Recipient myeloperoxidase-producing cells regulate antibody-mediated acute versus chronic kidney allograft rejection
Satoshi Miyairi, … , Stanley L. Hazen, Robert L. Fairchild
Satoshi Miyairi, … , Stanley L. Hazen, Robert L. Fairchild
Published June 3, 2021
Citation Information: JCI Insight. 2021;6(13):e148747. https://doi.org/10.1172/jci.insight.148747.
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Research Article Transplantation

Recipient myeloperoxidase-producing cells regulate antibody-mediated acute versus chronic kidney allograft rejection

Abstract

Antibody-mediated rejection (ABMR) continues to be a major problem undermining the success of kidney transplantation. Acute ABMR of kidney grafts is characterized by neutrophil and monocyte margination in the tubular capillaries and by graft transcripts indicating NK cell activation, but the myeloid cell mechanisms required for acute ABMR have remained unclear. Dysregulated donor-specific antibody (DSA) responses with high antibody titers are induced in B6.CCR5–/– mice transplanted with complete MHC-mismatched A/J kidneys and are required for rejection of the grafts. This study tested the role of recipient myeloid cell production of myeloperoxidase (MPO) in the cellular and molecular components of acute ABMR. Despite induction of equivalent DSA titers, B6.CCR5–/– recipients rejected A/J kidneys between days 18 and 25, with acute ABMR, whereas B6.CCR5–/–MPO–/– recipients rejected the grafts between days 46 and 54, with histopathological features of chronic graft injury. On day 15, myeloid cells infiltrating grafts from B6.CCR5–/– and B6.CCR5–/–MPO–/– recipients expressed marked phenotypic and functional transcript differences that correlated with the development of acute versus chronic allograft injury, respectively. Near the time of peak DSA titers, activation of NK cells to proliferate and express CD107a was decreased within allografts in B6.CCR5–/–MPO–/– recipients. Despite high titers of DSA, depletion of neutrophils reproduced the inhibition of NK cell activation and decreased macrophage infiltration but increased monocytes producing MPO. Overall, recipient myeloid cells producing MPO regulate graft-infiltrating monocyte/macrophage function and NK cell activation that are required for DSA-mediated acute kidney allograft injury, and their absence switches DSA-mediated acute pathology and graft outcomes to chronic ABMR.

Authors

Satoshi Miyairi, Daisuke Ueda, Takafumi Yagisawa, Daigo Okada, Karen S. Keslar, Kazunari Tanabe, Nina Dvorina, Anna Valujskikh, William M. Baldwin 3rd, Stanley L. Hazen, Robert L. Fairchild

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Figure 4

Differences in transcripts expressed by monocytes and macrophages infiltrating kidney allografts from B6.CCR5–/– or B6.CCR5–/–MPO–/– recipients.

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Differences in transcripts expressed by monocytes and macrophages infilt...
A/J allografts from groups of 2 B6.CCR5–/– or B6.CCR5–/–MPO–/– recipients were harvested on day 14 after transplant and were digested to obtain single-cell suspensions. Aliquots were stained with fluorochrome-labeled monoclonal antibody to identify the Ly6C+F4/80– monocytes and Ly6C–F4/80+ macrophages that were purified by flow sorting. RNA from whole-cell lysates was analyzed by the NanoString nCounter platform using the Mouse Pan Cancer Immune Profiling panel, and heatmaps were generated from the top differentially expressed genes to compare transcript differences in the (A) Ly6C+F4/80– monocytes and (B) Ly6C–F4/80+ macrophages infiltrating kidney allografts in B6.CCR5–/– or B6.CCR5–/–MPO–/– recipients. KEGG analyses of biological pathways were performed from differentially expressed genes in monocytes and macrophages isolated in the allografts from the 2 recipient groups. (C) Volcano plots indicate differentially expressed (up and down) genes (DEGs) expressed by purified Ly6C+F4/80– monocytes versus Ly6C–F4/80+ macrophages infiltrating A/J allografts on day 14 after transplant from B6.CCR5–/– (48 increased and 5 decreased DEGs) or B6.CCR5–/–MPO–/– (64 increased and 1 decreased DEGs) recipients. In both volcano plots open gray circles represent transcripts that are not changed between the 2 groups; solid black circles indicate DEGs with P < 0.05, 2-tailed t test; solid blue circles indicate DEGs with P < 0.01, 2-tailed t test; solid red circles indicate DEGs with P < 0.001, 2-tailed t test; the most highly significant DEGs are labeled on the plots. (D) DEGs shared by the infiltrating monocytes versus macrophages in the 2 recipient groups were determined and are shown in the heatmap. (E) Heatmap comparing inflammatory genes expressed in monocytes versus macrophages infiltrating kidney allografts in B6.CCR5–/– or B6.CCR5–/–MPO–/– recipients. The expression of IRF4 by each population is noted by the blue arrow.