Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0348321 (Haemophilus)
15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aggregation of non-serotypable Haemophilus influenzae (NTHI) by whole saliva from patients with chronic obstructive lung disease (COLD) was investigated. Significant differences were observed between salivary aggregating activity of a control and COLD population (P < 0.001). Saliva from patients less prone to acute exacerbations had a greater capacity to aggregate bacteria compared with saliva from patients with a predilection to infection. The mechanism of saliva-mediated aggregation of NTHI was investigated and shown to be related to lysozyme content. Lysozyme activity in saliva was measured by the turbidimetric technique and results showed that patients with chronic bronchitis had increased levels of salivary lysozyme, with a subpopulation within the non-infection-prone group having greater amounts. A significant difference was observed in salivary lysozyme between controls and non-infection-prone (P < 0.005) and infection-prone (P < 0.05) patients, respectively: the non-infection-prone patients having significantly (P < 0.005) more than the infection-prone patients. There was significant correlation (r = 0.742, P < 0.001) between salivary aggregation of NTHI and lysozyme activity. Chromatographically purified human lysozyme had a similar aggregation profile to that of saliva. There was no difference in serum and saliva lactoferrin concentrations between groups, but there was a significant increase (P < 0.05) in serum lysozyme concentration in the non-infection-prone group. This study suggests that the level of salivary lysozyme derived from macrophages may play an important role in determining resistance or susceptibility to acute bronchitis.
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PMID:A possible role for lysozyme in determining acute exacerbation in chronic bronchitis. 758 99

Two strains of Haemophilus parasuis, namely, the type strain (ATCC 19417) and strain E751, were investigated with respect to iron acquisition. Both strains produced iron-repressible outer membrane proteins and could acquire iron from porcine transferrin but not from porcine lactoferrin. Neither strain used bovine transferrin, and human transferrin was used to only a very limited extent, if at all. In all cases, iron acquisition from transferrin required direct contact between the organisms and the protein. An affinity isolation technique based on biotinylated porcine transferrin plus streptavidin-agarose, followed by SDS-PAGE, allowed the isolation and identification of two potential porcine transferrin binding polypeptides (94 and 60 kDa) from total membranes derived from the type strain grown under iron-restricted conditions but only one (96 kDa) from strain E751. Each of these polypeptides was iron repressible and was not isolated when biotinylated human or bovine transferrin was used instead of biotinylated porcine transferrin. It is concluded that both strains acquire transferrin-bound iron by means of siderophore-independent mechanisms and that the isolated polypeptides represent porcine transferrin receptor components.
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PMID:Contact-dependent acquisition of transferrin-bound iron by two strains of Haemophilus parasuis. 772 56

Nontypeable Haemophilus influenzae strains are the most common pathogens encountered in patients with chronic bronchitis. These organisms chronically colonize the airways of patients and occasionally cause bacteremia. Nontypeable H. influenzae strains have been demonstrated microscopically to bind to mucus, but quantitative studies of adhesion have not been published to date. We have therefore developed a reproducible microtiter plate assay to study mucin binding and have examined the adhesion of sputum and blood strains of nontypeable H. influenzae. The assay is similar to that described for Pseudomonas aeruginosa (S. Vishwanath and R. Ramphal, Infect. Immun. 45:197-202, 1984), but notably 2% Tween 20 is used to desorb bacteria from the wells to quantitate bacterial binding. Using a standard strain, we have established that 1 h of incubation is optimum with an inoculum of < or = 5 x 10(8) CFU/ml. The standard strain binds to bronchitic and cystic fibrosis mucins equally well but binds less to bronchiectasis mucins. It does not bind to bovine serum albumin or fetuin. We have also examined the levels of adhesion of freshly isolated sputum and bacteremia strains and find very significant differences in adhesion. Blood strains bound six to seven times less than sputum strains ([13.8 +/- 7] x 10(2) per well versus [102 +/- 43] x 10(2); P < 0.001). Studies with adhesion to lactoferrin, another glycosylated protein, revealed variable binding of respiratory strains but marked binding of blood strains compared with mucin. An isogenic pair of respiratory and blood isolates was examined by electron microscopy but did not show surface differences. We speculate that bacteremic strains studied may have masked, lost, or downregulated adhesin production to allow them to escape from mucins or upregulated adhesins for lactoferrin to invade the bloodstream.
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PMID:Adhesion of nontypeable Haemophilus influenzae from blood and sputum to human tracheobronchial mucins and lactoferrin. 786 61

