Catalytic Glycosylation for Minimally Protected Donors and Acceptors.

Oligosaccharides have myriad functions throughout biology.1,2 To investigate these functions requires multi-step chemical synthesis of these structurally complex molecules. With a dense concentration of stereocentres and hydroxyl groups, oligosaccharide assembly through O-glycosylation requires simultaneous control of site-, stereo-, and chemoselectivities3,4. Chemists have traditionally relied on protecting group manipulations for this purpose,5-8 adding a lot of synthetic work. Here, we report a glycosylation platform that enables selective coupling between unprotected or minimally protected donor and acceptor sugars, producing 1,2-cis-O-glycosides in a catalyst-controlled, site-selective manner. Radical-based activation9 of allyl glycosyl sulfones forms glycosyl bromides. A designed aminoboronic acid catalysts bring this reactive intermediate close to an acceptor through a network of noncovalent hydrogen bonding and reversible covalent B-O bonding interactions, allowing precise glycosyl transfer. The site of glycosylation can be switched with different aminoboronic acid catalysts by affecting their interaction modes with substrates. The method accommodates a wide range of sugar types, amenable to preparing naturally occurring sugar chains and pentasaccharides containing 11 free hydroxyls. Experimental and computational studies provide insights into the origin of selectivity outcomes.

Sialic Acid Conjugate-Modified Cationic Liposomal Paclitaxel for Targeted Therapy of Lung Metastasis in Breast Cancer: What a Difference the Cation Content Makes.

Cationic lipids play a pivotal role in developing novel drug delivery systems for diverse biomedical applications, owing to the success of mRNA vaccines against COVID-19 and the Phase III antitumor agent EndoTAG-1. However, the therapeutic potential of these positively charged liposomes is limited by dose-dependent toxicity. While an increased content of cationic lipids in the formulation can enhance the uptake and cytotoxicity toward tumor-associated cells, it is crucial to balance these advantages with the associated toxic side effects. In this work, we synthesized the cationic lipid HC-Y-2 and incorporated it into sialic acid (SA)-modified cationic liposomes loaded with paclitaxel to target tumor-associated immune cells efficiently. The SA-modified cationic liposomes exhibited enhanced binding affinity toward both RAW264.7 cells and 4T1 tumor cells in vitro due to the increased ratios of cationic HC-Y-2 content while effectively inhibiting 4T1 cell lung metastasis in vivo. By leveraging electrostatic forces and ligand-receptor interactions, the SA-modified cationic liposomes specifically target malignant tumor-associated immune cells such as tumor-associated macrophages (TAMs), reduce the proportion of cationic lipids in the formulation, and achieve dual objectives: high cellular uptake and potent antitumor efficacy. These findings highlight the potential advantages of this innovative approach utilizing cationic liposomes.

Sialic acid-modified doxorubicin liposomes target tumor-related immune cells to relieve multiple inhibitions of CD8+ T cells.

In different types of cancer treatments, cancer-specific T cells are required for effective anticancer immunity, which has a central role in cancer immunotherapy. However, due to the multiple inhibitions of CD8+ T cells by tumor-related immune cells, CD8+ T-cell mediated antitumor immunotherapy has not achieved breakthrough progress in the treatment of solid tumors. Receptors for sialic acid (SA) are highly expressed in tumor-associated immune cells, so SA-modified nanoparticles are a drug delivery nanoplatform using tumor-associated immune cells as vehicles. To relieve the multiple inhibitions of CD8+ T cells by tumor-associated immune cells, we prepared SA-modified doxorubicin liposomes (SL-DOX, Scheme 1A). In our study, free SA decreased the toxicity of SL-DOX to tumor-associated immune cells. Compared with common liposomes, SL-DOX could inhibit tumor growth more effectively. It is worth noting that SL-DOX could not only kill tumor-related neutrophils and monocytes to relieve the multiple inhibitions of CD8+ T cells but also induce immunogenic death of tumor cells to promote the infiltration and differentiation of CD8+ T cells (Scheme 1B). Therefore, SL-DOX has potential value for the clinical therapeutic effect of CD8+ T cells mediating anti-tumor immunotherapy.

Photoinduced Site-Selective Aryl C-H Borylation with Electron-Donor-Acceptor Complex Derived from B2Pin2 and Isoquinoline.

