The Design And Anti-inflammatory Effect Evaluation Of Hyaluronan-based Dexamethasone And MTOR SiRNA Co-delivery Nanosystem

Accompanied by overproduction of oxidants and reduction of pH,inflammation is closely related to many diseases such as cancer,atherosclerosis,and asthma.Currently,glucocorticoids and non-steroidal anti-inflammatory drugs are mainly used in the treatment of inflammation.Glucocorticoids represented by dexamethasone are widely used in the treatment of various types of inflammation due to their high efficiency and strong anti-inflammatory effect.However,long-term use of large doses of these drugs will lead to many adverse reactions,such as peptic ulcer,kirschner's syndrome,immunosuppression which can induce or even aggravate infection.Autophagy is an evolutionarily conserved process in eukaryotes which involves material turnover of the cell with the lysosomal degradation of cytoplasmic organelles or cytosolic components.In recent years,the potential regulative role of autophagy pathway and/or related proteins in inflammation attracts extensive attention and is being actively investigated.It was reported that activation of mTOR was evident in LPS-stimulated monocytes,and by inhibiting mTOR signal pathway and enhancing autophagy,rapamycin could reduce LPS-induced inflammatory response and oxidative stress.It is supposed that inhibiting mTOR may contribute to anti-inflammation.Small interfering RNA(siRNA)is a double-stranded RNA with about 21 nucleotides.It can specifically identify and degrade the target mRNA and silence the expression of homologous genes.Specificity and high efficiency make it a hotspot in the field of modern biology and medicine,but the lack of suitable carriers restricts its use seriously.The purpose of this study was to explore the potential anti-inflammatory effect of targeted gene knockout of autophagy inhibitory gene-mTOR and to further study the synergistic anti-inflammatory effect of dexamethasone and mTOR targeted siRNA(simTOR).So with DMT-MM catalyzing,we synthesized a hyaluronan-based ROS-sensitive polymer which was expected to release loaded chemical drugs-dexamethasone in inflammatory environment and further developed a stable and nontoxic co-delivery nanosystem of siRNA and chemotherapeutic agents through one-step nanoprecipitation.Physicochemical property studies revealed that the nanoparticles had compact and spherical morphology with a narrow size distribution.In addition,these particles had good stability and could protect siRNA from degradation by RNase.The in vitro transfection study of this nanosystem revealed improved intracellular accumulation of siRNA and excellent gene silencing efficacy comparable to that of conventional cationic liposome.Moreover,the mRNA expressions of inflammatory cytokines were remarkably decreased by our nanosystem and the differences were significant compared with those of mTOR gene silencing or dexamethasone treated alone.This study innovatively realized the codelivery of dexamethasone,a representative of corticosteroids,and the siRNA targeting autophagy suppressive gene,mTOR,through the new formulated hyaluronan-based nanosystem and the considerable anti-inflammation efficacy was confirmed,revealing a promising combined therapeutic strategy for enhanced anti-inflammatory therapy.