The binding selectivity of quercetin and its structure-related polyphenols to human serum albumin using a fluorescent dye cocktail for multiplex drug-site mapping

Human serum albumin (HSA) is a serum protein that carries flavonoids in blood circulation. In this report, the binding selectivity and strength of interactions to HSA-binding sites (sites I or II) by flavonoids were evaluated using competition experiments and the specific fluorescent dyes, dansylamide and BD140. Most tested flavonoids bound site I preferentially, with the binding strength dependent on the mother structure in the order flavonol > flavone > flavanone > flavan 3-ols. Glycosylation or glucuronidation reduced the binding of quercetin to site I of HSA, whereas sulfation increased binding. Quercetin 7-sulfate showed the strongest binding and molecular docking simulations supported this observation. Prenylation at any position or glucuronidation and sulfation at the C-4' or C-7 position of quercetin facilitated stronger binding to site II. The binding affinity of flavonoids toward site I correlated with the partition coefficient value (logP), whereas no corresponding correlation was observed for site II.

Acute Kidney Injury Caused by Rhabdomyolysis Is Ameliorated by Serum Albumin-Based Supersulfide Donors through Antioxidative Pathways

Oxidative stress is responsible for the onset and progression of various kinds of diseases including rhabdomyolysis-induced acute kidney injury (AKI). Antioxidants are, therefore, thought to aid in the recovery of illnesses linked to oxidative stress. Supersulfide species have been shown to have substantial antioxidative activity; however, due to their limited bioavailability, few supersulfide donors have had their actions evaluated in vivo. In this study, human serum albumin (HSA) and N-acetyl-L-cysteine polysulfides (NACSn), which have polysulfides in an oxidized form, were conjugated to create a supersulfide donor. HSA is chosen to be a carrier of NACSn because of its extended blood circulation and high level of biocompatibility. In contrast to a supersulfide donor containing reduced polysulfide in HSA, the NACSn-conjugated HSAs exhibited stronger antioxidant activity than HSA and free NACSn without being uptaken by the cells in vitro. The supersulfide donor reduced the levels of blood urea nitrogen and serum creatinine significantly in a mouse model of rhabdomyolysis-induced AKI. Supersulfide donors significantly reduced the expression of oxidative stress markers in the kidney. These results indicate that the developed supersulfide donor has the therapeutic effect on rhabdomyolysis-induced AKI.

Peritoneal B Cells Play a Role in the Production of Anti-polyethylene Glycol (PEG) IgM against Intravenously Injected siRNA-PEGylated Liposome Complexes

Polyethylene glycol (PEG)-modified (PEGylated) cationic liposomes are frequently used as delivery vehicles for small interfering RNA (siRNA)-based drugs because of their ability to encapsulate/complex with siRNA and prolong the circulation half-life in vivo. Nevertheless, we have reported that subsequent intravenous (IV) injections of siRNA complexed with PEGylated cationic liposomes (PLpx) induces the production of anti-PEG immunoglobulin M (IgM), which accelerates the blood clearance of subsequent doses of PLpx and other PEGylated products. In this study, it is interesting that splenectomy (removal of spleen) did not prevent anti-PEG IgM induction by IV injection of PLpx. This indicates that B cells other than the splenic version are involved in anti-PEG IgM production under these conditions. In vitro and in vivo studies have shown that peritoneal cells also secrete anti-PEG IgM in response to the administration of PLpx. Interleukin-6 (IL-6) is a glycoprotein that is secreted by peritoneal immune cells and has been detected in response to the in vivo administration of PLpx. These observations indicate that IV injection of PLpx stimulates the proliferation/differentiation of peritoneal PEG-specific B cells into plasma cells via IL-6 induction, which results in the production of anti-PEG IgM from the peritoneal cavity of mice. Our results suggest the mutual contribution of peritoneal B cells as a potent anti-PEG immune response against PLpx.

[Characterization of Supersulfide in Serum Albumin and Its Therapeutic Application]

Recent studies have shown that proteins already possess supersulfides during the translation. However, the distribution and the role of supersulfides are not fully understood. In this review, we focus on supersulfides in biological fluids, especially in serum. Various methods for measuring supersulfides have been developed, and these methods have elucidated the presence of supersulfides in serum proteins including serum albumin. Since the levels of supersulfides in serum and serum albumin of patients with chronic kidney disease were lower than those in healthy subjects and recovered by hemodialysis, the levels of supersulfides in serum would be an indicator reflecting oxidative stress. In addition, it has long been known that serum albumin is responsible for sulfur transference. We have applied this phenomenon to the synthesis of sulfur-added albumin (Sn-HSA) by the reaction of serum albumin with sodium polysulfide (Na2Sn). Sn-HSA suppressed the melanin production via scavenging oxidative stress. As described above, studies on the characterization of supersulfides in serum albumin may contribute to the monitoring of redox balance and prevention of oxidative stress-related diseases.

Carbon Monoxide Alleviates Post-ischemia-reperfusion Skeletal Muscle Injury and Systemic Inflammation

Restoration of blood flow in skeletal muscle after a prolonged period of ischemia induces muscular ischemia-reperfusion injury, leading to local injury/dysfunction in muscles followed by systemic inflammatory responses. However, preventive/curative agents for skeletal muscle ischemia injury are unavailable in clinics to date. Increasing evidence has validated that carbon monoxide (CO) prevents the progression of ischemia-reperfusion injury in various organs owing to its versatile bioactivity. Previously, we developed a bioinspired CO donor, CO-bound red blood cells (CO-RBC), which mimics the dynamics of RBC-associated CO in the body. In the present study, we have tested the therapeutic potential of CO-RBC in muscular injury/dysfunction and secondary systemic inflammation induced by skeletal muscle ischemia-reperfusion. The results indicate that CO-RBC rather than RBC alone suppressed elevation of plasma creatine phosphokinase, a marker of muscular injury, in rats subjected to both hind limbs ischemia-reperfusion. In addition, the results of the treadmill walking test revealed a significantly decreased muscular motor function in RBC-treated rats subjected to both hind limbs ischemia-reperfusion than that in healthy rats, however, CO-RBC treatment facilitated sustained muscular motor functions after hind limbs ischemia-reperfusion. Furthermore, CO-RBC rather than RBC suppressed the production of tumour necrosis factor (TNF)-α and interleukin (IL)-6, which were upregulated by muscular ischemia-reperfusion. Interestingly, CO-RBC treatment induced higher levels of IL-10 compared to saline or RBC treatments. Based on these findings, we suggest that CO-RBC exhibits a suppressive effect against skeletal muscle injury/dysfunction and systemic inflammatory responses after skeletal muscle ischemia-reperfusion.

Encapsulation of an Antioxidant in Redox-Sensitive Self-Assembled Albumin Nanoparticles for the Treatment of Hepatitis

Hepatitis is an inflammation of the liver caused by the inadequate elimination of reactive oxygen species (ROS) derived from Kupffer cells. Edaravone is clinically used as an antioxidant but shows poor liver distribution. Herein, we report on the design of a Kupffer cell-oriented nanoantioxidant based on a disulfide cross-linked albumin nanoparticle containing encapsulated edaravone (EeNA) as a therapeutic for the treatment of hepatitis. Since the edaravone is bound to albumin, this results in a soluble and stable form of edaravone in water. Exchanging the intramolecular disulfide bonds to intermolecular disulfide bridges of albumin molecules allowed the preparation of a redox responsive albumin nanoparticle that is stable in the blood circulation but can release drugs into cells. Consequently, EeNA was fabricated by the nanoscale self-assembly of edaravone and albumin nanoparticles without the additives that are contained in commercially available edaravone preparations. EeNA retained its nanostructure under serum conditions, but the encapsulated edaravone was released efficiently under intracellular reducing conditions in macrophages. The EeNA was largely distributed in the liver and subsequently internalized into Kupffer cells within 60 min after injection in a concanavalin-A-induced hepatitis mouse. The survival rate of the hepatitis mice was significantly improved by EeNA due to the suppression of liver necrosis and oxidative stress by scavenging excessive ROS. Moreover, even through the postadministration, EeNA showed an excellent hepatoprotective action as well. In conclusion, EeNA has the potential for use as a nanotherapeutic against various types of hepatitis because of its Kupffer cell targeting ability and redox characteristics.

