Levels of mannose-binding lectin (MBL) associates with sepsis-related in-hospital mortality in women

Some Human Anti-Glycan Antibodies Lack the Ability to Activate the Complement System

Background. Naturally occurring human antibodies against glycans recognize and quickly eliminate infectious bacteria, viruses and aberrantly glycosylated neoplastic malignant cells, and they often initiate processes that involve the complement system. Methods. Using a printed glycan array (PGA) containing 605 glycoligands (oligo- and polysaccharides, glycopeptides), we examined which of the glycan-binding antibodies are able to activate the complement system. Using this PGA, the specificities of antibodies of the IgM and IgG classes were determined in the blood serum of healthy donors (suggested as mostly natural), and, then, using the same array, it was determined which types of the bound immunoglobulins were also showing C3 deposition. Results. It was found that about 30% of anti-glycan antibodies in human serum detected by the PGA did not activate the complement. They were mostly IgGs and directed to bacterial O-antigens; no apparent common structural motif within their target polysaccharides was found. Antibodies to blood group systems ABO and Forssman, xeno-antigens, a number of polysaccharides from various strains of S. enterica, E. coli and P. alcalifaciens, as well as small fragments of bacterial polysaccharides were recognized by complement-activating antibodies as expected. A complement-activating antibody was affinity-isolated on glycan-Sepharose from human serum, and, in the presence of the complement, it lysed red blood cells coated with the same glycan (kodecytes, where glycans expressed on biological membranes), while an isolated complement non-activating antibody did not, which confirms the validity of the solid-phase PGA results. Conclusions. Thus, ~30% of human anti-glycan antibodies lack the ability to activate the complement system. The function of the widely represented immunoglobulins that do not cause C3 deposition remains unclear.

Acoustic ejection mass spectrometry empowers ultra-fast protein biomarker quantification

The global scientific response to COVID 19 highlighted the urgent need for increased throughput and capacity in bioanalytical laboratories, especially for the precise quantification of proteins that pertain to health and disease. Acoustic ejection mass spectrometry (AEMS) represents a much-needed paradigm shift for ultra-fast biomarker screening. Here, a quantitative AEMS assays is presented, employing peptide immunocapture to enrich (i) 10 acute phase response (APR) protein markers from plasma, and (ii) SARS-CoV-2 NCAP peptides from nasopharyngeal swabs. The APR proteins were quantified in 267 plasma samples, in triplicate in 4.8 h, with %CV from 4.2% to 10.5%. SARS-CoV-2 peptides were quantified in triplicate from 145 viral swabs in 10 min. This assay represents a 15-fold speed improvement over LC-MS, with instrument stability demonstrated across 10,000 peptide measurements. The combination of speed from AEMS and selectivity from peptide immunocapture enables ultra-high throughput, reproducible quantitative biomarker screening in very large cohorts.

A Nanoplasmonic Assay for Point-of-Care Detection of Mannose-Binding Lectin in Human Serum

Mannose-binding lectin (MBL) activates the complement system lectin pathway and subsequent inflammatory mechanisms. The incidence and outcome of many human diseases, such as brain ischemia and infections, are associated with and influenced by the activity and serum concentrations of MBL in body fluids. To quantify MBL levels, tests based on ELISA are used, requiring several incubation and washing steps and lengthy turnaround times. Here, we aimed to develop a nanoplasmonic assay for direct MBL detection in human serum at the point of care. Our assay is based on gold nanorods (GNRs) functionalized with mannose (Man-GNRs) via an amphiphilic linker. We experimentally determined the effective amount of sugar linked to the nanorods' surface, resulting in an approximate grafting density of 4 molecules per nm2, and an average number of 11 to 13 MBL molecules binding to a single nanoparticle. The optimal Man-GNRs concentration to achieve the highest sensitivity in MBL detection was 15 μg·mL-1. The specificity of the assay for MBL detection both in simple buffer and in complex pooled human sera was confirmed. Our label-free biosensor is able to detect MBL concentrations as low as 160 ng·mL-1 within 15 min directly in human serum via a one-step reaction and by using a microplate reader. Hence, it forms the basis for a fast, noninvasive, point-of-care assay for diagnostic indications and monitoring of disease and therapy.

Mannose-binding lectin gene polymorphism in psoriasis and vitiligo: an observational study and computational analysis

Introduction

Psoriasis and vitiligo are inflammatory autoimmune skin disorders with remarkable genetic involvement. Mannose-binding lectin (MBL) represents a significant immune molecule with one of its gene variants strongly linked to autoimmune diseases. Therefore, in this study, we investigated the role of the MBL variant, rs1800450, in psoriasis and vitiligo disease susceptibility.

