Expression of beta-carotene 15,15'- monooxygenase gene and retinol status in rats with puromycin aminonucleoside-induced nephrosis

Retinol and its metabolite retinoic acid play a critical role in immunity, reproduction, and development. Retinoids are known to influence renal development, and show beneficial effects in experimental models of renal disease. beta-Carotene (provitamin A) is cleaved to retinal by beta-carotene 15,15'- monooxygenase (BCM), which is an essential enzyme for retinoid biosynthesis. However, the metabolism of retinol and beta-carotene in renal diseases such as nephrosis remains unclear. We studied BCM gene expression and retinol status in rats with nephrotic syndrome induced by puromycin aminonucleoside (PAN). BCM gene expression in the liver and intestines of PAN-treated rats was decreased compared with that in controls, while the expression in the kidney of PAN-treated animals was increased. Plasma retinol and retinol-binding protein levels were decreased in PAN-treated rats, but hepatic retinol level did not differ between PAN-treated and control rats. Up-regulation of BCM gene expression in the kidneys of rats with nephrotic syndrome may result in increased conversion of beta-carotene to retinal, so this change might supply more retinoic acid to the damaged glomeruli. Changes in the metabolism of retinol and beta-carotene might have an important role in protection against the development of nephrosis.

Chinese herbal formula Qilong-Lishui granule improves puromycin aminonucleoside-induced renal injury through regulation of bone morphogenetic proteins

BACKGROUND

The Chinese herbal formula Qilong-Lishui granule (QLG) is an effective natural product for treatment of renal disorder. It was composed of six Chinese herbs according to our clinical practice in the treatment of patients with kidney disease. However, molecular and cellular mechanisms of QLG are still unclear. Therefore, the objective of the current study is to investigate molecular and cellular mechanisms of QLG in puromycin aminonucleoside (PAN)-induced nephrotic syndrome.

METHOD

Wistar rats were divided into six groups of sham operation, PAN model, PAN model with high-dosage QLG (QLG-H), PAN model with median-dosage QLG (QLG-M), PAN model with low-dosage QLG (QLG-L), and PAN model with fosinopril (FP). The PAN model was induced by jugular vein injection of PAN at a dose of 5 mg/100 g body weight. Quantities of 24 h urinary protein excretion were examined on days 5, 10, 15, 20, 25 and 30. All rats were sacrificed on day 31 for blood biochemistry, kidney histology and reverse transcriptase-polymerase chain reaction analysis.

RESULTS

PAN-induced nephrotic syndrome was successfully produced in rats. Treatment of QLG significantly reduced protein excretion and blood urea nitrogen and creatinine. QLG and FP treatments also improved protein content in blood, and reduced total cholesterol and triglyceride in blood. Moreover, QLG and FP improved the damage of interstitial induced by PAN. Furthermore, CYP and FP were able to reverse BMPRII and Smad1 mRNAs abundance caused by PAN.

CONCLUSION

QLG attenuates PAN-induced kidney injury possibly through the bone morphogenetic protein signal transduction pathway.

Cardiac remodeling and dysfunction in nephrotic syndrome

There is an increased incidence of heart disease in patients with chronic nephrotic syndrome (NS), which may be attributable to the malnutrition and activated inflammatory state accompanying the sustained proteinuria. In this study, we evaluated renal function, cardiac morphometry, contractile function, and myocardial gene expression in the established puromycin aminonucleoside nephrosis rat model of NS. Two weeks after aminonucleoside injection, there was massive proteinuria, decreased creatinine clearance, and a negative sodium balance. Skeletal and cardiac muscle atrophy was present and was accompanied by impaired left ventricular (LV) hemodynamic function along with decreased contractile properties of isolated LV muscle strips. The expression of selected cytokines and proteins involved in calcium handling in myocardial tissue was evaluated by real time polymerase chain reaction. This revealed that the expression of interleukin-1beta, tumor necrosis factor-alpha, and phospholamban were elevated, whereas that of cardiac sarco(endo)plasmic reticulum calcium pump protein was decreased. We suggest that protein wasting and systemic inflammatory activation during NS contribute to cardiac remodeling and dysfunction.

