Human milk secretory IgA antibody to nontypeable Haemophilus influenzae: possible protective effects against nasopharyngeal colonization

Induction of Mucosal IgA-Mediated Protective Immunity Against Nontypeable Haemophilus influenzae Infection by a Cationic Nanogel-Based P6 Nasal Vaccine

Nontypeable Haemophilus influenzae (NTHi) strains form a major group of pathogenic bacteria that colonizes the nasopharynx and causes otitis media in young children. At present, there is no licensed vaccine for NTHi. Because NTHi colonizes the upper respiratory tract and forms biofilms that cause subsequent infectious events, a nasal vaccine that induces NTHi-specific secretory IgA capable of preventing biofilm formation in the respiratory tract is desirable. Here, we developed a cationic cholesteryl pullulan–based (cCHP nanogel) nasal vaccine containing the NTHi surface antigen P6 (cCHP-P6) as a universal vaccine antigen, because P6 expression is conserved among 90% of NTHi strains. Nasal immunization of mice with cCHP-P6 effectively induced P6-specific IgA in mucosal fluids, including nasal and middle ear washes. The vaccine-induced P6-specific IgA showed direct binding to the NTHi via the surface P6 proteins, resulting in the inhibition of NTHi biofilm formation. cCHP-P6 nasal vaccine thus protected mice from intranasal NTHi challenge by reducing NTHi colonization of nasal tissues and eventually eliminated the bacteria. In addition, the vaccine-induced IgA bound to different NTHi clinical isolates from patients with otitis media and inhibited NTHi attachment in a three-dimensional in vitro model of the human nasal epithelial surface. Therefore, the cCHP-P6 nanogel nasal vaccine induced effective protection in the airway mucosa, making it a strong vaccine candidate for preventing NTHi-induced infectious diseases, such as otitis media, sinusitis, and pneumonia.

Serotype Distribution of Streptococcus pneumoniae Carriage in Six-Month-Old Infants: A Cross-sectional Study During 2017-18, Tehran, Iran

Background: Streptococcus pneumoniae is recognized as one of the main pathogens inducing several invasive and non-invasive infections in children. Objective: The present study aimed to evaluate the serotype distribution of S. pneumoniae in six–month–old carriers. Methods: This study encompassed 600 six-month-old healthy infants whose pharyngeal swap samples were collected and then cultured to isolate S. pneumoniae. Twenty- five different serotypes were defined on positive culture samples by multiplex PCR. Results: In this study, 13 cases (2.2%) were positive S. pneumonia. The most common isolated serotypes of S. pneumoniae were serotypes 23F (n = 6, 1%) and 3 (n = 3, 0.5%), respectively. Notably, the most frequent serotype in formula-fed infants (n = 300) was Serotype 23F (n = 5, 1.7%); however, Serotype 3 (n = 3, 1%) was the most frequent one in breastfed participants (n = 300). According to the findings, the overall coverage of PCV10, PCV13, and PPSV23 on the S. pneumoniae serotypes at the age of six months was 50%, 73%, and 85%, respectively. Conclusions: At this age, the type of feeding could not significantly affect the frequency rate of S. pneumoniae colonization, while the serotype distributions in the two breastfed and formula-fed groups were different.

The aetiology of diarrhoea, pneumonia and respiratory colonization of HIV-exposed infants randomized to breast- or formula-feeding

BACKGROUND

Diarrhoea and pneumonia are common causes of childhood death in sub-Saharan Africa but there are few studies describing specific pathogens.

OBJECTIVES

The study aimed to describe the pathogens associated with diarrhoea, pneumonia and oropharyngeal colonization in children born to HIV-infected women (HIV-exposed infants).

METHODS

The Mashi Study randomized 1200 HIV-infected women and their infants to breastfeed for 6 months with ZDV prophylaxis or formula-feed with 4 weeks of ZDV. Children were tested for HIV by PCR at 1, 4, 7, 9 and 12 months and by ELISA at 18 months. Pre-defined subsets of children were sampled during episodes of diarrhoea (n = 300) and pneumonia (n = 85). Stool was tested for bacterial pathogens, rotavirus and parasites. Children with pneumonia underwent bacterial blood culture, and testing of nasopharyngeal aspirates for viral pathogens by PCR. Oropharyngeal swabs were collected from a consecutive subset of 561 infants at the routine 3-month visit for bacterial culture.

RESULTS

The median age (range) at sampling was 181 days for diarrhoea (0-730) and 140 days for pneumonia (2-551). Pathogens were identified in 55 (18%) children with diarrhoea and 32 (38%) with pneumonia. No differences in pathogens by child HIV status (HIV-infected vs HIV-uninfected) or feeding strategy were identified. Campylobacter was the most common diarrhoeal pathogen (7%). Adenovirus (22%) and other viruses (19%) were the primary pathogens isolated during pneumonias. More formula-fed infants had oropharyngeal colonization by pathogenic Gram-negative bacteria (16.8% vs 6.2%, P = 0.003), which was associated with a non-significant increased risk of pneumonia (OR 2.2, 95% CI 0.8-5.7).

CONCLUSION

A trend toward oropharyngeal bacterial colonization was observed in formula-fed infants. Although viruses were most commonly detected during pneumonia, respiratory colonization by Gram-negative bacteria may have contributed to pneumonia in formula-fed infants.

Infant Health of Mothers with Multiple Sclerosis

Controversy surrounds whether mothers with multiple sclerosis (MS) who wish to breast-feed their infants should forgo breast-feeding in order to resume immunomodulating therapy following birth even though breast-feeding has not been shown to have deleterious effects on these mothers. Knowledge of potential health benefits to infants through breast-feeding could influence health care providers to encourage mothers with MS who wish to breast-feed to do so. This study of 140 breast-feeding and 35 non-breast-feeding mothers with MS identifies the type and prevalence of illnesses experienced by their infants during the first 6 postpartum months and at 9 months and 12 months. Significantly more non-breast-fed than breast-fed infants experienced otitis media, lower respiratory illness, constipation, milk intolerance, and allergy during the 1st year. Study results support the need to encourage mothers with MS who wish to breast-feed their infants to do so and to delay immunomodulating therapy until breast-feeding cessation.

Developing a vaccine to prevent otitis media caused by nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is a predominant organism of the upper respiratory nasopharyngeal microbiota. Its disease spectrum includes otitis media, sinusitis, non-bacteremic pneumonia and invasive infections. Protein-based vaccines to prevent NTHi infections are needed to alleviate these infections in children and vulnerable populations such as the elderly and those with chronic obstructive pulmonary disease (COPD). One NTHi protein is included in a pneumococcal conjugate vaccine and has been shown to provide efficacy. Our lab has been interested in understanding the immunogenicity of NTHi vaccine candidates P6, protein D and OMP26 for preventing acute otitis media in young children. We expect that continued investigation and progress in the development of an efficacious protein based vaccine against NTHi infections is achievable in the near future.

