Mannose Binding Research Articles

Conformational ensembles in Klebsiella pneumoniae FimH impact uropathogenesis

Klebsiella pneumoniae is an important pathogen causing difficult-to-treat urinary tract infections (UTIs). Over 1.5 million women per year suffer from recurrent UTI, reducing quality of life and causing substantial morbidity and mortality, especially in the hospital setting. Uropathogenic E. coli (UPEC) is the most prevalent cause of UTI. Like UPEC, K. pneumoniae relies on type 1 pili, tipped with the mannose-binding adhesin FimH, to cause cystitis. However, K. pneumoniae FimH is a poor binder of mannose, despite a mannose-binding pocket identical to UPEC FimH. FimH is composed of two domains that are in an equilibrium between tense (low-affinity) and relaxed (high-affinity) conformations. Substantial interdomain interactions in the tense conformation yield a low-affinity, deformed mannose-binding pocket, while domain-domain interactions are broken in the relaxed state, resulting in a high-affinity binding pocket. Using crystallography, we identified the structural basis by which domain-domain interactions direct the conformational equilibrium of K. pneumoniae FimH, which is strongly shifted toward the low-affinity tense state. Removal of the pilin domain restores mannose binding to the lectin domain, thus showing that poor mannose binding by K. pneumoniae FimH is not an inherent feature of the mannose-binding pocket. Phylogenetic analyses of K. pneumoniae genomes found that FimH sequences are highly conserved. However, we surveyed a collection of K. pneumoniae isolates from patients with long-term indwelling catheters and identified isolates that possessed relaxed higher-binding FimH variants, which increased K. pneumoniae fitness in bladder infection models, suggesting that long-term residence within the urinary tract may select for higher-binding FimH variants.

Accelerated wound healing and reduced scar formation induced by D-mannose: a possible role of mannose binding lectin

Wounds are most commonly caused by accidents, surgery and burns, and can be internal or external. Naturally, the wound healing process can take a long time and lead to scarring. In this study we present a technique to shorten wound healing time and prevent or mitigate scarring using D-mannose that is applied directly on the wound. The results showed that the healing time is almost halved compared to treatment with povidone-iodine solution which is an antiseptic widely used in surgery. D-Mannose is neither an antisepsis nor an antibiotic. We propose a posssible mechanism by which D-mannose binds to D-mannose binding lectin and immediately activates the innate immune system that ultimately phagocytizes pathogens and clears the wound of degraded cells and materials, which reduces inflammation and implicitly wound healing time. D-Mannose also intervenes in the coagulation process by binding to fibrinogen, generating a finer and denser fibrin, which visibly reduces collagen scars. Our findings show that applying D-mannose directly on the wound as a powder shortens wound healing time and visibly attenuates scarring. Apart from the unaesthetic appearance, these scars can also cause a certain tissue dysfunction, regardless of the affected organ.Graphical abstract

RNAi targeting LMAN1-MCFD2 complex promotes anticoagulation in mice.

Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) is a rare bleeding disease caused by variants in either lectin mannose binding 1 (LMAN1) or multiple coagulation factor deficiency 2 (MCFD2) gene. Reducing the level of FVIII by inhibiting the LMAN1-MCFD2 complex may become a new anticoagulant approach. We aimed to find a new therapeutic option for anticoagulation by RNA interference (RNAi) targeting LMAN1 and MCFD2. siRNA sequences with cross-homology between mice and humans were designed based on LMAN1 or MCFD2 transcripts in NCBI and were screened with the Dual-Luciferase reporter assay. The optimal siRNAs were chemically modified and conjugated with three N-acetylgalactosamine molecules (GalNAc-siRNA), promoting their targeted delivery to the liver. The expression of LMAN1 and MCFD2 in cell lines or mice was examined by RT-qPCR and western blotting. For the mice administered with siRNA, we assessed their coagulation function by measuring APTT and the activity of FVIII factor. After administration, siRNAs GalNAc-LMAN1 and GalNAc-MCFD2 demonstrated effective and persistent LMAN1 and MCFD2 inhibition. 7 days after injection of 3mg/kg GalNAc-LMAN1, the LMAN1 mRNA levels reduced to 19.97% ± 3.78%. MCFD2 mRNA levels reduced to 32.22% ± 13.14% with injection of 3mg/kg GalNAc-MCFD2. After repeated administration, APTT was prolonged and the FVIII activity was remarkably decreased. The tail bleeding test of mice showed that the amount of bleeding in the treated group did not significantly increase compared with the control group. Our study confirms that therapy with RNAi targeting LMAN1-MCFD2 complex is effective and can be considered a viable option for anticoagulation drugs. However, the benefits and potential risk of bleeding in thrombophilic mice model needs to be evaluated.