Due to boron's metalloid properties, aromatic boron reagents are prevalent synthetic intermediates. The direct borylation of aryl C-H bonds for producing aromatic boron compounds offers an appealing, one-step solution. Despite significant advances in this field, achieving regioselective aryl C-H bond borylation using simple and readily available starting materials still remains a challenge. In this work, we attempted to enhance the reactivity of the electron-donor-acceptor (EDA) complex by selecting different bases to replace the organic base (NEt3) used in our previous research. To our delight, when using NH4HCO3 as the base, we have achieved a mild visible-light-mediated aromatic C-H bond borylation reaction with exceptional regioselectivity (rr > 40:1 to single isomers). Compared with our previous borylation methodologies, this protocol provides a more efficient and broader scope for aryl C-H bond borylation through the use of N-Bromosuccinimide. The protocol's good functional-group tolerance and excellent regioselectivity enable the functionalization of a variety of biologically relevant compounds and novel cascade transformations. Mechanistic experiments and theoretical calculations conducted in this study have indicated that, for certain arenes, the aryl C-H bond borylation might proceed through a new reaction mechanism, which involves the formation of a novel transient EDA complex.

Phosphatidylserine and/or Sialic Acid Modified Liposomes Increase Uptake by Tumor-associated Macrophages and Enhance the Anti-tumor Effect.

DOX liposomes have better therapeutic effects and lower toxic side effects. The targeting ability of liposomes is one of the key factors affecting the therapeutic effect of DOX liposomes. This study developed two types of targeted liposomes. Sialic acid (SA)-modified liposomes were designed to target the highly expressed Siglec-1 receptor on tumor-associated macrophages surface. Phosphatidylserine (PS)-modified liposomes were designed to promote phagocytosis by monocyte-derived macrophages through PS apoptotic signaling. In order to assess and compare the therapeutic potential of different targeted pathways in the context of anti-tumor treatment, we compared four phosphatidylserine membrane materials (DOPS, DSPS, DPPS and DMPS) and found that liposomes prepared using DOPS as material could significantly improve the uptake ability of RAW264.7 cells for DOX liposomes. On this basis, normal DOX liposomes (CL-DOX) and SA-modified DOX liposomes (SAL-DOX), PS-modified DOX liposomes (PS-CL-DOX), SA and PS co-modified DOX liposomes (PS-SAL-DOX) were prepared. The anti-tumor cells function of each liposome on S180 and RAW264.7 in vitro was investigated, and it was found that SA on the surface of liposomes can increase the inhibitory effect. In vivo efficacy results exhibited that SAL-DOX and PS-CL-DOX were superior to other groups in terms of ability to inhibit tumor growth and tumor inhibition index, among which SAL-DOX had the best anti-tumor effect. Moreover, SAL-DOX group mice had high expression of IFN-γ as well as IL-12 factors, which could significantly inhibit mice tumor growth, improve the immune microenvironment of the tumor site, and have excellent targeted delivery potential.

[Effect of Xuming Decoction in Records of Proved Prescriptions, Ancient a nd Modern on cerebral ischemic injury and angiogenesis in rat model of acute cerebral infarction].

This paper aims to explore the effect of Xuming Decoction in the Records of Proved Prescriptions, Ancient and Modern on cerebral ischemic injury and angiogenesis in the rat model of acute cerebral infarction. SD rats were randomized into 6 groups: sham group, model group, low-, medium-, and high-dose(5.13, 10.26, and 20.52 g·kg~(-1), respectively) Xuming Decoction groups, and butylphthalide(0.06 g·kg~(-1)) group. After the successful establishment of the rat model by middle cerebral artery occlusion(MCAO), rats in the sham and model groups were administrated with distilled water and those in other groups with corresponding drugs for 7 consecutive days. After the neurological function was scored, all the rats were sacrificed, and the brain tissue samples were collected. The degree of cerebral ischemic injury was assessed by the neurological deficit score and staining with 2,3,5-triphenyltetrazolium chloride. Hematoxylin-eosin staining was performed to observe the pathological changes in the brain. Transmission electron microscopy was employed to observe the ultrastructures of neurons and microvascular endothelial cells(ECs) on the ischemic side of the brain tissue. Immunofluorescence assay was employed to detect the expression of von Willebrand factor(vWF) and hematopoietic progenitor cell antigen CD34(CD34) in the ischemic brain tissue. Real-time PCR and Western blot were employed to determine the mRNA and protein levels, respectively, of Runt-related transcription factor 1(RUNX1), vascular endothelial growth factor(VEGF), angiopoietin-1(Ang-1), angiopoietin-2(Ang-2), and VEGF receptor 2(VEGFR2) in the ischemic brain tissue. The results showed that compared with the sham group, the model group showed increased neurological deficit score and cerebral infarction area(P<0.01), pathological changes, and damaged ultrastructure of neurons and microvascular ECs in the ischemic brain tissue. Furthermore, the modeling up-regulated the mRNA levels of RUNX1, VEGF, Ang-1, Ang-2, and VEGFR2(P<0.01) and the protein levels of vWF, CD34, RUNX1, VEGF, Ang-1, Ang-2, and VEGFR2(P<0.05 or P<0.01). Compared with the model group, high-dose Xuming Decoction and butylphthalide decreased the neurological deficit score and cerebral infarction area(P<0.01) and alleviated the pathological changes and damage of the ultrastructure of neurons and microvascular ECs in the ischemic brain tissue. Moreover, they up-regulated the mRNA levels of RUNX1, VEGF, Ang-1, Ang-2, and VEGFR2(P<0.01) and the protein levels of vWF, CD34, RUNX1, VEGF, Ang-1, Ang-2, and VEGFR2(P<0.01). The results suggest that Xuming Decoction in the Records of Proved Prescriptions, Ancient and Modern can promote the angiogenesis and collateral circulation establishment to alleviate neurological dysfunction of the ischemic brain tissue in MCAO rats by regulating the RUNX1/VEGF pathway.