The Mammary Gland in Mucosal and Regional Immunity

The mammary gland (MG) lacks a mucosa but is part of the mucosal immune system because of its role in passive mucosal immunity. The MG is not an inductive site for mucosal immunity. Rather, synthesis of immunoglobulin (Ig)A by plasma cells stimulated at distal inductive sites dominate in the milk of rodents, humans, and swine whereas IgG1 derived from serum predominates in ruminants. Despite the considerable biodiversity in the role of the MG, IgG passively transfers the maternal systemic immunological experience whereas IgA transfers the mucosal immunological experience. Although passive antibodies are protective, they and other lacteal constituents can be immunoregulatory. Immune protection of the MG largely depends on the innate immune system; the monocytes–macrophages group together with intraepithelial lymphocytes is dominant in the healthy gland. An increase in somatic cells (neutrophils) and various interleukins signal infection (mastitis) and a local immune response in the MG. The major role of the MG to mucosal immunity is the passive immunity supplied to the suckling neonate.

Human milk glycoproteins protect infants against human pathogens

Breastfeeding protects the neonate against pathogen infection. Major mechanisms of protection include human milk glycoconjugates functioning as soluble receptor mimetics that inhibit pathogen binding to the mucosal cell surface, prebiotic stimulation of gut colonization by favorable microbiota, immunomodulation, and as a substrate for bacterial fermentation products in the gut. Human milk proteins are predominantly glycosylated, and some biological functions of these human milk glycoproteins (HMGPs) have been reported. HMGPs range in size from 14 kDa to 2,000 kDa and include mucins, secretory immunoglobulin A, bile salt-stimulated lipase, lactoferrin, butyrophilin, lactadherin, leptin, and adiponectin. This review summarizes known biological roles of HMGPs that may contribute to the ability of human milk to protect neonates from disease.

Bactericidal antibody response against P6, protein D, and OMP26 of nontypeable Haemophilus influenzae after acute otitis media in otitis-prone children

The bactericidal antibody response to three nontypeable Haemophilus influenzae (NTHi) outer membrane proteins (D, P6, and OMP26) was studied in 24 otitis-prone children (aged 7-28 months) after an acute otitis media (AOM) caused by NTHi. The study was carried out to understand the contribution of antigen-specific bactericidal antibody responses in the class of children who are most vulnerable to recurrent otitis media infections. Levels of protein D (P = 0.005) and P6 (P = 0.026) but not OMP26 antibodies were higher in bactericidal sera compared with nonbactericidal sera. For five (24%) and 16 (76%) of 21 bactericidal sera tested, removal of anti-protein D and P6 antibody, respectively, resulted in a two- to fourfold drop in bactericidal antibody. Antibodies to OMP26 did not make any contribution to the overall bactericidal activity in any serum samples. Eleven of 21 sera (52%) had bactericidal activity against a heterologous NTHi (86-028 NP) strain but the titers were significantly lower (P < 0.05) as compared to the homologous strains. Future studies of protein D, P6, OMP26, and other potential NTHi vaccine antigens should include studies of bactericidal antibody in children who are otitis prone as a possible correlate of protection.

Breast-feeding is associated with a reduced frequency of acute otitis media and high serum antibody levels against NTHi and outer membrane protein vaccine antigen candidate P6

Nontypeable Haemophilus influenzae (NTHi) causes acute otitis media (AOM) in infants. Breast-feeding protects against AOM and/or nasopharyngeal (NP) colonization; however, the mechanism of protection is incompletely understood. Children with AOM and healthy children were studied according to feeding status: breastfed,breast/formula fed, or formula fed. Cumulative episodes of AOM, ELISA titers of serum IgG antibodies to whole-cell NTHi and vaccine candidate outer membrane protein P6, bactericidal titers of serum and NP colonization by NTHi were assessed. A lower incidence of AOM was found in breast- versus formula-fed children. Levels of specific serum IgG antibody to NTHi and P6 were highest in breast-fed, intermediate in breast/formula fed, and lowest in formula-fed infants. Serum IgG antibody to P6 correlated with bactericidal activity against NTHi. Among children with AOM, the prevalence of NTHi in the NP was lower in breast- versus nonbreast-fed infants. We conclude that breast-feeding shows an association with higher levels of antibodies to NTHi and P6, suggesting that breast-feeding modulates the serum immune response to NTHi and P6. Higher serum IgG might facilitate protection against AOM and NP colonization in breast-fed children.

Resistance of nasopharyngeal pathogens and antimicrobial prescription rates for children in an area under controlled antimicrobial use

BACKGROUND

To reduce the spread of drug-resistant pathogens, appropriate use of antimicrobials is an indispensable measure. From January 2002, we undertook campaigns about antimicrobial treatment in Sado Island, Japan.

METHODS

The subjects were born in 1996 (group-1996) or during 2002-2004 (group-2002-2004) and received outpatient treatment at our hospital. We evaluated the subjects' medical information from patient records during their first 3 years of life. Demographic data, duration of breast-feeding, and attending a day-care center (DCC) were evaluated using a questionnaire.

RESULTS

Average visit-based antimicrobial prescription rates significantly decreased from 535 for group-1996, to 70 for group-2002-2004 per 1000 hospital visits (P < 0.001). The rate of cephalosporin prescriptions significantly decreased (77.1%-16.7%; P < 0.001), while amoxicillin (0.8%-29.5%) and macrolides (21.0%-52.4%) significantly increased (P < 0.001). Regarding 417 nasopharyngeal cultures from group-2002-2004, 77.8% (179/230) of Streptococcus pneumoniae strains were nonsusceptible to penicillin. For Haemophilus influenzae strains, 30.6% (59/193) were nonsusceptible to ampicillin. Living with older sibling(s) and early DCC attendance were associated with carriage of resistant pathogens.

CONCLUSIONS

In a closed area under controlled antimicrobial use, our data indicated that decreasing antimicrobial prescriptions alone could not achieve elimination of resistant pathogens. Strategies to control transmission at DCCs or from older sibling(s) are also essential.

Mucosal immunization of mice with recombinant OMP P2 induces antibodies that bind to surface epitopes of multiple strains of nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHI) is a significant cause of otitis media in children and exacerbations in patients with chronic obstructive pulmonary disease. Vaccine research for NTHI has focused on the outer membrane proteins (OMPs) of NTHI. The goal of this study was to evaluate mucosal and systemic immune responses to recombinant OMP P2 (rP2) of NTHI. Enzyme-linked immunosorbent assay (ELISA) demonstrated that both mucosal and systemic routes of immunization resulted in antibodies to rP2. Whole-cell ELISA and flow cytometry indicated that mucosal immunization induced antibodies to epitopes that are on the bacterial surface of the homologous strain as well as several heterologous strains. In contrast, systemic immunization induced antibodies to non-surface exposed epitopes. These data show for the first time that mucosal immunization of mice with rP2 induces antibodies that recognize surface exposed epitopes on multiple strains, indicating that P2 is a candidate for development of a mucosal vaccine for NTHI.

Promiscuous peptides on the nontypeable Haemophilus influenzae P6 outer membrane protein

INTRODUCTION

P6 outer membrane protein is one of the candidates for a vaccine formulation against nontypeable Haemophilus influenzae (NTHi) infection. As otitis-prone children who have recurrent episodes of acute otitis media because of NTHi show an impaired immune response to P6, an innovative approach to vaccination is required to augment their immune response.

