RESUMO
Type II diabetes mellitus (T2DM) is characterized by insulin resistance, ß-cell dysfunction and hyperglycemia. In addition to well known risk factors such as lifestyle and genetic risk score, accumulation of environmental toxicants in organs relevant to glucose metabolism is increasingly recognized as additional risk factors for T2DM. Here, we describe the development of an in vivo oral cadmium (Cd) exposure model. It was shown that oral Cd exposure in drinking water followed by washout and high fat diet (HFD) in C57BL/6N mice results in islet Cd bioaccumulation comparable to that found in native human islets while mitigating the anorexic effects of Cd to achieve the same weight gain required to induce insulin resistance as in Cd naïve control mice. Inter individual variation in plasma glucose and insulin levels as well as islet Cd bioaccumulation was observed in both female and male mice. Regression analysis showed an inverse correlation between islet Cd level and plasma insulin following a glucose challenge in males but not in females. This finding highlights the need to account for inter individual target tissue Cd concentrations when interpreting results from in vivo Cd exposure models. No effect of Cd on insulin secretion was observed in islets ex vivo, highlighting differences between in vivo and ex vivo cadmium exposure models. In summary, our oral in vivo Cd exposure-washout with HFD model resulted in islet Cd bioaccumulation that is relevant in the context of environmental cadmium exposure in humans. Here, we showed that islet Cd bioaccumulation is associated with complex cadmium-mediated changes in glucose clearance and ß-cell function. The model described here will serve as a useful tool to further examine the relationship between Cd exposure, islet Cd bioaccumulation, dysglycemia and their underlying mechanisms.
Assuntos
Intoxicação por Cádmio , Diabetes Mellitus Tipo 2 , Resistência à Insulina , Insulinas , Ilhotas Pancreáticas , Animais , Cádmio/metabolismo , Cádmio/toxicidade , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica/efeitos adversos , Feminino , Glucose/metabolismo , Insulina/metabolismo , Insulinas/metabolismo , Insulinas/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Type II diabetes mellitus (T2DM) is a multifactorial disease process that is characterized by insulin resistance and impairment of insulin-producing pancreatic islets. There is evidence that environmental exposure to cadmium contributes to the development of T2DM. The presence of cadmium in human islets from the general population and the uptake of cadmium in ß-cells have been reported. To identify cadmium-mediated changes in gene expression and molecular regulatory networks in pancreatic islets, we performed next-generation RNA-Sequencing (RNA-Seq) in islets following either in vivo (1 mM CdCl2 in drinking water) or ex-vivo (0.5 µM CdCl2) exposure. Both exposure regiments resulted in islet cadmium concentrations that are comparable to those found in human islets from the general population. 6-week in vivo cadmium exposure upregulates the expression of five genes: Synj2, Gjb1, Rbpjl, Try5 and 5430419D17Rik. Rbpjl is a known regulator of ctrb, a gene associated with diabetes susceptibility. With 18-week in vivo cadmium exposure, we found more comprehensive changes in gene expression profile. Pathway enrichment analysis showed that these secondary changes were clustered to molecular mechanisms related to intracellular protein trafficking to the plasma membrane. In islet culture, cadmium ex vivo significantly induces the expression of Mt1, Sphk1, Nrcam, L3mbtl2, Rnf216 and Itpr1. Mt1 and Itpr1 are known to be involved in glucose homeostasis. Collectively, findings reported here revealed a complex cadmium-mediated effect on pancreatic islet gene expression at environmentally relevant cadmium exposure conditions, providing the basis for further studies into the pathophysiological processes arising from cadmium accumulation in pancreatic islets.