PSMC5 regulates microglial polarization and activation in LPS-induced cognitive deficits and motor impairments by interacting with TLR4.

Luteolin is a flavonoid found in high concentrations in celery and green pepper, and acts as a neuroprotectant. PSMC5 (proteasome 26S subunit, ATPase 5) protein levels were reduced after luteolin stimulation in activated microglia. We aimed to determine whether regulating PSMC5 expression could inhibit neuroinflammation, and investigate the underlying mechanisms.BV2 microglia were transfected with siRNA PSMC5 before the addition of LPS (lipopolysaccharide, 1.0 µg/ml) for 24 h in serum free DMEM. A mouse model of LPS-induced cognitive and motor impairment was established to evaluate the neuroprotective effects of shRNA PSMC5. Intracerebroventricular administration of shRNA PSMC5 was commenced 7 days prior to i.p. injection of LPS (750 µg/kg). Treatments and behavioral experiments were performed once daily for 7 consecutive days. Behavioral tests and pathological/biochemical assays were performed to evaluate LPS-induced hippocampal damage. Molecular dynamics simulation was used to confirm the interaction between PSMC5 and TLR4 (Toll-like receptor 4) in LPS-stimulated BV2 microglia. SiRNA PSMC5 inhibited BV2 microglial activation, and suppressed the release of inflammatory factors (IL-1ß, COX-2, PGE2, TNF-α, and iNOS) upon after LPS stimulation in BV2 microglia. LPS increased IκB-α and p65 phosphorylation, which was attenuated by siRNA PSMC5. Behavioral tests and pathological/biochemical assays showed that shRNA PSMC5 attenuated LPS-induced cognitive and motor impairments, and restored synaptic ultrastructure and protein levels in mice. ShRNA PSMC5 reduced pro-inflammatory cytokine (TNF-α, IL-1ß, PGE2, and NO) levels in the serum and brain, and relevant protein factors (iNOS and COX-2) in the brain. Furthermore, shRNA PSMC5 upregulated the anti-inflammatory mediators interleukin IL-4 and IL-10 in the serum and brain, and promoted a pro-inflammation-to-anti-inflammation phenotype shift in microglial polarization. Mechanistically, shRNA PSMC5 significantly alleviated LPS-induced TLR4 expression. The polarization of LPS-induced microglial pro-inflammation phenotype was abolished by TLR4 inhibitor and in the TLR-4-/- mouse, as in shRNA PSMC5 treatment. PSMC5 interacted with TLR4 via the amino sites Glu284, Met139, Leu127, and Phe283. PSMC5 site mutations attenuated neuroinflammation and reduced pro-inflammatory factors by reducing TLR4-related effects, thereby reducing TLR4-mediated MyD88 (myeloid differentiation factor 88)-dependent activation of NF-κB. PSMC5 could be an important therapeutic target for treatment of neurodegenerative diseases involving neuroinflammation-associated cognitive deficits and motor impairments induced by microglial activation.

Targeting Ibrutinib to Tumor-Infiltrating T Cells with a Sialic Acid Conjugate-Modified Phospholipid Complex for Improved Tumor Immunotherapy.

