Mannose-Binding Lectin: Biologic Characteristics and Role in the Susceptibility to Infections and Ischemia-Reperfusion Related Injury in Critically Ill Neonates

A case report of uterine necrosis following cesarean section: lessons learned from cross binding suture for refractory postpartum hemorrhage

Uterine necrosis following cesarean section is an extremely rare but serious complication. This case report presents a unique scenario where a cross binding suture technique was employed to manage intractable postpartum hemorrhage (PPH), ultimately leading to uterine necrosis and hysterectomy. The case underscores the challenges of managing severe PPH and highlights the potential complications of unconventional surgical techniques. It also emphasizes the importance of early recognition and intervention to minimize maternal morbidity and mortality.

Sickle Cell Anemia and Inflammation: A Review of Stones and Landmarks Paving the Road in the Last 25 Years

A quarter of a century ago, sickle cell disease (SCD) was mainly viewed as a typical genetic disease inherited as a classical Mendelian trait. Therefore, the main focus concerning SCD was on diagnosis, meaning, genotyping, and identification of homozygous and heterozygous individuals carrying the relevant HbS mutant allele. Nowadays, it is well established that sickle cell disease is indeed the result of homozygosis for the HbS variant, although this single feature is not capable of explaining the highly diverse clinical presentation of SCD. In fact, an important feature of SCD is the chronic inflammation that accompanies the sickling of erythrocytes. In this manuscript, we will revisit the early evidence of inflammation in SCD and review what was uncovered during the last 25 years. Here, we describe Sickle cell anemia as a major participant in the history of science. In fact, SCD was the first genetic disease where the causal mutation was identified and is also the first disease for which treatment through genome editing was approved, making this disease a landmark in the road of molecular biology.

Prognostic role of mesangial IgM deposition in IgA nephropathy: a long-term cohort study

BACKGROUND

The clinical significance of mesangial immunoglobulin (Ig) M deposition in IgA nephropathy (IgAN) has been less explored and remains a topic of debate. Therefore, our study aimed to investigate the prognostic value of mesangial IgM deposition in a long-term follow-up cohort of IgAN patients.

METHODS

A unicentric retrospective study was conducted on 93 consecutive IgAN patients (median age 41 years, 68% male, eGFR 48.7 mL/min, proteinuria 1.1 g/g) from 2010 to 2015. They were followed until end-stage kidney disease (ESKD), death, or until the end of the study in January 2021, with a median follow-up of 7 years. An independent pathologist evaluated the IgM immunofluorescence pattern, Oxford MEST-C score, and transmission electron microscopy (TEM) lesions following a comprehensive protocol.

RESULTS

In our cohort, 70% had mesangial IgM-positive deposits, while 30% were IgM-negative. Both groups were similar in age, sex, prevalence of arterial hypertension, Charlson comorbidity scores, kidney function (eGFR and proteinuria), pathology findings (Oxford MEST-C score, IgG and C3 immune deposition), and TEM analysis. Treatment with RASI and immunosuppression, and death rates were also comparable. However, 37% of IgM-positive patients progressed to ESKD, significantly higher than the 11% in the IgM-negative group. Univariate and multivariate Cox proportional hazards regression analyses identified lower eGFR, higher Oxford MEST-C score, and mesangial IgM deposits as independent factors associated with shorter kidney survival.

CONCLUSIONS

Our study highlights mesangial IgM deposition as a potential risk factor for ESKD in patients with advanced IgAN, laying a foundation for further research in this area.

Relationship between IgM deposition in the mesangial region and the prognosis of IgA nephropathy: a single-centre retrospective study

OBJECTIVE

The aim of this study was to investigate the prognostic value of mesangial IgM deposition in a long-term follow-up cohort of patients with immunoglobulin A nephropathy (IgAN).

METHODS

A retrospective analysis of clinicopathological data from 774 patients with primary IgAN at Hangzhou Hospital of Traditional Chinese Medicine between January 1, 2016, and December 31, 2018, was conducted. Patients were categorized into end-event and non-end-event groups according to whether they reached the renal composite endpoint, defined as a ≥ 50% decline in eGFR or progression to end-stage renal disease (ESRD). Risk factors for adverse renal outcomes were evaluated via univariate and multivariate Cox regression models. Patients were further divided into three groups on the basis of IgM deposition levels in the glomerular mesangial area: IgM-negative, low (IF < 2+), and high (IF ≥ 2+). Comparative analyses of clinical and histopathological characteristics, along with treatment regimens, were performed across these groups.

RESULTS

Compared with the IgM-negative and low-deposition groups, the high-IgM deposition group exhibited significantly lower serum albumin and eGFR levels and higher cholesterol, 24-hour urine protein, and blood immunoglobulin M levels. Multivariate Cox regression analysis identified immunosuppressant use as an independent protective factor for IgAN prognosis, whereas low serum albumin, T2 lesions, and nephropathological IgM deposits were recognized as independent risk factors for the 5-year prognosis of patients with IgAN. Kaplan‒Meier survival curves revealed that patients with high IgM deposition had markedly poorer prognoses than those with negative or low IgM deposition.

CONCLUSION

In addition to low serum albumin and T2 lesions, IgM deposition in the mesangial region has emerged as an independent risk factor for the 5-year prognosis of patients with IgAN.

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

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.

