Mannan-binding protein--levels in plasma and upper-airways secretions and frequency of genotypes in children with recurrence of otitis media

Time delays shape the eco-evolutionary dynamics of cooperation

We study the intricate interplay between ecological and evolutionary processes through the lens of the prisoner's dilemma game. But while previous studies on cooperation amongst selfish individuals often assume instantaneous interactions, we take into consideration delays to investigate how these might affect the causes underlying prosocial behavior. Through analytical calculations and numerical simulations, we demonstrate that delays can lead to oscillations, and by incorporating also the ecological variable of altruistic free space and the evolutionary strategy of punishment, we explore how these factors impact population and community dynamics. Depending on the parameter values and the initial fraction of each strategy, the studied eco-evolutionary model can mimic a cyclic dominance system and even exhibit chaotic behavior, thereby highlighting the importance of complex dynamics for the effective management and conservation of ecological communities. Our research thus contributes to the broader understanding of group decision-making and the emergence of moral behavior in multidimensional social systems.

The association of care burden with motivation of vaccine acceptance among caregivers of stroke patients during the COVID-19 pandemic: mediating roles of problematic social media use, worry, and fear

BACKGROUND

The aim of the present study was to investigate the relationship between care burden and motivation of COVID-19 vaccine acceptance among caregivers of patients who have experienced a stroke and to explore the mediating roles of social media use, fear of COVID-19, and worries about infection in this relationship.

METHODS

A cross-sectional survey study with 172 caregivers of patients who had experienced a stroke took part in a Taiwan community hospital. All participants completed the Zarit Burden Interview, Bergen Social Media Addiction Scale, Worry of Infection Scale, Fear of COVID-19 Scale, and Motors of COVID-19 Vaccine Acceptance Scale. Multiple linear regression model was applied to construct and explain the association among the variables. Hayes Process Macro (Models 4 and 6) was used to explain the mediation effects.

RESULTS

The proposed model significantly explained the direct association of care burden with motivation of COVID-19 vaccine acceptance. Despite the increased care burden associated with decreased vaccine acceptance, problematic social media use positively mediated this association. Moreover, problematic social media use had sequential mediating effects together with worry of infection or fear of COVID-19 in the association between care burden and motivation of vaccine acceptance. Care burden was associated with motivation of vaccine acceptance through problematic social media use followed by worry of infection.

CONCLUSIONS

Increased care burden among caregivers of patients who have experienced a stroke may lead to lower COVID-19 vaccines acceptance. Moreover, problematic social media use was positively associated with their motivation to get COVID-19 vaccinated. Therefore, health experts and practitioners should actively disseminate accurate and trustworthy factual information regarding COVID-19, while taking care of the psychological problems among caregivers of patients who have experienced a stroke.

Therapeutic Potential of Quercetin Loaded Nanoparticles: Novel Insights in Alleviating Colitis in an Experimental DSS Induced Colitis Model

Oxidative stress is considered the main etiologic factor involved in inflammatory bowel disease (IBD). Integration of nanocarriers for natural therapeutic agents with antioxidant and anti-inflammatory potential is a novel promising candidate for curing IBD. Herein, the colonic antioxidant and anti-inflammatory effects of different concentrations of quercetin nanoparticles (QT-NPs) were evaluated using a dextran sulfate sodium (DSS)-induced colitis model. Following colitis induction, the efficacy and mechanistic actions of QT-NPs were evaluated by assessing lesion severity, molecular aids controlling oxidative stress and inflammatory response, and histopathological and immunohistochemistry examination of colonic tissues. Administration of QT-NPs, especially at higher concentrations, significantly reduced the disease activity index and values of fecal calprotectin marker compared to the colitic group. Colonic oxidant/antioxidant status (ROS, H₂O₂, MDA, SOD, CAT, GPX and TAC) was restored after treatment with higher concentrations of QT-NPs. Moreover, QT-NPs at levels of 20 mg/kg and, to a lesser extent, 15 mg/kg reduced Nrf2 and HO-1 gene expression, which was in line with decreasing the expression of iNOS and COX2 in colonic tissues. Higher concentrations of QT-NPs greatly downregulated pro-inflammatory cytokines; upregulated genes encoding occludin, MUC-2 and JAM; and restored the healthy architectures of colonic tissues. Taken together, these data suggest that QT-NPs could be a promising alternative to current IBD treatments.

Identification and expression analysis of phosphate transporter (PHT) gene family in Lupinus albus cluster root under phosphorus stress

According to global estimation, 5.7 billion hectares of agricultural land contain limited phosphorus (P) availability leading to insufficient plant growth and productivity. Internal phosphate transporters play an essential role in mediating P mobilization and uptake from the soil. White lupin (Lupinus albus) is a cluster root (CR) forming crop with great potential to survive under P limited soil. However, it is imperative to identify and characterize the phosphate transporter (PHT) gene family in plants to validate their involvement in solving P deficiency problems. The recent availability of white lupin high-quality genome allowed us an exhaustive searches in the whole genome and identified five phosphates transporters subfamilies, including 35 putative genes that are unevenly distributed on 16 chromosomes. The LaPHT1 subfamily contained eight genes, LaPHT2 subfamily have three, LaPHT3 subfamily have eight, LaPHT4 subfamily have nine, and LaPHO subfamily has seven. Gene structure and duplication were also examined in detail. Syntenic analysis revealed that white lupin PHT family members had maximum the collinear relationship with those in L. angustifolius followed by Phaseolus vulgaris but showed the least collinear relationship with those in Arabidopsis. Gene ontology (GO) analysis revealed that the in white lupin PHT genes were enriched in functions regulated P uptake, transport, and recycling mechanisms. RT-qPCR was performed to evaluate the transcript levels of LaPHT genes in different parts of CR under P deficient hydroponic culture. Our study would provide better understanding the genetic evolution and expression phosphate of phosphate transporters in L. albus CR under P deficiency. It will also be helpful for further functional-based studies to solve P deficiency-related issues and mitigate P stress responses.

Extracellular Matrix and the Production of Cultured Meat

Cultured meat production is an evolving method of producing animal meat using tissue engineering techniques. Cells, chemical factors, and suitable biomaterials that serve as scaffolds are all essential for the cultivation of muscle tissue. Scaffolding is essential for the development of organized meat products resembling steaks because it provides the mechanical stability needed by cells to attach, differentiate, and mature. In in vivo settings, extracellular matrix (ECM) ensures substrates and scaffolds are provided for cells. The ECM of skeletal muscle (SM) maintains tissue elasticity, creates adhesion points for cells, provides a three-dimensional (3D) environment, and regulates biological processes. Consequently, creating mimics of native ECM is a difficult task. Animal-derived polymers like collagen are often regarded as the gold standard for producing scaffolds with ECM-like properties. Animal-free scaffolds are being investigated as a potential source of stable, chemically defined, low-cost materials for cultured meat production. In this review, we explore the influence of ECM on myogenesis and its role as a scaffold and vital component to improve the efficacy of the culture media used to produce cultured meat.

