High production MBL2 polymorphisms protect against COVID-19 complications in critically ill patients: A retrospective cohort study

Mannose-binding lectin (MBL) binds to SARS-CoV-2, inhibits infection of susceptible cells, and activates the complement system via the lectin pathway. In this study, we investigated the association of MBL2 polymorphisms with the risk of hospitalization and clinical worsening in patients with COVID-19. A total of 550 patients with COVID-19 were included (94 non-hospitalized and 456 hospitalized). Polymorphisms in MBL2 exon 1 (codons 52, 54 and 57) and promoter region (-550, -221, and +4) were determined by real-time PCR. MBL and complement proteins were measured by Luminex. A higher frequency of the H/H genotype and the HYPA haplotype was observed in non-hospitalized patients when compared to hospitalized. In addition, critically ill patients carrying haplotypes associated with high MBL levels (HYPA/HYPA + HYPA/LYPA + HYPA/LYQA + LYPA/LYQA + LYPA/LYPA + LYQA/LYQA + LXPA/HYPA + LXPA/LYQA + LXPA/LYPA) were protected against lower oxygen saturation levels (P = 0.02), use of invasive ventilation use (P = 0.02, OR 0.38), and shock (P = 0.01, OR 0.40), independent of other potential confounders adjusted by multivariate analysis. Our results suggest that variants in MBL2 associated with high MBL levels may play a protective role in the clinical course of COVID-19.

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.

Circulating mannose-binding lectin concentration in patients with stable coronary artery disease is associated with heart failure and renal function

BACKGROUND

Mannose-binding lectin (MBL) has been associated with cardiovascular disease and its complications, the progression of diabetic nephropathy, and complement-mediated renal interstitial injury. However, the relationship between plasma MBL concentration with both heart failure and renal function is unclear. In this study, we examined associations of plasma MBL with both renal function and heart failure in patients with stable coronary artery disease (CAD).

METHODS

We enrolled 348 consecutive stable CAD patients and used ELISA to evaluate plasma concentrations of MBL. Renal function was classified into KDIGO G1, G2 and G3a-G4 groups according to the eGFR of ≥ 90, 60-89 and 15-59, ml/min/1.73 m2, respectively. Patients with a left ventricular ejection fraction (LVEF) ≤ 40 % were classified to have heart failure.

RESULTS

A significant positive association was found between MBL with diabetes mellitus, current smoker, blood urea nitrogen, creatinine, and brain natriuretic peptide, and a significant negative association was found between MBL with eGFR and LVEF. KDIGO stage G3a-G4 and heart failure increased along with tertiles of MBL (p for trend < 0.05). Multivariate analysis showed that compared to the patients with a low MBL concentration, the odds ratios of having KDIGO stage G3a-G4 were 1.89 (1.01-3.55) times and 2.37 (1.25-4.59) times higher for those with medium and high MBL concentrations. Furthermore, compared to the patients with a low MBL concentration, the OR of having heart failure were 1.97 (1.01-3.93) times higher for those with high MBL concentrations. Moreover, multivariate analysis showed an independent association between plasma MBL concentration with both KDIGO stage G3a-G4 and heart failure (LVEF < 40 %). In addition, the effect of MBL on both LVEF and eGFR was confirmed by structural equation model analysis.

CONCLUSION

There are associations between circulating MBL concentration with both heart failure and renal function in stable CAD patients, suggesting that increased plasma MBL may contribute to the pathogenesis of both chronic kidney disease and heart failure.

Plant lectins: Classical molecules with emerging roles in stress tolerance

Biotic and abiotic stresses impose adverse effects on plant's development, growth, and production. For the past many years, researchers are trying to understand the stress induced responses in plants and decipher strategies to produce stress tolerant crops. It has been demonstrated that molecular networks encompassing an array of genes and functional proteins play a key role in generating responses to combat different stresses. Newly, there has been a resurgence of interest to explore the role of lectins in modulating various biological responses in plants. Lectins are naturally occurring proteins that form reversible linkages with their respective glycoconjugates. To date, several plant lectins have been recognized and functionally characterized. However, their involvement in stress tolerance is yet to be comprehensively analyzed in greater detail. The availability of biological resources, modern experimental tools, and assay systems has provided a fresh impetus for plant lectin research. Against this backdrop, the present review provides background information on plant lectins and recent knowledge on their crosstalks with other regulatory mechanisms, which play a remarkable role in plant stress amelioration. It also highlights their versatile role and suggests that adding more information to this under-explored area will usher in a new era of crop improvement.

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.

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.-66 C>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.

MBL2 polymorphism may be a protective factor of autoimmune thyroid disease susceptibility

Genetic susceptibility is an essential pathogenetic mechanism in autoimmune thyroid disease (AITD). MBL2 gene polymorphisms have been shown to play a vital role in the pathogenesis of multiple autoimmune disorders, but its contribution to AITD is unclear. The aim of this study was to assess the linkage between MBL2 gene polymorphisms and AITD susceptibility in a Chinese Han population. One thousand seven hundred sixty seven subjects consisting of 965 AITD patients and 802 controls from a Chinese Han population were enrolled in the case-control study. Four common single-nucleotide polymorphisms (SNPs) in the MBL2 gene were tested using high-throughput sequencing technology for sequence-based SNP genotyping. The allele and genotype distribution results showed that the minor alleles of rs198266, rs10824793, and rs4935046 were significantly lower in Hashimoto's thyroiditis (HT) patients than in healthy controls. In further genetic model analysis, the dominant models of rs1982266, rs10824793, and rs4935046 for MBL2 in the AITD group exhibited a lower risk of morbidity. Finally, we discovered that haplotype AAGC was associated with Graves' disease (GD), while AGC was associated with HT. Our study provides strong evidence for a genetic correlation between MBL2 and AITD, and the polymorphism of the MBL2 gene may be a protective factor for AITD, especially for HT. These findings can advance our understanding of the etiology of AITD, as well as provide guidance for prevention and intervention toward AITD.

Nanometer- and angstrom-scale characteristics that modulate complement responses to nanoparticles

The contribution of the complement system to non-specific host defence and maintenance of homeostasis is well appreciated. Many particulate systems trigger complement activation but the underlying mechanisms are still poorly understood. Activation of the complement cascade could lead to particle opsonisation by the cleavage products of the third complement protein and might promote inflammatory reactions. Antibody binding in a controlled manner and/or sensing of particles by the complement pattern-recognition molecules such as C1q and mannose-binding lectin can trigger complement activation. Particle curvature and spacing arrangement/periodicity of surface functional groups/ligands are two important parameters that modulate complement responses through multivalent engagement with and conformational regulation of surface-bound antibodies and complement pattern-recognition molecules. Thus, a better fundamental understanding of nanometer- and angstrom-scale parameters that modulate particle interaction with antibodies and complement proteins could portend new possibilities for engineering of particulate drug carriers and biomedical platforms with tuneable complement responses and is discussed here.

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.

Complement Genetics for the Practicing Allergist Immunologist: Focus on Complement Deficiencies

Complement deficiencies have been considered to be rare for many decades, but this assumption is changing year by year. Recognition of these conditions significantly increases thanks to the availability of different testing approaches and due to clinical awareness. Furthermore, sequencing technologies (including Sanger sequencing, targeted gene panels, and whole exome/genome sequencing) may facilitate the identification of the underlying disease-causing genetic background. On the other hand, functional characterization of the identified possibly pathogenic variations and performing family studies, as illustrated by some of our cases, remain similarly important to establish a precise clinical diagnosis facilitating the most appropriate management. Here, we present 4 illustrative cases with complement deficiencies of diverse etiologies and also provide an educative, step-by-step description on how to identify the underlying cause of complement deficiency based on the results of complement laboratory testing.

Influence of the presence of mannose-binding lectin polymorphisms on the occurrence of leishmaniasis: a systematic review and meta-analysis

Background

Leishmaniasis is caused by an intracellular protozoan of the Leishmania genus. Mannose-binding lectin (MBL) is a serum complement protein and recognizes lipoprotein antigens in protozoa and the bacterial plasma membrane. Nucleotide variants in the promoter region and exon 1 of the MBL gene can influence its expression or change its molecular structure.

Objective

To evaluate, through a systematic review, case-control studies of the genetic association of variants in the MBL2 gene and the risk of developing leishmaniasis.

Methods

This review carried out a search in PubMed, Science Direct, Cochrane Library, Scopus and Lilacs databases for case-control publications with six polymorphisms in the mannose-binding Lectin gene. The following strategy was used: P = Patients at risk of leishmaniasis; I = Presence of polymorphisms; C = Absence of polymorphisms; O = Occurrence of leishmaniasis. Four case/control studies consisting of 791 patients with leishmaniasis and 967 healthy subjects (Control) are included in this meta-analysis. The association of variants in the mannose-binding Lectin gene and leishmaniasis under the allelic genetic model, -550 (Hvs. L), -221 (X vs. Y), +4 (Q vs. P), CD52 (A vs. D), CD54 (A vs. B), CD57 (A vs. C) and A/O genotype (A vs. O) was evaluated. International Prospective Register of Systematic Reviews (PROSPERO): CRD42020201755.

