Polysaccharide-Based Coacervate Microgel Bearing Cationic Peptides That Achieve Dynamic Cell-Membrane Structure Alteration and Facile Cytosolic Infusion of IgGs.

Conjugates of the biocompatible polysaccharide pullulan with a cell membrane permeabilizing peptide L17E (PL-L17Es) were prepared with the aim of producing complex coacervates with pronounced intracellular antibody (IgG) delivery activity and stable structures. Coacervates with diameters of a few µm were formed simply by mixing PL-L17Es with IgG labeled with negatively charged fluorescent moieties of Alexa Fluor 488 [IgG(AF488)]. The coacervate resulted in a pronounced cytosolic infusion of IgG(AF488) and IgG binding to the target proteins inside the cell. The droplet structures were maintained even under high salt conditions, and the fluorescence in the droplet was not recovered after photobleaching, suggesting the formation of complex coacervate microgels. Dynamic changes in cell membrane structure to entrap the coacervate microgels were captured by confocal and electron microscopy, resulting in cytosolic IgG infusion. The use of M-lycotoxin instead of L17E resulted in a coacervate microgel with marked IgG delivery activity even in the presence of serum. Successful IgG delivery to primary hepatocytes, undifferentiated induced pluripotent stem (iPS) cells, and iPS cell-derived intestinal epithelial cells was also achieved. The construction of complex coacervate microgels with design flexibility and the validity of intracellular IgG delivery with high salt stability were thus demonstrated.

Bacterial membrane vesicles combined with nanoparticles for bacterial vaccines and cancer immunotherapy.

Similar to mammalian cells, most bacteria can release nano-sized membrane vesicles (MVs) into the extracellular environment. MVs contain lipids, bioactive proteins, nucleic acids, and metabolites, and play important roles in microbial physiology. MVs have great potential for immunotherapeutic applications, such as bacterial vaccines and cancer immunotherapy. However, because of the diversity in content and heterogeneity in size of MVs, the clinical application of MVs has been limited. Recently, the use of MVs combined with nanoparticles (NPs) has been shown to be effective in improving the homogeneity, stability and function of MVs. In this review, we focus on studies of MVs combined with NPs (MV-NPs) and describe the use of these MV-NPs in biotechnology, especially in bacterial vaccine and cancer immunotherapy.

ATP2B4 is an essential gene for epidermal growth factor-induced macropinocytosis in A431 cells.

Macropinocytosis (MPC) is a large-scale endocytosis pathway that involves actin-dependent membrane ruffle formation and subsequent ruffle closure to generate macropinosomes for the uptake of fluid-phase cargos. MPC is categorized into two types: constitutive and stimuli-induced. Constitutive MPC in macrophages relies on extracellular Ca2+ sensing by a calcium-sensing receptor. However, the link between stimuli-induced MPC and Ca2+ remains unclear. Here, we find that both intracellular and extracellular Ca2+ are required for epidermal growth factor (EGF)-induced MPC in A431 human epidermoid carcinoma cells. Through investigation of mammalian homologs of coelomocyte uptake defective (CUP) genes, we identify ATP2B4, encoding for a Ca2+ pump called the plasma membrane calcium ATPase 4 (PMCA4), as a Ca2+-related regulator of EGF-induced MPC. Knockout (KO) of ATP2B4, as well as depletion of extracellular/intracellular Ca2+, inhibited ruffle closure and macropinosome formation, without affecting ruffle formation. We demonstrate the importance of PMCA4 activity itself, independent of interactions with other proteins via its C-terminus known as a PDZ domain-binding motif. Additionally, we show that ATP2B4-KO reduces EGF-stimulated Ca2+ oscillation during MPC. Our findings suggest that EGF-induced MPC requires ATP2B4-dependent Ca2+ dynamics.

Fluoride-treated rare earth-free magnesium alloy ZK30: An inert and bioresorbable material for bone fracture treatment devices.

Bone fractures represent a common health problem, particularly in an increasingly aging population. Bioresorbable magnesium (Mg) alloy-based implants offer promising alternatives to traditional metallic implants for the treatment of bone fractures because they eliminate the need for implant removal after healing. The Mg-Y-rare-earth (RE)-Zr alloy WE43, designed for orthopedic implants, has received European Conformity mark approval. However, currently, WE43 is not clinically used in certain countries possibly because of concerns related to RE metals. In this study, we investigated the use of a RE-free alloy, namely, Mg-Zn-Zr alloy (ZK30), as an implant for bone fractures. Hydrofluoric acid (HF) treatment was performed to improve the corrosion resistance of ZK30. HF-treated ZK30 (HF-ZK30) exhibited lower corrosion rate and higher biocompatibility than those of WE43 in in vitro experiments. After implanting a rod of HF-ZK30 into the fractured femoral bones of mice, HF-ZK30 held the bones and healed the fracture without deformation. Treatment results of HF-ZK30 were comparable to those of WE43, indicating the potential of HF-ZK30 as a bioresorbable and safe implant for bone repair.

