SP600125, a selective JNK inhibitor, protects ischemic renal injury via suppressing the extrinsic pathways of apoptosis

The important role of TLR2/MyD88/JNK in regulating the pathogenesis and inflammation induced by pseudorabies virus in mice

The host innate immune response plays a critical role in regulating and controlling viral infections by releasing inflammatory cytokines. Pseudorabies virus (PRV), a swine alphaherpesvirus, can cause severe encephalitis in piglets and various non-natural hosts. Previous studies demonstrated that PRV infection induced the significant elevation of pro-inflammatory cytokines levels and lethal inflammatory response in the mouse model. However, the underlying mechanisms responsible for activation and production of pro-inflammatory cytokines during PRV infection remain to be fully elucidated. In this study, we confirmed that PRV induced significant inflammatory response in C57BL/6 mice during its acute infection. Furthermore, TLR2/MyD88 axis was shown to be associated with the pathogenesis of PRV in mice. Specifically, TLR2/MyD88 axis was required for PRV-induced activation of NF-κB pathway and the subsequent pro-inflammatory cytokines expression. Meanwhile, MAPK/JNK and PI3K/Akt signaling pathways were also activated by TLR2/MyD88 axis and involved in regulating pro-inflammatory cytokines expression induced by PRV infection, respectively. Notably, administration of the JNK inhibitor (SP600125) could reduce clinical symptoms, alleviate pathological damage and prolong survival time of mice infected by PRV. Overall, this study strengthens our understanding upon the mechanism of host inflammatory response induced by PRV, and suggests that JNK signaling may act as a therapeutic target in controlling of PRV infection.

c-Jun N-terminal Kinase Supports Autophagy in Testicular Ischemia but Triggers Apoptosis in Ischemia-Reperfusion Injury

Oxidative stress triggered by testicular torsion and detorsion in young males could negatively impact future fertility. Using a rat animal model for testicular IRI (tIRI), we aim to study the induction of autophagy (ATG) during testicular ischemia and tIRI and the role of oxidative-stress-induced c-Jun N-terminal Kinase (JNK) as a cytoprotective mechanism. Sixty male Sprague-Dawley rats were divided into five groups: sham, ischemia only, ischemia+SP600125 (a JNK inhibitor), tIRI only, and tIRI+SP600125. The tIRI rats underwent an ischemic injury for 1 h followed by 4 h of reperfusion, while ischemic rats were subjected to 1 h of ischemia only without reperfusion. Testicular-ischemia-induced Beclin 1 and LC3B expression was associated with decreased p62/SQSTM1 expression, increased ATP and alkaline phosphatase (AP) activity, and slightly impaired spermatogenesis. SP600125 treatment improved p62 expression and reduced the levels of Beclin 1 and LC3B but did not affect ATP or AP levels. The tIRI-induced apoptosis lowered the expression of the three ATG proteins and AP activity, activated caspase 3, and caused spermatogenic arrest. SP600125-inhibited JNK during tIRI restored sham levels to all investigated parameters. This study emphasizes the regulatory role of JNK in balancing autophagy and apoptosis during testicular oxidative injuries.

JUN Amino-Terminal Kinase 1 Signaling in the Proximal Tubule Causes Cell Death and Acute Renal Failure in Rat and Mouse Models of Renal Ischemia/Reperfusion Injury

Activation of the JUN amino-terminal kinase (JNK) pathway is prominent in most forms of acute and progressive tubulointerstitial damage, including acute renal ischemia/reperfusion injury (IRI). Two forms of JNK, JNK1 and JNK2, are expressed in the kidney. Systemic administration of pan-JNK inhibitors suppresses renal IRI; however, the contribution of JNK1 versus JNK2, and the specific role of JNK activation in the proximal tubule in IRI, remains unknown. These questions were addressed in rat and mouse models of acute bilateral renal IRI. Administration of the JNK inhibitor, CC-930, substantially reduced the severity of renal failure, tubular damage, and inflammation at 24 hours in a rat IRI model. Additionally, Jnk1^-/- mice, but not Jnk2^-/- mice, were shown to be significantly protected against acute renal failure, tubular damage, and inflammation in the IRI model. Furthermore, mice with conditional Jnk1 deletion in the proximal tubule also showed considerable protection from IRI-induced renal failure, tubular damage, and inflammation. Finally, primary cultures of Jnk1^-/-, but not Jnk2^-/-, tubular epithelial cells were protected from oxidant-induced cell death, in association with preventing phosphorylation of proteins (receptor interacting serine/threonine kinase 3 and mixed lineage kinase domain-like pseudokinase) in the necroptosis pathway. In conclusion, JNK1, but not JNK2, plays a specific role in IRI-induced cell death in the proximal tubule, leading to acute renal failure.

c-Jun Amino Terminal Kinase Signaling Promotes Aristolochic Acid-Induced Acute Kidney Injury

Aristolochic acid (AA) is a toxin that induces DNA damage in tubular epithelial cells of the kidney and is the cause of Balkan Nephropathy and Chinese Herb Nephropathy. In cultured tubular epithelial cells, AA induces a pro-fibrotic response via the c-Jun amino terminal kinase (JNK) signaling pathway. This study investigated the in vivo role of JNK signaling with a JNK inhibitor (CC-930) in mouse models of acute high dose AA-induced kidney injury (day 3) and renal fibrosis induced by chronic low dose AA exposure (day 22). CC-930 treatment inhibited JNK signaling and protected from acute AA-induced renal function impairment and severe tubular cell damage on day 3, with reduced macrophage infiltration and expression of pro-inflammatory molecules. In the chronic model, CC-930 treatment inhibited JNK signaling but did not affect AA-induced renal function impairment, tubular cell damage including the DNA damage response and induction of senescence, or renal fibrosis; despite a reduction in the macrophage pro-inflammatory response. In conclusion, JNK signaling contributes to acute high dose AA-induced tubular cell damage, presumably via an oxidative stress-dependent mechanism, but is not involved in tubular atrophy and senescence that promote chronic kidney disease caused by ongoing DNA damage in chronic low dose AA exposure.

Molecular mechanism of mice gastric oxidative damage induced by nanoparticulate titanium dioxide

Background

Nanoparticulate titanium dioxide (Nano-TiO₂) has been widely used in food industry, and it has been demonstrated to have adverse effects on mice and human stomach, but its mechanism is rarely concerned. The aim of this study is to determine the effects of nano-TiO₂ on the stomach and confirm the role of oxidative stress and apoptosis in the mice gastric damage caused by nano-TiO₂, as well as its molecular mechanisms.

