Erythropoietin Response Research Articles

Erythropoietin hyporesponsiveness in non-alcoholic fatty liver disease.

Treatment with erythropoietin (EPO) can correct anaemia in chronic kidney disease (CKD) patients; however, up to 10% exhibit resistance or hyporesponsiveness to EPO. Non-alcoholic fatty liver disease (NAFLD), prevalent liver disease in CKD patients, may limit EPO response because of thrombopoietin deficiency, iron homeostasis disorder and inflammation. Therefore, we hypothesized NAFLD is a risk factor for EPO responsiveness. To test our hypothesis, we evaluated the effect of EPO in healthy rats and rats with NAFLD induced by a high-fat, high-carbohydrate (HFHC) diet. After 12 weeks on the HFHC diet, NAFLD rats showed lower erythroid response to EPO treatment than healthy rats. We, then, determined that the primary cause of EPO hyporesponsiveness could be iron deficiency associated with inflammation, which reduces erythroid cell production. Specifically, the concentrations of hepcidin, ferritin, transferrin and white blood cells in NAFLD rats were 12.8-, 16.4-, 2.51- and 1.40-fold higher than those in healthy rats, respectively. However, erythroid cell types in the bone marrow of NAFLD rats were significantly reduced. In conclusion, our data suggest that NAFLD could be a risk factor for EPO responsiveness, which is attributed to functional iron deficiency associated with inflammation.

Iron Indices Mediate but Not Modify Association of Parathyroid Hormone with Erythropoietin Resistance in Hemodialysis Patients

Introduction: Disordered iron balance and abnormal parathyroid hormone (PTH) concentrations, both prevalent in hemodialysis patients, are risk factors of erythropoietin (EPO) resistance. Few studies have evaluated the correlation between iron indices and PTH and the potential role of iron markers on the association of PTH with EPO resistance in hemodialysis population. Methods: In this cross-sectional study of 71 maintenance hemodialysis patients, iron indices including hepcidin, ferritin, reticulocyte hemoglobin content (CHr), and transferrin saturation (TSAT) were examined. EPO responsiveness was measured as EPO resistance index (ERI). Lowess regression curves were performed to explore the correlations of iron indices, PTH, and ERI. The association between PTH and ERI was modeled using linear regressions. Potential role of iron indices on this association was examined using stratified analyses and mediation analyses. Results: The average ERI value was 10.3 ± 5.3 IU w−1 kg−1 (g/dL) −1. ERI was correlated to PTH, hepcidin, CHr, and TSAT (all p < 0.05). Hepcidin and PTH were closely correlated with each other (r = 0.28, p = 0.020). Analysis by PTH categories yielded a total association effect of 2.53 (95% CI: 0.27–4.85, p = 0.027) for high PTH subgroup versus the reference low subgroup. No clinically significant interaction between iron indexes and PTH was identified. Hepcidin appeared to mediate about one-third of the total association between PTH and ERI in hemodialysis population (33.6%, p = 0.025). Conclusion: Iron indices and PTH levels were related to ERI values. Hepcidin appeared to be closely correlated to PTH and partly mediate the association between PTH and ERI in hemodialysis population.

Impaired erythropoietin response to hypoxia in type 2 diabetes.

Patients with type 2 diabetes have a 20% lower total blood volume than age- and weight-matched healthy adults, suggesting a reduced capacity to transport oxygen in this population. Intermittent hypoxia, consisting of alternating short bouts of breathing hypoxic and normoxic air, increases erythropoietin levels, the hormone regulating red blood cell production, in young and older adults. The objective of this study was to determine the effect of a single session of intermittent hypoxia on erythropoietin levels and hemoglobin mass, the absolute mass of hemoglobin contained in red blood cells, in patients with type 2 diabetes. Ten patients with type 2 diabetes were exposed to an intermittent hypoxia protocol consisting of eight 4-min cycles at a targeted oxygen saturation of 80% interspersed with normoxic cycles to resaturation. Erythropoietin and hemoglobin mass responses to intermittent hypoxia in patients with type 2 diabetes were compared to previously published data from an identical intermittent hypoxia protocol performed in age-matched older adults. Intermittent hypoxia increased erythropoietin levels in older adults but did not induce any change in erythropoietin levels in patients with type 2 diabetes (3.2 ± 2.2 vs. 0.2 ± 2.7mU/ml, p = 0.01). Hemoglobin mass indexed to body weight was 21% lower in patients with type 2 diabetes than in older adults (8.1 ± 1.7 vs. 10.2 ± 2.1g/kg, p < 0.01). These findings suggest an impaired erythropoietin response to decreased oxygen levels in patients with type 2 diabetes, which may contribute to the reduced oxygen transport capacity observed in this population.

