Tumor necrosis factor alpha-mediated inhibition of erythropoiesis involves GATA-1/GATA-2 balance impairment and PU.1 over-expression

A Review of Key Regulators of Steady-State and Ineffective Erythropoiesis

Erythropoiesis is initiated with the transformation of multipotent hematopoietic stem cells into committed erythroid progenitor cells in the erythroblastic islands of the bone marrow in adults. These cells undergo several stages of differentiation, including erythroblast formation, normoblast formation, and finally, the expulsion of the nucleus to form mature red blood cells. The erythropoietin (EPO) pathway, which is activated by hypoxia, induces stimulation of the erythroid progenitor cells and the promotion of their proliferation and survival as well as maturation and hemoglobin synthesis. The regulation of erythropoiesis is a complex and dynamic interaction of a myriad of factors, such as transcription factors (GATA-1, STAT5), cytokines (IL-3, IL-6, IL-11), iron metabolism and cell cycle regulators. Multiple microRNAs are involved in erythropoiesis, mediating cell growth and development, regulating oxidative stress, erythrocyte maturation and differentiation, hemoglobin synthesis, transferrin function and iron homeostasis. This review aims to explore the physiology of steady-state erythropoiesis and to outline key mechanisms involved in ineffective erythropoiesis linked to anemia, chronic inflammation, stress, and hematological malignancies. Studying aberrations in erythropoiesis in various diseases allows a more in-depth understanding of the heterogeneity within erythroid populations and the development of gene therapies to treat hematological disorders.

Defining a cohort of anemia-activated cis elements reveals a mechanism promoting erythroid precursor function

Acute anemia elicits broad transcriptional changes in erythroid progenitors and precursors. We previously discovered a cis-regulatory transcriptional enhancer at the sterile alpha motif domain-14 enhancer locus (S14E), defined by a CANNTG-spacer-AGATAA composite motif and occupied by GATA1 and TAL1 transcription factors, is required for survival in severe anemia. However, S14E is only 1 of dozens of anemia-activated genes containing similar motifs. In a mouse model of acute anemia, we identified populations of expanding erythroid precursors, which increased expression of genes that contain S14E-like cis elements. We reveal that several S14E-like cis elements provide important transcriptional control of newly identified anemia-inducing genes, including the Ssx-2 interacting protein (Ssx2ip). Ssx2ip expression was determined to play an important role in erythroid progenitor/precursor cell activities, cell cycle regulation, and cell proliferation. Over a weeklong course of acute anemia recovery, we observed that erythroid gene activation mediated by S14E-like cis elements occurs during a phase coincident with low hematocrit and high progenitor activities, with distinct transcriptional programs activated at earlier and later time points. Our results define a genome-wide mechanism in which S14E-like enhancers control transcriptional responses during erythroid regeneration. These findings provide a framework to understand anemia-specific transcriptional mechanisms, ineffective erythropoiesis, anemia recovery, and phenotypic variability within human populations.

Regulatory Effect and Mechanism of Erythroblastic Island Macrophages on Anemia in Patients with Newly Diagnosed Multiple Myeloma

Objective

To examine the clinical characteristics and anemia-related factors in patients with newly diagnosed multiple myeloma (NDMM), as well as the effect and mechanism of erythroblastic islands (EBIs) and EBI macrophages in NDMM patients with anemia.

Methods

We collected and analyzed clinical data to find anemia-related factors. Using flow cytometry, the numbers and ratios of erythroblasts and EBI macrophages were determined. RNA sequencing (RNA-seq) was used to determine the differences of EBI macrophages in NDMM patients with or without anemia.

Results

Based on the clinical characteristics of NDMM patients with anemia, MCV, abnormal levels of albumin, osteolytic lesions, and Durie-Salmon (DS) stage are risk factors for anemia. Patients with anemia have fewer erythroblasts, erythroblastic islands (EBIs), and EBI macrophages in their bone marrow than patients without anemia. RNA-seq analysis of EBI macrophages from the bone marrow of patients with and without anemia revealed that macrophages from patients with anemia are impaired and tend to promote the production of interleukin-6, which has been demonstrated to be an essential survival factor of myeloma cells and protects them from apoptosis.

Conclusion

In NDMM patients with anemia, EBI macrophages are impaired, which causes anemia in those patients. Our finding highlights the significance of EBI macrophages in anemia in NDMM patients and provides a new strategy for recovery from anemia in these patients.

Hepcidin and its multiple partners: Complex regulation of iron metabolism in health and disease

The peptide hormone hepcidin is central to the regulation of iron metabolism, influencing the movement of iron into the circulation and determining total body iron stores. Its effect on a cellular level involves binding ferroportin, the main iron export protein, preventing iron egress and leading to iron sequestration within ferroportin-expressing cells. Hepcidin expression is enhanced by iron loading and inflammation and suppressed by erythropoietic stimulation. Aberrantly increased hepcidin leads to systemic iron deficiency and/or iron restricted erythropoiesis as occurs in anemia of chronic inflammation. Furthermore, insufficiently elevated hepcidin occurs in multiple diseases associated with iron overload such as hereditary hemochromatosis and iron loading anemias. Abnormal iron metabolism as a consequence of hepcidin dysregulation is an underlying factor resulting in pathophysiology of multiple diseases and several agents aimed at manipulating this pathway have been designed, with some already in clinical trials. In this chapter, we assess the complex regulation of hepcidin, delineate the many binding partners involved in its regulation, and present an update on the development of hepcidin agonists and antagonists in various clinical scenarios.

