Characterization of lymphoid cells from the human fallopian tube mucosa.
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Antigens, Differentiation↗
Biomedical subjects
D S Stephens
Publications and source records attributed to D S Stephens.
Cytopathic effects of the pathogenic Neisseria. Studies using human fallopian tube organ cultures and human nasopharyngeal organ cultures.
Infection of mucosal surfaces by N. gonorrhoeae and N. meningitidis may result in inflammation indicating potential injury to host cells. We used human fallopian tube organ cultures (FTOC) and human nasopharyngeal organ cultures (NPOC) to study the mechanisms by which gonococci and meningococci damage human mucosal surfaces. Early in the course of FTOC infected with gonococci and NPOC infected with meningococci, damage was most apparent to ciliary activity. Loss of ciliary activity was accompanied by sloughing of ciliated cells. The damage to ciliated cells was not associated with attachment of gonococci or meningococci to these cells or the presence of organisms within ciliated cells. Infection with the commensal N. subflava did not result in significant damage to human FTOC or NPOC ciliary activity. LPS appears to be a major toxin of gonococci for human FTOC ciliated cells. Gonococcal peptidoglycan fragments also damage FTOC ciliary activity. Both piliated (P+) and nonpiliated (P-) gonococci and meningococci damage FTOC and NPOC ciliary activity, but P+ organisms damage ciliary activity more rapidly than P- organisms. Damage to FTOC ciliated cells was produced by less than 10 micrograms/ml of purified gonococcal and meningococcal LPS. By 1-2h after exposure to LPS, vesicles containing LPS were distributed throughout the cytoplasm of ciliated cells. Polymyxin B neutralized LPS-induced damage, suggesting that the lipid A portion of LPS was the toxic moiety. In contrast, purified gonococcal and meningococcal LPS at 100 micrograms/ml did not damage human NPOC or FTOC from rabbits, pigs and cows. These studies indicate that N. gonorrhoeae and possibly N. meningitidis damage ciliated epithelial cells indirectly by release of toxins from the organisms. The differences in susceptibility of FTOC and NPOC to LPS may suggest changes in density of receptors for LPS and may help explain variation in severity of gonococcal and meningococcal interactions at different human mucosal surfaces.
Cilia↗
Evidence that the serum resistance genetic locus sac-3 of Neisseria gonorrhoeae is involved in lipopolysaccharide structure.
The gonococcal chromosome contains a sequence of closely linked genes (for example, sac-1, sac-3, nmp) known or presumed to affect cell envelope structure and which appear to influence susceptibility of gonococci to killing by normal human sera (NHS). Previous work has shown that the serum-resistant isolate FA19, and FA899, a serum-sensitive transformant of FA19, differ in outer membrane protein I (PI) and at the sac-3 genetic locus. However, the sac-3 locus is separable from changes determined by nmp-3, the gene determining PI species. We found that FA19 and FA899 differ in lipopolysaccharide (LPS) molecular size and in reactivity with a monoclonal antibody which recognizes an LPS (L8) epitope. To address the question of whether the changes in LPS were due to the sac-3 locus, we constructed new transformants of FA19 using donor DNA prepared from FA899. The new transformants could be divided into three groups: (1) those identical to FA19 in serum resistance (greater than 90% survival at 120 min), in LPS molecular size and in expression of the L8 epitope; (2) those identical to FA899 in serum sensitivity (100% killed at 30 min), in LPS molecular size and in lack of expression of the L8 epitope; (3) those significantly killed by 50% NHS at 120 min, whose LPS molecular size was greater than that of FA19 but less than that of FA899 and which did not express the L8 epitope. Except for PI there were no differences in other outer-membrane proteins (e.g. PII, PIII, H.8) among these transformants.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Bactericidal Activity↗
Human adenoid organ culture: a model to study the interaction of influenza A with human nasopharyngeal mucosa.
Previous studies of infections with influenza A in animal models have stressed the tropism of this virus for the upper respiratory tract. To assess the interaction of influenza A virus with human respiratory tissue, we maintained adenoids, consisting of ciliated epithelium with underlying lymphoid follicles, in organ culture. When the organ cultures were inoculated with wild-type influenza A/Alaska (H3N2), epithelial damage and migration of inflammatory cells from the follicles into the lamina propria were seen. Growth of the virus and ciliary damage in infected organ cultures from seronegative donors were significantly greater than that seen in organ cultures from seropositive donors. Adenoidal lymphocytes were then studied to determine which factors might modulate infectivity. Specific in vitro production of antibody to influenza A/Alaska was demonstrated by adenoidal lymphocytes from seropositive donors, whereas lymphocytes from seronegative donors did not produce antibody. The human adenoid organ culture provides an attractive model to study the pathogenesis of influenza A infections and the resultant local immune response.
