Prokaryotic expression of the extracellular domain of porcine programmed death 1 (PD-1) and its ligand PD-L1 and identification of the binding with peripheral blood mononuclear cells in vitro.

Programmed cell death protein 1 (PD-1), a costimulatory molecule of the CD28 family, has 2 ligands, PD-L1 and PD-L2. Our previous studies showed that the expression of PD-1 and PD-L1 is up-regulated during viral infection in pigs. Extensive studies have shown that blockade of the PD-1/PD-L1 pathways by anti-PD-L1 antibody or soluble PD-1 restores exhausted T-cells in humans and mice. In the present study the extracellular domains of PD-1 and PD-L1 were used to evaluate the binding of PD-1 and PD-L1 with peripheral blood mononuclear cells (PBMCs). We amplified the cDNA encoding the extracellular domains of PD-1 and PD-L1 to construct recombinant expression plasmids and obtain soluble recombinant proteins, which were then labeled with fluorescein isothiocyanate (FITC). The His-ExPD-1 and His-ExPD-L1 recombinant proteins were expressed in the form of inclusion bodies with a relative molecular weight of 33.0 and 45.0 kDa, respectively. We then prepared polyclonal antibodies against the proteins with a multi-antiserum titer of 1:102 400. Binding of the proteins with PBMCs was evaluated by flow cytometry. The fluorescence signals of His-ExPD-1-FITC and His-ExPD-L1-FITC were greater than those for the FITC control. These results suggest that the soluble recombinant proteins may be used to prepare monoclonal antibodies to block the PD-1/PD-L1 pathway.

La protéine de la mort cellulaire programmée (PD-1), une molécule co-stimulatrice de la famille de CD28, a deux ligands, PD-L1 et PD-L2. Nos études antérieures ont montré que l'expression de PD-1 et PD-L1 est régulée à la hausse lors d'une infection virale chez des porcs. Des études exhaustives ont montré chez l'humain et la souris qu'un blocage de la voie PD-1/PD-L1 par des anticorps anti PD-L1 ou du PD-1 soluble permet la régénération des cellules T épuisées. Dans la présente étude les domaines extracellulaires de PD-1 et PD-L1 ont été utilisés afin d'évaluer l'attachement de PD-1 et PD-L1 avec des cellules mononucléaires du sang périphérique (CMSP). Nous avons amplifié l'ADNc codant pour les domaines extracellulaires de PD-1 et PD-L1 pour construire des plasmides d'expression recombinants et obtenir des protéines recombinants solubles, qui ont par la suite été marquées avec de l'isothiocyanate de fluorescéine (ITCF). Les protéines recombinantes His-ExPD-1 et His-ExPD-L1 étaient exprimées sous la forme de corps d'inclusion avec un poids moléculaire relatif de 33,0 et 45,0 kDa, respectivement. Nous avons par la suite préparé des anticorps polyclonaux contre ces protéines avec un antisérum titrant 1:102 400. L'attachement des protéines aux CMSP a été évalué par cytométrie en flux. Les signaux de fluorescence de His-ExPD-1-ITCF et His-ExPD-L1-ITCF étaient supérieurs à ceux pour le témoin ITCF. Ces résultats suggèrent que les protéines recombinantes solubles pourraient être utilisées afin de préparer des anticorps monoclonaux pour bloquer la voie PD-1/PD-L1.(Traduit par Docteur Serge Messier).

Homogeneous electrochemical detection of ochratoxin A in foodstuff using aptamer-graphene oxide nanosheets and DNase I-based target recycling reaction.

A simple and feasible homogeneous electrochemical sensing protocol was developed for the detection of ochratoxin A (OTA) in foodstuff on the immobilization-free aptamer-graphene oxide nanosheets coupling with DNase I-based cycling signal amplification. Thionine-labeled OTA aptamers were attached to the surface of nanosheets because of the strong noncovalent binding of graphene oxide nanosheets with nucleobases and aromatic compounds. The electronic signal was acquired via negatively charged screen-printed carbon electrode (SPCE) toward free thionine molecules. Initially, the formed thionine-aptamer/graphene nanocomposites were suspended in the detection solution and far away from the electrode, thereby resulting in a weak electronic signal. Upon addition of target OTA, the analyte reacted with the aptamer and caused the dissociation of thionine-aptamer from the graphene oxide nanosheets. The newly formed thionine-aptamer/OTA could be readily cleaved by DNase I and released target OTA, which could retrigger thionine-aptamer/graphene nanocomposites with target recycling to generate numerous free thionine molecules. Free thionine molecules were captured by negatively charged SPCE, each of which could produce an electrochemical signal within the applied potentials. Under optimal conditions, graphene-based aptasensing platform could exhibit good electrochemical responses for the detection of OTA at a concentration as low as 5.6pg/mL. The reproducibility, precision and selectivity of the system were acceptable. Importantly, the method accuracy was comparable with commercialized OTA ELISA kit when using for quantitative monitoring of contaminated wheat samples.

[The synergistic effect of FGF-21 and insulin on regulating glucose metabolism and its mechanism].

