Iron Deposition and Ferroptosis in the Spleen in a Murine Model of Acute Radiation Syndrome

Euphorbia humifusa Willd. ex Schltdl. Mitigates Liver Injury via KEAP1-NFE2L2-Mediated Ferroptosis Regulation: Network Pharmacology and Experimental Validation

Liver injury poses major health risks in livestock, necessitating effective therapeutic interventions. This study elucidates the hepatoprotective mechanisms of Euphorbia humifusa Willd. ex Schltdl. (EHW) by integrating network pharmacology, molecular docking, and experimental validation. Using a CCl4-induced liver injury model mimicking veterinary clinical scenarios, EHW markedly alleviated hepatic damage, demonstrated by reduced liver index, serum ALT and AST levels, histopathological lesions, iron accumulation, inflammatory cytokines, and ferroptosis-associated gene expression. Network pharmacology identified EHW's core bioactive components (quercetin, kaempferol, and β-sitosterol) and critical targets (IL-6, STAT3, HIF-1α, PTGS2, NFE2L2, and KEAP1) which were linked to ferroptosis and oxidative stress. Molecular docking revealed robust binding affinities between these compounds and ferroptosis-related proteins. In vivo validation confirmed that EHW inhibited KEAP1, activated NFE2L2-mediated antioxidant defenses (upregulating SOD1 and NQO1), restored iron homeostasis (lowering TFR1, elevating FTH1), and attenuated phospholipid peroxidation by suppressing ACSL4 and ALOX12. These results indicate that EHW mitigates ferroptosis-driven liver injury via KEAP1-NFE2L2 signaling to restore iron homeostasis and reduce oxidative stress, offering a mechanistic foundation for its clinical application in veterinary hepatoprotection.

Advances in the Regulation of Hematopoietic Homeostasis by Programmed Cell Death Under Radiation Conditions

The application of nuclear energy and the frequent occurrence of nuclear contamination have made radiation safety a major challenge to global public health. As a radiation-sensitive target organ, bone marrow is susceptible to both acute and chronic damage effects of ionizing radiation on the hematopoietic system. Researchers have demonstrated that radiation disrupts hematopoietic homeostasis through direct damage to hematopoietic stem cells, which inhibits hematopoietic regeneration indirectly through damage to hematopoietic progenitor cells and their downstream cell populations. However, the multi-target regulatory mechanism of radiation perturbation of hematopoietic homeostasis remains to be systematically elucidated. Recent studies have revealed that, in addition to the classical apoptotic pathway, non-apoptotic programmed cell death modes (e.g. pyroptosis, necroptosis, and ferroptosis) may be involved in the regulation of radiation-induced hematopoietic injury. A systematic review of the roles of the aforementioned programmed death pathways was presented in radiation-damaged hematopoietic cells, with a view to providing a scientific basis for targeted intervention in radiation-induced myelosuppression.

Fraxetin inhibits IKKβ, blocks NF-κB pathway and NLRP3 inflammasome activation, and alleviates spleen injury in sepsis

Sepsis is a systemic inflammatory condition associated with severe organ failure, particularly splenic injury. Fraxetin (Fra), a natural product isolated from ash bark, exhibits anti-inflammatory and antioxidant properties. This study explores the function and mechanism of Fra in sepsis-induced splenic injury using an in vivo mouse model induced by Cecal Ligation and Puncture and an in vitro sepsis model based on LPS/ATP co-stimulated J774A.1 cells. The experimental groups are as follows: Sham operation or control group, Fra control group, CLP or LPS/ATP group, CLP + Fra group or LPS/ATP + Fra group, with Dexamethasone as a positive control. The results indicated that Fra improved the survival rate, inhibited bacteria burden, and reduced spleen edema. Fra also alleviated spleen necrosis, and restored the structural integrity. Blood results showed that Fra restored platelet count and lymphocyte percentage, reduced neutrophil ratio and C-reactive protein increase, and prevented lymphocyte depletion. Immunohistochemistry demonstrated that Fra inhibited MPO levels. Additionally, Fra downregulated Procalcitonin, inhibited pro-inflammatory cytokines, NO release and Arg-1 expression, illustrating its anti-inflammatory effects. DHE staining revealed that Fra inhibited ROS and MDA, enhanced CAT, GSH-PX, and SOD activities. Furthermore, Fra inhibited NLRP3 inflammasome activation, p-IKKβ expression and NF-κB pathway. Mechanistically, molecular docking studies revealed that Fra could bind to IKKβ, thereby blocking the NF-κB pathway and NLRP3 inflammasome, functioning anti-inflammatory effects. In summary, Fra targets IKKβ to block the NF-κB pathway and NLRP3 inflammasome activation, alleviating sepsis-induced splenic injury, making it a promising therapeutic strategy for treating sepsis-induced splenic injury.

