Mannose-binding lectin 2 (MBL2) gene polymorphism in asthma and atopy among adults

Increased expression of ficolin-1 is associated with airway obstruction in asthma

BACKGROUND

The activated complement cascade is involved in asthmatic airway inflammation. Ficolins are essential for innate immunity and can activate the complement lectin pathway. Despite this, the significance of ficolins in asthma has yet to be determined. This study aimed to explore the presence of ficolins in individuals with asthma and to determine the relationship between ficolins and clinical characteristics.

METHODS

For the study, 68 asthmatic patients and 30 healthy control subjects were recruited. Enzyme-linked immunosorbent assay was used to determine plasma ficolin-1, ficolin-2, and ficolin-3 concentrations both before and after inhaled corticosteroid (ICS) therapy. Further, the associations of plasma ficolin-1 level with pulmonary function and asthma control questionnaire (ACQ) score were examined in the asthma patients.

RESULTS

Patients with asthma exhibited significantly elevated plasma ficolin-1 levels (median, 493.9 ng/mL; IQR, 330.2-717.8 ng/mL) in comparison to healthy controls (median, 330.6 ng/mL; IQR, 233.8-371.1 ng/mL). After ICS treatment, plasma ficolin-1 (median, 518.1 ng/mL; IQR, 330.2-727.0 ng/mL) in asthmatic patients was significantly reduced (median, 374.7 ng/mL; IQR, 254.8-562.5 ng/mL). Additionally, ficolin-1 expressions in plasma were significantly correlated with pulmonary function parameters and ACQ score in asthmatic patients. Asthma patients with higher plasma ficolin-1 levels demonstrated poorer lung function than those with lower plasma ficolin-1 levels.

CONCLUSIONS

The results revealed that asthmatic patients had higher plasma ficolin-1 concentrations, which decreased after ICS treatment and were linked to their lung function, implying a potential involvement of ficolin-1 in asthma pathogenesis.

Relationship among genetic variants, obesity traits and asthma in the Taiwan Biobank

BACKGROUND AND OBJECTIVE

Obesity and asthma impose a heavy health and economic burden on millions of people around the world. The complex interaction between genetic traits and phenotypes caused the mechanism between obesity and asthma is still vague. This study investigates the relationship among obesity-related polygenic risk score (PRS), obesity phenotypes and the risk of having asthma.

METHODS

This is a matched case-control study, with 4 controls (8288 non-asthmatic) for each case (2072 asthmatic). Data were obtained from the 2008-2015 Taiwan Biobank Database and linked to the 2000-2016 National Health Insurance Research Database. All participants were ≥30 years old with no history of cancer and had a complete questionnaire, as well as physical examination, genome-wide single nucleotide polymorphisms and clinical diagnosis data. Environmental exposure, PM_2.5, was also considered. Multivariate adjusted ORs and 95% CIs were calculated using conditional logistic regression stratified by age and sex. Mediation analysis was also assessed, using a generalised linear model.

RESULTS

We found that the obese phenotype was associated with significantly increased odds of asthma by approximately 26%. Four obesity-related PRS, including body mass index (OR=1.07 (1.01-1.13)), waist circumference (OR=1.10 (1.04-1.17)), central obesity as defined by waist-to-height ratio (OR=1.09 (1.03-1.15)) and general-central obesity (OR=1.06 (1.00-1.12)), were associated with increased odds of asthma. Additional independent risk factors for asthma included lower educational level, family history of asthma, certain chronic diseases and increased PM_2.5 exposure. Obesity-related PRS is an indirect risk factor for asthma, the link being fully mediated by the trait of obesity.

CONCLUSIONS

Obese phenotypes and obesity-related PRS are independent risk factors for having asthma in adults in the Taiwan Biobank. Overall, genetic risk for obesity increases the risk of asthma by affecting the obese phenotype.

Pediatric pulmonology 2019 year in review: rare and diffuse lung disease

Pediatric Pulmonology publishes original research, review articles, and case reports on topics related to a wide range of children's respiratory disorders. Here we review manuscripts published in 2019 in this journal and others on (1) anatomic lung, airway, and vascular malformations, (2) children's interstitial lung disease, and (3) primary ciliary dyskinesia and non-cystic fibrosis bronchiectasis.

