No abstract available.
Animals ; Apoptosis/*physiology ; Claudins/*metabolism ; Colitis/*physiopathology ; Intestinal Mucosa/*physiopathology ; Mannose-Binding Lectin/*immunology

OBJECTIVETo explore the association between the genetic polymorphisms of mannose-binding protein (MBP) alleles and susceptibility to pulmonary tuberculosis.

METHODS125 pulmonary tuberculosis cases and 198 healthy controls were collected. A case-control study was conducted. Three structural gene mutations in exon 1 of MBP gene (codon 52, codon 54 and codon 57) were studied. Polymerase chain reaction with sequence-specific primers (PCR-SSP) was carried out in the polymorphism in MBP alleles. Information on related risk factors of tuberculosis was collected, using a pre-tested questionnaire. Univariate and multivariate logistic analyses were conducted with SPSS software package.

RESULTSThe frequencies of mutant heterozygote or homozygote of MBP-52, 54, 57 were 8.0%, 7.2% and 0.4% for cases and 5.3%, 4.3%, 0.5% for controls, respectively. The distribution of mutant genotypes of MBP did not show significant difference between tuberculosis patients and control by Mantel-Haenszel chi2 on sex. The univariate analysis demonstrated that body mass index, marital status, vaccinal vestige, bacillus of Calmette-Guerin vaccine immunization, contacted with pulmonary tuberculosis patients, familial traits were the risk factors of pulmonary tuberculosis. After adjusting those related environmental factors in the multivariate logistic analyses, the total MBP (MBP-52, MBP-54 and MBP-57) and MBP-52 heterozygote genotypes were significantly overrepresented in cases, with adjusted OR (95% CI) being 2.182 (1.058-4.499) and 2.574 (1.028-6.446).

CONCLUSIONTotal MBP and MBP-52 mutant genotypes might be associated with the susceptibility to pulmonary tuberculosis.

Case-Control Studies ; Genetic Predisposition to Disease ; Humans ; Mannose-Binding Lectin ; genetics ; Polymorphism, Genetic ; Tuberculosis, Pulmonary ; genetics

OBJECTIVETo investigate the effects of mannan-binding lectin (MBL) on the maturation and cytokine secretion of human dendritic cells (DC) induced by Candida albicans (C. albicans).

METHODSThe plastic-adherent mononuclear cells were prepared from the blood of healthy adult volunteers. The human peripheral blood mononuclear cells-derived dendritic cells (MNC-DC) were induced by 5-day-culture in medium supplemented with rhGM-CSF and rhIL-4, and then cultured for 2 days in presence or absence of C. albicans at varying concentration of human MBL ranging from 1 to 20 mg/L. DC's shape and characters were observed under inverted microscopy, the expression of CD83 and CD86 on DC was analyzed by FACS. The levels of TNF-α and IL-6 were detected by ELISA. FACS also was used to investigate the interaction of MBL with immature DC(imDC) and C. albicans. Western blot was used to detect C. albicans-induced IκBα phosphorylation and p65/NF-κB translocation in DC.

RESULTSMBL at higher concentrations (10-20 mg/L) down-regulated the expression of CD83 and CD86 on the monocyte-derived dentritic cells(MoDC) induced by C. albicans, and inhibited the production of TNF-α and IL-6 induced by C. albicans. FACS showed that MBL could not only bind to C. albicans but also bind to imDCs in a Ca2+-dependent manner. Western blot showed that MBL could decrease the phosphorylation of IκBα and the nuclear translocation of p65/ NF-κB.

CONCLUSIONMBL may inhibit TNF-α and IL-6 production induced by C. albicans in DC through NF-κB signaling pathways, suggesting that MBL can play some roles in the regulation of C. albicans-induced immune response.

Candida albicans ; Cell Differentiation ; Cytokines ; Dendritic Cells ; Humans ; Mannose-Binding Lectin ; NF-kappa B ; Protein Transport

OBJECTIVEMannan-binding lectin (MBL) is a C-type serum lectin that plays a central role in the innate immune response. At present there is no a reference range of serum MBL levels for children in China. This study investigated serum MBL levels in preschool children from Shenzhen.

METHODSA total of 118 children (62 boys and 56 girls) at ages of 3-6 years and sampled randomly from three kindergartens of Shenzhen were enrolled in this study. Serum MBL concentrations were determined using enzyme-linked immunosorbent assay.

RESULTSThe mean serum MBL concentration in these children was 779.07+/-268.98 ng/mL. There were no significant differences in the value of serum MBL between boys and girls (783.89+/-252.30 ng/mL vs 773.65+/-288.29 ng/mL) (P>0.05). Sixteen children (13.6%) had MBL concentrations less than 500 ng/mL (the low limited value used abroad), including 14 cases with 50-500 ng/mL and 2 cases with less than 50 ng/mL.

