RESUMEN
Anemia of inflammation (AI) is a highly prevalent comorbidity in patients affected by chronic inflammatory disorders, such as chronic kidney disease, inflammatory bowel disease, or cancer, that negatively affect disease outcome and quality of life. The pathophysiology of AI is multifactorial, with inflammatory hypoferremia and iron-restricted erythropoiesis playing a major role in the context of disease-specific factors. Here, we review the recent progress in our understanding of the molecular mechanisms contributing to iron dysregulation in AI, the impact of hypoferremia and anemia on the course of the underlying disease, and (novel) therapeutic strategies applied to treat AI.
Asunto(s)
Anemia , Hierro , Humanos , Hierro/uso terapéutico , Calidad de Vida , Anemia/terapia , Anemia/tratamiento farmacológico , Eritropoyesis/fisiología , Inflamación/terapia , Enfermedad CrónicaRESUMEN
The liver plays a crucial role in maintaining systemic iron homeostasis through iron storage, sensing of systemic iron needs, and production of the iron-regulatory hormone hepcidin. While mice are commonly used as models for studying human iron homeostasis, their liver structure differs significantly from humans. Since the mouse liver is structured in six separated lobes, often, the analysis of a single defined lobe is preferred due to concerns over data reproducibility between experimental cohorts. In this study, we compared iron-related parameters in distinct liver lobes of C57BL/6 wild-type mice across different ages. We found that the non-heme iron levels, as well as the mRNA and protein expression of iron storage protein Ferritin and the iron importer Transferrin Receptor 1, were similar between liver lobes. Additionally, the mRNA expression of Hepcidin, as well as its regulators, Bmp2 and Bmp6, and iron importers Zip8 and Zip14 were comparable. Minor differences were observed in Ferroportin mRNA levels of 24-wk-old mice; however, this did not correlate with altered iron content. The findings in wild-type mice were reproduced in Hfe knock-out mice - a well-established genetic model of the most prevalent form of hemochromatosis. Overall, our results indicate that C57BL/6 mouse liver lobes can be used interchangeably for assessing iron content and expression of iron-related genes. Understanding if these findings are applicable to other mouse developmental stages, strains, or models of (iron-related) disorders will be key to promote reduction of experimental animal numbers and facilitate resource sharing among research groups studying liver iron homeostasis.NEW & NOTEWORTHY This study reveals that, despite being structurally separated, liver lobes from C57BL/6 wild-type and iron-overloaded mice can be used interchangeably for the evaluation of iron content and expression of iron-related genes.
Asunto(s)
Hemocromatosis , Hepcidinas , Ratones , Humanos , Animales , Hepcidinas/genética , Hepcidinas/metabolismo , Proteína de la Hemocromatosis/genética , Proteína de la Hemocromatosis/metabolismo , Antígenos de Histocompatibilidad Clase I , Reproducibilidad de los Resultados , Ratones Endogámicos C57BL , Hígado/metabolismo , Hemocromatosis/metabolismo , Hierro/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratones Noqueados , HomeostasisRESUMEN
BACKGROUND AND AIMS: TGFß/bone morphogenetic protein (BMP) signaling in the liver plays a critical role in liver disease. Growth factors, such as BMP2, BMP6, and TGFß1, are released from LSECs and signal in a paracrine manner to hepatocytes and hepatic stellate cells to control systemic iron homeostasis and fibrotic processes, respectively. The misregulation of the TGFß/BMP pathway affects expression of the iron-regulated hormone hepcidin, causing frequent iron overload and deficiency diseases. However, whether LSEC-secreted factors can act in an autocrine manner to maintain liver homeostasis has not been addressed so far. APPROACH AND RESULTS: We analyzed publicly available RNA-sequencing data of mouse LSECs for ligand-receptor interactions and identified members of the TGFß family (BMP2, BMP6, and TGFß1) as ligands with the highest expression levels in LSECs that may signal in an autocrine manner. We next tested the soluble factors identified through in silico analysis in optimized murine LSEC primary cultures and mice. Exposure of murine LSEC primary cultures to these ligands shows that autocrine responses to BMP2 and BMP6 are blocked despite high expression levels of the required receptor complexes partially involving the inhibitor FK-506-binding protein 12. By contrast, LSECs respond efficiently to TGFß1 treatment, which causes reduced expression of BMP2 through activation of activin receptor-like kinase 5. CONCLUSIONS: These findings reveal that TGFß1 signaling is functionally interlinked with BMP signaling in LSECs, suggesting druggable targets for the treatment of iron overload diseases associated with deficiency of the BMP2-regulated hormone hepcidin, such as hereditary hemochromatosis, ß-thalassemia, and chronic liver diseases.
