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Abstract: TH-OR55

Molecular and Cellular Mechanisms of Lipocalin-2-Mediated Renoprotection in Kidney Transplantation

Session Information

Category: Transplantation

  • 2001 Transplantation: Basic

Authors

  • Pfefferkorn, Anna Maria, Department of Surgery, Experimental Surgery, Charité – Universitätsmedizin, Berlin, Germany
  • Zhao, Liang, Department of Nephrology, the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
  • Xu, Minze, Institute of Translational Physiology, Charité-Universitätsmedizin, Berlin, Germany
  • Kusch, Angelika, Berlin Institute of Health at Charité - Universitätsmedizin, Berlin, Germany
  • Fritsche, Raphaela, Berlin Institute of Health at Charité - Universitätsmedizin Berlin, Metabolomics Platform, Berlin, Germany
  • Erdogan, Cem, Institute of Translational Physiology, Charité-Universitätsmedizin, Berlin, Germany
  • Schwelberger, Hubert G., Department of Visceral, Transplant and Thoracic Surgery, Medical University Innsbruck, Innsbruck, Austria
  • Aigner, Felix, Department of Surgery, Krankenhaus der Barmherzigen Brüder, Graz, Austria
  • Patzak, Andreas, Institute of Translational Physiology, Charité-Universitätsmedizin, Berlin, Germany
  • Sauer, Igor M., Department of Surgery, Experimental Surgery, Charité – Universitätsmedizin, Berlin, Germany
  • Ashraf, Muhammad Imtiaz, Department of Surgery, Experimental Surgery, Charité – Universitätsmedizin, Berlin, Germany
Background

While Lipocalin-2 (Lcn2) is a an early marker of acute kidney injury, delayed graft function and acute rejection, our previous studies have outlined a protective effect of recombinant Lcn2:Siderophore:Fe (rLcn2) in a mouse kidney transplantation (KTx) model. The underlying mechanism of renoprotection has not yet been fully investigated, elucidating which forms the primary focus of this study.

Methods

Kidneys were transplanted from Balb/c to C57Bl/6 mice (±rLcn2, 250mg/kg). Phenotyping of the immune cells, isolated from graft, spleen, lymph nodes and blood was performed by flow cytometry at post-KTx day 3 and 7. For analyses of stress, inflammation and survival signaling in the mouse kidney multiplex signaling analysis was performed following syngeneic KTx (cold ischemia (CI): 5.5h, reperfusion (R): 24h ±rLcn2, 250mg/kg) and in mouse primary proximal tubular epithelial cells, subjected to hypoxia/reoxygenation (H: 24h/ R: 30min, 6h, 12h, 24h ±rLcn2, 1µg/ml). To determine the effect of rLcn2 on physiology of renal microvessels, dilatation function of BAY 58-2667 (soluble guanylyl cyclase activator) on angiotensin II-preconstricted murine afferent arterioles (AA) was examined following H/R (H:30min/ R:10min) and syngeneic KTx (CI: 5.5h, R: 20h) ±rLcn2, apo-rLcn2 and defroxamine (DFO).

Results

Analysis of the leukocytes revealed no general immunosuppressive or regulatory effect of rLcn2. However, rLcn2 treatment curtailed intra graft accumulation of total and in particular of activated (NKG2D+) CD8+ T cells. Degranulation capacity and frequency of interferon gamma+ and perforin+ CD8+ T cells was significantly attenuated. No clear effect of rLcn2 was observed on candidate stress, inflammation and survival signaling molecules in the mouse kidney epithelia during H/R and KTx. Interestingly, rLcn2 not only circumvented H/R-induced loss in dilatation of isolated renal AA but also substantially improved CI-impaired vasodilatation. While Fe free apo-rLcn2 could not ameliorate loss of vasodilatation, DFO reversed the protective effect of rLcn2, validating the iron-dependent effect.

Conclusion

rLcn2 protects mouse renal allografts from CD8+T cell mediated alloimmune response and abates loss in dilatation of renal AA both in vitro (H/R) and in vivo (KTx).

Funding

  • Government Support – Non-U.S.