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A wide variety of drugs bind to human serum albumin (HSA) at its two principal sites, namely site I and site II. A number of reports indicate that drug binding to these two binding sites are not completely independent, and that interactions between ligands of these two discrete sites can play a role. In this study, the effect of the binding of long-chain fatty acids on the interactive binding between dansyl-L-asparagine (DNSA; site I ligand) and ibuprofen (site II ligand) at pH6.5 was examined. Binding experiments showed that the binding of sodium oleate (Ole) to HSA induces conformational changes in the molecule, which, in turn, changes the individual binding of DNSA and ibuprofen, as well as the mode of interaction between these two ligands from a 'competitive-like' allosteric interaction in the case of the defatted HSA conformer to a 'nearly independent' binding in the case of non-defatted HSA conformer. Circular dichroism measurements indicated that ibuprofen and Ole are likely to modify the spatial orientation of DNSA at its binding site. Docking simulations suggest that the long-distance electric repulsion between DNSA and ibuprofen on defatted HSA contributes to a 'competitive-like' allosteric interaction, whereas extending the distance between ligands and/or increasing the flexibility or size of the DNSA binding site in fatted HSA evokes a change in the interaction mode to 'nearly independent' binding. The present findings provide further insights into the structural dynamics of HSA upon the binding of fatty acids, and its effects on drug binding and drug-drug interactions that occur on HSA.

During pasteurization and storage of albumin products, Sodium octanoate (Oct) and N-acethyl-l-tryptophan (N-AcTrp) are used as the thermal stabilizer and the antioxidant for human serum albumin (HSA), respectively. We recently reported that N-acethyl-l-methionine (N-AcMet) is an antioxidant for HSA, which is superior to N-AcTrp when it is especially exposed to light during storage. The objective of the present study is to clarify the molecular mechanism responsible for the HSA protective effect of Oct and N-AcMet based on their ternary complex structure. Crystal structure of the HSA-Oct-N-AcMet complex showed that one N-AcMet molecule is bound to the entrance of drug site 1 of HSA, and its side chain, which is susceptible to the oxidation, is exposed to the solvent. At the same time, two Oct binding sites are observed in drug sites 1 and 2 of HSA, respectively, and each Oct molecule occupies the hydrophobic cavity in them. These results indicate the molecular mechanism responsible for the HSA stabilization by these small molecules as follows. N-AcMet seals the entrance of drug site 1 while it acts as an antioxidant for HSA. Oct is chiefly bound to drug site 2 of HSA and it increases the thermal stability of HSA because of the occupying the largest intra-cavity of sub-domain IIIA in HSA. These findings suggest that N-AcMet acts positively as useful stabilizer for albumin formulated products such as functionalized HSA and HSA fusion proteins.

Background A T‐helper (Th) cell subset Th17 preferentially produces interleukin (IL)‐17 and plays a pivotal role in the pathogenesis of psoriasis. However, the pathological roles of IL‐17 cascades in generalized pustular psoriasis (GPP) and psoriatic erythroderma (PsE) have not been well established. Objectives To evaluate the efficacy and safety of brodalumab, a human immunoglobulin G2 monoclonal antibody against human IL ‐17‐receptor A (IL‐17RA), in Japanese patients with GPP and PsE. Methods This was an open‐label, multicentre, long‐term phase III study in Japanese patients with rare and severe types of psoriasis. Patients received brodalumab 140 mg at day 1 and weeks 1 and 2, and then every 2 weeks until week 52. The primary endpoint was the Clinical Global Impression of Improvement (CGI). Safety evaluations included treatment‐emergent adverse events (AEs) and changes in laboratory parameters. Results A total of 12 patients with GPP and 18 with PsE were enrolled. Ten patients with GPP and 16 with PsE completed the study. At week 52 (last observation carried forward), CGI remission or improvement was achieved in 11 patients with GPP and 18 with PsE. The most commonly reported AE was nasopharyngitis (33·3%). Five serious AE s occurred during the study. However, none was considered treatment‐related. Conclusions Brodalumab significantly improved the symptoms of patients with GPP and PsE throughout the 52 weeks, and demonstrated favourable safety profiles without any new safety signals. Inhibition of IL‐17RA‐mediated signalling by brodalumab is expected to be a promising new treatment option for patients with GPP and PsE.

