Lipid peroxidation triggers both c-Jun N-terminal kinase (JNK) and extracellular-regulated kinase (ERK) activation and neointimal hyperplasia induced by cessation of blood flow in the mouse carotid artery

ALOX15B controls macrophage cholesterol homeostasis via lipid peroxidation, ERK1/2 and SREBP2

Macrophage cholesterol homeostasis is crucial for health and disease and has been linked to the lipid-peroxidizing enzyme arachidonate 15-lipoxygenase type B (ALOX15B), albeit molecular mechanisms remain obscure. We performed global transcriptome and immunofluorescence analysis in ALOX15B-silenced primary human macrophages and observed a reduction of nuclear sterol regulatory element-binding protein (SREBP) 2, the master transcription factor of cellular cholesterol biosynthesis. Consequently, SREBP2-target gene expression was reduced as were the sterol biosynthetic intermediates desmosterol and lathosterol as well as 25- and 27-hydroxycholesterol. Mechanistically, suppression of ALOX15B reduced lipid peroxidation in primary human macrophages and thereby attenuated activation of mitogen-activated protein kinase ERK1/2, which lowered SREBP2 abundance and activity. Low nuclear SREBP2 rendered both, ALOX15B-silenced and ERK1/2-inhibited macrophages refractory to SREBP2 activation upon blocking the NPC intracellular cholesterol transporter 1. These studies suggest a regulatory mechanism controlling macrophage cholesterol homeostasis based on ALOX15B-mediated lipid peroxidation and concomitant ERK1/2 activation.

Clinical value of serum JKAP in acute ischemic stroke patients

Background

Jun N‐terminal kinase pathway‐associated phosphatase (JKAP) regulates neuronal function, T helper (Th) 1/2/17 cell differentiation, and inflammatory process, but its clinical role in acute ischemic stroke (AIS) patients remains unclear. Hence, this study intended to evaluate JKAP level and its relationship with disease severity, Th1, 2, 17 secreted cytokines, adhesion molecules, and prognosis of AIS patients.

Methods

Serum JKAP of 122 AIS patients and 50 controls was detected by ELISA. For AIS patients only, Th1, 2, 17 secreted cytokines IFN‐γ, IL‐4, IL‐17; TNF‐α, ICAM‐1, and VCAM‐1 were also detected by ELISA.

Results

JKAP was decreased in AIS patients compared with controls (46.350 (interquartile range (IQR): 34.250–59.875) pg/ml vs. 84.500 (IQR: 63.175–113.275) pg/ml, p < 0.001), which could distinguish AIS patients from controls (area under curve (AUC): 0.810, 95% confidence interval (CI): 0.732–0.888). In AIS patients, JKAP negatively linked with the National Institutes of Health Stroke Scale (NIHSS) score (r_s = −0.342, p < 0.001); besides, it was positively related to IL‐4 (r_s = 0.213, p = 0.018) and negatively associated with IL‐17 (r_s = −0.270, p = 0.003) but not related to IFN‐γ (r_s = −0.146, p = 0.109). Furthermore, elevated JKAP associated with declined TNF‐α (r_s = −0.219, p = 0.015) and ICAM‐1 (r_s = −0.235, p = 0.009) but not related to VCAM‐1 (r_s = −0.156, p = 0.085). Besides, declined JKAP was linked with 2‐year recurrence (p = 0.027) and 3‐year recurrence (p = 0.010) in AIS patients; while JKAP was not related to 1‐year recurrence or death risk (both p > 0.050).

Conclusion

JKAP may sever as a candidate prognostic biomarker in AIS patients, indicating its potency for AIS management.

