A New Surface Plasmon Resonance Assay for In Vitro Screening of Mannose-Binding Lectin Inhibitors

Applications of mannose-binding lectins and mannan glycoconjugates in nanomedicine

Glycosylated nanoparticles (NPs) have drawn a lot of attention in the biomedical field over the past few decades, particularly in applications like targeted drug delivery. Mannosylated NPs and mannan-binding lectins/proteins (MBL/MBP) are emerging as promising tools for delivery of drugs, medicines, and enzymes to targeted tissues and cells as nanocarriers, enhancing their therapeutic benefits while avoiding the adverse effects of the drug. The occurrence of plenty of lectin receptors and their mannan ligands on cell surfaces makes them multifaceted carriers appropriate for specific delivery of bioactive drug materials to their targeted sites. Thus, the present review describes the tethering of mannose (Man) to several nanostructures, like micelles, liposomes, and other NPs, applicable for drug delivery systems. Bioadhesion through MBL-like receptors on cells has involvements applicable to additional arenas of science, for example gene delivery, tissue engineering, biomaterials, and nanotechnology. This review also focuses on the role of various aspects of drug/antigen delivery using (i) mannosylated NPs, (ii) mannosylated lectins, (iii) amphiphilic glycopolymer NPs, and (iv) natural mannan-containing polysaccharides, with most significant applications of MBL-based NPs as multivalent scaffolds, using different strategies.

GRAPHICAL ABSTRACT

Mannosylated NPs and/or MBL/MBP are coming up as viable and versatile tools as nanocarriers to deliver drugs and enzymes precisely to their target tissues or cells. The presence of abundant number of lectin receptors and their mannan ligands on cell surfaces makes them versatile carriers suitable for the targeted delivery of bioactive drugs.

A Surface Plasmon Resonance-Based Assay for Simultaneous Measurement of Serum Concentrations of Therapeutic Antibodies and Anti-Drug Antibodies

The monitoring of the blood levels of therapeutic antibodies and their immune responses is proposed to guide and optimize therapy with these expensive drugs. We describe a novel Surface Plasmon Resonance (SPR)-based assay suitable for the simultaneous determination of serum concentrations of infliximab and anti-infliximab antibodies. The real-time detection by SPR avoids the incubation/washing steps of commonly used methods, thus allowing faster and more reliable measurements, in particular for low-affinity anti-drug antibodies. This method proved to be highly reproducible and may be well applied to other biotherapeutics.

Plasma-derived and recombinant C1 esterase inhibitor: Binding profiles and neuroprotective properties in brain ischemia/reperfusion injury

C1 esterase inhibitor (C1INH) is known to exert its inhibitory effect by binding to several target proteases of the contact and complement systems. One of C1INH's targets comprise mannose-binding lectin (MBL), a critical player in post-stroke pathophysiology. We therefore explored the effects of recombinant human (rh) and plasma derived (pd) C1INH in C57BL/6J mice subjected to transient occlusion of the middle cerebral artery (tMCAo), receiving 15U/mouse of pd or rhC1INH intravenously, at reperfusion. We analyzed the compounds' (i)neuroprotective effects, (ii) plasma presence, (iii)effects on circulating and brain MBL, (iv)time course of endothelial deposition, and (v) effects on the formation of active complement products. rhC1INH-treated mice had neuroprotective effects, including reduced behavioral deficits and neuronal loss, associated with decreased MBL brain deposition and decreased formation of complement C4b active fragments. In contrast, pdC1INH did not show these neuroprotective effects despite its longer plasma residence time. We also analyzed the response to tMCAo in C1INH-deficient mice, observing a poorer ischemic outcome compared to the wild type mice, which could be partially prevented by rhC1INH administration. In conclusion, we show that rhC1INH exhibits stronger neuroprotective effects than the corresponding plasma-derived protein after experimental ischemia/reperfusion injury in the brain, placing it as a promising drug for stroke. Differential effects are likely related to more effective MBL inhibition which further confirms it as a useful pharmacological target for stroke.