Results

The meta-analysis results for any allelic genetic model showed no significant association for the variants within the promoter, the untranslated region, and exon 1, as well as for the wild-type A allele and mutant allele O with leishmaniasis.

Study limitations

Caution should be exercised when interpreting these results, as they are based on a few studies, which show divergent results when analyzed separately.

Conclusions

This meta-analysis showed a non-significant association between the rs11003125, rs7096206, rs7095891, rs5030737, rs1800450, and rs1800451 polymorphisms of the Mannose-binding Lectin gene and leishmaniasis in any allelic and heterogeneous evaluation.

Mannose-binding lectin levels and MBL2 gene polymorphisms are associated to dengue infection in Brazilian children at the early ages

BACKGROUND

The mannose-binding lectin (MBL) plays an important role in innate immunity. Genetically determined variations in serum levels of MBL may influence the susceptibility and clinical outcome of dengue infection in early life.

METHODS

We investigated MBL2 gene polymorphisms and serum levels of MBL (total and functional) in children with asymptomatic (n=17) and symptomatic (n=29), primary dengue infections, and age-matched uninfected children (n=84) enrolled in a Brazilian dengue birth cohort. Polymorphisms of the MBL2 gene were assessed by RT-PCR, while ELISA were used to quantify serum levels of MBL.

RESULTS

We found that the X allele and YX genotype in the MBL2 were more frequent in dengue cases than controls. Likewise, the LXPA haplotype was exclusively found in dengue cases, thus probably related to dengue infection in our setting. Moreover, we found a higher frequency of the O allele and AO genotype in control group. Serum levels of total and functional MBL were higher in dengue naïve infants than dengue cases.

CONCLUSIONS

MBL2 variants related to lower production of serum MBL were associated to dengue infection in infants, while intermediate to high levels of total and functional serum MBL were associated with protection. These findings highlight the role of MBL2 variants and serum levels of MBL in the susceptibility to dengue disease at early ages.

Bioinformatics analysis of structures and ligand-bindings of predicted zymogen granule protein observed on Bali cattle (Bos javanicus) saliva

Objective

Previously, we have shown that predicted zymogen granule protein 16 homolog B (P-G3MZ19) existed in Bali cattle (Bos javanicus) saliva. It was suggested that P-G3MZ19 is a member of the mannose-binding lectin family that plays an essential role in innate immunity. In the present study, we aimed to analyze the structure and ligand-binding of P-3MZ19 in Bali cattle saliva.

Materials and Methods

Saliva of four adult healthy Bali cattle was collected, lyophilized, and subjected to two-dimensional (2-D) gel electrophoresis. The target spot of around 17 kDa related to P-G3MZ19 was excised for matrix-assisted laser desorption ionization time-of-flight mass spectrometer/time-of-flight mass spectrometer mass spectrometry analysis and sequencing. The structure and the ligand-binding of P-3MZ19 were analyzed using bioinformatics software programs published elsewhere.

Results

Based on Iterative Threading ASSEmbly Refinement the 3D model of P-G3MZ19 was suggested to have similarities to exo-alpha-sialidase (EC 3.2.1.18); while its ligand-binding sites consisted of seven residues, i.e., 25aa-26aa (Gly-Gly), 95aa (Phe), 138aa (Tyr), 140aa (Leu), 141aa (Gly), and 143aa (Thr).

Conclusion

The structure of P-G3MZ19 of Bali cattle saliva and its ligand-binding sites have been successfully determined by using bioinformatics techniques. The biological and immunological roles of the peptide are currently under investigation based on P-G3MZ19 synthetic peptides.

Association of mannose-binding lectin, ficolin-2 and immunoglobulin concentrations with future exacerbations in patients with chronic obstructive pulmonary disease: secondary analysis of the randomized controlled REDUCE trial

BACKGROUND

The innate and adaptive immune system is involved in the airway inflammation associated with acute exacerbations in patients with chronic obstructive pulmonary disease (COPD). We evaluated the association of mannose-binding lectin (MBL), immunoglobulin (Ig) and ficolin-2 concentrations with COPD exacerbations and according to the glucocorticoid treatment duration for an index exacerbation.

METHODS

Post-hoc analysis of the randomized, double-blind, placebo-controlled REDUCE trial of 5 vs. 14 days of glucocorticoid treatment for an index exacerbation. MBL, ficolin-2 and total IgG/IgA and subclass concentrations were determined in stored samples drawn (n = 178) 30 days after the index exacerbation and associated with the risk of re-exacerbation during a 180-day follow-up period.

RESULTS

IgG and subclass concentrations were significantly lower after 14 days vs. 5 days of glucocorticoid treatment. Patients with higher MBL concentrations were more likely to suffer from a future exacerbation (multivariable hazard ratio 1.03 per 200 ng/ml increase (95% confidence interval (CI) 1.00-1.06), p = 0.048), whereas ficolin-2 and IgG deficiency were not associated. The risk was most pronounced in patients with high MBL concentrations, IgG deficiency and 14 days of glucocorticoid treatment pointing towards an interactive effect of MBL and IgG deficiency in the presence of prolonged glucocorticoid treatment duration [Relative excess risk due to interaction 2.13 (95% CI - 0.41-4.66, p = 0.10)]. IgG concentrations were significantly lower in patients with frequent re-exacerbations (IgG, 7.81 g/L vs. 9.53 g/L, p = 0.03).

CONCLUSIONS

MBL modified the short-term exacerbation risk after a recent acute exacerbation of COPD, particularly in the setting of concurrent IgG deficiency and recent prolonged systemic glucocorticoid treatment. Ficolin-2 did not emerge as a predictor of a future exacerbation risk.

Predictive and Prognostic Value of Ascitic Fluid Mannose Binding Lectin in Patients with Spontaneous Bacterial Peritonitis

BACKGROUND

Spontaneous bacterial peritonitis is a common bacterial infection of ascitic fluid, mainly in ascites due to liver cirrhosis. Mannose-binding lectin (MBL) can activate phagocytosis and the complement system. Spontaneous bacterial peritonitis was detected to be higher in MBL deficiency. This study aimed to assess ascitic fluid MBL in liver cirrhosis and spontaneous bacterial peritonitis.

METHODS

Ninety patients with cirrhotic ascites were included. Forty five of them had SBP. Child- Pugh score, Model for End Stage Liver Disease (MELD) and its update (uMELD) scores were used to assess the severity of liver cirrhosis. Ascitic fluid samples were obtained for differentiation of leucocytic count, estimation of albumin, protein, glucose, and serum-ascitic albumin gradient. Ascitic fluid levels of MBL were measured for all patients. SBP was documented if polymorphonuclear leucocytic count ≥250/mm in ascitic fluid.

RESULTS

Ascitic fluid MBL level was significantly lower in patients with SBP. MBL had a significant negative correlation with ascitic total leukocytic count (TLC), also with serum creatinine, bilirubin, PT, INR and MELD score among SBP patients. However, it had a significant positive correlation with ascitic protein and with platelets. According to multivariate analysis, fever, TLC, platelets, creatinine, MBL, glucose and polymorphs were independent predictors for SBP development.

CONCLUSION

Ascitic fluid MBL could be a good predictive and prognostic marker in patients with cirrhosis and spontaneous bacterial peritonitis.

Mannose-binding lectin and risk of infections in type 2 diabetes: A Danish cohort study

AIMS

In individuals at increased risk of infections, e.g., patients with type 2 diabetes, low MBL may have detrimental effects. We used the Mendelian randomization principle to examine whether genetically low MBL is a risk factor for developing infections in patients with type 2 diabetes.

METHODS

Serum MBL (n = 7305) and MBL genotype (n = 3043) were determined in a nationwide cohort of patients with new type 2 diabetes and up to 8 years follow-up for hospital-treated infections and community-based antimicrobial prescriptions. The associations were examined in spline and Cox regression analyses.

RESULTS

1140 patients (16%) were hospitalized with an infection and 5077 patients (70%) redeemed an antimicrobial prescription. For low (≤100 μg/L) versus intermediate (101-1000 μg/L) serum MBL concentration, the adjusted hazard ratios (aHRs) were 1.13(95% confidence interval, 0.96-1.33) for any hospital-treated infections and 1.19(1.01-1.41) for bacterial infections. Low MBL expression genotype was not associated with risk of any hospital-treated infections except for diarrheal diseases (aHR 2.23[1.04-4.80]). Low MBL expression genotype, but not low serum MBL, was associated with increased risk for antimicrobial prescriptions (aHR 1.18[1.04-2.34] and antibacterial prescriptions 1.20[1.05-1.36]).