Impact of 5' Near Gene Variants of Mannose Binding Lectin (MBL2) on Breast Cancer Risk.

The immune system plays a bifaceted role in tumour development through modulation of inflammation. MBL binds to damage-associated molecular patterns and induces inflammation through the activation of complement pathway. Dysregulated inflammation plays a major role in breast cancer pathogenesis, thereby suggesting its contribution towards breast cancer risk. Literature asserts single-nucleotide polymorphisms (SNPs) modulating serum MBL levels. Therefore, studying MBL2 SNPs in breast cancer might provide valuable insight in the disease pathogenesis. The present case-control association study aimed to elucidate the association between MBL2 5' near gene SNPs and breast cancer risk. Breast cancer patients were recruited from Government Medical College, G.N.D. Hospital, Amritsar. The age- and gender-matched genetically unrelated healthy individuals, from adjoining regions, with no history of malignancy up to three generations were recruited as controls. The SNPs of MBL2 from the 5' near gene region with putative functional significance were selected based upon the in silico analysis and literature review. The genotypic, allelic and haplotype frequencies for the studied variants were assessed and compared in the study participants by ARMS-PCR and PCR-RFLP. No difference in allelic, genotypic and haplotype frequencies was reported for rs7096206, rs7084554 and rs11003125 in both the participant groups. rs7084554 (CC) was found to confer risk towards hormone receptor-positive breast cancer. An intermediate LD was observed between rs7084554 and rs11003125. The study reports association between MBL2 variant (rs7084554) and hormone receptor-positive breast cancer risk. Further research in this direction might validate the findings.

Chorioamnionitis: clinical, anamnestic and molecular-genetic parallels

Aim: to determine clinical, anamnestic and molecular-genetic parallels in emergence of clinical chorioamnionitis (CA) and severe forms of intrauterine infections (IUI) in high-risk pregnant women.Materials and Methods. A single-center prospective cohort comparative case-control study was conducted by examining 58 pregnant female patients aged 18 to 42 years with a verified CA diagnosis during pregnancy and childbirth at different gestation stages (main group), and 35 age-matched pregnant women with uncomplicated pregnancy and no significant extragenital pathology, aggravated factors of obstetric and gynecological history and risk factors for developing CA (control group), observed and performed a delivery in Yudin City Clinical Hospital. All women underwent clinical, anamnestic, laboratory, instrumental and molecular-genetic examitation. We studied the polymorphism of genes FCGR2A (Fc fragment of immunoglobulin G receptor IIa), IFN-γ (interferon gamma), IL-10 (interleukin-10), IL-6 (interleukin-6) and MBL2 (mannose binding lectin 2) to determine their role in assessing a risk of maternal and neonatal infection.Results. Among the patients with developed clinical CA vs. control subjects, more of them had a history of abortion and miscarriages (17.24 %), comorbid with chronic arterial hypertension (13.79 %), previous surgical interventions (27.59 %), as well as chronic inflammatory diseases (chronic tonsillitis, bronchitis, pyelonephritis, sinusitis; 27.59 % vs. 17.14 %). In addition to risk factors directly related to the infectious and inflammatory unfavorable background, they also had a significantly higher rate of obstetric complications: moderate preeclampsia – 6 (10.34 %) cases, threat of miscarriage or premature birth – 14 (24.14 %) cases vs. 1 (2.86 %) case in control group (p = 0.007), polyhydramnions – 4 (6.9 %) cases, placental insufficiency – 6 (10.34 %) cases. The frequency of premature rupture of membranes was 31.03 % in women with CA. Questionable cardiotocography (CTG) type was found in 24 (41.38 %) women with CA vs. 4 (11.4 3%) women without CA (p = 0.003), the pathological CTG type was observed only in women with CA. In the group with clinical CA and neonatal IUI, the combination of genotypes AG rs1801274 FCGR2A, ТT rs2430561 (IFN-γ)+874, GC rs1800795 (IL-6)-174 occurs in 80.65 % (25/31), whereas in women without severe neonatal IUI – in 37.04 % (10/27) (odds ratio (OR) =7.08; 95 % confidence interval (CI) = 2.166–23.166). In addition, the combination of alleles TT rs2430561 (IFN-γ)+874, GC+CC rs1800795 (IL-6)-174, AA rs1800450 MBL2 codon 54 was detected in 60.86 % (62/102) vs. 47.52 % (370/778) in main and control group (OR = 11.667; 95 % CI = 2.842–47.886), respectively.Conclusion. The study data evidence about importance of identifying genes for developing CA and neonatal septic complications to optimize and personalize management of high-risk patients (premature birth, infections during pregnancy, premature rupture of membranes).