Assuntos
Cloreto de Cádmio/toxicidade , Perfilação da Expressão Gênica , Ilhotas Pancreáticas/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Administração Oral , Animais , Cloreto de Cádmio/administração & dosagem , Cloreto de Cádmio/sangue , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos Endogâmicos C57BL , RNA-Seq , Fatores de Tempo , Técnicas de Cultura de TecidosRESUMO
The understanding of cellular Cd2+ accumulation and toxicity is hampered by a lack of fluorescent indicators selective for intracellular free Cd2+ ([Cd2+]i). In this study, we used depolarized MIN6 mouse pancreatic beta cells as a model for evaluating [Cd2+]i detection with commercially available fluorescent probes, most of which have been traditionally used to visualize [Ca2+]i and [Zn2+]i. We trialed a panel of 12 probes including fura-2, FluoZin-3, Leadmium Green, Rhod-5N, indo-1, Fluo-5N, and others. We found that the [Zn2+]i probe FluoZin-3 and the traditional [Ca2+]i probe fura-2 responded most consistently and robustly to [Cd2+]i accumulation mediated by voltage-gated calcium channels. While selective detection of [Cd2+]i by fura-2 required the omission of Ca2+ from extracellular buffers, FluoZin-3 responded to [Cd2+]i similarly in the presence or absence of extracellular Ca2+. Furthermore, we showed that FluoZin-3 and fura-2 can be used together for simultaneous monitoring of [Ca2+]i and [Cd2+]i in the same cells. None of the other fluorophores tested were effective [Cd2+]i detectors in this model.
Assuntos
Cádmio/análise , Corantes Fluorescentes/análise , Fura-2/análise , Células Secretoras de Insulina/química , Células Secretoras de Insulina/metabolismo , Compostos Policíclicos/análise , Animais , Cádmio/metabolismo , Linhagem Celular , Corantes Fluorescentes/química , Fura-2/química , Espectrometria de Massas , Camundongos , Microscopia de Fluorescência , Compostos Policíclicos/químicaRESUMO
Cadmium (Cd) is a nephrotoxic environmental pollutant that causes insidious injury to the proximal tubule that results in severe polyuria and proteinuria. Cystatin C is a low molecular weight protein that is being evaluated as a serum and urinary biomarker for various types of ischemic and nephrotoxic renal injury. The objective of the present study was to determine if cystatin C might be a useful early biomarker of Cd nephrotoxicity. Male Sprague-Dawley rats were given daily injections of Cd for up to 12 weeks. At 3, 6, 9 and 12 weeks, urine samples were analyzed for cystatin C, protein, creatinine, ß2 microglobulin and kidney injury molecule-1. The results showed that Cd caused a significant increase in the urinary excretion of cystatin C that occurred 3-4 weeks before the onset of polyuria and proteinuria. Serum levels of cystatin C were not altered by Cd. Immunolabeling studies showed that Cd caused the relocalization of cystatin C from the cytoplasm to the apical surface of the epithelial cells of the proximal tubule. The Cd-induced changes in cystatin C labelling paralleled those of the brush border transport protein, megalin, which has been implicated as a mediator of cystatin C uptake in the proximal tubule. These results indicate that Cd increases the urinary excretion of cystatin C, and they suggest that this effect may involve disruption of megalin-mediated uptake of cystatin C by epithelial cells of the proximal tubule.
Assuntos
Biomarcadores/urina , Cádmio/toxicidade , Cistatina C/urina , Túbulos Renais Proximais/metabolismo , Animais , Biomarcadores/sangue , Cádmio/administração & dosagem , Moléculas de Adesão Celular/sangue , Creatinina/sangue , Cistatina C/sangue , Poluentes Ambientais , Humanos , Túbulos Renais Proximais/lesões , Túbulos Renais Proximais/patologia , Masculino , RatosRESUMO
Nanoparticles (NP) are pervasive in many areas of modern life, with little known about their potential toxicities. One commercially important NP is cadmium oxide (CdO), which is used to synthesize other Cd-containing NP, such as quantum dots. Cadmium (Cd) is a well-known nephrotoxicant, but the nephrotoxic potential of CdO NP remains unknown, particularly when exposure occurs during pregnancy. Therefore, pregnant CD-1 mice were used to examine the effects of inhaled CdO NP (230 µg CdO NP/m(3)) on maternal and neonatal renal function by examining urinary creatinine and urinary biomarkers of kidney injury, including kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL). Inhalation of CdO NP by dams produced a fivefold increase in urinary Kim-1 with no marked effect on urinary creatinine levels. Kim-1 mRNA expression peaked by gestational day (GD) 10.5, and NGAL expression increased from GD 10.5 to 17.5. In addition, histological analyses revealed proximal tubular pathology at GD 10.5. Neonatal Kim-1 mRNA expression rose between postnatal days (PND) 7 and 14, with mammary glands/milk being the apparent source of Cd for offspring. These studies demonstrate that, similar to what is seen with other Cd forms, Cd associated with inhaled CdO NP results in renal injury to both directly exposed dam and offspring. As commercial uses for nanotechnology continue to expand throughout the world, risks for unintentional exposure in the workplace increase. Given the large number of women in the industrial workforce, care needs to be taken to protect these already vulnerable populations.
