Haemophilus influenzae oral whole cell vaccination for preventing acute exacerbations of chronic bronchitis

Haemophilus influenzae oral vaccination for preventing acute exacerbations of chronic bronchitis and chronic obstructive pulmonary disease

BACKGROUND

Chronic bronchitis and chronic obstructive pulmonary disease (COPD) are serious conditions in which patients are predisposed to viral and bacterial infections resulting in potentially fatal acute exacerbations. Chronic obstructive pulmonary disease is defined as a lung disease characterised by obstruction to lung airflow that interferes with normal breathing. Antibiotic therapy has not been particularly useful in eradicating bacteria such as non-typeable Haemophilus influenzae (NTHi) because they are naturally occurring flora of the upper respiratory tract in many people. However, they can cause opportunistic infection. An oral NTHi vaccine has been developed to protect against recurrent infective acute exacerbations in chronic bronchitis.

OBJECTIVES

To assess the effectiveness of an oral, whole-cell NTHi vaccine in protecting against recurrent episodes of acute exacerbations of chronic bronchitis and COPD in adults. To assess the effectiveness of NTHi vaccine in reducing NTHi colonising the respiratory tract during recurrent episodes of acute exacerbations of COPD.

SEARCH METHODS

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (2017, Issue 1), MEDLINE (1946 to January 2017), Embase (1974 to January 2017), CINAHL (1981 to January 2017), LILACS (1985 to January 2017), and Web of Science (1955 to January 2017). We also searched trials registries and contacted authors of trials requesting unpublished data.

SELECTION CRITERIA

We included randomised controlled trials comparing the effects of an oral monobacterial NTHi vaccine in adults with recurrent acute exacerbations of chronic bronchitis or COPD when there was overt matching of the vaccine and placebo groups on clinical grounds. The selection criteria considered populations aged less than 65 years and those older than 65 years.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data from original records and publications for incidence and severity of bronchitis episodes and carriage rate of NTHi measured in the upper respiratory tract, as well as data relevant to other primary and secondary outcomes.

MAIN RESULTS

We identified six placebo-controlled randomised controlled trials with a total of 557 participants. These trials investigated the efficacy of enteric-coated, killed preparations of H influenzae in populations prone to recurrent acute exacerbations of chronic bronchitis or COPD. The vaccine preparation and immunisation regimen in all trials consisted of at least three courses of formalin-killed H influenzae in enteric-coated tablets taken at intervals (e.g. days 0, 28, and 56). Each course generally consisted of two tablets taken after breakfast over three consecutive days. In all cases the placebo groups took enteric-coated tablets containing glucose. Risk of bias was moderate across the studies, namely due to the lack of information provided about methods and inadequate presentation of results.Meta-analysis of the oral NTHi vaccine showed a small, non-statistically significant reduction in the incidence of acute exacerbations of chronic bronchitis or COPD (risk ratio (RR) 0.79, 95% confidence interval (CI) 0.57 to 1.10; P = 0.16). There was no significant difference in mortality rate between the vaccine and placebo groups (odds ratio (OR) 1.62, 95% CI 0.63 to 4.12; P = 0.31).We were unable to meta-analyse the carriage levels of NTHi in participants as each trial reported this result using different units and tools of measurement. Four trials showed no significant difference in carriage levels, while two trials showed a significant decrease in carriage levels in the vaccinated group compared with the placebo group.Four trials assessed severity of exacerbations measured by requirement for antibiotics. Three of these trials were comparable and when meta-analysed showed a statistically significant 80% increase in antibiotic courses per person in the placebo group (RR 1.81, 95% CI 1.35 to 2.44; P < 0.001). There was no significant difference between the groups with regard to hospital admission rates (OR 0.96, 95% CI 0.13 to 7.04; P = 0.97). Adverse events were reported in five trials but were not necessarily related to the vaccine; a point estimate is suggestive that they occurred more frequently in the vaccine group, however this result was not statistically significant (RR 1.43, 95% CI 0.70 to 2.92; P = 0.87). Quality of life was not meta-analysed but was reported in two trials, with results at six months showing an improvement in quality of life in the vaccinated group (scoring at least two points better than placebo).

AUTHORS' CONCLUSIONS

Analyses demonstrate that NTHi oral vaccination of people with recurrent exacerbations of chronic bronchitis or COPD does not yield a significant reduction in the number and severity of exacerbations. Evidence was mixed, and the individual trials that showed a significant benefit of the vaccine are too small to advocate widespread oral vaccination of people with COPD.

