Circulating Donor-Specific Anti-HLA Antibodies Associate With Immune Activation Independent of Kidney Transplant Histopathological Findings

Abstract

Despite the critical role of cytokines in allograft rejection, the relation of peripheral blood cytokine profiles to clinical kidney transplant rejection has not been fully elucidated. We assessed 28 cytokines through multiplex assay in 293 blood samples from kidney transplant recipients at time of graft dysfunction. Unsupervised hierarchical clustering identified a subset of patients with increased pro-inflammatory cytokine levels. This patient subset was hallmarked by a high prevalence (75%) of donor-specific anti-human leukocyte antigen antibodies (HLA-DSA) and histological rejection (70%) and had worse graft survival compared to the group with low cytokine levels (HLA-DSA in 1.7% and rejection in 33.7%). Thirty percent of patients with high pro-inflammatory cytokine levels and HLA-DSA did not have histological rejection. Exploring the cellular origin of these cytokines, we found a corresponding expression in endothelial cells, monocytes, and natural killer cells in single-cell RNASeq data from kidney transplant biopsies. Finally, we confirmed secretion of these cytokines in HLA-DSA-mediated cross talk between endothelial cells, NK cells, and monocytes. In conclusion, blood pro-inflammatory cytokines are increased in kidney transplant patients with HLA-DSA, even in the absence of histology of rejection. These observations challenge the concept that histology is the gold standard for identification of ongoing allo-immune activation after transplantation.

Transcriptional and spatial profiling of the kidney allograft unravels a central role for FcyRIII+ innate immune cells in rejection

“…Furthermore, our cell-to-cell communications analysis suggested that CXCL10 overexpression by FcγRIII+ monocytes may recruit CXCR3+ T cells and activate ACKR1+ endothelial cells composing the peritubular capillaries. This aligns with our previous finding that the FcγRIII engagement of purified nonclassical monocytes co-cultured with primary endothelial glomerular cells induces CXCL10 secretion 22 . Finally, increased expression of CXCL10 is not only observed in the biopsies at time of kidney allograft rejection but also in urine, serving as suitable biomarker of rejection [66][67][68] , and in peripheral blood 22 .…”

“…This aligns with our previous finding that the FcγRIII engagement of purified nonclassical monocytes co-cultured with primary endothelial glomerular cells induces CXCL10 secretion 22 . Finally, increased expression of CXCL10 is not only observed in the biopsies at time of kidney allograft rejection but also in urine, serving as suitable biomarker of rejection [66][67][68] , and in peripheral blood 22 .…”

“…In response to galectin-9, Tim-3+ NK cells enhance IFN-γ production 52 . This finding echoes our recent report showing that coculturing FcγRIII+ monocytes with FcγRIII+ NK cells and glomerular endothelial cells enhanced IFN-γ secretion in vitro 22 . FcγRIII+ monocytes also overexpress the chemokine CXCL10 together with upregulation of two other IFN-γ-inducible genes GBP5 and WARS upon rejection.…”

Microvascular Inflammation of the Renal Allograft: A Reappraisal of the Underlying Mechanisms

“…Excellent reviews detailing the current knowledge on non-HLA antibodies in transplantation have already been published ( 60 , 63 – 66 ). Here, to investigate the distribution of non-HLA antigen expression in the kidneys, we performed single-cell analysis of previously published human single-cell data ( Figures 2A, B ) from two ABMR biopsies and four healthy references corresponding to transplant surveillance biopsies as previously described ( 67 ). We focused on the main studied antibodies and discuss new large-scale studies in the field of non-HLA antibodies.…”

“…The associated raw counts or matrices were downloaded from the Gene Expression Omnibus (GEO; GSE145927, ) and Kidney Precision Medicine Project ( ). The analysis was performed as previously published ( 67 , 68 ). (A) UMAP dimensionality reduction for the different cell type clusters identified by scRNA-seq analysis.…”