Protective role of sulphated polysaccharides in abating the hyperlipidemic nephropathy provoked by cyclosporine A

Cyclosporine A (CsA)-induced nephrotoxicity hampers the immense therapeutic potential of such a powerful immunosuppressant. The present study was conducted with an aim to explicate the contribution of sulphated polysaccharides (SPS) in abating the lipid abnormalities induced by CsA in the rat kidney. Hyperlipidemia associated with nephrotic syndrome may play a role in the worsening of renal function. Male albino Wistar rats sorted into four groups were used for the study. CsA was given at a dose of 25 mg/kg body weight, orally for 21 days. Significant alterations in the lipid profile as well an increase in the activity of cholesterol ester synthase, coupled with a decrease in cholesterol ester hydrolase and lipoprotein lipase enzyme activities were noted in the plasma and kidneys of CsA-administered rats. A marked increase in the lipoprotein fractions, low-density lipoprotein (LDL) and very low density lipoprotein (VLDL), along with a decrease in the HDL level were found in CsA-administered rats. The degree of nephrotoxicity allied with lipid discrepancies was evident from augmented urinary excretion of urea, uric acid and creatinine. Further, an enhanced susceptibility of the apo B-containing lipoproteins (LDL + VLDL) to oxidation in vitro, induced by copper ions was also found in the plasma of CsA given groups. While SPS co-treated groups (5 mg/kg body weight, subcutaneously) revealed a normalized lipid profile and lipid metabolizing enzymes, the supplementation of SPS also brought back the elevated urinary constituents close to that of the controls and substantially minimized the oxidative changes. With these observations, it may be concluded herein that SPS may be an ideal choice as a renoprotective and hypolipidemic agent against CsA-induced hyperlipidemic nephropathy.

Increased cyclosporine bioavailability induced by experimental nephrotic syndrome in rats

Components of whole blood and plasma are highly altered during the presentation of nephrotic syndrome. The present study was aimed to explore the influence of nephrotic syndrome on the pharmacokinetics of cyclosporine (CsA) (10 mg/kg) administered i.v. to control or puromycin-induced nephrotic rats (P-NS). We found an increase in CsA bioavailability in the nephrotic group compared with controls. The area under the curve of blood CsA versus time (AUCiv) increased from 27.7 ± 5.3 to 60.6 ± 13.8 μg·h·mL–1in control and P-NS rats, respectively. The AUCivaugmentation was positively correlated with cholesterol levels. On the other hand, the total body clearance was significantly lower (0.38 ± 0.06 vs. 0.17 ± 0.03 L·(kg body mass)–1·h–1) and the volume of distribution at steady state (3.70 ± 0.52 vs. 2.85 ± 0.32 L/kg) was significantly smaller in nephrotic rats as compared with control. These pharmacokinetic changes lead to a longer terminal half-life of CsA in P-NS rats (11.8 ± 1.6 vs. 6.9 ± 0.91 h). We conclude that the physiopathologic changes induced by the nephrotic syndrome in P-NS animals result in a significant increase in CsA blood exposure by both the decrease in drug distribution and the reduction in elimination rate of CsA.

Podocyte protection by darbepoetin: preservation of the cytoskeleton and nephrin expression

Podocyte injury is a significant contributor to proteinuria and glomerulosclerosis. Recent studies have shown a renoprotective effect of erythropoietin (EPO) during ischemic kidney disease. In this study, we examine mechanisms by which a long acting recombinant EPO analog, darbepoetin, may confer renoprotection in the puromycin aminonucleoside-induced model of nephrotic syndrome. Darbepoetin decreased the proteinuria of rats treated with puromycin. This protective effect was correlated with the immunohistochemical disappearance of the podocyte injury markers desmin and the immune costimulator molecule B7.1 with the reappearance of nephrin expression in the slit diaphragm. Podocyte foot process retraction and effacement along with actin filament rearrangement, determined by electron microscopy, were all reversed by darbepoetin treatment. The protective effects were confirmed in puromycin-induced nephrotic rats that had been hemodiluted to normal hematocrit levels. Furthermore, puromycin treatment of rat podocytes in culture caused actin cytoskeletal reorganization along with deranged nephrin distribution. All these effects in vitro were reversed by darbepoetin. Our study demonstrates that darbepoetin treatment ameliorates podocyte injury and decreases proteinuria by a direct effect on podocytes. This may be accomplished by maintenance of the actin cytoskeleton and nephrin expression.