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 3weeks. 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.

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.

Theranova versus FX80: The impact on anemia management in hemodialysis.

Middle uremic toxins (MUTs) can cause anemia and erythropoietin hyporesponsiveness. Theranova dialyzers may improve anemia management by removing MUTs. Hence, the impact of Theranova dialyzers on erythropoietin responsiveness was studied. This exploratory single-center prospective observational study, encompassing 50 patients undergoing dialysis with either the Theranova-400 or FX80 membrane for 6 months, involved monthly tracking of hemoglobin levels, weight-adjusted erythropoiesis-stimulating agent (w-ESA) dosing, and erythropoietin resistance index (ERI), with ESA treatment decisions guided by a proprietary algorithm. The groups were similar in terms of demographics and baseline laboratory test results. The median hemoglobin levels, w-ESA and ERI, were found to be similar between FX80 and Theranova-400 groups at both baseline (11.06 vs 10.57, p = 0.808; 92.3 vs 105.2, p = 0.838; 8.1 vs 10.48, p = 0.876) and the end of the study (11.43 vs 11.03, p = 0.076; 48.7 vs 71.5; 4.48 vs 6.41, p = 0.310), respectively. There was a trend toward lower w-ESA and ERI at the end of the study compared to baseline in both groups, but the difference was non-significant. Based on this study of 50 patients undergoing high-flux dialysis with near-target hemoglobin levels, switching to Theranova 400 dialyzers compared to FX80 dialyzers did not show statistically significant differences in maintaining hemoglobin levels, reducing ESA dose, or lowering ERI. The non-randomized design and small sample size limit the study's power to detect true differences. Larger, randomized trials are needed to confirm findings and definitively assess Theranova 400's benefits.

Correlation between ultrafiltration rate and hemoglobin level and erythropoietin response in hemodialysis patients

This study aimed to investigate the correlation between ultrafiltration rate (UFR) and hemoglobin levels and erythropoietin (EPO) response in patients receiving maintenance hemodialysis (MHD). 225 MHD patients were divided into three groups according to the UFR: < 10 ml/h/kg, 10–13 ml/h/kg, and >13 ml/h/kg. Clinical parameters and prognosis were compared among the groups. Multiple linear correlation and regression analyses were conducted. SPSS 26.0 (IBM, Chicago, IL, USA) was used to analyze all statistics. The UFR < 10 ml/h/kg group was older than the other groups (p < 0.05). The UFR > 13 ml/h/kg group had the highest SpKt/V (p < 0.05), monthly EPO dose/weight (p < 0.001), and EPO resistance index (p < 0.001), as well as the lowest dry weight (p < 0.001), BMI (p < 0.001), hemoglobin (p < 0.001), hematocrit (p < 0.05), and red blood cell count (p < 0.05). Multiple linear regression analysis showed that sex, dry weight, UFR, calcium, phosphorus, albumin, and C-reactive protein levels were associated with hemoglobin levels. Multivariate logistic regression analysis revealed that a higher UFR was associated with lower hemoglobin levels, while male sex and higher levels of calcium and albumin were associated with higher hemoglobin levels. High UFR is associated with more severe anemia and EPO resistance in MHD. This study provides new insights into anemia management in patients undergoing hemodialysis.

The Role of Zinc and Copper in Anemia and Erythropoietin Responsiveness in Patients on Hemodialysis and Peritoneal Dialysis

