Effect of autophagy on necroptosis of renal tubular epithelial cells in subtotal nephrectomy rats

AIM: To explore whether autophagy is involved in the excessive death of renal tubular epithelial cells in subtotal nephrectomy(SNx) rats and the relationship between autophagy and necroptosis in the kidney of SNx rats. METHODS: Male Sprague-Dawley rats were randomly assigned to control group(n=6) and SNx group(n=42). The rats in SNx group were subjected to SNx. Sham surgery was performed in the rats in control group. The rats in SNx group were divided into subgroups at 0, 4, 8 and 12 weeks(n=6) and the other rats in SNx group were divided into SNx+vehicle group, SNx+necrostatin-1(Nec-1) group and SNx+3-methyladenine(3-MA) group. The expression of RIP1, RIP3, LC3 and beclin-1 at mRNA and protein levels was measured at 0, 4, 8 and 12 weeks by qPCR and immunohistochemistry. The effects of Nec-1 or 3-MA on the protein expression of LC3-I, LC3-II and beclin-1, and production of reactive oxygen species(ROS) in the rat kidney were determined by Western blot and DCFH-DA staining. The death of renal tubular epithelial cells in the SNx rats was observed by TUNEL staining and electron microscopy. Finally, the effects of Nec-1 and 3-MA on blood urea nitrogen(BUN), serum creatinine(SCr) and the pathological changes of the renal tissues were analyzed. RESULTS: The highest mRNA and protein levels of RIP1, RIP3, LC3 and beclin-1 appeared at the 8th week after SNx(P<0.01). Compared with the rats in SNx+vehicle group, the protein over-expression of LC3-II/I and beclin-1, renal tubular epithelial cells with typical morphological features of necroptotic cell death and TUNEL-positive renal tubular cells were decreased in the SNx rats treated with Nec-1 and 3-MA(P<0.01), but 3-MA did not reduce the increased concentration of ROS. In addition, treatment with Nec-1 and 3-MA obviously reduced BUN, SCr(P<0.05), glomerulosclerosis index and tubulointerstitial injury score(P<0.01). CONCLUSION: Autophagy participates in the excessive death of renal tubular epithelial cells in SNx rats. Inhibition of autograph prevents necroptotic cell death of renal tubular cells, and alleviates chronic renal injury in SNx rats.     

Activation of Rip1 promotes necroptosis in LNCaP-AI cells via inhibiting SHARPIN

AIM: To explore the role of SHARPIN in regulation of Rip1 in castration-resistant prostate cancer LNCaP-AI cells. METHODS: The LNCaP-AI cells were treated with TNF-α+Z-VAD(an inhibitor of pan-caspase) to activate necroptosis, which were compared to the cells treated with TNF-α+Z-VAD+Nec-1(an inhibitor of Rip1). A blank group and a TNF-α-treated group were set up as controls. The cell viability in each group was measured by MTS assay. In addition, SHARPIN was knocked down by siRNA, and the inhibitory efficiency was evaluated by RT-qPCR. The expression of Rip1 at mRNA and protein levels after knocking down SHARPIN was determined by RT-qPCR and Western blot to explore the underlying mechanism of regulatory network of necroptosis in prostate cancer. RESULTS: Compared with blank control group and TNF-α-treated group, the viability of LNCaP-AI cells treated with TNF-α+Z-VAD decreased by 28%(P<0.05). After treated with TNF-α+Z-VAD+Nec-1, the LNCaP-AI cells showed no significant difference in the viability compared with blank control and TNF-α-treated groups. Taken together, necroptosis may be an important way of cell death in LNCaP-AI cells. Besides, the expression of Rip1 at protein level was up-regulated following the inhibition of SHARPIN using siRNA, indicating that down-regulation of SHARPIN enhanced necroptosis via activating Rip1 in LNCaP-AI cells. CONCLUSION: Necroptosis is an important way of cell death.Inhibition of oncogenic factor SHARPIN enhances necroptosis via activating Rip1 in LNCaP-AI cells.     