The Influence of the Use of Face Masks During the COVID-19 Pandemic on the Human Microbiome – A Mini-Review

The aim of this study was to draw attention to the possible consequences of improper, unhygienic use of mouth and nose covers in the context of prophylaxis against the spread of COVID-19 from the point of view of a family physician and focus on the risk of respiratory infections and skin lesions in patients, in different age groups. The use of protective masks may reduce the likelihood of infection but will not eliminate the risk of infection. However, it should be remembered that any mask, no matter how effective the filtration is or how well it seals, will have little effect if not used in conjunction with other preventive measures, including isolation of infected people, immunization, proper respiratory culture, regular, frequent replacement of masks, and hand hygiene. Additionally, certain risks associated with this form of prophylaxis should be taken into account, which, unfortunately, may also aggravate or even constitute a source of serious respiratory infections and lead to the development and aggravation of skin problems. Moreover, educating society not only on hand hygiene but also on the topic of the value of nose and mouth covers, as well as the frequency of their replacement and/or disinfection, is becoming a significant issue.

In vivo model of Propionibacterium (Cutibacterium) spp. biofilm in Drosophila melanogaster

OBJECTIVES

Acne vulgaris is a common inflammatory disorder of the pilosebaceous unit and Propionibacterium acnes biofilm-forming ability is believed to be a contributing factor to the disease development. In vivo models mimicking hair follicle environment are lacking. The aim of this study was to develop an in vivo Propionibacterium spp. biofilm model in Drosophila melanogaster (fruit fly).

METHODS

We created a sterile line of D. melanogaster able to sustain Propionibacterium spp. biofilms in the gut. In order to mimic the lipid-rich, anaerobic environment of the hair follicle, fruit flies were maintained on lipid-rich diet. Propionibacterium spp. biofilms were visualized by immunofluorescence and scanning electron microscopy. We further tested if the biofilm-dispersal activity of DNase I can be demonstrated in the developed model.

RESULTS

We have demonstrated the feasibility of our in vivo model for development and study of P. acnes, P. granulosum and P. avidum biofilms. The model is suitable to evaluate dispersal as well as other agents against P. acnes biofilm.

CONCLUSIONS

We report a novel in vivo model for studying Propionibacterium spp. biofilms. The model can be suitable for both mechanistic as well as interventional studies.

Updating the Role of Probiotics, Prebiotics, and Synbiotics for Tilapia Aquaculture as Leading Candidates for Food Sustainability: a Review

Tilapia production has significantly increased over the past few years due to the adoption of semi-intensive and intensive aquaculture technologies. However, these farming systems have subjected the fish to stressful conditions that suppress their immunity, hence exposing them to various pathogens. The application of antibiotics and therapeutics to enhance disease resistance, survival, and growth performance in aquaculture has been recently banned due to the emergence of antibiotic-resistant bacteria that pose a serious threat to the environment and consumers of aquatic organisms. Hence, the need for an alternative approach based on sustainable farming practices is warranted. Probiotic, prebiotic, and synbiotic use in tilapia production is considered a viable, safe, and environmentally friendly alternative that enhances growth performance, feed utilization, immunity, disease resistance, and fish survival against pathogens and environmental stress. Their inclusion in fish diets and or rearing water improves the general wellbeing of fish. Hence, this review aims at presenting research findings from the use of probiotics, prebiotics, and synbiotics and their effect on survival, growth, growth performance, gut morphology, microbial abundance, enzyme production, immunity, and disease resistance in tilapia aquaculture, while highlighting several hematological, blood biochemical parameters, and omics techniques that have been used to assess fish health. Furthermore, gaps in existing knowledge are addressed and future research studies have been recommended.

Bullying in the clinical setting: Lived experiences of nursing students in the Central Region of Ghana

INTRODUCTION

Nursing students are confronted with bullies in the classroom and during clinical placement. Acquisition of the necessary psychomotor skills intended during clinical placements may be impeded when workplace bullies intimidate students. This study aimed to describe the various bullying behaviours experienced by nursing students and their effects during clinical placement in the Central Region of Ghana.

METHODS

A qualitative phenomenological descriptive approach using a semi-structured interview guide was employed to collect data from nursing students in focus groups. Overall, six (6) focus groups were used, with five (5) students in each group comprising males and females. The sample size was based on data saturation and was saturated on the six focus group discussions giving a sample size of 30. Purposive sampling was used to select students who had been on the ward at least three clinical placements and had experienced bullying in the clinical setting. In-depth interviews were conducted, recorded, transcribed verbatim and analysed using content analysis.

RESULTS

The study revealed that nursing students had experienced bullying practices such as shouting, isolation, humiliation and being assigned tasks below their competency level. In addition, findings showed that bullying led to a loss of confidence and caused stress and anxiety in nursing students.

CONCLUSION

Therefore, it is recommended that nursing students are mentored holistically in a caring and accepting environment where they will be supported to achieve their learning goals, build their confidence, and develop their personal and professional identity.

Dysregulation of immune response in otitis media

Objective

Otitis media (OM) is a common reason for children to be prescribed antibiotics and undergo surgery but a thorough understanding of disease mechanisms is lacking. We evaluate the evidence of a dysregulated immune response in the pathogenesis of OM.

Methods

A comprehensive systematic review of the literature using search terms [otitis media OR glue ear OR AOM OR OME] OR [middle ear AND (infection OR inflammation)] which were run through Medline and Embase via Ovid, including both human and animal studies. In total, 82 955 studies underwent automated filtering followed by manual screening. One hundred studies were included in the review.

Results

Most studies were based on in vitro or animal work. Abnormalities in pathogen detection pathways, such as Toll-like receptors, have confirmed roles in OM. The aetiology of OM, its chronic subgroups (chronic OM, persistent OM with effusion) and recurrent acute OM is complex; however, inflammatory signalling mechanisms are frequently implicated. Host epithelium likely plays a crucial role, but the characterisation of human middle ear tissue lags behind that of other anatomical subsites.

Conclusions

Translational research for OM presently falls far behind its clinical importance. This has likely hindered the development of new diagnostic and treatment modalities. Further work is urgently required; particularly to disentangle the respective immune pathologies in the clinically observed phenotypes and thereby work towards more personalised treatments.