HCMV US2 co-opts TRC8 to degrade the endoplasmic reticulum-resident protein LMAN2L.

The human cytomegalovirus (HCMV) pUS2 glycoprotein exploits the host's endoplasmic reticulum (ER)-associated degradation (ERAD) pathway to degrade major histocompatibility complex class I (MHC-I) and prevent antigen presentation. Beyond MHC-I, pUS2 has been shown to target a range of cellular proteins for degradation, preventing their cell surface expression. Here we have identified a novel pUS2 target, ER-resident protein lectin mannose binding 2 like (LMAN2L). pUS2 expression was both necessary and sufficient for the downregulation of LMAN2L, which was dependent on the cellular E3 ligase TRC8. Given the hypothesized role of LMAN2L in the trafficking of glycoproteins, we employed proteomic plasma membrane profiling to measure LMAN2L-dependent changes at the cell surface. A known pUS2 target, integrin alpha-6 (ITGA6), was downregulated from the surface of LMAN2L-deficient cells, but not other integrins. Overall, these results suggest a novel strategy of pUS2-mediated protein degradation whereby pUS2 targets LMAN2L to impair trafficking of ITGA6. Given that pUS2 can directly target other integrins, we propose that this single viral protein may exhibit both direct and indirect mechanisms to downregulate key cell surface molecules.

Mannose Binding Lectin and C3 Serum Levels in Coronary Artery Disease: A Cross-Sectional Study

ABSTRACT Background The process of tissue injury in coronary artery disease (CAD) has been associated with activation of the complement system, partly due to the action of mannose-binding lectin (MBL) and C3, which are expressed in atherosclerotic lesions. Objective The aim of this study was to evaluate the serum levels of MBL and C3 in patients with CAD and to compare them with healthy controls. Additionally, we aim to assess the correlation between MBL and C3 levels and cardiometabolic parameters. Methods MBL and C3 serum concentration were determined by ELISA and immunoturbidimetry, respectively, in up to 119 patients undergoing coronary angiography for CAD evaluation, comprising 48 individuals diagnosed with acute myocardial infarction (MI) and 71 without MI. A total of 93 paired healthy controls were included in the study. Results Individuals with CAD had MBL serum concentration higher than controls (p = .002), regardless of the presence of MI (p = .006). In addition, high concentration of MBL (>2000 ng/mL) was more frequent in patients with CAD (p = .007; OR = 2.6; 95% CI = 1.3–5.1). C3 levels were not significantly associated with any of the patient groups but were positively correlated with cardiometabolic parameters such as body mass index (BMI) and triglycerides levels. Conclusions Higher concentrations of MBL were found to be associated with CAD, whereas C3 levels were found to be associated with cardiovascular risk factors.

Abstract 6533: Pivotal role of specific LYVE1+ tissue resident macrophages in PDAC progression & immunotherapy resistance

