Helicobacter pylori tumor necrosis factor-α inducing protein promotes cytokine expression via nuclear factor-κB

AIM:To study the effects of Helicobacter pylori(H. pylori)tumor necrosis factor-α(TNF)inducing protein (Tip-α)on cytokine expression and its mechanism. METHODS:We cloned Tip-αfrom the H.pylori strain 26695,transformed Escherichia coli with an expression plasmid,and then confirmed the expression product by Western blotting.Using different concentrations of Tip-αthat affected SGC7901 and GES-1 cells at different times,we assessed cytokine levels using enzyme-linked immunosorbent assay.We blocked SGC7901 cells with pyrrolidine dithiocarbamate(PDTC),a specific inhibitor of nuclear factorκB(NF-κB).We then detected interleukin(IL)-1βand TNF-αlevels in SGC7901 cells. RESULTS:Western blot analysis using an anti-Tip-α antibody revealed a 23-kDa protein,which indicated that recombinant Tip-αprotein was recombined successfully.The levels of IL-1β,IL-8 and TNF-αwere sig-nificantly higher following Tip-αinterference,whether GES-1 cells or SGC-7901 cells were used(P<0.05).However,the levels of cytokines(including IL-1β,IL-8 and TNF-α)secreted by SGC-7901 cells were greater than those secreted by GES-1 cells following treatment with Tip-αat the same concentration and for the same duration(P<0.05).After blocking NF-κB with PDTC, the cells(GES-1 cells and SGC-7901 cells)underwent interference with Tip-α.We found that IL-1βand TNF-αlevels were significantly decreased compared to cells that only underwent Tip-αinterference(P<0.05). CONCLUSION:Tip-αplays an important role in cyto-kine expression through NF-κB.

肿瘤坏死因子-α通过内皮型一氧化氮合酶和小凹蛋白-1介导内皮细胞功能失调的研究

血管内皮细胞功能失调是致动脉粥样硬化形成的重要机制之一。其中,内皮型一氧化氮合酶和小凹蛋白-1是调节脂质物质摄取和炎症细胞跨内皮迁移的重要蛋白。肿瘤坏死因子-α为多效性促炎症反应细胞因子,可通过核因子-κB信号通路下调内皮型一氧化氮合酶表达,上调小凹蛋白-1表达,诱导内皮细胞胞吞转运作用失衡和炎症细胞跨内皮迁移,促使局部血管斑块形成。现就肿瘤坏死因子-α通过核因子-κB信号通路诱导血管内皮功能失调的机制做一简要综述。

Adaptive and regulatory mechanisms in aged rats with postoperative cognitive dysfunction

Inflammation may play a role in postoperative cognitive dysfunction. 5＇ Adenosine monophos- phate-activated protein kinase, nuclear factor-kappa B, interleukin-1β, and tumor necrosis factor-a are involved in inflammation. Therefore, these inflammatory mediators may be involved in postoperative cognitive dysfunction. Western immunoblot analysis revealed 5＇ adenosine mo- nophosphate-activated protein kinase and nuclear factor-kappa B in the hippocampus of aged rats were increased 1-7 days after splenectomy. Moreover, interleukin-1β and tumor necrosis fac- tor-α were upregulated and gradually decreased. Therefore, these inflammatory mediators may participate in the splenectomy model of postoperative cognitive dysfunction in aged rats.

Protective Effect and Mechanism of Sodium Tanshinone ⅡA Sulfonate on Microcirculatory Disturbance of Small Intestine in Rats with Sepsis

