Analysis of Mannose-Binding Lectin Protein and mRNA Levels on Selected Chicken Breeds in South Africa.

BACKGROUND: Mannose-binding lectin (MBL) is a key component of the innate immune system that plays a crucial role in binding to the microbial sugar surface to recognize and eliminate pathogens by activating the complement system. OBJECTIVE: To detect and quantify the MBL protein concentration and chicken MBL expression in selected chicken breeds in South Africa. METHODS: Forty-five blood samples from three indigenous chicken breeds, Ovambo (OV = 9), Venda (VD = 9) and Potchefstroom Koekoek (PK = 9), and two exotic chicken breeds, Rhode Island Red (RIR = 9) and Lohmann Brown (LB = 9), were used for MBL protein concentration using enzyme-linked immunosorbent assay (ELISA) techniques. Also 20 liver samples from symptomatic two indigenous chicken breeds, OV (5) and PK (5), and two exotic chicken breeds, RIR (5) and LB (5), were used for MBL expression using quantitative polymerase chain reaction (qPCR) techniques. A general linear model was done using Tukey's multiple comparison post hoc test. RESULTS: The findings revealed MBL protein concentration from 5.26 to 18.56 µg/mL. The LB breed had the lowest mean 6.40 ± 0.80 µg/mL, whereas the PK breed had the highest mean MBL concentration of 17.70 ± 0.24 µg/mL of MBL protein concentration. At 12, 25 and 35 weeks, the MBL proteins of OV, VD, PK, RIR and LB varied significantly at p ≤ 0.05. The mRNA MBL expression of OV and LB breeds showed a 1-fold decrease in MBL expression, while RIR showed a 2-fold increase in MBL expression, and the PK showed more than a 3-fold increase in MBL expression relative to the control. The least-squares means for OV, LB, PK and RIR mRNA MBL expression were 0.54 ± 0.19, 0.68 ± 0.30, 4.46 ± 2.76 and 2.89 ± 0.19 µg/mL, respectively. CONCLUSION: MBL protein was detected and quantified with distinct differences in concentration and expression levels  at the presence of mycoplasma gallisepticum among the sampled South African chicken breeds. This highlights the genetic diversity of MBL as a tool for disease prevention in South African chicken breeds.

Clinical associations of complement-activating collectins, collectin-10, collectin-11 and mannose-binding lectin in preterm neonates.

Introduction: Premature and low-birthweight infants are at especially high risk of perinatal complications, including impaired thermoregulation, infections and respiratory distress. Such adverse effects and the need for invasive procedures are associated with high mortality among preterms. This study focused on the influence of the innate immune system and tested the levels of collectins, collectin-10 (CL-10), collectin-11 (CL-11) and mannose-binding lectin (MBL) in preterm neonates. Methods: Cord blood was collected from 535 preterms (born at gestational age ≤37 weeks). COLEC10 and COLEC11 polymorphisms were analyzed by real-time PCR and those of MBL2 by PCR/PCR-RFLP. The concentrations of collectins in sera from cord blood were determined with ELISA. Findings: Low concentrations of CL-10 in cord sera (<462 ng/ml corresponding to the 10th percentile) were significantly associated with births at GA ≤32 weeks. Median levels of both CL-10 and CL-11 were significantly lower in preterms with very low birthweight (<1500 g), low Apgar 1' score and those who needed prolonged hospitalisation. Lower median CL-10 was also observed in fetal growth restriction cases. An important finding was the decreased concentrations of CL-10, CL-11 and MBL in respiratory distress syndrome (RDS). For CL-10 and CL-11, that relationship was confined to infants born at GA ≥33 weeks and/or with body mass at birth ≥1500 g. Only CL-10 was found to influence susceptibility to early-onset infections. COLEC11 heterozygosity for the activity-decreasing polymorphism (rs7567833, +39618 A>G, His219Arg) was more common in preterm premature rupture of membranes (pPROM) cases, compared with corresponding reference groups. Furthermore, C/T or T/T genotypes at COLEC11 at rs3820897 (-9570 C>T) as well as MBL deficiency-associated MBL2 gene variants were more common in preterms diagnosed with RDS than among unaffected newborns. Conclusion: The complement-activating collectins investigated here could be important for maintaining homeostasis in preterm neonates. Despite similar structure and specificity, MBL, CL-10 and CL-11 manifest a different spectrum of clinical associations.

Causal association of immune effector proteins with sepsis: A Mendelian randomization study.

