Alternative Immunomodulatory Strategies for Xenotransplantation: CD80/CD86-CTLA4 Pathway-Modified Immature Dendritic Cells Promote Xenograft Survival

Background

Xenotransplantation is a promising approach to circumventing the current organ shortage. However, T-cell-dependent anti-xenoresponses are a major challenge to successful xenografts. Given the advantages of the use of CTLA4-Ig in the survival of allografts, the purpose of the study was to investigate the therapeutic potential of CTLA4-IgG4 modified immature dendritic cells (imDCs) in the prevention of islets xenograft rejection.

Methods

CTLA4-IgG4 was constructed by the fusion of the extracellular regions of porcine CTLA4 to human the hIgG4 Fc region. The imDCs were induced and cultured from porcine peripheral blood mononuclear cells (PBMC). The CTLA4-IgG4 modified imDCs were delivered via the portal vein to the liver of diabetic mice (insulin-dependent diabetes mellitus) before islet xenografting, and mCTLA4-Ig was administered intravenously after xenotransplantation.

Results

The xenograft survival of mice receiving unmodified imDCs was approximately 30 days. However, following administration of CTLA4-IgG4 modified imDCs before grafting and mCTLA4-Ig after grafting, xenografts survived for more than 100 days. Flow cytometric analysis showed that the CD4⁺CD25⁺Foxp3⁺ Treg population was increased in spleens. The efficacy of donor CTLA4-IgG4 modified imDCs correlated partially with the amplification of Tregs.

Conclusions

These results confirm that selective inhibition of the direct and indirect pathways of T-cell activation by donor CTLA4-IgG4 modified imDCs and receptor CTLA4-Ig is a highly effective strategy to promote survival of xenografts.     

Bmi-1 Promotes Glioma Angiogenesis by Activating NF-κB Signaling

Angiogenesis in glioma is associated with the poor prognosis of the disease and closely correlates with the highly invasive phenotype of glioma cells, which represents the most challenging impediment against the currently glioma treatments. Bmi-1, an onco-protein, has been implicated in the progression of various human cancers, including gliomas, whereas its role in glioma angiogenesis remains unclear. Our current study examined the effects of Bmi-1 on glioma angiogenesis in vitro as well as in vivo. We found that overexpression of Bmi-1 enhanced, whereas knockdown of Bmi-1 diminished, the capability of glioma cells to induce tubule formation and migration of endothelial cells and neovascularization in chicken chorioallantoic membrane. In vivo, Bmi-1 overexpression and knockdown, respectively, promoted and inhibited angiogenesis in orthotopically transplanted human gliomas. Furthermore, NF-κB activity and VEGF-C expression was induced by Bmi-1 overexpression, whereas Bmi-1 knockdown attenuated NF-κB signaling and decreased VEGF-C expression. Additionally suppression of NF-κB activity using a specific chemical inhibitor abrogated the NF-κB activation and the pro-angiogenic activities of glioma cells. Together, our data suggest that Bmi-1 plays an important role in glioma angiogenesis and therefore could represent a potential target for anti-angiogenic therapy against the disease.     

A Novel PRPF31 Mutation in a Large Chinese Family with Autosomal Dominant Retinitis Pigmentosa and Macular Degeneration

Purpose

This study was intended to identify the disease causing genes in a large Chinese family with autosomal dominant retinitis pigmentosa and macular degeneration.

Methods

A genome scan analysis was conducted in this family for disease gene preliminary mapping. Snapshot analysis of selected SNPs for two-point LOD score analysis for candidate gene filter. Candidate gene PRPF31 whole exons'' sequencing was executed to identify mutations.

Results

A novel nonsense mutation caused by an insertion was found in PRPF31 gene. All the 19 RP patients in 1085 family are carrying this heterozygous nonsense mutation. The nonsense mutation is in PRPF31 gene exon9 at chr19:54629961-54629961, inserting nucleotide “A” that generates the coding protein frame shift from p.307 and early termination at p.322 in the snoRNA binding domain (NOP domain).

