Early administration of PDTC in adriamycin nephropathy: effect on proteinuria, cortical tubulointerstitial injury, and NF-kappaB activation

Inhibiting nuclear factor-κB at different stages after intracerebral hemorrhage can influence the hemorrhage-induced brain injury in experimental models in vivo

OBJECTIVE

Nuclear factor-κB (NF-κB) is a critical regulator of inflammatory responses after ICH, and different subunits may have different influences on the cell death and prognosis. The aim of the present study is to clarify whether the prognosis can be influenced by inhibiting NF-κB activation and subunits expression using PDTC at different stages after ICH.

METHODS

Rats were divided into sham group, ICH group, early interference group and late interference group. At preset time points after ICH, the ipsilateral striatum and tissue around was obtained for detection of NF-κB activation, cell death, and expression of caspase-3, bcl-2, and NF-κB subunits, to evaluate of the effect of PDTC.

RESULTS

NF-κB subunit p65 mainly expressed at the early stage after ICH, and c-Rel at the late stage. NF-κB activation can be inhibited at the early stage after ICH by administrating PDTC at 10 min, 1d and 2d after ICH, and at the late stage at 6d,7d and 8d. NF-κB activation inhibition at the early stage was due to p65, and c-Rel at the late stage. Inhibiting p65 expression at the early stage after ICH can reduce the apoptotic factor caspase-3 expression and cell death, and raise the antiapoptotic factor bcl-2. Meanwhile, inhibiting c-Rel expression at the late stage after ICH can lead to the opposite result.

CONCLUSION

Measures of inhibiting NF-κB subunits can be performed to influence the secondary brain damage and prognosis of ICH. We can also speculate that early inhibition of p65 expression and late promotion of c-Rel expression may be a more efficient method to improve the prognosis of ICH.

Pathogenic role of innate immunity in a model of chronic NO inhibition associated with salt overload

Nitric oxide inhibition with N^ω-nitro-l-arginine methyl ester (l-NAME), along with salt overload, leads to hypertension, albuminuria, glomerulosclerosis, glomerular ischemia, and interstitial fibrosis, characterizing a chronic kidney disease (CKD) model. Previous findings of this laboratory and elsewhere have suggested that activation of at least two pathways of innate immunity, Toll-like receptor 4 (TLR4)/NF-κB and nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3 (NLRP3) inflammasome/IL-1β, occurs in several experimental models of CKD and that progression of renal injury can be slowed with inhibition of these pathways. In the present study, we investigated whether activation of innate immunity, through either the TLR4/NF-κB or NLRP3/IL-1β pathway, is involved in the pathogenesis of renal injury in chronic nitric oxide inhibition with the salt-overload model. Adult male Munich-Wistar rats that received l-NAME in drinking water with salt overload (HS + N group) were treated with allopurinol (ALLO) as an NLRP3 inhibitor (HS + N + ALLO group) or pyrrolidine dithiocarbamate (PDTC) as an NF-κB inhibitor (HS + N + PDTC group). After 4 wk, HS + N rats developed hypertension, albuminuria, and renal injury along with renal inflammation, oxidative stress, and activation of both the NLRP3/IL-1β and TLR4/NF-κB pathways. ALLO lowered renal uric acid and inhibited the NLRP3 pathway. These effects were associated with amelioration of hypertension, albuminuria, and interstitial inflammation/fibrosis but not glomerular injury. PDTC inhibited the renal NF-κB system and lowered the number of interstitial cells staining positively for NLRP3. PDTC also reduced renal xanthine oxidase activity and uric acid. Overall, PDTC promoted a more efficient anti-inflammatory and nephroprotective effect than ALLO. The NLRP3/IL-1β and TLR4/NF-κB pathways act in parallel to promote renal injury/inflammation and must be simultaneously inhibited for best nephroprotection.

