Gentamicin nephrotoxicity in animals: current knowledge and future perspectives

Due to high relative blood flow the kidney is prone to drug-induced damage. Aminoglycoside type antibiotic gentamicin is one of the leading cause of drug-induced nephrotoxicity. In recent years gentamicin nephrotoxicity is significantly reduced by shifting to once daily dosage as well as by eliminating known risk factors. Application of gentamicin is still related to serious side effects which are reported more often compared to other antibiotics. Because gentamicin is still heavily used and is highly efficient in treating infections, it is important to find mechanisms to reduce its nephrotoxicity. This aim can only be achieved through better understanding of kidney metabolism of gentamicin. This problem has been extensively researched in the last 20 years. The experimental results have provided evidence for almost complete understanding of mechanisms responsible for gentamicin nephrotoxicity. We now have well described morphological, biochemical and functional changes in kidney due to gentamicin application. During the years, this model has become so popular that now it is used as an experimental model for nephrotoxicity per se. This situation can mislead an ordinary reader of scientific literature that we know everything about it and there is nothing new to discover here. But quite opposite is true. The precise and complete mechanism of gentamicin nephrotoxicity is still point of speculation and an unfinished story. With emerge of new and versatile technics in biomedicine we have an opportunity to reexamine old beliefs and discover new facts. This review focuses on current knowledge in this area and gives some future perspectives

Thioredoxin reductase as a target enzyme for electrophilic anticancer drugs

Induced production of reactive oxygen species (ROS) is a common attribute of most cancer cells. One strategy for cancer cells to maneuver the increased and potentially toxic levels of ROS is to induce the expression of cellular antioxidants and redox regulators, such as the thioredoxin (Trx) system. The Trx system consists of Trx and the NADPH-dependent thioredoxin reductase (TrxR protein/Txnrd1 gene). TrxR reduces Trx, which subsequently reduces disulfides in various proteins and supplies ribonucleotide reductase with electrons for DNA synthesis. Mammalian TrxRs have wide substrate specificity, also reducing other targets than Trx. Cytosolic Trx1 and TrxR1 are induced upon oxidative stress and both have proven to be overexpressed in many tumors. They are therefore proposed as potential targets for anticancer therapy. TrxR is a selenoprotein and contains selenium in the form of selenocysteine (Sec). The Sec residue is mostly de-protonated at physiological pH and is highly nucleophilic, thus being easily targeted by electrophilic drugs. The aim of this thesis was to address the role of TrxR1 as a potential drug target for anticancer therapy and evaluate its importance for side effects associated with the widely used anticancer drug cisplatin (cDDP). This thesis reports that RITA, a compound shown to induce p53 dependent cell-death by interacting and restoring p53 activity, caused inhibition of TrxR1. Cell culture experiments showed that RITA induced a 130 kDa covalently linked TrxR1-dimer, in a p53 dependent fashion. Furthermore, red wine, rich of polyphenols and flavonoids, was also shown to efficiently inhibit TrxR activity and to be highly toxic to various cancer cell lines. Transient TrxR1 knockdown in a lung carcinoma cell line lowered the TrxR activity by 90% and caused increased sensitivity towards menadione and 1-chloro-2,4- dinitrobenzene. TrxR1 knockdown cells were, however, more resistant towards cDDP. Depleting the glutathione (GSH) levels in knockdown cells had no effect on cell growth, suggesting that the remaining TrxR activity still was enough to sustain Trx function. Recent experiments in mice showed that normal replication of hepatocytes required either one functional copy of the Txnrd1 gene or a functional GSH system, agreeing with the previous interpretation. cDDP treatment is associated with side effects such as ototoxicity and nephrotoxicity. cDDP inhibits TrxR1 and cDDP-derivatized enzyme species have previously been shown to gain a pro-oxidant role in the cells. Data on cDDP-triggered nephrotoxicity in mice presented herein suggest that the degree of kidney damage is influenced by the TrxR status in both liver and kidney. Decreased TrxR activity in liver was associated with more renal damage, while high TrxR expression in kidney correlated with increased kidney toxicity. Pharmacokinetic studies on cDDP and oxaliplatin (Oxa) in guinea pig, showed that the cochlear uptake of cDDP was significantly higher than for Oxa, thus explaining why Oxa only rarely causes ototoxicity. Using a cancer cell line it was also shown that cDDP, but not Oxa, induced cell death which was dependent on calcium and superoxide levels and caused TrxR inhibition. In summary, this thesis shows that TrxR1 is an anticancer drug target that can have an important impact on the outcome of chemotherapy and its associated side effects

