Preventing brain death induced kidney injury through exploiting the hypoxia inducible factor pathway

Lammerts, R.G.M. (2013) Preventing brain death induced kidney injury through exploiting the hypoxia inducible factor pathway. thesis, Medicine.

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Abstract

Background and aims: Brain death-derived kidney allografts have inferior short and long-term outcomes when compared to the living donated allograft, even when HLA mismatches and cold ischemia times are taken into consideration. Brain death leads to a physiologically abnormal state resulting in dramatic hemodynamic, hormonal, coagulation and inflammatory disturbances culminating in kidney injury prior to organ procurement. Two promising therapies evaluated in the brain death setting include heme-oxygenase 1 (HO-1) and erythropoietin (EPO) administration. These are both downstream effectors of the hypoxia inducible factor (HIF) pathway. HIF is the universal cellular oxygen sensing mechanism and mediates over 100 hypoxia responsive genes. The HIF pathway is responsible for the early and delayed response of ischaemic preconditioning, a pathway in what exposure of an organ to a short period of ischemia protects the organ against exposure to subsequent periods of ischemia. We hypothesized that up regulation of HIF in brain death donors could protect against brain death induced kidney injury and improve the outcomes of kidney transplantation. To begin to evaluate this hypothesis I characterized the effects of brain death on HIF1α expression in comparison to other models of hypoxic/ischemic injury. Methods: the expression of HIF1α was characterized in four models of kidney ischemic injury. Adult male Fischer rats were used in the described animal model. (n=8, 230-350g). Brain death (DBD) was induced by a gradual inflation of a subdurally placed balloon catheter. In addition an ischemia reperfusion model(n=2) and a deceased after circulatory death model (n=2) was developed. Cell culture NRK-49 cells were grown in DMEM medium. Western blotting was performed to characterize the differential expression of HIF and HO-1, a downstream effector of HIF. Results: A brain death animal model was developed. Induction of brain death showed a drop in blood pressure after approximately 40 min. It was not possible to increase the blood pressure to 80 mmHg after brain death induction. Western blotting showed HIF1α expression in the 4 models of kidney injury. HO-1 expression was seen in 3 models. Conclusions: The BD model needs optimization to maintain the animals stable for a longer period of time. These results suggest that HIF1α is activated in the 4 different models of kidney injury. Western blotting for kidney samples showed more HIF1α and HO-1 expression in the IRI experimental group than in the control group. In the DCD model HIF1α is less expressed in the experimental group than in the control group, whereas HO-1 is more expressed in the DCD experimental group. As for the DBD group, both HIF1α and HO-1 are more expressed in the experimental group than in the control group. Western blotting for liver samples showed more HIF1α expression in the IRI control group than in the IRI experimental group. In the liver DCD model HIF1α is more expressed in the control group than in the DCD experimental group, whereas in the DBD model both HIF1α and HO-1 are more expressed in the experimental group than in the control group. However, to confirm this further research needs to be performed. Expression of the prolyl hydroxylases 1,2 and 3 and expression of HIF2 α and HIF 3α are questions yet to be answered before administration of a prolyl hydroxylase inhibitor and translation to the clinical setting.

Item Type:	Thesis (Thesis)
Supervisor name:	Leuvenink, H.G.D.
Supervisor name:	Ploeg, Prof. R.J. and Akhtar, Z.M. and Oxford Transplant Centre and Department of Surgical Sciences. and University of Oxford
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 11:07
Last Modified:	25 Jun 2020 11:07
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/2645

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