Murine Double Minute-2 Inhibition Ameliorates Established Crescentic Glomerulonephritis

Rapidly progressive glomerulonephritis is characterized by glomerular necroinflammation and crescent formation. Its treatment includes unspecific and toxic agents; therefore, the identification of novel therapeutic targets is required. The E3-ubiquitin ligase murine double minute (MDM)-2 is a nonredundant element of NF-κB signaling and the negative regulator of tumor suppressor gene TP53-mediated cell cycle arrest and cell death. We hypothesized that the MDM2 would drive crescentic glomerulonephritis by NF-κB-dependent glomerular inflammation and by p53-dependent parietal epithelial cell hyperproliferation. Indeed, the pre-emptive MDM2 blockade by nutlin-3a ameliorated all aspects of crescentic glomerulonephritis. MDM2 inhibition had identical protective effects in Trp53-deficient mice, with the exception of crescent formation, which was not influenced by nutlin-3a treatment. In vitro experiments confirmed the contribution of MDM2 for induction of NF-κB-dependent cytokines in murine glomerular endothelial cells and for p53-dependent parietal epithelial cell proliferation. To evaluate MDM2 blockade as a potential therapeutic intervention in rapidly progressive glomerulonephritis, we treated mice with established glomerulonephritis with nutlin-3a. Delayed onset of nutlin-3a treatment was equally protective as the pre-emptive treatment in abrogating crescentic glomerulonephritis. Together, the pathogenic effects of MDM2 are twofold, that is, p53-independent NF-κB activation increasing intraglomerular inflammation and p53-dependent parietal epithelial cell hyperplasia and crescent formation. We therefore propose MDM2 blockade as a potential novel therapeutic strategy in rapidly progressive glomerulonephritis.

Pyrrolidine dithiocarbamate reduces the progression of total kidney volume and cyst enlargement in experimental polycystic kidney disease

Heterocyclic dithiocarbamates have anti‐inflammatory and anti‐proliferative effects in rodent models of chronic kidney disease. In this study, we tested the hypothesis that pyrrolidine dithiocarbamate (PDTC) reduces the progression of polycystic kidney disease (PKD). Male Lewis polycystic kidney (LPK) rats (an ortholog of Nek8/NPHP9) received intraperitoneal injections of either saline vehicle or PDTC (40 mg/kg once or twice daily) from postnatal weeks 4 until 11. By serial magnetic resonance imaging at weeks 5 and 10, the relative within‐rat increase in total kidney volume and cyst volume were 1.3‐fold (P =0.01) and 1.4‐fold (P < 0.01) greater, respectively, in LPK + Vehicle compared to the LPK + PDTC(40 mg/kg twice daily) group. At week 11 in LPK rats, PDTC attenuated the increase in kidney weight to body weight ratio by 25% (P < 0.01) and proteinuria by 66% (P < 0.05 vs. LPK + Vehicle) but did not improve renal dysfunction. By quantitative whole‐slide image analysis, PDTC did not alter interstitial CD68+ cell accumulation, interstitial fibrosis, or renal cell proliferation in LPK rats at week 11. The phosphorylated form of the nuclear factor (NF)‐κB subunit, p105, was increased in cystic epithelial cells of LPK rats, but was not altered by PDTC. Moreover, PDTC did not significantly alter nuclear expression of the p50 subunit or NF‐κB (p65)‐DNA binding. Kidney enlargement in LPK rats was resistant to chronic treatment with a proteasome inhibitor, bortezomib. In conclusion, PDTC reduced renal cystic enlargement and proteinuria but lacked anti‐inflammatory effects in LPK rats.

Lewis polycystic kidney rats were treated with pyrrolidine dithiocarbamate (PDTC) from weeks 4 to 11. Quantitative analysis of serial magnetic resonance images indicated that over time, the change in total kidney volume was 1.3‐fold higher in PDTC‐treated than in vehicle‐treated rats. PDTC treatment also decreased kidney weight to body weight ratio, renal cystic volume, and proteinuria.

