lipid-a and Cystic-Fibrosis

Topics: Acylation; Anti-Bacterial Agents; Bacterial Proteins; Carrier Proteins; Cystic Fibrosis; Drug Resistance, Microbial; Escherichia coli Proteins; Glycosaminoglycans; Humans; Lipid A; Lipopolysaccharides; Lung; Membrane Transport Proteins; Peptides; Pseudomonas aeruginosa; Pseudomonas Infections; RNA-Binding Proteins; Symporters; Virulence

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Topics: Achromobacter; Anti-Bacterial Agents; Cystic Fibrosis; Humans; Lipid A; Lipopolysaccharides; Microbial Sensitivity Tests; Polymyxin B; Polymyxins

Pandoraea sp. is an emerging Gram-negative pathogen in cystic fibrosis causing severe and persistent inflammation and damage of the lungs. The molecular mechanisms underlying the high pathogenicity of Pandoraea species are still largely unknown. As Gram-negatives, Pandoraea sp. express lipopolysaccharides (LPS) whose recognition by the host immune system triggers an inflammatory response aimed at the bacterial eradication from the infected tissues. The degree of the inflammatory response strongly relies on the fine structure of the LPS and, in particular, of its glycolipid moiety, i.e. the lipid A. Here we report the structure of the lipid A isolated from the LPS of a chronic strain of P. pulmonicola (RL 8228), one of the most virulent identified so far among the Pandoraea species. Our data demonstrated that the examined chronic strain produces a smooth-type LPS with a complex mixture of hypoacylated lipid A species displaying, among other uncommon characteristics, the 2-hydroxylation of some of the acyl chains and the substitution by an additional glucosamine on one or both the phosphate groups.

Topics: Acylation; Burkholderiaceae; Cystic Fibrosis; Humans; Lipid A; Lipopolysaccharides; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Pseudomonas aeruginosa (PA) infection in cystic fibrosis (CF) lung disease causes airway neutrophilia and hyperinflammation without effective bacterial clearance. We evaluated the immunostimulatory activities of lipid A, the membrane anchor of LPS, isolated from mutants of PA that synthesize structural variants, present in the airways of patients with CF, to determine if they correlate with disease severity and progression. In a subset of patients with a severe late stage of CF disease, a unique hepta-acylated lipid A, hepta-1855, is synthesized. In primary human cell cultures, we found that hepta-1855 functioned as a potent TLR4 agonist by priming neutrophil respiratory burst and stimulating strong IL-8 from monocytes and neutrophils. hepta-1855 also had a potent survival effect on neutrophils. However, it was less efficient in stimulating neutrophil granule exocytosis and also less potent in triggering proinflammatory TNF-α response from monocytes. In PA isolates that do not synthesize hepta-1855, a distinct CF-specific adaptation favors synthesis of a penta-1447 and hexa-1685 LPS mixture. We found that penta-1447 lacked immunostimulatory activity but interfered with inflammatory IL-8 synthesis in response to hexa-1685. Together, these observations suggest a potential contribution of hepta-1855 to maintenance of the inflammatory burden in late-stage CF by recruiting neutrophils via IL-8 and promoting their survival, an effect presumably amplified by the absence of penta-1447. Moreover, the relative inefficiency of hepta-1855 in triggering neutrophil degranulation may partly explain the persistence of PA in CF disease, despite extensive airway neutrophilia.

