Long-term treatment with chaethomellic acid A reduces glomerulosclerosis and arteriolosclerosis in a rat model of chronic kidney disease

The high prevalence of end-stage renal disease emphasizes the failure to provide therapies to effectively prevent and/or reverse renal fibrosis. Therefore, the aim of this study was to evaluate the effect of long-term treatment with chaethomellic acid A (CAA), which selectively blocks Ha-Ras farnesylation, on renal mass reduction-induced renal fibrosis. Male Wistar rats were sham-operated (SO) or subjected to 5/6 renal mass reduction (RMR). One week after surgery, rats were placed in four experimental groups: SO:SO rats without treatment (n = 13); SO + CAA: SO rats treated with CAA (n = 13); RMR:RMR rats without treatment (n = 14); and RMR + CAA:RMR 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. Renal fibrosis was evaluated by two-dimensional ultrasonography and histopathological analysis. The kidneys of the RMR animals treated with CAA showed a significantly decrease in the medullary echogenicity (p < 0.05) compared with the RMR rats that received no treatment. Glomerulosclerosis and arteriolosclerosis scores were significantly lower (p < 0.001) in the RMR + CAA group when compared with the RMR group. There were no significant differences in interstitial fibrosis, interstitial inflammation and tubular dilatation scores between the RMR + CAA and RMR groups. These data suggest that CAA can be a potential future drug to attenuate the progression of chronic kidney disease.This work is supported by : European Investment Funds by FEDER/COMPETE/POCI– Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013; and by European Investment Funds by FEDER/COMPETE/POCI– Operacional Competitiveness and Internacionalization Programme, under Project POCI-01-0145-FEDER-016728 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project PTDC/DTP-DES/6077/2014.info:eu-repo/semantics/publishedVersio

Efeito das interacções adenosina-angiotensina II sobre a depuração renal num modelo experimental de diabetes

A nefropatia diabética é a principal causa de falência renal e, consequentemente, factor determinante de morbilidade e mortalidade relacionada com a diabetes mellitus (DM). No estado inicial da DM verifica-se hiperfiltração glomerular. A função glomerular pode ser estimada pela quantificação da taxa de filtração glomerular (GFR). A adenosina regula a GFR, modula o sistema renina-angiotensina (RAS) e o mecanismo de feedback tubuloglomerular. A actividade do RAS renal encontra-se aumentada na nefropatia diabética e contribui para a lesão progressiva da barreira de filtração glomerular. O bloqueio do RAS constitui uma abordagem terapêutica fundamental em doentes diabéticos. O efeito inibitório da adenosina sobre o RAS pode ser importante neste contexto, podendo a adenosina constituir um importante novo alvo terapêutico no contexto da nefropatia diabética. Foram objectivos deste trabalho a implementação de uma metodologia para quantificar a GFR, caracterizar os efeitos da 2-cloroadenosina (2CADO), um análogo estável da adenosina, sobre a função de renal de ratos com diabetes experimental induzida por injecção de estreptozotocina, e relacioná-los com a actividade do RAS renal. Da implementação da metodologia para quantificar a GFR, foi possível concluir que o melhor método inclui a injecção intravenosa de inulina radioactiva ou fluorescente e determinação do time-course do decaimento no plasma. A administração intraperitoneal de 2CADO aos ratos diabéticos atenuou o não aumento de peso corporal e o aumento da ingestão de comida e bebida, e da excreção de urina. Além disso, atenuou a excreção urinária de glicose e de ureia e normalizou a excreção urinária de proteínas. Os ratos diabéticos apresentaram uma excreção urinária da angiotensinogéneo superior à dos ratos controlo e a 2CADO não alterou este resultado. Os resultados com a 2CADO demonstram a sua influência benéfica na nefropatia diabética. Estes efeitos da 2CADO podem estar relacionados com a capacidade para baixar a glicemia e melhorar a resistência à insulina mas também com efeitos renais directos e indirectos. São necessários, no entanto, estudos mais aprofundados para avaliar se a interacção adenosina/Ang II participa nesta renoprotecção indirecta.Diabetic nephropathy is the main cause for end-stage renal disease and, consequently, a determinant factor to morbidity and mortality related to diabetes mellitus (DM). Initially, DM is characterized by glomerular hyperfiltration. Glomerular function can be estimated by quantification of glomerular filtration rate (GFR). Adenosine regulates GFR, modulates the renin-angiotensin system (RAS) and the tubuloglomerular feedback. Renal RAS activity is enhanced in diabetic nephropathy and contributes to impairment of glomerular filtration barrier. Pharmacological agents that inhibit RAS have been recommended to diabetic patients. Adenosine inhibitory effect of RAS can be important in this context as a new therapeutical target in diabetic nephropathy. The aims of these study were to implement a new method for GFR quantification and to characterize the effects of 2-chloroadenosin (2CADO), a stable and non-metabolized analogue of adenosine, in renal function of estreptozotocininduced diabetic rats and relate them with renal RAS activity. Our results show that the most accurate way to quantify GFR is to inject radioactive or fluorescent inulin, intravenously, and follow plasma decay time-course. The intraperitoneal administration of 2CADO, to estreptozotocin-induced diabetic rats, attenuates the arrest of body weight, and food and water intake, and urine excretion. Furthermore, it attenuates the urinary excretion of glucose and urea and normalizes protein excretion. Estreptozotocin-induced diabetic rats excreted more angiotensinogen than control rats, and 2CADO administration did not change these result. Taken together, the results express the beneficial effect of 2CADO in diabetic nephropathy. 2CADO effects may be related to the capacity to improve glicemia and insulin resistance, but also with direct and indirect renal effects. Further studies are required to evaluate if the adenosine/angiotensin II interaction participates in these indirect renoprotection

