Garlic accelerates red blood cell turnover and splenic erythropoietic gene expression in mice: evidence for erythropoietin-independent erythropoiesis

Garlic (Allium sativum) has been valued in many cultures both for its health effects and as a culinary flavor enhancer. Garlic's chemical complexity is widely thought to be the source of its many health benefits, which include, but are not limited to, anti-platelet, procirculatory, anti-inflammatory, anti-apoptotic, neuro-protective, and anti-cancer effects. While a growing body of scientific evidence strongly upholds the herb's broad and potent capacity to influence health, the common mechanisms underlying these diverse effects remain disjointed and relatively poorly understood. We adopted a phenotype-driven approach to investigate the effects of garlic in a mouse model. We examined RBC indices and morphologies, spleen histochemistry, RBC half-lives and gene expression profiles, followed up by qPCR and immunoblot validation. The RBCs of garlic-fed mice register shorter half-lives than the control. But they have normal blood chemistry and RBC indices. Their spleens manifest increased heme oxygenase 1, higher levels of iron and bilirubin, and presumably higher CO, a pleiotropic gasotransmitter. Heat shock genes and those critical for erythropoiesis are elevated in spleens but not in bone marrow. The garlic-fed mice have lower plasma erythropoietin than the controls, however. Chronic exposure to CO of mice on garlic-free diet was sufficient to cause increased RBC indices but again with a lower plasma erythropoietin level than air-treated controls. Furthermore, dietary garlic supplementation and CO treatment showed additive effects on reducing plasma erythropoietin levels in mice. Thus, garlic consumption not only causes increased energy demand from the faster RBC turnover but also increases the production of CO, which in turn stimulates splenic erythropoiesis by an erythropoietin-independent mechanism, thus completing the sequence of feedback regulation for RBC metabolism. Being a pleiotropic gasotransmitter, CO may be a second messenger for garlic's other physiological effects.     

Biogenesis of the red cell membrane and cytoskeletal proteins during erythropoiesis in vitro

Purified erythroid progenitor cells (CFU-E) were used to study in vitro the production of the proteins present in the plasma membrane and the membrane skeleton. At different stages of erythropoiesis incorporation of [35S]methionine was measured and membranes were isolated. Whereas incorporation in the total protein mass of the cells increased during erythropoiesis, the labeling of the membrane protein fraction decreased. The major erythrocyte membrane proteins were synthesized already in the CFU-E and continued to be made till the orthochromatic erythroblast stage. Band 3 protein, however, was made at a much lower rate. The incorporation in the late stages was only 5% of that in the CFU-E. The major changes in the protein composition of the membrane and its adherent skeleton occurred at the enucleation step.     

The utilization of senescent red cell and hemolysate iron for erythropoiesis.

We report experiments to determine the availability for new hemoglobin production of radioiron from nonviable red cells at various times after deposition in the reticulo-endothelial system and to determine the relative availability of radioiron derived from hemolysates versus that derived from nonviable red cells. When heated nonviable red cells labeled with 59Fe are injected into polycythemic mice the iron is deposited in the reticulo-endothelial system, and less than 1% of it is reutilized for hemoglobin synthesis. If the polycythemic mice are given nonviable red cells 48 hours after exposure to hypoxia, when hemoglobin synthesis is maximal, 25% of the iron is reutilized. When the cells are given 36 hr after exposure to hypoxia, iron reutilization declines to 16%, and when exposure to hypoxia is further delayed, reutilization of the iron falls to a plateau level of 11%. Radioiron from hemolysates, primarily deposited in parenchymal cells of the liver, is less available for new hemoglobin synthesis than is radioiron from nonviable red cells, which is primarily deposited in Kupffer cells of the liver. When transferrin-bound iron is given to polycythemic mice, this iron is also deposited in parenchymal cells of the liver and is also less available for new hemoglobin synthesis. Thus, in relation to an erythropoietic stimulus, the site and time of deposition of iron influence its accessibility for erythropoiesis.     