Expression of P63, P16 and CK17 in Atypical Squamous Metaplasia and Cervical Intraepithelial Neoplasia

Background & Objective:

Cervical intraepithelial neoplasia (CIN) is a dysmaturation process in squamous cells in epithelial layer, which highly increases the risk of developing cervical cancer. The aim of this study was to compare the expression of three biomarkers, p16, p63, and CK17 in patients with CIN and in those with atypical squamous metaplasia (ASM).

Methods:

In this study, 100 patients underwent a colposcopy-guided cervix biopsy. Immunostaining for the biomarkers was undertaken on tissue samples presented with ASM (n=50) and CIN (n=50).

Results:

A significant increase in immunostaining for CK7, P63, and P16 in patients with CIN was found compared to ASM subjects.

Conclusion:

Expression of CK17, P63, and P16 in CIN varied from those in ASM. Those biomarkers could be reliable factors to distinguish ASM from CIN; however, all the biomarkers could differentiate CIN from its mimics due to their high degree of sensitivity and specificity.

The Role of Mannose-Binding Lectin Serum Level in Tubotympanic Chronic Suppurative Otitis Media

BACKGROUND

Chronic suppurative otitis media (CSOM) is a common public health problem worldwide and a major cause of hearing impairment especially in developing countries. The role of Mannose-Binding Lectin (MBL), a component of innate immunity, in CSOM has not been studied. The aim of the study was to examine whether MBL deficiency was more frequently present in cases group of tubotympanic CSOM patients rather than healthy subjects.

MATERIAL AND METHODS

This was an analytic observational study. Subjects were enrolled in the Otorhinolaryngology Clinic at Margono Soekarjo Hospital, Purwokerto, Indonesia. An independent t-test was used to compare the mean of MBL serum concentration between tubotympanic CSOM subjects and control.

RESULTS

From 36 tubotympanic CSOM patients, there were 8 (22.22%) patients with MBL deficiency (MBL level < 100 ng/ml), while no deficiency was found in the control group. The mean of MBL level in cases group was 354.88 ng/ml, with the lowest level being 0.001 ng/ml and the highest level 690.24 ng/ml, while in the control group MBL level mean was 376.27 with the lowest level being 188.71 and the highest level 794.54 ng/ml.

CONCLUSION

There was no significant difference of MBL serum level between tubotympanic CSOM and control group. However, the presence of subjects with MBL deficiency in the tubotympanic CSOM group might be considered as playing a role in the tubotympanic CSOM.

Expression, Distribution, and Role of C-Type Lectin Receptors in the Human and Animal Middle Ear and Eustachian Tube: A Review

Otitis media (OM) is a group of inflammatory diseases of the middle ear (ME), regardless of cause or pathological mechanism. Among the molecular biological studies assessing the pathology of OM are investigations into the expression of C-type lectin receptors (CLR) in the ME and Eustachian tube (ET). To date, nine studies have evaluated CLR expression in the ME and ET. The expression of individual CLRs in mammalian ME and ET varies by species and model of OM. Assessments have shown that the patterns of CLR expression in the ME and ET vary; that CLR expression may vary by type of OM; and that the distribution and levels of expression of CLRs may depend on the presence or absence of inflammation, with variations even within the same species and same tissue. Infection of the ME and ET with various pathogens is a common cause of all types of OM, with host responses to pathogens mediated initially by the innate immune system. CLRs are important factors in the innate immune system because they act as both adhesion molecules and as pathogen recognition receptors. The expression of CLRs in OM tissues suggests that CLRs are associated with the pathogenesis of various types of OM.

Mannose-Binding Lectin: Biologic Characteristics and Role in the Susceptibility to Infections and Ischemia-Reperfusion Related Injury in Critically Ill Neonates

The mannose-binding lectin (MBL) is a member of the collectin family, belonging to the innate immunity system. Genetic, biologic, and clinical properties of MBL have been widely investigated throughout the last decades, although some interesting aspects of its potential clinical relevance are still poorly understood. Low circulating concentrations of MBL have been associated with increased risk of infection and poor neurologic outcome in neonates. On the other hand, an excessive and uncontrolled inflammatory response by the neonatal intestine after the exposure to luminal bacteria, leading to an increased production of MBL, may be involved in the onset of necrotizing enterocolitis. The purpose of the present review is to summarize the current knowledge about genetic and biologic characteristics of MBL and its role in the susceptibility to infections and to ischemia-reperfusion related tissue injuries to better explore its clinical relevance during the perinatal period and the possible future therapeutic applications.

Mannose-binding lectin 2 gene polymorphism and susceptibility to upper respiratory tract infection among endurance athletes

The aim of this study was to investigate the influence of mannose-binding lectin 2 (MBL2)-exon-1 gene polymorphisms on upper respiratory tract infection (URTI) incidence among endurance athletes. To this end, 100 healthy elite male athletes participating in the study were classified as either healthy or prone to frequent URTI. Blood samples, DNA isolation, multiplex polymerase chain reaction (PCR) and conventional PCR-RFLP were performed. Genomic DNA was extracted from peripheral leukocytes of whole blood samples using the QIAmp DNA Blood Mini Kit. For comparison of the distribution of genotypes between two groups and for estimating odds ratios (OR) for URTI susceptibility in relation to the MBL2-exon-1 polymorphism, Pearson's chi-square and logistic regression method were used, respectively. The MBL2-exon-1 genotype distribution differed between athletes with URTI and healthy athletes (χ(2) = 7.81, p = 0.02). The AO and AO + OO genotypes of MBL2 were observed at a greater frequency in the illness-prone group compared with the healthy group (34.04% vs. 11.32%). In conclusion, findings from this study have identified a potential role of genetic variation in influencing the risk for URTI in athletic populations and single-nucleotide polymorphisms (SNPs) in the MBL2-exon-1 genes were associated with an altered risk profile. These measures may have a predictive value in the identification of individuals who are more likely to experience recurrent infections when exposed to high physical stress in the areas of athletic endeavour.

Mannan-binding lectin deficiency - Good news, bad news, doesn't matter?

Mannan-binding lectin (MBL) deficiency has been classified as a commonly occurring immune disorder, affecting approximately 30% of the human population. MBL, being part of the innate immune system, supports the recognition of infectious pathogens by binding to carbohydrate moieties expressed on microorganisms and activates the lectin pathway of the complement system. MBL2 gene polymorphisms are associated with quantitative and qualitative MBL abnormalities in the serum. The clinical impact of MBL deficiency and its association to a wide variety of diseases has been extensively studied. The picture is puzzling as the studies suggest a detrimental or beneficial or no impact of low or high MBL serum levels on disease susceptibility. In this review we attempt to extract what is relevant from the literature and address controversial issues. We finally suggest that a comprehensive understanding of the role of MBL in human diseases requires considering its context-dependency.

