Serum erythropoietin levels in hemodialysed patients after administration of recombinant human erythropoietin

The Effect of Recombinant Human Erythropoietin on Bacterial Growth: A Dual-Edged Sword

Background

Hypererythropoietinemia is associated with common diseases like non-uremic anaemia where infection burden is high. Erythropoietin (EPO) is also given as therapy for anaemia associated with chronic kidney disease and cancer and in those who are at a higher risk of infections. EPO is known to have an effect on macrophages by which it helps in the growth of some intracellular pathogens. However, its direct role on bacterial growth is currently unknown.

Summary

Here, we investigated the direct effect of recombinant human erythropoietin (rhuEPO) on the growth of pathogenic Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. In silico experiments were designed to gain insight into the mechanisms. We found that 30 IU/L rhuEPO promoted the growth of E. coli and S. aureus and inhibited the growth of P. aeruginosa. In silico observations suggest that bacterial cell surface proteins may interact with the EPO and may cause the observed effects.

Key Message

It appears that some pathogens can explore EPO to proliferate and growth of others are inhibited by the same. The consequence of such observation is a matter of widespread concern for future research.

Effect of long-term administration of recombinant human growth hormone (rhGH) on plasma erythropoietin (EPO) and haemoglobin levels in anaemic patients with adult GH deficiency

OBJECTIVE

We investigated the effect of recombinant human GH (rhGH) on erythropoietin (EPO) and haemoglobin (Hb) concentrations in anaemic patients with adult GH deficiency.

PATIENTS AND DESIGN

rhGH was administrated in 8 patients with adult GH deficiency, three males and five females, aged from 24 to 69 years, mean (+/- SD) of 48.8 +/- 16.4 years, for 1 year by means of continuous subcutaneous infusion (CSI) at a flow rate of 0.036 U/kg/day using a portable syringe pump. Blood samples were obtained in the morning after an overnight fast every week for 1 month, followed by each month before and after the start of rhGH administration.

RESULTS

Mean (+/- SE) plasma GH levels increased from 0.24 +/- 0.09 microg/l to 2.32 +/- 0.23 microg/l 1 week after the start of rhGH administration to maintain a steady state. Plasma IGF-I levels increased from 70.1 +/- 13.8 microg/l to 282.8 +/- 70.6 microg/l 1 week after the start of rhGH administration to maintain the steady state. Plasma EPO levels increased from 25.9 +/- 2.6 IU/l to 37.6 +/- 4.2 IU/l and 34.3 +/- 3.6 IU/l at 1 week and 2 weeks after the start of rhGH administration, respectively, and then decreased gradually to 14-9 +/- 2.1 IU/l at 10 months after the start of rhGH administration. Reticulocyte counts increased from 0.88 +/- 0.06% to 1.49 +/- 0.21% at 1 week. Hb concentrations increased from 103 +/- 5 g/l to 106 +/- 5 g/l at 2 weeks after the start of rhGH administration, and then increased gradually to reach the normal range.

CONCLUSIONS

We conclude that EPO secretion was stimulated in the initial 2 weeks after the start of CSI of rhGH in anaemic patients with adult GH deficiency. Increased Hb concentrations after long-term administration of rhGH might be explained by direct stimulatory effects of rhGH and IGF-I on erythroid cells, which was accompanied by suppressed EPO secretion, in combination with a more generalized indirect impact of rhGH on physical activety. These findings suggest a beneficial effect of rhGH replacement in anaemic patients with adult GH deficiency.

Effect of long-term treatment with recombinant human growth hormone on erythropoietin secretion in an anemic patient with panhypopituitarism

We studied the effect of treatment with recombinant human GH in an anemic patient with panhypopituitarism in which hemoglobin (Hb) concentration remained as low as 11.0 g/dl in spite of appropriate replacement with thyroid and adrenocortical hormones. Recombinant human GH was subcutaneously and constantly infused for 12 months using a portable syringe pump at a rate of 0.25 U/kg/week. After the treatment with human GH plasma erythropoietin (EPO) levels increased from 12.2 to 25.1 mIU/ml, with a concomitant increase of Hb concentration to 13.6 g/dl. When the administration of human GH was interrupted, both plasma EPO levels and Hb concentrations decreased. There was a close correlation between plasma GH and EPO levels before and during the human GH administration (y=2.444x+1 3.423, r=0.641, p<0.05). Plasma GH levels were well correlated with Hb concentrations before and during human GH administration (y=0.529x+11.313, r=0.690, p<0.01). Plasma IGF4 levels were also correlated with Hb concentrations (y=0.007x+10.874, r=0.832, p<0.001), but not with plasma EPO levels. These findings suggest that GH treatment may be useful in anemic patients with panhypopituitarism.

Decreasing reticulocyte counts associated with declining post-dose erythropoietin plasma levels in anaemia of prematurity

A prospective sequential, multicentre trial was conducted to determine the association between erythropoietin (EPO) plasma levels and the erythropoietic response to recombinant human erythropoietin (r-HuEPO) during long-term treatment of premature infants. Twenty-nine infants, gestational ages 26-34 weeks and postnatal ages more than 14 days, received 600 IU r-HuEPO per kg per week divided into three doses subcutaneously for haemoglobin levels less than 120 g/l or haematocrit less than 36% over a period of 4 weeks. Eight additional patients were studied for a total of 10 weeks. EPO plasma concentrations and haematologic parameters were measured prior to the onset of treatment and at 2-weekly intervals thereafter. Treatment with r-HuEPO resulted in a median increase in corrected reticulocyte counts of 2.5% (range 0.2-4.6%) above patient's baseline, thereafter a decrease was observed. In the 8 patients followed for 10 weeks reticulocyte counts declined significantly during weeks 6-10 when compared with the first 4 weeks (p < 0.005). Median 72-hour post-dose EPO plasma levels increased significantly (p < 0.0001) to 57.3 mU/ml (range 5.0-160) above patient's baseline after the first injection, but declined progressively thereafter until they approached baseline values at week 10.

CONCLUSION

R-HuEPO treatment after the first month was associated with a decrease in post-injection plasma levels and a decrease in erythropoietic response. This decrease in erythropoietin's efficacy and the decline observed in post-dose EPO plasma levels may be causally related.

Inadequate erythropoietin response to anemia: definition and clinical relevance

The development of a specific and sensitive immunoassay for the measurement of serum erythropoietin (s-Epo) allows to improve our understanding of the model of in vivo regulation of erythropoiesis. In most anemias, circulating hemoglobin level determines Epo production which in turn stimulates erythropoietic activity. The disruption of the expected feedback mechanism of Epo production leads to an inadequately low s-Epo. The definition of inadequate Epo response to anemia relies on the documentation of a downregulated dependence of s-Epo on Hb with respect to the same dependence in patients with a physiologically regulated erythropoiesis. Literature reports a wide range of so called adequate s-Epo response to anemia and a number of criteria for judging on the adequateness of s-Epo at a certain degree of anemia. The O/P (observed/predicted) ratio allows categorization of each individual patient. The clinical syndromes in which an inadequate Epo response has been reported are numerous and the mechanisms of defective Epo production are different. A number of evidences clearly point to a relation between responsiveness to r-Hu-Epo and inadequate Epo response. This inequivocabily confirms the role inadequate Epo response plays in the pathogenesis of anemia.