Abstract: FR-PO336

Lineage Tracing Study Defines Erythropoietin-Producing Cells as the Distinct Subpopulation of Resident Fibroblasts with Unique Behaviors

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 308 CKD: Mechanisms of Tubulointerstitial Fibrosis

Authors

  • Kaneko, Keiichi, Kyoto University Graduate School of Medicine, Sakyo-ku, KYOTO, Japan
  • Endo, Shuichiro, Kyoto University Graduate School of Medicine, Sakyo-ku, KYOTO, Japan
  • Yanagita, Motoko, Kyoto University Graduate School of Medicine, Sakyo-ku, KYOTO, Japan
Background

We previously demonstrated that renal fibroblasts including erythropoeitin (Epo)-producing cells transdifferentiate into myofibroblasts with concomitant loss of Epo production during renal fibrosis. It has not been elucidated, however, whether Epo-producing cells, which account for less than 10 % of resident fibroblasts, are the distinct specialized population of resident fibroblasts. Lack of tools to label Epo-producing cells at desired time points has hindered our further understanding of the behavior of Epo-producing cells in adult kidneys.

Methods

We generated a novel mouse strain in which inducible Cre, CreERT2 was knocked-in at the locus of Epo gene (Epo-CreERT2 mice). Epo-CreERT2 mice were crossed with indicator mice, and tamoxifen was administered to the offspring to activate CreERT2.

Results

Epo-CreERT2 labeled cells were located in the interstitium of the cortex and corticomedullary region of the kidney, and expressed PDGFRβ and CD73, indicating that these cells were resident fibroblasts. The labeled cells increased in parallel with the magnitude of anemia. Double in situ hybridization confirmed that around 50 % of the labeled cells expressed Epo mRNA, indicating that Epo-CreERT2 mice faithfully labeled the Epo-producing cells. Around 50 % of the labeled cells maintained Epo-producing ability even 16 weeks after the recombination, supporting the hypothesis that the labeled cells are the distinct population with Epo-producing ability. After unilateral ureteral obstruction (UUO), the labeled cells transdifferentiated into myofibroblasts, lost Epo-producing ability, and proliferated. The percentage of the labeled cells in resident fibroblasts increased 4.5 folds during fibrosis (1.9 % in healthy kidney and 9.2 % in UUO kidney, p<0.01), and Ki67 expression was more prevalent in the labeled cells than in other fibroblasts (12.7 % vs 8.3 %, p<0.05).

Conclusion

Utilizing the new mouse strain, Epo-CreERT2 mice, we, for the first time, analyzed the behavior of the Epo-producing cells. The maintenance of Epo-producing ability and faster proliferation during fibrosis indicate the possibility that Epo-producing cells are the distinct populations of renal fibroblasts. Detailed analysis of the population will provide us new therapeutic approach to renal anemia.

Funding

  • Government Support - Non-U.S.