Nephrotic Syndrome After Bevacizumab: Case Report and Literature Review

Bevacizumab, or avastin, is a monoclonal hybrid antibody that binds to and neutralizes vascular endothelial growth factor. It has shown promising efficacy in the adjunctive treatment of patients with several cancers. Recent reports indicated that bevacizumab therapy often was associated with the development of proteinuria, but rarely nephrotic syndrome. In this report, we describe a patient who developed new-onset hypertension and nephrotic syndrome in association with bevacizumab treatment for metastatic pancreatic cancer. Renal biopsy showed an immune-complex-mediated focal proliferative glomerulonephritis. Nephrotic syndrome and hypertension resolved after discontinuation of bevacizumab therapy. The mechanism of bevacizumab-induced glomerulonephritis and nephrotic syndrome is unknown and requires additional investigation. Clinicians should be aware of the potential reversible nephrotoxicity of bevacizumab and should monitor blood pressure and urine protein excretion closely during therapy with this agent.

L-carnitine ameliorates doxorubicin-induced nephrotic syndrome in rats

AIM

Effects of L-carnitine on nephrotoxicity and oxidative stress induced by doxorubicin (DOX) in rats were investigated.

METHODS

The rats were divided into four groups: group 1, control (0.9% NaCl); group 2, DOX injection (7.5 mg/kg, i.v.); group 3, DOX plus low dose (40 mg/kg) L-carnitine; and group 4, DOX plus high dose (200 mg/kg) L-carnitine. L-carnitine was administered 1 h before doxorubicin injection and daily thereafter for 15 days.

RESULTS

Rats in group 2 were associated with hypoalbuminaemia, hyperlipidaemia, high urinary excretion of protein and elevated plasma creatinine and urea nitrogen. The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) decreased with increased renal vascular resistance (RVR). Kidney catalase (CAT) activity was decreased. In group 3 and 4, plasma triglyceride and cholesterol declined. L-carnitine improved renal functions by elevated GFR and ERPF and decreased plasma creatinine and urea nitrogen. The kidney CAT activity were increased significantly compared with group 2. From histopathological results, group 2 rats were found to have glomerular capillary dilation and tubular dilation. The lesions were less in group 3 and 4 rats.

CONCLUSION

L-carnitine can protect renal impairment functionally, biochemically and histopathologically with a corresponding reduction of oxidative stress.

Hyperbaric oxygen treatment augments the efficacy of a losartan regime in an experimental nephrotic syndrome model

BACKGROUND/AIMS

Proteinuria is associated with oxidant stress and inflammation. Hyperbaric oxygen (HBO) treatment has anti-inflammatory and anti-oxidant effects. The aim of the study was to investigate the benefits of HBO treatment on an experimental nephrotic syndrome model.

METHODS

50 male Sprague-Dawley rats weighing 255 +/- 39 g were housed. Forty rats were injected 6 mg/kg adriamycin into tail veins under anesthesia to induce nephrosis, while 10 rats were spared as sham control. After the stabilization of proteinuria at the sixth week, the rats were treated for 6 weeks by losartan (n = 10, 30 mg/kg/day), HBO (n = 10, 2.8 atmosphere absolute, 90 min/day), HBO + losartan (n = 10) and vehicle (n = 10). Protein carbonyl (PCO), superoxide dismutase (SOD) and glutathione peroxidase (GPx) were analyzed from tissue specimens. Biochemical markers were studied from venous samples and 24-hour urine was collected for proteinuria. The surviving animals at 12 weeks (vehicle group (n = 6), HBO (n = 6), losartan (n = 8), HBO + losartan (n = 10) were sacrificed. Glomerular sclerosis, tubulointerstitial and blood vessel changes were determined by semiquantitative scoring.