Clinical Relevance of Plasma Concentrations of MBL in Accordance with IgE Levels in Children Diagnosed with Bronchial Asthma

Background and objectives: Bronchial asthma is a heterogeneous, multifactorial pulmonary disease characterized by variable airway obstruction caused by chronic inflammation. Our study investigates the clinical relevance of MBL plasma levels in accordance with IgE values in children who attended a pediatric consult for respiratory symptoms with bronchial asthma. Materials and Methods: The study population consists of patients <18-years-old and included 43 patients with bronchial asthma and 64 age-matched healthy subjects as a control group. We used the ELISA Human MBL Immunoassay kit and the electrochemiluminescence immunoassay (ECLIA) kit for IgE determination. Results: Our results show significantly different distributions of patients in the bronchial asthma group and control group. The measured values were within the normal range for most controls, while the bronchial asthma patients displayed higher values of plasma MBL and IgE levels. We observed a wider heterogeneity in MBL concentrations in bronchial asthma patients when compared to the healthy age-matched controls. Our results also suggest a potential clinical usefulness of plasma MBL concentrations in accordance with IgE and eosinophil cells levels in the diagnosis of bronchial asthma, and our results may suggest a prognostic role of MBL in the evolution of asthmatic disease; however, further studies are necessary to confirm these findings. Conclusions: We can say that plasma MBL concentrations present a relative diagnostic role for bronchial asthma in pediatric patients and may suggest a more severe disease progression; however, further studies are needed to elucidate the role played by MBL in the determination and evolution of this disease.

Genetic Polymorphism of MBL 2 in Patients with Allergic Bronchial Asthma

Mannose-binding lectin (MBL) belongs to a family of glycoproteins called lectins or collectins, which possess many of the functional features of immunoglobulins. Mannose-binding lectin is a very important component of the innate immune system, which recognizes distinct pathogens and activates the classical path of the complement-fixation method. In humans, the serum levels of collectins vary widely, and their variability is correlated with susceptibility and resistance to infection and other diseases. Recent studys show that MBL gene polymorphism is involved in the pathogenesis of many diseases, including infectious and allergic illnesses. Our study aims to determine the role of MBL polymorphism in children diagnosed with allergic bronchial asthma, especially in acute episodes. We conclude that MBL2 gene polymorphism is associated with atopy, allergic diseases and acute respiratory tract infections with MBL deficiency in early childhood. In terms of genetic polymorphism, most of the studied alleles were type A, these being the most frequently present in the studied groups, while alleles B, C or D have been explored to a lesser extent. Studies are also required for adult patients with allergic and atopic conditions, because so far, most of the research has been done on pediatric population only.

The impact of mannose-binding lectin polymorphisms on lung function in primary ciliary dyskinesia

OBJECTIVE

Primary ciliary dyskinesia (PCD) is a congenital lung disease that leads to recurrent and chronic lung infection. The resulting inflammation causes lung damage and declines in lung function. Mannose-binding lectin (MBL) is a first line host defense protein of importance for the innate immunity. Polymorphisms in the MBL gene named MBL2 result in unstable and low functional levels MBL proteins. MBL insufficiency is linked to an increased risk of lung infection and to declines in lung function in patients with cystic fibrosis. We investigated whether there is a similar link in patients with PCD.

METHODS

This retrospective longitudinal study included 85 patients with PCD. Diagnostics and age at diagnosis were recorded, complete spirometry data starting at diagnosis, and Pseudomonas aeruginosa infection status over the last 2 years were collected, and the patients were grouped according to MBL2 genotype status (MBL2-sufficient or MBL2-deficient).

RESULTS

MBL-deficient patients were diagnosed almost 3 years earlier than MBL-sufficient patients (median 6.1 vs 8.9 years, P  < 0.05). There were no differences in the first measured spirometry values, but MBL-deficient patients showed greater declines in forced expiratory volume in one sec (FEV₁ ) than patients with MBL sufficiency (z-score: -0.049 per year [95% CI, -0.075; -0.021] vs -0.009 per year [95% CI, -0.033; 0.015]; P = 0.023). No differences were found in forced vital capacity (FVC), FEV₁ /FVC, or infection status.

CONCLUSION

MBL-deficiency, which is associated with MBL2 mutations, was associated with a lower age at diagnosis and with steeper declines in FEV₁ in patients with PCD. This suggests that the MBL genotype might be a disease modifier in PCD.

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.

Mannose-binding lectin deficiency in respiratory diseases

Mannosebinding lectin is a part of the innate immunity that, being the first barrier of the antiinfectious defense, acts in first minutes or hours after pathogen challenge. The review provides data about mechanisms of action of mannosebinding lectin and its particular pathogenic role in a wide range of respiratory diseases: bacterial pneumonia, viral respiratory tract infections, tuberculosis, cystic fibrosis, chronic obstructive pulmonary disease, and asthma in adults and children.

