Clinical Kidney Journal, 2021, vol. 14, no. 1, 424–428 doi: 10.1093/ckj/sfz104 Advance Access Publication Date: 23 August 2019 Exceptional Case EXCEPTIONAL CASE Podocyte and tubular involvement in AngioJet-induced kidney injury Raquel Esteras1,2,*, Pablo Cannata-Ortiz2,3,*, Marta del Palacio-Tamarit4, Melania Guerrero-Hue5,6, Cristina Garcı́a-Caballero5,6, Jesús Egido1,7, Javier Gimeno8, Alberto Ortiz1,2, Carolina Gracia-Iguacel1,2,# and Juan Antonio Moreno 5,6,# 1 Department of Nephrology, Fundacion Jimenez Diaz Health Research Institute (IIS-FJD), Autonoma University of Madrid, Madrid, Spain, 2Red de Investigacion Renal, Madrid, Spain, 3Department of Pathology, Fundacion Jimenez Diaz University Hospital, Madrid, Spain, 4Department of Internal Medicine, Fundacion Jimenez Diaz University Hospital, Madrid, Spain, 5Renal, Vascular and Diabetes Research Laboratory, Fundacion Jimenez Diaz Health Research Institute, Autonoma University of Madrid, Madrid, Spain, 6 Department of Cell Biology, Physiology and Immunology, Maimonides Biomedical Research Institute of Cordoba, University of Córdoba, Córdoba, Spain, 7Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders, Madrid, Spain and 8Department of Pathology, Hospital del Mar, Barcelona, Spain Correspondence and offprint requests to: Carolina Gracia-Iguacel; Email: cgracia1@fjd.es, Juan Antonio Moreno; Email: juan.moreno@uco.es * These authors contributed equally to this work. # These authors share senior authorship. ABSTRACT The AngioJet technique combines localized thrombolysis and percutaneous mechanical thrombectomy (PMT). However, PMT may cause acute kidney injury (AKI), which has been ascribed to severe mechanical haemolysis, although no renal biopsies have been reported. We now report the first renal biopsy in a patient with AKI following PMT. There is histological evidence of haemoglobin (Hb)-induced tubular injury and podocyte stress characterized by intracellular Hb and staining for ferritin and hemo-oxygenase-1, suggestive of an adaptive response to oxidative stress. This confirms that Hb is involved in kidney cell injury and supports the existence of several different kidney cellular targets. Keywords: acute kidney injury, AngioJet, haemoglobinuria, mechanical thrombolysis, podocyte, tubular cell Received: 23.2.2019; Editorial decision: 10.7.2019 C The Author(s) 2019. Published by Oxford University Press on behalf of ERA-EDTA. V This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com 424 AngioJet-induced kidney injury | 425 INTRODUCTION temporary dialysis (from 20 days to 5 months) [2, 3]. We present the first renal biopsy reported in this condition, which provided Percutaneous mechanical thrombectomy (PMT) using the insights into the pathogenesis and involvement of different cell AngioJet technique is used to treat arterial and deep vein types. Circulating free Hb filters freely through the glomerular thrombosis [1]. AngioJet combines a localized thrombolysis capillary wall and its toxicity to proximal tubular cells that up- agent and PMT with a guided catheter that destroys and aspi- take Hb is well characterized. Hb is reabsorbed by proximal rates the thrombus. However, PMT may cause acute kidney in- tubules through the megalin/cubilin receptor complex, causing jury (AKI), which has been ascribed to severe mechanical oxidative stress, mitochondrial damage and cell death, as well haemolysis, although no renal biopsies have been reported [2, as the release of inflammatory cytokines, which would explain 3]. We now report the first renal biopsy in post-PMT AKI and the tubular damage and the inflammatory infiltrate observed in histological evidence of podocyte as well as tubular injury. our case. Additionally, Hb decreases nitric oxide availability and causes intratubular obstruction in the distal nephron. CASE REPORT Tubular cells have traditionally been considered the only A 28-year-old man was diagnosed with right subclavian vein cellular target of the adverse