Regulation of T lymphocyte functio

Transcription

1 I Regulation of T lymphocyte functio v novel engineered polyunsaturated fatty acids By Maurizio Costabile B.Sc (Hons) A Thesis submitted for the degree of Doctor of Philosophy (PhD) The University of Adelaide 200r

2 u Table of Contents Acknowledgments xlv Abbreviations )w Summary )o(\ Chapter One I Introduction 1 1. General Introduction Mechanism of T cell activation J l.l.l Protein kinase C (PKC) l. I. 2 Mitogen activated protein kinases L I Extr ac ellular s ignal-r e gulate d kinas es c-jun NH2-terminal kinase j pj8 8 l Properties of cytokines released by T lymphocytes Thl vs Th2 cytokines T2 l Interleukin-2 14

3 lll Interferon-T Tumour necrosis factor-þ t7 1.3 Role of T tymphocytes in immunopathogenesis t7 1.4 Pharmacological agents used as immunosuppressive agents Cyclosporin A (CsA) t.4.2 FK j Rapamycin L4.4 Corticosteroids l, 4. 5 Mycophenolate mofetil t l Cytotoxic drugs I Anti-CD3 antibody CyclophosPhamide Azathioprine and í-mercaptopurine Modulation of immune responses by fatty acids and other lipid compounds 25 L5.1 Lipids, fats andfatty acids Fatty acids and their nomenclature 26 t TriacylglYcerols PhospholiPids SphingoliPids 29

4 1V 1.6 Sources of fatfy acids Digestion offats and lipids Oxidation offatty acids L6.3 Biosynthesis offatty acids Release offatty acids from membrane phospholipids 1.7 Eicosanoids 1.7. I Lipoxygenase pathway I Cyclooxygenase pathw ay l Epoxygenase pathway 1.8 Immunomodulatory properties of fatty acids l.b.i PUFA and immunologically based inflammatory diseases Effect of PUFA on cytokine production measured ex vivo Effects of PUFA on invivo immunological responses Effect offatty acids on the delayed type hypersensitivity (Dfry response Effect offatty acids on the graft vs host (GvH) and host vs graft (HvG) response Effects offatty acids on natural killer QtlK), lymphokine activated killer (LAK) and cytotoxic T lymphocyte (CTL) activity 55

5 Effect offatty acids on antigen presenting cell (APC) function Human lymphocyte proliferation Effects of PUFA on in vitro immunological responses Human cytokine production ,3 Effect of PUFA on animal lymphocyte proliferation Biological properties of LTs on lymphocytes 63 l.i0.1 Biological properties of PGs on lymphocytes Proposed inhibitory actions 1.12 Effect of r-3 PUFA on neutrophil superoxide production Concluding remarks Aims, hypothesis and significance of the present study 7l Chapter Two 73 Materials and Methods Natural fatty acids Engineered polyunsaturated fatty acids 74

6 vl I þ-oxa 2 I : 3n- 3 (Z,Z,Z)-(Octadeca-9, I 2, I S-trienyloxy) acetic acid þthia 23:4n-6 (3-[(all-Z)-(Eicosa-5,8,] l,l4-tetraenylthio)j propionic acid) þthia 2l:3n-6 3-[(Z,Z,Z)-(Octadeca-6,9,12-trienylthio)]propionic acid þ-thia 23:0 2.2,5 Determination of engineeredfatty acid purity Synthesis of engineeredfatty acid methyl esters 2.3 Assessment of fatty acid purity by thin layer chromatography (flc) 2.4 Presentation of fatty acids to cells 2.5 Purification of human leukocytes 2.5.I T lymphocytes Purification Determination of T lymphocyte purity 2.6 Estimation of surface antigen expression 2.7 Lymphocyte proliferation and cytokine production 2.7. I Lymphocyte proliferation Cytokine measurement

7 vll 2.8 Measurement of the neutrophil respiratory burst Activation of intracellular signalling molecules 9l Protein Kinase C 2.9. I. I PKC Translocation PKC kinase qssay Il'estern blotting 91 9T Measurement of the extracellular signal-regulated protein kinase Partial purification Kinase assay c-jun NH2 terminal kinase (INK) activity Purification of GSTfusion protein Kinase assay Measurement of p38 kinase activity Examination of the in vivo effect of B-oxa 2l:3n I0 I Effect of þ-oxa 2I :3n-3 on biochemical markers associated with liver and kidney function Gross determination of lipid incorporation Determination of lipid incorporation into human neu*ophils 100

8 vru 2.Il Delayed type hypersensitivity response r Canageenan-induced paw oedema r Plasmids and Vectors I Purification of plasmid vectors Transfection of Jurkat lymphocytes General Biochemicals Inhibitors Antibodies and Conjugates Statistical analysis of results r06 Chapter The effects of B-oxa, B-thia and y-thia fatty acids on the neutrophil oxygen-dependent respiratory burst t Introduction Ability of B-oxa, B-thia and 1-thia fatty acids to stimulate superoxide production in human neutrophils 110

