Category: Nature

A group from Clinical Medicine Scientific and Technical Innovation Center, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, China, etc. has reported about a negative role of PD-L1 expression on the host immune response, which inhibits neutrophil migration from the bone marrow into the infected sites for favoring immune escape of fungi infections. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9652346/ Candida albicans is both a commensal and opportunistic fungal pathogen of humans. During systemic infection, C. albicans enters the bloodstream and disseminates throughout the body, causing the disease known as invasive candidiasis. The successful clearance of C. albicans from the host mainly relies on neutrophils by releasing proinflammatory cytokines, producing reactive oxygen species and anti-microbial peptides, and forming neutrophil extracellular traps. PD-L1 is found to be expressed on the plasma membrane of immune cells, including neutrophils, B cells, dendritic cells, and macrophages. During C. albicans infection, β-glucans exposed on the cell wall of C. albicans play an important role in modulation of the host response. The C-type lectin receptor Dectin-1 (encoded by Clec7a gene) is the most important neutrophil pattern recognition receptor for the recognition of β-glucans. In this study, it was demonstrated that activation of Dectin-1 by fungal β-glucans induced PD-L1 expression in murine and human neutrophils, and the upregulated PD-L1 inhibits neutrophil migration from the bone marrow into the infected sites through regulating their autocrine secretion of chemokines CXCL1 and CXCL2. This finding provides new insights that PD-L1 would function as a potent therapeutic target of neutrophil-based immunotherapy against fungal infections through regulating neutrophil release from the bone marrow. That is, either PD-L1 blockade or pharmacological inhibition of PD-L1 expression significantly increased neutrophil release from bone marrow to enhance host antifungal immunity.

A group from Key Laboratory of Integrated Management of Crop Diseases and Pests, Department of Plant Pathology, Nanjing Agricultural University, China, etc. has reported that halophilic Bacillus strains to enhance plant growth and reduced the adverse effect of saline stress on wheat through regulation of salt resistant genes https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9608499/ Salinity has a detrimental effect on wheat growth by inducing physiological and metabolic disorders that lead to oxidative stress, osmotic stress, nutritional abnormalities, membrane dysfunction, reduced photosynthetic activity and improper hormone function. Plants under salt stress often overproduce reactive oxygen species (ROS), i.e., superoxide (O2−) and hydrogen peroxide (H2O2) leads to protein, cell wall and nucleic acid damage. The aim of this study was to evaluate the potential of Bacillus strains isolated from the Qinghai–Tibet region of China to enhance plant growth and reduce the adverse effect of saline stress on wheat. The selected Bacillus strains as PGPR, FZB42, NMCN1, and LLCG23, were able to grow on up to 10% NaCl, 18% NaCl, and 14% NaCl LB medium, respectively. The inoculation of NMCN1 and LLCG23 significantly enhanced wheat growth parameters in terms of physiological traits, i.e., fresh weight 31.2% and 29.7%, dry weight 28.6% and 27.3%, shoot length 34.2% and 31.3% and root length 32.4% and 30.2%, respectively, as compared to control plants under high NaCl concentration (200 mmol). It was found that salt-resistant genes in bacteria, DegU, OstB, OhrR, ComA, SodA, and OpuAC, were all up-regulated under saline conditions. And further, the plants inoculated with NMCN1 under salt stress (200 mmol NaCl) significantly overexpressed the genes in wheat related to expansin (expA1), cytokinin (CKX2) and auxin (ARF), followed LLCG23 and FZB42. The expression of ethylene encoding gene (ERF) was noticed to be highly downregulated in wheat plants treated with NMCN1 strain grown under the same stress condition.  The wheat plants treated with highly halophilic bacteria, NMCN1, were noticed to highly express the salt-resistant genes (MYB, DREB2, HKT1 and WRKY17), followed by LLCG23 and FZB42, as shown below.