effects of Hb in the kidney. thrombosis following a trans-Atlantic flight. Despite oral antico- However, data from our group showed that podocytes are capa- agulation, no improvement was observed and 2 weeks later he ble of capturing Hb, which alters their viability and functionality underwent AngioJet PMT. Six hours post-procedure he com- [4]. Thus Hb increases the production of reactive oxygen species plained of dark brown urine and bilateral lumbar pain. Serum and induces apoptosis in podocytes, as we have observed in creatinine (sCr) was 2.9 mg/dL (baseline 1.0 mg/dL), platelets cells in culture and experimental models of intravascular hemo- 240 000/mL, haemoglobin (Hb) 15 g/dL and lactate dehydrogenase lysis. In addition, we described the presence of podocytes (LDH) 3430 IU/L. He had dipstick haematuria þ1 and proteinuria loaded with Hb in biopsies of patients with atypical haemolytic 70 mg/dL. Despite intravenous fluid (0.9% sodium chloride and uremic syndrome (aHUS) and severe haemolysis [4]. Podocytes 5% dextrose, 3000–5000 mL/day) and urine alkalinization, 5 days stained for Hb and ferritin, suggesting iron overload; phosphor- post-procedure (Supplementary data, Figure S1) his sCr was ylated pNrf2, a transcription factor driving antioxidant 9.78 mg/dL, Hb 11 g/dL, platelets 180 000/mL, LDH 1030 IU/L, indi- responses, and HO-1, an antioxidant enzyme that is part of the rect bilirubin 1.3 mg/dL and haptoglobin 5 mg/dL. Direct Coombs pNrf2-driven adaptive antioxidant response, were reported in test was negative and no schistocytes were observed. Dipstick patients with aHUS. These features support the concept of Hb- haematuria persisted, urinary protein:creatinine ratio was driven podocyte involvement in aHUS. 731 mg/g and albuminuria was 191 mg/g. Prednisone 40 mg/24 h While albuminuria was not very severe in our patient, there was started after renal biopsy. is evidence from other nephropathies, such as childhood Fabry The renal biopsy contained 20 glomeruli: these and the ves- nephropathy, suggesting that histological evidence of podocyte sels in the biopsy appeared normal by light microscopy. injury (lysosomal accumulation followed by foot process widen- Immunofluorescence for immunoglobulin G (IgG), IgA, IgM, C3 ing followed by foot process effacement) precedes the develop- and light chains was negative. Severe diffuse acute tubular ment of pathological albuminuria and that a continuum of damage was characterized by tubular necrosis, occasional tubu- podocyte injury and resulting albuminuria exists [5]. aHUS is lar basement membrane ruptures and adjacent interstitial in- characterized by additional features, such as a local inflamma- flammatory reaction (Figure 1A and B). Tubules were filled with tory response and local kidney and glomerular thrombotic abundant debris encompassing necrotic tubular cells, granular microangiopathy. Therefore the results of the present case re- erythrocyte degeneration debris, isolated red blood cells and, in port represent a purer haemolysis model and confirms both the proximal tubules, eosinophilic filiform aggregates that stained Hb-driven nature of AKI in AngioJet-induced AKI as well as the for Hb (Figure 1B). Hb was observed in the cytoplasm of glomer- possible role of the podocyte as a new cellular target for the ad- ular capillary endothelium, podocytes and tubular cells verse effects of haemoglobinuria. (Figure 2A and C). Tubular epithelial cells and podocytes stained In conclusion, intravascular haemolysis secondary to me- for ferritin and hemo-oxygenase-1 (HO-1), suggestive of iron chanical thrombectomy due to AngioJet is associated with AKI overload and an adaptive response to oxidative stress, respec- characterized by acute tubular necrosis and podocyte involve- tively. The use of transmission electron microscopy showed ment. This is the first histological description of AKI following mild podocyte damage, with foot process widening, large intra- this procedure. cellular vacuoles and electron-dense iron deposits (Figure 2B). