Cardiometabolic Changes in Sirtuin1-Heterozygous Mice on High-Fat Diet and Melatonin Supplementation

A hypercaloric fatty diet predisposes an individual to metabolic syndrome and cardiovascular complications. Sirtuin1 (SIRT1) belongs to the class III histone deacetylase family and sustains anabolism, mitochondrial biogenesis, and fat distribution. Epididymal white adipose tissue (eWAT) is involved in inflammation, whilst interscapular brown adipose tissue (iBAT) drives metabolism in obese rodents. Melatonin, a pineal indoleamine, acting as a SIRT1 modulator, may alleviate cardiometabolic damage. In the present study, we morphologically characterized the heart, eWAT, and iBAT in male heterozygous SIRT1+/- mice (HET mice) on a high-fat diet (60%E lard) versus a standard rodent diet (8.5% E fat) and drinking melatonin (10 mg/kg) for 16 weeks. Wild-type (WT) male C57Bl6/J mice were similarly fed for comparison. Cardiomyocyte fibrosis and endoplasmic reticulum (ER) stress response worsened in HET mice on a high-fat diet vs. other groups. Lipid peroxidation, ER, and mitochondrial stress were assessed by 4 hydroxy-2-nonenal (4HNE), glucose-regulated protein78 (GRP78), CCAA/enhancer-binding protein homologous protein (CHOP), heat shock protein 60 (HSP60), and mitofusin2 immunostainings. Ultrastructural analysis indicated the prevalence of atypical inter-myofibrillar mitochondria with short, misaligned cristae in HET mice on a lard diet despite melatonin supplementation. Abnormal eWAT adipocytes, crown-like inflammatory structures, tumor necrosis factor alpha (TNFα), and iBAT whitening characterized HET mice on a hypercaloric fatty diet and were maintained after melatonin supply. All these data suggest that melatonin's mechanism of action is strictly linked to full SIRT1 expression, which is required for the exhibition of effective antioxidant and anti-inflammatory properties.

Polyamines and Physical Activity in Musculoskeletal Diseases: A Potential Therapeutic Challenge

Autophagy dysregulation is commonplace in the pathogenesis of several invalidating diseases, such as musculoskeletal diseases. Polyamines, as spermidine and spermine, are small aliphatic cations essential for cell growth and differentiation, with multiple antioxidant, anti-inflammatory, and anti-apoptotic effects. Remarkably, they are emerging as natural autophagy regulators with strong anti-aging effects. Polyamine levels were significantly altered in the skeletal muscles of aged animals. Therefore, supplementation of spermine and spermidine may be important to prevent or treat muscle atrophy. Recent in vitro and in vivo experimental studies indicate that spermidine reverses dysfunctional autophagy and stimulates mitophagy in muscles and heart, preventing senescence. Physical exercise, as polyamines, regulates skeletal muscle mass inducing proper autophagy and mitophagy. This narrative review focuses on the latest evidence regarding the efficacy of polyamines and exercise as autophagy inducers, alone or coupled, in alleviating sarcopenia and aging-dependent musculoskeletal diseases. A comprehensive description of overall autophagic steps in muscle, polyamine metabolic pathways, and effects of the role of autophagy inducers played by both polyamines and exercise has been presented. Although literature shows few data in regard to this controversial topic, interesting effects on muscle atrophy in murine models have emerged when the two "autophagy-inducers" were combined. We hope these findings, with caution, can encourage researchers to continue investigating in this direction. In particular, if these novel insights could be confirmed in further in vivo and clinical studies, and the two synergic treatments could be optimized in terms of dose and duration, then polyamine supplementation and physical exercise might have a clinical potential in sarcopenia, and more importantly, implications for a healthy lifestyle in the elderly population.

Mitophagy in Human Diseases

Mitophagy is a selective autophagic process, essential for cellular homeostasis, that eliminates dysfunctional mitochondria. Activated by inner membrane depolarization, it plays an important role during development and is fundamental in highly differentiated post-mitotic cells that are highly dependent on aerobic metabolism, such as neurons, muscle cells, and hepatocytes. Both defective and excessive mitophagy have been proposed to contribute to age-related neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, metabolic diseases, vascular complications of diabetes, myocardial injury, muscle dystrophy, and liver disease, among others. Pharmacological or dietary interventions that restore mitophagy homeostasis and facilitate the elimination of irreversibly damaged mitochondria, thus, could serve as potential therapies in several chronic diseases. However, despite extraordinary advances in this field, mainly derived from in vitro and preclinical animal models, human applications based on the regulation of mitochondrial quality in patients have not yet been approved. In this review, we summarize the key selective mitochondrial autophagy pathways and their role in prevalent chronic human diseases and highlight the potential use of specific interventions.

Natural Compounds and Autophagy: Allies Against Neurodegeneration

Prolonging the healthy life span and limiting neurological illness are imperative goals in gerontology. Age-related neurodegeneration is progressive and leads to severe diseases affecting motility, memory, cognitive function, and social life. To date, no effective treatments are available for neurodegeneration and irreversible neuronal loss. Bioactive phytochemicals could represent a natural alternative to ensure active aging and slow onset of neurodegenerative diseases in elderly patients. Autophagy or macroautophagy is an evolutionarily conserved clearing process that is needed to remove aggregate-prone proteins and organelles in neurons and glia. It also is crucial in synaptic plasticity. Aberrant autophagy has a key role in aging and neurodegeneration. Recent evidence indicates that polyphenols like resveratrol and curcumin, flavonoids, like quercetin, polyamine, like spermidine and sugars, like trehalose, limit brain damage in vitro and in vivo. Their common mechanism of action leads to restoration of efficient autophagy by dismantling misfolded proteins and dysfunctional mitochondria. This review focuses on the role of dietary phytochemicals as modulators of autophagy to fight Alzheimer's and Parkinson's diseases, fronto-temporal dementia, amyotrophic lateral sclerosis, and psychiatric disorders. Currently, most studies have involved in vitro or preclinical animal models, and the therapeutic use of phytochemicals in patients remains limited.

Sirtuin1 Role in the Melatonin Protective Effects Against Obesity-Related Heart Injury

Obesity is a worldwide epidemic disease that induces important structural and functional changes to the heart and predisposes a patient to devastating cardiac complications. Sirtuin1 (SIRT1) has been found to have roles in regulating cardiac function, but whether it can help in cardioprotection is not clear. The aim of the present study was to determine whether melatonin, by modulating SIRT1 and in turn mitochondria signaling, may alleviate obesity-induced cardiac injuries. We investigated 10 lean control mice and 10 leptin-deficient obese mice (ob/ob) orally supplemented with melatonin for 8 weeks, as well as equal numbers of age-matched lean and ob/ob mice that did not receive melatonin. Hearts were evaluated using multiple parameters, including biometric values, morphology, SIRT1 activity and expression of markers of mitochondria biogenesis, oxidative stress, and inflammation. We observed that ob/ob mice experienced significant heart hypertrophy, infiltration by inflammatory cells, reduced SIRT1 activity, altered mitochondrial signaling and oxidative balance, and overexpression of inflammatory markers. Notably, melatonin supplementation in ob/ob mice reverted these obesogenic heart alterations. Melatonin prevented heart remodeling caused by obesity through SIRT1 activation, which, together with mitochondrial pathways, reduced oxidative stress and inflammation.