Mannose-binding lectin and innate immunity

Innate immunity is the earliest response to invading microbes and acts to contain infection in the first minutes to hours of challenge. Unlike adaptive immunity that relies upon clonal expansion of cells that emerge days after antigenic challenge, the innate immune response is immediate. Soluble mediators, including complement components and the mannose binding lectin (MBL) make an important contribution to innate immune protection and work along with epithelial barriers, cellular defenses such as phagocytosis, and pattern-recognition receptors that trigger pro-inflammatory signaling cascades. These four aspects of the innate immune system act in concert to protect from pathogen invasion. Our work has focused on understanding the protection provided by this complex defense system and, as discussed in this review, the particular contribution of soluble mediators such as MBL and phagocytic cells. Over the past two decades both human epidemiological data and mouse models have indicated that MBL plays a critical role in innate immune protection against a number of pathogens. As demonstrated by our recent in vitro work, we show that MBL and the innate immune signaling triggered by the canonical pattern-recognition receptors (PRRs), the Toll-like receptors (TLRs), are linked by their spatial localization to the phagosome. These observations demonstrated a novel role for MBL as a TLR co-receptor and establishes a new paradigm for the role of opsonins, which we propose to function not only to increase microbial uptake but also to spatially coordinate, amplify, and synchronize innate immune defenses mechanism. In this review we discuss both the attributes of MBL that make it a unique soluble pattern recognition molecule and also highlight its broader role in coordinating innate immune activation.

Polymorphisms in the mannan-binding lectin gene are not associated with questionnaire-reported respiratory tract infections in children

BACKGROUND

Low mannan-binding lectin (MBL) levels, caused by MBL2 polymorphisms, are suggested to contribute to susceptibility to respiratory tract infections (RTIs), particularly early in life. Large-scale replication of previous associations is needed, however. We investigated the association between MBL2 polymorphisms and the frequency of RTI in a large population-based birth cohort of white children.

METHODS

The frequency of RTI was prospectively assessed by annual parental questionnaires until children were 4 years of age. Thirteen polymorphisms in MBL2 were determined in 987 Dutch children. Haplotypes, previously shown to be associated with functional levels of MBL, were constructed, and their associations with the frequency of RTI during year 1, year 2, and the first 4 years of life were assessed. High-producing, intermediate-producing, and deficient MBL2 genotypes were defined on the basis of exon 1 and Y/X promoter polymorphisms.

RESULTS

No differences were found between investigated polymorphisms and haplotype frequencies in the population as a whole or between the groups with frequent, moderately frequent, or no RTIs reported. Deficient MBL2 genotypes were not associated with an increased risk of RTI (odds ratio, 0.71 [95% confidence interval, 0.25 to 2.05]) during years 1-4 of life. This was also true when year 1 and year 2 were studied separately.

CONCLUSION

These results suggest that, at the population level, MBL2 polymorphisms do not contribute to the risk of questionnaire-reported RTI in white children.

Mannan-binding lectin (MBL) in women with tumours of the reproductive system

Mannan-binding lectin (MBL) is an important factor of innate immunity contributing to the clearance of microorganisms. Recently, an antitumourigenic role of MBL has been suggested. We investigated mbl2 genotypes, MBL concentrations, and MBL-MASP-2 complex activity in patients with ovarian cancer. The expression of both mbl2 and masp-2 genes were investigated in ovarian tissue sections. Additionally, samples from patients with other malignant and benign tumours of the reproductive tract were tested. A significantly higher incidence of MBL deficiency/insufficiency-associated genotypes was found among patients with malignant disease compared to age-matched controls. Unexpectedly, no differences in median MBL level or MBL-MASP-2 complex activity were found between the groups. This was partly a reflection of higher MBL concentrations and MBL-MASP-2 activity in cancer patients compared with healthy women carrying corresponding genotypes. MBL-specific mRNA expression was detected in several normal and malignant ovarian tissues, as well as in ovarian epithelial cell lines. Intracellular staining with MBL-specific antibodies demonstrated the presence of MBL in ovarian cell lines, and in normal as well as malignant ovarian tissue sections. In contrast, MASP-2-specific mRNA expression was detected only in the ovary tissues of patients with malignant disease. No significant changes in MBL concentration during 3 months of chemotherapy were noticed. MBL was detected in ascites and in the fluid of benign ovarian cysts. Our findings may reflect anti-tumourigenic activity of MBL protein which might suggest potential therapeutic application. However, it cannot be excluded that mbl-2 mutant alleles may be in linkage disequilibrium with an unidentified tumour susceptibility gene(s).

Involvement of complement pathways in patients with bacterial septicemia

The complement system is a major humoral portion of the innate immune system, playing a significant role in host defence against microorganisms. The biological importance of this system is underlined by the fact that at least three different pathways for its activation exist, the classical, the MBL and the alternative pathway. To elucidate the involvement of the classical and/or the MBL pathway during bacterial septicemia, 32 patients with gram-positive and 30 patients with gram-negative bacterial infections were investigated. In patients with gram-positive bacteria, a significant consumption of C1q (p=0.005) but not of mannose-binding lectin (MBL) (p=0.2) was found during the acute phase of infection. In contrast, in patients with gram-negative bacterial infections, a significant reduction of MBL (p=0.002) and only a moderate, less significant reduction of C1q (p=0.03) were observed. As a model for the binding of MBL to gram-negative bacteria, Salmonella strains with defined mutations in their lipopolysaccharide (LPS) structure were used. The comparison of the binding of MBL to these Salmonella strains with that of the corresponding isolated LPS forms bound to microtiter plates revealed a similar binding pattern, supporting the interpretation that LPS on the surface of gram-negative bacteria is the major acceptor molecule for MBL on these bacteria, which according to our results obviously also takes place during gram-negative bacterial septicaemia. Furthermore, we were able to demonstrate that MBL bound to LPS was able to initiate activation of the complement cascade as measured by the occurrence of the cleavage product C4c.

Mannan-binding lectin in children with chronic gastritis

The involvement of mannan-binding lectin (MBL) insufficiency in the pathogenesis of chronic gastritis (CG) in children was investigated. Blood samples were collected from 78 paediatric patients suffering from CG associated with Helicobacter pylori infection (group Hp(+)) and from 41 with the disease not associated with such an infection (group Hp(-)). Control group consisted of 77 children. The frequency of mbl-2 gene mutations and serum protein concentrations did not differ significantly in both groups as compared with controls. An expression of mbl-2 gene in gastric biopsies of CG patients was demonstrated. It was found to be stronger in H. pylori-infected children. The results presented in this paper suggest that MBL deficit/dysfunction probably does not contribute to an increased risk of CG (both associated and not associated with H. pylori infection) in children. However, MBL opsonic effect and/or the lectin pathway of complement activation may be taken into account as possible host defence mechanisms in gastric patients.

