Reverse immune suppressive microenvironment in tumor draining lymph nodes to enhance anti-PD1 immunotherapy via nanovaccine complexed microneedle

The maturation of dendritic cells(DCs)and infiltration effector T cells in tumor-draining lymph node(tdLN)and tumor tissue are crucial for immunotherapy.Despite constructive progresses have been made with anti-programmed death-1(anti-PD1)checkpoint blockade for immunotherapy,the efficacy of PD1/PD-L1 therapy deserves to be improved.Here,we constructed a novel transfersomes based nanovaccine complexed microneedles to enhance anti-PD1 immunotherapy via transdermal immunization for skin tumor therapy.Transfersomes were functionalized with DCs targeting moietyαCD40,co-encapsulated with antigens and adjuvant poly I:C.Moreover,transdermal administration promoted accumulation in tumor-draining lymph nodes(tdLN),which could facilitate cellular uptake,activate DCs maturation and enhance Th1 immune responses.Using a mouse melanoma model,combined therapy of such nanovaccine complexed microneedles with pembrolizumab(αPD1)was able to enhance cytotoxic T lymphocytes activation,promote infiltration and reduce regulatory T cells frequency in tdLN and tumor tissues,which achieved reversion of the immunosuppressive microenvironment into immune activation.This study highlighted the potential of transfersomes based nanovaccines complexed microneedles as an attractive platform for tumor immunotherapy.

Precise quantification of the antibacterial activity of chitosan by NB medium neutralizer

In the present research,nutrient broth(NB)medium was identified to be able to neutralize the antibacterial activity of chitosan and its derivatives.Therefore,an improved test method independent of NB medium was proposed to precisely quantify the antibacterial effectiveness and efficiency of chitosan.The minimum bactericidal concentration(MBC)of chitosan was 60μg m L^(-1) against S.aureus and E.coli,and 0.01%(w/v)chitosan could kill 100%of bacteria within 3 min.From another point of view,the neutralizing efficiency of NB could be tripled by adding 25 g L^(-1) of sodium chloride.Then the neutralizing mechanism of NB medium was ascribed to flocculation between chitosan and protein.Adding extra sodium chloride could significantly reduce the size of floccules,and smaller floccules would lose the ability of binding with bacteria directly,showing higher neutralizing rate on the macro scale.