RESULTS AND DISCUSSION

We previously identified human HLA-DR9-restricted T cell epitope peptide and highly immunogenic analog peptides on P6 for peptide vaccine candidates. To develop a vaccine formulation effective in the general population, we identified promiscuous T cell epitope peptides (p41-55, p71-85) on P6. In addition to stimulating with potentially promiscuous peptides (p30-44, p45-59) selected using a computer algorithm, we established peptide-specific T cell lines which respond to P6.

CONCLUSION

Our present results indicate that these peptides would be candidates for a widely applicable peptide vaccine formulation.

Effects of macrolides on antigen presentation and cytokine production by dendritic cells and T lymphocytes

Macrolides are effective therapeutic agents for chronic respiratory tract diseases, such as chronic sinusitis, sinobronchial syndrome and diffuse panbronchiolitis. Although only limited information is available about their mechanisms, suppression of various inflammatory cytokines (IL-8, etc.) and some transcription factors has been reported to be involved. Non-typeable Haemophilus influenzae (NTHI) is one of the most important pathogens of the respiratory tract. P6 is one of the outer membrane proteins of NTHI and the target antigen of protective antibodies. To analyze the influence of macrolides on human dendritic cells (DCs), we treated DCs with macrolides and used them as antigen-presenting cells (APCs). Clarithromycin, roxithromycin and prednisolone suppressed the in vitro proliferative response of CD4+ T cells to P6 and also the production of cytokines. As a control, we also cultured DCs alone and exposed them to the medicament, while conversely culturing T cells without adding any drugs to the cultures. The results showed similar tendencies for suppression of immune responses. These findings suggest that macrolides suppress the antigen-specific immune responses of DCs in vitro.

Identification of human T-cell epitopes and highly immunogenic analog peptides on the non-typeable Haemophilus influenzae P6 outer membrane protein

P6 outer membrane protein is one of the candidates for a vaccine formulation against non-typeable Haemophilus influenzae (NTHi) infection. However, otitis-prone children who have recurrent episodes of acute otitis media due to NTHi fail to respond adequately to P6. An innovative approach to vaccination is therefore required to augment such children's immune response. To develop an effective peptide vaccine, we established P6-specific CD4(+) T-cell lines (TCLs) restricted by the human histocompatibility leukocyte antigen (HLA)-DR9 molecule, and revealed a human T-cell epitope on P6 and its core peptide sequence (p77-85; EYNIALGQR). Furthermore, we found that 3 analog peptides, E77D (the substitution of E at position 77 with D), N79G, and R85K, induced high proliferative responses as well as marked cytokine production when compared to the T-cell epitope peptide. These peptides may be candidates for a peptide vaccine formulation effective against NTHi infections, even in otitis-prone children.

Predictors for Haemophilus influenzae colonization, antibiotic resistance and for sharing an identical isolate among children attending 16 licensed day-care centers in Michigan

BACKGROUND

Nontypable Haemophilus influenzae is an important cause of otitis media in children. Children attending day-care centers are at an increased risk for nontypable H. influenzae colonization and otitis media. We describe the prevalence of nontypable H. influenzae colonization, antibiotic resistance and predictors for colonization and sharing an identical isolate with at least 1 other child in the same day-care centers among children attending 16 day-care centers.

METHODS

Throat swabs of 198 children < 3 years old attending 16 day-care centers were cultured for H. influenzae. Day-care center directors and parents completed risk factors questionnaires. Nontypable H. influenzae isolates were screened for antibiotic resistance and genotyped. Statistics were performed using SAS software (SAS Institute, Inc., Cary, NC).

RESULTS

We isolated 179 unique nontypable H. influenzae strains from 127 participants. Colonization ranged from 0% to 95% among day-care centers. As individual factors, exposure to tobacco smoke was associated with colonization (P = 0.05), and racial self-identifications as "other" (nonwhite, nonblack) was protective (P = 0.035), whereas as "black" was protective for sharing (P = 0.03). Pacifier use was associated with sharing (P = 0.04), but not with colonization. As day-care centers factors, rates of colonization and sharing were higher in day-care centers with > or = 5 classrooms (P < 0.01 and P = 0.03), with such suboptimal hygiene habits as minimal hand washing by staff after eating (P < 0.002 and P < 0.01) or by children after wiping their own nose (P = 0.01 and P = 0.003). Of colonized children, 41% presented a beta-lactamase-producing strain. Colonized children were more likely to carry resistant strains if they were taking an antibiotic (P = 0.02).

CONCLUSION

Although day-care center colonization varied, the overall colonization rate was high. Colonization with nontypable H. influenzae, with beta-lactamase-producing strain and sharing were, mostly, associated with modifiable risk factors.

The Role of Mucosal Immunity: An Update

There is considerable evidence that the mucosa associated lymphoid tissues (MALT) of the body play an active part in triggering off and conducting the immune system's response to both viral and bacterial pathogens. Effectors are capable of intercepting the micro-organisms and rendering them harmless before they penetrate through the mucous membranes, or of expelling and inactivating them after they have penetrated. The system is consequently useful both in the prevention of infection and in the humoral or cellulo-mediated immune response. These operations, whose principal protagonists are Immunoglobulins A and dendritic cells, are made possible by the high degree of functional interconnection which binds the effectors of the system and the anatomical structures located in the mucosae. The data provided in literature consequently infer that appropriate stimulation of mucosal immunity, which takes into account the new acquisitions in the field of immunology, can enable oral vaccination to overcome the obstacles encountered up till now in terms of insufficient protection against diseases.

Detection of specific antibodies in cord blood, infant and maternal saliva and breast milk to staphylococcal toxins implicated in sudden infant death syndrome (SIDS)

The common bacterial toxins hypothesis of sudden infant death syndrome (SIDS) is that nasopharyngeal bacterial toxins can trigger events leading to death in infants with absent/low levels of antibody that can neutralise the toxins. The aim of this study was to investigate nasopharyngeal carriage of Staphylococcus aureus and determine levels of immunity in the first year of life to toxic shock syndrome toxin (TSST-1) and staphylococcal enterotoxin C (SEC). Both toxins have been implicated in SIDS cases. Seventy-three mothers and their infants (39 males and 34 females) were enrolled onto the study. The infants had birth dates spread evenly throughout the year. In infants, S. aureus carriage decreased significantly with age (P<0.001). Between 40% and 50% of infants were colonised with S. aureus in the first three months of life and 49% of the isolates produced one or both of the staphylococcal toxins. There was a significant correlation between nasopharyngeal carriage of S. aureus in mothers and infants in the three months following the birth (P<0.001). Carriage of S. aureus in infants and their mothers was not significantly associated with levels of antibody to TSST-1 or SEC in cord blood, adult saliva or breast milk. Infants colonised by S. aureus had higher levels of salivary IgA to TSST-1 than infants who were culture negative. Analysis of cord blood samples by a quantitative ELISA detected IgG bound to TSST-1 and SEC in 95.5% and 91.8% of cases respectively. There was a marked variation in levels of maternal IgG to both TSST-1 and SEC among cord blood samples. Maternal age, birth weight, and seasonality significantly affected the levels of IgG binding to TSST-1 or SEC. Analysis of infant saliva samples detected IgA to TSST-1 and SEC in the first month after birth; 11% of samples tested positive for salivary IgA to TSST-1 and 5% for salivary IgA to SEC. By the age of two months these proportions had increased to 36% and 33% respectively. More infants who used a dummy tested positive for salivary IgA to TSST-1 compared to infants who did not use a dummy. Levels of IgA to TSST-1 and SEC detected in the breast-milk samples varied greatly among mothers. There was a trend for infants receiving breast milk with low levels of antibody to TSST-1 or SEC to have higher levels of salivary antibody to the toxins. In conclusion, passive immunity to toxins implicated in SIDS cases varies greatly among infants. Infants are able to mount an active mucosal immune response to TSST-1 and SEC in the first month of life.