CONCLUSIONS

Low MBL is a weak causal risk factor for developing infections in patients with type 2 diabetes.

Plasma-derived and recombinant C1 esterase inhibitor: Binding profiles and neuroprotective properties in brain ischemia/reperfusion injury

C1 esterase inhibitor (C1INH) is known to exert its inhibitory effect by binding to several target proteases of the contact and complement systems. One of C1INH's targets comprise mannose-binding lectin (MBL), a critical player in post-stroke pathophysiology. We therefore explored the effects of recombinant human (rh) and plasma derived (pd) C1INH in C57BL/6J mice subjected to transient occlusion of the middle cerebral artery (tMCAo), receiving 15U/mouse of pd or rhC1INH intravenously, at reperfusion. We analyzed the compounds' (i)neuroprotective effects, (ii) plasma presence, (iii)effects on circulating and brain MBL, (iv)time course of endothelial deposition, and (v) effects on the formation of active complement products. rhC1INH-treated mice had neuroprotective effects, including reduced behavioral deficits and neuronal loss, associated with decreased MBL brain deposition and decreased formation of complement C4b active fragments. In contrast, pdC1INH did not show these neuroprotective effects despite its longer plasma residence time. We also analyzed the response to tMCAo in C1INH-deficient mice, observing a poorer ischemic outcome compared to the wild type mice, which could be partially prevented by rhC1INH administration. In conclusion, we show that rhC1INH exhibits stronger neuroprotective effects than the corresponding plasma-derived protein after experimental ischemia/reperfusion injury in the brain, placing it as a promising drug for stroke. Differential effects are likely related to more effective MBL inhibition which further confirms it as a useful pharmacological target for stroke.

Increased serum bactericidal activity of autologous serum in C2 deficiency after vaccination against Haemophilus influenzae type b, and further support for an MBL-dependent C2 bypass mechanism

Deficiencies of C2 and other components of the classical pathway of complement are associated with increased risk of infections with encapsulated bacteria, such as Haemophilus (H.) influenzae. Defense against H. influenzae is dependent on specific antibodies and complement, which mediate serum bactericidal activity (SBA) and opsonization. Due to lack of normal classical and lectin complement pathway function in C2 deficiency (C2D), SBA would have to depend either on the alternative pathway or on C2 bypass mechanisms. Here we studied SBA against H. influenzae type b (Hib) before and after vaccination in a group of C2-deficient persons, as the bactericidal capacity of antibodies in autologous complement in relation to vaccination has not been investigated at group level in C2D. Sera from 22 persons with C2D and 26 healthy controls were available. Out of these, 18 persons with C2D and all controls had been vaccinated with Act-HIB®. SBA against Hib bacteria was analyzed with autologous serum as the only complement source. Antibodies to Hib capsular polysaccharide had been analyzed previously. Concentrations of mannose-binding lectin (MBL) and other complement components were measured in serum. SBA of both C2-deficient persons and controls was significantly more efficient after vaccination (p = 0.002 and p < 0.0001, respectively). After vaccination, all but two C2-deficient sera and one control serum showed sufficient SBA (<50% surviving bacteria). Before vaccination, SBA of C2-deficient sera was negatively correlated to serum concentrations of MBL (lower proportion of surviving bacteria with higher MBL concentration; r = -0.55, p = 0.008). After vaccination, SBA of C2-deficient sera was negatively correlated to serum concentrations of IgG Hib antibodies (r = -0.56, p = 0.01). In conclusion, SBA against Hib in autologous serum is increased after vaccination in persons with C2D. In unvaccinated C2-deficient persons SBA was correlated to MBL concentration, providing further support for an MBL-dependent C2 bypass mechanism operating in C2D.

Effect of Glomerular Mannose-Binding Lectin Deposition on the Prognosis of Idiopathic Membranous Nephropathy

OBJECTIVE

Co-deposition of mannose-binding lectin (MBL) and IgG4 anti-phospholipase A2 receptor (anti-PLA2R) autoantibodies under subepithelial cells has been observed in patients with idiopathic membranous nephropathy (iMN), but the relationships of MBL deposition to iMN severity and progression remain unclear.

METHODS

Patients diagnosed with iMN who underwent renal puncture were enrolled and followed up for a median of 17 months (interquartile range [IQR], 9-25 months). Serum anti-PLA2R and anti-thrombospondin type-1 domain-containing 7A antibodies and MBL were detected by ELISA. Glomerular MBL and anti-PLA2R antibodies were detected by immunofluorescence. Proteinuria remission, including complete remission (CR), was defined as a clinical event. Clinicopathological characteristics and kidney outcomes were compared between patients with and without MBL deposition.

RESULTS

In 67 prevalent patients with biopsy-proven iMN, serum anti-PLA2R antibodies and anti-THSD7A antibodies were present in 37 (55.3%) and 1 (1.4%) patient with iMN. The positivity of glomerular MBL deposition and tissue anti-PLA2R antibody was 53 (79.1%) and 49 (73.1%), respectively. No significant difference was found between the MBL-positive and negative groups in the albumin level (26.5 ± 6.6 and 28.6 ± 6.1 g/L), eGFR (104.8 ± 17.4 and 114.6 ± 16.1 mL/min/1.73 m2), 24-h proteinuria (5.35 and 4.25 g/day), or serum MBL level corrected by serum Cr 4.92 (IQR, 0.86, 8.90) and 2.28 (IQR, 0.4, 5.62). In a Cox proportional hazards regression model adjusted for sex, age, systolic blood pressure, eGFR, immunosuppressive agent use, 24-h proteinuria, and anti-PLA2R antibody concentration, glomerular MBL deposition was independently associated with ICR of proteinuria (HR, 6.31; 95% CI, 1.1-36.1; p = 0.039).

CONCLUSIONS

The MBL pathway of complement activation is commonly initiated in patients with iMN, and patients with MBL deposition reach ICR faster than patients without MBL deposition.

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

Background

Mannose-binding lectin (MBL) mediates the innate immune response either through direct opsonisation of microorganisms or through activation of the complement system. There are conflicting data whether MBL deficiency leads to increased susceptibility to infections or not. The aim of this study was to determine if low levels of mannose-binding lectin (MBL) predict sepsis development, sepsis severity and outcome from severe sepsis or septic shock.

Method

Patients aged 18 years or more with documented sepsis within 24 h after admission to the intensive care unit were included if they had participated in a health survey and donated blood samples prior to the sepsis event. A subset of these patients had stored plasma also from the acute phase. Two matched referents free of known sepsis were selected for each case. Plasma levels MBL were determined in stored samples from health surveys (baseline) and from ICU admission (acute phase). The association between MBL and sepsis, sepsis severity and in-hospital mortality were determined with 1300 ng/mL as cut-off for low levels.

Results

We identified 148 patients (61.5% women) with a first-time sepsis event 6.5 years (median with IQR 7.7) after participation in a health survey, of which 122 also had samples from the acute septic phase. Both high MBL levels in the acute phase (odds ratio [95% confidence interval]) (2.84 [1.20-6.26]), and an increase in MBL levels from baseline to the acute phase (3.76 [1.21-11.72]) were associated with increased risk for in-hospital death in women, but not in men (0.47 [0.11-2.06]). Baseline MBL levels did not predict future sepsis, sepsis severity or in-hospital mortality.

Conclusions

An increase from baseline to the acute phase as well as high levels in the acute phase associated with an unfavourable outcome in women.

Mannose-binding lectin gene polymorphisms in the East Siberia and Russian Arctic populations

Mannose-binding lectin (MBL) encoded by MBL2 gene is a protein with the ability to form carbohydrate complexes with microbial wall promoting their subsequent elimination. Genetically determined levels of MBL can modify the risk and clinical characteristics of many infectious diseases. The frequency of MBL2 genotypes exhibits significant population differences. The data on the distribution of MBL2 genotypes among the aborigines of the Russian Arctic territories have not yet been published. A total of 880 specimens of dried blood spots of the newborns were genotyped. The newborns represented four populations: Nenets, Dolgan-Nganasans, Mixed aboriginal population, and Russians (Caucasians, Krasnoyarsk). Six polymorphisms of the MBL2 gene were studied: rs11003125, rs7096206, rs7095891, rs5030737, rs1800450, and rs1800451. The frequency of the combined rare O allele (composed of the coding region variants rs5030737, rs1800450, and rs1800451) in the homozygous state was significantly higher in Russians: 10% vs 2% in Nenets and 1% in Dolgan-Nganosans (p < 0.001 for Russians vs other populations). The frequency of the high-producing haplotype (HYPA) was 35.4% in the Russian newborns, in keeping with European populations (27-33%); 64% for Nenets and 56% for Dolgan-Nganasans, similar to the estimates obtained for Eskimos and North Amerinds (64-81%). Our study results are in line with the hypothesis that human evolution has been moving in the direction of accumulation of the genotypes associated with low activity of the lectin complement activation pathway because of the prevalence of some intracellular infections such as tuberculosis, whereby low MBL activity may have a protective effect.

