Mannose-binding Lectin Alleles Research Articles

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

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

High rate of in-stent restenosis after coronary intervention in carriers of the mutant mannose-binding lectin allele

BackgroundIn-stent restenosis occurs in 10–30% of patients following bare metal stent (BMS) implantation and has various risk factors. Mannose-binding lectin (MBL) is known to have effect on the progression of atherosclerosis. Single nucleotide polymorphisms (SNP) of the MBL2 gene intron 1 (codon 52, 54, 57) are known to modulate the bioavailability of the MBL protein. Our aim was to identify the association of these polymorphisms of the MBL gene in the occurrence of in-stent restenosis after coronary artery bare metal stent implantation.MethodsIn a non-randomized prospective study venous blood samples were collected after recoronarography from 225 patients with prior BMS implantation. Patients were assigned to diffuse restenosis group and control group based on the result of the coronarography. MBL genotypes were determined using quantitative real-time PCR. Proportion of different genotypes was compared and adjusted with traditional risk factors using multivariate logistic regression.ResultsAverage follow-up time was 1.0 (+ − 1.4) year in the diffuse restenosis group (N = 117) and 2.7 (+ − 2.5) years in the control group (N = 108). The age, gender distribution and risk status was not different between study groups. Proportion of the MBL variant genotype was 26.8% (29 vs. 79 normal homozygous) in the control group and 39.3% (46 vs. 71 normal homozygous) in the restenosis group (p = 0.04). In multivariate analysis the mutant allele was an independent risk factor (OR = 1.96, p = 0.03) of in-stent restenosis.ConclusionsMBL polymorphisms are associated with higher incidence of development of coronary in-stent restenosis. The attenuated protein function in the mutant allelic genotype may represent the underlying mechanism.

Mannose binding lectin (MBL) 2 gene polymorphism & its association with clinical manifestations in systemic lupus erythematosus (SLE) patients from western India.

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease characterized by production of autoantibodies. Mannose binding lectin (MBL) is an important element of the innate defense system. t0 he present study was undertaken to determine whether variant alleles in MBL2 gene were associated with disease severity in SLE patients. The MBL alleles [-550, -221, +4, Codon 52, Codon 54 and Codon 57] were studied by PCR- RFLP (restriction fragment length polymorphism) method in 100 SLE patients fulfilling ACR (American College of Rheumatology) criteria along with 100 healthy controls. SLE disease activity was evaluated using SLE Disease Activity Index (SLEDAI) score. Homozygosity for MBL variant allele (O/O) was observed in 24 per cent of the SLE patients compared to 16 per cent of the normal controls, while no difference was found for heterozygosity (A/O) (37 vs 35%). A significant difference was reported in incidence of double heterozygosity for mutant allele B and D (B/D) among SLE patients as against control group ( p = 0.015). MBL genotypes did not show any association with renal involvement. In this study from western India, MBL gene polymorphism showed an influence as a possible risk factor for susceptibility to SLE, but had no direct effect on disease characteristics. Further studies need to be done on a larger number of SLE patients in different regions of the country.

Mannose-Binding Lectin Gene Polymorphisms in Infants with Bronchiolitis and Post-Bronchiolitis Wheezing

Mannose-binding lectin (MBL) encoded by the MBL2 gene, is an important component of the innate immunity. Low levels have been linked with respiratory infections and both high and low levels with allergy and asthma. The aims of the study were to evaluate the connection between polymorphisms of the MBL2 gene and viral findings, clinical characteristics and subsequent wheezing in young infants with bronchiolitis. In all, 129 full-term infants hospitalized for bronchiolitis at age less than 6 months have been followed-up until the mean age of 1.5 years. The genotyping of the MBL2 gene mutations was made by pyrosequencing for a simultaneous detection of three single nucleotide polymorphisms (SNP). The MBL genotypes or allele frequencies had no significant associations with clinical characteristics of bronchiolitis. The 41 children with variant genotypes were more often infected by multiple viruses (21.9%, p = 0.047) than children with wild-type A/A genotypes (9.1%). In addition, more children with variant genotypes (31.7%, p = 0.016) had used corticosteroids because of post-bronchiolitis wheezing, compared to those with wild-type A/A genotypes (13.6%). No other significant associations with viral findings or post-bronchiolitis outcomes were found. Preliminary evidence was found that the variant non-A/A genotypes may be associated with susceptibility to multiple viral infections and more severe post-bronchiolitis wheezing requiring treatment with corticosteroids.