Effect of botulinum toxin type A on nasal symptoms in patients with allergic rhinitis: a double-blind, placebo-controlled clinical trial

OBJECTIVE

To investigate the possible beneficial effects of botulinum toxin type A (BTX-A) on nasal symptoms in patients with allergic rhinitis (AR).

MATERIAL AND METHODS

Thirty-four patients (21 females, 13 males; mean age 28 years) were included in the study. AR was diagnosed by means of history, clinical examination and skin prick test. Patients were randomly divided into 3 subgroups a follows: in Group A, 20 units of BTX-A was injected into each nasal cavity (total 40 units); in Group B, 30 units of BTX-A was injected into each nasal cavity (total 60 units); and in Group C, 2 ml of isotonic saline was injected as placebo. The symptoms of AR (rhinorrhea, nasal obstruction, sneezing, itching) were scored by the patient on a six-point scale (from 0 to 5). All of the patients were followed up at Weeks 1, 2, 4, 6 and 8; at each visit an anterior rhinoscopic examination was done and symptom scores were recorded.

RESULTS

There was no statistically significant difference between Groups A and B in terms of average symptom scores. Rhinorrhea, nasal obstruction and sneezing scores in Groups A and B were significantly better than those in Group C at all time points. Although itching scores were significantly lower at Weeks 1 and 2, there was no difference in the Week 4, 6 and 8 scores in Groups A and B. When total symptom scores were evaluated, the results for Groups A and B were similar but significantly better than those for Group C.

CONCLUSION

In selected cases, injection of 40 units of BTX-A into the turbinates, as a single agent, may help the symptomatic control of AR for up to 8 weeks.

Immunologic aspects of otitis media

The middle ear cleft is a modified gas pocket which functions normally when the gas contents are regulated by a normal eustachian tube, resulting in equalization of middle ear pressure to that of the environment. The most important regulator of this middle ear pressure is the eustachian tube, a critical passageway from the nasopharynx into the middle ear. Any alteration of eustachian tube mucociliary function caused by virus, allergy, pollutants, or alteration of the normal homeostasis of the nasopharynx will result in eustachian tube obstruction. This, in turn, leads to underventilation of the middle ear, and transudation of fluid. If bacteria or virus or viral-bacterial interaction leads to infectious disease of the middle ear, an immune response is produced as a result of the inflammatory response, allowing lymphocytes and antigen-presenting cells to enter into the middle-ear mucosa. This article summarizes the immunologic reactivity in the middle ear following a viral-bacterial inflammatory reaction in the middle-ear mucosa. Although secretory IgA is critical for protection of the nasopharynx, its function in the middle ear has still not been resolved. The evidence strongly suggests that IgG1 and IgG3 subclasses are responsible for eradication of middle ear pathogens. Finally, a review of alternative approaches to the prevention of otitis media is briefly discussed in this critical period of emergence of resistant bacteria to available antibiotics.

Lymphocyte proliferative response to P6 of Haemophilus influenzae is associated with relative protection from exacerbations of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by periodic exacerbations, some of which are caused by nontypeable Haemophilus influenzae (NTHI). P6 is an outer membrane lipoprotein that is highly conserved among strains of NTHI. We hypothesized that lymphocytes from patients with COPD who have exacerbations due to NTHI have a decreased ability to recognize P6. The in vitro lymphocyte proliferative response to P6 in 36 patients with COPD and 12 healthy control subjects was studied. Ten patients who had exacerbations due to NTHI in the previous 12 months showed statistically significant lower proliferation to P6 (stimulation index, log transformed mean +/- standard error 0.82 +/- 0.17) compared with 26 patients who had no exacerbations due to NTHI in the previous 12 months (1.42 +/- 0.13) and to 12 healthy control subjects (1.61 +/- 0.16). These three groups had no significant difference in the lymphocyte proliferative response to tetanus toxoid. There was no difference in serum antibody levels to P6 in the two groups with COPD. These results indicate that decreased proliferation of T cells to P6 is associated with exacerbations of COPD and suggest that the ability of T cells to recognize P6 is associated with relative protection from exacerbations due to NTHI.

Maternal immunization with pneumococcal polysaccharide vaccine in the third trimester of gestation

In a randomized, double blinded study, 23-valent pneumococcal polysaccharide vaccine (PSV) or conjugate Haemophilus influenzae type b (HbOC) vaccine was administered to 60 healthy women in the third trimester of gestation. Total IgG, IgG1, and IgG2 antibodies to pneumococcal serotypes 6B, 14, 19F and 23F were measured by ELISA in mothers prior to immunization, at delivery and 7 months after delivery, and in infants at birth (cord blood), 2 and 7 months after delivery. IgA was evaluated in breast milk at 2 and 7 months, and opsonophagocytic activity in cord blood. PSV was safe and immunogenic in pregnant women. Transplacental transmission of vaccine-specific antibodies was efficient. Maternal immunization with PSV resulted in significantly higher concentrations of pneumococcal antibodies in infants at birth and at 2 months of age, and greater functional opsonophagocytic activity of passively acquired IgG antibody.

Maternal vaccines

Acute lower respiratory illness (LRI) is the leading cause of disease worldwide as measured by disability-adjusted life years. New strategies are necessary to decrease the disease burden that is largely borne by infants. Respiratory syncytial virus is the most important cause of LRI in infants. Lower respiratory illness can be prevented by endowing infants with high levels of neutralizing antibodies from mothers whose antibodies are boosted during pregnancy with a potent subunit vaccine. Another important cause of infant mortality is group B streptococcus sepsis in the neonatal period; maternal immunization with a group B conjugate vaccine could prevent this devastating infection.

Breast feeding and the intestinal microflora of the infant--implications for protection against infectious diseases

Human breast milk contains an array of factors with anti-infectious potential, such as immunoglobulins (especially secretory IgA), oligosaccharides and glycoproteins with anti-adhesive capacity, and cytokines. Breast-feeding is associated with protection from the following infections or infection-related conditions: gastroenteritis, upper and lower respiratory tract infection, acute otitis media, urinary tract infection, neonatal septicaemia and necrotizing enterocolitis. Some of the protective effects may derive from an altered mucosal colonization pattern in the breast-fed infant. In other instances breast-fed infants develop less symptoms to the same microbe which causes disease in the bottle-fed infant. An example of an altered colonization pattern is that breast-fed infants have less P-fimbriated, but more type 1-fimbriated E. coli. This may protect against urinary tract infection in the breast-fed infant since P. fimbriae are the major virulence factor for urinary tract infection. An example of changed consequences of the same microbial colonization is that secretory IgA in the breast-milk protects very efficiently from translocation of intestinal bacteria across the gut mucosa by coating intestinal bacteria and blocking their interaction with the epithelium. This mechanism may protect the infant from septicaemia of gut origin and, possibly, necrotizing enterocolitis. Breast-milk is also highly anti-inflammatogenic and contains hormone like factors which counteract diarrhea. Thus, breast-fed infants may be colonized by recognized diarrheal pathogens and still remain healthy. Due to a less virulent intestinal microflora and decreased translocation breast-fed infants will obtain less stimuli for the gut immune system, resulting, in e.g., lower salivary IgA antibody titres.