Conclusion

This report is the first to associate PRPF31 gene''s nonsense mutation and adRP and JMD. Our findings revealed that PRPF31 can lead to different clinical phenotypes in the same family, resulting either in adRP or syndrome of adRP and JMD. We believe our identification of the novel “A” insertion mutation in exon9 at chr19:54629961-54629961 in PRPF31 can provide further genetic evidence for clinical test for adRP and JMD.     

Use of Thiopurines and Risk of Colorectal Neoplasia in Patients with Inflammatory Bowel Diseases: A Meta-Analysis

Objective

Inflammatory bowel disease (IBD) is commonly treated with thiopurines such as azathioprine and mercaptopurine for the maintenance of remission. Studies examining chemopreventive of these medications on colorectal neoplasm in IBD patients have yielded conflicting results. We performed a meta-analysis to assess the role of thiopurines for this indication.

Methods

We performed a systematic search of PubMed, Web of Science, EMBASE and Cochrane to identify studies reporting colorectal neoplasm from IBD patients treated with thiopurines and conducted a meta-analysis of pooled relative risk (RR) using the random effects model.

Results

Nine case-control and ten cohort studies fulfilled the inclusion criteria. The use of thiopurines was associated with a statistically significant decreased incidence of colorectal neoplasm (summary RR=0.71, 95% CI=0.54–0.94, p=0.017), even after adjustment for duration and extent of the disease, but there was high heterogeneity among studies (I ²=68.0%, p<0.001). The RR of advanced neoplasm (high-grade dysplasia and cancer) was 0.72 (95%CI=0.50–1.03, p=0.070) and that of cancer was 0.70 (95% CI=0.46–1.09, p=0.111) for thiopurine-treated patients. Heterogeneity of the studies was affected by the sample size (</≥100 cases) and whether the patients had longstanding colitis (≥7 years).

Conclusion

The current meta-analysis revealed that thiopurines had a chemopreventive effect of colorectal neoplasms and a tendency of reducing advanced colorectal neoplasms in IBD. Due to the heterogeneity of included studies, these results should be interpreted with caution.     

四川甘孜州高山葡萄酒产区酵母菌多样性分析

【背景】西南高山葡萄酒产区的甘孜州产区,具有生产优质葡萄酒的自然禀赋。【目的】研究四川甘孜州葡萄酒产区真核微生物种类多样性、本土酿酒酵母遗传多样性,以及商业酵母对本土酵母多样性的影响。【方法】利用ITS高通量测序技术对赤霞珠接种发酵和自然发酵过程中的微生物进行多样性分析,并利用Interdelta指纹图谱分析法,对经过26S rRNA基因鉴定的野生酿酒酵母基因型进行分类。【结果】ITS测序结果显示,接种发酵和自然发酵各时期均注释到7个科7个属的酵母,通过Interdelta指纹图谱分析发现甘孜州产区的酿酒酵母共有5种基因型。该产区酿酒酵母的6株代表菌株与我国其他产区109株酿酒酵母的进化树分析结果显示,均与来自北京产区的酿酒酵母菌株亲缘关系更近。【结论】甘孜州葡萄酒子产区酵母资源丰富,表现出较高的微生物多样性和中等程度的本土酿酒酵母基因型多样性,为后续优良本土酵母菌株的筛选奠定基础。     

Understanding lignin-degrading reactions of ligninolytic enzymes: binding affinity and interactional profile

Previous works have demonstrated that ligninolytic enzymes mediated effective degradation of lignin wastes. The degrading ability greatly relied on the interactions of ligninolytic enzymes with lignin. Ligninolytic enzymes mainly contain laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP). In the present study, the binding modes of lignin to Lac, LiP and MnP were systematically determined, respectively. Robustness of these modes was further verified by molecular dynamics (MD) simulations. Residues GLU460, PRO346 and SER113 in Lac, residues ARG43, ALA180 and ASP183 in LiP and residues ARG42, HIS173 and ARG177 in MnP were most crucial in binding of lignin, respectively. Interactional analyses showed hydrophobic contacts were most abundant, playing an important role in the determination of substrate specificity. This information is an important contribution to the details of enzyme-catalyzed reactions in the process of lignin biodegradation, which can be used as references for designing enzyme mutants with a better lignin-degrading activity.     