A novel peptide derived from the mannose binding lectin inhibits LPS-activated TLR4/NF-κB signaling and suppresses ocular inflammation

Uveitis is a major cause of vision impairment worldwide. Current treatments have limited effectiveness but severe complications. Mannose binding lectin (MBL) is an important protein of the innate immune system that binds to TLR4 and suppresses LPS-induced inflammatory cytokine secretion. MBL-mediated inhibition of inflammation via the TLR4 pathway and MBL-derived peptides might be a potential therapeutics. In this study, we designed a novel MBL-derived peptide, WP-17, targeting TLR4. Bioinformatics analysis was conducted for the sequence, structure and biological properties of WP-17. The binding of WP-17 to THP-1 cells was analyzed using flow cytometry. Signaling molecules were analyzed by western blotting, and activation of NF-κB was measured by immunofluorescence-histochemical analysis. Effects of WP-17 were studied in vitro using LPS-stimulated THP-1 cells and in vivo in endotoxin-induced uveitis (EIU). Our results showed that WP-17 could bind to TLR4 expressed on macrophages, thus downregulating the expression levels of MyD88, IRAK-4, and TRAF-6, and inhibiting the downstream NF-kB signaling pathway and LPS-induced expression of TNF-α and IL-6 in THP-1 cells. Moreover, in EIU rats, intravitreal pretreatment with WP-17 demonstrated significant inhibitory effects on ocular inflammation, attenuating the clinical and histopathological manifestations of uveitis, reducing protein leakage and cell infiltration into the aqueous humor, and suppressing TNF-α and IL-6 production in ocular tissues. In summary, our study provides the first evidence of a novel MBL-derived peptide that suppressed activation of the NF-кB pathway by targeting TLR4. The peptide effectively inhibited rat uveitis and may be a promising candidate for the management of ocular inflammatory diseases.

Mannose: a potential saccharide candidate in disease management

There are a plethora of antibiotic resistance cases and humans are marching towards another big survival test of evolution along with drastic climate change and infectious diseases. Ever since the first antibiotic [penicillin], and the myriad of vaccines, we were privileged to escape many infectious disease threats. The survival technique of pathogens seems rapidly changing and sometimes mimicking our own systems in such a perfect manner that we are left unarmed against them. Apart from searching for natural alternatives, repurposing existing drugs more effectively is becoming a familiar approach to new therapeutic opportunities. The ingenious use of revolutionary artificial intelligence-enabled drug discovery techniques is coping with the speed of such alterations. D-Mannose is a great hope as a nutraceutical in drug discovery, against CDG, diabetes, obesity, lung disease, and autoimmune diseases and recent findings of anti-tumor activity make it interesting along with its role in drug delivery enhancing techniques. A very unique work done in the present investigation is the collection of data from the ChEMBL database and presenting the targetable proteins on pathogens as well as on humans. It shows Mannose has 50 targets and the majority of them are on human beings. The structure and conformation of certain monosaccharides have a decisive role in receptor pathogen interactions and here we attempt to review the multifaceted roles of Mannose sugar, its targets associated with different diseases, as a natural molecule having many success stories as a drug and future hope for disease management.

Graphical abstract

Mannose-based surfactant as biofunctional nanoemulsion stabilizer

The development and implementation of new amphiphiles based on natural resources rather than petrochemical precursors is an essential requirement due to their feedstock depletion and adverse environmental impacts. In addition, the use of bio-based surfactants can provide unique characteristics and improve the properties and versatility of the colloidal systems in which they are applied, such as emulsions. Here, the emulsification properties of a synthesized biocompatible mannose-based surfactant were investigated. Its behavior was evaluated in the presence of four different natural oils (castor, sunflower, olive and soybean) as well as two different aqueous phases (pure water and phosphate-buffered saline). The results highlighted its interest as surfactant in O/W nanoemulsions for all tested oil and aqueous phases, using a low-energy preparation protocol and relatively low surfactant concentrations. Furthermore, the mannose groups present on the polar head of the surfactant and adsorbed on the surface of the emulsion droplets were shown to retain their native biological properties. The specific mannose-concanavalin A binding was observed in vitro by the designed nanoemulsions, revealing the biorecognition properties of the surfactant and its potential applicability as a nanocarrier.

Tinker, tailor, soldier, cell: the role of C-type lectins in the defense and promotion of disease

C-type lectins (CTLs) represent a large family of soluble and membrane-bound proteins which bind calcium dependently via carbohydrate recognition domains (CRDs) to glycan residues presented on the surface of a variety of pathogens. The deconvolution of a cell's glycan code by CTLs underpins several important physiological processes in mammals such as pathogen neutralization and opsonization, leukocyte trafficking, and the inflammatory response. However, as our knowledge of CTLs has developed it has become apparent that the role of this innate immune family of proteins can be double-edged, where some pathogens have developed approaches to subvert and exploit CTL interactions to promote infection and sustain the pathological state. Equally, CTL interactions with host glycoproteins can contribute to inflammatory diseases such as arthritis and cancer whereby, in certain contexts, they exacerbate inflammation and drive malignant progression. This review discusses the 'dual agent' roles of some of the major mammalian CTLs in both resolving and promoting infection, inflammation and inflammatory disease and highlights opportunities and emerging approaches for their therapeutic modulation.

The role of MBL, PCT, CRP, neutrophil-lymphocyte ratio, and platelet lymphocyte ratio in differentiating infections from flares in lupus

BACKGROUND

The distinction between infection and flare in systemic lupus erythematosus (SLE) has always been a dilemma for clinicians as the clinical and biochemical profiles overlap. The present study evaluated affordable biomarkers to distinguish infection from flare in an SLE cohort in a tertiary care center in eastern India.

