Emerging erythropoiesis-stimulating agents

Chemical Protein Synthesis in Medicinal Chemistry

Although the majority of proteins used for biomedical research are produced using living systems such as bacteria, biological means for producing proteins can be advantageously complemented by protein semisynthesis or total chemical synthesis. The latter approach is particularly useful when the proteins to be produced are toxic for the expression system or show unusual features that cannot be easily programmed in living organisms. The aim of this review is to provide a wide overview of the use of chemical protein synthesis in medicinal chemistry with a special focus on the production of post-translationally modified proteins and backbone cyclized proteins.

A meta-analysis and systematic review evaluating the use of erythropoietin in total hip and knee arthroplasty

Purpose

The debate is still ongoing on the effectiveness and safety of erythropoietin (EPO) treatment in orthopedic surgeries. Specifically, previous studies have not compared the dynamic change of hemoglobin (Hb) levels between different transfusion methods. Besides, complications or side effects of this alternative have not been quantitatively analyzed. We conducted a meta-analysis and systemic review to evaluate the efficacy of EPO on Hb levels observed during the whole perioperative period as well as the volume of allogeneic blood transfusion (ABT), the risk of venous thromboembolism, and application frequency of ABT in hip and knee surgery.

Materials and methods

PubMed, Embase, Web of Science, and the Cochrane library were systematically searched from inception to November 2017. The data from randomized controlled trials were extracted and the risk of bias assessed using Cochrane’s Collaboration’s tool.

Results

Twenty-five randomized controlled trials involving 4,159 patients were included in this meta-analysis. EPO could reduce exposure to allogeneic blood transfused (odds ratio [OR] =0.42, P=0.001) and reduce the average volume of allogeneic blood transfused (OR = −0.28, P=0.002). When EPO and preoperative autologous blood donation (PABD) were compared, the use of EPO was associated with lower exposure to ABT (OR =0.48, P=0.03), but no significant decrease in the average volume of allogeneic blood transfused (OR = −0.23, P=0.32). The use of EPO was associated with a higher level of Hb with or without use of PABD at all the 4 time points (preoperation, 24–48 hours postoperation, 3–5 days postoperation, discharge of last observation) (P<0.0001), which means EPO could increase the level of Hb significantly during the perioperative period. The results also indicated EPO does not increase the risk of a venous thromboembolism event.

Conclusion

Preoperative administration of EPO was shown to generally increase Hb levels during the whole perioperative period; however, the extent of the positive effects varies with time points. Additionally, EPO minimizes the need for transfusion significantly in patients undergoing hip or knee surgery without increasing the chance of developing thrombotic complications. Therefore, EPO offers an alternative blood management strategy in total hip arthroplasty and total knee arthroplasty.

The effects of CoCl2 on HIF-1α protein under experimental conditions of autoprogressive hypoxia using mouse models

It is well known that cobalt chloride (CoCl2) can enhance the stability of hypoxia-inducible factor (HIF)-1α. The aim of this study is to detect the effect of CoCl2 on the hypoxia tolerance of mice which were repeatedly exposed to autoprogressive hypoxia. Balb/c mice were randomly divided into groups of chemical pretreatment and normal saline (NS), respectively injected with CoCl2 and NS 3 h before exposure to hypoxia for 0 run (H0), 1 run (H1), and 4 runs (H4). Western Blot, electrophoretic mobility shift assay (EMSA), extracellular recordings population spikes in area cornus ammonis I (CA 1) of mouse hippocampal slices and real-time were used in this study. Our results demonstrated that the tolerance of mice to hypoxia, the changes of HIF-1α protein level and HIF-1 DNA binding activity in mice hippocampus, the mRNA level of erythropoietin (EPO) and vascular endothelial growth factor (VEGF), and the disappearance time of population spikes of hippocampal slices were substantially different between the control group and the CoCl2 group. Over-induction of HIF-1α by pretreatment with CoCl2 before hypoxia did not increase the hypoxia tolerance.

Frequency of administration of erythropoiesis-stimulating agents for the anaemia of end-stage kidney disease in dialysis patients

BACKGROUND

The benefits of erythropoiesis-stimulating agents (ESA) for dialysis patients have been demonstrated. However, it remains unclear whether the efficacy and safety of new, longer-acting ESA given less frequently is equivalent to recombinant human erythropoietin (rHuEPO) preparations. This is an update of a review first published in 2002 and last updated in 2005.

OBJECTIVES

This review aimed to establish the optimal frequency of ESA administration in terms of effectiveness (correction of anaemia, and freedom from adverse events) and efficiency (optimal resource use) of different ESA dose regimens.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 21 March 2013 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised control trials (RCTs) comparing different frequencies of ESA administration in dialysis patients.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility, risk of bias and extracted data. Results were expressed as risk ratio (RR) or risk differences (RD) with 95% confidence intervals (CI) for dichotomous outcomes. For continuous outcomes the mean difference (MD) or standardised mean difference (SMD) with 95% confidence intervals (CI) was used. Statistical analyses were performed using the random-effects model.

