Kidney Week

Abstract: SA-PO620

Human Hypoxic Proximal Tubule Epithelial Cells (PTECs) Trigger NLRP3 Inflammasome Activation in CD1c⁺ Dendritic Cells (DC)

Session Information

• Glomerular Diseases: Immunology, Inflammation - II
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1202 Glomerular Diseases: Immunology and Inflammation

Authors

• Healy, Helen G., Pathology Queensland/RBWH, Brisbane, Queensland, Australia

Helen G. Healy,

• Giuliani, Kurt Thomas Karl, Pathology Queensland/RBWH, Brisbane, Queensland, Australia

Kurt Thomas Karl Giuliani,

• Wang, Xiangju, Pathology Queensland/RBWH, Brisbane, Queensland, Australia

Xiangju Wang,

• Forbes, Josephine M., University of Queensland, Brisbane, Queensland, Australia

Josephine M. Forbes,

• Kassianos, Andrew J., Pathology Queensland/RBWH, Brisbane, Queensland, Australia

Andrew J. Kassianos,

Background

Chronic kidney disease (CKD) is characterised by inflammation and tubulointerstitial fibrosis. Hypoxia is a key driver of this pathology. Kidney proximal tubule epithelial cells (PTEC) are particularly susceptible to oxygen imbalances due to their high rates of aerobic respiration. We have reported activated CD1c⁺ dendritic cells (DC) adjacent to PTEC in fibrotic kidney tissue, where they are well positioned to sense PTEC-derived danger signals via the NLRP3 inflammasome. In this study, we examined the hypoxic response in human PTEC and their functional role in CD1c⁺ DC activation.

Methods

Primary human PTEC were cultured under normoxia (21% O₂) or hypoxia (1% O₂) and assessed for mitochondrial function, proliferation and viability. PTEC-CD1c⁺ DC interactions were examined by in vitro co-culture in the absence or presence of NLRP3 inflammasome inhibitor MCC950. DC activation was assessed by mRNA profiling and cytokine secretion. In vivo cellular interactions in fibrotic kidney tissue were examined by immunofluorescence microscopy.

Results

Hypoxic PTEC displayed significant mitochondrial dysfunction, significantly reduced proliferation and significantly increased cell death compared to normoxic PTEC. CD1c⁺ DC matured in the presence of hypoxic PTEC showed increased NLRP3 mRNA expression and secreted significantly elevated levels of inflammasome-related cytokines (IL-1β, IL-18). Notably, this pro-inflammatory response was significantly reduced in the presence of the NLRP3 inflammasome inhibitor, MCC950. Immunofluorescence staining of fibrotic kidney tissue identified PTEC co-localized with CD1c⁺ DC expressing downstream signalling markers of NLRP3 inflammasome activation (active Caspase-1).

Conclusion

Our data demonstrate that hypoxic PTEC trigger and activate CD1c⁺ DC via the NLRP3 inflammasome, resulting in the secretion of pro-inflammatory cytokines. Future studies will examine the putative role of mitochondrial danger signals generated by hypoxic PTEC for therapeutic targeting in human CKD.

Funding

• Government Support - Non-U.S.