Characterization of Asparagine Deamidation in Immunodominant Myelin Oligodendrocyte Glycoprotein Peptide Potential Immunotherapy for the Treatment of Multiple Sclerosis

Competitive ELISA for the identification of 35-55 myelin oligodendrocyte glycoprotein immunodominant epitope conjugated with mannan

Analogs of immunodominant myelin peptides involved in multiple sclerosis (MS: the most common autoimmune disease) have been extensively used to modify the immune response over the progression of the disease. The immunodominant 35-55 epitope of myelin oligodendrocyte glycoprotein (MOG35-55 ) is an autoantigen appearing in MS and stimulates the encephalitogenic T cells, whereas mannan polysaccharide (Saccharomyces cerevisiae) is a carrier toward the mannose receptor of dendritic cells and macrophages. The conjugate of mannan-MOG35-55 has been extensively studied for the inhibition of chronic experimental autoimmune encephalomyelitis (EAE: an animal model of MS) by inducing antigen-specific immune tolerance against the clinical symptoms of EAE in mice. Moreover, it presents a promising approach for the immunotherapy of MS under clinical investigation. In this study, a competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect the MOG35-55 peptide that is conjugated to mannan. Intra- and inter-day assay experiments proved that the proposed ELISA methodology is accurate and reliable and could be used in the following applications: (i) to identify the peptide (antigen) while it is conjugated to mannan and (ii) to adequately address the alterations that the MOG35-55 peptide may undergo when it is bound to mannan during production and stability studies.

Computational Insights into the Formation and Structure of S-N Containing Cyclic Peptides

Cyclic peptides are known to have biologically important roles and may also be applicable to the pharmaceutical and other industries. Furthermore, thiols and amines, which are found throughout biological systems, can react to form S-N bonds and to date, ∼100 biomolecules containing such a bond have been identified. However, while there are in principle numerous S-N containing peptide-derived rings possible, only a few are presently known to occur in biochemical systems. Density functional theory-based calculations have been used to consider the formation and structure of S-N containing cyclic peptides from systematic series of linear peptides in which a cysteinyl has first been oxidized to a sulfenic or sulfonic acid. In addition, the possible effect of the cysteine's vicinal residue on the free energy of formation has also been considered. In general, when the cysteine is first oxidized to a sulfenic acid, only the formation of smaller S-N containing rings is calculated to be exergonic in aqueous solution. In contrast, when the cysteine is first oxidized to a sulfonic acid, the formation of all rings considered (with one exception) is calculated to be endergonic in aqueous solution. The nature of vicinal residue can influence ring formation through stabilizing or destabilizing intramolecular interactions.

The quest for a generic bird target to detect the presence of bird in food products and considerations for paleoprotein analysis

It can be important for consumers to know whether food products contain animal material and, if so, of which species. Food products with animal material as an ingredient often contain collagen type 1. LC-MS/MS (Liquid Chromatography-tandem Mass Spectrometry) was applied as technique to generically detect bird. Unlike for example fish, that have experienced longer divergence times, it is still possible to find generic LC-MS targets for avian type 1 collagen. After theoretical target selection using 83 collagen 1α2 bird sequences of 33 orders and construction of a common ancestor sequence of birds, experimental evidence was provided by analyzing extracts from 10 extant bird species. Two suitable options have been identified. The combination of VGPIGPAGNR and VGPIGAAGNR (pheasant only) covers all investigated birds and was not found in other species. The peptide EGPVGFpGADGR covers all investigated birds, but also occurs in several species of crocodiles and turtles. The presence of the generic peptide (combination) was confirmed in food products, proving the principle, and can therefore be used to detect the presence of bird. Furthermore, it is shown how the use of constructed ancestor sequences could benefit the field of paleoproteomics, in the interpretation of collagen MS/MS spectra of ancient species. Our theoretical analysis and assessment of reported Brachylophosaurus canadensis collagen 1α2 MS/MS data provided support for several previous peptide sequence assignments, but we also propose that our constructed ancestral bird sequence GPpGESGAVGPAGPIGSR may fit the MS/MS data better than the original assignment GLPGESGAVGPAGPpGSR.

Development of PLGA Nanoparticles with a Glycosylated Myelin Oligodendrocyte Glycoprotein Epitope (MOG35-55) against Experimental Autoimmune Encephalomyelitis (EAE)

Multiple sclerosis (MS) is one of the most common neurodegenerative diseases in young adults, with early clinical symptoms seen in the central nervous system (CNS) myelin sheaths due to an attack caused by the patient's immune system. Activation of the immune system is mediated by the induction of an antigen-specific immune response involving the interaction of multiple T-cell types with antigen-presenting cells (APCs), such as dendritic cells (DCs). Antigen-specific therapeutic approaches focus on immune cells and autoantigens involved in the onset of disease symptoms, which are the main components of myelin proteins. The ability of such therapeutics to bind strongly to DCs could lead to immune system tolerance to the disease. Many modern approaches are based on peptide-based research, as, in recent years, they have been of particular interest in the development of new pharmaceuticals. The characteristics of peptides, such as short lifespan in the body and rapid hydrolysis, can be overcome by their entrapment in nanospheres, providing better pharmacokinetics and bioavailability. The present study describes the development of polymeric nanoparticles with encapsulated myelin peptide analogues involved in the development of MS, along with their biological evaluation as inhibitors of MS development and progression. In particular, particles of poly(lactic-co-glycolic) acid (PLGA) loaded with peptides based on mouse/rat (rMOG) epitope 35-55 of myelin oligodendrocyte glycoprotein (MOG) conjugated with saccharide residues were developed. More specifically, the MOG_35-55 peptide was conjugated with glucosamine to promote the interaction with mannose receptors (MRs) expressed by DCs. In addition, a study of slow release (dissolution) and quantification on both initially encapsulated peptide and daily release in saline in vitro was performed, followed by an evaluation of in vivo activity of the formulation on mouse experimental autoimmune encephalomyelitis (EAE), an animal model of MS, using both prophylactic and therapeutic protocols. Our results showed that the therapeutic protocol was effective in reducing EAE clinical scores and inflammation of the central nervous system and could be an alternative and promising approach against MS inducing tolerance against the disease.

New insights into the immunologic role of oligodendrocyte lineage cells in demyelination diseases

Oligodendrocyte lineage cells (OL-lineage cells) are a cell population that are crucial for mammalian central nervous system (CNS) myelination. OL-lineage cells go through developmental stages, initially differentiating into oligodendrocyte precursor cells (OPCs), before becoming immature oligodendrocytes, then mature oligodendrocytes (OLs). While the main function of cell lineage is in myelin formation, and increasing number of studies have turned to explore the immunological characteristics of these cells. Initially, these studies focused on discovering how OPCs and OLs are affected by the immune system, and then, how these immunological changes influence the myelination process. However, recent studies have uncovered another feature of OL-lineage cells in our immune systems. It would appear that OL-lineage cells also express immunological factors such as cytokines and chemokines in response to immune activation, and the expression of these factors changes under various pathologic conditions. Evidence suggests that OL-lineage cells actually modulate immune functions. Indeed, OL-lineage cells appear to play both "victim" and "agent" in the CNS which raises a number of questions. Here, we summarize immunologic changes in OL-lineage cells and their effects, as well as consider OL-lineage cell changes which influence immune cells under pathological conditions. We also describe some of the underlying mechanisms of these changes and their effects. Finally, we describe several studies which use OL-lineage cells as immunotherapeutic targets for demyelination diseases.