MAIN RESULTS

This review included 33 studies (5526 participants), 22 of which were added for this update. Risk of bias was generally high; only nine studies were assessed at low risk of bias for sequence generation and 14 studies for allocation concealment. Although only four studies were placebo-controlled, all were considered to be at low risk of performance or detection bias because the primary outcome of haemoglobin level was a laboratory-derived assessment and unlikely to be influenced by lack of blinding. We found that 16 studies were at low risk of attrition bias and five were at low risk of selection bias; only one study reporting sources of support was not funded by a pharmaceutical company.We compared four different interventions: Continuous erythropoietin receptor agonists (CERA) versus other ESA (darbepoetin or rHuEPO); different frequencies of darbepoetin administration; darbepoetin versus rHuEPO; and different frequencies of rHuEPO administration.There were no significant differences in maintaining final haemoglobin between CERA administered at two weekly intervals (4 studies, 1762 participants: MD 0.08 g/dL, 95% CI -0.04 to 0.21) or four weekly intervals (two studies, 1245 participants: MD -0.03 g/dL, 95% CI -0.17 to 0.12) compared with rHuEPO administered at two to three weekly intervals. In one study comparing CERA administered every two weeks with darbepoetin administered once/week, there was no significant difference in final haemoglobin (313 participants: MD 0.30 g/dL, 95% CI 0.05 to 0.55). In comparisons of once/week with once every two weeks darbepoetin (two studies, 356 participants: MD 0.04 g/dL, 95% CI -0.45 to 0.52) and once every two weeks with monthly darbepoetin (one study, 64 participants: MD 0.40 g/dL, 95% CI -0.37 to 1.17) there were no significant differences in final haemoglobin levels. There was marked heterogeneity among studies comparing weekly darbepoetin with once every two weeks and was possibly related to different administration protocols. Eight studies compared weekly darbepoetin with rHuEPO given two to three times/week; no statistical difference in final haemoglobin was demonstrated (6 studies, 1638 participants: MD 0.02 g/dL, 95% CI -0.09 to 0.12). Fourteen studies compared different frequencies of rHuEPO. No statistical difference was demonstrated in final haemoglobin (7 studies, 393 participants: SMD -0.17 g/dL, 95% CI -0.39 to 0.05). Adverse events did not differ significantly within comparisons; however, mortality and quality of life were poorly reported, particularly in earlier publications.

AUTHORS' CONCLUSIONS

Longer-acting ESA (darbepoetin and CERA) administered at one to four week intervals are non-inferior to rHuEPO given one to three times/week in terms of achieving haemoglobin targets without any significant differences in adverse events in haemodialysis patients. Additional RCTs are required to evaluate different frequencies of ESA in peritoneal and paediatric dialysis patients and to compare different longer-acting ESA (such as darbepoetin compared with CERA).

Erythropoietin stimulation decreases hepcidin expression through hematopoietic activity on bone marrow cells in mice

Erythropoiesis-stimulating agents (ESA) are now central to the treatment of renal anemia and are associated with improved clinical outcomes. It is well known that erythropoietin (EPO) is a key regulator of erythropoiesis through its promotion of red blood cell production. In order to investigate the role of ESA on iron metabolism, we analyzed the regulation of the iron regulatory hormone hepcidin by ESA treatment in a bone marrow transplant model in mouse. After treating C57BL/6 mice with continuous erythropoietin receptor activator (C.E.R.A.), recombinant human epoetin-β (rhEPO), or recombinant human carbamylated epoetin-β (rhCEPO), we investigated serum hepcidin concentrations and parameters of erythropoiesis. Serum hepcidin concentrations after rhEPO treatment were analyzed in mice subjected to total body irradiation followed by bone marrow transplantation. C.E.R.A. administration caused long-term downregulation of serum hepcidin levels. Serum hepcidin levels in rhEPO-treated mice decreased significantly, whereas there was no change in rhCEPO-treated mice. The reduction in circulating hepcidin levels after rhEPO administration was not observed in irradiated mice. Finally, bone marrow transplantation recovered the response to rhEPO administration that downregulates hepcidin concentration in irradiated mice. These results indicate that ESA treatment downregulates serum hepcidin concentrations, mainly by indirect mechanisms affecting hematopoietic activity in bone marrow cells.

Demand-adapted regulation of early hematopoiesis in infection and inflammation

During systemic infection and inflammation, immune effector cells are in high demand and are rapidly consumed at sites of need. Although adaptive immune cells have high proliferative potential, innate immune cells are mostly postmitotic and need to be replenished from bone marrow (BM) hematopoietic stem and progenitor cells. We here review how early hematopoiesis has been shaped to deliver efficient responses to increased need. On the basis of most recent findings, we develop an integrated view of how cytokines, chemokines, as well as conserved pathogen structures, are sensed, leading to divisional activation, proliferation, differentiation, and migration of hematopoietic stem and progenitor cells, all aimed at efficient contribution to immune responses and rapid reestablishment of hematopoietic homeostasis. We also outline how chronic inflammatory processes might impinge on hematopoiesis, potentially fostering hematopoietic stem cell diseases, and, how clinical benefit is and could be achieved by learning from nature.