Mechanisms Of Intestinal Iron Absorption And Consequences Of Iron Supplementation During The Perinatal Period
Funder
National Health and Medical Research Council
Funding Amount
$526,878.00
Summary
Iron intake is particularly high during pregnancy and in the newborn to meet the requirements of the growing fetus and neonate. While it is widely recommended that women take iron supplements at this time, too much iron may adversely affect pregnancy outcome. The aim of this study is to understand the factors controlling iron intake in the perinatal and the consequences of excess iron. This will provide the physiological information required to make rational decisions about iron supplementation.
The Mechanism Of Intestinal Haem Iron Absorption And Characterization Of A Novel Haem-binding Protein
Funder
National Health and Medical Research Council
Funding Amount
$537,773.00
Summary
Iron is essential for normal health as many important proteins in the body require iron to function properly (e.g. haemoglobin). However, too much iron can be toxic, so the body must keep its iron content within defined limits. The amount of iron in the body is determined at the point of absorption from the diet in the small intestine. If too little iron is absorbed, then anaemia can result. If too much iron is absorbed, as is the case in the common disease haemochromatosis (with approximately 1 ....Iron is essential for normal health as many important proteins in the body require iron to function properly (e.g. haemoglobin). However, too much iron can be toxic, so the body must keep its iron content within defined limits. The amount of iron in the body is determined at the point of absorption from the diet in the small intestine. If too little iron is absorbed, then anaemia can result. If too much iron is absorbed, as is the case in the common disease haemochromatosis (with approximately 1 in 200 Australians at risk) then the body becomes iron loaded and various organs, particularly the liver, can become damaged. An understanding of how iron is absorbed will place us in a much better position to treat diseases such as this. Iron is present in the diet in two forms - inorganic iron and haem iron. Inorganic iron is the main form of iron in foods of plant origin while most haem iron comes from meat. In a typical diet 80-90% of the iron is inorganic iron and only 10-20% is haem. Despite this, 30-50% of the iron taken into the body comes from haem, so haem iron absorption is particularly efficient. While we have learned a great deal about the mechanims by which inorganic iron is absorbed in recent years, we know very little about the absorption of haem iron, so that is the focus of this project. We will study the pathway by which haem enters the body, how this process is regulated, and the characteristics of haem binding to the cells lining the small intestine. These cells are responsible for the uptake of all nutrients from the diet. In particular, we will examine the biology of a recently identified protein known as HCP1. Preliminary evidence suggests that HCP1 could be the main protein enabling haem to be taken up by intestinal cells. These studies will enhance our knowledge of an important nutritional pathway and improve our capacity to treat diseases such as haemochromatosis where iron absorption is defective.Read moreRead less
The Role Of Transferrin Receptor, Divalent Metal Transporter, Ferroportin And Hemochromatosis Protein In Iron Absorption
Funder
National Health and Medical Research Council
Funding Amount
$195,990.00
Summary
Within Australia 1 in 300 people of Caucasian origin have a genetic defect which makes them absorb more iron from the diet than they need. Excess iron is a major problem because it damages cells and this is most obvious in the pancreas where the cells make insulin are destroyed and diabetes mellitus develop. In the liver cirrhosis and cancer often occur. Iron also accumulates in other tissues such as the heart and joints resulting in damage to these organs. The genetic defect has recently been i ....Within Australia 1 in 300 people of Caucasian origin have a genetic defect which makes them absorb more iron from the diet than they need. Excess iron is a major problem because it damages cells and this is most obvious in the pancreas where the cells make insulin are destroyed and diabetes mellitus develop. In the liver cirrhosis and cancer often occur. Iron also accumulates in other tissues such as the heart and joints resulting in damage to these organs. The genetic defect has recently been identified but how the defective protein causes the cells of the intestine to absorb more iron into the body than is needed remains unknown. This has led to the idea that the normal protein is responsible for controlling the amount of iron absorbed. Recent studies have shown a link between this protein and another called transferrin receptor. These two molecules are thought to co-operate in determining how much iron will be absorbed. Once this is determined other molecules called iron transporters are produced and these are responsible for moving the iron from the intestine into the blood. When not much iron is required only a small number of transporters are made and when more iron is required then many more are produced. How these transporters program the level of iron absorption is unknown but the process probably involves the transferrin receptor and the hemochromatosis protein. This project will investigate the function of the molecules that determine the programe for how much iron is to be absorbed, and secondly how this is linked to the production and movement of the transproters that co-ordinate this function.Read moreRead less