9 D( 3.3 Incorporation of B-oxa 2I:3n-3 into neutrophil lipids Summary 120 Chapter Alteration of T lymphocyte function byp-oxa 2l:3n-3 r Introduction t Effect of B-oxa 2I:3n-3 on T lymphocyte proliferation t Effect of varying pretreatment time on the ability of p-oxa 21:3n-3 to inhibit lymphocyte function Effect of B-oxa 21:3n-3 on the delayed type hypersensitivity response 142 4,5 Effect of B-oxa 2l:3n-3 on caffageenan induced paw odema t Effect of dietary administration of B-oxa 2I:3n-3 on biochemical markers associated with liver and kidney function Systemic incorporation of B-oxa 21:3n-3 fed to rats Summary 150

10 X Chapter 5 1sl Comparison between B-oxa, B-thia and y-thia fatty acids in their abitify to alter T lymphocyte function Introduction Effects of B-oxa, B-thia and y-thia fatfy acids on T lymphocyte function ts2 5.3 Effect of p-thia 2I:3n-6 and B-thia 23:4n-6 on T lymphocyte proliferation Effect of pre-treatment time on the ability of p-thia 23:4n-6 and p-thia 2I:3n-6 to inhibit lymphocyte function r Summary 178 Chapter 6 t79 Mechanisms by which B-oxa and B-thia PUFA inhibit T lymphocyte responses Introduction The effect of B-oxa and B-thia PUFA on CD3, CD4 and CD8 expression Effect of B-oxa and B-thia PUFA on PMA induced lymphocyte proliferation and cytokine production 183

11 )o 6.4 Effect of B-oxa and p-thia PUFA on CD3/CD28 induced lymphocyte proliferation Effect of B-oxa and p-thia PUFA on PHA-PMA induced activation of pkc t Effect of B-oxa 2I:3n-3 and22:6n-3 on PHA-PMA induced PKC isozyme translocation. t Effect of p-oxa and B-thia PUFA on MAP kinases Effect of B-oxa and B-thia PUFA on the activity of the extracellular signal-regulated kinase Effect of the p-oxa and B-thia PUFA on c-jun NH2-terminal kinase activity Effect of p-oxa and p-thia PUFA on p38 kinase activity Effect of Indomethacin and Nordihydroguaiaretic acid on B-oxa and B-thia PUFA mediated inhibition of lymphocyte proliferation Effect of Vitamin E and N-acetylcysteine on B-oxa and B-thia PUFA mediated inhibition of lymphocyte proliferation Importance of the carboxyl group of p-oxa and p-thia PUFA towards biological activity Summary 230 Chapter Discussion 23r

12 )or 7.I Anti-inflammatory properties Inhibition of T lymphocyte functions Mechanism of anti T lymphocyte effects Poor stimulation of superoxide production Effects of altering fatty acid structures Summary and conclusion 252 Chapter 8 2s4 Bibliography 254

13 )oõ/ Summary Natural polyunsaturated fatty acids (PUFA) were synthesized and assessed as potential anti-inflammatory agents. B-oxa, B-thia and y-thia PUFA were found to inhibit T lymphocyte responses in vitro, assessed as lymphoproliferation as well as production of tumour necrosis factor-b (llnfp), interferon-y (IFNY) and interleúkin-2 (IL-2). Threee of these compounds were studied in detail and found to be more active than the inhibition seen with fish oil fatty acid 22:6n-3. Interestingly these compounds unlike 22:6n-3 were poor stimulators of the human neutrophil respiratory burst, an additional advantage in their use as anti-inflammatory agents. Examination of one of these three, p-oxa 2I:3n-3, in in vivo models of chronic and acute inflammation showed that the fatty acids was highly inhibitory in both types of inflammatory responses. Thus the B-oxa 27:3n-3 inhibited the footpad swelling induced by sheep red blood cell antigens in a delayed type hypersensitivity (DTH) reaction as well as in the caffageenaninduced paw inflammation. This finding with DTH which is dependent on T lymphocytes is consistent with the ability of p-oxa 2l:3n-3 to inhibit Thl type cytokine production. While the reason for its effects on the caíageenan induced inflammation are less clea in this involves predominantly neutrophil infiltration, this reaction also has some T cell dependency. Studies on tissue distribution of the fatty acid, showed that B-oxa 2I:3n-3 was incorporated into membrane phospholipids of liver and blood cells. Preliminary toxicology studies also demonstrated that B- oxa2l:3n-3 was well tolerated by the animals as several chemical and biochemical parameters of liver and kidney function remained within the normal range. The mechanism of inhibition of T lymphocyte responses were in the main identified. The B-oxa 2l:3n-3 acted at a post receptor level affecting signals modules critical for lymphocyte

14 )0Õ/l activation and cytokine production. The fatty acid caused inhibition of pha-pma induced translocation of PKC-BI and PKC-e, but not PKC-cr, PKC-BII or pkc-o. This was further delineated to show inhibition of downstream ERK pathway activation but not the JNK or p3g pathways. This work has identified a new class of anti-inflammatory compounds which are based on PUFA. The action of the fatty acids is through the selective inhibition of the pkc-bl/e and ERK signalling module.