超选择子宫动脉栓塞治疗子宫肌瘤

目的探讨超选择子宫动脉栓塞治疗子宫肌瘤的方法及疗效。方法子宫肌瘤65例采用Seldinger技术经皮股动脉插管至双侧髂内动脉,造影了解肿瘤的血供来源后,超选至两侧子宫动脉,缓慢注入平阳霉素碘油乳剂或PVA微粒栓塞治疗。结果患者症状缓解率为93．2％,月经增多,痛经,尿频、尿急,贫血等1-3个月内恢复正常。并发症：除栓塞综合征外,可见阴道不规则流血,腰腿痛,可自行恢复。治疗后3-6个月肌瘤缩小率在30％-68％之间。中短期疗效较稳定,末见复发。治疗前后性激素水平变化无明显差异。结论子宫动脉栓塞术治疗子宫肌瘤操作简单安全,疗效好。超选择子宫动脉插管其分支栓塞,并发症少,具有较大的临床应用价值。     

Higher plant glycosyltransferases

Uridine diphosphate (UDP) glycosyltransferases (UGTs) mediate the transfer of glycosyl residues from activated nucleotide sugars to acceptor molecules (aglycones), thus regulating properties of the acceptors such as their bioactivity, solubility and transport within the cell and throughout the organism. A superfamily of over 100 genes encoding UGTs, each containing a 42 amino acid consensus sequence, has been identified in the model plant Arabidopsis thaliana. A phylogenetic analysis of the conserved amino acids encoded by these Arabidopsis genes reveals the presence of 14 distinct groups of UGTs in this organism. Genes encoding UGTs have also been identified in several other higher plant species. Very little is yet known about the regulation of plant UGT genes or the localization of the enzymes they encode at the cellular and subcellular levels. The substrate specificities of these UGTs are now beginning to be established and will provide a foundation for further analysis of this large enzyme superfamily as well as a platform for future biotechnological applications.     

Elementary Flux Mode Analysis Revealed Cyclization Pathway as a Powerful Way for NADPH Regeneration of Central Carbon Metabolism

NADPH regeneration capacity is attracting growing research attention due to its important role in resisting oxidative stress. Besides, NADPH availability has been regarded as a limiting factor in production of industrially valuable compounds. The central carbon metabolism carries the carbon skeleton flux supporting the operation of NADPH-regenerating enzyme and offers flexibility in coping with NADPH demand for varied intracellular environment. To acquire an insightful understanding of its NADPH regeneration capacity, the elementary mode method was employed to compute all elementary flux modes (EFMs) of a network representative of central carbon metabolism. Based on the metabolic flux distributions of these modes, a cluster analysis of EFMs with high NADPH regeneration rate was conducted using the self-organizing map clustering algorithm. The clustering results were used to study the relationship between the flux of total NADPH regeneration and the flux in each NADPH producing enzyme. The results identified several reaction combinations supporting high NADPH regeneration, which are proven to be feasible in cells via thermodynamic analysis and coincident with a great deal of previous experimental report. Meanwhile, the reaction combinations showed some common characteristics: there were one or two decarboxylation oxidation reactions in the combinations that produced NADPH and the combination constitution included certain gluconeogenesis pathways. These findings suggested cyclization pathways as a powerful way for NADPH regeneration capacity of bacterial central carbon metabolism.     

Dissecting metal ion-dependent folding and catalysis of a single DNAzyme

Protein metalloenzymes use various modes for functions for which metal-dependent global conformational change is required in some cases but not in others. In contrast, most ribozymes require a global folding that almost always precedes enzyme reactions. Herein we studied metal-dependent folding and cleavage activity of the 8-17 DNAzyme using single-molecule fluorescence resonance energy transfer. Addition of Zn2+ and Mg2+ induced folding of the DNAzyme into a more compact structure followed by a cleavage reaction, which suggests that the DNAzyme may require metal-dependent global folding for activation. In the presence of Pb2+, however, the cleavage reaction occurred without a precedent folding step, which suggests that the DNAzyme may be prearranged to accept Pb2+ for the activity. Neither ligation reaction of the cleaved substrates nor dynamic changes between folded and unfolded states was observed. These features may contribute to the unusually fast Pb2+-dependent reaction of the DNAzyme. These results suggest that DNAzymes can use all modes of activation that metalloproteins use.