Investigation of risk factors for penicillin-resistant Streptococcus pneumoniae carriage in Turkish children

BACKGROUND

Nasopharyngeal colonization plays an important role for infections caused by Streptococcus pneumoniae. Emergence of penicillin resistance in this organism has made it difficult to treat pneumococcal infections. The objectives of this study were to investigate the risk factors for nasopharyngeal colonization with S. pneumonia and for nasopharyngeal colonization with penicillin-resistant S. pneumoniae.

METHODS

Three hundred children with or without evidence of infection were investigated for various risk factors. Streptococcus pneumoniae isolated from children's nasopharyngeal swabs were examined for penicillin susceptibility.

RESULTS

Day-care attendance (odds ratio OR=2.82, P=0.003) and upper respiratory tract infection within the last month (OR=1.83, P=0.02), have been determined to be risk factors for S. pneumoniae carriage. The use of antibiotics within the last 3 months (OR=81.07, P<0.001), the presence of more than five people living in the house of the child (OR=6.63, P=0.03), and having a sibling under 5-years-old (OR=4.60, P=0.03) have been determined to be risk factors for penicillin-resistant S. pneumoniae carriage.

CONCLUSION

Some children are inevitably exposed to and colonized with penicillin susceptible or resistant S. pneumoniae. Changes in day-care organizations, better living conditions, and restriction of antibiotic use seems to be useful precautions to prevent the emerging and colonization with penicillin-susceptible or -resistant S. pneumoniae.

Host defense benefits of breastfeeding for the infant. Effect of breastfeeding duration and exclusivity

Breastfeeding confers lifesaving protection against infectious illness among disadvantaged populations. As a result, breastfeeding promotion has an important part in child health programs throughout the world. In this article, the evidence regarding the host defense benefits of breastfeeding for term infants of normal birth weight is reviewed, with an emphasis on recent information from industrialized countries regarding how the degree and duration of breastfeeding affect infant health.

Passive immunization for the prevention of otitis media

The safety and protective efficacy of exogenously-administered immunoglobulin for the prevention of otitis media has been demonstrated in the clinical trials of the human-derived polyclonal immune globulin used to prevent Haemophilus influenzae type b disease and respiratory syncytial virus infection in high risk neonates and young children. However, this form of therapy is expensive, difficult to administer due to the requirements of slow intravenous infusion or relatively large volumes given intramuscularly, and associated with side effects related to the volume and nature of the immunoglobulin preparation. In contrast, RSV-specific monoclonal antibody has not been as successful as human-derived immunoglobulin in preventing otitis media in high risk infants. The administration of monoclonal-antibody for the prevention of otitis media will be difficult, potentially due to the need for antibody to multiple epitopes of the viral and bacterial pathogens which could be targets. The use of maternal antibody to provide passive immunity to young infants at a time when they are most vulnerable to severe sequelae of infection can also be considered. We have studied maternal immunization using either a 23-valent pneumococcal polysaccharide vaccine or a conjugate H. influenzae type b (Hib) vaccine. Significant levels of maternally-derived Hib or pneumococcal antibody were transferred from the mother to the infant at the time of birth and persisting, for some antigens, through 2 months of age. The use of maternal immunization to prevent otitis media and other respiratory complications remains to be studied, but results of these small clinical trials indicate further clinical investigation is warranted.

Identification of a Haemophilus influenzae 5'-nucleotidase protein: cloning of the nucA gene and immunogenicity and characterization of the NucA protein

We report on the identification of a surface-exposed, highly conserved, immunogenic nontypeable Haemophilus influenzae (NTHi) protein, which elicits cross-reactive bactericidal antibodies against NTHi. The protein was extracted from NTHi strain P860295 with KSCN and purified; it migrated as a single band on a sodium dodecyl sulfate-polyacrylamide gel with an apparent molecular mass of 63 kDa. Mouse antiserum generated against the purified protein was reactive on whole-cell enzyme-linked immunosorbent assay (ELISA) with seven NTHi strains and type b Eagan and Whittier strains and exhibited bactericidal activity to homologous and heterologous NTHi strains. However, the protein is made in small amounts in NTHi as corroborated by immunoelectron microscopy. To further study this protein, we cloned, sequenced, and expressed it recombinantly in Escherichia coli. The recombinant protein is localized in the periplasm of E. coli and has been purified to homogeneity. Both the recombinant and native proteins possess 5'-nucleotidase activity; hence, the protein has been called NucA. Mouse antiserum directed against the recombinant NucA protein was reactive on Western immunoblots and whole-cell ELISA with all H. influenzae strains tested including Eagan and was bactericidal for two heterologous strains tested. The antiserum also resulted in a log reduction in bacteremia, in an infant-rat protection study with H. influenzae type b as the challenge strain. These features suggest that NucA is a potential subunit vaccine candidate against NTHi disease.

Risk factors for otitis media and carriage of multiple strains of Haemophilus influenzae and Streptococcus pneumoniae

We studied genetic diversity in Streptococcus pneumoniae and Haemophilus influenzae in throat culture isolates from 38 children attending two day-care centers in Michigan. Culture specimens were collected weekly; 184 S. pneumoniae and 418 H. influenzae were isolated from the cultures. Pulsed-field gel electrophoresis identified 29 patterns among the S. pneumoniae isolates and 87 among the H. influenzae isolates. Of the cultures, 5% contained multiple genetic types of S. pneumoniae, and 43% contained multiple types of H. influenzae. Carriage of multiple H. influenzae isolates, which was associated with exposure to smoking, history of allergies, and age 36 to 47 months, may increase risk for otitis media in children.

Purification and characterization of outer membrane protein P6, a vaccine antigen of non-typeable Haemophilus influenzae

Outer membrane protein P6 is a promising vaccine antigen with potential to prevent infections caused by non-typeable Haemophilus influenzae. A convenient and reliable method for the purification of P6 and an assessment of the purity, yield, protein structure, antigenicity and immunogenicity of the purified protein are described. The method begins with intact H. influenzae and utilizes a series of incubations and centrifugations using a single buffer to remove all cell components with the exception of the peptidoglycan to which the P6 is associated. P6 is dissociated from the complex with heat and the insoluble peptidoglycan is removed by centrifugation. The procedure yields highly purified P6. Contamination with lipooligosaccharide is less than 0.025 endotoxin U per microgr P6. The yield of P6 is approximately 2 mg of P6 per l H. influenzae culture. The purified P6 retains both the secondary and tertiary structure as measured by circular dichroism and analysis with monoclonal antibodies. The purified P6 is immunogenic in animals. A convenient method for purifying P6 which retains antigenicity and immunogenicity will be an important tool for future studies of the vaccine potential of P6.

