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Kidney Week

Abstract: TH-PO480

Sphingosine Kinase 2 Deletion in Kidney Pericytes/Fibroblasts Protects Against Kidney Fibrosis via Suppression of Local Interstitial Inflammation

Session Information

  • CKD: Mechanisms - I
    November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

  • 2103 CKD (Non-Dialysis): Mechanisms

Authors

  • Tanaka, Shinji, University of Virginia, Charlottesville, Virginia, United States
  • Zheng, Shuqiu, University of Virginia, Charlottesville, Virginia, United States
  • Kharel, Yugesh, University of Virginia, Charlottesville, Virginia, United States
  • Lipsey, Jonathan E., University of Virginia, Charlottesville, Virginia, United States
  • Rosin, Diane L., University of Virginia, Charlottesville, Virginia, United States
  • Lynch, Kevin, University of Virginia, Charlottesville, Virginia, United States
  • Okusa, Mark D., University of Virginia, Charlottesville, Virginia, United States
Background

Sphingosine 1-phosphate (S1P), which is produced by two different kinases, sphingosine kinase (SphK) 1 and 2, is a sphingolipid involved in myriad cell functions. We recently showed that Sphk2/ mice were protected from renal fibrosis when compared to wild type or Sphk1/ mice; bone marrow chimera experiments suggested that Sphk2 deletion in non-hematopoietic cells contributed to the protection (PMID: 27799486). We hypothesized that Sphk2 deletion in renal pericytes/fibroblasts confers the protection from progressive kidney fibrosis.

Methods

Folic acid (250 mg/kg) was given i.p. to male Foxd1Cre+ Sphk2fl/fl (perivascular (pv) Sphk2KO) mice and Foxd1CreSphk2fl/fl (WT) mice. For unilateral ischemia-reperfusion injury (IRI), left kidney was clamped for 30 min; right nephrectomy was performed at day 13. For bilateral IRI, both kidneys were clamped for 30 min. Mice were euthanized at day 14 to evaluate kidney fibrosis (folic acid and unilateral IRI) and at day 1 to evaluate the extent of acute kidney injury (folic acid and bilateral IRI). Primary renal pv cells were isolated from kidneys of pvSphk2KO mice and WT mice.

Results

In both folic acid and unilateral IRI models, pvSphk2KO mice demonstrated better kidney function (pCr, BUN), less kidney fibrosis (histology) with less macrophage infiltration, and suppressed expression of fibrosis-related genes (Acta2, Col1a1, Col3a1) in the kidneys compared with WT mice. In contrast, there was no difference between pvSphk2KO mice and WT mice in kidney function, kidney Kim-1/Ngal expression, and histology at day 1. In in vitro studies, the expression level of Sphk2 was much higher than that of Sphk1 in WT pv cells. Sphk2 KO pv cells expressed less inflammatory cytokines, such as Ccl2, Il6, Cxcl1, after LPS stimulation compared with WT pv cells. Furthermore, treatment with a selective Sphk2 inhibitor (SLM6031434) recapitulated the phenotype of Sphk2 KO pv cells.

Conclusion

Sphk2 deletion in renal pericytes/fibroblasts was protective against kidney fibrosis. In vitro studies suggested that suppressed production of S1P in Sphk2 KO pericytes/fibroblasts contributes to suppressed expression of inflammatory cytokines when injury occurs, leading to less immune cell infiltration into the kidneys and ameliorated kidney fibrosis.

Funding

  • NIDDK Support