We are entering an exciting new age in drug discovery and pharmacology. Biophysics, structural biology and physiology have all merged into a multi-discipline approach for developing and testing novel pharmaceutical agents. My laboratory investigates the mechanisms by which "4F," an apo A-I mimetic, decreases inflammation and improves vascular function. Apo A-I mimetics are small peptides that are designed to improve high-density lipoprotein (HDL) function. The apo A-I mimetic, 4F, exhibits powerful anti-inflammatory properties that we have shown improves vascular function in murine models of atherosclerosis, sickle cell disease, systemic sclerosis and asthma. Treatment of different murine models of vascular disease reveals that this small peptide increases vasodilation, promotes regression of existing lesions, inhibits influenza-induced macrophage infiltration of the vessel wall and inhibits inflammation surrounding brain microvessels which is hypothesized to improve cognitive function in hypercholesterolemic mice.
Recently we showed that D-4F restores vasodilation and inhibits vessel wall thickening in a murine model of hypercholesterolemia without lowering plasma cholesterol. In a murine model of sickle cell disease, we showed that D-4F improved vasodilation and limited the effects of ischemia/reperfusion injury of the liver. Such protection reduces the release of xanthine oxidase and actually helps protect vascular endothelial cells of the lung against increased oxidative stress. In an established murine model of scleroderma we showed that D-4F inhibited the formation of angiostatin in the hearts of the mice. Such changes correlated with marked increases in VEGF-stimulated angiogenesis and, in flow and endothelium- and eNOS-dependent vasodilation. Finally, we have used D-4F to decrease airway inflammation and improve airway reactivity in a murine model of asthma. The fact that this small peptide is able to decrease inflammation and improve vascular and pulmonary function in such diverse disease states suggests that it is targeting a mechanism that is likely fundamental to all forms of vascular disease.
My laboratory investigates mechanisms of vascular function with respect to the cell biology of endothelial nitric oxide synthase (eNOS). Our goal is to understand and define the cellular mechanisms governing nitric oxide and superoxide anion from eNOS itself. We use several transgenic and gene knock-out mice as murine models of disease and to test specific mechanisms impairing vasodilation. On the basis that D-4F rearranges HDL to isolate and remove lipid hydroperoxides from the HDL particle, we think that proinflammatory lipids generated during disease play critical roles in inhibiting vascular function; and, that these proinflammatory lipids, in turn, accelerate and enhance the disease process. Although we do not know exactly how D-4F and other apo A-1 mimetics work, we hypothesis that they restore vascular function in at least two ways; 1) by directly interacting with the vessel wall and 2) indirectly by improving HDL function, which, in turn, improves vascular health by decreasing inflammation of the vessel wall. Accordingly, one of the goals of my laboratory is determine if, and the extent to which, D-4F and other apo A-1 mimetics improve vascular function by these two distinct mechanisms.
My laboratory is pursuing these hypotheses in murine models of hypercholesterolemia, sickle cell disease, systemic sclerosis and asthma. As oxidative stress is well know to impair HDL function, targeting HDL may be an important new avenue for treating autoimmunity, rheumatoid arthritis, pulmonary disease, as well as sickle cell disease, hypercholesterolemia, systemic sclerosis and asthma. We are seeking active collaborations with physicians who treat children and adult patients with these diseases. It is our hope to establish a strong basic science program in each disease state. From there upon which we will be able to build translational programs to treat vascular disease in humans. The possibilities for apo A-1 mimetics to improve vascular function appear to be endless at this point.
Recent Publications
Sander TL, Noll L, Klinkner DB, Weihrauch D, He BJ, Kaul S, Zangwill SD, Tweddell JS, Pritchard Jr KA, Oldham KT. Rosiglitazone antagonizes vascular endothelial growth factor signaling and nuclear factor of activated T cells activation in cardiac valve endothelium. Endothelium, 2006, 13(3):181-90.
