Metallothionein (MTT) is an endogenous antioxidant that can be induced by both zinc (Zn) and ischemia. In kidneys, increased MTT expression exerts a putative protective role in diabetes and hypoxia. Our goal was to further investigate the behavior of MTT under the influence of Zn and hypoxia in vitro and in vivo.
MTT expression was measured in vitro in cell cultures of proximal tubular cells (LCC-PK1) by immune-histochemistry and real-time PCR after incubation with increasing concentrations of Zn under hypoxic and non-hypoxic conditions. In addition, in vivo studies were carried out in 54 patients to study MTT induction through Zn. This is a sub-study of a prospective, randomized, double-blind trial on prevention of contrast-media-induced nephropathy using Placebo, Zn and N-Acetylcysteine. Blood samples were obtained before and after 2 days p.o. treatment with or without Zn (60 mg). ELISA-based MTT level measurements were done to evaluate the effects of Zn administration. For in vivo analysis, we considered the ratio of MTT to baseline MTT (MTT1/MTT0) and the ratio of eGFR (eGFR1/eGFR0), correspondingly.
In vitro quantitative immuno-histochemical analysis (IHC) and real-time PCR showed that at increasing levels of Zn (5, 10, and 15 μg/ml) led to a progressive increase of MTTs: Median (IQR) expression of IHC also increased progressively from 0.10 (0.09–0.12), 0.15 (0.12–0.18), 0.25 (0.25–0.27), 0.59 (0.48–0.70) (p < 0.0001). Median (IQR) expression of PCR: 0.59 (0.51–1.72), 1.62 (1.38–4.70), 3.58 (3.06–10.42) and 10.81 (9.24–31.47) (p < 0.0001). In contrast, hypoxia did not change MTT-levels in vitro (p > 0.05).
In vivo no significant differences (p = 0.96) occurred in MTT-levels after 2 days of Zn administration compared with no Zn intake. Nevertheless, there was a significant correlation between MTT (MTT1/MTT0) and eGFR (eGFR1/eGFR0) in case of Zn administration (rho = −0.49; 95%-CI: −0.78 to −0.03; p = 0.04).
We found that Zn did induce MTTs in vitro, whereas hypoxia had no significant impact. In contrast, no significant increase of MTTs was detected after in vivo administration of Zn. However, there was a significant negative correlation between MTT and eGFR in vivo in case of Zn administration, this could indicate a protective role of MTTs in a setting of reduced kidney function, which is possibly influenced by Zn.
ClinicalTrials.gov Identifier: NCT00399256. Retrospectively registered 11/13/2006.
Shimazu T, Hirschey MD, Newman J, He W, Shirakawa K, Le Moan N, Grueter CA, Lim H, Saunders LR, Stevens RD, Newgard CB, Farese RV, de Cabo R, Ulrich S, Akassoglou K, Verdin E. Suppression of oxidative stress by β-hydroxybutyrate, an endogenous histone deacetylase inhibitor. Science. 2013;339(6116):211–4. CrossRefPubMed
Margoshes M, Vallee BL. A cadmium protein from equine kidney cortex. J Am Chem Soc. 1957;79(17):4813–4. CrossRef
Viarengo A, Burlando B, Ceratto N, Panfoli I. Antioxidant role of metallothioneins: a comparative overview. Cell Mol Biol (Noisy-le-grand). 2000;46(2):407–17.
Podhorska-Okołów M, Dziegiel P, Dolińska-Krajewska B, Dumańska M, Cegielski M, Jethon Z, Rossini K, Carraro U, Zabel M. Expression of metallothionein in renal tubules of rats exposed to acute and endurance exercise. Folia Histochem Cytobiol. 2006;44(3):195–200. PubMed
Takahashi T, Itano Y, Noji S, Matsumoto K, Taga N, Mizukawa S, Toda N, Matsumi M, Morita K, Hirakawa M. Induction of renal metallothionein in rats with ischemic renal failure. Res Commun Mol Pathol Pharmacol. 2001;110(3–4):147–60. PubMed
Sullivan VK, Burnett FR, Cousins RJ. Metallothionein expression is increased in monocytes and erythrocytes of young men during zinc supplementation. J Nutr. 1998;128(4):707–13. PubMed
Sharma R, Sharma M, Datta PK, Savin VJ. Induction of metallothionein-I protects glomeruli from superoxide-mediated increase in albumin permeability. Exp Biol Med (Maywood). 2002;227(1):26–31.
International Zinc Nutrition Consultative G, Brown KH, Rivera JA, Bhutta Z, Gibson RS, King JC, Lonnerdal B, Ruel MT, Sandtrom B, Wasantwisut E, Hotz C. International Zinc Nutrition Consultative Group (IZiNCG) technical document #1. Assessment of the risk of zinc deficiency in populations and options for its control. Food Nutr Bull. 2004;25(1 Suppl 2):S99–203.
Holt RRU-A JY, Keen CL. Zinc. In: Erdman JW, Macdonald IA, Zeisel SH, editors. Present Knowledge in Nutrition. Ames: Wiley-Blackwell; 2012. p. 521–39.
R Development Core Team. R: A language and environment for statistical computing. Vienna: R Foundation for Statistical Computing; 2016.
Sato M, Mehra RK, Bremner I. Measurement of plasma metallothionein-I in the assessment of the zinc status of zinc-deficient and stressed rats. J Nutr. 1984;114(9):1683–9. PubMed
Hidalgo J, Giralt M, Garvey JS, Armario A. Physiological role of glucocorticoids on rat serum and liver metallothionein in basal and stress conditions. Am J Physiol. 1988;254(1 Pt 1):E71–8. PubMed
King JC, Shames DM, Lowe NM, Woodhouse LR, Sutherland B, Abrams SA, Turnlund JR, Jackson MJ. Effect of acute zinc depletion on zinc homeostasis and plasma zinc kinetics in men. Am J Clin Nutr. 2001;74(1):116–24. PubMed
Hambidge KMC CE, Krebs NF. Zinc. In: Mertz W, editor. Trace Elements in Human and Animal Nutrition, vol. 2. Orlando: Academic; 1986. p. 1–137. CrossRef
Iyengar GV. Reevaluation of the trace element content in Reference Man. Radiat Phys Chem. 1998;51(4–6):545–60. CrossRef
- Renal effects of metallothionein induction by zinc in vitro and in vivo
Mark Dominik Alscher
- BioMed Central
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