Obacunone Retards Renal Cyst Development in Autosomal Dominant Polycystic Kidney Disease by Activating NRF2

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disease characterized by progressive enlargement of fluid-filled cysts derived from renal tubular epithelial cells, which has become the fourth leading cause of end-stage renal diseases. Currently, treatment options for ADPKD remain limited. The purpose of this study was to discover an effective therapeutic drug for ADPKD. With virtual screening, Madin-Darby canine kidney (MDCK) cyst model, embryonic kidney cyst model and kidney-specific Pkd1 knockout mouse (PKD) model, we identified obacunone as a candidate compound for ADPKD drug discovery from a natural antioxidant compound library. In vitro experiments showed that obacunone significantly inhibited cyst formation and expansion of MDCK cysts and embryonic kidney cysts in a dose-dependent manner. In vivo, obacunone treatment significantly reduced the renal cyst development in PKD mice. Western blot and morphological analysis revealed that obacunone served as a NRF2 activator in ADPKD, which suppressed lipid peroxidation by up-regulating GPX4 and finally restrained excessive cell proliferation by down-regulating mTOR and MAPK signaling pathways. Experimental data demonstrated obacunone as an effective renal cyst inhibitor for ADPKD, indicating that obacunone might be developed into a therapeutic drug for ADPKD treatment.

Testicular Torsion and Spermatogenesis

Testicular torsion (TT) is a common urologic emergency that can occur at any age. It is most common in newborns and during puberty. Prompt evaluation and management is required to salvage the testis following an episode of torsion. TT brings about damage to testicular tissue and spermatogenesis through various hypothesized mechanisms; however there is a consensus that the effects of ischemia, ischemia-reperfusion injury, and oxidative stress account for the most destructive effects. Numerous studies have examined the effects of various agents and therapies in limiting the effects of TT on the testis.

Lipid peroxidation-induced VEGF expression in the skin of KKAy obese mice

Obesity is known to be associated with a number of effects on skin physiology. KKA(y) obese mouse is a model of type 2 diabetes characterized by systemic oxidative stress because of severe obesity, hypertriglyceridaemia, hyperglycaemia and hyperinsulinaemia. We investigated lipid peroxidation and vascular endothelial growth factor (VEGF) expression in the skin of KKA(y) obese mice. We also investigated the effect of lipid peroxidation derivatives on VEGF production and proliferation in human epidermal keratinocyte cell line (HaCaT). The lipid peroxidation level in the mouse skin tissue was determined by measuring the levels of thiobarbituric acid-reactive substances. The levels of VEGF expression, p44/p42 mitogen-activated protein kinase (MAPK) activation and CD36 expression were analysed by Western blot. Their localization was examined by immunofluorescence. For the in vitro experiments, an enzyme-linked immunosorbent assay was utilized to measure VEGF secretion in the medium. In vitro experiments demonstrated that lipid peroxidation derivatives increased VEGF production in HaCaT cells, which was blocked by a p44/p42 MAPK inhibitor and anti-CD36 antibody. We observed increased levels of lipid peroxidation derivatives, p44/p42 MAPK activation and VEGF expression in the skin of KKA(y) obese mice. Notably, pitavastatin, an inhibitor of competitive 3-hydroxy-3-methylglutaryl coenzyme A reductase, suppressed all of these processes. Our results suggest that lipid peroxidation induces VEGF expression via CD36 and p44/p42 MAPK pathway in the skin of obese mice.

Glutathione S-transferase-micro1 regulates vascular smooth muscle cell proliferation, migration, and oxidative stress

Glutathione S-transferase-micro1, GSTM1, belongs to a superfamily of glutathione S-transferases that metabolizes a broad range of reactive oxygen species and xenobiotics. Across species, genetic variants that result in decreased expression of the Gstm1 gene are associated with increased susceptibility for vascular diseases, including atherosclerosis in humans. We previously identified Gstm1 as a positional candidate in our gene mapping study for susceptibility to renal vascular injury characterized by medial hypertrophy and hyperplasia of the renal vessels. To determine the role of Gstm1 in vascular smooth muscle cells (VSMCs), we isolated VSMCs from mouse aortas. We demonstrate that VSMCs from the susceptible C57BL/6 mice have reduced expression of Gstm1 mRNA and its protein product compared with that of the resistant 129 mice. After serum stimulation, C57BL/6 VSMCs proliferate and migrate at a much faster rate than 129 VSMCs. Furthermore, C57BL/6 VSMCs have higher levels of reactive oxygen species and exhibit exaggerated p38 mitogen-activated protein kinase phosphorylation after exposure to H(2)O(2). To establish causality, we show that knockdown of Gstm1 by small interfering RNA results in increased proliferation of VSMCs in a dose-dependent manner, as well as in increased reactive oxygen species levels and VSMC migration. Moreover, Gstm1 small interfering RNA causes increased p38 mitogen-activated protein kinase phosphorylation and attenuates the antiproliferative effect of Tempol. Our data suggest that Gstm1 is a novel regulator of VSMC proliferation and migration through its role in handling reactive oxygen species. Genetic variants that cause a decremental change in expression of Gstm1 may permit an environment of exaggerated oxidative stress, leading to susceptibility to vascular remodeling and atherosclerosis.