Compensatory renal hypertrophy, mitochondria and redox status

A reduction in functional renal mass occurs in humans during aging and severe kidney damage from diseases, injuries, infections and congenital conditions and after nephrectomy. Nephrectomy, or surgical removal of a kidney or a section of a kidney, is performed for treatment of unilateral secondary renal cancer, infections and for kidney transplantation. As a result, the remaining renal tissue undergoes compensatory growth due primarily to hypertrophy, in which both the size and functional capacity of the remaining kidney are increased. Renal compensatory hypertrophy is associated with a series of physiological, morphological and biochemical changes that also have toxicological implications. Previous studies have shown that compensatory renal cellular hypertrophy after uninephrectomy resulted in a hypermetabolic state, increased glutathione (GSH) content, but higher renal oxidative stress. These changes are also associated with increased susceptibility of renal proximal tubule cells to several drugs and environmental chemicals. Furthermore, our lab also showed that overexpression of mitochondrial GSH transporters, the dicarboxylate (DIC, Slc25a10) and 2-oxoglutarate (OGC, Slc25a11) carriers, in NRK-52E cells, which are derived from normal rat kidney proximal tubules, exhibited increased mitochondrial GSH uptake, contents of GSH and protection from chemically induced apoptosis from exposure to nephrotoxicants. Based on these previous observations, we hypothesized that compensatory renal hypertrophy after uninephrectomy alters renal function in vivo and mitochondrial status and modulation of mitochondrial redox status alters susceptibility to nephrotoxicants in the remnant kidney. In this study, we used a uninephrectomized (NPX) rat model to induce compensatory renal growth. Our results show alterations in renal physiological parameters consistent with modest renal injury, altered renal cellular energetics, upregulation of certain renal plasma membrane transporters, including some that have been observed to transport GSH, and evidence of increased oxidative stress in mitochondria from the remnant kidney of NPX rats. Our present results provide further evidence that compensatory renal hypertrophy is associated with mitochondrial hypertrophy and hyperpolarization and manipulation of mitochondrial GSH transporters in PT cells of hypertrophied kidney alters susceptibility to chemically induced injury. These studies provide additional insight into the molecular changes that occur in compensatory renal hypertrophy and should help in the development of novel therapeutic approaches for patients with reduced renal mass

Aspectos laboratoriais do lupus eritematoso sistemico com enfase na excreção urinaria de albumina e alfa-1-microglobulina

