Abstract: TH-PO322

Analysis of Molecular Mechanisms of Human Kidney Tubulointerstitial Disease Driven by Interleukin 1β

Session Information

Category: Acute Kidney Injury

  • 002 AKI: Repair and Regeneration

Authors

  • Lemos, Dario R., Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Bonventre, Joseph V., Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Morizane, Ryuji, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Gupta, Navin R., Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Garcia, Edgar, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Wilflingseder, Julia, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Miyoshi, Tomoya, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Susa, Koichiro, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Wang, Guanghai, Southern Medical University , Guangzhou, China
  • Duffield, Jeremy Stuart, Vertex Pharmaceuticals, Boston, Massachusetts, United States
Background

Tubulointerstitial disease is characterized by tubular damage with interstitial fibrosis and persistent inflammation. While the deleterious effect of the whole inflammatory response is well documented, contribution of specific cytokines is virtually impossible to study in vivo.

Methods

Combined whole genome human data analysis with hPSC-derived organoid technology, experimental mouse models and CRISPR/CAS9 technology.

Results

Whole genome analysis of patients with severe kidney fibrosis indicated a correlation between inflammatory cytokines, mitochondria damage and elevated levels of glycolytic enzymes suggesting that inflammatory and metabolic pathways are mechanistically related. To overcome the limitations of studying inflammatory signals in vivo, we tested the effect of single inflammatory cytokines on human kidney organoids. Among other damage mechanisms, we found that IL1β stimulation resulted in cell cycle arrest in proximal tubule epithelial cells after 48hr, and KIM1-expressing damaged proximal tubules with near complete absence of brush borders 96hr post stimulation. Simultaneously, IL1β induced the proliferation and differentiation of stromal fibrogenic cells, resulting in hypertrophic expansion of the interstitium, and interstitial fibrosis. Further investigation into the mechanisms of fibrosis revealed the activation of MYC in organoid stromal PDGFRβ+ cells. Nuclear localization of MYC in interstitial fibrogenic cells was confirmed in Col1a1-GFP mice 72hs after acute damage in vivo. IL1β stimulation of human PDGFRβ+ fibrogenic precursor cells purified from human kidneys in vitro induced autophagy, loss of SQSTM1/P62 reduced mTOR signaling and triggered a MYC-dependent metabolic proliferative program encompassing upregulation of glycolysis enzymes and cyclin kinases. Mechanistically, in the absence of IL1β, SQSTM1/P62 interacts directly with MYC, driving its proteasomal degradation to keep MYC levels low. That interaction is interrupted by IL1β through induction of autophagy, resulting in SQSTM1/P62 degradation and MYC stabilization.

Conclusion

By studying components of the inflammatory response separately, we identified a novel molecular mechanism for tubulointerstitial disease triggered by one single inflammatory cytokine, namely IL1β.

Funding

  • Other NIH Support