Etude de la dysfonction mitochondriale dans des modèles d'insuffisance rénale

Abstract

The Aristolochic Acids (AA) Nephropathy (AAN) is a disease discovered in the 90’s in Belgium. It is a tubulointerstitial nephritis defined by two phases: an acute phase called Acute Kidney Injury (AKI) step mainly characterized by oxidative stress and Proximal Tubular Epithelial Cells (PTEC) necrosis followed by a Chronic Kidney Disease (CKD) phase characterized by inflammation and fibrosis. Although the mechanisms of AAN are not fully understood, it has been demonstrated that PTECs are the main target of AA. Furthermore, the involvement of mitochondria in nephropathies is particularly studied as the processes of filtration and secretion require a huge amount of energy. Additionally, many studies pointed the involvement of mitochondria in many metabolic pathways including reactive oxygen species production and detoxification, cell death and inflammation. Previous works in the laboratory highlighted dysfunctions and structural disorders in mitochondria during long term AA-I treatment (from 24 to 72 hours) in HK-2 cells model. Therefore, the present work tried to assess the early events that may have occur during AA-I treatment in order to provide additional information about the timeline of mitochondrial metabolism: If mitochondria trigger HK-2 cells cytotoxicity or their dysfunction is a consequence of cytotoxicity. HK-2 cells were treated with AA-I at concentrations varying from 1 to 25 µM of AA and during timings ranging from 2 to 48 hours. Cell viability and cytotoxicity were studied through MTS and CellToxTM Green assays. The oxidative stress and mitochondrial abundance were respectively assessed through relative PGC-1α, HO-1 and NRF2 mRNA expressions and mtDNA and TOM20 protein abundance.