Micro- and Nanoencapsulated Hybrid Delivery System (MNEHDS): A Novel Approach for Colon-Targeted Oral Delivery of Berberine.

Berberine (BBR) is currently explored in the oral treatment of many disorders, especially in those involving inflammatory processes. Nanotechnology-based drug delivery systems are emerging as an effective approach for improving the poor oral absorption/bioavailability of BBR. To optimize the BBR immunoregulatory effects on a specific part of the gastrointestinal tract, here we describe a micro- and nanoencapsulated hybrid delivery system (MNEHDS) for colon-targeted oral delivery of BBR and test its therapeutic efficacy in a murine colitis model. The MNEHDS is formed by encapsulation of BBR-loaded poly(lactic-co-glycolic acid) nanoparticles into a pH-sensitive, BBR-pre-entrapped Eudragit FS30D matrix to form a hybrid microparticle composed of the BBR and BBR nanoparticles. Once in the colonic environment, the microencapsulated BBR is almost completely released for immediate action, while BBR nanoparticles can provide sustained release of BBR subsequent to their intestinal absorption. One dose of oral MNEHDS/BBR treatment results in significant attenuation of acute colitis induced by dextran sulfate sodium. The MNEHDS/BBR also proves to be effective during chronically induced colitis with two doses given 1 week apart. The improved efficacy is accompanied by decreased production of colon inflammation. Comparatively, oral treatment with one or two 7-day courses of free BBR has less effect on ameliorating either acute or chronic colitis. Thus, MNEHDS represents a novel delivery system for BBR, and potentially other therapeutic agents, to treat inflammatory bowel disease.

Intracellular signaling pathway in dendritic cells and antigen transport pathway in vivo mediated by an OVA@DDAB/PLGA nano-vaccine.

BACKGROUND: Poly(D, L-lactic-co-glycolic acid) (PLGA) nanoparticles have potential applications as a vaccine adjuvant and delivery system due to its unique advantages as biodegradability and biocompatibility. EXPERIMENTAL: We fabricated cationic solid lipid nanoparticles using PLGA and dimethyl-dioctadecyl-ammonium bromide (DDAB), followed by loading of model antigen OVA (antigen ovalbumin, OVA257-264) to form an OVA@DDAB/PLGA nano-vaccine. And we investigated the intracellular signaling pathway in dendritic cells in vitro and antigen transport pathway and immune response in vivo mediated by an OVA@DDAB/PLGA nano-vaccine. RESULTS: In vitro experiments revealed that the antigen uptake of BMDCs after nanovaccine incubation was two times higher than pure OVA or OVA@Al at 12 h. The BMDCs were well activated by p38 MAPK signaling pathway. Furthermore, the nano-vaccine induced antigen escape from lysosome into cytoplasm with 10 times increased cross-presentation activity than those of OVA or OVA@Al. Regarding the transport of antigen into draining lymph nodes (LNs), the nano-vaccine could rapidly transfer antigen to LNs by passive lymphatic drainage and active DC transport. The antigen+ cells in inguinal/popliteal LNs for the nano-vaccine were increased over two folds comparing to OVA@Al and OVA at 12 h. Moreover, the antigen of nano-vaccine stayed in LNs for over 7 days, germinal center formation over two folds higher than those of OVA@Al and OVA. After immunization, the nano-vaccine induced a much higher ratio of IgG2c/IgG1 than OVA@Al. It also effectively activated CD4+ T, CD8+ T and B cells for immune memory with a strong cellular response. CONCLUSION: These results indicated that DDAB/PLGA NP was a potent platform to improve vaccine immunogenicity by p38 signaling pathway in BMDCs, enhancing transport of antigens to LNs, and higher immunity response.

Prompt and Robust Humoral Immunity Elicited by a Conjugated Chimeric Malaria Antigen with a Truncated Flagellin.

