Studies On The Silkworm-expressed Cholera Toxin B Subunit And Active Peptide From Shark Liver Fusion Protein Against Type2Diabetes

Diabetes mellitus，a common chronic metabolic disease, usually caused by the interaction ofboth genetic and environmental factors, is leading to a severe threat to human health. Since mostof the existing anti-type2diabetes drugs have bad side effects and the defect of secondaryfailure, it is extremely urgent to develop a long-term and low toxicity antidiabetic drugs. Withdwindling land resources, the biodiversity and unique features of high efficiency and lowtoxicity of marine biological resources are obtaining more and more concern. Early researchesshowed that, active peptide from shark liver (APSL) has the functions of hepatoprotection,hypoglycemia, immunomodulatory effect and repairing damaged islet. Because of the limiteddrug source and inconvenience of drug delivery, its application and promotion was extremelylimited. The problem is well solved by scale preparation of recombinant protein using thesilkworm bioreactor combined receptor-mediated oral drug delivery system.APSL is a hepatocyte stimulating cytokine which is isolated and purified from the liver ofChiloscyllium plagiosum, and has potential therapeutic effect in the treatment of diabetes. Ourresearch combines the protein oral prospect silkworm expression system with the most effectivemucosal carrier protein cholera toxin B subunit (CTB), and connects the CTB to APSL usingflexible tetrapeptide GPGP, and then makes it efficiently expressed in silkworm. It uses CTB astransporters of the intestinal mucosa, and auxiliary the medicinal protein APSL through theintestinal epithelial cells, enters the blood circulation, and finally reaches the tissues and cells todo execution.Associated high fat and sugar diet induced with low-dose (80mg/kg) of STZ intraperitonealinjection, type2diabetic ICR mice are created. By intragastric administration five weeks (i.g.100mg/kg·d) the anti-type2diabetes effect of CTB-APSL fusion protein is evaluated. Studieshave shown that: CTB-APSL fusion protein can effectively reduce fasting blood glucose level intype2diabetic mice, promote insulin secretion, and effectively improve insulin resistance;significantly improve lipid metabolism in type2diabetic mice, reducing TG, TC and LDL levels,increase HDL level; effectively improve inflammatory response of type2diabetic mice, reducethe level of inflammatory cytokine TNF-α and IL-6. Histopathology displays that, CTB-APSL fusion protein can significantly repair damaged pancreatic tissue of type2diabetic mice;significantly improve hepatic steatosis and hepatic cells cloudy swelling, reduce the content oflipid droplets in type2diabetic mice; effectively inhibit renal interstitial inflammatory cellsinvasion, improve renal tubular epithelial cell nucleus pyknosis phenomenon. In addition,CTB-APSL fusion protein also has the effect of preventing weight loss in type2diabetic mice.In conclusion, CTB-APSL fusion protein has a good effect of anti-type2diabetes, andeffectively improves its complications, and thus provides a experimental basis for thedevelopment of a new type anti-type2diabetic oral drugs.