Molecular Pathogenesis, Immunopathogenesis and Novel Therapeutic Strategy Against COVID-19

The coronavirus disease 2019 (COVID-19), is a highly contagious transmittable disease caused by a recently discovered coronavirus, pathogenic SARS-CoV-2. Followed by the emergence of highly pathogenic coronaviruses in 2003 SARS-CoV, in 2012 MERS-CoV, now in 2019 pathogenic SARS-CoV-2, is associated with a global “pandemic” situation. In humans, the effects of these viruses are correlated with viral pneumonia, severe respiratory tract infections. It is believed that interaction between angiotensin converting enzyme 2 (ACE2) cell receptor and viral Spike protein mediates the coronavirus entry into human respiratory epithelial cells and establishes the host tropism. ACE2 receptor is highly expressed in airway epithelial cells. Along with viral-receptor interaction, proteolytic cleavability of S protein has been considered as the determinant of disease severity. Several studies highlight the occurrence of impaired host immune response and expression of excessive inflammatory response especially cytokines against viral infection. The mechanisms of SARS-CoV-2 induced acute lung injury are still undefined; however, the term cytokine storm has now been recognized to be closely associated with COVID-19. The levels of inflammatory mediators from cytokine storm cause damage to the host cells. In particular, the proinflammatory cytokine IL-6 appears to be the key mediator in early phase of virus-receptor interaction; however, secreted IL-6 might not be representative of lung inflammation. Understanding the cellular, and molecular factors involved in immune dysregulation and the high virulence capacity of COVID-19 will help in potential targeted therapy against it. “Drug repurposing” and “molecular docking analysis” is considered as an attractive alternative approach in analyzing suitable drug candidates to combat SARS-CoV-2 infection. Globally, extensive research is in progress to discover a new vaccine for novel COVID-19. Moreover, our review mainly focuses on the most state-of-the-art therapeutic approach mediated by “Mannose-binding lectin (MBL).” One of the most significant molecules of innate immunity is MBL. It plays a major role in the activation of the complement system as an ante-antibody prior to the response of any particular antibody. Recombinant human MBL can be used as immunomodulators against SARS-CoV-2.

Association between polymorphisms in mannose-binding lectin 2 gene with pulmonary tuberculosis susceptibility

Background

Mannose-binding lectin (MBL2) is considered to play a role in the human innate immune response to tuberculosis (TB) infections, and 4 common single nucleotide polymorphisms (SNPs) may be associated with pulmonary tuberculosis (PTB) risk. To examine these potential associations, we performed a comprehensive analysis to assess the relationships between MBL2 polymorphisms and PTB.

Methods

The PubMed, Embase, and SinoMed databases were searched for articles published prior to June 13, 2019. Odds ratios with 95% confidence intervals were calculated to evaluate the strength of the relationships.

Results

There were 37 case-control studies examining the effects of the four SNPs in MBL2 on PTB. A positive association between rs11003125 and PTB risk was observed in the hospital-based subgroup. Moreover, for the combined polymorphism and PTB risk, positive associations were detected not only in the total population but also in those with Asian origins across all source of control subgroups. No associations were found for rs7096206 or rs7095891.

Conclusions

Our current study indicated that several SNPs in MBL2 may be associated with susceptibility to PTB.

Mannose-binding lectin gene polymorphism and its effect on short term outcomes in preterm infants

OBJECTIVE

Mannose-binding lectin, which belongs to the collectin family, is an acute-phase reactant that activates the complement system. This study aimed to investigate the effect of MBL2 gene polymorphism on short-term outcomes in preterm infants.

METHOD

Infants of <37 gestational weeks who were admitted to the neonatal intensive care unit during a two-year period were enrolled in this prospective study. The neonates were categorized into two groups according to their MBL2 genotypes. Normal MBL2 genotype was defined as MBL2 wild-type (AA genotype), whereas mutant MBL2 genotype was defined as MBL2 variant-type (AO/OO genotype). The relationship between MBL2 genotype and short-term morbidity and mortality was evaluated.

RESULTS

During the two-year study period, 116 preterm infants were enrolled in this study. In MBL2 variant-type, mannose-binding lectin levels were significantly lower and incidences of mannose-binding lectin deficiency (MBL level<700ng/mL) were higher (p<0.001). In this group, the prevalence of respiratory distress syndrome and mortality was significantly higher (p<0.001, p=0.03 respectively). In the MBL2 wild-type group, the prevalence of necrotizing enterocolitis (NEC) was higher (p=0.01). Logistic regression analyses revealed that MBL2 variant-type had a significant effect on respiratory distress syndrome development (odds ratio, 5.1; 95% confidence interval, 2.2-11.9; p<0.001).

CONCLUSIONS

MBL2 variant-type and mannose-binding lectin deficiency are important risk factors for respiratory distress syndrome development in preterm infants. Additionally, there is an association between MBL2 wild-type and NEC. Further studies on this subject are needed.

Mannose-binding lectin 2 gene polymorphisms and their association with tuberculosis in a Chinese population

BACKGROUND

Immune- and inflammation-related genes (IIRGs) play an important role in the pathogenesis of tuberculosis (TB). However, the relationship between IIRG polymorphisms and TB risk remains unknown. In this study, the gene polymorphisms and their association with tuberculosis were determined in a Chinese population.

METHODS

We performed a case-control study involving 1016 patients with TB and 507 healthy controls of Han Chinese origin. Sixty-four single-nucleotide polymorphisms (SNPs) belonging to 18 IIRGs were genotyped by the PCR-MassArray assay, and the obtained data was analyzed with χ²-test, Bonferroni correction, and unconditional logistic regression analysis.

RESULTS

We observed significant differences in the allele frequency of LTA rs2229094*C (P = 0.015), MBL2 rs2099902*C (P = 0.001), MBL2 rs930507*G (P = 0.004), MBL2 rs10824793*G (P = 0.004), and IL12RB1 rs2305740*G (P = 0.040) between the TB and healthy groups. Increased TB risk was identified in the rs930507 G/G genotype (P_adjusted = 0.027) under a codominant genetic model as well as in the rs2099902 (C/T + C/C) vs T/T genotype (P_adjusted = 0.020), rs930507 (C/G + G/G) vs C/C genotype (P_adjusted = 0.027), and rs10824793 (G/A + G/G) vs A/A genotype (P_adjusted = 0.017) under a dominant genetic model after Bonferroni correction in the analysis of the overall TB group rather than the TB subgroups. Furthermore, the rs10824793_rs7916582*GT and rs10824793_rs7916582*GC haplotypes were significantly associated with increased TB risk (P = 0.001, odds ratio [OR] = 1.421, 95% confidence interval [CI]: 1.152-1.753; and P = 0.018, OR = 1.364, 95% CI: 1.055-1.765, respectively). Moreover, the rs10824793_rs7916582*AT/AT or rs10824793_rs7916582*GT/GT diplotype showed a protective (P = 0.003, OR = 0.530, 95% CI: 0.349-0.805) or harmful (P = 0.009, OR = 1.396, 95% CI: 1.087-1.793) effect against the development of TB.

CONCLUSIONS

This study indicated that MBL2 polymorphisms, haplotypes, and diplotypes were associated with TB susceptibility in the Han Chinese population. Additionally, larger sample size studies are needed to further confirm these findings in the future.

Complement related pattern recognition molecules as markers of short-term mortality in intensive care patients

OBJECTIVES

To evaluate the complement related pattern recognition molecules (PRMs) PTX3, MBL, CL-11, ficolin-2 and -3, along with the established marker CRP, to predict 28-day mortality and disease severity of sepsis in patients admitted to the intensive care unit (ICU).

METHODS

In a single-center, prospective, observational study 547 patients were included over a period of 18 months. Blood samples were obtained at admission to the ICU and the following 4 days.

RESULTS

PTX3 baseline levels were significantly higher in non-survivors compared to survivors, whereas MBL and ficolin-2 levels were significantly lower in non-survivors compared to survivors. A PTX3 level above the median was independently associated with 28-day mortality in the adjusted analysis including age, sex, chronic disease and immunosuppression (HR 1.87, 95% CI [1.41-2.48], p < 0.0001), while a MBL level above the median was associated with increased chance of survival (HR 0.75, 95% CI [0.57-0.98], p = 0.034). Ficolin-2 was only borderline significant (HR 0.79, 95% CI [0.60-1.03], p = 0.084). In a ROC analysis PTX3 was superior to CRP in predicting septic shock.

