Interaction of CD80 with Neph1: a potential mechanism of podocyte injury
The induction of CD80 on podocytes has been shown in animal models of podocyte injury and in certain cases of nephrotic syndrome. In a lipopolysaccharide (LPS)-induced mouse model of albuminuria, we have recently shown a signalling axis of LPS-myeloid cell activation-TNFα production-podocyte CD80 induction-albuminuria. Therefore, in this report, we investigated the cellular and molecular consequences of TNFα addition and CD80 expression on cultured podocytes.
A murine podocyte cell line was used for TNFα treatment and for over-expressing CD80. Expression and localization of various podocyte proteins was analysed by reverse transcriptase-polymerase chain reaction, western blotting and immunofluorescence. HEK293 cells were used to biochemically characterize interactions.
Podocytes treated with LPS in vitro did not cause CD80 upregulation but TNFα treatment was associated with an increase in CD80 levels, actin derangement and poor wound healing. Podocytes stably expressing CD80 showed actin derangement and co-localization with Neph1. CD80 and Neph1 interaction was confirmed by pull down assays of CD80 and Neph1 transfected in HEK293 cells.
Addition of TNFα to podocytes causes CD80 upregulation, actin reorganization and podocyte injury. Overexpressed CD80 and Neph1 interact via their extracellular domain. This interaction implies a mechanism of slit diaphragm disruption and possible use of small molecules that disrupt CD80-Neph1 interaction as a potential for treatment of nephrotic syndrome associated with CD80 upregulation.
KeywordsCD80 Podocytes TNFα Neph1 Lipopolysaccharide Minimal change disease
BK, RB, NO, NJ, AS and SS carried out the experiments. SS, SR and VB conceived the notion and provided intellectual content. BK compiled and analyzed the data and helped in manuscript preparation. MZA provided help in data analysis. AB, SB, UCMN and NW helped in data analysis and interpretation. SS, VB, SR and AG interpreted the data and wrote the article.
Compliance with ethical standards
Sources of funding
This work was supported in part by grants from the Department of Biotechnology, Ministry of Science and Technology (DBT) India (Grant numbers BT/PR12849/MED/15/35/2009 and BT/PR5138/BRB/10/1064/2012 to AG, Grant numbers BT/PR-14592/BRB/10/858/2010 and BT/PR/14651/MED/30/566/2010 to SR, Grant number BT/PR14420/Med/29/213/2010 to VB, and Grant number BT/Bio CARe/08/48/2010-2011 to SS); Department of Science and Technology, Ministry of Science and Technology, India (Grant number SR/SO/BB-0035/2013 to AG, grant number SR/SO/HS-0005/2011 to VB) and fellowships from the Council of Scientific and Industrial Research to BK, NO and NJ. National Institute of Immunology and Translational Health Science and Technology Institute are supported by DBT, Government of India.
Conflict of interest
The authors declare no competing or financial interests.
Research involving animals
All mice handling was done at the National Institute of Immunology (NII) and mice were used with the approval of the NII Institutional Animal Ethics Committee (IAEC). The title of the IAEC approved project was “Studies to understand pathogenic mechanisms associated with proteinuria in nephrotic syndrome” with approval number NII-IAEC#349/14.
No human subjects were involved in this study.
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