Prorenin receptor mediates inflammation in renal ischemia

We hypothesized that PRR contributes to renal inflammation in the 2‐kidney, 1‐clip (2K1C) renal ischaemia model. Male Sprague‐Dawley rats were fed normal sodium diet. Blood pressure (BP) was obtained on days 0 and 28 after left renal artery clipping that reduced renal blood flow by 40%. Renal expression of TNF‐α, COX‐2, NF‐κB, IL‐1β, MCP‐1 and collagen type I were assessed in sham and 2K1C rats with or without left renal administration of scramble or PRR shRNA. At baseline, there were no differences in BP. Compared to sham, MAP significantly increased in clipped animals (sham 102 ± 1.9 vs 2K1C 131.8 ± 3.09 mmHg, P < .05) and was not influenced by scramble or PRR shRNA treatment. Compared to sham and contra lateral (non‐clipped) kidney, there was upregulation in mRNA and protein expression of PRR (99% and 45%, P < .01), TNF‐α (72% and 50%, P < .05), COX‐2 (72% and 39%, P < .05), p‐NF‐κB (92%, P < .05), MCP‐1 (87%, P < .05) and immunostaining of collagen type I in the clipped kidney. These increases were not influenced by scramble shRNA. Compared to 2K1C and scramble shRNA, PRR shRNA treatment in the clipped kidney significantly reduced the expression of PRR (62% and 57%, P < .01), TNF‐α (51% and 50%, P < .05), COX‐2 (50% and 56%, P < .05), p‐NF‐κB by 68% (P < .05), MCP‐1 by 73% (P < .05) and collagen type I respectively. Ang II was increased in both kidneys and did not change in response to scramble or PRR shRNA treatments. We conclude that PRR mediates renal inflammation in renal ischaemia independent of blood pressure and Ang II.     

The toll like receptor 4‐myeloid differentiation factor 88 pathway is essential for particulate matter‐induced activation of CD4‐positive cells

Asian sand dust (ASD), a type of particulate matter (PM) found in Asia, can be transported to East Asia. We recently found that acute splenic inflammation is induced by ASD in mouse models. In this study, we examined the effect of sub‐chronic ASD exposure on mouse immune cells. Mice were intratracheally administered ASD once every 2 weeks for 8 weeks and killed 24 hours after the final administration. Wild‐type (WT) mice showed increased cell viability after ASD administration. In contrast, ASD administration induced splenocyte activation in toll‐like receptor (TLR)2^?/?, but not TLR4^?/? mice. Furthermore, concanavalin A‐induced interleukin‐2 production increased after ASD administration in WT and TLR2^?/? mice, but not in TLR4^?/? or myeloid differentiation factor (MyD)88^?/? mice. Immunoblotting demonstrated that nuclear factor κB (NF‐κB) was activated in WT mice, but not in TLR4^?/? or MyD88^?/? mice. The NF‐κB‐dependent gene products CDK2 and intercellular cell adhesion molecule‐1 were upregulated upon ASD administration in WT mice, but not in TLR4^?/? or MyD88^?/? mice. Furthermore, the particles themselves, rather than particle constituents, activated NF‐κB in CD4‐positive cells through the TLR4 or MyD88 pathway. Taken together, these results indicate that particle‐induced splenic inflammation occurs via TLR4‐MyD88 signaling.     

Anti‐inflammatory and retinal protective effects of capsaicin on ischaemia‐induced injuries through the release of endogenous somatostatin

The mechanisms regarding the retinal protective and anti‐inflammatory effects of capsaicin (CAP) remain unclear. Somatostatin is contained in CAP‐sensitive sensory neurons, including nerve terminals, from which it can be released by capsaicin. The present study provides a novel neurohumoral regulatory mechanism for CAP‐induced‐endogenous somatostatin in a retinal ischaemia‐reperfusion (I/R) mouse model. CAP (0.5 mg/kg) was injected subcutaneously 5 minutes after I/R. A selective somatostatin‐depleting agent, cysteamine, was applied subcutaneously 4 hours before the experiment to examine the effects of endogenous somatostatin. Ischaemia and oxidative stress‐induced inflammatory factors (CXCL10, CXCR3 and NF‐κB p65) were also examined in the present study. The morphometric evaluation showed that the retinal thickness was increased 24 hours after I/R injury and attenuated 7 days after I/R injury. The number of ganglion cells was reduced 7 days after I/R injury. The application of CAP significantly prevented retinal I/R damage. Cysteamine pretreatment reversed the effects of CAP. Inhibition of CXCL10/CXCR3 and NF‐κB (especially in astrocytes and microglia/macrophage) was involved in capsaicin‐induced retinal protection through endogenous somatostatin. CAP has anti‐inflammatory and neuroprotective effects in ischaemia‐induced retinal injuries through endogenous somatostatin. Novel therapeutic remedies for inflammation or neuronal injuries were developed based on the systemic humoral effects related to CAP.     