Asunto(s)
Proteína Morfogenética Ósea 2/metabolismo , Proteína Morfogenética Ósea 6/metabolismo , Hepcidinas/metabolismo , Hierro/metabolismo , Cirrosis Hepática , Transducción de Señal/fisiología , Factor de Crecimiento Transformador beta/metabolismo , Animales , Descubrimiento de Drogas , Células Endoteliales/metabolismo , Regulación de la Expresión Génica , Células Estrelladas Hepáticas , Hepatocitos/metabolismo , Homeostasis , Sobrecarga de Hierro/tratamiento farmacológico , Sobrecarga de Hierro/metabolismo , Cirrosis Hepática/metabolismo , Cirrosis Hepática/patología , RatonesRESUMEN
Anemia of cancer (AoC) with its multifactorial etiology and complex pathology is a poor prognostic indicator for cancer patients. One of the main causes of AoC is cancer-associated inflammation that activates mechanisms, commonly observed in anemia of inflammation, whereby functional iron deficiency and iron-restricted erythropoiesis are induced by increased hepcidin levels in response to raised levels of interleukin-6. So far only a few AoC mouse models have been described, and most of them did not fully recapitulate the interplay of anemia, increased hepcidin levels and functional iron deficiency in human patients. To test if the selection and the complexity of AoC mouse models dictates the pathology or if AoC in mice per se develops independently of iron deficiency, we characterized AoC in Trp53floxWapCre mice that spontaneously develop breast cancer. These mice developed AoC associated with high levels of interleukin-6 and iron deficiency. However, hepcidin levels were not increased and hypoferremia coincided with anemia rather than causing it. Instead, an early shift in the commitment of common myeloid progenitors from the erythroid to the myeloid lineage resulted in increased myelopoiesis and in the excessive production of neutrophils that accumulate in necrotic tumor regions. This process could not be prevented by either iron or erythropoietin treatment. Trp53floxWapCre mice are the first mouse model in which erythropoietin-resistant anemia is described and may serve as a disease model to test therapeutic approaches for a subpopulation of human cancer patients with normal or corrected iron levels who do not respond to erythropoietin.
Asunto(s)
Anemia , Neoplasias de la Mama , Eritropoyetina , Deficiencias de Hierro , Anemia/tratamiento farmacológico , Anemia/etiología , Anemia/patología , Animales , Neoplasias de la Mama/complicaciones , Eritropoyesis , Eritropoyetina/farmacología , Eritropoyetina/uso terapéutico , Femenino , Hepcidinas/genética , Humanos , Inflamación/complicaciones , Interleucina-6/genética , Hierro/uso terapéutico , RatonesRESUMEN
Throughout life, macrophages are located in every tissue of the body, where their main roles are to phagocytose cellular debris and recycle aging red blood cells. In the tissue niche, they promote homeostasis through trophic, regulatory, and repair functions by responding to internal and external stimuli. This in turn polarizes macrophages into a broad spectrum of functional activation states, also reflected in their iron-regulated gene profile. The fast adaptation to the environment in which they are located helps to maintain tissue homeostasis under physiological conditions.
Asunto(s)
Hierro/inmunología , Activación de Macrófagos , Macrófagos/inmunología , Animales , Homeostasis , Humanos , Inflamación/inmunología , Inflamación/metabolismo , Hierro/metabolismo , Macrófagos/metabolismo , FagocitosisRESUMEN
BACKGROUND: While the deregulation of iron homeostasis in breast epithelial cells is acknowledged, iron-related alterations in stromal inflammatory cells from the tumor microenvironment have not been explored. METHODS: Immunohistochemistry for hepcidin, ferroportin 1 (FPN1), transferrin receptor 1 (TFR1) and ferritin (FT) was performed in primary breast tissues and axillary lymph nodes in order to dissect the iron-profiles of epithelial cells, lymphocytes and macrophages. Furthermore, breast carcinoma core biopsies frozen in optimum cutting temperature (OCT) compound were subjected to imaging flow cytometry to confirm FPN1 expression in the cell types previously evaluated and determine its cellular localization. RESULTS: We confirm previous results by showing that breast cancer epithelial cells present an 'iron-utilization phenotype' with an increased expression of hepcidin and TFR1, and decreased expression of FT. On the other hand, lymphocytes and macrophages infiltrating primary tumors and from metastized lymph nodes display an 'iron-donor' phenotype, with increased expression of FPN1 and FT, concomitant with an activation profile reflected by a higher expression of TFR1 and hepcidin. A higher percentage of breast carcinomas, compared to control mastectomy samples, present iron accumulation in stromal inflammatory cells, suggesting that these cells may constitute an effective tissue iron reservoir. Additionally, not only the deregulated expression of iron-related proteins in epithelial cells, but also on lymphocytes and macrophages, are associated with clinicopathological markers of breast cancer poor prognosis, such as negative hormone receptor status and tumor size. CONCLUSIONS: The present results reinforce the importance of analyzing the tumor microenvironment in breast cancer, extending the contribution of immune cells to local iron homeostasis in the tumor microenvironment context.
