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Kidney Week

Abstract: SA-PO735

IL-6-Mediated Phosphorylation of STAT3 at Tyrosine 705 Leads to Proliferation of Pericytes and Fibroblasts

Session Information

  • CKD: Mechanisms - III
    November 09, 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

  • Zhao, Li, Brigham and Women's Hospital, Harvard Medical School, Boston, United States
  • Ajay, Amrendra Kumar, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Hsiao, Li-Li, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States
Background

Fibrosis is a final common pathway that leads to progressive chronic kidney disease (CKD) and end stage renal disease.Inflammation is one of the many events occurrs during the progression of CKD. IL-6,an inflammatory cytokine, contributes to kidney disease by enhancing the signaling response of tubular epithelial cells to profibrotic cytokines. STAT3 is known to be activated following phosphorylation at tyrosine 705 in response to IL-6, which plays a key role in many cellular processes such as cell proliferation and apoptosis. The role of IL-6/STAT3 pathway in the differentiation of specific cell types and its outcome in kidney fibrosis remains largely unknown.

Methods

We used the mouse pericyte cell line 10T1/2 and human fibroblast cells. We treated these cells with different doses (20 ng/ml to 300 ng/ml) of recombinant IL-6 for different time points. Phosphorylation of STAT3 was evaluated by western blot and immunofluorescence using anti-phospho-STAT3 specific antibody. To assess the cellular proliferation, we used MTS assay. The cellular migration was examined by trans well chamber method. The expression of pro-fibrotic markers was detected by RT-PCR, immunofluorescence and western blot analysis.

Results

IL-6 induced the activation of STAT3 in 10T1/2 and human fibroblast cells, and up-regulated the phosphorylation of STAT3 (Tyr705) in a dose and time dependent manner. The dose of IL-6 for activation of STAT3 was different in these two cell types (10T1/2 and human fibroblasts showed pSTAT3 at 20 and 300 ng/ml respectively). After phosphorylation, STAT3 was translocated to the nucleus, which is crucial for its transcriptional activity. IL-6 mediated phosphorylation of STAT3 caused cellular proliferation of human fibroblasts (at 72 hours by 123.88% and of mouse pericytes 10T1/2 (at 96 hours by 131.71%) as compared to respective control cells. pSTAT3 increased the expression levels of α-SMA, Collagen 1 and fibronectin.

Conclusion

IL-6/STAT3 pathway may participate in cellular proliferation of pericytes and fibroblasts during fibrosis development and its inhibition may reduce the proliferation of these cells leading to reduced fibrosis.

Funding

  • Private Foundation Support