Methods

Mice were continuously exposed to nano-TiO₂ with 1.25, 2.5 and 5 mg/kg bw by intragastric administration for 9 months in the present study. The ultrastructure, levels of reactive oxygen species (ROS) and peroxides, activities of antioxidant enzymes and mitochondria-related enzymes, ATP contents as well as apoptosis-related factors expression in mice stomach were examined.

Results

Oxidative stress, apoptosis and nano-TiO₂ aggregation were found in gastric mucosal smooth muscle cells after nano-TiO₂ exposure. Nano-TiO₂ exposure also resulted in the over-production of ROS and peroxides, decrease of ATP production and activities of antioxidant enzymes and mitochondria-related ATPases, upregulation of apoptosis-related factors including γH2AX, Cyt c, caspase 3, and p-JNK expression, and down-regulation of Bcl-2 expression in mice stomach.

Conclusions

The gastric toxicity of mice induced by chronic exposure to low dose nano-TiO₂ may be associated with oxidative stress and mitochondria-mediated apoptosis in mice.

JNK inhibition alleviates oxidative DNA damage, germ cell apoptosis, and mitochondrial dysfunction in testicular ischemia reperfusion injury

The aim of this study is to determine whether the c-Jun N-terminal kinase (JNK) signaling is a regulator of oxidative DNA damage, germ cell apoptosis (GCA), and mitochondrial dysfunction during testicular ischemia reperfusion injury (tIRI) using the JNK inhibitor SP600125. Male Sprague Dawley rats (n = 36) were equally divided into three groups: sham, tIRI only, and tIRI + SP600125 (15 mg/kg). Testicular ischemia was induced for 1 h followed by 4 h of reperfusion prior to animal sacrifice. Spermatogenesis was evaluated by light microscopy, while expression of oxidative stress and GCA-related mRNAs and proteins were evaluated by real-time polymerase chain reaction and colorimetric assays, respectively. Expressions of JNK, p53, and survivin were detected by immunofluorescence (IF) staining. Indicators of mitochondrial dysfunction were examined by western blot analysis and colorimetric assay. In comparison to sham, the tIRI testes showed a significant increase in lipid and protein oxidation products. Oxidative DNA damage was reflected by a significant increase in the number of DNA strand breaks, increased concentration of 8-OHdG, and elevated poly (ADP-ribose) polymerase activity. Spermatogenic damage was associated with the activation of caspase 3 and elevated Bax to Bcl2 ratio. This was also accompanied by a significantly heightened IF expression of the phosphorylated forms of JNK and p53 paralled with the suppression of survivin. Mitochondrial dysfunction was reflected by NAD+ depletion, overexpression of uncoupling protein 2, and increased level of cytochrome c. Such tIRI-induced modulations were all attenuated by SP600125 treatment prior to reperfusion. In conclusion, JNK signaling regulates oxidative DNA damage, GCA, and mitochondrial dysfunction through activation of p53 and suppression of survivin during tIRI.

The effects of inhibiting the activation of hepatic stellate cells by lignan components from the fruits of Schisandra chinensis and the mechanism of schisanhenol

Liver fibrosis is a pathological manifestation induced by chronic liver injury and may cause cirrhosis and liver cancer with the chronic progression of fibrosis. During the onset and progression of liver fibrosis, the activation of hepatic stellate cells (HSCs) is the core mechanism for the secretion of many extracellular matrices to induce fibrosis. Lignans are reportedly the main effective components of Schisandra chinensis with good anti-fibrosis effects. In this study, we compared the inhibiting effects of the seven lignan components from S. chinensis on HSC activation. We found that the seven lignans inhibited the activation of human HSCs (LX-2) in various degrees. Among all lignans, schisanhenol showed the best effect in inhibiting the activation of LX-2 with a dose-effect relationship. Sal also inhibited the phosphorylations of Smad1, Smad2, Smad3, extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), p38, and nuclear transcription factor-κB (NF-κB), as well as downregulated Smad4. All these findings suggested that schisanhenol may ameliorate liver fibrosis by inhibiting the transforming growth factor β (TGF-β)/Smad and mitogen-activated protein kinase (MAPK) signaling pathways. Remarkably, schisanhenol may be a potential anti-liver fibrosis drug and warrants further research.

SIRT2-mediated FOXO3a deacetylation drives its nuclear translocation triggering FasL-induced cell apoptosis during renal ischemia reperfusion

We have found that Fas/FasL-mediated "extrinsic" pathway promoted cell apoptosis induced by renal ischemic injury. This study is to elucidate the upstream mechanism regulating FasL-induced extrinsic pathway during renal ischemia/reperfusion. Results demonstrated that when SIRT2 was activated by renal ischemia/reperfusion, activated SIRT2 could bind to and deacetylate FOXO3a, promoting FOXO3a nuclear translocation which resulted in an increase of nuclear FOXO3a along with FasL expression and activation of caspase8 and caspase3, triggering cell apoptosis during renal ischemia/reperfusion. The administration of SIRT2 inhibitor AGK2 prior to renal ischemia decreased significantly the number of apoptotic renal tubular cells and alleviated ultrastructure injury. These results indicate that inhibition of FOXO3a deacetylation might be a promising therapeutic approach for renal ischemia /reperfusion injury.

Chemical Characterization of a Renoprotective Metabolite from Termite-Associated Streptomyces sp. RB1 against Cisplatin-Induced Cytotoxicity

Platinum-based anticancer drug therapies can cause renal damage and apoptotic kidney cell damage. The development of reno- and kidney-protective molecules is therefore urgently required. To address this challenge, we explored secondary metabolites of termite-associated Streptomyces sp. RB1 isolated from the cuticle of the South African termite, Macrotermes natalensis for their renoprotective ability using bioassay-guided fractionation and LLC-PK1 cells. Chemical investigation of the MeOH extract of Streptomyces sp. RB1 resulted in the isolation and identification of a renoprotective metabolite, 1-O-(2-aminobenzoyl)-α-l-rhamnopyranoside (ABR) (1) from the active fraction, which ameliorated cisplatin-induced cytotoxicity to 80% of the control value at 25 μM. Upregulated phosphorylation of c-Jun N-terminal kinases (JNK) and p38 following cisplatin treatment was markedly decreased after pre-treatment of cells with ABR. In addition, levels of cleaved caspase-3 and the percentage of apoptotic cells were also significantly reduced after pre-treatment with ABR. These findings provide experimental evidence that blocking the MAPK signaling cascade plays a critical role in mediating the renoprotective effect of ABR, which may inspire the development of novel therapeutic substances to prevent anticancer drug-induced nephrotoxicity.

