Dissertation > Excellent graduate degree dissertation topics show

Effects of Icaritin and HIV gp41 Fusion Peptide on the Function of T Cell Subsets

Author: HuYiPing
Tutor: LiuShuWen
School: Southern Medical University,
Course: Pharmacology
Keywords: Icaritin Immunoregulation HIV gp41 fusion peptide CD4~+ CD25~+ regulatory T cells
CLC: R285.5
Type: Master's thesis
Year: 2010
Downloads: 79
Quote: 0
Read: Download Dissertation

Abstract

Background:Acquiredimmunodeficiency syndrome (AIDS) is the major threats to public health worldwide.Human immunodeficiency virus (HIV) is class I enveloped virus. Class I enveloped viruses share a similar virus-host cell membrane fusion mechanism. The envelope glycoprotein binds to the host cell receptor and undergoes conformational changes which trigger the membrane fusion. The membrane fusion is mediated by the envelope glycoprotein of HIV gp160.Gp160 consist of two associated parts, the surface subunit gp120 responsible for binding receptor and the transmembrane subunit gp41 mediating membrane fusion.HIV is a lentivirus that cause AIDS,a disease that progressive reduction of the effectiveness of human immune system, leading to life-threatening opportunistic infections and cancers. HIV primarily infects vital cells in the human immune system such as CD4 positive T cells.To develop effective therapeutics and vaccines for treatment and prevention of AIDS,it is critical to understand pathogenesis of HIV infection and the interaction between virus and immune cells, especially T cell activation mediated by viral proteins.T cell activation is a double edged sword in the pathogenesis of AIDS.On one hand, T cell activation is required to eliminate the infected viruses because the CD4 positive T cells can mediate humoral and cellular immune responses against HIV.On the other hand, HIV preferentially infects the CD4 positive T cells, especially those in mucosa. Abnormal CD4 positive T cells activation caused by HIV contributes to activation induced cell apoptosis and precedes the host immune system crash. However, proper regulation of CD4 positive T cells activation may be applied as a therapeutic or strategy for the treatment and prevention of HIV. Munch et al had reported that a peptide derived from the subfragment of antitrpsin designed as virus inhibitory peptide, is able to interact with the HIV gp41 fusion peptide and inhibit HIV envelope mediated cell fusion. Fusion peptide could effectively downregulate the CD4 positive T cells activation.AIMS:To compare the different function of the natural active product Icaritin and Cyclosporin A.To study the effects of ConA on the early activation and the suppressed function of CD4+CD25+ regulatory T cells. To investigate the effect of the envelope protein gp41 fushion peptide on the non-antigen specific regulatory T cells and antigen specific regulatory T cells.METHODS:T cells were separated from spleen of mice.To investigate the effects of Icaritin on the T cells proliferation, T cells were stained by CFSE and the incubated with different concentration of Icaritin. After 6 days, the results were analyzed by flow cytometry. Then the activation marker of IL-2 receptor CD25 was detected. IL-2 secretion was analyzed by ELISA in order to test the effect of Icaritin. The CD4+ CD25+ regulatory T cells and CD4+CD25- effector T cells of BALB/c mice were separated by MACS immunomagnetic beads.After twelve hours of stimulation with different concentrations of ConA, the cells were collected and the percentage of CD69 expression was analyzed by flow cytometry. In addition, the CD4+CD25-effector T cells were stained by CFSE and co-cultured with the CD4+CD25+ regulatory T cells in a ratio of 2:1.After three days’stimulation of ConA, the suppressed function of the CD4+CD25+ regulatory T cells on the CD4+CD25-effector T cells was analyzed by flow cytometry. The effect of the HIV envelope protein gp41 fusion peptide on the early activation marker CD69 of the non-antigen specific regulatory T cells stimulated by ConA and PDB and antigen specific regulatory T cells stimulated by OVA was analyzed by flow cytometry.RESULTS:Icaritin could inhibit T cell proliferation, as well as CD4 positive T cell proliferation by using flow cytometry. Icaritin could inhibit expression of CD4 positive T cell IL-2 receptor CD25.Icaritin could also inhibit the secretion of IL-2. ConA could dose-dependently increase the percentage of CD69 expression of both CD4+CD25+ regulatory T cells and CD4+CD25- effector T cells. It acts similarly in enhancing the expression of CD69 on these two group cells. Moreover, ConA could dose-dependently activate the suppressed function of the CD4+CD25+ regulatory T cells on the CD4+CD25- effector T cells.HIV envelope protein gp41 fusion peptide increase the CD69 expression of antigen specific regulatory T cells stimulated by OVA,but fusion peptide doesn’t affect the CD69 expression of non-antigen specific regulatory T cells stimulated by ConA and PDB.CONCLUSION:Icaritin, as a natural active product, has immune suppression function. The activation and the function of CD4+CD25+ regulatory T cells in vitro could be enhanced by ConA. Considering that ConA can mimic the antigen to some extent, this system can be used to evaluate the influence of the drugs on the activation and the function of the regulatory T cells. Although HIV envelope protein gp41 fusion peptide doesn’t affect the function of non-antigen specific regulatory T cells, fusion peptide could enhance the suppressive function of antigen specific regulatory T cells on the antigen specific effector T cells, therefore inhibit the anti HIV immune response and escape from the immune system.

Related Dissertations

CLC: > Medicine, health > Chinese Medicine > Of Pharmacy > Pharmacology > Chinese medicine Experimental Pharmacology
© 2012 www.DissertationTopic.Net Mobile