Targeting iron metabolism in osteosarcoma

Osteosarcoma (OS) is the most common primary solid malignant tumour of bone, with rapid progression and a very poor prognosis. Iron is an essential nutrient that makes it an important player in cellular activities due to its inherent ability to exchange electrons, and its metabolic abnormalities are associated with a variety of diseases. The body tightly regulates iron content at the systemic and cellular levels through various mechanisms to prevent iron deficiency and overload from damaging the body. OS cells regulate various mechanisms to increase the intracellular iron concentration to accelerate proliferation, and some studies have revealed the hidden link between iron metabolism and the occurrence and development of OS. This article briefly describes the process of normal iron metabolism, and focuses on the research progress of abnormal iron metabolism in OS from the systemic and cellular levels.

Deciphering the Efficacy and Mechanism of Astragalus membranaceus on High Altitude Polycythemia by Integrating Network Pharmacology and In Vivo Experiments

Hypoxic exposure makes plateau migrators susceptible to high altitude polycythemia (HAPC). Astragalus membranaceus (AM) is an edible and medicinal plant with remarkable immunomodulatory activities. The purpose of this study was to discover if AM could be a candidate for the prevention of HAPC and its mechanism. Here, network pharmacology was applied to screen active compounds, key targets, and enriched pathways of AM in the treatment of HAPC. Molecular docking evaluated the affinity between compounds and core targets. Subsequently, the mechanisms of AM were further verified using the hypoxia exposure-induced mice model of HAPC. The network pharmacology analysis and molecular docking results identified 14 core targets of AM on HAPC, which were predominantly mainly enriched in the HIF-1 pathway. In the HAPC animal models, we found that AM inhibited the differentiation of hematopoietic stem cells into the erythroid lineage. It also suppressed the production of erythrocytes and hemoglobin in peripheral blood by reducing the expression of HIF-1α, EPO, VEGFA, and Gata-1 mRNA. Furthermore, AM downregulated the expression of IL-6, TNF-α, and IFN-γ mRNA, thereby alleviating organ inflammation. In conclusion, AM supplementation alleviates hypoxia-induced HAPC in mice, and TNF-α, AKT1, HIF-1α, VEGFA, IL-6, and IL-1B may be the key targets.

Evolution of severe (transfusion-dependent) anaemia in myelodysplastic syndromes with 5q deletion is characterized by a macrophage-associated failure of the eythropoietic niche

Evolution of erythrocyte transfusion-dependent (RBC-TD) anaemia associated with haploinsufficiency of the ribosomal protein subunit S14 gene (RPS14) is a characteristic complication of myelodysplastic syndromes (MDS) with del(5q) [MDS.del(5q)]. Evaluating 39 patients with MDS.del(5q), <5% of anaemia progression was attributable to RPS14-dependent alterations of normoblasts, pro-erythroblasts, or CD34⁺ CD71⁺ precursors. Ninety-three percent of anaemia progression and 70% of the absolute decline in peripheral blood Hb value were attributable to disappearance of erythroblastic islands (Ery-Is). Ery-Is loss occurred independently of blast excess, TP53 mutation, additional chromosome aberrations and RPS14-dependent alterations of normoblasts and pro-erythroblasts. It was associated with RPS14-dependent intrinsic (S100A8⁺ ) and extrinsic [tumour necrosis factor α (TNF-α)-overproduction] alterations of (CD169⁺ ) marrow macrophages (p < 0.00005). In a mouse model of RPS14 haploinsufficiency, Ery-Is disappeared to a similar degree: approximately 70% of Ery-Is loss was related to RPS14-dependent S100A8 overexpression of marrow macrophages, less than 20% to that of CD71^high Ter119^- immature precursors, and less than 5% to S100A8/p53 overexpression of normoblasts or pro-erythroblasts. Marked Ery-Is loss predicted reduced efficacy (erythrocyte transfusion independence) of lenalidomide therapy (p = 0.0006). Thus, erythroid hypoplasia, a characteristic complication of MDS.del(5q), seems to result primarily from a macrophage-associated failure of the erythropoietic niche markedly reducing the productive capacity of erythropoiesis as the leading factor in anaemia progression and evolution of RBC-TD in MDS.del(5q).

The role of SPI1-TYROBP-FCER1G network in oncogenesis and prognosis of osteosarcoma, and its association with immune infiltration

Osteosarcoma is an aggressive malignant bone sarcoma worldwide. A causal gene network with specific functions underlying both the development and progression of OS was still unclear. Here we firstly identified the differentially expressed genes (DEGs) between control and OS samples, and then defined the hub genes and top clusters in the protein–protein interaction (PPI) network of these DEGs. By focusing on the hub gene TYROBP in the top 1 cluster, a conserved TYROBP co-expression network was identified. Then the effect of the network on OS overall survival was analyzed. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses and Gene Set Enrichment Analysis (GSEA) were used to explore the functions of the network. XCell platform and ssGSEA algorithm were conducted to estimate the status of immune infiltration. ChEA3 platform, GSEA enrichment analysis, and Drug Pair Seeker (DPS) were used to predict the key transcription factor and its upstream signal. We identified the downregulated SPI1-TYROBP-FCER1G network in OS, which were significantly enriched in immune-related functions. We also defined a two-gene signature (SPI1/FCER1G) that can predict poorer OS overall survival and the attenuated immune infiltration when downregulated. The SPI1-TYROBP-FCER1G network were potentially initiated by transcription factor SPI1 and would lead to the upregulated CD86, MHC-II, CCL4/CXCL10/CX3CL1 and hence increased immune infiltrations. With this study, we could better explore the mechanism of OS oncogenesis and metastasis for developing new therapies.

Association Between Blood PLT and RBC Related Indices and Disease Activity in Patients with Rheumatoid Arthritis

Background

Platelet (PLT) and red blood cell (RBC) have been demonstrated to play a critical role in inflammatory processes. This study aimed to evaluate the association of blood PLT and RBC related parameters with the disease activity in rheumatoid arthritis (RA) patients, and also to investigate the role of these indices in differentiating among RA patients with different disease activity.