Anti-PEG IgM production induced by PEGylated liposomes as a function of administration route

Modifying the surface of nanoparticles with polyethylene glycol (PEG) is a commonly used approach for improving the in vitro stability of nanoparticles such as liposomes and increasing their circulation half-lives. We have demonstrated that, in certain conditions, an intravenous (i.v.) injection of PEGylated liposomes (PEG-Lip) induced anti-PEG IgM antibodies, which led to rapid clearance of second doses in mice. SARS-CoV-2 vaccines, composed of mRNA-containing PEGylated lipid nanoparticles, have been widely administered as intramuscular (i.m.) injections, so it is important to determine if PEGylated formulations can induce anti-PEG antibodies. If the favorable properties that PEGylation imparts to therapeutic nanoparticles are to be widely applicable this should apply to various routes of administration. However, there are few reports on the effect of different administration routes on the in vivo production of anti-PEG IgM. In this study, we investigated anti-PEG IgM production in mice following i.m., intraperitoneal (i.p.) and subcutaneous (s.c.) administration of PEG-Lip. PEG-Lip appeared to induce anti-PEG IgM by all the tested routes of administration, although the lipid dose causing maximum responses varied. Splenectomy attenuated the anti-PEG IgM production for all routes of administration, suggesting that splenic immune cells may have contributed to anti-PEG IgM production. Interestingly, in vitro experiments indicated that not only splenic cells but also cells in the peritoneal cavity induced anti-PEG IgM following incubation with PEG-Lip. These observations confirm previous experiments that have shown that measurable amounts of PEG-Lip administered i.p., i.m. or s.c. are absorbed to some extent into the blood circulation, where they can be distributed to the spleen and/or peritoneal cavity, and are recognized by B cells, triggering anti-PEG IgM production. The results obtained in this study have important implications for developing efficient PEGylated nanoparticular delivery system.

Effectiveness of Albumin-Fused Thioredoxin against 6-Hydroxydopamine-Induced Neurotoxicity In Vitro

Parkinson's disease (PD) is a neurodegenerative disorder caused by oxidative stress-dependent loss of dopaminergic neurons in the substantia nigra and elevated microglial inflammatory responses. Recent studies show that cell loss also occurs in the hypothalamus in PD. However, effective treatments for the disorder are lacking. Thioredoxin is the major protein disulfide reductase in vivo. We previously synthesized an albumin-thioredoxin fusion protein (Alb-Trx), which has a longer plasma half-life than thioredoxin, and reported its effectiveness in the treatment of respiratory and renal diseases. Moreover, we reported that the fusion protein inhibits trace metal-dependent cell death in cerebrovascular dementia. Here, we investigated the effectiveness of Alb-Trx against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in vitro. Alb-Trx significantly inhibited 6-OHDA-induced neuronal cell death and the integrated stress response. Alb-Trx also markedly inhibited 6-OHDA-induced reactive oxygen species (ROS) production, at a concentration similar to that inhibiting cell death. Exposure to 6-OHDA perturbed the mitogen-activated protein kinase pathway, with increased phosphorylated Jun N-terminal kinase and decreased phosphorylated extracellular signal-regulated kinase levels. Alb-Trx pretreatment ameliorated these changes. Furthermore, Alb-Trx suppressed 6-OHDA-induced neuroinflammatory responses by inhibiting NF-κB activation. These findings suggest that Alb-Trx reduces neuronal cell death and neuroinflammatory responses by ameliorating ROS-mediated disruptions in intracellular signaling pathways. Thus, Alb-Trx may have potential as a novel therapeutic agent for PD.

Ionic Liquid-Based Transcutaneous Peptide Antitumor Vaccine: Therapeutic Effect in a Mouse Tumor Model

Traditional vaccinations need to be injected with needles, and since some people have a strong aversion to needles, a needle-free alternative delivery system is important. In this study, we employed ionic liquids (ILs) for transcutaneous delivery of cancer antigen-derived peptides to obtain anticancer therapeutic effects in a needle-free manner. ILs successfully increased the in vitro skin permeability of a peptide from Wilms tumor 1 (WT1), one of the more promising cancer antigens, plus or minus an adjuvant, resiquimod (R848), a toll-like receptor 7 agonist. In vivo studies demonstrated that concomitant transcutaneous delivery of WT1 peptide and R848 by ILs induced WT1-specific cytotoxic T lymphocyte (CTL) in mice, resulting in tumor growth inhibition in Lewis lung carcinoma-bearing mice. Interestingly, administrating R848 in ILs before WT1 peptides in ILs increased tumor growth inhibition effects compared to co-administration of both. We found that the prior application of R848 increased the infiltration of leukocytes in the skin and that subsequent delivery of WT1 peptides was more likely to induce WT1-specific CTL. Furthermore, sequential immunization with IL-based formulations was applicable to different types of peptides and cancer models without induction of skin irritation. IL-based transcutaneous delivery of cancer antigen-derived peptides and adjuvants, either alone or together, could be a novel approach to needle-free cancer therapeutic vaccines.

Investigation of anti-PEG antibody response to PEG-containing cosmetic products in mice

Polyethylene glycol (PEG), a polyether compound, is available in molecular weights from ∼300 g/mol to ∼10,000,000 g/mol. In the molecular weight range of ∼750 to ∼5000, PEG is commonly used in bioconjugation technology and nano-formulations to improve the circulation half-life of the formulations and increase their stability. In cosmetics, lower molecular weight PEG compounds such as PEG 60 or PEG 100 are widely used as emulsifiers and skin penetration enhancers. PEG polymers are generally recognized as biologically inert and non-immunogenic. However, it is recently reported that the "pre-existing" anti-PEG antibodies have been detected in high percentages of healthy individuals who have never received treatment with parenteral PEGylated formulations. To the best of our knowledge, we are the first to attempt to find an explanation for the source of pre-existing anti-PEG antibodies in healthy individuals. In a murine study, we demonstrated that topically applied PEG derivatives, present in two commercially available cosmetic products, could efficiently penetrate the stratum corneum and reach the systemic circulation. The skin penetration of PEG derivatives was further enhanced in injured or otherwise compromised skin. Daily application of cosmetic PEG derivatives primed the immune system, inducing anti-PEG IgM production. Anti-PEG IgM was detected by Day 14 in mice with normal skin, while anti-PEG IgM was detected as early as day 7 in mice with compromised skin. In addition, in mice with pre-induced circulating levels of anti-PEG IgM, topically applied PEG derivatives from cosmetic products appeared to bind to the pre-induced anti-PEG IgM, lowering blood levels. Current results indicate that PEG derivatives in cosmetic products may be an important contributor to the source of the "pre-existing" anti-PEG antibodies that have been detected in healthy individuals.