NF‐κB activation mediates LPS‐or zymosan‐induced hypotension and inflammation reversed by BAY61‐3606, a selective Syk inhibitor,in rat models of septic and non‐septic shock

We have previously demonstrated that the activation of the spleen tyrosine kinase (Syk)/inhibitory‐κB (IκB)‐α/nuclear factor‐κB (NF‐κB) p65 signalling pathway contributes to hypotension and inflammatory response in a rat models of zymosan (ZYM)‐induced non‐septic shock. The purpose of this study was to further examine the possible mechanism underlying the effect of inhibition of Syk by BAY61‐3606 via NF‐κB activity at the level of nuclear translocation regarding the production of vasodilator and proinflammatory mediators in lipopolysaccharide (LPS) (septic)‐ and ZYM (non‐septic)‐induced shock. Administration of LPS (10 mg/kg, ip) or ZYM (500 mg/kg, ip) to male Wistar rats decreased mean arterial pressure and increased heart rate that was associated with an increase in the activities of cyclooxygenase and nitric oxide synthase, tumour necrosis factor‐α, and interleukin‐8 levels, and NF‐κB activation and nuclear translocation in sera and/or cardiovascular and renal tissues. BAY61‐3606 (3 mg/kg, ip), the selective Syk inhibitor, given 1 hour after LPS‐ or ZYM injection reversed all the above‐mentioned effects. These results suggest that Syk contributes to the LPS‐ or ZYM‐induced hypotension and inflammation associated with transactivation of NF‐κB in septic and non‐septic shock.     

Protective Effect of Atazanavir Sulphate Against Pulmonary Fibrosis In Vivo and In Vitro

Atazanavir sulphate, an antiretroviral protease inhibitor, has been used to treat HIV/AIDS, but its ability to serve as an antipulmonary fibrosis (PF) agent remains unknown. In this study, the effects of atazanavir sulphate on various aspects of PF were examined and CoCl₂ was used to induce the hypoxia‐mimicking condition in vitro, including epithelial–mesenchymal transition (EMT) in A549 cells, endothelial–mesenchymal transition (EndMT) in human pulmonary microvascular endothelial cells (HPMECs), proliferation in human lung fibroblasts (HLF‐1) and potential protective effects in human type I alveolar epithelial cells (AT I). Additionally, the effects of atazanavir sulphate were examined using a bleomycin (BLM)‐induced pulmonary fibrosis model. After atazanavir sulphate treatment, in A549 cells and HPMECs, the expression of vimentin, HMGB1, Toll‐like receptor 4 (TLR‐4) and p‐NF‐κB decreased, while the expression of E‐cadherin and VE‐cadherin increased. In AT I cells, the expression of aquaporin 5 and RAGE were increased after atazanavir treatment. Proliferation of HLF‐1 was reduced after atazanavir treatment, meanwhile the expression of hypoxia‐inducible factor‐1α (HIF‐1α), prolyl hydroxylase domain protein 2 (PHD‐2), HMGB1, TLR‐9, p‐NF‐κB, collagen I and collagen III was decreased. In the BLM‐induced pulmonary fibrosis rat model, atazanavir sulphate ameliorated PF by reducing pathological score, collagen deposition and the expression of α‐SMA, HIF‐1α, PHD‐2, HMGB1, TLR‐4, TLR‐9 and p‐NF‐κB. In summary, our study supports the proposal that atazanavir sulphate may have a therapeutic potential in reducing the progression of pulmonary fibrosis by suppressing HMGB1/TLR signalling.     

