Research

Anemia of Chronic Inflammation Caused by Hepcidin

Hepcidin is an iron regulatory hormone induced by inflammation that degrades the iron transport protein ferroportin. Hepcidin causes a condition known as anemia of chronic inflammation. Ferroportin is required to transport iron into the bloodstream from the intestinal cells that absorb iron from the diet. Ferroportin also exports iron from the liver, and spleen into the bloodstream where transferrin binds iron and delivers iron to the bone marrow for red blood cell synthesis. The Watt Lab has identified hepcidin inhibitors that prevent hepcidin production and stabilize ferroportin. Studies in rats show that iron delivery to the bone marrow is restored using these hepcidin inhibitors.

Inflammation produces hepcidin that binds to and degrades ferroportin. This stops iron delivery to the bone marrow. Inflammation also blocks EPO production and secretion from the kidneys. Combined, these effects decrease red blood cell synthesis.

Furin inhibitor effect. Furin inhibitors block hepcidin production so ferroportin is not degraded. Iron is released from the liver and loads transferrin for iron delivery to the bone marrow. Depending on the cytokines that triggered the inflammatory process EPO may be present or ESA drugs may be required to stimulate red blood cell synthesis.

Inhibitors of Iron Binding Proteins

The Watt Lab has focused on metabolites that build up in diseases with oxidative stress. Watt students have identified metabolites that disrupt iron loading into ferritin and transferrin. In Chronic kidney disease, serum phosphate levels increase because the kidneys are not properly filtering phosphate from the bloodstream. Watt students have also demonstrated that elevated phosphate inhibits iron loading into ferritin and transferrin by forming insoluble iron phosphate complexes. The Watt Lab Group is now focusing on other elevated metabolites to determine if they also disrupt normal iron loading or release of iron from ferritin or transferrin.

As Fe³⁺ is exported from the cell into the bloodstream it encounters a variety of serum molecules that can react with Fe³⁺ and form complexes that are not substrates for loading into apo transferrin. This work shows that citrate and albumin can prevent these dangerous side reactions and mediate iron delivery to apo transferrin to prevent the formation of non-transferrin bound iron.

Alzheimer’s Disease

Iron dysregulation is intimately connected to Alzheimer’s disease (AD) but the direct connections are not clear. A new hypothesis relating to homocysteine disrupting iron loading into ferritin might explain the elevated cytosolic iron and oxidative stress. The inability to load iron into ferritin results in elevated cytosolic iron which upregulates expression of the Amyloid Precursor Protein (APP). Homocysteine also inhibits the phosphatase that dephosphorylates tau leading to elevated hyper-phosphorylated tau and tau tangles. In collaboration with Dr. Jonathan Wisco in the BYU PDBio department, the Watt Lab is testing this hypothesis.

Diagnostics

For each of the situations outlined above, Watt researchers are developing point of care diagnostic methods to evaluate known biomarkers. The goals of the diagnostics research are two-fold. First, the Watt Lab is modifying and developing new methods related to antibody detection methods to provide increased sensitivity for this type of analysis. The Watt Lab also focuses on particular biomarkers that give diagnostic information to aid clinical practitioners identify the most beneficial and effective treatment.