The Many Facets of Erythropoietin Physiologic and Metabolic Response

The association of manganese levels with red cell distribution width: A population-based study

OBJECTIVES

Experimental and acute exposure studies imply that manganese affects red blood cell production. Nevertheless, the association between environmental exposure and red blood cell distribution width (RDW) has yet to be explored. This research sought to assess the correlation between blood manganese levels and RDW within the general population of the United States.

MATERIALS AND METHODS

Employing weighted multiple linear regression models, data from the 2011-2018 National Health and Nutrition Examination Survey (NHANES) were utilized to assess the correlation between manganese levels in the blood and RDW. Restricted cubic spline plots and two-piecewise linear regression models were also employed.

RESULT

The analysis included a total of 15882 participants in which we determined an independent positive relationship between blood manganese levels and RDW among participants(β = 0.079, P<0.001). Moreover, we identified a J-shaped association between blood manganese levels and RDW in total participants (inflection point for blood manganese: 7.32 ug/L) and distinct subgroups following adjusted covariates. Women exhibited a more pronounced association, even after controlling for adjusted covariates.

CONCLUSIONS

We determined a J-shaped relationship between blood manganese levels and RDW with an inflection point at 7.32 ug/L for blood manganese. Nevertheless, fundamental research and large sample prospective studies are needed to determine the extent to which blood manganese levels correlate with RDW.

Endothelial specific prolyl hydroxylase domain-containing protein 2 deficiency attenuates aging-related obesity and exercise intolerance

Obesity and exercise intolerance greatly reduce the life quality of older people. Prolyl hydroxylase domain-containing protein 2 (PHD2) is an important enzyme in modulating hypoxia-inducible factor-alpha (HIF) protein. Using vascular endothelial cell-specific PHD2 gene knockout (PHD2 ECKO) mice, we investigated the role of endothelial PHD2 in aging-related obesity and exercise capacity. Briefly, PHD2 ECKO mice were obtained by crossing PHD2-floxed mice with VE-Cadherin (Cdh5)-Cre transgenic mice. The effect of PHD2 ECKO on obesity and exercise capacity in PHD2 ECKO mice and control PHD2f/f mice were determined in young mice (6 to 7 months) and aged mice (16-18 months). We found that aged PHD2 ECKO mice, but not young mice, exhibited a lean phenotype, characterized by lower fat mass, and its ratio to lean weight, body weight, or tibial length, while their food uptake was not reduced compared with controls. Moreover, as compared with aged control mice, aged PHD2 ECKO mice exhibited increased oxygen consumption at rest and during exercise, and the maximum rate of oxygen consumption (VO2 max) during exercise. Furthermore, as compared with corresponding control mice, both young and aged PHD2 ECKO mice demonstrated improved glucose tolerance and lower insulin resistance. Together, these data demonstrate that inhibition of vascular endothelial PHD2 signaling significantly attenuates aging-related obesity, exercise intolerance, and glucose intolerance.

Mechanisms of Postischemic Stroke Angiogenesis: A Multifaceted Approach

Ischemic stroke constitutes a significant global health care challenge, and a comprehensive understanding of its recovery mechanisms is imperative for the development of innovative therapeutic strategies. Angiogenesis, a pivotal element of ischemic tissue repair, facilitates the restoration of blood flow to damaged regions, thereby promoting neuronal regeneration and functional recovery. Nevertheless, the mechanisms underlying postischemic stroke angiogenesis remain incompletely elucidated. This review meticulously examines the constituents of the neurovascular unit, ion channels, molecular mediators, and signaling pathways implicated in angiogenesis following stroke. Furthermore, it delves into prospective therapeutic strategies informed by these factors. Our objective is to provide detailed and exhaustive information on the intricate mechanisms governing postischemic stroke angiogenesis, thus providing a robust scientific foundation for the advancement of novel neurorepair therapies.

Preexisting Hyperuricemia Before High-Altitude Ascent is Associated with a Slower Recovery of Estimated Glomerular Filtration Rate Following Descent

Zhao, Linggong, Yujie Huang, and Xiaoling Tan. Preexisting hyperuricemia before high-altitude ascent is associated with a slower recovery of estimated glomerular filtration rate following descent. High Alt Med Biol. 00:00-00, 2024. Objectives: Hypoxia at high altitudes results in elevated uric acid (UA) and reduced estimated glomerular filtration rate (eGFR). However, the impact of a prolonged high-altitude sojourn on UA levels and renal function in patients with preexisting hyperuricemia warrants further exploration. The study was to investigate the eGFR and related factors in patients with preexisting hyperuricemia following exposure to high altitude. Methods: The study included 345 participants, who worked at a high altitude for 1 year. Anthropometric and laboratory indices were collected before ascent (i.e., baseline), as well as 20 and 80 days after descent. The participants were categorized into individuals with hyperuricemia (HUA) or normal uric acid (NUA) group based on the presence or absence of hyperuricemia at baseline. Results: No difference in baseline eGFR was observed between the two groups before ascend or on day 20 after descent (p > 0.05). However, on day 80, eGFR of the HUA group was lower compared with the NUA group (p < 0.05). Correlations existed between post-descent eGFR levels and variables, including sampling time, UA levels, total and direct bilirubin, and baseline grouping. Conclusions: After high-altitude exposure, the recovery of eGFR was delayed in participants with preexisting hyperuricemia. Preexisting hyperuricemia and high-altitude hypoxia jointly contribute to renal impairment.

Erythropoietin induces tumour progression and CD39 expression on immune cells in a preclinical model of triple-negative breast cancer

The adverse effects observed in some cancer patients treated with erythropoiesis-stimulating agents such as erythropoietin (EPO) might be due to the latter's well-known immunosuppressive functions. Here, we used a mouse model of syngeneic triple-negative breast cancer to explore EPO's immunomodulatory role in a tumour setting. Our results showed that EPO treatment promotes tumour growth, exacerbates the 'immune desert', and results in a 'cold tumour'. EPO treatment changed the immune cell distribution in peripheral blood, secondary lymphoid organs, and the tumour microenvironment (TME). Our in-depth analysis showed that EPO mainly impacts CD4 T cells by accelerating their activation in the spleen and thus their subsequent exhaustion in the TME. This process is accompanied by a general elevation of CD39 expression by several immune cells (notably CD4 T cells in the tumour and spleen), which promotes an immunosuppressive TME. Lastly, we identified a highly immunosuppressive CD39+ regulatory T cell population (ICOS+, CTLA4+, Ki67+) as a potential biomarker of the risk of EPO-induced tumour progression. EPO displays pleiotropic immunosuppressive functions and enhances mammary tumour progression in mice.

Are peptidomimetics the compounds of choice for developing new modulators of the JAK-STAT pathway?

Protein-protein interactions (PPIs) play critical roles in a wide range of biological processes including the dysregulation of cellular pathways leading to the loss of cell function, which in turn leads to diseases. The dysfunction of several signaling pathways is linked to the insurgence of pathological processes such as inflammation, cancer development and neurodegeneration. Thus, there is an urgent need for novel chemical modulators of dysregulated PPIs to drive progress in targeted therapies. Several PPIs have been targeted by bioactive compounds, and, often, to properly cover interacting protein regions and improve the biological activities of modulators, a particular focus concerns the employment of macrocycles as proteomimetics. Indeed, for their physicochemical properties, they occupy an intermediate space between small organic molecules and macromolecular proteins and are prominent in the drug discovery process. Peptide macrocycles can modulate fundamental biological mechanisms and here we will focus on peptidomimetics active on the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways.

Comprehensive analysis of prohibited substances and methods in sports: Unveiling trends, pharmacokinetics, and WADA evolution

This review systematically compiles sports-related drugs, substances, and methodologies based on the most frequently detected findings from prohibited lists published annually by the World Anti-Doping Agency (WADA) between 2003 and 2021. Aligned with structure of the 2023 prohibited list, it covers all proscribed items and details the pharmacokinetics and pharmacodynamics of five representatives from each section. Notably, it explores significant metabolites and metabolic pathways associated with these substances. Adverse analytical findings are summarized in tables for clarity, and the prevalence is visually represented through charts. The review includes a concise historical overview of doping and WADA's role, examining modifications in the prohibited list for an understanding of evolving anti-doping measures.

Regulation of Erythroid Differentiation via the HIF1α-NFIL3-PIM1 Signaling Axis Under Hypoxia

Aims: Erythropoiesis is controlled by several factors, including oxygen level under different circumstances. However, the role of hypoxia in erythroid differentiation and the underlying mechanisms are poorly understood. We studied the effect and mechanism of hypoxia on erythroid differentiation of K562 cells and observed the effect of hypoxia on early erythropoiesis of zebrafish. Results: Compared with normal oxygen culture, both hemin-induced erythroid differentiation of K562 cells and the early erythropoiesis of zebrafish were inhibited under hypoxic treatment conditions. Hypoxia-inducible factor 1 alpha (HIF1α) plays a major role in the response to hypoxia. Here, we obtained a stable HIF1α knockout K562 cell line using the CRISPR-Cas9 technology and further demonstrated that HIF1α knockout promoted hemin-induced erythroid differentiation of K562 cells under hypoxia. We demonstrated an HIF1-mediated induction of the nuclear factor interleukin-3 (NFIL3) regulated in K562 cells under hypoxia. Interestingly, a gradual decrease in NFIL3 expression was detected during erythroid differentiation of erythropoietin-induced CD34+ hematopoietic stem/progenitor cells (HSPCs) and hemin-induced K562 cells. Notably, erythroid differentiation was inhibited by enforced expression of NFIL3 under normoxia and was promoted by the knockdown of NFIL3 under hypoxia in hemin-treated K562 cells. In addition, a target of NFIL3, pim-1 proto-oncogene, serine/threonine kinase (PIM1), was obtained by RNA microarray after NFIL3 knockdown. PIM1 can rescue the inhibitory effect of NFIL3 on hemin-induced erythroid differentiation of K562 cells. Innovation and Conclusion: Our findings demonstrate that the HIF1α-NFIL3-PIM1 signaling axis plays an important role in erythroid differentiation under hypoxia. These results will provide useful clues for preventing the damage of acute hypoxia to erythropoiesis.

