Expression Of DMT1 Research Articles

Iron homeostasis, recycling and vulnerability in the stressed kidney: A neglected dimension of iron-deficient heart failure.

The available evidence suggests that the kidney may contribute importantly to the development of an iron deficiency state in patients with heart failure and may be injured by therapeutic efforts to achieve iron repletion. The exceptional workload of the proximal renal tubule requires substantial quantities of iron for ATP synthesis, which it derives from Fe3+ bound to transferrin in the bloodstream. Following ferrireduction, Fe2+ is conveyed by divalent transporters (e.g. DMT1) out of the endosome of the proximal renal tubule, and highly reactive Fe2+ can be directed to the mitochondria, sequestered safely in a ferritin nanocage or exported through the actions of hepcidin-inhibitable ferroportin. The actions of ferroportin, together with transferrin endocytosis and DMT1-mediated transport, play a key role in the recycling of iron from the tubular fluid into the bloodstream and preventing the loss of filtered iron in the urine. Activation of endogenous neurohormonal systems and proinflammatory signalling in heart failure decrease megalin-mediated uptake and DMT1 expression, and increase hepcidin-mediated suppression of ferroportin, promoting the loss of iron in the urine and contributing to the development of an iron deficiency state. Furthermore, the failure of ferroportin-mediated efflux at the basolateral membrane heightens the susceptibility of the renal tubules to cytosolic excesses of Fe2+, causing lipid peroxidation and synchronized cell death (ferroptosis) through the iron-dependent free radical theft of electrons from lipids in the cell membrane. Ferroptosis is a central mechanism to most disorders that can cause acute and chronic kidney disease. Short-term bolus administration of intravenous iron can cause oxidative stress and is accompanied by markers of renal injury. Experimentally, long-term maintenance of an iron-replete state is accompanied by accelerated loss of nephrons, oxidative stress, inflammation and fibrosis. Intravenous iron therapy increases glomerular filtration rate rapidly in patients with heart failure (perhaps because of a haemodynamic effect) but not in patients with chronic kidney disease, and the effects of intravenous iron on the progression of renal dysfunction in the long-term trials - AFFIRM-AHF, IRONMAN and HEART-FID - have not yet been reported. Given the potential role of dysregulated renal iron homeostasis in the pathogenesis of iron deficiency and the known vulnerability of the kidney to intravenous iron, the appropriate level of iron repletion with respect to the risk of acute and chronic kidney injury in patients with heart failure requires further study.

Myeloid Ptpn2 Deficiency in Mice Causes Functional Iron Deficiency

Background: Anemia is the most prevalent extraintestinal complication of inflammatory bowel disease (IBD) and is associated with the manifestation of Crohn’s disease. Anemia significantly reduces the quality of life, increases hospitalization visits, and increases medical care expenses of IBD patients. Iron deficiency is the leading cause of anemia in IBD; however, the physiological mechanisms involved are still poorly understood. Macrophages significantly contribute to iron homeostasis by mechanisms including iron recycling by phagocytosing senescent erythrocytes and damaged cells, and nurturing erythropoiesis in the bone marrow. In this study, we investigated the role of the IBD candidate gene, protein tyrosine phosphatase non-receptor type 2 ( PTPN2), in regulating macrophage iron homeostasis. Methods: Myeloid cell-specific knockout mice ( Ptpn2LysMCre) and control littermates ( Ptpn2fl/fl) were analyzed for serum iron content and liver and spleen non-heme iron. Duodenal epithelial cell (DEC) proteins were assayed by Western blotting. Localization of the brush border ferrous iron transporter, DMT1, and the coupled ferrous iron absorption driver, NHE3, in duodenal tissue was determined by immunohistochemistry (IHC). Gene expression profiles of macrophages were analyzed by Nanostring. Results: Ptpn2LysMCre mice had reduced serum iron ( p<0.0001; n=12) and reduced spleen non-heme iron (p=0.0017; n=6), whereas liver non-heme iron was unaltered (n=6), indicating iron deficiency in select tissues. DMT1 (n=8) and NHE3 (n=5) protein expression in DECs was unaltered and IHC confirmed the unaltered localization of DMT1 and NHE3 (n=6) in the duodenal epithelium of Ptpn2LysMCre mice, suggesting the reduction in serum iron was not due to an impairment in intestinal non-heme iron uptake. Nanostring analyses revealed that the gene expression of the iron transporter Dmt1, iron exporter Fpn, and iron importer Tfr1 were significantly downregulated (p<0.05; n=5) in macrophages from Ptpn2LysMCre mice, indicating an iron sequestering phenotype. Conclusions: Loss of myeloid Ptpn2 in mice causes functional iron deficiency. These findings indicate a major role of myeloid PTPN2 in regulating systemic iron homeostasis. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

DMT1 contributes to MF- 438 - mediated inhibition of glioma cells.