As one of the pathogen-associated molecular patterns (PAMPs), flagellin is recently utilized as a potent adjuvant for many subunit vaccines. In this study, a truncated flagellin (tFL) with deletion of the hypervariable regions was adopted as a carrier-adjuvant by chemical conjugation with a chimeric malaria antigen M.RCAg-1 (M312) via a heterobifunctional polyethylene glycol (PEG) linker. After booster immunization in mice without any extra adjuvants, the M312-PEG-tFL conjugates elicited M312-specific antibody titers 100-1000 times higher than M312 and 10-100 times higher than the physical mixture of M312 and tFL. The elicited specific antibodies could recognize the native parasites, and the immunofluorescence assay (IFA) titer was 2100 for M312-P5k-tFL, which was about 7 times higher than M312. Furthermore, the IFA titers of the conjugates were comparable to the positive control of complete Freund's adjuvant (CFA). Compared to M312, the M312-PEG-tFL conjugates enhanced the proliferation index, lymphocyte activation, and memory T-cell generation. IgG subclasses of sera and cytokines analysis of splenocytes showed that conjugation with tFL could slightly trigger the Th1 polarization, while the antigen alone predominantly induced a Th2-biased immune response. Furthermore, a more-efficient innate immune response was provoked by the M312-PEG-tFL conjugates, as determined by the detection of antigen-specific TNF-α secretion by splenocytes. Our results indicated that tFL mainly retained the function as an agonist of TLR5. Conjugation of antigen to tFL could induce strong humoral and moderate cellular immune responses. Thus, conjugation of antigen to tFL as a potent carrier-adjuvant is an effective strategy for developing a promising protein-based vaccine.

Potential Hepatitis B Vaccine Formulation Prepared by Uniform-Sized Lipid Hybrid PLA Microparticles with Adsorbed Hepatitis B Surface Antigen.

For the purpose of strengthening the immunogenicity of the hepatitis B vaccine, which contains hepatitis B surface antigen (HBsAg), the development of biodegradable poly(lactic acid) (PLA) microparticles (MPs) modified with the cationic surfactant didodecyldimethylammonium bromide (DDAB) was attempted. DDAB-PLA MPs with an uniform size of about 1 µm were prepared in a simple and mild way. DDAB-PLA MPs with increased surface charge enhanced antigen adsorption capacity compared to plain PLA MPs. After immunization, DDAB-PLA MPs induced the gene expression of inflammatory cytokines and chemokines, which facilitated the following immune responses. DDAB-PLA MPs augmented the expression of co-stimulatory molecules along with the activation of bone-marrow-derived dendritic cells (BMDCs). DDAB-PLA MP-based vaccine formulations efficiently induced antibody production more than the aluminum-based vaccine and plain PLA MP-based formulation in vivo. Moreover, DDAB-PLA MPs were more likely to generate the polarization of the Th1 response indicating the cytotoxic ability against infectious pathogens. In conclusion, DDAB-PLA MPs could be a potent vaccine formulation to prime robust cellular and humoral immune responses.

Adjuvanticity Regulation by Biodegradable Polymeric Nano/microparticle Size.

Polymeric nano/microparticles as vaccine adjuvants have been researched in experimental and clinical studies. A more profound understanding of how the physicochemical properties regulate specific immune responses has become a vital requirement. Here we prepared poly(d,l-lactic-co-glycolic acid) (PLGA) nano/microparticles with uniform sizes (500 nm, 900 nm, 2.1 µm, and 4.9 µm), and the size effects on particle uptake, activation of macrophages, and antigen internalization were evaluated. Particle uptake kinetic studies demonstrated that 900 nm particles were the easiest to accumulate in cells. Moreover, they could induce macrophages to secrete NO and IL-1ß and facilitate antigen internalization. Furthermore, 900 nm particles, mixed with antigen, could exhibit superior adjuvanticity in both humoral and cellular immune responses in vivo, including offering the highest antibody protection, promoting the maximum secretion levels of IFN-γ and IL-4 than particles with other sizes. Overall, 900 nm might be the optimum choice for PLGA particle-based vaccine adjuvants especially for recombinant antigens. Understanding the effect of particle size on the adjuvanticity based immune responses might have important enlightenments for rational vaccine design and applications.

Pathogen-Mimicking Polymeric Nanoparticles based on Dopamine Polymerization as Vaccines Adjuvants Induce Robust Humoral and Cellular Immune Responses.

