Human Dectin-1 deficiency impairs macrophage-mediated defense against phaeohyphomycosis

A group from Fungal Pathogenesis Section and Immunopathogenesis Section, Laboratory of Clinical Immunology and Microbiology (LCIM), National Institute of Allergy and Infectious Diseases (NIAID), NIH, Bethesda, Maryland, USA, etc. has reported that human Dectin-1 deficiency impairs macrophage-mediated defense against phaeohyphomycosis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9663159/ Phaeohyphomycosis is an invasive fungal infection caused by dematiaceous fungi, which are characterized by melanin production and filamentous growth. Phaeohyphomycosis typically affects the subcutaneous tissues following traumatic inoculation and is treatable with antifungal therapy and/or surgical resection. In this study, an index patient with severe phaeohyphomycosis caused by Corynespora cassiicola, a dematiaceous fungus of plants known to cause life-threatening infections in CARD9 deficiency is highlighted. This patient had biallelic deleterious mutations in CLEC7A, which encodes the CARD9-coupled receptor, Dectin-1. It was shown that Dectin-1 is critical for IL-1β and TNF-α production against this fungus by human immune cells, which enhances macrophage fungal killing. CARD9 is an immune adapter protein in myeloid cells involved in C-type lectin signaling and antifungal immunity. 17 additional unrelated patients with severe phaeohyphomycosis were also evaluated, and t was found that 12 out of 17 had deleterious CLEC7A mutations, which were associated with an altered Dectin-1 extracellular, β-glucan–binding, C-terminal domain, and impaired Dectin-1–dependent cytokine production. showing proinflammatory cytokine responses to this fungus from the Dectin-1–deficient patient and from CARD9-deficient patients.

Read more

A new therapeutic method focusing on inhibition of PD-L1 against Candida albicans

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.

Read more

Characteristic glycan modification of SARS-CoV-2 Omicron variant comparing with other variants

A group from Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, etc. has reported about characteristic glycan modification of SARS-CoV-2 Omicron variant comparing with other variants. https://pubmed.ncbi.nlm.nih.gov/36318020/ I thought I would stop blogging about SARS-CoV-2, but I would like to briefly introduce this paper it as a topic related to comparative glycan profiling analysis using lectin microarrays. From the comparative glycan profiling analysis, it was found that SARS-CoV-2 Omicron showed higher levels of terminal fucose (UEA-I), and also showed higher level of sialylated (MAL-II, MAA, ASNA-I) and galactosylated glycans (CSA, WFA, SBA, VVL) than other variants (Alpha, Beta, and Delta). SARS-CoV-2 Omicron was more susceptible to neutralization antibodies after neuraminidase or galactosidase treatment. This means that the higher expression of both Sia- and Gal-containing glycans on Omicron potentially enhance its shielding effect against neutralization.

Read more

halophilic Bacillus strains to enhance plant growth and reduced the adverse effect of saline stress on wheat through regulation of salt resistant genes

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.

Read more

Glycan binding specificity of LSEspecificity of LSECtin (CLEG4G) is different between solution NMR and Glycan

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.