Elevated SCD1 expression has been associated with enhanced cancer cell survival, proliferation, and resistance to therapy in many cancer types including gliomas. Hereby, we investigate the impact of MF-438 on SCD1-mediated lipid metabolism and its consequences on glioma growth and survival. Our data reveals an IDH mut -specific inhibitory effect of MF438 on gliomas. Also, we delineate a dual mechanism of action: while SCD1-mediated lipid metabolism is hindered by MF-438 treatment, MF-438 also exerts an SCD1-independent inhibition on DMT1 expression. Supporting data from the DMT1 blocker underscores its significance in MF-438's anti-glioma efficacy.

MaiJiTong granule attenuates atherosclerosis by reducing ferroptosis via activating STAT6-mediated inhibition of DMT1 and SOCS1/p53 pathways in LDLR−/− mice

Background and PurposeAtherosclerosis is the primary pathological basis of cardiovascular disease. Ferroptosis is a regulated form of cell death, a process of lipid peroxidation driven by iron, which can initiate and promote atherosclerosis. STAT6 is a signal transducer that shows a potential role in regulating ferroptosis, but, the exact role in ferroptosis during atherogenesis remains unclear. The Traditional Chinese Medicine Maijitong granule (MJT) is used for treating cardiovascular disease and shows a potential inhibitory effect on ferroptosis. However, the antiatherogenic effect and the underlying mechanism remain unclear. In this study, we determined the role of STAT6 in ferroptosis during atherogenesis, investigated the antiatherogenic effect of MJT, and determined whether its antiatherogenic effect was dependent on the inhibition of ferroptosis. Methods8-week-old male LDLR−/− mice were fed a high-fat diet (HFD) at 1st and 10th week, respectively, to assess the preventive and therapeutic effects of MJT on atherosclerosis and ferroptosis. Simultaneously, the anti-ferroptotic effects and mechanism of MJT were determined by evaluating the expression of genes responsible for lipid peroxidation and iron metabolism. Subsequently, we reanalyzed microarray data in the GSE28117 obtained from cells after STAT6 knockdown or overexpression and analyzed the correlation between STAT6 and ferroptosis. Finally, the STAT6−/− mice were fed HFD and injected with AAV-PCSK9 to validate the role of STAT6 in ferroptosis during atherogenesis and revealed the antiatherogenic and anti-ferroptotic effect of MJT. ResultsMJT attenuated atherosclerosis by reducing plaque lesion area and enhancing plaque stability in both preventive and therapeutic groups. MJT reduced inflammation via suppressing inflammatory cytokines and inhibited foam cell formation by lowering the LDL level and promoting ABCA1/G1-mediated lipid efflux. MJT ameliorated the ferroptosis by reducing lipid peroxidation and iron dysregulation during atherogenesis. Mechanistically, STAT6 negatively regulated ferroptosis by transcriptionally suppressing SOCS1/p53 and DMT1 pathways. MJT suppressed the DMT1 and SOCS1/p53 via stimulating STAT6 phosphorylation. In addition, STAT6 knockout exacerbated atherosclerosis and ferroptosis, which abolished the antiatherogenic and anti-ferroptotic effects of MJT. ConclusionSTAT6 acts as a negative regulator of ferroptosis and atherosclerosis via transcriptionally suppressing DMT1 and SOCS1 expression and MJT attenuates atherosclerosis and ferroptosis by activating the STAT6-mediated inhibition of DMT1 and SOCS1/p53 pathways, which indicated that STAT6 acts a novel promising therapeutic target to ameliorate atherosclerosis by inhibiting ferroptosis and MJT can serve as a new therapy for atherosclerosis treatment.

PM2.5 induce neurotoxicity via iron overload and redox imbalance mediated-ferroptosis in HT22 cells

PM2.5 is an important risk factor for the development and progression of cognitive impairment-related diseases. Ferroptosis, a new form of cell death driven by iron overload and lipid peroxidation, is proposed to have significant implications. To verify the possible role of ferroptosis in PM2.5-induced neurotoxicity, we investigated the cytotoxicity, intracellular iron content, iron metabolism-related genes, oxidative stress indices and indicators involving in Nrf2 and ferroptosis signaling pathways. Neurotoxicity biomarkers as well as the ferroptotic cell morphological changes were determined by Western Blot and TEM analysis. Our results revealed that PM2.5 induced cytotoxicity, lipid peroxidation, as indicated by MDA content, and neurotoxicity via Aβ deposition in a dose-related manner. Decreased cell viability and excessive iron accumulation in HT-22 cells can be partially blocked by ferroptosis inhibitors. Interestingly, GPX activity, Nrf2, and its regulated ferroptotic-related proteins (i.e. GPX4 and HO-1) were significantly up-regulated by PM2.5. Moreover, gene expression of DMT1, TfR1, IRP2 and FPN1 involved in iron homeostasis and NCOA4-dependent ferritinophagy were activated after PM2.5 exposure. The results demonstrated that PM2.5 triggered ferritinophagy-dependent ferroptotic cell death due to iron overload and redox imbalance. Activation of Nrf2 signaling pathways may confer a protective mechanism for PM2.5-induced oxidative stress and ferroptosis.

