PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Collectins”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2026

Crown ethers as artificial decoys: A supramolecular strategy to block SARS-CoV-2 entry via host-guest interactions.

Coronavirus disease (COVID-19) remains a major global health challenge, highlighting the need for antiviral strategies that act at the earliest stages of infection. Given that viral entry and spike-receptor interaction are critical steps in the coronavirus life cycle, targeting these processes represents a powerful strategy to block infection at its earliest stage. Inspired by the glycan-recognition and extracellular viral-trapping functions of pulmonary surfactant collectins (SP-A and SP-D), this work integrates supramolecular chemistry, pulmonary surfactant biology, and antiviral research to establish a biomimetic supramolecular molecular-decoy framework based on crown ethers, cyclodextrins, and related macrocyclic architectures. Through host-guest molecular recognition, these macrocyclic scaffolds can be engineered to mimic sialylated host receptors and multivalent glycan motifs, enabling competitive binding to viral spike proteins, virion capture, and sequestration away from epithelial surfaces. By redirecting viruses toward artificial host-mimetic structures, supramolecular decoys could intercept SARS-CoV-2 and other enveloped respiratory viruses before host-cell attachment, membrane fusion, or genome release. Acting upstream of intracellular replication, this strategy may prevent initiation of the viral replication cycle and subsequent hijacking of the host protein synthesis machinery, while potentially minimizing interference with host metabolic pathways and reducing the likelihood of resistance development. Furthermore, it can be translated into inhalation nanoformulations for pulmonary delivery and localized formulations targeting the upper respiratory tract. Overall, by integrating the biological principles of pulmonary surfactant immunity with supramolecular host-guest chemistry, this work provides a conceptual foundation for biomimetic molecular-decoy antivirals and highlights a promising direction for next-generation broad-spectrum antiviral design against emerging respiratory viruses.

Antiviral Agents↗
PubMed2024

Proteomics identifies complement protein signatures in patients with alcohol-associated hepatitis.

Diagnostic challenges continue to impede development of effective therapies for successful management of alcohol-associated hepatitis (AH), creating an unmet need to identify noninvasive biomarkers for AH. In murine models, complement contributes to ethanol-induced liver injury. Therefore, we hypothesized that complement proteins could be rational diagnostic/prognostic biomarkers in AH. Here, we performed a comparative analysis of data derived from human hepatic and serum proteome to identify and characterize complement protein signatures in severe AH (sAH). The quantity of multiple complement proteins was perturbed in liver and serum proteome of patients with sAH. Multiple complement proteins differentiated patients with sAH from those with alcohol cirrhosis (AC) or alcohol use disorder (AUD) and healthy controls (HCs). Serum collectin 11 and C1q binding protein were strongly associated with sAH and exhibited good discriminatory performance among patients with sAH, AC, or AUD and HCs. Furthermore, complement component receptor 1-like protein was negatively associated with pro-inflammatory cytokines. Additionally, lower serum MBL associated serine protease 1 and coagulation factor II independently predicted 90-day mortality. In summary, meta-analysis of proteomic profiles from liver and circulation revealed complement protein signatures of sAH, highlighting a complex perturbation of complement and identifying potential diagnostic and prognostic biomarkers for patients with sAH.

Humans↗
PubMed1989

Antibodies to polyclonal IgA, IgA1, and IgA2 and isotype-specific immune complexes in IgA nephropathy.

The concentrations of serum IgG and IgM antibodies to polyclonal IgA (IgAp), IgA1, and IgA2 were determined by enzyme immunoassay in 31 patients with IgA nephropathy and 30 healthy controls. Patients with IgA nephropathy had significantly raised concentrations of serum IgA compared to controls (Mann-Whitney U test, P = 0.001) and increased concentrations of conglutinin-binding IgA immune complexes (P = 0.024). No differences in the median concentrations of IgG and IgM anti-IgA antibodies were found between the patients and the controls. In serum samples from healthy controls there was a significant positive correlation between IgM anti-IgAp and IgA immune complex concentrations (P = 0.05), which contrasted with the finding of an inverse correlation between IgM anti-IgAp and IgA immune complex concentrations in patients with IgA nephropathy (P less than 0.05). In addition, the concentrations of conglutinin binding IgM immune complexes in serum were found to correlate with the concentration of IgM anti-IgAp (0.010 less than P less than 0.025), IgM anti-IgA1, and IgM anti-IgA2 (P much less than 0.005 for both) in patients with IgA nephropathy but not in controls. IgM anti-IgA antibodies may be important in augmenting the clearance of IgA immune complexes from the serum of patients with IgA nephropathy.