Methods

The study comprised performing in silico analysis, performing an observational study regarding psoriasis patients, and performing an observational study regarding vitiligo patients. Various in silico tools were used to investigate the impact of the selected mutation on the function, stability, post-translational modifications (PTMs), and secondary structures of the protein. In addition, a total of 489 subjects were enrolled in this study, including their demographic and clinicopathological data. Genotyping analysis was performed using real-time PCR for the single nucleotide polymorphism (SNP) rs1800450 on codon 54 of the MBL gene, utilizing TaqMan genotyping technology. In addition, implications of the studied variant on disease susceptibility and various clinicopathological data were analyzed.

Results

Computational analysis demonstrated the anticipated effects of the mutation on MBL protein. Furthermore, regarding the observational studies, rs1800450 SNP on codon 54 displayed comparable results in our population relative to global frequencies reported via the 1,000 Genomes Project. This SNP showed no significant association with either psoriasis or vitiligo disease risk in all genetic association models. Furthermore, rs1800450 SNP did not significantly correlate with any of the demographic or clinicopathological features of both psoriasis and vitiligo.

Discussion

Our findings highlighted that the rs1800450 SNP on the MBL2 gene has no role in the disease susceptibility to autoimmune skin diseases, such as psoriasis and vitiligo, among Egyptian patients. In addition, our analysis advocated the notion of the redundancy of MBL and revealed the lack of significant impact on both psoriasis and vitiligo disorders.

The Role of Complement in HSCT-TMA: Basic Science to Clinical Practice

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) is a common complication occurring post-HSCT and is associated with substantial morbidity and mortality if not promptly identified and treated. Emerging evidence suggests a central role for the complement system in the pathogenesis of HSCT-TMA. The complement system has also been shown to interact with other pathways and processes including coagulation and inflammation, all of which are activated following HSCT. Three endothelial cell-damaging “hits” are required for HSCT-TMA genesis: a genetic predisposition or existing damage, an endothelial cell-damaging conditioning regimen, and additional damaging insults. Numerous risk factors for the development of HSCT-TMA have been identified (including primary diagnosis, graft type, and conditioning regimen) and validated lists of relatively simple diagnostic signs and symptoms exist, many utilizing routine clinical and laboratory assessments. Despite the relative ease with which HSCT-TMA can be screened for, it is often overlooked or masked by other common post-transplant conditions. Recent evidence that patients with HSCT-TMA may also concurrently present with these differential diagnoses only serve to further confound its identification and treatment. HSCT-TMA may be treated, or even prevented, by removing or ameliorating triggering “hits”, and recent studies have also shown substantial utility of complement-targeted therapies in this patient population. Further investigation into optimal management and treatment strategies is needed. Greater awareness of TMA post-HSCT is urgently needed to improve patient outcomes; the objective of this article is to clarify current understanding, explain underlying complement biology and provide simple tools to aid the early recognition, management, and monitoring of HSCT-TMA.

Mannose-Binding Lectin 2 Gene Polymorphism during Pandemic: COVID-19 Family

Mannose-binding lectin 2 (MBL2) is a serine protease which is believed to be an important factor in the inherited immune system. In this article, we present a coronavirus disease 2019 (COVID-19) family of five patients: a 56-year-old father, a 51-year-old mother, two sons aged 23 and 21 years, and a 15-year-old daughter. According to the results of MBL2rs1800450 variant analysis performed, the father had homozygous mutant, the mother had homozygous normal, and the three children had heterozygous mutant genotype. When we compared the clinical parameters and genotypes, MBL2 gene polymorphism plays a very important role in COVID-19 susceptibility and severe disease. The family, which makes up our study, is the proof of this situation, and it contains important implications for host factors and COVID-19.

Role of MBL2 Polymorphisms in Sepsis and Survival: A Pilot Study and In Silico Analysis

Sepsis is a serious infection-induced syndrome with serious ramifications, especially in intensive care units. Global concern motivated the investigation of the role of related genes’ polymorphism in predicting the liability to infection, sepsis, septic shock and survival. Among these genes is the gene encoding mannose-binding lectin (MBL), with its remarkable importance in the immune system. However, the previous studies showed conflicting results and ambiguity that urged us to engage with this issue in the Egyptian population. Prediction of functional and structural impacts of single nucleotide polymorphisms (SNPs) was done using in silico methods. A prospective observational study was conducted in intensive care units; one hundred and thirty patients were followed up. Genotyping was performed using real-time polymerase chain reaction (RT-PCR) technology. MBL SNPs showed a remarkable high frequency in our population, as well. No significant association was found between MBL2 genotypes and any of our analyses (sepsis, septic shock and survival). Only septic shock and age were independently associated with time of survival by Cox regression analysis. Our study may confirm the redundancy of MBL and the absence of significant impact on sepsis liability and mortality in adult patients.