The JNK Signaling Pathway in Renal Fibrosis

Fibrosis of the glomerular and tubulointerstitial compartments is a common feature of chronic kidney disease leading to end-stage renal failure. This fibrotic process involves a number of pathologic mechanisms, including cell death and inflammation. This review focuses on the role of the c-Jun amino terminal kinase (JNK) signaling pathway in the development of renal fibrosis. The JNK pathway is activated in response to various cellular stresses and plays an important role in cell death and inflammation. Activation of JNK signaling is a common feature in most forms of human kidney injury, evident in both intrinsic glomerular and tubular cells as well as in infiltrating leukocytes. Similar patterns of JNK activation are evident in animal models of acute and chronic renal injury. Administration of JNK inhibitors can protect against acute kidney injury and suppress the development of glomerulosclerosis and tubulointerstitial fibrosis. In particular, JNK activation in tubular epithelial cells may be a pivotal mechanism in determining the outcome of both acute kidney injury and progression of chronic kidney disease. JNK signaling promotes tubular epithelial cell production of pro-inflammatory and pro-fibrotic molecules as well as tubular cell de-differentiation toward a mesenchymal phenotype. However, the role of JNK within renal fibroblasts is less well-characterized. The JNK pathway interacts with other pro-fibrotic pathways, most notable with the TGF-β/SMAD pathway. JNK activation can augment TGF-β gene transcription, induce expression of enzymes that activate the latent form of TGF-β, and JNK directly phosphorylates SMAD3 to enhance transcription of pro-fibrotic molecules. In conclusion, JNK signaling plays an integral role in several key mechanisms operating in renal fibrosis. Targeting of JNK enzymes has therapeutic potential for the treatment of fibrotic kidney diseases.

High resolution molecular and histological analysis of renal disease progression in ZSF1 fa/faCP rats, a model of type 2 diabetic nephropathy

ZSF1 rats exhibit spontaneous nephropathy secondary to obesity, hypertension, and diabetes, and have gained interest as a model system with potentially high translational value to progressive human disease. To thoroughly characterize this model, and to better understand how closely it recapitulates human disease, we performed a high resolution longitudinal analysis of renal disease progression in ZSF1 rats spanning from early disease to end stage renal disease. Analyses included metabolic endpoints, renal histology and ultrastructure, evaluation of a urinary biomarker of fibrosis, and transcriptome analysis of glomerular-enriched tissue over the course of disease. Our findings support the translational value of the ZSF1 rat model, and are provided here to assist researchers in the determination of the model’s suitability for testing a particular mechanism of interest, the design of therapeutic intervention studies, and the identification of new targets and biomarkers for type 2 diabetic nephropathy.

Aquaporin-3 deletion in mice results in renal collecting duct abnormalities and worsens ischemia-reperfusion injury

Aquaporin-3 (AQP3), a transporter of water, glycerol and H₂O₂, is expressed in basolateral membranes of principal cells in kidney collecting duct. Here, we report that AQP3 deletion in mice affects renal function and modulates renal injury. We found collecting duct hyperplasia and cell swelling in kidneys of adult AQP3 null mice. After mild renal ischemia-reperfusion (IR), AQP3 null mice had significantly greater blood urea nitrogen (57mg/dl) and creatinine (136μM) than wild-type mice (35mg/dl and 48μM, respectively), and showed renal morphological changes, including tubular dilatation, erythrocyte diapedesis and collecting duct incompletion. MPO, MDA and SOD following IR in AQP3 null mice were significantly different from that in wild-type mice (1.7U/g vs 0.8U/g, 3.9μM/g vs 2.4μM/g, 6.4U/mg vs 11U/mg, respectively). Following IR, AQP3 deletion inhibited activation of mitogen-activated protein kinase (MAPK) signaling and produced an increase in the ratios of Bax/Bcl-2, cleaved caspase-3/caspase-3 and p-p53/p53. Studies in transfected MDCK cells showed that AQP3 expression attenuated reduced cell viability following hypoxia-reoxygenation, with reduced apoptosis and increased MAPK signaling. Our results support a novel role for AQP3 in modulating renal injury and suggest the mechanisms involved in protection against hypoxic injury.

Ischemia/Reperfusion

Ischemic disorders, such as myocardial infarction, stroke, and peripheral vascular disease, are the most common causes of debilitating disease and death in westernized cultures. The extent of tissue injury relates directly to the extent of blood flow reduction and to the length of the ischemic period, which influence the levels to which cellular ATP and intracellular pH are reduced. By impairing ATPase-dependent ion transport, ischemia causes intracellular and mitochondrial calcium levels to increase (calcium overload). Cell volume regulatory mechanisms are also disrupted by the lack of ATP, which can induce lysis of organelle and plasma membranes. Reperfusion, although required to salvage oxygen-starved tissues, produces paradoxical tissue responses that fuel the production of reactive oxygen species (oxygen paradox), sequestration of proinflammatory immunocytes in ischemic tissues, endoplasmic reticulum stress, and development of postischemic capillary no-reflow, which amplify tissue injury. These pathologic events culminate in opening of mitochondrial permeability transition pores as a common end-effector of ischemia/reperfusion (I/R)-induced cell lysis and death. Emerging concepts include the influence of the intestinal microbiome, fetal programming, epigenetic changes, and microparticles in the pathogenesis of I/R. The overall goal of this review is to describe these and other mechanisms that contribute to I/R injury. Because so many different deleterious events participate in I/R, it is clear that therapeutic approaches will be effective only when multiple pathologic processes are targeted. In addition, the translational significance of I/R research will be enhanced by much wider use of animal models that incorporate the complicating effects of risk factors for cardiovascular disease. © 2017 American Physiological Society. Compr Physiol 7:113-170, 2017.

Gonadal steroids block the calpain-1-dependent intrinsic pathway of apoptosis in an experimental rat stroke model

OBJECTIVES

Apoptosis plays an important role in the progression of the ischemic penumbra after reperfusion. Estrogen and progesterone have neuroprotective effects against ischemic brain damage, however the exact mechanisms of neuroprotection and signaling pathways is not completely understood. In this study, we investigated the possible regulatory effects of a combined steroid treatment on extrinsic and intrinsic apoptotic signaling pathways after cerebral ischemia.

METHODS

Adult male Wistar rats were subjected to transient middle cerebral artery occlusion (tMCAO) using an intraluminal filament technique for 1 h followed by 23 h reperfusion. Estrogen and progesterone were immediately injected after tMCAO subcutaneously. Sensorimotor functional tests and the infarct volume were evaluated 24 h after ischemia. Protein expression of calpain-1 and Fas receptor (FasR), key members of intrinsic and extrinsic apoptosis, were determined in the penumbra region of the ischemic brain using western blot analysis, immunohistochemistry, and TUNEL staining.

RESULTS

Neurological deficits and infarct volume were significantly reduced following hormone therapy. Calpain-1 up-regulation and caspase-3 activation were apparent 24 h after ischemia in the peri-infarct area of the cerebral cortex. Steroid hormone treatment reduced infarct pathology and attenuated the induction of both proteases. FasR protein levels were not affected by ischemia and hormone application.