Waldeyer's ring and otitis media: the nasopharyngeal tonsil and otitis media

This overview of the relationship between the nasopharyngeal tonsil and otitis media will review three important concepts: (1) Adenoid inflammation leads to inflammatory obstruction of the Eustachian tube; (2) early colonization of the adenoid with the three major bacterial pathogens of otitis media is the most important factor in the early pathogenesis of otitis media; (3) the local immune system in the adenoid particularly specific secretory IgA directed against both viruses and bacterial pathogens are probably genetically controlled and represent the immunological factor in protecting the host against invasion of these agents in the Eustachian tube and middle ear. This overview of the relationship between the adenoid and the development of otitis media emphasizes that nasopharyngeal colonization with the three major middle ear pathogens is among the most important risk factors in the pathogenesis of otitis media. Inasmuch as these pathogens normally reside in the nasopharynges of most healthy children, the factors which trigger development of otitis media need to be carefully evaluated. Among these two triggers are viral infections and upper respiratory tract allergy.

Immunization of mice with P6 of nontypeable Haemophilus influenzae: kinetics of the antibody response and IgG subclasses

The kinetics of the anti-P6 antibody response was characterized in three strains of mice of different haplotypes (Balb/c; H-2d, C3H/H; H-2k, SJL/J; H-2s). Anti-P6 antibodies were measured on a weekly basis by enzyme-linked immunosorbent assay (ELISA). The primary response peaked 2 or 3 weeks after the initial injection with 40 microg of purified P6. The response remained at a plateau for 8-10 weeks. A maximum titer of 1:1,638,400 was attained and then steadily declined. To study the ability of P6 to generate a recall response, we opted to boost the vaccinated mice with a known subimmunogenic dose of live nontypeable Haemophilus influenzae (NTHI) bacteria. After the anti-P6 antibody titers in the primed animals had stayed at baseline levels for 2 weeks, the mice were injected intraperitonealy with 10(8) cfu of NTHI in sterile saline. This challenge with live NTHI bacteria induced a very rapid and strong secondary antibody response in all mice. Finally, we demonstrated that these murine anti-P6 sera were 100% bactericidal against three strains of NTHI when tested in a complement dependant bactericidal assay.

The induction of systemic and mucosal immune responses following the subcutaneous immunization of mature adult mice: characterization of the antibodies in mucosal secretions of animals immunized with antigen formulations containing a vitamin D3 adjuvant

Systemic and mucosal immune responses were effectively induced following the subcutaneous administration of Haemophilus influenzae type b oligosaccharide conjugated to diphtheria toxoid vaccine in a formulation containing the active form of vitamin D3. IgA and IgG antibodies with specificity for both the protein and oligosaccharide components of the vaccine were detectable in mucosal secretions following immunization. The IgA and IgG mucosal antibodies were produced locally, and were functional as demonstrated by their diphtheria toxin neutralizing activity. Our data suggests that subcutaneous tissues can effectively serve as effective antigen presenting sites for both mucosal and systemic immune responses to antigens administered in combination with vitamin D3.

Cellular immune response of adenoidal and tonsillar lymphocytes to the P6 outer membrane protein of non-typeable Haemophilus influenzae and its relation to otitis media

Cellular immune responses to the P6 outer membrane protein of non-typeable Haemophilus influenzae (NTHi) were determined in vitro by measuring immunoglobulin (Ig) secreting cells and lymphocyte proliferation in adenoidal and tonsillar lymphocytes from 19 children. Preliminary tests showed that P6 did not stimulate naive cells such as cord blood lymphocytes, but did stimulate sensitized cells in adenoids and tonsils. Cellular proliferation was significantly higher in adenoidal lymphocytes than in tonsillar lymphocytes (median: quadratile of stimulation index = 3.7:2.3-5.5 vs. 1.2:1.0-2.1, p < 0.02). A comparison between children with or without otitis media revealed that proliferative responses to P6 of adenoidal lymphocytes from children with otitis media were significantly decreased (2.0:1.8-3.6 vs. 3.7:2.3-5.5, p < 0.04). P6-specific antibody secreting cells were identified in a total of 14 adenoids and the number of cells secreting IgA was decreased in the otitis media group compared to controls (median: quadratile/10(6) cells = 435:359-499 vs. 755:593-1870, p < 0.05). Cultivation with P6 stimulated IgA secretion in children without otitis media, while no response was seen in children with otitis media (median: quadratile/10(6) cells = 1323:915-2410 vs. 2240:1900-2830, p < 0.02). These preliminary data demonstrate that lymphocytes from adenoids and tonsils recognize P6 as a specific antigen and that the adenoid is the more reactive of the two organs. Impaired P6-specific cellular immune responses of adenoids in children with otitis media may explain the recurrent nature of otitis media due to NTHi in the otitis prone population.

Incidence of Haemophilus influenzae in the throats of healthy infants with different feeding methods

BACKGROUND

Haemophilus influenzae is the major cause of otitis media and lower respiratory tract infection in childhood. In the presence of human milk, which contains numerous host defense factors, Haemophilus influenzae may be inhibited in attaching to and colonizing pharyngeal cells. We investigated the incidence of H. influenzae in the throats of 162 healthy infants with different feeding methods: 70 breast-fed, 49 mixed-fed and 43 formula-fed infants.

METHODS AND RESULTS

Haemophilus influenzae was identified using standard microbiological procedures and the API NH system. The incidence of H. influenzae in breast-fed infants, mixed-fed infants and formula-fed infants was 0, 0 and 7.0% respectively.

CONCLUSION

The results suggest that the colonization of H. influenzae in the throat was inhibited by the presence of breast milk.

Risk factors for carriage of respiratory pathogens in the nasopharynx of healthy children. Ascanius Project Collaborative Group

OBJECTIVES

To assess risk factors for nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in a large sample of healthy children.

METHODS

In this point prevalence survey nasopharyngeal specimens were obtained from 1723 healthy children, ages 1 to 7 years, attending day-care centers or schools in 18 Italian cities. Written questionnaires for obtaining information about the demographics and medical history of the children were completed by the parents in the presence of a pediatrician.

RESULTS

The overall carrier rate of respiratory pathogens was 17.9% (S. pneumoniae, 3.5%; H. influenzae, 11.9%; M. catarrhalis, 4.1%). Only 5% of S. pneumoniae strains were penicillin-resistant whereas approximately 40% were erythromycin-resistant. Beta-lactamase production was found in 5.8% of H. influenzae and 88.7% of M. catarrhalis isolates. By multivariate analysis age (< or = 3 years), having older siblings, a history of prolonged full-time day-care attendance and living in a rural area significantly influenced the odds of carrying nasopharyngeal respiratory pathogens, particularly in children ages 1 to 5 years. Sex, breastfeeding, passive smoking and recent upper respiratory tract infections were not significant variables. Antibiotic treatment in the previous 3 months did not affect nasopharyngeal carriage, whereas repeated treatments with a macrolide were associated with carriage of S. pneumoniae.

CONCLUSIONS

Our results suggest that there is a strong and long term relationship between exposure to large numbers of children in the first years of life and nasopharyngeal carriage of all respiratory pathogens. In addition antimicrobial restrictive guidelines should be tailored to local microbiologic sceneries.