Angiotensin-(1-7) protects H9c2 cardiac cells against high glucose-induced injury and inflammation by inhibiting the interaction between TLR4 activation and necroptosis

AIM: To investigate whether angiotensin-(1-7)[Ang-(1-7)] protects H9c2 cardiac cells against high glucose (HG)-induced injury and inflammation by inhibiting the interaction between Toll-like receptor 4 (TLR4) activation and necroptosis. METHODS: The expression levels of receptor-interacting protein 3 (RIP3; an indicator of necroptosis) and TLR4 were determined by Western blot. Cell viability was measured by CCK-8 assay. The activity of lactate dehydrogenase (LDH) in the culture medium was measured with a commercial kit. The releases of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were measured by ELISA. The intracellular level of reactive oxygen species (ROS) was analyzed by 2', 7'-dichlorfluorescein-diacetate (DCFH-DA) stating followed by photofluorography. Mitochondrial membrane potential (MMP) was examined by rhodamine 123 staining followed by photofluorography. RESULTS: After the H9c2 cardiac cells were treated with HG (35 mmol/L glucose) for 24 h, the expression of RIP3 was obviously increased. Co-treatment of the cells with 30 μmol/L TAK-242 (an inhibitor of TLR4) attenuated the up-regulation of RIP3 induced by HG. Furthermore, the expression of TLR4 was significantly increased after the cells were exposed to HG for 24 h, and co-treatment of the cells with 100 μmol/L necrostatin-1 (Nec-1; a specific inhibitor of necroptosis) and HG for 24 h attenuated the up-regulation of TLR4 expression induced by HG. Moreover, 1 μmol/L Ang-(1-7) simultaneously blocked the up-regulation of the RIP3 and TLR4 induced by HG. On the other hand, co-treatment of the cells with 1 μmol/L Ang-(1-7), 30 μmol/L TAK-242 or 100 μmol/L Nec-1 and HG for 24 h attenuated HG-induced injuries and inflammatory response, leading to the increase in the cell viability, and the decreases in the activity of LDH, ROS generation, MMP loss as well as the releases of IL-1β and TNF-α. CONCLUSION: Ang-(1-7) protects H9c2 cardiac cells against HG-induced injury and inflammation by inhibiting the interaction between TLR4 activation and necroptosis.     

Hydrogen sulfide protects H9c2 cardiomyocytes against high glucose-induced injury by inhibiting necroptosis

AIM: To study whether hydrogen sulfide(H₂S) protects H9c2 cardiomyocytes against high glucose(HG)-induced injury by inhibiting necroptosis. METHODS: The protein levels of RIP3(an indicator of necroptosis) and cleaved caspase-3 were determined by Western blot. The cell viability was measured by CCK-8 assay. The intracellular le-vels of reactive oxygen species(ROS) were detected by 2', 7'-dichlorfluorescein diacetate staining followed by photofluorography. Mitochondrial membrane potential(MMP) was examined by rhodamine 123 staining followed by photofluorography. The number of apoptotic cells was observed by Hoechst 33258 nuclear staining followed by photofluorography. RESULTS: After the H9c2 cells were treated with HG(35 mmol/L glucose) for 0~24 h, the protein expression of RIP3 in the H9c2 cells was significantly increased at 3 h, 6 h, 9 h, 12 h and 24 h, reaching the maximum level at 24 h. Pretreatment of the cells with 400μmol/L NaHS(a donor of H₂S) or co-treatment of the cells with necrostatin-1(Nec-1; a speci-fic inhibitor of necroptosis) considerably blocked the up-regulation of RIP3 protein induced by HG. Moreover, pretreatment with NaHS or co-treatment with Nec-1 obviously inhibited HG-induced injuries, leading to an increase in the cell viability, and decreases in the generation of ROS and MMP loss. On the other hand, pretreatment with NaHS also reduced the number of apoptotic cells and the protein level of cleaved caspase-3 in the HG-treated H9c2 cardiomyocytes. CONCLUSION: H₂S protects H9c2 cardiomyocytes against HG-induced injury by inhibiting necroptosis.     

