"Work presented in this dissertation demonstrates that red blood cells (RBCs) from patients with multiple sclerosis (MS) or type 1 diabetes (T1D) have an altered cell metabolism compared to healthy RBCs. An overview of each disease, along with implications of increased or decreased RBC metabolism and downstream events are presented here. Additional experiments investigated methods to increase or decrease the RBC metabolism in an effort to alleviate complications of each disease. Glucose transporter 1 (GLUT1) is the main glucose transporter on RBCs, and all metabolism within the RBC involves glucose. RBC GLUT1 content was used as a measure of RBC metabolism, and elevated RBC GLUT1 content is proposed to be associated with increased cell metabolism. RBCs obtained from MS patients contained 23.3 ± 4.8% more GLUT1 than control RBCs, while T1D RBCs contained 23.6 ± 4.2% less GLUT1 than control RBCs. Further studies evaluated the effects of various therapies on RBCs with respect to MS and T1D. Steroids are commonly prescribed to MS patients to manage exacerbations of the disease; however, hyperglycemic conditions often result. Evidence presented here using measurements of RBC adenosine triphosphate (ATP) release, suggests that the steroids estriol and prednisolone decrease RBC metabolism. ATP is a product of glycolysis, which utilizes the glucose transported into the cell to produce energy. While MS RBCs released 104 ± 18 nM more ATP than control RBCs, treatment with estriol or prednisolone significantly decreased the RBC ATP release, thought to correlate to RBC metabolism. RBC ATP release stimulates endothelial nitric oxide (NO) production in vivo, which is detrimental at the high levels seen in MS due to its toxicity to the blood brain barrier. Results presented here also suggest that RBCs treated with physiological levels of estriol or prednisolone significantly decrease the downstream endothelial NO production up to 30%, thought to correlate to decreased blood brain barrier damage in MS patients. Shear stress is a main mechanism of RBC ATP release; however, chemical stimulus also leads to RBC ATP release. Further studies investigated the effect steroids had on C-peptide and Zn2+ binding to RBCs, a proven chemical stimulus of RBC ATP release. Results suggest that RBC treatment with prednisolone decreased the Zn2+ binding from 1.99 ± 0.12 nM to 0.18 ± 0.30 nM, and decreased the C-peptide binding from 2.02 ± 0.22 nM to -0.47 ± 0.27 nM. It follows that any effect that C-peptide and Zn2+ have on RBCs is attenuated as their binding to RBCs is attenuated, such as ATP release. Further studies investigated T1D RBCs and a proposed therapy involving a complex of C-peptide, Zn2+, and albumin. T1D patients suffer from insufficient blood flow, and this work suggests that the complex of C-peptide, Zn2+, and albumin may enhance blood flow and alleviate T1D complications. Evidence is presented here showing that an increase in RBC ATP release (34 ± 1.5 nM increase), RBC GLUT1 content (25.5 ± 1.3% increase), RBC C-peptide binding (1.95 ± 0.14 nM increase), and RBC Zn2+ binding (2.26 ± 0.20 nM increase) is only measured when the full complex of C-peptide, Zn2+ and albumin is present. While T1D RBCs have a lower RBC metabolism at basal level, treatment with this complex is suggested to enhance RBC metabolism and ATP release leading to enhanced blood flow, which will greatly help with the treatment of T1D."--Pages ii-iii.
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