Antibodies, Viral↗
Pathogenesis of IgA1 protease-producing and -nonproducing Haemophilus influenzae in human nasopharyngeal organ cultures.
We evaluated mucosal attachment, colonization, and invasion by Haemophilus influenzae in an experimental model of human nasopharyngeal tissue in organ culture. Nonpiliated, encapsulated, and nonencapsulated, IgA1 protease-deficient mutants of H. influenzae were compared with their isogenic IgA1 protease-producing parents. Damage to peripheral ciliary activity was first noted 6 hr after infection and was associated with sloughing of ciliated cells to which H. influenzae were not attached. Infection of organ cultures with each strain resulted in similar degrees and rates of ciliary damage. H. influenzae attached selectively to nonciliated epithelial cells or was associated with surface mucus. Later, disruption of epithelial tight junctions was observed, and clusters of H. influenzae were found between epithelial cells. Organisms were also seen within phagocytic vacuoles of mononuclear cells located above and below the basement membrane. In summary, encapsulated and nonencapsulated H. influenzae damaged the ciliary function of human nasopharyngeal organ cultures, attached to the mucosal surface, and invaded the epithelium. H. influenzae IgA1 protease, however, was not essential for the pathogenic steps observed in this human nasopharyngeal organ culture model.
Haemophilus Infections↗
Analysis of damage to human ciliated nasopharyngeal epithelium by Neisseria meningitidis.
We used an in vitro model of human nasopharyngeal tissue in organ culture to evaluate the effects of Neisseria meningitidis on human cilia and ciliary function. Encapsulated, viable meningococci damaged ciliated epithelium of nasopharyngeal organ cultures, whereas Neisseria subflava, a commensal species, did not. Meningococcus-induced ciliary damage was due to loss of ciliated cells to which meningococci were not attached. Damage was seen with piliated and nonpiliated meningococci and did not appear to require the presence of other specific meningococcal surface proteins. Meningococcal viability was a requirement for both ciliary damage and interactions of meningococci with microvilli of nonciliated epithelial cells. That is, filter-sterilized supernatants from meningococcus-infected organ cultures, heat-killed meningococci at high inoculum, and purified meningococcal or gonococcal lipopolysaccharide at concentrations of 100 micrograms/ml did not damage ciliary activity of nasopharyngeal organ cultures. In contrast, meningococcal lipopolysaccharide at 10 micrograms/ml markedly damaged ciliary activity of human fallopian tube organ cultures, suggesting a selective toxicity of lipopolysaccharide for specific human ciliated cells. Damage to nasopharyngeal ciliated epithelium by N. meningitidis may be an important first step in meningococcal colonization of the human nasopharynx, but meningococcal lipopolysaccharide does not appear to be directly responsible for this toxicity.
Bacterial Outer Membrane Proteins↗
Pili of Neisseria meningitidis. Analysis of structure and investigation of structural and antigenic relationships to gonococcal pili.
To provide information useful for the design of a pilus vaccine effective for the prevention of both meningococcal and gonococcal disease, the electron microscopic morphology of meningococcal pili and the structural and antigenic relationships of meningococcal pili to gonococcal pili were investigated. Meningococcal pili were 4-6 nm in width, extended 500-6,000 nm from the organism surface, and occurred singly or in bundles composed of 8-10 pili per bundle. Meningococcal pilin varied between 17,250 and 20,600 daltons. Pilin was present in outer membrane preparations of some meningococcal isolates that were nonpiliated by electron microscopic examination. Antibodies to gonococcal pili, cyanogen bromide cleavage fragments of gonococcal pilin, or synthetic peptide analogues corresponding to regions of the gonococcal pilin sequence, were used to detect common meningococcal and gonococcal antigenic determinants that might indicate the existence of a conserved sequence beyond residue 29. Antibody to intact gonococcal pili or to the variable CNBR-3 region of gonococcal pilin detected little shared antigenicity with meningococcal pilin. However, pilin from all tested meningococcal isolates reacted with antibody to the CNBR-2 fragment of gonococcal pilin, a region highly conserved among gonococcal strains. Meningococcal pilins were also broadly crossreactive with antibody to a synthetic peptide corresponding to residues 69-84 of the gonococcal sequence, a part of the CNBR-2 region that appears to be critical for gonococcal receptor-binding function. If a sequence similar to 69-84 is also important for receptor-binding function in meningococcal pili, a peptide corresponding to this region may elicit antibodies that block the adherence function of pili elaborated by both Neisseria gonorrhoeae and N. meningitidis.
Amino Acid Sequence↗
Multicenter collaborative evaluation of a standardized serum bactericidal test as a prognostic indicator in infective endocarditis.