A model of necroptosis in human renal tubular epithelial cells

AIM:To make a model of necroptosis in human renal tubular epithelial HK-2 cells. METHODS:To induce necroptosis, HK-2 cells were treated with tumor necrosis factor α (TNF-α) followed by ATP depletion, and benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk) was added to block the activity of caspase-8. The morphological changes of the cells were observed under light microscope and electronic microscope.The cell viability was detected by CCK-8 assay, and the marker of necroptosis was analyzed by Western blotting. RESULTS:In the cells treated with TNF-α followed by zVAD-fmk and antimycin A for 1 h, the morphological changes including the cell and organelle inflation, and membrane fragmentation, with a large amount of autophagysome, were observed.However, these abnormalities were markedly attenuated after treatment with Nec-1. Meanwhile, the cell viability was also significantly improved after using Nec-1. No similar variation was observed in other groups. In addition, the expression of LC3-II was significantly decreased in Nec-1+TNF-α+zVAD-fmk+ antimycin A (1 h) group compared with control group. CONCLUSION: TNF-α stimulation and energy depletion induce necroptosis in renal tubular epithelial cells.Nec-1 inhibits necroptosis in a caspase-independent pathway, and may have therapeutic potential to prevent and treat renal ischemia injury.     

Effect of RIP3 expression on apoptosis of mouse macrophages infected with BCG

AIM:To investigate the function of receptor-interacting proteins 3 (RIP3) in regulating Bacillus Calmette-Guérin (BCG)-induced apoptosis of mouse macrophages (RAW264.7 cells). METHODS:The RIP3 adenovirus interference vector was constructed and used to infect the RAW264.7 cells, and then the RAW264.7 cells were infected with BCG. The cell viability was measured by MTT assay. The apoptotic rate, mitochondrial membrane potential and production of reactive oxygen species (ROS) were determined by flow cytometry analysis. The protein levels of RIP3 and apoptosis-associated proteins were examined by Western blot. RESULTS:The viability of RAW264.7 cells was decreased after BCG infection. In the meantime, the expression of RIP3 was up-regulated significantly (P<0.01). Compared with BCG infection group, the apoptotic rate and ROS level in BCG and RIP3 adenovirus interference vector co-infection group were significantly decreased (P<0.01). Importantly, RIP3 was able to further promote apoptosis in BCG-infected RAW264.7 cells in part by increasing mitochondrial membrane potential (P<0.01). In addition, Western blot analysis further demonstrated that RIP3 was involved in BCG-induced apoptosis partly through down-regulation of anti-apoptotic protein Bcl-2, and up-regulation of Bax and cleaved caspase-3 (P<0.01). CONCLUSION:RIP3 is involved in BCG-induced apoptosis of RAW264.7 cells, and this process may be achieved by the mitochondrial pathway.     

RIP1-mediated necroptosis regulates inflammatory response of renal tubular epithelial cells via NF-κB signaling pathway

AIM To investigate the effect of receptor-interacting protein 1 (RIP1)-mediated necroptosis on human kidney proximal tubular cell inflammation and its related mechanisms. METHODS Human kidney proximal tubular HK-2 cells were cultured in vitro, and stimulated with tumot tumor necrosis factor-α (TNF-α) and Z-VAD-FMK for 24 h. Lactate dehydrogenase (LDH) cytotoxicity assay was used to detect the percentage of necrosis. Western blot was used to detect the protein expression of RIP1, IKK-α and NF-κB p65. The protein levels of interleukin-1β (IL-1β) and monocyte chemoattractant protein-1 (MCP-1) were determined by Western blot and ELISA. Real-time PCR was used to detect the mRNA expression level of NF-κB p65. Furthermore, the RIP1 inhibitor necrostatin-1 (Nec-1) and the NF-κB specific inhibitor ammonium pyrrolidinedithiocarbamate (PDTC) were used, and the above indicators were also detected. RESULTS Compared with control group, the protein level of RIP1 was increased in TNF-α combined with Z-VAD-FMK stimulation group (T/Z group). The protein levels of IKK-α and NF-κB p65 were obviously increased, and the release of LDH was increased (P<0.01). Western blot and ELISA showed that the expression levels of IL-1β and MCP-1 were significantly increased (P<0.01). Real-time PCR showed that the mRNA expression level of NF-κB p65 was also obviously increased. After Nec-1 or PDTC stimulation (T/Z+N group or T/Z+P group), the release of LDH, and the expression levels of inflammation-related indicators IL-1β and MCP-1 were significantly decreased. The protein expression levels of IL-1β and MCP-1 were further reduced after treatment with the above 2 stimulati (T/Z+P/N group). CONCLUSION Under T/Z condition, RIP1-mediated necroptosis plays an important role in renal tubular inflammatory response, which may be partly achieved by regulating the activation of NF-κB signaling pathway.     

