Investigation of the pronounced erythropoietin-induced reduction in hyperglycemia in type 1-like diabetic rats

Impact of erythropoietin and myoinositol versus metformin on insulin resistance in a rat model of polycystic ovary syndrome

This study aimed to evaluate the therapeutic role of erythropoietin (EPO) or myoinositol versus metformin (MET) in improving the reproductive functions and glucose tolerance in a rat model of polycystic ovary (PCOS). Oral letrozole (LTZ) was used for induction of PCOS in wester rats for 21 days, after that, MET, EPO and myoinositol were administered for the following 21 days. The LTZ-induced PCOS rats have lost their oestrous cyclicity and become fixed at the diestrus phase, developed insulin resistance, abnormal sex and gonadotrophin hormone serum levels, increased cystic follicles, decreased number of the growing follicles and very little or no corpora lutea on microscopic examination, which were reversed by the three drugs, MET, EPO and myoinositol. MET and myoinositol were mostly equally effective in improving the reproductive manifestations of the disease. However, EPO was most effective in decreasing the insulin level observed in this LTZ-induced model of PCOS.

Comparison of Circulating Biomarkers in Predicting Diabetic Kidney Disease Progression With Autoantibodies to Erythropoietin Receptor

Introduction

Several circulating markers, including autoantibodies to erythropoietin receptor (anti-EPOR antibodies), have been identified as useful biomarkers in predicting diabetic kidney disease progression. However, a direct comparison of their utility is lacking. We aimed to validate and to compare the prognostic value of anti-EPOR antibodies with that of other known biomarkers, using the ADVANCE trial and its long-term follow-up, ADVANCE-ON, cohorts.

Methods

In this nested case-control study from the ADVANCE trial cohort, we included 165 case participants who had the composite kidney outcome (renal replacement therapy, renal death, or doubling of serum creatinine to ≥200 μmol/l) and 330 matched controls. We compared the associations of baseline plasma levels of anti-EPOR antibodies, tumor necrosis factor receptor (TNFR)-1 and -2, and bone morphogenetic protein (BMP)-7 with kidney outcomes.

Results

Cases had higher baseline plasma levels of anti-EPOR antibodies than controls (median 1.7 vs. 0.6 enzyme-linked immunosorbent assay unit, P < 0.001). Higher levels of anti-EPOR antibodies were associated with an increased risk of kidney outcome (odds ratio 2.16 [95% confidence interval 1.51, 3.08], per 1 SD of log-transformed levels) after adjusting for conventional markers. Elevated circulating TNFR1 and TNFR2 levels, and lower BMP-7 levels at baseline, were associated with poor kidney outcome (odds ratios 2.06 [1.29, 3.30], 1.66 [1.13, 2.43], and 0.45 [0.32, 0.65], respectively). The addition of anti-EPOR antibodies into the model improved the prediction of kidney outcome, regardless of other biomarkers.

Conclusion

Anti-EPOR antibodies provide a promising biomarker, as with TNFR1, TNFR2, and BMP-7, in predicting kidney disease progression in people with type 2 diabetes mellitus.

Erythropoietin Treatment Is Associated with Decreased Blood Glucose Levels in Hematologic Patients

BACKGROUND

Erythroid stimulating agents (ESAs) have pleiotropic effects, and in animal and human studies those exposed to high erythropoietin had lower blood glucose.

OBJECTIVE

To determine the association between ESA and glucose in anemia-treated patients with myelodysplastic syndromes (MDS) or multiple myeloma (MM).

PATIENTS AND METHODS

Patients' glucose levels were compared while on to while off ESA, and all served as their own controls. To test the association between ESA and blood glucose, we employed a linear mixed model, accounting for variability in the number of measurements for each patient.