Impact of Melatonin on Skeletal Muscle and Exercise

Skeletal muscle disorders are dramatically increasing with human aging with enormous sanitary costs and impact on the quality of life. Preventive and therapeutic tools to limit onset and progression of muscle frailty include nutrition and physical training. Melatonin, the indole produced at nighttime in pineal and extra-pineal sites in mammalians, has recognized anti-aging, anti-inflammatory, and anti-oxidant properties. Mitochondria are the favorite target of melatonin, which maintains them efficiently, scavenging free radicals and reducing oxidative damage. Here, we discuss the most recent evidence of dietary melatonin efficacy in age-related skeletal muscle disorders in cellular, preclinical, and clinical studies. Furthermore, we analyze the emerging impact of melatonin on physical activity. Finally, we consider the newest evidence of the gut-muscle axis and the influence of exercise and probably melatonin on the microbiota. In our opinion, this review reinforces the relevance of melatonin as a safe nutraceutical that limits skeletal muscle frailty and prolongs physical performance.

Melatonin Effects on Non-Alcoholic Fatty Liver Disease Are Related to MicroRNA-34a-5p/Sirt1 Axis and Autophagy

Melatonin, an indole produced by pineal and extrapineal tissues, but also taken with a vegetarian diet, has strong anti-oxidant, anti-inflammatory and anti-obesogenic potentials. Non-alcoholic fatty liver disease (NAFLD) is the hepatic side of the metabolic syndrome. NAFLD is a still reversible phase but may evolve into steatohepatitis (NASH), cirrhosis and carcinoma. Currently, an effective therapy for blocking NAFLD staging is lacking. Silent information regulator 1 (SIRT1), a NAD+ dependent histone deacetylase, modulates the energetic metabolism in the liver. Micro-RNA-34a-5p, a direct inhibitor of SIRT1, is an emerging indicator of NAFLD grading. Thus, here we analyzed the effects of oral melatonin against NAFLD and underlying molecular mechanisms, focusing on steatosis, ER stress, mitochondrial shape and autophagy. Male C57BL/6J (WT) and SIRT1 heterozygous (HET) mice were placed either on a high-fat diet (58.4% energy from lard) (HFD) or on a standard maintenance diet (8.4% energy from lipids) for 16 weeks, drinking melatonin (10 mg/kg) or not. Indirect calorimetry, glucose tolerance, steatosis, inflammation, ER stress, mitochondrial changes, autophagy and microRNA-34a-5p expression were estimated. Melatonin improved hepatic metabolism and steatosis, influenced ER stress and mitochondrial shape, and promoted autophagy in WT HFD mice. Conversely, melatonin was ineffective in HET HFD mice, maintaining NASH changes. Indeed, autophagy was inconsistent in HET HFD or starved mice, as indicated by LC3II/LC3I ratio, p62/SQSTM1 and autophagosomes estimation. The beneficial role of melatonin in dietary induced NAFLD/NASH in mice was related to reduced expression of microRNA-34a-5p and sterol regulatory element-binding protein (SREBP1) but only in the presence of full SIRT1 availability.

Perspective: Mitochondria-ER Contacts in Metabolic Cellular Stress Assessed by Microscopy

The interplay of mitochondria with the endoplasmic reticulum and their connections, called mitochondria-ER contacts (MERCs) or mitochondria-associated ER membranes (MAMs), are crucial hubs in cellular stress. These sites are essential for the passage of calcium ions, reactive oxygen species delivery, the sorting of lipids in whole-body metabolism. In this perspective article, we focus on microscopic evidences of the pivotal role of MERCs/MAMs and their changes in metabolic diseases, like obesity, diabetes, and neurodegeneration.

Abstract 293: Oxidative Stress in Obese Mice and Potential Melatonin Cardioprotective Effects

Adult obesity is a worldwide pandemic condition that leads to the metabolic syndrome and a spectrum of irreversible cardiovascular, neurological, renal and digestive morbidities and cardiovascular diseases represent the leading cause of death in obese people. Cardiomyocytes are particularly sensitive to oxidative damage due to the link between mitochondria and sarcoplasmic reticulum necessary for calcium flux and contraction. Melatonin, versatile and pleiotropic indoleamine with multiple actions, has also important cardioprotective properties. The present study defined mitochondria cardiomyocyte changes and relative oxidative stress pattern in ob/ob mice treated orally or not with melatonin at 100 mg/kg/day for 8 weeks. We observed that ob/ob mice mitochondria in cardiomyocytes sub-sarcolemmal and inter-myofibrillar compartments are often devoid of cristae and have an abnormal large size, so they are defined mega-mitochondria. Moreover, in ob/ob mice, we observed also alteration of peroxisome proliferator-activated receptor gamma coactivator-1α, protein that controls mitochondrial biogenesis, oxidative metabolism and inflammation, together with a deregulated endogenous antioxidant system, showing in particular altered heme oxygenase-1 cardyomiocyte expression. Melatonin oral treatment in ob/ob mice restores heart mitochondria and minimizes oxidative stress and inflammation. These preliminary data indicate a significant protective role of melatonin supplementation against obesity-related heart alterations.

Protective effects of quercetin treatment in a pristane-induced mouse model of lupus nephritis

INTRODUCTION

Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus. As murine models of LN are valuable tools to better understand its pathophysiology and to search for new effective treatments, we investigated the effects of the bioflavonoid quercetin on pristane-induced LN mice through histomorphological analyses.

METHODS

Immunofluorescence and biochemical assays were used to evaluate the expression of markers of inflammation (interleukin-6, IL-6; tumour necrosis factor-α, TNF-α), oxidative stress (catalase, CAT; superoxide dismutase 1, SOD1; thiobarbituric acid reactive substances, TBARS), apoptosis (Bax), and fibrosis (transforming growth factor-β1, TGF-β1). Glomerular and tubular ultrastructure was analysed, and tissue messenger RNA of podocin, podoplanin and α3β1-integrin were quantified using the real-time polymerase chain reaction.