Lactoferrin (LF), a cationic 80-kDa protein present in polymorphonuclear leukocytes and in mucosal secretions, is known to have antibacterial effects on gram-negative bacteria, with a concomitant release of lipopolysaccharides (LPS, endotoxin). In addition, LF is known to decrease LPS-induced cytokine release by monocytes and LPS priming of polymorphonuclear leukocytes. Its mechanism of action is incompletely understood. We have now demonstrated by in vitro-binding studies that LF binds directly to isolated lipid A and intact LPS of clinically relevant serotypes of the species which most frequently cause bacteremia (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa), as well as to lipid A and LPS of mucosal pathogens (among others, Neisseria meningitides and Haemophilus influenzae). Binding to LPS was inhibitable by lipid A and polymyxin B but not by KDO (3-deoxy-D-manno-octulosonate), a glycoside residue present in the inner core of LPS. Binding of LF to lipid A was saturable, and an affinity constant of 2 x 10(9) M-1 was calculated for the LF-lipid A interaction. Our data may explain, in part, the mechanism whereby LF exerts its antibacterial and anti-endotoxic effects. Further studies on the ability of LF to block the detrimental effects of LPS, both in vitro and in vivo, are warranted.
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PMID:Lactoferrin is a lipid A-binding protein. 818 89

We have recently cloned and characterized the hemoglobin (Hb) receptor gene, hmbR, from Neisseria meningitidis. To identify additional proteins that are involved in Hb utilization, the N. meningitidis Hb utilization system was reconstituted in Escherichia coli. Five cosmids from N. meningitidis DNA library enabled a heme-requiring (hemA), HmbR-expressing mutant of E. coli to use Hb as both porphyrin and iron source. Nucleotide sequence analysis of DNA fragments subcloned from the Hb-complementing cosmids identified four open reading frames, three of them homologous to Pseudomonas putida, E. coli, and Haemophilus influenzae exbB, exbD, and tonB genes. The N. meningitidis TonB protein is 28.8 to 33.6% identical to other gram-negative TonB proteins, while the N. meningitidis ExbD protein shares between 23.3 and 34.3% identical amino acids with other ExbD and TolR proteins. The N. meningitidis ExbB protein was 24.7 to 36.1% homologous with other gram-negative ExbB and TolQ proteins. Complementation studies indicated that the neisserial Ton system cannot interact with the E. coli FhuA TonB-dependent outer membrane receptor. The N. meningitidis tonB mutant was unable to use Hb, Hb-haptoglobin complexes, transferrin, and lactoferrin as iron sources. Insertion of an antibiotic cassette in the 3' end of the exbD gene produced a leaky phenotype. Efficient usage of heme by N. meningitidis tonB and exbD mutants suggests the existence of a Ton-independent heme utilization mechanism. E. coli complementation studies and the analysis of N. meningitidis hmbR and hpu mutants suggested the existence of another Hb utilization mechanism in this organism.
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PMID:Neisseria meningitidis tonB, exbB, and exbD genes: Ton-dependent utilization of protein-bound iron in Neisseriae. 900 36