Inhibition of HMGB1 expression promotes apoptosis of hemangioma endothelial cells

AIM: To investigate the effect of inhibiting high-mobility group box protein 1 (HMGB1) expression on the viability and apoptosis of hemangioma endothelial cells (HemECs). METHODS: Human HemECs were isolated and cultured, and HMGB1 small interfering RNA (HMGB1-siRNA) was transfected into the cells. The cell viability was detected by CCK-8 assay. The apoptosis and reactive oxygen species (ROS) content were analyzed by flow cytometry. The protein levels of HMGB1, NF-κB p65, p-IκBα, cyclin D1 and survivin were determined by Western blot. RESULTS: The protein expression of HMGB1 in the HemECs transfected with HMGB1-siRNA was significantly lower than that in blank control group (P<0.05). Compared with NC group, the cell viability was decreased significantly in the HemECs transfected with HMGB1-siRNA, the apoptotic rate was significantly increased, the content of ROS increased significantly, and the protein levels of NF-κB p65, p-IκBα, cyclin D1 and survivin were significantly decreased (P<0.05). After exposure to NF-κB signaling pathway inhibitor PDTC, the cell viability was inhibited, the apoptosis was increased, ROS content, and the protein levels of NF-κB p65, p-IκBα, cyclin D1 and survivin were down-regulated significantly, as compared with si-HMGB1 group (P<0.05). CONCLUSION: Inhibition of HMGB1 reduces the viability of HemECs and induces apoptosis by increasing the content of ROS and down-regulating the activity of NF-κB signaling pathway.     

Clinical significance of STMN1 expression in cervical cancer and effect of inhibition of its expression on viability and apoptosis of cervical cancer SiHa cells

AIM: To investigate the clinical significance of stathmin 1 (STMN1) expression in cervical cancer and the influence of its expression on the viability and apoptosis of cervical cancer cells. METHODS: Western blot was used to detect the protein expression of STMN1 in cervical cancer tissues, and the relationship between the expression and clinical characteristics of cervical cancer was analyzed. STMN1-siRNA was transfected into cervical squamous-cell carcinoma SiHa cells. The protein levels of STMN1, STAT3, p-STAT3 and survivin were determined by Western blot after transfection for 48 h. The cell viability was measured by MTT assay. The apoptosis was analyzed by flow cytometry. DCFH-DA probe was used to detect the level of reactive oxygen species (ROS). RESULTS: The protein expression of STMN1 in cervical cancer tissues was significantly higher than that in paracancerous tissues (P<0.01). The STMN1 protein expression level was not correlated with age and histological types of cervical cancer patients, but was related to clinical stage, histological differentiation and lymph node metastasis (P<0.01). Transfection with STMN1-siRNA significantly reduced the expression of STMN1 in SiHa cells. Compared with control group, the cell viability in STMN1-siRNA group was significantly decreased, the apoptotic rate and ROS content were increased, and the protein levels of p-STAT3 and survivin were down-regulated (P<0.01). However, no significant difference of the STAT3 protein level was observed between STMN1-siRNA group and control group. CONCLUSION: STMN1 is highly expressed in cervical cancer, and its expression is related to clinical stage, histological differentiation and lymph node metastasis. Inhibition of STMN1 expression reduces the viability and promotes apoptosis of cancer cells by down-regulating STAT3 signaling pathway.     

Effects of procyanidins on oxidative damage of osteocytes caused by TCP wear particles