Chronic inhibition of nuclear factor kappa B attenuates aldosterone/salt-induced renal injury

AIMS

Recent studies suggested that nuclear factor kappa B (NF-κB) plays a key role in the pathogenesis of renal injury. This study investigated whether NF-κB inhibition attenuates progressive renal damage in aldosterone/salt-induced renal injury and its mechanisms.

MAIN METHODS

Adult male rats were uninephrectomized and treated with one of the following for 4 weeks: vehicle (0.5% ethanol, subcutaneously); vehicle/1% NaCl (1% NaCl in drinking solution); aldosterone/1% NaCl (1% NaCl in drinking solution and aldosterone, 0.75 μg/h, subcutaneously); or aldosterone/1%NaCl+pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB (100 mg/kg/day, by gavage). The activity of NF-κB was measured by EMSA and immunohistochemistry, CTGF and ICAM-1 were measured by Western blot and real-time PCR, and TGF-β and CTGF were measured by immunohistochemistry.

KEY FINDINGS

Rats that received aldosterone/1% NaCl exhibited hypertension and severe renal injury. Renal cortical mRNA levels of CTGF, TGF-β, ICAM-1 and collagen IV, protein expression of CTGF and ICAM-1, and NF-κB-DNA binding activity were significantly upregulated in rats that received aldosterone/1% NaCl. Treatment with PDTC significantly decreased the percentage of cells positive for CTGF and TGF-β; mRNA levels of CTGF, TGF-β, ICAM-1 and collagen IV, and protein levels of CTGF and ICAM-1 were also inhibited by PDTC.

SIGNIFICANCE

These data suggest that the NF-κB signal pathway plays a role in the progression of aldosterone/salt-induced renal injury.

Preventive effect of a proteasome inhibitor on the formation of accelerated atherosclerosis in rabbits with uremia

Inflammation plays a central role in the pathogenesis of atherosclerosis. This study investigated whether the proteasome inhibitor has the same preventive effect on the formation of accelerated atherosclerosis in rabbits with uremia compared with a NF-kappaB inhibitor. New Zealand white rabbits were subjected to five-sixths nephrectomy (chronic renal failure [CRF]) or to a sham operation. Rats in each group were randomly assigned into three subgroups (n = 24 in each group) and treated with repeated intramuscular injections of proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC for a specified period. Compared with sham rabbits, CRF rabbits displayed typical atherosclerotic changes (endothelial cell damage, intimal thickens, and appearance of foam cells). CRF rabbits had significantly higher levels of proteasome activity, NF-kappaB mRNA, protein, and DNA binding activity as well as tumor necrosis factor-a and proliferative cell nuclear antigen protein expression in aortic wall cells. CRF rabbits also showed lower levels of IkappaBalpha. Compared with CRF rabbits, CRF rabbits treatment with proteasome inhibitor MG132 showed restoration of IkappaBalpha mRNA and protein expression and decreased NF-kappaB DNA binding activity and tumor necrosis factor-a expression. Treatment with either proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC could reverse these pathologic changes in the aortic wall cells of CRF rabbits. A comparison between the inhibitory effects of the two treatments revealed no statistical difference. These results suggest that ubiquitin-proteasome activation play a pivotal role in the pathogenesis of uremia-accelerated atherosclerosis. The ubiquitin-proteasome signaling pathway in aortic cells may therefore be an important target for preventing uremia-accelerated atherosclerosis.