Adolescent↗
PubMed1988

Isolation and characterization of endogenous ligands for liver mannan-binding protein.

Endogenous ligands for the hepatic lectin which is specific for mannose and N-acetylglucosamine (mannan-binding protein, MBP) were isolated from rat liver rough microsomes and primary cultured hepatocytes by affinity chromatography on an immobilized MBP column. Western blotting using specific antisera revealed that serum glycoproteins, alpha 1-macroglobulin, alpha 1-antitrypsin, and alpha 1-acid glycoprotein, and a lysosomal enzyme, beta-glucuronidase were the major constituents of the endogenous ligands. These endogenous ligands consisted of high mannose-type oligosaccharides of Man9GlcNAc2 and Man8GlcNAc2, and had rapid turnover rates with an average half-life of 45 min, indicating that they were mainly composed of biosynthetic intermediates of glycoproteins. In view of the identification of the endogenous ligands as the biosynthetic intermediates of glycoproteins, the possible functions of the intracellular lectin are discussed in relation to the intracellular transport of glycoproteins.

Animals↗
PubMed1988

Isolation and characterization of two distinct mannan-binding proteins from rat serum.

Two binding proteins, which are specific for mannose and N-acetylglucosamine, were isolated from rat serum to homogeneity. The minor component [serum mannan-binding protein I (S-MBP-I)] was indistinguishable from rat liver mannan-binding protein (L-MBP). S-MBP-I had a molecular mass of about 200 kDa and consisted of about six identical 32-kDa subunits; the molecule had a collagen-like structure, and its properties were identical to those of L-MBP. S-MBP-I was also indistinguishable from L-MBP in immunochemical reactivity. Furthermore, the sequence of 15 NH2-terminal amino acids of S-MBP-I was identical to that of L-MBP, the complete primary structure of which has been elucidated [Drickamer, K., Dordal, M. S., and Reynolds, L. (1986) J. Biol. Chem. 261, 6878-6887; Oka, S., Itoh, N., Kawasaki, T., and Yamashina, I. (1987) J. Biochem. 101, 135-144]. The major component (S-MBP-II) had a molecular mass of about 650 kDa and consisted of about 20 identical 31-kDa subunits; it was immunochemically distinct from L-MBP and S-MBP-I, although the molecule had a collagen-like structure similar to L-MBP and S-MBP-I. Metabolic studies using [3H]leucine showed that S-MBP-II is a typical plasma protein turning over with a half-life of 1.6 days. S-MBP-I was unusual in its late appearance and rapid turnover rate in plasma. These results, together with the fact that L-MBP decayed with biphasic curves, suggest that a part of L-MBP is leaked from liver into plasma in the form of S-MBP-I.

Amino Acid Sequence↗
PubMed1987

The carbohydrate specificity of conglutinin and its homology to proteins in the hepatic lectin family.

Inhibition experiments with D-mannose oligosaccharides establish that conglutinin recognises terminal alpha 1----2 mannobiosyl units present in the glycopeptide of the alpha-chain of the complement component C3b. On the basis of its three domain structure and the homology of its N-terminal amino-acid sequence to that of the dog pulmonary surfactant protein, it is proposed that conglutinin is a member of the hepatic lectin family.

Animals↗
PubMed1992

Isolation and characterization of conglutinin as an influenza A virus inhibitor.

Normal horse and guinea pig sera contain alpha 2-macroglobulin which inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H2 and H3 subtypes. On the other hand, normal bovine serum contains a component termed beta inhibitor that inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H1 and H3 subtypes. To investigate the nature of the beta inhibitor of influenza A virus, we purified the conglutinin and examined its characteristics. First, we found a high correlation between the hemagglutination inhibition(HI) titer and conglutinin titer in several bovine sera (r = 0.906, p less than 0.005). The HI of bovine serum was mainly dependent on conglutinin because the HI activity was abrogated by N-acetylglucosamine but not by D-mannose. The conglutinin, purified from bovine serum, had neutralizing-activity as well as HI activity on influenza A viruses of the H1 and H3 subtypes. The HI activity of conglutinin was heat stable (56 degrees C, 30 min), Ca(++)-dependent, and resistant to both neuraminidase and periodate treatments. The HI activity of purified conglutinin was blocked by N-acetylglucosamine but not by D-mannose. The conglutinin was bound to hemagglutinin which had high mannose and complex sugar chains and its binding was inhibited by N-acetylglucosamine and dependent on divalent cations. These data indicate that the beta-like inhibitor activity of bovine serum is mainly dependent on conglutinin which inhibits hemagglutination and neutralizes the virus infectivity by its binding to a carbohydrate site at the HA.

