title: Pretreatment by low-dose fibrates protects against acute free fatty acid-induced renal tubule toxicity by counteracting PPARα deterioration.
abstract: Development of a preventive strategy against tubular damage associated with proteinuria is of great importance. Recently, free fatty acid (FFA) toxicities accompanying proteinuria were found to be a main cause of tubular damage, which was aggravated by insufficiency of peroxisome proliferator-activated receptor alpha (PPARα), suggesting the benefit of PPARα activation. However, an earlier study using a murine acute tubular injury model, FFA-overload nephropathy, demonstrated that high-dose treatment of PPARα agonist (0.5% clofibrate diet) aggravated the tubular damage as a consequence of excess serum accumulation of clofibrate metabolites due to decreased kidney elimination. To induce the renoprotective effects of PPARα agonists without drug accumulation, we tried a pretreatment study using low-dose clofibrate (0.1% clofibrate diet) using the same murine model. Low-dose clofibrate pretreatment prevented acute tubular injuries without accumulation of its metabolites. The tubular protective effects appeared to be associated with the counteraction of PPARα deterioration, resulting in the decrease of FFAs influx to the kidney, maintenance of fatty acid oxidation, diminution of intracellular accumulation of undigested FFAs, and attenuation of disease developmental factors including oxidative stress, apoptosis, and NFκB activation. These effects are common to other fibrates and dependent on PPARα function. Interestingly, however, clofibrate pretreatment also exerted PPARα-independent tubular toxicities in PPARα-null mice with FFA-overload nephropathy. The favorable properties of fibrates are evident when PPARα-dependent tubular protective effects outweigh their PPARα-independent tubular toxicities. This delicate balance seems to be easily affected by the drug dose. It will be important to establish the appropriate dosage of fibrates for treatment against kidney disease and to develop a novel PPARα activator that has a steady serum concentration regardless of kidney dysfunction.
authors.affiliation: Department of Metabolic Regulation, Institute on Aging and Adaptation, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Takahashi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamijo
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hora
authors.forename: Koji
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Makoto
authors.initials: M
authors.lastname: Higuchi
authors.forename: Takero
authors.initials: T
authors.lastname: Nakajima
authors.forename: Takashi
authors.initials: T
authors.lastname: Ehara
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gonzalez
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Aoyama
mesh_terms: D000818:Animals; D002994:Clofibrate / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D005260:Female; D006651:Histocytochemistry; D000960:Hypolipidemic Agents / Q000494:pharmacology*; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism*; D011507:Proteinuria / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013047:Specific Pathogen-Free Organisms
chemical_list: D005230:Fatty Acids, Nonesterified; D000960:Hypolipidemic Agents; D047493:PPAR alpha; D012333:RNA, Messenger; D002994:Clofibrate