Lorena Giugno

Provinol Prevents CsA-induced Nephrotoxicity by Reducing Reactive Oxygen Species, iNOS, and NF-kB Expression

Cyclosporine A (CsA) use is associated with several side effects, the most important of which is nephrotoxicity that includes, as we previously showed, tubular injury and interstitial fibrosis. Recently, many researchers have been interested in minimizing these effects by pharmacological interventions. To do this, we tested whether the administration of a red wine polyphenol, Provinol (PV), prevents the development of CsA-induced nephrotoxicity. Rats were treated for 21 days and divided into four groups: control; group treated with PV (40 mg/kg/day by oral administration in tap water); group treated with CsA (15 mg/kg/day by subcutaneous injection); group treated with CsA plus PV. CsA produced a significant increase of systolic blood pressure; it did not affect urinary output, but caused a significant decrease in creatinine clearance. These side effects were associated with an increase in conjugated dienes, which are lipid peroxidation products, inducible NO-synthase (iNOS), and nuclear factor (NF)-kB, which are involved in antioxidant damage. However, PV prevented these negative effects through a protective mechanism that involved reduction of both oxidative stress and increased iNOS and NF-kB expression induced by CsA. These results provide a pharmacological basis for the beneficial effects of plant-derived polyphenols against CsA-induced renal damage associated with CsA.

Mitochondrial and metabolic dysfunction in renal convoluted tubules of obese mice: protective role of melatonin.

Obesity is a common and complex health problem, which impacts crucial organs; it is also considered an independent risk factor for chronic kidney disease. Few studies have analyzed the consequence of obesity in the renal proximal convoluted tubules, which are the major tubules involved in reabsorptive processes. For optimal performance of the kidney, energy is primarily provided by mitochondria. Melatonin, an indoleamine and antioxidant, has been identified in mitochondria, and there is considerable evidence regarding its essential role in the prevention of oxidative mitochondrial damage. In this study we evaluated the mechanism(s) of mitochondrial alterations in an animal model of obesity (ob/ob mice) and describe the beneficial effects of melatonin treatment on mitochondrial morphology and dynamics as influenced by mitofusin-2 and the intrinsic apoptotic cascade. Melatonin dissolved in 1% ethanol was added to the drinking water from postnatal week 5–13; the calculated dose of melatonin intake was 100 mg/kg body weight/day. Compared to control mice, obesity-related morphological alterations were apparent in the proximal tubules which contained round mitochondria with irregular, short cristae and cells with elevated apoptotic index. Melatonin supplementation in obese mice changed mitochondria shape and cristae organization of proximal tubules, enhanced mitofusin-2 expression, which in turn modulated the progression of the mitochondria-driven intrinsic apoptotic pathway. These changes possibly aid in reducing renal failure. The melatonin-mediated changes indicate its potential protective use against renal morphological damage and dysfunction associated with obesity and metabolic disease.

Obesity-related dysfunction of the aorta and prevention by melatonin treatment in ob/ob mice

In this study, we hypothesized that melatonin administration can minimize alterations in aorta morphology in an animal model of obesity (ob/ob mice). The animals were divided into four groups: (i) control lean mice, (ii) control lean mice treated with melatonin, (iii) ob/ob mice and (iv) ob/ob mice treated with melatonin. The synthetic melatonin was dissolved in 1% ethanol and added to the drinking water from postnatal week 5-13 at a final dose of 100 mg/kg body weight/day. Compared with the obese mice, melatonin intake was associated with a significant decrease in body weight and water consumption. Histological analysis showed that the aortic wall of ob/ob mice had a high Tunica media/lumen ratio and that the elastic fibers in the media layer appeared disrupted and degraded. Moreover, the aorta of ob/ob mice displayed a higher degree of collagen accumulation in the Tunica media compared to the normal aorta. The aorta of ob/ob mice treated with melatonin had a lower Tunica media/lumen ratio and collagen accumulation in comparison with untreated ob/ob mice. Our results showed that whereas melatonin had no apparent histological effects on the aorta in lean mice with normal weight, its administration in ob/ob mice can lead to a reduction in body weight and can ameliorate aorta histopathological dysfunction. This experimental study indicates an apparent protective role for melatonin on the aorta in obesity and melatonin could possibly be an effective tool in the management of obesity-related vascular complications.

Acute mercury exposition of virgin, pregnant, and lactating rats: Histopathological kidney and liver evaluations