Chen Y, Medhora M, Falck JR, Pritchard Jr KA, Jacobs, ER. Mechanisms of activation of eNOS by 20-hydroxyeicosatetraenoic acid and VEGF in bovine pulmonary artery endothelial cells. American Journal of Physiology: Lung Cellular and Molecular Physiology, 2006;10:1152
Klinkner DB, Densmore JC, Kaul S, Noll L, Lim HJ, Weihrauch D, Pritchard Jr KA, Oldham KT, and Sander TL. Endothelium-Derived Microparticles Inhibit Human Cardiac Valve Endothelial Cell Function. Shock, 2006; 25(6):575-580.
Densmore JC, Signorino, PR, Ou J, Hatoum OA, Rowe JJ, Shi Y, Kaul S, Jones DW, Sabina RE, Pritchard Jr KA, Guice KS, Oldham KT. Endothelium-Derived Microparticles Induce Endothelial Dysfunction and Acute Lung Injury. Shock, 2006, 26(5):464-71.
Kwitek AE, Jacob HJ, Baker JE, Dwinell MR, Forster HV, Greene AS, Kunert MP, Lombard JH, Mattson DL, Pritchard Jr KA, Roman RJ, Tonellato PJ, Cowley Jr AW. BN phenome: detailed characterization of the cardiovascular, renal, and pulmonary systems of the sequenced rat. Physiol Genomics, 2006 Apr 13;25(2):303-13.
Ou J, Wang J, Xu H, Ou Z, Sorci-Thomas M, Jones DW, Signorino P, Densmore JC, Kaul S, Oldham KT, Pritchard Jr KA. Effects of D-4F on Vasodilation and Vessel Wall Thickness in Hypercholesterolemic LDL Receptor Null and LDL receptor/ApoA-I Double Knockout Mice on Western Diet. Circ Res, 2005;97(11):1190-7.
Shi Y, Hutchins WC, Su J, Siker D, Hogg N, Pritchard Jr KA, Keszler A, Tweddell JS, Baker JE. Delayed cardioprotection with isoflurane: role of reactive oxygen and nitrogen. American Journal of Physiology: Heart and Circulation Physiology, 2005;288:H175-184
Shi Y, Hutchins W, Ogawa H, Chang CC, Pritchard Jr KA, Zhang C, Khampang P, Lazar J, Jacob HJ, Rafiee P, Baker JE. Increased resistance to myocardial ischemia in the Brown Norway vs. Dahl S rat: role of nitric oxide synthase and Hsp90. J Mol Cell Cardiol. 2005;38:625-635.
Rafiee P, Shi Y, Su J, Pritchard Jr KA, Tweddell JS, Baker JE. Erythropoietin protects the infant heart against ischemia-reperfusion injury by triggering multiple signaling pathways. Basic Research in Cardiology, 2005;100:187-197.
Pritchard Jr KA, Shi Y, Konduri GG. Tetrahydrobiopterin in pulmonary hypertension: pulmonary hypertension in guanosine triphosphate-cyclohydrolase-deficient mice. Circulation, 2005;111:2022-2024.
Shi Y, Rafiee P, Su J, Pritchard KA, Jr., Tweddell JS, Baker JE. Acute cardioprotective effects of erythropoietin in infant rabbits are mediated by activation of protein kinases and potassium channels. Basic Res Cardiol 2004;99(3):173-82.
Pritchard KA, Jr., Ou J, Ou Z, Shi Y, Franciosi JP, Signorino P, et al. Hypoxia-induced acute lung injury in murine models of sickle cell disease. Am J Physiol Lung Cell Mol Physiol 2004;286(4):L705-14.
Ou J, Fontana JT, Ou Z, Jones DW, Ackerman AW, Oldham KT, et al. Heat shock protein 90 and tyrosine kinase regulate eNOS NO* generation but not NO* bioactivity. Am J Physiol Heart Circ Physiol 2004;286(2):H561-H569.
Gendelman M, Halligan N, Komorowski R, Logan B, Murphy WJ, Blazar BR, et al. Phenyl-N-TERT-Butylnitrone (PBN) protects syngeneic marrow transplant recipients from the lethal cytokine syndrome occurring after agonistic CD40 antibody administration. Blood In Press 2004.
Rafiee P, Shi Y, Pritchard KA, Jr., Ogawa H, Eis AL, Komorowski RA, et al. Cellular redistribution of inducible Hsp70 protein in the human and rabbit heart in response to the stress of chronic hypoxia: role of protein kinases. J Biol Chem 2003;278(44):43636-44.
