The Heparinoid Sevuparin Improves Anemia and Kidney Status in a Mouse Model of Chronic Kidney Disease

The control of systemic iron availability is essential to sustain the different needs of the body, without causing iron overload disease or deficiency (anemia) meaning that iron is highly regulated and the master regulator is hepcidin. High levels of hepcidin induce ferroportin degradation, inhibiting iron release from enterocytes and macrophages resulting in an internal iron deficiency, which underlies anemia of chronic diseases (ACD). Patients with chronic kidney disease (CKD) often have ACD due to a combination of inflammation, erythropoietin (EPO) insufficiency/unresponsiveness, elevated hepcidin levels, reduced kidney function and decreased iron availability. Treatments involve erythropoiesis-stimulating agents, that in a longer perspective often fail to ameliorate the anemia, highlighting the need for new therapeutic tools. Interestingly, it has been reported that hepcidin suppression improves anemia in rodent models of CKD, suggesting that normalising hepcidin levels may be a means to treat anemia in CKD and in general in ACD.

It is known that heparins are potent hepcidin suppressors; sevuparin, a novel, clinical stage, low-molecular weight heparinoid compound with substantially reduced anticoagulant activity is a promising candidate drug to control hepcidin expression in patients with CKD.

The authors previously found that sevuparin strongly suppressed basal, BMP6- and IL6-dependent hepcidin expression in vitro with a maximum effect after 6h (90% reduction) persisting for at least 16h. The hepcidin lowering effect of sevuparin was confirmed also in healthy mice. Furthermore, in healthy volunteers, a single dose of subcutaneous sevuparin caused a significant reduction of about 50% (3 mg/kg) and 80% (9 mg/kg) of serum hepcidin after 12 and 24h, respectively, providing a robust translational context to the sevuparin effects on hepcidin levels.

The aim of the present work was to investigate the effect of sevuparin on hepcidin, hemoglobin and the kidney status in a CKD mouse model of high hepcidin anemia. Mice fed with “adenine rich diet” (ARD) (0.2% adenine; 0.9% phosphorus; 0.6% calcium; 20% casein) developed moderate or severe signs of kidney damage as manifested by weight loss, increased serum creatinine, high hepcidin levels, low serum iron and anemia (hemoglobin ≤ 12.5 g/dL) after 7-9 weeks. After the onset of CKD, the mice were chronically treated with PBS or sevuparin (10 mg/kg/daily) subcutaneously for 3 or 6 weeks alone or in combination with erythropoietin (EPO) administered intraperitoneally (50 U/mouse twice a week in the first 3 weeks followed by 3 weeks and then 25 U/mouse once a week to simulate EPO hypo-responsiveness). Sevuparin was provided by Modus Therapeutics AB, Sweden, whereas EPO was used in the form of the commercially available darbapoietin alfa (ARANESP^®). Sevuparin treatment alone increased hemoglobin, hematocrit and weight (Hb 11-12 g/dL; Ht 20%; 22 g vs baseline values of Hb 9-10 g/dL; Ht 18%; 14.5 g PBS) with adjoining modest decreases of serum hepcidin and creatinine. The reduction of creatinine was supported by a concomitant improvement of the kidney status visible as a reduction of collagen deposits indicative of reduced fibrosis compared to the mice treated with PBS only.

The EPO/sevuparin combination showed a strong reduction from control of serum hepcidin levels (292 ng/mL vs 1382 ng/mL) after 3 weeks of treatment whereas after 6 weeks levels were increased up to 2000 ng/mL suggesting that the chronic treatment with EPO is not optimal, as observed in patients. Interestingly the concomitant benefit on anemia at 3w (about Hb 18 g/dL, Ht 54%) for the combination remained stable at 6w, further supported by the maintained high Ret-He (about 15.62 pg); suggesting a phased dependency on hepcidin in the development of CKD anemia. Furthermore, the improvement of the kidney status (histology and function) was also maintained throughout combination treatment.

Our data in this mouse CKD model add new insights to the role of hepcidin in the development of CKD anemia over time. Furthermore, the results are promising and support further mechanistic and clinical studies to elucidate the therapeutic role for sevuparin as a treatment in anemia of inflammatory and/or chronic diseases in monotherapy or in combination with EPO and to explore its role in kidney protection.