Assuntos
Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/congênito , Compostos de Cádmio/toxicidade , Nanopartículas/toxicidade , Óxidos/toxicidade , Injúria Renal Aguda/patologia , Proteínas de Fase Aguda/biossíntese , Proteínas de Fase Aguda/genética , Animais , Animais Recém-Nascidos , Biomarcadores/urina , Compostos de Cádmio/farmacocinética , Creatinina/urina , Feminino , Glicosúria/induzido quimicamente , Glicosúria/urina , Receptor Celular 1 do Vírus da Hepatite A , Exposição por Inalação , Rim/patologia , Lipocalina-2 , Lipocalinas/biossíntese , Lipocalinas/genética , Glândulas Mamárias Animais/metabolismo , Exposição Materna , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Camundongos , Proteínas Oncogênicas/biossíntese , Proteínas Oncogênicas/genética , Óxidos/farmacocinética , Gravidez , RNA Mensageiro/biossínteseRESUMO
The E-cadherin/ß-catenin complex is a structural component of adherens-type junctions in epithelial cells. Moreover, ß-catenin acts as an intracellular signaling molecule that can influence the expression of a variety of genes that regulate apoptosis and cell cycle control. Cadmium (Cd) is an environmental toxicant that causes renal dysfunction and disrupts cadherin-dependent cell-cell adhesion in various types of epithelial cells. In this study, we examined the effects of Cd on the subcellular localization of ß-catenin, the cadherin/ß-catenin complex and ß-catenin-mediated gene transcription in rat proximal tubule NRK-52E cells. Exposure to 5-10 µM Cd for 4 h caused the NRK cells to separate from each other without killing the cells or causing them to detach from the growing surface. This effect was associated with the loss of ß-catenin and E-cadherin from the cell-cell contacts and apparent changes in the accumulation of ß-catenin in the nuclear cell subfraction. The expression of the ß-catenin-sensitive gene, c-jun was significantly increased in cells exposed to 5 µM Cd. However, there was no change in the expression of several other ß-catenin-regulated genes including: c-myc, cyclin D1 and matrilysin. Additional studies utilizing the TOPFLASH ß-catenin reporter gene construct showed that Cd caused a 2-3 fold increase in the expression of the luciferase reporter gene. Overall, these results indicate that Cd disrupts the cadherin/ß-catenin complex in NRK-52E cells, but this effect leads to only partial activation of ß-catenin-mediated gene transcription.
Assuntos
Cloreto de Cádmio/toxicidade , Poluentes Ambientais/toxicidade , beta Catenina/metabolismo , Animais , Caderinas/genética , Caderinas/metabolismo , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Rim/citologia , Lítio/farmacologia , Transporte Proteico/efeitos dos fármacos , Ratos , Ativação Transcricional/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , beta Catenina/genéticaRESUMO
Cadmium is an important industrial agent and environmental pollutant that is a major cause of kidney disease. With chronic exposure, cadmium accumulates in the epithelial cells of the proximal tubule, resulting in a generalized reabsorptive dysfunction characterized by polyuria and low-molecular-weight proteinuria. The traditional view has been that as cadmium accumulates in proximal tubule cells, it produces a variety of relatively nonspecific toxic effects that result in the death of renal epithelial cells through necrotic or apoptotic mechanisms. However, a growing volume of evidence suggests that rather than merely being a consequence of cell death, the early stages of cadmium-induced proximal tubule injury may involve much more specific changes in cell-cell adhesion, cellular signaling pathways, and autophagic responses that occur well before the onset of necrosis or apoptosis. In this commentary, we summarize these recent findings, and we offer our own perspectives as to how they relate to the toxic actions of cadmium in the kidney. In addition, we highlight recent findings, suggesting that it may be possible to detect the early stages of cadmium toxicity through the use of improved biomarkers. Finally, some of the therapeutic implications of these findings will be considered. Because cadmium is, in many respects, a model cumulative nephrotoxicant, these insights may have broader implications regarding the general mechanisms through which a variety of drugs and toxic chemicals damage the kidney.