RESULTS

Pristane-induced LN mice showed severe kidney injury, characterized by increased proteinuria, glomerular mesangial expansion and inflammation, high expression of the pro-fibrotic, apoptotic and prooxidant markers and reduction of antioxidants. In the kidney ultrastructure, foot process (FP) effacement, apoptotic mesangial cells and abnormal mitochondria with disrupted cristae were observed, along with suppressed tissue mRNA of podocin, podoplanin and α3β1-integrin. Treatment with quercetin in the pristane-induced LN mice model was nephroprotective, decreasing proteinuria levels and significantly lowering tissue expression of IL-6, TNF-α, TGF-β1, Bax and TBARS. Simultaneously, quercetin significantly increased CAT and SOD1 expressions in these mice. In addition, it was observed improvement of the kidney ultrastructure, and tissue mRNA of podocin, but not podoplanin and α3β1-integrin, was restored to the levels found in the control mice.

CONCLUSION

In conclusion, these findings provide experimental evidence of the renoprotective effects of quercetin in the pristane-induced LN mice model. We suggest that quercetin effectively ameliorates the kidney damage caused by pristane, a bioflavonoid to be further evaluated as a new therapeutic strategy in this disease.

Endoplasmic Reticulum Stress and Apoptosis Triggered by Sub-Chronic Lead Exposure in Mice Spleen: a Histopathological Study

Lead (Pb) is an environmental oncogenic metal that induces immunotoxicity and anaemia. Emerging evidence has linked Pb toxicity with endoplasmic reticulum-driven apoptosis and autophagy. Glucose-regulated protein of 78 kDa (Grp78 or binding immunoglobulin protein (BiP)), a master endoplasmic reticulum chaperone, drives macrophage activation and regulates protein folding and calcium flux in response to heavy metals. The spleen may be involved in Pb poisoning due to its crucial role in erythrocatheresis and immune response, although there are no data to support this theory. Here, we found haematic and histopathological changes in the spleen of mice exposed to medium doses of Pb acetate (200 ppm-1 mM) in drinking water for 45 days. Pb deposition was also detected in organs such as the liver, kidney, brain, bone, blood and faeces, indicating an accumulation of this metal despite relatively short exposure time. Blood Pb content (BBL) reached 21.6 μg/dL; echinocytes and poikilocytes were found in Pb smears of treated group. Inside the spleen, higher Fe(II) and Fe(III) deposits inside macrophages were observed. Grp78 immunostaining, weakly expressed in spleen cells of control mice, after Pb exposure was specifically restricted to macrophages and megakaryocytes of the marginal zone of red pulp. Furthermore, Pb exposure induced superoxide dismutase 1 (SOD1) expression, cleaved caspase-3 and p62/SQSTM1, consistent with oxidative stress, apoptosis and dysregulated autophagy in spleen compartments. We suggest that even at a middle dose, oral Pb intake induces oxidant iron deposition in the spleen and that this may trigger sustained Grp78 redistribution to cells, thus leading to oxidative and autophagy dysfunction as early local reactions to this dangerous metal.

Oral Supplementation of Melatonin Protects against Fibromyalgia-Related Skeletal Muscle Alterations in Reserpine-Induced Myalgia Rats

Fibromyalgia is a chronic syndrome characterized by widespread musculoskeletal pain and an extensive array of other symptoms including disordered sleep, fatigue, depression and anxiety. Important factors involved in the pathogenic process of fibromyalgia are inflammation and oxidative stress, suggesting that ant-inflammatory and/or antioxidant supplementation might be effective in the management and modulation of this syndrome. Recent evidence suggests that melatonin may be suitable for this purpose due to its well known ant-inflammatory, antioxidant and analgesic effects. Thus, in the current study, the effects of the oral supplementation of melatonin against fibromyalgia-related skeletal muscle alterations were evaluated. In detail, 90 Sprague Dawley rats were randomly treated with reserpine, to reproduce the pathogenic process of fibromyalgia and thereafter they received melatonin. The animals treated with reserpine showed moderate alterations at hind limb skeletal muscles level and had difficulty in moving, together with significant morphological and ultrastructural alterations and expression of inflammatory and oxidative stress markers in the gastrocnemius muscle. Interestingly, melatonin, dose and/or time dependently, reduced the difficulties in spontaneous motor activity and the musculoskeletal morphostructural, inflammatory, and oxidative stress alterations. This study suggests that melatonin in vivo may be an effective tool in the management of fibromyalgia-related musculoskeletal morphofunctional damage.

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 (18^th gestation day) and lactating (7^th 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 Bowman's 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. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1500-1512, 2017.

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.

Dietary supplementation with essential amino acids boosts the beneficial effects of rosuvastatin on mouse kidney

The effects of high-potency statins on renal function are controversial. To address the impact of statins on renal morpho-functional aspects, normotensive young mice were treated with rosuvastatin (Rvs). Moreover, because statins may impair mitochondrial function, mice received either dietary supplementation with an amino acid mixture enriched in essential amino acids (EAAm), which we previously demonstrated to increase mitochondrial biogenesis in muscle or an unsupplemented control diet for 1 month. Mitochondrial biogenesis and function, apoptosis, and insulin signaling pathway events were studied, primarily in cortical proximal tubules. By electron microscopy analysis, mitochondria were more abundant and more heterogeneous in size, with dense granules in the inner matrix, in Rvs- and Rvs plus EAAm-treated animals. Rvs administration increased protein kinase B and endothelial nitric oxide synthase phosphorylation, but the mammalian target of rapamycin signaling pathway was not affected. Rvs increased the expression of sirtuin 1, peroxisome proliferator-activated receptor γ coactivator-1α, cytochrome oxidase type IV, cytochrome c, and mitochondrial biogenesis markers. Levels of glucose-regulated protein 75 (Grp75), B-cell lymphoma 2, and cyclin-dependent kinase inhibitor 1 were increased in cortical proximal tubules, and expression of the endoplasmic reticulum-mitochondrial chaperone Grp78 was decreased. EAAm supplementation maintained or enhanced these changes. Rvs promotes mitochondrial biogenesis, with a probable anti-apoptotic effect. EAAm boosts these processes and may contribute to the efficient control of cellular energetics and survival in the mouse kidney. This suggests that appropriate nutritional interventions may enhance the beneficial actions of Rvs, and could potentially prevent chronic renal side effects.

Endothelial and vascular smooth muscle cell dysfunction mediated by cyclophylin A and the atheroprotective effects of melatonin

AIMS

This study evaluated the role of cyclophilin A (CyPA) in early phase of atherosclerosis and also examined the atheroprotective effects of melatonin due to its antioxidant properties.