Bronchiectasis in Children: Current Concepts in Immunology and Microbiology

Bronchiectasis is a complex chronic respiratory condition traditionally characterized by chronic infection, airway inflammation, and progressive decline in lung function. Early diagnosis and intensive treatment protocols can stabilize or even improve the clinical prognosis of children with bronchiectasis. However, understanding the host immunologic mechanisms that contribute to recurrent infection and prolonged inflammation has been identified as an important area of research that would contribute substantially to effective prevention strategies for children at risk of bronchiectasis. This review will focus on the current understanding of the role of the host immune response and important pathogens in the pathogenesis of bronchiectasis (not associated with cystic fibrosis) in children.

Guidelines for the management of adult lower respiratory tract infections--summary

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Guidelines for the management of adult lower respiratory tract infections--full version

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Oral bacterial vaccines for the prevention of acute exacerbations in chronic obstructive pulmonary disease and chronic bronchitis

Oral vaccines using killed bacterial extracts have been used to prevent acute exacerbations of chronic obstructive pulmonary disease (COPD); however, they are not recommended by current clinical guidelines. Two systematic reviews have been published on the efficacy of oral vaccines. The first, on the effects of an oral whole-cell nontypeable Haemophilus influenzae vaccine (NTHi) found a significant decrease in the incidence of acute episodes of chronic bronchitis (Poisson rate ratio 0.666; 95% confidence interval (CI) 0.500, 0.887; P = 0.005), and a 58% reduction in the prescription of antibiotics 3 months after vaccination. The second review evaluated studies that used multicomponent vaccines. It found that the duration of exacerbations was significantly shorter in the treatment group (weighted mean difference -2.7 days, 95% CI -3.5 to -1.8). These reviews suggest that oral vaccines reduce the number, severity, duration, or both, of acute exacerbations. However, many of the primary trials on which they are based are small and methodologically flawed. Further trials are needed before the use of oral vaccines could be considered as part of the routine clinical management of patients with COPD or chronic bronchitis.

Chronic obstructive pulmonary disease: clinical signs and infections

Chronic obstructive pulmonary disease (COPD) is a pathological condition that involves excessive production of mucus, chronic cough and inflammatory changes leading to airway limitation. The most common cause of COPD is cigarette smoking. COPD can be categorized into either chronic bronchitis or emphysema; both conditions can be differentiated by age and the production of copious, tenacious sputum. Patients with COPD are susceptible to pulmonary infections of bacterial or viral origin. Nurses should be aware of the subtle differences in conditions and the usefulness of antibiotics in the treatment of acute bacterial exacerbations of chronic bronchitis.

COPDX: an update of guidelines for the management of chronic obstructive pulmonary disease with a review of recent evidence

Long-acting beta(2) agonists are an effective and convenient treatment for chronic obstructive pulmonary disease (COPD), but do not significantly improve lung function. The long-acting anticholinergic tiotropium, which can be taken once daily, decreases exertional dyspnoea and increases endurance by reducing hyperinflation. The role in COPD of the combination of a long-acting beta(2) agonist and a glucocorticoid in a single inhaler remains unclear. The minimum duration of an effective pulmonary rehabilitation program that includes exercise training is 6 weeks. Long-term treatment with inhaled glucocorticoids may reduce the rate of decline in lung function, but the effect is small. Aminophylline should no longer be routinely used in acute exacerbations of COPD. Non-invasive positive pressure ventilation (NPPV) reduces mortality and hospital stay in patients with acute hypercapnic ventilatory failure; it is also an effective weaning strategy for patients who require intubation. Further studies are required to clarify the role of NPPV in the long-term management of stable COPD.

Safety and immunogenicity of an oral inactivated whole-cell pseudomonas aeruginosa vaccine administered to healthy human subjects