Individualization of Immunosuppressive Therapy after Solid Organ Transplantation

__Abstract__ When an individual’s kidneys fail, there are three treatment options: hemodialysis, peritoneal dialysis or kidney transplantation. A successful kidney transplantation results in the best patient survival and a better quality of life compared to the two other treatment modalities. Kidney transplantation is therefore the preferred therapy for renal failure. The first deceased donor kidney transplantation in the United States was performed in 1950 by Lawler and colleagues on Ruth Tucker, a 44-year-old woman with polycystic kidney disease. Although the kidney transplant was rejected ten months later because no immunosuppressive therapy was available at the time, the intervening time allowed Tucker’s remaining native kidney (it was an orthotopic transplantation) to recover and she lived for another five years. At the same time in France, Küss, Hamburger, and others also performed a number of kidney transplantations

Anti-cancer drug validation: the contribution of tissue engineered models

Abstract Drug toxicity frequently goes concealed until clinical trials stage, which is the most challenging, dangerous and expensive stage of drug development. Both the cultures of cancer cells in traditional 2D assays and animal studies have limitations that cannot ever be unraveled by improvements in drug-testing protocols. A new generation of bioengineered tumors is now emerging in response to these limitations, with potential to transform drug screening by providing predictive models of tumors within their tissue context, for studies of drug safety and efficacy. Considering the NCI60, a panel of 60 cancer cell lines representative of 9 different cancer types: leukemia, lung, colorectal, central nervous system (CNS), melanoma, ovarian, renal, prostate and breast, we propose to review current Bstate of art^ on the 9 cancer types specifically addressing the 3D tissue models that have been developed and used in drug discovery processes as an alternative to complement their studyThis article is a result of the project FROnTHERA (NORTE-01-0145-FEDER-000023), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This article was also supported by the EU Framework Programme for Research and Innovation HORIZON 2020 (H2020) under grant agreement n° 668983 — FoReCaST. FCT distinction attributed to Joaquim M. Oliveira (IF/00423/2012) and Vitor M. Correlo (IF/01214/2014) under the Investigator FCT program is also greatly acknowledged.info:eu-repo/semantics/publishedVersio

Caenorhabditis elegans as a model system for studying drug induced mitochondrial toxicity

Today HIV-1 infection is recognized as a chronic disease with obligatory lifelong treatment to keep viral titers below detectable levels. The continuous intake of antiretroviral drugs however, leads to severe and even life-threatening side effects, supposedly by the deleterious impact of nucleoside-analogue type compounds on the functioning of the mitochondrial DNA polymerase. For detailed investigation of the yet partially understood underlying mechanisms, the availability of a versatile model system is crucial. We therefore set out to develop the use of Caenorhabditis elegansto study drug induced mitochondrial toxicity. Using a combination of molecular-biological and functional assays, combined with a quantitative analysis of mitochondrial network morphology, we conclude that anti-retroviral drugs with similar working mechanisms can be classified into distinct groups based on their effects on mitochondrial morphology and biochemistry. Additionally we show that mitochondrial toxicity of antiretroviral drugs cannot be exclusively attributed to interference with the mitochondrial DNA polymerase

Research Models for Studying Vascular Calcification

Calcification of the vessel wall contributes to high cardiovascular morbidity and mortality. Vascular calcification (VC) is a systemic disease with multifaceted contributing and inhibiting factors in an actively regulated process. The exact underlying mechanisms are not fully elucidated and reliable treatment options are lacking. Due to the complex pathophysiology, various research models exist evaluating different aspects of VC. This review aims to give an overview of the cell and animal models used so far to study the molecular processes of VC. Here, in vitro cell culture models of different origins, ex vivo settings using aortic tissue and various in vivo disease-induced animal models are summarized. They reflect different aspects and depict the (patho)physiologic mechanisms within the VC process

Morphometric study of myocardial changes during doxorubicin-induced cardiomyopathy in mice