Association of MBL With Work-Related Respiratory Symptoms in Bakery Workers

Baker's asthma is the most prevalent occupational asthma, and IgE-mediated response is known as a major pathogenesis. However, recent studies have suggested the involvement of innate immune response because wheat flour contains bacterial endotoxins or lipopolysaccharides. To further understand a role of innate immune response in the development of work-related respiratory symptoms (WRS) in bakery workers, we investigated mannose-binding lectin (MBL), one of the initiating components of the complement cascade in a single cohort of bakery workers. A total of 373 bakery workers completed a questionnaire regarding WRS. The bakery workers were divided into 2 groups according to previous history of allergic rhinitis (AR)/bronchial asthma (BA): those with history of AR/BA (group I) and those without (group II). We measured serum MBL levels by using enzyme-linked immunosorbant assay and genotyped 4 single nucleotide polymorphisms of the MBL2 gene (226G>A in exon 1, -554G>C, -431A>C, and -225G>C in the promoter) by using TaqMan assays. Fifty-nine subjects (15.5%) were previously diagnosed with AR/BA, and 64 subjects (16.8%) complained of WRS. No significant differences were found in serum MBL levels between groups I and II. However, in group II subjects, but not in group I subjects, the serum MBL levels were significantly higher in bakery workers with WRS than in those without. In addition, the serum MBL levels were significantly different according to genetic polymorphisms of the MBL2 gene and its haplotypes. In conclusion, serum MBL, affected by genetic polymorphisms, may be associated with WRS in bakery workers with no previous history of AR/BA.

MBL2 polymorphisms and the risk of asthma: A meta-analysis

BACKGROUND

The association between MBL2 gene polymorphisms and the risk of asthma has been evaluated in multiple studies; however, the results are inconsistent.

OBJECTIVE

To perform a meta-analysis to explore whether MBL2 gene polymorphisms were associated with the risk of asthma.

METHODS

We searched PubMed, Web of Science, and Cochrane Library to find relevant articles published up to March 2016. Nine studies, including 2066 cases and 2183 controls, were included in the meta-analysis. The strength of association was evaluated by odds ratio (OR) with 95% confidence interval (CI).

RESULTS

The results reveal that MBL2 gene polymorphisms (codon 54 A/B, -550 H/L or -221 X/Y) were not associated with the risk of asthma (codon 54 A/B: BB+AB vs AA: OR, 1.02; 95% CI, 0.85-1.23; -550 H/L: LL+HL vs HH: OR, 0.81; 95% CI, 0.63-1.03; -221 X/Y: XX+YX vs YY: OR, 0.85; 95% CI, 0.69-1.04). Subgroup analysis by ethnicity implied that the MBL2 codon 54 A/B polymorphism was not significantly associated with the risk of asthma in Asians (BB+AB vs AA: OR, 0.95; 95% CI, 0.70-1.29) or whites (BB+AB vs AA: OR, 1.07; 95% CI, 0.84-1.35).

CONCLUSION

The results indicated that MBL2 gene polymorphisms (codon 54 A/B, -550 H/L or -221 X/Y) may be not associated with the risk of asthma.

Effects of MBL2 polymorphisms in patients with diisocyanate-induced occupational asthma

Diisocyanate (DI) is the most common cause of occupational asthma (OA) in Korea. Mannose-binding lectin (MBL) initiates the lectin complement activation pathway following oxidative stress and plays an important role in the regulation of inflammatory processes. To determine whether there is a genetic association between MBL2 polymorphisms and DI-OA, 99 patients with DI-OA, 99 asymptomatic exposed controls (AECs) and 144 unexposed normal controls were enrolled in this study. Three polymorphisms (-554 G>C, -431A>C and -225 G>C) in the MBL2 promoter were genotyped, and serum MBL levels were determined by enzyme-linked immunosorbent assay. Functional variabilities in the promoter polymorphisms were analyzed by a luciferase reporter assay and electrophoretic mobility shift assay (EMSA). A significantly higher frequency of haplotype (ht) 2 [CAG] was noted in the DI-OA group compared with the AEC group (P=0.044). The patients with DI-OA carrying ht2 [CAG] had significantly lower PC20 methacholine levels (P<0.001) than the non-carriers. The serum MBL levels were significantly higher in the DI-exposed subjects (both the DI-OA patients and AECs) carrying ht1 [GAG] (P=0.028). Luciferase activity was significantly enhanced in ht1 [GAG] compared with ht2 [CAG] in human hepatocarcinoma cells (Hep3B) (P=0.002). The EMSA showed that a -554G probe produced a specific shifted band compared with the -554C probe. These findings suggest that decreased serum MBL levels due to polymorphisms of the MBL2 gene may increase susceptibility to the development of DI-OA in DI-exposed individuals.

Mannose-binding lectin 2 gene polymorphism and lung damage in primary ciliary dyskinesia

BACKGROUND

Mannose-binding lectin (MBL) plays an important role in innate immunity and has been reported to be associated with the age-related decline in lung function in cystic fibrosis.

HYPOTHESIS

MBL polymorphisms are associated with lung function decline in Primary Ciliary Dyskinesia (PCD).

METHODS

We performed sputum microbiology, spirometry pre- and post-administration of salbutamol, ciliary motion analysis, ultrastructural assessment of cilia, ciliogenesis in culture, and chest high resolution computed tomography in children with a clinical history of respiratory tract infections and/or presence of bronchiectasis suggestive of PCD or secondary ciliary dyskinesia (SCD). All subjects were evaluated for single nucleotide polymorphisms in the gene encoding MBL-2.

