Abstract: TH-PO391

TWEAK Increases CD74 Expression and Sensitizes to DDT Proinflammatory Actions in Tubular Cells

Session Information

Category: Cell Biology

  • 203 Growth Factors, Chemokines, Autacoids

Authors

  • Valiño rivas, Lara, Hospital Universitario Fundación Jiménez Díaz, Madrid, Spain
  • Bucala, Richard, Yale University School of Medicine, New Haven, Connecticut, United States
  • Leng, Lin, Yale School of Medicine, New Haven, Connecticut, United States
  • Sanz, Ana Belen, Instituto de Investigacion Sanitaria Fundacion Jimenez Diaz, Madrid, Spain
  • Gonzalez-Lafuente, Laura, IIS-Fundacion Jimenez Diaz, Madrid, Spain
  • Ortiz, Alberto, Fundacion Jimenez Diaz, Madrid, Spain
  • Sanchez-Nino, Maria Dolores, Fundacion Jimenez Diaz, Madrid, Spain
Background

TWEAK is a proinflammatory cytokine that promotes kidney injury. CD74 is a multifunctional protein upregulated in diabetic kidney disease another chronic nephropathies. One function of CD74 is being a receptor for Macrophage Migration Inhibitory Factor (MIF) and for the recently described MIF-2 / D-dopachrome tautomerase (DDT) cytokine. However, the molecular mechanisms of TWEAK-induced kidney injury, the drivers of CD74 expression and the function of DDT function in kidney cells are poorly characterized.

Methods

Wild type (WT) mice received a single i.p. injection of TWEAK. Cell culture studies were performed in murine proximal tubular MCT cells. TWEAK, DDT and MIF expression was determined by immunohistochemistry in kidney tissue from mice. The effects of TWEAK in mice and in cultured tubular cells was assessed by qRT-PCR, Western blot and flow cytometry.

Results

We have now identified CD74 gene expression as upregulated in the kidneys in response to systemic TWEAK administration in mice in a transcriptomics analysis, and have characterized the in vivo CD74 expression and the functional consequences in cultured cells.
TWEAK administration to mice resulted in a progressive time-dependent (up to 24h) upregulation of kidney CD74 mRNA (RT-PCR) and protein (Western blot). Furthermore, the CD74 ligands MIF and DDT were also upregulated at the protein level 24h after TWEAK administration. Immunohistochemistry localized the increased CD74, MIF and DDT expression to tubular cells. In cultured tubular cells, TWEAK increased CD74 mRNA and protein expression dose-dependently, with the temporal pattern similar to the in vivo experiments. TWEAK-induced CD74 localized to the cell membrane, where it can function as a cytokine receptor. For the first time, we explored the actions of DDT in tubular cells and found that DDT amplified the increase in MCP-1 and RANTES expression in response to TWEAK. By contrast, DDT did not significantly modify TWEAK-induced Klotho downregulation.

Conclusion

In conclusion, TWEAK upregulates CD74 and its ligands MIF and DDT in renal tubular cells. This may have functional consequences for kidney injury since DDT amplified the inflammatory response to TWEAK.