Blockade of neutrophil recruitment to tumor sites based on sialic acid-modified nanoplatforms enhances the efficacy of checkpoint blockade immunotherapy

Checkpoint inhibitors are designed to rejuvenate depleted or suppressed T cells in the tumor microenvironment,relying on the immune system to control and kill tumors.However,accumulating evidence indicates that tumor-infiltrating neutrophils impede the proliferation and activation of T cells and determine the resistance to checkpoint blockade and chemotherapy.In this study,sialic acid ligand-modified colchicine derivative phospholipid complexes specifically targeted tumor-associated neutrophils in the peripheral blood,blocked neutrophil accumulation in tumors,and attenuated the inhibitory effect of infiltrating neutrophils on T cells.Neutrophil blocking therapy enhanced the immunotherapy effect of the PD-L1 antibody in S180 advanced tumors and 4T1 breast cancer.Our study found that PD-L1 antibody monotherapy increased the tumor infiltration of immunosuppressive neutrophils.Combination therapy with neutrophil blocking can greatly reduce tumor-infiltrating neutrophils and increase the proliferation of cytotoxic CD8^(+) T lymphocytes in the tumor.The combination therapy significantly improved the survival rate of mice with advanced S180 tumors and increased the sensitivity of immune checkpoint inhibitors to 4T1 cold tumors.

Progress involving new techniques for liposome preparation

The article presents a review of new techniques being used for the preparation of liposomes.A total of 28 publications were examined.In addition to the theories,characteristics and problems associated with traditional methods,the advantages and drawbacks of the latest techniques were reviewed.In the light of developments in many relevant areas,a variety of new techniques are being used for liposome preparation and each of these new technique has particular advantages over conventional preparation methods.However,there are still some problems associated with these new techniques that could hinder their applications and further improvements are needed.Generally speaking,due to the introduction of these latest techniques,liposome preparation is now an improved procedure.These applications promote not only advances in liposome research but also the methods for their production on an industrial scale.

Phyto-phospholipid complexes(phytosomes): A novel strategy to improve the bioavailability of active constituents

Although active constituents extracted from plants show robust in vitro pharmacological effects, low in vivo absorption greatly limits the widespread application of these compounds. A strategy of using phyto-phospholipid complexes represents a promising approach to increase the oral bioavailability of active constituents, which is consist of ‘‘label-friendly'phospholipids and active constituents. Hydrogen bond interactions between active constituents and phospholipids enable phospholipid complexes as an integral part. This review provides an update on four important issues related to phyto-phospholipid complexes: active constituents, phospholipids, solvents, and stoichiometric ratios. We also discuss recent progress in research on the preparation, characterization, structural verification, and increased bioavailability of phyto-phospholipid complexes.

Preparation and toxicity evaluation of a novel nattokinase-tauroursodeoxycholate complex

Nattokinase(NK), which has been identified as a potent fibrinolytic protease, has remarkable potential in treatment of thrombolysis, and even has the ability to ameliorate chronic vein thrombosis. To reduce the hemorrhagic risk from an intravenous injection of NK,nattokinase-tauroursodeoxycholate(NK-TUDCA) complex was prepared at different pH values and with different ratios of NK and TUDCA. When assessing survival time, survival state,tail injury, and the body weight of mice, it was found that the NK-TUDCA complex(NK: 10 k IU/ml; TUDCA: 10 mg/ml; pH 5.0) had a lower toxicity when administered at an NK dosage of 130 kIU/kg in the acute toxicity test and 13 kIU/kg in the repeated low-dose challenge. From the results of the in vitro thrombolytic test and characterization of NKTUDCA, we speculated that the delayed release of NK-TUDCA might be the main cause of toxicity reduction by the complex. This study described the preparation of an NK complex with low toxicity following intravenous administration, which could be utilized for further clinical study of NK.

The effect of monosialylganglioside mix modifying the PEGylated liposomal epirubicin on the accelerated blood clearance phenomenon

PEGylated liposomes are potential candidates to improve the pharmacokinetic characteristics of encapsulated drugs, to extend their circulation half-life and facilitate their passive accumulation at tumour sites. However, PEG-modified liposomes can induce accelerated blood clearance(ABC) upon repeated administration, and the extent of ABC phenomenon on the cytotoxic drugs-containing PEGylated liposomes is related to the dose of the cytotoxic drugs.In this study, EPI served as a model cytotoxic drug, a hydrophilic surfactant molecule,monosialylganglioside(GM1) was chosen and modified on the liposomes together with PEG.It was shown that upon mixed modification, when GM1 contents reached 10% or 15% mol,the ABC phenomenon of the PEGylated liposomal EPI significantly reduced. We also found that GM1 played an important role in abrogating the ABC phenomenon in both the induction phase and the effectuation phase. The results suggested that GM1 incorporation unfortunately did not avoid occurrence of ABC phenomenon completely, but GM1 modification on PEGylated liposomes may provide a significant improvement in clinical practice of PEGylated liposomes. Further study must be necessary.