Conventional and germinated pearl millet flour (Pennisetum glaucum (L.) R. Br.) improves iron metabolism and antioxidant capacity in Wistar rats

The study evaluated the effect of the consumption of pearl millet whole grain pre-cooked conventional, germinated and extruded flours on iron metabolism and antioxidant capacity in rats. The animals received iron-free standard diet (SD iron-free) for 28 days and subsequently, were separated into 4 groups: ferrous sulfate (SD + FS), conventional millet flour (SD + CM), germinated millet flour (SD + GM), and extruded millet flour (SD + EM), for 21 days. The SD iron free group presented increased ferroportin, hephaestin and ferritin gene expression and MDA concentration compared to the SD + FS group. The SD + GM group increased DcytB, ferroportin and hephaestin gene expression. The SD + EM group increased the concentration of transferrin compared to the SD + FS group and serum iron, compared to the other groups, while reducing the liver's total antioxidant capacity (TAC). The SD + CM group increased ferritin expression. All test groups increased the gene expression of DMT1 and hephaestin, as well as serum iron and reduced transferrin, Nrf2 and TNF gene expression, and MDA, NO, SOD and CAT levels in relation to the SD + FS group. In view of this, millet provides promising bioavailability of iron. Besides, germination stands out for improving iron metabolism in relation to extrusion and is similar to conventional millet in antioxidant capacity.

Protective effect of Angelica sinensis polysaccharide on pregnant rats suffering from iron deficiency anemia via regulation of the hepcidin-FPN1 axis

Iron deficiency anemia (IDA) is a common micronutrient deficiency among pregnant women with deleterious maternal and fetal outcomes. Angelica sinensis polysaccharide (ASP) has been shown to reduce hepcidin expression in IDA rats. However, the role of ASP in the treatment of IDA during pregnancy and its potential mechanisms have not been investigated. Moreover, the effect of ASP on duodenal iron absorption is not clear. The aim of this study was to investigate the preventive efficacy of ASP against IDA during pregnancy and clarify the underlying mechanisms. Our results showed that ASP improved maternal hematological parameters, increased serum iron, maternal tissue iron, and fetal liver iron content, and improved pregnancy outcomes. Additionally, ASP combated oxidative stress caused by iron deficiency by improving the body's antioxidant capacity. Western blot results demonstrated that ASP downregulated hepcidin expression by blocking the BMP6/SMAD4, JAK2/STAT3 and TfR2/HFE signaling pathways, which in turn increased the expression of FPN1 in the liver, spleen, and duodenum and promoted iron cycling in the body. Furthermore, ASP increased the expression of DMT1 and Dcytb in the duodenum, thereby facilitating duodenal iron uptake. Our results suggest that ASP is a potential agent for the prevention and treatment of IDA during pregnancy.

Enriched environment attenuates ferroptosis after cerebral ischemia/reperfusion injury by regulating iron metabolism

Preventing neuronal death after ischemic stroke (IS) is crucial for neuroprotective treatment, yet current management options are limited. Enriched environment (EE) is an effective intervention strategy that promotes the recovery of neurological function after cerebral ischemia/reperfusion (I/R) injury. Ferroptosis has been identified as one of the mechanisms of neuronal death during IS, and inhibiting ferroptosis can reduce cerebral I/R injury. Our previous research has demonstrated that EE reduced ferroptosis by inhibiting lipid peroxidation, but the underlying mechanism still needs to be investigated. This study aims to explore the potential molecular mechanisms by which EE modulates iron metabolism to reduce ferroptosis. The experimental animals were randomly divided into four groups based on the housing environment and the procedure the animals received: the sham-operated + standard environment (SSE) group, the sham-operated + enriched environment (SEE) group, the ischemia/reperfusion + standard environment (ISE) group, and the ischemia/reperfusion + enriched environment (IEE) group. The results showed that EE reduced IL-6 expression during cerebral I/R injury, hence reducing JAK2-STAT3 pathway activation and hepcidin expression. Reduced hepcidin expression led to decreased DMT1 expression and increased FPN1 expression in neurons, resulting in lower neuronal iron levels and alleviated ferroptosis. In addition, EE also reduced the expression of TfR1 in neurons. Our research suggested that EE played a neuroprotective role by modulating iron metabolism and reducing neuronal ferroptosis after cerebral I/R injury, which might be achieved by inhibiting inflammatory response and down-regulating hepcidin expression.

High Hepcidin Levels Promote Abnormal Iron Metabolism and Ferroptosis in Chronic Atrophic Gastritis.

