Roles of Macrophage Exosomes in Immune Response to Calcium Oxalate Monohydrate Crystals

Abstract

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 nanoscale liquid chromatography–electrospray ionization–electron transfer dissociation tandem mass spectrometry 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 proinflammatory cytokine IL-8 by monocytes that could be restored to its basal level by small-interfering RNA 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.

LncRNA HOXA11‐AS regulates calcium oxalate crystal–induced renal inflammation via miR‐124‐3p/MCP‐1

“…The excessive ROS can then activate the NF‐κB, NLRP3, NACHT and LRR inflammatory pathways, leading to the secretion of many inflammatory factors such as OPN, MCP‐1, CD44, TGF‐β and IL‐1β, among others . Successively, monocytes are chemotactically attracted by chemokines and converge to inflammatory sites where the monocyte can be activated to macrophages by COM and inflammatory cytokines and, thus, secrete more proinflammatory cytokines, followed by the enhancement of vasopermeability, recruitment of additional inflammatory cells, activation of complement and initiation of renal fibrosis . Therefore, the inflammatory response is amplified by this amplificatory loop, thereby aggravating kidney damage, which is conducive to stone formation.…”

“…4,5 Successively, monocytes are chemotactically attracted by chemokines and converge to inflammatory sites where the monocyte can be activated to macrophages by COM and inflammatory cytokines and, thus, secrete more proinflammatory cytokines, followed by the enhancement of vasopermeability, recruitment of additional inflammatory cells, activation of complement and initiation of renal fibrosis. 6,[29][30][31] Therefore, the inflammatory response is amplified by this amplificatory loop, thereby aggravating kidney damage, which is conducive to stone formation. It is well known that macrophages are phagocytic cells that can eliminate COM to some extent.…”

“…As a potent monocyte attractant, MCP‐1 has been reported to account for nearly 70%‐80% of the monocyte chemotactic activity in various types of renal inflammation . Monocytes are chemotactically attracted and converge to inflammatory sites where they are activated by COM and inflammatory factors and then secrete additional proinflammatory cytokines that attract more inflammatory cells, thereby aggravating the kidney damage via an amplification loop . Consequently, MCP‐1 plays a trigger‐point role in the inflammatory cascade of calcium oxalate stone formation.…”

Submicron Crystals of the Parkinson’s Disease Substantia nigra: Calcium Oxalate, Titanium Dioxide and Iron Oxide

“…If misfolded α-synuclein templates the misfolding of more synuclein, it constitutes a PD-propagating prion. [13][14][15] Because phagocytized crystals have been shown to activate the NLRP3 inflammasome [16][17][18][19][20][21][22][23][24][25], because they enhance in dopaminergic neurons α-synuclein expression and aggregation, [26] and they adsorb and orient peptides and as well as proteins, [27][28][29] we probe here by TEM if there are in the human PD substantia nigra crystals. We find ghosts of hydrated calcium oxalate (COD) and protein-coated titanium dioxide (TiO2) crystals.…”

“…It is a long-known cytotoxic component of urinary tract and kidney calculi, [30][31][32] associated also with retinopathy. [33,34] Both COD and TiO2 are phagocytized, [25,[35][36][37][38][39] TiO2 also by microglia. [40] Both activate the NLRP3 inflammasome.…”