Aiming to enhance the immunogenicity of subunit vaccines, a novel antigen delivery and adjuvant system based on dopamine polymerization on the surface of poly(D,L-lactic-glycolic-acid) nanoparticles (NPs) with multiple mechanisms of immunity enhancement is developed. The mussel-inspired biomimetic polydopamine (pD) not only serves as a coating to NPs but also functionalizes NP surfaces. The method is facile and mild including simple incubation of the preformed NPs in the weak alkaline dopamine solution, and incorporation of hepatitis B surface antigen and TLR9 agonist unmethylated cytosine-guanine (CpG) motif with the pD surface. The as-constructed NPs possess pathogen-mimicking manners owing to their size, shape, and surface molecular immune-activating properties given by CpG. The biocompatibility and biosafety of these pathogen-mimicking NPs are confirmed using bone marrow-derived dendritic cells. Pathogen-mimicking NPs hold great potential as vaccine delivery and adjuvant system due to their ability to: 1) enhance cytokine secretion and immune cell recruitment at the injection site; 2) significantly activate and maturate dendritic cells; 3) induce stronger humoral and cellular immune responses in vivo. Furthermore, this simple and versatile dopamine polymerization method can be applicable to endow NPs with characteristics to mimic pathogen structure and function, and manipulate NPs for the generation of efficacious vaccine adjuvants.

Immunopotentiator-Loaded Polymeric Microparticles as Robust Adjuvant to Improve Vaccine Efficacy.

PURPOSE: Adjuvants are required to ensure the efficacy of subunit vaccines. Incorporating molecular immunopotentiators within particles could overcome drawbacks of molecular adjuvants (such as solubility and toxicity), and improve adjuvanticity of particles, achieving stronger adjuvant activity. Aim of this study is to evaluate the adjuvanticity of immunopotentiator-loaded polymeric particles for subunit vaccine. METHODS: PLGA microparticles (PMPs) and imiquimod (TLR-7 ligand)-loaded PLGA microparticles (IPMPs) were prepared by SPG premix membrane emulsification. In vitro and in vivo studies were performed to their adjuvant activity, using ovalbumin and H5N1 influenza split vaccine as antigens. RESULTS: Incorporating imiquimod into microparticles significantly improved the efficacy of PLGA microparticles in activating BMDCs and pMΦs, and antigen uptake by pMΦs was also promoted. IPMPs showed stronger adjuvanticity to augment OVA-specific immune responses than PMPs. IgG subclass profiles and cytokine secretion levels by splenocytes indicated that IPMPs elicited more Th1-polarized immune response, compared to PMPs. In vivo study using H5N1 influenza split vaccine as antigen also confirmed the effects of IPMPs on antigen-specific cellular immunity. CONCLUSIONS: Considering adjuvanticity and safety profiles (PLGA and IMQ, both approved by FDA), we conclude that IMQ-loaded PLGA microparticles are promising robust adjuvant for subunit vaccines.

Enhanced humoral and cell-mediated immune responses generated by cationic polymer-coated PLA microspheres with adsorbed HBsAg.

Surface-engineered particulate delivery systems for vaccine administration have been widely investigated in experimental and clinical studies. However, little is known about charge-coated microspheres as potential recombinant subunit protein antigen delivery systems in terms of adsorption and related immune responses. In the present study, cationic polymers, including chitosan (CS), chitosan chloride (CSC), and polyethylenimine (PEI), were used to coat PLA microspheres to build positively charged surfaces. Antigen adsorption capacity was enhanced with increased surface charge of coated microspheres. In macrophages, HBsAg adsorbed on the surface of cationic microspheres specifically enhanced antigen uptake and augmented CD86, MHC I, and MHC II expression and IL-1ß, IL-6, TNF-α, and IL-12 release. Antigens were more likely to localize independent of lysosomes after phagocytosis in antigen-attached cationic microsphere formulations. After intraperitoneal immunization, cationic microsphere-based vaccine formulations generated a rapid and efficient humoral immune response and cytokine release as compared with aluminum-adsorbed vaccine and free antigens in vivo. Moreover, microspheres coated with cationic polymers with relatively high positive charges and higher antigen adsorption exhibited strong stimulation of the Th1 response. In conclusion, PLA microspheres coated with cationic polymers may be a potential recombinant antigen delivery system to induce strong cell and humoral immune responses.