Methods

Clinical data from RA patients were retrospectively analyzed. RA patients were divided into inactive group and active group according to DAS28-CRP. The relationship between blood PLT and RBC counts-related indices and DAS28-CRP was detected by Spearman correlation. ROC curve was used to assess the diagnostic value of these indices in differentiating active RA from inactive RA.

Results

Active RA patients exhibited higher level of PLT counts but significantly lower levels of RBC counts, hemoglobin (Hb), red blood cells-platelet ratio (RPR) and hemoglobin-platelet ratio (HPR) compared with inactive RA. PLT counts were positively but RBC counts, Hb, RPR and HPR were negatively related with DAS28-CRP.

Conclusion

Blood PLT and RBC related indices were significantly associated with RA disease activity. These indices may be used to distinguish active RA from inactive RA.

The Association between Pretreatment anemia and Overall Survival in Advanced Non-small Cell lung Cancer: A Retrospective Cohort Study Using Propensity Score Matching

Background: The purpose of this study was to investigate whether pretreatment anemia was an independent risk factor for survival in patients with advanced non-small cell lung cancer (NSCLC) after adjusting for other covariates. Methods: We used propensity score matching (PSM) to minimize the influence of confounding factors and used χ2 (categorical variables), Student's t-test (normal distribution), or Mann-Whitney U test (skewed distribution) to analyze the differences among the Hb groups. Cox regression and Kaplan-Meier analyses were used to assess the association between anemia and survival. P values < 0.05 (two-sided) were considered statistically significant. Results: The average age of the 758 selected participants was 58.2±11 years, and 210 patients (27.7%) had anemia. In the multivariate analysis, anemia was associated with a poor prognosis in the unmatched cohort (Hazards ratio (HR)=1.3, 95% (confidence interval (CI): 1.1-1.6; p= 0.008), and the matched cohort (HR=1.7, 95% CI: 1.3-2.3; p <0.001), emerging as an independent risk and prognostic factor in advanced NSCLC patients. In the Kaplan-Meier curve, the average survival time of anemic and non-anemic patients was 9.3 months (95% CI: 7.9-11.4 months) vs. 14.1 months (95% CI: 12-16.3 months) (p=0.0073) in the unmatched cohort. After propensity score matching, the average survival time of anemic and non-anemic patients was 10.9 months (95% CI: 8.8-12.9. months) vs. 17.8 months (95% CI: 16.0-23.3 months) (p <0.001). Conclusion: Pretreatment anemia was an independent risk and prognostic factor for survival in patients with advanced NSCLC. Large-scale studies are required to confirm our findings.

The role of lymphocyte-monocyte ratio on axial spondyloarthritis diagnosis and sacroiliitis staging

Background

Axial spondyloarthritis (axial SpA) is a chronic inflammatory disorder could lead to disability due to the failure of timely treatment. The role of lymphocyte-to-monocyte ratio (LMR) in axial SpA remains unclear. The aim of this study was to investigate the role of LMR in axial SpA diagnosis, disease activity classification and sacroiliitis staging.

Methods

Seventy-eight axial SpA patients [51males and 27 females; mean age 41.0 (29–52) years] and 78 healthy controls (HCs) [55males and 23 females; mean age 40 (30–53) years] were enrolled in this study. The diagnosis of axial SpA was performed according to the New York criteria or the Assessment of Spondyloarthritis international Society (ASAS) classification criteria, whereas the staging of sacroiliitis in axial SpA patients was determined by X-ray examination. Comparisons of LMR levels between groups were performed using t test. Pearson or Spearman correlation analysis were used to assess correlations between LMR and other indicators. Receiver operating characteristic (ROC) curves were used to determine the role of LMR in the diagnosis of axial SpA.

Results

Higher neutrophil-to-lymphocyte ratio(NLR), red blood cell distribution width(RDW), platelet-to-lymphocyte ratio(PLR), mean platelet volume(MPV), erythrocyte sedimentation rate (ESR), and C-reactive protein(CRP) levels and lower red blood cell (RBC), hemoglobin (Hb), Hematocrit (Hct), LMR, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL) and albumin/globulin (A/G) levels were noted in axial SpA patients compared to HCs. Positive correlations were observed between LMR and RBC, Hb, Hct and A/G, whereas negative correlations were found between LMR and NLR, PLR, AST, and TBIL (P < 0.05). ROC curves showed that the area under the curve (AUC) for LMR in the diagnosis of ankylosing spondylitis was 0.803 (95% CI = 0.734–0.872) with a sensitivity and specificity of 62.8 and 87.2%, respectively, and the AUC (95% CI) for the combination of ESR, CRP and LMR was 0.975 (0.948–1.000) with a sensitivity and specificity of 94.9 and 97.4%, respectively. LMR levels were lower (P < 0.05) and significant differences in LMR values were observed among different stages (P < 0.05).

Conclusions

Our study suggested that LMR might be an important inflammatory marker to identify axial SpA and assess disease activity and X-ray stage of sacroiliitis.

Chronic lymphocytic leukemia B-cell-derived TNFα impairs bone marrow myelopoiesis

TNFα is implicated in chronic lymphocytic leukemia (CLL) immunosuppression and disease progression. TNFα is constitutively produced by CLL B cells and is a negative regulator of bone marrow (BM) myelopoiesis. Here, we show that co-culture of CLL B cells with purified normal human hematopoietic stem and progenitor cells (HSPCs) directly altered protein levels of the myeloid and erythroid cell fate determinants PU.1 and GATA-2 at the single-cell level within transitional HSPC subsets, mimicking ex vivo expression patterns. Physical separation of CLL cells from control HSPCs or neutralizing TNFα abrogated upregulation of PU.1, yet restoration of GATA-2 required TNFα neutralization, suggesting both cell contact and soluble-factor-mediated regulation. We further show that CLL patient BM myeloid progenitors are diminished in frequency and function, an effect recapitulated by chronic exposure of control HSPCs to low-dose TNFα. These findings implicate CLL B-cell-derived TNFα in impaired BM myelopoiesis.