X-ray Fluorescence Microscopy to Develop Elemental Classifiers and Investigate Elemental Signatures in BALB/c Mouse Intestine a Week after Exposure to 8 Gy of Gamma Rays

Iron redistribution in the intestine after total body irradiation is an established phenomenon. However, in the literature, there are no reports about the use of X-ray fluorescence microscopy or equivalent techniques to generate semi-quantitative 2D maps of iron in sectioned intestine samples from irradiated mice. In this work, we used X-ray fluorescence microscopy (XFM) to map the elemental content of iron as well as phosphorus, sulfur, calcium, copper and zinc in tissue sections of the small intestine from eight-week-old BALB/c male mice that developed gastrointestinal acute radiation syndrome (GI-ARS) in response to exposure to 8 Gray of gamma rays. Seven days after irradiation, we found that the majority of the iron is localized as hot spots in the intercellular regions of the area surrounding crypts and stretching between the outer perimeter of the intestine and the surface cell layer of villi. In addition, this study represents our current efforts to develop elemental cell classifiers that could be used for the automated generation of regions of interest for analyses of X-ray fluorescence maps. Once developed, such a tool will be instrumental for studies of effects of radiation and other toxicants on the elemental content in cells and tissues. While XFM studies cannot be conducted on living organisms, it is possible to envision future scenarios where XFM imaging of single cells sloughed from the human (or rodent) intestine could be used to follow up on the progression of GI-ARS.

Role of ferroptosis in radiation-induced soft tissue injury

Ionizing radiation has been pivotal in cancer therapy since its discovery. Despite its therapeutic benefits, IR causes significant acute and chronic complications due to DNA damage and the generation of reactive oxygen species, which harm nucleic acids, lipids, and proteins. While cancer cells are more vulnerable to ionizing radiation due to their inefficiency in repairing damage, healthy cells in the irradiated area also suffer. Various types of cell death occur, including apoptosis, necrosis, pyroptosis, autophagy-dependent cell death, immunogenic cell death, and ferroptosis. Ferroptosis, driven by iron-dependent lipid peroxide accumulation, has been recognized as crucial in radiation therapy's therapeutic effects and complications, with extensive research across various tissues. This review aims to summarize the pathways involved in radiation-related ferroptosis, findings in different organs, and drugs targeting ferroptosis to mitigate its harmful effects.

Quercetin Inhibits Neuronal Pyroptosis and Ferroptosis by Modulating Microglial M1/M2 Polarization in Atherosclerosis

Atherosclerosis (AS) with iron and lipid overload and systemic inflammation is a risk factor for Alzheimer's disease. M1 macrophage/microglia participate in neuronal pyroptosis and recently have been reported to be the ferroptosis-resistant phenotype. Quercetin plays a prominent role in preventing and treating neuroinflammation, but the protective mechanism against neurodegeneration caused by iron deposition is poorly understood. ApoE-/- mice were fed a high-fat diet with or without quercetin treatment. The Morris water maze and novel object recognition tests were conducted to assess spatial learning and memory, and nonspatial recognition memory, respectively. Prussian blue and immunofluorescence staining were performed to assess the iron levels in the whole brain and in microglia, microglia polarization, and the degree of microglia/neuron ferroptosis. In vitro, we further explored the molecular biological alterations associated with microglial polarization, neuronal pyroptosis, and ferroptosis via Western blot, flow cytometry, CCK8, LDH, propidium iodide, and coculture system. We found that quercetin improved brain lesions and spatial learning and memory in AS mice. Iron deposition in the whole brain or microglia was reversed by the quercetin treatment. In the AS group, the colocalization of iNOS with Iba1 was increased, which was reversed by quercetin. However, the colocalization of iNOS with PTGS2/TfR was not increased in the AS group, suggesting a character resisting ferroptosis. Quercetin induced the expression of Arg-1 and decreased the colocalizations of Arg-1 with PTGS2/TfR. In vitro, ox-LDL combined with ferric ammonium citrate treatment (OF) significantly shifted the microglial M1/M2 phenotype balance and increased the levels of free iron, ROS, and lipid peroxides, which was reversed by quercetin. M1 phenotype induced by OF caused neuronal pyroptosis and was promoted to ferroptosis by L-NIL treatment, which contributed to neuronal ferroptosis as well. However, quercetin induced the M1 to M2 phenotype and inhibited M2 macrophages/microglia and neuron pyroptosis or ferroptosis. In summary, quercetin alleviated neuroinflammation by inducing the M1 to M2 phenotype to inhibit neuronal pyroptosis and protected neurons from ferroptosis, which may provide a new idea for neuroinflammation prevention and treatment.