METHODS

One hundred and fifty-two SLE patients were clinically evaluated and enrolled in the present study. Hematological, immunological, and biochemical profiles and various biomarkers such as C reactive protein (CRP), procalcitonin (PCT), and Mannose-binding lectin (MBL) were quantified.

RESULTS

One hundred and fifty-two patients (152) were enrolled in the present study and all had SLEDAI scores of more than 4. From which 70 had infection, and the common infections were urinary tract infection (34.28%) followed by pneumonia (27.14%). Neutrophil-lymphocyte ratio (NLR) and C-reactive protein (CRP) were significantly elevated in SLE with infections (NLR: 5.84 ± 2.47; CRP: 30.56 ± 41.63) than those with flare (NLR: 3.87 ± 2.62; CRP: 8.73 ± 9.53). The receiver operating characteristic curve (ROC) analysis revealed CRP, PLR, and NLR as important markers for predicting infections (CRP: AUC = 0.682, p = 0.0001; PLR: AUC = 0.668, p = 0.0008; NLR: AUC = 0.742, p < 0.0001). The MBL and PCT levels were comparable among SLE flare and those with infections.

CONCLUSIONS

NLR and CRP levels are affordable biomarkers to distinguish infections from flares in SLE. MBL and PCT could not differentiate flare from an infection. Key Points • Biomarkers for the differentiation of infection and flare in SLE are limited. • NLR, PLR, and CRP are promising biomarkers to enable differentiation. • PCT and MBL are not ideal biomarkers to differentiate infection from flare.

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.

Host-Pathogen Adhesion as the Basis of Innovative Diagnostics for Emerging Pathogens

Infectious diseases are an existential health threat, potentiated by emerging and re-emerging viruses and increasing bacterial antibiotic resistance. Targeted treatment of infectious diseases requires precision diagnostics, especially in cases where broad-range therapeutics such as antibiotics fail. There is thus an increasing need for new approaches to develop sensitive and specific in vitro diagnostic (IVD) tests. Basic science and translational research are needed to identify key microbial molecules as diagnostic targets, to identify relevant host counterparts, and to use this knowledge in developing or improving IVD. In this regard, an overlooked feature is the capacity of pathogens to adhere specifically to host cells and tissues. The molecular entities relevant for pathogen–surface interaction are the so-called adhesins. Adhesins vary from protein compounds to (poly-)saccharides or lipid structures that interact with eukaryotic host cell matrix molecules and receptors. Such interactions co-define the specificity and sensitivity of a diagnostic test. Currently, adhesin-receptor binding is typically used in the pre-analytical phase of IVD tests, focusing on pathogen enrichment. Further exploration of adhesin–ligand interaction, supported by present high-throughput “omics” technologies, might stimulate a new generation of broadly applicable pathogen detection and characterization tools. This review describes recent results of novel structure-defining technologies allowing for detailed molecular analysis of adhesins, their receptors and complexes. Since the host ligands evolve slowly, the corresponding adhesin interaction is under selective pressure to maintain a constant receptor binding domain. IVD should exploit such conserved binding sites and, in particular, use the human ligand to enrich the pathogen. We provide an inventory of methods based on adhesion factors and pathogen attachment mechanisms, which can also be of relevance to currently emerging pathogens, including SARS-CoV-2, the causative agent of COVID-19.

Prenatal Immunity and Influences on Necrotizing Enterocolitis and Associated Neonatal Disorders

Prior to birth, the neonate has limited exposure to pathogens. The transition from the intra-uterine to the postnatal environment initiates a series of complex interactions between the newborn host and a variety of potential pathogens that persist over the first few weeks of life. This transition is particularly complex in the case of the premature and very low birth weight infant, who may be susceptible to many disorders as a result of an immature and underdeveloped immune system. Chief amongst these disorders is necrotizing enterocolitis (NEC), an acute inflammatory disorder that leads to necrosis of the intestine, and which can affect multiple systems and have the potential to result in long term effects if the infant is to survive. Here, we examine what is known about the interplay of the immune system with the maternal uterine environment, microbes, nutritional and other factors in the pathogenesis of neonatal pathologies such as NEC, while also taking into consideration the effects on the long-term health of affected children.

Effect of mannose-binding lectin gene polymorphisms on the risk of rheumatoid arthritis: Evidence from a meta-analysis

BACKGROUND

The effect of mannose-binding lectin (MBL) gene polymorphisms on susceptibility of rheumatoid arthritis (RA) were evaluated in ethnically different populations, whereas the results were always inconsistent.

MATERIALS AND METHODS

Fourteen articles involving 36 datasets were recruited to evaluate the association between MBL gene polymorphisms and rheumatoid arthritis in a meta-analysis. The random or fixed effect models were used to evaluate the pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs).

RESULTS

Stratified analysis by ethnicities was conducted and the result revealed that rs1800450 (T vs C, OR = 1.32, 95% CI: 1.04-1.67, P < .05) and MBL-A/O (T vs C, OR = 1.20, 95% CI: 1.08-1.34, P < .001) were strongly associated with RA in Brazilian populations. In addition, the significant relationship between rs11003125 (T vs C, OR = 1.16, 95% CI: 1.06-1.26, P < .05) with RA were also observed in East Asian populations. Meanwhile, the inverse associations between rs5030737 with RA in East Asians and rs1800450 with RA in Indians were acquired. However, no association between any MBL polymorphism with RA susceptibility was confirmed in Caucasians.

