Expression and function of PTEN in fibroblast-like synoviocytes of rheumatoid arthritis

AIM: investigate the expression of PTEN gene in fibroblast-like synoviocytes (FLS) of rheumatoid arthritis (RA).METHODS: FLS were isolated from synovial tissue obtained from the patients with RA, osteoarthritis (OA) or joint trauma. The mRNA expression of PTEN was detected by RT-qPCR. The protein levels of PTEN, p-Akt (Thr308) and total Akt were determined by Western blotting. The phosphorylation status of Akt was analyzed by the protein ratio of p-Akt (Thr308)/total Akt.RESULTS: The mRNA expression of PTEN was significantly lower in RA-FLS than that in OA-FLS and joint trauma-FLS (P < 0.01), while no statistically significant difference was observed between that in OA-FLS and joint trauma-FLS (P < 0.05). Similarly, the protein expression of PTEN in the RA-FLS was much lower than that in the OA-FLS and joint trauma-FLS (P < 0.05), and there was no difference between the latter 2 groups. Moreover, the phosphorylation level of Akt (Thr308) in the RA-FLS was significantly higher than that in the other 2 control groups (P < 0.01), and that in OA-FLS was much lower than that in the joint trauma-FLS (P < 0.01). Finally, Pearson correlation analysis between the phosphorylation level of Akt (Thr308) and PTEN protein expression in the RA-FLSs showed a significant negative correlation (r=-0.994 5, P < 0.01).CONCLUSION: The mRNA and protein expression of PTEN are both decreased in the RA-FLS, which may contribute to the increased phosphorylation level of Akt (Thr308).     

Effect of RICTOR expression on cell viability in rheumatoid arthritis fibroblast-like synoviocytes

AIM：To investigate the effects of RICTOR expression on the viability of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS). METHODS：RA-FLS were obtained by tissue culture. Chemically synthesized double-stranded siRNAs targeting RICTOR gene were transfected into RA-FLS by cationic liposome. The nonspecific siRNA was also transfected into the negative control cells. The mRNA expression of RICTOR was detected by RT-qPCR after transfection for 24 h. Western blotting was used to evaluate the inhibitory effects of siRNAs on RICTOR expression after transfection for 48 h and 72 h. The cell viability was examined by MTT assay. RESULTS：Compared with control group, the mRNA expression of RICTOR significantly decreased by 78.36%±3.71% after the transfection of RICTOR siRNA for 24 h. The protein level of RICTOR was also obviously lower in RICTOR siRNA transfection group than that in control group after transfection for 48 h (decreased by 92.48%±6.14%) and 72 h (decreased by 98.57%±1.40%). Knock-down of RICTOR in RA-FLS for 72 h markedly decreased the cell viability. CONCLUSION：Transfection of RICTOR siRNA reduces the viability of RA-FLS, indicating that mTORC2 may be required for the survival of RA-FLS.     

Effects of IL-22 on rheumatoid arthritis fibroblast-like synoviocytes

AIM: To determine the effects and mechanisms of interleukin-22(IL-22) on the fibroblast-like synoviocytes(FLSs) from rheumatoid arthritis(RA) patients. METHODS: RA-FLSs were cultured by tissue culture method. RA-FLSs were incubated with different concentrations of IL-22(0,1,10,100 μg/L) for 24 h, 48 h and 72 h. The cell viability was examined by CCK-8 assay. IL-22 at concentration of 10 μg/L was used to stimulate RA-FLSs for 24 h, and the change of cell cycle distribution was identified by flow cytometry. The effects of IL-22 at concentrations of 0, 1, 10, 100 μg/L and/or STA-21(a STAT3 inhibitor at concentrations of 0, 25, 50 μmol/L) on the protein levels of Bcl-2 and p-STAT3 in the RA-FLSs were determined by Western blot.RESULTS: Compared with control group, stimulation of rhIL-22 at different concentrations for 24 h, 48 h and 72 h, the cells viabilityof RA-FLSs were obviously increased(P<0.05). After co-cultured with 10 μg/L rhIL-22 for 24 h, the percentages of RA-FLSs were obviously increased in the G₂/M+S phase and decreased in the G₀/G₁ phase. At the same time, rhIL-22 increased, but STA-21 decreased the protein levels of Bcl-2 but p-STAT3 in the RA-FLSs obviously(P<0.05). Treatment with STAT3 inhibitor STA-21 reversed the effect of IL-22-induced Bcl-2 upregulation in the RA-FLSs(P<0.01). CONCLUSION: STAT3 is critical in the process of IL-22-induced Bcl-2 upregulation in RA-FLSs, indicating that IL-22 may play a role in the apoptosis of RA-FLSs.     