MAIN METHODS

APOE null mice at 6 and 15weeks of age were treated with melatonin at a dose of 0.1mg/kg/day or 10mg/kg/day. We evaluated both histopathological alterations in endothelial and vascular smooth muscle cells by CyPA and rolling mononuclear cell expression during the early phase of atherosclerosis development.

KEY FINDINGS

Our study showed that CyPA expression increases and may modulate inflammatory cell adhesion and interleukin-6 expression inducing vascular smooth muscle cell migration and inflammatory cell extravasation in a time-dependent manner. Moreover, we observed an indirect atheroprotective effect of melatonin on vascular injury; it inhibited CyPA mediated inflammatory cell extravasation and oxidative stress.

SIGNIFICANCE

The melatonin treatment may represent a new atheroprotective approach that contributes to reducing the early phase of atherosclerosis involving the rolling of monocytes, their passage to subendothelial space and inhibition of CyPA expression.

Morphological and biochemical studies on aging and autophagy

To maintain health in the elderly is a crucial objective for modern medicine that involves both basic and clinical researches. Autophagy is a fundamental auto-cannibalizing process that preserves cellular homeostasis and, if altered, either by excess or defect, greatly changes cell fate and can result in incapacitating human diseases. Efficient autophagy may prolong lifespan, but unfortunately this process becomes less efficient with age. The present review is focused on the close relationship between autophagy and age-related disorders in different tissues/organs and in transgenic animal models. In particular, it comments on the up to date literature on mechanisms responsible for age-related impairment of autophagy. Moreover, before discussing about these mechanisms, it is necessary to describe the metabolic autophagic regulation of autophagy and the proteins involved in this process. At the end, these data would summarize the autophagic link with aging process, as important tools in the future biogerontology scenario.

ER signaling regulation drives the switch between autophagy and apoptosis in NRK-52E cells exposed to cisplatin

Cisplatin (cisPt) use in chemotherapy is limited by the occurrence of a severe nephrotoxicity. Both autophagy and apoptosis seem to contribute in kidney response to cisPt, however their cross-talk is still controversial, since the role played by autophagy (cytoprotective or harmful) and the cellular site driving their switch, are still unclear. Here, we used a multidisciplinary approach to study the correlation between autophagy and apoptosis in renal NRK-52E cells exposed to cisPt. We showed two "sensitivity-thresholds" to cisPt, stating whether apoptosis or autophagy would develop: 10 μM dose of cisPt activated autophagy that preserved cell homeostasis; however 3-methyladenine co-administration affected cell viability and induced apoptosis. In contrast, 50 μM cisPt determined cell death by apoptosis, whereas the pre-conditioning with taurine contributed to cell rescue, delaying apoptosis and maintaining autophagy. Hence, autophagy protects NRK-52E cells from cisPt injury. By studying the expression of ER specific hallmarks, such as GRP78, GRP94 and GADD153/CHOP, we found a possible pivotal role of ER signaling modulation in the crosstalk between autophagy and apoptosis induced by cisPt. To the best of our knowledge, this is the first demonstration that taurine enhances autophagic protection against apoptosis by reducing ER stress, thus making it possible to develop new strategies to reduce severe cisPt-induced side-effects such as nephrotoxicity.

Essential Amino Acid Supplementation Decreases Liver Damage Induced by Chronic Ethanol Consumption in Rats

The liver sustains the greatest damage from ethanol (EtOH) abuse. EtOH and its metabolites impair hepatocyte metabolism, causing intracellular accumulation of proteins and lipids and increasing radical oxygen species production. These processes are toxic to the mitochondrial respiratory chain and to mitochondrial DNA. We have recently shown that supplementating the diet of rodents with an essential amino acid-enriched mixture (EAAem) significantly increases mitochondrial mass and number in cardiac and skeletal muscles and improves mitochondrial function in aged animals. Thus, in this study we sought to test whether EAAem supplementation could reduce EtOH-induced liver damage. Groups of adult male Wistar rats were fed a standard diet and water ad libitum (the control group), drinking water with 20% EtOH (the EtOH group), or drinking water with 20% EtOH and EAAem supplementation (1.5 g/kg/day) (the EtOH+EAAem group) for 2 months. The blood EtOH concentration was measured, and markers for fat (Oil-Red-O), mitochondria (Grp75, Cyt-c-ox), endoplasmic reticulum (Grp78), and inflammation (Heme Oxigenase 1, iNOS, and peroxisomes) were analyzed in the liver of animals in the various experimental groups. EAAem supplementation in EtOH-drinking rats ameliorated EtOH-induced changes in liver structure by limiting steatosis, recruiting more mitochondria and peroxisomes mainly to perivenous hepatocytes, stimulating or restoring antioxidant markers, limiting the expression of inflammatory processes, and reducing ER stress. Taken together, these results suggest that EAAem supplementation may represent a promising strategy to prevent and treat EtOH-induced liver damage.

Supplementation with essential amino acids in middle age maintains the health of rat kidney

Chronic kidney diseases are a social and economic problem, and diet has long been recognized as a fundamental modulator of kidney health in human and experimental models. Age-dependent alterations in mitochondrial function play a crucial role in the development of diseases of aging, and mitochondrial disorders have been observed in experimental models of kidney failure. Recently, the beneficial dietary effect of a specific mixture of essential amino acids (EAA) has been studied in elderly subjects, but no data were collected from the kidney. The aim of this study was to assess whether daily supplementation of the diet with EAA at the beginning of senescence could preserve renal health. We used middle-aged (18-month-old) male Wistar rats fed a standard diet and water ad libitum (M-aged group) or a diet with added EAA (1.5 g/kg per day) dissolved in drinking water for 3 months (M-aged+EAA group). Young (2-month-old) rats fed a standard diet for 3 months were used as controls. Mitochondrial morphology and markers for collagen, cyt-c-oxidase, HSP60, GRP75, eNOS, iNOS, Bax, Bcl2 and VEGF were analyzed in glomeruli and tubules. EAA supplementation limited fibrosis and increased the capillary tuft area in the glomeruli of M-aged rats. VEGF and eNOS were enhanced in glomeruli and the peritubular space with the EAA-supplemented diet. Mitochondrial cyt-c oxidase, Bcl2, and chaperones increased in the distal tubules of the EAA group to levels similar to those observed in the young group. Mitochondrial area and density after EAA intake did not differ from young groups. The results suggest that prolonged EAA intake could represent a strategy for maintaining the healthy status of the kidney in M-aged animals.