Topics: Acylation; Cells, Cultured; Chronic Disease; Cystic Fibrosis; Disease Progression; Exocytosis; HEK293 Cells; Humans; Lipid A; Lipopolysaccharides; Neutrophil Activation; Opportunistic Infections; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; Respiratory Burst; Structure-Activity Relationship; Toll-Like Receptor 4

Pseudomonas aeruginosa, the major pathogen involved in lethal infections in cystic fibrosis (CF) population, is able to cause permanent chronic infections that can persist over the years. This ability to chronic colonize CF airways is related to a series of adaptive bacterial changes involving the immunostimulant lipopolysaccharide (LPS) molecule. The structure of LPSs isolated from several P. aeruginosa strains showed conserved features that can undergo chemical changes during the establishment of the chronic infection. In the present paper, we report the elucidation of the structure and the biological activity of the R-LPS (lipooligosaccharide, LOS) isolated from the persistent CF isolate P. aeruginosa strain RP73, in order to give further insights in the adaptation mechanism of the pathogen in the CF environment. The complete structural analysis of P. aeruginosa RP73 LOS was achieved by chemical analyses, NMR spectroscopy and MALDI MS spectrometry, while the assessment of the biological activity was attained testing the in vivo pro-inflammatory capacity of the isolated LOS molecule. While a typical CF LPS is able to trigger a high immune response and production of pro-inflammatory molecules, this P. aeruginosa RP73 LOS showed to possess a low pro-inflammatory capacity. This was possible due to a singular chemical structure possessing an under-acylated lipid A very similar to the LPS of P. aeruginosa found in chronic lung diseases such as bronchiectstasis.

Topics: Acylation; Animals; Carbon-13 Magnetic Resonance Spectroscopy; Cystic Fibrosis; Inflammation; Lipid A; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Neutrophil Infiltration; Peroxidase; Proton Magnetic Resonance Spectroscopy; Pseudomonas aeruginosa; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Strains of Pseudomonas aeruginosa (PA) isolated from the airways of cystic fibrosis patients constitutively add palmitate to lipid A, the membrane anchor of lipopolysaccharide. The PhoPQ regulated enzyme PagP is responsible for the transfer of palmitate from outer membrane phospholipids to lipid A. This enzyme had previously been identified in many pathogenic Gram-negative bacteria, but in PA had remained elusive, despite abundant evidence that its lipid A contains palmitate. Using a combined genetic and biochemical approach, we identified PA1343 as the PA gene encoding PagP. Although PA1343 lacks obvious primary structural similarity with known PagP enzymes, the β-barrel tertiary structure with an interior hydrocarbon ruler appears to be conserved. PA PagP transfers palmitate to the 3' position of lipid A, in contrast to the 2 position seen with the enterobacterial PagP. Palmitoylated PA lipid A alters host innate immune responses, including increased resistance to some antimicrobial peptides and an elevated pro-inflammatory response, consistent with the synthesis of a hexa-acylated structure preferentially recognized by the TLR4/MD2 complex. Palmitoylation commonly confers resistance to cationic antimicrobial peptides, however, increased cytokine production resulting in inflammation is not seen with other palmitoylated lipid A, indicating a unique role for this modification in PA pathogenesis.

Topics: Acidic Glycosphingolipids; Acyltransferases; Amino Acid Motifs; Amino Acid Sequence; Antimicrobial Cationic Peptides; Bacterial Proteins; Catalytic Domain; Cystic Fibrosis; Cytokines; Drug Resistance, Bacterial; Escherichia coli Proteins; Humans; Immunity, Innate; Lipid A; Lipoylation; Models, Molecular; Molecular Sequence Data; Mutation; Palmitates; Phylogeny; Polymyxin B; Protein Conformation; Protein Structure, Tertiary; Pseudomonas aeruginosa

