Upregulation Of MHC-Ⅰ Via Nanoparticle-Mediated Autophagy Inhibition For Enhanced Immunotherapy Effect Of Osteosarcoma

Background: Immune infiltration and immune recognition are interdependent processes,which are the key to achieving high-efficiency immunotherapy.In recent years,many studies have focused on increasing the infiltration of T cells in the tumor microenvironment.For example,the chemotherapeutic drug oxaliplatin(OXA)could induce immunogenic cell death(ICD)to promote T cell infiltration.However,studies on enhancing immune recognition are still poor.The recent study has shown that tumor cells can selectively degrade the key molecule for immune recognition,the major histocompatibility complex I(MHC-Ⅰ),through NBR1-mediated autophagy to inhibit immune recognition for immune escape.Purposes: To study the relationship between the expression level of MHC-Ⅰ molecule and the survival rates of patients with osteosarcoma(OS),and the effect of regulating the level of autophagy on the expression of MHC-Ⅰ to seek its potential as a synergistic therapeutic target.A safe and efficient nanoparticle-based drug delivery system was sought to co-deliver OXA and the autophagy inhibitor chloroquine(CQ)to maximize the effect of immunotherapy by synergistically increasing immune infiltration and immune recognition.Methods: Firstly,we analyzed the MHC-Ⅰ expression level and survival rates of 88 OS patients from the TCGA database.The effect of CQ on MHC-Ⅰ expression and antitumor effect of OXA in cell lines were verified.Then,we successfully prepared an acid-sensitive nanoparticlebased drug delivery system(NP2)to encapsulate the tetravalent OXA prodrug Pt(IV)and the autophagy inhibitor CQ.NP2 was characterized by transmission electron microscopy(TEM)and dynamic light scattering(DLS).Next,we verified the in vitro antitumor effect of NP2 and the synergistic effect of enhancing immune infiltration and recognition in tumor cells.Next,we verified the in vivo targeted performance,in vivo antitumor effect and impact on the immune microenvironment on the K7M2 orthotopic OS mouse model of NP2.Finally,we combined NP2 with αPD-L1 antibody,the immune checkpoint blocker,to further verify its anti-tumor effect and anti-tumor immunity.Results:(1)The expression level of MHC-Ⅰ was significantly correlated with the survival rates of OS patients.Specifically,the higher MHC-Ⅰ expression level corresponds to the better the survival rate of OS patients(p < 0.05).(2)CQ can significantly increase the expression of MHC-Ⅰ in tumor cells and enhance the anti-tumor effect of OXA.(3)The prepared nanoparticles NP2 are spherical around 149 nm and degrade rapidly under weakly acidic(p H = 5.7)conditions.(4)NP2 showed strong antitumor effect in vitro and in vivo with good biosafety.(5)On the one hand,NP2 can induce the ICD effect to recruit T cell infiltration at the tumor site to improve immune infiltration;on the other hand,NP2 can increase the expression of MHC-Ⅰ on the surface of tumor cells by inhibiting autophagy to enhance immune recognition.The combination increased the maturation of DC cells and the proportion of CTL cells.(6)The combination of NP2 and αPD-L1 showed stronger anti-tumor effect and anti-tumor immunity.Conclusion: Increasing the expression of MHC-Ⅰ is an effective treatment method for OS.To the end,we successfully designed and prepared a nanoparticle-based drug delivery system that can induce ICD effect and inhibit autophagy simultaneously,by synergistically enhancing immune infiltration and immune recognition for enhanced anti-tumor immunity.Further,the combination with immune checkpoint blockade therapy achieved the better therapeutic effects.