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by dense fibrotic stroma and abundant myeloid cell infiltration, which render it resistant to any therapeutic interventions, including immunocheckpoint blockade (ICB) therapy. Understanding the composition and function of myeloid cells within the PDAC microenvironment may help identify promising targets for PDAC immunotherapy. Tissue resident macrophages (TRMs) contribute to organogenesis and tissue regeneration and metabolism. In this study, we discovered a distinct population of pancreas TRMs that highly express lymphatic vessel hyaluronan receptor 1 (LYVE-1). Single cell RNAseq data reveal that LYVE-1+ TRM cluster in the pancreas expresses high levels of complement activation genes and transcription factors such as c-Maf and Stab1. RNAseq data also confirm that LYVE-1+ TRMs express enriched genes related to mannose binding, endocytosis, and glutathione metabolic process, while LYVE-1 negative macrophages express enriched genes related to antigen processing and presentation, T cell activation, and phagocytosis. Multiparameter flow cytometric analysis demonstrates that LYVE-1+ TRMs express M2-like markers, including increased CD163, CD206 and decreased MHC Class II molecule. During PDAC development and progression, LYVE-1+ TRMs expand and localize around the tumor border, promoting fibrotic stroma formation. Imaging mass cytometry (IMC) also reveals abundant infiltration of LYVE-1+CD14+CD68+ macrophages in human PDAC tumors and colocalized with collagen deposition. This subset of macrophages also highly express c-Maf. Through the use of Lys-Cre-c-Maf f/f mice, we demonstrate that depletion of c-Maf from myeloid cells significantly reduces LYVE-1+ TRMs and polarizes them to resemble an M1-like phenotype. In conclusion, our findings suggest that LYVE-1+ macrophages are a unique subset of myeloid cells within the pancreas and likely play a critical role in PDAC progression and immunotherapeutic resistance. Future work will focus on targeting LYVE1+ TRMs using various approaches, such as conditional knockout mice and small molecule inhibitors, to determine their therapeutic potential for PDAC treatment. Presented by Dr. Hong Li Citation Format: Hong Li, Jun Yan. Pivotal role of specific LYVE1+ tissue resident macrophages in PDAC progression & immunotherapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6533.

P139 A potential protective rule of Mannose Binding lectin (MBL) against SARS-COV2 infection in IBD patients

Abstract Background Since the beginning of the COVID-19 pandemic, IBD patients have appeared to be less susceptible to a severe form of the disease, despite undergoing immunosuppressive treatments. Mannose binding lectin (MBL) is a humoral fluid-phase pattern recognition molecule (PRM) crucial for activating the lectin complement pathway. It is capable of binding to the spike protein and blocking SARS-CoV-2 infection. Low MBL expression has been linked to poor outcomes in both SARS and SARS- CoV-2 infections. In IBD patients, the role of MBL is controversial; low concentrations seem to predispose individuals to the development of IBD, while high concentrations have been observed in severe forms of Crohn's disease. Methods Since April 2020, 104 IBD patients have been enrolled, with 20% treated with mesalazine, 50% with Anti-TNFa, 20% with Vedolizumab, and 20% receiving no treatment. Additionally, 45 healthy controls (HC) from North Italy were included. Serum samples and colon biopsies from inflamed and non- inflamed mucosa were collected. Serum samples underwent an ELISA test to quantify circulating MBL concentration, and MBL gene expression in biopsies was analyzed using qPCR. Results Both Crohn's disease and Ulcerative Colitis patients exhibited significantly higher circulating MBL levels than HC (411.6 ± 45.5 ng/ml vs. 160.9 ± 35.3 ng/ml, p < 0.05). Patients treated with Anti-TNFa showed significantly higher circulating MBL levels compared to those not undergoing therapy (530.1 ± 76.5 ng/ml vs. 225.4 ± 61.6 ng/ml, p < 0.05) and patients receiving Vedolizumab (530.1 ± 76.5 ng/ml vs. 155.3 ± 32.1 ng/ml, p < 0.05). MBL intestinal gene expression is higher in IBD patients than HC (5.55 ± 0.9 vs. 2.36 ± 0.6; p=0.591) and tended to be elevated at similar levels in inflamed and non-inflamed mucosa (5.14 ± 1.4 vs. 5.79 ± 1.1; p=0.337), suggesting a prevalent genetic determination of MBL concentration regardless of the inflammatory background. Conclusion MBL appears to play a key role in SARS-CoV-2 infection. We demonstrate that IBD patients have, on average, higher circulating MBL levels than HC independently of their inflammatory status. The highest MBL levels were observed in patients treated with Anti-TNFa. These findings contribute to understanding the reported low mortality and hospitalization for COVID-19 among IBD patients treated with Anti-TNFa.

High-Mannose Oligosaccharide Hemimimetics that Recapitulate the Conformation and Binding Mode to Concanavalin A, DC-SIGN and Langerin.

