PgmNr Z6133: A zebrafish model of acute kidney injury associated with systemic infection induced by intravascular bacteria injection.

Authors:
L. Cui 1,2 ; X. Wen 1,2 ; S. Morrisroe 1,2 ; L. Brilli 1,3 ; X. Chen 1,2 ; N. Hukriede 1,3 ; J. Kellum 1,2


Institutes
1) Center for Critical Care Nephrology, Pittsburgh, PA; 2) Department Critical Care Medicine, Pittsburgh, PA; 3) Department of Development Biology, University of Pittsburgh, Pittsburgh, PA.


Abstract:

Sepsis associated Acute Kidney Injury is a serious complication in critical ill patients, contributes to high mortality. To date, the underlying mechanisms responsible for kidney injury in sepsis remain poorly understood and treatments are still limited to supportive methods. The zebrafish is an economically attractive multicellular organism, provides unique visual access to the microscopic structure with cell-cell interactions. Both the embryonic and adult zebrafish show  conserved components in both immune responses and functional nephrons with mammals, which makes this model promising for studying mechanisms and screening for treatment options. An acute nephrotoxic kidney injury model has been developed using gentamycin, but inflammation-associated AKI is more clinical relevant and yet no model in the zebrafish has been reported. E. tadar is a lethal pathogen in zebrafish, characterized by striking cytokine excretion and high mortality. Here we compared inflammatory findings of both bacteria injections into 3 days post-fertilization (dpf) zebrafish embryos as well as infection mediated kidney damage. We show dose-dependent mortalities for both E. coli and E. tadar intravascular injections, with E. tadar significantly higher than E. coli treated animals. We found remarkably decreased fluorescent dextran uptake and loss of tubule brush boarder occurred as early as 6-24 hours post injection in E. tadar treated larvae compared to E. coli treated ones as well as normal controls. Nephron-specific kidney injury molecular-1 (KIM-1) functions as phagocyte receptor, mediates uptake of dead cells and tissue debris. Immunofluorescence staining of KIM-1 appears at late time points post injection in both groups compared to no expressions in control groups. Prolonged expression of KIM-1 in mammalian kidney predicts AKI and maladaptive repair.  These analyses have provided new insights for further understanding the physiological and molecular mechanisms that lead to kidney injury in the setting of infection and system inflammation.