Ou J, Geiger T, Ou Z, Oldham KT, Pritchard Jr KA. AP-4F, antennapedia peptide linked to an amphipathic a helical peptide, increases the efficiency of lipofectamine-mediated gene transfection in endothelial cells. Biochemical and Biophysical Research Communications, 2003; 305(3):605-610.
Ou J, Ou Z, Jones DW, Holzhauer S, Hatoum OA, Ackerman AW, et al. L-4F, an apolipoprotein A-1 mimetic, dramatically improves vasodilation in hypercholesterolemia and sickle cell disease. Circulation 2003;107(18):2337-41.
Ou J, Ou Z, McCarver DG, Hines RN, Oldham KT, Ackerman AW, et al. Trichloroethylene decreases heat shock protein 90 interactions with endothelial nitric oxide synthase: implications for endothelial cell proliferation. Toxicol Sci 2003;73(1):90-7.
Ou Z, Ou J, Ackerman AW, Oldham KT, Pritchard Jr. KA. L-4F, an apolipoprotein A-1 mimetic, restores nitric oxide and superoxide anion balance in low-density lipoprotein treated endothelial cells. Circulation 2003;107:803-7.
Ou J, Ou Z, Ackerman AW, Oldham KT, Pritchard KA, Jr. Inhibition of heat shock protein 90 (hsp90) in proliferating endothelial cells uncouples endothelial nitric oxide synthase activity. Free Radic Biol Med 2003;34(2):269-276.
Ogawa H, Rafiee P, Heidemann J, Fisher PJ, Johnson NA, Otterson MF, Kalyanaraman B, Pritchard Jr KA, and Binion DG. Mechanisms of endotoxin tolerance in human intestinal microvascular endothelial cells. J Immunol, 2003; 170: 5956-5964.
Lin MI, Fulton D, Babbitt R, Fleming I, Busse R, Pritchard KA, Jr., et al. Phosphorylation of threonine 497 in endothelial nitric-oxide synthase coordinates the coupling of L-arginine metabolism to efficient nitric oxide production. J Biol Chem 2003;278(45):44719-26.
Koshida R, Ou J, Matsunaga T, Chilian WM, Oldham KT, Ackerman AW, et al. Angiostatin, a negative regulator of endothelial-dependent vasodilation. Circulation 2003;107:803-806.
Konduri GG, Ou J, Shi Y, Pritchard Jr. KA. Decreased association of Hsp90 impairs endothelial nitric oxide synthase in fetal lambs with persistent pulmonary hypertension. Am J Physiol: Heart & Circulation 2003;285(1):H204-11.
Stepp DW, Ou J, Ackerman AW, Welak S, Klick D, Pritchard Jr. KA. Native LDL and minimally oxidized LDL differentially regulate superoxide anion in vascular endothelium In Situ. Am. J. Physiology Heart and Circulation 2002;283(2):H750–H759.
Shi Y, Baker JE, Zhang C, Tweddell JS, Su J, Pritchard Jr. KA. Chronic hypoxia increases endothelial nitric oxide synthase generation of nitric oxide by increasing heat shock protein 90 association and serine phosphorylation. Circulation Research 2002;91(4):300-6.
Rafiee P, Shi Y, Kong X, Pritchard KA, Jr., Tweddell JS, Litwin SB, et al. Activation of protein kinases in chronically hypoxic infant human and rabbit hearts: role in cardioprotection. Circulation 2002;106(2):239-45.
Pritchard KA, Jr., Ackerman AW, Ou J, Smalley DM, Curtis ML, Fontana JT, et al. Native Low-density Lipoprotein Induces Endothelial Nitric Oxide Synthase Dysfunction: Role of Heat Shock Protein 90 and Caveolin-1. Free Radic Biol Med 2002;33(1):52-62.
Pritchard KA, Jr., Ackerman AW, Gross ER, Stepp DW, Shi Y, Fontana JT, et al. Heat shock protein 90 mediates the balance of nitric oxide and superoxide anion from endothelial nitric-oxide synthase. J Biol Chem 2001;276(21):17621-4.