Comparison of PLA microparticles and alum as adjuvants for H5N1 influenza split vaccine: adjuvanticity evaluation and preliminary action mode analysis.

PURPOSE: To compare the adjuvanticity of polymeric particles (new-generation adjuvant) and alum (the traditional and FDA-approved adjuvant) for H5N1 influenza split vaccine, and to investigate respective action mode. METHODS: Vaccine formulations were prepared by incubating lyophilized poly(lactic acid) (PLA) microparticles or alum within antigen solution. Antigen-specific immune responses in mice were evaluated using ELISA, ELISpot, and flow cytometry assay. Adjuvants' action modes were investigated by determining antigen persistence at injection sites, local inflammation response, antigen transport into draining lymph node, and activation of DCs in secondary lymphoid organs (SLOs). RESULTS: Alum promoted antigen-specific humoral immune response. PLA microparticles augmented both humoral immune response and cell-mediated-immunity which might enhance cross-protection of influenza vaccine. With regard to action mode, alum adjuvant functions by improving antigen persistence at injection sites, inducing severe local inflammation, slightly improving antigen transport into draining lymph nodes, and improving the expression of MHC II on DCs in SLOs. PLA microparticles function by slightly improving antigen transport into draining lymph nodes, and promoting the expression of both MHC molecules and co-stimulatory molecules on DCs in SLOs. CONCLUSIONS: Considering the adjuvanticity and side effects (local inflammation) of both adjuvants, we conclude that PLA microparticles are promising alternative adjuvant for H5N1 influenza split vaccine.

Dimethyl-Dioctadecyl-Ammonium Bromide/Poly(lactic acid) Nanoadjuvant Enhances the Immunity and Cross-Protection of an NM2e-Based Universal Influenza Vaccine.

For most frequent respiratory viruses, there is an urgent need for a universal influenza vaccine to provide cross-protection against intra- and heterosubtypes. We previously developed an Escherichia coli fusion protein expressed extracellular domain of matrix 2 (M2e) and nucleoprotein, named NM2e, and then combined it with an aluminum adjuvant, forming a universal vaccine. Although NM2e has demonstrated a protective effect against the influenza virus in mice to some extent, further improvement is still needed for the induction of immune responses ensuring adequate cross-protection against influenza. Herein, we fabricated a cationic solid lipid nanoadjuvant using poly(lactic acid) (PLA) and dimethyl-dioctadecyl-ammonium bromide (DDAB) and loaded NM2e to generate an NM2e@DDAB/PLA nanovaccine (Nv). In vitro experiments suggested that bone marrow-derived dendritic cells incubated with Nv exhibited ∼4-fold higher antigen (Ag) uptake than NM2e at 16 h along with efficient activation by NM2e@DDAB/PLA Nv. In vivo experiments revealed that Ag of the Nv group stayed in lymph nodes (LNs) for more than 14 days after initial immunization and DCs in LNs were evidently activated and matured. Furthermore, the Nv primed T and B cells for robust humoral and cellular immune responses after immunization. It also induced a ratio of IgG2a/IgG1 higher than that of NM2e to a considerable extent. Moreover, NM2e@DDAB/PLA Nv quickly restored body weight and improved survival of homo- and heterosubtype influenza challenged mice, and the cross-protection efficiency was over 90%. Collectively, our study demonstrated that NM2e@DDAB/PLA Nv could offer notable protection against homo- and heterosubtype influenza virus challenges, offering the potential for the development of a universal influenza vaccine.

Engineering biomaterial-associated complement activation to improve vaccine efficacy.

The complement system plays an important role in innate and adaptive immunity, which suggests that complement activation could be exploited as a potential strategy for vaccine adjuvants. Here we explored the potential of chitosan-based microparticles (CS-NH2 MPs) as a vaccine adjuvant with an active surface for complement activation due to the abundance of amino groups. In vaccination studies, using recombinant anthrax protective antigen as a model antigen, compared with the control microparticles (amino-cross-linked MPs), we found that microparticles (MPs) with abundant amino groups significantly enhanced higher antigen-specific IgG titers in vivo and enhanced the production of IL-4 and IFN-γ with ex vivo restimulation. Furthermore, proliferative responses of splenocytes to ex vivo antigen restimulation were enhanced following immunization with MPs with amino groups. Overall, these results indicated that CS-NH2 MPs with a high surface density of amino groups were favorable for complement activation and immune responses. Our data provide further design principles for studies on complement-activating MPs as a vaccine platform.