RESULTS

Charts of 20 patients were reviewed. Mean age was 77 ± 9.8 years (range 50-91). Thirteen patients had MDS, and 8 had MM (1 with both). Glucose (mean ± standard error of the mean) was 116.38 ± 5.21 mg/dL without ESA, as opposed to 105.64 ± 5.11 mg/dL with ESA (p < 0.0001). The 3 diabetic and 5 steroid-treated patients also demonstrated reduced glucose by approximately 19 mg/dL with ESA (p = 0.003 and p = 0.0001, respectively). There was no difference in collective hemoglobin levels between the 2 groups.

CONCLUSION

ESA treatment for anemia is associated with lower blood glucose in hematologic patients. In those who also have diabetes mellitus, ESA might contribute to glucose control, and even to hypoglycemia. Glucose monitoring is thus advised. Further studies with both diabetic and nondiabetic patients are needed to clarify this association and underlying mechanisms.

Promotion of Adropin Expression by Hyperglycemia Is Associated with STAT3 Activation in Diabetic Rats

BACKGROUND

Adropin is a secreted polypeptide that has been demonstrated to play an important role in energy homeostasis and lipid metabolism. Signal transducer and activator of transcription 3 (STAT3) may promote the transcription of target genes including adropin. In the current study, we investigated the effect of adropin on glucose metabolism in diabetic rats and the mechanism that governs this effect was subsequently assessed.

MATERIALS AND METHODS

Rats received a single injection of streptozotocin to induce type 1 diabetes. The diabetic rats were treated with insulin or phloridzin, another antidiabetic agent through inhibition of glucose reabsorption, for 7 days. Plasma glucose levels and adropin levels were measured. The interaction between STAT3 and adropin was evaluated using the human hepatoma HepG2 cell line. HepG2 cells were pretreated with the specific antagonist Stattic or with STAT3-specific siRNAs to knockout STAT3. Changes in energy homeostasis-associated gene expression were measured using real-time PCR. The protein expression levels of pSTAT3 and STAT3 were measured using Western blotting.

RESULTS

In diabetic rats, the serum concentrations of adropin were increased in the vehicle-treated group and decreased in the insulin- or phloridzin-treated group. In liver tissues, the Enho expression level and the activity of STAT3 also showed similar tendencies. After HepG2 cells were treated with medium containing high glucose, the ratio of p-STAT3 to STAT3, Enho mRNA levels and reactive oxygen species expression levels in HepG2 cells were significantly increased in conjunction with increased glucose levels. The effect was inhibited after pretreatment with Stattic or knockdown with STAT3-specific siRNAs.

CONCLUSION

STAT3 is involved in the genetic regulation of adropin, increasing the levels of circulating adropin and promoting Enho expression in the livers of diabetic rats.

Fetal chronic hypoxia and oxidative stress in diabetic pregnancy. Could fetal erythropoietin improve offspring outcomes?

Oxidative stress is responsible for microvascular complications (hypertension, nephropathy, retinopathy, peripheral neuropathy) of diabetes, which during pregnancy increase both maternal and fetal complications. Chronic hypoxia and hyperglycemia result in increased oxidative stress and decreased antioxidant enzyme activity. However, oxidative stress induces also anti-oxidative reactions both in pregnant diabetes patients and in their fetuses. Not all type 1 diabetes patients with long-lasting disease develop microvascular complications, which suggests that some of these patients have protective mechanisms against these complications. Fetal erythropoietin (EPO) is the main regulator of red cell production in the mother and in the fetus, but it has also protective effects in various maternal and fetal tissues. This dual effect of EPO is based on EPO receptor (EPO-R) isoforms, which differ structurally and functionally from the hematopoietic EPO-R isoform. The tissue protective effects of EPO are based on its anti-apoptotic, anti-oxidative, anti-inflammatory, cell proliferative and angiogenic properties. Recent experimental and clinical studies have shown that EPO has also positive metabolic effects on hyperglycemia and diabetes, although these have not yet been fully delineated. Whether the tissue protective and metabolic effects of EPO could have clinical benefits, are important topics for future research in diabetic pregnancies.