CONCLUSIONS

PTX3, MBL and CRP levels were independently associated with 28-day mortality in ICU patients. PTX3 was a better marker of septic shock compared to CRP.

Genetic association of MBL-2 gene polymorphisms with Filarial chyluria

Lymphatic filariasis has become a significant public health issue in North India. The association of polymorphisms in MBL2 gene with filarial chyluria (FC) is evaluated in the North Indian patients for the first time. Hence, a tertiary care hospital based case-control study was conducted in north India where FC is endemic. Therefore, 186 confirmed patients of FC as cases and 210 age-, sex- and residence-matched subjects as controls were enrolled for the study. Filarial etiology was confirmed using diethylcarbamazine (DEC)-provocation test, immune chromatographic test and IgG/IgM antibody test. MBL2 gene polymorphisms at codon 54 and -221 promoter region were genotyped by PCR followed by RFLP. Wild-type, heterozygous and homozygous mutant frequencies of MBL2 genotype at the codon 54 were 57.5%, 32.8% and 9.7% in the case group and 62.9%, 30.5% and 6.7%, in controls, respectively. The same at the -221 position were 51.1%, 44.1% and 4.8% in FC patients and 44.3%, 40.0% and 15.7% in controls, respectively. Thus, results no significant association between MBL2 polymorphism at codon 54 and FC. However, polymorphism at the -221 promoter region is linked with FC with a significant odd-ratio of 0.27 (confidence interval at 95% was 0.12-0.59; p<0.001). This preliminary finding is intriguing for further confirmation using a larger study with more patients.

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.

Influence of a mannose-binding lectin gene polymorphism and exposure to Chlamydia trachomatis on fallopian tube obstruction in Brazilian woman

PURPOSE

Factors influencing fallopian tube occlusion in women with a lower genital tract infection remain incompletely elucidated. We evaluated whether a polymorphism in the mannose-binding lectin (MBL) gene at codon 54 influences the occurrence of fallopian tube blockage in relation to exposure to Chlamydia trachomatis.

METHODS

In a case-control study at The Hospital das Clínicas, University of São Paulo, Brazil, 75 women with hysterosalpingography-documented tubal occlusion and 75 women with patent fallopian tubes were analyzed for detection of single-nucleotide polymorphism in codon 54 of the MBL gene and for IgG anti-C. trachomatis antibodies in their sera. Both groups were matched for age, race, and sexual variables.

RESULTS

Prior exposure to C. trachomatis, as evidenced by the presence of IgG antibodies, was comparable in both groups. Detection of the polymorphic MBL allele was more prevalent in women with blocked tubes (p < 0.01), regardless of whether or not there was evidence of prior chlamydial exposure.

CONCLUSION

The level of MBL-related innate immunity influences the consequences of infection by C. trachomatis or other microbes.

Characterization and functional analysis of a novel mannose-binding lectin from the swimming crab Portunus trituberculatus

Mannose-binding lectin (MBL) is a pattern recognition receptor (PRR) that plays an important role in the innate immune response. In this study, a novel mannose-binding lectin was cloned from the swimmimg crab Portunus trituberculatus (designated as PtMBL). The complete cDNA of PtMBL gene was 1208 bp in length with an open reading frame (ORF) of 732 bp that encoded 244 amino acid proteins. PtMBL shared lower amino acid similarity with other MBLs, yet it contained the conserved carbohydrate-recognition domain (CRD) with QPD motif and was clearly member of the collectin family. PtMBL transcripts were mainly detected in eyestalk and gill with sexually dimorphic expression. The temporal expression of PtMBL in hemocytes showed different activation times after challenged with Vibrio alginolyticus, Micrococcus luteus and Pichia pastoris. The recombinant PtMBL protein revealed antimicrobial activity against the tested Gram-negative and Gram-positive bacteria. It could also bind and agglutinate (Ca²⁺-dependent) both bacteria and yeast. Furthermore, the agglutinating activity could be inhibited by both d-galactose and d-mannose, suggesting the broader pathogen-associated molecular patterns (PAMPs) recognition spectrum of PtMBL. These results together indicate that PtMBL could serve as not only a PRR in immune recognition but also a potential antibacterial protein in the innate immune response of crab.

Clinical and laboratory associations of mannose-binding lectin in 219 adults with IgG subclass deficiency

Background

Mannose-binding lectin (MBL) deficiency may increase risk of respiratory tract infection in adults unselected for IgG or IgG subclass levels. In a retrospective study, we sought to determine associations of serum MBL levels with clinical and laboratory characteristics of unrelated non-Hispanic white adults at diagnosis of IgG subclass deficiency (IgGSD). We computed the correlation of first and second MBL levels expressed as natural logarithms (ln) in a patient subgroup. We compared these characteristics of all adults with and without MBL ≤50 ng/mL: age; sex; body mass index; upper/lower respiratory tract infection; diabetes; autoimmune condition(s); atopy; other allergy; corticosteroid therapy; and subnormal serum IgG subclasses, IgA, and IgM. We performed logistic regression on MBL ≤50 ng/mL (dichotomous) using the three independent variables with the lowest values of p in univariate comparisons.

Results

There were 219 patients (mean age 51 ± 13 y; 82.5% women). Thirty-six patients (16.4%) had MBL ≤50 ng/mL. Two MBL measurements were available in 14 patients. The median interval between the first and second measurements was 125 d (range 18–1031). For ln-transformed data, we observed adjusted r² = 0.9675; Pearson correlation coefficient 0.9849; and p < 0.0001. Characteristics of patients with and without MBL ≤50 ng/mL did not differ significantly in univariate comparisons. We performed a regression on MBL ≤50 ng/mL using: subnormal IgM (p = 0.0565); upper respiratory tract infection (p = 0.1094); and body mass index (p = 0.1865). This regression revealed no significant associations. Conclusions: We conclude that the proportion of the present IgGSD patients with serum MBL ≤50 ng/mL is similar to that of healthy European adults. MBL ≤50 ng/mL was not significantly associated with independent variables we studied.

Role of lectin pathway complement proteins and genetic variants in organ damage and disease severity of systemic sclerosis: a cross-sectional study

BACKGROUND

The role of the complement system in the pathogenesis of systemic sclerosis (SSc) is controversial. This study investigated the role of the lectin pathway of complement as a mediator of ischemia/reperfusion injury in SSc.

METHODS

This is a prospective observational cross-sectional study of 211 SSc patients and 29 patients with Raynaud's phenomenon in undifferentiated connective tissue disease (UCTD) at risk of developing SSc from two outpatient clinics. Serum levels of lectin pathway proteins (FCN-2, FCN-3, MBL, and MASP-2) and eight MBL2 and FCN2 single-nucleotide polymorphisms (SNP) were analyzed by sandwich-type immunoassays and genotyping and examined for their association with disease manifestations.

RESULTS

Lectin pathway protein levels and SNPs were similar between SSc and UCTD patients. FCN-2 levels were however higher in SSc patients with present evidence of digital ulcers (mean 1.4 vs. 1.0 μg/mL, p = 0.05), pitting scars (mean 1.3 vs. 1.0 μg/mL, p = 0.01), and puffy fingers (mean 1.2 vs. 1.0 μg/mL, p = 0.04). Similarly, higher FCN-2 levels were observed in SSc patients with Scl-70 autoantibodies (mean 1.5 vs. 1.0 μg/mL, p = 0.001), interstitial lung disease (mean 1.2 vs. 0.9 μg/mL, p = 0.02), and a forced vital capacity (FVC) below 80% (mean 1.4 vs. 1.0 μg/mL, p = 0.02). In line, variant alleles in the FCN-2 SNP at position + 6359 were associated with a significantly reduced FVC and diffusion capacity. Furthermore, patients with SSc renal crisis harbored higher MBL levels (mean 2.7 vs. 1.5 μg/mL, p = 0.04). No other lectin pathway protein levels or polymorphisms were associated with disease manifestations, low complement C3 and/or C4 levels, or inflammatory markers.

CONCLUSIONS

This study does not support a relevant role for several lectin pathway complement proteins in the pathogenesis of SSc. Higher FCN-2 levels were however associated with Scl-70 autoantibody positivity, interstitial lung involvement, and digital vasculopathy. Elevated MBL levels were associated with renal crisis.