The nucleotide analogue 3-deazaadenosine prevents neointima-formation after balloon injury

We have recently shown that 3-deazaadenosine (c3Ado) inhibits atherogenesis in mice. We studied whether its anti-inflammatory capacity would also affect neointima-formation after balloon injury. Sprague Dawley rats underwent balloon angioplasty. C3Ado was administered orally, starting 5 days prior to the balloon injury and continued for 2 weeks. Fourteen days after balloon injury the intima/media ratio in the c3Ado-treated group was reduced by 67% (p<0.001) and luminal stenosis by 50% (p<0.001). Neointimal cellular density was decreased by 25% (p<0.001) and the induction of c-Jun and ki67 was markedly lower. The reduction of the intima/media ratio was still observed 3 months after balloon injury. Furthermore, a c3Ado-dependent inhibition of PDGF-mediated ERK-activation and proliferation could be demonstrated. Short-term administration of C3Ado inhibits neointima-formation in rats for at least 3 months after injury. The present findings implicate that c3Ado may be useful as an inhibitor of restenosis-formation after balloon angioplasty in humans.

Activation of the non-receptor tyrosine kinase cSrc in macrophage-rich atherosclerotic plaques of human carotid arteries

To determine the involvement of the non-receptor tyrosine kinase cSrc in plaque destabilization in carotid atherosclerosis (CAS), which is responsible for cerebral infarction, we performed quantitative and morphological detection of phosphorylated active cSrc (p-cSrc) and histopathological examination in CAS lesions. We examined carotid endarterectomy specimens obtained from 32 CAS patients. Each specimen was used for immunoblot and immunohistochemical analyses of p-cSrc, histopathological analysis, and image analysis of macrophage content. There was a strong positive correlation between cSrc activation on blots and macrophage content on sections. When we defined the macrophage-rich plaque (MRP) and the macrophage-poor plaque (MPP) as having macrophage content more and less than 5%, respectively, the p-cSrc density and the occurrence of plaque hemorrhage and thrombus formation were significantly increased in the MRP group (n=18) compared to the MPP group (n=14). p-cSrc immunoreactivity was localized in lesional endothelial cells, macrophages, and smooth muscle cells, which contained proinflammatory substances: the upstream oxidized low density lipoprotein, tissue factor and osteopontin, and the downstream active forms of extracellular signal-activated kinase and p38 and nuclear factor-kappaB. Our results suggest that cSrc activation in lesional cells contributes to plaque destabilization in CAS via persistent inflammation.

Blockade of both α1A- and α1B-adrenergic receptor subtype signaling is required to inhibit neointimal formation in the mouse femoral artery

Attenuation of early restenosis after percutaneous coronary intervention (PCI) is important for the successful treatment of coronary artery disease. Some clinical studies have shown that hypertension is a risk factor for early restenosis after PCI. These findings suggest that α1-adrenergic receptors (α1-ARs) may facilitate restenosis after PCI because of α1-AR's remarkable contribution to the onset of hypertension. In this study, we examined the neointimal formation after vascular injury in the femoral artery of α1A-knockout (α1A-KO), α1B-KO, α1D-KO, α1A-/α1B-AR double-KO (α1AB-KO), and wild-type mice to investigate the functional role of each α1-AR subtype in neointimal formation, which is known to promote restenosis. Neointimal formation 4 wk after wire injury was significantly ( P < 0.05) smaller in α1AB-KO mice than in any other group of mice, while blood pressures were not altered in any of the groups of mice after wire injury compared with those before it. These results suggest that lack of both α1A- and α1B-ARs could be necessary to inhibit neointimal formation in the mouse femoral artery.