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Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Carcinoma Ductal de Mama/metabolismo , Carcinoma Ductal de Mama/patología , Homeostasis , Hierro/metabolismo , Microambiente Tumoral , Antígenos CD/genética , Antígenos CD/metabolismo , Biomarcadores , Neoplasias de la Mama/genética , Carcinoma Ductal de Mama/genética , Proteínas de Transporte de Catión/genética , Proteínas de Transporte de Catión/metabolismo , Femenino , Citometría de Flujo , Expresión Génica , Hepcidinas/genética , Hepcidinas/metabolismo , Humanos , Inmunohistoquímica , Ganglios Linfáticos/metabolismo , Ganglios Linfáticos/patología , Receptores de Transferrina/genética , Receptores de Transferrina/metabolismo , Carga TumoralRESUMEN
ALK-positive NSCLC patients demonstrate initial responses to ALK tyrosine kinase inhibitor (TKI) treatments, but eventually develop resistance, causing rapid tumor relapse and poor survival rates. Growing evidence suggests that the combination of drug and immune therapies greatly improves patient survival; however, due to the low immunogenicity of the tumors, ALK-positive patients do not respond to currently available immunotherapies. Tumor-associated macrophages (TAMs) play a crucial role in facilitating lung cancer growth by suppressing tumoricidal immune activation and absorbing chemotherapeutics. However, they can also be programmed toward a pro-inflammatory tumor suppressive phenotype, which represents a highly active area of therapy development. Iron loading of TAMs can achieve such reprogramming correlating with an improved prognosis in lung cancer patients. We previously showed that superparamagnetic iron oxide nanoparticles containing core-cross-linked polymer micelles (SPION-CCPMs) target macrophages and stimulate pro-inflammatory activation. Here, we show that SPION-CCPMs stimulate TAMs to secrete reactive nitrogen species and cytokines that exert tumoricidal activity. We further show that SPION-CCPMs reshape the immunosuppressive Eml4-Alk lung tumor microenvironment (TME) toward a cytotoxic profile hallmarked by the recruitment of CD8+ T cells, suggesting a multifactorial benefit of SPION-CCPM application. When intratracheally instilled into lung cancer-bearing mice, SPION-CCPMs delay tumor growth and, after first line therapy with a TKI, halt the regrowth of relapsing tumors. These findings identify SPIONs-CCPMs as an adjuvant therapy, which remodels the TME, resulting in a delay in the appearance of resistant tumors.
Asunto(s)
Crizotinib , Neoplasias Pulmonares , Nanopartículas Magnéticas de Óxido de Hierro , Microambiente Tumoral , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/patología , Microambiente Tumoral/efectos de los fármacos , Animales , Nanopartículas Magnéticas de Óxido de Hierro/química , Humanos , Ratones , Crizotinib/farmacología , Crizotinib/química , Antineoplásicos/farmacología , Antineoplásicos/química , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/química , Línea Celular Tumoral , Macrófagos Asociados a Tumores/efectos de los fármacos , Macrófagos Asociados a Tumores/metabolismo , Proliferación Celular/efectos de los fármacos , FemeninoRESUMEN
OBJECTIVE: Hyperferremia and hyperferritinemia are observed in patients and disease models of type 2 diabetes mellitus (T2DM). Likewise, patients with genetic iron overload diseases develop diabetes, suggesting a tight link between iron metabolism and diabetes. The liver controls systemic iron homeostasis and is a central organ for T2DM. Here, we investigate how the control of iron metabolism in hepatocytes is affected by T2DM. METHODS: Perls Prussian blue staining was applied to analyze iron distribution in liver biopsies of T2DM patients. To identify molecular mechanisms underlying hepatocyte iron accumulation we established cellular models of insulin resistance by treatment with palmitate and insulin. RESULTS: We show that a subset of T2DM patients accumulates iron in hepatocytes, a finding mirrored in a hepatocyte model of insulin resistance. Iron accumulation can be explained by the repression of the iron exporter ferroportin upon palmitate and/or insulin treatment. While during palmitate treatment the activation of the iron regulatory hormone hepcidin may contribute to reducing ferroportin protein levels in a cell-autonomous manner, insulin treatment decreases ferroportin transcription via the PI3K/AKT and Ras/Raf/MEK/ERK signaling pathways. CONCLUSION: Repression of ferroportin at the transcriptional and post-transcriptional level may contribute to iron accumulation in hepatocytes observed in a subset of patients with T2DM.