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CLL patient BM HSPCs exhibit aberrant molecular and functional characteristics

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CLL B-cell-derived TNFα upregulates PU.1 and GATA-2 in BM HSPCs

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The effects of CLL B-cell-derived TNFα are reversible upon TNFα neutralization

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Chronic TNFα exposure in vitro recapitulates ex vivo HSPC functional deficiencies

Plasma TNFα and Unknown Factor/s Potentially Impede Erythroblast Enucleation Obstructing Terminal Maturation of Red Blood Cells in Burn Patients

INTRODUCTION

In this study, using burn patient's peripheral blood mononuclear cells (PBMCs), we have shown that the Epo independent stage of terminal enucleation to reticulocyte formation is impeded in the presence of autologous plasma (BP). Furthermore, substitution with allogeneic control plasma (CP) from the healthy individual in place of BP rectified this enucleation defect. The exclusive role of burn microenvironment in late-stage erythropoiesis defect was further demarcated through control healthy human bone marrow cells cultured in the presence of CP, BP, and cytokines.

METHODS

PBMCs and human bone marrow (huBM) were differentiated ex vivo to enucleated reticulocytes in the presence of required growth factors and 5% CP or BP. Effect of systemic mediators in burn microenvironment like IL-6, IL-15, and TNFα was also explored. Neutralization experiments were carried out by adding varying concentrations (25 ng-400 ng/mL) of Anti-TNFα Ab to either CP+TNFα or BP.

RESULTS

Reticulocyte proportion and maturation index were significantly improved upon substituting BP with CP during differentiation of burn PBMCs. In the huBM ex vivo culture, addition of IL-6 and IL-15 to CP inhibited the proliferation stages of erythropoiesis, whereas TNFα supplementation caused maximum diminution at erythroblast enucleation stage. Supplementation with anti-TNFα in the BP showed significant but partial restoration in the enucleation process, revealing the possibility of other crucial microenvironmental factors that could impact RBC production in burn patients.

CONCLUSION

Exogenous TNFα impairs late-stage erythropoiesis by blocking enucleation, but neutralization of TNFα in BP only partially restored terminal enucleation indicating additional plasma factor(s) impair(s) late-stage RBC maturation in burn patients.

Role of Extrinsic Apoptotic Signaling Pathway during Definitive Erythropoiesis in Normal Patients and in Patients with β-Thalassemia

Apoptosis is a process of programmed cell death which has an important role in tissue homeostasis and in the control of organism development. Here, we focus on information concerning the role of the extrinsic apoptotic pathway in the control of human erythropoiesis. We discuss the role of tumor necrosis factor α (TNFα), tumor necrosis factor ligand superfamily member 6 (FasL), tumor necrosis factor-related apoptosis-inducing (TRAIL) and caspases in normal erythroid maturation. We also attempt to initiate a discussion on the observations that mature erythrocytes contain most components of the receptor-dependent apoptotic pathway. Finally, we point to the role of the extrinsic apoptotic pathway in ineffective erythropoiesis of different types of β-thalassemia.

Hematologic Features of Children and Adolescent Patients with Acute Hypersensitivity Reactions on Drugs and Food

Hematological parameters and blood biochemical markers were measured in 131 children and adolescent patients (70 boys) aged 2 to 17 years with acute hypersensitivity reactions induced by food (59 patients) and medicines (72 patients) in order to establish differences in clinical manifestations and hematological parameters in children with food and drug hypersensitivity and to elaborate the hematological criteria for differentiating the possible pathophysiological mechanisms of various types of hypersensitivity. Both groups of patients had comparable clinical symptoms with a predominance of skin lesions. The significant differences between the groups with drug- and food-induced hypersensitivity reactions were found in their red blood characteristics. In patients with hypersensitive reactions to drugs, significantly lower levels of erythrocytes and hemoglobin were found, while the median values of these parameters did not exceed the limits of reference values. These differences persisted also in the analysis of hemoglobin values, analyzed with accounting for the age and sex of patients. The reduction of hemoglobin was not accompanied by an increase in bilirubin in these patients. Thus, this fact does not support the assumption about the drug-induced hemolysis as a main effect influencing the hematological parameters. Hemogram evaluation performed during 7–10 days after admission demonstrated a higher level of hemoglobin in both groups. The biochemical markers were not significantly distinguished except bilirubin and alkaline phosphatase which were higher in patients with food-induced hypersensitivity.

Hepcidin and diabetes are independently related with soluble transferrin receptor levels in chronic dialysis patients

Background: Soluble transferrin receptor (sTfR) is a biomarker of erythropoiesis, which is often impaired in dialysis patients. The aim of our study was to evaluate sTfR levels in chronically dialyzed patients and assess potential determinants of its levels. Methods: We performed a cross-sectional study by evaluating 246 end-stage renal disease patients undergoing dialysis and 32 healthy controls. Circulating levels of interleukin (IL)-6, C-reactive protein (CRP), tumor necrosis factor (TNF)-α, hepcidin, sTfR, growth differentiation factor 15 (GDF15), and traditional iron metabolism markers were measured, as well as hemogram parameters. Clinical data was obtained from all patients. Results: Compared to controls, patients presented similar values of sTfR, reticulocytes and reticulocyte production index (RPI), and significantly higher levels of IL-6, CRP, ferritin, hepcidin, TNF-α, and GDF15. Iron, transferrin, hemoglobin levels, erythrocyte count, mean cell hemoglobin (MCH), and mean cell hemoglobin concentration (MCHC) values were significantly lower in dialysis group. Within patients, sTfR values were higher in diabetic patients and were positively and significantly correlated with reticulocytes and erythrocytes, RPI, and therapeutic doses of erythropoiesis stimulating agents (ESA) and intravenous iron; and inversely and significantly correlated with circulating iron, ferritin, transferrin saturation, hepcidin, MCH, and MCHC. In multiple linear regression analysis, ESA dose, RPI, serum iron, diabetes, and hepcidin levels were independently associated with sTfR levels in dialysis patients and, thus, with erythropoiesis. Conclusion: Our data suggest that, besides RPI and ESA dose, diabetes and hepcidin are closely related to erythropoiesis in dialysis patients. The influence of diabetes on sTfR levels deserves further investigation.