Tumor Microenvironment Regulation and Cancer Targeting Therapy Based on Nanoparticles.

Although we have made remarkable achievements in cancer awareness and medical technology, there are still tremendous increases in cancer incidence and mortality. However, most anti-tumor strategies, including immunotherapy, show low efficiency in clinical application. More and more evidence suggest that this low efficacy may be closely related to the immunosuppression of the tumor microenvironment (TME). The TME plays a significant role in tumorigenesis, development, and metastasis. Therefore, it is necessary to regulate the TME during antitumor therapy. Several strategies are developing to regulate the TME as inhibiting tumor angiogenesis, reversing tumor associated macrophage (TAM) phenotype, removing T cell immunosuppression, and so on. Among them, nanotechnology shows great potential for delivering regulators into TME, which further enhance the antitumor therapy efficacy. Properly designed nanomaterials can carry regulators and/or therapeutic agents to eligible locations or cells to trigger specific immune response and further kill tumor cells. Specifically, the designed nanoparticles could not only directly reverse the primary TME immunosuppression, but also induce effective systemic immune response, which would prevent niche formation before metastasis and inhibit tumor recurrence. In this review, we summarized the development of nanoparticles (NPs) for anti-cancer therapy, TME regulation, and tumor metastasis inhibition. We also discussed the prospect and potential of nanocarriers for cancer therapy.

In vitro and in vivo evaluation of immune response of poly(lactic acid) nanoparticles with different end groups.

Poly(lactic acid) (PLA) has excellent properties of biodegradability and biocompatibility, which is a US Food and Drug Administration (FDA) approved biopolymer for the preparation of safe and effective vaccines, drugs, and gene delivery systems. However, there still exists a great problem whether and how the end group affects the immune response of PLA vaccines. Therefore, the aim of this study was to evaluate the in vitro and in vivo of immune response of PLA nanoparticles (NPs) with carboxyl (COOH) and ester (COOR) end groups. In vitro experiments suggested COOH NPs could promote the higher phagocytosis and activation of bone marrow dendritic cells (BMDCs) with a lower cytotoxicity. In vivo experiments showed that COOR NPs and COOH NPs could strongly elicit IgG, IgG1, and IgG2a responses both in the short and long-terms. However, the highest T cell and B cell activation, and central memory T cells response was induced by COOH NPs. In addition, the COOH NPs could significantly enhance splenocytes proliferation and cytokines secretion. Thus, the PLA with the COOH end group shows greater potential as efficient carrier materials of NPs for enhancing cellular and humoral immune responses.

The orchestration of cellular and humoral responses is facilitated by divergent intracellular antigen trafficking in nanoparticle-based therapeutic vaccine.

Therapeutic vaccination for the treatment of chronic hepatitis B is promising but has so far shown limited clinical efficacy. Herein, we employ polylactide nanoparticles (NPs) as the vaccine adjuvant and systematically explore their effect on activation of specific immunity and the underlying theoretical mechanisms. In vitro studies show that hepatitis B surface antigen (HBsAg) accumulates in antigen-presenting cells (APCs) to a larger content (270%) with the assistant of NP in comparison with the pure-antigen group. Besides the elevated costimulators (CD80/86) and increased major histocompatibility complex (MHC) II molecules, the MHC I molecules are also found upregulated. This result is mostly owing to the divergent antigen trafficking ways of NP-antigen in APCs, especially for the escape of exogenous HBsAg from the lysosomes to the cytosol. Interestingly, the MHC I level is downregulated in alum-antigen group, indicating a possible reason for its inefficiency in priming cellular response. Further in vivo experiments establish that NP-antigen group indeed enhances the CD8(+) CTL cytotoxicity and IFN-γ cytokine secretion. Meanwhile, specific antibody titer is also upregulated, and even surpasses that of the commercialized alum-antigen. All these results strongly support that NP-based antigen promotes an orchestration of cellular and humoral immune response, exhibiting favorable intrinsic properties to be applied in therapeutic vaccines.

