Tungsten toxicity on kidney tubular epithelial cells induces renal inflammation and M1-macrophage polarization.

Tungsten is widely used in medical, industrial, and military applications. The environmental exposure to tungsten has increased over the past several years, and few studies have addressed its potential toxicity. In this study, we evaluated the effects of chronic oral tungsten exposure (100 ppm) on renal inflammation in male mice. We found that 30- or 90-day tungsten exposure led to the accumulation of LAMP1-positive lysosomes in renal tubular epithelial cells. In addition, the kidneys of mice exposed to tungsten showed interstitial infiltration of leukocytes, myeloid cells, and macrophages together with increased levels of proinflammatory cytokines and p50/p65-NFkB subunits. In proximal tubule epithelial cells (HK-2) in vitro, tungsten induced a similar inflammatory status characterized by increased mRNA levels of CSF1, IL34, CXCL2, and CXCL10 and NFkB activation. Moreover, tungsten exposure reduced HK-2 cell viability and enhanced reactive oxygen species generation. Conditioned media from HK-2 cells treated with tungsten induced an M1-proinflammatory polarization of RAW macrophages as evidenced by increased levels of iNOS and interleukin-6 and decreased levels of the M2-antiinflammatory marker CD206. These effects were not observed when RAW cells were exposed to conditioned media from HK-2 cells treated with tungsten and supplemented with the antioxidant N-acetylcysteine (NAC). Similarly, direct tungsten exposure induced M1-proinflammatory polarization of RAW cells that was prevented by NAC co-treatment. Altogether, our data suggest that prolonged tungsten exposure leads to oxidative injury in the kidney ultimately leading to chronic renal inflammation characterized by a proinflammatory status in kidney tubular epithelial cells and immune cell infiltration.

Subchronic oral exposure of tungsten induces myofibroblast transformation and various markers of kidney fibrosis.

Tungsten is a naturally occurring transition element used in a broad range of applications. As a result of its extensive use, we are increasingly exposed to tungsten from our environment, including potable water, since tungsten can become bioaccessible in ground sources. The kidneys are particularly susceptible to tungsten exposure as this is the main site for tungsten excretion. In this study, we investigated the prolonged effects of tungsten on the kidneys and how this may impact injury and function. When mice were exposed to tungsten in their drinking water for 1 mo, kidney function had not significantly changed. Following 3-mo exposure, mice were presented with deterioration in kidney function as determined by serum and urine creatinine levels. During 3 mo of tungsten exposure, murine kidneys demonstrated significant increases in the myofibroblast marker α-smooth muscle actin (αSMA) and extracellular matrix products: fibronectin, collagen, and matricellular proteins. In addition, Masson's trichrome and hematoxylin-eosin (H&E) staining revealed an increase in fibrotic tissue and vacuolization of tubular epithelial cells, respectively, from kidneys of tungsten-treated mice, indicative of renal injury. In vitro treatment of kidney fibroblasts with tungsten led to increased proliferation and upregulation of transforming growth factor ß1 (TGFß1), which was consistent with the appearance of fibroblast-to-myofibroblast transition (FMT) markers. Our data suggest that continuous exposure to tungsten impairs kidney function that may lead to the development of chronic kidney disease (CKD).

Prospective study of the changes in pharmacokinetics of immunosuppressive medications after laparoscopic sleeve gastrectomy.