Broad-spectrum capture of clinical pathogens using engineered Fc-mannose-binding lectin enhanced by antibiotic treatment

Background: Fc-mannose-binding lectin (FcMBL), an engineered version of the blood opsonin MBL that contains the carbohydrate recognition domain (CRD) and flexible neck regions of MBL fused to the Fc portion of human IgG1, has been shown to bind various microbes and pathogen-associated molecular patterns (PAMPs). FcMBL has also been used to create an enzyme-linked lectin sorbent assay (ELLecSA) for use as a rapid (<1 h) diagnostic of bloodstream infections. Methods: Here we extended this work by using the ELLecSA to test FcMBL's ability to bind to more than 190 different isolates from over 95 different pathogen species. Results: FcMBL bound to 85% of the isolates and 97 of the 112 (87%) different pathogen species tested, including bacteria, fungi, viral antigens and parasites. FcMBL also bound to PAMPs including, lipopolysaccharide endotoxin (LPS) and lipoteichoic acid (LTA) from Gram-negative and Gram-positive bacteria, as well as lipoarabinomannan (LAM) and phosphatidylinositol mannoside 6 (PIM 6) from Mycobacterium tuberculosis. Conclusions: The efficiency of pathogen detection and variation between binding of different strains of the same species could be improved by treating the bacteria with antibiotics, or mechanical disruption using a bead mill, prior to FcMBL capture to reveal previously concealed binding sites within the bacterial cell wall. As FcMBL can bind to pathogens and PAMPs in urine as well as blood, its broad-binding capability could be leveraged to develop a variety of clinically relevant technologies, including infectious disease diagnostics, therapeutics, and vaccines.

Increased risk of group B Streptococcus causing meningitis in infants with mannose-binding lectin deficiency

OBJECTIVES

To evaluate the association of mannose-binding lectin (MBL) deficiency with susceptibility and clinical features of group B Streptococcus (GBS) causing meningitis in Chinese infants.

METHODS

During 2014-2017, 33 infants with laboratory-confirmed GBS meningitis were included. Six polymorphisms (H/L, Y/X, P/Q, A/D, A/B and A/C) of MBL were sought for in these patients and in 330 healthy controls by PCR-based sequencing. Serum MBL concentration was determined.

RESULTS

Significantly higher frequency of MBL variant genotype A/B was found in patients than controls (15/33, 45%, vs. 79/330, 24%, p=0.011). Patients with variant genotype A/B had significantly lower serum MBL than those with wild-type genotype A/A (median, 482.87 vs. 1455.13 ng/mL, p=0.002). Moreover, patients with genotype A/B had significantly higher level of C-reactive protein (median, 146 vs. 41 mg/L, p=0.007), neutrophil (median, 58.1% vs. 45.7%, p=0.033) and neutrophil-to-lymphocyte ratio in blood (median, 2.32 vs. 1.03, p=0.018) compared to those with genotype A/A. No significant differences were observed in clinical features of patients with different genotypes.

CONCLUSIONS

Our result suggested that infants with MBL deficiency are at higher risk of meningitis caused by GBS. Further studies in different populations with larger number of subjects are needed.

Binding capacity of mannose-binding lectin (MBL) is associated with the severity of chronic Chagas cardiomyopathy

Chagas disease (CD) is a global problem. Currently, it affects approximately 15 million individuals in Latin America. It is well know that the human immune response is related to different clinical manifestations. Mannose binding lectin (MBL) plays an important role in innate immunity, and it mediates the phagocytosis and complement-mediated destruction of pathogens. The binding capacity is enhanced by the oligomerization of MBL. In this study, we evaluated the serum concentration and the binding capacity of MBL in patients with chronic chagasic cardiomyopathy. A total of 77 patients with chronic CD were included with indeterminate (n = 19), mild cardiac (n = 29) and severe cardiac (n = 29) forms. The serum concentration and the binding capacity were measured using enzyme-linked immunosorbent assays (ELISA). There was no significant difference in the serum MBL levels between the groups of patients. However, we found a relationship between the binding capacity and the groups studied. Our results suggest that binding capacity of MBL could be an indicator of clinical manifestation in Chronic Chagas cardiomyopathy. Furthermore, combined with the Mannose Binding Index results in a useful clinical tool for management of Chronic Chagas Patients.

Correlation between MBL2/CD14/TNF-α gene polymorphisms and susceptibility to spinal tuberculosis in Chinese population

Objective: The present study investigated the clinical significance of mannose-binding lectin 2 (MBL2), cluster of differentiation 14 (CD14) and tumour necrosis factor-α (TNF-α) gene polymorphisms in patients with spinal tuberculosis (TB) in Chinese population. Methods: A total of 240 patients with spinal TB were enrolled in the present study from May 2013 to August 2016 at Hangzhou Red Cross Hospital. A total of 150 age- and sex-matched healthy subjects were enrolled as controls. The genomic DNA was extracted from the peripheral blood of all subjects, and the MBL2, CD14 and TNF-α gene polymorphisms were detected by direct DNA sequencing. Results: (1) Compared with controls, patients with spinal TB exhibited a significantly higher frequency of the XY genotype at the −221G>C polymorphism as well as the Q allele and PQ genotype or an association with the QQ genotype at the +4C>T polymorphism in the MBL2 gene. (2) Compared with controls, patients with spinal TB exhibited a significantly higher frequency of the T allele and TT genotype or an association with the CT genotype at the −159C>T polymorphism in the CD14 gene. (3) Compared with controls, patients with spinal TB exhibited a significantly higher frequency of the T allele and the CT genotype or an association with the TT genotype at the TNF-857 polymorphism in the TNF-α gene. Conclusion: The −221G>C polymorphism of MBL2, the −159C>T polymorphism of CD14 and the TNF-857 polymorphism of TNF-α are risk factors for spinal TB and may be involved in the development of spinal TB in the Chinese population. These factors are indicators of susceptibility to spinal TB and require clinical attention.

Ross River virus envelope glycans contribute to disease through activation of the host complement system

Mannose binding lectin (MBL) generally plays a protective role during viral infection, yet MBL-mediated complement activation promotes Ross River virus (RRV)-induced inflammatory tissue destruction, contributing to arthritis and myositis. As MBL binds to carbohydrates, we hypothesized that N-linked glycans on the RRV envelope glycoproteins act as ligands for MBL. Using a panel of RRV mutants lacking the envelope N-linked glycans, we found that MBL deposition onto infected cells was dependent on the E2 glycans. Moreover, the glycan-deficient viruses exhibited reduced disease and tissue damage in a mouse model of RRV-induced myositis compared to wild-type RRV, despite similar viral load and inflammatory infiltrates within the skeletal muscle. Instead, the reduced disease induced by glycan-deficient viruses was linked to decreased MBL deposition and complement activation within inflamed tissues. These results demonstrate that the viral N-linked glycans promote MBL deposition and complement activation onto RRV-infected cells, contributing to the development of RRV-induced myositis.

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Mannose-binding lectin promotes induction of complement-mediated arthritis and myositis during Ross River virus infection.

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Mannose Binding Lectin deposition onto Ross River virus-infected cells is dependent on glycans on the viral E2 glycoprotein.

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Viral mutants lacking E2 glycans exhibit reduced disease in a model of Ross River virus-induced arthritis and myositis.

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Ross River virus E2 glycan mutants cause reduced Mannose Binding Lectin deposition and complement activation.

Prospective Observational Study on the Association Between Serum Mannose-Binding Lectin Levels and Severe Outcome in Critically Ill Patients with Pandemic Influenza Type A (H1N1) Infection

Background

Mannose-binding lectin (MBL) plays an important role in the innate immune response. In addition to activating the complement, MBL can induce cytokine production and contribute to a deleterious inflammatory response with severe A(H1N1)pdm09 virus infection. Our aim was to determine if serum MBL levels correlate with the risk of mortality in intensive care units (ICU) patients with A(H1N1)pdm09 infection.

Methods

Prospective observational study was performed in ICU patients with acute respiratory distress syndrome due to influenza A(H1N1)pdm09 virus. Demographic characteristics and severity indices were recorded at ICU admission. MBL was assayed from blood drawn at influenza diagnosis within 24–48 h following the ICU admission. Outcomes were compared according to MBL levels. Results are expressed as median and interquartile range.

Results

Serum MBL levels were studied in 27 patients (age: 56 [IQR 29] years) with severe A(H1N1)pdm09 infection and in 70 healthy controls. Median admission SAPSII and SOFA scores were 49 [IQR 26] and 12 [IQR 5], respectively. Mortality rate after a 30-day was 37%. MBL was significantly higher in non-survivors (3741 [IQR 2336] ng/ml) vs survivors (215 [IQR 1307] ng/ml), p = 0.006, as well as control group (1814 [IQR 2250] ng/ml), p = 0.01. In contrast, MBL levels in survivors group were significantly lower than the controls group (215 [IQR 1307] ng/ml vs. 1814 [IQR 2250] ng/ml, p = 0.005). MBL cut-off > 1870 ng/ml had a sensitivity of 80% and a specificity of 88.2% for mortality [AUC = 0.82 (95% CI 0.63–0.94)]. Kaplan–Meier analysis demonstrated a strong association between MBL levels and mortality (log-rank 7.8, p = 0.005). MBL > 1870 ng/ml was independently associated with mortality (HR = 8.7, 95% CI 1.2–29.1, p = 0.007).