AIM: To investigate the effects of procyanidins (PC) on oxidative damage of osteocytes caused by tricalcium phosphate (TCP) wear particles, and to explore the underling mechanism. METHODS: Mouse long bone osteocyte MLO-Y4 cells were treated with TCP wear particles (0.1 g/L) for 48 h to establish the model of osteocyte injuries. The MLO-Y4 cells were divided into 4 groups:control group, TCP group, PC (10 μmol/L) group and PC (50 μmol/L) group. Calcein-AM staining and MTT assay were used to observe the viability of MLO-Y4 cells. The levels of dentin matrix protein 1 (DMP-1), sclerostin (SOST) and interleukin-1β (IL-1β) in the culture media were examined by ELISA. The apoptosis of MLO-Y4 cells was analyzed by flow cytometry with Annexin V/PI double staining. The malondialdehyde (MDA) content and superoxide dismutase (SOD) activity of MLO-Y4 cells, and lactate dehydrogenase (LDH) release in the culture media were measured by chemical colorimetry. The protein levels of NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), cleaved caspase-1 and IL-1β in the MLO-Y4 cells were determined by Western blot. RESULTS: Compared with control group, MLO-Y4 cell injuries, apoptosis rate and MDA level were obviously increased in TCP group, while SOD activity was significantly decreased (P<0.05) The protein levels of NLRP3, ASC, cleaved caspase-1 and IL-1β were remarkably up-regulated (P<0.05) in the MLO-Y4 cells, and the level of IL-1β and LDH release were increased in the culture media (P<0.05). Compared with TCP group, the injuries of MLO-Y4 cells, apoptosis rate and MDA level were decreased obviously (P<0.05) in PC groups, whereas SOD activity was increased (P<0.05). The protein levels of NLRP3, ASC, cleaved caspase-1 and IL-1β were down-regulated remarkably in the MLO-Y4 cells (P<0.05), and the level of IL-1β and LDH release were significantly decreased in the culture media (P<0.05). CONCLUSION: PC obviously inhibit oxidative damage of osteocytes caused by TCP wear particles, which may be related to alleviating NLRP3 inflammasome activation and pyroptosis.     

Role of ATP-sensitive potassium channels in inhibitory effect of hydrogen sulfide on high glucose-induced inflammation mediated by necroptosis in H9c2 cardiac cells

AIM: To investigate the role of ATP-sensitive potassium (K_ATP) channels in the inhibitory effect of hydrogen sulfide (H₂S) on high glucose(HG)-induced inflammation mediated by necroptosis in H9c2 cardiac cells.METHODS: The expression levels of receptor-interacting protein 3 (RIP3; an indicator of necroptosis) and cyclooxyge-nase-2 (COX-2) were determined by Western blot. The levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were detected by ELISA.RESULTS: After H9c2 cardiac cells were treated with 35 mmol/L glucose (HG) for 24 h, the expression of RIP3 was significantly increased. Pre-treatment of the cells with 100 μmol/L diazoxide (DZ; a K_ATP channel opener) or 400 μmol/L NaHS (a donor of H₂S) for 30 min considerably blocked the up-regulation of RIP3 induced by HG. Moreover, pre-treatment of the cells with 100 μmol/L 5-hydroxydecanoic acid (5-HD; a K_ATP channel blocker) attenuated the inhibitory effect of NaHS on HG-induced up-regulation of RIP3. On the other hand, co-treatment of the cells with 100 μmol/L necrostatin-1 (a specific inhibitor of necroptosis) or pre-treatment of the cells with 100 μmol/L DZ or 400 μmol/L NaHS attenuated HG-induced inflammatory responses, evidenced by decreases in the expression of COX-2 and secretion levels of IL-1β and TNF-α. However, pre-treatment of the cells with 100 μmol/L 5-HD significantly attenuated the above anti-inflammatory effects of NaHS.CONCLUSION: K_ATP channels play an important role in the inhibitory effect of H₂S on HG-induced inflammation mediated by necroptosis in H9c2 cardiac cells.     

Combination of LPS and z-VAD-FMK mediates necroptosis in IFN-γ-pretreated macrophages

AIM:To explore the mechanism of necroptosis in M1 macrophages mediated by lipopolysaccharide (LPS) combined with z-VAD-FMK. METHODS:THP-1 cells were induced to differentiate into M0 and M1 macrophages with phorbol 12-myristate 13-acetate (PMA) and interferon-γ (IFN-γ). The release of lactate dehydrogenase (LDH) and TUNEL-positive cells at different time points after LPS (100 μg/L) treatment were detected, and the effects of different inhibitors were observed. The protein levels of receptor-interacting protein (RIP) 1, RIP3, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), P38 and NOD-like receptor protein 3 (NLRP3) were determined by Wes-tern blot. RESULTS:LPS mediated cell death, and its combination with z-VAD-FMK specifically mediated necroptosis in M1 macrophages rather than M0 ones. The expression of RIP3 and NLRP3 was upregulated by IFN-γ, and LPS-mediated phosphorylation of JNK was also enhanced by IFN-γ. The inhibitors against RIP3 and JNK partly blocked LDH release mediated by LPS combined with z-VAD-FMK. CONCLUSION:Combination of LPS and z-VAD-FMK mediates necroptosis in IFN-γ-pretreated macrophages possibly by upregulation of RIP3 and enhancement of LPS-mediated JNK phosphorylation.     

