ADAM17 substrate release in proximal tubule drives kidney fibrosis
Eirini Kefaloyianni, Muthu Lakshmi Muthu, Jakob Kaeppler, Xiaoming Sun, Venkata Sabbisetti, Athena Chalaris, Stefan Rose-John, Eitan Wong, Irit Sagi, Sushrut S. Waikar, Helmut Rennke, Benjamin D. Humphreys, Joseph V. Bonventre, Andreas Herrlich
Eirini Kefaloyianni, Muthu Lakshmi Muthu, Jakob Kaeppler, Xiaoming Sun, Venkata Sabbisetti, Athena Chalaris, Stefan Rose-John, Eitan Wong, Irit Sagi, Sushrut S. Waikar, Helmut Rennke, Benjamin D. Humphreys, Joseph V. Bonventre, Andreas Herrlich
View: Text | PDF
Research Article Cell biology Nephrology

ADAM17 substrate release in proximal tubule drives kidney fibrosis

Abstract

Kidney fibrosis following kidney injury is an unresolved health problem and causes significant morbidity and mortality worldwide. In a study into its molecular mechanism, we identified essential causative features. Acute or chronic kidney injury causes sustained elevation of a disintegrin and metalloprotease 17 (ADAM17); of its cleavage-activated proligand substrates, in particular of pro-TNFα and the EGFR ligand amphiregulin (pro-AREG); and of the substrates’ receptors. As a consequence, EGFR is persistently activated and triggers the synthesis and release of proinflammatory and profibrotic factors, resulting in macrophage/neutrophil ingress and fibrosis. ADAM17 hypomorphic mice, specific ADAM17 inhibitor–treated WT mice, or mice with inducible KO of ADAM17 in proximal tubule (Slc34a1-Cre) were significantly protected against these effects. In vitro, in proximal tubule cells, we show that AREG has unique profibrotic actions that are potentiated by TNFα-induced AREG cleavage. In vivo, in acute kidney injury (AKI) and chronic kidney disease (CKD, fibrosis) patients, soluble AREG is indeed highly upregulated in human urine, and both ADAM17 and AREG expression show strong positive correlation with fibrosis markers in related kidney biopsies. Our results indicate that targeting of the ADAM17 pathway represents a therapeutic target for human kidney fibrosis.

Authors

Eirini Kefaloyianni, Muthu Lakshmi Muthu, Jakob Kaeppler, Xiaoming Sun, Venkata Sabbisetti, Athena Chalaris, Stefan Rose-John, Eitan Wong, Irit Sagi, Sushrut S. Waikar, Helmut Rennke, Benjamin D. Humphreys, Joseph V. Bonventre, Andreas Herrlich

×

Figure 4

IRI-induced ADAM17 pathway components are reduced in ADAM17ex/ex mice.

Options: View larger image (or click on image) Download as PowerPoint
IRI-induced ADAM17 pathway components are reduced in ADAM17ex/ex mice. T...
The expression levels of ADAM17 and its pathway components were examined at different time points after ischemic injury in whole kidneys. (A) qPCR analysis of ADAM17 mRNA expression levels in ex/ex or WT/WT mice, expressed as fold over respective sham-injured mice (n = 3–5). (B) Western blot analysis of ADAM17 protein levels in ex/ex or WT/WT mice subjected to sham or IRI (day 5 after ischemia) (left: sample blots; right: quantification; GAPDH was used as loading control; n = 5). (C–H) qPCR analysis of EGFR ligands, EGFR, TNFα, and TNFR1/2 mRNA expression levels in ex/ex or WT/WT mice, expressed as fold over respective sham-injured mice (time points as indicated; n = 3–6). (I) Soluble ectodomains of the ADAM17 substrates TNFα, TGFα, and AREG were measured in whole kidney lysates of WT/WT or ex/ex mice at day 2 after ischemia by ELISA (ADAM10 substrate cMET is used as control; n = 4). (J) Time-course of EGFR phosphorylation (Y1068) as measured by Western blot in whole kidney lysates of WT/WT or ex/ex mice (n = 5). (K) Representative images of EGFR phosphorylation (Y1173) examined in kidney cortex by immunostaining in WT/WT or ex/ex mice at day 2 after injury (left: representative images; right: quantification; n = 3; scale bar: 50 μm). *P < 0.05; **P < 0.01; ***P < 0.001 as determined by an unpaired 2-tailed Student’s t test. ADAM17; a disintegrin and metalloprotease 17; EGFR, epidermal growth factor receptor; IRI, ischemia reperfusion injury; NS, nonspecific band; TNFα, tumor necrosis factor α; TNFR, tumor necrosis factor receptor; AREG, amphiregulin; ADAM10, a disintegrin and metalloprotease 10; cMet, met proto-oncogene; WB, Western blot.