Alkyl gallates inhibit serine O-acetyltransferase in bacteria and enhance susceptibility of drug-resistant Gram-negative bacteria to antibiotics.

A principal concept in developing antibacterial agents with selective toxicity is blocking metabolic pathways that are critical for bacterial growth but that mammalian cells lack. Serine O-acetyltransferase (CysE) is an enzyme in many bacteria that catalyzes the first step in l-cysteine biosynthesis by transferring an acetyl group from acetyl coenzyme A (acetyl-CoA) to l-serine to form O-acetylserine. Because mammalian cells lack this l-cysteine biosynthesis pathway, developing an inhibitor of CysE has been thought to be a way to establish a new class of antibacterial agents. Here, we demonstrated that alkyl gallates such as octyl gallate (OGA) could act as potent CysE inhibitors in vitro and in bacteria. Mass spectrometry analyses indicated that OGA treatment markedly reduced intrabacterial levels of l-cysteine and its metabolites including glutathione and glutathione persulfide in Escherichia coli to a level similar to that found in E. coli lacking the cysE gene. Consistent with the reduction of those antioxidant molecules in bacteria, E. coli became vulnerable to hydrogen peroxide-mediated bacterial killing in the presence of OGA. More important, OGA treatment intensified susceptibilities of metallo-ß-lactamase-expressing Gram-negative bacteria (E. coli and Klebsiella pneumoniae) to carbapenem. Structural analyses showed that alkyl gallate bound to the binding site for acetyl-CoA that limits access of acetyl-CoA to the active site. Our data thus suggest that CysE inhibitors may be used to treat infectious diseases caused by drug-resistant Gram-negative bacteria not only via direct antibacterial activity but also by enhancing therapeutic potentials of existing antibiotics.

Modification of Silver Nanoplates with Cell-Binding Subunit of Bacterial Toxin and Their Antimicrobial Activity against Intracellular Bacteria.

Intracellular bacteria are able to survive and grow in host cells and often cause serious infectious diseases. The B subunit of the subtilase cytotoxin (SubB) found in enterohemorrhagic Escherichia coli O113:H21 recognizes sialoglycans on cell surfaces and triggers the uptake of cytotoxin by the cells, meaning that Sub B is a ligand molecule that is expected to be useful for drug delivery into cells. In this study, we conjugated SubB to silver nanoplates (AgNPLs) for use as an antibacterial drug and examined their antimicrobial activity against intracellularly infecting Salmonella typhimurium (S. typhimurium). The modification of AgNPLs with SubB improved their dispersion stability and antibacterial activity against planktonic S. typhimurium. The SubB modification enhanced the cellular uptake of AgNPLs, and intracellularly infecting S. typhimurium were killed at low concentrations of AgNPLs. Interestingly, larger amounts of SubB-modified AgNPLs were taken up by infected cells compared with uninfected cells. These results suggest that the S. typhimurium infection activated the uptake of the nanoparticles into the cells. SubB-modified AgNPLs are expected to be useful bactericidal systems for intracellularly infecting bacteria.

Enhanced Permeability and Retention Effect as a Ubiquitous and Epoch-Making Phenomenon for the Selective Drug Targeting of Solid Tumors.

In 1979, development of the first polymer drug SMANCS [styrene-co-maleic acid (SMA) copolymer conjugated to neocarzinostatin (NCS)] by Maeda and colleagues was a breakthrough in the cancer field. When SMANCS was administered to mice, drug accumulation in tumors was markedly increased compared with accumulation of the parental drug NCS. This momentous result led to discovery of the enhanced permeability and retention effect (EPR effect) in 1986. Later, the EPR effect became known worldwide, especially in nanomedicine, and is still believed to be a universal mechanism for tumor-selective accumulation of nanomedicines. Some research groups recently characterized the EPR effect as a controversial concept and stated that it has not been fully demonstrated in clinical settings, but this erroneous belief is due to non-standard drug design and use of inappropriate tumor models in investigations. Many research groups recently provided solid evidence of the EPR effect in human cancers (e.g., renal and breast), with significant diversity and heterogeneity in various patients. In this review, we focus on the dynamics of the EPR effect and restoring tumor blood flow by using EPR effect enhancers. We also discuss new applications of EPR-based nanomedicine in boron neutron capture therapy and photodynamic therapy for solid tumors.