C7 Deficiency and Meningococcal Infection Susceptibility in Two Spanish Families

In this work, we report the genetic basis of C7 deficiency in two different Spanish families. In family 1, by using exon-specific polymerase chain reaction and sequencing, a recently described mutation was found in homozygosity in the patient; a single base change in exon 15 (C2107T) leading to a stop codon that causes truncation of the C-terminal portion of C7 (Q681X). Patient's father, mother and sister were heterozygous for this mutation. Interestingly, patient's parents were not related. In family 2, a new single base mutation in exon 2 (G90A), leading to a stop codon that causes the premature truncation of C7 (W8X), was found in the patient, mother and sister 1. Additionally, patient 2, her father and sisters, displayed a missense mutation in exon 9 (G1135C) resulting in a change of aminoacid (G357R). Although sister 1 bore the same mutations in the C7 gene that patient 2, she remains asymptomatic. Because both mutations were found in the patient and her sister, we analyse other defence mechanisms such as FcgammaR polymorphisms as well as mannose-binding lectin alleles (MBL2 gene) and MBL levels. Results showed that both siblings bore identical combinations of FcgammaR allotypes and different MBL2 alleles, exhibiting patient 2 a MBL-insufficient genotype. Normal MBL levels were found in patient 1 and in two previously studied C7-deficient siblings, suggesting the involvement of other mechanisms of immunity distinct of FcgammaR variants and the MBL pathway, for the absence of meningococcal recurrent infections in certain C7-deficient individuals.

Mannose-binding lectin gene polymorphisms in Brazilian patients with systemic lupus erythematosus

The mannose-binding lectin gene (MBL-2) has emerged as a candidate for systemic lupus erythematosus susceptibility, but studies in Brazilian population have not been conducted. To examine potential associations of mannose-binding lectin alleles G57E, G54D, IVSnt5, R52C and R52H with susceptibility to and clinical expression of systemic lupus erythematosus in southern Brazilian patients, we conducted a case-control study with 327 consecutive patients with diagnosis of systemic lupus erythematosus and 345 healthy controls. Genotyping was performed by restriction fragment length polymorphism-polymerase chain reaction assay. A statistically significant difference in the frequencies of allele R52C was observed in European-derived systemic lupus erythematosus patients when compared with controls (9.6% vs. 3.3%, p < 0.001, odds ratio: 3.15, 95% confidence interval: 1.76-5.62, p < 0.05). The frequencies of alleles G54D and G57E were not different between European-derived systemic lupus erythematosus patients and controls. There were no differences between clinical and laboratory features in systemic lupus erythematosus patients according to the presence or absence of mannose-binding lectin allelic variants. These results support an increased risk of systemic lupus erythematosus in European-derived individuals carrying allele R52C. Patients carrying this allele have an approximately three-fold higher odds ratio of developing systemic lupus erythematosus when compared with controls. Our data do not support associations between the mannose-binding lectin allelic variants studied and clinical expression of systemic lupus erythematosus.

Mannose-binding lectin polymorphisms in common variable immunodeficiency

Common variable immunodeficiency (CVID) is a heterogeneous group of disorders, characterized by hypogammaglobulinemia and increased susceptibility to infections, autoimmunity and malignancies. This study was performed to analyze the Mannose-binding lectin (MBL) polymorphisms in Iranian patients with CVID. Thirty-five CVID patients who were treated at Children's Medical Center and 100 matched controls were enrolled in this study. Sixth single-nucleotide polymorphisms of the MBL gene were analyzed using PCR-SSP method. Comparison of MBL exon 1 coding alleles between patients and controls revealed that A allele (wild-type) was significantly decreased in CVID group, whereas B allele was overrepresented in the patient group. High frequency of heterozygous (A/O) in the patient group and high frequency of homozygous for wild-type coding regions in the control group were detected. Comparison of MBL haplotype promoters between CVID patients and controls showed that LYPB haplotype was significantly overrepresented in the CVID group. Mutant and low-producing MBL alleles and haplotypes might reflect as an associated genetic factor in CVID patients, which could play as a susceptibility factor in CVID.