CONCLUSIONS

The structural polymorphisms in exon 1 of MBL gene may significantly contribute to susceptibility and development of RA in Brazilian and Indian populations, whereas the functional polymorphisms in the promoter region were more likely to associate with RA in East Asians.

Kinetics of activation marker expression after in vitro polyclonal stimulation of chicken peripheral T cells

A comprehensive analysis of T cell activation markers in chicken is lacking. Kinetics of T cell activation markers (CD25, CD28, CD5, MHC-II, CD44, and CD45) in response to in vitro stimulation of peripheral blood mononuclear cells with concanavalin A (Con A) were evaluated between two chicken lines selected for high and low levels of mannose-binding lectin in serum (L10H and L10L, respectively) by flow cytometry. L10H chickens showed a stronger response to Con A based on the frequency of T cell blasts in both the CD4⁺ and CD8⁺ compartment. The majority of the proliferating CD4⁺ and CD8⁺ T cells expressed CD25. Proliferating T cells were seen both in the CD4⁺  MHC-II^+/- and CD8⁺  MHC-II^+/- population. For both CD4⁺ and CD8⁺ T cells, frequencies of CD25⁺ and MHC-II⁺ T cells were increased 24 h after stimulation. CD28⁺ frequencies were only increased on CD8⁺ T cells 48 h after stimulation. An increase in the relative surface expression based on mean fluorescence intensity (MFI) upon activation was observed for most markers except CD5. For CD4⁺ T cells, CD28 expression increased 24 h after stimulation whereas MHC-II expression increased after 48 h. For CD8⁺ T cells, a tendency toward an increase in CD25 expression was observed. CD28 expression started to increase 24 h after stimulation and only a transient peak in MHC-II expression on CD8⁺ T cells was observed after 24 h. CD44 and CD45 expressed on CD4⁺ and CD8⁺ T cells increased 24-72 h after stimulation. In summary, the frequency of CD25⁺ and MHC-II⁺ T cells were shown to be early markers (24 h) for in vitro activation of both CD4⁺ and CD8⁺ T cells. Frequency of CD28⁺ T cells was a later marker (48 h) and only for CD8⁺ T cells. Surface expression of all markers (MFI) increased permanently or transiently upon activation except for CD5.

Deep Gene Sequence Cluster Analyses of Multi-Virus-Infected Mucosal Tissue Reveal Enhanced Transmission of Acute HIV-1

During heterosexual HIV-1 transmission, a genetic bottleneck occurs in the newly infected individual as the virus passes from the mucosa, leading to systemic infection with a single transmitted HIV-1 clone in the recipient. This bottleneck in the recipient has just been described, and the mechanisms involved in this selection process have not been elucidated.

Exposure of the genital mucosa to a genetically diverse viral swarm from the donor HIV-1 can result in breakthrough and systemic infection by a single transmitted/founder (TF) virus in the recipient. The highly diverse HIV-1 envelope (Env) in this inoculating viral swarm may have a critical role in transmission and subsequent immune response. Thus, chronic (Env_chronic) and acute (Env_acute) Env chimeric HIV-1 were tested using multivirus competition assays in human mucosal penile and cervical tissues. Viral competition analysis revealed that Env_chronic viruses resided and replicated mainly in the tissue, while Env_acute viruses penetrated the human tissue and established infection of CD4⁺ T cells more efficiently. Analysis of the replication fitness, as tested in peripheral blood mononuclear cells (PBMCs), showed similar replication fitness of Env_acute and Env_chronic viruses, which did not correlate with transmission fitness in penile tissue. Further, we observed that chimeric Env viruses with higher replication in genital mucosal tissue (chronic Env viruses) had higher binding affinity to C-type lectins. Data presented herein suggest that the inoculating HIV-1 may be sequestered in the genital mucosal tissue (represented by chronic Env HIV-1) but that a single HIV-1 clone (e.g., acute Env HIV-1) can escape this trapped replication for systemic infection.

IMPORTANCE During heterosexual HIV-1 transmission, a genetic bottleneck occurs in the newly infected individual as the virus passes from the mucosa, leading to systemic infection with a single transmitted HIV-1 clone in the recipient. This bottleneck in the recipient has just been described (K. Klein et al., PLoS Pathog 14:e1006754, https://doi.org/10.1371/journal.ppat.1006754), and the mechanisms involved in this selection process have not been elucidated. However, understanding mucosal restriction is of the utmost importance for understanding dynamics of infections and for designing focused vaccines. Using our human penile and cervical mucosal tissue models for mixed HIV infections, we provide evidence that HIV-1 from acute/early infection, compared to that from chronic infection, can more efficiently traverse the mucosal epithelium and be transmitted to T cells, suggesting higher transmission fitness. This study focused on the role of the HIV-1 envelope in transmission and provides strong evidence that HIV transmission may involve breaking the mucosal lectin trap.

Lectin Protein as a Promising Component to Functionalize Micelles, Liposomes and Lipid NPs against Coronavirus

The outbreak of a novel strain coronavirus as the causative agent of COVID-19 pneumonia, first identified in Wuhan, China in December 2019, has resulted in considerable focus on virulence abilities of coronavirus. Lectins are natural proteins with the ability to bind specific carbohydrates related to various microorganisms, including viruses, bacteria, fungi and parasites. Lectins have the ability to agglutinate and neutralize these pathogeneses. The delivery of the encapsulated antiviral agents or vaccines across the cell membrane can be possible by functionalized micellar and liposomal formulations. In this mini-review, recent advances and challenges related to important lectins with inhibition activities against coronaviruses are presented to obtain a novel viewpoint of microformulations or nanoformulations by micellar and liposomal cell-binding carriers.