Relationship between anti-CCP antibody and migration or invasion ability of fibroblast-like synoviocytes from rheumatoid arthritis patients

AIM:To investigate the relationship between anti-cyclic citrullinated peptide (anti-CCP) antibody and migration or invasion ability of fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients. METHODS:FLS was isolated from 22 patients with active RA, 12 patients with osteoarthritis (OA) and 6 patients with joint injuries without arthritis history. The migration and invasion abilities were assessed by Transwell assay. RESULTS:Among the patients of RA, OA and normal controls, the numbers of migratory cells were (29.33±10.93), (9.28±7.87) and (7.00±4.07)/field, respectively, and the numbers of invasive cells were (14.35±7.67), (3.96±4.37) and (3.08±1.03)/field, respectively. The numbers of migratory and invasive cells were higher in RA than those in the other groups. The migration and invasion abilities of RA FLS from anti-CCP antibody-positive RA patients were significantly increased as compared with anti-CCP antibody-negative RA patients. Correlation analysis revealed that the migration and invasion abilities of RA FLS were correlated with the positive and high titer of anti-CCP antibody.CONCLUSION: The migration and invasion abilities of FLS from anti-CCP antibody-positive RA patients are increased. Anti-CCP antibody is possibly correlated with the increased migration and invasion abilities of RA FLS.     

Inhibitory effect of simvastatin on TNF-α-induced chemokines secretion in rheumatoid arthritis fibroblast like synoviocytes via inhibition of RhoA activation

AIM: To investigate the effect of simvastatin (SMV) on tumor necrosis factor α (TNF-α)-induced chemokine secretion in rheumatoid arthritis fibroblast-like synoviocytes (RA FLS).METHODS: RhoA activity was determined by pull-down assay. Chemokine secretion was measured by ELISA. MTT test was used to detect cell viability.RESULTS: Simvastatin attenuated TNF-α-induced interleukin-8(IL-8) and monocyte chemotactic protein-1(MCP-1) secretion as well as RhoA activation in RA FLS. The inhibitory effects of SMV were completely reversed by mevalonate (MEVA) and geranylgeranyl pyrophosphate (GGPP). Suppression of RhoA activation with a specific inhibitor depressed the secretion of IL-8 and MCP-1 in TNF-α-induced RA FLS.CONCLUSION: Simvastatin inhibits TNF-α-induced secretion of IL-8 and MCP-1 in RA FLS through inhibition of RhoA activation, indicating a novel strategy for anti-inflammatory effects of statins on treatment of RA.     

Changes of nuclear factor-κB and inducible nitric oxide synthase in hypoxic pulmonary hypertension

AIM: To observe the changes of nuclear factor-κB (NF-κB) activity and inducible nitric oxide synthase (iNOS) expression in hypoxic pulmonary hypertension (HPH). METHODS :The rat model of HPH was used. The NF-κB activity and iNOS expression in lung tissue were determined by immunohistochemistry (IHC), in situ hybridization (ISH), RT-PCR and Western blot. RESULTS: ISH showed that iNOS mRNA expression in intraacinar pulmonary arteriole (IAPA) in H28d group (hypoxic treatment for 28 days) was stronger than that in normal group, H5d group and H14d group. RT-PCR showed that the iNOS mRNA in H28 group was 2.1 times, 1.9 times and 1.8 times higher than that in normal group, H5d group and H14d group, respectively. The nucleic anti-NF-κB stain was observed in H28d group, which was significantly stronger, but the I-κB amount was 2.8 times, 2.7 times and 2.5 times lower than that in normal group, H5d group and H14d group, respectively. CONCLUSION: The activity of NF-κB was correlated with the hypoxic pulmonary vessel structural remodeling and iNOS expression.     

Expression of nuclear factor-κB in asthmatic guinea pigs and the effect of erigeron breviscapus on it

AIM:To explore the expression of nuclear factor-κB(NF-κB)in asthmatic guinea pigs,and the effect of erigeron breviscapus,a protein kinase C(PKC)inhibitor,on the expression of nuclear factor-κB(NF-κB).METHODS:48 guinea pigs were randomly divided into 6 groups(n=8).Airway resistance and eosinophilic inflammation of airway wall were examined,the expression of NF-κB in the lung tissue was detected by immunohistochemical staining.RESULTS:The expression of NF-κB was mainly found in airway epithelium,all the asthmatic animals showed significantly higher optical densities than that of the normal control group(P＜0.01),and the rats subjected therapeutic treatment for two weeks showed significantly lower NF-κB expression than those of the asthmatic groups(P＜0.01).Positive correlation exist between the airway resistance and the percentage of cells expressing NF-κB in epithelium,and between the amount of eosinophil in airway wall and the percentage of cells expressing NF-κB in epithelium(P＜0101).CONCLUSION:The increased expression of NF-κB in airway epithelium of the asthmatic guinea pigs suggested that NF-κB may be involved in asthma.And result that the increased expression of NF-κB was inhibited significantly by the treatment of the erigeron breviscapus suggested that PKC may play a significant role in the pathogenesis of asthma through NF-κB.     