Laparoscopic sleeve gastrectomy induces weight loss via the creation of a restrictive gastric tube for early satiety and is associated with an accelerated gastric transit time. A prospective, single-dose pharmacokinetic study was performed, prior to and after laparoscopic sleeve gastrectomy, for tacrolimus, extended-release tacrolimus, mycophenolate mofetil, and enteric-coated mycophenolate sodium. The study included 12 morbidly obese patients in chronic renal failure. The median decrease in body mass index was 8.8 kg/m2 with an excess body weight loss of 54.9%. The AUC24 of all drugs were increased after laparoscopic sleeve gastrectomy by 46%, 55%, 77%, and 74%, respectively. The maximum concentrations were increased for tacrolimus, extended-release tacrolimus, and mycophenolate mofetil by 43%, 46%, and 65%. The apparent total clearances were decreased for tacrolimus, mycophenolate mofetil, and enteric-coated mycophenolate sodium by 36%, 57%, and 38%. Laparoscopic sleeve gastrectomy can be associated with significant changes in pharmacokinetics of the drugs evaluated. The mechanism is likely decreased apparent drug clearance due to an increased drug exposure (from a more distal site of intestinal absorption with decreased intestinal metabolism), or decreased clearance (liver metabolism). Adapting the monitoring of immunosuppression will be important to avoid overdosing and potential side effects.

Pharmacodynamics of 250 mg and 500 mg oral furosemide in peritoneal dialysis
.

Residual renal function and diuresis preservation are associated with improved volume control and lower mortality in peritoneal dialysis (PD). Loop diuretics are used to maintain diuresis, although their optimal dosage remains unclear. This study aimed to compare the pharmacodynamics of a 250-mg and a 500-mg dose of oral furosemide in PD patients. 12 patients with a diuresis > 100 mL per day were randomized in a crossover pattern to successively receive an oral dose of 250 mg and 500 mg of furosemide. Twelve-hour natriuresis and diuresis were measured before and after each furosemide dose. Fractional excretion of sodium (FENa) and absolute sodium excretion increased after each dose, although these rises were not statistically significantly different (5.8% (250 mg) vs. 6.9% (500 mg), p = 0.57 for FENa and 42.6 mmol/12h (250 mg) vs. 70.8 mmol/12h (500 mg), p = 0.07 for absolute sodium excretion). Urinary volume was significantly increased after the 500-mg dose, whilst the difference did not reach statistical significance after the 250-mg dose. Furthermore, the higher dose was associated with a greater increase in diuresis than the lower dose (226 mL (250 mg) vs. 522 mL (500 mg), p = 0.04). Furosemide could be used at oral single doses reaching 500 mg in PD patients requiring greater volume control.

Impact of Arteriovenous fistula creation on estimated glomerular filtration rate decline in Predialysis patients.

BACKGROUND: Arteriovenous fistula (AVF) is the vascular access of choice for patients on hemodialysis. Recent evidence suggests that AVF creation may slow estimated glomerular filtration rate (eGFR) decline. The study objective was to assess the impact of the AVF creation on eGFR decline, after controlling for key confounding factors. METHODS: This retrospective cohort study included adult patients followed in a single-center predialysis clinic between 1999 and 2016. Patients with a patent AVF were followed up to 2 years pre- and post-AVF creation. Estimated GFR trajectory was reported using linear mixed models adjusted for demographic characteristics, comorbidities and use of renin-angiotensin-aldosterone blockade. RESULTS: A total of 146 patients were studied with a median age 68.7 (60.5-75.4) years and a median eGFR at time of AVF creation of 12.8 (11.3-13.9) mL/min/1.73m2. The crude annual eGFR decline rates were - 3.60 ± 4.00 mL/min/1.73 m2 pre- and - 2.28 ± 3.56 mL/min/1.73 m2 post-AVF, resulting in a mean difference of 1.28 mL/min/1.73 m2 (95% CI 0.49, 2.07). In a mixed effect linear regression model, monthly eGFR decline was - 0.63 (95% CI -0.81, - 0.46; p <  0.001) mL/min/1.73m2/month. The period after AVF creation was associated with a relatively higher eGFR (ß 0.94, 95% CI 0.61-1.26, p <  0.001). There was a significant association between follow-up time and the period pre/post AVF (ß 0.19, 95% CI 0.16, 0.22; p <  0.001) such that eGFR decline was more attenuated each month after AVF creation. CONCLUSIONS: In this cohort, AVF creation was associated with a significant reduction of eGFR decline. Further prospective studies are needed to confirm this association.

Effects of Chronic Renal Failure on Brain Cytochrome P450 in Rats.

