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Kidney Week

Abstract: PO0149

Polymorphisms in HAVCR1 Alter KIM-1-Mediated Phagocytosis

Session Information

  • AKI Mechanisms - 1
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Lee, Ji yun, Schulich School of Medicine and Dentistry Department of Microbiology and Immunology, Western University, London, Ontario, Canada
  • Shrum, Bradly, Schulich School of Medicine and Dentistry Department of Microbiology and Immunology, Western University, London, Ontario, Canada
  • Gunaratnam, Lakshman, Western University Department of Medicine, London, Ontario, Canada
Background

During renal ischemia reperfusion injury (IRI), necrotic cells, and apoptotic tubular epithelial cells (TECs) undergoing secondary necrosis, release their immunogenic contents into the extracellular milieu, exacerbating inflammation. Kidney Injury Molecule -1 (KIM-1) is a cell-surface glycoprotein upregulated on TECs during acute kidney injury (AKI). We previously uncovered that KIM-1 protects against renal IRI by enabling TECs to bind and engulf dying neighbouring cells, limiting inflammation and tissue damage. The gene encoding KIM-1 (HAVCR1) is highly polymorphic, but the relevance of human KIM-1 polymorphisms in renal IRI has not been studied. We hypothesized that HAVCR1 variant expressing TECs would have decreased phagocytic activity in vitro.

Methods

Using site-directed mutagenesis, we generated constructs for 3 high-frequency HAVCR1 coding variants in addition to an expression plasmid-encoding wild-type KIM-1 (pcDNA3-KIM-1). We then expressed the pcDNA3 vector, or HAVCR1variants in HEK-293 cells using stable transfection.

Results

We report that all 3 variants had altered cell surface KIM-1 expression compared to the wild-type. Importantly, the phagocytic uptake of apoptotic cells was significantly reduced in HEK-293 cells expressing each of the KIM-1 variants compared to those expressing wild-type KIM-1, indicating that mutations in these coding regions contribute to a functional impairment of KIM-1 activity.

Conclusion

This is the first study suggesting that human polymorphic variants in HAVCR1 may have consequences on the functional role of the KIM-1 protein in the kidney. This work strengthens the plausibility of a biological role for KIM-1 during AKI.

Funding

  • Government Support - Non-U.S.