Stress proteins in experimental nephrotoxicity: a ten year experience

Heat shock proteins and glucose-regulated proteins represent an extraordinary mechanism of defense induced in the kidney by chemicals or drugs and essential to survive. Here we resume our experience on the presence and regulation of stress proteins into acute and chronic nephrotoxic models in rodents and in vitro. In acute renal damage, induced in rats by a single injection of inorganic mercury, stress proteins enhanced in a dose-dependent manner to recover cytoskeleton and mitochondria and maintain nuclear activity. When we pre-treated mercury injected-rats with antioxidant melatonin or with bimoclomol, a stress proteins-coinducer, stress proteins expression was modulated together with tubular recovery. Similar data were obtained in ischemia-reperfusion in rats treated with stannous chloride, that provided cytoprotection stimulating heme oxygenase induction. During nephrotoxicity induced by administration of cyclosporine A at therapeutic dosage for 1-2 months, stress protein overexpression well correlated with oxidative and cell death, but decreased if we counteracted renal damage using antioxidants. In aluminium intoxication through drinking water for 3-6 months, we detected a time-dependent stress response in the rat kidney that was organ specific and different from the liver. In vitro studies on rat tubular proximal cells exposed to heavy metals demonstrated that stress protein expression was related to peculiar mechanisms of action of each metal. In conclusion, experimental studies on the renal chaperones can greatly contribute to understand their role, and agents able to modulate the stress response might be considered promising therapeutic tools to reduce nephrotoxicity.

Stress proteins and oxidative damage in a renal derived cell line exposed to inorganic mercury and lead

A close link between stress protein up-regulation and oxidative damage may provide a novel therapeutic tool to counteract nephrotoxicity induced by toxic metals in the human population, mainly in children, of industrialized countries. Here we analysed the time course of the expression of several heat shock proteins, glucose-regulated proteins and metallothioneins in a rat proximal tubular cell line (NRK-52E) exposed to subcytotoxic doses of inorganic mercury and lead. Concomitantly, we used morphological and biochemical methods to evaluate metal-induced cytotoxicity and oxidative damage. In particular, as biochemical indicators of oxidative stress we detected reactive oxygen species (ROS) and nitrogen species (RNS), total glutathione (GSH) and glutathione-S-transferase (GST) activity. Our results clearly demonstrated that mercury increases ROS and RNS levels and the expressions of Hsp25 and inducible Hsp72. These findings are corroborated by evident mitochondrial damage, apoptosis or necrosis. By contrast, lead is unable to up-regulate Hsp72 but enhances Grp78 and activates nuclear Hsp25 translocation. Furthermore, lead causes endoplasmic reticulum (ER) stress, vacuolation and nucleolar segregation. Lastly, both metals stimulate the over-expression of MTs, but with a different time course. In conclusion, in NRK-52E cell line the stress response is an early and metal-induced event that correlates well with the direct oxidative damage induced by mercury. Indeed, different chaperones are involved in the specific nephrotoxic mechanism of these environmental pollutants and work together for cell survival.

Aluminium exposure induces Alzheimer's disease-like histopathological alterations in mouse brain

Aluminium (Al) is a neurotoxic metal and Al exposure may be a factor in the aetiology of various neurodegenerative diseases such as Alzheimer's disease (AD). The major pathohistological findings in the AD brain are the presence of neuritic plaques containing beta-amyloid (Abeta) which may interfere with neuronal communication. Moreover, it has been observed that GRP78, a stress-response protein induced by conditions that adversely affect endoplasmic reticulum (ER) function, is reduced in the brain of AD patients. In this study, we investigated the correlation between the expression of Abeta and GRP78 in the brain cortex of mice chronically treated with aluminium sulphate. Chronic exposure over 12 months to aluminium sulphate in drinking water resulted in deposition of Abeta similar to that seen in congophilic amyloid angiopathy (CAA) in humans and a reduction in neuronal expression of GRP78 similar to what has previously been observed in Alzheimer's disease. So, we hypothesise that chronic Al administration is responsible for oxidative cell damage that interferes with ER functions inducing Abeta accumulation and neurodegenerative damage.

Effects of aluminium sulphate in the mouse liver: similarities to the aging process

Aluminium (Al) is a ubiquitous metal that is potentially toxic to the brain. Its effects on other fundamental organs are not completely understood. This morphological in vivo study sought to compare sublethal hepatotoxic changes and Al deposition in adult mice that orally ingested Al sulphate daily for 10 months, in age matched control mice that drank tap water and in senescent mice (24 months old). Livers were examined for collagen deposition using Sirius red and Masson, for iron accumulation using Perls' stain. Light, electron microscopy and morphometry were used to assess fibrosis and vascular changes. Scanning transmission electron microscopy and EDX microanalysis were used to detect in situ elemental Al. Iron deposition, transferrin receptor expression were significantly altered following Al exposure and in the aged liver but were unaffected in age matched control mice. In Al treated mice as in senescent mice, endothelial thickness was increased and porosity was decreased like perisinusoidal actin. Furthermore, Al stimulated the deposition of collagen and laminin, mainly in acinar zones 1 and 3. Pseudocapillarization and periportal laminin in senescent mice were similar to Al treated adult liver. In conclusion, prolonged Al sulphate intake accelerates features of senescence in the adult mice liver.

Altered immunolocalization of heat-shock proteins in human peri-implant gingiva

It has been suggested that heat-shock proteins (HSPs) might be involved in autoimmune disease mechanisms in humans, considering the high degree of sequence homology between bacterial and human HSPs. Several authors have postulated that HSPs might be involved in periodontal disease processes, but not specifically in peri-implantitis. Consequently, using immunohistochemical techniques, we studied the distribution of HSP25, HSP32, HSP60 and HSP72 in three groups of patients: (1) subjects with natural teeth (healthy periodontal tissue), (2) subjects with normal peri-implant mucosa and (3) subjects with clinically evident peri-implantitis. The immunolabelling for HSP25 and HSP60 was increased in the peri-implantitis group HSP32 immunolabelling slightly decreased in peri-implant and peri-implantitis gingiva. Labelling for HSP72 was undetectable in all three groups. In conclusion, we observed in peri-implantitis a clearly enhanced immunolabelling of two specific HSPs, HSP25 and HSP60, restricted to gingival epithelium and this could indicate a signal of local altered homeostasis.