Immunological status in the aetiology of recurrent otitis media with effusion: serum immunoglobulin levels, functional mannose-binding lectin and Fc receptor polymorphisms for IgG

The objective was to study the role of serum immunoglobulin levels, mannose-binding lectin (MBL), and Fc gamma receptor (FcgammaR) polymorphisms on the development of recurrent otitis media with effusion (OME). Children aged between two and seven years with persisting OME received bilateral tympanostomy tubes and immunological parameters were investigated in relation with OME recurrence within six months after tube extrusion. No statistically significant differences in serum immunoglobulin levels were present between children with and without OME recurrence. In children with bilateral recurrence (n = 56), median levels of MBL were 1.39 mg/L compared to 2.48 mg/L in children with OME recurrence (n = 17) (p = 0.29). In addition, 34% of the children with bilateral recurrence were homozygous for the genotype FcgammaRIIa-R/R131, whereas less than 20% of the children with unilateral recurrence or those without recurrence were homozygous for this Fcgamma receptor (p = 0.26). Serum mannose-binding lectin and FcgammaRIIa-R/R131 polymorphism may play a role in the aetio-pathogenesis of recurrent OME.

Childhood levels of immunoglobulins and mannan-binding lectin in relation to infections and allergy

Respiratory tract infections, allergies and otitis media are common problems in early childhood. Our aim was to evaluate in a longitudinal community-based cohort study the association between maturation of immunoglobulin (Ig) and mannan-binding lectin (MBL) responses and disease manifestations in the first 4 years of life. Sustained low levels of IgA proved the strongest single indicator of susceptibility for recurrent otitis media (P = 0.008) and respiratory tract infections (P = 0.02), and this condition was also associated with low production of IgG subclasses. About 7% of the cohort had sustained low levels of MBL (<0.4 mg/l). Low MBL did not predispose to any ailments studied, but children with low IgA and recurrent otitis media had relatively low MBL at birth, which failed to increase during the study period and was significantly reduced at the age of 4 years (P = 0.04). MBL levels increased from birth to 2 years (P < 0.0001) and were higher in children than in adults (P = 0.001). The increase was 1.9-fold in children with no recorded clinical events and 1.7-fold in children with asthma or infections, but significantly lower, 1.2-fold, in children with recurrent otitis media. Low levels of IgA within the normal range may reveal disease susceptibility not detected by conventional criteria. Slow maturation of Ig appears to be the main factor of susceptibility during childhood, but a strong corollary role for MBL is indicated by the high levels produced during childhood as well as the precipitation of disease in children with low levels of MBL and Ig.

The potential role of mannan-binding lectin in the clearance of self-components including immune complexes

Mannan-binding lectin (MBL) is a pattern recognition receptor in the innate immune system. It recognizes certain sugar residues arranged in a pattern that enables MBL to bind with sufficient strength. Such sugar patterns are common on the surface of many microorganisms, and MBL has therefore been considered to be an agent that can discriminate between self and nonself. There is, however, increasing evidence supporting that MBL, like many membrane-bound C-type lectin-like receptors, also helps to dispose of various outworn or abnormal body components. Most self-components are protected with sialic acid or galactose that disrupt the pattern of the sugars that MBL can bind, but MBL may be significantly involved in the elimination of self-components that have lost these protective terminal residues. The role of MBL in the clearance of invading pathogens has previously been thoroughly reviewed. Here, we review some findings that support the notion that MBL may contribute to noninflammatory removal of immune complexes and abnormal cells by the reticuloendothelial system. Defects in this clearance mechanism may cause an accumulation of potentially dangerous self-components, thereby increasing the likelihood of chronic inflammation and autoimmunity.

Analysis of low molecular weight intracellular associations of a human mannan binding lectin (MBL)

Human mannan binding lectin (MBL) is a member of the collectins, a group of proteins that contain a dual structure with a lectin and a collagenous moieties. The collectins are considered as major actors of innate immunity. We report the presence of low molecular weight intracellular MBL forms in human hepatocytic cell lysates, with binding capacities associated to its lectin and/or its collagen moiety. Competition with D-mannose and with antibodies directed against the lectin binding site of MBL indicate that the 60 kDa form represents an intracellular association of MBL through its lectin moiety. The effects of collagenase or MBL associated serine proteases (MASPs) from a MBL deficient plasma, gave evidence that the 60 KDa form contains also collagen and suggested the binding of a ligand to this collagen part. These results show that this intracellular form of MBL shares binding properties with circulating MBL. The binding potential of the lectin and the collagenous parts of precursor forms of intracellular MBL may suggest that they behave as molecular chaperone. The complexity of MBL structure and functions deserves further investigation on other intracellular forms of MBL.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Our studies show that MBL deficiency is an inherited characteristic and may be a crucial factor in maintaining immunologic health.

Umbilical cord mannan-binding lectin and infections in early childhood

To investigate whether mannan-binding lectin (MBL) in umbilical cord blood (UCB) is associated with the incidence rate of hospitalizations for infections during early childhood. A follow-up study from birth to 31 months of age, with endpoint data from the Danish National Hospital Discharge Registry. The concentration of MBL and immunoglobulin A (IgA) in UCB was measured in a time-resolved immunofluorometric assay. Information on possible confounding factors was obtained from questionnaires completed by mothers during their pregnancy, and characteristics of the child at birth were registered by a midwife on a structured coding sheet. A total of 2104 infants born in the period between 1 February 1990 and 25 May 1991 to mothers living in the municipality of Aarhus. Concentration of MBL and IgA in UCB, gestational age, birth weight, number of siblings less than 3 years old, mother's smoking habits, alcohol and coffee consumption, educational and marital status and previous spontaneous abortions and stillbirths. Of 2104 children, 626 were hospitalized at least once, and 346 of these were hospitalized with infection. The hazard ratio (HR) of hospitalization with infections in children with low levels of MBL (<120 ng/ml) was 1.4 (95% confidence interval (CI), 1.0-1.8), which was similar to our findings on hospitalization because of other diseases. The HR of hospitalization for viral infections was 2.8 (CI, 1.3-5.9). Low levels of MBL in UCB were associated with hospitalization in general and particularly with hospitalization for viral infections.