NF-kappaB in renal inflammation

The NF-kappaB family of transcription factors regulates the induction and resolution of inflammation. Two main pathways, classical and alternative, control the nuclear translocation of NF-kappaB. Classical NF-kappaB activation is usually a rapid and transient response to a wide range of stimuli whose main effector is RelA/p50. The alternative NF-kappaB pathway is a more delayed response to a smaller range of stimuli resulting in DNA binding of RelB/p52 complexes. Additional complexity in this system involves the posttranslational modification of NF-kappaB proteins and an ever-increasing range of co-activators, co-repressors, and NF-kappaB complex proteins. Collectively, NF-kappaB regulates the expression of numerous genes that play a key role in the inflammatory response during human and experimental kidney injury. Multiple stimuli activate NF-kappaB through the classical pathway in somatic renal cells, and noncanonical pathway activation by TWEAK occurs in acute kidney injury. Under most test conditions, specific NF-kappaB inhibitors tend to reduce inflammation in experimental kidney injury but not always. Although many drugs in current use clinically influence NF-kappaB activation, there are no data regarding specific NF-kappaB inhibition in human kidney disease.

Inhibition of NF-kappaB ameliorates sepsis-induced downregulation of aquaporin-2/V2 receptor expression and acute renal failure in vivo

Acute renal failure (ARF) is frequently associated with polyuria and urine concentration defects and it is a severe complication of sepsis because it increases the mortality rate. Inhibition of NF-kappaB activation has been suggested to provide a useful strategy for the treatment of septic shock. However, the impact on sepsis-induced ARF is still unclear. Therefore, we examined the effect of pyrrolidine dithiocarbamate (PDTC) and of small interfering RNA (siRNA) silencing NF-kappaB p50/p105 on sepsis-induced downregulation of vasopressin V(2) receptors and aquaporin (AQP)-2 channels using a cecal ligation and puncture (CLP) mouse model. CLP caused a time-dependent downregulation of renal vasopressin V(2) receptor and of AQP2 expression without alterations in plasma vasopressin levels. Renal activation of NF-kappaB in response to CLP was attenuated by PDTC pretreatment, which also attenuated the downregulation of V(2) receptor and AQP2 expression. Furthermore, a strong nuclear staining for the NF-kappaB p50 subunit throughout the whole kidney in response to CLP was observed. siRNA against NF-kappaB p50 attenuated the CLP-induced nuclear translocation of the p50 subunit and the CLP-induced downregulation of V(2) receptor and AQP2 expression. Additionally, PDTC and siRNA pretreatment inhibited the CLP-induced increase in renal TNF-alpha and IL-1beta concentration and NOS-2 mRNA abundance. Moreover, PDTC and siRNA pretreatment ameliorated CLP-induced hypotension and ARF. Our findings suggest that NF-kappaB activation is of importance for the downregulation of AQP2 channel and vasopressin V(2) receptor expression during sepsis. In addition, our data indicate that NF-kappaB inhibition ameliorates sepsis-induced ARF.

Chronic inhibition of nuclear factor-kappaB attenuates renal injury in the 5/6 renal ablation model

Recent studies indicated that the nuclear transcription factor, NF-kappaB, activates a number of proinflammatory genes in subjects with progressive nephropathies. We investigated whether NF-kappaB inhibition limits progressive renal injury in the 5/6 renal ablation model (Nx). Adult male Munich-Wistar rats were subdivided in four groups: S (n = 16), subjected to sham operation; S+PDTC (n = 18), sham-operated rats receiving the NF-kappaB inhibitor pyrrolidine-dithiocarbamate (PDTC; 60 mg x kg(-1) x day(-1)) in drinking water; Nx (n = 16), Nx rats receiving vehicle only; and Nx+PDTC (n = 19), Nx rats given PDTC as above. Thirty days after renal ablation, Nx rats exhibited systemic and glomerular hypertension. Only the former was attenuated by PDTC treatment. Sixty days after renal ablation, Nx rats exhibited marked hypertension, albuminuria and creatinine retention, as well as glomerulosclerosis and cortical interstitial expansion/inflammation. Immunohistochemical analysis of Nx rats showed renal interstitial infiltration by macrophages and by cells staining positively for ANG II and its receptor, AT(1). Glomerular and interstitial cells expressing the p65 subunit of the NF-kappaB system were also found. PDTC treatment attenuated renal injury and inflammation, as well as the density of cells staining positively for the p65 subunit. Activation of the NF-kappaB system plays an important role in the pathogenesis of renal injury in the Nx model. Inhibition of this system may represent a new strategy to prevent the progression of chronic kidney disease.