Introduction: Imbalance in copper (Cu) and zinc (Zn) homeostasis is a frequent finding in patients undergoing dialysis. These patients have higher serum Cu and lower serum Zn levels compared to controls. This study is designed to investigate the relationship between blood Cu and Zn levels and Cu/Zn ratio and, ESA (erythropoietin stimulating agent) dosage, erythropoietin responsiveness and anemia in dialysis patients. Methods: Clinical and demographic data for 151 participants (men=79) with a median dialysis vintage of 69.7 months [101 on Hemodialysis (HD), 50 on Peritoneal Dialysis (PD)] and mean age of 56.25±15.6 years was collected in November 2022. Zn and Cu levels were measured with atomic absorption. Erythropoietin responsiveness was evaluated by the erythropoietin resistance index (ERI) and ESA dosing. Results: In HD patients, mean serum Zn and Cu levels were 61.33 ± 15.77 μg/dL and 95.1 ± 21.1 µg/dL, respectively, with a Cu/Zn ratio of 1.58 ± 0.69. In PD patients, mean serum Zn and Cu levels were 54.8 ± 10.3 µg/dL and 97 ± 20.2 µg/dL, respectively, with a Cu/Zn ratio of 1.72 ± 0.55. In Spearman analyses serum Cu was negatively correlated with hemoglobin (p=0.018), serum iron (p=0.03), transferrin saturation (p=0.019), and iron supplementation (p &lt;0.01) in the HD patient group. Serum Cu was found to be positively correlated with erythropoietin (EPO) dosage (p=0.03), ERI (p=0.04), high sensitive C reactive protein (hsCRP) (p=0.01), and Kt/V (p=0.033). Cu/Zn ratio was positively correlated with EPO dosage (p=0.043), ERI (p=0.051) and hsCRP (p=0.015). Conversely, it was negatively correlated with iron supplementation (p=0.014) and serum albumin levels (p=0.049). Serum Zn levels was solely correlated with albumin level (p=0.039). In PD, patient’s serum Cu level was correlated positively with hsCRP (p=0.036); serum Zn levels correlated positively (p=0.01), and Cu/Zn ratio was correlated negatively with albumin (p=0.042). Conclusion: This study has shown a possible association between both serum Cu and Cu/Zn ratio, ESA dosage and hsCRP in HD patients.

Understanding the Impact of HIV-Associated Bone Marrow Alterations on Erythropoiesis

Human Immunodeficiency Virus (HIV) infection presents a multifaceted challenge, extending beyond its primary impact on the immune system to affect various organ systems. Among these, the bone marrow, the primary site for hematopoiesis, undergoes substantial alterations during HIV infection, profoundly influencing erythropoiesis—the process of red blood cell production. Anemia, a prevalent hematologic complication in HIV-infected individuals, often serves as a marker of disease progression and impacts overall health outcomes. This paper aims to delve into the intricate relationship between HIV-associated bone marrow alterations and their consequential effects on erythropoiesis. The mechanisms underlying bone marrow changes in HIV infection, including direct viral effects, dysregulation of cytokine networks, and inflammatory processes, significantly disrupt the delicate balance necessary for efficient erythropoiesis. The impact of these alterations on erythropoiesis manifests through ineffective red blood cell production, decreased erythropoietin responsiveness, and shortened red blood cell lifespan. Chronic inflammation further complicates erythropoietic processes, contributing to the development and perpetuation of anemia in HIV-infected individuals. Therapeutic interventions encompass a multifaceted approach, including antiretroviral therapy (ART) to control viral replication, erythropoiesis-stimulating agents, and adjunctive nutritional support to manage anemia. However, emerging research targeting bone marrow microenvironmental factors and novel agents stimulating erythropoiesis offer promising avenues for future therapeutic development. Keywords: HIV, bone marrow, erythropoiesis, erythropoietin, antiretroviral therapy

Comparative analysis of roxadustat efficacy between maintenance hemodialysis and peritoneal dialysis patients.

This study evaluated the comparative efficacy of roxadustat for renal anemia between patients on maintenance hemodialysis (HD) and peritoneal dialysis (PD). 93 maintenance dialysis patients who regularly followed up from August 2015 to June 2021 were enrolled. Despite receiving a therapeutic dose ≥ 12,000 U/week of erythropoiesis-stimulating agents (E+SA) in the past 12 weeks, this had not worked very well. Subjects were assigned to the HD group (n = 60) or the PD group (n = 33) based on their dialysis treatment modality. All patients received oral roxadustat and were followed up for 24 weeks, after which their hemoglobin, serum iron, transferrin saturation, and ferritin were tested. We observed that the hemoglobin level of PD patients was significantly increased from 76.1 ± 15.7 g/L to 106 ± 23.8 g/L (p < 0 .001), while it significantly increased from 73.8 ± 12.9 g/L to 100.7 ± 20.2 g/L (p < 0.001) in the HD patients. After 1 and 3 months of roxadustat treatment, the hemoglobin level and its change in the PD group was significantly higher compared to that in the HD group despite the higher dose of roxadustat in the latter group. In addition, roxadustat was noted to reduce cholesterol levels and stabilize serum iron levels in parallel with improving hemoglobin levels. Roxadustat can effectively increase the hemoglobin level of maintenance dialysis patients, even in those with low erythropoietin response or erythropoietin resistance, and, more importantly, its efficacy in PD patients was more significant.

