Kidney Week

Abstract: FR-OR42

Proteomics Reveals Extracellular Matrix Injury in the Glomeruli and Tubulointerstitium of Kidney Allografts with Early Antibody-Mediated Rejection

Session Information

• In-Depth Look at Transplantation: Basic and Translational
  October 23, 2020 | Location: Simulive
  Abstract Time: 05:00 PM - 07:00 PM

Category: Transplantation

• 1901 Transplantation: Basic

Authors

• Clotet Freixas, Sergi, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Sergi Clotet Freixas, PhD



Dr. Sergi Clotet-Freixas completed his Bachelor of Biotechnology at the Universitat Autònoma of Barcelona (2010), and a Master’s degree in Biomedical Research at the University of Barcelona (2011). In 2012, he embarked on a PhD in basic science at the Hospital del Mar in Barcelona. The aim of his PhD was to explore the effect of sex on experimental diabetic kidney disease (DKD) and the renin-angiotensin system. Dr. Clotet-Freixas uncovered a critical role of androgens and a sex-specific role of angiotensin-converting enzyme 2 in DKD progression. These observations may shed new light on sex-specific approaches to the treatment of DKD. As a PhD student, Dr. Clotet-Freixas also discovered a novel link between male sex hormones and impaired energy metabolism in the diabetic kidney, which may help to understand the more rapid kidney disease progression associated with male sex. Since the completion of his PhD, Dr. Clotet-Freixas has been working as a post-doctoral fellow in the laboratory of Dr. Ana Konvalinka at the University Health Network in Toronto. He is continuing to study the role of cell sex and sex hormones on the metabolic function of renal tubular cells. Dr. Clotet-Freixas is also expanding his expertise in other kidney-related disease settings. His recent proteomics findings uncovered a compartment-specific remodeling of the extracellular matrix (ECM) in early antibody-mediated rejection (AMR) after kidney transplantation. These novel observations could help explain the development of basement membrane injury that often occurs in AMR at more advanced stages. Dr.Clotet-Freixas is currently exploring the link between key antibodies and cytokines involved in AMR and cell-specific mechanisms of ECM remodeling in kidney cells. Early targeting of ECM remodeling may be the key to prevent the progression of AMR and other kidney diseases in which basement membrane injury plays a central role.

• McEvoy, Caitriona M., Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Caitriona M. McEvoy,

• Batruch, Ihor, Department of Laboratory Medicine and Pathobiology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada

Ihor Batruch,

• Pastrello, Chiara, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada

Chiara Pastrello,

• Kotlyar, Max, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada

Max Kotlyar,

• Arambewela, Madhurangi, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Madhurangi Arambewela,

• Van, Julie Anh Dung, Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada

Julie Anh Dung Van,

• Niu, Yun, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada

Yun Niu,

• Farkona, Sofia, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Sofia Farkona,

• Boshart, Alexander, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Alexander Boshart,

• Bozovic, Andrea, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada

Andrea Bozovic,

• Kulasingam, Vathany, Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada

Vathany Kulasingam,

• Famure, Olusegun, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Olusegun Famure,

• Kim, Joseph, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Joseph Kim,

• Martinu, Tereza, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Tereza Martinu,

• Juvet, Stephen C., Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Stephen C. Juvet,

• Chruscinski, Andrzej, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Andrzej Chruscinski,

• John, Rohan, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Rohan John,

• Konvalinka, Ana, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada

Ana Konvalinka,

Background

Antibody-mediated rejection (AMR) accounts for >50% of kidney allograft losses. AMR is caused by donor-specific antibodies (DSA) against HLA antigens in the glomeruli and the tubulointerstitium, which together with interferon-γ and tumor necrosis factor-α (TNFα), trigger graft injury. The reasons behind cell-specific injury in AMR remain unclear. Identifying compartment-specific proteome alterations may help uncover mechanisms of early antibody-mediated injury.

Methods

We studied 30 for-cause kidney biopsies with early AMR, acute cellular rejection (ACR) or acute tubular necrosis (ATN). We laser-captured microdissected glomeruli and tubulointerstitium and subjected them to unbiased proteome analysis.

Results

We found 107 glomerular and 112 tubulointerstitial proteins significantly differentially expressed in AMR vs ACR (p<0.05). Similarly,112 (glomeruli) and 124 (tubulointerstitium) proteins were altered in AMR vs ATN. Basement membrane and extracellular matrix (ECM) proteins were decreased in both compartments in AMR, compared to ACR and ATN. We verified decreased glomerular and tubulointerstitial LAMC1 expression, and decreased glomerular NPHS1 and PTPRO expression in AMR. Cathepsin-V (CTSV) was predicted to cleave ECM-proteins in the AMR glomeruli. We identified galectin-1, an immunomodulatory protein increased in AMR glomeruli and linked to the ECM. An external dataset (GSE36059) also demonstrated increased galectin-1 expression in AMR. Anti-HLA class-I antibodies induced inflammation and significantly increased CTSV expression, and galectin-1 expression and secretion, in human glomerular endothelial cells. We also studied GSTO1, an ECM-modifying enzyme, increased in the AMR tubulointerstitium. GSTO1 expression was significantly increased in TNFα-treated proximal tubular epithelial cells.

Conclusion

Basement membranes are often remodeled in chronic AMR, and we demonstrated that this remodeling begins early in glomeruli and tubulointerstitium. ECM-remodeling in AMR may represent a new therapeutic target.