CONCLUSION

We conclude that a combined steroid treatment inhibits ischemia-induced neuronal apoptosis through the regulation of intrinsic pathways.

Pharmacokinetic and tissue distribution studies of 1,9-pyrazoloanthrone, a c-Jun-N-terminal kinase inhibitor in Wistar rats by a simple and sensitive HPLC method

JNK pathway activates c-Jun(s) which are responsible for cell apoptosis; as a result, inhibitors of JNK pathway have the potential to prevent dopaminergic neurons from death and decrease the loss of dopamine in substantia nigra pars compacta (SNpc). Recent in-vitro studies show that 1,9-pyrazoloanthrone (1,9-P) a potent JNK-3 inhibitor prevents the apoptosis of dopaminergic cells of brain. In the present study we formulated liposomes to increase the bioavailability of 1,9-P in the brain and developed a simple, sensitive and selective high performance liquid chromatographic method and validated for the estimation of 1,9-P in Wistar rat plasma and tissue samples. Plasma and tissue samples were extracted by protein precipitation technique using acetonitrile (ACN) and rasagiline as the internal standards. Chromatography was performed on Hibar C18 column with mobile phase of ammonium acetate (10mM, pH 8.0 adjusted with ammonia) and ACN at a flow rate of 1mL/min. The lower limit of quantification of the developed method was found to be 2.0ng/mL and 4.0ng/g in plasma and tissue samples respectively. The liposomes of 1,9-P administered to animals at the dose equivalent to 15mg/kg orally demonstrated remarkable absorption into the systemic circulation with maximum concentration (∼7500ng/mL) within 2.0h. The order of the area under curve was found to be kidney>liver>brain>lungs>spleen>heart. The liposomes of 1,9-P were rapidly taken up into brain and showed a good brain concentration after 2.0h; sustenance up to 4.0h was achieved which is better than 1,9-P solution.

Inhibitory effects of PPARγ ligands on TGF-β1-induced CTGF expression in cat corneal fibroblasts

Ligands of Peroxisome Proliferator Activated Receptor gamma (PPARγ) possess strong anti-fibrotic properties in the cornea and several other body tissues. In the cornea, we recently showed this class of molecules to prevent stromal myofibroblast differentiation partially by blocking the actions of p38 mitogen-activated protein kinase (MAPK). However, given the important role assigned to connective tissue growth factor (CTGF) in mediating corneal fibrosis, here we asked whether PPARγ ligands also act by affecting transforming growth factor-β (TGF-β) 1-induced expression of CTGF in cultured corneal fibroblasts. Corneal keratocytes were isolated from young, adult cats and early passage cells were exposed to TGF-β1 with or without the PPARγ ligands Rosiglitazone, Troglitazone and 15d-PGJ2. Western blots were used to assay levels of CTGF and alpha smooth muscle actin (αSMA), a marker of myofibroblast differentiation. CTGF siRNA demonstrated a critical role for CTGF in TGF-β1-mediated myofibroblast differentiation, while exogenously applied CTGF potentiated the pro-fibrogenic effects of TGF-β1. TGF-β1-mediated increases in CTGF and αSMA expression were strongly inhibited by all three PPARγ ligands tested, and by a c-jun N-terminal kinase (JNK) inhibitor. However, while extracellular signal-regulated kinase (ERK) 1/2, protein kinase B (AKT) and p38 MAPK inhibitors also blocked TGF-β1-induced αSMA induction, they did not dampen TGF-β1-induced increases in levels of CTGF. Thus, we conclude that PPARγ ligands block TGF-β1-induced increases in CTGF levels in cat corneal fibroblasts. They appear to do this in addition to their anti-fibrotic effect on p38 MAPK, providing a second intracellular pathway by which PPARγ ligands block αSMA induction.

Protective effects of SP600125 in brain death-induced liver injury

The aim of the present study was to investigate the protective effect of SP600125, a selective c-Jun N-terminal kinase inhibitor, in brain death-induced liver injury. All 40 Sprague-Dawley rats are anesthetized. Analysis of liver histology, function, JNK phosphorylation status, as well as apoptosis related protein was evaluated in this study. As a result, SP600125 diminished the increased phosphorylation of JNK, whereas, expression of total JNK in the liver remained unchanged compared with the sham control and was not affected by SP600125. At the same time, SP600125 attenuated Bax translocation to mitochondria and the release of cytochrome c induced by brain death. Furthermore, the activation of caspase-3 and apoptosis induced by brain death was also significantly suppressed by the administration of SP600125. The results obtained from the present study suggested that targeting the JNK pathway provided a therapeutic target in liver injury induced by brain death.

Effect of cell permeable peptide of c-Jun NH2-terminal kinase inhibitor on the attenuation of renal ischemia-reperfusion injury in pigs

The outcomes of organ transplantation have improved due to better immunosuppressive drugs, surgical techniques, and management of complications. However, ischemia-reperfusion injury remains a challenge affecting graft survival. In this study, we employed injection of a protein transduction domain (PTD) to inhibit the c-Jun NH2-terminal kinase (JNK) pathway thereby attenuating ischemia-reperfusion injury in a porcine model. The PTD-JNK inhibitor (JNKI) was administered into the renal artery, allowing it to be taken into various elements including vascular endothelial cells by endocytosis via the PTD. Serum creatinine and blood urea nitrogen concentrations were lower among PTD-JNKI than controls. In addition, renal tissue blood flow was maintained in the PTD-JNKI group, resulting in less tissue injury and fewer apoptotic cells. These results suggested that the PTD technique improved renal transplantation outcomes.

Protective effect of N-acetylcysteine (NAC) on renal ischemia/reperfusion injury through Nrf2 signaling pathway

The aim of this study was to investigate whether N-acetylcysteine (NAC), a known antioxidant, can protect kidney against ischemic injury through regulating Nrf2 signaling pathway. The expression of Nrf2, HO-1 and cleaved caspase 3 were analyzed by Western blot analysis. Apoptosis of renal tubular epithelial cells was assessed by the TUNEL method. Malondialdehyde (MDA) levels were measured by the thiobarbituric acid reaction. Blood serum creatinine and blood urea nitrogen levels were measured with an Olympus automatic multi-analyzer. We found that NAC significantly increased Nrf2 and downstream HO-1 expression. Furthermore, NAC significantly decreased cleaved caspase 3, p53 and renal epithelial tubular cell apoptosis. In addition, NAC reduced the MDA level. These findings suggest that the protective action of NAC on ischemia renal injury is associated closely with Nrf2 signaling pathway.