Long-term treatment with the apolipoprotein A1 mimetic peptide increases antioxidants and vascular repair in type I diabetic rats

Apolipoprotein A1 mimetic peptide (D-4F), synthesized from D-amino acid, enhances the ability of high-density lipoprotein to protect low-density lipoprotein (LDL) against oxidation in atherosclerotic disease. Using a rat model of type I diabetes, we investigated whether chronic use of D-4F would lead to up-regulation of heme oxygenase (HO)-1, endothelial cell marker (CD31(+)), and thrombomodulin (TM) expression and increase the number of endothelial progenitor cells (EPCs). Sprague-Dawley rats were rendered diabetic with streptozotocin (STZ) and either D-4F or vehicle was administered, by i.p. injection, daily for 6 weeks (100 microg/100 g b.wt.). HO activity was measured in liver, kidney, heart, and aorta. After 6 weeks of D-4F treatment, HO activity significantly increased in the heart and aorta by 29 and 31% (p < 0.05 and p < 0.49), respectively. Long-term D-4F treatment also caused a significant increase in TM and CD31(+) expression. D-4F administration increased antioxidant capacity, as reflected by the decrease in oxidized protein and oxidized LDL, and enhanced EPC function and/or repair, as evidenced by the increase in EPC endothelial nitric-oxide synthase (eNOS) and prevention of vascular TM and CD31(+) loss. In conclusion, HO-1 and eNOS are relevant targets for D-4F and may contribute to the D-4F-mediated increase in TM and CD31(+), the antioxidant and anti-inflammatory properties, and confers robust vascular protection in this animal model of type 1 diabetes.

Different experimental protocols for decontamination affect the cleaning of medical devices. A preliminary electron microscopy analysis

The aim of the present study was to examine the efficiency of different decontamination-cleaning protocols on blood-soiled catheters used for interventional cardiology. Electrophysiology and cardiac ablation disposable devices were contaminated with bacteria-spiked human blood and underwent four different pre-sterilization protocols, including a chlorine-releasing agent, a polyphenolic emulsion, and an enzymatic detergent. Treated samples were examined by optical microscopy, scanning electron microscopy and transmission electron microscopy to identify and characterize biological and inorganic residuals. The use of chlorine as a first treatment caused denaturation of serum proteins and adherence of blood components to the surface of the device, thus hindering the cleaning efficiency of subsequent treatments with enzymatic detergents. An enzymatic/chlorine protocol was more efficient, but was considered to be a greater risk to healthcare staff. Polyphenolic-based treatments had the highest level of efficiency in bioburden removal, but interaction and adsorption of this class of chemicals onto biopolymers might lead to serious concerns about toxicity on subsequent reuse. Adequate pre-sterilization cleaning is fundamental for sterilization success and high-resolution electron microscopy can provide significant and detailed information about the efficiency of chemicals used for cleaning a blood-soiled device.

Bimoclomol ameliorates mercuric chloride nephrotoxicity through recruitment of stress proteins

Bimoclomol (BIM), is a stress proteins coinducer, that acts synergistically with a mild stressor to activate cytoprotective stress proteins. BIM has been successfully utilized in animal models for the treatment of various nervous, cardiac and cerebrovascular diseases. Mercuric chloride (HgCl(2)) induces acute renal failure in rats by a single dosage. The present in vivo study was conducted to assess the efficacy of BIM against acute HgCl(2) nephrotoxicity. At different times after BIM and/or HgCl(2) exposure we evaluated renal morphology and the localization/abundance of three stress proteins (HSP72, GRP75, HSP60) by electron microscopy, immunohistochemistry and Western blot analysis. BIM delivery to rats 6h before mercury, ameliorated damage to renal ultrastructure, with recovery of tubular and mitochondrial membranes 24h after mercury treatment. In rats pretreated with BIM prior to HgCl(2) exposure, HSP72 was significantly overexpressed in proximal tubules in a time-dependent manner. In contrast, the amounts of GRP75 and HSP60 after BIM pretreatment were comparable to the group treated with mercury alone, but these stress proteins had translocated to the nuclei at 14 and 24h, respectively. These novel findings suggest that BIM mitigates HgCl(2) nephrotoxicity in rats through the early recruitment of stress proteins in midcortical proximal tubules that are the main renal mercury-targets.

Tubular stress proteins and nitric oxide synthase expression in rat kidney exposed to mercuric chloride and melatonin

Stress proteins such as HSP70 members (HSP72 and GRP75) and metallothionein (MT) protect the kidney against oxidative damage and harmful metals, whereas inducible nitric oxide synthase (iNOS) regulates tubular functions. A single dose of mercuric chloride (HgCl(2)) can cause acute renal failure in rats, its main target being the proximal tubule. Oxidative damage has been proposed as one of its pathogenic mechanisms. In this study we tested whether melatonin (MEL), a powerful antioxidant compound, is effective against HgCl(2) nephrotoxicity. Rats were treated with saline, HgCl(2) (3.5 mg/kg), MEL (5 mg/kg), and MEL + HgCl(2) and examined after 24 hr for HSP72, GRP75, MT, and iNOS by immunohistochemistry and immunoblotting. Tubular effects of the treatment were then characterized by ultrastructure. In the HgCl(2) group, all markers were overexpressed in convoluted proximal tubules and sometimes in distal tubules. In the MEL + HgCl(2) group, GRP75 and iNOS decreased in convoluted and straight proximal tubules, whereas HSP72 and MT persisted more than the saline and MEL-only groups. Tubular damage and mitochondrial morphometry were improved by MEL pretreatment. In conclusion, the beneficial effect of MEL against HgCl(2) nephrotoxicity was outlined morphologically and by the reduction of the tubular expression of stress proteins and iNOS. These markers could represent sensitive recovery index against mercury damage.

Stress proteins expression in rat kidney and liver chronically exposed to aluminium sulphate

Aluminium (Al) is the third most widespread metal in the environment. It is toxic for the brain, bone and haematological system but unfortunately very little data exist for other organs. Stress proteins are induced or enhanced against metal toxicity with an essential role in the recovery of organules and other cellular proteins. This immunohistochemical study was performed to analyze the distribution of three stress proteins (HSP25, HSP72, GRP75) in rat kidney and liver orally exposed to Al sulphate daily for 3 and 6 months. Al-induced alterations were further studied by histopathology (H-E, PAS, Perl's, Masson) and ultrastructural morphometry. In the kidney: HSP25 was enhanced in proximal tubules after 6 months Al-exposure when abnormal brush borders were observed; HSP72 was induced in proximal tubules only after long Al-treatment; GRP75 was raised in midcortical area sometimes within nuclei. Furthermore, lysosomal and lipofuscins densities increased in the juxtamedullary tubules after 3 months Al exposure with respect to controls. In the liver: Perl's-positive deposits and fibrosis became evident after Al treatment. HSP25 was very weak; HSP72 focal in pericentral hepatocytes at 3 months and induced also in Kupffer cells at 6 months; GRP75 diffuse in periportal hepatocytes and non parenchymal cells at 6 months. Prolonged Al exposure stimulated stress proteins strictly organ-dependently in the rat. Their distribution in kidney and liver seems related to cumulative sublethal effects induced by metal and could be a sensitive index of Al susceptibility of these organs.