Assuntos
Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/metabolismo , Intoxicação por Cádmio/metabolismo , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/metabolismo , Injúria Renal Aguda/patologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Biomarcadores/metabolismo , Cádmio/metabolismo , Intoxicação por Cádmio/patologia , Adesão Celular/efeitos dos fármacos , Adesão Celular/fisiologia , Poluentes Ambientais/toxicidade , Humanos , Túbulos Renais Proximais/patologiaRESUMO
As the risks of cadmium (Cd)-induced kidney disease have become increasingly apparent, much attention has been focused on the development and use of sensitive biomarkers of Cd nephrotoxicity. The purpose of this review is to briefly summarize the current state of Cd biomarker research. The review includes overviews of the toxicokinetics of Cd, the mechanisms of Cd-induced proximal tubule injury, and mechanistic summaries of some of the biomarkers (N-acetyl-ß-D-glucosamidase; ß(2)-microglubulin, metallothionein, etc.) that have been most widely used in monitoring of human populations for Cd exposure and nephrotoxicity. In addition, several novel biomarkers (kidney injury molecule-1, α-glutathione-S-transferase and insulin) that offer the potential for improved biomonitoring of Cd-exposed populations are discussed.
Assuntos
Biomarcadores/metabolismo , Cádmio/toxicidade , Rim/efeitos dos fármacos , Cádmio/administração & dosagem , Cádmio/farmacocinética , Exposição Ambiental , Saúde Ambiental , Monitoramento Ambiental , Humanos , Rim/lesões , Rim/fisiopatologia , Metalotioneína/metabolismo , Modelos Biológicos , Distribuição TecidualRESUMO
Kratom (Mitragyna speciosa, Korth) is a tree-like plant that is indigenous to Southeast Asia. Kratom leaf products have been used in traditional folk medicine for their unique combination of stimulant and opioid-like effects. Kratom is being increasingly used in the West for its reputed benefits in the treatment of pain, depression and opioid use disorder. Recently, the United States Food and Drug Administration and Centers for Disease Control have raised concerns regarding the contamination of some kratom products with toxic metals (Pb and Ni) and microbes such as Salmonella. To further explore this issue, eight different kratom products were legally purchased from various "head"/"smoke" shops in the Western Suburbs of Chicago and then tested for microbial burden, a panel of metals (Ni, Pb, Cr, As, Hg, Cd), and levels of the main psychoactive alkaloid mitragynine. All of the samples contained significant, but variable, levels of mitragynine (3.9-62.1 mg/g), indicating that the products were, in fact, derived from kratom. All but two of the samples tested positive for the presence of various microbes including bacteria and fungi. However, none of the samples tested positive for Salmonella. Seven products showed significant levels of Ni (0.73-7.4 µg/g), Pb (0.16-1.6 µg/g) and Cr (0.21-5.7 µg/g) while the other product was negative for metals. These data indicate that many kratom products contain variable levels of mitragynine and can contain significant levels of toxic metals and microbes. These findings highlight the need for more stringent standards for the production and sale of kratom products.
Assuntos
Mitragyna , Alcaloides de Triptamina e Secologanina , Chicago , Metais/análise , Mitragyna/química , Folhas de Planta , Alcaloides de Triptamina e Secologanina/análise , Estados UnidosRESUMO
Kidney injury molecule-1 (Kim-1) has been qualified by the Food and Drug Administration and European Medicines Agency as a highly sensitive and specific urinary biomarker to monitor drug-induced kidney injury in preclinical studies and on a case-by-case basis in clinical trials. Here we report the development and evaluation of a rapid direct immunochromatographic lateral flow 15-min assay for detection of urinary Kim-1 (rat) or KIM-1 (human). The urinary Kim-1 band intensity using the rat Kim-1 dipstick significantly correlated with levels of Kim-1 as measured by a microbead-based assay, histopathological damage, and immunohistochemical assessment of renal Kim-1 in a dose- and time-dependent manner. Kim-1 was detected following kidney injury induced in rats by cadmium, gentamicin, or bilateral renal ischemia/reperfusion. In humans, the urinary KIM-1 band intensity was significantly greater in urine from patients with acute kidney injury than in urine from healthy volunteers. The KIM-1 dipstick also enabled temporal evaluation of kidney injury and recovery in two patients who developed postoperative acute kidney injury following cytoreductive surgery for malignant mesothelioma with intraoperative local cisplatin administration. We hope that future, more extensive studies will confirm the utility of these results, which show that the Kim-1/KIM-1 dipsticks can provide a sensitive and accurate detection of Kim-1/KIM-1, thereby providing a rapid diagnostic assay for kidney damage and facilitating the rapid and early detection of kidney injury in preclinical and clinical studies.