Exploring the Potential Benefits of Interventions When Addressing Simulated Altitude Hypoxia during Male Cyclist Sports: A Systematic Review

Training in hypoxic environments enhances endurance, but the various influences of training protocols and supplementation for efficient performance are not yet clear. This systematic review explored the effects of different supplementations and interventions used to optimize the aerobic and anaerobic performance of cyclists. Data were collected from the following sources: PubMed, Google Scholar, EMBASE, WOS, Cochrane Central Register of Controlled Trials, and randomized controlled trials (RCTs). Studies that explored the effects of supplementation or intervention during cycling were selected for analysis. Five studies (67 male cyclists; mean age, 23.74–33.56 years) reported different outcomes from supplementation or intervention during the acute hypoxia of cyclists. Three studies (42 male cyclists; mean age, 25.88–36.22 years) listed the benefits of beetroot juice in preserving SpO2 (pulse oxygen saturation) and enhancing high-intensity endurance performance, effectively preventing the reduction in power output. This systematic review provided evidence that the different effects of ischemic preconditioning (IPC), sildenafil, and beetroot (BR) supplementation and intervention did not present a statistically greater benefit than for normoxia groups, but BR supplementation promoted the benefits of SpO2. Future research should evaluate the duration and higher FiO2 (simulated altitude, hypoxia) levels of hypoxia in training protocols for cyclists. This is important when determining the effectiveness of supplements or interventions in hypoxic conditions and their impact on sports performance, particularly in terms of power output.

Neuronal nitric oxide synthase required for erythropoietin modulation of heart function in mice

Introduction: Erythropoietin (EPO) acts primarily in regulating red blood cell production mediated by high EPO receptor (EPOR) expression in erythroid progenitor cells. EPO activity in non-erythroid tissue is evident in mice with EPOR restricted to erythroid tissues (ΔEPORE) that become obese, glucose-intolerant, and insulin-resistant. In animal models, nitric oxide synthase (NOS) contributes to EPO activities including erythropoiesis, neuroprotection, and cardioprotection against ischemia-reperfusion injury. However, we found that extended EPO treatment to increase hematocrit compromised heart function, while the loss of neuronal NOS (nNOS) was protective against the deleterious activity of EPO to promote heart failure. Methods: Wild-type (WT) mice, ΔEPORE mice, and nNOS-knockout mice (nNOS-/-) were placed on a high-fat diet to match the ΔEPORE obese phenotype and were treated with EPO for 3 weeks. Hematocrit and metabolic response to EPO treatment were monitored. Cardiac function was assessed by echocardiography and ultrasonography. Results: ΔEPORE mice showed a decrease in the left ventricular outflow tract (LVOT) peak velocity, ejection fraction, and fractional shortening, showing that endogenous non-erythroid EPO response is protective for heart function. EPO treatment increased hematocrit in all mice and decreased fat mass in male WT, demonstrating that EPO regulation of fat mass requires non-erythroid EPOR. EPO treatment also compromised heart function in WT mice, and decreased the pulmonary artery peak velocity (PA peak velocity), LVOT peak velocity, ejection fraction, and fractional shortening, but it had minimal effect in further reducing the heart function in ΔEPORE mice, indicating that the adverse effect of EPO on heart function is not related to EPO-stimulated erythropoiesis. ΔEPORE mice had increased expression of heart failure-associated genes, hypertrophic cardiomyopathy-related genes, and sarcomeric genes that were also elevated with EPO treatment in WT mice. Male and female nNOS-/- mice were protected against diet-induced obesity. EPO treatment in nNOS-/- mice increased the hematocrit that tended to be lower than WT mice and decreased the PA peak velocity but did not affect the LVOT peak velocity, ejection fraction, and fractional shortening, suggesting that nNOS is required for the adverse effect of EPO treatment on heart function in WT mice. EPO treatment did not change expression of heart failure-associated gene expression in nNOS-/- mice. Discussion: Endogenous EPO has a protective effect on heart function. With EPO administration, in contrast to the protective effect to the cardiac injury of acute EPO treatment, extended EPO treatment to increase hematocrit in WT mice adversely affected the heart function with a corresponding increase in expression of heart failure-associated genes. This EPO activity was independent of EPO-stimulated erythropoiesis and required EPOR in non-erythroid tissue and nNOS activity, while nNOS-/- mice were protected from the EPO-associated adverse effect on heart function. These data provide evidence that nNOS contributes to the negative impact on the heart function of high-dose EPO treatment for anemia.

Spatiotemporal expression profiles of c-Mpl mRNA in the tooth germ: Comparative expression dynamics of vascularization-related genes

BACKGROUND

Vascularization is an essential event for both embryonic organ development and tissue repair in adults. During mouse tooth development, endothelial cells migrate into dental papilla during the cap stage, and form blood vessels through angiogenesis. Megakaryocytes and/or platelets, as other hematopoietic cells, express angiogenic molecules and can promote angiogenesis in adult tissues. However, it remains unknown which cells are responsible for attracting and leading blood vessels through the dental papilla during tooth development.

METHODS

Here we analyzed the spatiotemporal expression of c-Mpl mRNA in developing molar teeth of fetal mice. Expression patterns were then compared with those of several markers of hematopoietic cells as well as of angiogenic elements including CD41, erythropoietin receptor, CD34, angiopoietin-1 (Ang-1), Tie-2, and vascular endothelial growth factor receptor2 (VEGFR2) through in situ hybridization or immunohistochemistry.

RESULTS

Cells expressing c-Mpl mRNA was found in several parts of the developing tooth germ, including the peridental mesenchyme, dental papilla, enamel organ, and dental lamina. This expression occurred in a spatiotemporally controlled fashion. CD41-expressing cells were not detected during tooth development. The spatiotemporal expression pattern of c-Mpl mRNA in the dental papilla was similar to that of Ang-1, which preceded invasion of endothelial cells. Eventually, at the early bell stage, the c-Mpl mRNA signal was detected in morphologically differentiating odontoblasts that accumulated in the periphery of the dental papilla along the inner enamel epithelium layer of the future cusp region.

CONCLUSION

During tooth development, several kinds of cells express c-Mpl mRNA in a spatiotemporally controlled fashion, including differentiating odontoblasts. We hypothesize that c-Mpl-expressing cells appearing in the forming dental papilla at the cap stage are odontoblast progenitor cells that migrate to the site of odontoblast differentiation. There they attract vascular endothelial cells into the forming dental papilla and lead cells toward the inner enamel epithelium layer through production of angiogenic molecules (e.g., Ang-1) during migration to the site of differentiation. C-Mpl may regulate apoptosis and/or proliferation of expressing cells in order to execute normal development of the tooth.

Mechanisms and Cardiorenal Complications of Chronic Anemia in People with HIV

Chronic anemia is more prevalent in people living with HIV (PLWH) compared to the general population. The mechanisms that drive chronic anemia in HIV are multifaceted and include functional impairment of hematopoietic stem cells, dysregulation of erythropoietin production, and persistent immune activation. Chronic inflammation from HIV infection adversely affects erythropoiesis, erythrocyte lifespan, and erythropoietin response, leading to a heightened risk of co-infections such as tuberculosis, persistent severe anemia, and increased mortality. Additionally, chronic anemia exacerbates the progression of HIV-associated nephrotoxicity and contributes to cardiovascular risk through immune activation and inflammation. This review highlights the cardinal role of chronic inflammation as a link connecting persistent anemia and cardiovascular complications in PLWH, emphasizing the need for a universal understanding of these interconnected pathways for targeted interventions.

Erythropoietin receptor signal is crucial for periodontal ligament stem cell-based tissue reconstruction in periodontal disease

Alveolar bone loss caused by periodontal disease eventually leads to tooth loss. Periodontal ligament stem cells (PDLSCs) are the tissue-specific cells for maintaining and repairing the periodontal ligament, cementum, and alveolar bone. Here, we investigated the role of erythropoietin receptor (EPOR), which regulates the microenvironment-modulating function of mesenchymal stem cells, in PDLSC-based periodontal therapy. We isolated PDLSCs from patients with chronic periodontal disease and healthy donors, referred to as PD-PDLSCs and Cont-PDLSCs, respectively. PD-PDLSCs exhibited reduced potency of periodontal tissue regeneration and lower expression of EPOR compared to Cont-PDLSCs. EPOR-silencing suppressed the potency of Cont-PDLSCs mimicking PD-PDLSCs, whereas EPO-mediated EPOR activation rejuvenated the reduced potency of PD-PDLSCs. Furthermore, we locally transplanted EPOR-silenced and EPOR-activated PDLSCs into the gingiva around the teeth of ligament-induced periodontitis model mice and demonstrated that EPOR in PDLSCs participated in the regeneration of the periodontal ligament, cementum, and alveolar bone in the ligated teeth. The EPOR-mediated paracrine function of PDLSCs maintains periodontal immune suppression and bone metabolic balance via osteoclasts and osteoblasts in the periodontitis model mice. Taken together, these results suggest that EPOR signaling is crucial for PDLSC-based periodontal regeneration and paves the way for the development of novel options for periodontal therapy.