Sepsis is an infection-induced systemic inflammatory response syndrome. Immune regulation plays a crucial role in sepsis. We looked into the link between immune effector-related proteins and sepsis in this study by using both univariate and multivariate Mendelian randomization (MR) analyses. We accessed and collected data from the Integrative Epidemiology Unit's Open About Sepsis genome-wide association study database. The 6 immune effector-associated proteins each contained 10,534,735 single-nucleotide polymorphisms from 3301 samples. Using the weighted median, MR-Egger, simplex, inverse-variance weighting, and weighted mode methods, univariate MR then investigated the link between complement factor H-related protein-5 (CFHR5), Fc epsilon receptor II (FCER2), granzyme B (GZMB), major histocompatibility complex, class II, DQ alpha (HLA-DQA2), mannose-binding lectin 2 (MBL2), or myeloperoxidase (MPO) and sepsis. In the inverse-variance weighted results, the P values of all 6 immune effector-related proteins were <0.05, suggesting a possible causal relationship between them and sepsis. MBL2 (odds ratio [OR] = 1.046) was a risk factor for sepsis, while the other proteins (FCER2: OR = 0.922; GZMB: OR = 0.908; CFHR5: OR = 0.858; HLA-DQA2: OR = 0.896; MPO: OR = 0.875) were safety factors. By revealing a causal link between sepsis and CFHR5, FCER2, GZMB, HLA-DQA2, MBL2, or MPO, our study offers an essential resource for additional investigations on the subject.

Landscape of in situ cytokine expression, soluble C-type lectin receptors, and vitamin D in patients with recurrent vulvovaginal candidiasis.

The immunopathogenesis of recurrent vulvovaginal candidiasis (RVVC) is poorly understood. Recently, it was reported that patients with RVVC present a decrease in both the fungicidal capacity of neutrophils and the proliferative capability of peripheral blood mononuclear cells in response to Candida albicans infection, suggesting an alteration in the innate and adaptive immune response. The aim of this study was to determine the in-situ expression, in the vaginal mucosa, of genes associated with the immune response, as well as the serum concentrations of dectin-1, mannose-binding lectin (MBL), and vitamin D in patients with RVVC. A study was carried out on 40 patients with a diagnosis of RVVC and 26 healthy women. Vaginal scrapings were obtained, and the expression of genes that encode cytokines and transcription factors specific for Th1, Th2, Th17, Treg, pro-inflammatory profiles, and enzymes related to oxidative/microbicidal mechanisms was evaluated by quantitiative polymerase chain reaction (qPCR). Additionally, serum levels of vitamin D and the soluble receptors dectin-1 and MBL were determined by enzyme-linked immunosorbent assay (ELISA). In patients with RVVC, a decreased expression of T-bet, RORγ-T, IL-1ß, and IL-17, and an increase in the expression of FOXP3, IL-4, IL-8, IL-10, and IL-18 were observed when compared to healthy women: moreover, decreased levels of MBL were also observed in these patients. These results confirm that patients with RVVC present in-situ alterations in both the specific and adaptive immune response against Candida spp., a fact that could be associated with the exaggerated vaginal inflammatory response.

The study concerns the immune response of women with recurrent vulvovaginal candidiasis; we observed an alteration in the expression of genes that participate in the control of infection, a fact that could be associated with the exaggerated vaginal inflammatory response observed in those patients.

Mannose-Binding Lectin Gene Variants as Disease Susceptibility Biomarkers in Rheumatoid Arthritis.

Background: Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disease characterized by progressive destruction of peripheral joints. About 1% of the human population worldwide is suffering from this disease. The pathophysiology of RA is largely being influenced by immune dysregulation. Mannose-binding lectin (MBL), an acute-phase protein, has been reported to play an important role in pathogenesis of RA by the activation of complement pathway. Various studies documented the established the role of MBL in pathogenesis of various autoimmune diseases, including RA. MBL protein is encoded by gene MBL2, mapped on chromosome 10q11.2-q21. Objective: Both MBL serum levels and activity are mainly determined genetically by its variants. So considering the putative clinical role of MBL2, this case-control association study was designed to assess its six functional variants in a northwestern Indian cohort. Methods: Genetic typing of six MBL2 variants was done by amplification refractory mutation system-polymerase chain reaction. Data were analyzed using suitable statistical tools. Results: Significant difference has been observed in genotypic and allelic distribution between cases and controls for rs11003125. Comparison of allelic distribution for rs1800450 showed significantly high prevalence of A allele in cases than controls. Conclusion: These results indicate that MBL2 variants may act as plausible marker for susceptibility toward RA. Keeping this in view, it is pertinent to screen these variants in other population groups of India.