Assuntos
Moléculas de Adesão Celular/urina , Nefropatias/diagnóstico , Nefropatias/urina , Rim/química , Glicoproteínas de Membrana/urina , Animais , Bioensaio , Biomarcadores/urina , Cádmio/efeitos adversos , Estudos de Casos e Controles , Cisplatino/efeitos adversos , Estudos Transversais , Diagnóstico Precoce , Receptor Celular 1 do Vírus da Hepatite A , Humanos , Imuno-Histoquímica , Rim/patologia , Masculino , Ratos , Ratos Sprague-Dawley , Receptores Virais , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/urina , Sensibilidade e Especificidade , Fatores de Tempo , UrináliseRESUMO
Recent epidemiological studies suggest a positive association between exposure to the environmental pollutant cadmium (Cd) and the incidence and severity of diabetes. In this review, we examine the literature suggesting a relationship between Cd exposure, elevated blood glucose levels, and the development of diabetes. In addition we review human and animal studies indicating that Cd potentiates or exacerbates diabetic nephropathy. We also review the various possible cellular mechanisms by which Cd may alter blood glucose levels. In addition, we present some novel findings from our own laboratories showing that Cd elevates fasting blood glucose levels in an animal model of subchronic Cd exposure before overt signs of renal dysfunction are evident. These studies also show that Cd reduces insulin levels and has direct cytotoxic effects on the pancreas. Together, these findings indicate that Cd may be a factor in the development of some types of diabetes and they raise the possibility that Cd and diabetes-related hyperglycemia may act synergistically to damage the kidney.
Assuntos
Cádmio/toxicidade , Diabetes Mellitus/induzido quimicamente , Nefropatias Diabéticas/etiologia , Poluentes Ambientais/toxicidade , Pâncreas/efeitos dos fármacos , Animais , Glicemia/efeitos dos fármacos , Doença Crônica , Diabetes Mellitus/epidemiologia , Diabetes Mellitus/metabolismo , Nefropatias Diabéticas/induzido quimicamente , Nefropatias Diabéticas/epidemiologia , Nefropatias Diabéticas/metabolismo , Humanos , Insulina/sangue , Modelos Animais , Pâncreas/metabolismo , Pâncreas/patologia , Medição de Risco , Fatores de RiscoRESUMO
As a result of the widespread use of Cd in industry and its extensive dissemination in the environment, there has been considerable interest in the identification of early biomarkers of Cd-induced kidney injury. Kim-1 is a transmembrane glycoprotein that is not detectable in normal kidney, but is up-regulated and shed into the urine following ischemic or nephrotoxic injury. Recent studies utilizing a sub-chronic model of Cd exposure in the rat have shown that Kim-1 is an early urinary marker of Cd-induced kidney injury. Kim-1 was detected in the urine 4-5 weeks before the onset of proteinuria and 1-3 weeks before the appearance of urinary metallothionein and Clara cell protein 16, which are standard markers of Cd nephrotoxicity. In the present study, we have compared the time course for the appearance of Kim-1 in the urine with the time course for the appearance of alpha glutathione-S-transferase (alpha-GST), N-acetyl-beta-D-glucose amidase (NAG) and Cd, each of which have been used or proposed as urinary markers of Cd nephrotoxicity. Adult male Sprague-Dawley rats were given daily subcutaneous injections of 0.6 mg (5.36 micromoles)/kg Cd, 5 days per week for up to 12 weeks. One day each week, 24 h urine samples were collected and analyzed for protein, creatinine and the various markers. The results showed that significant levels of Kim-1 appeared in the urine as early as 6 weeks into the treatment protocol and then continued to rise for the remainder of the 12 week treatment period. By contrast, significant levels of alpha-GST and NAG did not appear in the urine until 8 and 12 weeks, respectively, while proteinuria was not evident until 10 weeks. The urinary excretion of Cd was below the level of detection until week 4 and then showed a slow, linear increase over the next 6 weeks before increasing markedly between weeks 10 and 12. These results provide additional evidence that Kim-1 is a sensitive biomarker of the early stages of Cd-induced proximal tubule injury.