Chronic renal failure (CRF) impedes renal excretion of drugs and their metabolism by reducing the expression of liver cytochrome P450 (P450). Uremic serum contains factors, such as parathyroid hormone (PTH), that decrease liver P450s. The P450s are also involved in the metabolism of xenobiotics in the brain. This study investigates: 1) the effects of CRF on rat brain P450, 2) the role of PTH in the downregulation of brain P450s in CRF rats, and 3) the effects of PTH on P450s in astrocytes. Protein and mRNA expression of P450s were assessed in the brain of CRF and control (CTL) rats, as well as from CTL or CRF rats that underwent parathyroidectomy (PTX) 1 week before nephrectomy. CYP3A activity was measured using 3-[(3, 4-difluorobenzyl) oxy]-5, 5-dimethyl-4-[4-methylsulfonyl) phenyl] furan-2(5H)-1 metabolism in brain microsomal preparation. CYP3A protein expression was assessed in primary cultured astrocytes incubated with serum obtained from CRF or CTL rats or with PTH. Significant downregulations (≥40%) of CYP1A, CYP2C11, and CYP3A proteins were observed in microsomes from CRF rat brains. CYP3A activity reduction was also observed. CYP3A expression and activity were unaffected in PTX-pretreated CRF rats. Serum of PTX-treated CRF rats had no impact on CYP3A levels in astrocytes compared with that of untreated CRF rats. Finally, PTH addition to normal calf serum induced a reduction in CYP3A protein similar to CRF serum, suggesting that CRF-induced hyperparathyroidism is associated with a significant decrease in P450 drug-metabolizing enzymes in the brain, which may have implications in drug response.

Effects of renal impairment on the pharmacokinetics of orally administered deferiprone.

AIMS: In light of the growing recognition of renal disease in thalassemia, it is important to understand the impact of renal impairment on the pharmacokinetics of iron chelators. This study evaluated the pharmacokinetics and safety of the iron chelator deferiprone (DFP) in subjects with renal impairment in comparison with healthy volunteers (HVs). METHODS: Thirty-two subjects were categorized into four groups based on degree of renal impairment: none, mild, moderate or severe, as determined by estimated glomerular filtration rate (eGFR). All subjects received a single oral dose of 33 mg kg(-1) DFP, provided serum and urine samples for pharmacokinetic assessment over 24 h and were monitored for safety. RESULTS: Renal clearance of DFP decreased as renal impairment increased. However, based on Cmax , AUC(0,t) and AUC(0,∞), there were no significant group differences in systemic exposure, because less than 4% of the drug was excreted unchanged in the urine. DFP is extensively metabolized to a renally excreted, pharmacologically inactive metabolite, deferiprone 3-O-glucuronide (DFP-G), which exhibited higher Cmax , AUC(0,t), AUC(0,∞) and longer tmax and t1/2 in the renally impaired groups compared with HVs. The Cmax and AUCs of DFP-G increased as eGFR decreased. Overall, 75%-95% of the dose was retrieved in urine, either as DFP or DFP-G, regardless of severity of renal impairment. With respect to safety, DFP was well tolerated. CONCLUSIONS: These data suggest that no adjustment of the DFP dosage regimen in patients with renal impairment is necessary, as there were no significant changes in the systemic exposure to the drug.

Effect of experimental kidney disease on the functional expression of hepatic reductases.