A Maleimide-Terminally Modified PEGylated Liposome Induced the Accelerated Blood Clearance Independent of the Production of Anti-PEG IgM Antibodies

PEGylated liposomes (PL) lose their long-circulating characteristic when administered repeatedly, called the accelerated blood clearance (ABC) phenomenon. The ABC phenomenon is generally thought to occur when the anti-polyethylene glycol (PEG) antibody (anti-PEG immunoglobulin M (IgM)) expressed in the spleen B cells triggered by the first dose of PL binds to the second and subsequent doses of PL, leading to activation of the complement system. MAL-PEG-DSPE, a PEG lipid with a maleimide (MAL) group at the PEG terminal, is used in various studies as a linker for ligand-bound liposomes such as antibody-modified liposomes. However, most ABC phenomenon research used PL with a terminal methoxy group (PL-OCH₃). In this study, we prepared MAL-PEG-DSPE liposomes (PL-MAL) to evaluate the effect of PL-MAL on the ABC phenomenon induction compared to PL-OCH₃. Pharmacokinetic, anti-PEG IgM secretion and complement activation analyses of these liposomes were conducted in mice. Interestingly, despite C3 bound to the surface of the initially administered PL-MAL, the administered PL-MAL showed high blood retention, demonstrating the same results as PL-OCH₃. On the other hand, although the secretion of anti-PEG IgM induced by PL-MAL was lower than PL-OCH₃, the second dose of PL-MAL rapidly disappeared from the blood. These results suggest that the antibody produced from the first dose of PL-MAL binds to the second dose of PL-MAL, thereby activating C3 to act as an opsonin which promotes phagocytic uptake. In conclusion, PL-MAL induced the ABC phenomenon independent of the production of IgM antibodies against PEG. This study provides valuable findings for further studies using ligand-bound liposomes.

Novel nitric oxide donor, nitrated phenylbutyrate, induces cell death of human pancreatic cancer cells and suppresses tumor growth of cancer xenografts

Pancreatic cancer has a low response rate to chemotherapy due to the low drug transferability caused by the low blood flow around the tumor. In the present study, focusing on nitric oxide (NO) for its vasodilatory and antitumor effects, a novel NO donor, a nitrated form of phenylbutyrate (NPB) was synthesized and the antitumor effect on human pancreatic cancer cells (AsPC1 and BxPC3) and xenografts was examined. Using Annexin V, NPB was confirmed to induce cell death against AsPC1 and BxPC3 in a time‑ and concentration‑dependent manner. In NPB‑exposed cells, DAF‑FM DA (a probe to detect intracellular NO) derived fluorescence was observed. Release of nitrite and nitrate from NPB in aqueous solution was very gradual until even 72 h after dissolution. Phenylbutyrate (PB) and hydroxy PB in which the nitro group of NPB was replaced with a hydroxyl group did not have the cell death‑inducing effect as observed in NPB. These results suggest that the effect of NPB was dependent on NO release form NPB. Apoptosis inhibitor, Z‑VAD FMK, had no effect on the cell death‑inducing effect of NPB, and NPB did not show significant activation of caspase‑3/7. In addition, NPB significantly decreased cellular ATP levels, suggesting that necrosis is involved in the effect of NPB. NPB also accumulated cells specifically at the S phase of the cell cycle. A single dose of NPB (10 mg/kg) into mice with established BxPC3 xenografts significantly suppressed tumor growth for at least 7 weeks without apparent toxicity. The findings of the present study indicate that NPB has potential as a novel therapeutic agent for NO‑based therapy of pancreatic cancer.

Polyethylene glycol (PEG): The nature, immunogenicity, and role in the hypersensitivity of PEGylated products

Polyethylene glycol (PEG) is a versatile polymer that is widely used as an additive in foods and cosmetics, and as a carrier in PEGylated therapeutics. Even though PEG is thought to be less immunogenic, or perhaps even non-immunogenic, with a variety of physicochemical properties, there is mounting evidence that PEG causes immunogenic responses when conjugated with other materials such as proteins and nanocarriers. Under these conditions, PEG with other materials can result in the production of anti-PEG antibodies after administration. The antibodies that are induced seem to have a deleterious impact on the therapeutic efficacy of subsequently administered PEGylated formulations. In addition, hypersensitivity to PEGylated formulations could be a significant barrier to the utility of PEGylated products. Several reports have linked the presence of anti-PEG antibodies to incidences of complement activation-related pseudoallergy (CARPA) following the administration of PEGylated formulations. The use of COVID-19 mRNA vaccines, which are composed mainly of PEGylated lipid nanoparticles (LNPs), has recently gained wide acceptance, although many cases of post-vaccination hypersensitivity have been documented. Therefore, our review focuses not only on the importance of PEGs and its great role in improving the therapeutic efficacy of various medications, but also on the hypersensitivity reactions attributed to the use of PEGylated products that include PEG-based mRNA COVID-19 vaccines.

Development of a Nanocarrier-Based Splenic B Cell-Targeting System for Loading Antigens in Vitro

B cells are types of lymphocytes that are involved in the production of antibodies against pathogens. They also deliver and present antigens for the priming of T cells. Recently, we developed an in vivo splenic marginal zone (MZ) B cell-targeting liposomes decorated with polyethylene glycol (PEG) containing a hydroxyl-terminus group (HO-PEG-Lip). In an expansion of a previous study, we used HO-PEG-Lip as an in vitro antigen delivery tool to splenic B cells to test the ability of this formulation to overcome the limitations of the poor antigen uptake ability of B cells for implantation. To achieve our purpose, various factors were optimized. These factors include cell number, liposome concentration, pre-opsonization of liposomes, fresh serum concentration, and incubation time, all of which affect the extent of interaction between liposomes and B cells. As a result, we confirmed that the HO-PEG-Lip required incubation at 37 °C for at least 20 min with 50% mouse fresh serum followed by a subsequent incubation at 37 °C for at least another 30 min with splenic B cells. By using such a loading system, fluorescein isothiocyanate (FITC)-labeled ovalbumin (OVA), a model antigen, encapsulated in HO-PEG-Lip could be efficiently loaded into splenic B cells. In addition, HO-PEG-Lip and FITC-labeled OVA encapsulated in HO-PEG-Lip were efficiently associated with MZ-B cells with high levels of complement receptors (CRs) rather than follicular B cells with low levels of CRs. These results propose a novel and useful system to efficiently load antigens into B cells in vitro by taking advantage of complement systems.

8-Prenylnaringenin tissue distribution and pharmacokinetics in mice and its binding to human serum albumin and cellular uptake in human embryonic kidney cells

8-Prenylnaringenin (8-PN), a hop flavonoid, is a promising food substance with health benefits. Compared with nonprenylated naringenin, 8-PN exhibits stronger estrogenic activity and prevents muscle atrophy. Moreover, 8-PN prevents hot flushes and bone loss. Considering that prenylation reportedly improves the bioavailability of flavonoids, we compared the parameters related to the bioavailability [pharmacokinetics and tissue distribution in C57/BL6 mice, binding affinity to human serum albumin (HSA), and cellular uptake in HEK293 cells] of 8-PN and its mother (non-prenylated) compound naringenin. C57/BL6 mice were fed an 8-PN or naringenin mixed diet for 22 days. The amount of 8-PN (nmol/g tissue) in the kidneys (16.8 ± 9.20), liver (14.8 ± 2.58), muscles (3.33 ± 0.60), lungs (2.07 ± 0.68), pancreas (1.80 ± 0.38), heart (1.71 ± 0.27), spleen (1.36 ± 0.29), and brain (0.31 ± 0.09) was higher than that of naringenin. A pharmacokinetic study in mice demonstrated that the C _max of 8-PN (50 mg/kg body weight) was lower than that of naringenin; however, the plasma concentration of 8-PN 8 h after ingestion was higher than that of naringenin. The binding affinity of 8-PN to HSA and cellular uptake in HEK293 cells were higher than those of naringenin. 8-PN bioavailability features assessed in mouse or human model experiments were obviously different from those of naringenin.

