Pathophysiological mechanisms of renal fibrosis: a review of animal models and therapeutic strategies

Chronic kidney disease (CKD) is a long-term condition in which the kidneys do not work correctly. It has a high prevalence and represents a serious hazard to human health and estimated to affects hundreds of millions of people. Diabetes and hypertension are the two principal causes of CKD. The progression of CKD is characterized by the loss of renal cells and their replacement by extracellular matrix (ECM), independently of the associated disease. Thus, one of the consequences of CKD is glomerulosclerosis and tubulointerstitial fibrosis caused by an imbalance between excessive synthesis and reduced breakdown of the ECM. There are many molecules and cells that are associated with progression of renal fibrosis e.g. angiotensin II (Ang II). Therefore, in order to understand the biopathology of renal fibrosis and for the evaluation of new treatments, the use of animal models is crucial such as: surgical, chemical and physical models, spontaneous models, genetic models and in vitro models. However, there are currently no effective treatments for preventing the progression of renal fibrosis. Therefore it is essential to improve our knowledge of the cellular and molecular mechanisms of the progress of renal fibrosis in order to achieve a reversion/elimination of renal fibrosis.This work was supported in part by a project grant from the Fundação para a Ciência e Tecnologia, Ministério da Educação, Portugal (grant no. SFRH/PROTEC/67576/2010).info:eu-repo/semantics/publishedVersio

On the ordeal of quinolone preparation via cyclisation of aryl-enamines; synthesis and structure of ethyl 6-methyl-7-iodo-4-(3-iodo-4-methylphenoxy)-quinoline-3-carboxylate

Recent studies directed to the design of compounds targeting the bc(1) protein complex of Plasmodium falciparum, the parasite responsible for most lethal cases of malaria, identified quinolones (4-oxo-quinolines) with low nanomolar inhibitory activity against both the enzyme and infected erythrocytes. The 4-oxo-quinoline 3-ester chemotype emerged as a possible source of potent bc(1) inhibitors, prompting us to expand the library of available analogs for SAR studies and subsequent lead optimization. We now report the synthesis and structural characterization of unexpected ethyl 6-methyl-7-iodo-4-(3-iodo-4-methylphenoxy)quinoline-3-carboxylate, a 4-aryloxy-quinoline 3-ester formed during attempted preparation of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate (4-oxo-quinoline 3-ester). We propose that the 4-aryloxy-quinoline 3-ester derives from 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate (4-hydroxy-quinoline 3-ester), the enol form of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate. Formation of the 4-aryloxy-quinoline 3-ester confirms the impact of quinolone/hydroxyquinoline tautomerism, both on the efficiency of synthetic routes to quinolones and on pharmacologic profiles. Tautomers exhibit different cLogP values and interact differently with the enzyme active site. A structural investigation of 6-methyl-7-iodo-4-oxo-quinoline-3-carboxylate and 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate, using matrix isolation coupled to FTIR spectroscopy and theoretical calculations, revealed that the lowest energy conformers of 6-methyl-7-iodo-4-hydroxy-quinoline-3-carboxylate, lower in energy than their most stable 4-oxo-quinoline tautomer by about 27 kJ mol(-1), are solely present in the matrix, while the most stable 4-oxo-quinoline tautomer is solely present in the crystalline phase.Fundacao para a Ciencia e Tecnologia (FCT - Portugal) [UID/Multi/04326/2013]; QREN-COMPETE-UE; CCMAR; FCT [SFRH/BD/81821/2011, RECI/BBB-BQB/0230/2012, UI0313/QUI/2013, UID/FIS/04564/2016]; FEDER/COMPETE-UE; [PTDC/QEQ-QFI/3284/2014 - POCI-01-0145-FEDER-016617]info:eu-repo/semantics/publishedVersio

Chaetomellic acid A treatment improves oxidative stress in rats with renal mass reduction