Growth inhibitory effect of β‐eudesmol on cholangiocarcinoma cells and its potential suppressive effect on heme oxygenase‐1 production,STAT1/3 activation,and NF‐κB downregulation

Cholangiocarcinoma (CCA) is a progressively fatal form of cancer originating from the malignant transformation of hepatic biliary cholangiocytes. The present study reports for the first time in vitro growth inhibitory activities of β‐eudesmol, the bioactive sesquiterpenoid present in the rhizome of Atractylodes lancea (Thunb) DC., with respect to its underlying potential effects on heme oxygenase‐1 (HO‐1) production, STAT1/3 phosphorylation, and NF‐κB protein expression in human CCA cell line CL‐6. The cytotoxic effect of β‐eudesmol on CL‐6 cells was evaluated by MTT assay using normal human embryonic fibroblast (OUMS) as a control cell line. Results indicated that β‐eudesmol exhibited selective cytotoxicity towards CL‐6 compared to OUMS with mean (±SD) IC₅₀ (concentration that inhibits cell growth by 50%) values of 166.75 ± 3.69 and 240.01 ± 16.54 μmol/L, respectively. In addition, it also significantly suppressed colony forming and wound healing ability of CL‐6 cells in a concentration‐dependent manner. Western blot analysis indicated that β‐eudesmol treatment resulted in significant suppression of HO‐1 production in CL‐6 cells. Its inhibitory effects on the phosphorylation of STAT1/3 proteins and expression of NF‐κB (p65 and p50) proteins were concentration‐dependent. Taken together, these results suggest that β‐eudesmol exerts significant growth inhibitory activity on CL‐6 cells that may be linked to its inhibitory effect on the production of HO‐1, phosphorylation of STAT1/3, and expression of major NF‐κB proteins.     

MiR‐146a regulates PM1‐induced inflammation via NF‐κB signaling pathway in BEAS‐2B cells

Exposure to particulate matter (PM) leads to kinds of cardiopulmonary diseases, such as asthma, COPD, arrhythmias, lung cancer, etc., which are related to PM‐induced inflammation. We have found that PM_2.5 (aerodynamics diameter <2.5 µm) exposure induces inflammatory response both in vivo and in vitro. Since the toxicity of PM is tightly associated with its size and components, PM₁ (aerodynamics diameter <1.0 µm) is supposed to be more toxic than PM_2.5. However, the mechanism of PM₁‐induced inflammation is not clear. Recently, emerging evidences prove that microRNAs play a vital role in regulating inflammation. Therefore, we studied the regulation of miR‐146a in PM₁‐induced inflammation in human lung bronchial epithelial BEAS‐2B cells. The results show that PM₁ induces the increase of IL‐6 and IL‐8 in BEAS‐2B cells and up‐regulates the miR‐146a expression by activating NF‐κB signaling pathway. Overexpressed miR‐146a prevents the nuclear translocation of p65 through inhibiting the IRAK1/TRAF6 expression, and downregulates the expression of IL‐6 and IL‐8. Taken together, these results demonstrate that miR‐146a can negatively feedback regulate PM₁‐induced inflammation via NF‐κB signaling pathway in BEAS‐2B cells.     

Expression of pro‐inflammatory cytokines and mediators induced by Bisphenol A via ERK‐NFκB and JAK1/2‐STAT3 pathways in macrophages

Macrophages not only play an important role in the innate immune response but also participate in many inflammatory and infectious diseases including asthma, diabetes, obesity, cardiovascular diseases, and cancers. Bisphenol A (BPA) is the most commonly used component for plastic products. However, BPA is an endocrine disruptor for mammals and participates in several inflammatory and infectious diseases. Up until now, there are no researches demonstrated the potential role of BPA in macrophage activation and its relative mechanism. BPA promoted the generation of proinflammatory cytokines IL‐1β, IL‐6, and TNFα in a concentration‐dependent manner (P < 0.05). BPA was identified to increase the expression of proinflammatory mediators NO and PGE2, and its upstream factors iNOS, COX2, and cPLA2 in a concentration‐dependent manner (P < 0.05). Phosphorylation and nuclear translocation of NF‐κB p65 were significantly induced by BPA via IκB degradation (P < 0.05). In addition, phosphorylation of ERK significantly induced by BPA at a concentration which was less than that for phosphorylation of p38 MAPK and JNK (P < 0.05). Furthermore, phosphorylation of STAT3 significantly induced by BPA at a concentration lower than that for phosphorylation of STAT1 (P < 0.05). Phosphorylation of JAK1 and JAK2 was also significantly induced by BPA in a concentration‐dependent manner (P < 0.05).     

