Preparation Of EMO/PSM Nanosystem And Evaluation Of Its Therapeutic Efficacy On Experimental UC

Background: Ulcerative colitis(UC)is a chronic refractory disease with complex pathogenesis,which is closely related to the mucosa-barrier destruction,gut dysbacteriosis,and immune disorders.Emodin(EMO)is a natural active component of traditional Chinese medicine(TCM),such as Rheum palmatum L.,Polygonum cuspidatum Willd.ex Spreng.and Polygonum multiflorum Thunb.(Polygonaceae),which shows multiple pharmacological effects and is a potential candidate drug for UC treatment.However,EMO appears low water-solubility and high first-pass metabolism,leading to low concentration in inflammatory tissue.Long-term or large doses use of EMO for expected treatment effect tends to cause multiple adverse reactions,which seriously restrict its anti-UC effect and clinical application.Purpose: A colon-targeted nano-system of EMO was constructed using multifunctional biomedical materials,to evaluate its anti-colitis and mucosa reconstruction effect.Methods: EMO nanoparticles(NPs)were prepared by improved emulsificationsolvent evaporation technology,and the formulation of EMO-loaded poly(DL-lactideco-glycolide)(PLGA)/Eudragit(?) S100/montmorillonite(MMT)(EMO/PSM NPs)was optimized by orthogonal test and single factor test design.The physical and chemical properties of NPs,such as morphology,particle size,Zeta potential,drug loading(DL)and encapsulation efficiency(EE)were characterized.The colon-targeted delivery behavior of NPs was evaluated by in vitro drug release test and in vivo,in vitro and confocal imaging.The acute UC model was induced by sodium dextran sulfate(DSS)in mice,The anti-colitis efficacy of NPs was evaluated by weight,disease activity index(DAI),colon length,histological changes and UC biomarker detection;The cell transwell model in vitro was combined with the results of serum zonulin level,tight junction(TJs)and MUC2 gene expression was conducted to study the reconstruction effect of EMO/PSM NPs on the damaged mucosal barrier;The safety of EMO/PSM NPs in UC therapy was evaluated by the liver and kidney sections and liver indexes.Results: The average hydration particle size of EMO/PSM NPs was 234.8 nm with a Zeta potential of-31.36 ± 3.25 m V.The shell-core structure could effectively avoid the burst release of EMO in the upper gastrointestinal tract(GIT)(< 4%)and boost the retention of NPs in the colonic mucosa.The therapeutic efficacy of EMO/PSM NPs was better than that of free EMO by significantly improved DAI,alleviated histological damage of colon,and positively regulated biochemical indexes of UC,such as myeloperoxidase(MPO),nitric oxide(NO)and glutathione(GSH).EMO/PSM NPs can effectively inhibit up-regulated inflammatory factors at m RNA and protein levels,such as induced nitric oxide synthase(i NOS),cyclooxygenase-2(COX-2),TNF-α and IL-1 β;EMO/PSM NPs significantly reduced the leakage of FITC-dextran,decreased the level of serum zonulin(p < 0.001),and up-regulated the m RNA expression of TJsrelated proteins and MUC2,suggesting that the anti-UC effect of EMO/PSM NPs is related to the promoted regeneration of mucosal barrier.In addition,free EMO(20 mg/kg)showed watery degeneration of hepatocytes and up-regulation of liver serological indexes(AST,ALT)in UC treatment,while NPs eliminated the liver injury caused under excessive immune inflammation in UC,indicating the safety of EMO/PSM NPs in anti-UC treatment.Conclusion: The EMO/PSM NPs constructed here could effectively target the colon lesions to release drugs,showed reconstructing effect on the colon mucosal barrier,and effectively enhanced the therapeutic effect of EMO on UC mice.The nano-technology also avoided the liver toxicity of EMO caused by collective susceptibility in the state of excessive inflammation.The results of this study also suggest that PSM NPs is an excellent carrier for oral colon-targeted therapy,which can simultaneously achieve increased therapeutic efficacy and reduced side-effects of loaded drugs.