Conclusions

This study shows that baseline MBL > 1870 ng/ml is associated with higher mortality in ICU patients with severe A(H1N1)pdm09 infection.

Association of Single-Nucleotide Polymorphisms of the MBL2 with Atopic Dermatitis in Korean Patients

BACKGROUND

Human mannose-binding lectin (MBL) is a serum lectin taking part in the innate immunity by opsonizing various microorganisms for phagocytosis. The MBL serum concentration is affected by several single-nucleotide polymorphisms (SNPs) in the promoter region of the MBL2 gene.

OBJECTIVE

The purpose of this study was to examine the relationship between MBL2 polymorphisms and atopic dermatitis (AD) susceptibility.

METHODS

To examine whether the MBL2 SNPs are related to AD susceptibility, we examined 237 patients with AD and 94 controls by polymerase chain reaction (PCR)-restriction fragment length polymorphism and PCR-sequence specific primer analyses of four polymorphic loci: two (H/L and X/Y) within the promoter region and the other two (P/Q and A/B) within exon 1. MBL concentrations in the blood were estimated by ELISA.

RESULTS

The prevalence of haplotype HYPB, leading to MBL deficiency, was significantly decreased in the AD patients compared to the controls (p=0.002), while the prevalence of haplotype HYPA was increased with a clear trend toward significance (p=0.056). The frequency of MBL2 LYPB/LXPA (odds ratio, 0.08; 95% confidence interval, 0.009~0.655; p=0.021) were significantly decreased in the AD patients. The blood log [total immunoglobulin E, IgE] levels of MBL2 HYPA/HYPA, HYPA/LYPA, HYPA/LYPB, HYPA/LYQA, and LYQA/LXPA haplotype pairs were significantly increased in the AD patients.

CONCLUSION

The frequency of MBL2 HYPB haplotype was significantly decreased in the AD patients compared to the controls. The frequency of LYPB/LXPA had a possibly protective effect on AD. Moreover, the MBL2 HYPA haplotype pairs, which were related to higher blood total IgE levels, were possibly associated with extrinsic AD.

MBL2 and FCN2 gene polymorphisms in a cohort of Italian children with rheumatic fever: A case-control study

BACKGROUND

Mannose-binding lectins and human ficolins are pattern-recognition proteins involved in innate immunity. A role for MBL2 and FCN2 gene polymorphisms in the pathogenesis of recurrent severe streptococcal infections and rheumatic carditis has been suggested.

OBJECTIVES

The aim of this study is to evaluate the presence of MBL2 and FCN2 gene polymorphisms (SNPs) in children with a history of rheumatic fever (RF) and to investigate their possible role in RF clinical presentation and disease course.

METHODS

A total of 50 Caucasian patients with RF were recruited with a control group of 52 healthy children. DNA was extracted for analysis of MBL2 gene (exon 1, codons: 52, 54, and 57) and FCN2 gene (promoter region at position -986, -602, and -4).

RESULTS

The FCN2 AG genotype at the -986 position was more frequently observed in patients, as compared to healthy subjects (p = 0.006); furthermore, the A allele was identified as a possible risk factor for the development of RF (OR = 7.14, CI: 2.439-20.89). Conversely, the GG genotype at the same position was observed more frequently in the control group and can be considered a protective factor for the development of the disease (p = 0.001, OR = 8.37, 95% CI: 2.763-25.33). In addition, the FCN2 GG and AG genotypes in the -4 position were also found to be protective factors for the development of RF and for carditis respectively (OR = 3.32, CI: 1.066-10.364; OR = 0.15, 95% CI: 0.037-0.566). Finally, the AA genotype in the -602 position was associated with a late onset of RF (p = 0.006). The analysis of the MBL2 gene only resulted in a higher frequency of the AA genotype on position 57 in controls as compared to patients (p = 0.025).

CONCLUSIONS

This is the first study evaluating the FCN2 gene polymorphisms in patients with RF and rheumatic carditis finding a protective effect of -986 GG and -4 GG genotypes in the development of RF and the -4 AG genotype for the development of carditis. Our data do not support a possible role for MBL2 polymorphisms in the pathogenesis and in the clinical manifestations of RF.

Interaction of extremophilic archaeal viruses with human and mouse complement system and viral biodistribution in mice

Archaeal viruses offer exceptional biophysical properties for modification and exploration of their potential in bionanotechnology, bioengineering and nanotherapeutic developments. However, the interaction of archaeal viruses with elements of the innate immune system has not been explored, which is a necessary prerequisite if their potential for biomedical applications to be realized. Here we show complement activation through lectin (via direct binding of MBL/MASPs) and alternative pathways by two extremophilic archaeal viruses (Sulfolobus monocaudavirus 1 and Sulfolobus spindle-shaped virus 2) in human serum. We further show some differences in initiation of complement activation pathways between these viruses. Since, Sulfolobus monocaudavirus 1 was capable of directly triggering the alternative pathway, we also demonstrate that the complement regulator factor H has no affinity for the viral surface, but factor H deposition is purely C3-dependent. This suggests that unlike some virulent pathogens Sulfolobus monocaudavirus 1 does not acquire factor H for protection. Complement activation with Sulfolobus monocaudavirus 1 also proceeds in murine sera through MBL-A/C as well as factor D-dependent manner, but C3 deficiency has no overall effect on viral clearance by organs of the reticuloendothelial system on intravenous injection. However, splenic deposition was significantly higher in C3 knockout animals compared with the corresponding wild type mice. We discuss the potential application of these viruses in biomedicine in relation to their complement activating properties.

Identification and characterization of a mannose-binding lectin from Nile tilapia (Oreochromis niloticus)

Mannose-binding lectin (MBL) is a pattern recognition protein that plays an important role in innate immunity capable of activating the lectin pathway of the complement system. In this study, a MBL homologue (OnMBL) was identified from Nile tilapia (Oreochromis niloticus) and characterized at expression and agglutination functional levels. The open reading frame of OnMBL is 687 bp of nucleotide sequence encoding polypeptides of 228 amino acids. The deduced amino acid sequence is highly homology to teleost and similar to mammalian MBL, containing a canonical collagen-like region, a carbohydrate recognition domain and a neck region. Expression analysis revealed that the OnMBL was highly expressed in the liver, and also exhibited in other tissues including hind kidney, intestines, head kidney and spleen. In addition, the OnMBL expression was significantly up-regulated in spleen and head kidney following challenges with a Gram-positive bacterial pathogen (Streptococcus agalactiae) and a Gram-negative bacterial pathogen (Aeromonas hydrophila). Recombinant OnMBL ((r)OnMBL) protein was able to agglutinate both S. agalactiae and A. Hydrophila in vitro. Taken together, the results of this study indicated that OnMBL, possessing apparent agglutination ability to bacterial pathogens, might be involved in host defense against bacterial infection in Nile tilapia.

Evaluation of TNF-alpha gene (G308A) and MBL2 gene codon 54 polymorphisms in Turkish patients with tuberculosis

OBJECTIVE

MBL acts as a binding protein that enables uptake of mycobacteria into macrophages. And, TNF-alpha is an important cytokine that is involved in control of mycobacterial infections both in-vivo and in-vitro. A large number of genetic factors exerting susceptibility to tuberculosis has been identified, among which mannose-binding lectin and tumor necrosis factor-alpha call attention. The objective of this study is to compare the frequency of TNF-alpha and MBL gene polymorphisms between patients diagnosed with tuberculosis and healthy volunteers in Turkey, and determine the association between tuberculosis and TNF-alpha gene (G308A) and MBL2 gene codon 54 polymorphisms.

MATERIAL AND METHODS

The study included 69 patients who were diagnosed with tuberculosis and 70 control subjects. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to detect TNF-alpha (G308A) gene and MBL2 gene codon 54 polymorphisms. For statistical analysis, the significance level was determined as p<0.05.

RESULTS

A comparison between patient and control groups in TNF-alpha (G308A) gene and MBL2 gene codon 54 polymorphisms showed no statistically significant difference (p>0.05). However, a comparison of mean body mass index (BMI) and smoking status showed a statistically significant difference between the tuberculosis and control groups (p=0.01 and p=0.009, respectively).

CONCLUSION

Our results suggest that the MBL2 gene Codon 54 and TNF-alpha gene G308A polymorphisms are not associated with an increased risk for development of tuberculosis in our patients. Further studies are required including more cases of tuberculosis patients and other potentially relevant gene polymorphisms.

Neonatal levels of adiponectin, interleukin-10 and interleukin-12 are associated with the risk of developing type 1 diabetes in childhood and adolescence: A nationwide Danish case-control study

BACKGROUND/AIM

An in-depth understanding of the early phase of type 1 diabetes (T1D) pathogenesis is important for targeting primary prevention. We examined if 14 preselected mediators of immune responses differed in neonates that later developed T1D compared to control neonates.

