scholarly journals Role of Complement in Defense of the Middle Ear Revealed by Restoring the Virulence of Nontypeable Haemophilus influenzae siaB Mutants

2006 ◽  
Vol 75 (1) ◽  
pp. 325-333 ◽  
Author(s):  
Marisol A. Figueira ◽  
Sanjay Ram ◽  
Richard Goldstein ◽  
Derek W. Hood ◽  
E. Richard Moxon ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Otitis Media ◽  
Resistant Strain ◽  
Alternative Pathway ◽  
Factor H ◽  
Sensitive Strain ◽  
Surface Proteins ◽  
Wild Type ◽  
Nontypeable Haemophilus Influenzae ◽  
Type Strains

ABSTRACT Nontypeable (NT) Haemophilus influenzae is an important cause of otitis media in children. We have shown previously that NT H. influenzae mutants defective in their ability to sialylate lipopolysaccharide (LPS), called siaB mutants, show attenuated virulence in a chinchilla model of experimental otitis media (EOM). We show that complement is a key arm of host innate immunity against NT H. influenzae-induced EOM. Depleting complement in chinchillas by use of cobra venom factor (CoVF) rendered two otherwise avirulent siaB mutants fully virulent and able to cause EOM with severity similar to that of wild-type strains. Clearance of infection caused by siaB mutants in CoVF-treated animals coincided with reappearance of C3. Wild-type strains were more resistant to direct complement-mediated killing than their siaB mutants. The serum-resistant strain bound less C3 and C4 than the serum-sensitive strain. Neither NT H. influenzae strain tested bound factor H (alternative complement pathway regulator). Selective activation of the alternative pathway resulted in more C3 binding to siaB mutants. LPS sialylation had a more profound impact on the amount of alternative-pathway-mediated C3 binding (∼5-fold decrease in fluorescence) when LPS was the main C3 target, as occurred on the more serum-resistant strain. In contrast, only an ∼1.5-fold decrease in fluorescence intensity of C3 binding was seen with the serum-sensitive strain, where surface proteins predominantly bound C3. Differences in binding sites for C3 and C4 may account for variations in serum resistance between NT H. influenzae strains, which in turn may impact their virulence. These data demonstrate a central role for complement in innate immune defenses against NT H. influenzae infections and specifically EOM.

scholarly journals Borrelia burgdorferi Binding of Host Complement Regulator Factor H Is Not Required for Efficient Mammalian Infection

2007 ◽  
Vol 75 (6) ◽  
pp. 3131-3139 ◽  
Author(s):  
Michael E. Woodman ◽  
Anne E. Cooley ◽  
Jennifer C. Miller ◽  
John J. Lazarus ◽  
Kathryn Tucker ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Alternative Pathway ◽  
Host Factor ◽  
Factor H ◽  
Surface Proteins ◽  
Wild Type ◽  
Factor B ◽  
Mammalian Infection ◽  
Deficient Mice

ABSTRACT The causative agent of Lyme disease, Borrelia burgdorferi, is naturally resistant to its host's alternative pathway of complement-mediated killing. Several different borrelial outer surface proteins have been identified as being able to bind host factor H, a regulator of the alternative pathway, leading to a hypothesis that such binding is important for borrelial resistance to complement. To test this hypothesis, the development of B. burgdorferi infection was compared between factor H-deficient and wild-type mice. Factor B- and C3-deficient mice were also studied to determine the relative roles of the alternative and classical/lectin pathways in B. burgdorferi survival during mammalian infection. While it was predicted that B. burgdorferi should be impaired in its ability to infect factor H-deficient animals, quantitative analyses of bacterial loads indicated that those mice were infected at levels similar to those of wild-type and factor B- and C3-deficient mice. Ticks fed on infected factor H-deficient or wild-type mice all acquired similar numbers of bacteria. Indirect immunofluorescence analysis of B. burgdorferi acquired by feeding ticks from the blood of infected mice indicated that none of the bacteria had detectable levels of factor H on their outer surfaces, even though such bacteria express high levels of surface proteins capable of binding factor H. These findings demonstrate that the acquisition of host factor H is not essential for mammalian infection by B. burgdorferi and indicate that additional mechanisms are employed by the Lyme disease spirochete to evade complement-mediated killing.

scholarly journals Biofilm Biology and Vaccine Strategies for Otitis Media Due to Nontypeable Haemophilus influenzae

2018 ◽  
Vol 14 (02) ◽  
pp. 069-078 ◽  
Author(s):  
Laura Novotny ◽  
Kenneth Brockman ◽  
Elaine Mokrzan ◽  
Joseph Jurcisek ◽  
Lauren Bakaletz
Keyword(s):  
Haemophilus Influenzae ◽  
Otitis Media ◽  
Middle Ear ◽  
Causative Agent ◽  
Upper Respiratory Tract ◽  
Nontypeable Haemophilus Influenzae ◽  
Physical Defenses ◽  
Upper Respiratory ◽  
Recurrent Nature ◽  
Gain Access