Rosiglitazone ameliorates diabetic nephropathy by inhibiting reactive oxygen species and its downstream-signaling pathways

AIM

To study whether rosiglitazone prevents the development of diabetic nephropathy through reduction of reactive oxygen species and its downstream signal transduction pathways.

METHODS

The rats were intraperitoneally injected with streptozotocin to induce diabetes, meanwhile the rats in the therapeutic groups were given rosiglitazone (5 or 20 mg/kg/day) for 4 weeks by intragastric administration. Blood glucose, serum lipid and creatinine, urinary albumin excretion were measured. Malondialdehyde content, the activities of nuclear factor-kappaB (NF-kappaB), antioxidant enzymes including Cu-Zn SOD and GSH-Px in kidney were also measured. In addition, the mRNA and protein expression of MCP-1 were semiquantitatively determined with PT-PCR and immunohistochemical staining respectively.

RESULTS

No significant difference of blood glucose and lipid were found between diabetic rats and rosiglitazone treatment groups. The renal histopathology was improved significantly. The expressions of MCP-1 mRNA and protein, malondialdehyde level and the activity of NF-kappaB were decreased markedly in rats treated with high-dose rosiglitazone, but the activities of renal Cu-Zn SOD and GSH-Px increased significantly.

CONCLUSIONS

Rosiglitazone treatment prevented glomerular injury in diabetic rats, which was closely related with its roles of reducing reactive oxygen species, NF-kappaB activation and MCP-1 expression in the early phase of diabetic nephropathy.

Antisense ERK1/2 oligodeoxynucleotide gene therapy attenuates graft arteriosclerosis of aortic transplant in a rat model

Chronic rejection is a major cause of transplant loss that is effected by the extracellular signal-regulated kinases (ERK) pathway. This study investigated the effects of antisense ERK1/2 oligodeoxynucleotide(ODN) gene therapy on chronic rejection.

METHODS

Lewis (RT1(1)) rats served as recipients of Brown-Norway (BN, RT1n) grafts. The BN rat abdominal aortas were harvested and orthotopically grafted into Lewis rats. The recipients were divided into three groups: (1) control group (n = 9), (2) random ODN transfer group (n = 10), and (3) antisense ODN transfer group (n = 10). At day 60 after transplantation, the recipients were sacrificed; the grafted aortas were evaluated histologically and immunohistochemically. ERK1/2 protein expression in the grafts was determined using Western Blot assays. Serum levels of slCAM-1 were detected by ELISA.

RESULTS

In the control group and random ODN transfer group, we observed a remarkable degree of intimal hyperplasia and inflammatory cell infiltration, including macrophages and T cells. Compared with the control group, antisense ERK1/2 ODN gene therapy resulted in a significant reduction in neointimal proliferation (P < .01), inhibition of ERK1/2 protein expression (P < .01), decreased graft infiltration with CD4+ T lymphocytes (P < .01), CD8+ T lymphocytes(P < .05), and ED-1 macrophages (P < .01) with decreased serum levels of sICAM-1 (P < .05). We obtained a negative correlation between ERK1/2 expression and immune cell infiltration or ICAM-1 level.

CONCLUSIONS

Antisense ERK1/2 gene therapy can attenuate graft arteriosclerosis so as to protect aortic allografts. The protection seemed to correlate with inhibition of inflammatory infiltration, implying that the ERK1/2 signal transduction pathway plays an important role in the process of chronic vascular rejection.

Adenovirus-Mediated Antisense-ERK2 Gene Therapy Attenuates Chronic Allograft Nephropathy

BACKGROUND

The aim of this study was to investigate the effects of adenovirus-mediated antisense ERK2 (Adanti-ERK2) gene therapy on chronic allograft nephropathy.