Immune checkpoint blockade (ICB) treatment for the clinical therapy of numerous malignancies has attracted widespread attention in recent years. Despite being a promising treatment option, developing complementary strategies to enhance the proportion of patients benefiting from ICB therapy remains a formidable challenge because of the complexity of the tumor microenvironment. Ibrutinib (IBR), a covalent inhibitor of Bruton's tyrosine kinase (BTK), has been approved as a clinical therapy for numerous B-cell malignancies. IBR also irreversibly inhibits interleukin-2 inducible T cell kinase (ITK), an essential enzyme in Th2-polarized T cells that participates in tumor immunosuppression. Ablation of ITK by IBR can elicit Th1-dominant antitumor immune responses and potentially enhance the efficacy of ICB therapy in solid tumors. However, its poor solubility and rapid clearance in vivo restrict T cell targetability and tumor accumulation by IBR. A sialic acid derivative-modified nanocomplex (SA-GA-OCT@PC) has been reported to improve the efficacy of IBR-mediated combination immunotherapy in solid tumors. In vitro and in vivo experiments showed that SA-GA-OCT@PC effectively accumulated in tumor-infiltrating T cells mediated by Siglec-E and induced Th1-dominant antitumor immune responses. SA-GA-OCT@PC-mediated combination therapy with PD-L1 blockade agents dramatically suppressed tumor growth and inhibited tumor relapse in B16F10 melanoma mouse models. Overall, the combination of the SA-modified nanocomplex platform and PD-L1 blockade offers a treatment opportunity for IBR in solid tumors, providing novel insights for tumor immunotherapy.

Liposomal Doxorubicin: the Sphingomyelin/Cholesterol System Significantly Enhances the Antitumor Efficacy of Doxorubicin.

Doxorubicin (DOX) has a cytotoxic effect on many tumor cells; however, its clinical application is limited owing to its strong side effects. Although Doxil® reduces the cardiotoxicity of free DOX, it has also introduced a new dose-limiting toxicity. In a previous study, a sialic acid-cholesterol conjugate (SA-CH) was synthesized and modified onto the surface of DOX-loaded liposomes to target tumor-associated macrophages (TAMs), further improving the efficacy of DOX-loaded liposomes over that of Doxil®. Meanwhile, the good retention characteristics and promising antitumor ability of sphingomyelin/cholesterol (SM/CH) system for water-soluble drugs have attracted wide attention. Therefore, we aimed to use SA-CH as the target and hydrogenated soybean phosphatidylcholine (HSPC) or egg sphingomyelin (ESM) as the membrane material to develop a more stable DOX-loaded liposome with stronger antitumor activity. The liposomes were evaluated for particle size, polydispersity index, zeta potential, entrapment efficiency, in vitro release, long-term storage, cytotoxicity, cellular uptake, pharmacokinetics, tumor targetability, and in vivo antitumor activity. In the liposomes prepared using HSPC/CH, sialic acid (SA) modification considerably increased the accumulation of DOX-loaded liposomes in the tumor, thus exerting a better antitumor effect. However, SA modification in DOX-ESL (SA-CH-modified DOX-loaded liposomes prepared by ESM/CH) destroyed the strong retention effect of the ESM/CH system on DOX, resulting in a reduced antitumor effect. Notably, DOX-ECL (DOX-loaded liposome prepared by ESM/CH) had the optimal storage stability, lowest toxicity, and optimal antitumor effect due to better drug retention properties. Thus, the ESM/CH liposome of DOX is a potential drug delivery system. Sketch of the effect of two DOX-loaded liposomes with hydrogenated soybean phospholipid (HSPC) and egg sphingomyelin (ESM) as lipid membrane material and surface-modified SA derivative on tumor growth inhibition.

[CiteSpace knowledge map of gut microbiota research involving traditional Chinese medicine in recent twenty years].

