Comparative lectin histochemistry on the murine respiratory tract and primary olfactory pathway using a fully automated staining procedure

Lectins are naturally occurring molecules which bind to specific carbohydrates of glycoconjugates. The binding specificity of lectins can therefore be used to specifically elucidate the glycosylation pattern in various tissues. While lectin histochemistry is usually carried out manually on single slides, a fully automated immunostaining system offers an easy, standardized, and high throughput system. In this study lectin histochemistry was implemented and optimized on a fully automated immunostaining system to investigate glycosylation patterns in the murine respiratory tract and the primary olfactory pathway. We tested 22 commercially available biotinylated lectins for their labelling-profiles to specifically identify morphologic structures. The results showed that lectin staining profiles using the implemented protocol on the automated system were constant and suitable for high throughput morphological studies. Further, the morphological evaluation of the stained slides revealed a complete characterization of the murine respiratory tract and primary olfactory pathway including the lectin binding profiles for the olfactory bulb, the vomeronasal organ and the nasal-associated lymphoid tissue.

Similarity assessment by multivariate statistics method based on the distance between biosimilar and originator

The development of biosimilar products or follow-on biologics has been flourishing in recent years because of their lower price than the originators. In this study, a multivariate data analysis method based on JMP software was proposed to assess the glycosylation pattern similarity of antibody candidates from different conditions in optimization experiments with a reference. A specific distance was generated by this method and indicated the glycoform similarity between the biosimilar and the reference. This method can be applied to analyze the similarity of other physicochemical and functional characteristics between follow-on biologics and originators. Then, the design of experimental methods can be realized to optimize the conditions of cell culture to attain similar antibody candidates. A higher concentration of GlcNAc added to the basal media made the glycan of the antibody more similar to the glycan of the reference in this study.

Impedimetric aptamer-based glycan PSA score for discrimination of prostate cancer from other prostate diseases

Prostate specific antigen (PSA) is the common biomarker for prostate cancer (PCa). However, its lack of specificity to differentiate PCa from benign prostate disorders stimulates the search for alternative cancer biomarkers to improve the clinical management of the patients. Different studies have described changes in the core-fucosylation level of PSA between PCa patients and healthy controls. To exploit these findings, we have adapted an impedimetric aptamer-based sensor to the dual recognition of PSA. Two different aptamers, PSAG-1 and anti-PSA, are immobilized onto two adjacent nanostructured gold electrodes. The direct binding from diluted serum samples of specific glycosylated-PSA to the first sensor and total PSA to the second one leads to changes in the charge transfer resistance, which correlate to the amount of glycosylated and total PSA in the sample. The sensors are able to measure PSA in serum with a dynamic range between 0.26 and 62.5 ng/mL (PSAG-1) and from 0.64 to 62.5 ng/mL (anti-PSA), with a reproducibility of 5.4 %. The final output of the proposed platform is the ratio between PSAG-1 reactive PSA and total PSA, defined as the glycan score. The glycan score was tested in serum samples from patients with different pathologies, showing excellent correlation between the measured score and the known diagnosis of the patients. Hence this dual aptamer-based impedimetric biosensor could be used as a minimally invasive method for the diagnosis of prostate cancer.

Mucosal and systemic immune responses in Senegalese sole (Solea senegalensis Kaup) bath challenged with Tenacibaculum maritimum: A time-course study

Tenacibaculosis, caused by Tenacibaculum maritimum, continues to inflict substantial losses among cultured marine species, particularly in the Senegalese sole. However, the immune mechanisms in fish involved in fighting against this disease are still poorly understood. Thus, the present study aimed to investigate the skin mucus's terminal carbohydrate composition, several immune-related enzymes (i.e. lysozyme, peroxidase, proteases and antiproteases), the haemolytic activity of complement and the bactericidal activity in the skin mucus and plasma of the Senegalese sole in a time-course study following a bath challenge with T. maritimum. The haematological profile and the kinetics of cell migration post-infection were also considered. The bath challenge induced slight variations in the terminal carbohydrate composition of Senegalese sole skin mucus. In general, results from this study showed a delay in the mucosal immune response compared to that found at the systemic level (i.e. blood and plasma). For instance, a significant increase in the skin mucus's lysozyme, complement, protease and antiprotease activities were observed at the end of the experiment (14 d post-challenge). Interestingly, the higher activity of these enzymes could be related to the skin mucus's bactericidal capacity and haemolytic complement activity, suggesting that these enzymes play an important role in the defence against Gram-negative bacteria. The haematological profile revealed a significant increase in circulating neutrophils in challenged fish after 48 and 72 h, which was positively correlated to the increments observed in peroxidase and lysozyme activities, respectively, in the plasma of challenged fish at the same time. Although the route of entry and the survival strategy of T. maritimum are still not fully elucidated, results from the present study will contribute to this endeavour through the study of the mucosal immune responses of fish against this particular pathogen.

Particle-based N-linked glycan analysis of selected proteins from biological samples using nonglycosylated binders

Glycosylation is one of the most common and important post-translational modifications, influencing both the chemical and the biological properties of proteins. Studying the glycosylation of the entire protein population of a sample can be challenging because variations in the concentrations of certain proteins can enhance or obscure changes in glycosylation. Furthermore, alterations in the glycosylation pattern of individual proteins, exhibiting larger variability in disease states, have been suggested as biomarkers for different types of cancer, as well as inflammatory and neurodegenerative diseases. In this paper, we present a rapid and efficient method for glycosylation analysis of individual proteins focusing on changes in the degree of fucosylation or other alterations to the core structure of the glycans, such as the presence of bisecting N-acetylglucosamines and a modified degree of branching. Streptavidin-coated magnetic beads are used in combination with genetically engineered immunoaffinity binders, called VHH antibody fragments. A major advantage of the VHHs is that they are nonglycosylated; thus, enzymatic release of glycans from the targeted protein can be performed directly on the beads. After deglycosylation, the glycans are analyzed by MALDI-TOF-MS. The developed method was evaluated concerning its specificity, and thereafter implemented for studying the glycosylation pattern of two different proteins, alpha-1-antitrypsin and transferrin, in human serum and cerebrospinal fluid. To our knowledge, this is the first example of a protein array-type experiment that employs bead-based immunoaffinity purification in combination with mass spectrometry analysis for fast and efficient glycan analysis of individual proteins in biological fluid.

Changes of protein glycosylation in the course of radiotherapy

This is the first study of changes in protein glycosylation due to exposure of human subjects to ionizing radiation. Site specific glycosylation patterns of 7 major plasma proteins were analyzed; 171 glycoforms were identified; and the abundance of 99 of these was followed in the course of cancer radiotherapy in 10 individual patients. It was found that glycosylation of plasma proteins does change in response to partial body irradiation (∼ 60 Gy), and the effects last during follow-up; the abundance of some glycoforms changed more than twofold. Both the degree of changes and their time-evolution showed large inter-individual variability.