Mannan-Binding Lectin Is Associated with Inflammation and Kidney Damage in a Mouse Model of Type 2 Diabetes.

Autoreactivity of the complement system may escalate the development of diabetic nephropathy. We used the BTBR OB mouse model of type 2 diabetes to investigate the role of the complement factor mannan-binding lectin (MBL) in diabetic nephropathy. Female BTBR OB mice (n = 30) and BTBR non-diabetic WT mice (n = 30) were included. Plasma samples (weeks 12 and 21) and urine samples (week 19) were analyzed for MBL, C3, C3-fragments, SAA3, and markers for renal function. Renal tissue sections were analyzed for fibrosis, inflammation, and complement deposition. The renal cortex was analyzed for gene expression (complement, inflammation, and fibrosis), and isolated glomerular cells were investigated for MBL protein. Human vascular endothelial cells cultured under normo- and hyperglycemic conditions were analyzed by flow cytometry. We found that the OB mice had elevated plasma and urine concentrations of MBL-C (p < 0.0001 and p < 0.001, respectively) and higher plasma C3 levels (p < 0.001) compared to WT mice. Renal cryosections from OB mice showed increased MBL-C and C4 deposition in the glomeruli and increased macrophage infiltration (p = 0.002). Isolated glomeruli revealed significantly higher MBL protein levels (p < 0.001) compared to the OB and WT mice, and no renal MBL expression was detected. We report that chronic inflammation plays an important role in the development of DN through the binding of MBL to hyperglycemia-exposed renal cells.

Mannan-binding lectin inhibits oxidative stress-induced senescence via the NAD+/Sirt1 pathway.

Prolonged or excessive oxidative stress can lead to premature cellular and body aging. Mannan-binding lectin (MBL) is synthesized by the liver and plays an important role in innate immunity, anti-inflammation, and anti-oxidation, and has a positive impact on health and longevity. To date, few studies investigated the role of MBL in attenuating oxidative stress-induced senescence. In this study, we evaluated the role of MBL in oxidative stress-induced premature aging and explored its underlying mechanism in C57BL/6 mice and mouse embryonic fibroblasts (NIH/3T3). First, we established an oxidative premature senescence model induced by D-galactose in C57BL/6 mice. We found that MBL-deficient mice had a marked aging-like appearance, reduced learning and spatial exploration abilities, severe liver pathological damage, and significantly upregulated expression of Senescence-associated proteins (p53 and p21), inflammatory kinesins (IL-1ß and IL-6), and the senescence ß-galactosidase (SA-ß-Gal) positive rate as compared with WT mice. In the H2O2-induced oxidative senescence model of NIH/3T3 cells, consistent results were obtained after MBL intervention. In addition, MBL effectively inhibited G1 phase arrest, ROS levels, DNA damage, and mitochondrial dysfunction in premature senescent cells. Mechanistically, we found that oxidative stress inhibited the nicotinamide adenine dinucleotide (NAD+)/ silent information regulator 1 (Sirt1) signaling pathway, while MBL activated the NAD+/Sirt1 signaling pathway inhibited by oxidative stress. In addition, MBL could activate the NAD+/Sirt1 pathway by upregulating NAMPT, which in turn inhibited p38 phosphorylation by activating the NAD+/Sirt1 pathway. In conclusion, MBL inhibits oxidative aging, which may facilitate the development of therapeutics to delay oxidative aging.

The mannose-binding lectin (MBL) gene cloned from Exopalaemon carinicauda plays a key role in resisting infection by Vibrio parahaemolyticus.

Mannose-binding lectin (MBL) is a vital member of the lectin family, crucial for mediating functions within the complement lectin pathway. In this study, following the cloning of the mannose-binding lectin (MBL) gene in the ridgetail white prawn, Exopalaemon carinicauda, we examined its expression patterns across various tissues and its role in combating challenges posed by Vibrio parahaemolyticus. The results revealed that the MBL gene spans 1342 bp, featuring an open reading frame of 972 bp. It encodes a protein comprising 323 amino acids, with a predicted relative molecular weight of 36 kDa and a theoretical isoelectric point of 6.18. The gene exhibited expression across various tissues including the eyestalk, heart, gill, hepatopancreas, stomach, intestine, ventral nerve cord, muscle, and hemolymph, with the highest expression detected in the hepatopancreas. Upon challenge with V. parahaemolyticus, RT-PCR analysis revealed a trend of MBL expression in hepatopancreatic tissues, characterized by an initial increase followed by a subsequent decrease, peaking at 24 h post-infection. Employing RNA interference to disrupt MBL gene expression resulted in a significant increase in mortality rates among individuals challenged with V. parahaemolyticus. Furthermore, we successfully generated the Pet32a-MBL recombinant protein through the construction of a prokaryotic expression vector for conducting in vitro bacterial inhibition assays, which demonstrated the inhibitory effect of the recombinant protein on V. parahaemolyticus, laying a foundation for further exploration into its immune mechanism in response to V. parahaemolyticus challenges.

