Preparation and immune-enhancing effects of monophosphoryl lipid A pH-sensitive liposome
10.3760/cma.j.cn112309-20220302-00066
- VernacularTitle:单磷酸脂质A(MPLA)pH敏感脂质体制备及免疫增强作用研究
- Author:
Wenyu CUI
1
;
Wenjing QUAN
;
Jilai LI
;
Yibo HOU
;
Jing XU
;
Yuntao ZHANG
Author Information
1. 国药中生生物技术研究院第三研究室，北京 101111
- Keywords:
pH-sensitive liposome;
Monophosphoryl lipid A;
Adjuvant
- From:
Chinese Journal of Microbiology and Immunology
2022;42(9):699-704
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To prepare pH-sensitive liposomes to avoid the degradation of monophosphoryl lipid A (MPLA) by lysosomes.Methods:Using DOPE and CHEMS as carrier materials, pH-sensitive liposomes were prepared by thin-film dispersion method. Particle sizes and Zeta potential of the liposomes were detected by dynamic light scattering. The morphological features of pH-sensitive liposomes under different pH conditions were observed by transmission electron microscopy. Flow cytometry was performed to detect the phagocytosis of liposomes by THP-1 and DC2.4 cells. Confocal laser microscopy was used to observed the colocalization of liposomes and lysosomes. BALB/c mice were immunized with hepatitis B surface antigen (HBsAg) using MPLA pH-sensitive liposome as an adjuvant. The levels of serum anti-HBs were quantitatively detected by ELISA. IFN-γ and IL-2 spot forming cells (SFCs) in mouse splenic lymphocytes were detected by ELISPOT.Results:The pH-sensitive liposomes were constructed with an average particle size of (90.90±1.13) nm, polydispersity index (PDI) of 0.076±0.013 and Zeta potential of (-27.900±0.666) mV. As the pH value of the solution decreased, the particle size increased significantly and the liposomes presented irregular shapes, indicating the pH-sensitive features. The phagocytosis rates by THP-1 cells and DC2.4 cells were 10.40% and 12.40% for pH-sensitive fluorescent liposomes, and 1.09% and 0.28% for fluorescent liposomes. Confocal laser microscopy revealed that pH-sensitive fluorescent liposomes were phagocytosed by THP-1 cells and existed in the cytoplasm, while fluorescent liposomes existed in lysosomes. Compared with MPLA liposomes, MPLA pH-sensitive liposomes could significantly improve the cellular immune response in mice. The levels of IFN-γ and IL-2 SFCs in the MPLA pH-sensitive liposome group were significantly higher than those in the MPLA liposome group ( P<0.01) and the non-adjuvant group ( P<0.001). Conclusions:The pH-sensitive liposome delivery system could improve the utilization of MPLA as an adjuvant.