We employed bibliometrics to comprehensively study the hotspots and frontiers of gut microbiota research involving traditional Chinese medicine(TCM), aiming to provide new ideas for the subsequent research in this field. The studies of gut microbiota with TCM published from January 1, 2002 to December 31, 2021 were retrieved from CNKI, Wanfang, VIP and Web of Science(WoS). After data screening and cleaning, CiteSpace 5.8.R3 was used to visualize and analyze the authors, journals, and keywords. A total of 1 119 Chinese articles and 815 English articles were included in the study. The period of 2019-2021 witnessed the surge in the number of articles published in this field, being the peak research period. TAN Zhou-jin and DUAN Jin-ao were the authors publishing the most articles in Chinese and English, respectively. The two authors ranked top in both Chinese and English articles, playing a central role in this research field. The top five Chinese and English journals in this field had a large influence in the international research field. High-frequency keywords and keyword clustering showed that the research hotspots in this field were concentrated in four areas: trial and clinical research on the regulation of gut microbiota in disease treatment by TCM, metabolic transformation of Chinese medicines by gut microbiota, and the effect of TCM added to feed on the gut microbiota and growth performance of animals. The study of gut microbiota structure in patients with different TCM syndromes, as well as that of TCM combined with probiotics/flora transplantation in the treatment of diseases, can provide new ideas for clinical diagnosis and traditional drug treatment of diseases and has great research space and research value in the future.

Polysialic Acid Self-assembled Nanocomplexes for Neutrophil-Based Immunotherapy to Suppress Lung Metastasis of Breast Cancer.

The role of neutrophils in tumor metastasis has recently attracted widespread interest. Neutrophils are the most abundant immune cells in human peripheral blood, and large numbers can spontaneously migrate to metastatic sites, where they form an immunosuppressive microenvironment. Polysialic acid (PSA) can target peripheral blood neutrophils (PBNs) mediated by L-selectin, and abemaciclib (ABE) and mitoxantrone (MIT) can treat immunosuppressive microenvironments. Here, we aimed to inhibit lung metastasis of breast cancer and improve chemoimmunotherapy by designing a PSA-modified ABE and MIT co-delivery system (AM-polyion complex (PIC)) to target PBNs in mice with metastatic tumors. We found that through electrostatic interactions between the strong negative charge of PSA and the positive charge of the drug can form stable nanocomplexes and that spontaneous migration of neutrophils can mediate the aggregation of these complexes in the lungs, induce antimetastatic immune responses, enhance the effectiveness of cytotoxic T lymphocytes (CTLs), and inhibit regulatory T cell (Treg) proliferation in vivo and in vitro. Pharmacodynamic results suggested that neutrophil-mediated AM-PIC chemoimmunotherapy inhibited tumor metastasis in mice with lung metastasis of 4T1 breast cancer. Overall, PSA-modified nanocomplexes offer promising neutrophil-mediated, targeted drug delivery systems to treat lung metastasis of breast cancer.

Antitumor Immunotherapy of Sialic Acid and/or GM1 Modified Coenzyme Q10 Submicron Emulsion.

Immunotherapy is a novel therapeutic approach for controlling and killing tumor cells by stimulating or reconstituting the immune system, among which T cells serve as immune targets. Herein, we used coenzyme Q10 (CoQ10), which has both immune activation and avoids adverse reactions, as a model drug and developed four CoQ10 submicron emulsions modified with sialic acid (SA) and/or monosialotetrahexosyl ganglioside (GM1). On the one hand, SA interacts with L-selectins on the surface of T cells after entering the circulatory system, leading to activation of T cells and enhancement of antitumor immune responses. On the other hand, owing to its immune camouflage, GM1 can prolong the circulation time of the preparation in the body, thereby increasing the accumulation of the drug at the tumor site. In vitro and in vivo experiments showed that SA-modified preparations exhibited stronger immune activation and inhibition of tumor proliferation. Pharmacokinetic experiments showed that GM1-modified preparations have longer circulation times in vivo. However, SA and GM1 co-modification did not produce a synergistic effect on the preparation. In conclusion, the SA-modified CoQ10 submicron emulsion (Q10-SE) showed optimal antitumor efficacy when administered at a medium dose (6 mg CoQ10 kg-1). In this study, the submicron emulsion model was used as a carrier, and the tumor-bearing mice were used as animal models. In addition, CoQ10 submicron emulsion was modified with SA-CH with active targeting function and/or GM1 with long-circulation function to explore the antitumor effects of different doses of CoQ10 submicron emulsion, and to screen the best tumor immunotherapy formulations of CoQ10.

An Application of Tumor-Associated Macrophages as Immunotherapy Targets: Sialic Acid-Modified EPI-Loaded Liposomes Inhibit Breast Cancer Metastasis.