To explore the protective effect of sodium tanshinone ⅡA sulfonate（STS） on microcirculatory disturbance of small intestine in rats with sepsis,and the possible mechanism,a rat model of sepsis was induced by cecal ligation and puncture（CLP）.Rats were randomly divided into 3 groups：sham operated group（S）,sepsis group（CLP） and STS treatment group（STS）.STS（1 mg/kg） was slowly injected through the right external jugular vein after CLP.The histopathologic changes in the intestinal tissue and changes of mesenteric microcirculation were observed.The levels of tumor necrosis factor-α（TNF-α） in the intestinal tissue were determined by using enzyme-linked immunoabsorbent assay（ELISA）.The expression of intercellular adhesion molecule-1（ICAM-1） in the intestinal tissue was detected by using immunohistochemisty and Western blot,that of nuclear factor κB（NF-κB） and tissue factor（TF） by using Western blot,and the levels of NF-κB mRNA expression by using RT-PCR respectively.The microcirculatory disturbance of the intestine was aggravated after CLP.The injury of the intestinal tissues was obviously aggravated in CLP group as compared with S group.The expression levels of NF-κB p65,ICAM-1,TF and TNF-α were upregulaed after CLP（P0.01）.STS post-treatment could ameliorate the microcirculatory disturbance,attenuate the injury of the intestinal tissues induced by CLP,and decrease the levels of NF-κB,ICAM-1,TF and TNF-α（P0.01）.It is suggested that STS can ameliorate the microcirculatory disturbance of the small intestine in rats with sepsis,and the mechanism may be associated with the inhibition of inflammatory responses and amelioration of coagulation abnormality.

Molecular mechanisms of triggering,amplifying and targeting RANK signaling in osteoclasts

Osteoclast differentiation depends on receptor activator of nuclear factor-κB(RANK) signaling,which can be divided into triggering,amplifying and targeting phases based on how active the master regulator nuclear factor of activated T-cells cytoplasmic 1(NFATc1) is. The triggering phase is characterized by immediateearly RANK signaling induced by RANK ligand(RANKL) stimulation mediated by three adaptor proteins,tumor necrosis factor receptor-associated factor 6,Grb-2-associated binder-2 and phospholipase C(PLC)γ2,leading to activation of IκB kinase,mitogen-activated protein kinases and the transcription factors nuclear factor(NF)-κB and activator protein-1(AP-1). Mice lacking NF-κB p50/p52 or the AP-1 subunit c-Fos(encoded by Fos) exhibit severe osteopetrosis due to a differentiation block in the osteoclast lineage. The amplification phase occurs about 24 h later in a RANKLinduced osteoclastogenic culture when Ca2+ oscillation starts and the transcription factor NFATc1 is abundantly produced. In addition to Ca2+ oscillation-dependent nuclear translocation and transcriptional auto-induction of NFATc1,a Ca2+ oscillation-independent,osteoblastdependent mechanism stabilizes NFATc1 protein in dif-ferentiating osteoclasts. Osteoclast precursors lacking PLCγ2,inositol-1,4,5-trisphosphate receptors,regulator of G-protein signaling 10,or NFATc1 show an impaired transition from the triggering to amplifying phases. The final targeting phase is mediated by activation of numerous NFATc1 target genes responsible for cell-cell fusion and regulation of bone-resorptive function. This review focuses on molecular mechanisms for each of the three phases of RANK signaling during osteoclast differentiation.

(5R)-5-hydroxytriptolide inhibits the inflammatory cascade reaction in astrocytes

Many studies have shown that(5R)-5-hydroxytriptolide is the optimal modified analogue of triptolide, possessing comparable immunosuppressive activity but much lower cytotoxicity than triptolide. Whether(5R)-5-hydroxytriptolide has preventive effects on neuroinflammation is unclear. This study was designed to pretreat primary astrocytes from the brains of neonatal Sprague-Dawley rats with 20, 100 and 500 nM(5R)-5-hydroxytriptolide for 1 hour before establishing an in vitro neuroinflammation model with 1.0 μg/mL lipopolysaccharide for 24 hours. The generation of nitric oxide was detected by Griess reagents. Astrocyte marker glial fibrillary acidic protein was measured by immunohistochemical staining. The levels of tumor necrosis factor-α and interleukin-1β in the culture supernatant were assayed by enzyme linked immunosorbent assay. Nuclear factor-κB/p65 expression was examined by immunofluorescence staining. The phosphorylation of inhibitor of nuclear factor IκB-α and the location of nuclear factor-κB/P65 were determined using western blot assay. Our data revealed that(5R)-5-hydroxytriptolide inhibited the generation of nitric oxide, tumor necrosis factor-α and interleukin-1β from primary astrocytes activated by lipopolysaccharide, decreased the positive reaction intensity of glial fibrillary acidic protein, reduced the expression of tumor necrosis factor alpha and interleukin-1β in culture supernatant, inhibited the phosphorylation of IκB-α and the translocation of nuclear factor-κB/P65 to the nucleus. These results have confirmed that(5R)-5-hydroxytriptolide inhibits lipopolysaccharide-induced glial inflammatory response and provides cytological experimental data for(5R)-5-hydroxytriptolide in the treatment of neurodegenerative diseases.