Chronic kidney disease (CKD) affects the nonrenal clearance of drugs by modulating the functional expression of hepatic drug-metabolizing enzymes and transporters. The impact of CKD on oxidative and conjugative metabolism has been extensively studied. However, its effect on hepatic drug reduction, an important phase I drug-metabolism pathway, has not been investigated. We aimed to assess the effect of experimental CKD on hepatic reduction using warfarin as a pharmacological probe substrate. Cytosolic and microsomal cellular fractions were isolated from liver tissue harvested from five-sixths-nephrectomized and control rats (n = 10 per group). The enzyme kinetics for warfarin reduction were evaluated in both fractions, and formation of warfarin alcohols was used as an indicator of hepatic reductase activity. Selective inhibitors were employed to identify reductases involved in warfarin reduction. Gene and protein expression of reductases were determined using quantitative real-time polymerase chain reaction and Western blotting, respectively. Formation of RS/SR-warfarin alcohol was decreased by 39% (P < 0.001) and 43% (P < 0.01) in cytosol and microsomes, respectively, in CKD rats versus controls. However, RR/SS-warfarin alcohol formation was unchanged in the cytosol, and a trend toward its decreased production was observed in microsomes. Gene and protein expression of cytosolic carbonyl reductase 1 and aldo-keto reductase 1C3/18, and microsomal 11ß-hydroxysteroid dehydrogenase type 1 were significantly reduced by >30% (P < 0.05) in CKD rats compared with controls. Collectively, these results suggest that the functional expression of hepatic reductases is selectively decreased in kidney disease. Our findings may explain one mechanism for altered nonrenal clearance, exposure, and response of drugs in CKD patients.

In Vitro and In Vivo Mechanistic Studies toward Understanding the Role of 1-Aminobenzotriazole in Rat Drug-Drug Interactions.

1-Aminobenzotriazole (ABT) is regularly used in vivo as a nonspecific and irreversible cytochrome P450 inhibitor to elucidate the role of metabolism on the pharmacokinetic profile of xenobiotics. However, few reports have considered the recent findings that ABT can alter drug absorption or have investigated the possible differential inhibition of ABT on intestinal and hepatic metabolism. To address these uncertainties, pharmacokinetic studies under well controlled and defined ABT pretreatment conditions (50 mg/kg, 1 hour ABT i.v. and 16 hours ABT p.o.) were conducted prior to the oral administration of metoprolol, a permeable P450 probe that undergoes extensive intestinal and hepatic metabolism. The pharmacokinetic profile of metoprolol was affected differently by the two ABT pretreatments. An increase in area under the curve of 16-fold with ABT p.o. and 6.5-fold with ABT i.v. was observed compared with control. Based on in vitro studies, this difference could not be attributed to a differential inhibition of intestinal and hepatic metabolism. In the ABT i.v. pretreatment group, the increase in area under the curve was also associated with a prolonged time at maximal concentration (24-fold versus control), suggesting a delay in absorption. This was further confirmed by the administration of a charcoal meal, which resulted in a 7-fold increase in stomach weights in the 1-hour ABT pretreated groups compared with the untreated or 16-hour ABT pretreated rats. Based on these results, we recommend pretreating rats with ABT p.o. 16 hours before the administration of a test compound to preserve the inhibitory effect on intestinal and hepatic metabolism and avoid the confounding effect on drug absorption.

Transplantation of mesenchymal stem cells promotes tissue regeneration in a glaucoma model through laser-induced paracrine factor secretion and progenitor cell recruitment.

Among bone marrow cells, hematopoietic and mesenchymal components can contribute to repair damaged organs. Such cells are usually used in acute diseases but few options are available for the treatment of chronic disorders. In this study, we have used a laser-induced model of open angle glaucoma (OAG) to evaluate the potential of bone marrow cell populations and the mechanisms involved in tissue repair. In addition, we investigated laser-induced tissue remodeling as a method of targeting effector cells into damaged tissues. We demonstrate that among bone marrow cells, mesenchymal stem cells (MSC) induce trabecular meshwork regeneration. MSC injection into the ocular anterior chamber leads to far more efficient decrease in intraocular pressure (IOP) (p < .001) and healing than hematopoietic cells. This robust effect was attributable to paracrine factors from stressed MSC, as injection of conditioned medium from MSC exposed to low but not to normal oxygen levels resulted in an immediate decrease in IOP. Moreover, MSC and their secreted factors induced reactivation of a progenitor cell pool found in the ciliary body and increased cellular proliferation. Proliferating cells were observed within the chamber angle for at least 1 month. Laser-induced remodeling was able to target MSC to damaged areas with ensuing specific increases in ocular progenitor cells. Thus, our results identify MSC and their secretum as crucial mediators of tissue repair in OAG through reactivation of local neural progenitors. In addition, laser treatment could represent an appealing strategy to promote MSC-mediated progenitor cell recruitment and tissue repair in chronic diseases.

