LOXL2 labels inflammation-associated myofibroblasts predicting kidney allograft dysfunction and fibrosis

TL;DR

LOXL2 identifies a new type of myofibroblast linked to kidney transplant dysfunction and fibrosis, offering potential for early detection.

Contribution

LOXL2 is introduced as a novel biomarker for inflammation-associated myofibroblasts in kidney allografts.

Findings

LOXL2 labels SMA-negative, CD68-positive myofibroblasts with high extracellular matrix activity.

LOXL2+ cells are associated with fibrosis, inflammation, and reduced kidney function in transplant biopsies.

High abundance of LOXL2+ cells predicts long-term allograft dysfunction.

Abstract

Progressive allograft fibrosis remains a major obstacle in kidney transplantation. Early identification of patients at high risk could be instrumental to improve outcomes. Here, we investigated Lysyl oxidase like 2 (LOXL2) as a biomarker for graft fibrosis and dysfunction. Using single-cell sequencing and imaging of transplant biopsies, we found that LOXL2 labeled an intertubular myofibroblast-like cell type with a smooth muscle actin (SMA)-negative, CD68-positive phenotype and high extracellular matrix activity. These cells were present in non-fibrotic and fibrotic regions using collagen 3 as a scaffold. Native kidneys also harbored LOXL2+ myofibroblasts, albeit at much lower levels. Following transplant surgery, LOXL2+ cells could rapidly emerge within days, particularly during episodes of rejection, where they associated with leukocyte aggregates. Elevated cell numbers were not irreversible as shown in follow-up biopsies. A retrospective analysis of 118 biopsies revealed a significant association with fibrosis, inflammation, and kidney function but not with other Banff parameters. Non-rejecting allografts displayed high variability in LOXL2+ cells, with high abundance serving as a long-term predictor of reduced allograft function. Our findings point to a new subset of inflammation-associated myofibroblasts that may be useful as a biomarker for early fibrogenesis.

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