Pseudomonas aeruginosa can develop resistance to polymyxin as a consequence of mutations in the PhoPQ regulatory system, mediated by covalent lipid A modification. Transposon mutagenesis of a polymyxin-resistant phoQ mutant defined 41 novel loci required for resistance, including two regulatory systems, ColRS and CprRS. Deletion of the colRS genes, individually or in tandem, abrogated the polymyxin resistance of a ΔphoQ mutant, as did individual or tandem deletion of cprRS. Individual deletion of colR or colS in a ΔphoQ mutant also suppressed 4-amino-L-arabinose addition to lipid A, consistent with the known role of this modification in polymyxin resistance. Surprisingly, tandem deletion of colRS or cprRS in the ΔphoQ mutant or individual deletion of cprR or cprS failed to suppress 4-amino-L-arabinose addition to lipid A, indicating that this modification alone is not sufficient for PhoPQ-mediated polymyxin resistance in P. aeruginosa. Episomal expression of colRS or cprRS in tandem or of cprR individually complemented the Pm resistance phenotype in the ΔphoQ mutant, while episomal expression of colR, colS, or cprS individually did not. Highly polymyxin-resistant phoQ mutants of P. aeruginosa isolated from polymyxin-treated cystic fibrosis patients harbored mutant alleles of colRS and cprS; when expressed in a ΔphoQ background, these mutant alleles enhanced polymyxin resistance. These results define ColRS and CprRS as two-component systems regulating polymyxin resistance in P. aeruginosa, indicate that addition of 4-amino-L-arabinose to lipid A is not the only PhoPQ-regulated biochemical mechanism required for resistance, and demonstrate that colRS and cprS mutations can contribute to high-level clinical resistance.

Topics: Anti-Bacterial Agents; Arabinose; Bacterial Proteins; Cystic Fibrosis; DNA Transposable Elements; Drug Resistance, Bacterial; Gene Deletion; Gene Expression Regulation, Bacterial; Genes, Regulator; Genetic Complementation Test; Genetic Loci; Humans; Lipid A; Mutation; Plasmids; Polymyxins; Pseudomonas aeruginosa; Pseudomonas Infections

Pseudomonas aeruginosa can develop resistance to polymyxin and other cationic antimicrobial peptides. Previous work has shown that mutations in the PmrAB and PhoPQ regulatory systems can confer low to moderate levels of polymyxin resistance (MICs of 8 to 64 mg/liter) in laboratory and clinical strains of this organism. To explore the role of PhoPQ in high-level clinical polymyxin resistance, P. aeruginosa strains with colistin MICs > 512 mg/liter that had been isolated from cystic fibrosis patients treated with inhaled colistin (polymyxin E) were analyzed. Probable loss-of-function phoQ alleles found in these cystic fibrosis strains conferred resistance to polymyxin. Partial and complete suppressor mutations in phoP were identified in some cystic fibrosis strains with resistance-conferring phoQ mutations, suggesting that additional loci can be involved in polymyxin resistance in P. aeruginosa. Disruption of chromosomal phoQ in the presence of an intact phoP allele stimulated 4-amino-l-arabinose addition to lipid A and induced transcription from the promoter of the pmrH (arnB) operon, consistent with the known role of this lipid A modification in polymyxin resistance. These results indicate that phoQ loss-of-function mutations can contribute to high-level polymyxin resistance in clinical strains of P. aeruginosa.

Topics: Anti-Bacterial Agents; Bacterial Proteins; Colistin; Cystic Fibrosis; Drug Resistance, Bacterial; Female; Humans; Lipid A; Male; Microbial Sensitivity Tests; Mutation; Polymyxins; Pseudomonas aeruginosa; Pseudomonas Infections

Cystic fibrosis is an autosomal recessive disorder and it is characterised by chronic bacterial airway infection which leads to progressive lung deterioration, sometimes with fatal outcome. Burkholderia multivorans and Burkholderia cenocepacia are the species responsible for most of the infections of cystic fibrosis patients. Lipopolysaccharide endotoxins (LPSs) are among the foremost factors of pathogenesis of Gram-negative infection and, in particular, lipid A is the endotoxic portion of LPS responsible for eliciting host innate immune response. In this work, the complete primary structure of the lipid A from B. multivorans C1576 has been defined and, further, its pro-inflammatory activity in a cystic fibrosis airways model is shown. The structure of B. multivorans lipid A was attained by chemical, mass spectrometry and nuclear magnetic resonance analyses whereas its biological activity was assessed on the intestinal epithelial cell line CACO-2 cells, on the airway epithelial IB3-1 cells, carrying the ΔF508/W1282X CFTR mutation and on an ex vivo model of culture explants of nasal polyps.