Assuntos
Acetilglucosaminidase/urina , Cádmio/toxicidade , Moléculas de Adesão Celular/urina , Poluentes Ambientais/toxicidade , Glutationa Transferase/urina , Isoenzimas/urina , Proteinúria/diagnóstico , Animais , Biomarcadores/urina , Cádmio/urina , Diagnóstico Precoce , Poluentes Ambientais/urina , Masculino , Valor Preditivo dos Testes , Proteinúria/induzido quimicamente , Proteinúria/urina , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , Regulação para CimaRESUMO
Cadmium (Cd) is a nephrotoxic industrial and environmental pollutant that causes a generalized dysfunction of the proximal tubule. Kim-1 is a transmembrane glycoprotein that is normally not detectable in non-injured kidney, but is up-regulated and shed into the urine during the early stages of Cd-induced proximal tubule injury. The objective of the present study was to examine the relationship between the Cd-induced increase in Kim-1 expression and the onset of necrotic and apoptotic cell death in the proximal tubule. Adult male Sprague-Dawley rats were treated with 0.6 mg (5.36 micromol) Cd/kg, subcutaneously, 5 days per week for up to 12 weeks. Urine samples were analyzed for levels of Kim-1 and the enzymatic markers of cell death, lactate dehydrogenase (LDH) and alpha-glutathione-S-transferase (alpha-GST). In addition, necrotic cells were specifically labeled by perfusing the kidneys in situ with ethidium homodimer using a procedure that has been recently developed and validated in the Prozialeck laboratory. Cryosections of the kidneys were also processed for the immunofluorescent visualization of Kim-1 and the identification of apoptotic cells by TUNEL labeling. Results showed that significant levels of Kim-1 began to appear in the urine after 6 weeks of Cd treatment, whereas the levels of total protein, alpha-GST and LDH were not increased until 8-12 weeks. Results of immunofluorescence labeling studies showed that after 6 weeks and 12 weeks, Kim-1 was expressed in the epithelial cells of the proximal tubule, but that there was no increase in the number of necrotic cells, and only a modest increase in the number of apoptotic cells at 12 weeks. These results indicate that the Cd-induced increase in Kim-1 expression occurs before the onset of necrosis and at a point where there is only a modest level of apoptosis in the proximal tubule.
Assuntos
Apoptose/efeitos dos fármacos , Cloreto de Cádmio/toxicidade , Moléculas de Adesão Celular/urina , Poluentes Ambientais/toxicidade , Túbulos Renais Proximais/efeitos dos fármacos , Animais , Biomarcadores/urina , Cloreto de Cádmio/metabolismo , Poluentes Ambientais/metabolismo , Glutationa Transferase/urina , Isoenzimas/urina , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , L-Lactato Desidrogenase/urina , Masculino , Necrose , Ratos , Ratos Sprague-Dawley , Índice de Gravidade de Doença , Fatores de Tempo , Regulação para CimaRESUMO
Cadmium (Cd) is an environmental toxicant that accumulates in bone and alters bone turnover and metabolism. Periodontal disease is characterized by tooth loss and tissue destruction, specifically, loss of supporting bone around the teeth. We have previously shown that Cd causes loss of dental alveolar (tooth supporting) bone in a rodent model of long-term Cd poisoning. The overall goal of this study was to determine the possible association between levels of Cd in alveolar bone and evidence of periodontal disease in human cadavers. The extent of Cd accumulation in human mandible samples was analyzed. Levels of Cd in mandibular alveolar bone were compared to those in basal bone as well as the renal cortex in samples obtained from the cadavers. Alveolar bone contained significantly higher levels of Cd when compared to basal bone (p < 0.01). Cd levels in mandibular bone were significantly higher in female compared to male cadavers (p < 0.05). The kidney cortex had greater than 15-fold higher Cd levels compared to mandible bone. Additional analyses showed a possible association between levels of Cd in basal bone and the presence of periodontal disease in cadavers from which the samples were obtained. This study shows that Cd accumulates to relatively high levels within alveolar bone as compared to basal bone in the mandible and thus may have a significant and direct effect in the progression of changes in bone associated with periodontal disease.