RESULTS

The diagnosis of PCD was established in 45 subjects, while in the remaining 53 the diagnosis was SCD. A significant bronchodilator response was observed only in PCD associated with the MBL2-3 genotype, which is known to be associated with low/undetectable MBL serum levels. Also, bronchiectasis severity was significantly greater in subjects with MBL2-3 in both PCD and SCD. No other association was found between MBL genotypes and clinical findings.

CONCLUSIONS

MBL plays a relatively minor role as a disease modifier in PCD. A similar finding in SCD supports the likely significance of this result.

Role of infections in the induction and development of asthma: genetic and inflammatory drivers

Genetic and environmental factors interact to initiate and even maintain the course of asthma. As one of the highly risky environmental factors, infections in predisposed individuals can promote asthma development and exacerbations and/or prolong symptoms. This review will describe our current understanding of the genetic markers of innate immunity in the induction and development of asthma, the diverse roles of infections in modulating allergic inflammation, host susceptibility to infections and subsequent acute exacerbations in an allergic setting, and the therapeutic or preventive implications of existing knowledge. Current challenges and future directions in basic and clinical research of asthma are also discussed.

Association between low levels of Mannan-binding lectin and markers of autoimmune thyroid disease in pregnancy

Functional deficiency of mannan-binding lectin (MBL) has been associated with adverse pregnancy outcome. Adverse events during pregnancy have also been described in women with autoimmune thyroid diseases (AITD), and thyroid hormones have been shown to influence serum levels of MBL. Therefore, the aim of this study was to analyse the impact of MBL-deficiency on the outcome of pregnancy in relation to the presence of AITD. Almost one year after delivery, we assessed serum MBL levels and MBL2-genotypes in 212 women positively screened for AITD in pregnancy. In 103 of these women, we could also measure MBL levels in frozen serum samples from the 9-12^th gestational week, obtaining 96 pairs of MBL values (pregnancy vs. follow-up). As controls, 80 sera of pregnant women screened negatively for AITD were used. MBL2-genotyping was performed using multiplex PCR. Women with thyroid dysfunction and/or thyroid peroxidase antibodies (TPOAb) had lower MBL levels during pregnancy than controls, (3275 vs. 5000 ng/ml, p<0.05). The lowest levels were found in women with elevated thyroid-stimulating hormone (TSH) levels in the absence of TPOAb (2207 ng/ml; p<0.01 as compared to controls). MBL2 genotype distribution did not differ between subgroups. At a median follow-up period of 17 months (range: 3–78 months) after delivery, median MBL level had decreased further to 1923 ng/ml (p<0.0001) without significant changes in TSH. In an explorative survey, functional MBL-deficiency was neither linked to a history of spontaneous abortion, nor other obstetric complications, severe infections throughout life/pregnancy or antibiotics use in pregnancy. In conclusion, hypothyroidism during pregnancy is associated with decreased MBL levels, and the levels decreased further after delivery.

Association of MBL2 polymorphism with asthma after bronchiolitis in infancy

BACKGROUND

Mannose-binding lectin (MBL) is a component of innate immunity and has been linked with the pathogenesis of asthma. The aim of the present study was to evaluate the association of MBL genotypes with preschool asthma and allergy in children with bronchiolitis in early infancy.

METHODS

In all, 205 infants were hospitalized for bronchiolitis at <6 months of age. Asthma and allergy were studied from a total of 166 children at 6.4 years (mean). A total of 141 (85%) frozen whole blood samples were available for MBL genotyping and MBL2 gene mutations were determined on pyrosequencing for detection of three single-nucleotide polymorphisms.

RESULTS

Ninety-five children (67.4%) had the wild-type MBL genotype A/A and 46 had A/O or O/O genotypes. Asthma was present in 16 children (11.3%) at 5-7 years of age. Nine children (19.6%) with non-AA genotype had asthma (vs 7.4% of those with genotype AA, P= 0.03). The result remained significant after adjustment for age, gender and atopy. There were no significant associations between MBL genotypes and asthma at any age before the study. Atopic dermatitis, allergic rhinitis or paternal and/or maternal asthma had no significant associations with MBL genotypes.

CONCLUSIONS

The variant non-A/A MBL genotype is associated with asthma after bronchiolitis in infancy, but not earlier than at 5-7 years of age.

Association of CFTR gene mutation with bronchial asthma

Mutation on both the copies of cystic fibrosis transmembrane conductance regulator (CFTR) gene results in cystic fibrosis (CF), which is a recessively transmitted genetic disorder. It is hypothesized that individuals heterozygous for CFTR gene mutation may develop obstructive pulmonary diseases like asthma. There is great heterogeneity in the phenotypic presentation and severity of CF lung disease. This could be due to genetic or environmental factors. Several modifier genes have been identified which may directly or indirectly interact with CFTR pathway and affect the severity of disease. This review article discusses the information related to the association of CFTR gene mutation with asthma. Association between CFTR gene mutation and asthma is still unclear. Report ranges from studies showing positive or protective association to those showing no association. Therefore, studies with sufficiently large sample size and detailed phenotype are required to define the potential contribution of CFTR in the pathogenesis of asthma.