Effects of complement inhibition on the ABC phenomenon in rats

Researchers reported that intravenously injected PEGylated colloidal drug carriers lose their long-circulating characteristic and accumulated extensively in liver when they are administrated twice in the same animal with certain intervals. This phenomenon was referred to as the 'accelerated blood clearance(ABC) phenomenon'. Some former studies had found that complement-mediated phagocytosis, activated by antigen–antibody complex, was responsible for inducing the phenomenon. According to the theory, we have used cobra venom factor to deplete complement in vivo and to investigate the effect of complement inhibition on the ABC phenomenon. Rats were administered by injection of cobra venom factor solution to build up the model of complement exhaustion/inhibition, and the effect of the inhibition of complement on ABC phenomenon was carried out. It seemed that inhibition of complement didn’t affect the pharmacokinetic of the first infection. By contrast, in rats of which complement had been depleted, the second dose of PEGylated nanoemulsions showed enhanced circulation time compared with normal rats in a complement inhibition-independent manner, but the ABC phenomenon was not completely eliminated. It indicated that complement inhibition could certainly weaken the accelerated clearance;meanwhile, there were other factors causing the ABC effect.These findings provide novel insights into the attenuating of ABC phenomenon and lay foundation for further study of immune mechanism.

Effect of Kupffer cells depletion on ABC phenomenon induced by Kupffer cells-targeted liposomes

Accelerated blood clearance(ABC) phenomenon is common in many PEGylated nanocarriers, whose mechanism has not been completely elucidated yet. In this study, the correlation between Kupffer cells(KCs) and ABC phenomenon has been studied by KCs-targeted liposomes inducing ABC phenomenon and KCs depletion. In other words, the 4-aminophenyl-α-D-mannopyranoside(APM) lipid derivative DSPE-PEG 2000-APM(DPM), and 4-aminophenyl-β-L-fucopyranoside(APF) lipid derivative DSPE-PEG 2000-APF(DPF) were conjugated and modified on alendronate sodium(AD) liposomes to specifically target and deplete KCs. The dualligand modified PEGylated liposomes(MFPL) showed stronger ability to damage KCs in vitro and in vivo, which also could indirectly illustrate that dual-ligand modification could better target KCs. Besides, the hepatic biodistribution and pharmacokinetics could directly prove that MFPL had a stronger targeting ability to KCs. In addition, in depletion rats, plasma concentration and splenic biodistribution of MFPL and PEGylated liposomes(PL) were significantly elevated and hepatic biodistribution was significantly reduced, which demonstrated that KCs played an important role on elimination of nanoparticles. What’s more, ABC phenomenon of the secondary injection of PL was stronger in KCs depletion rats than that in normal rats, which indicated that depletion of KCs prolonged the circulation of PL in the first injection repeatedly stimulating B-cells in the marginal region of the spleen and causing it to secrete more IgM antibodies. This could also illustrate that anti-PEG IgM takes up a major station compared with KCs. Most important of all, KCs-targeted liposomes could induce a stronger ABC phenomenon than PL in normal rats, which declared that based on the same IgM concentration, the more the KCs were stimulated, the stronger ABC phenomenon was induced. However, in depletion rats, this difference of ABC phenomenon between PL and MFPL could no more exist, further demonstrating that KCs could participate and play a certain role in the ABC phenomenon.

The accelerated blood clearance phenomenon of PEGylated nanoemulsion upon cross administration with nanoemulsions modified with polyglycerin

For investigating the accelerated blood clearance(ABC) phenomenon of polyglycerin modified nanoemulsions upon cross administration with polyethylene glycol(PEG) covered nanoemulsion, we used the 1,2-distea-royl-sn-glycero-3-phosphoethanolamine-npolyglycerine-610 and the 1,2-distearoyl-n-glycero-3-phosphoethanolamine-n-[methoxy(polyethylene glycol)-2000] as modify materials, the dialkylcarbocyanines as fluorescence indicator. Exhausted macrophages rat model was established and new material containing polycarboxyl structure was synthesized. The microplate reader and the in vivo optical imaging system were applied to measure the concentration of nanoemulsions in tissues.The results show that the first dose of polyglycerin modified nanoemulsion can induce the ABC phenomenon of the second dose of PEGylated nanoemulsion. With the increase in the amount of the surface polyglycerin, the extent of the ABC phenomenon decreases. Liver accumulation has positive relationship with the ABC phenomenon. Furthermore, kupffer cells in liver can get more immune information from polyhydroxy structure than polycarboxyl group in the modify compound. The results of our work imply that the polycarboxyl structure has advantages to eliminate the ABC phenomenon.