Association between Insulin-Like Growth Factor-I Levels and the Disease Progression and Anemia in Visceral Leishmaniasis

We analyzed the association between insulin-like growth factor-I (IGF-I) and the pathogenesis of anemia during active visceral leishmaniasis (VL). Serum levels of IGF-I, IGF-binding protein 3 (IGFBP3), and cytokines were measured in samples from individuals with active VL and cured VL, asymptomatic Leishmania-infected, and noninfected individuals. Then, we extended our analysis to VL dogs to evaluate hematimetric parameters, bone marrow alterations, and cytokine and IGF-I expression. We identified a positive correlation between lower IGF-I and IGFBP3 levels in active VL patients and lower hemoglobin levels. In infected dogs, there was a positive correlation between lower IGF-I expression in the bone marrow and lower peripheral blood hematocrit and hemoglobin levels. There was no correlation between decreased IGF-I level/expression and any measured cytokine serum levels in either host. The data suggest that low IGF-I expression is associated with pathogenesis of anemia in active VL, primarily in severe cases, by mechanisms other than alterations in cytokine production.

Hepcidin-ferroportin axis in health and disease

Hepcidin is central to regulation of iron metabolism. Its effect on a cellular level involves binding ferroportin, the main iron export protein, resulting in its internalization and degradation and leading to iron sequestration within ferroportin-expressing cells. Aberrantly increased hepcidin leads to systemic iron deficiency and/or iron restricted erythropoiesis. Furthermore, insufficiently elevated hepcidin occurs in multiple diseases associated with iron overload. Abnormal iron metabolism as a consequence of hepcidin dysregulation is an underlying factor resulting in pathophysiology of multiple diseases and several agents aimed at manipulating this pathway have been designed, with some already in clinical trials. In this chapter, we present an overview of and rationale for exploring the development of hepcidin agonists and antagonists in various clinical scenarios.

Sphingolipid-mediated inflammatory signaling leading to autophagy inhibition converts erythropoiesis to myelopoiesis in human hematopoietic stem/progenitor cells

Elevated levels of the pro-inflammatory cytokine tumor necrosis factor-α (TNFα) inhibit erythropoiesis and cause anemia in patients with cancer and chronic inflammatory diseases. TNFα is also a potent activator of the sphingomyelinase (SMase)/ceramide pathway leading to ceramide synthesis and regulating cell differentiation, proliferation, apoptosis, senescence, and autophagy. Here we evaluated the implication of the TNFα/SMase/ceramide pathway on inhibition of erythropoiesis in human CD34⁺ hematopoietic stem/progenitor cells (CD34/HSPCs) from healthy donors. Exogenous synthetic C2- and C6-ceramide as well as bacterial SMase inhibited erythroid differentiation in erythropoietin-induced (Epo)CD34/HSPCs shown by the analysis of various erythroid markers. The neutral SMase inhibitor GW4869 as well as the genetic inhibition of nSMase with small interfering RNA (siRNA) against sphingomyelin phosphodiesterase 3 (SMPD3) prevented the inhibition by TNFα, but not the acid SMase inhibitor desipramine. Moreover, sphingosine-1-phosphate (S1P), a ceramide metabolite, restored erythroid differentiation, whereas TNFα inhibited sphingosine kinase-1, required for S1P synthesis. Analysis of cell morphology and colony formation demonstrated that erythropoiesis impairment was concomitant with a granulomonocytic differentiation in TNFα- and ceramide-treated EpoCD34/HSPCs. Inhibition of erythropoiesis and induction of granulomonocytic differentiation were correlated to modulation of hematopoietic transcription factors (TFs) GATA-1, GATA-2, and PU.1. Moreover, the expression of microRNAs (miR)-144/451, miR-146a, miR-155, and miR-223 was also modulated by TNFα and ceramide treatments, in line with cellular observations. Autophagy plays an essential role during erythropoiesis and our results demonstrate that the TNFα/neutral SMase/ceramide pathway inhibits autophagy in EpoCD34/HSPCs. TNFα- and ceramide-induced phosphorylation of mTOR^S2448 and ULK1^S758, inhibited Atg13^S355 phosphorylation, and blocked autophagosome formation as shown by transmission electron microscopy and GFP-LC3 punctae formation. Moreover, rapamycin prevented the inhibitory effect of TNFα and ceramides on erythropoiesis while inhibiting induction of myelopoiesis. In contrast, bafilomycin A1, but not siRNA against Atg5, induced myeloid differentiation, while both impaired erythropoiesis. We demonstrate here that the TNFα/neutral SMase/ceramide pathway inhibits erythropoiesis to induce myelopoiesis via modulation of a hematopoietic TF/miR network and inhibition of late steps of autophagy. Altogether, our results reveal an essential role of autophagy in erythroid vs. myeloid differentiation.