Chaetomellic acid A (CA) is a potent and highly specific inhibitor of Ras farnesyl-protein transferase that has shown to decrease oxidative stress in rats with brain damage. Oxidative stress has been suggested to play an important role in the pathogenesis of chronic renal disease. Thus, the aim of this work was to evaluate the effect of chronic treatment with CA on oxidative stress in a model of renal mass reduction. Male Wistar rats were subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been placed in four experimental groups: RMR rats without treatment (n=12); RMR rats treated with CA (n=8); SO rats without treatment (n=13); SO rats treated with CA (n=13). CA was intraperitoneally administered in a dose of 0.23 μg/Kg three times a week for six months. To evaluate the effect of CA on renal redox potential, the status of oxidative stress in renal tissues was determined. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity, and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CA administration significantly increased catalase and GR activity (p<0.05), and increased GSH/GSSG ratio, but no significant difference between the treated and no treated groups was found in this ratio. These data suggest that CA can attenuate 5/6 RMR-induced oxidative stress and therefore, contribute to prevention of progressive renal failure in chronic renal disease

The relation between the erythrocyte nitric oxide and hemorheological parameters

© 2006 – IOS Press and the authors. All rights reservedWe stimulated human erythrocytes obtained from patients with hypercholesterolemia (HC; n = 42), renal transplantation (RT; n = 18) and hypertension (HT; n = 10) with acetylcholine (ACh 10 μM) and measured the amperometric NO production, comparing with the NO levels achieved on erythrocytes of healthy persons (n = 27). We also measured the hemoglobin, hematocrit, erythrocyte aggregation, erythrocyte deformability, plasma viscosity and fibrinogen concentration from human blood samples. The erythrocytes NO levels were of 2.5 ± 0.7 nM (P = 0.038, HC), 2.4 ± 1.1 nM (RT) and 2.2 ± 0.8 nM (HT) against the 2.0 ± 0.8 nM for the control groups. For each group and at each shear stress value, the erythrocytes deformability decreases with the increase of the NO concentration after ACh stimulation. We observed a significant increase of the control values on the erythrocyte aggregation results on each patient group. Besides the lower erythrocyte deformability obtained on HC, RT and HT blood samples, the erythrocytes produced higher NO levels after ACh stimulation than the healthy ones. The power of erythrocyte hemorheological behaviour could be compensated by the NO production at the presence of acetylcholine. We can hypothesises that cholinergic drugs could be used as co-adjuvants of specific therapeutics compounds on these studied diseases.This work was supported by “Fundação para a Ciência e Tecnologia”, Portugal

Ultrasonographic evaluation of the kidney in 5/6 nephrectomized rats: Correlation with biochemical and histopathological findings

To characterize the kidney alterations associated with renal mass reduction by two-dimensional ultrasound and assess the correlation of the ultrasonographic parameters with the histological and biochemical findings. Materials and Methods: Rats were divided into two groups: sham-operated animals (n=13), and animals which underwent renal mass reduction (RMR) through 5/6 nephrectomy (n=14). Renal length, renal thickness, cortical thickness, medullary length and echogenicity of the kidneys were evaluated by ultrasonography at 3 and 6 months after the RMR. Results: Except for the renal length, the renal dimensions at 3 and 6 months were significantly higher in the RMR group when compared to the sham-operated group (p < 0.05). Furthermore, the cortical and medullary echogenicity was significantly higher in the RMR group when compared to the sham-operated group (p < 0.05). A significant correlation was observed between the plasma creatinine level and the renal length 3 months after RMR (r=-0.612, p=0.045). Conclusion: These data support future application of ultrasonography for monitoring the progression of renal damage in chronic studies with the 5/6 nephrectomy model.This work was supported by : European Investment Funds by FEDER/COMPETE/POCI Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT – the Portuguese Foundation for Science and Technology, under project UID/AGR/04033/2013; and by European Investment Funds by FEDER/COMPETE/POCI Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER-016728 and National Funds by FCT – the Portuguese Foundation for Science and Technology, under the project PTDC/DTP-DES/6077/2014.info:eu-repo/semantics/publishedVersio