Mannose-Binding Lectin Levels in Late-Onset Sepsis in Preterm Infants: Results from a Prospective Study in a Tertiary Care Center

Introduction: This study aimed to determine the association between serum mannose-binding lectin (MBL) levels, gene polymorphisms and late-onset sepsis (LOS) in preterm infants. Methods: Infants with <37 gestational weeks were categorized into two groups according to the presence of LOS during their hospitalization. An MBL level <700 ng/ml was defined as deficiency, <400 ng/ml as severe deficiency. Codon 54 and 57 polymorphisms of MBL2 gene were analyzed. Results: Overall, 153 preterm infants were included. MBL deficiency was found to be more common in the LOS group (p = 0.02). The rate of Gram-negative sepsis was higher in MBL2 variant-type (p = 0.01). In the logistic regression analysis, MBL levels <700 ng/ml were found to have a significant effect on LOS development (odds ratio: 2.692, 95% confidence interval 1.196-5.8, p = 0.02). Conclusions: MBL deficiency is an important risk factor for the development of LOS. Furthermore, there is an association between MBL2 gene polymorphism and Gram-negative sepsis.

Association of MBL2 Exon 1 Polymorphisms With Multibacillary Leprosy

Mannose-binding lectin (MBL) is a serum protein of innate immunity, with a central role in the activation of the complement system through the lectin pathway. This protein is encoded by MBL2 gene, and single-nucleotide polymorphisms located at exon 1, such as rs5030737 C>T (D variant), rs1800450 G>A (B variant), and rs1800451 G>A (C variant), may change the MBL structure and the serum concentration. MBL2 polymorphisms have been associated with several infectious diseases, including leprosy. Host immune response has a major impact on the clinical manifestation of leprosy since only a few individuals infected with Mycobacterium leprae will develop the disease. Therefore, the aim of this study was to evaluate the influence of MBL2 exon 1 polymorphisms (rs5030737, rs1800450, and rs1800451) on the MBL levels and leprosy immunopathogenesis. This case–control study included 350 leprosy patients from Southern Brazil, with 279 classified as multibacillary (MB) and 71 as paucibacillary (PB). The control group consisted of 350 non-consanguineous individuals, who were not diagnosed with leprosy or other infectious and autoimmune diseases. Genotyping was performed by PCR–sequence specific primers, and the MBL serum concentrations were evaluated by ELISA. MBL2 exon 1 polymorphisms were analyzed individually and grouped as genotypes, considering “A” as the wild allele and “O” as the presence of at least one polymorphism (D, B, or C variants). Differences were not observed in the distribution of genotypic and allelic frequencies between leprosy per se patients and controls. However, in a haplotypic analysis, the TGG haplotype presented a risk for development of leprosy per se in women when compared to the wild haplotype (CGG) (OR = 2.69). Comparing patients with MB and PB, in a multivariate analysis, the B variant was associated with the susceptibility of developing the MB form of leprosy (OR = 2.55). Besides that, the CAG haplotype showed an increased susceptibility to develop MB leprosy in women compared to men. It was observed that the A/O genotype in women was associated with a susceptibility to leprosy development per se (OR = 1.66) and progression to MB leprosy (OR = 3.13). In addition, the MBL serum concentrations were in accordance with the genotyping analysis. In summary, our data suggest that MBL2 exon 1 polymorphisms are associated with an increased risk to leprosy development and progression.

Serum mannose-binding lectin (MBL) concentrations are reduced in non-pregnant women with previous adverse pregnancy outcomes

Mannose-binding lectin (MBL) is an important component of the innate immunity, and it is responsible not only for opsonization of micro-organisms, but also for efferocytosis. The aim of this study was to investigate whether MBL concentrations and lectin complement pathway activity are altered in non-pregnant women with previous adverse pregnancy outcomes. Patients were divided into four groups on the basis of their history of pregnancy complications, including control patients who had uncomplicated pregnancies and term deliveries (control, n = 33), and three groups of patients with a history of pregnancy complications, including preterm labour (n = 29), recurrent miscarriage (n = 19) or unexplained intrauterine foetal death (IUFD; n = 17). All women enrolled in the study had an interval of three to six months following their previous pregnancy, and they agreed to have a blood sample taken. We found significantly higher MBL concentrations and functional activity of the lectin complement pathway in healthy controls who had previous uneventful term pregnancies (1341 ng/mL; activity 100% (IQR: 62%-100%)), compared to women with the history of IUFD (684 ng/mL, P = .008; activity 8.5% (IQR: 0%-97.8%), P = .011), recurrent miscarriage (524 ng/mL, P = .022; activity 44% (IQR: 4%-83%), P = .011) or preterm labour (799 ng/mL, P = .022; activity 62.5% (IQR: 0%-83%), P = .003). Our results suggest that inadequate function of the complement lectin pathway is associated with a higher risk of preterm labour, recurrent miscarriage and unexplained intrauterine foetal death.