Chronic atrophic gastritis (CAG) is a chronic inflammatory disease and premalignant lesion of gastric cancer. As an antimicrobial peptide, hepcidin can maintain iron metabolic balance and is susceptible to inflammation. The objective of this study was to clarify whether hepcidin is involved in abnormal iron metabolism and ferroptosis during CAG pathogenesis. Non-atrophic gastritis (NAG) and chronic atrophic gastritis (CAG) patient pathology slides were collected, and related protein expression was detected by immunohistochemical staining. The CAG rat model was established using MNNG combined with an irregular diet. CAG patients and rats exhibited iron deposition in gastric tissue. CAG-induced ferroptosis in the stomach was characterized by decreased GPX4 and FTH levels and increased 4-HNE levels. Hepcidin, which is mainly located in parietal cells, was elevated in CAG gastric tissue. The high gastric level of hepcidin inhibited iron absorption in the duodenum by decreasing the protein expression of DMT1 and FPN1. In addition, the IL-6/STAT3 signaling pathway induced hepcidin production in gastric tissue. Our results showed that the high level of gastric hepcidin induced ferroptosis in the stomach but also inhibited iron absorption in the intestines. Inhibiting hepcidin might be a new strategy for the prevention of CAG in the future.

Effect of replacing inorganic iron with iron-rich microbial preparations on growth performance, serum parameters and iron metabolism of weaned piglets.

This study aimed to investigate the effects of replacing of dietary inorganic iron with iron-rich Lactobacillus plantarum and iron-rich Candida utilis on the growth performance, serum parameters, immune function and iron metabolism of weaned piglets. Fifty-four 28-day-old healthy Duroc × Landrace × Yorkshire castrated male weanling piglets of similar body weight were randomly and equally divided into three groups. The piglets were kept in three pens per group, with six pigs in each pen. The dietary treatments were (1) a basal diet + ferrous sulfate preparation containing 120mg/kg iron (CON); (2) a basal diet + iron-rich Candida utilis preparation containing 120mg/kg iron (CUI); and (3) a basal diet + iron-rich Lactobacillus plantarum preparation containing 120mg/kg iron (LPI). The entire feeding trial lasted for 28 days, after which blood, viscera, and intestinal mucosa were collected. The results showed no significant difference in growth parameters and organ indices of the heart, liver, spleen, lung, and kidney of weaned piglets when treated with CUI and LPI compared with the CON group (P > 0.05). However, CUI and LPI significantly reduced the serum contents of AST, ALP, and LDH (P < 0.05). Serum ALT content was significantly lower in the LPI treatment compared to the CON group (P < 0.05). Compared to CON, CUI significantly increased the contents of serum IgG and IL-4 (P < 0.05), and CUI significantly decreased the content of IL-2. LPI significantly increased the contents of serum IgA, IgG, IgM and IL-4 (P < 0.05), while LPI significant decreased the levels of IL-1β, IL-2, IL-6, IL-8, and TNF-α compared to CON (P < 0.05). CUI led to a significant increase in ceruloplasmin activity and TIBC (P < 0.05). LPI significantly increased the contents of serum Fe and ferritin, and increased the serum ceruloplasmin activity and TIBC compared to CON (P < 0.05). Furthermore, CUI resulted in a significant increase in the relative mRNA expression of FPN1 and DMT1 in the jejunal mucosa (P < 0.05). LPI significantly increased the relative mRNA expression of TF, FPN1, and DMT1 in the jejunal mucosa (P < 0.05). Based on these results, the replacement of dietary inorganic iron with an iron-rich microbial supplement could improve immune function, iron absorption and storage in piglets.

Human umbilical cord mesenchymal stem cells derived exosome shuttling mir-129-5p attenuates inflammatory bowel disease by inhibiting ferroptosis

BackgroundFerroptosis, a unique form of non-apoptotic cell death, is dependent on iron and lipoperoxidation, and has been shown to be associated with the pathogenesis of inflammatory bowel disease (IBD). Human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Ex) are involved in cell survival, immune conditioning, and damage repair. However, the relationship between hucMSC-Ex, IBD, and ferroptosis is unknown. This paper explores the role of hucMSC-Ex in the repair of IBD through the regulation of the ferroptosis signaling pathway.ResultsIn this study, we used small RNA sequencing to find that miR-129-5p was highly expressed in hucMSC-Ex, and by predicting its targeting to ACSL4, we verified the effect of miR-129-5p on mice IBD in vitro and human colonic epithelial cells (HCoEpiC) in vivo. We found that miR-129-5p reduces ferroptosis in intestinal epithelial cells by targeting ACSL4 to repair IBD, which provides new strategies for the prevention and treatment of IBD.ConclusionIn conclusion, our results demonstrate that hucMSC-Ex relieves IBD by targeting ACSL4 with miR-129-5p to inhibit lipid peroxidation (LPO) and ferroptosis, reducing intestinal inflammation and repairing damages.Graphic abstractMechanism of hucMSC-Ex inhibiting ferroptosis in intestinal epithelial cells. System Xc− mediates the transport of extracellular cystine into the cell, which gets reduced to cysteine to participate in GSH-mediated metabolism. GPX4 strongly inhibits ferroptosis by helping scavenge reactive oxygen species. The depletion of GSH correlates with decreased GPX4, and the imbalance of the antioxidant system leads to the formation of toxic phospholipid hydroperoxide, which promotes the occurrence of ferroptosis with the participation of irons. HucMSC-Ex has the ability to relieve GSH and GPX4 depletion and repair the intracellular antioxidant system. Ferric ions enter the cytosol through DMT1 and participate in lipid peroxidation. HucMSC-Ex can reduce the expression of DMT1 and alleviate this process. HucMSC-Ex-derived miR-129-5p targets ACSL4 and reduces the expression of ACSL4, an enzyme that mediates the conversion of PUFAs into phospholipids in intestinal epithelial cells, and is a positive regulator of lipid peroxidation. Abbreviations: GSH, glutathione; GPX4, glutathione peroxidase 4; GSSG, oxidized glutathione; DMT1, divalent metal transporter 1; ACSL4, acyl-CoA synthetase long-chain family member 4; PUFAs, polyunsaturated fatty acids; ALOXs, lipoxygenases; CoA, coenzyme A; PL, phospholipid; PLOOH, hydroperoxides, LOH, phospholipid alcohols; LPO, lipid peroxidation.