One hundred twenty-nine patients with bacterial endocarditis were evaluated in a multicenter collaborative study to determine whether a standardized serum bactericidal test could predict the outcome of the infection. All centers used a microdilution test method that defined all known test variables, including inoculum size, culture medium, dilution technique, incubation time, method of subculture, and bactericidal endpoint. Peak serum bactericidal titers of 1:64 or more and trough serum bactericidal titers of 1:32 or more predicted bacteriologic cure in all patients. The traditionally recommended serum bactericidal titer of 1:8 had statistically significant predictive accuracy at trough antibiotic levels only. The serum bactericidal test was a poor predictor of bacteriologic failure and ultimate clinical outcome, which depends on many factors. Wider recognition by physicians and clinical microbiologists that this in vitro test of antimicrobial activity can accurately predict bacteriologic success but cannot accurately predict either bacteriologic failure or clinical outcome could lead to a better consensus about its appropriate use. On the basis of the results of this study, peak serum bactericidal titers of 1:64 or more and trough serum bactericidal titers of 1:32 or more are recommended to provide optimal medical therapy for infective endocarditis.
Adolescent↗
Neisseria meningitidis.
N. meningitidis continues to be a worldwide cause of human disease, usually in otherwise healthy individuals. The natural habitat and reservoir for meningococci are the mucosal surfaces of the human nasopharynx and to a lesser extent, the urogenital tract and anal canal. In most instances meningococcal colonization of mucosal surfaces is asymptomatic but may produce local infection. In those individuals who lack serum bactericidal activity against the meningococcus, colonization of mucosal surfaces and bloodstream invasion by N. meningitidis can lead to devastating meningitis and septicemia. Recent studies on the ultrastructure of the meningococcus and on the mechanisms of pathogenesis have given us new insight into meningococcal infections and suggest ways for improved immunoprophylaxis. Currently, penicillin is the drug of choice for the treatment of meningococcal meningitis and septicemia. However, the report of meningococci with antibiotic resistant plasmids is alarming and in the future may alter traditional treatment regimens.
Cephalosporins↗
Clinical features of mild systemic meningococcal disease with characterization of bacterial isolates.
Neisseria meningitidis is an important cause of fulminant septicemia and meningitis in children. Only limited reports of mild disease associated with this organism exist. In this study, we describe eight children, ages 2.5-19 months, with mild meningococcal disease and characterize the meningococcal isolates from some of these patients. Children with mild meningococcal disease presented with a mean fever of 40.1 degrees C, but without purpura or petechiae. Five were diagnosed as having otitis media and were not thought to be seriously ill when initially observed. Six of the eight children had complete resolution of their clinical symptoms as outpatients. One had apparent meningococcal meningitis that sterilized without antibiotic therapy, and one had persistent low grade bacteremia that cleared within 48 hours after institution of parenteral antibiotics. Characterization of the meningococcal isolates from three of the patients revealed that the organisms were encapsulated, piliated, and contained similar outer membrane proteins. This report confirms that blood stream invasion by N. meningitidis organisms may result in clinically mild disease.
Blood Bactericidal Activity↗
Loss of pili and decreased attachment to human cells by Neisseria meningitidis and Neisseria gonorrhoeae exposed to subinhibitory concentrations of antibiotics.
Recent evidence has suggested that surface structures of pathogenic bacteria, which are important in attachment to human mucosal surfaces, may be absent on bacteria grown in the presence of subinhibitory concentrations of antibiotics. We studied the effect of tetracycline and penicillin on meningococcal and gonococcal pili. Subinhibitory concentrations of tetracycline and penicillin were found to markedly reduce the number of pili per meningococcus or gonococcus and the percentage of meningococci or gonococci with pili, as determined by negative-staining electron microscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane preparations suggested that tetracycline decreased expression of pili by inhibiting synthesis of pilin subunits. In contrast, pilin subunit synthesis was unaltered by penicillin, suggesting a defect in assembly of pilin subunits or in anchoring of assembled pili. The decrease in the number of pili that occurred with subinhibitory concentrations of both tetracycline and penicillin was accompanied by a marked decrease in the ability of the organisms to attach to human cells. Gonococci or meningococci removed from the influence of subinhibitory concentrations of the antibiotics regained piliation, and attachment returned to levels near those of controls. The expression of meningococcal and gonococcal pili may be affected by factors that influence synthesis of pilin subunits or factors that interfere with the assembly and anchoring of pili in the outer membrane.
Adhesiveness↗
Common pathways of invasion of mucosal barriers by Neisseria gonorrhoeae and Neisseria meningitidis.
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Bacterial Capsules↗
Association of virulence of Neisseria meningitidis with transparent colony type and low-molecular-weight outer membrane proteins.
