Glomerular damage mediated by glomerulus-infiltrating myeloid-derived cells is a key pathogenic event in lupus nephritis (LN), but the process is poorly understood. Confocal microscopy of kidney sections and flow cytometry analysis of glomerular cells from magnetic bead–purified glomeruli have identified glomerulus-infiltrating leukocyte populations in NZM2328 (NZM) lupus-prone mice with spontaneous chronic glomerulonephritis (GN) and anti–glomerular basement membrane-induced nephritis. The occurrence of a major glomerulus-infiltrating CD11b+F4/80−I-A− macrophage population exhibiting the markers programmed death ligand-1 (PD-L1), Mac-2, and macrophage mannose receptor (CD206) and producing Klf4, Il10, Retnla, Tnf, and Il6 mRNA, which are known to be expressed by alternatively activated (M2b) macrophages, correlated with proteinuria status. In NZM mice with spontaneous LN, glomerular macrophage infiltration is predominant. CD11b+F4/80−I-A− intraglomerular macrophages and polymorphonuclear neutrophils (PMN) are important in inducing GN, as anti-CD11b and –ICAM-1 mAb inhibited both proteinuria and macrophage and PMN infiltration. The predominant and high expression of PD-L1 by CD11b+F4/80−I-A− glomerular macrophages in kidneys of mice with GN and the inhibition of proteinuria by anti–PD-L1 mAb supported the pathogenic role of these macrophages but not the PD-L1− PMN in GN development and in inducing podocyte damage. In NZM mice with spontaneous chronic GN and severe proteinuria, few glomerulus-infiltrating PMN were found, leaving macrophages and, to a less extent, dendritic cells as the major infiltrating leukocytes. Taken together, these data support the important pathogenic effect of CD11b+F4/80−I-A− M2b-like glomerulus-infiltrating macrophages in LN and reinforce macrophages as a promising target for GN treatment.
This work was supported in part by National Institutes of Health Grants AI083024 (to S.-s.J.S. and Y.S.H.), AR047988 and AR045222 (to S.M.F.), DK105833 (to R.S. and S.M.F.), DK085080 (to J.Y.), DK094907 (to T.H.L.), DK062324 (to M.D.O.), and DK076095 (to W.K.B.), Alliance for Lupus Research Grants TIL187966 and TIL332615 (to S.M.F.), and by Lupus Research Alliance Grant DIA481517 (to S.M.F.).
An abstract on this work was presented in poster form at Kidney Week 2016, Chicago, IL, November 15–20, 2016 (poster no. FR-PO123).
The online version of this article contains supplemental material.
Abbreviations used in this article:
- Alexa Fluor
- Brilliant Violet
- chronic glomerulonephritis
- dendritic cell
- glomerular basement membrane
- lupus nephritis
- myeloid-derived suppressor cell
- macrophage mannose receptor
- programmed death 1
- programmed death ligand-1
- polymorphonuclear neutrophil
- systemic lupus erythematosus.
- Received September 7, 2016.
- Accepted January 26, 2017.
- Copyright © 2017 by The American Association of Immunologists, Inc.