Exposure to aluminium changes the NADPH-diaphorase/ NPY pattern in the rat cerebral cortex

Aluminium (Al) impairs the glutamate-nitric oxide-cGMP pathway and reduces the number of nitroxidergic neurons in the rat somatosensory cortex. To understand better the effect of the time of exposure, we monitored the effect of aluminium administration on nitroxidergic neurons, identified by NADPH-diaphorase (NADPH-d) or by nitric oxide synthase (NOS) staining, after 0.5, 1, 2, 3, 6 and 12 months of aluminium administration. Since neuropeptide Y (NPY) is known to be colocalised with nitric oxide synthase in cortical neurons, the aim of this work was to study the effects of Al administration on the cortical expression of NADPH-d, nNOS, and NPY. NADPH-d or NOS positive neurons were found scattered in the cortex where they constituted about 1% of all neurons. Double staining using NADPH-d and NPY showed that almost all nitroxidergic neurons were co-localised with NPY neurons (NADPH-d/NPY double stained neurons) whereas some neurons were stained only with NPY (NPY single stained neurons) ; these were more numerous than NADPH-d/NPY double stained neurons. Al significantly reduced NADPH-d and nNOS positive neurons in the cerebral cortex time dependently, with the greatest effect appearing after 3 months. Also measured was the integrated optical density (IOD) of nNOS positive neurons showing a significant decrease of NOS immunostaining even in the remaining NOS positive neurons. The double staining experiment exhibited a decrease in NADPH-d/NPY double stained neurons with an apparent increase in NPY single stained neurons; these then decreased after 6-12 months. On the whole, the results confirm that Al impairs nitroxidergic pathways time dependently; moreover, the transient increase in NPY single stained neurons from 1 to 3 months suggests that there is an intraneuronal down-regulation of NOS, without affecting neuronal viability. In addition, the decrease in the NPY system found at 6 and 12 months may indicate that Al affected nitroxidergic and NPY systems at different times.

Protective role of melatonin in cyclosporine A-induced oxidative stress in rat liver

Cyclosporine A (CsA) is the most widely used immunosuppressive drug for preventing graft rejection and autoimmune disease. However, the therapeutic treatment induces several side effects such as nephrotoxicity, cardiotoxicity, hypertension and hepatotoxicity. Among possible mechanisms of CsA-induced hepatic damage, oxidative stress has been suggested. Melatonin (Mel) has been successfully used as a potent antioxidant against many pathophysiological states. This experimental study was performed to test, during CsA treatment, the alterations of some heat shock proteins (HSP) and the Mel antioxidant properties against CsA-induced injury. Rats were divided into four groups, which were treated respectively with olive oil, Mel alone, CsA and CsA plus Mel for 30 days. At the end of the treatments, the animals were killed and hepatic tissue was treated for morphological (haematoxylin-eosin), biochemical (reduced glutathione, GSH and malondialdehyde, MDA) and immunohistochemical (HSP60, HSP72, GRP75 and MT) analyses. The results indicate that CsA-induced hepatotoxicity was characterised by morphological alterations in tissue architecture, changes in GSH and MDA levels and increase in stress protein expression. In conclusion, our data suggest that the imbalance between production of free oxygen radicals and antioxidant defence systems, due to CsA administration, is a mechanism responsible for oxidative stress. Moreover, we show that Mel plays a protective action against CsA-induced oxidative stress, as supported by biochemical and immunohistochemical results.

Histochemical and immunohistochemical evaluation of gingival collagen and metalloproteinases in peri-implantitis

The extra-cellular matrix of the gingival tissue plays an important role in the homeostasis of dental implants. In this work we have studied immunohistochemically the distribution of collagen I-III-IV-V, tenascin, metalloproteinases (MMP) 1-3-8-13 and TIMP-1 in three groups of patients: (1) subjects with natural teeth (healthy periodontal tissue), (2) subjects with normal peri-implant mucosa and (3) subjects with clinically evident peri-implantitis. The immunolabelling for collagen I-III-IV showed a similar pattern in all three groups. The labelling for collagen V increased in lamina propria of healthy peri-implant tissue and peri-implantitis. Tenascin immunolabelling in healthy and peri-implant tissues was scattered in lamina propria. In peri-implantitis tenascin immunolabelling increased mainly near to the basal lamina. The MMP-1-3-8 and TIMP-1 immunolabelling were very faint and localized in the stroma in all three groups. In healthy and peri-implant tissues MMP-13 immunolabelling was found in the lamina propria whereas in peri-implantitis MMP-13 immunolabelling was also in epithelium. On the whole, these data suggest that in the extracellular matrix of peri-implantitis there are alterations of collagen V, tenascin and MMP-13 patterns.

Cyclosporine A induces vascular fibrosis and heat shock protein expression in rat

The immunosuppressive drug Cyclosporine A (CsA) has been successfully used in several diseases with immunological basis and in transplant patients. However, the therapeutic treatment induces several side effects, which include the development of severe hypertension, renal failure and cardiotoxicity in the majority of the patients. Since the mechanism by which CsA induces hypertension is not well defined, the aim of this study is to evaluate the morphological changes and the expression of heat shock proteins (HSPs) in the thoracic aorta of CsA-treated rats. The study was carried out on 40 male Wistar rats with an average weight of 200-250 g. The animals were divided into four groups. Groups I and II were injected subcutaneously (sc) daily with castor oil for 15 or 30 days and used as control; group III and IV were injected sc daily with CsA (15 mg/Kg/day) for 15 or 30 days. After the end of the treatment, the thoracic aortae were removed and treated for morphological (Sirius Red) and immunohistochemical evaluation (HSP 25, alphaB-crystallin and HSP 47). The results indicate that CsA induces (1) time-dependent vascular damage visible as fibrosis mainly in intima-media tunica of aorta, and (2) a clear increase in HSP expression. In fact, after 30 days of treatment, HSP and alphaB-crystallin are increased in all tunicas, whereas HSP47 only in tunica media and adventitia. These findings could suggest that these proteins are up-regulated after CsA treatment in order to play a defensive role in vascular damage.