Association of Mannose-Binding Lectin Gene Polymorphism but Not of Mannose-Binding Serine Protease 2 with Chronic Severe Aortic Regurgitation of Rheumatic Etiology

N-Acetylglucosamine (GlcNAc) is the major immunoepitope of group A streptococcal cell wall carbohydrates. Antistreptococcal antibodies cross-reactive with anti-GlcNAc and laminin are present in sera of patients with rheumatic fever. The cross-reactivity of these antibodies with human heart valvular endothelium and the underlying basement membrane has been suggested to be a possible cause of immune-mediated valve lesion. Mannose-binding lectin (MBL) encoded by the MBL2 gene, a soluble pathogen recognition receptor, has high affinity for GlcNAc. We postulated that mutations in exon 1 of the MBL2 gene associated with a deficient serum level of MBL may contribute to chronic severe aortic regurgitation (AR) of rheumatic etiology. We studied 90 patients with severe chronic AR of rheumatic etiology and 281 healthy controls (HC) for the variants of the MBL2 gene at codons 52, 54, and 57 by using a PCR-restriction fragment length polymorphism-based method. We observed a significant difference in the prevalence of defective MBL2 alleles between patients with chronic severe AR and HC. Sixteen percent of patients with chronic severe AR were homozygotes or compound heterozygotes for defective MBL alleles in contrast to 5% for HC (P = 0.0022; odds ratio, 3.5 [95% confidence interval, 1.6 to 7.7]). No association was detected with the variant of the MASP2 gene. Our study suggests that MBL deficiency may contribute to the development of chronic severe AR of rheumatic etiology.

Mannose-Binding Lectin Genotype and Invasive Pneumococcal Infection

Invasive pneumococcal disease is a serious infection that primarily affects young children and elderly or immunocompromised persons, but it also can affect healthy persons. Mannose-binding lectin (MBL) is a mediator of innate host immunity that activates the complement pathway and directly opsonizes pathogens. Variant structural codon and promoter MBL alleles have been associated with susceptibility to infections. Sixty-three Belgian patients with invasive pneumococcal disease and 162 healthy Belgian controls were genotyped for MBL alleles. We found a nonsignificant increased risk between the MBL structural codon variants (52, 54, and 57) and invasive pneumococcal disease. Combining our data with similar data from Kronberg et al. (J Infect Dis 2002;185:1517-20) indicated that MBL structural variants contributed to a small but significant increased risk of invasive pneumococcal disease. On the other hand, the -221 and -550 promoter allele distribution and the prevalence of the combined MBL structural and promoter -221 variant alleles were not significantly different between the patient group and the control group.

Influence of FcγRIIA and MBL polymorphisms on severe acute respiratory syndrome

Polymorphisms of human Fc γ‐receptor IIA (FcγRIIA) and mannose‐binding lectin (MBL) genes have been associated with susceptibility to or severity of some infectious diseases. In order to investigate whether these genetic factors might influence susceptibility to infection with the severe acute respiratory syndrome‐associated coronavirus (SARS‐Cov) as well as the course and severity of the infection, we evaluated polymorphisms of FcγRIIA and MBL genes in DNA samples from a group of approximately 180 people from Hong Kong who were infected with SARS‐Cov. These included 132 patients who had moderate course of SARS infection (home subgroup), 26 patients with a severe course requiring treatment in an intensive care ward (ICU subgroup) and a subgroup of 22 patients who died from SARS (deceased subgroup). A total of 200 normal blood donors from the same region were used as controls. A significant association was found between the FcγRIIA‐R/R131 genotype and a severe course of SARS, with higher frequency of homozygosity for FcγRIIA‐R/R131 in the ICU subgroup of SARS patients when compared with controls (P = 0.03; odds ratio: 3.2; 95% confidence interval: 1.1–9.1). In comparison with controls, a significant difference in linear trend distribution of FcγRIIA genotypes was seen among the severe SARS patients (ICU and deceased subgroups) without co‐morbidity, and the incidence of FcγRIIA‐H/H131 was lower in these patients as well. There were no significant differences in MBL genotypes and allele frequencies among SARS patients and controls. The study reveals that in addition to age and co‐morbidity, FcγRIIA polymorphism of individuals may also influence outcome after infection with the SARS‐Cov.