Bone marrow hematopoietic dysfunction in untreated chronic lymphocytic leukemia patients

The consequences of immune dysfunction in B-chronic lymphocytic leukemia (CLL) likely relate to the incidence of serious recurrent infections and second malignancies that plague CLL patients. The well-described immune abnormalities are not able to consistently explain these complications. Here, we report bone marrow (BM) hematopoietic dysfunction in early and late stage untreated CLL patients. Numbers of CD34⁺ BM hematopoietic progenitors responsive in standard colony-forming unit (CFU) assays, including CFU-GM/GEMM and CFU-E, were significantly reduced. Flow cytometry revealed corresponding reductions in frequencies of all hematopoietic stem and progenitor cell (HSPC) subsets assessed in CLL patient marrow. Consistent with the reduction in HSPCs, BM resident monocytes and natural killer cells were reduced, a deficiency recapitulated in blood. Finally, we report increases in protein levels of the transcriptional regulators HIF-1α, GATA-1, PU.1, and GATA-2 in CLL patient BM, providing molecular insight into the basis of HSPC dysfunction. Importantly, PU.1 and GATA-2 were rapidly increased when healthy HSPCs were exposed in vitro to TNFα, a cytokine constitutively produced by CLL B cells. Together, these findings reveal BM hematopoietic dysfunction in untreated CLL patients that provides new insight into the etiology of the complex immunodeficiency state in CLL.

Anti-anemia effects of ginsenoside Rk3 and ginsenoside Rh4 on mice with ribavirin-induced anemia

Ginsenoside Rk3 and ginsenoside Rh4 stimulate hematopoiesis and show excellent anti-anemia effectsviathe combined effects of different related cytokines.

Impact of weight loss on inflammation and red blood cell biomarkers after laparoscopic gastric banding surgery

Adipose tissue produces several adipokines that are enrolled in different metabolic and inflammatory pathways that may disturb iron metabolism and erythropoiesis. Considering that laparoscopic adjustable gastric banding (LAGB) has not been associated with a long-term risk of malabsorption, we performed a 13-month follow-up study in severe obese patients submitted to LAGB in order to clarify its impact on inflammation, iron metabolism and on red blood cell (RBC) biomarkers. Twenty obese patients were enrolled in the study, being clinical and analytically assessed before (T0) and 13 months after LAGB intervention (T1). Inflammation, iron bioavailability and RBC biomarkers were evaluated at T0 and T1. At T1, weight and anthropometric indices decreased significantly; patients showed a significant increase in mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration (MCHC), and a reduction in red cell distribution width, ferritin, hepcidin, tumor necrosis factor-α, interleukin-6 (IL-6) and C-reactive protein. Before LAGB, IL-6 correlated negatively with iron, hemoglobin concentration and MCHC; hepcidin correlated inversely with transferrin. Our data show that 13 months after LAGB, the weight loss is associated with an improvement in inflammation, namely a reduction in IL-6 that may reduce hepcidin production, improving iron availability for erythropoiesis, as shown by more adequate erythrocyte hemoglobinization.

Role of hepcidin-ferroportin axis in the pathophysiology, diagnosis, and treatment of anemia of chronic inflammation

Anemia of chronic inflammation (ACI) is a frequently diagnosed anemia and portends an independently increased morbidity and poor outcome associated with multiple underlying diseases. The pathophysiology of ACI is multifactorial, resulting from the effects of inflammatory cytokines which both directly and indirectly suppress erythropoiesis. Recent advances in molecular understanding of iron metabolism provide strong evidence that immune mediators, such as IL-6, lead to hepcidin-induced hypoferremia, iron sequestration, and decreased iron availability for erythropoiesis. The role of hepcidin-ferroportin axis in the pathophysiology of ACI is stimulating the development of new diagnostics and targeted therapies. In this review, we present an overview of and rationale for inflammation-, iron-, and erythropoiesis-related strategies currently in development.

Anemia of Chronic Disease and Iron Deficiency Anemia in Inflammatory Bowel Diseases: Pathophysiology, Diagnosis, and Treatment

Anemia coexists with inflammatory bowel disease (IBD) in up to two-thirds of patients, significantly impairing quality of life. The most common types of anemia in patients with IBD are iron deficiency anemia and anemia of chronic disease, which often overlap. In most cases, available laboratory tests allow successful diagnosis of iron deficiency, where difficulties appear, recently established indices such as soluble transferrin-ferritin ratio or percentage of hypochromic red cells are used. In this review, we discuss the management of the most common types of anemia in respect of the latest available data. Thus, we provide the mechanisms underlying pathophysiology of these entities; furthermore, we discuss the role of hepcidin in developing anemia in IBD. Next, we present the treatment options for each type of anemia and highlight the importance of individual choice of action. We also focus on newly developed intravenous iron preparations and novel, promising drug candidates targeting hepcidin. Concurrently, we talk about difficulties in differentiating between the true and functional iron deficiency, and discuss tools facilitating the process. Finally, we emphasize the importance of proper diagnosis and treatment of anemia in IBD. We conclude that management of anemia in patients with IBD is tricky, and appropriate screening of patients regarding anemia is substantial.

Natural compounds and pharmaceuticals reprogram leukemia cell differentiation pathways

In addition to apoptosis resistance and cell proliferation capacities, the undifferentiated state also characterizes most cancer cells, especially leukemia cells. Cell differentiation is a multifaceted process that depends on complex regulatory networks that involve transcriptional, post-transcriptional and epigenetic regulation of gene expression. The time- and spatially-dependent expression of lineage-specific genes and genes that control cell growth and cell death is implicated in the process of maturation. The induction of cancer cell differentiation is considered an alternative approach to elicit cell death and proliferation arrest. Differentiation therapy has mainly been developed to treat acute myeloid leukemia, notably with all-trans retinoic acid (ATRA). Numerous molecules from diverse natural or synthetic origins are effective alone or in association with ATRA in both in vitro and in vivo experiments. During the last two decades, pharmaceuticals and natural compounds with various chemical structures, including alkaloids, flavonoids and polyphenols, were identified as potential differentiating agents of hematopoietic pathways and osteogenesis.

