ABSTRACT
With the sequence of the vasoactive intestinal peptiepeptide (VIP) from humans and according to the condon bias of Pichia pastoris, we designed PCR primers of VIP and obtained the sequence of VIP by SOE-PCR. Then VIP gene was cloned into Pichia pastoris secretory expression vector and the cell secretary system GS115-pPICZαA-vip was constructed. The recombinant strain was induced by methanol for 96 hours, and we collected the supernatant and identified the VIP by mass spectrometry. The molecular weight of VIP was consistent with theoretical molecular weight. The final result showed that the target peptide VIP was successfully expressed. The experimental investigations of agarose gel diffusion revealed that the recombinant expression modified VIP had relatively strong antibacterial activity to E. coli ATCC25922 and S. aureus ATCC25923. The minimal inhibitory concentration (MIC) of VIP to E. coli ATCC25922 and S. aureus ATCC25923 was 8 mmol/L and 16 mmol/L. Further cytotoxicity and hemolytic experiments indicated that recombinant VIP was non-toxic to normal cells NCM460 and IPEC-J2, had little hemolysis activity to SD rat erythrocytes. Meanwhile, by transmission electron microscopy, we found that VIP mainly inhibited bacteria by disrupting the cell membrane. These experiments established a useful system for further studies, application and mass production of antimicrobial peptide VIP.
ABSTRACT
The study was conducted to investigate the role of vitamin E in the high altitude hypoxia-induced damage to the intestinal barrier in rats. Sprague-Dawley rats were divided into control (Control), high altitude hypoxia (HH), and high altitude hypoxia+vitamin E (250 mg/kg BW*d) (HV) groups. After the third day, the HH and HV groups were placed in a hypobaric chamber at a stimulated elevation of 7000 m for 5 days. The rats in the HV group were given vitamin E by gavage daily for 8 days. The other rats were given equal volume saline. The results showed that high altitude hypoxia caused the enlargement of heart, liver, lung and kidney, and intestinal villi damage. Supplementation with vitamin E significantly alleviated hypoxia-caused damage to the main organs including intestine, increased the serum superoxide dismutase (SOD) (p< 0.05), diamino oxidase (DAO) (p< 0.01) levels, and decreased the serum levels of interleukin-2 (IL-2) (p< 0.01), interleukin-4 (IL-4) (p<0.001), interferon-gamma (IFN-gamma) (p<0.01) and malondialdehyde (MDA) (p<0.001), and decreased the serum erythropoietin (EPO) activity (p<0.05). Administration of vitamin E significantly increased the S-IgA (p<0.001) in ileum and significantly improved the expression levels of occludin and IkappaBalpha, and decreased the expression levels of hypoxia-inducible factor 1 alpha and 2 alpha (HIF-1alpha and HIF-2alpha), Toll-like receptors (TLR4), P-IkappaBalpha and nuclear factor-kappaB p65(NF-kappaB P65) in ileum compared to the HH group. This study suggested that vitamin E protectis from intestinal injury caused by high altitude hypoxia environment. These effects may be related to the HIF and TLR4/NF-kappaB signaling pathway.