Mycophenolate mofetil improves renal haemodynamics,microvascular oxygenation,and inflammation in a rat model of supra‐renal aortic clamping‐mediated renal ischaemia reperfusion injury

Ischaemia/reperfusion (I/R) is one of the main causes of acute kidney injury (AKI), which is characterized by sterile inflammation and oxidative stress. Immune cell activation can provoke overproduction of inflammatory mediators and reactive oxygen species (ROS), leading to perturbation of the microcirculation and tissue oxygenation associated with local and remote tissue injury. This study investigated whether the clinically employed immunosuppressant mycophenolate mofetil (MMF) was able to reduce I/R‐induced renal oxygenation defects and oxidative stress by preventing sterile inflammation. Rats were divided into three groups (n=6/group): (1) a sham‐operated control group; (2) a group subjected to renal I/R alone (I/R); and (3) a group subjected to I/R and MMF treatment (20 mg/kg prior to I/R) (I/R+MMF). Ischaemia was induced by a vascular occluder placed on the abdominal aorta for 30 minutes, followed by 120 minutes of reperfusion. Renal I/R deteriorated renal oxygenation (P<.001) and oxygen delivery (P<.01), reduced creatinine clearance (P<.01) and tubular sodium reabsorption (P<.001), and increased iNOS, renal tissue injury markers (P<.001), and IL‐6 (P<.001). Oral MMF administration prior to insult restored renal cortical oxygenation (P<.05) and iNOS, renal injury markers, and inflammation parameters (P<.001) to near‐baseline levels without affecting renal function. MMF exerted a prophylactic effect on renal microvascular oxygenation and abrogated tissue inflammation and renal injury following lower body I/R‐induced AKI. These findings may have clinical implications during major vascular or renal transplant surgery.     

Protectin DX ameliorates palmitate‐induced hepatic insulin resistance through AMPK/SIRT1‐mediated modulation of fetuin‐A and SeP expression

The role as well as the molecular mechanisms of protectin DX (PDX) in the prevention of hepatic insulin resistance, a hallmark of type 2 diabetes, remains unknown. Therefore, the present study was designed to explore the direct impact of PDX on insulin resistance and to investigate the expression of fetuin‐A and selenoprotein P (SeP), hepatokines that are involved in insulin signalling, in hepatocytes. Human serum levels of PDX as well as fetuin‐A and SeP were determined by high‐performance liquid chromatography (HPLC). Human primary hepatocytes were treated with palmitate and PDX. NF‐κB phosphorylation as well as expression of insulin signalling associated genes and hepatokines were determined by Western blotting analysis. FOXO1 binding levels were measured by quantitative real‐time PCR. Selected genes from candidate pathways were evaluated by small interfering (si) RNA‐mediated gene suppression. Serum PDX levels were significantly (P < 0.05) downregulated, whereas serum fetuin‐A and SeP levels were increased (P < 0.05) in obese subjects compared with healthy subjects. In in vitro experiments, PDX treatment increased AMP‐activated protein kinase (AMPK) phosphorylation and SIRT1 expression and attenuated palmitate‐induced fetuin‐A and SeP expression and insulin resistance in hepatocytes. AMPK or SIRT1 siRNA mitigated the suppressive effects of PDX on palmitate‐induced fetuin‐A through NF‐κB and SeP expression linked to FOXO1 and insulin resistance. Recombinant fetuin‐A and SeP reversed the suppressive effects of fetuin‐A and SeP expression on palmitate‐mediated impairment of insulin signalling. The current finding provides novel insight into the underlying mechanism linking hepatokines to the pathogenesis of hepatic insulin resistance.     

C‐phycocyanin protects against ethanol‐induced gastric ulcers in rats: Role of HMGB1/NLRP3/NF‐κB pathway

Gastric ulcer is a widespread inflammatory disease with high socio‐economic burden. C‐phycocyanin is one of the active constituents of Spirulina microalgae, and although it is well known for its antioxidant and anti‐inflammatory properties, its protective effects against gastric ulcer have not yet been identified. High‐mobility group box 1 (HMGB1) is a nuclear protein that, once secreted extracellularly, initiates several inflammatory reactions, and it is involved in the pathogenesis of gastric ulcer. The aim of the present study was to investigate the anti‐inflammatory and anti‐ulcerogenic effects of C‐phycocyanin against ethanol‐induced gastric ulcer targeting HMGB1/NLRP3/NF‐κB pathway. Ulcer induction showed increase in HMGB1 expression through activation of nucleotide‐binding domain and leucine‐rich repeat‐containing protein 3 (NLRP3) inflammasome and nuclear factor kappa p65 (NF‐κB p65). Moreover, oxidative stress and inflammatory markers were elevated in the ulcer‐treated group compared to the normal control group. However, pre‐treatment with C‐phycocyanin significantly reduced HMGB1 expression via suppression of NLRP3/NF‐κB, oxidative markers, IL‐1β, tumour necrosis factor‐α (TNF‐α) and ulcer index value. These results were consistent with histopathological and immunohistochemistry examination. Thus, C‐phycocyanin is a potential therapeutic strategy with anti‐inflammatory and anti‐ulcerogenic effects against ethanol‐induced gastric ulcer.     