METHODS

We employed a rat kidney transplantation mode (F344-->Lewis) and studied four groups: (1) controls (n = 6); (2) vector controls (n = 6); (3) an Adanti-ERK2 group (n = 10); and (4) an isograft group (n = 4). The animals were monitored for proteinuria, graft histology, infiltrating cells, and immune-related gene (interleukin-2 [IL-2] and intracellular adhesion molecule-1 [ICAM-1]) expression for 20 weeks after transplantation.

RESULTS

The control group had increasing proteinuria during the 20-week follow-up. All rats showed advanced chronic renal failure associated with strong immune cell infiltration and immune gene expression. Chronic graft injury was accelerated in the vector-control group, but no significant difference was observed compared with the control group. In contrast, the Adanti-ERK2 group showed less inflammation and improved graft histology/function compared with controls. Moreover, ERK2 protein expression in the Adanti-ERK2 group was lower than in the control group (P < .05) and vector-control group (P < .05). Furthermore, serial estimates of genes (IL-2, ICAM-1) related to chronic rejection showed significant downregulation in the Adanti-ERK2 group (P < .01).

CONCLUSIONS

Adenovirus-mediated antisense ERK2 gene therapy attenuated chronic allograft nephropathy. The protective effects of antisense ERK2 gene therapy may have derived from a blocked ERK signal transduction pathway, which reduced ERK expression as well as those of immune-related genes.

Lipid Peroxidation Activates Mitogen-Activated Protein Kinases in Testicular Ischemia-Reperfusion Injury

PURPOSE

Testicular damage after torsion has been attributed to many mechanisms, of which one is lipid peroxidation of the plasma membrane, which could cause the activation of the mitogen-activated protein kinase family. These proteins are of vital importance for signal transduction pathways and 2 of them, extracellular signal-regulated kinase and c-jun N-terminal kinase, participate in the pathogenesis of testicular ischemia. We investigated whether lipid peroxidation may trigger mitogen-activated protein kinase activation in testicular ischemia-reperfusion.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to 1-hour testicular ischemia, followed by 24 hours of reperfusion. Sham testicular ischemia-reperfusion rats served as controls. Animals were randomized to receive raxofelast, an inhibitor of lipid peroxidation (20 mg/kg intraperitoneally administered 15 minutes before detorsion and 15 minutes after detorsion) or vehicle (1 ml/kg 10% dimethyl sulfoxide/NaCl solution). A group of animals was sacrificed 0, 10, 15, 20, 25 and 30 minutes, and 1, 2 and 3 hours, respectively, after detorsion to evaluate testicular c-jun N-terminal kinase, extracellular signal-regulated kinase and tumor necrosis factor-alpha activation by Western blot analysis, and mRNA expression and conjugated dienes using a spectrophotometer technique. Another group was sacrificed 24 hours after detorsion to evaluate histological alterations.

RESULTS

Testicular ischemia-reperfusion injury caused a significant increase in the conjugated diene levels, extracellular signal-regulated kinase c-jun N-terminal kinase activity and tumor necrosis factor-alpha expression in both testes. Furthermore, histological examination revealed marked damage. Raxofelast inhibited these parameters and decreased histological damage.

CONCLUSIONS

These data suggest that lipid peroxidation triggers extracellular signal-regulated kinase and c-jun N-terminal kinase activation. Furthermore, mitogen-activated protein kinase blockade might represent a potential therapeutic approach to treatment in patients with unilateral testicular torsion.