Animals↗
PubMed1987

Antigen-specific circulating immune complexes in Coxiella burnetii-infected guinea pigs.

An antigen-specific conglutinin-binding assay was developed with artificial immune complexes of Coxiella burnetii and an enzyme-linked immunosorbent assay for the detection of circulating immune complexes. Sera from guinea pigs infected with C. burnetii were examined by this assay, and the percentages of infected guinea pigs with C. burnetii antigen-specific circulating immune complexes were 71, 93, 74, 65, 49, and 27%, respectively, from the first to sixth week after infection. C. burnetii antigen eluted from circulating immune complexes by acid dissociation was detected by counterimmunoelectrophoresis. The antigen-specific conglutinin binding assay was specific, sensitive, and reproducible for assay of circulating immune complexes.

Animals↗
PubMed1992

Affinity chromatographic purification of immunoglobulin M antibodies utilizing immobilized mannan binding protein.

A method is described for the rapid and efficient affinity chromatographic purification of murine monoclonal immunoglobulin M (IgM) which utilizes immobilized rabbit mannan binding protein (MBP). This solid-phase matrix is shown to bind IgM-class antibodies from a variety of species. Conditions reported show a binding capacity of IgM from murine ascites of nearly 1 mg/ml of immobilized MBP support. The prepared gel is shown to possess an ability to bind not only mouse IgM, but also human and bovine IgM, although with a lesser affinity. The matrix can be regenerated and reused at least ten times without any apparent loss of binding capacity or specificity. Mouse monoclonal IgM purified from ascites fluid using this method is greater than 95% pure as shown by high-performance liquid chromatography analysis.

Animals↗
PubMed1991

Mannan-binding protein in human liver.

Mannan-binding protein (MBP) is a Ca(2+)-dependent lectin which was first described in 1978 in rabbit liver, and subsequently in serum and liver tissue from humans and a range of animal species. MBP structurally resembles C1q, and may act both as a focus for complement activation on the surface of microorganisms and as an opsonin in its own right. Low serum levels of serum MBP have been described in a group of children known to suffer from severe recurrent infections. MBP has also been reported to behave as an acute phase reactant. This preliminary study has investigated the localisation of MBP in human tissues using material obtained both at post mortem and from diagnostic liver biopsies. Using the IgG fraction of rabbit anti-human MBP, immunoperoxidase staining showed no evidence of significant MBP in a wide range of normal tissues, including liver taken both at post mortem and needle biopsy. However, there was a significant degree of staining for MBP in liver biopsies showing a variety of different pathologies, in particular severely damaged alcoholic livers, and those harbouring metastatic tumour. Moderate degrees of staining were also seen in liver biopsies from patients suffering from chronic biliary disease. It is uncertain whether this localisation of MBP in abnormal liver is an acute phase response, or represents a more fundamental link with liver disease. This question could be the focus for future studies.

Adolescent↗
PubMed1988

Detection of parasite related antigens associated with conglutinin binding immune complexes in patients with Schistosoma haematobium.

An ELISA assay was designed to detect the presence of parasite related antigens associated with circulating immune complexes in patients affected by urinary schistosomiasis. The assay makes use of bovine conglutinin as the immune complex recognition unit and of human anti-Schistosoma antibody as the antigen recognition unit. Using this method we showed that 10 of 15 (67%) patients with a positive polyethylene glycol assay had circulating immune complexes in which parasite antigens could be detected.

Antigen-Antibody Complex↗
PubMed1992

Localization and characterization of the carbohydrate-binding site of the porcine lymphocyte mannan-binding protein.

