Month: January 2023

A group from Departamento de Medicina y Zootecnia de Cerdos, Universidad Nacional Autónoma de México, Ciudad de México, Mexico, etc. has reported about changes in glycosylation of B cells and T cells in systemic lupus erythematosus (SLE) patients.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9820943/

Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect every organ and system in the body.

In the case of B cells, glycosylation studies have been directed primarily at immunoglobulins. SLE patients have alterations in the glycosylation of immunoglobulin G. A greater recognition of the AAL lectin, which has an affinity for fucosylated residues, has been observed in comparison with healthy individuals. Increased recognition of the LCA lectin, which is specific for the core fucosylated trimannose N-glycan, towards immunoglobulin G has been also reported in SLE patients. Using ultra-resolution liquid chromatography, it was also found that they present a decrease in IgG galactosylation and sialylation.

It has been shown that T cells from SLE patients present alterations in O-glycosylation using the ALL lectin, which recognizes core 1 in coactivating T cell receptors. T cells from patients with active SLE had less recognition by ALL than those with inactive SLE, and expression of receptors recognized by ALL was inversely correlated with disease activity. Another study reported increased expression of Tn antigen-type O-glycans in T cells from SLE patients using VVA lectin.

A decrease in O-GlcNAcylation and phosphorylation of E74-like factor 1 (ELF-1) has been observed in SLE patients.

A group from Department of Experimental and Translational Ophthalmology, University Medical Center, Johannes Gutenberg University, Mainz, Germany has reported about characterization of N-glycoproteins from human tear films.
https://pubmed.ncbi.nlm.nih.gov/36677706/

The main objective of this study was to develop a lectin-based affinity purification method for the enrichment of glycoproteins/glycopeptides from human tear film and the MS-based detection as well as localization of their specific N-glycosylation sites.

The best-performing multi-lectin column system (comprising the four lectins ConA, JAC, WGA, and UEA I, termed 4L) was applied to glycopeptide enrichment from human tear sample digests. As the main result, a total of 26 N glycosylation sites of 11 N-glycoproteins (LIF, PIGR, IGHA2, IGHA1, AZGP1, LACRT, JCHAIN, PIP, TF, HP, and SERPINA1) was identified in the tear sample pools of healthy individuals.

This result will serve as an important N-glycoprotein reference map for future studies focusing on the ocular surface and will help to unravel the complex regulatory functions of N-glycoproteins in maintaining tear film stability and the ocular defense system.

A group from Division of Molecular Pathobiology, International Institute for Zoonosis Control, Hokkaido University, Sapporo, Japan, etc. has reported about isolation and characterization of distinct Rotavirus A (RVA) in bat and rodent hosts.
https://pubmed.ncbi.nlm.nih.gov/36633410/

Here, RVA was isolated from Egyptian fruit bat and Natal multimammate mouse collected in Zambia (representative strains: 16-06 and MpR12).
The RVA genome consists of 11 dsRNA segments, each encoding 6 structural viral proteins (VPs) and 5 or 6 nonstructural proteins (NSPs). RVA has a nonenveloped, triple-layered virion, with the outer capsid layer consisting of the spike protein VP4 and the glycoprotein VP7.

It was found that 16-06 entered cells by binding to sialic acids on the cell surface, while MpR12 entered in a sialic acid-independent manner. Notably, glycan-binding analysis suggested that 16-06 recognizes both human and animal-type sialic acid, NeuAc and NeuGc.

A group from State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China, etc., has reported about differences in microbial communities between wild and cultivated Rice.
https://pubmed.ncbi.nlm.nih.gov/36625666/

The core rice phyllosphere bacteria contained 27 Proteobacteria that made up 62.8% of relative abundance, and Pantoea was the most abundant genus (42.7%), followed by Methylobacterium (4.8%), Pseudomonas (3.6%), Acinetobacter (2.9%), and Serratia (2.1%). Except for Proteobacteria, Actinobacteriota (11.7%), Firmicutes (8.5%), and Bacteroidota (0.5%) were the abundant phyla of the core phyllosphere bacteria. As for fungi, 29 core fungal ASVs were mainly classified in the genera of Nigrospora (13.2%), Pyrenophora (13.1%), Papiliotrema (12.5%), and Phaeosphaeria (4.5%). Although the core taxa were present in all the samples, the relative abundance of these ASVs varied significantly across rice species and sampling sites.