Inhibitory effects of PPARγ ligands on TGF-β1-induced corneal myofibroblast transformation

Corneal scarring, whether caused by trauma, laser refractive surgery, or infection, remains a significant problem for humans. Certain ligands for peroxisome proliferator-activated receptor gamma (PPARγ) have shown promise as antiscarring agents in a variety of body tissues. In the cornea, their relative effectiveness and mechanisms of action are still poorly understood. Here, we contrasted the antifibrotic effects of three different PPARγ ligands (15-deoxy-Δ12,14-prostaglandin J2, troglitazone, and rosiglitazone) in cat corneal fibroblasts. Western blot analyses revealed that all three compounds reduced transforming growth factor (TGF)-β1-driven myofibroblast differentiation and up-regulation of α-smooth muscle actin, type I collagen, and fibronectin expression. Because these effects were independent of PPARγ, we ascertained whether they occurred by altering phosphorylation of Smads 2/3, p38 mitogen-activated protein kinase, stress-activated protein kinase, protein kinase B, extracellular signal-regulated kinase, and/or myosin light chain 2. Only p38 mitogen-activated protein kinase phosphorylation was significantly inhibited by all three PPARγ ligands. Finally, we tested the antifibrotic potential of troglitazone in a cat model of photorefractive keratectomy-induced corneal injury. Topical application of troglitazone significantly reduced α-smooth muscle actin expression and haze in the stromal ablation zone. Thus, the PPARγ ligands tested here showed great promise as antifibrotics, both in vitro and in vivo. Our results also provided new evidence for the signaling pathways that may underlie these antifibrotic actions in corneal fibroblasts.

Valproic acid protects motor neuron death by inhibiting oxidative stress and endoplasmic reticulum stress-mediated cytochrome C release after spinal cord injury

Both oxidative stress and endoplasmic reticulum (ER) stress are known to contribute to secondary injury, ultimately leading to cell death after spinal cord injury (SCI). Here, we showed that valproic acid (VPA) reduced cell death of motor neurons by inhibiting cytochrome c release mediated by oxidative stress and ER stress after SCI. After SCI, rats were immediately injected with VPA (300 mg/kg) subcutaneously and further injected every 12 h for an indicated time period. Motor neuron cell death at an early time after SCI was significantly attenuated by VPA treatment. Superoxide anion (O2-) production and inducible NO synthase (iNOS) expression linked to oxidative stress was increased after injury, which was inhibited by VPA. In addition, VPA inhibited c-Jun N-terminal kinase (JNK) activation, which was activated and peaked at an early time after SCI. Furthermore, JNK activation and c-Jun phosphorylation were inhibited by a broad-spectrum reactive oxygen species (ROS) scavenger, Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), indicating that ROS including O2- increased after SCI probably contribute to JNK activation. VPA also inhibited cytochrome c release and caspase-9 activation, which was significantly inhibited by SP600125, a JNK inhibitor. The levels of phosphorylated Bim and Mcl-1, which are known as downstream targets of JNK, were significantly reduced by SP600125. On the other hand, VPA treatment inhibited ER stress-induced caspase-12 activation, which is activated in motor neurons after SCI. In addition, VPA increased the Bcl-2/Bax ratio and inhibited CHOP expression. Taken together, our results suggest that cell death of motor neurons after SCI is mediated through oxidative stress and ER stress-mediated cytochrome c release and VPA-inhibited cytochrome c release by attenuating ROS-induced JNK activation followed by Mcl-1 and Bim phosphorylation and ER stress-coupled CHOP expression.

Low molecular weight fucoidan against renal ischemia-reperfusion injury via inhibition of the MAPK signaling pathway

BACKGROUND

Ischemia reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI) in both native and transplanted kidneys. The objective of the present study was to evaluate whether low-molecular-weight fucoidan (LMWF) could attenuate renal IRI in an animal model and in vitro cell models and study the mechanisms in which LMWF protected from IRI.

METHODOLOGY/PRINCIPAL FINDINGS

Male mice were subjected to right renal ischemia for 30 min and reperfusion for 24 h, or to a sham operation with left kidney removed. Kidneys undergone IR showed characteristic morphological changes, such as tubular dilatation, and brush border loss. However, LMWF significantly corrected the renal dysfunction and the abnormal levels of MPO, MDA and SOD induced by IR. LMWF also inhibited the activation of MAPK pathways, which consequently resulted in a significant decrease in the release of cytochrome c from mitochondria, ratios of Bax/Bcl-2 and cleaved caspase-3/caspase-3, and phosphorylation of p53. LMWF alleviated hypoxia-reoxygenation or CoCl(2) induced cell viability loss and ΔΨm dissipation in HK2 renal tubular epithelial cells, which indicates LMWF may result in an inhibition of the apoptosis pathway through reducing activity of MAPK pathways in a dose-dependent manner.

CONCLUSIONS/SIGNIFICANCE

Our in vivo and in vitro studies show that LMWF ameliorates acute renal IRI via inhibiting MAPK signaling pathways. The data provide evidence that LMWF may serve as a potential therapeutic agent for acute renal IRI.

Identification of an Adamantyl Azaquinolone JNK Selective Inhibitor

3-[4-((1S,2S,3R,5S,7S)-5-Hydroxyadamantan-2-ylcarbamoyl)benzyl]-4-oxo-1-phenyl-1,4-dihydro-[1,8]naphthyridine-2-carboxylic acid methyl ester (4) was identified as a novel, druglike and selective quinolone pan JNK inhibitor. In this communication, some of the structure-activity relationship of the azaquinolone analogues leading to 4 is discussed. The focus is on how changes at the amide functionality affected the biochemical potency, cellular potency, metabolic properties, and solubility of this class of JNK inhibitors. Optimization of these properties led to the identification of the adamantyl analogue, 4. 4 achieved proof of mechanism in both rat and mouse TNF-α challenge models.

Salidroside and tyrosol from Rhodiola protect H9c2 cells from ischemia/reperfusion-induced apoptosis

AIMS

Heart disease is the leading cause of death worldwide. Ischemia-reperfusion injury can lead to apoptotic death of heart cells and subsequently heart failure. Rhodiola is an herbal medicine with two main bioactive compounds--salidroside (SAL) and tyrosol (TYR). This study aimed to investigate whether these two compounds can prevent ischemia/reperfusion-induced apoptosis in H9c2 cells.

MAIN METHODS

Assays for total phenolics assay and Oxygen Radical Absorbance Capacity showed high antioxidant capacity of SAL and TYR. H9c2 cells were subjected to simulated ischemia/reperfusion (IR) in the presence and absence of SAL and/or TYR, and nuclei condensation, caspase-3 activity, cytochrome c release and JNK phosphorylation were determined.