Sweet turning bitter: Carbohydrate sensing of complement in host defence and disease

The complement system plays a major role in threat recognition and in orchestrating responses to microbial intruders and accumulating debris. This immune surveillance is largely driven by lectins that sense carbohydrate signatures on foreign, diseased and healthy host cells and act as complement activators, regulators or receptors to shape appropriate immune responses. While carbohydrate sensing protects our bodies, misguided or impaired recognition can contribute to disease. Moreover, pathogenic microbes have evolved to evade complement by mimicking host signatures. While complement is recognized as a disease factor, we only slowly start to appreciate the role of carbohydrate interactions in the underlying processes. A better understanding of complement's sweet side will contribute to a better description of disease mechanisms and enhanced diagnostic and therapeutic options. This review introduces the key components in complement-mediated carbohydrate sensing, discusses their role in health and disease, and touches on the potential effects of carbohydrate-related disease intervention. LINKED ARTICLES: This article is part of a themed issue on Canonical and non-canonical functions of the complement system in health and disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.14/issuetoc.

Comparative biophysical characterization: A screening tool for acetylcholinesterase inhibitors

Among neurodegenerative diseases, Alzheimer’s disease (AD) is one of the most grievous disease. The oldest cholinergic hypothesis is used to elevate the level of cognitive impairment and acetylcholinesterase (AChE) comprises the major targeted enzyme in AD. Thus, acetylcholinesterase inhibitors (AChEI) constitutes the essential remedy for the treatment of AD. The study aims to evaluate the interactions between natural molecules and AChE by Surface Plasmon Resonance (SPR). The molecules like alkaloids, polyphenols and substrates of AChE have been considered for the study with a major emphasis on affinity and kinetics. To better understand the activity of small molecules, the investigation is supported by both experimental and theoretical approach such as fluorescence, Circular Dichroism (CD) and molecular docking studies. Amongst the screened ones tannic acid showed promising results compared with others. The methodology followed here have highlighted many molecules with a higher affinity towards AChE and these findings may take lead molecules generated in preclinical studies to treat neurodegenerative diseases. Additionally, we suggest a unique signature for the heterogeneous analyte model using competitive experiments for analyzing simultanous interactions of both the analytes.

Synthesis and comparison of linear and hyperbranched multivalent glycosides for C-type lectin binding

Hyperbranched and linear polyglycerol-based mannoside and fucosyllactoside residues with different ligand densities showed nanomolar binding affinities for MBL and DC-SIGN proteins.

Pharmacological inhibition of mannose-binding lectin ameliorates neurobehavioral dysfunction following experimental traumatic brain injury

Mannose-binding lectin is present in the contusion area of traumatic brain-injured patients and in that of traumatic brain-injured mice, where mannose-binding lectin-C exceeds mannose-binding lectin-A. The reduced susceptibility to traumatic brain injury of mannose-binding lectin double knock-out mice (mannose-binding lectin^-/-) when compared to wild type mice suggests that mannose-binding lectin may be a therapeutic target following traumatic brain injury. Here, we evaluated the effects of a multivalent glycomimetic mannose-binding lectin ligand, Polyman9, following traumatic brain injury in mice. In vitro surface plasmon resonance assay indicated that Polyman9 dose-dependently inhibits the binding to immobilized mannose residues of plasma mannose-binding lectin-C selectively over that of mannose-binding lectin-A. Male C57Bl/6 mice underwent sham/controlled cortical impact traumatic brain injury and intravenous treatment with Polyman9/saline. Ex-vivo surface plasmon resonance studies confirmed that Polyman9 effectively reduces the binding of plasma mannose-binding lectin-C to immobilized mannose residues. In vivo studies up to four weeks post injury, showed that Polyman9 induces significant improvement in sensorimotor deficits (by neuroscore and beam walk), promotes neurogenesis (73% increase in doublecortin immunoreactivity), and astrogliosis (28% increase in glial fibrillary acid protein). Polyman9 administration in brain-injured mannose-binding lectin^-/- mice had no effect on post-traumatic brain-injured functional deficits, suggestive of the specificity of its neuroprotective effects. The neurobehavioral efficacy of Polyman9 implicates mannose-binding lectin-C as a novel therapeutic target for traumatic brain injury.