A Study On Molecular Mechanisms For Human FcγRⅡa-mediated Enhancement Of Macrophage Virus Permeability And Viral Antigen Presentation Using A Transgenic Mouse Model

The autogenic antiviral response includes innate immune response and adaptive immune response.Compared with innate immune response,the specificity and memory of the adaptive immune response ensure the body capable of killing and defending against viruses.As we all know,all vaccines should induce the body to produce a strong and long-lasting antiviral adaptive immune response.Antiviral adaptive immunity starts with an innate immune response,and the connection between innate and adaptive immunity is antigen-presenting cells.As a powerful antigen-presenting cell,macrophages can present intracellular viral antigens and provide co-stimulatory signals to promote the proliferation and activation of lymphocytes.Antigen-presenting macrophage is an important guarantee for eliciting a potent antiviral adaptive immune response.In a previous study of this experiment,we found that immune-complex treated monocytes were more susceptible to viruses.It’s due to the cross-link of the Fc fragment of antibody and hFcγRⅡa on the surface of monocytes.This phenomenon is consistent with the previously reported antibody-dependent enhancement(ADE)that the non-neutralizing antibodies engage the virus to be a complex,and then cross-link FcyR to promote the infection of viruses.Although ADE will increase the virus titer in monocytes/macrophages,it also has been reported that if appropriately reduces the antiviral ability of macrophages and controllable promotes the intracellular replication of viruses.It can make macrophages present enough antigenic peptides to promote the antiviral adaptive immunity.Since mouse immune cells have no homologous protein of hFcyRⅡa,we constructed hFcyRⅡa transgenic(hFcyRⅡa-Tg)mice to mimic the inereased viral replication effect of human monocytes.Our previous study found that the monocytes/macrophages of hFcyRⅡa-Tg mice were also susceptible to viruses.Therefore,we wonder whether this kind of virus-increasing effect similar to ADE in the process of chronic virus infection or re-infection can enhance the body’s adaptive immunity.In this study,we first demonstrated that macrophages(Tg-PEM)from hFcyRⅡaTg mice were more susceptible to virus infection than macrophages(WT-PEM)from wild-type mice.Tg-PEM can also induce better proliferation of antigen-specific CD8~+T cells in vitro and in vivo and promote the polarization of naive CD8~+T cells to antiviral effector CD8~+T cells that can secrete more INF-γ and TNF-α.At the same time,Adoptive transfer of the virus-infected Tg-PEM can also initiate a stronger antiviral adaptive immune response in mice to inhibit virus infection.Compared with WT mice,Tg mice have more and stronger antiviral-specific CD8~+T cells after chronic viral infection,which can significantly resist chronic viral infection and re-infection.We previously found that improved E3 ubiquitin ligase TRIM54 in monocytes upon immune complex treatment will inhibit the antiviral response of monocytes,thereby promoting intracellular viral replication.Through systemic knockout of TRIM54 in mice,we verified that knockout of TRIM54 can limit the replication of the virus in Tg-PEM and reduce the potent antigen-presenting ability of Tg-PEM.The proliferation of antiviral-specific CD8~+effector T cells induced the resistance of Tg mice to chronic infection and reinfection in vivo and in vitro.To further explore the differential expression of genes of WT-PEM and Tg-PEM after virus infection,and the effect of TRIM54 knockout in Tg-PEM,we performed transcriptome sequencing on these three groups of macrophages.The results showed that virus-infected Tg-PEM can secrete more cytokines that promote antiviral immunity and reduce the transcription of intracellular antiviral protein genes.It can also increase the expression of antigen presentation-related proteins and activated immune checkpoint molecules so that it can produce a stronger antiviral adaptive immune response.The knockout of TRIM54 can largely inhibit this function,making the phenotype and function of TRIM54 knockout Tg-PEM more similar to WT-PEM.Studying how hFcγRⅡa-mediate the increasing of viral replication and its molecular mechanism,helps us understand the ADE.It’s also helpful for us to design vaccines and antibody-based viral drugs.