The "carbohydrate chemical mimicry" exhibited by sp2 -iminosugars has been utilized to develop practical syntheses for analogs of the branched high-mannose-type oligosaccharides (HMOs) Man3 and Man5 . In these compounds, the terminal nonreducing Man residues have been substituted with 5,6-oxomethylidenemannonojirimycin (OMJ) motifs. The resulting oligomannoside hemimimetic accurately reproduce the structure, configuration, and conformational behavior of the original mannooligosaccharides, as confirmed by NMR and computational techniques. Binding studies with mannose binding lectins, including concanavalin A, DC-SIGN, and langerin, by enzyme-linked lectin assay and surface plasmon resonance revealed significant variations in their ability to accommodate the OMJ unit in the mannose binding site. Intriguingly, OMJMan segments demonstrated "in line" heteromultivalent effects during binding to the three lectins. Similar to the mannobiose (Man2 ) branches in HMOs, the binding modes involving the external or internal monosaccharide unit at the carbohydrate binding-domain exist in equilibrium, facilitating sliding and recapture processes. This equilibrium, which influences the multivalent binding of HMOs, can be finely modulated upon incorporation of the OMJ sp2 -iminosugar caps. As a proof of concept, the affinity and selectivity towards DC-SIGN and langerin were adjustable by presenting the OMJMan epitope in platforms with diverse architectures and valencies.

Abstract 061: Identification of Proteins Predictive of Post‐Thrombectomy Outcome Based on an Appalachian vs. Non‐Appalachian Cohort

Introduction The Appalachia region of North America is known to have significant health disparities, specifically, worse risk factors and outcomes for stroke. Appalachians are more likely to have comorbidities related to stroke, such as diabetes, obesity, and tobacco use, and are often less likely to have stroke interventions such as mechanical thrombectomy (MT) for emergent large vessel occlusion (ELVO). As our Comprehensive Stroke Center directly serves stroke subjects from both Appalachian and non‐Appalachian areas, we set out to identify proteomic biomarkers predictive of stroke outcomes specific to subjects residing in Appalachia. Methods Eighty‐one subjects met inclusion criteria for this study. These subjects underwent MT for ELVO, and during the procedure, carotid arterial blood samples were acquired and subsequently sent for proteomic analysis. Samples were processed in accordance with the Blood And Clot Thrombectomy Registry And Collaboration (BACTRAC; clinicaltrials.gov; NCT 03153683). Statistical analyses were utilized to examine whether relationships between protein expression and outcomes differed by Appalachian status for functional outcomes (NIH Stroke Scale; NIHSS and Modified Rankin Score; mRS), cognitive outcomes (Montreal Cognitive Assessment; MoCA), and mortality. Results No significant differences were found in demographic data nor co‐morbidities when comparing Appalachia to non‐Appalachia subjects. However, time from stroke onset to treatment (last known normal) was significantly longer in patients from Appalachia, so this datapoint was entered as a co‐variate in all predictive models. A comprehensive analysis of 184 cardiometabolic and inflammatory proteins revealed seven Appalachia‐specific proteins predictive of NIHSS, fourteen predictive of MoCA, six predictive of mRS, and seven proteins related to mortality. Specifically, within the Appalachian group, the protein multiple epidermal growth factor‐like domains protein 9 (MEGF9) was positively correlated to discharge NIHSS, elevated levels of the proteins coagulation factor XI (F11) and mannose binding protein (MBL2) were found to have an increased likelihood of worse mRS, but there were no proteins identified from the Appalachian cohort that were predictive of worse MoCA score, nor worse mortality. Conclusion Appalachia is an underserved population with significantly worse health disparities, specifically related to ischemic stroke. Our study found that patients who presented from Appalachian regions have a different proteomic response at time of MT when compared to otherwise similar subjects presenting from non‐Appalachian communities. These differentially expressed proteins could be used as prognostic biomarkers as well as novel therapies targeted at an underserved population. Lastly, expression differences may be in part related to environmental exposures, such as coal pollution, which will require additional studies moving forward.

Association of rs6695096 Single Nucleotide Polymorphism of Human Mannose Binding Lectin Associated Serine Protease 2 (MASP2) Gene Locus and MASP2 Serum Level with Systemic Lupus Erythematosus

Association of rs6695096 Single Nucleotide Polymorphism of Human Mannose Binding Lectin Associated Serine Protease 2 (MASP2) Gene Locus and MASP2 Serum Level with Systemic Lupus Erythematosus

Association of mannose binding lectin with chronic obstructive pulmonary disease susceptibility and its clinical outcomes.

