Kidney Week

Abstract: FR-PO289

IL-32 Is a Lipid Droplet-Associated Mediator of Tubular Injury in Diabetic Kidney Disease

Session Information

• Diabetic Kidney Disease: Basic - 1
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Diabetic Kidney Disease

• 701 Diabetic Kidney Disease: Basic

Authors

• Chung, Hyunjae, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Hyunjae Chung, PhD

• Sinha, Sarthak, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Sarthak Sinha, PhD

• Chappellaz, Mona L., University of Calgary, Calgary, Alberta, Canada

Mona L. Chappellaz

• Lau, Arthur, University of Calgary, Calgary, Alberta, Canada

Arthur Lau, PhD

• Rahmani, Waleed, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Waleed Rahmani, MD, PhD

• Belay, Sisay G., University of Calgary, Calgary, Alberta, Canada

Sisay G. Belay, MSc

• Swamy, Asha K. R., University of Calgary, Calgary, Alberta, Canada

Asha K. R. Swamy

• Chapman, Kevin R., University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Kevin R. Chapman

• Andonegui, Graciela, University of Calgary, Calgary, Alberta, Canada

Graciela Andonegui, PhD

• Benediktsson, Hallgrimur, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Hallgrimur Benediktsson, MD

• Stys, Peter K., University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Peter K. Stys, MD

• Muruve, Daniel A., University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Daniel A. Muruve, MD

• Chun, Justin, University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Justin Chun, MD, MSc, PhD, FASN

Background

Diabetic kidney disease (DKD) is the leading cause of kidney failure worldwide. The mechanisms contributing to DKD progression remains poorly characterized. In biopsies of human DKD, lipid droplets (LD) accumulate primarily in tubules with advanced stages of DKD. The contribution of lipid dysregulation is not well understood for DKD. Here we use human kidney biopsies and DKD patient-derived kidney organoids to investigate how LDs contribute to the pathogenesis of DKD.

Methods

Human kidney biopsies of the DKD as classified by the Renal Pathology Society classification of DKD were stained using Nile Red and analyzed to LD distribution and numbers. To model DKD, induced pluripotent stem cells (iPSC) were reprogrammed from healthy controls and DKD patients and differentiated to kidney organoids. Kidney organoids were treated with diabetic conditions in the absence of the SGLT2 inhibitor canagliflozin and analyzed by single cell RNA sequencing, in vitro assays, digital spatial imaging (CosMx), molecular spatial imaging (GeoMx) and live kidney organoid imaging.

Results

High glucose uptake promoted prominent LD formation in proximal tubular cells (PTC) of human kidney organoids derived from the iPSC of DKD patients. Single cell RNA sequencing of kidney organoids identified IL32, a gene encoding a pro-inflammatory cytokine induced by high glucose and downregulated by the SGLT2 inhibitor canagliflozin. Analysis of human DKD biopsies by Nanostring's digital spatial transcriptomics and molecular spatial imaging confirmed enrichment of IL32 mRNA in injured proximal tubules. In human DKD organoids, IL-32 localized to tubular LD and its upregulation led to mitochondrial reactive oxygen species generation, mitochondrial fragmentation and tubular basement membrane thickening, attenuated by IL32 knockdown. Overexpression of the beta and gamma isoforms of IL-32 in primary human proximal tubular epithelial cells induced mitochondrial fragmentation, ROS, and caspase-3 and GSDME-mediated cell death.

Conclusion

These findings identify IL-32 as a potential mediator linking metabolic dysfunction to chronic inflammation in DKD. IL-32 is a potentially targetable LD-associated cytokine that can be used to delay the progression of DKD.

Funding

• Government Support – Non-U.S.