KEY FINDINGS

In H9c2 cells, IR can lead to a 5-fold increase in p-JNK level. Apoptotic nuclei condensation, caspase-3 activity and cytochrome c release were markedly elevated, indicating the occurrence of apoptosis. SAL and TYR caused a dose-dependent inhibition of nuclear condensation. Furthermore, SAL and TYR, separately and in combination, significantly reduced caspase-3 activity, cytochrome c release and JNK activation. The anti-apoptotic effect of the combination was markedly higher than that of SAL or TYR alone.

SIGNIFICANCE

The inhibition of the JNK signaling pathway is the key mechanism for the cytoprotective effect of SAL and TYR in IR-induced apoptosis.

Effects of c-Jun N-terminal kinase signaling pathway on severe acute pancreatitis-associated lung injury

OBJECTIVE

The objective of this study was to investigate the effects of the c-Jun N-terminal kinase (JNK) signaling pathway on rats' acute pancreatitis-associated lung injury (APALI).

METHODS

Seventy-two Sprague-Dawley rats were randomly divided into 3 groups, namely, the sham operation (SO) group, the severe acute pancreatitis (SAP) group, and the SP600125 group. The SAP model was established by injection of 5% sodium taurocholate into the pancreatic duct. The samples were taken at 3, 6, 12, and 24 hours. Serum amylase, pathologic lesions of the pancreas and lung tissues, wet-to-dry weight ratio of the lung, myeloperoxidase (MPO) activity of the lung, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), intercellular adhesion molecule 1 (ICAM-1), and p-JNK of lung tissues were detected.

RESULTS

The wet-to-dry weight ratio, MPO activity, and IL-1β, TNF-α, ICAM-1, and p-JNK levels in the SAP group significantly increased compared with those in the SO group. The scores of lung pathologic injury significantly increased, consistent with the APALI. The wet-to-dry weight ratio, MPO activity, IL-1β, TNF-α, ICAM-1, p-JNK expressions, and lung pathologic injury scores in the SP600125 group decreased compared with those in the SAP group. p-JNK was closely correlated with MPO activity, IL-1β, ICAM-1, and total scores of lung injury.

CONCLUSIONS

The JNK signaling pathway plays a critical role in APALI. On the other hand, application of a specific JNK inhibitor can contribute to alleviation of APALI.

Cell biology of ischemia/reperfusion injury

Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.

Evaluation of JNK blockade as an early intervention treatment for type 1 diabetic nephropathy in hypertensive rats

BACKGROUND/AIMS

The c-Jun amino-terminal kinase (JNK) signaling pathway is activated in human kidney diseases and promotes renal injury in experimental glomerulonephritis. In this study, we examined whether JNK signaling plays a role in the development of diabetic nephropathy or in regulating hypertension, which exacerbates diabetic renal injury.

METHODS

Diabetes was induced in spontaneously hypertensive rats (SHR) using streptozotocin. At week 16 of diabetes, rats with equivalent hyperglycemia and albuminuria were randomized into groups which received no treatment, vehicle alone or a selective JNK inhibitor (CC-930, 60 mg/kg/bid) for 10 weeks. These rats were assessed for hypertension and progression of renal damage.

RESULTS

At week 16, diabetic rats showed increased kidney JNK activation compared with nondiabetic controls. Effective JNK inhibition was demonstrated at week 26 by reductions in c-Jun phosphorylation. CC-930 did not affect blood pressure, kidney hypertrophy, glomerular hyperfiltration, podocyte loss, glomerular fibrosis or tubulointerstitial injury in diabetic SHR. However, CC-930 reduced macrophages and ccl2 mRNA levels in diabetic kidneys. In contrast, CC-930 exacerbated albuminuria at week 26, which was associated with reduced glomerular mRNA levels of the podocyte-specific molecules, nephrin and podocin.

CONCLUSION

JNK inhibition does not prevent the progression of early diabetic renal injury in hypertensive rats, which contrasts with the ability of JNK inhibition to suppress albuminuria and injury in experimental glomerulonephritis.

Attenuation of diabetic nephropathy in diabetes rats induced by streptozotocin by regulating the endoplasmic reticulum stress inflammatory response

The endoplasmic reticulum (ER) is capable of sensing metabolic and stress parameters and integrating intra- and extracellular signals to support a coordinated cell response. In the present study, we verified the hypothesis that 4-phenylbutyric acid (4-PBA), a chemical chaperone, prevented the progression of diabetic nephropathy (DN). Male Sprague-Dawley rats were randomly divided into 3 groups: a normal control group, a DN group, and a DN model plus 4-PBA treatment group (PBA). The DN model was induced by injection of streptozotocin with uninephrectomy. The dosage of 4-PBA treatment was gavaged at a dose of 1 g/kg body weight each day for 12 weeks. The expression of the ER stress indicators significantly increased in the kidney of DN rats within the indicated period. Moreover, the expression of phosphorylated c-JUN NH(2)-terminal kinase, the monocyte chemoattractant protein-1, and the final fibrotic effector all elevated markedly in the kidney of DN rats. Urinary protein excretion rate and the concentration of urinary monocyte chemoattractant protein-1 were higher than those in the normal control group. Treatment with 4-PBA can suppress the expression of the glucose-regulated protein 78 and the phosphorylation of the PKR-like ER kinase, both of which are ER stress indicators; renoinflammatory signal; and the expression of inflammatory cytokines and fibrosis factors. It also can inhibit the increase in urinary protein excretion rate and urinary monocyte chemoattractant protein-1. In conclusion, 4-PBA exerts a marked renoprotective effect possibly due to modulating ER stress and related inflammatory cascade.

Protective effects of SP600125 on renal ischemia-reperfusion injury in rats

BACKGROUND

Ischemia/reperfusion injury (IRI) has a negative effect on renal allograft survival. Using a rat model of kidney IRI in this study, we investigated the overall effect of selective c-Jun N-terminal kinase (JNK) inhibitor SP600125 on renal IRI events.

METHODS

All 45 Fisher rats were anesthetized and renal IRI model was established by 45 min clamp of bilateral renal pedicles and 24 h reperfusion. Vehicle solution or SP600125 solution was intraperitoneally injected 45 min before ischemia, respectively. Analysis of renal histology, function, reactive oxygen species (ROS) expression, JNK phosphorylation status, as well as intra-renal pro-inflammatory cytokines expression was evaluated in this study.

RESULTS

After IRI, the levels of blood urea nitrogen, creatinine, tissue malondialdehyde, TNF-α, IL-1β, IL-6 were all elevated significantly, while superoxide dismutase, catalase activity were decreased. Histologic findings showed severe devastating lesions and increased rodent cell apoptosis; SP600125 effectively improved morphologic features, reversed above-mentioned parameters, and significantly attenuated c-Jun phosphorylation, as well as intra-renal pro-inflammatory cytokines expression compared with vehicle-treated group.