The physiological interactions of MBL suggest its contribution towards the pathogenesis of COPD. The present case-control study was undertaken to elucidate the role of MBL with COPD risk and clinical outcomes in north Indian cohort. Patients were enrolled as per GOLD criteria. MBL2 variants were selected based on the literature and their putative functional significance. Genotyping of six single nucleotide polymorphisms of MBL2 comprising of two coding (rs1800450, rs1800451) and four non-coding variants (rs11003125, rs7096206, rs11003123 and rs7095891) was done by using PCR-RFLP and ARMS-PCR. Serum MBL levels were analysed by sandwich ELISA. Overall findings of the molecular genetic analysis of MBL2 indicated significant difference in frequency of three of the six studied variants, between patients and controls or among different disease severity stages. Heterozygous genotype of rs7095891 showed significant protective association towards severity of disease. Linkage disequilibrium (LD) analysis indicated a strong LD between rs1800450 and rs7095891 while intermediate LD was observed for rs11003123/rs11003125 and rs7096206/rs11003125. Haplotype analysis revealed 17.14-fold risk of developing exacerbations conferred by GGGTGG haplotype. Significantly low serum MBL levels observed in COPD patients as compared to controls. Significant difference in MBL deficiency levels were also observed for homozygous wild and variant genotypes of rs11003125 and rs7096206 respectively, as well as for all genotypes of rs11003123 than respective controls. The present study reinforces the role played by MBL in the susceptibility, protection and clinical outcomes of COPD. Therefore, including the reported associations at diagnostic, prognostic and therapeutic interventions may prove helpful.

Mannose binding lectin-associated serine protease-1 is a novel contributor to myocardial ischemia/reperfusion injury

BackgroundThe lectin pathway has been demonstrated to play a critical role in the pathological process of myocardial ischemia/reperfusion injury (IRI). Mannose-binding lectin (MBL)-associated serine protease-1 (MASP-1), especially different from other components of the lectin pathway, mediates proinflammatory and procoagulant reactions independent of complement cascades. However, the role of MASP-1 in myocardial IRI remains unknown so far. MethodsMyocardial IRI was established with 45 min ischemia and 24 h reperfusion in mice. C1 inhibitor, as the natural inhibitor of MASP-1, was administrated at 20 IU/Kg via tail vein 5 min before surgical operation. Cardiac function and myocardial infarct size were assessed. Myocardial histology and fibrosis were evaluated by H&E and Masson staining, respectively. Deposition of MASP-1, expression of PAR-1/4 and neutrophil extracellular traps (NET) were investigated on myocardium tissue by IHC staining. Cell apoptosis was detected by TUNEL assay. Levels of myocardial enzymes and proinflammatory cytokines were determined by ELISA. ResultsInhibition of MASP-1 with C1 INH improved cardiac function and alleviated myocardium tissue injury (infarct size, enzymes, histology and fibrosis) after myocardial IRI. Deposition of MASP-1 and expression PAR-1, as well as NET formation in myocardial tissue were suppressed by MASP-1 inhibitor, while PAR-4 was elevated. Levels of apoptosis, HMGB-1 and IL-6 were lower after blocking MASP-1. Yet, IL-8 and TNF-α remained unchanged. ConclusionsMASP-1, as a new contributor, played a critical role in myocardial IRI. Inhibition of MASP-1 protected myocardial tissue from IRI probably via regulation of PARs/NET pathway. This may provide a novel target strategy against myocardial IRI.

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 binding lectin deficiency and COVID-19 rates of thrombosis and mortality: Partial protection by immunodeficiency

Objective: The purpose of this study is to determine the effects of COVID-19 infection on individuals with mannose binding lectin deficiency. Methods: An electronic medical records search was conducted for MBL deficiency and COVID-19 positive tests from March 2020-August 2022. Individualized chart analysis was conducted and statistical analysis was performed. Results: Thirty-three people in WVU medicine health system carry a diagnosis of mannose binding lectin deficiency and were diagnosed with COVID-19. The mean age of this cohort was 41 years. Seven individuals had severe enough symptoms to lead to an emergency department visit. One person was hospitalized. MBL deficient individuals had 7 times the odds of hospitalization ( p = .1506, OR 7.06 (CI 1.117-44.52)) compared to the general public. There was zero mortality among the MBL deficient population. None of the patients reported thrombosis or blood clots. Conclusion: This retrospective cross-sectional analysis of those with known MBL deficiency and COVID-19 infection suggest a lower risk of fatalities and thrombotic events in this cohort. There was however a higher odds ratio of hospitalization compared to the general public, although this was not statistically significant.