A mouse model for studying the effect of blood anti-PEG IgMs levels on the in vivo fate of PEGylated liposomes

The presence of anti-polyethylene glycol (PEG) antibodies in the systemic circulation might have potential implications for the therapeutic activity of PEGylated products in vivo in the clinic. In order to study the effect of pre-existing anti-PEG antibodies on the in vivo fate and the therapeutic efficiency of PEGylated therapeutics, we developed a BALB/c mouse model by virtue of the intraperitoneal (i.p.) inoculation of hybridoma cells (HIK-M09 and HIK-M11), secreting monoclonal anti-PEG IgM, mimicking the presence of pre-existing anti-PEG antibodies in the blood. In the model, the titers of anti-PEG IgM in the blood increased as a function of hybridoma cells numbers and time after i.p. inoculation. The in vivo levels of anti-PEG IgM decreased in a dose-dependent manner, following i.v. administration of empty PEGylated liposomes. C26 tumor-bearing mice with measurable levels of anti-PEG IgM, receiving i.v. injection of DiR-labeled empty PEGylated liposomes, showed lower levels of liposomal tumor accumulation and higher levels of liver and spleen accumulation, compared to C26 tumor-bearing mice without measurable anti-PEG IgM. This specifies that the presence of anti-PEG IgM in the murine circulation induced accelerated blood clearance of PEGylated liposomes and reduced their tumor accumulation. The biodistribution and antitumor efficacy of commercially available doxorubicin (DXR)-containing PEGylated liposomes, Doxil®, were scrutinized in the anti-PEG IgM mouse model. In C26 tumor-bearing mice having circulating anti-PEG IgM, at 24 h after injection almost no DXR was observed in blood and tumor, and increased DXR accumulation was observed in spleen and liver, compared to tumor-bearing mice with no circulating anti-PEG IgM. The antitumor efficacy of Doxil® was significantly compromised in the C26 tumor-bearing mice in the presence of anti-PEG IgM. These results demonstrate that the anti-PEG IgM mouse model could be a useful prognostic indicator for the therapeutic effectiveness of different formulations of PEGylated therapeutics in pre-clinical studies.

Using Bio-Layer Interferometry to Evaluate Anti-PEG Antibody-Mediated Complement Activation

The purpose of this study was to develop a Bio-layer interferometry (BLI) system that could be an alternative approach for the direct evaluation of anti-polyethylene glycol (PEG) immunoglobulin M (IgM)-mediated complement activation of the accelerated blood clearance (ABC) phenomenon. Complement activation is well known to play an important role in the clearance of PEGylated and non-PEGylated nanomedicines following intravenous injection. This complement system is also thought to be responsible for the ABC phenomenon wherein repeated injections of PEGylated products are bound by anti-PEG antibodies. This study used three different sources of anti-PEG antibodies: HIK-M09 monoclonal antibodies (mAbs); HIK-M11 mAbs; and antiserum containing polyclonal anti-PEG IgMs. 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-n-[methoxy (polyethylene glycol)-2000] (mPEG₂₀₀₀-DSPE) was immobilized as an antigen on aminopropyl silane biosensor chips of BLI. All anti-PEG IgMs in the sources increased the signals (thickness of the layer around the sensor tip) regarding binding of anti-PEG antibodies to PEG on the chips. In all anti-PEG IgM sources, further increases in the signals were observed when incubated in naïve mouse serum, which is a complement source, but not in heat inactivated (56 °C, 30 min) mouse serum, which abolishes complement activity. These findings show that the complement activation mediated via anti-PEG IgMs, which occurred on the sensor chips, was detected via BLI analysis. The complement activation induced by all anti-PEG IgM sources was confirmed via conventional enzyme-linked immunosorbent assay (ELISA), which is the conventional mode for detection of complement activation. Our study results show that BLI is a simple alternative method for the detection of complement activation.

Nitric oxide facilitates the targeting Kupffer cells of a nano-antioxidant for the treatment of NASH

Kupffer cells are a key source of reactive oxygen species (ROS) and are implicated in the development of steatohepatitis and fibrosis in nonalcoholic steatohepatitis (NASH). We recently developed a polythiolated and mannosylated human serum albumin (SH-Man-HSA), a nano-antioxidant that targets Kupffer cells, in which the mannosyl units on albumin allows their specific uptake by Kupffer cells via the mannose receptor C type 1 (MRC1), and in which the polythiolation confers antioxidant activity. The aim of this study was to investigate the therapeutic potential of SH-Man-HSA in NASH model mice. In livers from mice and/or patients with NASH, we observed a reduced blood flow in the liver lobes and the down-regulation in MRC1 expression in Kupffer cells, and SH-Man-HSA alone failed to improve the pathological phenotype in NASH. However, the administration of a nitric oxide (NO) donor restored hepatic blood flow and increased the expression of the mannose receptor C type 2 (MRC2) instead of MRC1. Consequently, treatment with a combination of SH-Man-HSA and an NO donor improved oxidative stress-associated pathology. Finally, we developed a hybrid type of nano-antioxidant (SNO-Man-HSA) via the S-nitrosation of SH-Man-HSA. This nanomedicine efficiently delivered both NO and thiol groups to the liver, with a hepatoprotective effect that was comparable to the combination therapy of SH-Man-HSA and an NO donor. These findings suggest that SNO-Man-HSA has the potential for functioning as a novel nano-therapy for the treatment of NASH.

The Therapeutic Effect of Human Serum Albumin Dimer-Doxorubicin Complex against Human Pancreatic Tumors

Human serum albumin (HSA) is a versatile drug carrier with active tumor targeting capacity for an antitumor drug delivery system. Nanoparticle albumin-bound (nab)-technology, such as nab-paclitaxel (Abraxane^®), has attracted significant interest in drug delivery research. Recently, we demonstrated that HSA dimer (HSA-d) possesses a higher tumor distribution than HSA monomer (HSA-m). Therefore, HSA-d is more suitable as a drug carrier for antitumor therapy and can improve nab technology. This study investigated the efficacy of HSA-d-doxorubicin (HSA-d-DOX) as next-generation nab technology for tumor treatment. DOX conjugated to HSA-d via a tunable pH-sensitive linker for the controlled release of DOX. Lyophilization did not affect the particle size of HSA-d-DOX or the release of DOX. HSA-d-DOX showed significantly higher cytotoxicity than HSA-m-DOX in vitro. In the SUIzo Tumor-2 (SUIT2) human pancreatic tumor subcutaneous inoculation model, HSA-d-DOX could significantly inhibit tumor growth without causing serious side effects, as compared to the HSA binding DOX prodrug, which utilized endogenous HSA as a nano-drug delivery system (DDS) carrier. These results indicate that HSA-d could function as a natural solubilizer of insoluble drugs and an active targeting carrier in intractable tumors with low vascular permeability, such as pancreatic tumors. In conclusion, HSA-d can be an effective drug carrier for the antitumor drug delivery system against human pancreatic tumors.

Reduction-Responsive and Multidrug Deliverable Albumin Nanoparticles: An Antitumor Drug to Abraxane against Human Pancreatic Tumor-Bearing Mice

Many macromolecular antitumor drugs were developed based on the enhanced permeability and retention (EPR) effect, for example, albumin-bound paclitaxel nanoparticles (nab-PTX and Abraxane) and pegylated liposomal doxorubicin (Doxil). However, these EPR effect-based therapeutic systems are less effective in malignant tumors with low vascular permeability, such as pancreatic tumors. Because the EPR effect depends on nanoparticles' size, we first determined nanoparticles' size associated with a high tumor-targeting rate in a human pancreatic tumor xenograft model with low vascular permeability. Abraxane appears to behave as an albumin monomer (7 nm) in the blood circulation following intravenous injection. The in vitro and in vivo tumor-targeted delivery and antitumor activity of PTX-loaded albumin nanoparticles were significantly improved by optimizing the mean nanoparticle diameter to 30 nm. Furthermore, nitric oxide was added to 30 nm PTX-loaded albumin nanoparticles to examine the feasibility of albumin nanoparticles as a platform for multiple drug delivery. Their antitumor effect was evaluated in an orthotopic transplantation mouse model of a human pancreatic tumor. The nitric oxide PTX-loaded 30 nm albumin nanoparticle treatment on model mice achieved a significantly higher survival rate than Abraxane treatment. These findings suggest that 30 nm albumin nanoparticles have a high therapeutic effect as a useful platform for multiple drugs against human pancreatic tumors.