Protective Effect of Diallyl Trisulfide on Liver in Rats with Sepsis and the Mechanism

The protective effects of diallyl trisulfide on liver were examined in rats with sepsis. Sepsis was reproduced in rats by cecum ligation and puncture (CLP). Fifty-six male Wistar rats were randomly divided into sham-operated group (group S, n=8), sepsis model group (group C, n=24), diallyl trisulfide (DATS)-treated group (group D, n=24). Animals in groups C and D were further divided into three subgroups according to different observation time points, with 8 rats in each sub-group.Rats in group D and C were intravenously injected with normal saline or DATS respectively at a dose of 20 mg/kg after the establishment of sepsis model. Eight rats in groups C and D were sacrificed at 3, 6 and 24 h post-CLP and their livers were harvested for detection of interleukin (IL)-1 receptor associated kinase-4 (IRAK-4), nuclear factor-κB (NF-κB), c-fos, c-jun, malondialdehydethhe (MDA) and superoxide dismutase (SOD), tumor necrosis factor alpha (TNF-α) and for pathological examination. The results showed that the levels of serum IRAK-4, NF-κB and TNF-α in hepatic tissues were higher in group C than group S (control group) (P<0.05). After DATS treatment, the levels of IRAK-4 and NF-κB in the hepatic tissues and serum TNF-α in group D were lower than those in group C (P<0.05). The levels of c-fos and c-jun and MDA in the hepatic tissues were higher in group C than in group S (P<0.05). After DATS treatment, the levels of c-fos and c-jun and MDA in the hepatic tissues were significantly lower in group D than in group C (P<0.05). When compared with group S group, concentration of SOD in the hepatic tissues in group C was significantly lower (P<0.05). After DATS treatment, the concentration of SOD in the hepatic tissues was higher in group D than in group C (P<0.05). These findings suggested that treatment with DATS could ameliorate sepsis-induced liver injury in rats. The protective effect might be related to its ability to inhibit the signal pathway of IRAK-4 and NF-κB, thereby decreasing the production of oxygen free radicals and down-regulating the expression of c-fos and c-jun.

Splenectomy Attenuates Severe Thermal Trauma-induced Intestinal Barrier Breakdown in Rats

Summary： The severe local thermal trauma activates a number of systemic inflammatory mediators, such as TNF-α, NF-κB, resulting in a disruption of gut barrier. The gastrointestinal tight junction （T J） is highly regulated by membrane-associated proteins including zonula occludens protein-1 （ZO-1） and oc- cludin, which can be modulated by inflammatory cytokines. As splenectomy has been shown to reduce secretion of cytokines, we hypothesized that （1） severe scald injury up-regulates TNF-α and NF-κB, meanwhile down-regulates expression of ZO-1 and occludin, leading to the increased intestinal perme- ability, and （2） splenectomy can prevent the burn-induced decrease in ZO-1 and occludin expression, resulting in improved intestinal barrier. Wistar rats undergoing a 30% total body surface area （TBSA） thermal trauma were randomized to receive an accessorial splenectomy meanwhile or not. Intestinal in- jury was assessed by histological morphological analysis, and serum endotoxin levels, TNF-α, NF-κB, ZO-1 and occludin levels were detected by Western blotting in the terminal ileum mucosal tissue. 30% TBSA bum caused a significant increase in serum endotoxin levels, but NF-κB, and TNF-α, and the av- erage intestinal villus height and mucosal thickness were decreased significantly. Burn injury could also markedly decrease the levels of ZO-1 and occludin in terminal ileum mucosal tissue （all P〈0.01）. Sple- nectomy at 7th day after burn significantly reversed the bum-induced breakdown of ZO-1 and occludin （all P〈0.01）. The results of this study suggest that severe thermal injury damages the intestinal mucosal barrier. Splenectomy may provide a therapeutic benefit in restoring bum-induced intestinal barrier by decreasing the release of inflammatory cytokines and recovering TJ proteins.