Ion Interference Therapy of Tumors Based on Inorganic Nanoparticles.

As an essential substance for cell life activities, ions play an important role in controlling cell osmotic pressure balance, intracellular acid-base balance, signal transmission, biocatalysis and so on. The imbalance of ion homeostasis in cells will seriously affect the activities of cells, cause irreversible damage to cells or induce cell death. Therefore, artificially interfering with the ion homeostasis in tumor cells has become a new means to inhibit the proliferation of tumor cells. This treatment is called ion interference therapy (IIT). Although some molecular carriers of ions have been developed for intracellular ion delivery, inorganic nanoparticles are widely used in ion interference therapy because of their higher ion delivery ability and higher biocompatibility compared with molecular carriers. This article reviewed the recent development of IIT based on inorganic nanoparticles and summarized the advantages and disadvantages of this treatment and the challenges of future development, hoping to provide a reference for future research.

Virus-like Particles for TEM Regulation and Antitumor Therapy.

Tumor development and metastasis are intimately associated with the tumor microenvironment (TME), and it is difficult for vector-restricted drugs to act on the TME for long-term cancer immunotherapy. Virus-like particles (VLPs) are nanocage structures self-assembled from nucleic acid free viral proteins. Most VLPs range from 20-200 nm in diameter and can naturally drain into lymph nodes to induce robust humoral immunity. As natural nucleic acid nanocarriers, their surfaces can also be genetically or chemically modified to achieve functions such as TME targeting. This review focuses on the design ideas of VLP as nanocarriers and the progress of their research in regulating TME.

Local Destruction of Tumors for Systemic Immunoresponse: Engineering Antigen-Capturing Nanoparticles as Stimulus-Responsive Immunoadjuvants.

Immunotherapy has established a new paradigm for cancer treatment and made many breakthroughs in clinical practice. However, the rarity of immune response suggests that additional intervention is necessary. In recent years, it has been reported that local tumor destruction (LTD) can cause cancer cell death and induce an immunologic response. Thus, the combination of immunotherapy and LTD methods will be a promising approach to improve immune efficiency for cancer treatment. Herein, a nanobiotechnology platform to achieve high-precision LTD for systemic cancer immunotherapy has been successfully constructed. Possessing radio-sensitizing and photothermal properties, the engineered immunoadjuvant-loaded nanoplatform, which could precisely induce radiotherapy (RT)/photothermal therapy (PTT) to eliminate local tumor and meanwhile lead to the release of tumor-derived protein antigens (TDPAs), has been facilely fabricated by commercialized SPG membrane emulsification technology. Further on, the TDPAs could be captured and form personal nanovaccines in situ to serve as both reservoirs of antigen and carriers of immunoadjuvant, which can effectively improve the immune response. The investigations suggest that the combination of RT/PTT and improved immunotherapy using adjuvant-encapsulated antigen-capturing nanoparticles holds tremendous promise in cancer treatments.

Surface charge affects cellular uptake and intracellular trafficking of chitosan-based nanoparticles.

Chitosan-based nanoparticles (NPs) are widely used in drug delivery, device-based therapy, tissue engineering, and medical imaging. In this aspect, a clear understanding of how physicochemical properties of these NPs affect the cytological response is in high demand. The objective of this study is to evaluate the effect of surface charge on cellular uptake profiles (rate and amount) and intracellular trafficking. We fabricate three kinds of NPs (∼ 215 nm) with different surface charge via SPG membrane emulsification technique and deposition method. They possess uniform size as well as identical other physicochemical properties, minimizing any differences between the NPs except for surface charge. Moreover, we extend our research to eight cell lines, which could help to obtain a representative conclusion. Results show that the cellular uptake rate and amount are both positively correlated with the surface charge in all cell line. Subsequent intracellular trafficking indicates that some of positively charged NPs could escape from lysosome after being internalized and exhibit perinuclear localization, whereas the negatively and neutrally charged NPs prefer to colocalize with lysosome. These results are critical in building the knowledge base required to design chitosan-based NPs to be used efficiently and specifically.