Orientadores: Celia Regina Garlipp, Paula Virginia BottiniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências MédicasResumo: O envolvimento renal é uma causa importante de morbidade e mortalidade no LES. Alterações morfológicas renais são observadas em quase todos os pacientes sendo que 40-75% deles desenvolvem doença renal clínica, indicada por níveis aumentados de creatinina plasmática, proteinúria e/ou hematúria. O presente estudo tem como objetivo avaliar a excreção de proteínas urinárias específicas em pacientes com LES e sua possível correlação com alterações hematológicas, urinárias ou bioquímicas. Foram selecionados 47 pacientes com LES, sem evidência clínica e laboratorial de doença renal e divididos em dois Grupos (Grupo I = 35 pacientes sem história de nefrite e Grupo 2 = 12 pacientes com história de nefrite). Durante o período de um ano e a intervalos regulares de 3 meses, esses pacientes foram avaliados sendo que de cada indivíduo, em cada etapa do estudo, amostras sangüíneas e amostras urinárias isoladas e de 24h, foram coletadas e submetidas às seguintes determinações laboratoriais: hemograma, contagem de plaquetas, velocidade de hemossedimentação, pesquisa de anticorpo anti-DNA nativo, perfil lipídico (colesterol total, HDL-colesterol, triglicerídeos, LDL-colesterol, VLDL-colesterol, lipoproteína (a), apolipoproteína A1 e apolipoproteína B), determinação do clearance de creatinina, dosagens urinárias de proteína total, creatinina (para estabelecer a relação proteína urinária/creatinina), microalbuminúria (indicada pela relação MALB/CREA), alfa1-microglobulina (indicada pela relação A1M/CREA), sedimento urinário e pesquisa de dismorfismo eritrocitário. Excreções alteradas de MALB/CREA (23% no Grupo I e 25% no Grupo II) e de A1M/CREA (17% no Grupo I e 8% no Grupo II) não apresentaram diferenças significativas entre os grupos estudados (p>0,05). O mesmo foi observado em relação aos outros parâmetros avaliados. Pesquisa positiva para anti-DNA nativo e perfis lipídicos alterados não mostraram associação com MALB/CREA (p>0,05). Clearance de creatinina não sofreu alteração ao longo do tempo e não se mostrou dependente da excreção de albumina observando¿se uma fraca correlação estes dois parâmetros (p = 0,0774). Apesar da variabilidade na excreção urinária de albumina ao longo do tempo, não houve associação dessa excreção com alterações lipídicas, lipoproteicas e apolipoproteicas e com ANTI-DNA nativo (p > 0,05). Concluímos que alterações na excreção urinária de albumina e de alfa-1-microglobulina são freqüentes no LES, embora possam ser decorrentes da própria variabilidade biológica da excreção dessas proteínasAbstract: Renal involvement in systemic lupus erythematosus (SLE) is frequent although the evolution of renal function abnormalities is not completely elucidated. Morphological renal changes are present in virtually all patients, as 40% to 75% develop clinical renal disease. Lupus nephritis is an important cause of mortality and morbidity of the disease. Consequently, the major topic of investigations focus on the diagnosis, treatment and prognosis of this condition.This study was performed to evaluate whether the urinary protein excretion profile in systemic lupus erythematosus (SLE) patients could predict the development of lupus nephritis and their possible relationship with hematological, urinary and biochemical abnormalities. Forty seven patients divided into Group I (GI) with 35 patients without history of lupus nephritis and Group II (GII) with 12 patients with history of nephritis were studied during a year period. Random urine samples, 24-hour urine collection and 12-hour fasting blood samples were collected. Laboratory studies included: hemogram, platelet count, erythrocyte sedimentation rate, anti-dsDNA antibodies, lipid profiles, creatinine clearance, total urine protein, routine urine analysis (including dysmorphic erythrocytes), urinary albumin/creatinine (MALB/CREA) and alpha-1-microglobulin/creatinine (A1M/CREA). Altered excretions of MALB/CREA (23% GI; 25% GII) and A1M/CREA (17% GI; 8% GII) showed no significant differences between the Groups (p>0.05). The same was observed for the other analyzed parameters. Anti-dsDNA and altered lipid profiles were not associated with MALB/CREA (p>0.05). There was a tendency of a correlation between creatinine clearance and MALB/CREA (p=0.0774). Although altered excretions of MALB/CREA and A1M/CREA were frequent in SLE it seems to be due to the daily excretion variability of these proteinsMestradoCiencias BiomedicasMestre em Ciências Médica