AbstractOtitis media (OM) is one of the most common diseases of childhood, and nontypeable Haemophilus influenzae (NTHI) is the predominant causative agent of chronic and recurrent OM, as well as OM for which treatment has failed. Moreover, NTHI is now as important a causative agent of acute OM as the pneumococcus. NTHI colonizes the human nasopharynx asymptomatically. However, upon perturbation of the innate and physical defenses of the airway by upper respiratory tract viral infection, NTHI can replicate, ascend the Eustachian tube, gain access to the normally sterile middle ear space, and cause disease. Bacterial biofilms within the middle ear, including those formed by NTHI, contribute to the chronic and recurrent nature of this disease. These multicomponent structures are highly resistant to clearance by host defenses and elimination by traditional antimicrobial therapies. Herein, we review several strategies utilized by NTHI to persist within the human host and interventions currently under investigation to prevent and/or resolve NTHI-induced diseases of the middle ear and uppermost airway.

scholarly journals LuxS Promotes Biofilm Maturation and Persistence of Nontypeable Haemophilus influenzae In Vivo via Modulation of Lipooligosaccharides on the Bacterial Surface

2009 ◽  
Vol 77 (9) ◽  
pp. 4081-4091 ◽  
Author(s):  
Chelsie E. Armbruster ◽  
Wenzhou Hong ◽  
Bing Pang ◽  
Kristin E. Dew ◽  
Richard A. Juneau ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Otitis Media ◽  
Opportunistic Infections ◽  
Bacterial Species ◽  
Enzyme Linked Immunosorbent Assay ◽  
Nontypeable Haemophilus Influenzae ◽  
Bacterial Persistence ◽  
Soluble Mediator

ABSTRACT Nontypeable Haemophilus influenzae (NTHI) is an extremely common airway commensal which can cause opportunistic infections that are usually localized to airway mucosal surfaces. During many of these infections, NTHI forms biofilm communities that promote persistence in vivo. For many bacterial species, density-dependent quorum-signaling networks can affect biofilm formation and/or maturation. Mutation of luxS, a determinant of the autoinducer 2 (AI-2) quorum signal pathway, increases NTHI virulence in the chinchilla model for otitis media infections. For example, bacterial counts in middle-ear fluids and the severity of the host inflammatory response were increased in luxS mutants compared with parental strains. As these phenotypes are consistent with those that we have observed for biofilm-defective NTHI mutants, we hypothesized that luxS may affect NTHI biofilms. A luxS mutant was generated using the well-characterized NTHI 86-028NP strain and tested to determine the effects of the mutation on biofilm phenotypes in vitro and bacterial persistence and disease severity during experimental otitis media. Quantitation of the biofilm structure by confocal microscopy and COMSTAT analysis revealed significantly reduced biomass for NTHI 86-028NP luxS biofilms, which was restored by a soluble mediator in NTHI 86-028NP supernatants. Analysis of lipooligosaccharide moieties using an enzyme-linked immunosorbent assay and immunoblotting showed decreased levels of biofilm-associated glycoforms in the NTHI 86-028NP luxS strain. Infection studies showed that NTHI 86-028NP luxS had a significant persistence defect in vivo during chronic otitis media infection. Based on these data, we concluded that a luxS-dependent soluble mediator modulates the composition of the NTHI lipooligosaccharides, resulting in effects on biofilm maturation and bacterial persistence in vivo.

Animal Model of Acute Otitis Media Consequent to Beta-Lactamase-Producing Nontypeable Haemophilus Influenzae

1983 ◽  
Vol 92 (6_suppl) ◽  
pp. 29-29
Author(s):  
W. J. Doyle ◽  
J. S. Supance ◽  
G. Marshak ◽  
E. I. Cantekin ◽  
C. D. Bluestone
Keyword(s):  
Animal Model ◽  
Haemophilus Influenzae ◽  
Otitis Media ◽  
Acute Otitis Media ◽  
Beta Lactamase ◽  
Nontypeable Haemophilus Influenzae

Components of the Alternative Pathway of Complement in Otitis Media with Effusion

1985 ◽  
Vol 93 (5) ◽  
pp. 607-611 ◽  
Author(s):  
Michael J. Parker ◽  
Donald A. Leopold ◽  
Ann E. Stitzel ◽  
Thomas R. Welch ◽  
Leonard B. Weiner ◽  
...  
Keyword(s):  
Otitis Media ◽  
Clinical Course ◽  
Otitis Media With Effusion ◽  
Past History ◽  
Alternative Pathway ◽  
Factor H ◽  
Complement Components ◽  
Bacterial Cultures ◽  
Middle Ear Fluid ◽  
Alternative Pathway Of Complement