Structural Determination of the Nanocomplex of Borate with Styrene-Maleic Acid Copolymer-Conjugated Glucosamine Used as a Multifunctional Anticancer Drug.

The development of effective anticancer drugs is essential for chemotherapy that specifically targets cancer tissues. We recently synthesized a multifunctional water-soluble anticancer polymer drug consisting of styrene-maleic acid copolymer (SMA) conjugated with glucosamine and boric acid (BA) (SGB complex). It demonstrated about 10 times higher tumor-selective accumulation compared with accumulation in normal tissues because of the enhanced permeability and retention effect, and it inhibited tumor growth via glycolysis inhibition, mitochondrial damage, and thermal neutron irradiation. Gaining insight into the anticancer effects of this SGB complex requires a determination of its structure. We therefore investigated the chemical structure of the SGB complex by means of nuclear magnetic resonance, infrared (IR) spectroscopy, and liquid chromatography-mass spectrometry. To establish the chemical structure of the SGB complex, we synthesized a simple model compound─maleic acid-glucosamine (MAG) conjugate─by using a maleic anhydride (MA) monomer unit instead of the SMA polymer. We obtained two MAG-BA complexes (MAGB) with molecular weights of 325 and 343 after the MAG reaction with BA. We confirmed, by using IR spectroscopy, that MAGB formed a stable complex via an amide bond between MA and glucosamine and that BA bound to glucosamine via a diol bond. As a result of this chemical design, identified via analysis of MAGB, the SGB complex can release BA and demonstrate toxicity to cancer cells through inhibition of lactate secretion in mild hypoxia that mimics the tumor microenvironment. For clinical application of the SGB complex, we confirmed that this complex is stable in the presence of serum. These findings confirm that our design of the SGB complex has various advantages in targeting solid cancers and exerting therapeutic effects when combined with neutron irradiation.

Controlled Delivery of an Anti-Inflammatory Toxin to Macrophages by Mutagenesis and Nanoparticle Modification.

Advances in drug delivery systems (DDSs) have enabled the specific delivery of drugs to target cells. Subtilase cytotoxin (SubAB) produced by certain enterohemorrhagic Escherichia coli strains induces endoplasmic reticulum (ER) stress and suppresses nitric oxide generation in macrophages. We previously reported that modification of SubAB with poly(D,L-lactide-co-glycolic) acid (PLGA) nanoparticles (SubAB-PLGA NPs) increased intracellular uptake of SubAB and had an anti-inflammatory effect on macrophages. However, specific delivery of SubAB to macrophages could not be achieved because its effects on other cell types were not negligible. Therefore, to suppress non-specific SubAB binding, we used low-binding mutant SubABS35A (S35A) in which the 35th serine of the B subunit was mutated to alanine. In a macrophage cell line, PLGA NPs modified with S35A (S35A-PLGA NPs) induced ER stress and had anti-inflammatory effects similar to WT-PLGA NPs. However, in an epithelial cell line, S35A-PLGA NPs induced lower ER stress than WT-PLGA NPs. These results suggest that S35A is selectively delivered to macrophages rather than epithelial cells by modification with PLGA NPs and exerts anti-inflammatory effects. Our findings provide a useful technique for protein delivery to macrophages and encourage medical applications of DDSs for the treatment of inflammatory diseases.

Effect of Parylene C on the Corrosion Resistance of Bioresorbable Cardiovascular Stents Made of Magnesium Alloy 'Original ZM10'.

Magnesium (Mg) alloy has attracted significant attention as a bioresorbable scaffold for use as a next-generation stent because of its mechanical properties and biocompatibility. However, Mg alloy quickly degrades in the physiological environment. In this study, we investigated whether applying a parylene C coating can improve the corrosion resistance of a Mg alloy stent, which is made of 'Original ZM10', free of aluminum and rare earth elements. The coating exhibited a smooth surface with no large cracks, even after balloon expansion of the stent, and improved the corrosion resistance of the stent in cell culture medium. In particular, the parylene C coating of a hydrofluoric acid-treated Mg alloy stent led to excellent corrosion resistance. In addition, the parylene C coating did not affect a polymer layer consisting of poly(ε-caprolactone) and poly(D,L-lactic acid) applied as an additional coating for the drug release to suppress restenosis. Parylene C is a promising surface coating for bioresorbable Mg alloy stents for clinical applications.

