Detection of the antigenic peptides in pHLA complexes by ultrafiltration-high performance liquid chromatography / 生物工程学报

Recombinant HLA-Ⅰ molecules/antigenic peptide complexes (pHLA complexes) are applied in the research of human T cell-specific immune responses. The preparation of pHLA complex is based on genetic engineering and protein in vitro dilution and folding-refolding technology. In an in vitro refolding system, recombinant HLA-Ⅰ molecules correctly fold and bind with antigenic peptides to form complexes. In this study, ultrafiltration-high performance liquid chromatography (ultrafiltration-HPLC) was used for quantitative determination of the antigenic peptides in recombinant pHLA complexes, especially for those in a small amount of prepared products. By adding the recombinant HLA-Ⅰ molecules and antigenic peptides into the refolding buffer, the heavy chain (HC) and light chain (β2m) of recombinant HLA-Ⅰ molecules were refolded and bond with the VYF antigenic peptide containing anchor residues to form a pHLA complex. The unbound free antigenic peptide VYF was removed by ultrafiltration to retain the complex. Finally, the pHLA complex was treated by acid to destroy its interaction, thus releasing the antigenic peptide. The results showed that the prepared recombinant pHLA complex was recognized by HLA-Ⅰ molecule specific antibody W6/32, which indicated that the recombinant HLA-Ⅰ class molecule had correct folding and was identified as pHLA complex. The antigen peptide VYF contained in the pHLA complex was also detected by ultrafiltration-HPLC, so it is feasible to apply ultrafiltration-HPLC for determination of pHLA complex. Compared with Western blotting, the concentration of antigenic peptides detected by ultrafiltration-HPLC was 0-9 μg/mL. The binding conditions can be optimized according to the amount of antigenic peptides bound in the complex in order to improve the folding efficiency of HLA-Ⅰ molecules and promote the binding of HLA-Ⅰ molecules to antigenic peptides. The production rate of pHLA complexes in the refolding system can also be calculated according to the content of antigenic peptides bound by pHLA complexes. Therefore, ultrafiltration-HPLC in this study can be used for the quality control of the preparation process of pHLA complexes, and may facilitate the research of T cell-specific immunity, artificial antigen-presenting cells, and development of specific tetramer probe applications.

Tripterygium glycosides suppress colitis via NOXs-ROS-NLRP3 inflamma-tory signaling pathways / 中国病理生理杂志

AIM: To observe the effect of Tripterygium glycosides on NOXs-ROS-NLRP3 inflammatory signa-ling pathways in the colon tissue in dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) mice, and to investi-gate the underlying mechanisms.METHODS: BALB/c mice were used and the mouse model of UC was established by DSS induction.The mice were randomly divided into 5 groups (model group, low-, medium-and high-dose Tripterygium glycosides groups, and normal group).The colon tissues were collected 21 d after Tripterygium glycosides gavage.The mRNA expression of NLRP3, ASC and caspase-1 in the colon tissues was detected by real-time PCR.The caspase-1 ex-pression in the colorectal mucosa was observed by immunohistochemical method.ELISA was used to detect the protein le- vels of IL-1α, TNF-αand IL-13.The production of reactive oxygen species (ROS) was measured by chemiluminescence technique, and the consumption rate of NADPH, which was inhibited by DPI, was analyzed to determine the activity of NADPH oxidases (NOXs).The neutrophils were isolated, and the ROS production, NOXs activity, and the mRNA ex-pression of NLRP3, ASC and caspase-1 were also detected.RESULTS: The colon tissues were abnormal with different de-grees in Tripterygium glycosides groups, and histopathological scores were lower than that in model group.In Tripterygium glycosides groups, in addition to the mRNA expression levels of caspase-1 in the colon tissues between normal group and high-dose group, ROS production, NOXs activity and the mRNA expression levels of NLRP3, ASC and caspase-1 in the colon tissues and colon-isolated neutrophils were lower than those in model group (P <0.05), and higher than those in normal group (P <0.05).The results of pairwise comparison for the efficacy of Tripterygium glycosides administration showed that the above indexes were statistically significant except the mRNA expression levels of caspase-1 between middle-dose group and high-dose group.Tripterygium glycosides administration significantly decreased the expression levels of proinflammatory cytokines IL-1αand TNF-αin the homogenates of colon tissues in the model mice (P <0.05).No differ-ence of IL-13 expression among the groups was observed.CONCLUSION: Tripterygium glycosides inhibits NOXs-ROS-NLRP3 inflammatory signaling pathways to reduce the expression of IL-1α, TNF-αand other proinflammatory cytokines, and attenuates DSS-induced ulcerative colitis in mice, by which the neutrophils might be involved in the process.