An evaluation of the alternative pathway of complement was undertaken in patients with otitis media with effusion (OME). Middle ear fluid (MEF) and serum specimens were obtained from 34 patients at the time of elective myringotomy for OME. Bacterial, viral, and mycoplasma cultures were made for all specimens of the fluids. Immunochemical determinations by radial immunodiffusion were performed for C3, C5, factor B, properdin, factor H, factor I, and albumin. Each patient's recent clinical course and past history were reviewed. The results of all viral and mycoplasma cultures were negative. Three of 55 bacterial cultures were positive for type B Haemophilus Influenzae. All components of the alternative pathway measured were found to be present in varying amounts in MEF. When the levels of the complement components were compared to the clinical factors studied, there were no observable differences. These data suggest that components of the alternative pathway Of complement are present in OME and are not useful in predicting the clinical course or outcome of this disorder.

scholarly journals Tympanic membrane changes in experimental acute otitis media and myringotomy

Medicina ◽  
2008 ◽  
Vol 44 (4) ◽  
pp. 313 ◽  
Author(s):  
Giedrė Alzbutienė ◽  
Ann Hermansson ◽  
Per Cayè-Thomasen ◽  
Vytenis Kinduris
Keyword(s):  
Calcium Phosphate ◽  
Haemophilus Influenzae ◽  
Tympanic Membrane ◽  
Otitis Media ◽  
Acute Otitis Media ◽  
Polymorphonuclear Neutrophil ◽  
Sprague Dawley ◽  
Nontypeable Haemophilus Influenzae ◽  
Temporal Bones ◽  
Tympanic Membranes

Objective. The present experimental study explored pathomorphological changes and calcium depositions in the tympanic membrane during experimental acute otitis media caused by nontypeable Haemophilus influenzae in myringotomized and nonmyringotomized ears. Material and methods. A rat model of experimental acute otitis media caused by nontypeable Haemophilus influenzae was employed. Sixteen Sprague-Dawley rats were used. Four days following middle ear inoculation, a bilateral myringotomy was performed in six randomly selected animals. Another group of 10 animals was inoculated only. On days 4, 7, 14, and 28 after inoculation, two animals from each group were sacrificed. The temporal bones were removed and the tympanic membranes were dissected, followed by paraffin embedding. Adjacent sections were stained with PAS-alcian blue for basic histopathological observations and by von Kossa method for determination of calcium phosphate depositions. Results. Particularly intense invasion of polymorphonuclear neutrophil leukocytes was seen on day 4 after inoculation. The highest infiltration of macrophages was observed on day 7. The peak number of lymphocytes was seen on day 14. No difference occurred in the number of polymorphonuclear leukocytes in myringotomized and nonmyringotomized tympanic membranes. The infiltration with lymphocytes and activated macrophages in all parts of the myringotomized tympanic membranes was statistically significantly higher than in the nonmyringotomized animals. The total amount of interstitial calcium phosphate depositions during days 7, 14, and 28 of study was statistically higher in the sections of pars tensa from myringotomized membranes compared to the nonmyringotomized membranes. Conclusion. Nontypeable Haemophilus influenzae-induced acute otitis media and myringotomy provoke more extensive inflammatory reaction with microcalcification in the tympanic membranes.

scholarly journals Role of the Nuclease of Nontypeable Haemophilus influenzae in Dispersal of Organisms from Biofilms

2014 ◽  
Vol 83 (3) ◽  
pp. 950-957 ◽  
Author(s):  
Christine Cho ◽  
Aroon Chande ◽  
Lokesh Gakhar ◽  
Lauren O. Bakaletz ◽  
Joseph A. Jurcisek ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Microscopic Analysis ◽  
Human Infection ◽  
Extracellular Dna ◽  
Wild Type ◽  
Nontypeable Haemophilus Influenzae ◽  
Dispersal Pattern ◽  
Content Type ◽  
Biofilm Dispersal

NontypeableHaemophilus influenzae(NTHI) forms biofilms in the middle ear during human infection. The biofilm matrix of NTHI contains extracellular DNA. We show that NTHI possesses a potent nuclease, which is a homolog of the thermonuclease ofStaphylococcus aureus. Using a biofilm dispersal assay, studies showed a biofilm dispersal pattern in the parent strain, no evidence of dispersal in the nuclease mutant, and a partial return of dispersion in the complemented mutant. Quantitative PCR of mRNA from biofilms from a 24-h continuous flow system demonstrated a significantly increased expression of the nuclease from planktonic organisms compared to those in the biofilm phase of growth (P< 0.042). Microscopic analysis of biofilms grownin vitroshowed that in the nuclease mutant the nucleic acid matrix was increased compared to the wild-type and complemented strains. Organisms were typically found in large aggregates, unlike the wild-type and complement biofilms in which the organisms were evenly dispersed throughout the biofilm. At 48 h, the majority of the organisms in the mutant biofilm were dead. The nuclease mutant formed a biofilm in the chinchilla model of otitis media and demonstrated a propensity to also form similar large aggregates of organisms. These studies indicate that NTHI nuclease is involved in biofilm remodeling and organism dispersal.

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