Laboratory Analysis of the Renal Function Changes Under Long-Term Exposure to Extremely Low Ambient Temperatures: Case Report

The study subject was a healthy, 47-year-old man, a low temperature Guinness World Record holder. He spent 50 days alone in Rovaniemi, Lapland, and functioned in the ambient temperature ranging from +2°C to -37°C. He did not use sources of heat, he did not eat warm meals or drink hot water, and did not dry his clothes. He slept in an igloo, on an ice cover of 20-30 cm. He spent 10 hours a day in a sleeping bag and for the remaining time he walked, skied, or rode a bicycle, and practiced swimming. The aim of the study was a laboratory assessment of renal capacity in a man exposed to long-term extremely low ambient temperatures. The study was approved by the Ethical Committee at the Regional Medical Chamber in Krakow, Poland (approval No.: 194/KBL/OIL/2019). Twice during the observation, urine and blood were collected and analyzed: before and after the prolonged exposure to extremely low ambient temperatures. Changes were seen in many blood and urine parameters, but in urine, they were more significant. In urine, decreased values of sodium (by 53.9%), potassium (by 22.6%), creatinine (by 65.5%), urea (by 61.3%), uric acid (by 58.4%), and protein (by 50%) were observed. Neutrophil gelatinase-associated lipocalin (NGAL) increased by 34%. Absence of calcium oxalate excretion was reported relative to the value before the exposure to cold. In blood, increased values of interleukin-6 (by 60%) and β-2-microglobulin (by 26.9%) were observed. Erythropoietin decreased by 22.4%. No changes were noted in estimated glomerular filtration rate. The study subject lost 10 kg in weight. On the basis of the results obtained during the observation, it can be determined that the probable cause of changes in the laboratory results of the subject was the diet used, and not a dysfunction of the excretory system. The body weight loss and activation of compensating mechanisms focused on saving vitally important diet components, caused by the insufficient diet, exclude the theory of a negative effect of exposure to extremely low temperatures on renal filtration function.

Organogermanium, Ge-132, promotes the clearance of senescent red blood cells via macrophage-mediated phagocyte activation

Red blood cells (RBCs) are renewed in a cyclic manner. Aging RBCs are captured and degraded by phagocytic cells, and heme metabolic pigments are subsequently excreted in feces. We evaluated the effect of an organogermanium compound on RBC metabolism and found that the phagocytosis of RAW264.7 macrophage-like cells was increased by treatment with 3-(trihydroxygermyl)propanoic acid (THGP). Additionally, consumption of Ge-132 (a dehydrate polymer of THGP) changed the fecal color to bright yellow and increased the erythrocyte metabolic pigment levels and antioxidant activity in feces. These data suggest that Ge-132 may activate macrophages in the body and promote the degradation of aged RBCs. Furthermore, Ge-132 intake promoted not only increases in RBC degradation but also the induction of erythroblast differentiation in bone marrow cells. The normal hematocrit levels were maintained due to the maintenance of homeostasis, even though Ge-132 ingestion increased erythrocyte degradation. Therefore, Ge-132 enhances the degradation of senescent RBCs by macrophages. In turn, RBC production is increased to compensate for the amount of degradation, and RBC metabolism is increased.

Which sub-compartments of fat mass and fat-free mass are related to blood viscosity factors?

The size of body compartments is a determinant of several factors of blood viscosity. Red cell aggregation is proportional to fat mass while hematocrit is proportional to both fat-free mass and abdominal adiposity, but which parts of these body components are involved in this relationship is not known. Segmental bioelectrical impedance analysis (sBIA) provides a possibility to delineate the relationships more precisely between various subdivisions of the body and blood viscosity factors, going farther than preceding studies using non segmental BIA. In this study we investigated in 38 subjects undergoing a standardized breakfast test with mathematical modelling of glucose homeostasis and a segmental bioelectrical impedance analysis (sBIA) the relationships between the various compartments of the body and viscosity factors. Blood and plasma viscosity were measured with the Anton Paar rheometer and analyzed with Quemada's model. The parameters better correlated to hematocrit are fat free mass (r = 0.562) and its two components muscle mass (r = 0.516) and non-muscular fat-free mass (r = 0.452), and also trunk fat mass (r = 0.383) and waist-to hip ratio (r = 0.394). Red cell aggregation measurements were correlated with both truncal and appendicular fat mass (r ranging between 0.603 and 0.728). Weaker correlations of M and M1 are found with waist circumference and hip circumference. This study shows that the correlation between lean mass and hematocrit involves both muscle and non-muscle moieties of lean mass, and that both central and appendicular fat are determinants of red cell aggregation.

Assessing the mediating role of iron status on associations between an industry-relevant metal mixture and verbal learning and memory in Italian adolescents

BACKGROUND

Metals, including lead (Pb), manganese (Mn), chromium (Cr) and copper (Cu), have been associated with neurodevelopment; iron (Fe) plays a role in the metabolism and neurotoxicity of metals, suggesting Fe may mediate metal-neurodevelopment associations. However, no study to date has examined Fe as a mediator of the association between metal mixtures and neurodevelopment.

OBJECTIVE

We assessed Fe status as a mediator of a mixture of Pb, Mn, Cr and Cu in relation to verbal learning and memory in a cohort of Italian adolescents.

METHODS

We used cross-sectional data from 383 adolescents (10-14 years) in the Public Health Impact of Metals Exposure Study. Metals were quantified in blood (Pb) or hair (Mn, Cr, Cu) using ICP-MS, and three markers of Fe status (blood hemoglobin, serum ferritin and transferrin) were quantified using luminescence assays or immunoassays. Verbal learning and memory were assessed using the California Verbal Learning Test for Children (CVLT-C). We used Bayesian Kernel Machine Regression Causal Mediation Analysis to estimate four mediation effects: the natural direct effect (NDE), natural indirect effect (NIE), controlled direct effect (CDE) and total effect (TE). Beta (β) coefficients and 95 % credible intervals (CIs) were estimated for all effects.

RESULTS

The metal mixture was jointly associated with a greater number of words recalled on the CVLT-C, but these associations were not mediated by Fe status. For example, when ferritin was considered as the mediator, the NIE for long delay free recall was null (β = 0.00; 95 % CI = -0.22, 0.23). Conversely, the NDE (β = 0.23; 95 % CI = 0.01, 0.44) indicated a beneficial association of the mixture with recall that operated independently of Fe status.

CONCLUSION

An industry-relevant metal mixture was associated with learning and memory, but there was no evidence of mediation by Fe status. Further studies in populations with Fe deficiency and greater variation in metal exposure are warranted.

Whispers in the Blood: Leveraging MicroRNAs for Unveiling Autologous Blood Doping in Athletes

The prevalence of autologous blood transfusions (ABTs) presents a formidable challenge in maintaining fair competition in sports, as it significantly enhances hemoglobin mass and oxygen capacity. In recognizing ABT as a prohibited form of doping, the World Anti-Doping Agency (WADA) mandates stringent detection methodologies. While current methods effectively identify homologous erythrocyte transfusions, a critical gap persists in detecting autologous transfusions. The gold standard practice of longitudinally monitoring hematological markers exhibits promise but is encumbered by limitations. Despite its potential, instances of blood doping often go undetected due to the absence of definitive verification processes. Moreover, some cases remain unpenalized due to conservative athlete-sanctioning approaches. This gap underscores the imperative need for a more reliable and comprehensive detection method capable of unequivocally differentiating autologous transfusions, addressing the challenges faced in accurately identifying such prohibited practices. The development of an advanced detection methodology is crucial to uphold the integrity of anti-doping measures, effectively identifying and penalizing instances of autologous blood transfusion. This, in turn, safeguards the fairness and equality essential to competitive sports. Our review tackles this critical gap by harnessing the potential of microRNAs in ABT doping detection. We aim to summarize alterations in the total microRNA profiles of erythrocyte concentrates during storage and explore the viability of observing these changes post-transfusion. This innovative approach opens avenues for anti-doping technologies and commercialization, positioning it as a cornerstone in the ongoing fight against doping in sports and beyond. The significance of developing a robust detection method cannot be overstated, as it ensures the credibility of anti-doping efforts and promotes a level playing field for all athletes.

[Related factors of endogenous erythropoietin and its association with 10-year risks of cardiovascular disease in a community-based Chinese study]

OBJECTIVE

To investigate the associated factors of endogenous erythropoietin (EPO) and its association with 10-year risks of atherosclerotic cardiovascular disease in a Chinese community-based general population.

METHODS

The participants of this study were from an atherosclerosis cohort survey which was established by the Department of Cardiology, Peking University First Hospital in 2011. The cohort survey was performed in the Gucheng and Pingguoyuan communities of Shijingshan district in Beijing, China. The inclusion criteria of this study were: (1) endogenous EPO was measured; (2) health questionnaire data and other clinical data were complete; (3) participatants who had cardiovascular or cerebrovascular diseases (defined as self-reported coronary heart disease, stroke or transient ischemic attack) or anemia or estimated glomerular filtration rate (eGFR) < 60 mL/(min·1.73 m2) at baseline were excluded. Multivariate linear regression model was used to examine the associated factors of endogenous EPO. The participants were grouped into low (< 5%), moderate (5%-10%) and high risk (≥10%) groups, based on predicted 10-year cardiovascular disease risk using the prediction for atherosclerotic cardiovascular disease risk in China (China-PAR) equations.

RESULTS

A total of 4 013 participants were included. Mean age of them was (55.9±8.2) years, 62.2% (n=2 496) of them were female, and 46.3% (n=1 859), 70.9% (n=2 845), 21.9% (n=879) had hypertension, dyslipidemia and diabetes, individually. The average body mass index was (26.1±3.3) kg/m2. The median of EPO level was 12.8 (9.3-17.4) IU/L and 25.1% (n=998) were at high 10-years risk of cardiovascular disease. Hemoglobin (β=-0.05, 95%CI: -0.07 to -0.04) and eGFR ≥90 mL/(min·1.73 m2) (β=-0.05, 95%CI: -0.07 to -0.04) were associated with lower in transformed EPO levels while hypertension (β=0.08, 95%CI: 0.05 to 0.12) and obesity (β=0.14, 95%CI: 0.09 to 0.18) were associated with higher in transformed EPO levels in multivariate linear regression analyses. Ten-year cardiovascular disease risks were positively associated with in transformed EPO levels (β=0.07, 95%CI: 0.05 to 0.09). The participants at moderate and high cardiovascular disease risks had significant higher EPO levels than the low risk group (all P < 0.05).