Effects of diterpenoid C from ether extract of Radix Curcumae on nuclear factor-κB activity in LPS-induced human gastric adenocarcinoma SGC7901 cells

AIM: To observe the effects of diterpenoid C from ether extract of Radix Curcumae (RC) on the activity of nuclear factor-κB in human gastric adenocarcinoma SGC7901 cells stimulated with lipopolysaccharide (LPS). METHODS: SGC7901 cells were normally cultured, induced by LPS, or treated with LPS plus RC. The protein expression of IKKα, IKKβ, p65, phosphorylated p65 and phosphorylated IκBα was assayed by Western blotting. NF-κB DNA binding activity was determined by electrophoretic mobility shift assay. RESULTS: RC reduced the protein expression of IKKα, IKKβ, p65, phosphorylated p65 and phosphorylated IκBα induced by LPS. NF-κB DNA binding activity increased much greatly by LPS stimulation, while RC resisted the action of LPS. CONCLUSION: RC may attenuate the secretion of inflammatory cytokines by inhibiting the activation of NF-κB signaling pathway.     

Roles of nuclear factor-κB in the development of rat pancreatic fibrosis mediated by angiotensin II

AIM: To determine the effects of NF-κB on the development of rat pancreatic fibrosis mediated by angiotensin II. METHODS: Spraque-Dawley rats (200-300g) were randomly divided into normal group, control group and losartan-treatment group. Pancreatic fibrosis was induced by injection of 2% TNBS into biliopancreatic duct. Rats in losartan-treatment group and control group were respectively treated with losartan (10 mg·kg^-1·d^-1) by gavage and the same volume of saline vehicle. The expression, distribution, and activation of NF-κB were studied by Western blot, immunohistochemistry and TransAM^TM. Toluidine blue staining and transmission electron microscopy were also used to observe the number, distribution and degranulation of mast cells. In addition, RT-PCR was performed to detect the intrapancreatic ICAM-1 mRNA expression. RESULTS: The expression and activity of intrapancreatic NF-κB p65 protein were significantly increased on day 3 after operation, reaching peak on day 7 [(0.406±0.086)mg/g total protein].. Mast cell activation was observed and ICAM-1 mRNA levels on day 3 and 7 were up-regulated in control group. Losartan treatment inhibited NF-κB expression and activation, reduced mast cell infiltration and degranulation and decreased ICAM-1 mRNA expression compared with control rats. CONCLUSION: It might be associated with the expression and activation of NF-κB that angiotensin II mediates inflammation and fibrosis in the early stage of pancreatic fibrosis.     

Rosiglitazone inhibits osteoclastogenesis in rheumatoid arthritis by down-regulating RANKL expression and suppressing ERK phosphorylation

AIM: To investigate the effects of rosiglitazone on fibroblast-like synoviocyte (FLS)-induced osteoclastogenesis in rheumatoid arthritis (RA) and the related mechanism. METHODS: RA-FLS were cocultured with peripheral blood monocytes from healthy volunteers in the presence of macrophage colony-stimulating factor (M-CSF) and rosiglitazone. Osteoclasts were assayed by tartrate-resistant acid phosphatase (TRAP) staining. Resorption lacunae area was identified by toluidine blue staining and quantified by image analysis software. The mRNA expression of RANKL and OPG was evaluated by real-time PCR, and the protein levels of RANKL, OPG, p-ERK, p-p38 and p-JNK were measured by Western blot. RESULTS: Compared with control group (without rosiglitazone treatment), rosiglitazone at concentration of 15 μmol/L significantly decreased the number of osteoclasts (P<0.01) and resorption lacunae area (P<0.05). The expression of RANKL at mRNA and protein levels was significantly down-regulated by rosiglitazone at concentration of 15 μmol/L, while the mRNA and protein expression of OPG was up-regulated (P<0.01). Rosiglitazone (15 μmol/L) significantly decreased the protein level of p-ERK (P<0.05), but not the protein level of p-p38 or p-JNK (P>0.05). CONCLUSION: Rosiglitazone inhibits RA-FLS-induced osteoclast formation and its resorption activity by down-regulating RANKL expression and ERK phosphorylation, suggesting that rosiglitazone may inhibit RA osteoclastogenesis and bone resorption.     