Comparison of oral and intravenous alfacalcidol in chronic hemodialysis patients.

BACKGROUND: Activated vitamin D is the mainstay of treatment for secondary hyperparathyroidism (SHPT) in chronic hemodialysis patients. However, the optimal route of administration is still debated. The aim of our study was to compare efficacy of oral vs intravenous (IV) administration of alfacalcidol in hemodialysis. A secondary objective was to determine the cost-effectiveness advantage of oral administration. METHODS: Eighty-eight chronic hemodialysis patients receiving IV alfacalcidol three times a week were included in the study. All were switched to the same dose of alfacalcidol given orally three times a week during the hemodialysis session. A budget impact analysis was performed. RESULTS: Mean patient age was 64 years old and 43% were males. The mean alfacalcidol dose administered was 2.1 µg three times a week. After three months, serum parathormone (PTH) levels decreased from 80 to 59 pmol/L (p = 0.001) and total serum calcium levels increased from 2.34 to 2.40 mmol/L (p = 0.002). After six months, total serum calcium levels were still significantly higher. Alfacalcidol dosage was significantly decreased during study period; the mean reduction was 0.44 µg per dose. Finally, oral administration was associated with an annual cost reduction of 197 678$CAN and an annual nursing time reduction of 25 days. CONCLUSION: Our findings support that switching IV to oral administration of alfacalcidol during hemodialysis sessions may lead to a similar control of SHPT with lower doses of activated vitamin D. This is a good strategy for optimizing compliance and may allow a dose reduction because of a greater efficacy to suppress PTH. Oral administration also has significant cost-effectiveness advantages.

An interprofessional team that includes a nurse practitioner and patients with diabetes and chronic kidney disease.

Diabetes is the leading cause of chronic kidney disease (CKD). The clinical practice guidelines of the Canadian Diabetes Association were updated in 2013. We sought to identify the level of adherence to the CDA guidelines of an interprofessional team in a pre-dialysis clinic that includes a nurse practitioner, and examine how team members integrated the guidelines and optimized each provider's role. A mixed methods study was undertaken. Chart audits (n= 146) identified 10 patients who met the inclusion criteria. The level of adherence to the CDA guidelines was high for several indicators; yet a number of care activities were not well documented in the health record. Interviews (n= 7) with interprofessional team members identified specific strategies used by providers to incorporate the guidelines and optimize each team members's role. Accurate documentation of care activities is essential to assessing adherence to guidelines and informing decisions about care.

Restoration of renal function by a novel prostaglandin EP4 receptor-derived peptide in models of acute renal failure.

Acute renal failure (ARF) is a serious medical complication characterized by an abrupt and sustained decline in renal function. Despite significant advances in supportive care, there is currently no effective treatment to restore renal function. PGE(2) is a lipid hormone mediator abundantly produced in the kidney, where it acts locally to regulate renal function; several studies suggest that modulating EP(4) receptor activity could improve renal function following kidney injury. An optimized peptidomimetic ligand of EP(4) receptor, THG213.29, was tested for its efficacy to improve renal function (glomerular filtration rate, renal plasma flow, and urine output) and histological changes in a model of ARF induced by either cisplatin or renal artery occlusion in Sprague-Dawley rats. THG213.29 modulated PGE(2)-binding dissociation kinetics, indicative of an allosteric binding mode. Consistently, THG213.29 antagonized EP(4)-mediated relaxation of piglet saphenous vein rings, partially inhibited EP(4)-mediated cAMP production, but did not affect Gα(i) activation or ß-arrestin recruitment. In vivo, THG213.29 significantly improved renal function and histological changes in cisplatin- and renal artery occlusion-induced ARF models. THG213.29 increased mRNA expression of heme-oxygenase 1, Bcl2, and FGF-2 in renal cortex; correspondingly, in EP(4)-transfected HEK293 cells, THG213.29 augmented FGF-2 and abrogated EP(4)-dependent overexpression of inflammatory IL-6 and of apoptotic death domain-associated protein and BCL2-associated agonist of cell death. Our results demonstrate that THG213.29 represents a novel class of diuretic agent with noncompetitive allosteric modulator effects on EP(4) receptor, resulting in improved renal function and integrity following acute renal failure.