Effects of liraglutide on astrocyte polarization and neuroinflammation in db/db mice: focus on iron overload and oxidative stress.

Neuroinflammation plays a crucial role in the occurrence and development of cognitive impairment in type 2 diabetes mellitus (T2DM), but the specific injury mechanism is not fully understood. Astrocyte polarization has attracted new attention and has been shown to be directly and indirectly involved in neuroinflammation. Liraglutide has been shown to have beneficial effects on neurons and astrocytes. However, the specific protection mechanism still needs to be clarified. In this study, we assessed the levels of neuroinflammation and A1/A2-responsive astrocytes in the hippocampus of db/db mice and examined their relationships with iron overload and oxidative stress. First, in db/db mice, liraglutide alleviated the disturbance of glucose and lipid metabolism, increased the postsynaptic density, regulated the expression of NeuN and BDNF, and partially restored impaired cognitive function. Second, liraglutide upregulated the expression of S100A10 and downregulated the expression of GFAP and C3, and decreased the secretion of IL-1β, IL-18, and TNF-α, which may confirm that it regulates the proliferation of reactive astrocytes and A1/A2 phenotypes polarize and attenuate neuroinflammation. In addition, liraglutide reduced iron deposition in the hippocampus by reducing the expression of TfR1 and DMT1 and increasing the expression of FPN1; at the same time, liraglutide by up-regulating the levels of SOD, GSH, and SOD2 expression, as well as downregulation of MDA levels and NOX2 and NOX4 expression to reduce oxidative stress and lipid peroxidation. The above may attenuate A1 astrocyte activation. This study preliminarily explored the effect of liraglutide on the activation of different astrocyte phenotypes and neuroinflammation in the hippocampus of a T2DM model and further revealed its intervention effect on cognitive impairment in diabetes. Focusing on the pathological consequences of astrocytes may have important implications for the treatment of diabetic cognitive impairment.

Oral iron supplementation exacerbates dextran sulfate sodium (DSS)-induced colitis in mice

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) characterized by diarrhea, abdominal pain, and bloody, mucous-laden stools. In one-third of UC patients, severity of blood loss is sufficient to cause iron deficiency anemia, making it the most common extra-intestinal manifestation of UC. Oral iron supplementation is the first line treatment for IDA. However, there is a debate concerning the safety of orally administered iron, as some studies have reported an exacerbation of disease, whereas others report the treatment is well tolerated and effective. Aim: The purpose of this study was to determine the effect of oral iron administration on disease activity in dextran sulfate sodium (DSS)-induced colitis in mice, a model that effectively recapitulates ulcerative colitis. Hypothesis: We hypothesize that iron-supplemented chow will increase disease activity and lead to pathogenic changes in mice with DSS-induced colitis. Methods: Experimental acute colitis (UC) was produced in BALBc/AnNCrl (male and female; 7 weeks old) mice by administration of 3% DSS dissolved in drinking water for 7 days. Control mice received standard water. Normal control (NC) and UC (UC) animals were fed standard chow contained 200 parts per million (ppm) ferrous sulfate (2018 Teklad Global 18% Protein Rodent Diet, Huntingdon, UK), while normal (NCFe) and UC (UCFe) experimental animals were fed an iron-supplemented diet containing 600 ppm ferrous sulfate (2018 Teklad Global 18% Protein Rodent Custom Diet, Huntingdon, UK). Food and water were provided ad libitum. Daily scores for weight loss, stool consistency, and fecal blood content were averaged to produce a disease activity index as previously described by Friedman and co-workers (DAI, 2009). On day-8 post-treatment, mice were euthanized with 5% isoflurane. Length of colon was measured from cecum to rectum, and epithelial cells were isolated from distal colon by EDTA chelation technique. Histopathology, RNA isolation, and qRT-PCR analyses were performed using standard techniques. Results: Food and water consumption were not significantly altered among the 4 groups of mice. Additional iron supplementation significantly: 1) increased DAI; 2) decreased fecal dry weight; and 3) increased blood inflammatory cytokine levels in UCFe as compared to UC group. Colon length was shortened one-third in UC as compared to NC, but was not further significantly altered by iron supplementation. Loss of crypt architecture and increased influx of inflammatory cells identified in UC colon was not significantly altered in colons from the UCFe group. Expression of apical iron importer DMT1 was increased in UC as compared to NC, but not in the UCFe group. In total, there were no differences due to iron supplementation, and no differences were present due to gender. Conclusion: We conclude that iron supplementation increases the severity of colitis by stimulating water secretion. This study was supported by the National Institute of Health NIDDK DK104791 and DK112085 grants This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Constitutive Loss of Ptpn2 in Mice Causes Features of Anemia Including Iron Deficiency