Ferroptosis, Inflammation, and Microbiome Alterations in the Intestine in the Göttingen Minipig Model of Hematopoietic-Acute Radiation Syndrome

Hematopoietic acute radiation syndrome (H-ARS) involves injury to multiple organ systems following total body irradiation (TBI). Our laboratory demonstrated that captopril, an angiotensin-converting enzyme inhibitor, mitigates H-ARS in Göttingen minipigs, with improved survival and hematopoietic recovery, as well as the suppression of acute inflammation. However, the effects of captopril on the gastrointestinal (GI) system after TBI are not well known. We used a Göttingen minipig H-ARS model to investigate captopril's effects on the GI following TBI (60Co 1.79 or 1.80 Gy, 0.42-0.48 Gy/min), with endpoints at 6 or 35 days. The vehicle or captopril (0.96 mg/kg) was administered orally twice daily for 12 days, starting 4 h post-irradiation. Ilea were harvested for histological, protein, and RNA analyses. TBI increased congestion and mucosa erosion and hemorrhage, which were modulated by captopril. GPX-4 and SLC7A11 were downregulated post-irradiation, consistent with ferroptosis at 6 and 35 days post-irradiation in all groups. Interestingly, p21/waf1 increased at 6 days in vehicle-treated but not captopril-treated animals. An RT-qPCR analysis showed that radiation increased the gene expression of inflammatory cytokines IL1B, TNFA, CCL2, IL18, and CXCL8, and the inflammasome component NLRP3. Captopril suppressed radiation-induced IL1B and TNFA. Rectal microbiome analysis showed that 1 day of captopril treatment with radiation decreased overall diversity, with increased Proteobacteria phyla and Escherichia genera. By 6 days, captopril increased the relative abundance of Enterococcus, previously associated with improved H-ARS survival in mice. Our data suggest that captopril mitigates senescence, some inflammation, and microbiome alterations, but not ferroptosis markers in the intestine following TBI.

Ferulic acid protects against gamma-radiation induced liver injury via regulating JAK/STAT/Nrf2 pathways

This study aims to evaluate the effect and underlying mechanism of ferulic acid (FA) in alleviating the acute liver injury by ionizing radiation (IR) in vivo. Rats were divided into 4groups (Groups: control, 6Gy irradiated (IRR), FA (50 mg/kg) and FA + IRR). The results showed that FA can effectively inhibit liver damage and restore the structure and function of the liver. In mechanism, FA prevented IR-induced liver fibrosis and blocked the JAK/STAT signaling pathway to effectively inhibit the hepatic inflammatory response; and inhibited IR-induced oxidative stress (OS) by upregulating the Nrf2 signaling pathway and promoting the synthesis of several antioxidants. Moreover, FA inhibited ferroptosis in the liver by stimulating the expression of GPX4 and SLC7A11. FA reduced lipid peroxidation by downregulation of the reactive oxygen species (ROS) production and iron aggregation, thus inhibiting ferroptosis and alleviating IR-induced liver injury. In conclusion, the current study suggests the potential complex mechanisms underlying the mitigating impact of FA in IR-induced ferroptotic liver damage.