Topics: Bronchi; Burkholderia; Caco-2 Cells; Cystic Fibrosis; Enzyme-Linked Immunosorbent Assay; Host-Pathogen Interactions; Humans; Interleukin-8; Lipid A; Magnetic Resonance Spectroscopy; Microscopy, Confocal; Nasal Polyps; Spectrometry, Mass, Electrospray Ionization; Tumor Necrosis Factor-alpha

Pseudomonas aeruginosa (PA) is a ubiquitous environmental Gram-negative bacterium found in soil and water. This opportunistic pathogen can cause infections in individuals with impaired phagocytic function, such as those with burns, exposure to chemotherapy, or cystic fibrosis (CF). PA infects the lungs of most individuals with CF, and is associated with severe progressive pulmonary disease that is the major cause of premature death in this disorder. The specific adaptations of PA to the CF airway responsible for bacterial persistence and antibiotic tolerance are not completely understood but may include increased alginate production (i.e., mucoid phenotype), biofilm formation, and specific lipid A modifications. During adaptation to the CF airway, PA synthesizes a variety of lipid A structures that alter host innate immune responses and promote bacterial persistence and chronic infection. The synthesis of specific lipid A structures is attributable to bacterial enzymes that: (1) remove the 3OH-C10:0 acyl chain from the 3-position (PagL); (2) add a C16:0 acyl chain to the 3OH-C10:0 chain at the 3'-position (PagP); (3) add C12:0 and 2OH-C12:0 acyl chains to the 3OH-C12:0 chains at the 2- and 2'-positions (HtrB and LpxO); and (4) add aminoarabinose to phosphate groups at the 1- and 4'-positions (PmrH, PmrF, PmrI, PmrJ, PmrK, and PmrE). These lipid A modifications represent an essential aspect of PA adaptation to the CF airway.

Topics: Adult; Antimicrobial Cationic Peptides; Carbohydrate Conformation; Carbohydrate Sequence; Child; Cystic Fibrosis; Humans; Inflammation; Lipid A; Lipopolysaccharides; Molecular Sequence Data; Molecular Structure; Pseudomonas aeruginosa; Pseudomonas Infections

Pseudomonas aeruginosa can establish life-long airways chronic infection in patients with cystic fibrosis (CF) with pathogenic variants distinguished from initially acquired strain. Here, we analysed chemical and biological activity of P. aeruginosa Pathogen-Associated Molecular Patterns (PAMPs) in clonal strains, including mucoid and non-mucoid phenotypes, isolated during a period of up to 7.5 years from a CF patient. Chemical structure by MS spectrometry defined lipopolysaccharide (LPS) lipid A and peptidoglycan (PGN) muropeptides with specific structural modifications temporally associated with CF lung infection. Gene sequence analysis revealed novel mutation in pagL, which supported lipid A changes. Both LPS and PGN had different potencies when activating host innate immunity via binding TLR4 and Nod1. Significantly higher NF-kB activation, IL-8 expression and production were detected in HEK293hTLR4/MD2-CD14 and HEK293hNod1 after stimulation with LPS and PGN respectively, purified from early P. aeruginosa strain as compared to late strains. Similar results were obtained in macrophages-like cells THP-1, epithelial cells of CF origin IB3-1 and their isogenic cells C38, corrected by insertion of cystic fibrosis transmembrane conductance regulator (CFTR). In murine model, altered LPS structure of P. aeruginosa late strains induces lower leukocyte recruitment in bronchoalveolar lavage and MIP-2, KC and IL-1beta cytokine levels in lung homogenates when compared with early strain. Histopathological analysis of lung tissue sections confirmed differences between LPS from early and late P. aeruginosa. Finally, in this study for the first time we unveil how P. aeruginosa has evolved the capacity to evade immune system detection, thus promoting survival and establishing favourable conditions for chronic persistence. Our findings provide relevant information with respect to chronic infections in CF.