RESULTS

The PCO levels increased (p < 0.001), and the GPx and SOD levels decreased (p < 0.001 for both) in the nephrotic rats. In losartan and HBO groups GPx levels increased (p = 0.001, p = 0.002 respectively), but PCO and SOD levels did not change. The combination of HBO with losartan significantly increased the GPx and SOD levels (p = 0.001 for both) and decreased PCO levels (p = 0.005). HBO but not losartan significantly reduced proteinuria (p < 0.001). The combination of HBO and losartan reduced proteinuria better than the single losartan regime (p < 0.001). The effect of the combination was also noticed on the histological examination of the kidneys. The activities, appetites, weight gains, and improvement of edema were better in the HBO combined with losartan regime.

CONCLUSIONS

These results indicate that the addition of HBO therapy to a conventional regime, angiotensin receptor blockers, has significant benefits in the management of proteinuria. Future clinical studies are needed to elucidate the role of HBO and other antioxidant strategies in the treatment of proteinuria.

Thrombotic microangiopathy associated with alpha-interferon therapy for chronic myeloid leukaemia (Case Report)

The association of interferon (IFN) therapy with haemolytic uraemic syndrome in patients with chronic myeloid leukaemia (CML) has been reported infrequently. The pathogenesis of the renal lesion in such cases remains unclear. We report the case of a patient with chronic myeloid leukaemia who developed nephrotic syndrome and renal failure while being treated with hydroxyurea and IFN-alpha. Renal biopsy showed features of chronic thrombotic microangiopathy. The discontinuation of IFN-alpha, and a prompt institution of plasmapheresis and steroids resulted in improvement of the nephrotic syndrome and renal function. These findings suggest that long-term IFN-alpha therapy can induce thrombotic microangiopathy and haemolytic uraemic syndrome in patients with chronic myeloid leukaemia.

Increased expression but not targeting of ENaC in adrenalectomized rats with PAN-induced nephrotic syndrome

Sodium retention is a hallmark of nephrotic syndrome (NS). Puromycin aminonucleoside (PAN)-induced NS is associated with high aldosterone levels and increased ENaC expression and apical targeting. However, the mechanisms associated with increased apical targeting of ENaC in NS remain undefined, and it is unclear whether this is secondary to high aldosterone levels and whether aldosterone and/or apical ENaC targeting are important for the development of sodium retention. This study aimed at uncovering 1) whether aldosterone is essential for sodium retention in PAN-induced NS, 2) whether ENaC expression or apical targeting is secondary to high aldosterone levels, and 3) the role of aldosterone in the dysregulation of sodium transporters in NS. Puromycin treatment of adrenalectomized (ADX) rats supplemented with dexamethasone induced sodium retention despite the absence of aldosterone. Immunocytochemical analyses revealed an absence of enhanced apical targeting of ENaC subunits in PAN-treated ADX (ADX-PAN) rats, with distribution of labeling similar to adrenalectomized dexamethasone-treated control rats (ADX). Moreover, ENaC subunit abundance was increased in ADX-PAN rats. The abundance of aquaporin-2 was unchanged, whereas apical targeting was enhanced. Key sodium transporters were downregulated as previously observed in nonadrenalectomized puromycin-treated rats (Kim SW, Wang W, Nielsen J, Praetorius J, Kwon TH, Knepper MA, Frøkiaer J, and Nielsen S. Am J Physiol Renal Physiol 286: F922-F935, 2004), whereas the global expression of the alpha1-subunit of the Na-K-ATPase was unchanged. In conclusion, PAN treatment in the absence of aldosterone induced sodium retention, increased ENaC expression, but did not change the subcellular distribution of ENaC. This indicates that the previously observed enhanced apical targeting of ENaC in PAN-induced NS (Kim SW, Wang W, Nielsen J, Praetorius J, Kwon TH, Knepper MA, Frøkiaer J, and Nielsen S. Am J Physiol Renal Physiol 286: F922-F935, 2004) is caused by aldosterone and that development of sodium retention can occur in the absence of aldosterone in NS.