METHODS

The study is a case-control study with a 1:2 matching. The individuals were born between 1981 through 2002. Cases were validated using the National Patient Register and the Danish Childhood Diabetes Register. Interleukin(IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-12p70, interferon gamma, tumor necrosis factor alpha, transforming growth factor beta 1 (active form), leptin, adiponectin, c-reactive protein, mannose-binding lectin and soluble triggering receptor expressed on myeloid cells-1 were measured by using a flowmetric Luminex xMAP® technology. We tested two models both including a number of possible confounders. In the first model (model 1) we also adjusted for HLA-DQB1 genotype. A total of 1930 groups of assay-matched cases and controls (4746 individuals) were included in the statistical analyses.

RESULTS

Adiponectin was negatively associated with later risk of T1D in both models (relative change (RC), model 1: 0.95, P=0.046 and model 2: 0.95, P=0.006). IL-10 and IL-12 were both positively associated with T1D risk in the model 2 (RC, 1.19, P=0.006 and 1.07, P=0.02, respectively)-these results were borderline significant in model 1, but showed the same direction as the results from model 2.

CONCLUSIONS

Our results indicate that specific immunological signatures are already present at time of birth in children developing T1D before the age of 18years.

Tri- and tetravalent mannoclusters cross-link and aggregate BC2L-A lectin from Burkholderia cenocepacia

The opportunistic Gram-negative bacterium Burkholderia cenocepacia causes lethal infections in cystic fibrosis patients. Multivalent mannoside derivatives were prepared as potential inhibitors of lectin BC2L-A, one of the virulence factors deployed by B. cenocepacia in the infection process. An (α1→2)-thio-linked mannobioside mimic bearing an azide functionalized aglycon was conjugated to different multivalent scaffolds such as propargylated calix[4]arenes, methyl gallate and pentaerythritol by azide-alkyne 1,3-dipolar cycloaddition. The interaction between the glycoclusters and the mannose binding BC2L-A lectin from B. cenocepacia was examined by isothermal microcalorimetry, surface plasmon resonance, inhibition of yeast agglutination and analytical ultracentrifugation.

Mannose-binding Lectin Mediated Complement Pathway in Autoimmune Neurological Disorders

Multiple sclerosis (MS) is a complex, demyelinating disease of the central nervous system (CNS) with variable phenotypic presentations, while Guillain-Barre Syndrome (GBS) is the prototypic acute inflammatory disorder that affects the peripheral nervous system. Myasthenia gravis (MG) is a T cell dependent and antibody mediated autoimmune disease. Although it has been shown that complement plays a critical role in the pathogenesis of MS, GBS, and MG, the role of mannose-binding lectin (MBL) as a biomarker of immunopathogensis of these diseases and also its association with the severity of them have been poorly investigated. Therefore, in this study we aimed to measure plasma levels of MBL in patients with MS, GBS, and MG. In a case-control study, plasma was obtained from healthy controls (n=100) and also patients with MS (n=120), GBS (n=30), and MG (n=30). Plasma level measurement of MBL was performed using enzyme-linked immunosorbent assay (ELISA). The mean serum level of MBL was significantly different between groups of patients and healthy controls (p<0.001). We also found a positive correlation between plasma levels of MBL and severity scores of MS, MG, and GBS patients including: expanded disability status scale (EDSS) (r=+0.60 and p=<0.001), quantitative myasthenia gravis score (QMGS) (r=+0.56 and p=0.01), and GBS disability scale (GDS) (r=+0.37 and p=0.04). Taken together, our findings suggest that complement activation mediated by MBL contributes to the pathogenesis and also severity of MS, MG, and GBS. However, because the lectin pathway can be involved in several phases of the immune response, further evidence will be required to elucidate the underlying mechanism.

Genetic variations of the bitter taste receptor TAS2R38 are associated with obesity and impact on single immune traits

SCOPE

Changes in genetic variations affecting the taste receptor, type 2, member 38 (TAS2R38) may identify the interacting mechanism leading to obesity and potential associations with proteins partaking in innate immunity, such as surfactant protein D (SPD) and mannan-binding lectin (MBL).

METHODS AND RESULTS

We evaluated haplotypes of the bitter-taste receptor TAS2R38 in an identification sample of 210 women in different weight conditions, including anorexia nervosa and obesity. The association with SPD and MBL was tested in an independent sample picturing general population (n = 534). The relationship with obesity was validated in an extended final sample of 1319 participants. In the sample comprised of women in extreme weight conditions, increased obesity was identified in AVI/AVI subjects (OR = 2.5 [1.06-6.11], p = 0.035). In the sample picturing general population, increased SPD and MBL concentrations were found in nonsmoking AVI carriers. In this cohort, smoking and obesity blunted associations between TAS2R38 haplotypes and SPD and MBL. In the extended sample, the association of AVI/AVI haplotypes with increased obesity was also identified (OR = 1.4 [0.99/1.85], p = 0.049), being more robust in subjects aged <40 years (OR = 1.9 [1.06/3.42], p = 0.031).

CONCLUSION

Current data reinforce the impact of TAS2R38 gene on phenotypic and clinical outputs affecting obesity, showing significant associations with extreme weight conditions (i.e., obesity and anorexia nervosa), and changes in both olfactory capacity and immune traits.

Almroth Wright, opsonins, innate immunity and the lectin pathway of complement activation: a historical perspective

Two clinical tests - the erythrocyte sedimentation rate and the opsonic index - have long been known to non-specifically detect pathology based on their responsiveness to changes in serum proteins. In infections serum levels of specific antibodies increase. However, for healthy subjects Wright held that antibodies contributed minimally to opsonic activity (the complement-enhanced phagocytosis of microorganisms). The activity was present in newborn serum, was increased in the acute phase of an immune response prior to antibody increase, and was less specific. Furthermore, defective opsonization was associated with undue susceptibility to certain infections, for which a genetic basis was later found. With the demonstrations of complement-mediated lysis both of normal cells by foreign (plant) lectins, and of foreign cells (microorganisms) by animal lectins, it now appears that endogenous lectins correspond to the heat-stable component of Wright's serum opsonic activity. His work leads to the lectin pathway of complement activation with specificities limited to the recognition of relatively immutable surface sugars - predictable pathogen characters that contrast with the less predictable targets of the adaptive immune system.

Candidate gene variants of the immune system and sudden infant death syndrome

BACKGROUND

Sudden infant death syndrome (SIDS) causes early infant death with an incidence between 0.5 and 2.5 cases among 1000 live births. Besides central sleep apnea and thermal dysregulation, infections have been repeatedly suggested to be implicated in SIDS etiology.

METHODS

To test the risk contribution of common genetic variants related to infection, we genotyped 40 single-nucleotide polymorphisms (SNPs) from 15 candidate genes for association with SIDS in a total of 579 cases and 1124 controls from Germany and the UK in a two-stage case control design.

RESULTS

The discovery-stage series (267 SIDS cases and 303 controls) revealed nominally significant associations for variants in interleukin 6 (IL6) (rs1880243), interleukin 10 (IL10) (rs1800871, rs1800872), and mannose-binding lectin 2 (MBL2) (rs930506), and for several other variants in subgroups. Meta-analyses were then performed in adding genotype information from a genome-wide association study of another 312 European SIDS cases and 821 controls. Overall associations were observed for two independent variants in MBL2: rs930506 in a co-dominant model (odds ratio (OR) = 0.82, p = 0.04) and rs1838065 in a dominant model (OR = 1.27, p = 0.03).

CONCLUSION

Our study did not replicate published associations of IL10 variants with SIDS. However, the evidence for two independent MBL2 variants in the combined analysis of two large series seems consistent with the hypothesis that infection may play a role in SIDS pathogenesis.

Mannose-binding Lectin Deficiency in Patients with a History of Recurrent Infections

Mannose-binding lectin (MBL) is a protein of innate immune system that is involved in opsonization and complement activation. MBL deficiency is associated with predisposition to infectious diseases; however subnormal levels are also seen in healthy subjects. The aim of this study was to investigate the prevalence and clinical manifestation of MBL deficiency in patients with increased susceptibility to infection. We studied the MBL serum concentration of 104 patients with a history of recurrent and/or severe infections referred to Immunology, Asthma and Allergy Research Institute (IAARI) in order to evaluate the primary immunodeficiency (PID). The distribution of MBL deficiency in these patients and 593 healthy subjects of previous study were analyzed. The frequency of individuals with MBL deficiency was significantly higher in patients with recurrent and/or severe infections (13.5% [14/104]) compared with healthy subjects (4.7% [28/593]; p=0.001; OR 3.1, 95% CI 1.5-6.1). However, in 10.9% (7/64) of patients with recurrent infections without any immunodeficiency background, the MBL deficiency was detected. On the whole, our findings indicate an association between MBL deficiency and increased susceptibility to infections.