Doxorubicin (DOX) is one of the most effective anti-cancer drugs in oncology, but may cause a cumulative dose-dependent cardiomyopathy in a number of cancer patients. The effect of DOX on the heart was studied in mice treated with i.v. injections of 2 mg/kg by measuring morphometric parameters, including nuclear index (number of non-myocytes/number of myocyte nuclei), reticulin index (reticulin area/number of myocyte transsections), nuclear transsectional area, myocyte transsectional area, capillary index (number of capillaries/number of myocyte transsections) and capillary transsectional area. The highest significant difference between control mice and DOX-treated mice was observed immediately after the 12th dose of DOX except for the two capillary parameters. The highest level of significance for these two parameters was obtained 12 weeks after the end of DOX treatment. In contrast to the observations in rats, mice did not develop a nephrotic syndrome during treatment with DOX. The morphometric analysis of myocardial changes in mice, as a quantitative and objective method, seems to be a good model for comparative studies on cardiomyopathy induced by anthracycline analogues

Potential Protective Role Exerted by Secoiridoids from Olea europaea L. in Cancer, Cardiovascular, Neurodegenerative, Aging-Related, and Immunoinflammatory Diseases

Iridoids, which have beneficial health properties, include a wide group of cyclopentane [c] pyran monoterpenoids present in plants and insects. The cleavage of the cyclopentane ring leads to secoiridoids. Mainly, secoiridoids have shown a variety of pharmacological effects including anti-diabetic, antioxidant, anti-inflammatory, immunosuppressive, neuroprotective, anti-cancer, and anti-obesity, which increase the interest of studying these types of bioactive compounds in depth. Secoiridoids are thoroughly distributed in several families of plants such as Oleaceae, Valerianaceae, Gentianaceae and Pedialaceae, among others. Specifically, Olea europaea L. (Oleaceae) is rich in oleuropein (OL), dimethyl-OL, and ligstroside secoiridoids, and their hydrolysis derivatives are mostly OL-aglycone, oleocanthal (OLE), oleacein (OLA), elenolate, oleoside-11-methyl ester, elenoic acid, hydroxytyrosol (HTy), and tyrosol (Ty). These compounds have proved their efficacy in the management of diabetes, cardiovascular and neurodegenerative disorders, cancer, and viral and microbial infections. Particularly, the antioxidant, anti-inflammatory, and immunomodulatory properties of secoiridoids from the olive tree (Olea europaea L. (Oleaceae)) have been suggested as a potential application in a large number of inflammatory and reactive oxygen species (ROS)-mediated diseases. Thus, the purpose of this review is to summarize recent advances in the protective role of secoiridoids derived from the olive tree (preclinical studies and clinical trials) in diseases with an important pathogenic contribution of oxidative and peroxidative stress and damage, focusing on their plausible mechanisms of the action involved.España Ministerio de Economía y Competitivida

UPLC-MS/MS analysis of ochratoxin A metabolites produced by Caco-2 and HepG2 cells in a co-culture system

Ochatoxin A (OTA) is one of the most important mycotoxins based on its toxicity. The oral route is the main gateway of entry of OTA into the human body, and specialized epithelial cells constitute the first barrier. The present study investigated the in vitro cytotoxic effect of OTA (5, 15 and 45 μM) and production of OTA metabolities in Caco-2 and HepG2 cells using a co-culture Transwell System to mimic the passage through the intestinal epithelium and hepatic metabolism. The results derived from MTS cell viability assays and transepithelial electrical resistance measurements showed that OTA was slightly cytotoxic at the lowest concentration at 3 h, but significant toxicity was observed at all concentrations at 24 h. OTA metabolites generated in this co-culture were ochratoxin B (OTB), OTA methyl ester, OTA ethyl ester and the OTA glutathione conjugate (OTA-GSH). OTA methyl ester was the major metabolite found in both Caco-2 and HepG2 cells after all treatments. Our results showed that OTA can cause cell damage through several mechanisms and that the OTA exposure time is more important that the dosage in in vitro studies. OTA methyl ester is proposed as an OTA exposure biomarker, although future studies should be conducted.The authors are grateful to the Spanish (Project AGL2011-24862) and Catalonian (XaRTA-Reference Network on Food Technology) Governments for their financial support. C.A. González-Arias thanks the Secretaria de Universitats i Recerca del Departament de Economia i Coneixement of the Generalitat de Catalunya for the pre-doctoral grant