Human hypoxic proximal tubule epithelial cells modulate CD1c<sup>+ </sup>dendritic cell function — ASN Events
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  2. Poster Session Two
  3. Human hypoxic proximal tubule epithelial cells modulate CD1c+ dendritic cell function

Human hypoxic proximal tubule epithelial cells modulate CD1c+ dendritic cell function (#271)

Melissa J Rist 1 2 , Xiangju Wang 1 2 , Ray Wilkinson 1 2 3 4 , Andrew Kassianos 1 2 3 4 , Helen Healy 1 2
  1. Conjoint Kidney Research Laboratory, Pathology Queensland, Herston, QUEENSLAND, Australia
  2. Kidney Health Service, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
  3. Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
  4. School of Medicine, University of Queensland, Brisbane, QLD, Australia

BACKGROUND: Chronic kidney disease (CKD) is the most prevalent chronic disease in Australia, characterised by inflammation and tubulointerstitial fibrosis. Hypoxia is a powerful bio-pathological driver of this inflammation/fibrosis. Proximal tubule epithelial cells (PTEC) of the kidney are particularly susceptible to oxygen imbalances as they depend solely on aerobic oxidative metabolism.  We have previously shown activated human CD1c+ dendritic cells (DC) to be instrumental in this inflammatory/pro-fibrotic environment.  As CD1c+ DC aggregate adjacent to PTEC, they are aptly positioned to receive danger signals and become activated by hypoxic PTEC. In this novel study we examined the hypoxic response in primary human PTEC as well as their functional role in CD1c+ DC activation. 

METHODS: Primary human PTEC were cultured under normoxic (21% O2), hypoxic (1% O2) and hypoxic + inflammatory (1% O2 + IFN-γ/TNF-α) conditions. PTEC were analysed for cellular proliferation, viability and mitochondrial function. PTEC-CD1c+ DC interactions were examined by in vitro co-culture, with DC activation monitored by surface antigen expression and cytokine secretion.

RESULTS: PTEC exhibited reduced proliferation and increased cell death under hypoxic conditions, most pronounced under hypoxic + inflammatory conditions. Hypoxic PTEC also displayed loss of mitochondrial membrane potential and increased mitochondrial reactive oxygen species production, in particular under hypoxic + inflammatory conditions. CD1c+ DC matured in the presence of hypoxic PTEC expressed elevated levels of activation markers CD83, CD86 and HLA-DR, increased expression of inflammasome component NLRP3 and secreted more pro-inflammatory cytokine IL-1β. With the exception of HLA-DR, upregulation was further augmented under hypoxic + inflammatory conditions.

CONCLUSIONS: Our results suggest that CD1c+ DC activation by hypoxic PTEC may be mediated via an NLRP3 inflammasome-dependent mechanism. We aim to further analyse the signalling pathways in this mechanism, including using inhibitors, to identify candidate therapeutic targets to disrupt inflammation in CKD.

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