Serum erythropoietin level in anemic and non-anemic patients with chronic leukemia

Abstract Background: Anemia is a common issue in chronic leukemia, which results in a worse outcome and shorter survival. Inadequate production of erythropoietin (EPO) as compared to the severity of anemia may play a major role in ACD for patients with hematological malignancies. Clarifying the role of EPO may provide a better understanding of its pathogenesis, and proper management of patients. Objectives: To determine serum EPO levels and look for any potential link between EPO and the cause of anemia in anemic patients with chronic leukemia in a sample of Iraqi patients in the middle euphrates region. Materials and Methods: This is a case control study included 38 patients (19 chronic myeloid leukemia [CML], 19 chronic lymphocytic leukemia [CLL]) who were attending the outpatient clinic of hematology in Baghdad Teaching Hospital, Marjan Teaching Hospital from September 2022 to March 2023, together with 30 adult participants without disease as a control group. All patients involved were diagnosed as having a disease based on a specialist’s physical examination, morphological evaluation of peripheral blood films and bone marrow, and flow cytometric immune-phenotypic profile. Blood samples were collected from each subject, and the following investigations were done: CBC, RFT, blood film examination, and ELISA assay for serum EPO. Results: The mean age of CML patients was (50.1 ± 12.85) range from 24 to 72, CLL patients (58.2 ± 10.4) range from 38 to 75. The majority of patients were men (N = 23, 60.5%). The participants in the patient group were subdivided into 18 (47.4%) patients with anemia and 20 (52.6%) patients without anemia. The mean differences of EPO concentration (U/L) between study groups demonstrated significant higher level among patient group (49.53 ± 56.82) than control group (12.73 ± 4.72) with P value &lt; 0.0001. The level of serum EPO in anemic patients (89.28 ± 61.95) has been found to be higher than non-anemic patients (13.82 ± 4.43) and it was statistically significant (P &lt; 0.0001). Endogenous EPO production was found to be defective in 10% of CML patients, 50% of CLL patients were judged by a value for the ratio of observed-to-predicted serum EPO levels (observed/predicted ratio) of ≤0.9. Conclusion: These findings indicate that anemia associated with hematologic malignancy may result from an inappropriately low EPO response. EPO treatment should benefit in this group of patients.

#2621 HEMOGLOBIN VARIABILITY IS ASSOCIATED WITH NUTRITIONAL STATUS IN HEMODIALYSIS PATIENTS UNDERGOING DARBEPOETIN-ALFA TREATMENT