To assess the factors that might be associated with the virulence of Neisseria meningitidis, isolates from the blood or cerebrospinal fluid of patients with meningococcal disease and meningococcal isolates from the nasopharynx of asymptomatic carriers were compared with regard to opacity or transparency of colonies. Neisseria meningitidis isolated from patients with meningitis and septicemia grew in predominantly transparent colonies, whereas meningococci isolated from asymptomatic carriers generally formed opaque or a mixture of opaque and transparent colonies. Piliated meningococci from opaque colonies attached to human mucosal cells in significantly greater numbers than did piliated meningococci from transparent colonies of the same isolate. Meningococci from transparent colonies were more resistant to killing by normal human serum than were meningococci from isogenic opaque colonies. Disease-associated isolates that formed transparent colonies contained one or more heat-modifiable outer membrane proteins of molecular weight 26,000-32,000 which were not found in some isogenic clones that formed opaque colonies. Transparency of meningococcal colonies may be an important marker for factors that mediate meningococcal virulence.
Adhesiveness↗
Interaction of Neisseria meningitidis with human nasopharyngeal mucosa: attachment and entry into columnar epithelial cells.
The mechanisms by which Neisseria meningitidis establishes a carrier state or invades mucosal surfaces of the host to cause septicemia and meningitis are unknown. An experimental model of human columnar nasopharyngeal tissue in organ culture was developed, and the interaction of encapsulated, piliated N meningitidis with this mucosal surface was studied. Electron microscopic studies showed that meningococci attached selectively to nonciliated columnar cells of the nasopharynx. After attachment, the microvilli of these nonciliated cells elongated and surrounded the organisms. Six to twelve hours after infection, endocytic vacuoles containing meningococci were seen in the apical portion of some nonciliated columnar cells. Later, diplococci were seen in the subepithelial tissues adjacent to lymphoid tissue; this observation suggested that meningococci had penetrated the epithelial layer. The interaction of meningococci with the nasopharyngeal epithelium may be an important means whereby these bacteria establish a carrier state or invade the host.
Adhesiveness↗
Attachment of pathogenic Neisseria to human mucosal surfaces: role in pathogenesis.
Studies of the interaction between Neisseria gonorrhoeae and human fallopian tube mucosa in organ culture suggest that attachment of gonococci is important, not only to secure th organism in the host, but also to initiate the disease process. The steps observed in gonococcal infection of fallopian tube organ cultures are: 1) attachment of gonococci to microvilli of nonciliated cells; 2) release from gonococci of lipopolysaccharide and possibly other toxic moities to cause mucosa damage; 3) engulfment or phagocytosis of gonococci by nonciliated cells; 4) transport of phagocytic vacuoles containing gonococci to the base of the nonciliated cells; and 5) exocytosis of gonococci within phagocytic vacuoles into the subepithelial tissues. In vivo, these steps might result in extensive local disease (e.g. salpingitis) or in the invasion of blood vessels to cause disseminated disease. Preliminary studies of human nasopharyngeal tissue in organ culture infected with Neisseria meningitidis indicate that meningococci attach to microvilli of nonciliated cells and are phagocytized by these cells. Meningococci subsequently appear in subepithelial tissues, though the route they take is not yet certain. These observations suggest at least some of the ways in which attachment may play a role in disease caused by N. gonorrhoeae and N. meningitidis. Mechanisms to block this attachment may provide new approaches to the prevention of infections caused by the pathogenic Neisseria.
Epithelium↗
Pili and outer membrane appendages on Neisseria meningitidis in the cerebrospinal fluid of an infant.
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Cell Membrane↗
Attachment of Neisseria meningitidis to human mucosal surfaces: influence of pili and type of receptor cell.
The factors that determine attachment of meningococci predominantly to the mucosa of the nasopharynx rather than to other mucosal surfaces are unknown. Isolates of Neisseria meningitidis from the nasopharynx of carriers and from patients with meningococcal disease were found to be heavily piliated. Isogenic piliated and nonpiliated meningococcal clones were derived from blood and cerebrospinal fluid isolates. Meningococci with pili consistently attached to human nasopharyngeal cells in greater numbers than meningococci without pili. Meningococci treated with trypsin or mechanical shear forces lost pili and exhibited decreased attachment. Attachment of piliated meningococci differed markedly among epithelial cells from different sites. In contrast, nonpiliated meningococci attached equally but in low numbers to all cell types. These data suggest that pili are important mediators of meningococcal attachment. The number and distribution of receptor sites for pili or pili-associated meningococcal ligands differ among human cells and may determine sites of meningococcal colonization.
Epithelium↗
Pseudodiphtheria: prominent pharyngeal membrane associated with fatal paraquat ingestion.
Three patients presented with prominent pharyngeal membranes suggestive of tonsillar-pharyngeal diphtheria, but later found to be caused by oral ingestion of the herbicide paraquat. In all cases appropriate therapy was delayed because of failure to include paraquat in the differential diagnosis: Paraquat ingestion should be considered in all patients with prominent tongue and pharyngeal membranes.
Adult↗