Low concentrations of exogenous carbon monoxide (CO) have been reported to be useful for the treatment of various disorders related to inflammation and oxidative stress. However, a number of obstacles make it difficult to use CO in vivo. Among these are, at high concentrations, it is toxic and the fact that it is difficult to control its delivery in the body. Hemoglobin-encapsulated liposomes, Hemoglobin-vesicles (HbV), have the potential for use as a new type of nano-sized CO donor, referred to as CO-bound HbV (CO-HbV). In this study, we investigated the potential of CO-HbV as a CO donor in terms of toxicity and therapeutic efficacy using an experimental colitis model. Toxicological assessments of CO-HbV showed no severe adverse effects including death, and clinical laboratory tests and histopathological changes remained normal for 28 days after the administration of doses up to 1400 mg Hb/kg. We then evaluated the therapeutic efficacies of CO-HbV on dextran sulfate sodium (DSS)-induced colitis model mice. A single administration of CO-HbV at 3 days from beginning of the DSS treatment dramatically improved colitis symptoms, colonic histopathological changes and the duration of survival compared to both saline and HbV administration. In addition, the therapeutic effects of CO-HbV on colitis can be attributed to a decreased level of neutrophil infiltration, the production of pro-inflammatory cytokines and oxidative injuries. Interestingly, it appears that an increase in anti-inflammatory cytokine production contributes, in part, to therapeutic effects of CO-HbV in the treatment of colitis. These safety and efficacy profiles of CO-HbV suggest that it has the potential for use as a drug for treating, not only colitis but also a variety of other disorders associated with inflammation and oxidative stress.

Purpose: The half-life of insulin analogs and glucagon like peptide-1 (GLP-1) receptor agonist is prolonged through binding to albumin, but this may not occur in hypoalbuminemic diabetic patients with protein leaking from glomerulus and high capillary protein permeability. We previously showed that human serum albumin (HSA) dimer produced by crosslinking Cys34 of two HSA molecules with 1,6-bis(maleimido)hexane has potential as a drug carrier under high glomerular permeability conditions such as nephrosis. The aim of this study was to investigate the superior ability of a structurally defined HSA dimer as an augmenting agent for antidiabetic drugs. For this purpose, the pharmacokinetic properties of HSA dimer in diabetic rat model were evaluated. In addition, the existence of insulin analogs (insulin detemir and insulin degludec) and GLP-1 receptor agonist (liraglutide) binding sites in HSA dimer was determined. Methods: The diabetic nephropathy rat model was prepared by administering a single injection (60 mg/kg) of streptzotocin (STZ) through the tail vein of Sprague-Dawley rats. Fourteen days after STZ administration, STZ-induced diabetic nephropathy model rats were given a single injection of 111In-labeled HSA monomer or 111In-labeled HSA dimer via the tail vein. Subsequently, the 111In levels in the plasma and excised organs were determined. Site specific fluorescent probe displacement experiments were performed using warfarin potassium (WF) and dansylsarcosine (DNSS) as site I and site II specific fluorescent probes, respectively. [Results and Discussion] HSA monomer was rapidly cleared from the plasma compared to the HSA dimer in diabetic nephropathy model rats. In addition, the half-life of the HSA dimer was 1.5 times longer than the HSA monomer, which can be attributed to accumulation in the muscle. The fluorescent probe displacement experiment results for HSA monomer and dimer were similar, where insulin analogs and GLP-1 receptor agonist displaced DNSS but

Human serum albumin (HSA) is synthesized predominantly in the liver, and has an extraordinarily long circulatory half-life (~19 days). Since HSA is responsible for 80% of the colloidal osmotic pressure of plasma, the patients with hypoalbuminemia are typically given a plasma expander to increase the plasma volume. Clinically, using HSA as an extender is preferable to other options, such as dextran, hydroxylethyl starch, due to its long retention in plasma. However, the circulatory half-life of HSA is significantly- impacted by structural changes of HSA and pathological conditions. Recent scientific advances have revealed new information regarding the factors that influence the pharmacokinetic properties of HSA. In this chapter, we provide an overview of the impact of HSA structure and biotransformation upon the pharmacokinetic properties of HSA, and discuss new possibilities for the therapeutic potential of HSA based on its pharmacokinetic properties.

Objectives The half-life of fatty acid-conjugated antidiabetic drugs are prolonged through binding to albumin, but this may not occur in diabetic patients with nephropathy complicated with hypoalbuminemia. We previously showed that human serum albumin (HSA) dimerized at the protein's Cys34 by 1,6-bis(maleimido)hexane has longer half-life than the monomer under high permeability conditions. The aim of this study was to investigate the superior ability of this HSA dimer as a plasma-retaining agent for fatty acid conjugated antidiabetic drugs. Methods The diabetic nephropathy rat model was prepared by administering a single injection of streptozotocin (STZ) intravenously, and the pharmacokinetic properties of HSA monomer and dimer were evaluated. Site-specific fluorescent probe displacement experiments were performed using warfarin and dansylsarcosine as site I and site II specific fluorescent probes, respectively. Key findings The half-life of the HSA dimer in STZ-induced diabetic nephropathy model rats was 1.5 times longer than the HSA monomer. The fluorescent probe displacement experiment results for HSA monomer and dimer were similar, where fatty acid-conjugated antidiabetic drugs displaced dansylsarcosine but not warfarin in a concentration-dependent manner. Conclusions The HSA dimer shows potential for use as a plasma-retaining agent for antidiabetic drugs due to its favourable pharmacokinetic properties.