RESUMO
Cadmium is a toxic metal and common environmental contaminant. Chronic cadmium exposure results in kidney, bone, reproductive, and immune toxicity as well as cancer. Cadmium induces splenomegaly and affects the adaptive immune system, but specific effects vary depending on the dose, model, and endpoint. This study investigates the effects of subchronic, oral, and low-dose cadmium exposure (32 ppm cadmium chloride in drinking water for 10 weeks) on the rat immune system, focusing on T cell function. Cadmium-exposed animals demonstrated slight increases in the spleen-to-body weight ratios, and decreases in overall splenic cell numbers and markers of oxidative stress. The relative ratios of splenic cell populations remained similar, except for modest increases in regulatory T cells in the cadmium-exposed animals. Cadmium exposure also significantly increased the production of IFNγ, a pro-inflammatory cytokine, and IL-10, a cytokine produced by multiple T cell subsets that typically inhibits IFNγ expression, by activated T cells. The increase in IFNγ and IL-10 suggests that cadmium exposure may affect multiple T cell subsets. Collectively, this study suggests that subchronic, low-dose cadmium exposure impacts both immune cell function and cellularity, and may enhance inflammatory responses.
RESUMO
Cell adhesion molecules are integral cell-membrane proteins that maintain cell-cell and cell-substrate adhesion and in some cases act as regulators of intracellular signaling cascades. In the kidney, cell adhesion molecules, such as the cadherins, the catenins, the zonula occludens protein-1 (ZO-1), occludin and the claudins are essential for maintaining the epithelial polarity and barrier integrity that are necessary for the normal absorption/excretion of fluid and solutes. A growing volume of evidence indicates that these cell adhesion molecules are important early targets for a variety of nephrotoxic substances including metals, drugs, and venom components. In addition, it is now widely appreciated that molecules, such as intracellular adhesion molecule-1 (ICAM-1), integrins, and selectins play important roles in the recruitment of leukocytes and inflammatory responses that are associated with nephrotoxic injury. This review summarizes the results of recent in vitro and in vivo studies indicating that these cell adhesion molecules may be primary molecular targets in many types of chemically-induced renal injury. Some of the specific agents that are discussed include cadmium (Cd), mercury (Hg), bismuth (Bi), cisplatin, aminoglycoside antibiotics, S-(1,2-dichlorovinyl)-l-cysteine (DCVC), and various venom toxins. This review also includes a discussion of the various mechanisms, by which these substances can affect cell adhesion molecules in the kidney.
Assuntos
Moléculas de Adesão Celular/fisiologia , Nefropatias/induzido quimicamente , Nefropatias/fisiopatologia , Animais , Carcinógenos/toxicidade , Junções Comunicantes/fisiologia , Humanos , Glomérulos Renais/fisiologia , Túbulos Renais/fisiologia , Xenobióticos/toxicidadeRESUMO
The One Health Initiative focuses on the complex relationships among the health of humans, animals, plants, microbes, and the environment. There are dynamic and delicate balances among these various elements, and disruption of these elements can have adverse effects on human health. Over the past 5 years, the Department of Pharmacology at the Midwestern University/Chicago College of Osteopathic Medicine has used the One Health Initiative as a framework for the growth and development of ongoing research programs in the area of environmental toxicology. As described in this article, this One Health approach has been successful, as evidenced by increases in the number of publications and level of grant-seeking activity by department faculty. With its emphasis on holistic patient care, the osteopathic medical profession is well positioned to be a leading advocate for the One Health Initiative.
Assuntos
Ecotoxicologia , Saúde Única , Medicina Osteopática/educação , Farmacologia , Pesquisa/organização & administração , Chicago , Humanos , Avaliação de Programas e Projetos de SaúdeRESUMO
Cadmium (Cd) is an environmental contaminant that damages the kidney, the liver, and bones. Some epidemiological studies showed associations between Cd exposure and periodontal disease. The purpose of this study was to examine the relationship between Cd exposure and periodontal disease in experimental animals. Male Sprague/Dawley rats were given daily subcutaneous injections of Cd (0.6 mg/kg/day) for up to 12 weeks. The animals were euthanized, and their mandibles and maxillae were evaluated for levels of periodontal bone by measuring the distance from the cementoenamel junction (CEJ) to the alveolar bone crest (ABC) of the molar roots. After 12 weeks of Cd exposure in animals, there was a significantly greater distance between the CEJ and ABC in the palatal aspect of the maxillary molars and the lingual aspect of the mandibular molars when compared with controls (p < 0.0001). This study shows that Cd has significant, time-dependent effects on periodontal bone in an animal model of Cd exposure. These findings support the possibility of Cd being a contributing factor to the development of periodontal disease in humans.
