Renal effects of the serine protease inhibitor aprotinin in healthy conscious mice

Stefan Wörner,Kerstin Amann,Bernhard N Bohnert,Matthias Wörn,Andrea Janessa,Mengyun Xiao,Christoph Daniel,Andreas L Birkenfeld,Ferruh Artunc

doi:10.1038/s41401-021-00628-1

Abstract

Treatment with aprotinin, a broad-spectrum serine protease inhibitor with a molecular weight of 6512 Da, was associated with acute kidney injury, which was one of the reasons for withdrawal from the market in 2007. Inhibition of renal serine proteases regulating the epithelial sodium channel ENaC could be a possible mechanism. Herein, we studied the effect of aprotinin in wild-type 129S1/SvImJ mice on sodium handling, tubular function, and integrity under a control and low-salt diet. Mice were studied in metabolic cages, and aprotinin was delivered by subcutaneously implanted sustained release pellets (2 mg/day over 10 days). Mean urinary aprotinin concentration ranged between 642 ± 135 (day 2) and 127 ± 16 (day 8) µg/mL . Aprotinin caused impaired sodium preservation under a low-salt diet while stimulating excessive hyperaldosteronism and unexpectedly, proteolytic activation of ENaC. Aprotinin inhibited proximal tubular function leading to glucosuria and proteinuria. Plasma urea and cystatin C concentration increased significantly under aprotinin treatment. Kidney tissues from aprotinin-treated mice showed accumulation of intracellular aprotinin and expression of the kidney injury molecule 1 (KIM-1). In electron microscopy, electron-dense deposits were observed. There was no evidence for kidney injury in mice treated with a lower aprotinin dose (0.5 mg/day). In conclusion, high doses of aprotinin exert nephrotoxic effects by accumulation in the tubular system of healthy mice, leading to inhibition of proximal tubular function and counterregulatory stimulation of ENaC-mediated sodium transport.

Highlights

Aprotinin is a broad-spectrum serine protease inhibitor that was first isolated from cow parotis gland and pancreas in the 1930s
Our study demonstrates that aprotinin treatment in high doses led to proximal tubular dysfunction in healthy wild-type mice as reflected by impaired sodium preservation, glucosuria, and proteinuria
High-dose aprotinin treatment led to kidney injury and reduced glomerular filtration rate as evidenced by increased plasma creatinine, urea and cystatin C concentration, increased tubular sclerosis index (TSI), and most strikingly positive staining for kidney injury molecule 1 (KIM-1)

Summary

Introduction

Aprotinin is a broad-spectrum serine protease inhibitor that was first isolated from cow parotis gland and pancreas in the 1930s. It is an unselective inhibitor of trypsin-like serine proteases such as trypsin, plasmin, plasma and tissue kallikreins, coagulation factor XII, and others [1]. Between 2006 and 2008, studies appeared that found an increased risk for renal dysfunction and even mortality in patients undergoing cardiac surgery who were treated with aprotinin [3,4,5,6]. After early termination of the BART trial (Blood Conservation Using Antifibrinolytics in a Randomized Trial) due to increased mortality of aprotinin-treated patients [7], aprotinin was withdrawn from the market in 2007. In the last years aprotinin is being reintroduced in Europe and Canada after reevaluation of the safety data, highlighting several methodological limitations [9]

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