Magnitude of discordance between registry data and death certificate when evaluating leading causes of death in dialysis patients.

BACKGROUND: Discordance between dialysis registry and death certificate reported death has been demonstrated. Since cause of death is measured using registry data in dialysis patients and death certificate data in the general population, comparisons of cause of death proportions between dialysis patients and the general population may be biased. Our aim was to compare the proportion of deaths attributed to cardiovascular disease (CVD), malignancy, and infections between patients receiving dialysis and the general population using death certificates for both, and to quantify the magnitude of discrepancy between registry and death certificate estimates in dialysis patients. METHODS: A retrospective cohort study of 5858 patients initiating maintenance dialysis between 2001 and 2007 was conducted. Cause of death was obtained from both registry and death certificate data for dialysis patients, and from death certificate data for the general population. RESULTS: Compared to the general population, use of death certificate data in dialysis patients resulted in smaller differences in the proportion of deaths attributed to CVD or infection than that from the registry. In the general population, the proportion of deaths due to CVD is 29.3% for men and 28.2% for women, and the proportion of deaths due to infection is 3.3% for men and 3.6% for women. For men, the proportion of deaths in dialysis patients due to CVD using registry data is 41.5%, compared with a proportion of 32.1% using death certificate data. Similarly for women, the proportion of deaths due to CVD using registry data is 35.2% and that using death certificate data 24.3%. The proportion of deaths due to infection in dialysis patients follows the same pattern: for men, the proportion of deaths due to infection using registry data is 9.9% and that from death certificate data at 5.0%; while for women the proportions are 11.6% and 4.8%, respectively. CONCLUSIONS: While absolute cause-specific mortality rates did differ, evaluation of causes of death using death certificate in dialysis patients in Quebec revealed that they do not have substantially different proportion of death due to CVD or infections than the general population. Infections appeared to be a frequent complication leading to death, suggesting that infections are an important target to consider for reducing mortality in dialysis populations.

Effect of cinacalcet availability and formulary listing on parathyroidectomy rate trends.

BACKGROUND: Recent trends in parathyroidectomy rates are not known. Our objective was to investigate the trend in parathyroidectomy rates between 2001 and 2010, and to evaluate if the availability and reimbursement of cinacalcet modified that trend. METHODS: Using a provincial administrative database, we included all adult patients receiving chronic dialysis treatments between 2001 and 2010 (incident and prevalent) in a time series analysis. The effect of cinacalcet availability on parathyroidectomy bimonthly rates was modeled using an ARIMA intervention model using different cut-off dates: September 2004 (Health Canada cinacalcet approval), January 2005, June 2005, January 2006, June 2006 (date of cinacalcet provincial reimbursement), and January 2007. RESULTS: A total of 12 795 chronic dialysis patients (mean age 64 years, 39% female, 82% hemodialysis) were followed for a mean follow-up of 3.3 years. During follow-up, 267 parathyroidectomies were identified, translating to an average rate of 7.0 per 1000 person-years. The average parathyroidectomy rate before cinacalcet availability was 11.4 /1000 person-years, and 3.6 /1000 person-years after cinacalcet public formulary listing. Only January 2006 as an intervention date in the ARIMA model was associated with a change in parathyroidectomy rates (estimate: -5.58, p = 0.03). Other intervention dates were not associated with lower parathyroidectomy rates. CONCLUSIONS: A reduction in rates of parathyroidectomy was found after January 2006, corresponding to cinacalcet availability. However, decreased rates may be due to other factors occurring simultaneously with cinacalcet introduction and further studies are needed to confirm these findings.