Regorefenib induces extrinsic/intrinsic apoptosis and inhibits MAPK/NF‐κB‐modulated tumor progression in bladder cancer in vitro and in vivo

The aim of the present study is to investigate anticancer effect and mechanism of regorafenib in bladder cancer in vitro and in vivo. Human bladder cancer TSGH 8301 cells were treated with regorafenib, NF‐κB, AKT, or mitogen‐activated protein kinase (MAPK) inhibitors for different time. The changes of cell viability, NF‐κB activation, apoptotic signaling transduction, and expression of tumor progression‐associated proteins were evaluated with MTT, NF‐κB reporter gene assay, flow cytometry, and Western blotting assay. TSGH 8301 tumor bearing mice were established and treated with vehicle (140 μL of 0.1% DMSO) or regorafenib (10 mg/kg/day by gavage) for 15 days. The changes of tumor volume, body weight, NF‐κB activation, MAPK activation, and tumor progression‐associated proteins (MMP‐9, XIAP, VEGF, and Cyclin‐D1) after regorafenib treatment were evaluated with digital caliper, digital weight, and ex vivo Western blotting assay. Our results demonstrated NF‐κB activation and protein levels of MMP‐9, XIAP, VEGF, and Cyclin‐D1 were significantly reduced by NF‐κB (QNZ), ERK (PD98059), and P38 (SB203580) inhibitors. Regorafenib also significantly induced extrinsic and intrinsic apoptotic signaling transduction in bladder cancer in vitro. In addition, regorafenib significantly inhibited tumor growth, NF‐κB, p38, ERK activation and expression of tumor progression‐associated proteins in bladder cancer in vitro and in vivo. Taken together, these results proved that regorafenib not only induced apoptosis through extrinsic and intrinsic pathways and but suppressed MAPK/ NF‐κB‐modulated tumor progression in bladder cancer.     

Mechanism of sphingosine‐1‐phosphate induced cardioprotection against I/R injury in diabetic rat heart: Possible involvement of glycogen synthase kinase 3β and mitochondrial permeability transition pore

There is growing evidence that diabetes mellitus causes attenuation of the bioactive metabolite of membrane sphingolipids, sphingosine‐1‐phosphate, and this may be a key mechanism in the decreased cardioprotective effect of ischaemic preconditioning (IPC) in the diabetic heart. Thus, this study has been designed to investigate the role and pharmacological potential of sphingosine‐1‐phosphate in diabetic rat heart. Diabetes was produced in Wistar rats by administration of a low dose of streptozotocin (STZ) (35 mg/kg, i.p., once) and feeding a high fat diet (HFD) for 6 weeks. Isolated rat heart was subjected to 30 min ischaemia followed by 120 min of reperfusion (I/R). The heart was subjected to pre‐ischaemic treatment (before ischaemia for 20 min) and pharmacological preconditioning with the S1P agonist FTY720 (0.6 μmol/L) with and without atractyloside (an mPTP opener; in the last episode of reperfusion before I/R). Myocardial infarction was assessed in terms of increase in lactate dehydrogenase (LDH), creatinine kinase‐MB (CK‐MB), myeloperoxidase (MPO) level and infarct size (triphenyltetrazolium chloride staining). Immunohistochemistry analysis was done for assessment of tumour necrosis factor (TNF)‐α and glycogen synthase kinase (GSK)‐3β level in cardiac tissue. Pre‐ischaemic treatment and pharmacological preconditioning with FTY720 significantly decreased I/R‐induced myocardial infarction, TNF‐alpha, GSK‐3β level and release of LDH and CK‐MB as compared to control group. The cardioprotective effect of S1P agonist was significantly attenuated by atractyloside. It may be concluded that S1P agonist FTY720 prevents the diabetic heart from ischaemic reperfusion injury, possibly through inhibition of GSK‐3β and regulation of opening of mitochondrial permeability transition pore.     