Necroptosis mediates high glucose-induced injury in human umbilical vein endothelial cells

AIM: To explore whether necroptosis contributes to the high glucose (HG)-induced damage in human umbilical vein endothelial cells (HUVECs). METHODS: The protein levels of receptor-interacting protein 3 (RIP3) and cleaved caspase-3 were detected by Western blot. The intracellular levels of reactive oxygen species (ROS) were determined by DCFH-DA staining followed by photofluorography. Mitochondrial membrane potential (MMP) was measured by rhodamine 123 staining followed by photofluorography. RESULTS: Treatment of HUVECs with HG at different concentrations (10, 20 and 40 mmol/L glucose) for 24 h gradually enhanced the expression levels of RIP3. Treatment of HUVECs with HG (40 mmol/L glucose) for different time (3 h, 6 h, 9 h, 12 h and 24 h) also up-regulated the expression levels of RIP3, peaking at 9 h. Pretreatment of HUVECs with 20 μmol/L Z-VAD-FMK (an inhibitor of caspase) for 30 min before exposure to HG enhanced the expression level of RIP3. Pretreatment of HUVECs with 100 μmol/L necrostatin-1 (an inhi-bitor of necroptosis) for 1 h before exposure to HG alleviated the HG-induced injuries, such as a decrease in cell viability, an increase in ROS generation and dissipation of MMP, but up-regulated the protein level of cleaved caspase-3. CONCLUSION: Necroptosis mediates HG-induced injury in HUVECs. There is a negative interacting between necroptosis and apoptosis.     

Role of NOX1 in TNF-α-induced oxidative damage and inflammation in alveolar epithelial cells

AIM: To explore the role of NADPH oxidase 1 (NOX1) in tumor necrosis factor-α (TNF-α)-induced oxidative damage and inflammation in alveolar epithelial cells.METHODS: The mRNA and protein expression levels of NOX1 in alveolar epithelial cells after TNF-α treatment were determined by real-time PCR and Western blot. NOX1 siRNA and its negative control were transfected into the alveolar epithelial cells. After the induction of TNF-α, NOX1 levels in the cells were measured by real-time PCR and Western blot, and the content of malondialdehyde (MDA) in the cells was detected by thiobarbituric acid method. Xanthine oxidation assay was used to detect the activity of superoxide dismutase (SOD) in the cells. The contents of interleukin-4 (IL-4), IL-6 and IL-1β in cell culture medium were examined by ELISA. The rate of apoptosis was analyzed by flow cytometry. Western blot was used to detect the level of apoptotic protein cleaved caspase-3.RESULTS: The expression of NOX1 at mRNA and protein levels in TNF-α-induced cells was increased after induction (P<0.05). After transfection of NOX1 siRNA, the expression of NOX1 at mRNA and protein levels in the cell was downregulated (P<0.05). Transfection of siRNA negative control had no effect on the expression level of NOX1 in the cells. The content of MDA in the cells after TNF-α treatment was increased, the activity of SOD was reduced, the releases of IL-4, IL-6 and IL-1β by the cells were increased, and the apoptotic rate and the level of apoptotic protein cleaved caspase-3 were increased as compared with the cells that were not treated with TNF-α (P<0.05). The content of MDA in the cells with NOX1 knockdown induced by TNF-α was reduced, the activity of SOD elevated, and the releases IL-4, IL-6 and IL-1β, the apoptotic rate and the level of apoptotic protein cleaved caspase-3 decreased, as compared with the cells only treated with TNF-α induction (P<0.05).CONCLUSION: TNF-α induces the expression of NOX1 in the alveolar epithelial cells. Knockdown of NOX1 expression reduces cellular oxidative damage, releases of inflammatory factors, and cell apoptosis.     