Topics: Animals; Cell Line; Cell Movement; Chronic Disease; Colony Count, Microbial; Cystic Fibrosis; Cytokines; Humans; Immunity, Innate; Inflammation; Leukocytes; Lipid A; Lung; Mice; Nod1 Signaling Adaptor Protein; Peptides; Peptidoglycan; Pseudomonas aeruginosa; Pseudomonas Infections

Stenotrophomonas maltophilia is a multiple-antibiotic-resistant opportunistic pathogen that is being isolated with increasing frequency from patients with health-care-associated infections and especially from patients with cystic fibrosis (CF). While clinicians feel compelled to treat infections involving this organism, its potential for virulence is not well established. We evaluated the immunostimulatory properties and overall virulence of clinical isolates of S. maltophilia using the well-characterized opportunistic pathogen Pseudomonas aeruginosa PAO1 as a control. The properties of CF isolates were examined specifically to see if they have a common phenotype. The immunostimulatory properties of S. maltophilia were studied in vitro by stimulating airway epithelial and macrophage cell lines. A neonatal mouse model of pneumonia was used to determine the rates of pneumonia, bacteremia, and mortality, as well as the inflammatory response elicited by S. maltophilia infection. Respiratory and nonrespiratory S. maltophilia isolates were highly immunostimulatory and elicited significant interleukin-8 expression by airway epithelial cells, as well as tumor necrosis factor alpha (TNF-alpha) expression by macrophages. TNF-alpha signaling appears to be important in the pathogenesis of S. maltophilia infection as less than 20% of TNFR1 null mice (compared with 100% of wild-type mice) developed pneumonia and bacteremia following intranasal inoculation. The S. maltophilia isolates were weakly invasive, and low-level bacteremia with no mortality was observed. Despite the lack of invasiveness of S. maltophilia, the immunostimulatory properties of this organism and its induction of TNF-alpha expression specifically indicate that it is likely to contribute significantly to airway inflammation.

Topics: Animals; Bacteremia; Cell Line; Cystic Fibrosis; Epithelial Cells; Gram-Negative Bacterial Infections; Humans; Interleukin-8; Lipid A; Macrophages; Mice; Mice, Inbred C57BL; Mice, Transgenic; Phagocytosis; Pneumonia, Bacterial; Pseudomonas aeruginosa; Receptors, Tumor Necrosis Factor, Type I; Respiratory Mucosa; Respiratory Tract Infections; Stenotrophomonas maltophilia; Tumor Necrosis Factor-alpha

Three structural features of lipid A (addition of palmitate [C16 fatty acid], addition of aminoarabinose [positively charged amino sugar residue], and retention of 3-hydroxydecanoate [3-OH C10 fatty acid]) were determined for Pseudomonas aeruginosa isolates from patients with cystic fibrosis (CF; n=86), from the environment (n=13), and from patients with other conditions (n=14). Among P. aeruginosa CF isolates, 100% had lipid A with palmitate, 24.6% with aminoarabinose, and 33.3% retained 3-hydroxydecanoate. None of the isolates from the environment or from patients with other conditions displayed these modifications. These results indicate that unique lipid A modifications occur in clinical P. aeruginosa CF isolates.

Topics: Arabinose; Child; Child, Preschool; Chronic Disease; Cystic Fibrosis; Decanoic Acids; Humans; Infant; Lipid A; Lung Diseases; Palmitates; Prevalence; Pseudomonas aeruginosa; Pseudomonas Infections