Protective effects of pyrrolidine dithiocarbamate on myocardium apoptosis induced by adriamycin in rats

BACKGROUND

Effects of pyrrolidine dithiocarbamate (PDTC) on programmed cell death are controversial. It is unclear if PDTC has the protective effects on myocardial apoptosis induced by adriamycin (ADR) in rats. The present study was undertaken to study the protective effects of pyrrolidine dithiocarbamate (PDTC) on myocardium apoptosis induced by adriamycin (ADR) in rats and its mechanisms.

METHODS

Forty male Wistar rats were randomly divided into five groups: control, ADR, ADR+PDTC 50 mg/kg, ADR+PDTC 100 mg/kg and ADR+PDTC 200 mg/kg group. Myocardial apoptosis was detected by electron microscopic examination and TUNEL assay. Myocardium p53 gene expression was examined by RT-PCR analysis. Location and distribution of p53 was observed by immunohistochemical assay. Myocardial expression of p53 protein was assessed by Western blot analysis. Activity of NF-kappaB was evaluated by Electrophoretic Mobility Shift Assay.

RESULTS

Myocardial apoptotic index, expression of p53 mRNA, expression of p53 protein and the binding activity of NF-kappaB decreased significantly in ADR+PDTC groups compared with ADR group. All these change were significantly correlated with dose of PDTC.

CONCLUSION

PDTC has preventive effects on myocardial apoptosis induced by ADR, which is probably associated with inhibiting binding activity of NF-kappa B and further regulating apoptosis-related gene expression and translation, and inhibiting myocardial apoptosis.

Nuclear factor-kappaB activation in diabetic rat kidney: evidence for involvement of P-selectin in diabetic nephropathy

Activation of a transcription factor, nuclear factor-kappaB (NF-kappaB), is a key step in the pathogenesis of diabetic nephropathy. In this study, we investigated the role of P-selectin, a platelet-derived adhesion molecule, in diabetic nephropathy by examining the activation status of NF-kappaB in the renal cortex of streptozotocin (STZ)-treated rats. The STZ treatment induced pathogenetic parameters such as increased creatinine clearance, increased blood glucose and massive albuminuria in a time-dependent manner. Electrophoretic mobility shift assays (EMSAs) with a specific probe, representing the P-selectin gene promoter, revealed the activation status of NF-kappaB in the STZ-treated rats, as judged by the time-dependent increase in the formation of the specific protein-DNA complexes. This increase was associated with the increased pathogenetic parameters. Supershift assays with specific antibodies revealed that p50, but not p52, p65, Rel B, or c-Rel, may be involved in the activation of NF-kappaB, though the component primarily responsible for the increase could not be determined. Western blot analysis confirmed an increase in P-selectin in STZ-treated rats. Notably, treatment with ammonium pyrrolidinedithiocarbamate, an antioxidant and inhibitor of NF-kappaB, inhibited the activation of NF-kappaB in STZ-treated rats and decreased P-selectin in the renal cortical tissue. Our results indicate that expression of the P-selectin gene is induced through the activation of NF-kappaB and that P-selectin may be involved in the pathogenesis of diabetic nephropathy.