Since its discovery at the end of the nineteenth century, Moraxella (Branhamella) catarrhalis has undergone several changes of nomenclature and periodic changes in its perceived status as either a commensal or a pathogen. Molecular analysis based on DNA hybridisation or 16S rDNA sequence comparisons has established its phylogenetic position as a member of the Moraxellaceae and shown that it is related more closely to Acinetobacter spp. than to the genus Neisseria in which it was placed formerly. However, confusion with phenotypically similar Neisseria spp. can occur in the routine diagnostic laboratory if appropriate identification tests are not performed. M. catarrhalis is now accepted as the third commonest pathogen of the respiratory tract after Streptococcus pneumoniae and Haemophilus influenzae. It is a significant cause of otitis media and sinusitis in children and of lower respiratory tract infections in adults, especially those with underlying chest disease. Nosocomial spread of infection, especially within respiratory wards, has been reported. Invasive infection is uncommon, but analysis of reports for England and Wales between 1992 and 1995 revealed 89 cases of M. catarrhalis bacteraemia, with the peak incidence in children aged 1-2 years. Carriage rates of M. catarrhalis are high in children and in the elderly, but its role as a commensal organism has probably been overstated in the past. Approximately 90% of strains are now beta-lactamase positive and, given that the first such strain was reported in 1976, this represents a dramatic increase in frequency over the last 20 years which has not been paralleled in any other species. The BRO-1 and BRO-2 beta-lactamase enzymes of M. catarrhalis are found in other Moraxellaceae, but are not related to beta-lactamases of any other species and their origin is therefore unknown. Molecular and typing studies have shown that the M. catarrhalis species is genetically heterogeneous and these methods have aided epidemiological investigation. Studies of factors that may be related to pathogenicity have shown the existence of three serotypes of lipooligosaccharide and the presence of fimbriae and a possible capsule. Some strains are serum-resistant, probably by virtue of interference with complement action, whilst transferrin- and lactoferrin-binding proteins enable the organism to obtain iron from its environment. An antibody response in humans to various M. catarrhalis antigens, including highly conserved outer-membrane proteins, has been demonstrated. Increased understanding of the organism's pathogenic properties and the host response to it may help to identify suitable vaccine targets or lead to other strategies to prevent infection. Whilst it remains, at present, the third most important respiratory pathogen, the impact of immunisation strategies for other organisms may change this position. The speed with which M. catarrhalis acquired beta-lactamase demonstrates the capacity of this organism to surprise us.
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PMID:Moraxella (Branhamella) catarrhalis--clinical and molecular aspects of a rediscovered pathogen. 915 30

Since the ability of bacteria to compete with lactoferrin for iron contributes to the pathogenesis of mucosal infections, the presence of lactoferrin receptor activity in non-encapsulated Haemophilus influenzae was investigated. The growth of 18 H. influenzae isolates from the sputum samples of chronic bronchitis patients and of six of seven H. influenzae throat isolates from healthy adults was stimulated by iron saturated human lactoferrin. Apo-lactoferrin did not stimulate the growth of H. influenzae. Human lactoferrin binding to iron limited bacteria was detected for 16 H. influenzae strains from chronic bronchitis patients and for five of seven isolates from healthy adults. We conclude that the majority of H. influenzae isolates tested bind human lactoferrin and that the iron from lactoferrin is used for growth.
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PMID:Human lactoferrin receptor activity in non-encapsulated Haemophilus influenzae. 936 77

Airway inflammation during infection is associated with increased transudation of serum proteins and increased production of protein by the airway epithelium. We therefore, assessed whether Haemophilus influenzae infections in patients with chronic bronchitis are associated with increased levels of transferrin and lactoferrin in the sputum compared to uninfected patients. Sputum sol phase and serum samples from 14 infected and 13 uninfected patients with chronic bronchitis and from 12 bronchial asthma patients were included in the study. The median Q-values (the concentration in sputum sol phase/the concentration in serum) x 10(3) of transferrin appeared increased in chronic bronchitis patients with an H. influenzae infection (26.0, n=13) compared to uninfected controls (9.5, n=11) and bronchial asthma patients (4.5, n=6). The ratio of the Q(transferrin)/Q(albumin) was >1 in infected chronic bronchitis patients, indicating local production of transferrin. Growth of H. influenzae was stimulated more in sputum from infected and uninfected patients with chronic bronchitis than in sputum from patients with bronchial asthma. The concentrations of lactoferrin were not significantly different in infected (n=14) and uninfected (n=13) chronic bronchitis patients and bronchial asthma patients (n=12) (median 137.4, 84.6, 87.1 mg x L(-1), respectively). We conclude that in patients with chronic bronchitis with Haemophilus influenzae infections, the levels of transferrin are increased and the levels of lactoferrin are not associated with infections.
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PMID:Iron-binding proteins in sputum of chronic bronchitis patients with Haemophilus influenzae infections. 938 61