Previous studies proposed that the synergistic effect of fibroblast growth factor-21 (FGF-21) and insulin may be due to the improvement of insulin sensitivity by FGF-21. However, there is no experimental evidence to support this. This study was designed to elucidate the mechanism of synergistic effect of FGF-21 and insulin in the regulation of glucose metabolism. The synergistic effect of FGF-21 and insulin on regulating glucose metabolism was demonstrated by investigating the glucose absorption rate by insulin resistance HepG2 cell model and the blood glucose chances in type 2 diabetic db/db mice after treatments with different concentrations of FGF-21 or/and insulin; The synergistic metabolism was revealed through detecting GLUT1 and GLUT4 transcription levels in the liver by real-time PCR method. The experimental results showed that FGF-21 and insulin have a synergistic effect on the regulation of glucose metabolism. The results of real-time PCR showed that the effective dose of FGF-21 could up-regulate the transcription level of GLUT1 in a dose-dependent manner, but had no effect on the transcription level of GLUT4. Insulin (4 u) alone could up-regulate the transcription level of GLUT4, yet had no effect on that of GLUT1. Ineffective dose 0.1 mg kg(-1) FGF-21 alone could not change the transcription level of GLUT1 or GLUT4. However, when the ineffective dose 0.1 mg x kg(-1) FGF-21 was used in combination with insulin (4 u) significantly increased the transcription levels of both GLUT1 and GLUT4, the transcription level of GLUT1 was similar to that treated with 5 time concentration of FGF-21 alone; the transcription level of GLUT4 is higher than that treated with insulin (4 u) alone. In summary, in the presence of FGF-21, insulin increases the sensitivity of FGF-21 through enhancing GLUT1 transcription. Vice versa, FGF-21 increases the sensitivity of insulin by stimulating GLUT4 transcription in the presence of insulin. FGF-21 and insulin exert a synergistic effect on glucose metabolism through mutual sensitization.

Up-regulated expression of PD-1 and its ligands during acute Classical Swine Fever virus infection in swine.

In order to investigate the relationship between the PD-1 pathway and impairment of immune responses with the CSFV infection, the mRNA expression of PD-1 and its ligands were evaluated by quantitative polymerase chain reaction (qPCR) during artificial CSFV infection. Simultaneously, expression of IL-2 and IL-10 mRNA were detected. The T cell proliferation and CSFV load in plasma were also measured. Results showed that the expression of PD-1 and its ligands mRNA were significantly increased (p < 0.01) in PBMC from 3 to 7 days post infection (dpi). Meanwhile the level of IL-10 was up-regulated (p < 0.01). The IL-2 mRNA was not obviously changed but it is significantly increased from 14 dpi. The T cell proliferation was notably decreased at 7 dpi. The CSFV load was also increased in plasma. Overall, our results suggest that the expression of PD-1 and its ligands were up-regulated and probably correlated with immune inhibition during acute CSFV infection.

[The long lasting effect of the murine fibroblast growth factor-21 on blood glucose control of diabetic animals].

Insulin is the most common medicine used for diabetic patients, unfortunately, its effective time is short, even the long-acting insulin cannot obtain a satisfactory effect. Fibroblast growth factor (FGF)-21 is a recently discovered glucose mediator and expected to be a potential anti-diabetic drug that does not rely on insulin. In this study, db/db mice were used as the type 2 diabetic model to examine whether mFGF-21 has the long-term blood lowering effect on the animal model. The results showed that mFGF-21 could stably maintain the blood glucose at normal level for a long-term in a dose-dependent manner. Administration of mFGF-21 once a day with three doses (0.125, 0.25 and 0.5 mg x kg(-1)) could maintain blood glucose of the model animals at normal level for at least 24 h. Administration of mFGF-21 every two days with the same doses could maintain blood glucose of the model animals at normal level for at least 48 h, although it took longer time for blood glucose to reach to normal level depending on doses used (twenty injections for 0.125 mg x kg(-1) and 0.25 mg x kg(-1) doses, ten injections for 0.5 mg x kg(-1) dose). Surprisingly, the blood glucose of the treated model animals still maintained at normal level for 24 h after the experiment terminated. Glycosylated hemoglobin level of the animals treated with mFGF-21, which represented long-term glucose status, decreased significantly compared to the control group and the insulin group. The results suggest that FGF-21 has potential to become a long-acting and potent anti-diabetic drug.

[Cloning, expression and glucose regulation activity of human FGF-21].

Fibroblast growth factor (FGF)-21 is a recently discovered glucose regulator and has potential to become therapeutics for treatment of type 2 diabetes. The aim of this study was to clone and express human FGF-21 gene and characterize its bioactivity for glucose regulation. The hFGF-21 cDNA was cloned from human liver by RT-PCR and subcloned into the pSUMO vector after sequencing confirmation. The recombinant plasmid was transformed into Escherichia coli Rosetta strain. The FGF-21 protein expression was induced by IPTG and purified by Ni-NTA agarose. The FGF-21 product was verified by Western blotting analysis with specific antibody. The bioactivity of the purified protein was examined by glucose uptake assay in 3T3-L1 adipocytes. The cloned hFGF-21 gene consisted of 546 bp, which was in agreement with the published data in GenBank. SDS-PAGE analysis showed that hFGF-21 expressed in the E. coli system was 19.4 kDa in size. The glucose uptake assay in 3T3-L1 adipocytes indicated that the purified hFGF-21 could stimulate glucose uptake in a dose-dependent manner, and glucose transporters (GLUT1) is the functional unit.