Mannan-binding proteins found in the liver and serum of several vertebrate species are supposed to play an important role in the intracellular transport of glycoproteins, as well as in several protective reactions including complement activation and elimination of various pathogens. To study these protective functions at molecular level it is necessary to understand the fine oligosaccharide specificity and mutual relation among various forms of these soluble lectins. We have isolated mannan-binding protein as peripheral membrane proteins of porcine lymphocytes. This lectin was purified to homogeneity and shown to possess many properties in common with the well studied rat liver proteins (mol. mass, subunit composition and general organization of the molecule). Binding studies performed with three series of defined oligosaccharides (high mannose, hybrid type, and complex) on native lectin molecules as well as isolated carbohydrate-binding domains revealed distinctive features of this mannan-binding protein, including its impaired ability to bind the oligosaccharide ligand after reduction and decyclization at core N-acetyl-D-glucosamine 1.

Animals↗
PubMedDate not supplied

Mannan-binding protein, a complement activating animal lectin.

Mannan-binding protein is an animal serum lectin (i.e. a molecule with the ability to bind specifically to certain carbohydrate structures). The relevant carbohydrate ligands are found on many pathogenic microorganisms. After binding to suitable carbohydrate ligands, mannan-binding protein is found to be an activator of the classical pathway of complement via an activation of the C1r2C1s2 complex, i.e. antibody and C1q independent. The molecular organization of MBP resembles that of C1q with a distinct division of collagen-like and globular amino acid sequences. This molecular similarity seems to be the basis for the common functional activity of the two proteins. MBP may play an important protective role, especially at early stages of infection prior to the generation of the specific humoral and cellular defence system. The paper explores the structure and the physiological functions of mannan-binding protein.

Animals↗
PubMed1988

A simple isolation procedure for functionally pure components of the bovine alternative complement pathway (ACP) C3 convertase and bovine conglutinin (K).

A simple multicomponent isolation procedure for bovine C3, factor B, factor D and conglutinin (K) from a single serum sample is described. The components of the alternative pathway C3 convertase were isolated in milligram quantities from 800 ml bovine serum and were found to be functionally pure with respect to each other and to factors H and I.

Animals↗
PubMed1989

Detection of conglutinin in bovine serum by complement-dependent agglutination of Escherichia coli.

Agglutination of Escherichia coli (ECA) by normal bovine serum was shown to be prevented by heating serum to 56 degrees C for 30 min, but restored by normal horse, swine, rabbit or guinea pig sera. Further investigation of the ECA reaction using techniques to distinguish between conglutination and immunoconglutination indicated ECA to be a conglutination reaction. Testing of 264 sera obtained from 22 normal cattle over a period of 5 months did not show individual or seasonal variation in ECA. Changes in ECA and conglutination were detected in sera of periparturient cows. The ECA reaction is a simple technique for detecting conglutinin in bovine serum.

Agglutination↗
PubMed1991

Bovine sire effects on daughters' in vitro blood neutrophil functions, lymphocyte blastogenesis, serum complement and conglutinin levels.

Blood neutrophil functions, lymphocyte blastogenic responses, serum complement, and serum conglutinin activity of 98 lactating Holstein cows from two genetic lines were evaluated. The genetic lines were produced in a selection experiment that created and perpetuated genetic differences in milk production for up to seven generations. No significant differences between the two genetic lines of cows were found for neutrophil function, lymphocyte blastogenic responses, serum complement levels, or serum conglutinin levels. Significant differences between sire progeny groups within lines were found for unstimulated and mitogen-stimulated lymphocyte blastogenesis (P less than 0.0001), and almost all neutrophil functions (antibody independent neutrophil cytotoxicity, antibody dependent neutrophil cytotoxicity, ingestion of bacteria, iodination, chemiluminescence, chemokinesis, and chemotaxis (P less than or equal to 0.05)). Sire progeny group differences (P less than or equal to 0.0001) within lines for serum complement and conglutinin activity were also found. Neutrophil chemiluminescence activity (positive relationship; P less than or equal to 0.001), concanavalin A-stimulated lymphocyte blastogenesis (positive relationship; P less than or equal to 0.004), and serum conglutinin activity levels (negative relationship; P less than or equal to 0.01) each had small but significant associations with the total milk somatic cell count. Cows seropositive for bovine leukosis virus had increased resting and mitogen-stimulated lymphocyte blastogenic activity and were associated with increased in vitro neutrophil random migration and production of superoxide anion. Estimates of genetic parameters of various immune cell functions, of serum complement and of conglutinin levels for daughters of 11 sires with 4-6 daughters in the data set were determined. In this report, genetic variation was demonstrated for nonspecific humoral and cellular immunity.

Animals↗