Nucleic acid vaccines: prospects for non-viral delivery of mRNA vaccines

Introduction: Nucleic acid-based vaccines are being developed as a means to combine the positive attributes of both live-attenuated and subunit vaccines. Viral vectors and plasmid DNA vaccines have been extensively evaluated in human clinical trials and have been shown to be safe and immunogenic, although none have been licensed for human use. More recently, mRNA-based vaccine alternatives have emerged and might offer certain advantages over their DNA-based counterparts.

Areas covered: This review describes the two main categories of mRNA vaccines: conventional non-amplifying and self-amplifying mRNA. It summarizes the initial clinical proof-of-concept studies and outlines the preclinical testing of the next wave of innovations for the technology. Finally, this review highlights the versatile functionality of the mRNA molecule and introduces opportunities for future improvements in vaccine design.

Expert opinion: The prospects for mRNA vaccines are very promising. Like other types of nucleic acid vaccines, mRNA vaccines have the potential to combine the positive attributes of live attenuated vaccines while obviating many potential safety limitations. Although data from initial clinical trials appear encouraging, mRNA vaccines are far from a commercial product. These initial approaches have spurred innovations in vector design, non-viral delivery, large-scale production and purification of mRNA to quickly move the technology forward. Some improvements have already been tested in preclinical models for both prophylactic and therapeutic vaccine targets and have demonstrated their ability to elicit potent and broad immune responses, including functional antibodies, type 1 T helper cells-type T cell responses and cytotoxic T cells. Though the initial barriers for this nucleic acid vaccine approach seem to be overcome, in our opinion, the future and continued success of this approach lies in a more extensive evaluation of the many non-viral delivery systems described in the literature and gaining a better understanding of the mechanism of action to allow rational design of next generation technologies.     

酸枣仁汤对抑郁模型大鼠皮质、海马中NMDAR1、NMDAR2A、NMDAR2B基因表达的影响

目的观察酸枣仁汤对抑郁模型大鼠大脑皮质、海马中NMDAR1、NMDAR2A、NMDAR2B基因表达的影响,并探讨其作用机制。方法将大鼠随机分为空白组、模型组、西药组和酸枣仁汤高、中、低剂量组,除空白组外,其余各组大鼠均以慢性应激法复制抑郁症模型,各给药组给予相应药物灌胃。采用RT-PCR检测大鼠皮质、海马中NMDAR1、NMDAR2A和NMDAR2B基因的表达。结果与模型组比较,酸枣仁汤高、中剂量组大鼠皮质和海马中NMDAR1阳性表达均降低(P0.01);酸枣仁汤高、中剂量组和西药组皮质和海马中NMDAR2A阳性表达均降低(P0.05,P0.01),酸枣仁汤低剂量组海马中NMDAR2A表达增高(P0.05);酸枣仁汤高、中、低剂量组和西药组皮质中NMDAR2B阳性表达均降低(P0.01),酸枣仁汤中、低剂量组海马中NMDAR2B表达增高(P0.01)。结论酸枣仁汤可能通过降低大鼠皮质、海马中NMDAR1、NMDAR2A、NMDAR2B基因表达达到治疗抑郁症的作用。     

电针对VD大鼠海马神经细胞PKC mRNA、mGluRs和AMPAR表达的影响

目的 观察电针对血管性痴呆(VD)大鼠海马神经细胞PKC mRNA、mGluRs、AMPAR表达的影响,探讨电针的治疗作用机制.方法 将SD大鼠随机分为假手术组、模型组和电针组,每组10只.模型组和电针组采用重复脑缺血再灌注方法建立VD大鼠模型.将电针组大鼠放入大鼠固定器中,暴露大鼠头部和背部,将电针浅刺入大鼠“百会”、“大椎”穴,每天电针1次,留针20 min,连续治疗10 d.3组大鼠均于造模10d后采用逆转录聚合酶链式反应(RT-PCR)检测海马神经细胞PKC mRNA,免疫组织化学染色技术观察脑组织海马神经细胞mGluRs、AMPAR染色结果.结果 模型组海马PKC mRNA表达较假手术组降低,而与模型组比较,电针组海马PKC mRNA表达显著增加,差异有统计学意义(P＜0.05).海马mGluRs免疫阳性细胞积分光密度在假手术组、模型组和电针组分别为(58.6±3.6)、(36.3±2.5)和(51.5±4.8),与假手术组比较,模型组海马mGluRs免疫阳性细胞积分光密度显著降低,差异有统计学意义(P＜0.01);而与模型组比较,电针组海马mGluRs免疫阳性细胞积分光密度显著增加,差异有统计学意义(P＜0.05);海马AMPAR免疫阳性细胞积分光密度在假手术组、模型组和电针组分别为(66.5±2.8)、(40.1±5.1)和(58.3±4.6),与假手术组比较,模型组海马AMPAR免疫阳性细胞积分光密度显著降低,差异有统计学意义(P＜0.01),而与模型组比较,电针组海马AMPAR免疫阳性细胞积分光密度显著增加,差异有统计学意义(P＜0.05).结论 电针可增加VD大鼠海马PKC mRNA、mGluRs和AMPAR表达.电针大鼠“百会”、“大椎”穴改善大鼠学习记忆能力的机制可能与提高海马mGluRs、AMPAR和PKC mRNA表达有关.     