CONCLUSION

In community-based Beijing populations, endogenous EPO was associated with hemoglobin, renal function, obesity and hypertension. Individuals at high 10-years cardiovascular disease risks have higher endogenous EPO levels. Endogenous EPO may be a potential risk marker of cardiovascular disease.

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

Nanoengineered injectable hydrogels derived from layered double hydroxides and alginate for sustained release of protein therapeutics in tissue engineering applications

Chronic Kidney Disease (CKD) which involves gradual loss of kidney function is characterized by low levels of a glycoprotein called Erythropoietin (EPO) that leads to red blood cell  deficiency and anemia. Recombinant human EPO (rhEPO) injections that are administered intravenously or subcutaneously is the current gold standard for treating CKD. The rhEPO injections have very short half-lives and thus demands frequent administration with a risk of high endogenous EPO levels leading to severe side effects that could prove fatal. To this effect, this work provides a novel approach of using lamellar inorganic solids with a brucite-like structure for controlling the release of protein therapeutics such as rhEPO in injectable hydrogels. The nanoengineered injectable system was formulated by incorporating two-dimensional layered double hydroxide (LDH) clay materials with a high surface area into alginate hydrogels for sustained delivery. The inclusion of LDH in the hydrogel network not only improved the mechanical properties of the hydrogels (5-30 times that of alginate hydrogel) but also exhibited a high binding affinity to proteins without altering their bioactivity and conformation. Furthermore, the nanoengineered injectable hydrogels (INHs) demonstrated quick gelation, injectability, and excellent adhesion properties on human skin. The in vitro release test of EPO from conventional alginate hydrogels (Alg-Gel) showed 86% EPO release within 108 h while INHs showed greater control over the initial burst and released only 24% of EPO in the same incubation time. INH-based ink was successfully used for 3D printing, resulting in scaffolds with good shape fidelity and stability in cell culture media. Controlled release of EPO from INHs facilitated superior angiogenic potential in ovo (chick chorioallantoic membrane) compared to Alg-Gel. When subcutaneously implanted in albino mice, the INHs formed a stable gel in vivo without inducing any adverse effects. The results suggest that the proposed INHs in this study can be utilized as a minimally invasive injectable platform or as 3D printed patches for the delivery of protein therapeutics to facilitate tissue regeneration.

Erythropoietin receptor is a risk factor for prognosis: A potential biomarker in lung adenocarcinoma

Lung cancer has the highest mortality rate of all cancers, and LUAD's survival rate is particularly poor. Erythropoietin receptor (EPOR) can be detected in lung adenocarcinoma (LUAD), however, the expression levels and prognostic value of EPOR in LUAD are still unclear. In our study, clinicopathological data of 92 LUAD patients between January 2008 and June 2016, multiple bioinformatics databases and immunohistochemistry were used to explore the EPOR expression, the mutant genes affecting EPOR expression, and the correlation of EPOR expression with oxidative stress - related genes, prognosis, immune microenvironment. All statistical analyses were performed in the R version 4.1.1. The study found that EPOR expression might be down-regulated at the mRNA levels and significantly up-regulated at the protein levels in LUAD, which indicates that the mRNA and protein levels of EPOR are inconsistent. The muTarget showed that the expression of EPOR was significantly different between the mutant group and the wild group of 15 genes, including DDX60L and C1orf168. Importantly, we found that EPOR was associated with VEGF and HIF family members, and had significant positive correlation with oxidative stress - related genes such as CCS, EPX and TXNRD2. This suggests that EPOR may be involved in the regulation of oxidative stress. The Kaplan-Meier Plotter and PrognoScan databases consistently concluded that EPOR was associated with prognosis in LUAD patients. Our clinicopathological data showed that high EPOR expression was associated with poorer overall survival (29.5 vs 46 months) and had a good predictive ability for 4-year and 5-year survival probability. EPOR is expected to be a potential new prognostic marker for LUAD.

The contribution of the AT1 receptor to erythropoiesis

The renin-angiotensin system (RAS) comprises a broad set of functional peptides and receptors that play a role in cardiovascular homeostasis and contribute to cardiovascular pathologies. Angiotensin II (Ang II) is the most potent peptide hormone produced by the RAS due to its high abundance and its strong and pleiotropic impact on the cardiovascular system. Formation of Ang II takes place in the bloodstream and additionally in tissues in the so-called local RAS. Of the two Ang II receptors (AT1 and AT2) that Ang II binds to, AT1 is the most expressed throughout the mammalian body. AT1 expression is not restricted to cells of the cardiovascular system but in fact AT1 protein is found in nearly all organs, hence, Ang II takes part in several modulatory physiological processes one of which is erythropoiesis. In this review, we present multiple evidence supporting that Ang II modulates physiological and pathological erythropoiesis processes trough the AT1 receptor. Cumulative evidence indicates that Ang II by three distinct mechanisms influences erythropoiesis: 1) stimulation of renal erythropoietin synthesis; 2) direct action on bone marrow precursor cells; and 3) modulation of sympathetic nerve activity to the bone marrow. The text highlights clinical and preclinical evidence focusing on mechanistic studies using rodent models.

Mitochondrial modulation of amplified preconditioning influences of remote ischemia plus erythropoietin against skeletal muscle ischemia/reperfusion injury in rats

AIMS

Skeletal muscle ischemia and reperfusion (S-I/R) injury is relieved by interventions like remote ischemic preconditioning (RIPC). Here, we tested the hypothesis that simultaneous exposure to a minimal dose of erythropoietin (EPO) boosts the protection conferred by RIPC against S-I/R injury and concomitant mitochondrial oxidative and apoptotic defects.

MAIN METHODS

S-I/R injury was induced in rats by 3-h right hindlimb ischemia followed by 3-h of reperfusion, whereas RIPC involved 3 brief consecutive I/R cycles of the contralateral hindlimb.

KEY FINDINGS

S-I/R injury caused (i) rises in serum lactate dehydrogenase and creatine kinase and falls in serum pyruvate, (ii) structural deformities like sarcoplasm vacuolations, segmental necrosis, and inflammatory cells infiltration, and (iii) decreased amplitude and increased duration of electromyography action potentials. These defects were partially ameliorated by RIPC and dose-dependently by EPO (500 or 5000 IU/kg). Further, greater repairs of S-I/R-evoked damages were seen after prior exposure to the combined RIPC/EPO-500 intervention. The latter also caused more effective (i) preservation of mitochondrial number (confocal microscopy assessed Mitotracker red staining) and function (citrate synthase activity), (ii) suppression of mitochondrial DNA damage and indices of oxidative stress and apoptosis (succinate dehydrogenase, myeloperoxidase, cardiolipin, and cytochrome c), (iii) preventing calcium and nitric oxide metabolites (NOx) accumulation and glycogen consumption, and (iv) upregulating EPO receptors (EPO-R) gene expression.

SIGNIFICANCE

dual RIPC/EPO conditioning exceptionally mends structural, functional, and neuronal deficits caused by I/R injury and interrelated mitochondrial oxidative and apoptotic damage. Clinically, the utilization of relatively low EPO doses could minimize the hormone-related adverse effects.

Exploiting moderate hypoxia to benefit patients with brain disease: Molecular mechanisms and translational research in progress

Hypoxia is increasingly recognized as an important physiological driving force. A specific transcriptional program, induced by a decrease in oxygen (O2) availability, for example, inspiratory hypoxia at high altitude, allows cells to adapt to lower O2 and limited energy metabolism. This transcriptional program is partly controlled by and partly independent of hypoxia-inducible factors. Remarkably, this same transcriptional program is stimulated in the brain by extensive motor-cognitive exercise, leading to a relative decrease in O2 supply, compared to the acutely augmented O2 requirement. We have coined the term "functional hypoxia" for this important demand-responsive, relative reduction in O2 availability. Functional hypoxia seems to be critical for enduring adaptation to higher physiological challenge that includes substantial "brain hardware upgrade," underlying advanced performance. Hypoxia-induced erythropoietin expression in the brain likely plays a decisive role in these processes, which can be imitated by recombinant human erythropoietin treatment. This article review presents hints of how inspiratory O2 manipulations can potentially contribute to enhanced brain function. It thereby provides the ground for exploiting moderate inspiratory plus functional hypoxia to treat individuals with brain disease. Finally, it sketches a planned multistep pilot study in healthy volunteers and first patients, about to start, aiming at improved performance upon motor-cognitive training under inspiratory hypoxia.

Allostasis in Neuroendocrine Systems Controlling Reproduction

Allostasis provides a supporting role to the homeostatic control of biological variables in mammalian species. While the concept of homeostasis is related to the control of variables within a set point or range that are essential to life, allostasis refers to systems that facilitate adaptation to challenges that the organism faces and the new requirements for survival. Essential for such adaptation is the role played by the brain in eliciting neural and neuroendocrine responses. Reproductive function is fundamental for the survival of species but is costly in energetic terms and requires a synchrony with an ever-changing environment. Thus, in many species reproductive function is blocked or delayed over immediate challenges. This review will cover the physiological systems and neuroendocrine pathways that supply allostatic control over reproductive neuroendocrine systems. Light, hypoxia, temperature, nutrition, psychosocial, and immune mediators influence the neuroendocrine control of reproductive functions through pathways that are confluent at the paraventricular nucleus; however, understanding of the integrative responses to these stimuli has not been clarified. Likely, the ultimate consequence of these allostatic mechanisms is the modification of kisspeptin and gonadotropin-releasing hormone neuronal activity, thus compromising reproduction function in the short term, while preserving species survivability.