CONCLUSIONSThis study provides a reference range of serum MBL concentration for preschool children. MBL may be a useful marker for the prevention of infection in children.

Child ; Child, Preschool ; Female ; Humans ; Immunity, Innate ; Male ; Mannose-Binding Lectin ; blood

OBJECTIVETo purify Mannan-binding lectin (MBL) from human serum and detect its binding ability to several kinds of bacteria common in infectious diseases of children.

METHODSMBL was purified from human serum by affinity chromatography on mannan-Sepharose 4B column. Its binding ability to eight species, 97 strains of bacteria was detected by enzyme-linked lectin assay (ELLA).

RESULTSMBL has different binding ability to bacteria and shows strong binding ability to Klebsiella ornithinolytica and Escherichia coli, but shows relatively lower binding ability to Staphylococcus haemolyticus, Enterobacter cloacae and Staphylococcus epidermidis. To different isolates of Klebsiella pneumoniae, Haemophilus influenzae and Staphylococcus aureus, MBL shows quite different binding ability.

CONCLUSIONSMBL has different binding ability to different bacteria, and has relatively stronger binding ability to Gram-negative bacteria. Its binding ability to different isolates of certain kinds of bacteria is quite different.

Bacteria ; classification ; metabolism ; Child ; Child, Preschool ; Communicable Diseases ; microbiology ; Humans ; Mannose-Binding Lectin ; blood ; metabolism ; Protein Binding ; Species Specificity

BACKGROUND: Mannose-binding lectin (MBL) is a serum protein of innate immunity. Its genetic mutations lead to deficiency of serum MBL and recurrent pyogenic infection in childhood. However, little is known about the frequency of its gene mutations or serum levels in Korean population and patients with cancers. METHODS: We studied the mutational genotypes of MBL exon 1 codon 52, 54, and 57 or serum MBL levels from 102 normal adults and 228 cases of breast, stomach, colon, uterine cervical, and lung cancers by allele-specific PCR and enzyme-linked immunosorbent assay. RESULTS: MBL gene mutations were found in 32 of 102 normal adults (31.4%), and were restricted only to exon 1 codon 54 showing homozygous (n=5, 4.9%) or heterozygous mutations (n=27, 26.5%). Mean and median serum MBL in the patients with cancers were increased (2,647+/-1,742 and 2,915 ng/mL, mean+/-S.D. and median) than those of normal adults (1,906+/-1,359 and 1,758 ng/mL). Serum MBL level was significantly increased in the patients with stomach, uterine cervical, colon, and lung cancers. CONCLUSION: Our results indicate that the frequency and pattern of MBL gene mutations and its serum level is very similar among northeastern Asian populations. In addition, MBL might be involved in an immunologic response against common cancers, although further studies are needed.
Adult ; Asian Continental Ancestry Group ; Breast ; Codon ; Colon ; Enzyme-Linked Immunosorbent Assay ; Exons ; Genotype ; Humans ; Immunity, Innate ; Lung Neoplasms ; Mannose ; Mannose-Binding Lectin* ; Polymerase Chain Reaction ; Stomach

We purified a novel mannose binding lectin form Musca domestica pupae by affinity chromatography on Con A-Sepharose 4B and DEAE weak anion-exchange chromatography. By SDS-PAGE, MBL-1 yielded a single band with the molecular weight of 24 kDa. It was a glycoprotein detected by periodic acid-schiffs staining reaction, with 97.36% protein and 2.1% oligosaccharide. Meanwhile, the results of beta-elimination reaction, infrared spectroscopy, atomic force microscopy and protein sequencing instrument show that MBL-1 was an ellipsoidal-shaped monomer with 60-100 nm in diameter. N-glycoside bond linked oligosaccharide chain and the N-terminal blocked peptide chain. Further study suggested that MBL-1 promote the proliferation of macrophage in a concentration-dependent manner. The scanning electron microscope analysis shows that MBL-1 promoted the activation of macrophages. These results show that MBL-1 purified from Musca domestica pupae possesses immune regulation effect, serving a reference basis to develop natural immune-modulator.
Animals ; Glycoproteins ; analysis ; Houseflies ; chemistry ; Immunomodulation ; immunology ; physiology ; Macrophages ; immunology ; Mannose-Binding Lectin ; chemistry ; physiology ; Oligosaccharides ; analysis ; Pupa ; chemistry

OBJECTIVETo prepare the trimeric subunits of recombinant human mannan-binding lectin (MBL) with biological activities.