Mannose-binding lectin gene sequence data in Kelantan population.

The human mannose-binding lectin (MBL) gene encodes a polymorphic protein that plays a crucial role in the innate immune response. Human MBL deficiency is associated with immunodeficiencies, and its variants have been linked to autoimmune and infectious diseases. Despite this significance, gene studies concerning MBL sequencing are uncommon in Malaysia. Therefore, we aimed to preliminary described the human MBL sequencing dataset based on the Kelantan population. Blood samples were collected from 30 unrelated individuals and underwent DNA extraction, genotyping, and sequencing. The sequencing data generated 886 bp, which were deposited in GenBank (ON619541-ON619546). Allelic variants were identified and translated into six MBL haplotypes: HYPA, HYPB, LYPB, LXPB, HXPA, and LXPA. An evolutionary tree was constructed using the haplotype sequences. These findings contribute to the expansion of MBL information within the country, providing a valuable baseline for future research exploring the association between the gene and targeted diseases.

Association of MBL2 gene polymorphisms and MBL levels with dilated cardiomyopathy in a Chinese Han population.

BACKGROUND: It has been reported that Mannose-binding lectin 2 (MBL2) gene polymorphisms and expression levels are related to dilated cardiomyopathy (DCM). This study aimed to investigate the potential association between MBL2 gene polymorphisms and the pathogenesis of DCM. METHODS: Five single nucleotide polymorphisms (SNPs) of the MBL2 gene were genotyped in 440 DCM patients and 532 controls in Southwest China. A luciferase reporter assay was used to detect the transcriptional activity the different genotypes. MBL serum levels, left ventricle ejection fraction (LVEF) and lower left ventricular end-diastolic diameter (LVEDD) were measured. RESULTS: The rs11003125 C allele increased the transcriptional activity of the MBL2 promoter compared with the rs11003125 G allele. The rs11003125 CC carriers had higher MBL serum levels, LVEF and LVEDD than the rs11003125 CG and GG carriers. CONCLUSIONS: Our study first revealed that MBL2 polymorphisms and serum MBL levels were associated with DCM. Allele C in rs11003125 of MBL2 may upregulate the expression levels of MBL. High serum MBL levels may be a protective factor in DCM pathogenesis.

Genetic determinants of complement activation in the general population.

Complement is a fundamental innate immune response component. Its alterations are associated with severe systemic diseases. To illuminate the complement's genetic underpinnings, we conduct genome-wide association studies of the functional activity of the classical (CP), lectin (LP), and alternative (AP) complement pathways in the Cooperative Health Research in South Tyrol study (n = 4,990). We identify seven loci, encompassing 13 independent, pathway-specific variants located in or near complement genes (CFHR4, C7, C2, MBL2) and non-complement genes (PDE3A, TNXB, ABO), explaining up to 74% of complement pathways' genetic heritability and implicating long-range haplotypes associated with LP at MBL2. Two-sample Mendelian randomization analyses, supported by transcriptome- and proteome-wide colocalization, confirm known causal pathways, establish within-complement feedback loops, and implicate causality of ABO on LP and of CFHR2 and C7 on AP. LP causally influences collectin-11 and KAAG1 levels and the risk of mouth ulcers. These results build a comprehensive resource to investigate the role of complement in human health.

[Polymorphisms associated with dental caries in pediatric populations: a systematic review]. / Polimorfismos asociados a la caries dental en poblaciones pediátricas: una revisión sistemática.

