Cytotoxicity Of Gp120 Derived Amyloidogenic Peptides To Lymphocytes By Amyloid-Membrane Interaction

BACKGROUND:AIDS,also known as Acquired Immune Deficiency Syndrome,is the most serious single-cause disease in humans characterized by severe systemic immune system damage.As of 2018,nearly 37 million people worldwide are still infected with HIV,which seriously threatens human health and survival globally.Once HIV infects the host,the HIV-specific immune response has not yet occurred,the rate of HIV replication and expansion in the body is very fast,and the number of CD4+T cells in the peripheral blood decreases rapidly.Replication and amplification have a strong inhibitory effect,at which time the body enters a period of dynamic equilibrium where the virus is constantly being produced and cleared.Subsequently,CD4+T cells continue to decline.Finally,due to the long-term infection and replication of HIV-1,the number of CD4+T cells drops to below 200 cells/μl,at the same time,the immune system is completely destroyed,eventually leading to a variety of opportunistic infections and tumors.Therefore,the reduction of CD4+T cells is the core issue during the pathogenesis of HIV-1.Clarifying the mechanism of CD4+T cell reduction has important significance for the diagnosis and treatment of AIDS.The previous research results of our group show that amyloid peptides(GAPs)which derived from HIV envelope protein gp120 in AIDS human body can spontaneously form amyloid fibers and significantly promote HIV infection.Meanwhile,GAPs and other pathological amyloid polypeptides like Aβ that have similar structures can cause cell membrane damage and mediate cytotoxicity.Studies have shown that HIV-1 envelope glycoprotein gp 120 can regulate the immune system,which is probably related to the down-regulation of CD4+T lymphocytes;considering the pathological role of GAPs and its relationship with gp120,we believe that GAPs are also likely to be new targets for HIV treatment.Objectives:The purpose of our study is to investigate the role of amyloid polypeptide GAPs in the lymphatic system of the HIV-infected patients and their effect on immune function.Based on in vitro experiments,we investigate whether the GAPs could bind to the membrane of lymphocytes and induce cytotoxicity,whether they could mediate cell membrane damage by the same mechanisms with other pathological amyloid polypeptides and cause damage to the lymphatic system in animals.We aim to clarify the role of GAPs in the lympatic system,and provide new ideas and methods for the treatment of HIV.Method:1.The binding of GAPs with lymphocyte cell membranes was explored using flow cytometry and laser confocal microscopy;2.GAPs induced lymphocyte inflammation response was investigated using RT-PCR assay;3.The toxic effect of GAPs on lymphocytes was detected by XTT assays;4.The binding of GAPs with membranes was explored using phospholipid membrane model LUVs;5.The binding ability of GAPs and LUVs was detected by ITC assay;6.The binding between GAPs and LUVs membranes was detected by CD spectroscopy to explore possible membrane damage mechanisms;7.The damage effect of GAPs on Membrane was explored by calcium leakage experiment and transmission electron microscopy.8.The effects of GAPs on lymphoid tissues was explored through animal models.RESULTS:1.GAPs were found to bind to lymphocyte membranes by flow cytometry and laser confocal microscopy;2.GAPs could induce the release of lymphocyte cytokines in vitro;3.GAPs could induce lymphocyte death,indicating that GAPs may play a toxic role in the lymphatic system;4.It was found that GAPs have obvious film damage effects through ITC,CD,TEM assays and dye leakage experiments;5.It was found that GAPs could cause the release of lymphokines which lead to the activation of T cells in mice.The germinal centers of lymphocytes in the spleen were immature caused by the GAPs,which affected the growth and differentiation of lymphocytes.CONCLUSION:1.GAPs bind to the cell membrane of lymphocytes,which cause the release of inflammatory factors and lead to the death of lymphocytes.2.GAPs have a common toxicological mechanism with other pathological amyloid polypeptides,which can bind to cell membranes and cause increased cell membrane permeability.and lead to cell death.3.GAPs can affect the lymphocyte e generation and differentiation in lymphoid tissues in the body,which affect the immune function of the lymphatic system.