Lipopolysaccharide (LPS) is the major surface component of gram-negative bacteria, and a component of LPS, lipid A, is recognized by the innate immune system through the Toll-like receptor 4/MD-2 complex. Pseudomonas aeruginosa, an environmental gram-negative bacterium that opportunistically infects the respiratory tracts of patients with cystic fibrosis (CF), can synthesize various structures of lipid A. Lipid A from P. aeruginosa strains isolated from infants with CF has a specific structure that includes the removal of the 3 position 3-OH C10 fatty acid. Here we demonstrate increased expression of the P. aeruginosa lipid A 3-O-deacylase (PagL) in isolates from CF infants compared to that in environmental isolates. PagL activity was increased in environmental isolates by growth in medium limited for magnesium and decreased by growth at low temperature in laboratory-adapted strains of P. aeruginosa. P. aeruginosa PagL was shown to be an outer membrane protein by isopycnic density gradient centrifugation. Heterologous expression of P. aeruginosa pagL in Salmonella enterica serovar Typhimurium and Escherichia coli resulted in removal of the 3-OH C14 fatty acid from lipid A, indicating that P. aeruginosa PagL recognizes either 3-OH C10 or 3-OH C14. Finally, deacylated lipid A species were not observed in some clinical P. aeruginosa isolates from patients with severe pulmonary disease, suggesting that loss of PagL function can occur during long-term adaptation to the CF airway.

Topics: Acylation; Bacterial Proteins; Carboxylic Ester Hydrolases; Child; Cystic Fibrosis; Gene Expression Regulation, Bacterial; Histidine; Humans; Lipid A; Magnesium; Pseudomonas aeruginosa; Respiratory System; Temperature

Organisms from the Burkholderia cepacia complex are important pathogens in cystic fibrosis and are associated with increased rates of sepsis and death. These organisms comprise nine closely related species known as genomovars. B. cenocepacia (genomovar III) is the most prevalent and appears the most virulent. We investigated the biological activity of a reference panel of strains using whole-cell lysates to induce septic-shock related cytokines from differentiated human monocytic cells. We found varying biological activity within and between genomovars, with B. cenocepacia strains possessing the greatest cytokine induction activity. This activity was CD-14 dependent, suggesting that LPS was responsible for the cytokine induction. Cytokine induction was not simply related to the expression of rough or smooth LPS. We purified LPS from two strains, B. cenocepacia LMG 12614 and B. multivorans LMG 14273, each possessing rough LPS. Divergence in biological activity of the two genomovars was preserved when human monocytic cells were stimulated with purified LPS. Lipid A purified from LMG 14273 and LMG 12614 were analyzed by matrix-assisted laser desorption ionization/time of flight mass spectrometry. Lipid A from the less effective cytokine inducer LMG 14273 was found to be missing a beta-hydroxymyristate (3-OH C14:0) relative to the lipid A of B. cenocepacia LMG 12614.

Topics: Burkholderia cepacia complex; Cell Line; Cystic Fibrosis; Cytokines; Electrophoresis, Polyacrylamide Gel; Humans; Inflammation; Lipid A; Lipopolysaccharides; U937 Cells

Lipid A is the pro-inflammatory component of bacterial lipopolysaccharide, the major surface component of Gram-negative bacteria. Gram-negative bacteria alter the structure of lipid A in response to specific environmental conditions including those found upon colonization of a host. The opportunistic pathogen Pseudomonas aeruginosa synthesizes a unique hexa-acylated lipid A containing palmitate and aminoarabinose during adaptation to the cystic fibrosis airway. Different lipid A species are observed in P. aeruginosa isolated from non-cystic fibrosis associated infections. Here we report that P. aeruginosa isolates from the airway of a cystic fibrosis patient with severe pulmonary disease synthesized a novel hepta-acylated lipid A. Cystic fibrosis-specific P. aeruginosa lipid A modifications result in resistance to host antimicrobial peptides and increased recognition by human Toll-like receptor 4 (TLR4). Using P. aeruginosa lipid A with different levels of acylation, we identified a 222 amino acid region in the extracellular portion of human TLR4 that is required for the differential recognition of cystic fibrosis-specific lipid A. P. aeruginosa adaptation to the human airway may, therefore, play a fundamental role in the progressive lung damage associated with cystic fibrosis.