Propofol inhibits LPS-induced inflammatory response in microglia via TRPV1 ion channels

AIM:To investigate the effects of propofol (P) on the inflammatory response of microglia induced by lipopolysaccharide (LPS) and the mechanisms. METHODS:Mouse microglia BV2 cells were treated with LPS at 100 μg/L to establish a neuroinflammatory injury model. The BV2 cells were divided into 4 groups:control group (C group), model group (L group), L+P group and LPS+AMG517 group (L+A group). The level of tumor necrosis factor-α (TNF-α) in the cell culture supernatant was measured by ELISA. The mRNA expression of transient receptor potential cation channel subfamily V member 1 (TRPV1) was detected by real-time PCR. The protein levels of TRPV1, TNF-α, interleukin-1β (IL-1β), interleukin-6 (IL-6) and phosphorylated calcium/calmodulin-dependent protein kinase Ⅱ (p-CaMKⅡ) were determined by Western blot. The content of free Ca²⁺ in the microglia BV2 cells was detected by Fluo-3 AM assay. RESULTS:Compared with C group, the level of TNF-α was significantly increased in L group (P<0.01), but that in P group was not changed. Compared with L group, the level of TNF-α was significantly lower than that in L+P group within 4 h (P<0.01). Compared with C group, the mRNA expression of TRPV1 was significantly increased in L group (P<0.01). Compared with L group, the mRNA expression of TRPV1 was significantly down-regulated in L+P group (P<0.01).Compared with L group, the protein levels of TNF-α, IL-1β, IL-6 and p-CaMKⅡ and intracellular Ca²⁺ concentration were significantly lower than those in L+P group and L+A group (P<0.01). CONCLUSION:Propofol inhibits the inflammatory response of microglia by reducing the expression of TNF-α, IL-1 and IL-6, which may be related to the down-regulation of TRPV1 and p-CaMKⅡ and the reduction of intracellular Ca²⁺ concentration.     

Effects of renal denervation on inflammatory factors in a rabbit model of early atherosclerosis

AIM: To evaluate the effects of renal denervation (RDN) on the expression of tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α) and interleukin-6 (IL-6) in a rabbit model of early atherosclerosis. METHODS: New Zealand male rabbits were divided into control group, RDN+ high-fat diet (HFD) group (RDN group), sham+HFD group (sham group) and HFD group. The rabbits in later 3 groups were fed with 2% cholesterol for 8 weeks to establish an early atherosclerosis model. The blood samples were collected to test the levels of lipids, norepinephrine (NE), TNF-α, IL-1α and IL-6. The protein expression of angiotensin Ⅱ (Ang Ⅱ) was detected by the method of immunohistochemistry. The levels of nuclear factor-κB (NF-κB) and Ang II 1 type receptor (AT1R) were evaluated by Western blot. The mRNA expression of TNF-α, IL-1α and IL-6 was determined by real-time PCR. RESULTS: After 1 d of RDN procedure, the NE level was lower in RDN group than that in sham group (P<0.01). After 8 weeks, the NE level was lower in RDN group than that in sham group and HFD group (P<0.05), and triglyceride (TG) was lower in RDN group than that in HFD group (P<0.05). The protein expression of Ang II was decreased in RDN group compared with sham group and HFD group (P<0.01). The protein expression of NF-κB was lower in RDN group than that in sham group (P<0.05). The plasma levels of TNF-α and IL-1α were reduced in RDN group compared with sham group and HFD group (P<0.05). The mRNA expression of TNF-α, IL-1α and IL-6 was reduced in RDN group compared with sham group (P<0.05). CONCLUSION: RDN inhibits sympathetic activity, decreases the plasma level of TG, and alleviates inflammatory reactions in the rabbits with atherosclerosis.     

Effect of HMGB1 expression knockdown on invasion ability of breast cancer cells induced by TNF-α

