Jain Sanyog, Singh Paramjit, Mishra Vivek, Vyas S P
Drug Delivery Research Laboratory, Department of Pharmaceutical Sciences, Dr. Harisingh Gour University, Sagar 470003, MP, India.
Immunol Lett. 2005 Oct 15;101(1):41-9. doi: 10.1016/j.imlet.2005.04.002. Epub 2005 Apr 25.
Aim of the present study was to develop mannosylated niosomes as oral DNA vaccine carriers for the induction of humoral, cellular and mucosal immunity. Niosomes composed of span 60, cholesterol and stearylamine as constitutive lipids were prepared by reverse phase evaporation method and were coated with a modified polysaccharide o-palmitoyl mannan (OPM) in order to protect them from bile salt caused dissolution and enzymatic degradation in the gastrointestinal tract and to enhance their affinity towards the antigen presenting cells of Peyer's patches. Prepared niosomes were characterized in vitro for their size, shape, entrapment efficiency, ligand binding specificity and stability in simulated gastric fluid and simulated intestinal fluid. OPM coated niosomes were found to better stable in simulated GIT conditions. The immune stimulating activity was studied by measuring serum anti-HBsAg titer, secretory IgA level in intestinal and salivary secretions and cyokines level (IL-2 and IFN-gamma) in spleen homogenates following oral administration of niosomal formulations in Balb/c mice and compared with naked DNA as well as pure recombinant HBsAg injected intramuscularly. The serum anti-HBsAg titer obtained after oral administration of OPM coated niosomal formulations was although less as compared to that elicited by naked DNA and pure HBsAg administered intramuscularly, but the mice were seroprotective within 2 weeks and antibody level far above the clinically protective limit for humans was achieved. Intramuscular naked DNA and recombinant HBsAg did not elicited sIgA titer in mucosal secretions that was induced by oral administration of OPM coated niosomes. Similarly, cellular response (cytokines level) was absent in pure HBsAg treated animals. OPM coated niosomes produced humoral (both systemic and mucosal) and cellular immune response upon oral administration. The study signifies the potential of OPM coated niosomes as DNA vaccine carrier and adjuvant for effective oral immunization.
本研究的目的是开发甘露糖基化脂质体作为口服DNA疫苗载体，以诱导体液免疫、细胞免疫和黏膜免疫。采用逆相蒸发法制备了由司盘60、胆固醇和硬脂胺作为组成脂质的脂质体，并用改性多糖邻棕榈酰甘露聚糖（OPM）进行包被，以保护它们免受胆汁盐引起的溶解以及胃肠道中的酶降解，并增强它们对派伊尔结抗原呈递细胞的亲和力。对制备的脂质体进行体外表征，测定其大小、形状、包封率、配体结合特异性以及在模拟胃液和模拟肠液中的稳定性。发现OPM包被的脂质体在模拟胃肠道条件下更稳定。通过在Balb/c小鼠口服脂质体制剂后测量血清抗HBsAg滴度、肠道和唾液分泌物中的分泌型IgA水平以及脾匀浆中的细胞因子水平（IL-2和IFN-γ）来研究免疫刺激活性，并与裸DNA以及肌肉注射的纯重组HBsAg进行比较。口服OPM包被的脂质体制剂后获得的血清抗HBsAg滴度虽然低于裸DNA和肌肉注射的纯HBsAg所引发的滴度，但小鼠在2周内具有血清保护作用，并且抗体水平远高于人类的临床保护限值。肌肉注射的裸DNA和重组HBsAg未在黏膜分泌物中引发口服OPM包被的脂质体所诱导的分泌型IgA滴度。同样，纯HBsAg处理的动物中没有细胞反应（细胞因子水平）。口服后，OPM包被的脂质体产生了体液免疫（全身和黏膜）和细胞免疫反应。该研究表明OPM包被的脂质体作为DNA疫苗载体和佐剂用于有效口服免疫的潜力。
