Emerging drug class may enhance red blood cell production in anemic patients

December 22, 2010

FINDINGS: By determining how corticosteroids act to increase production of red blood cell progenitors, Whitehead Institute researchers have identified a class of drugs that may be beneficial in treating some erythropoietin-resistant anemias. One such anemia is Diamond-Blackfan anemia (DBA), which is frequently treated with corticosteroids, despite their severe side-effects. The identified class of drugs may be able to treat other anemias, including those resulting from trauma, sepsis, malaria, kidney dialysis, and chemotherapy.

RELEVANCE: Some common anemias can be treated with the hormone erythropoietin (EPO), which stimulates red blood-cell production. However, certain anemias, including DBA, do not respond to EPO, creating a large unmet medical need.

CAMBRIDGE, Mass. (December 22, 2010) - By determining how corticosteroids act to promote red blood cell progenitor formation, Whitehead Institute researchers have identified a class of drugs that may be beneficial in anemias, including those resulting from trauma, sepsis, malaria, kidney dialysis, and chemotherapy.

Anemia occurs due to a breakdown in erythropoiesis, the multi-step process that creates red blood cells. Some common anemias can be treated with a recombinant form of the hormone erythropoietin (EPO), which normally stimulates red blood-cell production at a fairly early stage of erythropoiesis.

However, certain anemias fail to respond to EPO, creating a large unmet medical need. In the case of Diamond Blackfan anemia (DBA), patients lack a sufficient number of EPO-responsive cells. Instead, corticosteroids such as prednisone or prednisolone are used to treat DBA, although it has been unclear exactly how these agents affect erythropoiesis.

To see how corticosteroids are able to increase red blood cell counts, Johan Flygare, a postdoctoral researcher in the lab of Whitehead Institute Founding Member Harvey Lodish, purified two progenitors of red blood cells, called burst forming unit-erythroids (BFU-Es) and colony forming unit-erythroids (CFU-Es), from mouse fetal liver cells. During erythropoiesis, BFU-Es produce CFU-Es, which are then stimulated by EPO to generate the pro-erythroblasts that eventually become red blood cells. By dividing numerous times before maturing, both BFU-Es and CFU-Es have a limited ability to self-renew. When Flygare exposed BFU-Es and CFU-Es in vitro to a corticosteroid, only the BFU-Es responded--dividing 13 times instead of the usual 9 times before maturing into CFU-Es. These additional cell divisions ultimately led to a 13-fold increase in red blood-cell production.

Flygare identified 83 genes in BFU-Es that are stimulated by the corticosteroid, and he examined the promoters that facilitate those genes' transcription. The promoters appeared to have binding sites for a transcription factor, called hypoxia-induced factor 1-alpha (HIF1-alpha), that is activated when an organism is deprived of oxygen. To prolong the 83 genes' promotion by HIF1-alpha, Flygare used a class of drugs known as prolyl hydroxylase inhibitors (PHIs), which extends HIF1-alpha's effectiveness. PHIs have also been used in early-stage clinical trials to increase EPO production.

When Flygare added both a corticosteroid and a PHI to BFU-Es in culture, the cells produced 300 times more red blood cells than did cells without exposure to the drugs. Flygare repeated the experiment with adult human BFU-Es, and found that a corticosteroid plus a PHI generated 10 times more red blood cells than BFU-Es exposed to a corticosteroid alone.

Flygare hopes this research eventually leads to improved treatment for DBA patients who currently suffer from a host of corticosteroid-induced side effects, including decreased bone density, immunosuppression, stunted growth, and cataracts.

"If you could lower the dose of steroids so DBA patients would get just a little bit, and then add on this kind of drug, like a PHI, that would boost the effect, maybe you could get around the steroids' side effects," says Flygare. "That would be good."

This new approach to increasing erythropoiesis by extending the self-renewal of BFU-Es--resulting in creation of more EPO-responsive cells--could lead to novel therapies for other anemias.

"There are a number of anemias that are much more prevalent than DBA and that cannot be treated with EPO, either, such as anemias from trauma, sepsis, malaria, and anemia in kidney dialysis patients," says Lodish, who is also a professor of biology and bioengineering at MIT. "Whether these treatments will work in those conditions remains to be seen."
-end-
This research was supported by the Diamond Blackfan Anemia Foundation, the Swedish Research Council, Maja och Hjalmar Leanders Stiftelse, The Sweden-America Foundation, and the National Institutes of Health (NIH).

Written by Nicole Giese

Harvey Lodish's primary affiliation is with Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also a professor of biology and a professor of bioengineering at Massachusetts Institute of Technology.

Full Citations:

"HIF-1 Alpha synergizes with glucocorticoids to promote BFU-E progenitor self-renewal"

Blood, published online the week of December 22, 2010

Johan Flygare (1), Violeta Rayon Estrada (1), Chanseok Shin (1, 2), Sumeet Gupta (1), and Harvey F. Lodish (1, 3, 4).

1. Whitehead Institute for Biomedical Research, Cambridge, MA 02142
2. Department of Agricultural Biotechnology, Seoul National University, Seoul, 151-921, Republic of Korea
3. Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA

Whitehead Institute for Biomedical Research

Related Malaria Articles from Brightsurf:

Clocking in with malaria parasites
Discovery of a malaria parasite's internal clock could lead to new treatment strategies.

Breakthrough in malaria research
An international scientific consortium led by the cell biologists Volker Heussler from the University of Bern and Oliver Billker from the UmeƄ University in Sweden has for the first time systematically investigated the genome of the malaria parasite Plasmodium throughout its life cycle in a large-scale experiment.

Scientists close in on malaria vaccine
Scientists have taken another big step forward towards developing a vaccine that's effective against the most severe forms of malaria.

New tool in fight against malaria
Modifying a class of molecules originally developed to treat the skin disease psoriasis could lead to a new malaria drug that is effective against malaria parasites resistant to currently available drugs.

Malaria expert warns of need for malaria drug to treat severe cases in US
The US each year sees more than 1,500 cases of malaria, and currently there is limited access to an intravenously administered (IV) drug needed for the more serious cases.

Monkey malaria breakthrough offers cure for relapsing malaria
A breakthrough in monkey malaria research by two University of Otago scientists could help scientists diagnose and treat a relapsing form of human malaria.

Getting to zero malaria cases in zanzibar
New research led by the Johns Hopkins Center for Communication Programs, Ifakara Health Institute and the Zanzibar Malaria Elimination Program suggests that a better understanding of human behavior at night -- when malaria mosquitoes are biting -- could be key to preventing lingering cases.

Widely used malaria treatment to prevent malaria in pregnant women
A global team of researchers, led by a research team at the Liverpool School of Tropical Medicine (LSTM), are calling for a review of drug-based strategies used to prevent malaria infections in pregnant women, in areas where there is widespread resistance to existing antimalarial medicines.

Protection against Malaria: A matter of balance
A balanced production of pro and anti-inflammatory cytokines at two years of age protects against clinical malaria in early childhood, according to a study led by ISGlobal, an institution supported by ''la Caixa'' Foundation.

The math of malaria
A new mathematical model for malaria shows how competition between parasite strains within a human host reduces the odds of drug resistance developing in a high-transmission setting.

Read More: Malaria News and Malaria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.