Read more

N-type glycosylated proteomics overview of human Alzheimer’s disease brain

A group from Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, USA, etc. has reported about N-type glycosylated proteomics overview of normal, asymptomatic and symptomatic human Alzheimer’s disease brain. https://www.mcponline.org/article/S1535-9476(22)00241-9/fulltext The neuropathological hallmark of AD is the formation of β-amyloid (Aβ)-containing extracellular deposits and progression of intraneuronal neurofibrillary tangles from hyperphosphorylated tau. To investigate the larger glycoprotein landscape, a qualitative N-type glycosylated proteomics analysis of brain samples was performed from 30 humans including those with normal, asymptomatic AD, and symptomatic AD. A combination of lectin affinity isolation and hydrophilic interaction chromatography (HILIC) was optimized and employed to selectively enrich N-glycoproteins prior to LC-MS/MS analysis. A combination of ConA, RCA, SNA, WGA, VVA, and AAL could target the major monosaccharide components of N-glycans in the brains. As a result, a total of 303 glycoproteins were identified from 2,035 unique glycopeptides, 580 N-linked glycosylation sites, and 124 glycans, making up a total of 1,901 glycoforms (remark: if a single glycosylation site was identified with three different glycans, they are counted as three glycoforms) that were identified from all samples. The most abundant glycans range within the 1201-1250 MW range, which contribute to over 20% of the total glycoforms detected from the samples based on the glycan composition. The majority of glycans in this MW range are from Man5GlcNAc2 (Man5) structure. The second most frequent glycan is assigned as a biantennary glycan with a bisecting GlcNAc and core fucosylation. Other common glycans include several high-mannose, complex, and hybrid N-glycans with different degrees of fucosylation on glycopeptides were identified across the tissues. When considering the distribution based on the overall glycoforms, there is no statistical difference in the glycan molecular weight or glycan distribution among the different sample types. To gain more information about the glycosylation pattern in different sample groups, it was analyzed at glycosylation site level, When comparing different sample types (normal, asymptomatic AD, and symptomatic AD) for the collective changes in glycosylation across different glycosylation sites, it was observed that a decrease in galactosylation, fucosylation, bisection, and the number of antennary glycans in asymptomatic and symptomatic AD samples, compared with normal brain samples. For asymptomatic compared to symptomatic AD samples, there are generally higher levels of galactosylation, fucosylation, bisection, and the number of antennary and hybrid glycans. A definitive N-type glycan marker unique to Alzheimer’s disease has yet to be found.

Read more

Duality of the Vi Capsular Polysaccharide of Salmonella Typhi

A group from Department of Medical Microbiology and Immunology, University of California at Davis, Davis, California, USA, etc. has reported about duality of the Vi Capsular Polysaccharide of Salmonella Typhi. https://journals.asm.org/doi/10.1128/mbio.02733-22 Bacterial pathogens overcome innate host defenses by either (i) evading opsonization and phagocytosis, which is the strategy used by extracellular pathogens, or (ii) evading killing during phagocytosis and take residence within the phagocyte, which is the approach taken by intracellular pathogens. The enterica serovar Typhi is the causative agent of typhoid fever, a severe disseminated infection characterized by persistence of the pathogen in small granulomas, termed typhoid nodules, which are accumulations of mononuclear phagocytes and lymphocytes. S. Typhi synthesizes a virulence-associated (Vi) capsular polysaccharide, also known as the Vi-antigen, which protects bacteria from opsonization with natural IgM, thereby preventing engulfment by phagocytic host cells such as neutrophils and macrophages. However, it is paradoxical that S. Typhi has such an antiphagocytic capsule, because S. Typhi is typical intracellular pathogen. In this work, the duality of the S. Typhi Vi capsular polysaccharide was shown. The Vi capsular antigen allows S. Typhi to selectively evade phagocytosis by neutrophils, while promoting macrophage phagocytosis, by binding to DC-SIGN, C-type lectin expressed on macrophages. where, tviB-vexE is a mutant of S. Typhi with noncapsulated

Read more

Immune-enhancing activity of polysaccharides from wild mushroom (Gymnopilus imperialis)

A group from Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Brazil, etc. has reported about immune-enhancing activity of polysaccharides from wild mushroom (Gymnopilus imperialis). https://www.mdpi.com/1424-8247/15/10/1179 In this study, the aqueous extract was obtained from dried basidiomata of G. imperialis, which was fractioned by several steps yielding three main polysaccharide fractions (Gi-MRSW, Gi-FSME, and Gi-FPME) as shown below. Among those polysaccharides, only the Gi-MRSW fraction displayed immune-enhancing activity on murine macrophages similar to LPS. The detailed molecular structure was not mentioned here.

Read more

Interactions between galectins and O-mannosylated core M1 glycopeptides of α-dystroglycan

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

Read more

Affects of AM fungi inoculation on soybean yield and the composition of microbial communities

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.

Read more