Chitosan-based Polymeric Carriers For Delivery Of Therapeutic Proteins

Drug delivery is a bridge between drug discovery and drug development.Appropriate drug delivery methods can eventually help drugs to achieve their value in clinical practice.In recent years,biological drugs,especially those protein drugs with large molecular weights,have achieved a series of major breakthroughs.However,the delivery of biological macromolecular drugs is still mainly by injections.Since these macromolecular therapeutics such as proteins have large molecular sizes,complex structures,they are fragile in complex physiological environments and could hardly penetrate various biological barriers such as mucosal barriers and skin barriers.The development of topical or oral delivery methods for proteins drugs remains to be a great challenge.Considering the above challenges,in this doctoral dissertation,we developed several platforms based on chitosan or modified chitosan for pulmonary,topical or oral delivery of macromolecular drugs.Firstly,we found that chitosan could self-assemble with therapeutic proteins to form nanocomplexes for inhalation,and achieved pulmonary antibody delivery and synergistic immunotherapy.Then,we further optimized the carrier by fluorocarbon modulation,and realized effective oral delivery efficacy of immune checkpoint antibodies.In addition to the mucosal barrier,the platform can effectively penetrate the skin barrier to achieve a broader application scenario.The main contents are summarized as follows:(1)We have developed an inhaled chitosan-immunotherapeutic antibody complex for immunotherapy for lung cancer treatment.In this system,chitosan is used as a delivery vector of anti-programmed cell death protein ligand 1(aPD-L1)to achieve efficient transmucosal delivery.In addition,we have found that chitosan can trigger immune responses by activating cyclic-di-GMP-AMP synthase(cGAS)-stimulator of interferon genes(STING)pathway,and improve infiltration of a variety of immune cells,especially CD8+ T cells in tumor lesions,and finally extend the survival of mice.Therefore,this work proposes a unique aerosol inhalation delivery method for immune checkpoint antibodies,which is expected to topically treat pulmonary metastasis with high efficacy and low systemic toxicity.(2)We developed a fluorocarbon-modified chitosan(FCS)as an innovative transmucosal carrier for effective oral delivery of immune checkpoint antibodies.FCS could promote the transmucosal delivery of the protein drugs by inducing temporary rearrangement of tight junctions between intestinal epithelial cells.Using this vector,we realized oral systemic delivery of antibody drugs.Under the dose of five times the conventional intravenous delivery,the FCS-based oral delivery of anti-programed cell dealth 1(anti-PD1)could achieve therapeutic effects comparable to that achieved with i.v.injection,with significantly reduced immune related side effects(3)We further applied such strategy in the oral delivery of insulin.In our design,insulin is mixed with FCS to form nanoparticles,lyophilized with appropriate excipients,and then filled into enteric capsules for oral administration.The effective oral delivery of insulin could lead to relatively sustained normal blood glucose in both diabetic mice and pigs.Oral insulin could act like the metabolism of endogenous insulin in vivo,and could improve patient compliance.In addition,we also proved that this FCS-based strategy may be a universal platform that could combine with various therapeutic proteins,and this strategy could bring new opportunities for the oral delivery of protein drugs.Insipired by the successful transmucosal delivery of FCS-based platforms,we further explored its application in transdermal delivery.FCS-insulin complex was therefore encapsulated in hydrogel as a patch for diabetes treatment.This work not only shows the potential of FCS as a transdermal delivery vector,but also shows its broad application prospects.Such carrier can be combined with a variety of macromolecular drugs,which is expected to develop a variety of products and even achieve a broader development in the fields of vaccines or cosmetology.In summary,this doctoral dissertation has developed a series of chitosan-based noninvasive delivery platforms of therapeutic proteins.These nanocomplex could facilitate the transmucosal or transdermal delivery of various proteins including antibodies and insulin for immunotherapy or diabetes treatment strategies.We systematically studied the effectiveness,safety and mechanism of chitosan-based platforms and explored its potential to deliver various macromolecular drugs.