Evidence for Delivery of Abraxane via a Denatured-Albumin Transport System

Abraxane, an albumin-bound paclitaxel nanoparticle formulation, is superior to conventional paclitaxel preparations because it has better efficacy against unresectable pancreatic cancer. Previous reports suggest that this better efficacy of Abraxane than conventional paclitaxel preparation is probably due to its transport through Gp60, an albumin receptor on the surface of vascular endothelial cells. The increased tumor accumulation of Abraxane is also caused by the secreted protein acid and rich in cysteine in the tumor stroma. However, the uptake mechanism of Abraxane remains poorly understood. In this study, we demonstrated that the delivery of Abraxane occurred via different receptor pathways from that of endogenous albumin. Our results showed that the uptake of endogenous albumin was inhibited by a Gp60 pathway inhibitor in the process of endocytosis through endothelial cells or tumor cells. In contrast, the uptake of Abraxane-derived HSA was less affected by the Gp60 pathway inhibitor but significantly reduced by denatured albumin receptor inhibitors. In conclusion, these data indicate that Abraxane-derived HSA was taken up into endothelial cells or tumor cells by a mechanism different from normal endogenous albumin. These new data on distinct cellular transport pathways of denatured albumin via gp family proteins different from those of innate albumin shed light on the mechanisms of tumor delivery and antitumor activity of Abraxane and provide new scientific rationale for the development of a novel albumin drug delivery strategy via a denatured albumin receptor.

Anti-PEG IgM production and accelerated blood clearance phenomenon after the administration of PEGylated exosomes in mice

Recently, there is an increasing interest in exosomes or extracellular vesicles as potential candidates for delivering RNAs, proteins, genes, and anticancer agents. Engineering of exosome properties is rapidly evolving as a means of expanding exosome applications. PEGylation of exosomes is a technique used to improve their in vivo stability, circulation half-lives, and sometimes to allow the binding targeting ligands to the exosome exterior. According to FDA guidelines for the development of PEGylated proteins, immunological responses to PEGylated molecules and particles should be examined. In this study, we prepared PEGylated exosomes and investigated the production of anti-PEG IgM antibodies after single i.v. injections in mice. In addition, we monitored blood concentrations and tumor accumulation of a second dose of PEGylated exosomes administered after the initial dose. Single injections of PEGylated exosomes in mice induced anti-PEG IgM production in a T cell-dependent manner. The anti-PEG IgM production decreased when the injection dose of PEGylated exosomes was further increased. Anti-PEG IgM induced by injection of PEGylated exosomes decreased blood concentrations of a second dose of PEGylated exosomes and suppressed their tumor accumulation in a C26 murine colorectal cancer model. Initial injection doses of either PEGylated liposomes or PEGylated ovalbumin (PEG-OVA), both of them induced anti-PEG IgM production, also decreased the blood concentration of PEGylated exosomes. Interestingly, anti-PEG IgM induced by injection of PEGylated exosomes did not affect the blood concentration of PEG-OVA. These results imply the importance of monitoring anti-PEG IgM when repeat PEGylated exosome doses are required and/or when PEGylated exosomes are used together with other PEGylated therapeutics.

Incorporating Gangliosides into PEGylated Cationic Liposomes that Complexed DNA Attenuates Anti-PEG Antibody Production but Not Anti-DNA Antibody Production in Mice

Gangliosides (glycosphingolipids) reduce antibody production by inhibiting B-cell receptor (BCR) signaling. We have shown that a copresentation of gangliosides and polyethylene glycol (PEG) on the same liposomes suppresses anti-PEG IgM production in mice. In addition, we recently observed that pDNA incorporated in PEGylated cationic liposomes (PCLs) induces anti-DNA IgM, which could be a hurdle to the development of efficient gene delivery systems. Therefore, the focus of this study was to determine if the copresentation of gangliosides and DNA on the same PCL would suppress antibody production against DNA. PCLs including DNA induced both anti-PEG IgM production and anti-DNA IgM production. The extent of anti-PEG and anti-DNA IgM production was likely dependent on the immunogenicity of the complexed DNA. Treatment of clodronate-containing liposomes, which causes a depletion of phagocytic cells, suppressed anti-PEG IgM production from PCLs that did not include DNA but failed to suppress anti-PEG IgM production from PCLs that complexed DNA (PCLD). Both anti-PEG IgM and anti-DNA IgM was induced in T-cell-deficient nude mice as well as in normal mice following treatment with PCLs and PCLD, respectively. These results indicate that phagocytic cells contribute to anti-PEG IgM production but not to anti-DNA IgM production, while T-cells do not contribute to any form of antibody production. The copresentation of gangliosides and DNA significantly reduced anti-PEG IgM production but unfortunately did not reduce anti-DNA IgM production. It appears that the immunosuppressive effect of gangliosides, presumably via the CD22 signaling pathway, is limited only to anti-PEG immunity.

Nucleic acids delivered by PEGylated cationic liposomes in systemic lupus erythematosus-prone mice: A possible exacerbation of lupus nephritis in the presence of pre-existing anti-nucleic acid antibodies

Nucleic acid-based therapy with plasmid DNA (pDNA) and small interfering RNA (siRNA) have received recent attention for their ability to modulate the cellular expression of genes and proteins. Polyethylene glycol-modified (PEGylated) cationic nanoparticles have been used as non-viral vectors for the in vivo delivery of these nucleic acids. We have reported that PEGylated cationic liposomes (PCL) including pDNA or siRNA induce anti-PEG antibodies upon repeated intravenous injection, leading to the formation of immune complexes and enhanced clearance from the blood of subsequent doses. However, the issue surrounding the association of nucleic acids with PCL whether induces anti-nucleic acid antibodies has not been studied. Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with the character of end-organ damage and the presence of anti-nuclear antibodies. We used a healthy mouse and an SLE mouse model to test the hypothesis that nucleic acids associated with PCL induce anti-nuclear antibodies and then induce SLE and exacerbate SLE symptoms. We report here that pDNA or siRNA associated with PCL (pDNA/PCL or siRNA/PCL) induced anti-DNA or RNA antibodies, respectively, in healthy mice. Repeated injections did not, however, cause SLE-like symptoms in the healthy mice. In addition, in SLE-prone mice with pre-existing anti-nuclear antibodies, pDNA/PCL were deposited on the kidneys and exacerbated lupus nephritis subsequent to the formation of immune complexes. These results may imply that nucleic acids associated with PCL do not contribute to the onset of SLE in healthy individuals who lack anti-nuclear antibodies, but nucleic acids may exacerbate the symptoms in SLE patients who have pre-existing anti-nuclear antibodies.

Increasing Tumor Extracellular pH by an Oral Alkalinizing Agent Improves Antitumor Responses of Anti-PD-1 Antibody: Implication of Relationships between Serum Bicarbonate Concentrations, Urinary pH, and Therapeutic Outcomes

Acidic extracellular pH (pHe) is characteristic of the tumor microenvironment. Several reports suggest that increasing pHe improves the response of immune checkpoint inhibitors in murine models. To increase pHe, either sodium bicarbonate (NaHCO3) or citric acid/potassium-sodium citrate (KNa-cit) was chronically administered to mice. It is hypothesized that bicarbonate ions (HCO3-), produced from these alkalinizing agents in vivo, increased pHe in the tumor, and excess HCO3- eliminated into urine increased urinary pH values. However, there is little published information on the effect of changing serum HCO3- concentrations, urinary HCO3- concentrations and urinary pH values on the therapeutic outcomes of immunotherapy. In this study, we report that oral administration of either NaHCO3 or KNa-cit increased responses to anti-programmed cell death-1 (PD-1) antibody, an immune checkpoint inhibitor, in a murine B16 melanoma model. In addition, we report that daily oral administration of an alkalinizing agent increased blood HCO3- concentrations, corresponding to increasing the tumor pHe. Serum HCO3- concentrations also correlated with urinary HCO3- concentrations and urinary pH values. There was a clear relationship between urinary pH values and the antitumor effects of immunotherapy with anti-PD-1 antibody. Our results imply that blood HCO3- concentrations, corresponding to tumor pHe and urinary pH values, may be important factors that predict the clinical outcomes of an immunotherapeutic agent, when combined with alkalinizing agents such as NaHCO3 and KNa-cit.