Does mannose-binding lectin have a role in adult Turkish patients with nasal polyposis?

OBJECTIVE

Mannose-binding lectin is an important component of innate immunity; it initiates the lectin pathway of complement activation critical for innate immunity. Failure of local innate defenses may result in defective responses that lead to the persistent carriage of microorganisms or ongoing inflammation. This study investigated the role of mannose-binding lectin levels and the frequency of the 6 functional mannose-binding lectin polymorphisms in Turkish individuals with nasal polyposis.

STUDY DESIGN

A case-control study.

SETTING

University hospital.

SUBJECTS AND METHODS

Fifty-one patients with nasal polyposis and 53 healthy controls were enrolled. Serum mannose-binding lectin levels were obtained by enzyme-linked immunosorbent assay (ELISA) using the mannose-binding lectin oligomer ELISA kit. Mannose-binding lectin 2 genotyping was performed by isolating the genomic DNA from leukocytes.

RESULTS

Mean mannose-binding lectin levels were 1693.2 and 1887.8 in the patient and control group, respectively. Although mannose-binding lectin levels were lower in the patient group, the difference was not statistically significant (P > .05). No overall association was observed between the mannose-binding lectin genotype and susceptibility to nasal polyposis (95% confidence interval = 0.716-4.389, odds ratio = 1.773). The mutant allele frequencies of the 3 structural polymorphisms did not differ significantly between the nasal polyposis patients and the controls (P = .659).

CONCLUSIONS

Mannose-binding lectins are not involved in the pathogenesis of nasal polyposis in adult Turkish patients, but additional research is needed for further comment.

An overlapping syndrome of allergy and immune deficiency in children

Recurrent airway inflammations in children are an important clinical problem in pediatric practice. An essential challenge is differentiation between allergic background and immune deficiency, which is a difficult task taking into consideration individual predisposition to atopy, immune system maturation in the early childhood, as well as exposition to environmental allergens and microbial antigens. In this paper relationship between selected elements of innate and adaptive immunity, such as pattern-recognition receptors, complement components, dendritic cells, as well as immunoglobulins, and regulatory T lymph cells has been discussed. Particular attention has been paid to these mechanisms of the immune response which, depending on settings and timing of activation, predispose to allergy or contribute to tolerogenic phenotype. In the context of multifactorial conditioning of the innate and adaptive immunity governing the ultimate response and associations between allergy and immune deficiencies, these phenomena should be considered as pathogenetically not precluding, but as an overlapping syndrome.

Association of genetic variants of mannan-binding (MBL) lectin-2 gene, MBL levels and function in ulcerative colitis and Crohn's disease

Ulcerative colitis and Crohn's disease are the two major forms of inflammatory bowel disease (IBD). A series of reports have hypothesized interplay of genetic and environmental factors in the pathogenesis of IBD. Polymorphism in the mannan-binding lectin-2 (MBL-2) gene is known to affect the structural assembly and function thereby predisposing subjects to various diseases. The present study was designed to evaluate effect of MBL-2 gene polymorphism on MBL levels and function in IBD patients. Genomic DNA was isolated from blood samples collected from 157 ulcerative colitis, 42 Crohn's disease and 204 control subjects. Genotyping for different polymorphic sites at exon1 of MBL-2 gene was performed by refractory mutation system-PCR and amplification followed by restriction digestion (PCR-RFLP). Serum MBL concentration and C4 deposition levels were estimated using ELISA. Mannan-binding lectin-2 genotypic variants were calculated in IBD and healthy controls. The frequency of single nucleotide polymorphisms at codon 54 was significantly higher in ulcerative colitis patients than controls (P < 0.0001). Ulcerative colitis patients with 'codon 54'-variation showed low serum MBL concentrations coupled with altered MBL function compared to controls. In conclusion, single nucleotide polymorphism in the MBL-2 gene is an important risk factor significantly affecting MBL levels and function in the development of ulcerative colitis among Indians.