Distinct mechanisms of inadequate erythropoiesis induced by tumor necrosis factor alpha or malarial pigment

The role of infection in erythropoietic dysfunction is poorly understood. In children with P. falciparum malaria, the by-product of hemoglobin digestion in infected red cells (hemozoin) is associated with the severity of anemia which is independent of circulating levels of the inflammatory cytokine tumor necrosis alpha (TNF-α). To gain insight into the common and specific effects of TNF-α and hemozoin on erythropoiesis, we studied the gene expression profile of purified primary erythroid cultures exposed to either TNF-α (10ng/ml) or to hemozoin (12.5μg/ml heme units) for 24 hours. Perturbed gene function was assessed using co-annotation of associated gene ontologies and expression of selected genes representative of the profile observed was confirmed by real time PCR (rtPCR). The changes in gene expression induced by each agent were largely distinct; many of the genes significantly modulated by TNF-α were not affected by hemozoin. The genes modulated by TNF-α were significantly enriched for those encoding proteins involved in the control of type 1 interferon signalling and the immune response to viral infection. In contrast, genes induced by hemozoin were significantly enriched for functional roles in regulation of transcription and apoptosis. Further analyses by rtPCR revealed that hemozoin increases expression of transcription factors that form part of the integrated stress response which is accompanied by reduced expression of genes involved in DNA repair. This study confirms that hemozoin induces cellular stress on erythroblasts that is additional to and distinct from responses to inflammatory cytokines and identifies new genes that may be involved in the pathogenesis of severe malarial anemia. More generally the respective transcription profiles highlight the varied mechanisms through which erythropoiesis may be disrupted during infectious disease.

Spectrum of myeloid neoplasms and immune deficiency associated with germline GATA2 mutations

Guanine-adenine-thymine-adenine 2 (GATA2) mutated disorders include the recently described MonoMAC syndrome (Monocytopenia and Mycobacterium avium complex infections), DCML (dendritic cell, monocyte, and lymphocyte deficiency), familial MDS/AML (myelodysplastic syndrome/acute myeloid leukemia) (myeloid neoplasms), congenital neutropenia, congenital lymphedema (Emberger's syndrome), sensorineural deafness, viral warts, and a spectrum of aggressive infections seen across all age groups. While considerable efforts have been made to identify the mutations that characterize this disorder, pathogenesis remains a work in progress with less than 100 patients described in current literature. Varying clinical presentations offer diagnostic challenges. Allogeneic stem cell transplant remains the treatment of choice. Morbidity, mortality, and social costs due to the familial nature of the disease are considerable. We describe our experience with the disorder in three affected families and a comprehensive review of current literature.

Hemozoin inhibition and control of clinical malaria

Malaria has a negative impact on health and social and economic life of residents of endemic countries. The ultimate goals of designing new treatment for malaria are to prevent clinical infection, reduce morbidity, and decrease mortality. There are great advances in the understanding of the parasite-host interaction through studies by various scientists. In some of these studies, attempts were made to evaluate the roles of malaria pigment or toxins in the pathogenesis of malaria. Hemozoin is a key metabolite associated with severe malaria anemia (SMA), immunosuppression, and cytokine dysfunction. Targeting of this pigment may be necessary in the design of new therapeutic products against malaria. In this review, the roles of hemozoin in the morbidity and mortality of malaria are highlighted as an essential target in the quest for effective control of clinical malaria.

Distinct roles for hepcidin and interleukin-6 in the recovery from anemia in mice injected with heat-killed Brucella abortus

Anemia of inflammation (AI) is commonly observed in chronic inflammatory states and may hinder patient recovery and survival. Induction of hepcidin, mediated by interleukin 6, leads to iron-restricted erythropoiesis and anemia. Several translational studies have been directed at neutralizing hepcidin overexpression as a therapeutic strategy against AI. However, additional hepcidin-independent mechanisms contribute to AI, which are likely mediated by a direct effect of inflammatory cytokines on erythropoiesis. In this study, we used wild-type, hepcidin knockout (Hamp-KO) and interleukin 6 knockout (IL-6-KO) mice as models of AI. AI was induced with heat-killed Brucella abortus (BA). The distinct roles of iron metabolism and inflammation triggered by interleukin 6 and hepcidin were investigated. BA-treated wild-type mice showed increased expression of hepcidin and inflammatory cytokines, as well as transitory suppression of erythropoiesis and shortened red blood cell lifespan, all of which contributed to the severe anemia of these mice. In contrast, BA-treated Hamp-KO or IL-6-KO mice showed milder anemia and faster recovery compared with normal mice. Moreover, they exhibited different patterns in the development and resolution of anemia, supporting the notion that interleukin 6 and hepcidin play distinct roles in modulating erythropoiesis in AI.

The effect of iron loading and iron chelation on the innate immune response and subclinical organ injury during human endotoxemia: a randomized trial

In this double-blind randomized placebo-controlled trial involving 30 healthy male volunteers we investigated the acute effects of iron loading (single dose of 1.25 mg/kg iron sucrose) and iron chelation therapy (single dose of 30 mg/kg deferasirox) on iron parameters, oxidative stress, the innate immune response, and subclinical organ injury during experimental human endotoxemia. The administration of iron sucrose induced a profound increase in plasma malondialdehyde 1 h after administration (433±37% of baseline; P<0.0001), but did not potentiate the endotoxemia-induced increase in malondialdehyde, as was seen 3 h after endotoxin administration in the placebo group (P=0.34) and the iron chelation group (P=0.008). Endotoxemia resulted in an initial increase in serum iron levels and transferrin saturation that was accompanied by an increase in labile plasma iron, especially when transferrin saturation reached levels above 90%. Thereafter, serum iron decreased to 51.6±9.7% of baseline at T=8 h in the placebo group versus 84±15% and 60.4±8.9% of baseline at 24 h in the groups treated with iron sucrose and deferasirox, respectively. No significant differences in the endotoxemia-induced cytokine response (TNF-α, IL-6, IL-10 and IL-1RA), subclinical vascular injury and kidney injury were observed between groups. However, vascular reactivity to noradrenalin was impaired in the 6 subjects in whom labile plasma iron was elevated during endotoxemia as opposed to those in whom no labile plasma iron was detected (P=0.029). In conclusion, a single dose of iron sucrose does not affect the innate immune response in a model of experimental human endotoxemia, but may impair vascular reactivity when labile plasma iron is formed. (Clinicaltrials.gov identifier:01349699).