Topics: Amino Acid Sequence; Cell Line; Cystic Fibrosis; Genetic Variation; Humans; Kidney; Lipid A; Lipopolysaccharides; Mass Spectrometry; Membrane Glycoproteins; Molecular Weight; Pseudomonas aeruginosa; Receptors, Cell Surface; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Toll-Like Receptor 4; Toll-Like Receptors; Transfection

Cystic fibrosis (CF) patients develop chronic airway infections with Pseudomonas aeruginosa (PA). Pseudomonas aeruginosa synthesized lipopolysaccharide (LPS) with a variety of penta- and hexa-acylated lipid A structures under different environmental conditions. CF patient PA synthesized LPS with specific lipid A structures indicating unique recognition of the CF airway environment. CF-specific lipid A forms containing palmitate and aminoarabinose were associated with resistance to cationic antimicrobial peptides and increased inflammatory responses, indicating that they are likely to be involved in airway disease.

Topics: Acylation; Antimicrobial Cationic Peptides; Arabinose; Bacterial Proteins; Cells, Cultured; Cystic Fibrosis; Drug Resistance, Microbial; Humans; Infant; Interleukin-8; Lipid A; Lipopolysaccharides; Magnesium; Mutation; Palmitates; Peptides; Polymyxins; Pseudomonas aeruginosa; Pseudomonas Infections; Respiratory System; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Virulence

Enzyme-linked immunosorbent assays were developed separately for the three main parts of the Pseudomonas aeruginosa lipopolysaccharide (LPS) molecule, namely, lipid A, core, and O polysaccharide. Anti-lipid A, anticore, and anti-O polysaccharide antibodies were measured in serum samples from 12 patients with cystic fibrosis (CF) in a longitudinal study covering the period before P. aeruginosa infection was established through at least 5 years of chronic infection. The serum antibody response to all parts of the P. aeruginosa LPS molecule increased during the course of chronic infection. The increase in anti-lipid A antibodies was specific for P. aeruginosa lipid A, since no increase in anti-Escherichia coli lipid A antibodies was seen. Immunoglobulin G, A, and M (IgG, IgA and IgM) antibodies were all involved in the specific systemic response to P. aeruginosa lipid A, core, and the O polysaccharides. IgG and IgA levels in particular increased during the course of infection and were significantly higher than the antibody increase seen with age in a healthy control group. The local immune response in the lungs was investigated by measuring IgG, IgA, and IgM antibodies to the separate parts of the P. aeruginosa LPS molecule in sputum samples from 18 CF patients with at least a 5-year history of chronic P. aeruginosa infection. Antibodies detected in sputum were mainly anti-lipid A and anti-O polysaccharide antibodies of the IgG and IgA isotypes. Very high IgA anti-lipid A titers were detected in sputum samples from some CF patients.

Topics: Adolescent; Adult; Antibodies, Bacterial; Child; Child, Preschool; Cystic Fibrosis; Endotoxins; Female; Humans; Immunoglobulin A; Immunoglobulin G; Immunoglobulin M; Infant; Lipid A; Lipopolysaccharides; Male; O Antigens; Polysaccharides, Bacterial; Pseudomonas aeruginosa; Sensitivity and Specificity; Sputum

IgM antibodies to monophosphoryl-lipid A were found to be elevated in sera from children with all forms of juvenile arthritis (JA) and systemic lupus erythematosus. Of more interest, in patients with pauciarticular JA, IgG antibody titers to monophosphoryl-lipid A were found to be correlated with the C3a concentration and the C3d:C3 ratio. Although the full specificity of these antibodies is unknown, they are the first that have been found to be correlated with complement activation products in any form of JA.

Topics: Arthritis, Juvenile; Autoantibodies; Child; Complement Activation; Complement C3; Complement C4; Cystic Fibrosis; Enzyme-Linked Immunosorbent Assay; Humans; Immunoglobulin G; Immunoglobulin M; Lipid A; Lupus Erythematosus, Systemic; Rheumatoid Factor