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Front. Immunol. | doi: 10.3389/fimmu.2018.00316

Roles of macrophage exosomes in immune response to calcium oxalate monohydrate crystals

Nilubon Singhto1 and  Visith Thongboonkerd1*
  • 1Medical Proteomics Unit, Office for R&D, Faculty of Medicine, Siriraj Hospital, Mahidol University, Thailand

In kidney stone disease, macrophages secrete various mediators via classical secretory pathway and cause renal interstitial inflammation. However, whether their extracellular vesicles, particularly exosomes, are involved in kidney stone pathogenesis remained unknown. This study investigated alterations in exosomal proteome of U937-derived macrophages (by phorbol-12-myristate-13-acetate activation) after exposure to calcium oxalate monohydrate (COM) crystals for 16-h using 2-DE-based proteomics approach. Six significantly altered proteins in COM-treated exosomes were successfully identified by nanoLC-ESI-ETD MS/MS as proteins involved mainly in immune processes, including T-cell activation and homeostasis, Fcγ receptor-mediated phagocytosis, interferon-γ (IFN-γ) regulation, and cell migration/movement. The decreased heat shock protein 90-beta (HSP90β) and increased vimentin were confirmed by Western blotting. ELISA showed that the COM-treated macrophages produced greater level of interleukin-1β (IL-1β), one of the markers for inflammasome activation. Functional studies demonstrated that COM-treated exosomes enhanced monocyte and T-cell migration, monocyte activation and macrophage phagocytic activity, but on the other hand, reduced T-cell activation. In addition, COM-treated exosomes enhanced production of pro-inflammatory cytokine IL-8 by monocytes that could be restored to its basal level by small-interfering RNA (siRNA) targeting on vimentin (si-Vimentin). Moreover, si-Vimentin could also abolish effects of COM-treated exosomes on monocyte and T-cell migration as well as macrophage phagocytic activity. These findings provided some implications to the immune response during kidney stone pathogenesis via exosomal pathway of macrophages after exposure to COM crystals.

Keywords: CaOx, com, Inflammasome, Inflammation, Kidney stone, Migration, Phagocytosis

Received: 10 Nov 2017; Accepted: 05 Feb 2018.

Edited by:

Ivan Poon, La Trobe University, Australia

Reviewed by:

Christian Kurts, University of Bonn, Germany
Sho Morioka, University of Virginia, United States  

Copyright: © 2018 Singhto and Thongboonkerd. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Visith Thongboonkerd, Faculty of Medicine, Siriraj Hospital, Mahidol University, Medical Proteomics Unit, Office for R&D, 6th Fl-SiMR Bldg, Siriraj Hosp, 2 Wanglang Rd, Bangkoknoi, Bangkok, 10700, Thailand, vthongbo@yahoo.com