Abstract Background and Aims Anemia is the most common finding in hemodialysis (HD) patients. A significant proportion of patients are taking erythropoietin (EPO) or other erythrocyte-stimulating agents (ESAs), yet the response to treatment is unsatisfactory, and EPO responsiveness is inconsistent in HD patients. Further, although the introduction of EPO has led to a dramatic reduction in blood transfusion requirements and is associated with improved quality of life, fluctuations in hemoglobin (Hb) levels, known as Hb variability, during EPO treatment is a well-documented phenomenon. Malnutrition is a well-known risk factor in the general population and in HD patients. However, few studies have evaluated the association between EPO responsiveness/Hb variability and nutritional status in HD patients. Therefore, our aim was to investigate whether EPO responsiveness and Hb variability can be associated with nutritional status in HD patients undergoing NESP® (darbepoetin-alfa; Kyowa Kirin Korea Co., Ltd.) treatment. Method In this prospective study, we included adult ninety-eight patients aged over 20 years who had been undergoing HD over 6 months. The target hemoglobin (Hb) level is 10–11 g/dL according to the Korean reimbursement guideline. Dose adjustments of NESP® were made according to the Hb level measured monthly in our facility. Every study population have more than 24 monthly Hb data points. We checked average darbepoetin-alfa dose weekly and the EPO resistance index (ERI) as a marker of EPO responsiveness was calculated by dividing the weekly average darbepoetin-alfa dose by the Hb level. In addition, we evaluated the more than 24 month Hb variability, which was expressed by Hb-Coefficient of Variation (Hb-CV). All of them were measured by BCM® (Fresenius Medical Care a Deutschland GmbH, Germany) to assess the nutritional status three times (Baseline, 12 Mos, 24 Mos). Nutritional parameters obtained by BCM® were body mass index (BMI), fat tissue index (FTI), lean tissue index (LTI), body cell mass index, phase angle (PhA). Clinical parameters and routine biochemical tests such as dose of erythropoietin, Kt/Vurea, iron and lipid profiles, C-reactive protein, albumin, calcium, phosphorus, intact-parathyroid hormone were also taken into account. Results In this study, the mean age of the patients was 64.0 ± 11.9 years, and 55.0% were male. Dialysis vintage was 54.9 ± 46.8 months. Follow-up duration was 79.3±47.9 months. Mean Hb was 10.7 ± 1.3 g/dL. We divided into tertiles (T) according to the ERI. The average ERI was 0.02 ± 0.01, 0.04 ± 0.01, and 0.07 ± 0.03 in ERI-T1, ERI-T2, and ERI-T3, respectively. The ERI-T3 group had the lower Hb level (p = 0.038) whereas administration dose of EPO were higher in ERI-T3 (p = 0.001). The ERI-T3 group had the lower PhA (p = 0.044), BMI (p = 0.001) and FTI (p = 0.046) values. We divided into tertiles (T) according to the Hb-CV. The average Hb-CV was 0.06 ± 0.01, 0.08 ± 0.05, and 0.12 ± 0.02 in Hb-CV-T1, Hb-CV-T2, and Hb-CV-T3, respectively. When comparing the three groups, the Hb-CV-T3 group had the lower BMI (p = 0.002) and lower FTI (p = 0.002). Age (r = 0.203, p = 0.036), female sex (r = 0.376, p = 0.001), presence of diabetes mellitus (r = 0.191, p = 0.049), total iron binding capacity (r = 0.205, p = 0.035) and triglyceride (r = 0.227, p = 0.018) were positively correlated with FTI. ERI (r = -0.193, p = 0.046) and Hb-CV (r = -0.268, p = 0.005) were negatively correlated with FTI. In multiple linear regression analysis, FTI was negatively associated with ERI (β = -0.218, p = 0.014), Hb-CV (β = -0.181, p = 0.039), whereas FTI was positively associated with age (β = 0.197, p = 0.017) and female sex (β = 0.386, p = 0.001). Conclusion In HD patients with higher ERI, PhA, BMI and FTI were significantly decreased. Furthermore, in patients with high Hb-CV, BMI and FTI were decreased. In addition, FTI was negatively associated with ERI and Hb-CV. Therefore, EPO responsiveness and Hb-variability is associated with nutritional status, especially fat tissue in hemodialysis patients undergoing darbepoetin-alfa treatment.

Brief exposure to intermittent hypoxia increases erythropoietin levels in older adults.

Eight 4-min cycles of intermittent hypoxia represent the shortest hypoxic exposure to increase erythropoietin (EPO) levels in young adults. The impact of aging on the EPO response to a hypoxic stimulus remains equivocal. Thus, the objective of this study was to determine the effect of the same intermittent hypoxia protocol on EPO levels in older adults. Twenty-two participants (12 women, age: 53 ± 7 yr) were randomly assigned to an intermittent hypoxia group (IH, n = 11) or an intermittent normoxia group (IN, n = 11). Intermittent hypoxia consisted of eight 4-min cycles at a targeted oxygen saturation of 80% interspersed with normoxic cycles to resaturation. Air was made hypoxic by titrating nitrogen into a breathing circuit. Intermittent normoxia consisted of the same protocol, but nitrogen was not added to the breathing circuit. EPO levels were measured before and 4.5 h after the beginning of each protocol. Intermittent hypoxia lowered oxygen saturation to 82 ± 3%, which corresponded to a fraction of inspired oxygen of 10.9 ± 1.0%. There was a greater increase in EPO levels following intermittent hypoxia than intermittent normoxia (IH: 3.2 ± 2.2 vs. IN: 0.7 ± 0.8 mU/mL, P < 0.01). A single session of eight 4-min cycles of hypoxia increased EPO levels, the glycoprotein stimulating red blood cell production, in older adults. Exposure to intermittent hypoxia has therefore the potential to increase oxygen-carrying capacity in a population with reduced red blood cell volume.NEW & NOTEWORTHY We previously identified the shortest intermittent hypoxia protocol necessary to increase erythropoietin levels in young adults. The objective of this study was to determine whether the same intermittent hypoxia protocol increases erythropoietin levels in older adults. Eight 4-min bouts of hypoxia, representing a hypoxic duration of 32 min at a targeted oxygen saturation of 80%, increased erythropoietin levels in older adults, suggesting that exposure to intermittent hypoxia has the potential to increase oxygen-carrying capacity in an aging population.