Subchronic Arsenite Exposure Induced Atrophy and Erythropoietin Sensitivity Reduction in Skeletal Muscle Were Relevant to Declined Serum Melatonin Levels in Middle-Aged Rats

Arsenic is a kind of widespread environmental toxicant with multiorgan-toxic effects, and arsenic exposure is associated with the occurrence and development of many chronic diseases. The influence of environmental arsenic exposure on skeletal muscle, which is a vital organ of energy and glucose metabolism, has received increasing attention. This study aimed to investigate the types of inorganic arsenic-induced skeletal muscle injury, and the potential regulatory effects of melatonin (MT) and erythropoietin (EPO) in young (3-month-old) and middle-aged (12-month-old) rats. Our results showed that 1 mg/L sodium arsenite exposure for 3 months could accelerate gastrocnemius muscle atrophy and promote the switch of type II fibers to type I fibers in middle-aged rats; however, it did not cause significant pathological changes of gastrocnemius muscle in young rats. In addition, arsenite could inhibit serum MT levels, and promote serum EPO levels but inhibit EPO receptor (EPOR) expression in gastrocnemius muscle in middle-aged rats, while serum MT levels and EPOR expression in gastrocnemius muscle showed an opposite effect in young rats. Importantly, exogenous MT antagonized the arsenite-induced skeletal muscle toxic effect and restored serum EPO and gastrocnemius muscle EPOR expression levels in middle-aged rats. There was a positive correlation among gastrocnemius muscle index, serum MT level, and gastrocnemius muscle EPOR protein level in arsenite-exposed rats. This study demonstrated that inorganic arsenic could accelerate skeletal muscle mass loss and type II fiber reduction in middle-aged rats, which may be related to decreased MT secretion and declined EPO sensitivity in skeletal muscle.

Clinical outcome and humoral immune responses of β-thalassemia major patients with severe iron overload to SARS-CoV-2 infection and vaccination: a prospective cohort study

BACKGROUND

COVID-19 has raised special concern for patients with β-thalassemia major (β-TM) due to frequent comorbidities, regular blood transfusions, and iron overload. However, the exact implications of COVID-19 for patients with β-TM remain uncertain. We aimed to explore the COVID-19 incidence and severity, and the serological response to SARS-CoV-2 infection and vaccination in patients with β-TM.

METHODS

Patients with β-TM (n = 105) and age-matched healthy controls, all individuals of all control groups were health care workers of the hospital, were prospectively enrolled at the haematology department of Al-Shifa hospital in the Gaza Strip from January 1st, 2021 to December 31st, 2021. Data on COVID-19 incidence and severity were analysed, with Alpha, Beta, and Delta SARS-CoV-2 variants dominating at that time. Anti-SARS-CoV-2 IgG antibody levels were measured and compared between study groups.

FINDINGS

Patients with β-TM showed a higher incidence of SARS-CoV-2 infection than the general population (61.9% vs. 7.1%, p < 0.0001). Most patients with β-TM had asymptomatic (70.8%) or mild disease (26.1%), with no fatalities recorded. COVID-19 illness was more severe among female than male patients with β-TM. Anti-SARS-CoV-2 IgG antibodies were significantly higher in symptomatic patients with β-TM than controls post-infection (geometric mean ÷ geometric standard deviation 1299.0 ÷ 3.3 vs. 555.7 ÷ 2.4 AU/mL, p = 0.009) and post-vaccination (8404.0 ÷ 3.9 vs. 2785.6 ÷ 5.0 AU/mL, p = 0.015). Similar responses were observed when comparing splenectomised to non-splenectomised (both asymptomatic and symptomatic) patients with β-TM post-infection (595.4 ÷ 3.9 vs. 280.7 ÷ 3.5 AU/mL, p = 0.005) and post-vaccination (13,778.2 ÷ 3.2 vs. 4961.8 ÷ 4.1 AU/mL, p = 0.045).

INTERPRETATION

This distinctive β-TM cohort exhibited a high susceptibility to SARS-CoV-2 infection but mild disease course. Our findings support favourable serological responses to SARS-CoV-2 infection and to vaccination in patients with β-TM, indicating a potential interplay between iron availability and COVID-19-related immunity.

FUNDING

This study was funded by Mr. Hosam and Wasim s. El Helou.

A retrospective view of the relationship of soluble Fas with anemia and outcomes in chronic kidney disease

BACKGROUND

Anemia is common in chronic kidney disease (CKD) and is associated with outcomes. In addition, serum soluble Fas (sFas) levels are related to anemia and erythropoietin (EPO) resistance.

OBJECTIVES

Firstly, to compare clinical data and serum levels of sFas, EPO, and pro-inflammatory markers between patients with non-dialytic CKD (NDD-CKD) and healthy subjects. Subsequently, to compare and evaluate the relationship of serum EPO, sFas levels with anemia, and outcomes in patients with NDD-CKD over a long follow-up period.

METHODS

We performed a retrospective study in 58 NDD-CKD patients compared with 20 healthy subjects on complete blood count, kidney function, serum EPO, sFas, and inflammatory markers (CRP, IL- 6, and IFN-γ) at baseline. We then compared the same baseline data between patients with NDD-CKD who evolved to anemia and those who did not have anemia over the follow-up. We also evaluated the frequency of outcomes in patients with CKD with higher sFas levels. Finally, we performed a multivariate analysis of factors associated with CKD anemia.

RESULTS

There were lower eGFR and Hb but higher serum inflammatory markers, sFas levels, sFas/eGFR, and EPO/Hb ratios in patients with NDD-CKD. Comparatively, on the other hand, NDD-CKD patients with anemia had lower eGFR but were older, had more diabetes, and had higher sFas/ eGFR, EPO/Hb ratios, and serum levels of IL-6 and sFas than NDD-CKD without anemia for an extended period. In addition, there was an association in a multivariate analysis of diabetes, age, and sFas levels with kidney anemia. Furthermore, there were higher frequencies of outcomes in increased serum sFas levels.

CONCLUSION

As an elective risk factor, serum sFas levels, in addition to age and diabetes, were independently associated with kidney anemia for an extended period. Thus, more studies are necessary to analyze the proper relationship of sFas with kidney anemia and its outcomes and therapy in CKD.

Exogenous ketosis elevates circulating erythropoietin and stimulates muscular angiogenesis during endurance training overload

De novo capillarization is a primary muscular adaptation to endurance exercise training and is crucial to improving performance. Excess training load, however, impedes such beneficial adaptations, yet we recently demonstrated that such downregulation may be counteracted by ketone ester ingestion (KE) post-exercise. Therefore, we investigated whether KE could increase pro-angiogenic factors and thereby stimulate muscular angiogenesis during a 3-week endurance training-overload period involving 10 training sessions/week in healthy, male volunteers. Subjects received either 25 g of a ketone ester (KE, n = 9) or a control drink (CON, n = 9) immediately after each training session and before sleep. In KE, but not in CON, the training intervention increased the number of capillary contacts and the capillary-to-fibre perimeter exchange index by 44% and 42%, respectively. Furthermore, KE also substantially increased vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) expression both at the protein and at the mRNA level. Serum erythropoietin concentration was concomitantly increased by 26%. Conversely, in CON the training intervention increased only the protein content of eNOS. These data indicate that intermittent exogenous ketosis during endurance overload training stimulates muscular angiogenesis. This likely resulted from a direct stimulation of muscle angiogenesis, which may be at least partly due to stimulation of erythropoietin secretion and elevated VEGF activity, and/or an inhibition of the suppressive effect of overload training on the normal angiogenic response to training. This study provides novel evidence to support the potential of exogenous ketosis to benefit endurance training-induced muscular adaptation. KEY POINTS: Increased capillarization is a primary muscular adaptation to endurance exercise training. However, excess training load may impede such response. We previously observed that intermittent exogenous ketosis by post-exercise and pre-sleep ketone ester ingestion (KE) counteracted physiological dysregulations induced by endurance overload training. Therefore, we investigated whether KE could increase pro-angiogenic factors thereby stimulating muscular angiogenesis during a 3-week endurance training overload period. We show that the overload training period in the presence, but not in the absence, of KE markedly increased muscle capillarization (+40%). This increase was accompanied by higher circulating erythropoietin concentration and stimulation of the pro-angiogenic factors vascular endothelial growth factor and endothelial nitric oxide synthase in skeletal muscle. Collectively, our data indicate that intermittent exogenous ketosis may evolve as a potent nutritional strategy to facilitate recovery from strenuous endurance exercise, thereby stimulating beneficial muscular adaptations.

A critical role for erythropoietin on vagus nerve Schwann cells in intestinal motility

BACKGROUND

Dysmotility and postoperative ileus (POI) are frequent major clinical problems post-abdominal surgery. Erythropoietin (EPO) is a multifunctional tissue-protective cytokine that promotes recovery of the intestine in various injury models. While EPO receptors (EPOR) are present in vagal Schwann cells, the role of EPOR in POI recovery is unknown because of the lack of EPOR antagonists or Schwann-cell specific EPOR knockout animals. This study was designed to explore the effect of EPO via EPOR in vagal nerve Schwann cells in a mouse model of POI.

RESULTS

The structural features of EPOR and its activation by EPO-mediated dimerization were understood using structural analysis. Later, using the Cre-loxP system, we developed a myelin protein zero (Mpz) promoter-driven knockout mouse model of Schwann cell EPOR (MpzCre-EPOR^flox/flox / Mpz-EPOR-KO) confirmed using PCR and qRT-PCR techniques. We then measured the intestinal transit time (ITT) at baseline and after induction of POI with and without EPO treatment. Although we have previously shown that EPO accelerates functional recovery in POI in wild type mice, EPO treatment did not improve functional recovery of ITT in POI of Mpz-EPOR-KO mice.

CONCLUSIONS

To the best of our knowledge, this is the first pre-clinical study to demonstrate a novel mouse model of EPOR specific knock out on Schwan cells with an effect in the gut. We also showed novel beneficial effects of EPO through vagus nerve Schwann cell-EPOR in intestinal dysmotility. Our findings suggest that EPO-EPOR signaling in the vagus nerve after POI is important for the functional recovery of ITT.