The flavonoid quercetin induces apoptosis and inhibits JNK activation in intimal vascular smooth muscle cells

Quercetin, the most abundant dietary flavonol, exerts vasodilator, anti-hypertensive, and anti-atherogenic effects and reduces the vascular remodelling associated with elevated blood pressure. Here, we have compared the effects of quercetin in intimal- and medial-type rat vascular smooth muscle cells (VSMC) in culture. After 48 h, quercetin reduced the viability of a polyclonal intimal-type cell line derived from neonatal aorta but not of a medial-type cell line derived from adult aorta. These differential effects were similar in both proliferating and quiescent VSMC. Quercetin also preferentially reduced the viability of intimal-type over medial-type VSMC in primary cultures derived from balloon-injured carotid arteries. The effects of quercetin on cell viability were mainly dependent upon induction of apoptosis, as demonstrated by nuclear condensation and fragmentation, and were unrelated to PPARgamma, pro-oxidant effects or nitric oxide. The expression of MAPKs (ERK, p38, and JNK) and ERK phosphorylation were not different between intimal- and medial-type VSMC. p38 phosphorylation was negligible in both cell types. Medial-type showed a weak JNK phosphorylation while this was markedly increased in intimal-type cells. Quercetin reduced JNK phosphorylation but had no consistent effect on ERK phosphorylation. In conclusion, quercetin preferentially produced apoptosis in intimal-type compared to medial-type VSMC. This might play a role in the anti-atherogenic and anti-hypertensive effects of quercetin.

Modulation of the oxidative stress and inflammatory response by PPAR-γ agonists in the hippocampus of rats exposed to cerebral ischemia/reperfusion

Agonists of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) exert protective effects in several models of ischemia/reperfusion injury, but their role in stroke is less clear. The study investigates the effects of two PPAR-gamma agonists, rosiglitazone and pioglitazone, on oxidative stress and inflammatory response induced by ischemia/reperfusion in the rat hippocampus. Common carotid artery occlusion for 30 min followed by 1 h reperfusion resulted in a significant increase in the generation of reactive oxygen species, nitric oxide and the end products of lipid peroxidation as well as markedly reduced endogenous antioxidant glutathione levels and up-regulated superoxide dismutase activity. Western blot analysis showed that ischemia/reperfusion lead to an increase in cyclooxygenase-2 (COX-2) expression, as well activating p38 and p42/44 mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB). Pre-treatment with either rosiglitazone or pioglitazone significantly reduced oxidative stress, COX-2 protein expression and activation of MAPKs and NF-kappaB. Taken together, the results provide convincing evidence that PPAR-gamma agonists exert protective effects in a rat model of mild forebrain ischemia/reperfusion injury by inhibiting oxidative stress and excessive inflammatory response.

Evidence for a Role of Mitogen-Activated Protein Kinase 3/Mitogen-Activated Protein Kinase in the Development of Testicular Ischemia-Reperfusion Injury

Mitogen-activated protein kinase (MAPK) 3/MAPK1 (also known as ERK1/ERK2) plays an important role in the signal transduction pathways. To our knowledge, however, its role in the development of testicular ischemia-reperfusion injury has not yet been investigated. Therefore, we studied the pattern of MAPK3/MAPK1 activation in a experimental model of testicular ischemia-reperfusion injury. We also investigated MAPK8 to understand whether an association exists between these two MAPKs. Adult male Sprague-Dawley rats were subjected to 1 h of testicular ischemia followed by 24 h of reperfusion or to a sham testicular ischemia-reperfusion. Animals were randomized to receive PD98059, which is an inhibitor of MAPK3/MAPK1 (10 mg/kg i.p. administered immediately after detorsion), or its vehicle. The time course of MAPK3/MAPK1, MAPK8, and tumor necrosis factor (TNF; also known as TNF alpha) expression and a histological examination in both the ischemic-reperfused testis and the contralateral one were performed. In both testes, MAPK3/MAPK1 and MAPK8 expression appeared following 10 min of reperfusion and reached their highest activation after 30 min. The MAPK levels slowly decreased, and no significant expression of either kinase was observed following 2 h of reperfusion. Expression of TNF was evident after 1 h of reperfusion and reached its maximum increase after 3 h. PD98059 blunted MAPK3/MAPK1 and MAPK8, reduced TNF expression, and improved the testicular damage caused by ischemia-reperfusion injury in both testes. These data emphasize that MAPK3/MAPK1 has a role in testicular damage and that its blockade might have a future therapeutic role for the management of patients with unilateral testicular torsion.