Biology subjects

Sahu, A. P.

Publications and source records attributed to Sahu, A. P..

3 recordsLinked to original sources

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

Tumor-associated macrophages protect glioblastoma cells from ferroptosis by inducing the release of ferritin-bound iron via exosomes.

Tumor-associated macrophages (TAMs) are the most abundant non-tumor cell type in glioblastoma (GBM) and act as the pivotal cell type in regulating iron metabolism in the GBM tumor microenvironment. High TAM infiltration into the TME is also associated with increased resistance to ferroptosis, an iron-dependent cell death. However, the exact mechanism by which TAMs make the cancer cells resistant to ferroptosis remains relatively unexplored. Here, we have investigated how TAMs modify iron metabolism in GBM cells to make them more resistant to ferroptotic stress. We utilized GL261 cells, a GBM cell line derived from C57BL6 mice, and syngeneic primary murine bone marrow-derived macrophages (BMDM) to study GBM-TAM interactions in vitro. We found that male macrophages exhibited higher iron uptake, greater iron storage, and a larger labile iron pool compared to female macrophages, indicating intrinsic sex biases in macrophage iron metabolism. Subsequently, we used co-culture experiments to study how macrophages regulate the iron and ferroptotic status of GL261 cells. We discovered that GL261 cells cocultured with BMDMs showed higher resistance to RSL3-induced ferroptotic stress. Mechanistically, BMDMs caused a decrease in total cellular iron in GL261 cells by inducing increased H-ferritin-bound iron release via CD63-positive exosomes; thus, limiting the amount of iron that is available for lipid peroxidation during ferroptosis. This process was moderately sex biased in favor of male macrophages. Finally, we show that this mechanism of BMDM-induced resistance to ferroptosis is independent of Hepcidin regulation and can act as a possible pathway by which GBM cells escape ferroptotic stress during proinflammatory conditions.

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↗