Background: Anemia is the most frequent extraintestinal manifestation of inflammatory bowel disease (IBD) and is associated with the risk of Crohn’s disease. Anemia significantly impairs quality of life, increases hospitalization rates, and increases medical care costs of IBD patients. Iron deficiency is the most frequent cause of anemia in IBD; however, the mechanisms involved are still poorly understood. Here, we investigated the role of the IBD risk gene, protein tyrosine phosphatase non-receptor type 2 ( PTPN2), in regulating iron homeostasis. Methods: Constitutive Ptpn2 wild type (WT), heterozygous (Het), and knockout (KO) 3-week-old mice were analyzed for serum iron content, complete blood count parameters, and intestinal and extraintestinal non-heme iron. Protein and RNA from duodenal epithelial cells (DECs) were assayed by western blotting and qPCR. Localization of the brush border ferrous iron transporter, DMT1, and the ferrous iron absorption driver, NHE3, in duodenal tissue was determined by immunohistochemistry (IHC). Results: Ptpn2-KO mice had reduced i) serum iron ( p=0.0007; n=10); ii) serum iron carrier transferrin saturation ( p=0.0077; n=8); iii) hemoglobin ( p=0.0002; n=5); iv) hematocrit ( p=0.0023; n=5); v) intestinal non-heme iron: duodenum ( p=0.0128; n=10) and jejunum ( p=0.0006; n=8); and vi) extraintestinal tissue non-heme iron: liver ( p=0.0014; n=10), spleen ( p=0.04; n=10), kidney ( p=0.0004; n=7), and gastrocnemius muscle ( p=0.0436; n=9) vs. Ptpn2-WT and Het mice. This indicated that loss of Ptpn2 causes characteristics of anemia including decreased serum iron and tissue iron storage and impaired intestinal iron homeostasis. DEC gene expression of the intracellular iron storage molecule ferritin ( Fth1) was reduced ( p=0.048; n=4) while the basolateral cellular iron importer transferrin receptor 1 ( Tfrc1) was significantly increased ( p=0.0048; n=5) in Ptpn2-KO mice. Reduced FTH1 protein expression ( p=0.007; n=12) and increased TFRC1 protein expression ( p=0.0021; n=8) in DECs of Ptpn2-KO mice was confirmed by western blot, indicating cellular iron deficiency. DMT1 (n=6) and NHE3 (n=8) protein expression in DECs was unaltered, whereas IHC showed reduced apical membrane DMT1 and NHE3 in the duodenal epithelium of Ptpn2-KO mice (n=6), suggesting a possible mechanism of impaired intestinal non-heme iron uptake. Conclusions: Loss of Ptpn2 in mice causes features of anemia including iron deficiency associated with mislocalization of DMT1 and reduced apical membrane expression of NHE3. These findings identify a critical role for PTPN2 in regulating systemic iron homeostasis. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Impact of maternal iron deficiency anemia on fetal iron status and placental iron transporters in human pregnancy

Iron deficiency anemia is associated with maternal morbidity and poor pregnancy outcomes. Heme and non-heme iron transport proteins expressed in the placenta help in adequate iron supply from anemic mother to fetus. Here we examined the expression of placental iron trafficking molecules and their association with maternal and neonatal iron status in pregnant women with iron deficiency anemia (IDA). Pregnant women who received prenatal care at Christian Medical College, Vellore, India for childbirth were recruited. Pregnant women who were 18–35 years old with gestational age (GA) of ≥36 weeks were eligible to participate in the study. In a prospective cohort of pregnant women, 22 % were iron deficiency anemia and 42 % were iron replete. Samples were collected (Maternal blood, placental tissue, and cord blood) from pregnant women with a gestational age of ≥38 weeks at the time of delivery. The mean gestational age at the first visit and delivery was 12.8 ± 2.72 weeks and 39 ± 1.65 weeks, respectively. Hemoglobin (9.3 ± 0.9 g/dl) and ferritin (15.4(0.8–28.3) ng/ml) levels at delivery were significantly decreased in IDA as compared to controls. The fetal hemoglobin and ferritin levels were in the normal range in both groups. There was no correlation between maternal and cord blood hepcidin with fetal iron status in IDA. We further analyzed the expression of iron transport genes in the placenta of controls and the IDA group. Under maternal iron insufficiency, the expression of placental iron transporters DMT1, FPN1, and GDF15 was upregulated at the protein level. In IDA, placental GDF15 and ferroportin protein had an association with fetal iron status. These findings confirm that placental iron traffickers respond to maternal iron deficiency by increasing their expression and allowing sufficient iron to pass to the fetus.

