral Sclerosis (ALS) patients have increased levels of the inflammatory cytokine IL-18. Because IL-18 is produced by dendritic cells stimulated by the Platelet-activating factor (PAF), a major neuroinflammatory mediator, it is expected that PAF is involved in ALS. Pilot experimental data on amplification of PAF receptor (PAFR) mRNA by RT-PCR show that PAFR is overexpressed, as compared to age matched controls, in the spinal cords of transgenic ALS mouse model SOD1-G93A, suggesting PAF mediation. Although anti-inflammatory drugs have been tested for ALS before, no clinical trial has been conducted using PAFR specific inhibitors. Therefore, we hypothesize that administration of PAFR inhibitors, such as Ginkgolide B, PCA 4248 and WEB 2086, have potential to function as a novel therapy for ALS, particularly in SOD1 familial ALS forms. Because currently there are only two approved drugs with modest effectiveness for ALS therapy, a search for novel drugs and targets is essential.

neuroscience↗