Avaliação da função renal em ratos wistar com insuficiência renal

A incidência e a prevalência da doença renal crónica continuam a aumentar em todo o mundo. O modelo de redução de 5/6 de massa renal (5/6 RMR) é um dos procedimentos experimentais mais utilizados para a indução e o estudo das alterações associadas a uma insuficiência renal crónica. A resposta adaptativa do rim à redução cirúrgica do número de nefrónios parece ser suficientemente semelhante às características fisiopatológicas das nefropatias progressivas humanas. Neste estudo foram utilizados seis ratos machos da estirpe Wistar. Os animais foram anestesiados com xilazina (10 mg/kg) e ketamina (75 mg/kg). Em três animais foi realizada a redução de 5/6 de massa renal e nos restantes três a cirurgia foi simulada. Os animais foram divididos em dois grupos experimentais: grupo SO: animais em que a cirurgia foi simulada; e grupo RMR: animais submetidos à RMR. Foi realizada uma recolha de sangue e de urina no estado basal e depois mensalmente, durante 2 meses. Os animais submetidos à RMR apresentaram um aumento do fluxo urinário, um aumento das concentrações plasmáticas de ureia e de creatinina, uma diminuição da depuração de creatinina e um aumento das concentrações plasmáticas de potássio. Portanto, a redução cirúrgica de massa renal foi acompanhada por um declínio da função renal

The effects of long-term chaetomellic acid a administration on renal function and oxidative stress in a rat model of renal mass reduction

This study aimed to evaluate the effect of chronic treatment with chaetomellic acid A (CAA) on oxidative stress and renal function in amodel of renalmass reduction. Methods.MaleWistar ratswere subjected to 5/6 nephrectomy (RMR) or sham-operated (SO). One week after surgery, rats have been divided into four experimental groups: RMR: RMR rats without treatment (n = 14); RMR + CAA: RMR rats treated with CAA (n = 13); SO: SO rats without treatment (n = 13); and SO + CAA: SO rats treated with CAA (n = 13). CAA was intraperitoneally administered in a dose of 0.23 μg/Kg three times a week for six months. Results. RMR was accompanied by a significant reduction in catalase and glutathione reductase (GR) activity (p < 0.05) and a decrease in reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio. CAAadministration significantly increased catalase andGR activity (p < 0.05) and increased GSH/GSSG ratio, but no significant difference between the treated and nontreated groups was found in this ratio.No significant differences were found between theRMRgroups in any of the parameters of renal function.However, CAA administration slightly improves some parameters of renal function. Conclusions. These data suggest that CAA could attenuate 5/6 RMR-induced oxidative stress.The authors would like to thank Jos´e Miguel Lopez- Novoa for valuable comments and suggestions. This work is supported by European Investment Funds by FEDER/ COMPETE/POCI, Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145- FEDER-006958, and National Funds by FCT, Portuguese Foundation for Science and Technology, under Project UID/AGR/04033/2013, and by European Investment Funds by FEDER/COMPETE/POCI, Operational Competitiveness and Internationalization Programme, under Project POCI- 01-0145-FEDER-016728, and National Funds by FCT, Portuguese Foundation for Science and Technology, under Project PTDC/DTP-DES/6077/2014.info:eu-repo/semantics/publishedVersio

Avaliação da função renal em ratos wistar com insuficiência renal

A incidência e a prevalência da doença renal crónica continuam a aumentar em todo o mundo. O modelo de redução de 5/6 de massa renal (5/6 RMR) é um dos procedimentos experimentais mais utilizados para a indução e o estudo das alterações associadas a uma insuficiência renal crónica. A resposta adaptativa do rim à redução cirúrgica do número de nefrónios parece ser suficientemente semelhante às características fisiopatológicas das nefropatias progressivas humanas. Neste estudo foram utilizados seis ratos machos da estirpe Wistar. Os animais foram anestesiados com xilazina (10 mg/kg) e ketamina (75 mg/kg). Em três animais foi realizada a redução de 5/6 de massa renal e nos restantes três a cirurgia foi simulada. Os animais foram divididos em dois grupos experimentais: grupo SO: animais em que a cirurgia foi simulada; e grupo RMR: animais submetidos à RMR. Foi realizada uma recolha de sangue e de urina no estado basal e depois mensalmente, durante 2 meses. Os animais submetidos à RMR apresentaram um aumento do fluxo urinário, um aumento das concentrações plasmáticas de ureia e de creatinina, uma diminuição da depuração de creatinina e um aumento das concentrações plasmáticas de potássio. Portanto, a redução cirúrgica de massa renal foi acompanhada por um declínio da função renal