Breast cancer metastasis is an important cause of death in patients with breast cancer and is closely related to circulating tumor cells (CTCs) and the metastatic microenvironment. As the most infiltrating immune cells in the tumor microenvironment (TME), tumor-associated macrophages (TAMs), which highly express sialic acid (SA) receptor (Siglec-1), are closely linked to tumor progression and metastasis. Furthermore, the surface of CTCs also highly expressed receptor (Selectin) for SA. A targeting ligand (SA-CH), composed of SA and cholesterol, was synthesized and modified on the surface of epirubicin (EPI)-loaded liposomes (EPI-SL) as an effective targeting delivery system. Liposomes were evaluated for characteristics, stability, in vitro release, cytotoxicity, cellular uptake, pharmacokinetics, tumor targeting, and pharmacodynamics. In vivo and in vitro experiments showed that EPI-SL enhanced EPI uptake by TAMs. In addition, cellular experiments showed that EPI-SL could also enhance the uptake of EPI by 4T1 cells, resulting in cytotoxicity second only to that of EPI solution. Pharmacodynamic experiments have shown that EPI-SL has optimal tumor inhibition with minimal toxicity, which can be ascribed to the fact that EPI-SL can deliver drugs to tumor based on TAMs and regulate TME through the depletion of TAMs. Our study demonstrated the significant potential of SA-modified liposomes in antitumor metastasis. Schematic diagram of the role of SA-CH modified EPI-loaded liposomes in the model of breast cancer metastasis.

[Visual analysis on regulation of necroptosis with Chinese medicine based on VOSviewer and CiteSpace knowledge graphs].

The study was conducted by searching the literature related to the regulation of necroptosis with Chinese medicine from January 1, 2005 to December 31, 2021 in CNKI, VIP, Wanfang, Web of Science(WoS), and PubMed. The obtained literature were imported into NoteExpress for eliminating duplicates and screening, and the final included articles were imported into Excel to plot the publication trend. The core authors were identified according to Price's law, and VOSviewer 1.6.17 was used to draw a collaborative view of the core authors and sort the high-frequency keywords. Then CiteSpace 5.8.R3 was employed to analyze keywords clustering, burst, and timeline view. Finally, 98 Chinese articles and 72 English articles were included in the study. The number of publications on the regulation of necroptosis with Chinese medicine has been increasing year by year. China ranked among the top in the world in terms of the number of publications, and Chinese authors played a central role in this field. Specifically, LIU Hua published the most Chinese literature while CHEN X P had the most English publications. The collaborative view of the core authors showed more intra-team cooperation and less inter-team cooperation. The Chinese and English keywords formed ten clusters separately, indicating that the research hotspots of regulation of necroptosis with Chinese medicine mainly focused on disease, prescription, related factors, and mecha-nism. Further, the analysis of Chinese and English keywords revealed that regarding disease treatment, tumor, ischemia-reperfusion injury, neurodegenerative diseases, and inflammatory diseases were studied most. The Chinese medicines that received much attention in this field were curcumin, shikonin and tanshinone. The main protein factors involved were Ripk1, Ripk3, Mlkl, and TNF-α, and Ripk1/Ripk3/Mlkl and p53 signaling pathways were predominant. Moreover, single herbs and herbal monomers were the hotspots of the included articles. In the future, scholars need to expand the study of classical Chinese herbal compounds and explore their mechanism of action in the occurrence and development of various diseases, to provide new ideas and experimental basis for the treatment of clinical diseases with Chinese medicine.

Evaluation of the Antitumor Effect and Immune Response of Micelles Modified with a Polysialic Acid-D-α-Tocopheryl Polyethylene Glycol 1000 Succinate Conjugate.

D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) has shown potential applications in cancer therapy owing to its attractive properties, including reversal of multi-drug resistance and synergistic effects with antitumor drugs. However, its associated shortcomings cannot be underestimated, including activation of the body's immune response and acceleration of blood clearance of polyethylene glycolylated preparations. Polysialic acid (PSA) is a polysaccharide homopolymer, with the dual function of immune camouflage and tumor targeting. PSA and TPGS conjugates (PSA-TPGS) were synthesized to weaken the immune risks of TPGS. We developed PSA-TPGS and TPGS self-assembled mixed micelles and encapsulated the classical antineoplastic, docetaxel. The particle size of docetaxel-loaded mixed micelles was 16.3 ± 2.0 nm, with entrapment efficiency of 99.0 ± 0.9% and drug-loading efficiency of 3.20 ± 0.03%. Antitumor activity studies revealed that the mixed micelles showed better tumor inhibition than Tween 80 and TPGS micelles. Detection of the accelerated blood clearance (ABC) phenomenon demonstrated that insertion of PSA-TPGS into the micelles weakened the ABC phenomenon induced by TPGS. In summary, PSA-TPGS could be a potential nanocarrier to improve antitumor activity and weaken immune responses.