CONCLUSION

These data demonstrate that inhibition of c-Jun with SP600125 is capable of attenuating renal IRI, which might be a novel therapy target.

SOD1 and MitoTEMPO partially prevent mitochondrial permeability transition pore opening, necrosis, and mitochondrial apoptosis after ATP depletion recovery

Generation of excessive reactive oxygen species (ROS) leads to mitochondrial dysfunction, apoptosis, and necrosis in renal ischemia-reperfusion (IR) injury. Previously we showed that lentiviral vector-mediated overexpression of superoxide dismutase-1 (SOD1) in proximal tubular epithelial cells (LLC-PK(1)) reduced cytotoxicity in an in vitro model of IR injury. Here, we examined the effects of SOD1 overexpression on mitochondrial signaling after ATP depletion-recovery (ATP-DR). To examine the role of mitochondrial ROS, a subset of cells was treated with the mitochondrial antioxidant MitoTEMPO. ATP-DR-mediated increase in mitochondrial calcium, loss of mitochondrial membrane potential, and increase in mitochondrial permeability transition pore (MPTP) were attenuated by SOD1 and MitoTEMPO (P<0.01). SOD1 prevented ATP-DR-induced mitochondrial Bax translocation, although the release of proapoptotic proteins from mitochondria was not prevented by SOD1 alone and required the presence of both SOD1 and MitoTEMPO. SOD1 suppressed the increase in c-jun phosphorylation, suggesting that JNK signaling regulates Bax translocation to mitochondria via ROS. ATP-DR-mediated changes in MPTP and mitochondrial signaling increased necrosis and apoptosis, both of which were partially attenuated by SOD1 and MitoTEMPO. These studies show that SOD1 and MitoTEMPO preserve mitochondrial integrity and attenuate ATP-DR-mediated necrosis and apoptosis.

JNK signalling in human and experimental renal ischaemia/reperfusion injury

BACKGROUND

Ischaemia/reperfusion (I/R) is an important factor in delayed graft function in renal transplantation and is a determinant of long-term graft outcome. This study examined the role of c-Jun N-terminal kinase (JNK) signalling in human and experimental renal I/R injury.

METHODS

Biopsies obtained 15-20 min after reperfusion of human renal allografts were examined for JNK signalling by immunostaining for phospho-c-Jun. To examine the pathologic role of JNK signalling, a selective JNK inhibitor (CC-401) was administered to rats before or after the induction of a 30-min period of bilateral renal ischaemia followed by reperfusion. Renal function and tubular damage were analysed.

RESULTS

Substantial JNK activation was evident in tubular epithelial cells in kidneys from deceased donors (n = 30) which was less prominent in kidneys from live donors (n = 7) (44.6 +/- 24.8% vs 29.1 +/- 20% p-c-Jun+, respectively; P < 0.05), whereas biopsies of thin basement membrane disease exhibited little, or no, p-c-Jun staining. The degree of p-c-Jun staining correlated with ischaemic time in deceased donor allografts, but not with graft function. Administration of CC-401 to rats prior to bilateral renal I/R prevented acute renal failure and largely prevented tubular damage, leucocyte infiltration and upregulation of pro-inflammatory molecules. However, delaying CC-401 treatment until 1 h after reperfusion (after the peak of JNK activation) had no protective effect.

CONCLUSIONS

We have identified acute activation of the JNK signalling pathway following I/R in human kidney allografts. Experimental studies indicate that blockade of JNK signalling, commenced prior to this activation, can prevent acute tubular necrosis and renal dysfunction secondary to I/R injury.

Reperfusion stress induced during intermittent selective clamping accelerates rat liver regeneration through JNK pathway

BACKGROUND & AIMS

Liver resection includes temporal vascular inflow occlusion resulting in ischemia/reperfusion injury in the remnant liver. Here, we developed a rat model of selective lobe occlusion to isolate reperfusion stress from ischemia and to analyze its effect on liver regeneration.

METHODS

Left lateral and median lobes of liver were either mobilized or subjected twice for 10min to ischemia followed by 5min reperfusion prior to resection while the regenerative lobes were only subjected to reperfusion.

RESULTS

Although intermittent reperfusion stress induced higher levels of serum transaminases, analysis of cell cycle regulators revealed accelerated regenerative response compared to standard partial hepatectomy. The G0/G1 transition occurred before tissue resection, as evidenced by c-fos, junB, and IL-6 induction. Following hepatectomy, Cyclin D1 up-regulation, G1/S transition, and cell division occurred earlier than normal. Unexpectedly, liver mobilization, a component of the clamping procedure, also resulted in earlier G1/S transition. The shortened G1-phase was driven by the c-Jun N-terminal Kinase pathway and was associated with an oxidative stress response as evidenced by the expression of inducible nitric oxide synthase.

CONCLUSION

Intermittent selective clamping of lobes to be resected induced reperfusion stress on remnant liver that was beneficial for liver regeneration, suggesting this procedure could be applied in clinical practice.

c-Jun NH2-terminal kinase is crucially involved in renal tubulo-interstitial inflammation

Chronic inflammation is a major outcome determinant in several renal disorders. Induction of monocyte chemoattractant protein (MCP)-1 expression in tubular epithelial cells contributes importantly to the recruitment of inflammatory cells from the circulation toward the damaged tubulo-interstitium. Because the MCP-1 gene contains several c-Jun binding sites, we hypothesized that the c-Jun NH(2)-terminal kinase (JNK) pathway regulates MCP-1 expression and subsequently tubulo-interstitial inflammation. This was investigated in cultured rat tubular epithelial cells (NRK-52E) and in the rat unilateral ischemia/reperfusion (I/R) model. In NRK-52E cells, the JNK inhibitor anthra(1,9-cd)pyrazol-6(2H)-one-1,9-pyrazoloanthrone (SP600125) reduced interleukin-1beta-, transforming growth factor-beta-, or bovine serum albumin-induced MCP-1 expression in a potent manner (up to 150-fold). In the rat I/R model, JNK activation was low in controls but induced in tubular cells from 30 min after I/R. The extent of JNK activation correlated with interstitial macrophage accumulation. Treatment with SP600125 (30 mg/kg/day i.p. for 4 days) reduced renal c-Jun activation; MCP-1, osteopontin, and vimentin expression; and interstitial macrophage and T-cell accumulation (all p < 0.05). In human renal disease, we also found induction of JNK activation, which correlated strongly with interstitial macrophage accumulation, tubulointerstitial fibrosis, and renal function loss. In conclusion, these data indicate that the JNK pathway plays an important role in renal inflammation, at least in part through induction of MCP-1 gene expression in tubular epithelial cells.