Asunto(s)
Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Insulinas , Sobrecarga de Hierro , Humanos , Hierro/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Sobrecarga de Hierro/metabolismo , Hepatocitos/metabolismo , Palmitatos/metabolismo , Insulinas/metabolismoRESUMEN
Twenty years ago the discovery of hepcidin deeply changed our understanding of the regulation of systemic iron homeostasis. It is now clear that hepcidin orchestrates systemic iron levels by controlling the amount of iron exported into the bloodstream through ferroportin. Hepcidin expression is increased in situations where systemic iron levels should be reduced, such as in iron overload and infection. Conversely, hepcidin is repressed during iron deficiency, hypoxia or expanded erythropoiesis, to increase systemic iron availability and sustain erythropoiesis. In this review, we will focus on molecular mechanisms of hepcidin regulation and on the pathological consequences of their disruption.
Asunto(s)
Hepcidinas , Sobrecarga de Hierro , Eritropoyesis , Hepcidinas/metabolismo , Homeostasis , Humanos , Hierro/metabolismo , Sobrecarga de Hierro/metabolismoRESUMEN
BACKGROUND: Iron export via the transport protein ferroportin (Fpn) plays a critical role in the regulation of dietary iron absorption and iron recycling in macrophages. Fpn plasma membrane expression is controlled by the hepatic iron-regulated hormone hepcidin in response to high iron availability and inflammation. Hepcidin binds to the central cavity of the Fpn transporter to block iron export either directly or by inducing Fpn internalization and lysosomal degradation. Here, we investigated whether iron deficiency affects Fpn protein turnover. METHODS: We ectopically expressed Fpn in HeLa cells and used cycloheximide chase experiments to study basal and hepcidin-induced Fpn degradation under extracellular and intracellular iron deficiency. CONCLUSIONS/GENERAL SIGNIFICANCE: We show that iron deficiency does not affect basal Fpn turnover but causes a significant delay in hepcidin-induced degradation when cytosolic iron levels are low. These data have important mechanistic implications supporting the hypothesis that iron export is required for efficient targeting of Fpn by hepcidin. Additionally, we show that Fpn degradation is not involved in protecting cells from intracellular iron deficiency.
Asunto(s)
Proteínas de Transporte de Catión/genética , Hepcidinas/genética , Deficiencias de Hierro , Proteínas de Transporte de Catión/metabolismo , Cicloheximida/farmacología , Deferoxamina/farmacología , Regulación de la Expresión Génica , Células HeLa , Hepcidinas/metabolismo , Humanos , Transporte Iónico/efectos de los fármacos , Quelantes del Hierro/farmacología , Unión Proteica/efectos de los fármacos , Inhibidores de la Síntesis de la Proteína/farmacología , Transporte de Proteínas/efectos de los fármacos , Proteolisis/efectos de los fármacos , Transducción de SeñalRESUMEN
Iron is an essential co-factor for cellular processes. In the immune system, it can activate macrophages and represents a potential therapeutic for various diseases. To specifically deliver iron to macrophages, iron oxide nanoparticles are embedded in polymeric micelles of reactive polysarcosine-block-poly(S-ethylsulfonyl-l-cysteine). Upon surface functionalization via dihydrolipoic acid, iron oxide cores act as crosslinker themselves and undergo chemoselective disulfide bond formation with the surrounding poly(S-ethylsulfonyl-l-cysteine) block, yielding glutathione-responsive core cross-linked polymeric micelles (CCPMs). When applied to primary murine and human macrophages, these nanoparticles display preferential uptake, sustained intracellular iron release, and induce a strong inflammatory response. This response is also demonstrated in vivo when nanoparticles are intratracheally administered to wild-type C57Bl/6N mice. Most importantly, the controlled release concept to deliver iron oxide in redox-responsive CCPMs induces significantly stronger macrophage activation than any other iron source at identical iron levels (e.g., Feraheme), directing to a new class of immune therapeutics.