Mannose-binding lectin gene polymorphisms are associated with gestational diabetes mellitus.

Insulin resistance is a feature of gestational diabetes mellitus (GDM). Inverse correlations between indexes of insulin sensitivity and serum markers of inflammation have been observed and, particularly, TNF-alpha has been shown to be associated with the appearance of insulin resistance in pregnancy. Mannose-binding lectin (MBL) is a protein member of the collectin family. Its deficiency is genetically determined and predisposes to recurrent infections and chronic inflammatory diseases. To test the hypothesis that a genetic predisposition to a proinflammatory state could favor the appearance of GDM during pregnancy, we studied R52C and G54D polymorphisms of MBL2 gene and plasma MBL levels from 105 consecutive GDM women and 173 healthy pregnant women. An association was found between G54D and GDM [odds ratio, 2.03 (1.18-3.49); P < 0.01], and this association remained significant when the presence of both mutated alleles was considered [odds ratio, 1.76 (1.04-2.96); P < 0.05] but not for the R52C. GDM patients who carried the G54D mutation required insulin therapy more frequently (56.4 vs. 30.4%, chi(2) =5.83; P = 0.027) and had heavier infants (3326.4 +/- 546.9 vs. 3087.5 +/- 395.5 g; P < 0.05) than GDM women homozygous for the wild-type allele. An inverse correlation in GDM patients between neonatal weight and plasma MBL levels (r = -0.320; P = 0.002) was found, remaining significant after adjustment for confounding variables. In conclusion, pregnant women bearing the G54D MBL allele have a greater risk for developing GDM and having heavier infants.

Association between tubal infertility, antibodies to Chlamydia trachomatis and the Chlamydia 60kDa heat shock protein (HSP) and a mannose binding lectin (MBL) gene polymorphism in women undergoing IVF

Association between tubal infertility, antibodies to Chlamydia trachomatis and the Chlamydia 60kDa heat shock protein (HSP) and a mannose binding lectin (MBL) gene polymorphism in women undergoing IVF

Altered distribution of mannose-binding lectin alleles at exon I codon 54 in women with vulvar vestibulitis syndrome

Objectives Mannose-binding lectin (MBL) is active in the innate immune defense against microorganisms. In this study, we determined whether vulvar vestibulitis syndrome, a disorder of unknown etiology, was associated with an altered distribution of MBL alleles. Study design Buccal swabs were obtained from women with vulvar vestibulitis syndrome in New York (62) and from 2 cities in Sweden (60), as well as control women in New York (48) and Sweden (51). DNA was tested for a single nucleotide polymorphism at codon 54 in exon I by polymerase chain reaction, endonuclease digestion, and gel electrophoresis. Blood samples were also obtained from the New York women and tested by ELISA for plasma MBL concentrations. The relationships between genotype, allele frequencies, blood MBL levels, and diagnosis were analyzed by Fisher exact test and one-way analysis of variance. Results The variant MBL allele, MBL ∗B, was detected in 35.5% and 26.7% of vulvar vestibulitis patients from New York and Sweden, respectively. Only 12.5% of New York controls ( P = .007) and 9.8% of Swedish controls ( P=.01) were MBL ∗2-positive. All women, with one exception, who were positive for MBL ∗B were MBL ∗A/MBL ∗B heterozygotes. Women who carried MBL ∗B had almost a 10-fold reduction in median plasma MBL concentrations (278 ng/mL), as opposed to women who were MBL ∗A homozygotes (1980 ng/mL) ( P < .0001). Conclusion MBL ∗B carriage and reduced plasma MBL levels are more common in women with vulvar vestibulitis syndrome than in control patients, and may contribute to symptomatology in a subset of patients.

Increased incidence and severity of the systemic inflammatory response syndrome in patients deficient in mannose-binding lectin.