Genotypes coding for low serum levels of mannose-binding lectin are underrepresented among individuals suffering from noninfectious systemic inflammatory response syndrome

Gene polymorphisms, giving rise to low serum levels of mannose-binding lectin (MBL) or MBL-associated protease 2 (MASP2), have been associated with an increased risk of infections. The objective of this study was to assess the outcome of intensive care unit (ICU) patients with systemic inflammatory response syndrome (SIRS) regarding the existence of functionally relevant MBL2 and MASP2 gene polymorphisms. The study included 243 ICU patients with SIRS admitted to our hospital, as well as 104 healthy control subjects. MBL2 and MASP2 single nucleotide polymorphisms were genotyped using a sequence-based typing technique. No differences were observed regarding the frequencies of low-MBL genotypes (O/O and XA/O) and MASP2 polymorphisms between patients with SIRS and healthy controls. Interestingly, ICU patients with a noninfectious SIRS had a lower frequency for low-MBL genotypes and a higher frequency for high-MBL genotypes (A/A and A/XA) than either ICU patients with an infectious SIRS or healthy controls. The existence of low- or /high-MBL genotypes or a MASP2 polymorphism had no impact on the mortality rates of the included patients. The presence of high-MBL-producing genotypes in patients with a noninfectious insult is a risk factor for SIRS and ICU admission.

L-ficolin (ficolin-2) insufficiency is associated with combined allergic and infectious respiratory disease in children

We previously reported an association between relative L-ficolin deficiency and recurrent respiratory infections co-existing with allergic disorders in children. To confirm and extend this preliminary finding, we performed a prospective study on children of a similar age (mean 8.9 years) designed to establish whether the principal relationship was with infection or allergy. Serum L-ficolin values in healthy children were normally distributed with a mean value of 3838 ng/ml. L-ficolin concentrations were generally lower in patients with asthma and/or allergic rhinitis with (mean 3413 ng/ml; p=0.02) or without (3512 ng/ml; p<0.07) respiratory infections, but not in patients with respiratory infections without allergic disease (3623 ng/ml; p=0.2). The lower average values in the group comprised of children with respiratory allergy and infections were largely due to a high proportion of very low values: 18.3% had values below 2150 ng/ml compared to only 5.5% of healthy controls (OR=3.9; p=0.01). This relationship was not apparent in the groups characterized by allergy without infection or infections without allergy. An association between mannan-binding lectin (MBL) insufficiency and recurrent respiratory infections was also confirmed. One of the patients was MASP-2 deficient, evidenced both by MASP2 genotyping and by lectin pathway activity measurement. In conclusion, L-ficolin may confer some protection from microorganisms that exacerbate allergic inflammation in the lung and its relative deficiency may contribute to enhanced susceptibility to respiratory infections. MBL insufficiency and MASP-2 deficiency are risk factors for recurrence of infections independently of allergic disease.

Mannose-binding lectin cord blood levels and respiratory symptoms during infancy: a prospective birth cohort study

Respiratory infections cause considerable morbidity during infancy. The impact of innate immunity mechanisms, such as mannose-binding lectin (MBL), on respiratory symptoms remains unclear. The aims of this study were to investigate whether cord blood MBL levels are associated with respiratory symptoms during infancy and to determine the relative contribution of MBL when compared with known risk factors. This is a prospective birth cohort study including 185 healthy term infants. MBL was measured in cord blood and categorized into tertiles. Frequency and severity of respiratory symptoms were assessed weekly until age one. Association with MBL levels was analysed using multivariable random effects Poisson regression. We observed a trend towards an increased incidence rate of severe respiratory symptoms in infants in the low MBL tertile when compared with infants in the middle MBL tertile [incidence rate ratio (IRR) = 1.59; 95% confidence interval (CI): 0.95-2.66; p = 0.076]. Surprisingly, infants in the high MBL tertile suffered significantly more from severe and total respiratory symptoms than infants in the middle MBL tertile (IRR = 1.97; 95% CI: 1.20-3.25; p = 0.008). This association was pronounced in infants of parents with asthma (IRR = 3.64; 95% CI: 1.47-9.02; p = 0.005). The relative risk associated with high MBL was similar to the risk associated with well-known risk factors such as maternal smoking or childcare. In conclusion the association between low MBL levels and increased susceptibility to common respiratory infections during infancy was weaker than that previously reported. Instead, high cord blood MBL levels may represent a so far unrecognized risk factor for respiratory morbidity in infants of asthmatic parents.

Mannose-binding lectin 2 gene polymorphism in recurrent herpes simplex virus 2 infection

Mannose-binding lectin (MBL) is a complement component and an opsonic factor recognizing and binding to herpes simplex virus 2 (HSV-2). In this study, we assessed the effect of MBL2 genotypes on the risk of recurring HSV-2 infection. The MBL2 structural variant genotype (A/O or O/O) was more common among the patients with recurrent HSV-2 infection compared with healthy controls (47% vs 26%, respectively; odds ratio [OR] = 2.6, 95% confidence interval [CI] 1.3-4.9; p = 0.005) or controls positive for HSV-2 antibodies (15%; OR 4.9, 95% CI 1.5-16; p = 0.007). Thus, we conclude that the MBL2 structural variant genotype, possibly through impaired recognition of HSV-2, seems to predispose individuals to the development of recurring HSV-2 infection.