Effect of sodium nitroprusside on activation of nuclear factor κB

AIM: To investigate the effect of sodium nitroprusside (SNP) on activation of nuclear factor κB. METHODS: The techniques of culture of human T lymphocytes, Western blot and RT-PCR were applied. The effects of NO donor sodium nitroprusside (SNP) at different concentrations on mRNA and protein expression of IκB_α in human T lymphocytes at 30 min or 120 min after stimulating with phytohaemagglutinin (PHA-P) were observed. RESULTS: SNP at middle or high concentrations reduced the degradation of κIB_αprotein 30 min after stimulating with PHA-P,and increased the re-expression of κIB_αmRNA 120 min after stimulating with PHA-P significantly.CONCLUSION: The mechanism of inhibitory effect of SNP at middle or high concentrations may be due to the decrease in degradation and the increase in re-synthesis of κIB_α.The regulatory mechanism of SNP at low concentration may not be through κIB_α.     

Genetic polymorphism of caspase-7 isoform β in patients with rheumatoid arthritis

AIM: To investigate the association between the rs2227309 polymorphism of cysteinyl aspartate-specific protease-7 (caspase-7) isoform β and the genetic susceptibility in rheumatoid arthritis (RA) patients in Taizhou of China. METHODS: Genotyping of rs2227309 of caspase-7 isoform β gene was performed in 204 RA patients and 203 matched healthy controls using TaqMan single nucleotide polymorphism (SNP) genotyping assays. RESULTS: The genotype frequencies of GG, AG and AA of caspase-7 polymorphism in the RA patients were 33.3%, 53.4% and 13.2%, respectively, and 33.0%, 44.3% and 22.7% in the healthy individuals,respectively. There was a significant difference in caspase-7 genotype frequencies between the RA patients and healthy controls (P<0.05). The frequency of GG+AG genotype in RA patients was higher than that in healthy controls with significant difference (P<0.05, OR=1.921, 95%CI: 1.140~3.236). The frequencies of the G allele were 60.0% and 55.2% in the RA patients and the healthy individuals,respectively. No significant difference was observed in allele frequency between the RA patients and healthy controls (P>0.05, OR=1.221, 95%CI: 0.924~1.613). CONCLUSION: The rs2227309 polymorphism of caspase-7 isoform β gene is associated with the susceptibility to rheumatoid arthritis. The high production of the non-functional variant of caspase-7 may reduce the apoptosis of rheumatoid synovial cells, indicating the mechanism of this association.     

Effects of TREM-2 silencing on migration and invasion abilities of rheumatoid arthritis fibroblast-like synoviocytes

AIM: To investigate the effects of triggering receptor expressed on myeloid cells-2 (TREM-2) silencing on migration and invasion abilities of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS). METHODS: Small interference RNA (siRNA) specifically targeting TREM-2 gene was transfected into RA-FLS. The interference efficiency of TREM-2 siRNA on the production of TREM-2 mRNA and protein was determined by RT-PCR and Western blot. The cell activity was assessed by CCK-8 assay. The migration and invasion abilities of RA-FLS were determined by Transwell assay. The releases of MMP-2 and MMP-9 in RA-FLS were analyzed by ELISA. The influence of TREM-2 on PI3K/AKT signal pathway was measured by Western blot. RESULTS: TREM-2 siRNA significantly decreased the mRNA and protein expression of TREM-2. No difference of cell activity between TREM-2 siRNA group and control group was observed. Transwell migration assay showed that RA-FLS through the Transwell membrane in TREM-2 siRNA group were more than the blank control group and the NC-siRNA group. In Transwell invasion assay, RA-FLS through the Transwell membrane in TREM-2 siRNA group were more than the blank control group and the NC-siRNA group. After transfected with TREM-2 siRNA, the MMP-2 secretion and phosphorylation of AKT increased significantly, while the MMP-9 secretion was not changed. CONCLUSION: TREM-2 may play an important role in the migration and invasion of RA-FLS through regulating the activation of PI3K/AKT signal pathway.     

Effects of burn sera on IκBα degradation and NF-κB activation in monocytes in vitro

AIM: To investigate the effects of burn sera on IκBα degradation, NF-κB activation in peripheral blood monocytes (PBMCs) in order to explore the role of burn sera on activation of monocytes. METHODS: PBMCs isolated from healthy volunteers were stimulated by sera from healthy volunteers and burn patients and by burn sera together with PDTC (pyrrolidine dithioncarbamate). Activation of monocytic NF-κB was tested by electrophoretic mobility shift assay (EMSA) and the degradation of monocytic IκBα was determined by Western blotting. RESULTS: When compared to that in control group, cytosolic IκBα degradation occurred within 30 min after PBMCs stimulated by burn sera, and peaked at 60 min. But IκBα gradually recovered in the cytoplasm after 2 h of stimulation. Meanwhile, activity of monocytic NF-κB was markedly increased, reached the peak at 30 min to 60 min after stimulation, and gradually decreased after 2 h of stimulation. PDTC (an antioxidants) effectively inhibited the monocytic IκBα degradation and activation of NF-κB induced by burn sera. CONCLUSION: Burn sera might induce the degradation of IκBα, then activate NF-κB, which ultimately lead to the secretion of cytokines from the monocytes.