METHODSA prokaryotic expression vector containing human MBL N-terminal deletant (rhMBLδN) gene we previously constructed was transformed into E. coli for efficient expression of rhMBLδN fusion protein. Based on the principle that the collagen polypeptides tend to self-assembly into the tertiary structure of proteins by forming a triple helix due to the characteristic properties of the collagen proteins, rhMBLδN fusion protein was limitedly hydrolyzed with thrombin. The obtained rhMBLδN polypeptide was repeatedly dialyzed in 50 mmol/L PBS (pH7.2) and ddH(2)O, and the final product was analyzed for its bioactivities using a ligand-binding assay and a C4d deposition assay.

RESULTSrhMBLδN polypeptide with a relative molecular mass of about 20 000 was obtained by limited proteolysis of rhMBLδN fusion protein with thrombin. Repeated dialyses of rhMBLδN polypeptides in 50 mmol/L PBS and ddH(2)O resulted in the isolation of the trimeric subunit trhMBLδN (with a relative molecular mass of about 50 000), which contained a collagen-like helix. The trhMBLδN protein had a higher ligand-binding activity than rhMBLδN polypeptide, and acquired the activity to initiate the lectin pathway of complement activation, but the activities were lower than those of natural MBL.

CONCLUSIONWe have successfully obtained the bioactive trimeric subunit of rhMBL, trhMBLδN, and this structural subunit is also the functional subunit of the MBL molecule.

Complement Activation ; Escherichia coli ; metabolism ; Genetic Vectors ; Humans ; Mannose-Binding Lectin ; biosynthesis ; genetics ; isolation & purification ; Recombinant Proteins ; biosynthesis

OBJECTIVETo investigate the effects of mannan-binding lectin (MBL) on the functions of human polymorphonuclear cells (PMNs).

METHODSELISA and Dot blot were performed to examine the binding between MBL and the microorganisms. Flow cytometry and fluorescence microscopy were employed to analyze the phagocytosis of FITC-labeled microorganisms by the PMNs. Real-time quantitative PCR was used to detect the expression levels of IL-1β, TNF-α and CD11b mRNA in the PMNs, and ELISA used to detect the levels of TNF-α and IL-6 in the supernatants of PMN culture. Nitro-blue tetrazolium reduction assay was used to estimate the levels of superoxide production.

RESULTSMBL bound to the microorganisms in a dose-dependent manner. MBL had no significant effect on phagocytosis of C. albicans and E.coli by the PMNs in the absence of human serum, but in presence of mixed MBL-deficient human sera, MBL promoted the phagocytosis of C. albicans, which could be blocked by mannan. Mannan treatment increased the expressions of IL-1β, TNF-α, IL-6 and CD11b and enhanced superoxide production in the PMNs.

CONCLUSIONMBL can promote phagocytosis of microorganisms by PMNs and increase the expressions of proinflammatory cytokines from PMNs in a complement lectin pathway-dependent manner.

Candida albicans ; immunology ; Cells, Cultured ; Cytokines ; immunology ; Escherichia coli ; immunology ; Humans ; Mannose-Binding Lectin ; blood ; Neutrophils ; immunology ; Phagocytosis ; Superoxides ; immunology

Mannan-binding lectin (MBL) is a soluble innate immune protein that binds to glycosylated targets. MBL acts as an opsonin and activates complement, contributing to the destruction and clearance of infecting microorganisms. Hepatitis C virus (HCV) encodes two envelope glycoproteins E1 and E2, expressed as non-covalent E1/E2 heterodimers in the viral envelope. E1 and E2 are potential ligands for MBL. Here we describe an analysis of the interaction between HCV and MBL using recombinant soluble E2 ectodomain fragment, the full-length E1/E2 heterodimer, expressed in vitro, and assess the effect of this interaction on virus entry. A binding assay using antibody capture of full length E1/E2 heterodimers was used to demonstrate calcium dependent, saturating binding of MBL to HCV glycoproteins. Competition with various saccharides further confirmed that the interaction was via the lectin domain of MBL. MBL binds to E1/E2 representing a broad range of virus genotypes. MBL was shown to neutralize the entry into Huh-7 cells of HCV pseudoparticles (HCVpp) bearing E1/E2 from a wide range of genotypes. HCVpp were neutralized to varying degrees. MBL was also shown to neutralize an authentic cell culture infectious virus, strain JFH-1 (HCVcc). Furthermore, binding of MBL to E1/E2 was able to activate the complement system via MBL-associated serine protease 2. In conclusion, MBL interacts directly with HCV glycoproteins, which are present on the surface of the virion, resulting in neutralization of HCV particles.
Binding, Competitive ; Glycosylation ; Hepacivirus ; genetics ; pathogenicity ; physiology ; Humans ; Mannose-Binding Lectin ; metabolism ; Mannose-Binding Protein-Associated Serine Proteases ; metabolism ; Monosaccharides ; metabolism ; Protein Binding ; Protein Multimerization ; Tumor Cells, Cultured ; Viral Envelope Proteins ; metabolism ; Virion ; pathogenicity ; physiology ; Virus Internalization