Iron Deposition in the Bone Marrow and Spleen of Nonhuman Primates with Acute Radiation Syndrome

The risk of exposure to high levels of ionizing radiation from nuclear weapons or radiological accidents is an increasing world concern. Partial- or total-body exposure to high doses of radiation is potentially lethal through the induction of acute radiation syndrome (ARS). Hematopoietic cells are sensitive to radiation exposure; white blood cells primarily undergo apoptosis while red blood cells (RBCs) undergo hemolysis. Several laboratories demonstrated that the rapid hemolysis of RBCs results in the release of acellular iron into the blood. We recently demonstrated using a murine model of ARS after total-body irradiation (TBI) and the loss of RBCs, iron accumulated in the bone marrow and spleen, notably between 4-21 days postirradiation. Here, we investigated iron accumulation in the bone marrow and spleens from TBI nonhuman primates (NHPs) using histological stains. We observed trends in increased intracellular and extracellular brown pigmentation in the bone marrow after various doses of radiation, especially after 4-15 days postirradiation, but these differences did not reach significance. We observed a significant increase in Prussian blue-staining intracellular iron deposition in the spleen 13-15 days after 5.8-8.5 Gy of TBI. We observed trends of increased iron in the spleen after 30-60 days postirradiation, with varying doses of radiation, but these differences did not reach significance. The NHP model of ARS confirms our earlier findings in the murine model, showing iron deposition in the bone marrow and spleen after TBI.

Transcriptomic Profiling and Pathway Analysis of Mesenchymal Stem Cells Following Low Dose-Rate Radiation Exposure

Low dose-rate radiation exposure can occur in medical imaging, as background from environmental or industrial radiation, and is a hazard of space travel. In contrast with high dose-rate radiation exposure that can induce acute life-threatening syndromes, chronic low-dose radiation is associated with Chronic Radiation Syndrome (CRS), which can alter environmental sensitivity. Secondary effects of chronic low dose-rate radiation exposure include circulatory, digestive, cardiovascular, and neurological diseases, as well as cancer. Here, we investigated 1-2 Gy, 0.66 cGy/h, ⁶⁰Co radiation effects on primary human mesenchymal stem cells (hMSC). There was no significant induction of apoptosis or DNA damage, and cells continued to proliferate. Gene ontology (GO) analysis of transcriptome changes revealed alterations in pathways related to cellular metabolism (cholesterol, fatty acid, and glucose metabolism), extracellular matrix modification and cell adhesion/migration, and regulation of vasoconstriction and inflammation. Interestingly, there was increased hypoxia signaling and increased activation of pathways regulated by iron deficiency, but Nrf2 and related genes were reduced. The data were validated in hMSC and human lung microvascular endothelial cells using targeted qPCR and Western blotting. Notably absent in the GO analysis were alteration pathways for DNA damage response, cell cycle inhibition, senescence, and pro-inflammatory response that we previously observed for high dose-rate radiation exposure. Our findings suggest that cellular gene transcription response to low dose-rate ionizing radiation is fundamentally different compared to high-dose-rate exposure. We hypothesize that cellular response to hypoxia and iron deficiency are driving processes, upstream of the other pathway regulation.

Pro- and Anti-Tumoral Factors Involved in Total Body Irradiation and Interleukin-2 Conditioning in Adoptive T Cell Therapy of Melanoma-Bearing Rag1 Knock-Out Mice

In adoptive T cell therapy (ACT), the transfer of tumor-specific T cells is paralleled by the conditioning regimen to increase therapeutic efficacy. Pre-conditioning depletes immune-suppressive cells and post-conditioning increases homeostatic signals to improve the persistence of administered T cells. Identifying the favorable immunological factors involved in a conditioning regimen is important to design effective strategies in ACT. Here, by using an ACT model of murine melanoma, we evaluate the effect of the total body irradiation (TBI) and interleukin-2 (IL-2) treatment combination. The use of a Rag1 knock-out strain, which lacks endogenous T cells, enables the identification of factors in a way that focuses more on transferred T cells. We demonstrate that the TBI/IL-2 combination has no additive effect in ACT, although each conditioning improves the therapeutic outcome. While the combination increases the frequency of transferred T cells in lymphoid and tumor tissues, the activation intensity of the cells is reduced compared to that of the sole TBI treatment. Notably, we show that in the presence of TBI, the IL-2 treatment reduces the frequency of intra-tumoral dendritic cells, which are crucial for T cell activation. The current study provides insights into the immunological events involved in the TBI/IL-2 combination in ACT.