The transcriptional and regulatory identity of erythropoietin producing cells

Erythropoietin (Epo) is the master regulator of erythropoiesis and oxygen homeostasis. Despite its physiological importance, the molecular and genomic contexts of the cells responsible for renal Epo production remain unclear, limiting more-effective therapies for anemia. Here, we performed single-cell RNA and transposase-accessible chromatin (ATAC) sequencing of an Epo reporter mouse to molecularly identify Epo-producing cells under hypoxic conditions. Our data indicate that a distinct population of kidney stroma, which we term Norn cells, is the major source of endocrine Epo production in mice. We use these datasets to identify the markers, signaling pathways and transcriptional circuits characteristic of Norn cells. Using single-cell RNA sequencing and RNA in situ hybridization in human kidney tissues, we further provide evidence that this cell population is conserved in humans. These preliminary findings open new avenues to functionally dissect EPO gene regulation in health and disease and may serve as groundwork to improve erythropoiesis-stimulating therapies.

Physiologic considerations of pig-to-human kidney xenotransplantation

PURPOSE OF REVIEW

The greatest challenge facing end-stage kidney disease (ESKD) patients is the scarcity of transplantable organs. Advances in genetic engineering that mitigate xenogeneic immune responses have made transplantation across species a potentially viable solution to this unmet need. Preclinical studies and recent reports of pig-to-human decedent renal xenotransplantation signify that clinical trials are on the horizon. Here, we review the physiologic differences between porcine and human kidneys that could impede xenograft survival. Topics addressed include porcine renin and sodium handling, xenograft water handling, calcium, phosphate and acid-base balance, responses to porcine erythropoietin and xenograft growth.

RECENT FINDINGS

Studies in nonhuman primates (NHPs) have demonstrated that genetically modified pig kidneys can survive for an extended period when transplanted into baboons. In recent studies conducted by our group and others, hyperacute rejection did not occur in pig kidneys lacking the α1,3Gal epitope transplanted into brain-dead human recipients. These experimental trials did not study potential clinical abnormalities arising from idiosyncratic xenograft responses to human physiologic stimuli due to the brief duration of observation this model entails.

SUMMARY

Progress in biotechnology is heralding an era of xenotransplantation. We highlight the physiologic considerations for xenogeneic grafts to succeed.

Beauty and the beast: host microRNA-155 versus SARS-CoV-2

Severe acute respiratory coronavirus 2 (SARS-CoV-2) infection in the young and healthy usually results in an asymptomatic or mild viral syndrome, possibly through an erythropoietin (EPO)-dependent, protective evolutionary landscape. In the old and in the presence of co-morbidities, however, a potentially lethal coronavirus disease 2019 (COVID-19) cytokine storm, through unrestrained renin-angiotensin aldosterone system (RAAS) hyperactivity, has been described. Multifunctional microRNA-155 (miR-155) elevation in malaria, dengue virus (DENV), the thalassemias, and SARS-CoV-1/2, plays critical antiviral and cardiovascular roles through its targeted translational repression of over 140 genes. In the present review, we propose a plausible miR-155-dependent mechanism whereby the translational repression of AGRT1, Arginase-2 and Ets-1, reshapes RAAS towards Angiotensin II (Ang II) type 2 (AT2R)-mediated balanced, tolerable, and SARS-CoV-2-protective cardiovascular phenotypes. In addition, it enhances EPO secretion and endothelial nitric oxide synthase activation and substrate availability, and negates proinflammatory Ang II effects. Disrupted miR-155 repression of AT1R + 1166C-allele, significantly associated with adverse cardiovascular and COVID-19 outcomes, manifests its decisive role in RAAS modulation. BACH1 and SOCS1 repression creates an anti-inflammatory and cytoprotective milieu, robustly inducing antiviral interferons. MiR-155 dysregulation in the elderly, and in comorbidities, allows unimpeded RAAS hyperactivity to progress towards a particularly aggressive COVID-19 course. Elevated miR-155 in thalassemia plausibly engenders a favorable cardiovascular profile and protection against malaria, DENV, and SARS-CoV-2. MiR-155 modulating pharmaceutical approaches could offer novel therapeutic options in COVID-19.

Controls of Central and Peripheral Blood Pressure and Hemorrhagic/Hypovolemic Shock

The pressure exerted on the heart and blood vessels because of blood flow is considered an essential parameter for cardiovascular function. It determines sufficient blood perfusion, and transportation of nutrition, oxygen, and other essential factors to every organ. Pressure in the primary arteries near the heart and the brain is known as central blood pressure (CBP), while that in the peripheral arteries is known as peripheral blood pressure (PBP). Usually, CBP and PBP are correlated; however, various types of shocks and cardiovascular disorders interfere with their regulation and differently affect the blood flow in vital and accessory organs. Therefore, understanding blood pressure in normal and disease conditions is essential for managing shock-related cardiovascular implications and improving treatment outcomes. In this review, we have described the control systems (neural, hormonal, osmotic, and cellular) of blood pressure and their regulation in hemorrhagic/hypovolemic shock using centhaquine (Lyfaquin^®) as a resuscitative agent.

Effect of pentavalent inorganic arsenic salt on erythropoietin production and autophagy induction

Arsenic is abundant in the environment and takes the form of trivalent and pentavalent arsenic compounds. Arsenite has been reported to both promote and suppress erythropoietin (EPO) production and autophagy induction. EPO production is involved in hematopoiesis, and autophagy induction is involved in cytoprotection, both of which are thought to be cellular responses to arsenic stress. While there are reports that show the effects of EPO on autophagy induction, the relationship between EPO production and autophagy induction is unclear. Therefore, this study analyzed the effect of the pentavalent inorganic arsenic salt arsenate on EPO production in vitro and in vivo and EPO-induced autophagy in HepG2 cells. Exposure of HepG2 cells to low-concentration arsenate was observed to increase EPO production and induced autophagy. Moreover, a ROS scavenger suppressed the arsenate-induced increase in autophagy and EPO mRNA levels. Both EPO production and autophagy induction contributed to protection from arsenate-induced cytotoxic stress. HepG2 cells expressed the EPO receptor and production of EPO by HepG2 cells acted in an autoregulatory manner to suppress autophagy induction. In vivo administration of low-concentration arsenate to rats increased EPO mRNA levels in the liver and kidney. These results suggested that low-concentration arsenate promotes EPO production and autophagy induction in HepG2 cells, and the resultant EPO production contributes to cytoprotection of cultured cells via EPO receptor activation.

Repurposing existing products to accelerate injury recovery (REPAIR) of military relevant musculoskeletal conditions

Musculoskeletal injuries (MSKIs) are a great hindrance to the readiness of the United States Armed Forces through lost duty time and reduced operational capabilities. While most musculoskeletal injuries result in return-to-duty/activity with no (functional) limitations, the healing process is often long. Long healing times coupled with the high frequency of musculoskeletal injuries make them a primary cause of lost/limited duty days. Thus, there exists an urgent, clinically unmet need for interventions to expedite tissue healing kinetics following musculoskeletal injuries to lessen their impact on military readiness and society as a whole. There exist several treatments with regulatory approval for other indications that have pro-regenerative/healing properties, but few have an approved indication for treating musculoskeletal injuries. With the immediate need for treatment options for musculoskeletal injuries, we propose a paradigm of Repurposing Existing Products to Accelerate Injury Recovery (REPAIR). Developing treatments via repurposing existing therapeutics for other indications has shown monumental advantages in both cost effectiveness and reduced time to bring to market compared to novel candidates. Thus, undertaking the needed research efforts to evaluate the effectiveness of promising REPAIR-themed candidates has the potential to enable near-term solutions for optimizing musculoskeletal injuries recovery, thereby addressing a top priority within the United States. Armed Forces. Herein, the REPAIR paradigm is presented, including example targets of opportunity as well as practical considerations for potential technical solutions for the translation of existing therapeutics into clinical practice for musculoskeletal injuries.

Neuronal nitric oxide synthase is required for erythropoietin stimulated erythropoiesis in mice

Introduction: Erythropoietin (EPO), produced in the kidney in a hypoxia responsive manner, is required for red blood cell production. In non-erythroid tissue, EPO increases endothelial cell production of nitric oxide (NO) and endothelial nitric oxide synthase (eNOS) that regulates vascular tone to improve oxygen delivery. This contributes to EPO cardioprotective activity in mouse models. Nitric oxide treatment in mice shifts hematopoiesis toward the erythroid lineage, increases red blood cell production and total hemoglobin. In erythroid cells, nitric oxide can also be generated by hydroxyurea metabolism that may contribute to hydroxyurea induction of fetal hemoglobin. We find that during erythroid differentiation, EPO induces neuronal nitric oxide synthase (nNOS) and that neuronal nitric oxide synthase is required for normal erythropoietic response. Methods: Wild type (WT) mice and mice with targeted deletion of nNOS (nNOS-/-) and eNOS (eNOS-/-) were assessed for EPO stimulated erythropoietic response. Bone marrow erythropoietic activity was assessed in culture by EPO dependent erythroid colony assay and in vivo by bone marrow transplantation into recipient WT mice. Contribution of nNOS to EPO stimulated cell proliferation was assessed in EPO dependent erythroid cells and in primary human erythroid progenitor cell cultures. Results: EPO treatment increased hematocrit similarly in WT and eNOS-/- mice and showed a lower increase in hematocrit nNOS-/- mice. Erythroid colony assays from bone marrow cells were comparable in number from wild type, eNOS-/- and nNOS-/- mice at low EPO concentration. Colony number increased at high EPO concentration is seen only in cultures from bone marrow cells of wild type and eNOS-/- mice but not from nNOS-/- mice. Colony size with high EPO treatment also exhibited a marked increase in erythroid cultures from wild type and eNOS-/- mice but not from nNOS-/- mice. Bone marrow transplant from nNOS-/- mice into immunodeficient mice showed engraftment at comparable levels to WT bone marrow transplant. With EPO treatment, the increase in hematocrit was blunted in recipient mice that received with nNOS-/- donor marrow compared with recipient mice that received WT donor marrow. In erythroid cell cultures, addition of nNOS inhibitor resulted in decreased EPO dependent proliferation mediated in part by decreased EPO receptor expression, and decreased proliferation of hemin induced differentiating erythroid cells. Discussion: EPO treatment in mice and in corresponding cultures of bone marrow erythropoiesis suggest an intrinsic defect in erythropoietic response of nNOS-/- mice to high EPO stimulation. Transplantation of bone marrow from donor WT or nNOS-/- mice into recipient WT mice showed that EPO treatment post-transplant recapitulated the response of donor mice. Culture studies suggest nNOS regulation of EPO dependent erythroid cell proliferation, expression of EPO receptor and cell cycle associated genes, and AKT activation. These data provide evidence that nitric oxide modulates EPO dose dependent erythropoietic response.