Association of mannose-binding lectin 2 (MBL2) and suppressor of cytokine signaling-1 (SOCS1) gene variants in children with febrile neutropenia

INTRODUCTION

Febrile neutropenia (FEN) was reported in patients with solid malignancies at a rate of 5-10% and in patients with hematological malignancies at a rate of 20-25%. In our study, we aimed to investigate the effects of mannose-binding lectin 2 (MBL2) (rs1800450) and suppressor of cytokine signaling-1 (SOCS1) (rs33989964) gene variants on patients with FEN.

METHODS

A total of 123 patients who applied to pediatric emergency department between December 2019-12/2020 included in the study. Thirteen patients were excluded from the study due to the inability to obtain DNA. Demographic-clinical features at initial diagnosis and genotype distributions were recorded. The control group consisted of volunteers with the same ethnicity, age and gender, no active infection, and no consanguinity.

RESULTS

CA/CA genotype of SOCS1 was found to be significantly higher in the healthy control group (p = 0.028). AB/BB genotype of MBL2 was significantly higher in FEN patients with a MASCC score of high risk, AA genotype was found to be higher in patients with low risk (p = 0.001). While the rate of microbiologically documented infection (MDI) was significantly lower in patients with the AA genotype of MBL2, it was significantly higher in patients with AA/BB genotypes (p = 0.025). MDI rate in patients with the del/del genotype of SOCS1 was found to be significantly lower than in patients with CA/CA + CA/del genotypes (p = 0.026).

CONCLUSIONS

In this study, it was revealed that low expression-related MBL2 genotypes were riskier for FEN and also, gene variants associated with high SOCS1 transcription were both protective against FEN and increased the rate of culture-negativity.

Importance of mannose-binding lectin2 polymorphism (rs1800450) in infections in children

PURPOSE

Mannose-binding lectin (MBL) is a serine protease belonging to the collectins and an important factor in the inherited immune system. We aimed to reveal the distribution of different MBL2 genotypes in patients diagnosed with acute bronchiolitis and pneumonia.

MATERIAL AND METHODS

A total of 147 patients who applied to Paediatric Emergency between 01.12.2019 and 31.12.2020 were included in the study. Patients were divided into two subgroups: Bronchiolitis and pneumonia.

RESULTS

AA genotype was found to be significantly higher in healthy controls (p = 0.039). In the pneumonia group, both AB/BB genotype was significantly higher compared to healthy controls (p = 0.001). While the AA genotype was more common in patients with acute bronchiolitis, AB/BB genotypes were more common in the pneumonia group (p = 0.001). The presence of fever, crepitation, tachypnoea, pathological x-ray finding, and high leukocyte count are significantly more common in patients with AA genotype, while more than 3 days of follow-up duration and severe clinical picture were more common in patients with AB/BB genotypes (p < 0.05, for all).

CONCLUSIONS

Genotypes with low MBL expression were significantly more common in patients with pneumonia and severe infection. All these results reveal the importance of MBL polymorphisms and their expression in infections.

Investigation of MBL2 and NOS3 functional gene variants in suspected COVID-19 PCR (-) patients

For COVID-19 (Coronavirus Disease-2019) cases, detecting host-based factors that predispose to infection is a very important research area. In this study, the aim is to investigate the MBL2 and NOS3 gene polymorphisms in COVID-19 patients with lung involvement, whose first nasopharyngeal PCR results were negative. Seventy-nine patients diagnosed with COVID-19 between April-June 2020 who were admitted to a university hospital, and 100 healthy controls were included. In the first statistical analysis performed between PCR-positive, CT-negative and PCR-negative, CT-positive patients; the AB of MBL2 genotype was significantly higher in the first group (p = 0.049). The B allele was also significantly higher in the same subgroup (p = 0.001). The absence of the AB genotype was found to increase the risk of CT positivity by 6.9 times. The AB genotype of MBL2 was higher in healthy controls (p = 0.006). The absence of the AB genotype was found to increase the risk of CT positivity; also, it can be used for early detection and isolation of patients with typical lung involvement who had enough viral loads, but whose initial PCR results were negative.