Mixed PEGylated surfactant modifying system decrease the accelerated blood clearance phenomenon of nanoemulsions in rats

The accelerated blood clearance(ABC) phenomenon which is induced by repeated injection of poly(ethylene glycol)(PEG)-coated colloidal carriers gives clinical challenge to the promising drug delivery system. It is necessary to decrease this unexpected immunological response.A novel 4-arm poly(ethylene glycol-5000)4-cholesteryl methyl amide(4-arm PEG5000-CHMA)has been synthesized. The structure of 4-arm PEG5000-CHMA was confirmed by IR and 1H-NMR spectrum. The pharmacokinetics of the tocopheryl nicotinate(TN)-loaded nanoemulsions modified with 4-arm PEG5000-CHMA or/and 1, 2-distearoyl-Sn-glycero-3-phosphoethanolamine-n-[methoxy(poly-ethyleneglycol)-2000](mPEG2000-DSPE) have been studied. Furthermore, the ABC phenomenon has been detailed investigated in rats by TN-loaded nanoemulsions modified with 4-arm PEG5000-CHMA and mPEG2000-DSPE(CPNE). The plasma levels of TN and anti-PEG IgM antibody were determined by HPLC and ELISA, respectively.The circulation time of the CPNEs were comparable to the mPEG2000-DSPE coated nanoemulsions. Moreover, the ABC phenomenon can be decreased by CPNEs. This study designs a method to decrease the ABC phenomenon and develops a clinical promising nanoemulsion for therapeutic or imaging purpose.

Sialic acid-mediated photochemotherapy enhances infiltration of CD8^(+)T cells from tumor-draining lymph nodes into tumors of immunosenescent mice

Immunoscenescence plays a key role in the initiation and development of tumors.Furthermore,immunoscenescence also impacts drug delivery and cancer therapeutic efficacy.To reduce the impact of immunosenescence on anti-tumor therapy,this experimental plan aimed to use neutrophils with tumor tropism properties to deliver sialic acid(SA)-modified liposomes into the tumor,kill tumor cells via SA-mediated photochemotherapy,enhance infiltration of neutrophils into the tumor,induce immunogenic death of tumor cells with chemotherapy,enhance infiltration of CD8^(+)T cells into the tumordraining lymph nodes and tumors of immunosenescent mice,and achieve SA-mediated photochemotherapy.We found that CD8^(+)T cell and neutrophil levels in 16-month-old mice were significantly lower than those in 2-and 8-month-old mice;16-month-old mice exhibited immunosenescence.The anti-tumor efficacy of SA-mediated non-photochemotherapy declined in 16-month-old mice,and tumors recurred after scabbing.SA-mediated photochemotherapy enhanced tumor infiltration by CD8^(+)T cells and neutrophils,induced crusting and regression of tumors in 8-month-old mice,inhibited metastasis and recurrence of tumors and eliminated the immunosenescence-induced decline in antitumor therapeutic efficacy in 16-month-old mice via the light-heat-chemical-immunity conversion.

Compression Algorithm for Implicit 3D B-Spline Solids

Due to advantages in solid modeling with complex geometry and its ideal suitability for 3D printing,the implicit representation has been widely used in recent years.The demand for free-form shapes makes the implicit tensor-product B-spline representation attract more and more attention.However,it is an important challenge to deal with the storage and transmission requirements of enormous coefficient ten-sor.In this paper,we propose a new compression framework for coefficient tensors of implicit 3D tensor-product B-spline solids.The proposed compression algorithm consists of four steps,i.e.,preprocessing,block splitting,using a lifting-based 3D discrete wavelet transform,and coding with 3D set partitioning in hierarchical trees algorithm.Finally,we manage to lessen the criticism of the implicit tensor-product B-spline representation of surface for its redundancy store of 3D coefficient tensor.Experimental results show that the proposed compression framework not only achieves satisfactory reconstruction quality and considerable compression ratios,but also sup-ports progressive transmissions and random access by employing patch-wise coding strategy.

Diamond Inclusion Reconstruction

In this paper,we make an improvement on the conventional visual hull reconstruction method that runs on a single consumer graphics card.The target application is a high-precision diamond inclusion reconstruction system.One major contribution of this paper is an evaluation system of voxels for high-precision reconstruction.In contrast to existing approaches,it allows us to reconstruct the thin structure of the diamond inclusion.Based on this,we obtain a significant improvement in reconstruction precision,especially for thin inclusion.