Abstract: FR-PO090
Deletion of the EGFR Ligand Amphiregullin Attenuates Renal Fibrosis After Severe Ischemic Injury by Inactivating Renal Macrophage Responses
Session Information
- AKI: Mechanisms - Inflammation/Sepsis/Remote Injury
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Jin, Guannan, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Pan, Yu, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Wang, Yinqiu, Vanderbilt University, Nashville, Tennessee, United States
- Niu, Aolei, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Wang, Suwan, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Fan, Xiaofeng, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Zhang, Ming-Zhi, Vanderbilt University Medical School, Nashville, Tennessee, United States
- Harris, Raymond C., Vanderbilt University Medical School, Nashville, Tennessee, United States
Group or Team Name
- Vanderbilt nephrology
Background
The activation EGFR signaling pathway is a mediator of recovery from acute kidney injury (AKI) but is also a mediator of renal fibrosis in chronic kidney diseases. EGFR can be activated by a family of ligands including amphiregulin (AREG). Macrophage polarization plays a key role in propagation of AKI and in the development of chronic renal damage. The role of AREG in macrophage polarization and recovery from AKI and subsequent renal fibrosis has not been previously investigated.
Methods
AREG-/- and wild type mice (male, 3 months, C57BL/6) were uninephrectomized, immediately followed by unilateral ischemia-reperfusion for 29 min or 30 min for survival and fibrosis development. An AKI/CKD fibrotic model was also used. Renal macrophages were isolated with a mixture of CD11b and CD11c microbeads. Both a murine macrophage cell line Raw264.7 and a human macrophage cell line THP1 were used.
Results
In both Raw264.7 and THP1 cells, M1 polarization with LPS/IFNγ increased AREG expression. After AKI, AREG was the only EGFR ligand that markedly increased in both kidney and isolated renal macrophages. Surprisingly, renal macrophages of AREG-/- mice exhibited a less activated, M0-like phenotype, being lower in both Th1/M1 (TNF-α, IL-6, IL-1α, IL-1β, CCL-2, IRF5) and Th2/M2 (CD206, IL-4Rα, Arginase 1, YM-1, CD209, CD150) cytokines under normal condition or 2 days after AKI. AREG-/- mice had faster functional recovery after AKI. AREG-/- mice developed less renal fibrosis after severe AKI, as indicated by Sirius red and Masson’s trichrome staining, decreases in profibrotic and fibrotic components (TGF-β, collagen I, III, IV, FSP-1, α-SMA, fibronectin, vimentin, CTGF, IL-11), as indicated by qPCR, immunoblotting, and immunohistochemistry, in association with decreases in renal macrophage and neutrophil infiltration, renal proinflammatory cytokines, and renal injury (less renal KIM-1 and NAGAL expression). AREG-/- also developed less fibrosis in AKI/CKD fibrotic model. Finally, AREG-/- had increased survival rate after severe AKI.
Conclusion
Amphiregulin deficiency protects against AKI and renal fibrosis after severe AKI, at least in part due to less renal macrophage activation in response to kidney injury.
Funding
- NIDDK Support