For bacteria, Xanthomonas, Klebsiella and Sphingomonas were mostly enriched in the wild rice. Meanwhile, there were some core bacteria significantly enriched in the wild rice, such as Methylobacterium, Xanthomonas, Hymenobacter, and Klebsiella. Compared to the cultivated rice, Methylobacterium was the most enriched genus in wild rice. For fungi, Khuskia, Acidomyces, and Pyrenophora were mostly enriched in the wild rice, while none of core fungal taxa were enriched in the wild rice. Compared to the wild rice, Pseudomonas and Comamonas were the main enriched bacterial genera in the cultivated rice, and Chaetomium, and Rhodotorula were the main enriched fungal genera in the cultivated rice, respectively.

From a view point of functional profiles of the rice phyllosphere microbiome, significantly higher functional potentials of methanol oxidation (+594%), methylotrophy (+460%), ureolysis (+430%), and photoheterotrophy (+345%) were expected in wild rice than in cultivated rice (P < 0.05) (Fig. S5C). In addition, cultivated rice had significantly higher potentials of plant pathogens (+91%), human-associated (+88%) and human pathogens (+88%).

A group from Institute of Physiology, University of Zurich, Zurich, Switzerland, etc. has reported that increase of intestinal bacterial sialidase activity exacerbates acute colitis in mice.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9780602/

The gut microbiota mainly consists of the phyla Bacteroidetes and Firmicutes, while members of Actinobacteria, Verrucomicrobia, Fusobacteria and Proteobacteria represent a minor fraction. The gut microbiota plays a vital role in human health, supplying essential nutrients, training the immune system, and helping to protect against pathogens. The gut microbiota is also involved in the host metabolism and has been linked to a variety of chronic diseases.

Gut microbes express a multitude of genes, including a vast group of carbohydrate-active enzymes, which are required to digest complex oligo- and polysaccharides. In addition to digesting dietary carbohydrates, these enzymes are also active on the thick mucus layer lining intestinal surfaces. The cleavage of host glycans by bacterial GHs may also alter carbohydrate structures involved in cell adhesion, trafficking and activation. Especially fucosylated and sialylated epitopes are recognized by endogenous lectins, such as selectins and siglec, which regulate leukocyte trafficking and activation, respectively.

To investigate the impact of bacterial glycoside hydrolase activities on the gut microbial composition and on host glycans during colon inflammation, local glycoside hydrolase activity was promoted by supplementing mice developed acute colitis with recombinant E. coli expressing specific sialidase, fucosidase and rhamnosidase enzymes. Interestingly, whereas increased fucosidase and rhamnosidase activity did not alter the course of colitis, increased sialidase activity exacerbated disease severity.

Of note, the microbial composition of mice gavaged with recombinant E. coli expressing specific sialidase, fucosidase and rhamnosidase enzymes had little changes in the gut microbiota composition.

On the other hand, it was found that the sialic acid on mucosal glycans and also on resident leukocytes in the colon mucosa was cleaved from PNA stainning and siglec ligand staining experiments.

PNA staining in proximal colon

As a conclusion, the remodeling of surface sialylation caused by increased sialidase activity could account for the observed exacerbation of acute colitis in mice due to down-regulate activation of immune cells.

A group from College of Life Sciences, Shaanxi Normal University, Xi’an, Shaanxi, China, etc, has reported about changes in glycan patterns and glycan-related genes in the medial prefrontal cortex of autism spectrum disorders (ASD) rats.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9772556/

With using lectin microarrays, the following changes in glycosylation were found in ASD rats.
(1) Branched high-mannose (recognized by ConA) was upregurated in ASD rats,
(2) complex-type antennary agalacto N-glycan (recognized by GSL-II and PHA-E) was up-regulated in ASD rats, and
(3) Siaα2-3 Gal/GalNAc (recognized by WGA and MAL-I) and terminal GalNAc structure (recognized by BPL and VVA) were down-regulated in ASD rats.