Low-Dose Erythropoietin Amplifies Beneficial Effects of Angiotensin II Blockade on Glomerulosclerosis

Exogenous erythropoietin (EPO) is used to treat anemia in patients with chronic kidney disease (CKD). Concerns about the possible adverse effect of EPO on the progression of CKD have been raised owing to nonerythroid cell effects. We investigated the effects of low-dose EPO, independent of correcting anemia, on existing glomerulosclerosis. Adult mice underwent 5/6 nephrectomy and were randomized into the following 4 groups at week 8 after surgery: vehicle (VEH), losartan (angiotensin II type 1 receptor blocker [ARB]), darbepoetin-α (DA), or combination (DA+ARB). Four weeks later, mice were euthanized, followed by evaluation of renal structure and function. Glomerular endothelial cells and podocytes were cultured to evaluate the effects of DA on cell migration, apoptosis, and Akt signaling. ARB reduced blood pressure, albuminuria, and the level of serum creatinine and increased hematocrit compared with VEH, whereas low-dose DA only reduced the level of serum creatinine. Combination treatment showed a trend to increase hematocrit and survival compared with ARB alone. Combination treatment but not ARB alone significantly reduced the progression of glomerulosclerosis compared with VEH. Low-dose DA resulted in more preserved glomerular and peritubular capillary endothelial cells with increased p-Akt and even further endothelial cell preservation in combination with ARB. In cultured glomerular endothelial cells, angiotensin II induced more apoptosis, reduced migration, and decreased p-Flk1, a receptor for the proangiogenic vascular endothelial growth factor. DA counteracted these injuries and increased p-Akt, a key factor in angiogenesis and cell survival. DA also protected cultured podocytes against transforming growth factor β-induced apoptosis and synaptopodin loss. Low-dose EPO directly protects glomerular and peritubular endothelial cells via Akt phosphorylation. Therefore, treatment using a combination of low-dose EPO and ARB results in less progression of glomerulosclerosis in an experimental CKD model.

A protective erythropoietin evolutionary landscape, NLRP3 inflammasome regulation, and multisystem inflammatory syndrome in children

The low incidence of pediatric severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and the associated multisystem inflammatory syndrome (MIS-C) lack a unifying pathophysiological explanation, impeding effective prevention and therapy. Activation of the NACHT, LRR, and PYD domains-containing protein (NLRP) 3 inflammasome in SARS-CoV-2 with perturbed regulation in MIS-C, has been reported. We posit that, early age physiological states and genetic determinants, such as certain polymorphisms of renin-angiotensin aldosterone system (RAAS) molecules, promote a controlled RAAS hyperactive state, and form an evolutionary landscape involving an age-dependent erythropoietin (EPO) elevation, mediating ancestral innate immune defenses that, through appropriate NLRP3 regulation, mitigate tissue injury and pathogen invasion. SARS-CoV-2-induced downregulation of angiotensin-converting enzyme (ACE)2 expression in endothelial cells (EC), impairment of endothelial nitric oxide (NO) synthase (eNOS) activity and downstream NO bioavailability, may promote a hyperactive RAAS with elevated angiotensin II and aldosterone that, can trigger, and accelerate NLRP3 inflammasome activation, while EPO-eNOS/NO abrogate it. Young age and a protective EPO evolutionary landscape may successfully inhibit SARS-CoV-2 and contain NLRP3 inflammasome activation. By contrast, increasing age and falling EPO levels, in genetically susceptible children with adverse genetic variants and co-morbidities, may lead to unopposed RAAS hyperactivity, NLRP3 inflammasome dysregulation, severe endotheliitis with pyroptotic cytokine storm, and development of autoantibodies, as already described in MIS-C. Our haplotype estimates, predicted from allele frequencies in population databases, are in concordance with MIS-C incidence reports in Europeans but indicate lower risks for Asians and African Americans. Targeted Mendelian approaches dissecting the influence of relevant genetic variants are needed.

SARS-CoV-2 Infection Dysregulates Host Iron (Fe)-Redox Homeostasis (Fe-R-H): Role of Fe-Redox Regulators, Ferroptosis Inhibitors, Anticoagulants, and Iron-Chelators in COVID-19 Control

Severe imbalance in iron metabolism among SARS-CoV-2 infected patients is prominent in every symptomatic (mild, moderate to severe) clinical phase of COVID-19. Phase-I - Hypoxia correlates with reduced O₂ transport by erythrocytes, overexpression of HIF-1α, altered mitochondrial bioenergetics with host metabolic reprogramming (HMR). Phase-II - Hyperferritinemia results from an increased iron overload, which triggers a fulminant proinflammatory response - the acute cytokine release syndrome (CRS). Elevated cytokine levels (i.e. IL6, TNFα and CRP) strongly correlates with altered ferritin/TF ratios in COVID-19 patients. Phase-III - Thromboembolism is consequential to erythrocyte dysfunction with heme release, increased prothrombin time and elevated D-dimers, cumulatively linked to severe coagulopathies with life-threatening outcomes such as ARDS, and multi-organ failure. Taken together, Fe-R-H dysregulation is implicated in every symptomatic phase of COVID-19. Fe-R-H regulators such as lactoferrin (LF), hemoxygenase-1 (HO-1), erythropoietin (EPO) and hepcidin modulators are innate bio-replenishments that sequester iron, neutralize iron-mediated free radicals, reduce oxidative stress, and improve host defense by optimizing iron metabolism. Due to its pivotal role in 'cytokine storm', ferroptosis is a potential intervention target. Ferroptosis inhibitors such as ferrostatin-1, liproxstatin-1, quercetin, and melatonin could prevent mitochondrial lipid peroxidation, up-regulate antioxidant/GSH levels and abrogate iron overload-induced apoptosis through activation of Nrf2 and HO-1 signaling pathways. Iron chelators such as heparin, deferoxamine, caffeic acid, curcumin, α-lipoic acid, and phytic acid could protect against ferroptosis and restore mitochondrial function, iron-redox potential, and rebalance Fe-R-H status. Therefore, Fe-R-H restoration is a host biomarker-driven potential combat strategy for an effective clinical and post-recovery management of COVID-19.

Differential miRNA expression profiles in the bone marrow of Beagle dogs at different stages of Toxocara canis infection

BACKGROUND

Toxocara canis is distributed worldwide, posing a serious threat to both human and dog health; however, the pathogenesis of T. canis infection in dogs remains unclear. In this study, the changes in microRNA (miRNA) expression profiles in the bone marrow of Beagle dogs were investigated by RNA-seq and bioinformatics analysis.

RESULTS

Thirty-nine differentially expressed (DE) miRNAs (DEmiRNAs) were identified in this study. Among these, four DEmiRNAs were identified at 24 h post-infection (hpi) and all were up-regulated; eight DEmiRNAs were identified with two up-regulated miRNAs and six down-regulated miRNAs at 96 hpi; 27 DEmiRNAs were identified with 13 up-regulated miRNAs and 14 down-regulated miRNAs at 36 days post-infection (dpi). Among these DEmiRNAs, cfa-miR-193b participates in the immune response by regulating the target gene cd22 at 24 hpi. The novel_328 could participate in the inflammatory and immune responses through regulating the target genes tgfb1 and tespa1, enhancing the immune response of the host and inhibiting the infection of T. canis at 96 hpi. In addition, cfa-miR-331 and novel_129 were associated with immune response and self-protection mechanisms at 36 dpi. 20 pathways were significantly enriched by KEGG pathway analysis, most of which were related to inflammatory response, immune response and cell differentiation, such as Cell adhesion molecules (CAMs), ECM-receptor interaction and Focal adhesion.

CONCLUSIONS

These findings suggested that miRNAs of Beagle dog bone marrow play important roles in the pathogenesis of T. canis infection in dogs and provided useful resources to better understand the interaction between T. canis and the hosts.

Silk Fibroin/Collagen/Hydroxyapatite Scaffolds Obtained by 3D Printing Technology and Loaded with Recombinant Human Erythropoietin in the Reconstruction of Alveolar Bone Defects

The fast osteogenesis of the large alveolar fossa and the maintenance of the height of the alveolar ridge after tooth extraction have always been a clinical challenge. Therefore, this work describes the creation of innovative silk fibroin/collagen/hydroxyapatite (SCH) biological scaffolds by 3D printing technology, which are loaded with recombinant human erythropoietin (rh-EPO) for the reconstruction of bone defects. Low-temperature 3D printing can maintain the biological activity of silk fibroin and collagen. The SCH scaffolds showed the ideal water absorption and porosity, being a sustained-release carrier of rh-EPO. The optimized scaffolds had ideal mechanical properties in vitro, and MC3T3-E1 cells could easily adhere and proliferate on it. In vivo experiments in rabbits demonstrated that the composite scaffolds gradually degraded and promoted the accumulation and proliferation of osteoblasts and the formation of collagen fibers, significantly promoting the reconstruction of mandibular defects. In this study, a novel composite biological scaffold was prepared using 3D printing technology, and the scaffold was innovatively combined with the multifunctional growth factor rh-EPO. This provides a new optimized composite material for the reconstruction of irregular mandible defects, and this biomaterial is promising for clinical reconstruction of alveolar bone defects.

