Acute Kidney Injury: Basic Research Interactive Workshop Lisa Robinson, MD, FRCP(C) Division of Nephrology, The Hospital for Sick Children Renal Transplant Program, SickKids Transplant Centre Program in Cell Biology, SickKids Research Institute
Objectives 1. Review the pathogenesis of acute kidney injury (AKI) 2. Review mechanisms of repair following AKI 3. Understand limitations of current therapy for AKI 4. Explore new approaches to target AKI
AKI is a common problem Acute kidney injury is a common problem amongst hospitalized patients Many different causes, of which ischemic AKI is one of the most common AKI is associated with increased mortality Chertow G et al, J Am Soc Nephrol 2005; 16: 3365 3370.
Causes of decreased regional blood flow in AKI Bonventre JV et al (2011), J Clin Invest
Central Features of Injury in Ischemic AKI Epithelial cell injury Endothelial cell injury Recruitment of pro inflammatory cells
Endothelial injury in ischemic AKI Bonventre JV et al (2011), J Clin Invest
Endothelial Cell Injury in AKI Endothelial cell ac8va8on Upregula8on of adhesion molecules expression of endothelial protein C receptor and thrombomodulin endothelial cell permeability Endothelial cell injury Altered vasomotor tone Exposure of prothrombo8c basement membrane Sharfuddin AA, Molitoris BA; Nat Rev Nephrol 2011; 7: 189 200.
Epithelial Cell Injury in AKI Sublethal injury Loss of 8ght junc8ons ROS produc8on Release of proinflammatory chemokines Lethal injury Apoptosis Necrosis Autophagy Cast forma8on Sharfuddin AA, Molitoris BA; Nat Rev Nephrol 2011; 7: 189 200.
Immune response in ischemic AKI Bonventre JV et al (2011), J Clin Invest
Recruitment of Inflammatory Cells
Summary Sharfuddin AA, Molitoris BA; Nat Rev Nephrol 2011; 7: 189 200.
Abnormal repair in ischemic AKI Bonventre JV et al (2011), J Clin Invest
K Ley, University of Virginia
Chemokine/ Chemokine Receptor Family CXC Fractalkine CC CX 3 C XC
Different Approach: Is it possible to generally inhibit pathologic attractant-mediated leukocyte migration?
Slit and Robo: Neuronal Guidance Cues Robo1 Ig repeats FNIII CC0 CC1 CC2 CC3 bind to LRRs and full-length Slit Determines repulsive response to Slit LRR Slit2 Kidney Heart Lung Slit is a potent repellent for projecting axons and migrating neurons in the developing nervous system. Slit and Robo are widely expressed outside of the nervous system.
Slit2 inhibits migration of many cell types Slit2 Neuronal cells Vascular smooth muscle cells PDGF Robo-1 PDGFR Cancer cells Dendritic Lymphocytes cells CXCL12 Cdc42-GDP or Rac-GDP srgap GEF Cdc42-GTP or Rac-GTP CXCR4 Actin polymerization Cell (2001) 107: 209-221 Circ Res (2006) 98: 480-489 Nature (2001) 410: 948-952 Cell migration J Biol Chem (2004) 279: 9115-9124 Oncogene (2006) 25: 5103-5112 J Immunol (2003) 171: 6519-6526
Can Slit2 prevent AKI? Acute kidney injury Neutrophils Inflammation Monocytes/ macrophages
Neutrophils express Robo-1 Tole S et al (2009). J Leukoc Biol.
Monocytes and macrophages express Robo-1 Monocytes THP-1
Slit2 Inhibits Monocyte Chemotaxis unstimulated SDF-1α A B untreated C D Slit2
Slit2 inhibits neutrophil migration towards diverse attractants Tole S et al (2009). J Leukoc Biol.
How does Slit2 inhibit leukocyte migration?
Slit2 prevents activation of Rac and Cdc42 Monocytes Neutrophils
Slit2 prevents activation of Akt and Erk in monocytes p-akt p-erk p-p38
Slit2 prevents polarization of neutrophils Tole S et al (2009). J Leukoc Biol.
?Slit2 Slit2 K Ley, University of Virginia
Slit2 inhibits monocyte adhesion to vascular endothelial cells
Slit2 inhibits neutrophil adhesion to endothelium in ischemia-reperfusion injury
Does Slit2 prevent acute kidney injury in vivo???
Slit2 protects kidney function in IRI Plasma creatinine (mg/dl)
Slit2 prevents kidney inflammation in IRI Tubular necrosis Neutrophil infiltration
Platelets express Robo-1 and srgap1 Robo-1 P-selectin
Slit2 inhibits platelet spreading Control Slit2
Slit2 prolongs bleeding time in vivo
Slit2 prevents formation of stable, occlusive thrombi Adili Reheman Heyu Ni
Inflammation S L I AKI T 2 Thrombosis
HSCRI: U Toronto: U Virginia: Acknowledgements Yiwei Huang Guang Ying Liu Soumitra Tole Ming Yan Ilya Mukovozov Meeta Mallik Min Rui Crow Harry Yan Sajeda Patel Swasti Chaturvedi Harikesh Wong Michael Glogauer Heyu Ni Adili Reheman Mark Okusa Aman Bhajwa NRC: Sergio Grinstein Bill Trimble Darius Bagli Walter Kahr Fred Pluthero John Brumell Grace Lam Yves Durocher Kidney Transplant Team