Résumé
Anthrax is a highly lethal infectious disease caused by the spore-forming bacterium Bacillus anthracis. The major virulence factor of B. anthracis consists of protective antigen (PA), lethal factor (LF) and edema factor (EF). PA binds with LF to form lethal toxin (LT), and PA binds with EF to form edema toxin (ET). Antibiotics is hard to work in advanced anthrax infections, because injuries and deaths of the infected are mainly caused by lethal toxin (LT). Thus, the therapeutic neutralizing antibody is the most effective treatment of anthrax. Currently most of the anthrax toxin antibodies are monoclonal antibodies (MAbs) for PA and US FDA has approved ABTHRAX humanized PA monoclonal antibody for the treatment of inhalational anthrax. Once B. anthracis was artificially reconstructed or PA had mutations within recognized neutralization epitopes, anti-PA MAbs would no longer be effective. Therefore, anti-LF MAbs is an important supplement for anthrax treatment. Most of the anti-LF antibodies are murine or chimeric antibodies. By contrast, fully human MAbs can avoid the high immunogenicity of murine antibodies. First, we used LF to immunize the transgenic mice and used fluorescent cell sorting to get antigen-specific memory B cells from transgenic mice spleen lymphocytes. By single cell PCR method, we quickly found two strains of anti-LF MAbs with binding activity, 1D7 and 2B9. Transiently transfected Expi 293F cells to obtain MAbs protein after purification. Both 1D7 and 2B9 efficiently neutralized LT in vitro, and had good synergistic effect when mixed with anti-PA MAbs. In summary, combining the advantages of transgenic mice, fluorescent cell sorting and single-cell PCR methods, this study shows new ideas and methods for the rapid screening of fully human monoclonal antibodies.
Résumé
Objective To investigate the influence of ursolic acid on vascular endothelial growth factor ( VEGF) , cycloxygen-ase-2 (COX-2), and matrix metalloproteinases-2 (MMP-2) expressed in the mouse retinal ischemic model , and to explore the mecha-nisms of anti-angiogenesis.Methods Sixty 7-day clean-class C57BL/6J mice were divided randomly into 6 groups [ n =10 mice (20 eyes) per group]:blank control, model control (PBS), positive control (triamcinolone), and ursolic acid (UA) intervention (low-dose, medium-dose, and high-dose).Mice in the blank control group were raised in air , and mice in other groups in(75%±2%)O2 high-oxygen environment for 5 consecutive days .Mice in the model control group and breastfeeding mice were put back in air environ-ment (21%O2 ) on the 12th day after the new-born mice to induce the generation of retinal neovascularization .When models were suc-cessful, the drug treatments were applied immediately to the corresponding groups , with injection of 3μl of sterile PBS in model control group, 3 μl of 1.5, 3.00 and 6.0 μg UA in UA intervention group, and 3 μl of triamcinolone (1 ml∶40 mg) in positive control group, respectively.All mice were killed after overdose anesthesia on the 17th day.Their eyeballs were made into samples and retinal tissue pathological sections with H-E dying method.The positive expressions of VEGF , COX-2, and MMP-2 were detected with immu-nohistochemical method .The fresh retinal tissue homogenate was prepared to detect the protein expressions of VEGF , COX-2, and MMP-2 in retinal tissue with western blot method ,and mRNA expressions of VEGF , COX-2, and MMP-2 were detected with real-time fluorescent quantitative polymerase chain reaction ( RT-PCR) .Results According to protein and mRNA expressions of VEGF , COX-2,and MMP-2 in retinal tissue among six groups , protein expressions of VEGF , COX-2, and MMP-2 in model group were significantly higher than those in blank group ( P 0.05 ) .Each protein expression in the high UA intervention group was significantly lower than that in the low UA intervention group( P <0.05).Conclusions UA inhibited expressions of VEGF, COX-2, and MMP-2 in retinal ischemia model .UA also played an inhibitory role in the formation of neovascularization , and this role was positively correlated with UA dose .