Effects of chronic renal failure on brain drug transporters in rats.

Studies demonstrated that chronic renal failure (CRF) affects the expression and activity of intestinal, hepatic, and renal drug transporters. Such drug transporters are expressed in brain cells and at the blood-brain barrier (BBB), where they limit the entry and distribution of drugs in the brain. Perturbations in brain drug transporter equilibrium by CRF could lead to central drug toxicity. This study evaluates how CRF affects BBB drug transporters using a 5/6 nephrectomized rat model. Protein and mRNA expression of influx transporters [organic anion-transporting polypeptide (Oatp), organic anion transporter (Oat)] and efflux transporters [P-glycoprotein (P-gp), multidrug resistance-related protein (Mrp), breast cancer resistance protein (Bcrp)] were measured in CRF and control rat brain. Intracerebral accumulation of radiolabeled benzylpenicillin, digoxin, doxorubicin, and verapamil was used to evaluate BBB drug permeability. Protein expression of the transporters was evaluated in rat brain endothelial cells (RBECs) and astrocytes incubated with control and CRF rat serum. We demonstrated significant decreases (30-50%) in protein and mRNA levels of Bcrp, Mrp2 to -4, Oat3, Oatp2 and -3, and P-gp in CRF rat brain biopsies, as well as in astrocytes and RBECs incubated with CRF serum. These decreases did not correlate with in vivo changes because BBB permeability of benzylpenicillin was decreased by 30% in CRF rats, whereas digoxin, doxorubicin, and verapamil permeabilities were unchanged. It thus seems that even with decreased drug transporters, BBB integrity and function is conserved in CRF.

SMOC2 promotes an epithelial-mesenchymal transition and a pro-metastatic phenotype in epithelial cells of renal cell carcinoma origin.

Renal Cell Carcinoma (RCC) is the most common form of all renal cancer cases, and well-known for its highly aggressive metastatic behavior. SMOC2 is a recently described non-structural component of the extracellular matrix (ECM) that is highly expressed during tissue remodeling processes with emerging roles in cancers, yet its role in RCC remains elusive. Using gene expression profiles from patient samples, we identified SMOC2 as being significantly expressed in RCC tissue compared to normal renal tissue, which correlated with shorter RCC patient survival. Specifically, de novo protein synthesis of SMOC2 was shown to be much higher in the tubular epithelial cells of patients with biopsy-proven RCC. More importantly, we provide evidence of SMOC2 triggering kidney epithelial cells into an epithelial-to-mesenchymal transition (EMT), a phenotype known to promote metastasis. We found that SMOC2 induced mesenchymal-like morphology and activities in both RCC and non-RCC kidney epithelial cell lines. Mechanistically, treatment of RCC cell lines ACHN and 786-O with SMOC2 (recombinant and enforced expression) caused a significant increase in EMT-markers, -matrix production, -proliferation, and -migration, which were inhibited by targeting SMOC2 by siRNA. We further characterized SMOC2 activation of EMT to occur through the integrin ß3, FAK and paxillin pathway. The proliferation and metastatic potential of SMOC2 overexpressing ACHN and 786-O cell lines were validated in vivo by their significantly higher tumor growth in kidneys and systemic dissemination into other organs when compared to their respective controls. In principle, understanding the impact that SMOC2 has on EMT may lead to more evidence-based treatments and biomarkers for RCC metastasis.

Rationale for heating oxaliplatin for the intraperitoneal treatment of peritoneal carcinomatosis: a study of the effect of heat on intraperitoneal oxaliplatin using a murine model.