[Neurotoxicity of cyclosporine]

Using cyclosporine as an immunosuppressive drug allowed increasing survival of grafts as well as patients. Despite this drug is being safely used for many years, it can cause complications. The most often complications are nefrotoxicity, hepatotoxicity, diabetes mellitus, arterial hypertension and neurotoxicity. The most often manifestation of neurotoxicity are tremor, leucoencephalopathia, headache and even seizures. Among risk factors we can enumerate arterial hypertetension, low cholesterol level, hypomagnesemia and previous cerebrovascular insufficiency.

Impact of the cyclosporine-ketoconazole interaction in children with steroid-dependent idiopathic nephrotic syndrome

BACKGROUND

Children with steroid-dependent nephrotic syndrome experience serious side effects from steroid therapy. Cyclosporine A (CsA), which is an effective agent in the treatment of steroid-dependent nephrotic syndrome, is expensive and, consequently, often unaffordable in developing countries. Many studies have documented the benefit of ketoconazole administration in transplant adults treated with CsA. We have conducted a retrospective study with the objective of addressing cost-savings, safety, and the efficacy of the co-administration of ketoconazole and CsA to children with steroid-dependent nephrotic syndrome.

METHODS

This study included 102 nephrotic patients who were steroid-dependent and who received cyclosporine therapy. The commonest pathologic lesions were focal segmental glomerulosclerosis (64 patients) and minimal change disease (36 patients). Among the patients participating in the study, 78 received daily ketoconazole therapy (ketoconazole group) in the form of a 50-mg dose accompanied by an initial one-third decrease in the CsA dose, while 24 received CsA alone (non- ketoconazole group). All of the patients were children (below 18 years), and the male-to-female ratio was 3:1. The mean duration of treatment was 22.9 months. The characteristics of both groups were comparable.

RESULTS

Co-administration of ketoconazole significantly reduced mean doses of CsA by 48% with a net cost savings of 38%. It also resulted in a significant improvement in the CsA response and a more successful steroid withdrawal as well as a decrease in the frequency of renal impairment. Liver function tests remained normal in both groups up to and including the final follow-up (mean of 33.6 months).

CONCLUSIONS

The co-administration of ketoconazole to CsA in children with idiopathic steroid-dependent nephrotic syndrome safely results in a significant reduction in CsA cost, which causes great concern in developing countries. It may also improve CsA response.

Nephrotic syndrome in a multiple sclerosis patient treated with interferon beta 1a

BACKGROUND

Interferon beta has become standard therapy for reducing relapse frequency in relapsing/remitting Multiple Sclerosis (RRMS). Several different preparations are available including interferon beta 1a (Avonex, Rebif) and interferon beta 1b (Betaferon/Betaseron). For the most part these preparations have been considered safe. Recently there have been concerns relating to liver and now kidney toxicity.

CASE REPORT

We present a case of a 28-yr-old male who developed a severe case of nephrotic syndrome while being treated for relapsing/remitting Multiple Sclerosis (RRMS) with weekly injections of interferon beta 1a. SUBSEQUENT COURSE: The nephrosis resolved almost completely once the interferon was stopped and after immunosuppressive treatment. At its peak the daily protein loss was 35.82 g. Kidney biopsy demonstrated membranous glomerulonephritis.

DISCUSSION

Two other case reports of nephrotic syndrome have been reported in the literature. This latest (third) report suggests that the safety profile should be reexamined and at least raises the question of potential renal toxicity of interferons in MS.

Glomerular tip lesion associated with nonsteroidal anti-inflammatory drug-induced nephrotic syndrome

Glomerular tip lesion and its relation to different glomerular diseases is a subject of controversy. The therapeutic and prognostic clinical implications of glomerular tip lesions are ambiguous. We present a case of glomerular tip lesion associated with nonsteroidal anti-inflammatory drug-induced nephrotic syndrome that further complicates this issue. To our knowledge, this is the first case report of glomerular tip lesion associated with nonsteroidal anti-inflammatory drug-induced nephrotic syndrome.

Infliximab and nephrotic syndrome

Infliximab is a chimeric tumor necrosis factor-alpha (TNF-alpha) monoclonal antibody, which has been used extensively in patients with rheumatoid arthritis and inflammatory bowel disease. It also appears to be effective in other conditions such as psoriasis and ankylosing spondylitis. The major side effect of infliximab is infection. Renal complications are uncommon and not well recognized. This report describes a probable case of infliximab-induced membranous nephropathy.