Revisiting the complement system in systemic lupus erythematosus

Introduction: Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease, characterized by the production of autoantibodies. Numerous mechanisms contribute to the pathogenesis and autoimmunity in SLE. One of the most important mechanisms is the defective function of the early complement components that are involved in clearing the immune-complexes and apoptotic debris. Major evidence supporting this hypothesis is the development of severe lupus in individuals with monogenic defects in any one of the early complement components such as C1q, C1 s, C1 r, C2, or C4.Areas covered: In this review, we discuss hereditary defects in classical complement components and their clinical manifestations, acquired defects of complements in lupus, the role of complements in the pathogenesis of antiphospholipid antibody syndrome and lupus nephritis, and laboratory assessment of complement components and their functions. Articles from the last 20 years were retrieved from PubMed for this purpose.Expert opinion: Complements have a dual role in the pathogenesis of SLE. On one hand, deficiency of complement components predisposes to lupus, while, on the other, excess complement activation plays a role in the organ damage. Understanding the intricacies of the role of complements in SLE can pave way for the development of targeted therapies.

Mechanisms of Pathogenic Candida Species to Evade the Host Complement Attack

Candida species are common colonizers of the human skin, vagina, and the gut. As human commensals, Candida species do not cause any notable damage in healthy individuals; however, in certain conditions they can initiate a wide range of diseases such as chronic disseminated candidiasis, endocarditis, vaginitis, meningitis, and endophthalmitis. The incidence of Candida caused infections has increased worldwide, with mortality rates exceeding 70% in certain patient populations. C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei are responsible for more than 90% of Candida-related infections. Interestingly, the host immune response against these closely related fungi varies. As part of the innate immune system, complement proteins play a crucial role in host defense, protecting the host by lysing pathogens or by increasing their phagocytosis by phagocytes through opsonization. This review summarizes interactions of host complement proteins with pathogenic Candida species, including C. albicans and non-albicans Candida species such as C. parapsilosis. We will also highlight the various ways of complement activation, describe the antifungal effects of complement cascades and explore the mechanisms adopted by members of pathogenic Candida species for evading complement attack.

Mannan-Binding Lectin Regulates Inflammatory Cytokine Production, Proliferation, and Cytotoxicity of Human Peripheral Natural Killer Cells

Natural killer (NK) cells represent the founding members of innate lymphoid cells (ILC) and play critical roles in inflammation and the immune response. NK cell effector functions are regulated and fine-tuned by various immune modulators. Mannan (or mannose)-binding lectin (MBL), a soluble C-type lectin, is traditionally recognized as an initiator of the complement pathway. Recently, it is also considered as an immunomodulator by its interaction with kinds of immune cells. However, the effect of MBL on NK cell function remains unexplored. In this study, we found that human plasma MBL could interact directly with peripheral NK cells partially via its collagen-like region (CLR). This MBL binding markedly suppressed the interleukin-2- (IL-2-) induced inflammatory cytokine tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) production but increased the IL-10 production in NK cells. In addition, the expression of activation surface markers such as CD25 and CD69 declined after MBL treatment. Also, MBL impaired the proliferation and lymphokine-activated killing (LAK) of NK cells. Moreover, we demonstrated that MBL inhibited IL-2-induced signal transducers and activators of transcription 5 (STAT5) activation in NK cells. In conclusion, we have uncovered a far unknown regulatory role of MBL on NK cells, a new clue that could be important in the immunomodulatory networks of immune responses.

The Role of Complement in Transfusion-Related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) is a life-threatening complication of acute respiratory distress occurring within 6 hours of blood transfusion. TRALI is one of the leading causes of transfusion-related fatalities and specific therapies are unavailable. Neutrophils are recognized as the major pathogenic cells, whereas T regulatory cells and dendritic cells appear to be important for protection against TRALI. The pathogenesis, however, is complex and incompletely understood. It is frequently postulated that the complement system plays an important role in the TRALI pathogenesis. In this article, we assess the evidence regarding the involvement of complement in TRALI from both human and animal studies. We hypothesize about the potential connection between the complement system and neutrophils in TRALI. Additionally, we draw parallels between TRALI and other acute pulmonary disorders of acute lung injury and acute respiratory distress syndrome regarding the involvement of complement. We conclude that, even though a role for complement in the TRALI pathogenesis seems plausible, studies investigating the role of complement in TRALI are remarkably limited in number and also present conflicting findings. Different types of TRALI animal models, diverse experimental conditions, and the composition of the gastrointestinal microbiota may perhaps all be factors which contribute to these discrepancies. More systematic studies are warranted to shed light on the contribution of the complement cascade in TRALI. The underlying clinical condition of the patient, which influences the susceptibility to TRALI, as well as the transfusion factor (antibody-mediated vs non–antibody-mediated), will be important to take into consideration when researching the contribution of complement. This should significantly increase our understanding of the role of complement in TRALI and may potentially result in promising new treatment strategies.

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Studies investigating complement and TRALI are limited in number and present conflicting findings.

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Systematic investigation is needed to better understand the contribution of the complement cascade in TRALI.

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Future studies in this area should consider both the clinical susceptibility of the patient as well as the effect of transfusion factors.

Exploitation of glycosylation in enveloped virus pathobiology

Glycosylation is a ubiquitous post-translational modification responsible for a multitude of crucial biological roles. As obligate parasites, viruses exploit host-cell machinery to glycosylate their own proteins during replication. Viral envelope proteins from a variety of human pathogens including HIV-1, influenza virus, Lassa virus, SARS, Zika virus, dengue virus, and Ebola virus have evolved to be extensively glycosylated. These host-cell derived glycans facilitate diverse structural and functional roles during the viral life-cycle, ranging from immune evasion by glycan shielding to enhancement of immune cell infection. In this review, we highlight the imperative and auxiliary roles glycans play, and how specific oligosaccharide structures facilitate these functions during viral pathogenesis. We discuss the growing efforts to exploit viral glycobiology in the development of anti-viral vaccines and therapies.

