Effect And Mechanism Of MMI-0100 On Alzheimer’s Disease In Mice

P38 mitogen-activated protein kinase(p38MAPK)is one of the MAPK kinase families.A large number of studies have reported that p38MAPK/MK2 signaling pathway involved in the regulation of cell stress,inflammation,apoptosis and so on.For the target,the p38 MAPK inhibitor(SB203580)was developed,but the application and development were limited by the safety risks(liver toxicity,cardiotoxicity,central nervous system toxicity,etc.).As a result,the downstream substrate MK2 is considered as a new drug target for the regulation of inflammatory response.Recently,the designed MMI-0100 is an exogenous therapeutic polypeptide that could be targeted to inhibit MK2.In peripheral inflammatory studies have showed its good efficacy.So MMI-0100 targeting inhibition of p38MAPK/MK2 signaling pathway may also have a better regulatory effect on neuroinflammatory.Alzheimer’s disease(AD)is a neurodegenerative disease that affects hippocampus and neocortical brain regions,and the etiology is complex and unknown.However,long-term chronic neuroinflammatory causes continuous activation of glial cells and continuous release of inflammatory factor.This is an important process leading to neuronal death and brain disease.Our study focused on whether MMI-0100 attenuates cognitive impairment in the mouse AD model by inhibiting neuritis.Results:(1)Using the new object(NOR)and new position(OLR)memory recognition model,Neuritis induced by Aβ42 and LPS to promote memory impairment in mice.It was found that the memory impairment was slowed down after the administration of MMI-0100 24 h and showed no significant difference compared with the saline group.(2)Through immunohistochemistry,analysising CD11 b and GFAP protein expression to investigate the inflammatory response of microglia and astrocytes in hippocampus of mice.It was found that MMI-0100 could significantly reduce the high expression of CD11 b and GFAP induced by LPS,that is,MMI-0100 could decrease the activation of immune cells in CNS and keep it in resting state.(3)In tissue level,Real-time quantitative PCR analysis showed that MMI-0100 significantly reduced the expression of inflammatory factors(IL-6,IL-1β,TNF-α,i NOS)induced by Aβ42 and LPS.Western blot analysis showed that MMI-0100 could inhibit the inflammatory reaction by inhibiting ERK phosphorylation,and p38 MAPK could be degraded during the process of hippocampal tissue protein extraction,and its phosphorylation level could not be determined.(4)In BV-2 cell line,MMI-0100 can be significantly reduced neurological inflammation(IL-6,IL-1β,i NOS and COX-2)and the phosphorylation of ERK and p38 MAPK,indicating that MMI-0100 may reduce the LPS-induced inflammatory response by inhibiting ERK and p38 MAPK pathways.(5)MMI-0100 is a therapeutic polypeptide with cell-penetrating membrane activity.Interestingly,after MMI-0100 administration of nasal mucosa,the OLR and NOR memory impairment models induced by Aβ42 and LPS found that MMI-0100 was able to restore the memory of the mice and no significant difference with the control group.To illustrate this phenomenon,the fluorescence labeled Cy7.5-MMI-0100 was subjected to small animal fluorescence imaging to determine that MMI-0100 could through its cell nasal mucosa entry the brain area.This will be a good reference value for the poor stability of the peptide drug and the low correlation of BBB.