Kidney Week

Abstract: FR-OR104

Amphiregulin Drives Kidney Fibrosis in Mice and Its Elevated Serum Levels Correlate with CKD Outcomes in Humans

Session Information

• Signaling in CKD Progression
  October 26, 2018 | Location: 23A, San Diego Convention Center
  Abstract Time: 04:54 PM - 05:06 PM

Category: CKD (Non-Dialysis)

• 1903 CKD (Non-Dialysis): Mechanisms

Authors

• Kefalogianni, Eirini, Washington University in St. Louis, St. Louis, Missouri, United States

Eirini Kefalogianni, PhD

• Keerthi raja, Manikanda raja, Washington University in St. Louis, St. Louis, Missouri, United States

Manikanda raja Keerthi raja,

• Pliaka, Vaia, Protavio, Athens, Greece

Vaia Pliaka,

• Schumacher, Julian, Washington University in St. Louis, St. Louis, Missouri, United States

Julian Schumacher,

• Alexopoulos, Leonidas G., National Technical Univ of Athens, Glyfada, Greece

Leonidas G. Alexopoulos,

• Waikar, Sushrut S., Harvard Medical School , Boston, Massachusetts, United States

Sushrut S. Waikar,

• Herrlich, Andreas, Washington University in St. Louis, St. Louis, Missouri, United States

Andreas Herrlich,

Background

We have shown that ADAM17-released EGFR ligands in proximal tubule cells (PTCs) drive kidney fibrosis in IRI and UUO kidney injury models (Kefaloyianni et al, JCI Insight 2016). Which specific EGFR ligands are involved remains unknown. We showed that amphiregulin (AREG) is the most upregulated EGFR ligand after kidney injury in mice and the most potent EGFR ligand in inducing pro-inflammatory and pro-fibrotic genes in human PTCs (HPTCs) in vitro. Soluble AREG (sAREG) is significantly elevated in the urine of AKI and CKD patients and AREG protein is elevated in CKD biopsies, as compared to healthy controls. It is not known whether AREG has a key role in mediating injury-induced kidney fibrosis in mice and humans.

Methods

We used tamoxifen inducible AREG^fl/fl-Slc34a1^GCE+/--tdTomato⁺ (AREG-PTC KO) mice and ADAM17^fl/fl-Slc34a1^GCE+/--tdTomato⁺ (ADAM17-PTC KO) mice and their respective wt littermates, as well as HPTCs transfected with control or YAP1 siRNA. We also developed and extensively validated a sensitive bead-based ELISA for sAREG in human serum samples.

Results

We found that sAREG can uniquely sustain EGFR activation in HPTC in vitro via YAP1-dependent upregulation of its own transcript, followed by ADAM17-dependent release of sAREG (positive feedback). In vivo, AREG-PTC-KO reduced IRI-induced sustained EGFR phosphorylation, as well as upregulation of pro-inflammatory cytokines and pro-fibrotic markers. We show that in ADAM17-PTC-KO mice, which cannot release any injury-induced EGFR ligand in PTC, injection of sAREG alone is sufficient to induce production of pro-inflammatory and pro-fibrotic factors to the levels of ADAM17 wt mice. Finally, we show that sAREG serum levels correlate positively with serum creatinine and CKD stage and negatively with eGFR in a nephrectomy cohort (n=69) of patients with various diagnosis and levels of fibrosis.

Conclusion

These results suggest that AREG is a major driver of kidney fibrosis in mice and humans, acting via a YAP1-dependent positive feedback loop that sustains EGFR activation and induces pro-inflammatory and pro-fibrotic cytokines, and represents a potential functional marker of fibrosis and CKD progression.

Funding

• NIDDK Support