Sex differences in the erythropoietin response to hot tub treatment and carbon monoxide inhalation

The kidney increases erythropoietin (EPO) when oxygen delivery is reduced, and when reductions in oxygen delivery are sustained, increased EPO results in increased red blood cell (RBC) production. More recently, carbon monoxide (CO) and heat have been used chronically to increase RBC production and therefore hemoglobin (Hb) mass. However, studies examining the acute effects of these interventions are limited, and no studies have examined these interventions in women. The purpose of this study was to examine the effects of CO inhalation and heat treatment alone and in combination on circulating EPO and determine if there are sex differences in these responses. 11 healthy subjects completed the study (6 women). Baseline blood was drawn to measure iron, ferritin, and transferrin concentrations. Hb mass was measured via the 10-minute CO-rebreathe method. Subjects completed three interventions – CO inhalation (carboxyhemoglobin 13.01±2.5%) hot tub immersion (40 degrees C for 45 minutes), and combined CO and hot tub – in a randomized crossover design. Renal blood velocity (RBV) was measured via ultrasound during all interventions. Venous blood was drawn at baseline and every hour for 6 hours post-intervention for measurements of EPO. All interventions reduced renal oxygen delivery (Δ47.5±21mL O2/min), and there were no sex differences in the reduction in oxygen delivery. All three treatments similarly increased EPO from baseline to peak concentration (Δ4.94±5.6mIU/mL). Women had a significantly greater increase in EPO than men to all three interventions (Δwomen 8.22±5.6mIU/mL; Δmen 1±2.06mIU/mL). The degree of EPO increase on all three days negatively correlated with Hb mass (R2=0.64) and positively correlated with transferrin (R2=0.73). Women may respond better to these interventions aimed to increase EPO, but the degree of responsiveness may depend on baseline Hb mass as well as transferrin concentrations. Wu-Tsai Human Performance Alliance at Oregon This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Impaired Erythropoietin Response to Intermittent Hypoxia in Patients with Type 2 Diabetes

Patients with type 2 diabetes (T2D) exhibit, on average, a 20% decline in maximal oxygen consumption when compared to healthy adults. Hemoglobin mass strongly correlates to maximal oxygen consumption. A reduced total blood volume has been observed in patients with T2D, suggesting that a reduced hemoglobin mass contributes to the decreased maximal oxygen consumption in this population. Hypoxia stimulates the release of erythropoietin (EPO), the hormone regulating red blood cell production. We previously showed that intermittent hypoxia, consisting of alternating short bouts of breathing hypoxic and normoxic air, increases EPO levels. Thus, the objective of this study was to determine the effect of a single session of intermittent hypoxia on serum EPO levels and hemoglobin mass in patients with T2D. We hypothesized that a single session of intermittent hypoxia would raise serum EPO levels and lead to an increase in hemoglobin mass in patients with T2D. Ten patients with T2D (4 women, age: 53 ± 10 years, body mass index: 36.2 ± 8.5 kg/m2, HbA1c: 7.2 ± 1.2%) were exposed to an intermittent hypoxia protocol consisting of eight 4-min cycles at a targeted oxygen saturation of 80% interspersed with normoxic cycles to resaturation. Air was made hypoxic by titrating nitrogen into a breathing circuit. Pulmonary gas exchange, oxygen saturation, and hemodynamics were continuously measured throughout the protocol. EPO levels were measured before and 4.5 hours after the beginning of the protocol. Hemoglobin mass was assessed via carbon monoxide rebreathing before and seven days following intermittent hypoxia. Intermittent hypoxia lowered oxygen saturation (&amp;shy;&amp;shy;97 ±&amp;shy; 2 to 81 ± 2%, p&lt;0.01), which resulted in a lower fraction of inspired oxygen (20.8 ±&amp;shy; 0.1 to 11.1 ± 1.0%, p&lt;0.01). There was no significant change in EPO levels following exposure to intermittent hypoxia (11.9 ± 5.3&amp;shy; to 12.1 ± 4.3 mU/ml, p=0.83). There was also no change in hemoglobin mass in response to intermittent hypoxia (864 ± 152&amp;shy; to 850 ± 150 g, p=0.64). Intermittent hypoxia did not affect mean arterial pressure (94 ± 5 to 97 ± 7 mmHg, p=0.18) but increased cardiac output (9.1 ± 2.7 to 9.8 ± 2.8 L/min, p=0.03) due to an increase in heart rate (78 ± 9 to 84 ± 10 bpm, p&lt;0.01). In conclusion, a single session of intermittent hypoxia did not increase serum EPO levels or hemoglobin mass in patients with T2D. These findings suggest an impaired EPO response to decreased oxygen levels in patients with T2D, which may contribute to the reduced hemoglobin mass and total blood volume observed in this population. College of Education Small Grants Program This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A single approach to targeting transferrin receptor 2 corrects iron and erythropoietic defects in murine models of anemia of inflammation and chronic kidney disease

