A 90-day subchronic toxicology screen of genetically modified rice Lac-3 and its effects on the gut microbiota in Sprague-Dawley rats.

A 90-day subchronic toxicology screen of genetically modified (GM) rice Lac-3 expressing human lactoferrin (hLF) and its effects on the gut microbiota were studied in comparison to non-GM rice fed to Sprague-Dawley (SD) rats. Three different dietary concentrations (17.5%, 35% and 70%, w/w) of the GM rice or its corresponding non-GM rice were used. Additionally, the phylotypes of gut microbiota in the control group, the 70% GM rice diet group and the 70% non-GM rice diet group on day 90 were determined by 16S rRNA sequencing. The results of the 90-day subchronic feeding study demonstrated that the GM rice Lac-3 containing human lactoferrin (LF) gene is considered as safe as the non-GM rice. The results of bacterial 16S rRNA sequencing showed that the structure of gut microbiota in the 70% GM group slightly changed when compared with the control group and the 70% non-GM group. There were no significant differences in the microbiota diversity among the three groups.

Expression of α-1,6-fucosyltransferase (FUT8) in rice grain and immunogenicity evaluation of plant-specific glycans.

Rice seed is a cost-effective bioreactor for the large-scale production of pharmaceuticals. However, convincing evidence of the immunogenicity of plant-specific glycans is still limited although plant-specific glycans are considered potential allergic antigens. In the present study, we found that the α-1,3-fucose content of the glycoprotein produced from rice seed was much lower than that in leaf, and conversely, a higher ß-1,2-xylose content was detected in seed than that in leaf. We detected the α-1,6-fucose content in the glutelin and recombinant human α1-antitrypsin (OsrAAT). The further results in a line containing AAT and FUT8 genes indicated that the α-1,6-fucose content of modified glycosylated recombinant α1-antitrypsin (mgOsrAAT) was 38.4%, while glutelin was only 6.8%. Interestingly, the α-1,3-fucose content of mgOsrAAT was significantly reduced by 59.8% compared with that of OsrAAT. Furthermore, we assessed the immunogenicity of OsrAAT, mgOsrAAT and human α1-antitrypsin (hAAT) using an animal system. The PCA results indicated no significant differences in the IgG, IgM and IgE titers among OsrAAT, mgOsrAAT and hAAT. Further studies revealed that those antibodies were mainly from α-1,3-fucose, but not from ß-1,2-xylose, indicating that α-1,3-fucose was the major immunogenic resource. Our results demonstrated that α-1,3-fucose contents in seed proteins was much less than that of leaf, and could not be a plant-specific glycan because it also exists in human proteins.

Transgenic rice endosperm as a bioreactor for molecular pharming.

Plants provide a promising expression platform for producing recombinant proteins with several advantages in terms of high expression level, lower production cost, scalability, and safety and environment-friendly. Molecular pharming has been recognized as an emerging industry with strategic importance that could play an important role in economic development and healthcare in China. Here, this review represents the significant advances using transgenic rice endosperm as bioreactor to produce various therapeutic recombinant proteins in transgenic rice endosperm and large-scale production of OsrHSA, and discusses the challenges to develop molecular pharming as an emerging industry with strategic importance in China.

Expression and characterization of recombinant human alpha-antitrypsin in transgenic rice seed.

Human alpha-antitrypsin (AAT) is the most abundant circulating protease inhibitor in the human plasma. It is produced in the liver and exerts a primary physiological role as inhibitor for the neutrophil elastase in the lung. Individuals with one or several gene mutations in AAT causing reduction of the protein are related to lung, liver and pancreatic emphysema diseases and are treated lifelong with infusions of human plasma-derived AAT. Due to shortage of plasma and low expression levels of recombinant AAT in conventional gene expression systems, we explored the possibility to produce recombinant AAT in rice grains (Oryza sativa AAT, OsrAAT). An expression level of up to 2.24g/kg brown rice and a final recovery of purified 0.366g/kg OsrAAT has been obtained. OsrAAT has the same secondary structure and protease inhibitory activity as plasma-derived AAT (pAAT), but was highly heterogeneous with regard to glycan modifications. Thus 32.8% of OsrAAT were glycosylated and 67.2% were free of glycans as determined by MALDI-MS. Of the N-glycan structures 64.8% were vacuole-specific paucimannosidic molecules. Immune electron microscopy located OsrAAT in the endoplasmic reticulum lumen as precursor-accumulating (PAC)-like vesicle structures. The pharmacokinetic study indicated that the half-life of OsrAAT was prolonged, while the clearance rate was faster than that of pAAT in vivo. The results demonstrate that rice endosperm is a promising system to express this biopharmaceutical protein.

[Identification of the active material of anti-hepatic fibrosis from Amydae Carapax].

OBJECTIVE: To identify the active material of anti-hepatic fibrosis from Amydae Carapax. METHODS: Membrane separation technology was adopted to screen active fraction in Amydae Carapax, and the active components were isolated from the active fraction using gel chromatography and high performance liquid chromatography. The purified active components in Amydae Carapax were further analyzed using 4700 series time-of-flight mass spectrometer. RESULTS: Proteins and peptides of Amydae Carapax with molecular weight less than 6000 were proved to have biological activity. 8 components (Bj1-Bj8) were isolated from the active fraction. Bj4, Bj6 and Bj7 were screened as active components. Bj7 was further purified, resulting in 7 components (Bj701-Bj707). Bj704 and Bj707 showed significant biological activity. Mass spectrometry showed three molecular ion peaks with highest abundance, i.e. m/e 526, 542 and 572, i.e. m/e 526, 542 and 572, in Bj707 -A The amino acid sequences of above three peptide compounds were NDDY (Asn-Asp-Asp-Tyr), NPNPT (Asn-Pro-Asn-Pro-Thr), and HGRFG (His-Gly-Arg-Phe-Gly), respectively. And M572 was the most abandunt components. CONCLUSION: Three active peptide compounds of anti-hepatic fibrosis of Amydae Carapax were identified.