Abstract: TH-PO565

Preferential Utilization of Histidine as a Glucogenic Amino Acid for PKD Cyst Growth

Session Information

Category: Genetic Diseases of the Kidney

  • 801 Cystic Kidney Diseases

Authors

  • Chen, Peili, University of Chicago, Chicago, Illinois, United States
  • Ma, Chunyu, Emory University, Atlanta, Georgia, United States
  • Chapman, Arlene B., University of Chicago, Chicago, Illinois, United States
Background

Autosomal dominant polycystic kidney disease (PKD) is a proliferative disorder characterized by progressive development of renal cysts and renal failure. Alterations in metabolism in patients with PKD have been identified with increased representation of the histidine pathway with increasing disease severity. Histidine has multiple roles, regulating intracellular pH, entry into the Krebs cycle via glutamate/α-ketoglutarate, shared pathways with purine metabolism and generation of histamine for host defense purposes. To understand the role of histidine in PKD epithelial cell proliferation, non-targeted metabolomic analysis of cystic and non-cystic tubular epithelial cells were evaluated.

Methods

Primary human PKD cyst epithelial and human proximal and distal tubular cell lines were established. Conditioned media (8 replicates/sample) were harvested after 24h-incubation and subjected to high-resolution liquid chromatography mass spectrometry (LC-MS). Histidine decarboxylase inhibitor, α-fluromethylhistidine (α -FMH) in increasing doses (0-10uM) was administered and cell proliferation rates measured over 48 hrs with XTT assays. Data were analyzed using xMSanalyzer to identify metabolic features after normalization for protein content. Significant features were subjected to metabolic pathway analysis and enrichment with Mummichog.

Results

Metabolites were differentially expressed between PKD cells and controls. Histidine, histamine and methylimidazole acetaldehyde were decreased (P<0.05) in cystic cells vs. control media. Terminal histamine pathways not leading to further energy metabolism were decreased in cystic vs non-cystic cells (p<0.05). Aspartate and glutamate (entry points to the Krebs cycle) were increased in cystic vs. non-cystic cells (P<0.05). Cystic cells demonstrated an up to 21% increase in proliferation with α-FMH compared to baseline (P<0.05), and greater than non-cystic cells (P<0.001).

Conclusion

Histidine metabolism is abnormal PKD cystic epithelia demonstrating increased generation of aspartate and glutamate, precursors for energy generation. Inhibition of histidine decarboxylase reduced histamine generation, and thereby increased cell proliferation, consistent with increased energy substrate availability.

Funding

  • NIDDK Support