EET-mediated mechanisms of protection against AKI
Final Report Abstract
The long-term objective of this project has been to develop novel therapeutic strategies for the prevention of acute kidney injury (AKI) by targeting the formation and action of cytochrome P450 (CYP)-dependent eicosanoids. We hypothesized that imbalances in the formation of 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) contribute to the initiation of ischemic AKI due to the opposing roles of these two lipid mediator classes in promoting (20-HETE) or repressing (EETs) vasoconstriction, inflammation, and apoptosis. Substantiating the presumed detrimental role of 20-HETE, we found that inhibition of 20-HETE formation and action ameliorated ischemia/reperfusion (I/R)-induced AKI in rats. Our follow-up studies in the same model (uninephrectomized male Lewis rats subjected to 45 min of renal ischemia followed by up to 48 h of reperfusion), revealed the ischemia-induced imbalance in CYP-eicosanoid formation: compared to sham controls, renal ischemia induced an about 10-fold increase of free 20-HETE levels, whereas free EETs were not accumulated. To compensate for the lack of endogenous EET release, we applied a synthetic 14,15-EET analog by intrarenal injection before ischemia. The EET analog improved renal reoxygenation as monitored by in vivo parametric MRI during the initial 2 h reperfusion phase (in collaboration with the groups of Niendorf and Seeliger. The EET analog mediated fast PI3K- as well as mTORC2-dependent rephosphorylation of Akt, induced inactivation of GSK-3β, reduced the development of tubular apoptosis and attenuated inflammatory cell infiltration. The EET analog also significantly alleviated the I/R-induced drop in creatinine clearance. Considering that EETs are rapidly metabolized to dihydroxyeicosatrienoic acids (DHETs) by the soluble epoxide hydrolase (sEH), we hypothesized that sEH gene (EPHX2) deletion would increase endogenous EET levels and thereby protect against I/R-induced AKI. Contrary to this hypothesis, renal function declined more severely in sEH-KO mice that also featured stronger tubular lesion scores, tubular apoptosis, and inflammatory cell infiltration compared to WT mice. CYP-eicosanoid profiling revealed that renal, but not plasma and hepatic, 20-HETE levels were significantly increased in sEH- KO compared to WT mice. Renal expression of Cyp4a12a, the murine 20-HETE-generating CYP-enzyme, was up-regulated both at the mRNA and protein level, and Cyp4a12a immunostaining was more intense in the renal arterioles of sEH-KO compared with WT mice. These results indicate that the potential beneficial effects of reducing EET degradation were obliterated by a thus far unknown mechanism leading to kidney-specific up-regulation of 20-HETE formation in sEH-KO-mice. Moreover, we performed a translational pilot study, where we compared the circulating CYP-eicosanoid profiles in patients who underwent cardiac surgery with and without developing postoperative AKI4. The AKI group featured increased pre-operative 20-HETE and 8,9-EET levels indicating that individual differences in CYP-eicosanoid formation may contribute to the risk of developing AKI in clinical settings such as cardiac surgery. Collaborations with other partners of the research unit resulted in novel findings regarding the role of sEH-mediated EETs hydrolysis in vasopressin-induced antidiuresis and contributed to the analysis of hypoxia-reoxygenation induced enhanced angiotensin II mediated afferent renal arteriolar vasoconstriction. Taken together, the results of this project demonstrate that 20-HETE and EETs play opposing roles in the initiation and extension of ischemic AKI and suggest that pharmacological interventions targeting the CYP-eicosanoid pathway could offer promising new options for AKI prevention. This project also stimulated parallel attempts to develop druggable epoxyeicosanoid analogs for the treatment of cardiovascular and inflammatory diseases, a goal now pursued by a start-up company at the MDC campus.
Publications
- Novel Eicosanoid Derivatives. WO 2010/081683
Schunck Wolf-Hagen; Wallukat Gerd; Fischer Robert; Arnold Cosima; Mueller Dominik N; Puli Narender; Falck John R
- Inhibition of 20-hete synthesis and action protects the kidney from ischemia/reperfusion injury. Kidney Int. 79: 57-65, 2011
Hoff U, Lukitsch I, Chaykovska L, Ladwig M, Arnold C, Manthati VL, Fuller TF, Schneider W, Gollasch M, Muller DN, Flemming B, Seeliger E, Luft FC, Falck JR, Dragun D, Schunck WH
(See online at https://doi.org/10.1038/ki.2010.377) - High temporal resolution parametric mri monitoring of the initial ischemia/reperfusion phase in experimental acute kidney injury. PLoS One 8: e57411, 2013
Pohlmann A, Hentschel J, Fechner M, Hoff U, Bubalo G, Arakelyan K, Cantow K, Seeliger E, Flemming B, Waiczies H, Waiczies S, Schunck WH, Dragun D, Niendorf T
(See online at https://doi.org/10.1371/journal.pone.0057411) - Novel signalling mechanisms and targets in renal ischaemia and reperfusion injury. Acta Physiologica 208: 25-40, 2013
Kusch A, Hoff U, Bubalo G, Zhu Y, Fechner M, Schmidt-Ullrich R, Marko L, Muller DN, Schmidt-Ott KM, Gurgen D, Blum M, Schunck WH, Dragun D
(See online at https://doi.org/10.1111/apha.12089) - Cytochrome p450 enzymes in the bioactivation of polyunsaturated fatty acids and their role in cardiovascular disease. Advances in experimental medicine and biology 851: 151-187, 2015
Westphal C, Konkel A, Schunck WH
(See online at https://doi.org/10.1007/978-3-319-16009-2_6) - Novel Cyp-Eicosanoid Derivatives. WO 2015/110262
Schunck Wolf-Hagen; Muller Dominik; Fischer Robert; Wallukat Gerd; Konkel Anne; Falck John Russell
- Renal ischemia/reperfusion injury in soluble epoxide hydrolase-deficient mice. PLoS One 11: e0145645, 2016
Zhu Y, Blum M, Hoff U, Wesser T, Fechner M, Westphal C, Gurgen D, Catar RA, Philippe A, Wu K, Bubalo G, Rothe M, Weldon SM, Dragun D, Schunck WH
(See online at https://doi.org/10.1371/journal.pone.0145645) - Vasopressin lowers renal epoxyeicosatrienoic acid levels by activating soluble epoxide hydrolase. Am J Physiol Renal Physiol. 311: F1198-F1210, 2016
Boldt C, Roschel T, Himmerkus N, Plain A, Bleich M, Labes R, Blum M, Krause H, Magheli A, Giesecke T, Mutig K, Rothe M, Weldon SM, Dragun D, Schunck WH, Bachmann S, Paliege A
(See online at https://doi.org/10.1152/ajprenal.00062.2016) - Hypoxia-reoxygenation enhances murine afferent arteriolar vasoconstriction by angiotensin II. Am J Physiol Renal Physiol. 314: F430-F438, 2018
Pahlitzsch T, Liu ZZ, Al-Masri A, Braun D, Dietze S, Persson PB, Schunck WH, Blum M, Kupsch E, Ludwig M, Patzak A
(See online at https://doi.org/10.1152/ajprenal.00252.2017) - Therapeutic potential of omega-3 fatty acidderived epoxyeicosanoids in cardiovascular and inflammatory diseases. Pharmacol Ther. 183: 177- 204, 2018
Schunck WH, Konkel A, Fischer R, Weylandt KH
(See online at https://doi.org/10.1016/j.pharmthera.2017.10.016)
