| Objective:Alzheimer's disease(AD)is the most common neurodegenerative disease characterized with progressive memory loss and cognitive dysfunction.So far,the pathogenesis of AD has not been fully elucidated,and there are no effective intervention measures.Therefore,it is of great medical and social significance to explore the pathogenesis of AD and find effective early intervention measures to reduce the occurrence and delay the development of AD.The peripheral immune system is considered as an important contributor to the pathogenesis of Alzheimer's disease(AD).Macrophages are phenotypically and functionally similar to the resident microglial cells in the central nervous system(CNS),which can enter the brain through the damaged blood brain barrier(BBB),then change to be bone marrow-derived microglia.Studies have found that these bone marrow-derived macrophages(BMDMs)had more efficient phagocytosis and played an important role in pathogenesis of AD.A cohort study of familial AD found that the plasma A?1-42peptide levels had increased significantly almost 15 years before the onset of AD.A?1-42is a major pathological product of AD,and it's also an inflammatory activator.Monocytes/macrophages are key effectors and regulators of innate immune response and play an important role in inflammatory response.Previous studies have demonstrated that mononuclear macrophage are involved in pathogenesis of AD,however,the effects of high levels of A?1-42peptide in plasma on mononuclear macrophage are still unclear.Myeloid derived suppressor cells(MDSCs)are the major immunosuppressive cells that can be recruited into inflammatory tissues exerting immunosuppresive effects during the chronic inflammatory process.MDSCs can mediate the polarization of macrophages and affect the numbers and functions of mononuclear macrophages.The numbers of mononuclear macrophages and MDSCs in peripheral circulation and tissues are affected by the proliferation and differentiation of bone marrow hemopietic stem cells(HSCs).The proliferation and differentiation of HSCs are precisely regulated by multiple signal transduction pathways inside and outside the cells.Janus kinase(JAK)/signal transducer and activator of transcription(STAT),Mitogen-activated protein kinase(MAPK)/Extracellular signal-regulated kinase(ERK),Phosphatidylinositol-3 kinase(PI3K)/serine-threonine kinase(Akt)signal pathway are the important pathway which are involved in regulating proliferation,differentiation,and apoptosis of cell.Thus,we conducted the following two parts of experiments to study the effects and mechanisms of high plasma levels of A?1-42peptide on mononuclear macrophage in AD mouse models.Part 1 The effects of plasma high levels of A?1-42on numbers and functions of mononuclear macrophage in Alzheimer's disease mouse modelsObjective:In this study,three AD animal models were used to explore the effects of high plasma A?1-42on numbers and functions of monocytes in spleen and macrophages in the peritoneal cavity of mouse.Methods:(1)Establishing AD animal models:(1)3 months old female C57BL/6 wild-type(Wt)mice and APPswe/PS1d E9(APP/PS1)transgenic(Tg)mice were constructed the parabiosis animal models of Wt mice and Tg mice(Parabiotic Wt-Tg,Pa(Wt-Tg)),and Wt mice and Wt mice(Parabiotic Wt-Wt,Pa(Wt-Wt))respectively;(2)A?1-42peptide was intravenously injected into Wt mice via the tail vein;(2)Detecting A?1-42levels in plasma and A?deposition in brain of mouse after high plasma levels of A?1-42sustaining stimulation for 4 and 8 months;(3)Detecting the changes of the numbers of monocytes in spleen and macrophages in peritoneal cavity of mouse after high plasma levels of A?1-42sustaining stimulation for 4 and 8months and tail intravenous injection with A?1-421 week;(4)Detecting the numbers of BMDMs in mouse brain after high plasma levels of A?1-42sustaining stimulation for 4and 8 months;(5)Detecting the alterations of macrophages phagocytosis of mouse after high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-421 week;(6)Detecting the alterations of cytokines levels in mouse plasma after high plasma levels of A?1-42sustaining stimulation for 4and 8 months and tail intravenous injection with A?1-421 week;Results:(1)The levels of plasma A?1-42in the Wt mice of Pa(Wt-Tg)animal model(Pa Wt(Wt-Tg))were significantly elevated,and in Pa Wt(Wt-Tg)mice brain formed A?deposition;Bioluminescence imager observed that A?1-42peptide labeled with Hi Lyte Fluor 488 entered the Wt mice;(2)After 4 months sustaining stimulation with high plasma levels of A?1-42,the percents of monocytes in spleen