Single nucleotide polymorphisms (SNPs) have been reported to play an important role in the etiology of dental caries. The aim of this research was, through a systematic review, to identify SNPs recently associated with dental caries in pediatric populations. We included studies performed in humans up to 18 years of age that evaluated the relationship between SNPs and dental caries from 2017 to 2022. Articles that covered other study variables were excluded. PubMed, ScienceDirect and Web of Science were used to search for information and the included articles were evaluated with one of the Joanna Briggs Institute's tools. Twenty-five articles were selected, 60% of which were given high methodological quality. A total of 10,743 research subjects, ranging in age from 20 months to 17 years, participated in the study. The SNPs considered risk factors were identified in the genes miRNA202, VDR, AMELX, TUFT1, KLK4, MBL2, ENAM, DEFB1, HLA-DRB1, TAS1R1, DSPP, RUNX2 and MMP13; those considered protective factors were identified in the genes MMP20, AMBN, MMP9, TIMP2, TNF-α, VDR, IL1B, ENAM and HLA-DRB1. This systematic review presents the genetic polymorphisms that are associated with the etiology of caries in children and adolescents, some of which act as risk factors and others as protective factors against the disease.

Se ha reportado que los polimorfismos de nucleótido único (SNPs) juegan un papel importante en la etiología de la caries dental. El objetivo de esta investigación fue, a través de una revisión sistemática, identificar los SNPs asociados recientemente a la caries dental en poblaciones pediátricas. Se incluyeron estudios realizados en humanos de hasta 18 años de edad que evaluaron la relación entre los SNPs y la caries dental, publicados desde el 2017 hasta el 2022. Se excluyeron los artículos que abarcaron otras variables de estudio. PubMed, ScienceDirect y Web of Science se utilizaron para la búsqueda de información y los artículos incluidos fueron evaluados con una de las herramientas del Instituto Joanna Briggs. Fueron seleccionados 25 artículos, al 60% de ellos se le otorgó calidad metodológica alta. En total participaron 10,743 sujetos de invetigación, cuyas edades variaron de 20 meses a 17 años. Los SNPs considerados factores de riesgo fueron identificados en los genes miRNA202, VDR, AMELX, TUFT1, KLK4, MBL2, ENAM, DEFB1, HLA-DRB1, TAS1R1, DSPP, RUNX2 y MMP13, los considerados factores de protección se identificaron en los genes MMP20, AMBN, MMP9, TIMP2, TNF-α, VDR, IL1B, ENAM y HLA-DRB1. Esta revisión sistemática expone los polimorfismos genéticos que se encuentran asociados a la etiología de la caries en niños y adolescentes, algunos de los cuales actúan como factores de riesgo y otros como factores de protección ante la enfermedad.

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

BACKGROUND: The physiological interactions of MBL suggest its contribution towards the pathogenesis of COPD. OBJECTIVE: The present case-control study was undertaken to elucidate the role of MBL with COPD risk and clinical outcomes in north Indian cohort. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

A likely association between low mannan-binding lectin level and brain fog onset in long COVID patients.

Brain fog can be described as a constellation of new-onset neuropsychiatric sequelae in the post-acute phase of COVID-19 (long COVID). The symptoms include inattention, short-term memory loss, and reduced mental acuity, which may undermine cognition, concentration, and sleep. This cognitive impairment, persisting for weeks or months after the acute phase of SARS-CoV-2 infection, can significantly impact on daily activities and the quality of life. An important role for the complement system (C) in the pathogenesis of COVID-19 has emerged since the beginning of pandemic outbreak. A number of pathophysiological characteristics including microangiopathy and myocarditis have been attributed to dysregulated C activation due to SARS-CoV-2 infection. Mannan-binding lectin (MBL), the first recognition subcomponent of the C lectin pathway, has been shown to bind to glycosylated SARS-CoV-2 spike protein, genetic variants of MBL2 are suggested to have an association with severe COVID-19 manifestations requiring hospitalization. In the present study, we evaluated MBL activity (lectin pathway activation) and levels in the sera of a cohort of COVID-19 patients, presenting brain fog or only hyposmia/hypogeusia as persistent symptoms, and compared them with healthy volunteers. We found significantly lower levels of MBL and lectin pathway activity in the sera of patients experiencing brain fog as compared to recovered COVID-19 patients without brain fog. Our data indicate that long COVID-associated brain fog can be listed among the variegate manifestations of increased susceptibility to infections and diseases contributed by MBL deficiency.

The MBL2 genotype relates to COVID-19 severity and may help to select the optimal therapy.