Rabbit red blood cell hexokinase

Summary Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in reticulocytes as two distinct molecular forms, designated hexokinase Ia and Ib, but only one of these was consistently present in mature red cells. In vivo, hexokinase la and Ib show a decay rate of 3 and 8% a day, respectively, while in vitro they show a similar stability.The possibility that the proteolytic activities of the reticulocyte could be responsible for the fast decay of hexokinase was investigated. No differences were found in the decay rates of hexokinase la and Ib during in vitro reticulocyte maturation in presence or absence of proteolytic inhibitors. Contrariwise, many findings indicate the ATP-dependent proteolytic system of the reticulocyte as a possible mechanism. In fact, the decay of hexokinase and the degradation of 3H-globins are both stimulated by ATP and ubiquitin; they show similar kinetic properties and both disappear during reticulocyte maturation.The cellular localization of hexokinase la and Ib was shown to be responsible for the differences found between their decay rates.Abbreviations PMSF phenylmethylsulfonyl fluoride - TPCK 1-1-tosylamide-2-phenylethyl-chloromethyl ketone - TLCK N -p-tosyl-L-lysine chloromethyl ketone     

Serum protein and red cell enzyme polymorphisms in affective disorders

Frequencies of serum groups (Hp and Gc) and red cell enzyme types (PGM1, 6-PGD and ES D) were studied in 195 patients with affective disorders. The patients were classified into four groups: (1) bipolar (manic-depressive) psychosis; (2) unipolar, recurrent, depressive psychosis; (3) non-psychotic reactive depression, and (4) unclassifiable. The Hp2 gene was increased in reactive and unclassifiable patients, the PGM1 1 gene was increased in bipolar patients and the ES D1 gene in reactive patients. No associations were found between affective disorders and the Gc and 6-PGD systems.     

Abnormal blood flow and red blood cell deformability in severe malaria

Obstruction of the microcirculation plays a central role in the pathophysiology of severe malaria. Here, Arjen Dondorp and colleagues describe the various contributors to impaired microcirculatory flow in falciparum malaria: sequestration, rosetting and recent findings regarding impaired red blood cell deformability. The correlation with clinical findings and possible therapeutic consequences are discussed.     

Cyclic red blood cell destruction in thalassemia

A retrospective analysis of time series of hemoglobin (Hb) destruction of 24 children (11 males and 13 females) with thalassemia from the age of 6 to 12 years showed that the Hb destruction rate typically oscillated with an average period of 50 days. A possible relation between the periodism and the severity of the disease is also suggested. (Chronobiology International, 18(4), 729-736, 2001)     

Human red blood cell polymorphisms and malaria

Genetic factors are a major determinant of child survival in malaria endemic countries. Identifying which genes are involved and how they affect the malaria disease risk potentially offers a powerful mechanism through which to learn more about the host-parasite relationship. The past few years have seen significant progress towards achieving this goal for some of the best-known malaria resistance genes that determine the structure or function of red blood cells: Gerbich blood group antigen negativity; polymorphisms of the complement receptor genes (most notably CR1); Southeast Asian ovalocytosis; pyruvate kinase deficiency; haemoglobin E; the sickle cell trait; and alpha-thalassaemia are all examples. The challenge for the future must be to translate such advances into fresh approaches to the prevention and treatment of malaria.     

Malaria proteases and red blood cell invasion

Studies of malaria proteases have focused on two general groups, corresponding to activities specific to malaria parasites: (1) proteases involved in hemoglobin degradation which are active in the food vacuole and which exhibit optimal activity at low pH; and (2) proteases specific to schizonts and/or merozoites which are involved in merozoite maturation and red blood cell invasion and which exhibit optimal activity at neutral pH. In this paper, Catherine Braun Breton and Luis H. Pereira da Silva will focus on those activities necessary for the release of infectious merozoites and the entry of the parasite into its host cell.