This work investigated the effects of mercury chloride (HgCl2) acute exposure on virgin, pregnant and lactating rats by determination of renal and hepatic morphological and ultrastructural parameters and the expression of oxidative stress and stress tolerance markers, due to kidney and liver are the organs that more accumulate inorganic mercury. Adult Wistar rats virgin (90 days old), pregnant (18th gestation day) and lactating (7th lactation day) were injected once with HgCl2 (5 mg/kg) or saline (controls). We observed that HgCl2 exposure of virgin rats caused significant inflammatory infiltration and severe morphological variations, like glomeruli atrophy, dilatation of Bowmans capsule, tubular degeneration and hepatocytes alteration. Moreover, virgin rats presented mitochondrial modification, important oxidative stress and increase in stress tolerance proteins at both kidney and liver level, compared with virgin controls. In detail, virgin rats exposed to HgCl2 presented significantly elevated level of inducible nitric oxide synthase, heat shock protein 27 and glucose regulated proteins 75 expressions at both renal tubular and hepatocytes level, respect untreated virgin rats. Interestingly, pregnant and lactating rats exposed to HgCl2 presented weak renal and liver morphological alterations, showing weak inflammatory infiltration and no significant difference in structural mitochondrial transmembrane protein, oxidative stress markers and stress tolerance proteins expressions respect controls (virgin, pregnant and lactating rats). Although, both control and HgCl2‐exposed pregnant and lactating rats showed renal glomeruli greater in diameter respect virgin rats. In conclusion, we believe that virgin rats are more sensitive to HgCl2 toxicity respect pregnant and lactating rats.

Melatonin efficacy in obese leptin-deficient mice heart

Cardiomyocytes are particularly sensitive to oxidative damage due to the link between mitochondria and sarcoplasmic reticulum necessary for calcium flux and contraction. Melatonin, important indoleamine secreted by the pineal gland during darkness, also has important cardioprotective properties. We designed the present study to define morphological and ultrastructural changes in cardiomyocytes and mainly in mitochondria of an animal model of obesity (ob/ob mice), when treated orally or not with melatonin at 100 mg/kg/day for 8 weeks (from 5 up to 13 week of life). We observed that ob/ob mice mitochondria in sub-sarcolemmal and inter-myofibrillar compartments are often devoid of cristae with an abnormally large size, which are called mega-mitochondria. Moreover, in ob/ob mice the hypertrophic cardiomyocytes expressed high level of 4hydroxy-2-nonenal (4HNE), a marker of lipid peroxidation but scarce degree of mitofusin2, indicative of mitochondrial sufferance. Melatonin oral supplementation in ob/ob mice restores mitochondrial cristae, enhances mitofusin2 expression and minimizes 4HNE and p62/SQSTM1, an index of aberrant autophagic flux. At pericardial fat level, adipose tissue depot strictly associated with myocardium infarction, melatonin reduces adipocyte hypertrophy and inversely regulates 4HNE and adiponectin expressions. In summary, melatonin might represent a safe dietary adjuvant to hamper cardiac mitochondria remodeling and the hypoxic status that occur in pre-diabetic obese mice at 13 weeks of life.

Melatonin treatment improves aging-related conditions in the liver of Apo E-KO mice

Aging is a complex, dynamic, and multifaceted process that is currently still poorly understood [1]. Hypercholesterolemia increases and exacerbates stress signals contributing to aging-related disorders in different organs such as liver [2]. Aging may contribute to the loss of cells in vital structures or organs through several mechanisms. Sirtuin1 (SIRT1) is a member of the sirtuin family of protein deacetylases involved in life span extension; however, its involvement in the aging is not yet completely defined. Recently, it was shown that melatonin, a pleiotropic molecule, activates SIRT1 and modulates oxidative stress-induced senescence and pro-survival pathways [3]. We treated 6and 15-week-old apolipoprotein E-deficient mice (ApoE -/-) with melatonin to evaluate its anti-aging effects. Morphological changes and expression of SIRT1, inducible nitric oxide synthase (iNOS) and antioxidant enzymes (SOD, CAT) were evaluated in the liver of these mice. We observed that SIRT1 expression and antioxidants enzyme activities were decreased in the liver of ApoE deficient mice between 6 and 15 weeks. On the other hand, hypercholesterolemia induced an elevated expression of iNOS in the liver of ApoE -/animals. The treatment with melatonin improves the morphological impairment of the liver, reduced the oxidative stress and inhibited liver aging processes most likely via SIRT1 regulation.

Melatonin atheroprotective effects in vivo

Chronic inflammatory fibro-proliferative changes leading to atherosclerotic plaques are considered hallmark of cardiovascular diseases [1]. Atherosclerosis pathogenesis is a complex entity, which has not been fully understood; however, many studies have demonstrated the role of oxidative stress and inflammation in its development. Melatonin effects on inflammation and oxidative stress process have been demonstrated in the last ten-year literature [2]. However, its role(s) and mechanism(s) of action as a therapeutic tool against atherosclerosis remain largely unexplored. Our aims were to assess the role of melatonin in the onset and developing of atherosclerotic plaques through radiologic and morphometrical tools in 20 apolipoprotein-E knockout (ApoE) mice fed with Western diet (42% calories from fat). 10/20 mice were treated with melatonin (10 mg/kg per os). 18F-FDG PET-CT is a widely used tool to assess inflammatory changes, even before macroscopic changes have taken place. Glucose metabolism is known to be higher in areas of inflammation due to an increased expression of GLUT transporters on the cell membranes both in animals and humans. Using this feature PET/CT is able to determinate metabolic cellular changes and therefore it can be used as biomarker of atherosclerosis. All mice were scanned both before starting melatonin treatment and at the end of the study. After the last scan mice were sacrificed and vascular remodeling, oxidative stress and inflammation at aortic arch level were evaluated. CT-corrected PET datasets were used for computation of SUVmax. Atherosclerotic vascular remodeling, oxidative stress and inflammation levels were significantly more conspicuous in the control cohort, compared to the treated mice (p≤0.05). 18F-FDG PET/CT did not show significant difference in SUVmax. In summary, also in vivo, melatonin may have a protective effect in the atherosclerotic pathogenesis. Flamma S.p.A.-Italy (www.flammagroup.com) provided with melatonin. Financial supports: Fondazione Cariplo e Regione Lombardia “New opportunities and ways towards ERC” (Project 2014-2256) and University of California - Radiology and Biomedical Imaging Nuclear Medicine Section.