OBJECTIVES: Sars-CoV-2 acute infection is clinically heterogeneous, ranging from asymptomatic cases to patients with a severe, systemic clinical course. Among the involved factors age and preexisting morbidities play a major role; genetic host susceptibility contributes to modulating the clinical expression and outcome of the disease. Mannose-binding lectin is an acute-phase protein that activates the lectin-complement pathway, promotes opsonophagocytosis and modulates inflammation, and is involved in several bacterial and viral infections in humans. Understanding its role in Sars-CoV-2 infection could help select a better therapy. METHODS: We studied MBL2 haplotypes in 419 patients with acute COVID-19 in comparison to the general population and related the haplotypes to clinical and laboratory markers of severity. RESULTS: We recorded an enhanced frequency of MBL2 null alleles in patients with severe acute COVID-19. The homozygous null genotypes were significantly more frequent in patients with advanced WHO score 4-7 (OR of about 4) and related to more severe inflammation, neutrophilia, and lymphopenia. CONCLUSIONS: Subjects with a defective MBL2 genotype (i.e., 0/0) are predisposed to a more severe acute Sars-CoV-2 infection; they may benefit from early replacement therapy with recombinant MBL. Furthermore, a subset of subjects with the A/A MBL genotype develop a relevant increase of serum MBL during the early phases of the disease and develop a more severe pulmonary disease; in these patients, the targeting of the complement may help. Therefore, COVID-19 patients should be tested at hospitalization with serum MBL analysis and MBL2 genotype, to define the optimal therapy.

Polymorphisms in the MBL2 gene are associated with the plasma levels of MBL and the cytokines IL-6 and TNF-α in severe COVID-19.

Introduction: Mannose-binding lectin (MBL) promotes opsonization, favoring phagocytosis and activation of the complement system in response to different microorganisms, and may influence the synthesis of inflammatory cytokines. This study investigated the association of MBL2 gene polymorphisms with the plasma levels of MBL and inflammatory cytokines in COVID-19. Methods: Blood samples from 385 individuals (208 with acute COVID-19 and 117 post-COVID-19) were subjected to real-time PCR genotyping. Plasma measurements of MBL and cytokines were performed by enzyme-linked immunosorbent assay and flow cytometry, respectively. Results: The frequencies of the polymorphic MBL2 genotype (OO) and allele (O) were higher in patients with severe COVID-19 (p< 0.05). The polymorphic genotypes (AO and OO) were associated with lower MBL levels (p< 0.05). IL-6 and TNF-α were higher in patients with low MBL and severe COVID-19 (p< 0.05). No association of polymorphisms, MBL levels, or cytokine levels with long COVID was observed. Discussion: The results suggest that, besides MBL2 polymorphisms promoting a reduction in MBL levels and therefore in its function, they may also contribute to the development of a more intense inflammatory process responsible for the severity of COVID-19.

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

BACKGROUND: 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. METHODS AND RESULTS: 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). CONCLUSION: These findings suggest that codon 54 polymorphism in the MBL2 gene exon-1 region can be associated with the symptomatic course of COVID-19.

Complement lectin pathway activation is associated with COVID-19 disease severity, independent of MBL2 genotype subgroups.

Introduction: While complement is a contributor to disease severity in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, all three complement pathways might be activated by the virus. Lectin pathway activation occurs through different pattern recognition molecules, including mannan binding lectin (MBL), a protein shown to interact with SARS-CoV-2 proteins. However, the exact role of lectin pathway activation and its key pattern recognition molecule MBL in COVID-19 is still not fully understood. Methods: We therefore investigated activation of the lectin pathway in two independent cohorts of SARS-CoV-2 infected patients, while also analysing MBL protein levels and potential effects of the six major single nucleotide polymorphisms (SNPs) found in the MBL2 gene on COVID-19 severity and outcome. Results: We show that the lectin pathway is activated in acute COVID-19, indicated by the correlation between complement activation product levels of the MASP-1/C1-INH complex (p=0.0011) and C4d (p<0.0001) and COVID-19 severity. Despite this, genetic variations in MBL2 are not associated with susceptibility to SARS-CoV-2 infection or disease outcomes such as mortality and the development of Long COVID. Conclusion: In conclusion, activation of the MBL-LP only plays a minor role in COVID-19 pathogenesis, since no clinically meaningful, consistent associations with disease outcomes were noted.

MBL2 gene variants and susceptibility to meningitis in Egyptian patients.

BACKGROUND: Meningitis 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. OBJECTIVE: The 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 METHODS: This case-control study, included 53 patients and 50 sex and age matched controls. MBL2 genotyping was done using Sanger sequencing. RESULTS: The 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). CONCLUSION: The 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.