Anemia is a common complication of systemic inflammation. Proinflammatory cytokines both decrease erythroblast sensitivity to erythropoietin (EPO) and increase the levels of the hepatic hormone hepcidin, sequestering iron in stores and causing functional iron deficiency. Anemia of chronic kidney disease (CKD) is a peculiar form of anemia of inflammation, characterized by impaired EPO production paralleling progressive kidney damage. Traditional therapy based on increased EPO (often in combination with iron) may have off-target effects due to EPO interaction with its non-erythroid receptors. Transferrin Receptor 2 (Tfr2) is a mediator of the iron-erythropoiesis crosstalk. Its deletion in the liver hampers hepcidin production, increasing iron absorption, whereas its deletion in the hematopoietic compartment increases erythroid EPO sensitivity and red blood cell production. Here, we show that selective hematopoietic Tfr2 deletion ameliorates anemia in mice with sterile inflammation in the presence of normal kidney function, promoting EPO responsiveness and erythropoiesis without increasing serum EPO levels. In mice with CKD, characterized by absolute rather than functional iron deficiency, Tfr2 hematopoietic deletion had a similar effect on erythropoiesis but anemia improvement was transient because of limited iron availability. Also, increasing iron levels by downregulating only hepatic Tfr2 had a minor effect on anemia. However, simultaneous deletion of hematopoietic and hepatic Tfr2, stimulating erythropoiesis and increased iron supply, was sufficient to ameliorate anemia for the entire protocol. Thus, our results suggest that combined targeting of hematopoietic and hepatic Tfr2 may be a therapeutic option to balance erythropoiesis stimulation and iron increase, without affecting EPO levels.

Abstract 104: Cytochrome B5 Reductase 3 Regulates The Erythropoietin Response To Ischemic Stroke In A Mouse Model Of Chronic Anemia And Oxidative Stress

Introduction: Cytochrome b5 reductase 3 (Cyb5R3) is a heme iron reductase that reverses oxidized soluble guanylate cyclase (sGC) heme iron (Fe 3+ Fe 2+ ) to preserve nitric oxide signaling. Under oxidative stress, such as occurs with sickle cell disease (SCD) and ischemic stroke, Cyb5R3 redox signaling provides resilience against tissue damage. A loss-of-function (roughly 50%) Cyb5R3 missense variant (T117S) occurs with high frequency (0.23 minor allele) in persons of African ancestry, who also suffer a greater burden of sickle cell anemia and ischemic stroke than other races. We hypothesized that Cyb5R3 regulates the erythropoietin response to ischemic stroke in a mouse model of SCD. Methods: Age-matched male SCD mice with wild-type Cyb5R3 (SS WT ) or T117S Cyb5R3 (SS T117S ) underwent middle cerebral artery occlusion (55 min) and reperfusion (48 hr). Blood was sampled at baseline and 48h reperfusion for hematology measurements. Brains were stained with 2,3,5-triphenyltetrazolium chloride to quantify infarct volume. Erythropoietin (EPO), heme oxygenase 1 (HMOX1) and sGC were assayed by Western blot. Results: We found brain infarct volume to be greater in SS T117S vs SS WT (63 vs 27 cm 3 , respectively; P=0.003). Red cells, hematocrit and hemoglobin decreased in SS T117S post-stroke, which was opposite to SS WT (red cells: -13% vs 13%, P=0.01; hematocrit: -20% vs 0%, P=0.03; hemoglobin: -18% vs 3%, P=0.02, respectively). In the absence of stroke (age-matched controls), SS WT had elevated HMOX1 protein compared to SS T117S , which normalized in post-stroke SS WT but was unchanged in post-stroke SS T117S . Kidney and plasma EPO levels significantly increased in SS WT post-stroke, but not in SS T117S . In vitro studies using HEK293 cells showed EPO and HMOX1 decrease with Cyb5R3 knockdown by siRNA. Conclusion: Our findings suggest a modifying role for Cyb5R3 in brain-kidney crosstalk during ischemic stroke, wherein loss of T117S Cyb5R3 activity negatively impacts renal and plasma EPO levels and resilience against infarct of ischemic brain tissue. The Cyb5R3 axis on which the brain-kidney-blood response to stroke in SCD turns represents a novel target for precision medicine approaches to managing stroke risk and pathology in SCD carriers of the T117S variant.