New insights into the molecular regulation of kidney disease: contributions of APOL1 and MYH9

People of African ancestry (AA) are at greater risk of developing chronic kidney disease than those of non-AA. Much of this risk has been linked to specific genetic haplotypes on chromosome 22, near the genes APOL1, encoding apolipoprotein L1, and MYH9, encoding non-muscle myosin heavy chain IIA (NMHCIIA). The mechanisms by which the disease-associated chromosome 22 haplotypes promote kidney damage are unknown. Apolipoprotein L1 is a circulating protein with no known role in kidney function. However, the kidney disease-associated chromosome 22 haplotypes are protective against trypanosome infection, resulting in positive selective pressure for these haplotypes in western Africa, where trypanosome infection is endemic. In contrast, NMHCIIA may have an important role in glomerular function, and mutations in MYH9 are associated with glomerular disease, yet the disease-associated chromosome 22 haplotypes do not involve coding sequence variations in MYH9. With no clear disease-causing role for genes near the chromosome 22 risk locus, it is plausible that indirect mechanisms of gene regulation may be responsible for the increased disease risk. This study examines several potential pathways for kidney injury, including altered glomerular gene expression in carriers of chromosome 22 risk haplotypes, and the role of altered expression of MYH9 in podocyte cell biology and kidney disease. We found that carriers of chromosome 22 risk variants exhibited differential glomerular gene expression in pathways promoting kidney injury. We also found decreased glomerular NMHCIIA expression in human FSGS kidney biopsies, and altered cell structure and mechanical function when Myh9 is ablated in murine podocytes. Further, Myh9 podocyte deletion predisposed mice to glomerulopathy in response to injury by the DOCA-salt uninephrectomy model of hypertension. Taken together, these findings demonstrate direct and indirect effects of chromosome 22 risk variants on glomerular gene expression which promote kidney injury

Complement abnormalities in membranoproliferative glomerulonephritis and C3 glomerulopathy

PhD ThesisMembranoproliferative glomerulonephritis (MPGN) and C3 glomerulopathy (C3G) are rare diseases that associate with dysregulation of the alternative pathway (AP). The earliest abnormalities associated with these diseases were C3 nephritic factor and also rare genetic variants in the gene CFH that caused factor H (FH) deficiency. Since then, other acquired and genetic abnormalities in AP have been reported in MPGN and C3G. The aim of this project was to screen cohorts of MPGN and C3G for such abnormalities. Screening for rare sequence variants in genes encoding proteins involved in AP activity in two cohorts revealed a low prevalence of genetic abnormalities. Compared to the prevalence of C3 nephritic factor and autoantibodies to complement proteins, it was clear that the predominant abnormalities in these cohorts were acquired. Though few, rare genetic variants identified in CFH were studied in functional studies. The first was identified in a case of familial MPGN in the N-terminal domain of CFH. Functional studies included surface plasmon resonance and haemolytic assays to study a mutant protein in the setting of a short fragment comprising the N-terminal domain of FH. This initial study confirmed loss of function in a familial variant and formed the basis for further studies. In studies of eight other variants identified in MPGN and C3G and two other diseases that share complement risk factors, only two variants were likely to be functionally significant as demonstrated by complete loss of function. This highlights the need for such studies to correctly identify important variants. The significant functional effects initially identified in studies using short fragments were then confirmed in studies using full length protein. The significance of rare genetic variants in CFH needs to be considered even though MPGN and C3G are largely an autoimmune phenomenon.Medical Research Council and Northern Counties Kidney Research Fun

The role of immunoregulatory cells in healthy and sick African children.

Doctoral Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF.Papers from thesis on page iii