AIM:To investigate the effect of high-mobility group box-1 (HMGB1) expression knockdown on the invasion ability of breast cancer cells induced by tumor necrosis factor-α (TNF-α). METHODS:HMGB1 siRNA was used to transfect into the breast cancer MDA-MB-231 cells. The expression of HMGB1 at mRNA and protein levels was determined by RT-qPCR and Western blot. After the MDA-MB-231 cells with HMGB1 expression knockdown were treated with TNF-α, the apoptosis rate was analyzed by flow cytometry, the cell invasion ability was measured by Transwell assay, and the cell migration ability was detected by cell scratch test. The protein expression of E-cadherin, MMP-2, N-cadherin, MMP-9 and Bax was determined by Western blot. RESULTS:The expression of HMGB1 at mRNA and protein levels in the MDA-MB-231 cells transfected with HMGB1 siRNA was significantly lower than that in the non-transfected cells (P<0.05). The apoptosis rate in the cells was increased after TNF-α treatment, and the cell invasion and migration abilities were also increased. The protein level of E-cadherin in the cells was decreased, the protein level of N-cadherin was increased, and the protein levels of MMP-2, MMP-9 and Bax were also increased (P<0.05). After the MDA-MB-231 cells with HMGB1 expression knockdown were induced by TNF-α, the apoptotic rate was increased, the invasion and migration abilities were decreased, the protein levels of E-cadherin and Bax were increased, and the protein levels of N-cadherin, MMP-2 and MMP-9 were decreased, as compared with the cells only induced by TNF-α without knockdown of HMGB1 expression (P<0.05). CONCLUSION:Knockdown of HMGB1 expression enhances the apoptosis of breast cancer cells induced by TNF-α, and inhibited the cell invasion, migration and epithelial-mesenchymal transition induced by TNF-α. The mechanism may be related with the changes of protein expression of MMP-2, MMP-9 and Bax.     

Effects of resveratrol on TNF-α-induced injury and expression of MCP-1 in isolated rat pulmonary artery endothelial cells

AIM: To investigate the possible mechanism of resveratrol (Res) on tumor necrosis factor-α (TNF-α)-induced monocyte chemoattractant protein-1 (MCP-1) expression in primary rat pulmonary artery endothelial cells (RPAECs).METHODS: RPAECs were randomly divided into 4 groups:control group, solvent (1% DMSO) group, TNF-α group and Res group. Each group was divided into 1 h, 4 h and 8 h subgroups (n=6 per time point). The TNF-α+C1142 (a rodent chimeric mAb that neutralizes rat MCP-1) group was set up at the 8 h time point. At each time point, the protein and mRNA expression of MCP-1 was measured by Western blot and real-time PCR.RESULTS: Pretreatment of the RPAECs with C1142 significantly down-regulated the expression of MCP-1 (P<0.05). The protein and mRNA expression of MCP-1 was markedly increased in TNF-α group (P<0.05). Notably, incubation with Res down-re-gulated the protein and mRNA expression of MCP-1, which was significantly lower than that in TNF-α group (P<0.05).CONCLUSION: MCP-1 was involved in the process of TNF-α-induced injury of RPAECs. Res down-regulates the expression of MCP-1 in RPAECs, thus attenuating cell injury.     

Mycoplasma pneumoniae induces IL-1β production through activating NLRP3 inflammasome by ROS in RAW264.7 cells

AIM: To investigate whether Mycoplasma pneumoniae (Mp)-induced interleukin-1β (IL-1β) production in RAW264.7 cells is through the activation of NLRP3 inflammasome via reactive oxygen species (ROS). ME-THODS: RAW264.7 cells were randomly divided into 3 groups. In normal group, RAW264.7 cells were treated without Mp. In model group, RAW264.7 cells were treated with 1∶ 10 multiplicity of infection (MOI) of Mp. In NAC group, RAW264.7 cells were pretreated with N- acetylcysteine (NAC) at a concentration of 5 mmol/L for 30 min before infection with Mp. The RAW264.7cells were infected with Mp (1∶ 10 MOI) for 4, 8, 16 and 24 h in model group and NAC group, respectively. The intracellular ROS level was analyzed by flow cytometry. The mRNA expressions of NLRP3, ASC and caspase-1 were detected by real-time PCR. The protein levels of NLRP3, ASC and caspase-1 p20 were determined by Western blot. The levels of pro-inflammatory cytokine IL-1β in the supernatant were measured by ELISA. RESULTS: Compared with normal group, the production of ROS were significantly increased at 4, 8, 16 and 24 h after infection, the mRNA expression of NLRP3, ASC and caspase-1 were increased at 8, 16 and 24 h after infection, the protein levels of NLRP3, ASC and caspase-1 p20 were increased at 16 and 24 h after infection, and the releases of IL-1β were increased at 24 h after infection in model group (P<0.01). Compared with the model group, the level of ROS in NAC group decreased, so as the expression of NLRP3, ASC and caspase-1 at mRNA and protein levels and the releases of IL-1β in the supernatant at the corresponding time points. CONCLUSION: Mp may stimulate the ROS production to activate NLRP3 inflammasome in RAW264.7 cells.