Mercuric chloride-induced alterations in stress protein distribution in rat kidney

Mercuric chloride (HgCl2) induces acute renal failure associated to tubular impairment in experimental animals and humans. Stress proteins are a superfamily of proteins, comprising heat- shock proteins (HSP) and glucose-regulated proteins (GRP), enhanced or induced in the kidney in response to stress. They act as molecular chaperones that protect organelles and repair essential proteins which have been denatured during adverse conditions. The involvement of stress proteins in mercury-nephrotoxicity has not yet been well clarified. This study was undertaken to detect the tubular distribution of four stress proteins (HSP25, HSP60, GRP75, HSP72) in the rat kidney injected with HgCl2 and to quantify lysosomal and mitochondrial changes in straight proximal tubules, the main mercury target. Sprague-Dawley rats were administered i.p. with progressive sublethal doses of HgCl2 (0.25 mg/kg, 0.5 mg/kg, 1 mg/kg and 3.5 mg/kg) or saline (as controls) and sacrificed after 24 h. In dosages over 0.50 mg/kg, stress proteins increased and changed localization in a dose-dependent manner. HSP25 was focally expressed in altered proximal tubules at 1 mg/kg but in the macula densa it was at 3.5 mg/kg. HSP60 and GRP75 were intense in the nucleus and cytoplasm of proximal tubules but moderate in distal tubules. HSP72 was induced in distal tubules after low exposures but in proximal tubules it happened at the highest dose. Moreover, a significant increase in lysosomal and total mitochondria (normal and with broken cristae) area and density were progressively found after HgCl2 treatments. Stress proteins could represent sensitive biomarkers that strongly correlate with the degree of oxidative injury induced by HgCl2 in the rat proximal tubules.

Dose-dependent mercuric chloride tubular injury in rat kidney

Mercuric chloride (HgCl(2)) produces an acute renal failure in experimental animal models. Since the mechanism of tubular injury has not completely been clarified, this morpho-quantitative study was undertaken to better understand the effects of 2 sublethal doses (T1=1 mg/kg and T3.5=3.5 mg/kg) of HgCl(2) in rat proximal tubules. Morphometrical analysis was performed to quantify both cytoplasmic and nuclear changes found in treated in respect to saline-injected proximal tubules. In the controls, single-cell damage was occasional and nucleolar changes were absent. HgCl(2) induced progressively severe proximal tubule atrophy. In the T1 group, necrosis was limited to pars recta cells and nucleolar segregation was often partial. In the T3.5 group, atrophy was extensive in both convoluted and straight tracts, the nucleolus was completely segregated and coiled body-like inclusions were detached from it. Ultrastructural analysis confirmed dose-dependent changes within straight proximal tubules, i.e., necrosis, apoptosis, nucleolar segregation, swollen mitochondria, vacuolization, and disrupted brush border. In conclusion, in the rat kidney HgCl(2) induced dose-dependent alterations not only in the cytoplasm but also in the nucleus of proximal tubule cells. These findings will be useful for better understanding of the pathogenesis of mercury nephrotoxicity and its genotoxic effect.

Small heat shock proteins expression in rat kidneys treated with cyclosporine A alone and combined with melatonin

Small heat shock proteins (sHSPs) are cytoskeletal chaperones constitutively expressed in the normal kidney but enhanced with beneficial roles during adverse stimuli. Cyclosporine A is an immunosuppressive drug with major adverse side effect such as severe nephrotoxicity. Among possible mechanisms of cyclosporine A-induced renal damage, oxidative stress and cytoskeletal damage have been suggested. Melatonin has been successfully used as antioxidant against many renal diseases. This in vivo study was performed to shed light on the protective effect of melatonin against cyclosporine A-induced renal alterations. We treated rats with cyclosporine A alone, or combined with melatonin, and with melatonin alone (as controls) for 40 days and analysed the renal abundance and distribution of two sHSPs, HSP25 and alpha B-crystallin. These data were correlated with the histopathological effects of the treatments. Cyclosporine A induced insoluble isoforms that moved to soluble fractions after melatonin coadministration as in controls. After cyclosporine A treatment, an intense signal for sHSPs was found within the glomeruli, nucleus and cytoplasm of cortical tubules, collecting ducts and vascular wall. After melatonin supply, the staining was faint, limited to the cytoplasm of cortical tubules, similar to controls. Both fibrosis and tubular alterations significantly decreased after melatonin coadministration. In conclusion, HSP25 and alpha B-crystallin are overexpressed in the rat kidney treated with cyclosporine A but are similar to controls after combined melatonin. This could be a consequence of the cytoprotective effect of melatonin in this nephrotoxic model so that a beneficial sHSPs response is unnecessary.

Cyclosporine A-induced kidney alterations are limited by melatonin in rats: an electron microscope study

The effect of melatonin on experimental prolonged cyclosporine A (CsA) nephrotoxicity was analyzed by electron microscopy and morphometry. Twenty female Wistar rats were divided into groups that received (1) CsA at a therapeutic dose (15 mg/kg/day) sc for 40 days; (2) olive oil, CsA vehicle, as controls; (3) CsA plus melaton (1 mg/kg) ip for the same time; (4) melatonin alone, as additional controls. All controls had normal renal ultrastructure. However, in CsA group, both tubular and glomerular alterations were observed. The authors found apoptotic and necrotic proximal tubules with disrupted brush border, swollen mitochondria, abundant lysosomes; in the glomerulus, amorphous basement membrane, and abnormal mesangial matrix. CsA plus melatonin administration partly prevented these changes. Nevertheless, fibrillar deposits in podocytes and basolateral membrane dilatations in proximal tubules were observed. Histopathological analysis on semithin sections and ultrastructural morphometry were also performed. CsA induced interstitial fibrosis, atrophy, and PAS positive inclusions in the proximal tubules. Moreover, CsA reduced glomerular and mesangial volume but enhanced mesangial matrix volume and basement membrane thickness. After CsA plus melatonin, these parameters were reduced in the proximal tubules and restored in the glomerulus. In conclusion, melatonin attenuated morpho-quantitative alterations induced by CsA in the rat kidney.

Distribution of heat shock proteins in kidneys of rats after immunosuppressive treatment with cyclosporine A

Cyclosporine A (CsA), a fungal undecapeptide, is the most common immunosuppressive drug used in organ transplantation and auto-immune diseases. However, it has severe side effects mainly on renal structures and functions. Therefore, nephrotoxicity is the major limiting side effect. Heat shock proteins (HSPs) are molecular chaperones, that are induced or expressed at high levels in mammalian cells due to a variety of adverse effects. HSPs have beneficial roles in protein processing and protection against cell injury. In the present study, we examined immunohistochemically levels of expression and localization patterns of various HSPs in rat kidneys after administration of a therapeutic CsA dose during 30 days. After CsA treatment, both constitutive HSP 25 and alpha B-crystallin immunoreactivity became stronger in glomeruli, proximal tubules and collecting ducts. Nuclear translocation of these proteins was detected in renal tubules. HSP 47 was detected in the interstitial space between tubules, vascular smooth muscle and medullary rays. Finally, HSP 72 was induced in the cytoplasm of epithelial cells of proximal and distal tubules, and in the cytoplasm of epithelial cells of Henle limbs and collecting ducts. These data demonstrate that CsA clearly induces increased immunoreactivity of HSPs in defined structures of rat kidneys. These findings suggest that these proteins are functionally involved in the defence against renal cellular damage caused by prolonged drug treatment in rat.