Blunted renal dopaminergic system activity in puromycin aminonucleoside-induced nephrotic syndrome

BACKGROUND

A primary tubular sodium handling abnormality has been implicated in the edema formation of nephrotic syndrome. Dopamine synthesized by renal proximal tubules behaves as an endogenous natriuretic hormone by activating D(1)-like receptors as a paracrine/autocrine substance.

METHODS

We examined the time courses of the urinary excretion of sodium, protein and dopamine in puromycin aminonucleoside (PAN)-treated and control rats. The rats were sacrificed during greatest sodium retention (day 7) as well as during negative sodium balance (day 14) for the evaluation of renal aromatic l-amino acid decarboxylase (AADC) activity, the enzyme responsible for the synthesis of renal dopamine. Also, the influence of volume expansion (VE) and the effects of the D(1)-like agonist fenoldopam (10 microg/kg bw/min) on natriuresis and on proximal tubular Na(+),K(+)-ATPase activity were examined on day 7.

RESULTS

The daily urinary excretion of dopamine was decreased in PAN-treated rats, from day 5 and beyond. This was accompanied by a marked decrease in the renal AADC activity, on days 7 and 14. During VE, the fenoldopam-induced decrease in proximal tubular Na(+),K(+)-ATPase activity was more pronounced in PAN-treated rats than in controls. However, the urinary sodium excretion during fenoldopam infusion was markedly increased in control rats but was not altered in PAN-treated animals.

CONCLUSION

PAN nephrosis is associated with a blunted renal dopaminergic system activity which may contribute to enhance the proximal tubular Na(+),K(+)-ATPase activity. However, the lack of renal dopamine appears not to be related with the overall renal sodium retention in a state of proteinuria.

Increased apical targeting of renal ENaC subunits and decreased expression of 11betaHSD2 in HgCl2-induced nephrotic syndrome in rats

Nephrotic syndrome is often accompanied by sodium retention and generalized edema. We hypothesize that dysregulation of the epithelial sodium channel (ENaC) and/or of sodium (co)transporters may be responsible for the increased sodium retention associated with HgCl(2)-induced nephropathy. In addition, we examined the hypothesis that the expression of type 2 11beta-hydroxysteroid dehydrogenase (11betaHSD2) is reduced, contributing to the enhanced mineralocorticoid activity. Membranous nephropathy was induced in Brown Norway rats by repeated injections of HgCl(2) (1 mg/kg sc), whereas the control group received only vehicle. After 13 days of treatment, the abundance of ENaC subunits, sodium (co)transporters, and 11betaHSD2 in the kidney was examined by immunoblotting and immunohistochemistry. HgCl(2) treatment induced marked proteinuria, hypoalbuminemia, decreased urinary sodium excretion, and ascites. The protein abundance of alpha-ENaC was increased in the cortex/outer stripe of outer medulla (OSOM) and inner stripe of the outer medulla (ISOM). The protein abundances of beta-ENaC and gamma-ENaC were decreased in the cortex/OSOM while increased in the ISOM. Immunoperoxidase microscopy demonstrated increased targeting of ENaC subunits to the apical plasma membrane in the distal convoluted tubule, connecting tubule, and cortical and medullary collecting duct segments. Moreover, 11betaHSD2 abundance was decreased in cortex/OSOM and ISOM. The protein abundances of type 3 Na/H exchanger (NHE3), Na-K-2Cl cotransporter (NKCC2), and thiazide-sensitive Na-Cl cotransporter (NCC) were decreased. Moreover, the abundance of the alpha-1 subunit of the Na-K-ATPase was decreased in the cortex/OSOM and ISOM but remained unchanged in the inner medulla. These results suggest that increased apical targeting of ENaC subunits combined with diminished abundance of 11betaHSD2 may contribute to sodium retention associated with HgCl(2)-induced nephrotic syndrome. The decreased abundance of NHE3, NKCC2, NCC, and Na-K-ATPase may play a compensatory role in promoting sodium excretion.