Sialic Acid Conjugate-Modified Liposomal Dexamethasone Palmitate Targeting Neutrophils for Rheumatoid Arthritis Therapy: Influence of Particle Size.

Many anti-inflammatory therapies targeting neutrophils have been developed so far. A sialic acid (SA)-modified liposomal (SAL) formulation, based on the high expression of L-selectin in peripheral blood neutrophils (PBNs) and SA as its targeting ligand, has proved to be an effective neutrophil-mediated drug delivery system targeting rheumatoid arthritis (RA). The objective of this study was to investigate the influence of particle size of drug-carrying SALs transported and delivered by neutrophils on their anti-RA effect. Dexamethasone palmitate-loaded SALs (DP-SALs) of different particle sizes (300.2 ± 5.5 nm, 150.3 ± 4.3 nm, and 75.0 ± 3.9 nm) were prepared with DP as a model drug. Our study indicated that DP-SALs could efficiently target PBNs, with larger liposomes leading to higher drug accumulation in cells. However, a high intake of large DP-SALs by PBNs inhibited their migration ability and capacity to release the payload at the target site. In contrast, small DP-SALs (75.0 ± 3.9 nm) could maintain the drug delivery potential of PBNs, leading to their efficient accumulation at the inflammatory site, where PBNs would be excessively activated to form neutrophil extracellular traps along with efficient payload release (small DP-SALs) and finally to induce excellent anti-RA effect.

Influence of Dose on Neutrophil-Mediated Delivery of Nanoparticles for Tumor-Targeting Therapy Strategies.

It is well known that neutrophil-mediated delivery of therapeutic agents is a promising method for treating tumors. However, owing to the limited number and limited uptake ability of neutrophils, determining a reasonable dose has become an urgent problem to be solved. Furthermore, the number of nanoparticles is far greater than the number of neutrophils at normal doses, which causes excessive nanoparticles to reach nontargeted organs or tissues, leading to serious adverse effects. To address these problems, a neutrophil-targeting delivery system (DiR-DADGC-L) based on DiR-labeled and butanedioic acid (DA)-linked 5-amino-3,5-dideoxy-D-Glycerol-D-galactonanulose-cholesterol conjugate (DADGC) was designed to improve the efficiency of hitchhiking neutrophils through the specific binding of sialic acid (SA) to L-selectin (SA-binding receptor, expressed on neutrophils). DiR-DADGC-L was prepared with favorable particle size and encapsulation efficiency (%EE) to deliver DiR into neutrophils. Subsequently, diverse doses of DiR-DADGC-L were injected intravenously into S180 tumor-bearing and cyclophosphamide-depleted (CTX-D) S180 tumor-bearing mice to evaluate the in vivo behavior of liposomes. The results verified the following: a) The content of DiR-DADGC-L in neutrophils accounts for approximately 14.5% of the content of DiR-DADGC-L in plasma, and the uptake capacity of neutrophils remains unchanged under different doses, and b) both neutrophils and the enhanced permeability and retention (EPR) effect might exert significant roles in tumor treatment. As for the neutrophil-mediated delivery system, higher doses are not necessarily appropriate, and a lower dose may achieve an unexpected effect. It will be wise to determine an optimum dose to improve delivery efficiency.

Accelerated Blood Clearance of Nanoemulsions Modified with PEG-Cholesterol and PEG-Phospholipid Derivatives in Rats: The Effect of PEG-Lipid Linkages and PEG Molecular Weights.

Various types of nanocarriers modified with poly(ethylene glycol) (PEG) exhibit the accelerated blood clearance (ABC) phenomenon, resulting in reduced circulation time and abnormal increase in hepatic and splenic accumulations. Based on the abundance of esterases in the serum of rats, we developed cleavable methoxy PEG-cholesteryl methyl carbonate (mPEG-CHMC) with a carbonate linkage and noncleavable N-(carbonyl-methoxy PEG-n)-1,2-distearoyl-sn-glycero-3-phos-phoethanolamine (mPEG-DSPE) with a carbamate linkage on the surface of the nanoemulsions (CHMCE and PE, respectively). Both PEG derivatives possessed PEG with six different molecular weights (n = 350, 550, 750, 1000, 2000, and 5000). The pharmacokinetic behaviors and biodistributions of single and repeated injection of the two types of PEGylated nanoemulsions were determined to investigate the influence of cleavable linkages and PEG molecular weights on the ABC phenomenon in an attempt to find a potential strategy to eliminate the ABC phenomenon. CHMCEns (n = 1000, 2000, and 5000) exhibited the same pharmacokinetic behaviors as PE550 and PE750 and only alleviated the ABC phenomenon to a certain extent at the expense of shortened cycle time, indicating that the cleavable carbonate linkage was not an ideal strategy to eliminate the ABC phenomenon. As the molecular weights of PEG increased, the ABC phenomenon became more severe. Surprisingly, PE5000 induced a lower anti-PEG IgM level and a weaker ABC phenomenon compared with PE2000 while possessing a similar long circulation time. The results suggested that increasing the molecular weight of PEG in the PEG derivatives could be a potential strategy for eliminating the ABC phenomenon while simultaneously guaranteeing longer circulation time.