This study examines the safety and immunogenicity of an oral, whole-cell Pseudomonas aeruginosa vaccine administered to healthy volunteers. Thirty subjects received an oral dose of Pseudostat in two timed, measured doses with serological follow-up to 56 days postvaccination. Following vaccination, several individuals were identified as antibody responders for all three immunoglobulin (Ig) isotypes tested, specifically against whole-cell P. aeruginosa extract and outer membrane proteins F and I. The mean pooled lipopolysaccharide antigen-specific IgA showed the most significant and constant increases in titer postdose, with a similar increase in titer for whole-cell P. aeruginosa extract-specific IgA. The results demonstrated an increased phagocytic ability of the selected macrophage cell line in post vaccination sera. Furthermore a significant increase in intracellular macrophage killing of opsonized P. aeruginosa was also demonstrated (82% on day 14 postdose) in the presence of the postvaccination sera. The safety component of the study did not show any vaccine-attributable adverse effects in any of the subjects, as documented by clinical evidence, hematology, and biochemistry profiles. We conclude that Pseudostat is safe and immunogenic in humans at this dose and that further studies to determine the appropriate dosage and efficacy are needed. In our study, we have shown that the most significant and sustained responses to oral vaccination in human adult volunteers were serum IgA levels and that pooled sera collected postimmunization have an increased capacity to promote opsonophagocytotic killing of P. aeruginosa.

Microbial pattern recognition receptors mediate M-cell uptake of a gram-negative bacterium

The receptors involved in the sampling of particulate microbial antigens by the gut are largely unknown. Here we demonstrate for the first time in an in vitro M-cell model and in situ in isolated murine intestinal segments that the receptors TLR-4, PAF-R, and alpha5beta1 integrin are all involved in mediating bacterial uptake associated with transcytosis. The pattern of expression of TLR-4 and alpha5beta1 integrin differed between M cells and enterocytes. There was increased apical expression of TLR-4 in M-cell cultures, and it was present on the apical surface of murine M cells but not enterocytes in situ. In contrast, PAF-R was expressed equally by both cell types in vitro and was abundantly expressed throughout the intestinal epithelium. Inhibition of TLR-4 and PAF-R, but not TLR-2, reduced gram-negative bacterial uptake by both cell types, whereas inhibition of the apically expressed alpha5beta1 integrin significantly reduced the ability of M cells to translocate bacteria. Hence, the involvement of each receptor was dependent not only on differences in the level of receptor expression but the cellular localization. Using bacteria that had mutations that affected the bacterial lipooligosaccharide structure indicated that the oligosaccharide moiety was important in bacterial uptake. Taken together, the data suggest that pathogen-associated molecular pattern interactions with pattern recognition receptors are key factors in M-cell recognition of intestinal antigens for mucosal immune priming.

Considerations for development of whole cell bacterial vaccines to prevent diarrheal diseases in children in developing countries

Enteric pathogens constitute a major pediatric threat in the developing world through their impact on morbidity and mortality, physical and cognitive development and cause and effect relationship with malnutrition. Although many bacterial pathogens can cause diarrheal diseases, a group of less than 10 including Shigella spp., enterotoxigenic Escherichia coli (ETEC), Vibrio cholerae, and possibly, Campylobacter jejuni account for a significant percentage of these diseases in developing countries. Rotavirus is also a major cause of diarrheal diseases. Vaccines against these agents offer a potentially effective control measure against these diseases, but safe, practical, and effective vaccines for many of these agents have yet to be realized. Many vaccine development approaches are under investigation, but the one that is currently most advanced and that has been most widely applied to enteric pathogens is the use of orally administered live or killed whole pathogen preparations. If inactivated, these vaccines will probably be administered as multiple doses with approximately 10(10) to 10(11) total particles per dose, but they are relatively safe for oral administration. Further, they may not require a buffer for delivery and can be stored in liquid formulations. Fewer doses may be required for some live attenuated pathogen vaccines, but a buffer will most likely be required for oral delivery and the product must be stored in a dried formulation. Also, safety becomes more of a concern with live pathogens depending on the degree of attenuation, host immunocompetence, and the total number and kinds of attenuated pathogens which may be present in a combined agent vaccine. Both live and killed whole pathogen vaccines can be immunogenic and have the possibility to serve as vectors for other antigens. Although many organisms and serotypes are clinically important, by exploiting antigenic cross reactivity and using some pathogen components as vectors for cloned antigens of other pathogens, it could be possible to induce immunity against major enteric pathogens/serotypes with <10 whole pathogen components in a multi-agent vaccine. Safe and effective mucosal adjuvants may in the future be useful in whole pathogen vaccines, but they do not seem to be essential for immunization. Further, dietary supplements such as zinc, mixed routes of delivery and new regimens are under study which may in the future enhance further the effectiveness of the whole pathogen vaccines which now seem realizable in the near term. For this to happen, however, a coordinated and committed effort is necessary now to address the immunologic, regulatory, manufacturing, testing and implementation issues which will be involved in the realization of this important product to benefit children's health worldwide.