Reactive arthritis and serum levels of mannose binding lectin -- lack of association

The purpose was to evaluate the possible association of serum mannose binding lectin (s-MBL) levels on type of triggering microbe, duration of diarrhoea, incidence and course of reactive arthritis (ReA) caused by Salmonella, Yersinia and Campylobacter. Sixty patients with ReA of 1-228 months duration, 173 patients with ReA or uncomplicated enterocolitis caused by Campylobacter, 226 sera from patients with elevated antibody levels against Salmonella, Yersinia or Campylobacter, and 114 blood donors were tested for s-MBL using ELISA technique, both direct mannan binding assay and sandwich ELISA. s-MBL was compared with C-reactive protein (CRP) levels and with the ability of activating complement C4. Among the 114 donors 9% had s-MBL <50 microg/l, 16% had from 50-500 microg/l and 75% had >500 microg/l. The distribution of s-MBL levels in the three-patient groups did not differ significantly from the controls. There were no indications that low s-MBL was associated with prolonged duration of arthritis, diarrhoea or individual bacterial infections. The two MBL assays were comparable with respect to serum concentrations, indicating that the actual circulating MBL was also functionally active. s-MBL exhibited acute phase reactant behaviour and correlated to CRP level, but only in patients with s-MBL concentrations exceeding 1000 microg/l. MBL in 10 randomly selected ReA sera were tested for the ability to activate complement C4. The results did not differ from those of donor controls. This study demonstrates that the distributions of s-MBL levels in serum among patients with ReA are not different from donor controls. The course, outcome or triggering bacteria are not associated with a particular level of s-MBL.

Changes in the mannan binding lectin (MBL) concentration in human milk during lactation

The mannan binding lectin (MBL) activates the complement system by the lectin pathway after the recognition of some structural motifs (saccharides) present on the surface of microorganisms. MBL has been mostly identified and quantified in human serum by ELISA or microparticle immunonephelometry assays. This article reports the MBL levels as assessed by a microparticle immunonephelometric assay in 76 human milk samples. Immunonephelometry was performed using skim-milk samples diluted 20 times over a calibration range of 0.07-4.82 mg/L. MBL is indeed present in human milk and its concentration decreases significantly during development from colostrum (0.55+/-0.09 mg/L) to transitional (0.18+/-0.02 mg/L) and mature milk (0.17+/-0.02 mg/L). This innate molecule may be involved in the primary defenses of the mammary gland and the neonate, whose immune system is immature. The high levels observed during the first days of lactation support the hypothesis that this molecule plays a key role in limiting the colonization of the newborn gut by pathogens.

Evaluation and clinical interest of mannan binding lectin function in human plasma

The mannan binding lectin (MBL) plays a major role in innate immunity through its ability to activate complement upon binding to carbohydrate arrays on the surface of various microorganisms. The question of a possible association of the MBL structural gene polymorphism and the oligomeric state of MBL was poorly documented. For these reasons, it appears difficult to evaluate MBL in blood patients on the only basis of protein contents, even in combination with MBL genotyping. This study reports a method to calculate a specific activity for circulating MBL, that relies on: (i) the availability of purified MBL; and (ii) a simplified MBL activity assay based on complement activation. The three-step MBL purification from human plasma reported here is characterized by a highly purified MBL, that occurs in two different oligomeric forms. The results on the specific activity of these forms show that the higher oligomeric forms of MBL have the ability to induce C4 cleavage more efficiently than the corresponding lower oligomers. The usefulness of this approach is illustrated by its potential interest in the biological exploration of certain pathology, for example in the follow-up of chronic hepatitis C. Further investigation is needed to establish whether MBL specific activity (MBLsa) is correlated to the polymorphic state of the molecule. The relative simplicity of the test described here allows better investigation on the relationship between MBL biological activity and its genotype.

The genetics of otitis media

Almost every child will suffer at least one episode of otitis media (OM). Therefore, it is not immediately obvious that there is a genetic predisposition to the development of the disease. However, evidence from a variety of studies has shown that there is a clear genetic component to susceptibility to OM. Methodologies for discovering these genes are described within this article. The identification of OM susceptibility genes allows the development of molecular diagnostic assays that will inform the clinician as to which child is at increased risk and warrants more aggressive intervention. Delineating the OM genes not only provides a deeper understanding of the pathophysiology of this common disease, but also of acute and chronic bacterial disease in general.

Single nucleotide polymorphisms of the mannose-binding lectin are associated with susceptibility to primary biliary cirrhosis

Although the immunopathogenesis of primary biliary cirrhosis (PBC) remains unknown, familial clustering of patients with PBC suggests an important role for genetic factors. In addition, recent data support the thesis that the mucosal immune response against intraluminal pathogens may be involved with the onset of PBC. Mannose-binding lectin (MBL) is a key factor in innate mucosal defenses and has several key single nucleotide polymorphisms (SNPs). To study whether MBL gene SNPs are associated with susceptibility to PBC, we studied 65 patients with PBC and 218 controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequence specific priming-polymerase chain reaction (SSP-PCR) to examine 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. We also analyzed serum MBL concentrations. Interestingly, the prevalence of haplotype HYPA, leading to hyper-production of MBL, as well as HYPA/HYPA genotype were significantly increased in PBC compared to controls (0.53 vs. 0.44, P=0.031; 33.9%vs. 17.0%, P=0.003, respectively). Furthermore, individuals homozygous for HYPA had a significantly increased risk for PBC (odds ratio (OR)=2.51, 95% confidence interval (CI)=1.34-4.66). Our results demonstrate that the MBL genotype can be significantly associated with increased risk for PBC, and further, that increased production of MBL plays a critical role in immunopathogenesis.

The genetics of otitis media

There is significant evidence from epidemiologic, anatomic, physiologic, and immunologic studies that susceptibility to recurrent episodes of acute otitis media (OM) and persistent OM with effusion is largely genetically determined. The genetics of OM are most likely complex, i.e., many genes are probably contributing to the overall phenotype. The knowledge of a hereditary component has important implications because closer surveillance of children at risk for OM could result in earlier detection and treatment. Further, once OM susceptibility genes have been identified it may be possible to develop molecular diagnostic assays that could enable the clinician to identify the child at high risk for OM and to develop more focused treatments in the future.

Cell biology of tubotympanum in relation to pathogenesis of otitis media - a review

The sterility of the eustachian tube and tympanic cavity of normal individuals is maintained not only by the adaptive immune system, but also by the mucociliary system and the antimicrobial molecules of innate immunity. Mucin production and periciliary fluid homeostasis are essential for normal mucociliary function and dysfunction of this system is an important risk factor for otitis media. The secreted antimicrobial molecules of the tubotympanum include lysozyme, lactoferrin, beta defensins, and the surfactant proteins A and D (SP-A, SP-D). Defects in the expression or regulation of these molecules may also be the major risk factor for otitis media.