Inhibition of NF‐κB and metastasis in irinotecan (CPT‐11)‐resistant LoVo colon cancer cells by thymoquinone via JNK and p38

Clinically used chemotherapeutics can effectively eliminate most tumor cells. However, they cause unwanted side effects and result in chemoresistance. To overcome such problems, phytochemicals are now used to treat cancers by means of targeted therapy. Thymoquinone (TQ) is used to treat different cancers (including colon cancer) and is an NF‐κB inhibitor. Irinotecan resistant (CPT‐11‐R) LoVo colon cancer cell line was previous constructed by step‐wise CPT‐11 challenges to un‐treated parental LoVo cells and expresses EGFR/IKKα/β/NF‐κB pathway. TQ resulted in reduced total and phosphorylation of IKKα/β and NF‐κB and decreased metastasis in CPT‐11‐R cells. TQ not only reduced activity of ERK1/2 and PI3K but also activated JNK and p38. Furthermore, TQ was also found to suppress metastasis through activation of JNK and p38. Therefore, TQ suppressed metastasis through NF‐κB inhibition and activation of JNK and p38 in CPT‐11‐R LoVo colon cancer cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 669–678, 2017.     

Acetaminophen‐induced hepatocyte injury: C2‐ceramide and oltipraz intervention,hepatocyte nuclear factor 1 and glutathione S‐transferase A1 changes

Acetaminophen (APAP) is an antipyretic and analgesic, which is commonly associated with drug‐induced hepatic injury. C2‐ceramide plays a key role in mediating cell life activities, and oltipraz was extensively studied as a cancer chemopreventive agent. Glutathione S‐transferase A1 (GSTA1) acts as a vital liver detoxification enzyme. Hepatocyte nuclear factor 1 (HNF‐1) regulates various cellular signaling pathways. In this study, we investigated the effects of C2‐ceramide and oltipraz on APAP‐induced hepatocyte injury and the changes of HNF‐1 and GSTA1. Results showed that C2‐ceramide (6 μmol/L) exacerbated APAP‐induced hepatocyte injury and caused a significant decrease (P < .01) in HNF‐1 and GSTA1 expressions. Meanwhile, GSTA1 content in supernatant was significantly increased (P < .01). In contrast, oltipraz (8 μmol/L) reduced the injury and significantly elevated (P < .01) HNF‐1 and GSTA1 expressions while GSTA1 content in supernatant was significantly decreased (P < .01). In conclusion, these findings revealed that C2‐ceramide inhibited HNF‐1 and GSTA1 expression and exacerbated hepatocyte injury, while oltipraz treatment results in the reduction of hepatocyte injury, and promoted HNF‐1 and GSTA1 expression. Additionally, the changes in HNF‐1 and GSTA1 were related to APAP‐induced hepatocyte injury. These results were useful to investigate the mechanism of an antipyretic and analgesic drug combination.     

Nonylphenol regulates cyclooxygenase‐2 expression via Ros‐activated NF‐κB pathway in sertoli TM4 cells

The aim of this study was to investigate the signaling pathways involved in the cyclooxygenase (COX)‐2 regulation induced by nonylphenol (NP) in mouse testis Sertoli TM4 cells. Our results showed that treatment of TM4 cells with NP increased COX‐2 protein expression and interleukin‐6 (IL)‐6 and prostaglandin E2 (PGE2) secretion in a dose‐dependent manner. Pretreatment with reactive oxygen species (ROS) scavenger, N‐acetylcysteine (NAC), attenuated NP‐induced ROS production, COX‐2 expression, and IL‐6 and PGE2 release in TM4 cells. Exposure to NP stimulated activation of NF‐κB, whereas the NF‐κB inhibitor, pyrrolidine dithiocarbamate, attenuated NP‐enhanced COX‐2 expression and IL‐6 and PGE2 release in TM4 cells in a dose‐dependent manner. Furthermore, NAC blocked NP‐induced activation of NF‐κB. In addition, inhibition of COX‐2 mitigated NP‐induced IL‐6 release. In conclusion, NP induced ROS generation, activation of NF‐κB pathway, COX‐2 upregulation, and IL‐6 and PGE2 secretion in TM4 cells. NP may regulate COX‐2 expression via ROS‐activated NF‐κB pathway in Sertoli TM4 cells. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1144–1152, 2015.