Relation among mannose-binding lectin 2 genotype, beta-cell autoantibodies, and risk for type 1 diabetes in Finnish children

Mannose-binding lectin (MBL) is a key mediator of innate immunity, the insufficiency of which is caused by point mutations in the MBL2 gene. MBL insufficiency is associated with increased susceptibility to infections and certain autoimmune diseases, but its impact in the pathogenesis and risk of type 1 diabetes (T1D) is controversial. We investigated the significance of the MBL2 genotype on the risk of T1D in a Finnish study population comprising 470 diabetic children and 501 controls. Furthermore, the effect of MBL2 gene polymorphism on the emergence of beta-cell autoantibodies in 289 unaffected children with human leukocyte antigen-conferred susceptibility to T1D was assessed. MBL genotype had no significant effect on the risk or onset age of T1D. However, children with the biallelic variant genotype reflecting total MBL deficiency tested positive more frequently for > or =3 autoantibodies compared with children with another genotype (odds ratio = 6.0, 95% confidence interval 1.3-28; p = 0.013). In conclusion, the MBL2 genotype did not affect susceptibility to T1D in children, and this finding does not support previous reports implicating a role of the MBL2 genotype as a factor predisposing to T1D. The association of the biallelic variant genotype with positivity for multiple autoantibodies suggests that intermolecular epitope spreading may be linked with impaired clearance of autoantigens as a result of MBL deficiency.

MBL2 variants in relation to common childhood infections and atopy-related phenotypes in a large German birth cohort

Mannose-binding lectin (MBL) is considered an important component of innate immunity. Four functional MBL2 alterations in codons 52, 54, 57 and in the promoter at position c.1-290 are correlated with significantly lowered MBL serum levels. These variants have been associated with susceptibility to a variety of infectious agents as well as with various immunologic disorders including asthma. To reassess these observations, we analysed the four above mentioned MBL2 variants in 749 children, who were recruited by the German Multicenter Allergy Study and were prospectively evaluated for common respiratory childhood infections and atopy-related phenotypes from birth up to the age of 11 yr. We performed genotyping by melting curve analysis using fluorescence resonance energy transfer probes and the LightCycler. In contrast to previous studies, we found an association of MBL2 variants neither with the frequency of common respiratory childhood infections at any age nor with asthma or other atopy-related phenotypes. Our data suggest that MBL deficiency does not represent a pre-disposing factor for respiratory infections or atopic disorders in infants and children.

Mannose binding lectin gene polymorphisms and asthma

BACKGROUND

Bronchial asthma is a chronic inflammatory disorder of the airways. Recently, it has been suggested that complement plays significant roles in asthma. Mannose-binding lectin (MBL) is one of the key molecules in complement activation pathways that are associated with several infectious and immune disorders.

SUBJECTS AND METHOD

To investigate whether MBL plays roles in asthma, we analysed MBL2 polymorphisms (allele B, H/L and Y/X) and plasma MBL levels in a Japanese adult population including 232 healthy controls and 579 asthmatics.

RESULTS

Although there was linkage disequilibrium among the three polymorphisms, each polymorphism significantly affects serum MBL levels independently. However, there were no significant differences between asthmatics and controls in MBL2 genotype distribution and in MBL concentrations [1.47+/-0.07(SE) mg/L for asthmatics and 1.66+/-0.14 mg/L for controls, P=0.2]. MBL levels and genotype have no significant relationship with serum IgE, pulmonary functions, and the severity of asthma.

CONCLUSION

Although plasma MBL levels depend on the MBL2 polymorphisms, these polymorphisms and plasma MBL levels are not associated with the asthma phenotype.

Variant mannose-binding lectin 2 genotype is a risk factor for reactive systemic amyloidosis in rheumatoid arthritis

OBJECTIVE

The aim of this study was to investigate whether polymorphism of the mannose-binding lectin 2 (MBL2) gene is related to the occurrence of systemic AA amyloidosis in patients with rheumatoid arthritis (RA).

METHODS

MBL2 structural gene polymorphisms at codon 52 (CGT-->TGT, Arg-->Cys; D), codon 54 (GGC-->GAC, Gly-->Asp; B) and codon 57 (GGA-->GAA, Gly--> Glu; C), and MBL2 promoter region polymorphism at position -221 (G-->C) were examined in 57 patients with RA complicated by biopsy-proven reactive amyloidosis and 51 control RA patients without amyloid.

RESULTS

A strong association was found between the presence of a structural MBL2 gene variant O (B, D or C) and the occurrence of amyloidosis in RA patients: 29 of 57 (50.9%) of the RA patients with amyloid had a variant allele compared with 12 of 51 (23.5%) of the RA patients without amyloid (OR 3.37, 95% CI 1.47-7.72; P = 0.004).

CONCLUSION

We conclude that variant MBL2 structural genotype constitutes a significant risk factor for reactive amyloidosis in RA and that the increased risk is probably related to MBL-mediated impairment of mononuclear phagocyte function.