Association of Vitamin D Deficiency with Renal Anemia and Erythropoietin Hyporesponsiveness in Hemodialysis Patients

Background and Aim: The erythropoietin (EPO) response is usually hypo responsive in patients on maintenance hemodialysis (MHD). EPO requirements in chronic kidney disease patients are inversely associated with vitamin D levels. By suppressing chronic inflammation, reducing hyperparathyroidism, or stimulating erythroid progenitors, vitamin D supplementation may improve response to EPO. Anemia and hypo responsiveness of erythropoietin in patients undergoing hemodialysis were investigated in the current study. Patients and Methods: This cross-sectional study was conducted on 40 hemodialysis patients with anemia in Nephrology department, of Mayo Hospital, Lahore from 21st January 2021 to 20th February 2022. As controls, 30 healthy people of the same age and gender were used. Study protocol was approved by institute research and ethical committee. Each individual provided written informed consent. ERI calculation, total iron-binding capacity, complete blood profile, serum iron, alkaline phosphate, vitamin D, ferritin, interleukin (IL-6), calcium, and C-reactive protein were the baseline laboratory parameters measured. Oral α-calcidol therapy was used for follow-up for 3 months. SPSS version 26 was used for data analysis. Results: The overall mean age was 46.82±16.37 years. Of the total 40 HD patients, there were 20 (50%) male and 20 (50%) females. Based on comparison made for hemodialysis patients before and after α-calcidol therapy (P2), there were significant decrease in ERI from 7.42±1.24 to 6.59±1.1 IU/kg/g/dl and significant increase in Hb from 8.37±0.8 to 9.52±0.9 g/dl. Inflammatory markers such as hepcidin, C-reactive protein, ferritin, and IL-6 significantly decreased. There was a substantial positive relation between ERI and serum ferritin (P=0.03) at the start of the trial, and a significant negative correlation between blood vitamin D3 level and ALP (P=0.003). There was a significant negative connection between blood vitamin D3 level and serum ferritin (P=0.005) and IL-6 (P=0.02) levels at the conclusion of the trial. Conclusion: The present study found that hemoglobin levels in HD patients are significantly increased following a 3 month course of oral alfacalcidol supplementation. Improvements in these patients' chronic inflammatory status and control of hyperparathyroidism appear to be associated with and mediated by ameliorative effects. To manage anemia and mineral metabolism in DKD patients effectively, PTH hypersecretion must be controlled effectively. Supplementing HD patients with vitamin D increases their response to EPO and increases its cost-effectiveness within CKD-MBD guidelines. Keywords: Vitamin D deficiency, Renal anemia, Erythropoietin, Hemodialysis

Relation between serum zinc and Erythropoietin responsiveness in prevalent Hemodialysis patients

Relation between serum zinc and Erythropoietin responsiveness in prevalent Hemodialysis patients

Malnutrition and Erythropoietin Resistance among Patients with End-Stage Kidney Disease: Where Is the Perpetrator of Disaster?

Hemodialyzed patients with poor erythropoietin response tend to have low volume of visceral adipose tissue and score high on malnutrition-inflammation score. This study investigates in-depth the role of leptin and chosen cytokines in the development of malnutrition-inflammation syndrome (MIS) and erythropoietin resistance. Eighty-one hemodialyzed patients with erythropoietin-treated anemia were enrolled in the study. Their body composition was measured. Erythropoietin resistance index was calculated. Blood samples for leptin, IL-6, IL-18, TNF-alpha, and IL-1-alpha serum levels were drawn. Leptin showed negative correlation with erythropoietin resistance index (ERI), whilst IL-6 showed the opposite. IL-6 seemed to be linked more to HD parameters and vintage, while TNF-alpha and leptin were more dependent on body composition. IL-18 and IL-1-alpha did not affect nutritional parameters nor ERI. Modulation of adipokine- and cytokine-related signaling is a promising target in tempering malnutrition in hemodialyzed, and thus achieving better outcomes in anemia treatment. Large clinical studies that target the inflammatory response in hemodialysis, especially regarding IL-6, TNF-alpha, and leptin, would be of great worth.