The Pathogenesis Of Haemochromatosis In The HFE Knockout Mouse Model
Funder
National Health and Medical Research Council
Funding Amount
$244,616.00
Summary
Hereditary haemochromatosis is a very common genetic disease that affects approximately 1 in 200 Australians. It alters the way the body uses iron. It causes an increase in absorption of dietary iron and increased deposition of iron in major organs of the body such as the liver, heart and pancreas. This iron is harmful to tissues in the body and may lead to the development of liver cirrhosis, heart disease, diabetes and malignancy. The gene that is defective in hereditary haemochromatosis patien ....Hereditary haemochromatosis is a very common genetic disease that affects approximately 1 in 200 Australians. It alters the way the body uses iron. It causes an increase in absorption of dietary iron and increased deposition of iron in major organs of the body such as the liver, heart and pancreas. This iron is harmful to tissues in the body and may lead to the development of liver cirrhosis, heart disease, diabetes and malignancy. The gene that is defective in hereditary haemochromatosis patients has been identified and called HFE however, the function of HFE is not known. Recently, an excellent laboratory model of this disease has been developed. We aim to use this model to show for the first time how HFE controls the amount of iron the body absorbs and how much iron is delivered to tissues such as the liver. We also aim to identify how these processes are impaired in hereditary haemochromatosis patients. From this study, we will gain a better understanding of the role of HFE in iron metabolism of normal and hereditary haemochromatosis patients and this will provide opportunities for the development of new therapies for the prevention or treatment of iron overload.Read moreRead less
Iron Metabolism And The Cirrhotic Liver:studies On Iron Absorption And Hepatic Iron Kinetics
Funder
National Health and Medical Research Council
Funding Amount
$256,980.00
Summary
Patients with liver disease awaiting liver transplantation often have excess iron in the liver that aggravates the existing liver disease. We have shown that patients with cholestatic liver disease, (due to poor bile excretion), do not have much iron in the liver compared to those patients with hepatocellular cirrhosis, (where the liver cells are damaged). Why this is so is unknown. Iron is normally absorbed from the diet by with the help of special molecules in the small intestine, carried in t ....Patients with liver disease awaiting liver transplantation often have excess iron in the liver that aggravates the existing liver disease. We have shown that patients with cholestatic liver disease, (due to poor bile excretion), do not have much iron in the liver compared to those patients with hepatocellular cirrhosis, (where the liver cells are damaged). Why this is so is unknown. Iron is normally absorbed from the diet by with the help of special molecules in the small intestine, carried in the blood to the liver where it is used by the cells. We would like to study how the proteins that transport iron in the intestine function and see if this is a different in disease. We would also like to examine exactly which molecules are important in depositing iron in the liver in patients with cirrhosis. We will work on animal models of liver disease as well as humans. We will treat animals so that they have liver disease that resembles human subjects with cirrhosis. These treatments include (1) feeding the animals carbon-tetrachloride, a toxin which damages the liver cells and therefore causes hepatocellular liver injury, and (2) tying the bile duct which stops the flow of bile and this results in cholestatic liver injury. It is known which proteins takes iron into the normal liver cells but no one knows which molecules transport the iron in liver disease. We think they may be different, because when the liver becomes diseased, scarring occurs this results in cirrhosis. Molecules that could easily enter liver cells may now be too big to pass through the openings. These studies are important since they will suggest new treatments to patients with liver disease who are awaiting a liver transplant and the treatment will probably differ depending on which type of liver disease the patient has.Read moreRead less
Red Cell Disorders And The Regulation Of Iron Homeostasis
Funder
National Health and Medical Research Council
Funding Amount
$605,096.00
Summary
Iron is an essential nutrient, but it is also toxic when present in excess, so the amount of iron moving into and around the body must be tightly controlled. In this project we will investigate how this body iron movement is regulated, and in particular the role played by macrophages, the cells that clean up old red blood cells. An understanding of this process will be of great benefit in the analysis and treatment of important blood diseases and disorders of iron metabolism.