Thioredoxin-albumin fusion protein prevents urban aerosol-induced lung injury via suppressing oxidative stress-related neutrophil extracellular trap formation

The number of deaths from air pollution worldwide is estimated at 8.8 million per year, more than the number of deaths from smoking. Air pollutants, such as PM_2.5, are known to induce respiratory and cardiovascular diseases by inducing oxidative stress. Thioredoxin (Trx) is a 12-kDa endogenous protein that exerts antioxidant activity by promoting dithiol disulfide exchange reactions. We previously synthesized human serum albumin-fused thioredoxin (HSA-Trx), which has a longer half-life in plasma compared with Trx, and demonstrated its efficacy against various diseases including respiratory diseases. Here, we examined the effect of HSA-Trx on urban aerosol-induced lung injury in mice. Urban aerosols induced lung injury and inflammatory responses in ICR mice, but intravenous administration of HSA-Trx markedly inhibited these responses. We next analyzed reactive oxygen species (ROS) production in murine lungs using an in vivo imaging system. The results show that intratracheal administration of urban aerosols induced ROS production that was inhibited by intravenously administered HSA-Trx. Finally, we found that HSA-Trx inhibited the urban aerosol-induced increase in levels of neutrophilic extracellular trap (NET) indicators (i.e., double-stranded DNA, citrullinated histone H3, and neutrophil elastase) in bronchoalveolar lavage fluid (BALF). Together, these findings suggest that HSA-Trx prevents urban aerosol-induced acute lung injury by suppressing ROS production and neutrophilic inflammation. Thus, HSA-Trx may be a potential candidate drug for preventing the onset or exacerbation of lung injury caused by air pollutants.

Synthesis and In Vitro Assessment of pH-Sensitive Human Serum Albumin Conjugates of Pirarubicin

In a previous study, we reported on the development of a synthetic polymer conjugate of pirarubicin (THP) that was formed via an acid-labile hydrazone bond between the polymer and the THP. However, the synthetic polymer itself was non-biodegradable, which could lead to unexpected adverse effects. Human serum albumin (HSA), which has a high biocompatibility and good biodegradability, is also a potent carrier for delivering antitumor drugs. The objective of this study was to develop pH-sensitive HSA conjugates of THP (HSA-THP), and investigate the release of THP and the cytotoxicity under acidic conditions in vitro for further clinical development. HSA-THP was synthesized by conjugating maleimide hydrazone derivatives of THP with poly-thiolated HSA using 2-iminothiolane, via a thiol-maleimide coupling reaction. We synthesized two types of HSA-THP that contained different amounts of THP (HSA-THP2 and HSA-THP4). Free THP was released from both of the HSA conjugates more rapidly at an acidic pH, and the rates of release for HSA-THP2 and HSA-THP4 were similar. Moreover, both HSA-THPs exhibited a higher cytotoxicity at acidic pH than at neutral pH, which is consistent with the effective liberation of free THP under acidic conditions. These findings suggest that these types of HSA-THPs are promising candidates for further development.

Changes in redox state of albumin before and after kidney transplantation in patients with end-stage renal disease

OBJECTIVES

Cardiovascular disease is one of the major causes of death in patients with end-stage kidney disease who have undergone kidney transplantation. Since the complication of cardiovascular disease in patients with chronic kidney disease is strongly linked to oxidative stress, understanding the oxidative stress condition after kidney transplantation would be of great importance for the prevention of cardiovascular disease. This study examined whether improvement of renal function after kidney transplantation has an impact on the redox state of the Cys34 residue of albumin that reflects the level of oxidative stress in blood.

DESIGN & METHODS

We enrolled 23 patients with end-stage renal failure who received kidney transplantation. All patients were followed for 180 days after transplantation. The fractions of albumin isoforms were determined by the electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) method.

RESULTS

Serum creatinine decreased significantly immediately after kidney transplantation, suggesting successful transplantations. The ESI-TOFMS method identified three albumin isoforms cysteinylated at the Cys34 residue (Cys-Cys34-albumin) and the three corresponding albumin isoforms without Cys34 cysteinylation. The fraction of total Cys-Cys34-albumin decreased transiently after kidney transplantation, and was followed by an elevation at day 7 and gradual decrease thereafter until day 180. Meanwhile, reduced albumin concentration did not change until day 14 after kidney transplantation, then showed a significant increase compared to pre-transplant level at day 30 and remained stably elevated until day 180.

CONCLUSIONS

Actual reduced albumin levels were found to exceed pre-transplant levels on or after day 30 following kidney transplantation unlike immediate restoration of renal function. Renal function was recovered immediately following kidney transplantation, but reduced albumen concentration increased above the pre-transplant levels only from day 30 after transplantation.

Involvement of SAPK/JNK Signaling Pathway in Copper Enhanced Zinc-Induced Neuronal Cell Death

Zinc (Zn) plays an important role in many organisms in various physiological functions such as cell division, immune mechanisms and protein synthesis. However, excessive Zn release is induced in pathological situations and causes neuronal cell death. Previously, we reported that Cu ions (Cu2+) markedly exacerbates Zn2+-induced neuronal cell death by potentiating oxidative stress and the endoplasmic reticulum stress response. In contrast, the stress-activated protein kinase/c-Jun amino-terminal kinase (SAPK/JNK) signaling pathway is important in neuronal cell death. Thus, in this study, we focused on the SAPK/JNK signaling pathway and examined its involvement in Cu2+/Zn2+-induced neurotoxicity. Initially, we examined expression of factors involved in the SAPK/JNK signaling pathway. Accordingly, we found that phosphorylated (ie, active) forms of SAPK/JNK (p46 and p54) are increased by CuCl2 and ZnCl2 co-treatment in hypothalamic neuronal mouse cells (GT1-7 cells). Downstream factors of SAPK/JNK, phospho-c-Jun, and phospho-activating transcription factor 2 are also induced by CuCl2 and ZnCl2 co-treatment. Moreover, an inhibitor of the SAPK/JNK signaling pathway, SP600125, significantly suppressed neuronal cell death and activation of the SAPK/JNK signaling pathway induced by CuCl2 and ZnCl2 cotreatment. Finally, we examined involvement of oxidative stress in activation of the SAPK/JNK signaling pathway, and found that human serum albumin-thioredoxin fusion protein, an antioxidative protein, suppresses activation of the SAPK/JNK signaling pathway. On the basis of these results, our findings suggest that activation of ZnCl2-dependent SAPK/JNK signaling pathway is important in neuronal cell death, and CuCl2-induced oxidative stress triggers the activation of this pathway.

[Induction of Anti-PEG Immune Responses by PEGylation of Proteins]

Modification of proteins with polyethylene glycol (PEG) (PEGylation) is a gold standard technique that improves the solubility, pharmacokinetics, and immunogenicity of modified proteins. To date more than 10 PEGylated protein formulations have been approved, and more than 20 PEGylated drugs are entering clinical trials. PEG has been considered non-immunogenic and non-toxic, but several studies have shown that PEG acquires immunogenicity following attachment to nanoparticles. The administration of PEGylated liposomes, micelles and proteins induces the production of antibodies against PEG (anti-PEG antibodies) in animals and human subjects. Indeed, approximately 20% of healthy human subjects possess pre-existing anti-PEG antibodies prior to treatment with PEGylated therapeutics. The induced and pre-existing anti-PEG antibodies cause not only the elimination of PEGylated proteins from blood circulation, but also allergic responses via the release of anaphylatoxins. Consequently, therapeutic outcomes for PEGylated proteins are impaired. The utility of PEGylated proteins could be improved by attenuating the PEG-related immune response. On the other hand, anti-PEG immune responses might be exploited for vaccine applications. Our recent studies demonstrated that anti-PEG antibodies mediate the delivery of antigens encapsulated in PEGylated liposomes, and enhance antigen-specific immune responses. In this review, we summarize anti-PEG antibody induction by PEGylated proteins and alterations in anti-PEG IgM-mediated pharmacokinetics and pharmacodynamics. These findings extend our knowledge of PEG-related immune responses.