Mannose-binding lectin polymorphisms and pulmonary outcome in premature neonates: a pilot study

OBJECTIVE

Mannose-binding lectin (MBL2) is a collectin molecule able to activate the complement system and the subsequent inflammatory mechanisms. Several MBL2 genetic variants have been described, including the six variants studied in this report, which are those analyzed in most detail in the medical literature.

DESIGN

The present study analyzes the prevalence of MBL2 gene variants in preterm newborns and associates individual genotypes with pulmonary outcome variables. All polymorphisms were analyzed by means of a commercially available reverse dot-blot kit.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS AND PARTICIPANTS

Seventy-five consecutive preterm newborns.

MEASUREMENTS AND RESULTS

Two variants were particularly analyzed: -550G > C and R52C. The first one is known to be associated with lower protein synthesis when included in specific haplotypes. The homozygous and heterozygous -550G > C mutations were significantly associated with protective effects regarding different lung outcome variables, including shorter duration of mechanical ventilation, hours of continuous positive airway pressure and lower number of hemotransfusions. In contrast, the heterozygous R52C mutation was associated with unfavorable outcome, including higher bronchopulmonary dysplasia prevalence. Multivariate logistic regression analysis showed that these associations were independent of gestational age and birth weight. In addition, four groups of patients were defined on the basis of haplotype combinations. Those known to be associated with low serum MBL2 levels were linked to a better outcome in terms of factors such as hours of mechanical ventilation, continuous positive airway pressure, number of hemotransfusions and bronchopulmonary disease development.

CONCLUSIONS

The four haplotype combination groups may have a potential diagnostic use as opposite risk factors for lung disease of prematurity.

Association between mannose-binding lectin deficiency and septic shock following acute pyelonephritis due to Escherichia coli

Structural and promoter MBL2 gene polymorphisms responsible for low MBL levels are associated with increased risk of infection. The objective of this study was to assess the possible association between polymorphisms of the MBL2 gene and the incidence of septic shock and bacteremia in patients with acute pyelonephritis due to Escherichia coli. The study included 62 female patients with acute pyelonephritis due to E. coli who required hospital admission, as well as 133 healthy control subjects. Six single-nucleotide polymorphisms (-550 G/C, -221 C/G, +4 C/T, codon 52 CGT/TGT, codon 54 GGC/GAC, and codon 57 GGA/GAA) in the MBL2 gene were genotyped by using a sequence-based typing technique. No significant differences were observed in the frequencies for low-expression MBL2 genotypes (O/O and LXA/O) between patients with acute pyelonephritis and healthy controls. Patients with acute pyelonephritis and septic shock had a higher incidence of low-expression MBL2 genotypes than patients with acute pyelonephritis without septic shock (odds ratio = 9.019, 95% confidence interval = 1.23 to 65.93; P = 0.03). No association was found between bacteremic acute pyelonephritis and low-expression MBL2 genotypes. We found that low-expression MBL2 genotypes predispose to septic shock but not to bacteremia in patients with E. coli-induced acute pyelonephritis. Determination of MBL2 polymorphisms could be useful for assessing the risk of septic shock in women undergoing acute pyelonephritis.

Genetic association study between mbl2 and asthma phenotypes in Chinese children

Mannose-binding lectin (MBL), a member of the innate immune system, initiates complement deposition on microbial surfaces. MBL deficiency is associated with severe respiratory infections. Polymorphisms in the MBL gene (mbl2) were associated with the susceptibility and severity of autoimmune diseases. This study investigated whether mbl2 polymorphisms at positions -550 and -221 and at codon-54 are associated with asthma phenotypes in Chinese children. Asthmatics aged 5-18 yr and non-allergic controls were eligible, and their plasma total and allergen-specific immunoglobulin E (IgE) concentrations were measured by micro-particle immunoassay and fluorescent enzyme immunoassay. mbl2 polymorphisms were genotyped by restriction fragment length polymorphism. Three hundred and seventeen asthmatic children and 140 controls were recruited, with their mean (s.d.) log-transformed plasma total IgE being 2.61 (0.61) and 1.77 (0.77), respectively (p < 0.0001). Polymorphisms at -550 and codon-54 (p < 0.0001 for both) but not at -221 (p = 0.534) of mbl2 were significantly associated with plasma MBL concentrations. mbl2 genotypes were not associated with asthma, atopy, sensitization to individual aeroallergens or spirometric variable. Subjects with LYB haplotype had the lowest plasma MBL concentrations (p < 0.0001), but two- and three-loci mbl2 haplotypes were also not associated with asthma diagnosis. However, patients with LY and LYB haplotypes were less likely to be atopic (p = 0.006 and 0.031). Subjects with LY and LYA were also less likely to be sensitized to cockroach (p = 0.035 and 0.047). The latter three associations became insignificant when adjusted for multiple comparisons. Despite the importance of MBL in innate immunity, our mbl2 polymorphisms only show weak association with asthma and atopy in children.