The role of adipocytes in the modulation of iron metabolism in obesity

A tight relationship between iron deficiency and obesity is known to exist. The chronic low-grade inflammation that characterizes obesity enhances hepcidin production, the principal regulator of iron availability. Adipose tissue is known to secret interleukin-6 and leptin that triggers hepcidin production. It was found that adipose tissue also expresses hepcidin and hemojuvelin, a regulator of hepcidin production. These recent findings suggest that adipose tissue may have an important role in erythropoiesis particularly on obesity that is still poorly clarified. This paper discusses these findings and how they can modulate erythropoiesis.

[Heart failure and anemia]

Chronic heart failure has an age-dependent prevalence of 2% and is therefore one of the most frequent diseases in western societies. A reduced hemoglobin concentration according to the definition of the World Health Organization is a common comorbidity affecting more than half of all heart failure patients. Elderly patients, patients suffering from renal impairment and women are more likely to develop anemia but a definitive etiology of anemia is only identified in the minority of cases. Anemia is associated with a poor clinical status and a greater risk of hospitalization and is a predictive factor for increased mortality. The incidence of anemia appears to increase with a poorer functional class. Intravenous iron therapy improves the exercise capacity in patients with systolic heart failure and iron deficiency and is currently being recommended for patients with persistent symptoms despite optimal medical and device therapy. However, erythropoietin-stimulating agents as a treatment for anemia in chronic heart failure have failed to improve clinical outcome in a large randomized trial. In patients with heart failure but with maintained ejection fraction, anemia is also associated with a poor prognosis. Specific therapeutic recommendations for these patients are still not available.

Monoclonal anti-TNF antibodies can elevate hemoglobin level in patients with ankylosing spondylitis

Anemia is one of the extra-articular findings of ankylosing spondylitis (AS), and anti-TNF therapy has been shown benefit in patients with anemia associated AS. In this study, we aimed to evaluate and compare the effects of biological and non-biological agents on hemoglobin levels in AS patients. One hundred consecutive patients who fulfilled ASAS criteria for AS were included in the study. Fifty-four of the patients treated with anti-TNF agents (20 patients treated with infliximab, 20 patients with adalimumab, and 14 patients with etanercept), and 46 patients treated with non-steroidal anti-inflammatory drugs and/or other disease modifying anti-rheumatic drugs. The C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), hemoglobin (HGB), hematocrit (HCT) counts, and BASDAI scores were compared before starting therapy and at 52 weeks. There was no statistically significant difference between patients about demographical data (age, sex) and disease age (p > 0.05 for all). Significant difference was determined between HGB, HCT, CRP, ESR, and BASDAI values before and after therapy (for infliximab p: 0.001; 0.000; 0.000; 0.000; 0.000, respectively, and for adalimumab p: 0.017; 0.03; 0.001; 0.002; 0.000, respectively). In etanercept group, there was no significant difference in HGB values, when compared with before starting therapy and at 52 weeks (p > 0.05). In the group of treated with non-biological agents, ESR values and BASDAİ scores showed distinctive improvement after 52 weeks of therapy, but was not a significant difference in hemoglobin and hematocrit values.

CONCLUSION

Anti-TNF-alpha therapy with monoclonal antibodies (adalimumab and infliximab) did not only suppress disease activity but also provided a significant improvement in HGB levels. In the groups of treated with a TNF-alpha receptor antagonist (ETA) and non-biological agents, disease activity was suppressed, but there was not founded significant improvement in HGB levels after 52 weeks. Different outcomes of anti-TNF agents may be associated with their different effect mechanisms.

Neopterin, inflammation-associated product, prolongs erythropoiesis suppression in aged SAMP1 mice due to senescent stromal-cell impairment

Anemia induced by inflammation is well known to be more serious in the elderly than in non-elderly adults; however, the reason why this is so remains unclear. Neopterin produced by monocytes during inflammation promotes myelopoiesis but suppresses B-lymphopoiesis and erythropoiesis, by activating stromal cells in mice. Here, age-related changes in the erythropoietic response to neopterin were determined using senescence accelerated mice (SAMP1) with senescence stromal-cell impairment. Intravenous injection of neopterin into young mice (8-12 weeks old) resulted in a decrease in erythroid progenitor cell number in the bone marrow (BM), concomitant with an increase in myeloid progenitor cell number over one week. Intravenous injection of neopterin into aged mice (30-36 weeks old) resulted in a prolonged decrease in erythroid progenitor cell number in the BM over three weeks and a limited increase in myeloid progenitor cell number over one day. Neopterin treatment induced a decrease in serum erythropoietin concentrations in young mice but not in aged mice. The gene expression of tumor necrosis factor α (TNF-α), a negative regulator of erythropoiesis, was up-regulated in the BM of both young and aged mice, and the degree of TNF-α up-regulation was the same in both groups. The gene expression of interleukin (IL)-11, a positive regulator of erythropoiesis, was also up-regulated over one day in both young and aged mice. However, IL-11 gene expression remained up-regulated thereafter in young mice, whereas it was rapidly down-regulated in aged mice. These data suggest that prolonged suppression of erythropoiesis in aged mice may be due to a decrease in the production of positive regulators rather than to an increase in the production of negative regulators. Our combined data suggest that age-related impairment of stromal cells induces serious anemia in the elderly during inflammation.