Carbon Monoxide Rescues the Developmental Lethality of Experimental Rat Models of Rhabdomyolysis-Induced Acute Kidney Injury

Many victims, after being extricated from a collapsed building as the result of a disaster, suffer from disaster nephrology, a term that is referred to as the crush syndrome (CS). Recommended treatments, which include dialysis or the continuous administration of massive amounts of fluid are not usually easy in cases of such mass natural disasters. In the present study, we examined the therapeutic performance of a biomimetic carbon monoxide (CO) delivery system, CO-enriched red blood cells (CO-RBCs), on experimental animal models of an acute kidney injury (AKI) induced by traumatic and nontraumatic rhabdomyolysis, including CS and rhabdomyolysis with massive hemorrhage shock. A single CO-RBC treatment was found to effectively suppress the pathogenesis of AKI with the mortality in these model rats being improved. In addition, in further studies using glycerol-induced rhabdomyolysis model rats, the pathogenesis of which is similar to that for the CS, AKI and mortality were also reduced as the result of a CO-RBC treatment. Furthermore, CO-RBCs were found to have renoprotective effects via the suppression of subsequent heme protein-associated renal oxidative injury; the oxidation of myoglobin in the kidneys, the generation of reactive oxygen species by free heme produced from degraded-cytochrome P450 and hemoglobin-associated renal injury. Because CO-RBCs can be prepared and used at both hospitals and at a disaster site, these findings suggest that CO-RBCs have the potential for use as a novel cell therapy against both nontraumatic and traumatic rhabdomyolysis including CS-induced AKI. SIGNIFICANCE STATEMENT: After mass natural and man-made disasters, people who are trapped in collapsed buildings are in danger of acute kidney injury (AKI), including crush syndrome (CS)-related AKI. This paper reports that carbon monoxide-enriched red blood cells (CO-RBCs), which can be prepared at both hospitals and disaster sites, dramatically suppressed the pathogenesis of CS-related AKI, thus improving mortality via suppressing heme protein-associated renal injuries. CO-RBCs have the potential for serving as a practical therapeutic agent against disaster nephrology associated with the CS.

Repeated Administration of Kupffer Cells-Targeting Nanoantioxidant Ameliorates Liver Fibrosis in an Experimental Mouse Model

Kupffer cells are a major producer of reactive oxygen species and have been implicated in the development of liver fibrosis during chronic hepatitis in non-alcoholic steatohepatitis (NASH) and alcoholic steatohepatitis (ASH). We recently reported on the development of a polythiolated and mannosylated human serum albumin (SH-Man-HSA) that functions as a Kupffer cell-targeting nanoantioxidant. In this material, the albumin is mannosylated, which permits it to be taken up by mannose receptor C type 1 expressed on Kupffer cells, and is also polythiolated to have antioxidant activity. To clarify the anti-fibrotic property of this nanoantioxidant, we repeatedly administered SH-Man-HSA to a liver fibrosis mouse model that was induced by the repeated treatment of the concanavalin-A, which mimics the liver fibrosis observed in NASH and ASH. SH-Man-HSA dramatically improved the survival rate and suppressed liver fibrosis in the experimental model. In addition, SH-Man-HSA suppressed hepatic oxidative stress levels, thereby decreasing the numbers of apoptotic cells. In contrast, N-acetylcysteine, which contains the same thiol content as the SH-Man-HSA, failed to show a substantial therapeutic effect in these mice. The expression levels of inflammatory genes including epidermal growth factor module-containing mucin-like receptor (Emr-1/F4/80), Toll-like receptor-4 (TLR-4), high mobility group box-1 (HMGB-1), CC chemokine ligand-5 (CCL-5), tumor necrosis factor-α (TNF-α), CCL-2, interleukin-6 (IL-6), and IL-1β, as well as fibrotic (α-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), and Snail) and extracellular matrix genes (collagen, type Iα2 (Col1α2), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase 1 (TIMP-1)), showed some decreasing trends by the SH-Man-HSA administration. These findings suggest that the repeated administration of the Kupffer cell-targeting nanoantioxidant, SH-Man-HSA, ameliorates liver fibrosis in mice by suppressing the level of oxidative stress and a portion of the inflammation, and has a potential therapeutic effect against NASH and ASH.

Albumin domain mutants with enhanced Aβ binding capacity identified by phage display analysis for application in various peripheral Aβ elimination approaches of Alzheimer's disease treatment

Deposition of amyloid protein, particularly Aβ_1-42 , is a major contributor to the onset of Alzheimer's disease (AD). However, almost no deposition of Aβ in the peripheral tissues could be found. Human serum albumin (HSA), the most abundant protein in the blood, has been reported to inhibit amyloid formation through binding Aβ, which is believed to play an important role in the peripheral clearance of Aβ. We identified the Aβ binding site on HSA and developed HSA mutants with high binding capacities for Aβ using a phage display method. HSA fragment 187-385 (Domain II) was found to exhibit the highest binding capacity for Aβ compared with the other two HSA fragments. To elucidate the sequence that forms the binding site for Aβ on Domain II, a random screening of Domain II display phage biopanning was constructed. A number of mutants with higher Aβ binding capacities than the wild type were identified. These mutants exhibited stronger scavenging abilities than the wild type, as revealed via in vitro equilibrium dialysis of Aβ experiments. These findings provide useful basic data for developing a safer alternative therapy than Aβ vaccines and for application in plasma exchange as well as extracorporeal dialysis.

A novel intraperitoneal therapy for gastric cancer with DFP-10825, a unique RNAi therapeutic targeting thymidylate synthase, in a peritoneally disseminated xenograft model

Purpose

In advanced gastric cancer, peritoneal dissemination is a life‐threatening mode of metastasis. Since the treatment options with conventional chemotherapy remain limited, any novel therapeutic strategy that could control such metastasis would improve the outcome of treatment. We recently developed a unique RNA interference therapeutic regimen (DFP‐10825) consisting of short hairpin RNA against thymidylate synthase (TS shRNA) and cationic liposomes. The treatment with DFP‐10825 has shown remarkable antitumor activity in peritoneally disseminated human ovarian cancer–bearing mice via intraperitoneal administration. In this study, we expanded DFP‐10825 to the treatment of peritoneally disseminated gastric cancer.

Methods

DFP‐10825 was administered intraperitoneally into mice with intraperitoneally implanted human gastric cancer cells (MKN45 or NCI‐N87). Antitumor activity and host survival benefits were monitored. Intraperitoneal distribution of fluorescence‐labeled DFP‐10825 was monitored in this MKN45 peritoneally disseminated mouse model.

Results

Intraperitoneal injection of DFP‐10825 suppressed tumor growth in two peritoneally disseminated cancer models (MKN45 and NCI‐N87) and increased the survival time of the MKN45 model without severe side effects. Throughout the treatment regimen, no significant body weight loss was associated with the administration of DFP‐10825. Interestingly, after intraperitoneal injection, fluorescence‐labeled DFP‐10825 retained for more than 72 hours in the peritoneal cavity and selectively accumulated in disseminated tumors.

Conclusions

Intraperitoneal injection of DFP‐10825 demonstrated effective antitumor activity without systemic severe adverse effects via the selective delivery of RNAi molecules into disseminated tumors in the peritoneal cavity. Our current study indicates that DFP‐10825 could become an alternative option to improve the outcomes of patients with peritoneally disseminated gastric cancer.