Specific mucosal immunity and enhanced nasopharyngeal clearance of nontypeable Haemophilus influenzae after intranasal immunization with outer membrane protein P6 and cholera toxin

Nontypeable Haemophilus influenzae (NTHi) is one of the leading pathogens in otitis media. Studies of vaccines against NTHi have focused on outer membrane proteins (OMPs). One outer membrane protein P6 is highly conserved among strains and is an attractive candidate for a subunit bacterial vaccine. In this study, mucosal immunity induced by intranasal immunization with P6 and cholera toxin (CT) was investigated in a mouse model. Intranasal immunization with P6 and CT evoked a good mucosal IgA as well as a systemic IgG response against P6. On the other hand, intranasal immunization with P6 alone induced a weak mucosal IgA response. Enzyme linked immunospot assay detected anti-P6 specific antibody producing cells in the nasopharyngeal mucosa of immunized mice. The protective response of intranasal immunization was demonstrated by enhancement of nasopharyngeal clearance of NTHi and inhibition of adherence of NTHi to cultured human epithelial cells. Based on these results, intranasal immunization with P6 and CT may be an effective approach to protect human from H. influenzae infections in the upper respiratory tract.

Immunonutrition: the pediatric experience

The health benefits of specific nutrients in the diet are reviewed as they pertain to the pediatric population and its unique needs. Secretory immunoglobulins, lysozyme, interferon, and growth factors, among others, are known to confer immunological advantages to breast milk. Inhibition of bacterial pathogens, as well as permissive growth of a protective colonic ecoflora occur as a result of various cellular and biochemical mechanisms at play. The immunomodulatory properties of minerals such as iron, zinc, and selenium, are presented and the newly recognized protective role of vitamin A and its importance in developing countries and in conditions of compromised nutrition are discussed. The review also covers the role of arginine, glutamine, and nucleotides in adaptive responses of the developing gut and in pathologic states such as necrotizing enterocolitis, short bowel syndrome, and inflammatory bowel disease. Probiotics (specific microbial feeds with potential benefits to the host), and prebiotics (dietary components such as complex carbohydrates able to change the colonic microenvironment fostering colonization with non-enteropathogens) are areas of current interest because they offer alternatives for the management of the growing problem of multiple antibiotic resistance and overwhelming infections in the hospitalized patient.

Nontypeable Haemophilus influenzae: pathogenesis and prevention

In this paper, we describe the ability of nontypeable Haemophilus influenzae (NTHi) to coexist with the human host and the devastating results associated with disruption of the delicate state of balanced pathogenesis, resulting in both acute and chronic respiratory tract infections. It has been seen that the strains of NTHi causing disease show a marked genetic and phenotypic diversity but that changes in the lipooligosaccharide (LOS) and protein size and antigenicity in chronically infected individuals indicate that individual strains of NTHi can remain and adapt themselves to avoid expulsion from their infective niche. The lack of reliance of NTHi on a single mechanism of attachment and its ability to interact with the host with rapid responses to its environment confirmed the success of this organism as both a colonizer and a pathogen. In vitro experiments on cell and organ cultures, combined with otitis media and pulmonary models in chinchillas, rats, and mice, have allowed investigations into individual interactions between NTHi and the mammalian host. The host-organism interaction appears to be a two-way process, with NTHi using cell surface structures to directly interact with the mammalian host and using secreted proteins and LOS to change the mammalian host in order to pave the way for colonization and invasion. Many experiments have also noted that immune system evasion through antigenic variation, secretion of enzymes and epithelial cell invasion allowed NTHi to survive for longer periods despite a specific immune response being mounted to infection. Several outer membrane proteins and LOS derivatives are discussed in relation to their efficacy in preventing pulmonary infections and otitis media in animals. General host responses with respect to age, genetic makeup, and vaccine delivery routes are considered, and a mucosal vaccine strategy is suggested.

The microbial ecology and immunology of the adenoid: implications for otitis media

The nasopharyngeal tonsil, or adenoid, is a major inductive site for the synthesis of J-chain-positive B cells that may migrate to other areas of the upper respiratory tract, such as the nasal mucosa, the parotid gland, the lacrimal gland, and the middle ear during inflammation. The production of secretory IgA by both the nasopharyngeal tonsil and the nasal mucosa plays a major role in local immune protection against bacteria and viruses. The release of cytokines from Th1 and Th2 lymphocytes must be appropriate for B cells to produce IgA. The factors or mechanisms responsible for this are not, at present, known, but it appears that there is a difference in the profiles of cytokine secretion by Th1 and Th2 lymphocytes in the adenoids in both otitis-prone, as well as nonotitis-prone children. We have suggested that if this specific immune system does not protect the host from invasion by potential pathogens, there are other modalities of therapy to protect the nasopharynx from colonization with pathogenic bacteria or viruses. These include the production of specific antibodies against bacterial surface proteins that have been identified as mucin-binding proteins. Alteration of the microbial flora with commensal organisms such as viridans streptococci can be utilized. These alpha-hemolytic streptococci probably function by producing an acid environment that prevents colonization of organisms such as nontypeable H. influenzae. Finally, the induction of specific SIgA by conserved outer membrane protein antigens of potential pathogens may be another strategy in the prevention of colonization of potential bacterial pathogens in the nasopharynx.

Exclusive breastfeeding protects against bacterial colonization and day care exposure to otitis media

OBJECTIVE

We followed a cohort (N = 306) of infants at well-baby visits in two suburban pediatric practices to assess the relation of exclusive breastfeeding, and other environmental exposures, to episodes of acute otitis media (AOM) and otitis media with effusion (OME).

METHODS

Detailed prospective information about the exclusiveness of breastfeeding, parental smoking, day care attendance, and family history was obtained at scheduled clinic visits. Tympanometric and otoscopic examinations were used in the diagnosis of otitis media (OM). Nasopharyngeal cultures were performed at 1-6 months, and at 8, 10, 12, 15, 18, and 24 months of age to detect colonization with middle-ear pathogens.

RESULTS

Between 6 and 12 months of age, cumulative incidence of first OM episodes increased from 25% to 51% in infants exclusively breastfed and from 54% to 76% in infants formula-fed from birth. Peak incidence of AOM and OME episodes was inversely related to rates of breastfeeding beyond 3 months of age. A twofold elevated risk of first episodes of AOM or OME was observed in exclusively formula-fed infants compared with infants exclusively breast-fed for 6 months. In the logistic regression analysis, formula-feeding was the most significant predictor of AOM and OME episodes, although age at colonization with middle-ear pathogens and day care (outside the home) were significant competing risk factors. A hazard health model suggested additionally that breastfeeding, even for short durations (3 months), reduced onset of OM episodes in infancy.

CONCLUSIONS

Modifiable factors in the onset of AOM and OME episodes during the first 2 years of life include early age at colonization (</=3 months of age), day care outside the home, and not being breastfed.