Responsiveness to an erythropoiesis-stimulating agent is correlated with body composition in patients undergoing chronic hemodialysis

BACKGROUND

Resistance to erythropoiesis-stimulating agents (ESA) is associated with adverse outcomes in patients undergoing chronic hemodialysis. However, the impact of body composition on ESA response remains uncertain. This study retrospectively investigated whether there is an association between the ESA resistance index (ERI) and body composition in patients undergoing chronic hemodialysis.

METHODS

Multifrequency bioelectrical impedance analysis was used to measure body composition every six months. The ERI was calculated by dividing the weekly body weight-adjusted erythropoietin dose by the hemoglobin concentration. The ERI values were recorded every three months.

RESULTS

A total of 123 patients were followed up for 24 (interquartile range 5, 75) months. The ERI was negatively correlated with body mass index, arm circumference, arm muscle circumference, body fat percentage, and visceral fat area (P = 0.057, 0.001, 0.017, 0.063, and 0.041, respectively). Patients with a higher mean ERI during the study period had an increased risk of all-cause mortality, cardiovascular events, and infection requiring hospitalization than those with a lower mean ERI (P = 0.027, 0.021, and 0.037, respectively). We also evaluated the association between the slope of body composition parameters and the ERI trend over time and found that the ERI increased over time in patients who had an increased ratio of extracellular water to total body water (P = 0.002) as well as decreased arm circumference, arm muscle circumference, visceral fat area, and phase angle (P = 0.001, P < 0.001, P = 0.036, and 0.002).

CONCLUSION

ESA responsiveness appears to be associated with body composition in patients undergoing chronic hemodialysis. Therefore, measures improving body composition, such as nutrition and exercise, may have a favorable effect on the response to ESA.

Signaling Pathways Regulating Human Cervical Ripening in Preterm and Term Delivery

At the end of gestation, the cervical tissue changes profoundly. As a result of these changes, the uterine cervix becomes soft and vulnerable to dilation. The process occurring in the cervical tissue can be described as cervical ripening. The ripening is a process derivative of enzymatic breakdown and inflammatory response. Therefore, it is apparent that cervical remodeling is a derivative of the reactions mediated by multiple factors such as hormones, prostaglandins, nitric oxide, and inflammatory cytokines. However, despite the research carried out over the years, the cellular pathways responsible for regulating this process are still poorly understood. A comprehensive understanding of the entire process of cervical ripening seems crucial in the context of labor induction. Greater knowledge could provide us with the means to help women who suffer from dysfunctional labor. The overall objective of this review is to present the current understanding of cervical ripening in terms of molecular regulation and cell signaling.

Assessment of Serum Hypoxia Biomarkers Pre- and Post-radiotherapy in Patients with Brain Tumors

Hypoxia is a prevalent hallmark of many malignant neoplasms. The aim was to assess the serum hypoxia biomarkers HIF-1α, VEGF, osteopontin, erythropoietin, caveolin-1, GLUT-1, and LDH pre- and post-radiotherapy in patients with brain tumors. The study was conducted on 120 subjects were divided into two groups: group I: 40 healthy volunteers as control group. Group II: 80 brain tumor patients were subdivided into glioblastoma subgroup: 40 glioblastoma patients, meningioma subgroup: 40 malignant meningioma patients. Two venous blood samples were collected from every patient prior to and following RT and one sample from controls. Biomarkers were assayed by ELISA. In glioblastoma subgroup, HIF-1α, VEGF, and LDH were significantly increased after RT. On the contrary, these biomarkers were significantly decreased after RT in malignant meningioma subgroup. Osteopontin was significantly increased after RT in both subgroups. Regarding erythropoietin, it was significantly decreased in both subgroups when compared to before RT. Caveolin-1 showed a significant increase in glioblastoma subgroup after RT comparing to before RT. GLUT-1 was significantly increased after RT in both subgroups comparing to before RT. Association of significant elevation of hypoxia biomarkers either pre- or post-RT with aggressive tumor such as glioblastoma indicates that, they are markers of malignancy and may have a role in tumor development and progression.

A methodology for classifying tissue-specific metabolic and inflammatory receptor functions applied to subcutaneous and visceral adipose

To achieve homeostasis, the human biological system relies on the interaction between organs through the binding of ligands secreted from source organs to receptors located on destination organs. Currently, the changing roles that receptors perform in tissues are only partially understood. Recently, a methodology based on receptor co-expression patterns to classify their tissue-specific metabolic functions was suggested. Here we present an advanced framework to predict an additional class of inflammatory receptors that use a feature space of biological pathway enrichment analysis scores of co-expression networks and their eigengene correlations. These are fed into three machine learning classifiers-eXtreme Gradient Boosting (XGBoost), Support Vector Machines (SVM), and K-Nearest Neighbors (k-NN). We applied our methodology to subcutaneous and visceral adipose gene expression datasets derived from the GTEx (Genotype-Tissue Expression) project and compared the predictions. The XGBoost model demonstrated the best performance in predicting the pre-labeled receptors, with an accuracy of 0.89/0.8 in subcutaneous/visceral adipose. We analyzed ~700 receptors to predict eight new metabolic and 15 new inflammatory functions of receptors and four new metabolic functions for known inflammatory receptors in both adipose tissues. We cross-referenced multiple predictions using the published literature. Our results establish a picture of the changing functions of receptors for two adipose tissues that can be beneficial for drug development.

Erythropoietin Receptor (EPOR) Signaling in the Osteoclast Lineage Contributes to EPO-Induced Bone Loss in Mice

Erythropoietin (EPO) is a pleiotropic cytokine that classically drives erythropoiesis but can also induce bone loss by decreasing bone formation and increasing resorption. Deletion of the EPO receptor (EPOR) on osteoblasts or B cells partially mitigates the skeletal effects of EPO, thereby implicating a contribution by EPOR on other cell lineages. This study was designed to define the role of monocyte EPOR in EPO-mediated bone loss, by using two mouse lines with conditional deletion of EPOR in the monocytic lineage. Low-dose EPO attenuated the reduction in bone volume (BV/TV) in Cx3cr1^Cre EPOR^f/f female mice (27.05%) compared to controls (39.26%), but the difference was not statistically significant. To validate these findings, we increased the EPO dose in LysM^Cre model mice, a model more commonly used to target preosteoclasts. There was a significant reduction in both the increase in the proportion of bone marrow preosteoclasts (CD115⁺) observed following high-dose EPO administration and the resulting bone loss in LysM^Cre EPOR^f/f female mice (44.46% reduction in BV/TV) as compared to controls (77.28%), without interference with the erythropoietic activity. Our data suggest that EPOR in the monocytic lineage is at least partially responsible for driving the effect of EPO on bone mass.

Erythroblastic islands foster granulopoiesis in parallel to terminal erythropoiesis

The erythroblastic island (EBI), composed of a central macrophage surrounded by maturing erythroblasts, is the erythroid precursor niche. Despite numerous studies, its precise composition is still unclear. Using multispectral imaging flow cytometry, in vitro island reconstitution, and single-cell RNA sequencing of adult mouse bone marrow (BM) EBI-component cells enriched by gradient sedimentation, we present evidence that the CD11b+ cells present in the EBIs are neutrophil precursors specifically associated with BM EBI macrophages, indicating that erythro-(myelo)-blastic islands are a site for terminal granulopoiesis and erythropoiesis. We further demonstrate that the balance between these dominant and terminal differentiation programs is dynamically regulated within this BM niche by pathophysiological states that favor granulopoiesis during anemia of inflammation and favor erythropoiesis after erythropoietin stimulation. Finally, by molecular profiling, we reveal the heterogeneity of EBI macrophages by cellular indexing of transcriptome and epitope sequencing of mouse BM EBIs at baseline and after erythropoietin stimulation in vivo and provide a searchable online viewer of these data characterizing the macrophage subsets serving as hematopoietic niches. Taken together, our findings demonstrate that EBIs serve a dual role as niches for terminal erythropoiesis and granulopoiesis and the central macrophages adapt to optimize production of red blood cells or neutrophils.

Developmental changes in iron metabolism and erythropoiesis in mice with human gain-of-function erythropoietin receptor

Iron availability for erythropoiesis is controlled by the iron-regulatory hormone hepcidin. Increased erythropoiesis negatively regulates hepcidin synthesis by erythroferrone (ERFE), a hormone produced by erythroid precursors in response to erythropoietin (EPO). The mechanisms coordinating erythropoietic activity with iron homeostasis in erythrocytosis with low EPO are not well defined as exemplified by dominantly inherited (heterozygous) gain-of-function mutation of human EPO receptor (mtHEPOR) with low EPO characterized by postnatal erythrocytosis. We previously created a mouse model of this mtHEPOR that develops fetal erythrocytosis with a transient perinatal amelioration of erythrocytosis and its reappearance at 3-6 weeks of age. Prenatally and perinatally, mtHEPOR heterozygous and homozygous mice (differing in erythrocytosis severity) had increased Erfe transcripts, reduced hepcidin, and iron deficiency. Epo was transiently normal in the prenatal life; then decreased at postnatal day 7, and remained reduced in adulthood. Postnatally, hepcidin increased in mtHEPOR heterozygotes and homozygotes, accompanied by low Erfe induction and iron accumulation. With aging, the old, especially mtHEPOR homozygotes had a decline of erythropoiesis, myeloid expansion, and local bone marrow inflammatory stress. In addition, mtHEPOR erythrocytes had a reduced lifespan. This, together with reduced iron demand for erythropoiesis, due to its age-related attenuation, likely contributes to increased iron deposition in the aged mtHEPOR mice. In conclusion, the erythroid drive-mediated inhibition of hepcidin production in mtHEPOR mice in the prenatal/perinatal period is postnatally abrogated by increasing iron stores promoting hepcidin synthesis. The differences observed in studied characteristics between mtHEPOR heterozygotes and homozygotes suggest dose-dependent alterations of downstream EPOR stimulation.