Kidney Week

Abstract: SA-OR029

Unravelling Reno-Protective Effects of SGLT2 Inhibition in Human Proximal Tubular Cells

Session Information

• Diabetic Kidney Disease: Mechanisms, Models, and Modulators - II
  October 27, 2018 | Location: 5A, San Diego Convention Center
  Abstract Time: 06:06 PM - 06:18 PM

Category: Diabetic Kidney Disease

• 601 Diabetic Kidney Disease: Basic

Authors

• Pirklbauer, Markus, Medical University Innsbruck, Innsbruck, Austria

Markus Pirklbauer, MD, PhD

• Schupart, Ramona, Medical University Innsbruck, Innsbruck, Austria

Ramona Schupart,

• Fuchs, Lisa, Medical University Innsbruck, Innsbruck, Austria

Lisa Fuchs,

• Staudinger, Petra, Medical University Innsbruck, Innsbruck, Austria

Petra Staudinger,

• Corazza, Ulrike, Medical University Innsbruck, Innsbruck, Austria

Ulrike Corazza,

• Sallaberger, Sebastian, Medical University Innsbruck, Innsbruck, Austria

Sebastian Sallaberger,

• Leierer, Johannes, Medical University Innsbruck, Innsbruck, Austria

Johannes Leierer,

• Mayer, Gert J., Medical University Innsbruck, Innsbruck, Austria

Gert J. Mayer,

• Schramek, Herbert, Medical University Innsbruck, Innsbruck, Austria

Herbert Schramek,

Background

Large clinical trials recently demonstrated that SGLT2 inhibitors (SGLT2i) slow the progression of kidney function decline in type 2 diabetes independently of their glucose lowering effects. However, the underlying molecular mechanisms of these beneficial renal effects are unknown. As the proximal tubule (PT) is supposed to play a role as initiator and contributor in early pathogenesis of diabetic kidney disease, we conducted a systematic molecular approach to study the effects of SGLT2i on gene expression in human PT cells. Utilizing two SGLT2i, namely empagliflocin and canagliflocin, we investigated their effects on differential gene expression in the presence and absence of TGF-ß1, a well established pro-fibrotic ligand.

Methods

human proximal tubular cell culture (HK-2 and RPTEC/TERT1), microarray hybridization, pathway enrichment analysis, real-time PCR, ELISA

Results

Microarray hybridization analysis identified 94 genes that were both upregulated by TGF-ß1 and downregulated by two SGLT2i in HK-2 and RPTEC/TERT1 cells (n=2). Functional annotation of these genes revealed 152 involved pathways in 7 annotation clusters (EASE score < 0,05). Within the top-ranked clusters (enrichment score > 3), annotations for extracellular matrix organisation (p=6,4x10^-7) and extracellular space (p=2,8x10^-6) showed the highest significance. Differential gene expression of 3 annotated genes of interest within this pathway, namely thrombospondin 1 (THBS1), tenascin C (TNC) and platelet derived growth factor subunit B (PDGFB), was verified on mRNA level in HK-2 and RPTEC/TERT1 cells: While TGF-ß1 significantly induced mRNA expression of THBS1 (5-fold), TNC (8-fold) and PDGFB (4,2-fold), SGLT2i significantly downregulated basal mRNA expression of THBS1 (0,2-fold), TNC (0,5-fold) and PDGFB (0,5-fold). Administration of SGLT2i in the presence of TGF-ß1 resulted in a significant inhibition of TGF-ß1-induced THBS1 and TNC mRNA expression by approximately 50 % (n=4; p<0,05). TGF-ß1-induced PDGFB protein expression was almost completely blocked in the presence of SGLT2i (n=6; p<0,001).

Conclusion

We conclude that SGLT2i block basal and TGF-ß1-induced expression of key mediators of renal fibrosis and kidney disease progression, namely of THBS1, TNC and PDGFB in two independent human PT cell lines.