Identification of TLR downstream pathways in stroke patients

Objective

Toll-like receptors (TLRs) are important molecules for detecting both pathogen invasion and tissue damage. The expression of TLR4 is upregulated in ischemic stroke, at least in the subacute stage. However, the TLR downstream pathways in the context of stroke have not been well studied in previous research. The purpose of this study is to elucidate the TLR4 downstream pathways following ischemic stroke.

Design and methods

In this study, 12 ischemic stroke patients and 12 controls were selected from among 89 ischemic stroke patients and 166 controls. The chosen subjects had the highest levels of TLR4 mRNA in the peripheral blood. The differences in the TLR downstream signaling pathways, which were studied by using an RT2 Profiler TM PCR array system (Qiagen), were analyzed. The differentially expressed genes were analyzed by using GeneSpring GX and visualized based on the TLR pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG).

Results

The genes upregulated in stroke patients were found to be involved in the MyD88-independent pathway and in UBE2V1–TRAF6 ubiquitin-mediated proteolysis. The genes were more expressed in extracellular space, receptor binding, and cytokine receptor binding by use of gene ontology (GO) terms than in control patients.

Conclusions

We found that the MyD88-independent pathway and the ubiquitin-mediated proteolysis pathway, especially TRAF6, may be the most vital molecules among TLR downstream pathways in incidences of ischemic stroke.     

EFFECTS OF NITRIC OXIDE ON REPERFUSION INJURY FOLLOWING PANCREATICODUODENAL TRANSPLANTATION IN RATS

NITRIC oxide(NO ) isa potentvasodilatofrormswhen L-arginine(L-Arg)isconvertedtoL-Citrul-lineby theactionofNO synthase(NOS ),and pla-ysa major roleinmicrocirculatorhyomeostasis.1 NO isalsoa diffusiblientercellulmaerssenger moleculethatdoes notrequirespecialmembrane carrier,sand a highlyreactivseub-stancewitha veryshorthalf-lifdeue toitschemicalinstabi-lityas a radicalspecies.2,3 Posttransplantatipoanncreatitisand graftthrombosisaretwo majorcomplicationosf pancreastransplantatiocnontribut…     

豚鼠内淋巴囊透明质酸合成酶原位杂交方法的初探

目前在豚鼠内淋巴囊进行原位杂交的方法欠稳定,本研究总结出一种豚鼠内淋巴囊透明质酸合成酶原位杂交的方法,现报告如下.     

EXPRESSION OF mRNA FOR MEMBRANE-TYPE 1, 2, AND 3 MATRIX METALLOPROTEINASES IN HUMAN LARYNGEAL CANCER

DEGRADATIONofextracellularmatrix(ECM)andbasementmembranes(BM)isakeystepinthein-vasionandmetastasisofmalignanttumors.Previ-ousstudieshavedemonstratedthatmarixmetalloproteinases(MMPs)arethemostimportantproteolyticenzymesinthedegradationofECMandBM.1 AmongtheMMPs,MMP-2candegradecollagenⅣ,amajorcomponentofBM,andhasbeendemonstratedtoplayacriticalroleintheprogressofvariouscarcinomas.2 MMP-2issecretedasinactivezymogens(proMMP-2)whoseuniqueactivatorsaremembranetypemarixmetalloproteinases…