Tripterygium Glycosides Protects Mice against Colonic Inflammation by Inhibiting TLR4/NF-κB Signaling Pathway / 胃肠病学

Background:Tripterygium glycosides(TG)is effective for treatment of ulcerative colitis(UC)in clinical practice, however,the underlying mechanism has not been clarified yet. Aims:To investigate the therapeutic effect of TG on dextran sulfate sodium(DSS)-induced experimental colitis in mice and its possible mechanisms. Methods:Sixty healthy male BALB/ c mice were randomly divided into six groups:model control group,low,medium and high-dose TG group,blank control group and normal control group. Mice in the first four groups drank 5% DSS freely for 7 days to induce experimental colitis;simultaneously,distilled water,9. 01,27. 03 or 81. 09 mg/(kg·d)TG were given intragastrically for 21 days in these four groups,respectively. Histopathological changes of colonic mucosal tissues were observed;expressions of TLR4 mRNA and protein were determined by RT-PCR and Western blotting;expression of NF-κB p65 was detected by immunohistochemistry;concentrations of IL-1α,TNF-α and IL-13 were measured by ELISA. Results:Tissue damage and inflammation in varying degrees were observed in colonic mucosal tissues in TG groups with different dosage,but all were less severe than those in model control group. Expressions of TLR4 mRNA,TLR4 protein,and NF-κB p65 in colonic mucosal tissues,as well as concentrations of IL-1α and TNF-α in supernatant of colonic homogenate were significantly lower in TG groups than those in model control group(P 0. 05). Conclusions:TG exerts a protective effect on DSS-induced experimental colitis in mice. The underlying mechanism of its anti-inflammatory effect might be related with the inhibition of TLR4 / NF-κB signaling pathway activation and subsequently suppressing downstream proinflammatory cytokines expression and secretion.

Expression of myocyte enhancer factor 2A in processing of hepatic stellate cell activation / 中国病理生理杂志

AIM: To observe the changes in expression and activity of the transcription factor myocyte enhancer factor 2A (MEF2A) during hepatic stellate cells (HSC) activation, and to study the roles of MEF2A in the process of HSC activation. METHODS: Cultured HSC was isolated from male sprague-dawley rat liver on plastic dishes and were used as model of activation. The freshly isolated (0 day) and cultured HSC at time points of 1st, 2nd, 3rd, 4th, 5th, 6th, 7th and 8th day were collected. Expression of MEF2A mRNA was detected by real-time quantitative PCR. MEF2A and α-smooth muscle actin (α-SMA, a marker for activated HSC) were tested by Western blotting. Meanwhile, the MEF2A DNA binding activity was determined by electrophoretic mobility shift assays (EMSA). RESULTS: The expression of MEF2A mRNA was small amounts in the freshly isolated HSC and increased gradually after culture on plastic dishes. Western blotting revealed that the freshly isolated HSC expressed very low levels of MEF2A and α-SMA. The proteins of MEF2A and α-SMA were increased gradually in the process of HSC activation. Increased MEF2A protein was correlated with α-SMA. EMSA revealed that MEF2A DNA binding activity was increased gradually during HSC activation. CONCLUSION: In the process of HSC activation, expression and activity of MEF2A are increased gradually, indicating a role in HSC activation.