Effect of mercury in virgin, pregnant and lactating rats

Mercury is a toxic metal widely used in industrial activities. In Brazil, cases of mercury contamination occur mainly in the Amazon region, where mercury is used in mining to amalgamate the gold; people is so exposed to mercury occupationally and through the consumption of contaminated fish and water [1]. Mercury has a non uniform distribution after absorption, being accumulated mainly in the kidneys causing renal injury [2]. Numerous metabolic changes occur physiologically in pregnancy and lactation periods and induce a different response to exogenous substances, respect virgin animals. At this aim, we evaluated the pathogenetic mechanism, at kidney level, involved in the different responses of virgin, pregnant and lactating rats exposed to a single dose of mercury. Interestingly, the mercury-induced nephrotoxicity differs among pregnant or lac- tating respect virgin rats. In particular, virgin rat showed kidney histopathological alterations including interstitial fibrosis and tubular damages and an altered modulation of heat shock proteins, damages that correlates with the overall loss of renal function. The distinctive responses between pregnant and lactating respect virgin rats observed in our study may be associated with some of several physiological changes that occur during pregnancy or lactation periods.

Metabolic syndrome and melatonin: a tool for prevent obesity-associated abnormalities

Obesity is a common and complex health problem, which impacts crucial organs; it is also considered an independent risk factor for chronic kidney disease [1]. Few studies have analyzed the consequence of obesity in the renal proximal convoluted tubules, the major section of the reabsorptive process. To best perform its functions, the kidney requires energy primarily provided by mitochondria. Melatonin, indoleamine and antioxidant, has been identified in mitochondria, and overwhelming evidence has documented its essential role in the prevention of oxidative mitochondrial damage [2]. Herein, we evaluated the mechanism(s) of mitochondrial alterations in an animal model of obesity (ob/ob mice) and describe the beneficial effects of melatonin treatment on mitochondria morphology and dynamics as influenced by mitofusin- 2 and the intrinsic apoptotic cascade. Melatonin was dissolved in 1% ethanol and added to the drinking water from postnatal week 5 to 13; the calculated dose of melatonin intake was 100 mg/kg body weight/day. Compared to control mice, obesity-induced morphological alterations were apparent in the proximal tubules; the tubules contained round mitochondria with irregular, short cristae and the lining cells excited and elevated apoptotic index. Melatonin supplementation in obese mice changed mitochondria shape and cristae organization of proximal tubules, enhanced mitofusin-2 expression, which in turn modulated the progression of the mitochondria- driven intrinsic apoptotic pathway. The results aid in reducing renal failure. The melatonin-mediated changes probably suggest the use of melatonin to protect against renal morphological damage and dysfunction during metabolic disease.

Melatonin limits adaptive ER stress and hepatosteatosis in leptin-deficient mice

Non alcoholic fatty liver disease (NAFLD) impacts on about 30% of the population in industrialized countries, associated to the metabolic syndrome may be reversible or dramatically evolve into cirrhosis or hepatocellular cancer (Wree et al., 2011). Leptin-deficient homozygous mice (ob/ob) represent a well-known animal model to study obesity, associated with overweight, liver steatosis and insulinresistance. Recently ER stress has been reported to contribute to hepatic steatosis and cell damage called lipoapoptosis (Flamment et al., 2010). Melatonin, the main pineal indoleamine, has been demonstrated to be useful to limit adipogenesis in many metabolic clinical conditions (de Luxan-Delgado et al., 2014). Therefore major aims of the present study were: 1.To localize ER stress, energy homeostasis and hypoxia markers in the liver of ob/ob mice receiving or not melatonin in drinking water at 100 mg/ kg/day for 8 weeks; 2.To characterize hepatic steatosis and quantify macrosteatosis in different experimental groups. C57BL6 mice treated or not with melatonin were used as controls. Remarkably in ob/ob mice receiving melatonin, macrosteatosis, periportal GRP78 staining decreased while beta catenin became basolateral into hepatocytes. Furthermore melatonin limited nuclear CHOP staining, a recognized index of major sensitivity to apoptosis, but stimulated p62/SQSTM1 signal, involved in reducing lipogenesis. Moreover by TEM analysis, we visualized in ob/ob mice liver mitochondria that displayed more cristae and strict RER adhesion after melatonin intake. In conclusion, our morphological analysis suggests that melatonin might ameliorate NAFLD by anti-oxidative and ER stress modulatory abilities in obese mice.