RESUMO
Cadmium (Cd) is a nephrotoxic environmental pollutant that causes a generalized dysfunction of the proximal tubule characterized by polyuria and proteinuria. Even though the effects of Cd on the kidney have been well-characterized, the molecular mechanisms underlying these effects have not been fully elucidated. MicroRNAs (miRNAs) are small non-coding RNAs that regulate cellular and physiologic function by modulating gene expression at the post-transcriptional level. The goal of the present study was to determine if Cd affects renal cortex miRNA expression in a well-established animal model of Cd-induced kidney injury. Male Sprague-Dawley rats were treated with subcutaneous injections of either isotonic saline or CdCl2 (0.6 mg/kg) 5 days a week for 12 weeks. The 12-week Cd-treatment protocol resulted in kidney injury as determined by the development of polyuria and proteinuria, and a significant increase in the urinary biomarkers Kim-1, ß2 microglobulin and cystatin C. Total RNA was isolated from the renal cortex of the saline control and Cd treated animals, and differentially expressed miRNAs were identified using µParafloTM microRNA microarray analysis. The microarray results demonstrated that the expression of 44 miRNAs were significantly increased and 54 miRNAs were significantly decreased in the Cd treatment group versus the saline control (t-test, p ≤ 0.05, N = 6 per group). miR-21-5p, miR-34a-5p, miR-146b-5p, miR-149-3p, miR-224-5p, miR-451-5p, miR-1949, miR-3084a-3p, and miR-3084c-3p demonstrated more abundant expression and a significant two-fold or greater increased expression in the Cd-treatment group versus the saline control group. miR-193b-3p, miR-455-3p, and miR-342-3p demonstrated more abundant expression and a significant two-fold or greater decreased expression in the Cd-treatment group versus the saline control group. Real-time PCR validation demonstrated (1) a significant (t-test, p ≤ 0.05, N = 6 per group) increase in expression in the Cd-treated group for miR-21-5p (2.7-fold), miR-34a-5p (10.8-fold), miR-146b-5p (2-fold), miR-224-5p (10.2-fold), miR-3084a-3p (2.4-fold), and miR-3084c-3p (3.3-fold) and (2) a significant (t-test, p ≤ 0.05, N = 6 per group) 52% decrease in miR-455-3p expression in the Cd-treatment group. These findings demonstrate that Cd significantly alters the miRNA expression profile in the renal cortex and raises the possibility that dysregulated miRNA expression may play a role in the pathophysiology of Cd-induced kidney injury. In addition, these findings raise the possibility that Cd-dysregulated miRNAs might be used as urinary biomarkers of Cd exposure or Cd-induced kidney injury.
RESUMO
BACKGROUND: Ethidium homodimer is a cell-membrane impermeant nuclear fluorochrome that has been widely used to identify necrotic cells in culture. Here, we describe a novel technique for evaluating necrosis of epithelial cells in the proximal tubule that involves perfusing ethidium homodimer through the intact rat kidney. As a positive control for inducing necrosis, rats were treated with 3.5, 1.75, 0.87 and 0.43 mg/kg mercuric chloride (Hg2+, intraperitoneal), treatments which have previously been shown to rapidly cause dose-dependent necrosis of the proximal tubule. Twenty-four h after the administration of Hg2+, ethidium homodimer (5 microM) was perfused through the intact left kidney while the animal was anesthetized. The kidney was then removed, placed in embedding medium, frozen and cryosectioned at a thickness of 5 microm. Sections were permeabilized with -20 degrees C methanol and then stained with 4',6-diamidino-2-phenylindole (DAPI) to label total nuclei. Total cell number was determined from the DAPI staining in random microscopic fields and the number of necrotic cells in the same field was determined by ethidium homodimer labeling. RESULTS: The Hg2+-treated animals showed a dose-dependent increase in the number of ethidium labeled cells in the proximal tubule, but not in other segments of the nephron. Other results showed that a nephrotoxic dose of gentamicin also caused a significant increase in the number of ethidium labeled cells in the proximal tubule. CONCLUSION: These results indicate that this simple and sensitive perfusion technique can be used to evaluate cellular necrosis in the proximal tubule with the three-dimensional cyto-architecture intact.