Extracellular Matrix Injury of Kidney Allografts in Antibody-Mediated Rejection: A Proteomics Study

Sergi Clotet-Freixas; Caitriona M. McEvoy; Ihor Batruch; Chiara Pastrello; Max Kotlyar; Julie Anh Dung Van; Madhurangi Arambewela; Alex Boshart; Sofia Farkona; Yun Niu; Yanhong Li; Olusegun Famure; Andrea Bozovic; Vathany Kulasingam; Peixuen Chen; S. Joseph Kim; Emilie Chan; Sajad Moshkelgosha; Syed Ashiqur Rahman; Jishnu Das; Tereza Martinu; Stephen Juvet; Igor Jurisica; Andrzej Chruscinski; Rohan John; Ana Konvalinka

doi:10.1681/ASN.2020030286

Visual Abstract

Significance Statement

Antibody-mediated rejection (AMR) accounts for more than 50% of kidney allograft loss. It arises from donor-specific antibodies against HLA antigens, which induce maladaptive responses in the glomeruli and tubulointerstitium. An unbiased proteomics analysis of laser-captured/microdissected glomeruli and tubulointerstitium from 30 indication kidney biopsy specimens with early AMR, acute cellular rejection, or acute tubular necrosis, quantified >2000 proteins in each compartment. Basement membrane and extracellular matrix (ECM) proteins were significantly decreased in both AMR compartments. Two ECM-modifying proteins, galectin-1 (LGALS1) and glutathione S-transferase ω-1 (GSTO1), were significantly increased in glomeruli and tubulointerstitium, respectively. Anti-HLA antibodies or AMR-related cytokines upregulated LGALS1 and GSTO1 in primary kidney cells, and may represent therapeutic targets to ameliorate ECM remodeling in AMR.

Abstract

Background Antibody-mediated rejection (AMR) accounts for >50% of kidney allograft loss. Donor-specific antibodies (DSA) against HLA and non-HLA antigens in the glomeruli and the tubulointerstitium cause AMR while inflammatory cytokines such as TNFα trigger graft injury. The mechanisms governing cell-specific injury in AMR remain unclear.

Methods Unbiased proteomic analysis of laser-captured and microdissected glomeruli and tubulointerstitium was performed on 30 for-cause kidney biopsy specimens with early AMR, acute cellular rejection (ACR), or acute tubular necrosis (ATN).

Results A total of 107 of 2026 glomerular and 112 of 2399 tubulointerstitial proteins was significantly differentially expressed in AMR versus ACR; 112 of 2026 glomerular and 181 of 2399 tubulointerstitial proteins were significantly dysregulated in AMR versus ATN (P<0.05). Basement membrane and extracellular matrix (ECM) proteins were significantly decreased in both AMR compartments. Glomerular and tubulointerstitial laminin subunit γ-1 (LAMC1) expression decreased in AMR, as did glomerular nephrin (NPHS1) and receptor-type tyrosine-phosphatase O (PTPRO). The proteomic analysis revealed upregulated galectin-1, which is an immunomodulatory protein linked to the ECM, in AMR glomeruli. Anti-HLA class I antibodies significantly increased cathepsin-V (CTSV) expression and galectin-1 expression and secretion in human glomerular endothelial cells. CTSV had been predicted to cleave ECM proteins in the AMR glomeruli. Glutathione S-transferase ω-1, an ECM-modifying enzyme, was significantly increased in the AMR tubulointerstitium and in TNFα-treated proximal tubular epithelial cells.

Conclusions Basement membranes are often remodeled in chronic AMR. Proteomic analysis performed on laser-captured and microdissected glomeruli and tubulointerstitium identified early ECM remodeling, which may represent a new therapeutic opportunity.

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