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Hierro , Micelas , Animales , Inflamación/tratamiento farmacológico , Macrófagos , Ratones , PolímerosRESUMEN
The respiratory tract is constantly exposed to pathogens that require iron for proliferation and virulence. Pulmonary iron levels are increased in several lung diseases and associated with increased susceptibility to infections. However, regulation of lung iron homeostasis and its cross talk to pulmonary immune responses are largely unexplored. Here we investigated how increased lung iron levels affect the early pulmonary inflammatory response. We induced acute local pulmonary inflammation via aerosolized LPS in a mouse model of hereditary hemochromatosis type 4 (Slc40a1 C326S/C326S), which is hallmarked by systemic and pulmonary iron accumulation, specifically in alveolar macrophages. We show that Slc40a1 C326S/C326S mice display a mild attenuation in the LPS-induced pulmonary inflammatory response, with a reduced upregulation of some pro-inflammatory cytokines and chemokines. Despite mildly reduced cytokine levels, there is no short-term impairment in the recruitment of neutrophils into the bronchoalveolar space. These data suggest that increased pulmonary iron levels do not strongly alter the acute inflammatory response of the lung.
RESUMEN
Iron is an essential micronutrient and a critical cofactor for proteins involved in fundamental processes such as oxygen transport, energy production and DNA synthesis. However, iron levels need to be tightly balanced to avoid pathological consequences of iron overload or deficiency. Genetically engineered mouse models with alterations in systemic or cellular iron handling advanced our knowledge how systemic and cellular iron homeostasis is maintained. Here, we prepared a comprehensive overview of mouse models that provide insight into mechanisms of iron regulation and/or rare or frequent iron-related disorders.
Asunto(s)
Homeostasis , Animales , Modelos Animales de Enfermedad , Humanos , Hierro , RatonesRESUMEN
Macrophages release iron into the bloodstream via a membrane-bound iron export protein, ferroportin (FPN). The hepatic iron-regulatory hormone hepcidin controls FPN internalization and degradation in response to bacterial infection. Salmonella typhimurium can invade macrophages and proliferate in the Salmonella-containing vacuole (SCV). Hepcidin is reported to increase the mortality of Salmonella-infected animals by increasing the bacterial load in macrophages. Here we assess the iron levels and find that hepcidin increases iron content in the cytosol but decreases it in the SCV through FPN on the SCV membrane. Loss-of-FPN from the SCV via the action of hepcidin impairs the generation of bactericidal reactive oxygen species (ROS) as the iron content decreases. We conclude that FPN is required to provide sufficient iron to the SCV, where iron serves as a cofactor for the generation of antimicrobial ROS rather than as a nutrient for Salmonella.
Asunto(s)
Proteínas de Transporte de Catión/metabolismo , Hepcidinas/metabolismo , Hierro/metabolismo , Macrófagos/inmunología , Salmonella typhimurium/metabolismo , Vacuolas/microbiología , Animales , Carga Bacteriana , Línea Celular , Femenino , Células HeLa , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Células RAW 264.7 , Especies Reactivas de Oxígeno/metabolismo , Receptores de Estrógenos/antagonistas & inhibidores , Infecciones por Salmonella/tratamiento farmacológico , Tamoxifeno/análogos & derivados , Tamoxifeno/farmacologíaRESUMEN
Breast cancer epithelial cells with the CD44+/CD24-/low phenotype possess tumor-initiating cells and epithelial-mesenchymal transition (EMT) capacity. Massive parallel sequencing can be an interesting approach to deepen the molecular characterization of these cells. We characterized CD44+/CD24-/cytokeratin(Ck)+/CD45- cells isolated through flow cytometry from 43 biopsy and 6 mastectomy samples harboring different benign and malignant breast lesions. The Ion Torrent Ampliseq Cancer Hotspot panel v2 (CHPv2) was used for the identification of somatic mutations in the DNA extracted from isolated CD44+/CD24-/Ck+/CD45- cells. E-Cadherin and vimentin immunohistochemistry was performed on sections from the corresponding formalin-fixed, paraffin-embedded (FFPE) blocks. The percentage of CD44+/CD24-/Ck+/CD45- cells increased significantly from non-malignant to malignant lesions and in association with a significant increase in the expression of vimentin. Non-malignant lesions harbored only a single-nucleotide polymorphism (SNP). Mutations in the tumor suppressor p53 (TP53), NOTCH homolog 1 (NOTCH1), phosphatase and tensin homolog (PTEN), and v-akt murine thymoma viral oncogene homolog 1 (AKT1) genes were found in isolated CD44+/CD24-/Ck+/CD45- cells from ductal carcinomas in situ (DCIS). Additional mutations in the colony-stimulating factor 1 receptor (CSF1R), ret proto-oncogene (RET), and TP53 genes were also identified in invasive ductal carcinomas (IDCs). The use of massive parallel sequencing technology for this type of application revealed to be extremely effective even when using small amounts of DNA extracted from a low number of cells. Additional studies are now required using larger cohorts to design an appropriate mutational profile for this phenotype.