Porous quaternized chitosan nanoparticles containing paclitaxel nanocrystals improved therapeutic efficacy in non-small-cell lung cancer after oral administration.

Clinical application of paclitaxel (PTX) is limited because of its poor solubility in aqueous media. To overcome this hurdle, we devised an oral delivery system by encapsulating PTX into N-((2-hydroxy-3-trimethylammonium) propyl) chitosan chloride (HTCC) nanoparticles. These nanoparticles were small (~130 nm), had a narrow size distribution, and displayed high loading efficiency owing to the homogeneous distribution of PTX nanocrystals. The matrix hydrophilicity and porous structure of the obtained nanoparticles accelerated their degradation and improved drug release. In vitro and in vivo transport experiments had proved that the presence of positive charges enhanced the intestinal permeability of these nanoparticles. Further in vitro experiment of cytotoxicity showed that the PTX-loaded HTCC nanoparticle (HTCC-NP:PTX) was more effective than native PTX owing to enhanced cellular uptake. Drug distribution in tissues and in vivo imaging studies confirmed the preferred accumulation of HTCC-NP:PTX in subcutaneous tumor tissue. Subsequent tumor xenograft assays demonstrated the promising therapeutic effect of HTCC-NP:PTX on inhibition of tumor growth and induction of apoptosis in tumor cells. Additional investigation into side effects revealed that HTCC-NP:PTX caused lower Cremophor EL-associated toxicities compared with Taxol. These results strongly supported the notion that HTCC nanoparticle (HTCC-NP) is a promising candidate as an oral carrier of PTX for cancer therapy.

Tumor microenvironment remodeling and tumor therapy based on M2-like tumor associated macrophage-targeting nano-complexes.

Background: Among the many immunosuppressive cells in the tumor microenvironment, tumor-associated-macrophages (TAMs) are well known to contribute to tumor development. TAMs can be conditioned (polarized) to transition between classical M1-like macrophages, or alternatively to M2-like macrophages. Both are regulated by signaling molecules in the microenvironment. M1-like TAMs can secrete classic inflammatory cytokines that kill tumors by promoting tumor cell necrosis and immune cell infiltration into the tumor microenvironment. In contrast, M2-like TAMs exhibit powerful tumor-promoting functions, including degradation of tumor extracellular matrix, destruction of basement membrane, promotion of angiogenesis, and recruitment of immunosuppressor cells, all of which further promote tumor progression and distal metastasis. Therefore, remodeling the tumor microenvironment by reversing the TAM phenotype will be favorable for tumor therapy, especially immunotherapy. Methods: PLGA nanoparticles encapsulating baicalin and melanoma antigen Hgp peptide fragment 25-33 were fabricated using the ultrasonic double-emulsion technique. The nanoparticles were further loaded with CpG fragments and used conjugated M2pep and α-pep peptides on their surfaces to produce novel nano-complexes. The capability to target M2-like TAMs and anti-tumor immunotherapy effects of nano-complexes were evaluated by flow cytometry and confocal microscopy in vitro. We also investigated the survival and histopathology of murine melanoma models administrated with different nanocomplexes. Improvements in the tumor microenvironment for immune attack of melanoma-bearing mice were also assessed. Results: The nano-complexes were effectively ingested by M2-like TAMs in vitro and in vivo, and the acidic lysosomal environment triggered the disintegration of polydopamine from the nanoparticle surface, which resulted in the release of the payloads. The released CpG played an important role in transforming the M2-like TAMs into the M1-like phenotype that further secreted inflammatory cytokines. The reversal of TAM released cytokines and gradually suppressed tumor angiogenesis, permitting the remodeling of the tumor microenvironment. Moreover, the activated TAMs also presented antigen to T cells, which further stimulated the antitumor immune response that inhibited tumor metastasis. Activated T cells released cytokines, which stimulated NK cell infiltration and directly resulted in killing tumor cells. The baicalin released by M1-like TAMs also killed tumor cells. Conclusion: The nano-complexes facilitated baicalin, antigen, and immunostimulant delivery to M2-like TAMs, which polarized and reversed the M2-like TAM phenotype and remodeled the tumor microenvironment to allow killing of tumor cells.