α1-Acid Glycoprotein Has the Potential to Serve as a Biomimetic Drug Delivery Carrier for Anticancer Agents

Nanosize plasma proteins could be used as a biomimetic drug delivery system (DDS) for cancer treatment when loaded with anticancer drugs based on the fact that plasma proteins can serve as a source of nutrients for cancer cells. This prompted us to investigate the potential of α₁-acid glycoprotein (AGP) for this role because it is a nanosize plasma protein and binds a variety of anticancer agents. Pharmacokinetic analyses indicated that AGP is distributed more extensively in tumor tissue than human serum albumin, which was already established as a cancer DDS carrier. AGP is possibly being incorporated into tumor cells via endocytosis pathways. Moreover, a synthetic AGP-derived peptide which possesses a high ability to form an α-helix, as deduced from the primary structure of AGP, was also taken up by the tumor cells. AGP loaded with anticancer agents, such as paclitaxel or nitric oxide, efficiently induced tumor cell death. These results suggest that AGP has the potential to be a novel DDS carrier for anticancer agents.

A simplified method for manufacturing RNAi therapeutics for local administration

RNA interference (RNAi) is one of the most promising strategies for cancer therapeutics. The successful translation of RNAi therapeutics to a clinic setting requires a delivery system that is efficient and simple to upscale. In this study, we devised a simple industrial method to manufacture lipoplex, which includes short hairpin RNA against the expression of thymidylate synthase (TS shRNA) - a key molecule for DNA biosynthesis. An aqueous solution of TS shRNA was gently mixed with either a precursor of cationic liposome (Presome DF-1) or a cationic lipid mixture in an o/w emulsion. This solution was subsequently lyophilized under optimal conditions to obtain either FD-lipoplex-1 or FD-lipoplex-2, respectively. With this method, a lipoplex in activated form was obtained via a simple "one-step" hydration with saline. Both forms of FD-lipoplex showed physicochemical properties comparable to those of conventional lipoplex. FD-lipoplexes stably retained TS shRNA within their formulations in the presence of tumor ascites fluid. Intraperitoneal treatment with either FD-lipoplex-1 or FD-lipoplex-2 provided a therapeutic level of efficacy comparable to that of conventional lipoplex in the treatment of a peritoneal disseminated gastric cancer mouse model. Collectively, established freeze-drying-based methods for RNAi-therapeutic preparation could realistically be used in a clinical setting for the treatment of patients with peritoneal disseminated cancer.

Distribution of Polysulfide in Human Biological Fluids and Their Association with Amylase and Sperm Activities

Intracellular polysulfide could regulate the redox balance via its anti-oxidant activity. However, the existence of polysulfide in biological fluids still remains unknown. Recently, we developed a quantitative analytical method for polysulfide and discovered that polysulfide exists in plasma and responds to oxidative stress. In this study, we confirmed the presence of polysulfide in other biological fluids, such as semen and nasal discharge. The levels of polysulfide in these biological fluids from healthy volunteers (n = 9) with identical characteristics were compared. Additionally, the circadian rhythm of plasma polysulfide was also investigated. The polysulfide levels detected from nasal discharge and seminal fluid were approximately 400 and 600 μM, respectively. No correlation could be found between plasma polysulfide and the polysulfide levels of tear, saliva, and nasal discharge. On the other hand, seminal polysulfide was positively correlated with plasma polysulfide, and almost all polysulfide contained in semen was found in seminal fluid. Intriguingly, saliva and seminal polysulfide strongly correlated with salivary amylase and sperm activities, respectively. These results provide a foundation for scientific breakthroughs in various research areas like infertility and the digestive system process.

Long-term storage of PEGylated liposomal oxaliplatin with improved stability and long circulation times in vivo

Liposomal anticancer drugs have been developed with improved clinical effects and reduced side effects. We have developed a PEGylated liposomal formulation of oxaliplatin that has anticancer effects in animal models of colorectal cancer with a favorable toxicity profile. To move this formulation into clinical development, a formulation that is stable during long term storage is needed, which has similar pharmacokinetics and therapeutic activity against solid tumors to the original formulation. In this study, we found that PEGylated liposomal oxaliplatin showed no changes in particle size after long term storage (12 months at 2-8 °C), but phospholipid degradation had occurred. Hence, the stored formulation had compromised membrane integrity, resulting in decreased in vivo circulation times of the liposomes. To improve the stability during long-term storage, a screening study to obtain an appropriate stabilizer was carried out. The buffer 2-morpholinoethansulfonic acid (MES) attenuated not only phospholipid degradation but also oxaliplatin degradation, unlike most other excipients. After 12 months storage at 2-8 °C in the presence of MES only slight degradation of phospholipids in PEGylated liposomal oxaliplatin occurred, resulting in similar in vivo pharmacokinetic profiles of the encapsulated oxaliplatin to the original formulation. Long term stability of PEGylated liposomal oxaliplatin was achieved by addition of MES, resulting in long circulation half-lives in vivo, a property which would be expected to lead to increased suppression of tumor growth and reduced side effects. Our formulation may now be suitable for clinical development.

S-Nitrosated alpha-1-acid glycoprotein exhibits antibacterial activity against multidrug-resistant bacteria strains and synergistically enhances the effect of antibiotics

Alpha-1-acid glycoprotein (AGP) is a major acute-phase protein. Biosynthesis of AGP increases markedly during inflammation and infection, similar to nitric oxide (NO) biosynthesis. AGP variant A (AGP) contains a reduced cysteine (Cys149). Previously, we reported that S-nitrosated AGP (SNO-AGP) synthesized by reaction with a NO donor, possessed very strong broad-spectrum antimicrobial activity (IC50 = 10-9-10-6 M). In this study, using a cecal ligation and puncture animal model, we confirmed that AGP can be endogenously S-nitrosated during infection. Furthermore, we examined the antibacterial property of SNO-AGP against multidrug-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa to investigate the involvement of SNO-AGP in the host defense system. Our results showed that SNO-AGP could inhibit multidrug efflux pump, AcrAB-TolC, a major contributor to bacterial multidrug resistance. In addition, SNO-AGP decreased biofilm formation and ATP level in bacteria, indicating that SNO-AGP can revert drug resistance. It was also noteworthy that SNO-AGP showed synergistic effects with the existing antibiotics (oxacillin, imipenem, norfloxacin, erythromycin, and tetracycline). In conclusion, SNO-AGP participated in the host defense system and has potential as a novel agent for single or combination antimicrobial therapy.

Doxorubicin Expands in Vivo Secretion of Circulating Exosome in Mice

Modulation of tumor immunity is a known factor in the antitumor activity of many chemotherapeutic agents. Exosomes are extracellular nanometric vesicles that are released by almost all types of cells, which includes cancer cells. These vesicles play a crucial role in tumor immunity. Many in vitro studies have reproduced the aggressive secretion of exosomes following treatment with conventional anticancer drugs. Nevertheless, how chemotherapeutic agents including nanomedicines such as Doxil^® affect the in vivo secretion of exosomes is yet to be elucidated. In this study, the effect of intravenous injection of either free doxorubicin (DXR) or liposomal DXR formulation (Doxil^®) on exosome secretion was evaluated in BALB/c mice. Exosomes were isolated from serum by using an ExoQuick™ kit. Free DXR treatment markedly increased serum exosome levels in a post-injection time-dependent manner, while Doxil^® treatment did not. Exosomal size distribution and marker protein expressions (CD9, CD63, and TSG101) were studied. The physical/biological characteristics of treatment-induced exosomes were comparable to those of control mice. Interestingly, splenectomy significantly suppressed the copious exosomal secretions induced by free DXR. Collectively, our results indicate that conventional anticancer agents induce the secretion of circulating exosomes, presumably via stimulating immune cells of the spleen. As far as we know, this study represents the first report indicating that conventional chemotherapeutics may induce exosome secretion which might, in turn, contribute partly to the antitumor effect of chemotherapeutic agents.