Signal transduction pathways involved in brain death-induced renal injury

Kidneys derived from brain death organ donors show an inferior survival when compared to kidneys derived from living donors. Brain death is known to induce organ injury by evoking an inflammatory response in the donor. Neuronal injury triggers an inflammatory response in the brain, leading to endothelial dysfunction and the release of cytokines in the circulation. Serum levels of interleukin-6, -8, -10, and monocyte chemoattractant protein-1 (MCP-1) are increased after brain death. Binding with cytokine-receptors in kidneys stimulates activation of nuclear factor-kappa B (NF-kappaB), selectins, adhesion molecules and production of chemokines leading to cellular influx. Mitogen-activated protein kinases (MAP-kinases) mediate inflammatory responses and together with NF-kappaB they seem to play an important role in brain death induced renal injury. Altering the activation state of MAP-kinases could be a promising drug target for early intervention to reduce cerebral injury related donor kidney damage and improve outcome after transplantation.

Blockade of the c-Jun amino terminal kinase prevents crescent formation and halts established anti-GBM glomerulonephritis in the rat

Macrophages induce acute renal injury in anti-glomerular basement membrane (GBM) glomerulonephritis. This operates, in part, via activation of the c-Jun amino terminal kinase (JNK) signaling pathway. However, it is unknown whether inhibition of JNK signaling is effective once the proinflammatory response is established in the injured kidney. This study examined whether blockade of JNK signaling could halt disease progression, including crescent formation, in a model of severe crescentic anti-GBM glomerulonephritis. WKY rats were immunized with sheep IgG and then injected with sheep anti-GBM serum (day 0). Animals were treated with the JNK inhibitor, CC-401, vehicle alone, or no treatment from day 7 until being killed on day 24 of disease. Untreated animals at day 7 showed significant proteinuria, focal glomerular lesions, marked glomerular macrophage and T-cell accumulation, and upregulation of proinflammatory mediators (TNF-alpha, iNOS, MMP-12). Untreated and vehicle-treated groups displayed severe glomerulonephritis at day 24 with renal impairment and worsening proteinuria. These animals had severe glomerular lesions, with 60% of glomeruli exhibiting fibrocellular crescents, in association with increased macrophage and T-cell accumulation (including macrophage giant cells) and a further increase in mRNA levels of TNF-alpha, iNOS, MMP-12, and TGF-beta1. In contrast, CC-401 treatment prevented renal impairment, suppressed proteinuria, and prevented severe glomerular and tubulointerstitial lesions, including crescent formation and granulomatous-like lesions. These protective effects were independent of glomerular macrophage and T-cell accumulation, and of the humoral immune response. CC-401 treatment inhibited expression of both pro- and antiinflammatory molecules (interleukin-10 and heme oxygenase-1). In addition, IL-1 induced MMP-12 and IL-10 production by cultured macrophages was found to be JNK dependent. In conclusion, blockade of JNK signaling provides substantial protection against the progression of crescentic anti-GBM glomerulonephritis, which may be, in part, due to inhibition of the macrophage proinflammatory response.

Protective effect of a standardized Ginkgo extract (ginaton) on renal ischemia/reperfusion injury via suppressing the activation of JNK signal pathway

A new standardized Ginkgo extract (ginaton) destined for i.v. injection was investigated in rats for its protective effect on renal ischemia/reperfusion injury. We report on the elucidation of the downstream mechanism of action of JNK on the renal ischemia/reperfusion injury, which can be explained as the decrease in JNK phosphorylation at 20 min and c-Jun phosphorylation (Ser63/73) at 3h after renal ischemia. At the same time, ginaton attenuated the increased expression of FasL at 3h and caspase3 immunoreactivity at 6h after renal ischemia. Furthermore, ginaton significantly decreased renal epithelial tubular cell apoptosis induced by renal ischemia/reperfusion, alleviating renal ischemia/reperfusion injury. These results cumulatively indicate that ginaton could suppress the JNK-c-Jun-FasL-caspase3 signaling cascade, protecting renal tubular epithelial cells against ischemia/reperfusion-induced apoptosis, which implies that antioxidants may be a potential and effective agent for prevention of the ischemic/reperfusion injury through the suppression extrinsic apoptotic signal pathway induced by JNK signal pathway.

Renal ischemia: does sex matter?

Renal ischemia is a common complication in the perioperative period that leads to a high rate of morbidity and mortality. As in other forms of ischemia (i.e., cardiac, neurologic), the incidence and outcome of renal ischemia is strikingly sex-specific. Sexual dimorphism in response to renal injury has been noted for many years, but is now the subject of both clinical and experimental research. Clinically, women experience a lower incidence of perioperative acute renal failure, with the exception of cardiac surgery. Experimental science is now producing tantalizing clues that sex steroids, both male and female, play a role in the kidney's response to ischemia. In this review, we evaluated sex differences in perioperative renal failure and in the pathophysiology of renal ischemia/reperfusion injury. Although much work remains to characterize the biological mechanisms involved, the data are sufficient to support consideration of gender and the use of medications that impact steroid availability in the perioperative plan of care.

Pharmacological modulation of epithelial mesenchymal transition caused by angiotensin II. Role of ROCK and MAPK pathways

PURPOSE

Tubulointerstitial fibrosis is a final common pathway to end-stage chronic kidney diseases, which are characterized by elevated renal angiotensin II (AngII) production. This peptide participates in kidney damage inducing fibrosis and epithelial mesenchymal transition (EMT). Our aim was to describe potential therapeutic targets in AngII-induced EMT, investigating the blockade of different intracellular pathways.

METHODS

Studies were done in human tubular epithelial cells (HK2 cell line), evaluating changes in phenotype and EMT markers (Western blot and immunofluorescence).

RESULTS

Treatment of HK2 cells with AngII for 3 days caused transdifferentiation into myofibroblast-like cells. The blockade of MAPKs cascade, using specific inhibitors of p38 (SB203580), extracellular signal-regulated kinase1/2 (ERK; PD98059) and Jun N-terminal kinase (JNK) (SP600125), diminished AngII-induced EMT. The blockade of RhoA/ROCK pathway, by transfection of a RhoA dominant-negative vector or by ROCK inhibition with Y-27632 or fasudil, inhibited EMT caused by AngII. Connective tissue growth factor (CTGF) is a downstream mediator of AngII-induced EMT. MAPKs and ROCK inhibitors blocked CTGF overexpression induced by AngII. HMG-CoA reductase inhibitors, although blocked AngII-mediated kinases activation, only partially diminished EMT and did not regulate CTGF.

CONCLUSIONS

These data suggest a potential therapeutic use of kinase inhibitors in renal fibrosis.