Association between mannose binding lectin gene polymorphisms and clinical severity of COVID-19 in children.

Mannose-binding lectin (MBL) is a member of innate immunity and acts with MASP (MBL-associated serine protease) to activate the lectin pathway of the complement system. MBL gene polymorphisms are associated with susceptibility to infectious diseases. This study investigated whether MBL2 genotype, serum MBL levels, and serum MASP-2 levels affect the course of SARS-CoV-2 infection. Pediatric patients diagnosed with COVID-19 by positive real-time polymerase chain reaction (PCR) were included in the study. Single nucleotide polymorphisms in the promoter and exon 1 in the MBL2 gene (rs11003125, rs7096206, rs1800450, rs1800451, rs5030737) were identified by a PCR and restriction fragment length polymorphisms analysis. Serum MBL and MASP-2 levels were measured by ELISA. COVID-19 patients were divided into asymptomatic and symptomatic. Variables were compared between these two groups. A total of 100 children were included in the study. The mean age of the patients was 130 ± 67.2 months. Of the patients, 68 (68%) were symptomatic, and 32 (32%) were asymptomatic. The polymorphisms in the - 221nt and - 550nt promoter regions did not differ between groups (p > 0.05). All codon 52 and codon 57 genotypes were determined as wild-type AA. AB genotypes were found 45.6% in symptomatic patients while 23.5% in asymptomatics. Moreover, BB genotype was detected 9.4% in symptomatic and 6.3% in asymptomatic patients (p < 0.001). B allele was more frequent in symptomatic patients (46.3%) compared to asymptomatic patients (10.9%). (p < 0.001). Serum MBL and MASP-2 levels did not differ statistically between the groups (p = 0.295, p = 0.073). These findings suggest that codon 54 polymorphism in the MBL2 gene exon-1 region can be associated with the symptomatic course of COVID-19.

Glycan-Presenting Coacervates Derived from Charged Poly(active esters): Preparation, Phase Behavior, and Lectin Capture.

This study presents the preparation and phase behavior of glycan-functionalized polyelectrolytes for capturing carbohydrate-binding proteins and bacteria in liquid condensate droplets. The droplets are formed by complex coacervation of poly(active ester)-derived polyanions and polycations. This approach allows for a straightforward modular introduction of charged motifs and specifically interacting units; mannose and galactose oligomers are used here as first examples. The introduction of carbohydrates has a notable effect on the phase separation and the critical salt concentration, potentially by reducing the charge density. Two mannose binding species, concanavalin A (ConA) and Escherichia coli, are shown to not only specifically bind to mannose-functionalized coacervates but also to some degree to unfunctionalized, carbohydrate-free coacervates. This suggests non-carbohydrate-specific charge-charge interactions between the protein/bacteria and the droplets. However, when mannose interactions are inhibited or when non-binding galactose-functionalized polymers are used, interactions are significantly weakened. This confirms specific mannose-mediated binding functionalization and suggests that introducing carbohydrates reduces non-specific charge-charge interactions by a so far unidentified mechanism. Overall, the presented route toward glycan-presenting polyelectrolytes enables new functional liquid condensate droplets with specific biomolecular interactions.