Tailored Structure and Antibacterial Properties of Silica-Coated Silver Nanoplates by Pulsed Laser Irradiation.

We coated triangular-shaped silver nanoparticles, a type of anisotropic nanoplate (NPL), with silica (i.e., prepared Ag@SiO2 NPLs). When we irradiated Ag@SiO2 NPLs with nanosecond-pulsed laser light for 10 s, the triangular shape changed to spherical because of the photothermal effect. A high laser power exposed the silver core, and the particles exhibited strong antimicrobial activity. In contrast, at a moderate laser power, the silica layer crystallized, and the particles' antimicrobial activity decreased. Thus, a combination of Ag@SiO2 NPLs and an appropriately tuned power of pulsed laser irradiation facilitated a decreased or an increased antimicrobial activity.

Sirolimus Release from Biodegradable Polymers for Coronary Stent Application: A Review.

Drug-eluting stents (DESs) are commonly used for the treatment of coronary artery disease. The evolution of the drug-eluting layer on the surface of the metal stent plays an important role in DES functionality. Here, the use of biodegradable polymers has emerged as an attractive strategy because it minimizes the occurrence of late thrombosis after stent implantation. Furthermore, understanding the drug-release behavior of DESs is also important for improving the safety and efficacy of stent treatments. Drug release from biodegradable polymers has attracted extensive research attention because biodegradable polymers with different properties show different drug-release behaviors. Molecular weight, composition, glass transition temperature, crystallinity, and the degradation rate are important properties affecting the behavior of polymers. Sirolimus is a conventional anti-proliferation drug and is the most widely used drug in DESs. Sirolimus-release behavior affects endothelialization and thrombosis formation after DES implantation. In this review, we focus on sirolimus release from biodegradable polymers, including synthetic and natural polymers widely used in the medical field. We hope this review will provide valuable up-to-date information on this subject and contribute to the further development of safe and efficient DESs.

Photochemical OFF/ON Cytotoxicity Switching by Using a Photochromic Surfactant with Visible Light Irradiation.

Photochemical switching of cytotoxicity by using spiropyran compounds with pyridinium and alkyl groups was investigated. The spiropyran compound, SP6, with a hexyl group as the alkyl group displayed negative photochromism, in which the hydrophilic open merocyanine form (MC form) was stable and isomerized to the hydrophobic closed spiro form (SP form) by visible light irradiation. Both MC and SP forms exhibited amphiphilicity because of the hydrophobic hexyl and hydrophilic pyridinium groups introduced. Cytotoxicity toward HeLa cells was observed for both MC and SP forms of SP6 at concentrations higher than the critical aggregation concentration of the isomers CACMC and CACSP (CACMC > CACSP), respectively. In contrast, cytotoxicity by SP6 was activated by visible light irradiation at concentrations between CACMC and CACSP; thus, photochemical switching of cytotoxicity from the OFF to ON state was achieved. Cytotoxicity was revealed to be caused by disruption of the cell membrane. The results provide an important step in developing novel next-generation photochemotherapy drugs.

EPR-Effect Enhancers Strongly Potentiate Tumor-Targeted Delivery of Nanomedicines to Advanced Cancers: Further Extension to Enhancement of the Therapeutic Effect.

For more than three decades, enhanced permeability and retention (EPR)-effect-based nanomedicines have received considerable attention for tumor-selective treatment of solid tumors. However, treatment of advanced cancers remains a huge challenge in clinical situations because of occluded or embolized tumor blood vessels, which lead to so-called heterogeneity of the EPR effect. We previously developed a method to restore impaired blood flow in blood vessels by using nitric oxide donors and other agents called EPR-effect enhancers. Here, we show that two novel EPR-effect enhancers-isosorbide dinitrate (ISDN, Nitrol®) and sildenafil citrate-strongly potentiated delivery of three macromolecular drugs to tumors: a complex of poly(styrene-co-maleic acid) (SMA) and cisplatin, named Smaplatin® (chemotherapy); poly(N-(2-hydroxypropyl)methacrylamide) polymer-conjugated zinc protoporphyrin (photodynamic therapy and imaging); and SMA glucosamine-conjugated boric acid complex (boron neutron capture therapy). We tested these nanodrugs in mice with advanced C26 tumors. When these nanomedicines were administered together with ISDN or sildenafil, tumor delivery and thus positive therapeutic results increased two- to four-fold in tumors with diameters of 15 mm or more. These results confirmed the rationale for using EPR-effect enhancers to restore tumor blood flow. In conclusion, all EPR-effect enhancers tested showed great potential for application in cancer therapy.