OBJECTIVE: To study the effect of heat on the absorption of intraperitoneal (IP) oxaliplatin using a murine model. BACKGROUND: Because of its efficiency in the systemic treatment of colorectal cancer, oxaliplatin is currently used in hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis. However, its properties when administered by the IP route have not been well characterized by preclinical studies. METHODS: Under general anesthesia, 35 Sprague-Dawley rats were submitted to 3 different doses of IP oxaliplatin (460, 920, and 1840 mg/m(2)) at 3 different perfusion temperatures (37, 40, and 43°C) during 25 minutes. At the end of perfusion, samples in different compartments (peritoneum, portal blood, and systemic blood) were harvested and the concentrations of oxaliplatin were measured by high performance liquid chromatography. RESULTS: As the dose of IP oxaliplatin was increased, higher concentrations were observed in every compartment. When the temperature of IP oxaliplatin was increased, it resulted in an increase of its peritoneal concentration (linear regression 0.38; 95% CI: 0.28-0.47) and in a decrease of its systemic blood (linear regression -1, 02; 95% CI: -1.45 to -0.60) and portal blood (linear regression -1.08; 95% CI: -1.70 to -0.47) concentrations. CONCLUSION: Proportionally to the dose administered, IP oxaliplatin leads to high concentration of drug in peritoneal tissues. Furthermore, heat enhances peritoneal tissue concentration of Oxaliplatin while reducing its systemic absorption. This last effect may possibly lead to decreased systemic toxicity. These observations support the use of oxaliplatin for HIPEC.

Effects of chronic renal failure on kidney drug transporters and cytochrome P450 in rats.

Chronic renal failure (CRF) leads to decreased drug renal clearance due to a reduction in the glomerular filtration rate. However, little is known about how renal failure affects renal metabolism and elimination of drugs. Because both depend on the activity of uptake and efflux by renal transporters as well as enzymes in tubular cells, the purpose of this study was to investigate the effects of CRF on the expression and activity of select renal drug transporters and cytochrome P450. Two groups of rats were studied: control and CRF (induced by 5/6 nephrectomy). Compared with control rats, we observed reductions in the expression of both protein and mRNA of Cyp1a, sodium-dependent phosphate transport protein 1, organic anion transporter (Oat)1, 2, and 3, OatK1/K2, organic anion-transporting polypeptide (Oatp)1 and 4c1, P-glycoprotein, and urate transporter 1, whereas an induction in the protein and mRNA expression of Mrp2, 3, and 4 and Oatp2 and 3 was observed. Cyp3a expression remained unchanged. Similar results were obtained by incubating a human proximal tubule cell line (human kidney-2) with sera from CRF rats, suggesting the presence of uremic modulators. Finally, the renal elimination of [(3)H]digoxin and [(14)C]benzylpenicillin was decreased in CRF rats, compared with controls, as shown by a 4- and 9-fold accumulation, respectively, of these drugs in kidneys of rats in CRF. Our results demonstrate that CRF affects the expression and activity of several kidney drug transporters leading to the intrarenal accumulation of drugs and reduced renal clearance that could, at least partially, explain the tubular toxicity of many drugs.

Reduced hepatic synthesis of calcidiol in uremia.

Calcidiol insufficiency is highly prevalent in chronic kidney disease (CKD), but the reasons for this are incompletely understood. CKD associates with a decrease in liver cytochrome P450 (CYP450) enzymes, and specific CYP450 isoforms mediate vitamin D(3) C-25-hydroxylation, which forms calcidiol. Abnormal levels of parathyroid hormone (PTH), which also modulates liver CYP450, could also contribute to the decrease in liver CYP450 associated with CKD. Here, we evaluated the effects of PTH and uremia on liver CYP450 isoforms involved in calcidiol synthesis in rats. Uremic rats had 52% lower concentrations of serum calcidiol than control rats (P < 0.002). Compared with controls, uremic rats produced 71% less calcidiol and 48% less calcitriol after the administration of vitamin D(3) or 1alpha-hydroxyvitamin D(3), respectively, suggesting impaired C-25-hydroxylation of vitamin D(3). Furthermore, uremia associated with a reduction of liver CYP2C11, 2J3, 3A2, and 27A1. Parathyroidectomy prevented the uremia-associated decreases in calcidiol and liver CYP450 isoforms. In conclusion, these data suggest that uremia decreases calcidiol synthesis secondary to a PTH-mediated reduction in liver CYP450 isoforms.