were increased and the percents of pro-inflammatory macrophages in peritoneal cavity were reduced,after 8 months sustaining stimulation,the percents of monocytes in spleen and the percents of pro-inflammatory macrophages in peritoneal cavity were increased;(3)High plasma levels of A?1-42stimulation for 8 months,the numbers of BMDMs in mouse brain were increased;(4)High plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-421 week,the phagocytosis of macrophages had no notable alterations;(5)After 4 months high plasma levels of A?1-42sustaining stimulation,the expressions of pro-inflammatory cytokines IL-6 in plasma were reduced,after 8 months sustaining stimulation,the expressions of pro-inflammatory cytokines IL-6 and TNF-?in plasma were increased,after tail intravenous injection with A?1-421 week,the expressions of IL-6 were increased;Conclusion:Wt mice can obtain long-term and stable stimulation of high plasma levels of A?1-42from Tg mice by parabiosis,and the parabiosis mice models meet the requirements of our experiment.High plasma levels of A?1-42had a biphasic regulating effects on pro-inflammatory macrophages and pro-inflammatory cytokines.The sustaining stimulation of high plasma levels of A?1-42for 4 months inhibited the expressions of pro-inflammatory macrophages and pro-inflammatory cytokines,sustaining stimulation for 8 months promoted the expressions of pro-inflammatory macrophages and pro-inflammatory cytokines,playing the pro-inflammatory roles.Part 2 The effects and mechanisms of plasma high levels of A?1-42on myeloid derived suppressor cells and bone marrow myeloid progenitor cells in Alzheimer's disease mouse modelsObjective:In this study,three AD animal models were used in this study to explore whether the effects of chronic inflammatory response induced by plasma high levels of A?1-42on MDSCs and myeloid progenitor cells in bone marrow are involved in the regulation of A?1-42on monocytes/macrophages,and further explore the signal pathway involved in regulating the proliferation and differentiation of HSCs.Methods:(1)Detecting the changes of the numbers of MDSCs in mouse spleen after high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-42one week;(2)Detecting the changes of the numbers of MDSCs in mouse bone marrow after high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-42one week;(3)Detecting the changes of the numbers of myeloid progenitor cells in mice bone marrow after high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-42one week;(4)Detecting the proliferative functions of the bone marrow cells(BMCs)of mouse after high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-42one week;(5)Detecting the expressions of JAK/STAT,MAPK/ERK,PI3K/Akt signal pathway m RNA in mouse BMCs after high plasma levels of A?1-42sustaining stimulation for 8 months;(6)Detecting the protein expressions of JAK/STAT,MAPK/ERK,PI3K/Akt signal pathway in mouse BMCs after high plasma levels of A?1-42sustaining stimulation for 8 months;Results:(1)After high plasma levels of A?1-42sustaining stimulation for 4months,the percents of MDSCs in mouse spleen were reduced,after 8 months sustaining stimulation and tail intravenous injection with A?1-42one week,the percents of MDSCs were increased;(2)After high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-42one week,the percents of MDSCs in mouse bone marrow had no notable alterations;(3)After high plasma levels of A?1-42sustaining stimulation for 4 months,the percents of bone marrow granulocyte-monocyte progenitors(GMP)of mouse were decreased,after 8months sustaining stimulation,the percents of GMP were increased,after tail intravenous injection with A?1-42one week,the percents of GMP had no alteration;(4)After high plasma levels of A?1-42sustaining stimulation for 4 and 8 months and tail intravenous injection with A?1-42one week,the proliferative functions of BMCs were elevated;(5)High levels of plasma A?1-42sustaining stimulation for 8 months,the expressions of STAT3 m RNA were increased;(6)High levels of plasma A?1-42sustaining stimulation for 8 months,the expressions of STAT3,STAT5 protein were increased;Conclusion:High plasma levels of A?1-42had biphasic regulatory effects on the numbers of mouse spleen MDSCs and bone marrow myeloid progenitor cells,and A?1-42promoted the proliferative functions of BMCs via activating the STAT3 and STAT5 protein expressions.The alterations of the number and proliferation of myeloid progenitor cells in bone marrow may be involved in the regulation of peripheral MDSCs and monocytes/macrophages. |
PDF Full Text Request