A group from Basque Research & Technology Alliance (BRTA), Chemical Glycobiology Group, CIC bioGUNE, Bizkaia, Spain, etc. has reported that solution NMR and surface-based microarray studies provide different results on the molecular recognition features of LSECtin toward bi-antennary N-glycans. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9615123/ The molecular recognition features of LSECtin (CLEG4G) toward asymmetric N-glycans have been scrutinized by NMR and compared to those occurring in glycan microarrays. Strikingly, NMR studies confirmed that both asymmetric LDN3 and LDN6 N-glycans are recognized by LSECtin with similar affinities in solution, which is different in contrast to the results obtained when those glycans are presented on microarrays, where only LDN6 was efficiently recognized by the lectin. Molecular recognition details differ from solution state to surfaces. Which one is closer to those existing in nature? Glycans are usually exposed on cell surfaces as part of glycoconjugates forming the glycocalyx. It is tempting to propose that the studies conducted using arrays are closer to those taking place on cell surfaces. However, the surface of slide glass is compretely different from actual cell surface glycocalyxes. Also, the length and chemical nature of the linkers used to attach the ligands to surfaces, and the composition of the solid support itself, could also influence the final outcome and the interpretation of the obtained results.

A group from Frontier Research Center for Advanced Material and Life Science, Hokkaido University, Sapporo, Japan, etc. has reported about interactions between galectins and O-mannosylated glycopeptides of α-dystroglycan, especially focusing on its core M1 structure. https://www.nature.com/articles/s41598-022-22758-0 The O-linked mannose (O-Man) exists in a limited number of proteins that are required for normal development and have vital functions in muscle and neural physiology. The α-dystroglycan (α-DG) is the extracellular component of dystroglycan (DG), and is the most extensively studied mammalian O-Man glycoprotein. It is ubiquitously expressed in the skeletal muscles and the brain and is associated with cell adhesion, muscle integrity, and neurological development. α-DG possesses unique glycans, LacNac-terminated three kind of core structures (M1, M2, and M3), in its mucin (MUC)–like domain. In this study, it was shown that Human Gal-1, -4, and -9 (except -3) can strongly recognize O-Man LacNAc-terminated glycoconjugates, and the presence of an α2,3-sialylated terminus led to a major reduction in the affinity of galectin, suggesting that this type of extension can fine-tune galectin activity towards this type of O-Man glycans. These interactions were significantly inhibited by lactose, establishing that the α-DG core M1-type glycans bind to the canonical sugar-binding site (S-face) of galectin, thus serving as a receptor for galectins. And further, it was shown in microarray experiments that Gal-1 revealed trans-bridging capabilities, linking laminin-111, -121, -211, and -221 (but little -511) and core M1 α-DG glycopeptides as shown below, providing a new insight on the therapeutic application of this galectin in muscular dystrophy. Fluorescence images of M1 glycoconjugates microarrays with laminins plus galectins

A group from Engineering Research Center of Agricultural Microbiology Technology, Ministry of Education, Heilongjiang University, Harbin, China, etc. has reported about effects of inoculation of AM fungi (Rhizophagus intraradices) on soybean yield and the composition of microbial communities. https://www.nature.com/articles/s41598-022-22473-w The field experiment was done in triplicate with AM fungal treatments (non-inoculated and inoculated with Rhizophagus intraradices) and continuous cropping regimes (0 and 1 year of continuous cropping for soybean) as factors, i.e., there were four conditions, In0, In1, Non0, and Non1. The effect of AM fungal inoculation was seen greatly in the composition of fungal communities rather than the composition of bacterial communities. As shown below, the most dominant genus was Subulicystidium in In1YSF and Non1YSF. However, Fusarium was the most dominant genus in In0YSF and Non0YSF. Interestingly, the relative abundance of Fusarium decreased significantly  from 15.72% in Non0YSF to 1.58% in In0YSF. In response to this, the disease index of soybean root rot was significantly decreased by the inoculation of AM fungi. For example, the disease index with the AM fungal inoculation decreased to 66%. The growth/yield indexes of soybean increased by the AM fungal inoculation, and it was the highest in the inoculated soybean plants under non-continuous cropping.