Xanthorrhizol has a potential to attenuate the high dose cisplatin-induced nephrotoxicity in mice

Cisplatin is a widely used anticancer drug, but it can produce undesirable side effects such as nephrotoxicity. The present study investigated the effect of xanthorrhizol isolated from Curcuma xanthorrhiza Roxb. (Zingiberaceae) on cisplatin-induced nephrotoxicity in mice. A single dose of cisplatin (45 mg/kg, i.p.) significantly elevated the levels of blood urea nitrogen, serum creatinine, and the kidney to body weight ratio, but the pretreatment of xanthorrhizol (200 mg/kg/day, per os) for 4 days significantly attenuated the cisplatin-induced nephrotoxicity. The preventive effect of xanthorrhizol was more efficacious than that of curcumin with the same amount (200 mg/kg). However, this effect seemed not to be related with the ability of xanthorrhizol to regulate the DNA-binding activities of transcription factors such as nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1). This is first time the preventive effect of xanthorrhizol on cisplatin-induced nephrotoxicity has been demonstrated, and these data suggest that the administration of xanthorrhizol is a promising approach in the treatment of nephrotoxicity caused by cisplatin.

Macrophages in mouse type 2 diabetic nephropathy: correlation with diabetic state and progressive renal injury

BACKGROUND

Macrophage-mediated renal injury has been implicated in progressive forms of glomerulonephritis; however, a role for macrophages in type 2 diabetic nephropathy, the major cause of end-stage renal failure, has not been established. Therefore, we examined whether macrophages may promote the progression of type 2 diabetic nephropathy in db/db mice.

METHODS

The incidence of renal injury was examined in db/db mice with varying blood sugar and lipid levels at 8 months of age. The association of renal injury with the accumulation of kidney macrophages was analyzed in normal db/+ and diabetic db/db mice at 2, 4, 6, and 8 months of age.

RESULTS

In db/db mice, albuminuria and increased plasma creatinine correlated with elevated blood glucose and hemoglobin A1c (HbA1c) levels but not with obesity or hyperlipidemia. Progressive diabetic nephropathy in db/db mice was associated with increased kidney macrophages. Macrophage accumulation and macrophage activation in db/db mice correlated with hyperglycemia, HbA1c levels, albuminuria, elevated plasma creatinine, glomerular and tubular damage, renal fibrosis, and kidney expression of macrophage chemokines [monocyte chemoattractant protein-1 (MCP-1), osteopontin, migration inhibitory factor (MIF), monocyte-colony-stimulating factor (M-CSF)]. The accrual and activation of glomerular macrophages also correlated with increased glomerular IgG and C3 deposition, which was itself dependent on hyperglycemia.

CONCLUSION

Kidney macrophage accumulation is associated with the progression of type 2 diabetic nephropathy in db/db mice. Macrophage accumulation and activation in diabetic db/db kidneys is associated with prolonged hyperglycemia, glomerular immune complex deposition, and increased kidney chemokine production, and raises the possibility of specific therapies for targeting macrophage-mediated injury in diabetic nephropathy.

Pyrrolidine dithiocarbamate reduces renal dysfunction and injury caused by ischemia/reperfusion of the rat kidney

Dithiocarbamates can modulate the expression of genes associated with inflammation or development of ischemia/reperfusion injury. Here, we investigate the effects of pyrrolidine dithiocarbamate, an inhibitor of nuclear factor (NF)-kappaB activation, on the renal dysfunction and injury caused by ischemia/reperfusion of the rat kidney. Bilateral clamping of renal pedicles (45 min) followed by reperfusion (6 h) caused significant renal dysfunction and marked renal injury. Pyrrolidine dithiocarbamate (100 mg/kg, administered i.v.) significantly reduced biochemical and histological evidence of renal dysfunction and injury caused by ischemia/reperfusion of the rat kidney. Furthermore, pyrrolidine dithiocarbamate markedly reduced the expression of inducible nitric oxide synthase (iNOS) protein and significantly reduced serum levels of nitric oxide. Finally, pyrrolidine dithiocarbamate inhibited the activation of NF-kappaB by preventing its translocation from the cytoplasm into the nuclei of renal cells. These results demonstrate that pyrrolidine dithiocarbamate reduces renal ischemia/reperfusion injury and that dithiocarbamates may provide beneficial actions against ischemic acute renal failure.