To determine whether pediatric PICU patients with mannose-binding lectin (MBL) gene polymorphisms associated with low levels of the functional protein have an increased risk of developing sepsis and SIRS. A prospective, observational cohort study in a 22-bed PICU in a tertiary referral centre. One hundred consecutive admissions to a PICU with at least one organ system failure longer than 12 h. Patients were classified into those with infectious or non-infectious insults as the primary reason for intensive care admission. Patients were followed to determine which developed sepsis or non-infection related SIRS using standard criteria. Of the 100 patients 50 had infectious and 50 had non-infectious insults as the precipitant for admission. 42 patients had variant MBL alleles (determined by MBL-2 gene exon 1 and promoter polymorphisms) and were significantly over-represented amongst the 59 patients that developed SIRS. This effect was not explained by differences in age, sex or ethnicity and was seen in both the infection and non-infection subgroups. In patients with infection, variant MBL alleles were associated with increased systemic response (2/15 with localised infection, 10/19 with sepsis and 12/16 with septic shock). MBL serum levels showed close concordance with the genotype and indicated that MBL levels less than 1000 ng/ml are associated with a greatly increased risk of SIRS. MBL-2 exon 1 polymorphisms with low serum levels of functional MBL protein are associated with a greatly increased risk of developing SIRS and of progression from infection to sepsis and septic shock in paediatric ICU patients.

Prospective analysis of mannose-binding lectin genotypes and coronary artery disease in American Indians: the Strong Heart Study.

Mannose-binding lectin (MBL) is a circulating immune factor responsible for opsonization of pathogens and directly activating complement. Common variations in the MBL gene are responsible for an opsonic deficiency that affects 5% to 7% of whites and are associated with increased susceptibility to infections. After a preliminary report associating these variations with coronary artery disease (CAD), we determined MBL genotypes in 3 American Indian communities experiencing an increased mortality and morbidity from CAD. We examined DNA from 434 participants in a population-based cohort, the Strong Heart Study. Genotypes for 3 common MBL coding variations and 1 promoter polymorphism were determined. The frequency of a composite genotype that conferred low MBL levels was 20.7% in 217 cases and 11.1% in matched controls without CAD. A conditional logistic regression model indicated a univariate OR for CAD of 2.3 (95% CI 1.3 to 4.2, P=0.005) for the variant genotypes. After adjustment for demographic and CAD risk factors, including type 2 diabetes mellitus, fibrinogen, triglycerides, and hypertension, the OR was 3.2 (95% CI 1.5 to 7.0, P=0.004). Variant MBL genotypes coding for markedly diminished levels of MBL are predictive of CAD. After adjustment for multiple traditional risk factors for ischemic heart disease, this association remains significant. A high prevalence of variant MBL alleles and CAD in this population suggests that potentially important public health benefits may accrue from future interventions based on these genotypes.

Inherited mannose-binding lectin deficiency as evidenced by genetic and immunologic analyses: association with severe recurrent infections

Mannose-binding lectin (MBL), an acute-phase serum protein of hepatic origin, plays an essential protective role in host innate immunity in targeting microbial pathogens for destruction via opsonization, enhancement of phagocytosis and complement activation. MBL deficiency, characterized by low serum MBL, has been attributed to genetic mutations in both structural and promoter regions of the gene coding for the protein. Concomitant MBL deficiency in patients with chronic immunologic disease has been associated with increased susceptibility to complicating infections that may hasten disease progression. Few cases of inherited MBL deficiency in adults and possible associations with recurrent infection have been reported. To address this issue, we investigated the MBL profile of four generations within a single adult family whose members have experienced a variety of persistent infections. MBL serum levels and MBL genotypes of each participating family member were ascertained by enzyme-linked immunoadsorbent assay and reverse transcriptase-polymerase chain reaction, respectively. MBL complement activation, as measured by C4b deposition against mannan-coated wells, was assayed using an enzyme-linked immunoadsorbent assay. Routine immunologic and cellular tests were carried out to evaluate the immunologic status of each family member. Six of the 7 family members screened carried one or more of the variant MBL alleles in their genotype and had correspondingly low serum MBL and reduced ability to affect C4b opsonization. Medical histories of the participating family members revealed an array of mild to severe recurrent infections despite no apparent immunodeficiency. Our studies show that MBL deficiency is an inherited characteristic and may be a crucial factor in maintaining immunologic health.

