Activation of human dendritic cells by liposomes derived from total lipid of mycobacterium smegmatis

• Main Author: Suhaimi, Nurfatihah Azlyna Ahmad
• Format: Thesis
• Language: English
• Published: 2023
• Subjects: R Medicine; RC109-216 Infectious and parasitic diseases
• Online Access: http://eprints.usm.my/59952/1/NURFATIHAH%20AZLYNA%20BINTI%20AHMAD%20SUHAIMI%20-%20FINAL%20THESIS%20P-UM001119%28R%29%20-D.pdf; http://eprints.usm.my/59952/
• Institution: Universiti Sains Malaysia

Liposomes are small-sized, potent, and self-assembled lipids that hold great potential as efficient drug delivery vehicles and adjuvants. They possess a unique vesicular structure and can be derived from natural and synthetic substances. Liposomes can mimic the biological membrane of drugs, thus extending the half-life and minimizing the toxicity levels while delivering them to the target organs. The adjuvant mechanism of liposomes has been intimately associated with the stimulation of desired immune responses upon the exposure of antigen and immune cell targeting. This current study mainly targets to investigate the activation of human DCs by liposomes derived from the total lipid of Mycobacterium smegmatis. Herein, the liposomes were produced from M. smegmatis total lipid and characterized under field emission scanning electron microscopy (FESEM), demonstrating a size ranging from 20 nm-135 nm with spherical structures. The human whole blood sample was collected and isolated to obtain the peripheral blood mononuclear cells (PBMCs) from three distinctive groups: TST-negative individuals, TST-positive individuals, and active pulmonary TB patients. The immune activation of DCs by M. smegmatis liposomes was analysed by the expression level of DCs surface markers (HLA-DR, CD11c, CD123, CD86) in flow cytometry and the secretion of cytokines (IFN-γ, IL-12p70, and IL-4) and via ELISA assay. The capability of liposomes to improve the antigen presentation during the active state of TB infection was approved through the increased level of HLA-DR and CD86 alongside the high concentration levels of IL-12p70, IFN-γ, and IL-4 cytokines. Further confirmation study via FESEM and confocal microscopy recognized the uptake of M. smegmatis liposomes by DCs. The exposure of liposomes to DCs in all study groups under FESEM imaging showed the large circular formation on the surface of DCs which pointed out the presence of liposomes on the surface of DCs compared to the negative and positive controls. The protrusion of dendrites with different cell-shaped development with the presence of different stimulators assisted in the activation of DCs. Similarly, the fluorescence signals observed under the confocal microscope supported the internalization of liposomes by DCs. Overall, this study suggests that liposomes have significant potential as effective vaccines and adjuvants for immunotherapy.