Green Tea Polyphenols Stimulate Mitochondrial Biogenesis and Improve Renal Function after Chronic Cyclosporin A Treatment in Rats

Niels Olsen Saraiva Câmara,Hasibur Rehman,Rick G Schnellmann,Khujista Haque,Zhi Zhong,Yasodha Krishnasamy,Ronald G Thurman,John J Lemasters

doi:10.1371/journal.pone.0065029

Abstract

Our previous studies showed that an extract from Camellia sinenesis (green tea), which contains several polyphenols, attenuates nephrotoxicity caused by cyclosporine A (CsA). Since polyphenols are stimulators of mitochondrial biogenesis (MB), this study investigated whether stimulation of MB plays a role in green tea polyphenol protection against CsA renal toxicity. Rats were fed a powdered diet containing green tea polyphenolic extract (0.1%) starting 3 days prior to CsA treatment (25 mg/kg, i.g. daily for 3 weeks). CsA alone decreased renal nuclear DNA-encoded oxidative phosphorylation (OXPHOS) protein ATP synthase-β (AS-β) by 42%, mitochondrial DNA (mtDNA)-encoded OXPHOS protein NADH dehydrogenase-3 (ND3) by 87% and their associated mRNAs. Mitochondrial DNA copy number was also decreased by 78% by CsA. Immunohistochemical analysis showed decreased cytochrome c oxidase subunit IV (COX-IV), an OXPHOS protein, in tubular cells. Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α, the master regulator of MB, and mitochondrial transcription factor-A (Tfam), the transcription factor that regulates mtDNA replication and transcription, were 42% and 90% lower, respectively, in the kidneys of CsA-treated than in untreated rats. These results indicate suppression of MB by chronic CsA treatment. Green tea polyphenols alone and following CsA increased AS-β, ND3, COX-IV, mtDNA copy number, PGC-1α mRNA and protein, decreased acetylated PGC-1α, and increased Tfam mRNA and protein. In association with suppressed MB, CsA increased serum creatinine, caused loss of brush border and dilatation of proximal tubules, tubular atrophy, vacuolization, apoptosis, calcification, and increased neutrophil gelatinase-associated lipocalin expression, leukocyte infiltration, and renal fibrosis. Green tea polyphenols markedly attenuated CsA-induced renal injury and improved renal function. Together, these results demonstrate that green tea polyphenols attenuate CsA-induced kidney injury, at least in part, through the stimulation of MB.

Highlights

Cyclosporin A (CsA) is an important immunosuppressive agent
Mitochondrial DNA is responsible for synthesis of crucial mitochondrial oxidative phosphorylation (OXPHOS) proteins, and proper function of mitochondrial respiration requires an adequate copy number of mitochondrial DNA (mtDNA) per cell [49,56]
Polyphenols increased mtDNA copy number by 19% in rats treated with the vehicle and recovered mtDNA copy number to,90% of control levels after chronic CsA treatment (Fig. 1)

Summary

Introduction

Cyclosporin A (CsA) is an important immunosuppressive agent. Immunosuppressive therapy with CsA is always long-term and results in a number of side effects, the most frequent and severe being nephrotoxicity (e.g. renal dysfunction in up to 30% of patients) [4,5,6,7]. The mechanisms by which CsA causes nephrotoxicity are not well understood but are thought in part due to calcineurin inhibition [8]. CsA causes acute reversible nephrotoxicity as well as chronic, irreversible nephrotoxicity [7]. Upregulation of tolllike receptors (TLR) and TNF-a is involved in CsA nephrotoxicity [14]. Chronic CsA causes decreases of glomerular filtration rates, tubulointerstitial injury, apoptosis, tubular microcalcification, arteriolar hyalinosis, fibrosis, and focal glomerular sclerosis [7]. Mechanisms of CsA chronic damage are less clear compared to the acute nephrotoxicity [7]. Cyclosporine A upregulates TGF-b expression [15]

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Results

Conclusion