The development of asthma in children infected with Chlamydia pneumoniae is dependent on the modifying effect of mannose-binding lectin

Background Although several studies found associations between infection with Chlamydia pneumoniae and asthma, these were mainly restricted to the exacerbation of the symptoms in adults with known asthma. Data about the role of C pneumoniae in the initiation and development of asthma in children are controversial. Objective We investigated the role of C pneumoniae infection in 139 children with asthma, comparing them with 174 healthy control subjects. Furthermore, we studied the modifying effect of mannose-binding lectin (MBL) variant alleles on the susceptibility to asthma in children infected with C pneumoniae. Methods C pneumoniae–specific antibodies were measured by means of ELISA, and MBL genotypes were determined by means of PCR-RFLP. Results There were no significant differences in the percentage of children with positive results for C pneumoniae–specific antibodies between patients and control subjects. Among asthmatic children carrying variant MBL alleles, there were significantly more patients with positive results for C pneumoniae–specific IgG than among control children with variant MBL genotypes (63.7% vs 40.7% of asthmatic vs control children, respectively; odds ratio adjusted for age and sex, 2.21; 95% CI, 1.10-4.41; P = .02). Infected children with variant MBL alleles were found to have a higher risk of asthma development than infected children with normal MBL genotype. This risk was especially high in children with chronic or recurrent infection (positive results for both IgA and IgG; adjusted odds ratio, 5.38; 95% CI, 1.75-14.36; P = .01), but no increased risk was seen in children with current C pneumoniae infection (positive results for IgM). Conclusion This study indicates the important role of variant MBL alleles in the susceptibility to asthma in children infected with C pneumoniae. (J Allergy Clin Immunol 2003;112:729-34.)

Mannose Binding Lectin (MBL) gene polymorphism and in vitro fertilization outcome