Effects of high levels of zinc oxide and dietary zinc/copper ratios on the metabolism of iron in weaned pigs.

The present study compares the use different levels of dietary zinc oxide and zinc/copper ratios on the metabolism of iron (Fe) in weaned pigs. Two experiments were conducted using 120 and 160 weanling piglets (7.96 ± 1.17 kg and 7.81 ± 0.25 kg body weight, respectively) that were randomly assigned to the experimental treatments. Experiment I: diets supplemented with 100, 1,000, and 3,000 mg/kg of zinc (Zn) as ZnO (LZn, MZn, HZn) and 130 mg/kg of copper (Cu) as CuSO4; experiment II: diets supplemented with 100 or 3,000 mg/kg of Zn as ZnO (LZn and HZn) in combination with 6 or 130 mg/kg of Cu as CuSO4 (LCu and HCu). In both experiments, diets had similar levels of supplemental Fe (100 mg/kg of Fe as FeSO4). Piglets were slaughtered at d21 (weaning), d23 (experiment I), d28 (experiment II), d35, and d42 to assess whole blood, serum, and liver Fe concentrations, hemoglobin concentration, and the relative expression of key genes associated with Fe metabolism in jejunum and liver. Whole blood Fe and hemoglobin concentrations (experiment I) as well as serum Fe concentrations (experiments I and II) were not affected by dietary treatments (P ≥ 0.11). Liver Fe concentrations (experiment II) and total liver Fe content (experiments I and II) were lower (P ≤ 0.05) in HZn compared to LZn groups at d42. In both experiments, the mRNA expression of jejunal DMT1 was lowest and that of jejunal FTH1 was highest at d42 (P ≤ 0.04) for HZn piglets. In experiment II only, jejunal FTH1 and FPN1 expression were greater (P ≤ 0.04) in HCu compared to LCu groups at d42. The highest expression of hepatic FTH1 and FPN1 at d35 and d42 (P ≤ 0.02) was detected in HZn piglets in both experiments. For hepatic HAMP, expression values were greater (P = 0.04) at d42 in HZn groups. In conclusion, high dietary ZnO levels impair Fe metabolism but the effects are not intense enough to impact circulating Fe and hemoglobin concentrations.

Gut-on-a-chip for exploring the transport mechanism of Hg(II)

Animal models and static cultures of intestinal epithelial cells are commonly used platforms for exploring mercury ion (Hg(II)) transport. However, they cannot reliably simulate the human intestinal microenvironment and monitor cellular physiology in situ; thus, the mechanism of Hg(II) transport in the human intestine is still unclear. Here, a gut-on-a-chip integrated with transepithelial electrical resistance (TEER) sensors and electrochemical sensors is proposed for dynamically simulating the formation of the physical intestinal barrier and monitoring the transport and absorption of Hg(II) in situ. The cellular microenvironment was recreated by applying fluid shear stress (0.02 dyne/cm2) and cyclic mechanical strain (1%, 0.15 Hz). Hg(II) absorption and physical damage to cells were simultaneously monitored by electrochemical and TEER sensors when intestinal epithelial cells were exposed to different concentrations of Hg(II) mixed in culture medium. Hg(II) absorption increased by 23.59% when tensile strain increased from 1% to 5%, and the corresponding expression of Piezo1 and DMT1 on the cell surface was upregulated.

Iron cycle disruption by heme oxygenase-1 activation leads to a reduced breast cancer cell survival

Heme oxygenase-1 (HO-1), which catalyzes heme degradation releasing iron, regulates several processes related to breast cancer. Iron metabolism deregulation is also connected with several tumor processes. However the regulatory relationship between HO-1 and iron proteins in breast cancer remains unclear. Using human breast cancer biopsies, we found that high HO-1 levels significantly correlated with low DMT1 levels. Contrariwise, high HO-1 levels significantly correlated with high ZIP14 and prohepcidin expression, as well as hemosiderin storage. At mRNA level, we found that high HO-1 expression significantly correlated with low DMT1 expression but high ZIP14, L-ferritin and hepcidin expression. In in vivo experiments in mice with genetic overexpression or pharmacological activation of HO-1, we detected the same expression pattern observed in human biopsies. In in vitro experiments, HO-1 activation induced changes in iron proteins expression leading to an increase of hemosiderin, ROS levels, lipid peroxidation and a decrease of the growth rate. Such low growth rate induced by HO-1 activation was reversed when iron levels or ROS levels were reduced. Our findings demonstrate an important role of HO-1 on iron homeostasis in breast cancer. The changes in iron proteins expression when HO-1 is modulated led to the iron accumulation deregulating the iron cell cycle, and consequently, generating oxidative stress and low viability, all contributing to impair breast cancer progression.