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining confirmed the presence of dead intratubular SUPPLEMENTARY DATA cells (Figure 2D). Supplementary data are available at ckj online. Ten days after the procedure, sCr peaked at 12 mg/dL while haemolysis was improving (haptoglobin 159 mg/dL, LDH 800 IU/ L). Albuminuria was 288 mg/day and proteinuria was 900 mg/ FUNDING day 12 days after thrombectomy. sCr and urinalysis normalized This work was supported by FIS/FEDER CP16/00017, PI16/ 2 months after the procedure. 02057, PI17/00130, PI17/01495, ISCIII-RETIC Red de Investigacion Renal RD016/0009 FEDER funds, Spanish DISCUSSION Ministry of Economy and Competitiveness (RYC-2017- The incidence of AKI is higher following PMT than following 22369), Sociedad Espan ~ ola de Nefrologı́a, Fundacion Renal catheter-guided thrombolysis without mechanical thrombec- ~ igo Álvarez de Toledo and Comunidad de Madrid CIFRA2 In tomy (20–29% versus 0–8%) [1, 3]. The average AKI duration was B2017/BMD-3686. Guerrero-Hue M. was supported by FIS/ 5 days [1]. However, AKI may be severe enough to require FEDER FI18/00310. 426 | R. Esteras et al. FIGURE 1: Characteristics of the renal biopsy. (A) A fresh renal biopsy specimen under a dissecting microscope (left; fresh 40) showing brownish and red casts that highlight the proximal tubules of renal cortex (red arrowheads), corresponding with microscopic evidence of foci of acute tubular necrosis, loss of brush border and intratubular contents composed of cell debris and protein [middle panel, haematoxylin and eosin (HE 400, white arrowheads]. The right upper panel shows heteroge- neous tubular casts with compact moderately electron dense areas, similar to erythrocyte cytoplasm, admixed with smaller and strongly electron dense material (blue arrowheads). The right lower panel shows a detail of electron dense material, showing a vaguely crystallized appearance, identified in the cytoplasm of some cortical tubules (green arrowheads). (B) The left panel shows an H&E image (400) of a proximal tubule in its first portion filled with eosinophilic filiform content corresponding to free Hb filtered by the glomerulus (yellow arrowheads), as identified by specific immunostaining shown in the right panel for Hb (green). Additional staining was for podocytes [synaptopodin (Syn), red] and nuclei [40 ,6-diamidino-2-phenylindole (DAPI), blue], as determined by confocal microscopy. AngioJet-induced kidney injury | 427 FIGURE 2: Glomerular and tubular immunostaining of the renal biopsy. (A) Representative confocal microscopy images showing co-localization (white arrowheads) of Hb (green), ferritin (green) and HO-1 (green) with the podocyte marker synaptopodin (Syn, red) in the renal biopsy of the patient with AKI haemolysis. Note that there was no staining in the control samples from non-tumour renal tissue after surgery in patients with kidney cancer. The rectangle shows the region of interest for which high-magnification images are shown in the lower panels. (B) Representative images of transmission electronic microscopy showing a high number of vacuoles (left panel, yellow arrowheads) and the presence of intensely electron dense and compact cytoplasmic inclusions (right panel, black arrowheads) in podocytes as well as foot process widening in the renal biopsy of the patient. (C) Localization of Hb (green), ferritin (green) and HO-1 (green) in tubular epithelium. (D) Representative confo- cal microscopy images showing the presence of dead intratubular cells (TUNEL-positive cells, green). Nuclei were stained with [40 ,6-diamidino-2-phenylindole (DAPI), blue]. Scale bars: 50 mm. 428 | R. Esteras et al. CONFLICT OF INTEREST STATEMENT 3. Escobar GA, Burks D, Abate MR et al. Risk of acute kidney in- jury after percutaneous pharmacomechanical thrombectomy None declared. using AngioJet in venous and arterial thrombosis. 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