Mannose-binding lectin is a component of innate mucosal defense against Cryptosporidium parvum in AIDS

BACKGROUND & AIMS

Nonimmune mechanisms of mucosal defense seem to be biologically important and might explain the observed variability in the course of enteric infection in immunodeficiency. Mannose-binding lectin (MBL) deficiency is associated with persistent diarrhea in children. We found that genetic determinants of MBL deficiency appear to predispose to cryptosporidiosis in patients with the acquired immunodeficiency syndrome (AIDS), and went on to study interactions of MBL and complement on Cryptosporidium parvum sporozoites.

METHODS

This study involved cross-sectional study of MBL genotype and enteric infection in 72 Zambian AIDS patients with diarrhea, immunofluorescence analysis of MBL and C4 binding to C. parvum, and immunoblotting for MBL and complement in small intestinal fluid.

RESULTS

Individuals homozygous for MBL structural gene mutations were at increased risk of cryptosporidiosis (odds ratio, 8.2; 95% confidence interval, 1. 5-42; P = 0.02). Lectin-mediated and concentration-dependent binding of purified MBL was detected on sporozoites but not oocysts, and MBL activated C4 on sporozoites. MBL, C3, C4, and albumin were detected in small intestinal fluid in half the patients tested, suggesting transudation of serum components into the enteropathic gut.

CONCLUSIONS

The increased risk of cryptosporidiosis in MBL deficiency appears to include patients with AIDS. It may operate through MBL-mediated complement activation on sporozoites.

The lipopolysaccharide structures of Salmonella enterica serovar Typhimurium and Neisseria gonorrhoeae determine the attachment of human mannose-binding lectin to intact organisms

Mannose-binding lectin (MBL) is an important component of the innate immune system. It binds to the arrays of sugars commonly presented by microorganisms and activates the complement system independently of antibody. Despite detailed knowledge of the stereochemical basis of MBL binding, relatively little is known about how bacterial surface structures influence binding of the lectin. Using flow cytometry, we have measured the binding of MBL to a range of mutants of Salmonella enterica serovar Typhimurium and Neisseria gonorrhoeae which differ in the structure of expressed lipopolysaccharide (LPS). For both organisms, the possession of core LPS structures led to avid binding of MBL, which was abrogated by the addition of O antigen (Salmonella serovar Typhimurium) or sialic acid (N. gonorrhoeae). Truncation of the LPS within the core led to lower levels of MBL binding. It was not possible to predict the magnitude of MBL binding from the identity of the LPS terminal sugar alone, indicating that the three-dimensional disposition of LPS molecules is probably also of importance in determining MBL attachment. These results further support the hypothesis that LPS structure is a major determinant of MBL binding.

Mannan-binding lectin (MBL) in chickens: molecular and functional aspects

Mannan-binding lectin (MBL) is a serum collectin (i.e. mosaic protein with collagenous and lectin domains) involved in the innate immune defence against various microbes. In vitro studies indicate that MBL exerts its function by binding to the microbial surface through its carbohydrate recognition domains followed by direct opsonization or complement activation via the MBL associated serine proteases MASP-1 and MASP-2. In Aves (i.e. chickens), as in man, only one MBL form has been found, while traditional laboratory animals (i.e. mouse and rat) have two MBL forms in serum. MBL has been extensively studied in mammals but recently also in Aves. This review summarizes the present knowledge of MBL in chickens and compares it to the situation in mammals.

Lack of association between mannose-binding lectin, acute otitis media and early Epstein-Barr virus infection among children in Greenland

Low serum levels of mannose-binding lectin (MBL) have been associated with recurrent infections in early childhood. Otitis media (OM) is frequent in Greenlandic children and the first episode of acute OM (AOM) occurs early, as is the case also with Epstein-Barr virus (EBV) infection. We have therefore investigated the association between MBL genotypes, episodes of AOM, and early EBV infection in 82 community-based, unselected children in Greenland. Nasopharyngeal aspirations for EBV and MBL genotype examination, nasopharyngeal bacterial cultures, and history of AOM episodes were obtained. MBL genotypes were established in 73 specimens: 68% of these were homozygous for normal wildtype (AA), and 32% were homozygous or heterozygous for variant alleles that are associated with absence or low MBL serum level. The allele frequencies were: A = 0.88, B = 0.08 (codon 54) and D = 0.04 (codon 52). EBV was found in 41 specimens, more often with increasing age, and significantly related to ethnicity. Presence of variant MBL alleles or EBV infection was not associated with AOM, recurrent AOM (rAOM) or age at first AOM episode and EBV positive children with homozygosity for the normal MBL genotype did not have significantly more episodes of AOM, rAOM or earlier age at the first AOM episode. MBL genotypes and EBV infection alone or in interplay are not associated with the high prevalence of OM in Greenlandic children. The study suggests that low MBL level does not by itself predispose to AOM in community-based, unselected children.

Association of mannose-binding lectin gene heterogeneity with severity of lung disease and survival in cystic fibrosis

Mannose-binding lectin (MBL) is a key factor in innate immunity, and lung infections are the leading cause of morbidity and mortality in cystic fibrosis (CF). Accordingly, we investigated whether MBL variant alleles, which are associated with recurrent infections, might be risk factors for CF patients. In 149 CF patients, different MBL genotypes were compared with respect to lung function, microbiology, and survival to end-stage CF (death or lung transplantation). The lung function was significantly reduced in carriers of MBL variant alleles when compared with normal homozygotes. The negative impact of variant alleles on lung function was especially confined to patients with chronic Pseudomonas aeruginosa infection. Burkholderia cepacia infection was significantly more frequent in carriers of variant alleles than in homozygotes. The risk of end-stage CF among carriers of variant alleles increased 3-fold, and the survival time decreased over a 10-year follow-up period. Moreover, by using a modified life table analysis, we estimated that the predicted age of survival was reduced by 8 years in variant allele carriers when compared with normal homozygotes. Presence of MBL variant alleles is therefore associated with poor prognosis and early death in patients with CF.

Mannose-binding lectin (MBL) deficiency. Variant alleles in a midwestern population of the United States

OBJECTIVES

To describe a method for the genotype analysis of mutations in the gene encoding mannose binding lectin (MBL), study the incidence of MBL gene mutations in a population of the Midwest of the United States, and compare it with previous reports in other populations. The objective of this report is also an extensive review of the literature to analyze the importance of MBL deficiency in human disease.

DATA SOURCES

Blood samples were obtained from the blood bank of the Mayo Clinic. They represented a population of blood donors living in the Midwest of the United States. A review of the literature was performed by selection of articles from Medline database.

STUDY SELECTION

Blood samples, 148, were randomly selected from a pool of blood donors. They included both females and males. Blood donors had been previously screened by a questionnaire and were found to be generally healthy. For the literature review, articles containing original data on MBL in humans were selected.