The relation among myocardial iron load and the severity of heart failure

Abstract Heart failure (HF) symptoms are related to reduced circulatory perfusion, peripheral congestion, also impaired peripheral muscle strength &amp; oxygen utilization due to iron deficiency. Despite many premises, the correlation between myocardial iron load and failing heart function was not proved. The purpose of this study was to assess iron itself and iron-related proteins in human failing (FH) vs non-failing (NFH) myocardium. The study group consisted of 58 explanted FHs vs the control consisted of 31 NFHs unsuitable for transplantation. HF study group presented with LV dilatation (LVDD 67±8 mm; LVSD 59±13 mm), reduced contraction (LVEF 20±7.5%), RV enlargement (RVD 42±6.5 mm), pulmonary hypertension (2.21±0.93 Wu) and elevated NTproBNP (3955.5±2250.5pg/ml). We assessed iron serum markers: ferritin (FR), transferrin/saturation (TSAT), transferrin receptor (soluble sTfR), sTFR/log FR; myocardial iron homeostasis assessment: M-Iron (Instrumental Neutron Activation Analysis, μg/g) and iron gathering proteins (by ELISA): divalent metal transporter (DMT-1); L-type calcium channel (L-CH), TfR-1/TfR-2; ferritins: heavy (FT-H), light (FT-L) chain, mitochondrial (FT-MT); ferroportin (FPN) and oxidative stress marker: 4-hydroxynonenal (4-HNE). In FH vs NFH, M-Iron was reduced (164.6±25.2 vs 182.3±23.9; p=0.0358) however, did not apply to the entire group. Therefore we divvied the FH group into two subgroups (based on M-Iron concentration in NFH controls). Average iron concertation in non-iron-deficient (NIDM) subgroup was 172.5±19.1 (n=35) and in iron-deficient (IDM) subgroup wad 127.0±16.5; (n=23, p=0.0001). Regardless M-Iron load in FH vs NFH myocardial proteins expressions were reduced: L-CH (NIDM vs IDM vs NFH: 49.2±9.2; 42.5±4.2; 67.3±23.0, p=0.0022); FT-L (16.4±7.3; 11.6±4.8; 26.3±7.5, p= &amp;lt;0.0001, respectively); FT-MT (41.2±7.6; 38.7±4.1; 59.3±10.4 p≤0,0001, respectively). With regard to M-Iron load, only in DMT-1 expression was changed (NIDM vs IDM vs NFH 4.8±0.7; 4.0±0.5; 5.8±0.8; p≤0.0001). 4-HNE levels in FH vs NFH were increased, regardless M-Iron load (NIDM-Iron vs IDM-Iron vs NFH; 55.7±29.2; 57.2±47.8; 9.9±8.1 p≤0.0001). Interestingly, the iron load (NIDM-Iron vs IDM-Iron) did not modify the assessed clinical parameters. With regard to commonly used systemic iron markers only sTFR/log FR proved M-Iron load difference (NIDM-Iron vs IDM-Iron 0.6±0.2; 0.7±0.3; p=0.047910) In FH, we observed, the subgroup with the reduced M-Iron load. The observed reduction of iron gathering proteins were independent on M-Iron load, except DMT-1 the main iron transportation protein into the cell. The results showed that the HF degree and concertation of iron proteins are unlikely to be affected by the M-Iron load, except DMT-1 protein. The oxidative stress was also regardless from M-Iron load, and increased in the whole FH group. Commonly used systemic iron markers except sTFR/log FR did not define M-Iron load. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): The Cardinal Stefan Wyszyński National Institute of Cardiology

Ketogenic diet prevents chronic sleep deprivation-induced Alzheimer's disease by inhibiting iron dyshomeostasis and promoting repair via Sirt1/Nrf2 pathway.

Sleep deprivation (SD) is one of the main risk factors for Alzheimer’s disease (AD), but the underlying mechanism is still unclear. Ketogenic diet (KD) has been shown widely neuroprotective effects but less known about its effect on SD-induced AD. In the present study, a continuous 21 days SD mouse model with or without KD was established. The changes of cognitive function, pathological hallmarks of AD, ferroptosis, and intracellular signal pathways in mice were detected by Morris water maze, ThS staining, diaminobenzidine (DAB)-enhanced Perls’ stain, antioxidant assay, immuno-histochemistry, and western blot. The results showed that KD can prevent the cognitive deficiency, amyloid deposition and hyperphosphorylated tau induced by chronic SD. Analysis of ferroptosis revealed that KD can inhibit iron dyshomeostasis by down-regulating the expression of TfR1 and DMT1 and up-regulating the expression of FTH1, FPN1. Meanwhile, KD alleviated oxidative stress with elevated xCT/GPX4 axis, FSP1 and reduced MDA. In addition, KD could promote neuronal repair by enhancing BDNF and DCX. Further studies demonstrated that KD activated Sirt1/Nrf2 signaling pathway in the hippocampus in SD-exposed mice. Our finding firstly suggested that KD could prevent chronic SD-induced AD by inhibiting ferroptosis and improving the neuronal repair ability via Sirt1/Nrf2 signaling pathway.