Haemophilus influenzae is a major cause of otitis media and other respiratory tract disease in children. The pathogenesis of disease begins with colonization of the upper respiratory mucosa, a process that involves evasion of local immune mechanisms and adherence to epithelial cells. Several studies have demonstrated that human milk is protective against H. influenzae colonization and disease. In the present study, we examined the effect of human milk on the H. influenzae IgA1 protease and Hap adhesin, two autotransported proteins that are presumed to facilitate colonization. Our results demonstrated that human milk lactoferrin efficiently extracted the IgA1 protease preprotein from the bacterial outer membrane. In addition, lactoferrin specifically degraded the Hap adhesin and abolished Hap-mediated adherence. Extraction of IgA1 protease and degradation of Hap were localized to the N-lobe of the bilobed lactoferrin molecule and were inhibited by serine protease inhibitors, suggesting that the lactoferrin N-lobe may contain serine protease activity. Additional experiments revealed no effect of lactoferrin on the H. influenzae P2, P5, and P6 outer-membrane proteins, which are distinguished from IgA1 protease and Hap by the lack of an N-terminal passenger domain or an extracellular linker region. These results suggest that human milk lactoferrin may attenuate the pathogenic potential of H. influenzae by selectively inactivating IgA1 protease and Hap, thereby interfering with colonization. Future studies should examine the therapeutic potential of lactoferrin, perhaps as a supplement in infant formulas.
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PMID:Human milk lactoferrin inactivates two putative colonization factors expressed by Haemophilus influenzae. 977 May 39

Moraxella catarrhalis-induced otitis media continues to be a significant cause of infection in young children, prompting increased efforts at identifying effective vaccine antigens. We have previously demonstrated that M. catarrhalis expresses specific outer membrane proteins (OMPs) in response to iron limitation and that this organism can utilize transferrin and lactoferrin for in vitro growth. One of these proteins, which binds human transferrin, is OMP B1. As the human host presents a naturally iron-limited environment, proteins, like OMP B1, which are expressed in response to this nutritional stress are potential vaccine antigens. In this study, we have developed monoclonal antibody (MAb) 11C6, which reacts to a surface-exposed epitope of OMP B1 expressed by M. catarrhalis 7169. This antibody was used to clone ompB1, and sequence analysis suggested that OMP B1 is the M. catarrhalis homologue to the transferrin binding protein B described for pathogenic Neisseriaceae, Haemophilus influenzae, Actinobacillus pleuropneumoniae, and M. catarrhalis. Expression of recombinant OMP B1 on the surface of Escherichia coli confers transferrin binding activity, confirming that this protein is likely involved in iron acquisition. In addition, ompB1 was used to construct an isogenic mutant in M. catarrhalis 7169. This mutant, termed 7169b12, was used as the control in bactericidal assays designed to determine if OMP B1 elicits protective antibodies. In the presence of MAb 11C6 and human complement, wild-type 7169 demonstrated a 99% decline in viability, whereas the ompB1 isogenic mutant was resistant to this bactericidal activity. Further analysis with MAb 11C6 revealed the presence of this OMP B1 epitope on 31% of the clinical isolates tested. These data suggest that OMP B1 is a potential vaccine antigen against M. catarrhalis infections.
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PMID:Use of an isogenic mutant constructed in Moraxella catarrhalis To identify a protective epitope of outer membrane protein B1 defined by monoclonal antibody 11C6. 991 77


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