Association between -221 X/Y polymorphism of mannose-binding lectin (MBL) gene and susceptibility to HTLV-1 infection among people from an endemic region in the Northeast of Iran

BACKGROUND

The role of (MBL) gene single nucleotide polymorphisms (SNPs) has been well documented in susceptibility to several infectious diseases. This study aimed to investigate the association between two MBL promoter variants, -550 H/L and -221 X/Y, and susceptibility to HTLV-1 infection.

METHODS

A total of 153 subjects infected with HTLV-1 and 169 healthy controls were recruited. SSP-PCR method was applied to genotype -550 H/L and -221 X/Y polymorphisms. Associations between genotypes or alleles and susceptibility to HTLV-1 infection were analyzed by Pearson's Chi-Square. p ≤ .05 was considered statistically significant.

RESULTS

Statistical analysis revealed significant differences between the two groups in the -221 position (χ2 = 19.709; p = .000). The MBL YX genotype was significantly associated with increased susceptibility to HTLV-1 (OR = 2.73, %95 CI = 1.74-4.30). Combined genotype of the two loci showed that the HYHX genotype (OR = 2.20, 95% CI = 1.95-2.48) and LYLX (OR = 1.97, 95% CI = 1.13-3.45) were associated with an increased risk of HTLV-1 infection.

CONCLUSION

Our results represent the importance of -221 X > Y variants in acquisition of HTLV-1 as this is the case for several other viral and bacterial infections.

Mannan-binding lectin promotes keratinocyte to produce CXCL1 and enhances neutrophil infiltration at the early stages of psoriasis

Psoriasis is a chronic, relapsing inflammatory skin disorder. Numerous experimental evidence and therapeutic evidence have shown that the innate immune response is critical for the pathogenesis and development of psoriasis. Mannan-binding lectin (MBL), a prototypic pattern recognition molecule of the innate immune system, plays an essential role in the host defense against certain infections and also appears to be a major regulator of inflammation. In this study, we investigated the function of MBL on the course of experimental murine imiquimod (IMQ)-induced psoriasis. Our data showed that MBL-deficient (MBL^-/- ) mice exhibited attenuated skin damage characterized by greatly decreased erythema compared with wild-type control mice during the early stages of IMQ-induced psoriasis-like skin inflammation. The reduced skin inflammation in MBL^-/- mice was associated with the decreased infiltration of neutrophils. Furthermore, we have determined that MBL deficiency limited the chemokine CXCL1 production from skin keratinocytes upon IMQ stimulation, which might be responsible for the impaired skin recruitment of neutrophils. Additionally, we have provided the data that MBL protein promotes the IMQ-induced expression of CXCL1 and activation of MAPK/NF-κB signalling pathway in human keratinocyte HaCaT cells in vitro. In summary, our study revealed an unexpected role of MBL on keratinocyte function in skin, thus offering a new insight into the pathogenic mechanisms of psoriasis.

Exploring lectin-like activity of the S-layer protein of Lactobacillus acidophilus ATCC 4356

The surface layer (S-layer) protein of Lactobacillus acidophilus is a crystalline array of self-assembling, proteinaceous subunits non-covalently bound to the outmost bacterial cell wall envelope and is involved in the adherence of bacteria to host cells. We have previously described that the S-layer protein of L. acidophilus possesses anti-viral and anti-bacterial properties. In this work, we extracted and purified S-layer proteins from L. acidophilus ATCC 4356 cells to study their interaction with cell wall components from prokaryotic (i.e., peptidoglycan and lipoteichoic acids) and eukaryotic origin (i.e., mucin and chitin), as well as with viruses, bacteria, yeast, and blood cells. Using chimeric S-layer fused to green fluorescent protein (GFP) from different parts of the protein, we analyzed their binding capacity. Our results show that the C-terminal part of the S-layer protein presents lectin-like activity, interacting with different glycoepitopes. We further demonstrate that lipoteichoic acid (LTA) serves as an anchor for the S-layer protein. Finally, a structure for the C-terminal part of S-layer and possible binding sites were predicted by a homology-based model.

Mannose-binding lectin concentrations in people living with HIV/AIDS infected by HHV-8

Background

Mannose-binding lectin (MBL) plays an important role in the innate immune response by activating the complement system via the lectin pathway, and it has been studied in several viral infections; however, the influence of MBL in PLWHA infected with HHV-8 is unknown. The objective of this study was to verify the association of MBL deficient plasma concentrations in HIV/HHV-8 coinfected and HIV monoinfected patients and to correlate these concentrations with HIV viral load and CD4 counts in both groups.

Results

This was an analytical study of case-controls consisting of PLWHA monitored at the medical outpatient of Infectious and Parasitic Diseases of the clinical hospital in the Federal University of Pernambuco. Plasma concentrations of MBL were obtained by an enzyme-linked immunosorbent assay (ELISA) using a commercial Human Mannose Binding Lectin kit (MyBioSource, Inc.) that was performed according to the manufacturer’s guidelines, with values < 100 ng/ml considered deficient. A total of 245 PLWHA samples were analysed; 118 were HIV/HHV-8 coinfected and 127 were HIV monoinfected; 5.1% (6/118) of the coinfected patients and 3.2% (4/127) of the monoinfected patients (p = 0.445) were considered plasma concentration deficient. The median of the plasma concentrations of MBL in the coinfected patients was 2803 log₁₀ ng/ml and was 2.959 log₁₀ ng/ml in the monoinfected patients (p = 0.001). There was an inverse correlation between the plasma concentrations of MBL and the HIV viral load in both groups, but no correlation with the CD4 count.

