Saturated fatty acid stimulates production of extracellular vesicles by renal tubular epithelial cells
Lipotoxicity, an accumulation of intracellular lipid metabolites, has been proposed as an important pathogenic mechanism contributing to kidney dysfunction in the context of metabolic disease. Palmitic acid, a predominant lipid derivative, can cause lipoapoptosis and the release of inflammatory extracellular vesicles (EVs) in hepatocytes, but the effect of lipids on EV production in chronic kidney disease remains vaguely explored. This study was aimed to investigate whether palmitic acid would stimulate EV release from renal proximal tubular epithelial cells. Human and rat proximal tubular epithelial cells, HK-2 and NRK-52E, were incubated with 1% bovine serum albumin (BSA), BSA-conjugated palmitic acid (PA), and BSA-conjugated oleic acid (OA) for 24–48 h. The EVs released into conditioned media were isolated by ultracentrifugation and quantified by nanoparticle-tracking analysis (NTA). According to NTA, the size distribution of EVs was 30–150 nm with similar mode sizes in all experimental groups. Moreover, BSA-induced EV release was significantly enhanced in the presence of PA, whereas EV release was not altered by the addition of OA. In NRK-52E cells, PA-enhanced EV release was associated with an induction of cell apoptosis reflected by an increase in cleaved caspase-3 protein by Western blot and Annexin V positive cells analyzed by flow cytometry. Additionally, confocal microscopy confirmed the uptake of lipid-induced EVs by recipient renal proximal tubular cells. Collectively, our results indicate that PA stimulates EV release from cultured proximal tubular epithelial cells. Thus, extended characterization of lipid-induced EVs may constitute new signaling paradigms contributing to chronic kidney disease pathology.
KeywordsExtracellular vesicles Lipotoxicity Renal proximal tubules Palmitic acid
This work was supported by the NIH SC1DK112151, NIH 5T32HL103104-07, NIH/NCRR/RCMI 8G12MD007602 and 8U54MD007588.
Compliance with ethical standards
Conflict of Interest
The authors declare no conflict of interest.
- 1.Saran R, Li Y, Robinson B, Abbott KC, Agodoa LY, Ayanian J, Bragg-Gresham J, Balkrishnan R, Chen JL, Cope E, Eggers PW, Gillen D, Gipson D, Hailpern SM, Hall YN, He K, Herman W, Heung M, Hirth RA, Hutton D, Jacobsen SJ, Kalantar-Zadeh K, Kovesdy CP, Lu Y, Molnar MZ, Morgenstern H, Nallamothu B, Nguyen DV, O’Hare AM, Plattner B, Pisoni R, Port FK, Rao P, Rhee CM, Sakhuja A, Schaubel DE, Selewski DT, Shahinian V, Sim JJ, Song P, Streja E, Kurella TM, Tentori F, White S, Woodside K, Hirth RA (2016) US Renal Data System 2015 Annual Data Report: Epidemiology of Kidney Disease in the United States, Am J Kidney Dis67: Svii, S1–Svii, 305. https://doi.org/10.1053/j.ajkd.2015.12.014
- 14.Cobbs A, Ballou K, Chen X, George J, Zhao X (2018) Saturated fatty acids bound to albumin enhance osteopontin expression and cleavage in renal proximal tubular cells. Int J Physiol Pathophysiol Pharmacol 10:29–38Google Scholar
- 16.Hirsova P, Ibrahim SH, Krishnan A, Verma VK, Bronk SF, Werneburg NW, Charlton MR, Shah VH, Malhi H, Gores GJ (2016) Lipid-induced signaling causes release of inflammatory extracellular vesicles from hepatocytes. Gastroenterology 150:956–967. https://doi.org/10.1053/j.gastro.2015.12.037 CrossRefGoogle Scholar
- 17.Lee YS, Kim SY, Ko E, Lee JH, Yi HS, Yoo YJ, Je J, Suh SJ, Jung YK, Kim JH, Seo YS, Yim HJ, Jeong WI, Yeon JE, Um SH, Byun KS (2017) Exosomes derived from palmitic acid-treated hepatocytes induce fibrotic activation of hepatic stellate cells. Sci Rep 7:3710. https://doi.org/10.1038/s41598-017-03389-2 CrossRefGoogle Scholar
- 18.Lennon R, Pons D, Sabin MA, Wei C, Shield JP, Coward RJ, Tavare JM, Mathieson PW, Saleem MA, Welsh GI (2009) Saturated fatty acids induce insulin resistance in human podocytes: implications for diabetic nephropathy. Nephrol Dial Transplant 24:3288–3296. https://doi.org/10.1093/ndt/gfp302 CrossRefGoogle Scholar
- 19.Sabin MA, Stewart CE, Crowne EC, Turner SJ, Hunt LP, Welsh GI, Grohmann MJ, Holly JM, Shield JP (2007) Fatty acid-induced defects in insulin signalling, in myotubes derived from children, are related to ceramide production from palmitate rather than the accumulation of intramyocellular lipid. J Cell Physiol 211:244–252. https://doi.org/10.1002/jcp.20922 CrossRefGoogle Scholar
- 22.Nakamura K, Sawada K, Kinose Y, Yoshimura A, Toda A, Nakatsuka E, Hashimoto K, Mabuchi S, Morishige KI, Kurachi H, Lengyel E, Kimura T (2017) Exosomes promote ovarian cancer cell invasion through transfer of CD44 to peritoneal mesothelial cells. Mol Cancer Res 15:78–92. https://doi.org/10.1158/1541-7786.MCR-16-0191 CrossRefGoogle Scholar
- 29.Katsoulieris E, Mabley JG, Samai M, Sharpe MA, Green IC, Chatterjee PK (2010) Lipotoxicity in renal proximal tubular cells: relationship between endoplasmic reticulum stress and oxidative stress pathways. Free Radic Biol Med 48:1654–1662. https://doi.org/10.1016/j.freeradbiomed.2010.03.021 CrossRefGoogle Scholar
- 32.Harp D, Driss A, Mehrabi S, Chowdhury I, Xu W, Liu D, Garcia-Barrio M, Taylor RN, Gold B, Jefferson S, Sidell N, Thompson W (2016) Exosomes derived from endometriotic stromal cells have enhanced angiogenic effects in vitro. Cell Tissue Res 365:187–196. https://doi.org/10.1007/s00441-016-2358-1 CrossRefGoogle Scholar
- 36.De S, Kuwahara S, Hosojima M, Ishikawa T, Kaseda R, Sarkar P, Yoshioka Y, Kabasawa H, Iida T, Goto S, Toba K, Higuchi Y, Suzuki Y, Hara M, Kurosawa H, Narita I, Hirayama Y, Ochiya T, Saito A (2017) Exocytosis-mediated urinary full-length megalin excretion is linked with the pathogenesis of diabetic nephropathy. Diabetes 66:1391–1404. https://doi.org/10.2337/db16-1031 CrossRefGoogle Scholar