RESULTS

Forty-five (30.4%) of the analyzed blood donors carried one variant allele, while 8 donors (5.4%) showed homozygosity or compound heterozygosity for MBL gene mutations. Allele frequency for the different MBL variants is provided. Our results are similar to those reported for the Danish population. Literature review provides evidence for a significant role of MBL deficiency in the innate immunity. The incidence of MBL mutations is higher among patients with recurrent infections and autoimmune disorders.

CONCLUSIONS

Mannose binding lectin deficiency has a definite role in the pathogenesis of primary immunodeficiency in humans and screening patients with recurrent infections and autoimmunity might be beneficial. The significance of MBL deficiency among apparently healthy blood donors remains to be determined.

Association of mannose-binding lectin gene haplotype LXPA and LYPB with interferon-resistant hepatitis C virus infection in Japanese patients

BACKGROUND/AIMS

Mannose-binding lectin, a key factor of the innate immune system, has genetic polymorphism, and individuals who carry certain genotypes of mannose-binding lectin are known to be more prone to severe or prolonged infectious diseases. We aimed to find any relevance of mannose-binding lectin polymorphism to hepatitis C virus infection.

METHODS

We determined the mannose-binding lectin genotypes by sequence specific priming-polymerase chain reaction in 159 hepatitis C virus-infected chronic hepatitis patients and 218 healthy controls in Japan by looking at 4 polymorphic loci: 2 (H/L and X/Y) within the promoter region and 2 (P/Q and A/B) within exon-1 of the mannose-binding lectin gene.

RESULTS

A group of mannose-binding lectin genotypes designated "XB-type" (containing LXPA or LYPB haplotype at least heterozygously) was less frequently found in interferon-responsive patients (38.5%) than in interferon-resistant patients (60.7%, p=0.008) and controls (57.3%, p=0.014). Individuals with the "XB-type" had lower serum concentrations of mannose-binding lectin, compared to those with "YA-type", which is defined by homozygous carriage of both Y and A alleles: 0.63+/-0.61 vs 2.06+/-1.17 mg/l, p<0.001.

CONCLUSIONS

Our results suggest that the mannose-binding lectin-related innate immune system plays an important role in elimination of hepatitis C virus during interferon therapy. Determining mannose-binding lectin genotypes may help in selecting the hepatitis C virus-infected patients to be treated with interferon.

Human mannose-binding protein inhibits infection of HeLa cells by Chlamydia trachomatis

The role that collectin (mannose-binding protein) may play in the host's defense against chlamydial infection was investigated. Recombinant human mannose-binding protein was used in the inhibition of cell culture infection by Chlamydia trachomatis (C/TW-3/OT, E/UW-5/Cx, and L2/434/Bu), Chlamydia pneumoniae (AR-39), and Chlamydia psittaci (6BC). Mannose-binding protein (MBP) inhibited infection of all chlamydial strains by at least 50% at 0.098 microg/ml for TW-3 and UW-5, and at 6.25 microg/ml for 434, AR-39, and 6BC. The ability of MBP to inhibit infection with strain L2 was not affected by supplementation with complement or addition of an L2-specific neutralizing monoclonal antibody. Enzyme-linked immunosorbent assay and dot blot analyses showed MBP bound to the surface of the organism to exert inhibition, which appeared to block the attachment of radiolabeled organisms to HeLa cells. Immunoblotting and affinity chromatography indicated that MBP binds to the 40-kDa glycoprotein (the major outer membrane protein) on the outer surface of the chlamydial elementary body. Hapten inhibition assays with monosaccharides and defined oligosaccharides showed that the inhibitory effects of MBP were abrogated by mannose or high-mannose type oligomannose-oligosaccharide. The latter carbohydrate is the ligand of the 40-kDa glycoprotein of C. trachomatis L2, which is known to mediate attachment, suggesting that the MBP binds to high mannose moieties on the surface of chlamydial organisms. These results suggest that MBP plays a role in first-line host defense against chlamydial infection in humans.

Conotruncal cardiac anomalies and otitis media

BACKGROUND

The neural crest influences the differentiation of the branchial arches, including the precursor tissue of the cardiac outflow tract and the eustachian tubes. Abnormal eustachian tubes are associated with otitis media. We hypothesized a relationship between conotruncal anomalies and eustachian tube anomalies.

METHODS

We surveyed 115 nonsyndromic patients, aged 5 to 20 years, attending a state-run pediatric cardiology clinic. The cardiac anomalies were conotruncal (transposition of the great arteries, tetralogy of Fallot, or aortic stenosis) or nonconotruncal (atrial septal defect, tricuspid atresia, atrioventricular canal). Tympanic membrane photographs were categorized independently by two physicians as to normal, abnormal (scarred or other indication of otitis proneness), or indeterminate.

RESULTS

For the 37 patients who had both ears categorized as normal or abnormal by both physicians, 20 of the 26 with a conotruncal anomaly had evidence of otitis media. In contrast, only 4 of 11 with nonconotruncal cardiac anomaly had evidence of otitis (p < 0.03; relative risk [conotruncal vs nonconotruncal], 5.83; 95% confidence interval, 1.26 to 26.95).

CONCLUSION

The concept is supported that a neural crest determined branchial field defect influences the development of the cardiac outflow tract and the eustachian tubes. Children with congenital cardiac conotruncal anomalies are otitis media prone.

Genetics of infectious disease resistance

The identification of large numbers of candidates genes and the introduction of methodologies for whole-genome screening have provided new opportunities for elucidating the molecular basis of variable susceptibility to major infectious diseases. 12 genes have been implicated in variable susceptibility to malaria and susceptibility/resistance genes for several other infectious diseases are beginning to be identified. Recent work suggests that large-scale family linkage and population association studies will be a more successful route to human disease genes than extrapolation from mouse models of infection.

The collectins in innate immunity

The collectins are proteins with collagen tails and globular lectin domains that appear to play an important role in mammalian first line host defense. Recent insights have clarified the structural basis of ligand recognition, the interactions of collectins with complement cascades, and the association with disease susceptibility.

Increased frequency of homozygosity of abnormal mannan-binding-protein alleles in patients with suspected immunodeficiency

A low plasma concentration of mannan-binding protein (MBP) impairs opsonisation and phagocytosis. Three different mutations in the MBP gene have a dominant effect on MBP concentration. We investigated the frequency of the abnormal MBP alleles in 228 unrelated patients suspected of various non-HIV-related immunodeficiencies. The frequency of heterozygotes for the abnormal alleles was not different from that in the background population (36.0% and 37.4%, respectively). By contrast, the frequency of homozygotes for the abnormal alleles was significantly increased (8.3% and 0.8%, respectively; p = 0.0017). This finding implies that homozygotes for abnormal MBP alleles are predisposed to recurrent infections.