MBL2 gene variants and susceptibility to meningitis in Egyptian patients

BackgroundMeningitis is inflammation of the membranes enclosing the brain and spinal cord. It is a fatal disease with severe morbidity and mortality. Mannose binding lectin (MBL) encoded by MBL2 gene activates complement system through lectin pathway in innate immunity to defense against the infections. ObjectiveThe current study aimed to investigate the promoter and exon 1 variants of MBL2 gene among Egyptian patients having meningitis to explore their role in disease susceptibility. Patients and methodsThis case–control study, included 53 patients and 50 sex and age matched controls. MBL2 genotyping was done using Sanger sequencing. ResultsThe frequency of one promoter (c.-290C > G) and four in exon 1 (c.161G > A, c.170G > A, c.154C > T and c.132C > T) as well as another one located in its 5′utranslated part (c.-66C > T) variants were estimated. The incidence of the four individual exonic variants was not significantly different between cases and healthy individuals (all P > 0.05). The promoter variant, c.-290C > G was found in all examined patients (84.9% of the patients in homozygote state and 15.1% of patients in heterozygous state) with a highly significant variance in the prevalence of this variant between cases and control group (p = 0.0001). Additionally, UTR variant (c.-66C > T) was also significantly higher in patients than controls (P = 0.033).In comparison with clinical outcome, it was found that c.170G > A variant named C allele was associated with favorable outcome in the studied patients (P = 0.025). ConclusionThe results obtained showed that the Promoter (c.-290C > G) and UTR (c.-66C > T) variants of MBL2 gene may be potential risk factors for disease susceptibility in Egyptian cases with meningitis. Our results also proposed that c.170G > A (C allele and CC genotype) could affect the severity and play a protective role in these patients. The other genetic variants of MBL2 gene, including c.132C > T, c.161G > A (A > B), and c.154C > T (A > D) that were investigated, did not show any association with susceptibility or severity of meningitis.

Characterization of Mannose Binding Lectin (MBL) Levels in Type-2 Diabetes Mellitus Patients Amongst Pakistani Population

Introduction: Mannose Binding Lectin (MBL) is a pattern recognizing molecule in the Lectin complement pathway and acts by activating the complement cascade via binding with ligands. There is evidence of increased autoreactivity of Mannose Binding Lectin in various diseases especially diabetes. MBL deficiency can reduce pathogen clearance and impair atherogenic lipoprotein removal whereas higher levels are associated with exaggerated immune response due to complement activation in the presence of hyperglycemia.&#x0D; Aims &amp; Objectives: This study aims to find out the association of MBL (Mannose Binding Lectin) with different clinical parameters in healthy controls and type 2 DM patients to predict disease outcome in type 2 diabetics. Mean level of MBL in type 2 diabetics and healthy population will be compared to characterize MBL levels amongst diabetics helping the clinicians to stratify patients according to disease severity.&#x0D; Place and duration of study: It was a cross sectional analytical study conducted at Chughtai Institute of Pathology from July 2019 to January 2020 on samples collected nationwide at Chughtai Lab collection centres.&#x0D; Material &amp; Methods: We selected 300 adult male and females in this study after taking informed consent based on strict inclusion and exclusion criteria. Of these 200 were known cases of type 2 diabetes mellitus and 100 healthy controls. .Fasting blood samples were drawn from both groups were analyzed for hs-CRP, HbA1c, creatinine, Total Cholesterol, Alanine amino transfer as (ALT), HDL-Cholesterol, LDL-Cholesterol, Glucose, Triglyceride, and Mannose Binding lectin. eGFR (Estimated Glomerular Filtration rate) was calculated for each patient and control. Data was analyzed via Graph Pad Prism 5 and SPSS version 23.0, p value ? 0.05 was taken as significant.&#x0D; Results: Mean age of the participants was 47.9 years in diabetic group and 39.3 years in healthy controls. The healthy population had a mean MBL level of 110.1 (SD±3.94) pg/ml and mean MBL level of diabetic group was 197.9 (SD±12.84) pg/ml (p&lt;0.05). No differences in MBL levels were detected based on gender distribution. There was a significant difference among HbA1c, LDL-C, HDL-C, Fasting Glucose, TG, creatinine and eGFR amongst the diabetic and the healthy group (p&lt;0.05). There was a negative correlation between MBL levels and plasma glucose and a positive correlation between the former and HDL-C in the healthy controls. In diabetic patients having MBL above 178pg/ml, a positive correlation of HbA1C with MBL was found. CRP in the healthy population resembled levels in patients with elevated MBL and the ratio Trig/HDL was higher in this subgroup having a positive correlation with MBL.&#x0D; Conclusion: MBL plays a role in pathophysiology of diabetes mellitus and elevated MBL having positive correlation with HbA1c might show association of glycemic control with the biomarker levels. A direct relationship of MBL with development of cardiovascular complications in type 2 diabetics was suggested by a positive association of MBL with TG to HDL-C ratio.