Adherence of non-typeable Haemophilus influenzae promotes reorganization of the actin cytoskeleton in human or chinchilla epithelial cells in vitro

Non-typeable Haemophilus influenzae (NTHi) are opportunistic mucosal pathogens which adhere to epithelial cells via a variety of non-specific and specific interactions. Several adhesins have been identified and while the complimentary receptor(s) for each of these adhesins has not yet been fully characterized, it is widely accepted that adherence is an absolute prerequisite for disease. Several reports have indicated that NTHi can also be internalized and reside intracellularly. For this to occur, NTHi must be taken up by mucosal epithelial cells lining the respiratory tract. We have noted, by TEM, that adherent NTHi overlie an electron dense area in the cell membrane of human epithelial cells which is associated with a localized complex assembly of cytoskeletal fibers in the eukaryotic cytoplasm. We thus examined the potential involvement of cytoskeletal actin in this phenomenon via FITC-phalloidin labeling of respiratory tract epithelial cells which had been incubated with several clinical isolates of NTHi. Strong punctate fluorescence was coincident with adherent NTHi to both human oropharyngeal and chinchilla middle ear epithelial cells. This reactivity was similar to the discrete fluorescent spots observed with enteropathogenic Escherichia coli which were adhered to HeLa cells. In contrast, none of the NTHi isolates tested induced actin polymerization in cells of endothelial origin. While the exact mechanisms involved are yet to be elucidated, our data indicated that actin nucleation was coincident with NTHi adherence.

Kinetics of the ascension of NTHi from the nasopharynx to the middle ear coincident with adenovirus-induced compromise in the chinchilla

To determine the kinetics of ascension of the eustachian tube (ET) by non-typeable Haemophilus influenzae (NTHi) in situ from the nasopharynx to the middle ear using an experimental model of otitis media (OM), we examined snap-frozen sections of chinchilla ET and middle ear mucosa for adherent bacteria over a 14 day time period. Via fluorescent- and transmission electron-microscopy, we found that NTHi preferentially adhered not to the epithelial cells but to the mucus in the ET and gradually ascended this tubal organ, reaching the middle ear approximately 10 days after intranasal inoculation of adenovirus-infected animals. The number of NTHi adherent to mucus at the pharyngeal portion of the ET increased significantly in the first 4 days after inoculation of the nares whereas the number of adherent bacteria in both the mid and tympanic portions of the ET increased more gradually over time. NTHi were not observed in the middle ear until approximately 7-10 days after inoculation of the nares which was coincident with the onset of clinical signs of OM. These data confirmed our earlier in vitro investigation which suggested that adherence to and growth within stagnant mucus within a ET compromised by adenovirus was a possible mechanism by which NTHi, resident in the nasopharynx, might gain access to the middle ear and induce OM.

Urinary biotinidase and alanine excretion in patients with insulin-dependent diabetes mellitus

Twenty-four-hour urine specimens from 21 juvenile insulin-dependent diabetics and 10 healthy controls were compared with respect to biotinidase activity and alanine content. Urinary biotinidase activity was analysed by a newly developed high-performance liquid chromatography (HPLC) method. It was found that the excretion of biotinidase in urine was elevated in diabetics (7.02 mU/d; p < 0.005) as compared with controls (not detectable). Alanine excretion was also found to increase (p < 0.01) in diabetics. Biotinidase excretion in diabetics was correlated with alanine excretion (rS = 0.667; p < 0.01), but not with protein, albumin or N-acetyl-beta-glucosaminidase excretion. The simultaneous elevation of urinary biotinidase and alanine excretion in juvenile diabetics suggests that changes in kidney metabolism arise in the early stages of diabetes.

Mapping of a surface-exposed, conformational epitope of the P6 protein of Haemophilus influenzae

P6 is an outer membrane protein of Haemophilus influenzae that is antigenically conserved and considered a candidate component of future H. influenzae vaccines. P6 contains a surface-exposed epitope recognized by monoclonal antibody (MAb) 3B9. This epitope has been shown to be distinct from that recognized by the P6-specific MAbs 7F3 and 4G4 in a competitive inhibition enzyme-linked immunosorbent assay (ELISA). MAb 3B9 did not bind to synthetic P6-specific sequential and overlapping hexameric peptides. Five peptides made to correspond to P6 sequences with high probabilities of surface exposure did not inhibit binding of MAb 3B9 to P6. An antiserum to one of the peptides, designated SP66, inhibited binding of MAb 3B9 to P6. A rabbit antiserum to P6 bound to sequential hexameric peptides, Gly-87AsnThrAspGluArgGlyThr-94, which were in the SP66 region of P6. This antiserum inhibited the binding of P6 to MAb 3B9 in a competitive inhibition ELISA. P6 mutations with His and Ala substitutions at residues Thr-88 and Asn-89 still bound MAb 3B9. MAb 3B9 reacted with Escherichia coli OmpA and Salmonella typhimurium OmpA. Sequence comparisons of P6 with these proteins indicated that the residue in the SP66 region responsible for binding is either Gly-87, Asp-90, or Gly-93. Mercaptoethanol reduction abolished MAb 3B9 binding to E. coli OmpA and S. typhimurium OmpA. In these proteins, immediately downstream of the second cysteine, there is an ArgArg dipeptide which is identical to and aligns with Arg-147Arg-148 in P6. This dipeptide has a high probability of surface exposure in P6. Mutagenesis of the Arg-147Arg-148 to an AlaAla dipeptide in P6 abolished binding of MAb 3B9, demonstrating that it was either a portion of the epitope or important in the protein folding necessary for expression of this epitope. This study demonstrates that MAb 3B9 recognizes a conserved conformational determinant on the surface of H. influenzae that is composed of two discontinuous regions of P6.

Enhanced respiratory clearance of nontypeable Haemophilus influenzae following mucosal immunization with P6 in a rat model

Nontypeable Haemophilus influenzae (NTHi) is a common cause of infection of the respiratory tract in children and adults. The search for an effective vaccine against this pathogen has focused on components of the outer membrane, and peptidoglycan-associated lipoprotein P6 is among the proposed candidates. This study investigated the immunogenicity of P6 in a rat respiratory model. P6 was purified from two strains of NTHi, one capsule-deficient strain and an H. influenzae type b strain, and assessed for clearance of both homologous and heterologous bacterial strains following mucosal immunization. A protective immune response was determined by enhancement of pulmonary clearance of live bacteria and an increased rate of recruitment of phagocytic cells to the lungs. This was most effective when Peyer's patch immunization was accompanied by an intratracheal (IT) boost. However, the rate of bacterial clearance varied between strains, which suggests some differences in anti-P6 immunological defenses recognizing the expression of the highly conserved P6 lipoprotein on the bacterial surface in some strains. P6-specific antibodies in both serum and bronchoalveolar lavage fluid were cross-reactive and did not differ significantly in strain specificity, demonstrating that difference in clearance was unlikely due to differences in P6-specific antibody levels. Serum homologous and heterologous P6-antibody was bactericidal against NTHi even when enhanced clearance had not been observed. Peyer's patch immunization induced P6-specific CD4+ T-helper cell proliferation in lymphocytes isolated from the mesenteric lymph nodes. An IT boost increased the level of P6-specific antibodies in serum and bronchoalveolar lavage fluid, and P6-specific mesenteric node lymphocyte proliferation. Cells from rats immunized with P6 demonstrated proliferation following stimulation with P6 from nonhomologous strains; however, there was some variation in proliferative responses to P6 from different strains in lymphocytes isolated from animals immunized with killed bacteria. The increase in P6-specific antibodies and T-helper cell responses following an IT boost correlated with an increased rate of recruitment of phagocytic cells and enhanced bacterial clearance of both homologous and heterologous bacteria in the lungs. The data suggests that P6 has the potential to afford protection against pulmonary infection by NTHi following the induction of effective antigen-specific B- and T-cell responses in mucosal tissues.