Objective: MBL is a serum protein and a component of the innate immune system. By binding to carbohydrate residues on microorganisms, MBL activates the complement system and marks microbes for opsonization. MBL binding to Chlamydia has been demonstrated. The gene coding for MBL is polymorphic and the variant alleles result in decreased MBL serum levels. The association between C. pneumoniae and cardiovascular disease was shown to depend on the presence of variant MBL alleles. Given the relationship between Chlamydia and infertility, we examined the relationship between MBL genotype, infertility etiology and IVF outcome.Design: Prospective analysis of the association between MBL genotype, etiology of infertility and IVF outcome.Materials and Methods: MBL genotypes at codon 54 were determined in 185 consecutive IVF patients by polymerase chain reaction, endonuclease digestion and gel electrophoresis, using DNA isolated from cervical swabs. IVF outcome and the etiology of infertility were obtained at the conclusion of MBL genotype testing. Implantation was defined as the presence of a fetal heart beat. Statistics utilized included Categorical Chi-square testing and Student’s t-test where appropriate. P value < 0.05 was considered significant. Data is presented as mean ± standard deviation.Results: The wild type MBL genotype (AA) was present in 138 (74.6%) of the patients; 47 (25.4%) had variant alleles (41 were AB and 6 were BB). There were no differences in the age, oocyte yield, fertilization percentage or number of embryos transferred based on the MBL genotype result. Patients with the variant alleles had a trend towards an increased rate of tubal infertility (25.6% vs. 16.8%, p = 0.2). Among all subjects, the rates of pregnancy, clinical pregnancy and implantation were not related to the MBL genotype. However, among patients carrying the AB genotype, those with tubal infertility were less likely to achieve a clinical pregnancy than patients with non-tubal infertility (20% vs. 57.7%; P < 0.05). Patients with tubal and non-tubal infertility who had the AA genotype did not differ in pregnancy outcome.Conclusion: Possession of the MBL AB genotype is associated with a decreased IVF success rate in women with tubal infertility. Possession of this genotype, which results in reduced serum MBL levels and lowered innate immune defense against infection, may render women less effective in eliminating microorganisms from the upper genital tract. Analysis of tubal infertility patients for MBL genotypes may have predictive value for IVF outcome and for selecting patients that may need antibiotic prophylaxis. Objective: MBL is a serum protein and a component of the innate immune system. By binding to carbohydrate residues on microorganisms, MBL activates the complement system and marks microbes for opsonization. MBL binding to Chlamydia has been demonstrated. The gene coding for MBL is polymorphic and the variant alleles result in decreased MBL serum levels. The association between C. pneumoniae and cardiovascular disease was shown to depend on the presence of variant MBL alleles. Given the relationship between Chlamydia and infertility, we examined the relationship between MBL genotype, infertility etiology and IVF outcome. Design: Prospective analysis of the association between MBL genotype, etiology of infertility and IVF outcome. Materials and Methods: MBL genotypes at codon 54 were determined in 185 consecutive IVF patients by polymerase chain reaction, endonuclease digestion and gel electrophoresis, using DNA isolated from cervical swabs. IVF outcome and the etiology of infertility were obtained at the conclusion of MBL genotype testing. Implantation was defined as the presence of a fetal heart beat. Statistics utilized included Categorical Chi-square testing and Student’s t-test where appropriate. P value < 0.05 was considered significant. Data is presented as mean ± standard deviation. Results: The wild type MBL genotype (AA) was present in 138 (74.6%) of the patients; 47 (25.4%) had variant alleles (41 were AB and 6 were BB). There were no differences in the age, oocyte yield, fertilization percentage or number of embryos transferred based on the MBL genotype result. Patients with the variant alleles had a trend towards an increased rate of tubal infertility (25.6% vs. 16.8%, p = 0.2). Among all subjects, the rates of pregnancy, clinical pregnancy and implantation were not related to the MBL genotype. However, among patients carrying the AB genotype, those with tubal infertility were less likely to achieve a clinical pregnancy than patients with non-tubal infertility (20% vs. 57.7%; P < 0.05). Patients with tubal and non-tubal infertility who had the AA genotype did not differ in pregnancy outcome. Conclusion: Possession of the MBL AB genotype is associated with a decreased IVF success rate in women with tubal infertility. Possession of this genotype, which results in reduced serum MBL levels and lowered innate immune defense against infection, may render women less effective in eliminating microorganisms from the upper genital tract. Analysis of tubal infertility patients for MBL genotypes may have predictive value for IVF outcome and for selecting patients that may need antibiotic prophylaxis.

Mannose-binding lectin polymorphisms in clinical tuberculosis.

Mannose-binding lectin (MBL) mediates protection against infections by using the complement system, but certain microorganisms may increase infectivity by exploiting this host defense system. Thus, it has been speculated whether genetically determined low MBL levels may confer partial protection against certain intracellular microorganisms, such as Mycobacterium tuberculosis. We investigated MBL alleles in 109 culture-positive human immunodeficiency virus-uninfected patients with tuberculosis living in Denmark and 250 white control subjects. Patients and control subjects were divided into 3 different groups defined by undetectable, low, and high serum MBL concentrations, which correlates to deficient, low, and high expressing MBL genotypes. A significantly decreased frequency of patients with the low-expressing MBL genotype was observed in white patients compared to control subjects. The same tendency also was observed in patients of other ethnic origin. It may be hypothesized that heterozygosity for MBL variant alleles, which encodes low serum MBL levels, is associated with protection against clinical tuberculosis.

Absence of association between mannose-binding lectin gene polymorphisms and HIV-1 infection in a Colombian population.

Mannose-binding lectin (MBL) is a calcium-dependent lectin shown to play an important role in innate immunity to infection by activating the classical complement pathway and phagocytosis. In vitro studies have shown that MBL is able to bind to the gp120 HIV-1 surface antigen, and variants of the gene are associated with increased risk of HIV infection among Scandinavians. We investigated the association of genetic MBL variants and HIV-1 infection in 278 Colombian HIV-infected and control individuals. MBL genotype frequencies were similar for both groups, and no association was detected between MBL alleles B, C, and D and susceptibility to HIV-1 infection ( P=1.0). Since there is a well-documented link between the tested MBL alleles and very low MBL serum concentration, these results do not support the hypothesis that MBL levels are a risk factor for HIV-1 infection in Colombia.