[Drug Release System Controlled by Photothermal Effect of Gold Nanoparticles].

Controlled drug release in response to light irradiation is an important technique for focusing drug elution to specific sites and reducing the side effects of drugs in normal tissue. In one example, we used double-stranded DNA to modify gold nanorods. When the gold nanorods were heated by irradiation with near-infrared light, single-stranded DNA was released. Thus, we successfully prepared a controlled release system that responds to near-infrared irradiation by combining heat-labile linkers such as double-stranded DNA. However, the drug-loading capacity on the surface of the nanoparticles was limited. To improve the loading efficiency, we encapsulated gold nanorods in poly(lactic-co-glycolic acid) (PLGA) nanoparticles, where PLGA acted as a drug payload. When the gold nanorod-containing PLGA nanoparticles were irradiated with a near-infrared laser, the PLGA nanoparticles were destroyed and significant drug release was observed. In another example, silver nanoplates were used as a near-infrared responsive photothermal nanodevice. Silver nanoparticles show antimicrobial activity that we expected could be controlled by light irradiation. First, we coated the silver nanoplates with gold atoms to mask the antimicrobial activity. When the gold-coated silver nanoplates were irradiated with a near-infrared pulsed laser, the shape of the silver nanoplates changed from plate-like to spherical, and silver ions were released. As a result, the antibacterial activity of the silver nanoplates was recovered. In this review, we outline examples of controlled release systems that respond to light irradiation. We believe that this review will contribute to improving the efficiency and safety of chemotherapy.

Polymer-conjugated glucosamine complexed with boric acid shows tumor-selective accumulation and simultaneous inhibition of glycolysis.

We synthesized unique water-soluble synthetic-polymer, styrene-maleic acid copolymer (SMA) conjugated glucosamine (SG); which formed a stable complex with boric acid (BA). This complex had a mean particle size of 15 nm by light scattering, and single peak in gel permeation chromatography. The particles were taken up by tumor cells five times faster than free BA in vitro and liberated BA at acidic tumor pH (5-7). Liberated BA inhibited glycolysis and resulted in tumor suppression in vivo. Intravenously injected SGB-complex did bind with albumin, and plasma half-life was about 8 h in mice, and accumulated to tumor tissues about 10 times more than in normal organs. IC50 of SGB-complex for HeLa cells under pO2 of 6-9% was about 20 µg/ml (free BA equivalent), 150 times more potent than free BA. Neutron irradiation of human oral cancer cells with SGB-complex resulted in 16 times greater cell-killing than that without SGB-complex. In vivo antitumor effect was evaluated after neutron irradiation only once in SCC VII tumor bearing mice and significant tumor suppression was confirmed. These results indicate that SGB-complex is a unique multifunctional anticancer agent with much more potent activity under low pO2 conditions as in large advanced cancers.

pH-sensitive multi-drug liposomes targeting folate receptor ß for efficient treatment of non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is the leading cause of lung cancer-related deaths worldwide. Tumor-associated macrophages (TAMs), which can be polarized into tumor-promoting M2 phenotype, overexpress folate receptor beta (FRß) and are associated with poor prognosis in NSCLC. In addition, calpain-2 (CAPN2) is overexpressed in NSCLC and is involved in tumor growth. To improve the anticancer efficacy of drugs and reduce their side effects in the treatment of NSCLC, it is important to develop smart drug delivery systems with specific targeting ability and controlled release mechanisms. In this study, FRß-targeted pH-sensitive liposomes were designed as carriers to ensure efficient drug delivery and acid-responsive release in NSCLC cells. Folate-mediated targeting of FRß in M2 TAMs and NSCLC cells effectively inhibited tumor growth and the stimulus-responsive drug release reduced the toxic side effects of the drug. The combination of doxycycline (anti-CAPN2) and docetaxel (anticancer drug) showed a synergistic inhibitory effect on tumor growth by suppressing CAPN2 expression.

Effect of Surface Modifications on Cellular Uptake of Gold Nanorods in Human Primary Cells and Established Cell Lines.

