The protective role of tumour necrosis factor alpha in the heart

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dc.contributor.advisorSack, Michael Nen_ZA
dc.contributor.authorMeiring, James Justusen_ZA
dc.date.accessioned2018-01-09T08:54:08Z
dc.date.available2018-01-09T08:54:08Z
dc.date.issued2002en_ZA
dc.description.abstractThe pleiotropic cytokine tumour necrosis factor alpha (TNFα) is produced by the heart in response to the ischaemic preconditioning (PC) stimulus. We hypothesised that this endogenously produced peptide may play a role in activating the ischaemic PC mediated tolerance towards a subsequent ischaemic insult in muscle cells. To test this and to delineate the downstream signalling cascades mediating this programme we developed classic PC protocols in adherent mature murine C2C12 myotubes and in human cardiac derived Girardi cell lines. The C2C12 myotubes were preconditioned using either one hour of simulated ischaemia (SI) or the PC-mimetic adenosine (0.1 mM) or TNFα (0.5 ng/ml) followed by one hour of reoxygenation followed by an eight hour SI insult. Cell viability was assessed by measuring lactate dehydrogenase (LOH) release. Simulated ischaemia (SI), PC, adenosine and TNFα activated the PC programme and increased cell viability by 40±3%, 28±5% and 36±4% respectively compared to the SI controls (p<0.005 in all experiments, n≥4 x 6 well plates in all groups). Cell viability was also evaluated by the measurement of propidium iodide uptake on flow cytometry. Preconditioning and TNFα enhanced cell viability with a reduction in propidium iodide uptake by 28% and 41 % respectively versus the ischaemic controls. To evaluate whether TNFα activation of the nuclear regulatory protein nuclear factor kappa B (NFₖ B) mediates this myocyte protection, the NFₖ B antagonists diethyldithiocarbamate (DDTC 10mM) or sodium salicylate (SA 100μM) were co-administered with TNFα. The myocyte protective effect of TNF a was significantly decrease with both antagonists, although not completely inhibited/blocked (DDTC - attenuated cell viability by 62 ±6% and SA by 45 ±5% compared to the TNFα preconditioned cells (p <0.05 vs SI controls and p<0.05 vs TNFα PC, with either antagonists). To confirm these data, TNFα was used as a PC-mimetic in the isolated Langendorff perfused rat heart (Langendorff) preparation. Infarct size was used as the end point. In parallel with cell culture studies, TNFα again conferred preconditioning induced cardioprotection with partial abrogation of these effects with the pharmacological antagonists of NFₖ B. Thus, TNFα administration mimics the cytoprotective effects of ischaemic PC in cardiac, skeletal myocytes and in the isolated perfused rat heart. Moreover, these data support the role of TNFα production as an endogenous paracrine / autocrine signalling peptide which promotes myocyte cellular survival, in part, through activation of NFₖ B.en_ZA
dc.identifier.apacitationMeiring, J. J. (2002). <i>The protective role of tumour necrosis factor alpha in the heart</i>. (Thesis). University of Cape Town ,Faculty of Health Sciences ,Division of Cardiology. Retrieved from http://hdl.handle.net/11427/26755en_ZA
dc.identifier.chicagocitationMeiring, James Justus. <i>"The protective role of tumour necrosis factor alpha in the heart."</i> Thesis., University of Cape Town ,Faculty of Health Sciences ,Division of Cardiology, 2002. http://hdl.handle.net/11427/26755en_ZA
dc.identifier.citationMeiring, J. 2002. The protective role of tumour necrosis factor alpha in the heart. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Meiring, James Justus AB - The pleiotropic cytokine tumour necrosis factor alpha (TNFα) is produced by the heart in response to the ischaemic preconditioning (PC) stimulus. We hypothesised that this endogenously produced peptide may play a role in activating the ischaemic PC mediated tolerance towards a subsequent ischaemic insult in muscle cells. To test this and to delineate the downstream signalling cascades mediating this programme we developed classic PC protocols in adherent mature murine C2C12 myotubes and in human cardiac derived Girardi cell lines. The C2C12 myotubes were preconditioned using either one hour of simulated ischaemia (SI) or the PC-mimetic adenosine (0.1 mM) or TNFα (0.5 ng/ml) followed by one hour of reoxygenation followed by an eight hour SI insult. Cell viability was assessed by measuring lactate dehydrogenase (LOH) release. Simulated ischaemia (SI), PC, adenosine and TNFα activated the PC programme and increased cell viability by 40±3%, 28±5% and 36±4% respectively compared to the SI controls (p<0.005 in all experiments, n≥4 x 6 well plates in all groups). Cell viability was also evaluated by the measurement of propidium iodide uptake on flow cytometry. Preconditioning and TNFα enhanced cell viability with a reduction in propidium iodide uptake by 28% and 41 % respectively versus the ischaemic controls. To evaluate whether TNFα activation of the nuclear regulatory protein nuclear factor kappa B (NFₖ B) mediates this myocyte protection, the NFₖ B antagonists diethyldithiocarbamate (DDTC 10mM) or sodium salicylate (SA 100μM) were co-administered with TNFα. The myocyte protective effect of TNF a was significantly decrease with both antagonists, although not completely inhibited/blocked (DDTC - attenuated cell viability by 62 ±6% and SA by 45 ±5% compared to the TNFα preconditioned cells (p <0.05 vs SI controls and p<0.05 vs TNFα PC, with either antagonists). To confirm these data, TNFα was used as a PC-mimetic in the isolated Langendorff perfused rat heart (Langendorff) preparation. Infarct size was used as the end point. In parallel with cell culture studies, TNFα again conferred preconditioning induced cardioprotection with partial abrogation of these effects with the pharmacological antagonists of NFₖ B. Thus, TNFα administration mimics the cytoprotective effects of ischaemic PC in cardiac, skeletal myocytes and in the isolated perfused rat heart. Moreover, these data support the role of TNFα production as an endogenous paracrine / autocrine signalling peptide which promotes myocyte cellular survival, in part, through activation of NFₖ B. DA - 2002 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2002 T1 - The protective role of tumour necrosis factor alpha in the heart TI - The protective role of tumour necrosis factor alpha in the heart UR - http://hdl.handle.net/11427/26755 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/26755
dc.identifier.vancouvercitationMeiring JJ. The protective role of tumour necrosis factor alpha in the heart. [Thesis]. University of Cape Town ,Faculty of Health Sciences ,Division of Cardiology, 2002 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/26755en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDivision of Cardiologyen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherCardiologyen_ZA
dc.titleThe protective role of tumour necrosis factor alpha in the hearten_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Med)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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