Conclusions

Although the plasma concentrations considered deficient in MBL were not associated with HHV-8 infection in PLWHA, the coinfected patients showed lower MBL concentrations and an inverse correlation with HIV viral load, suggesting that there may be consumption and reduction of MBL due to opsonization of HIV and HHV-8, leading to the reduction of plasma MBL and non-accumulation in the circulation.

Pathophysiology of environmental enteric dysfunction and its impact on oral vaccine efficacy

Environmental enteric dysfunction (EED) refers to a subclinical disorder of intestinal function common in tropical countries and in settings of poverty and economic disadvantage. The enteropathy that underlies this syndrome is characterized by mucosal inflammation and villus blunting mediated by T cell activation. Epithelial cell disruption and microbial translocation drive systemic inflammation. EED in young children is associated geographically with growth failure, malnutrition, and greatly impaired responses to oral vaccines, notably rotavirus and poliovirus vaccines. In this review, we describe the pathophysiology of EED and examine the evidence linking EED and oral vaccine failure. This evidence is far from conclusive. Although our understanding of EED is still sketchy, there is limited evidence of disturbed innate immunity, B cell disturbances including aggregation into lymphoid follicles, and autoantibody generation. Pathways of T cell activation and the possibility of dendritic cell anergy, which could help explain oral vaccine failure, require further work.

Antimicrobial peptide LL-37 and recombinant human mannose-binding lectin express distinct age- and pathogen-specific antimicrobial activity in human newborn cord blood in vitro

Background: There is a need to prevent and treat infection in newborns. One approach is administration of antimicrobial proteins and peptides (APPs) such as LL-37, a membrane-active cathelicidin antimicrobial peptide, and mannose-binding lectin (MBL), a pattern-recognition protein that binds to microbial surface polysaccharides resulting in opsonization and complement activation. Low plasma/serum levels of LL-37 and of MBL have been correlated with infection and exogenous administration of these agents may enhance host defense. Methods: The antimicrobial activity of LL-37 (15 µg/ml) or rMBL (0.5, 2 and 10 µg/ml) was tested in hirudin-anticoagulated preterm and term human cord blood (N = 12-14) against Staphylococcus aureus (SA) USA 300 (2x10 4 CFU/ml), Staphylococcus epidermis (SE) 1457 (2x10 4 CFU/ml) and Candida albicans (CA) SC5314 (1x10 4 CFU/ml). After incubation (1, 45, or 180 min), CFUs were enumerated by plating blood onto agar plates. Supernatants were collected for measurement of MBL via ELISA. Results: Preterm cord blood demonstrated impaired endogenous killing capacity against SA and SE compared to term blood. Addition of LL-37 strongly enhanced antimicrobial/antifungal activity vs SA, SE and CA in term blood and SE and CA in preterm blood. By contrast, rMBL showed modest fungistatic activity vs CA in a sub-analysis of term newborns with high basal MBL levels. Baseline MBL levels varied within preterm and term cohorts with no correlation to gestational age. In summary, exogenous LL-37 demonstrated significant antimicrobial activity against SA, SE and CA in term and SE and CA in preterm human blood tested in vitro. rMBL demonstrated modest antifungal activity in term cord blood of individuals with high baseline MBL levels. Conclusions: To the extent that our in vitro results predict the effects of APPs in vivo, development of APPs for prevention and treatment of infection should take into account host age as well as the target pathogen.

Microglial Lectins in Health and Neurological Diseases

Microglia are the innate sentinels of the central nervous system (CNS) and are responsible for the homeostasis and immune defense of the CNS. Under the influence of the local environment and cell-cell interaction, microglia exhibit a multidimensional and context-dependent phenotypes that can be cytotoxic and neuroprotective. Recent studies suggest that microglia express multitudinous types of lectins, including galectins, Siglecs, mannose-binding lectins (MBLs) and other glycan binding proteins. Because most studies that examine lectins focus on the peripheral system, the functions of lectins have not been critically investigated in the CNS. In addition, the types of brain cells that contribute to the altered levels of lectins present in diseases are often unclear. In this review, we will discuss how galectins, Siglecs, selectins and MBLs contribute to the dynamic functions of microglia. The interacting ligands of these lectins are complex glycoconjugates, which consist of glycoproteins and glycolipids that are expressed on microglia or surrounding cells. The current understanding of the heterogeneity and functions of glycans in the brain is limited. Galectins are a group of pleotropic proteins that recognize both β-galactoside-containing glycans and non- β-galactoside-containing proteins. The function and regulation of galectins have been implicated in immunomodulation, neuroinflammation, apoptosis, phagocytosis and oxidative bursts. Most Siglecs are expressed at a low level on the plasma membrane and bind to sialic acid residues for immunosurveillance and cell-cell communication. Siglecs are classified based on their inhibitory and activatory downstream signaling properties. Inhibitory Siglecs negatively regulate microglia activation upon recognizing the intact sialic acid patterns and vice versa. MBLs are expressed upon infection in cytoplasm and can be secreted in order to recognize molecules containing terminal mannose as an innate immune defense machinery. Most importantly, multiple studies have reported dysregulation of lectins in neurological disorders. Here, we reviewed recent studies on microglial lectins and their functions in CNS health and disease, and suggest that these lectin families are novel, potent therapeutic targets for neurological diseases.