Endocytosis is a cellular process in which substances are engulfed by the cellular membrane and budded off inside the cells to form vesicles. It plays key roles in controlling nutritional component uptake, immune responses, and other biological functions. A comprehensive understanding of endocytosis gives insights into such physiological functions and informs the design of medical nanodevices that need to enter cells. So far, endocytosis has been studied mostly using established cell lines. However, the established cell lines generally originate from cancer cells or are transformed from normal cells into immortalized cells. Therefore, primary cells may give us more reliable information about the endocytosis process of nanoparticles into cells. In this research, we studied the uptake of gold nanorods (AuNRs) with four different surface modifications (anionic/cationic polymers and anionic/cationic silica) by two kinds of primary cells (human monocyte-derived macrophages and human umbilical vein endothelial cells) and two kinds of established cell lines (HeLa cells and RAW 264.7 cells). We found that the surface properties of AuNRs affected their cellular uptake, and the cationic surface tended was advantageous for uptake, but it depended on the cell types. Control experiments using inhibitors of representative endocytosis pathways (macropinocytosis, clathrin-mediated endocytosis, and caveolae-mediated endocytosis) indicated that primary cells had a dominant uptake pathway for internalization of the AuNRs, whereas the established cell lines had multiple pathways. Our results provide us with novel insights into cellular uptake of AuNRs in that they depend not only on surface characters of the nanoparticles but also cell types, such as primary cells and established cell lines.

Development of ErbB2-Targeting Liposomes for Enhancing Drug Delivery to ErbB2-Positive Breast Cancer.

ErbB2 is a type of receptor tyrosine kinase, which is known to be involved in tumorigenesis, tumor aggressiveness, and clinical outcome. ErbB2-targeting therapy using therapeutic antibodies has been successful in breast cancer treatment. However, the need for repeated treatments and the high cost are major disadvantages with monoclonal antibody therapies. Compared with antibodies, peptides are cheap, relatively stable, and have low immunogenicity. We have developed a highly specific cancer-targeting drug delivery system using a targeting peptide to maximize the therapeutic efficiency of rapamycin and to help prevent drug resistance in ErbB2-positive breast cancer. Physicochemical characterization confirmed the successful construction of ErbB2-targeting liposomes (ErbB2Lipo). A comparison of a scrambled peptide (ScrErbB2) with the ErbB2-targeting peptide confirmed that these peptides had similar properties except for the targeting ability. The ErbB2Lipo exhibited higher delivery efficiency in ErbB2 positive BT-474 cells than non-targeting liposomes conjugated with ScrErbB2 (ScrErbB2Lipo). This peptide-targeting strategy has the potential to improve the efficacy of chemotherapy in ErbB2-positive cancers.

Preparation of Biodegradable PLGA-Nanoparticles Used for pH-Sensitive Intracellular Delivery of an Anti-inflammatory Bacterial Toxin to Macrophages.

Poly(D,L-lactide-co-glycolic) acid (PLGA) is a synthetic copolymer that has been used to design micro/nanoparticles as a carrier for macromolecules, such as protein and nucleic acids, that can be internalized by the endocytosis pathway. However, it is difficult to control the intracellular delivery to target organelles. Here we report an intracellular delivery system of nanoparticles modified with bacterial cytotoxins to the endoplasmic reticulum (ER) and anti-inflammatory activity of the nanoparticles. Subtilase cytotoxin (SubAB) is a bacterial toxin in certain enterohemorrhagic Escherichia coli (EHEC) strains that cleaves the host ER chaperone BiP and suppresses nuclear factor-kappaB (NF-κB) activation and nitric oxide (NO) generation in macrophages at sub-lethal concentration. PLGA-nanoparticles were modified with oligo histidine-tagged (6 × His-tagged) recombinant SubAB (SubAB-PLGA) through a pH-sensitive linkage, and their translocation to the ER in macrophage cell line J774.1 cells, effects on inducible NO synthase (iNOS), and levels of tumor necrosis factor (TNF)-α cytokine induced by lipopolysaccharide (LPS) were examined. Compared with free SubAB, SubAB-PLGA was significantly effective in BiP cleavage and the induction of the ER stress marker C/EBP homologous protein (CHOP) in J774.1 cells. Furthermore, SubAB-PLGA attenuated LPS-stimulated induction of iNOS and TNF-α. Our findings provide useful information for protein delivery to macrophages and may encourage therapeutic applications of nanoparticles to the treatment of inflammatory diseases.