The Contribution of PEG Molecular Weights in PEGylated Emulsions to the Various Phases in the Accelerated Blood Clearance (ABC) Phenomenon in Rats.

PEGylated preparations will be cleared rapidly from blood circulation when they are administrated twice in the same animal at a time interval, referred to as the "accelerated blood clearance" (ABC) phenomenon. Commonly, the study of the ABC phenomenon was investigated in two aspects: induction phase and effectuation phase. Herein, we report the influence of physicochemical properties (PEG molecular weights) in the induction phase and effectuation phase on the ABC phenomenon. In the experiment, on one hand, PEGylated emulsions with different molecular weights of PEG (refer to PEn, n = 400, 600, 800, 1000, 2000, and 5000) were injected for the first dose (induction phase) and induced PE2000 to produce ABC phenomenon. On the other hand, after PE2000 injected, PEn was injected for the second dose (effectuation phase). The results indicated that PE2000 and PE5000 induced an intense ABC phenomenon by their long-circulating characteristic. Interestingly, PE400, PE600, PE800, and PE1000 produced a consistent ABC phenomenon but different circulation time. Apparently, the induction of the ABC phenomenon is not only determined by the circulation time but also by the PEG molecular weights. When PEn is in the effectuation phase, the extent of the ABC phenomenon was not positively related to the molecular weights of PEG, increasing first and then weaken with the increase of molecular weights of PEG. These suggest that the number of -(CH2CH2O)n- repeat units of PE2000 was more conducive to interact with anti-PEG IgM. The results reported here clearly indicate that both the PEG molecular weights of prior dose and the subsequent dose of emulsion strongly influence the extent of the ABC phenomenon. Taken together, our observations in this study complete the effect of PEG molecular weights at a different phase of the ABC phenomenon. Furthermore, our findings have a significant impact on the choice of molecular weights for PEGylated formulations for use in cross-administration.

Effects of Uncleavable and Cleavable PEG-Lipids with Different Molecular Weights on Accelerated Blood Clearance of PEGylated Emulsions in Beagle Dogs.

To investigate the effect of polyethylene glycol (PEG) molecular weights on circulation time of PEGylated emulsions and the second injection of injected PEGylated emulsions, we studied the effect of molecular weights on the pharmacokinetic behavior of PEG-DSPE (modified emulsions with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-n-[methoxy (polyethyleneglycol)]) and PEG-CHMC (modified emulsions with poly(ethyleneglycol)-cholesteryl carbonate) emulsions in beagle dogs. The "accelerated blood clearance" (ABC) phenomenon was induced. Through this study, the contribution of PEG molecular weights on the ABC phenomenon was further clarified, and the results provided guidance for lessening or eliminating the ABC phenomenon. We injected different PEG-modified emulsions with 10% PEG-modified density into beagle dogs at 2 µmol phospholipids kg-1 and the blood samples were drawn after 1 min, 3 min, 5 min, 10 min, 15 min, 30 min, 60 min, 120 min, 240 min, 360 min, 600 min, and 24 h. Then, concentrations of the drug were assayed using high-performance liquid chromatography (HPLC). The results showed that the circulation times of PEG-DSPE-modified emulsions were significantly different because of the difference in molecular weights, whereas those of the PEG-CHMC modified emulsions were not. The spatial conformation of PEG with small molecular weights (PEG400, PEG600, and PEG800) was more likely to induce a strong ABC phenomenon. The results of our work suggest the interaction of circulation time and PEG molecular weights on the ABC phenomenon, implying that the spatial conformation of PEG has advantages that alleviate the ABC phenomenon. Importantly, the results have implications for the choice of molecular weights of PEG for PEGylated formulations.