The Application Of Inflammation-responsive Polymers Nanomedicines For Treatment Of Arthritis

Arthritis is a common and multiple-occurring disease in clinic.The patients with the early stage of arthritis will show the symptoms like joint swelling and activity limitation,while the late stage patients may face the problems of joint destruction,disability and teratogenicity.Based on etiology,pathogenetic information and clinical manifestation,the classification of arthritis have been group into rheumatoid arthritis,osteoarthritis,spondylitis and other dozens of types.Among the classification of arthritis,rheumatoid arthritis?RA?and osteoarthritis?OA?have higher incidence.Although the precise of etiology of various types of arthritis remains elusive,the evidence of immunopathogenic pathways have been accumulated over decades.As the central effectors of arthritis,the macrophages will express pattern recognition receptors?PRRs?on the cell membrane surface,release a large amount of proinflammatory cytokines,inflammatory mediators,change the local microenvironment and trigger a series of biochemical reactions,leading to the progression of synovial hyperplasia,bone and articular cartilage damage.Currently,the common drugs for treatment of arthritis was limited by low drug efficiency,short half-life,the poor targeting efficiency and severe toxicity.Compared to the conventional chemotherapeutic agents,the intelligent nano-scaled polymeric drug delivery systems for arthritis therapy have demonstrated many advantages,including enhanced specific targeting of inflammtory tissues,improved drug efficiency,prolonged circulation time,decreased side effects etc.Based on the characteristics of the activated macrophages expressed PRRs and the inflammatory microenvironment,this dissertation has focused on the development of nanoparticles?NPs?as inflammtion-responsive polymers via covalent or noncovalent interaction between drug and carrier.Due to the amphipathic polymers,the spontaneous formation of the NPs with uniform size was found to occur in aqueous medium.The NPs was applied in CIA and MIA model.The main content and conclusions of this dissertation are summarized below:?1?Based on the pathological and physiological characteristics of RA,a novel ROS-responsive NPs was designed and prepared.It is composed of a novel poly?ethyleneglycol?-b-?poly??-propargyl-L-glutamate?-g-propanethiol??mPEG-b-?PPLG-PTL??via noncovalent loaded common anti-rheumatoid durg,methotrexate?MTX?.The thioether group in mPEG-b-?PPLG-PTL?have excellent antioxidant properties and ROS-responsive characteristics,which can scavenge ROS in inflammatory microenvironment of RA,and then suppressing M1 polarization.The efficacy of mPEG-b-?PPLG-PTL?via noncovalent loaded MTX enhance synergisticly the ability that inhibit the viability of the macrophages and reduce the expression of inflammatory cytokines.The distribution and therapeutic effect of the novel antioxidant mPEG-b-?PPLG-PTL?-MTX NPs in vivo were evaluated using the CIA model.At first,Rapid and efficient side-chain functionalization of polypeptide-based block copolymer was achieved via the combination of ring-opening polymerization of a clickable monomer of?-propargyl-L-glutamate-N-carboxyanhydride?PLG-NCA?and subsequent thiol-yne click chemistry.The polymer formed uniform NPs by spontaneous assembled in aqueous solution.The drug showed a slow release from the drug-loaded mPEG-b-?PPLG-PTL?-MTX NPs at physiological conditions,but significantly accelerated release under the H₂O₂ conditions.The cellular uptake and inhibition studies suggested that mPEG-b-?PPLG-PTL?-MTX NPs were taken up by RAW 264.7 cells via endocytosis,with a slightly slower cellular internalization and proportionable inhibition of viability compared with free MTX,and also reduce the expression of inflammatory cytokines and drive the polarization of macrophages.Moreover,mechanism studies proved that the superior therapeutic effect of mPEG-b-?PPLG-PTL?-MTX NPs was attributed to their high ROS scavenging and anti-inflammatory abilities.Thus,mPEG-b-?PPLG-PTL?-MTX NPs exhibited the enhanced therapeutic efficacy,increased accumulation in inflammatory site and reduced systemic toxicity in CIA model compared with free MTX.It can also reduce inflammatory macrophages infiltration,inhibit the expression of pro-inflammatory cytokines,relieve bone and cartilage destruction,and slow the inflammatory process of RA.?2?Combined with the characteristics of macrophages in the immunopathological mechanism of OA,the design and preparation of dextran sulfate-triamcinolone acetonide conjugate?DS-TA?NPs,for treatment of OA via specifically targeting scavenger receptor class A?SR-A?on activated macrophages.The excellent targeting specificity of DS-TA NPs to SR-A was verified by flow cytometry?FCM?,confocal laser scanning microscopy?CLSM?,and the inhibitory effect on the viability of activated macrophages?RAW 264.7 cells?and expression of proinflammatory cytokines was evaluated.In vivo,intra-articular injection of DS-TA NPs improved the regeneration of collagen and glycosaminoglycans,thereby effectively alleviating the structural damage of joint cartilage,which was confirmed by histopathology.Additionally,DS-TA NPs decreased the expression of proinflammatory cytokines.Overall,DS-TA NPs are a type of potential targeting therapeutic nanomedicine for the treatment of OA.The above results are expected to provide important evidence for designing NPs via targeting for PRRs on the activated macrophages surface and its inflammtory microenvironment that have success for reducing inflammatory macrophages infiltration,inhibiting the expression of pro-inflammatory cytokines,relieving bone and cartilage destruction,and slowing the inflammatory process of arthritis.Furthermore,they also provide new strategies for precisely intelligent targeted NPs and combination of drug therapy for the treatment of arthritis.