Towards a vaccine for chronic obstructive pulmonary disease

An Oral Whole-Cell Killed Nontypeable Haemophilus influenzae Immunotherapeutic For The Prevention Of Acute Exacerbations Of Chronic Airway Disease

In subjects with chronic bronchitis, protection against acute bronchitis following oral administration of a whole-cell killed nontypeable Haemophilus influenzae (NTHi) preparation was demonstrated in the mid-1980s. Subsequently, studies aiming to validate clinical efficacy of this oral treatment were complicated by a number of factors, including the modification of clinical definitions, the implications of which were not recognized at that time. The objective of this review is to integrate our pre-clinical and clinical research in this field conducted over the past 30 years to demonstrate the evolution of the idea of communication between mucosal surfaces through the common mucosal immune system and the development of an effective oral NTHi immunotherapy. Our earliest studies recruited subjects with chronic sputum production and high levels of culture-positive sputum for Gram-negative bacteria but by 2000, the clinical diagnostic focus had switched from “chronic bronchitis” to “chronic obstructive pulmonary disease” (COPD), which was functionally defined using spirometry. This change led to variable clinical trial results, confirming the importance of chronic sputum production and culture-positive sputum. Additional conditioning factors such as patient age and gender were influential in study populations with low culture-positive sputum production. Through this period, studies in human and in rodent models provided new insights into airway protection mechanisms and the pathogenesis of airway inflammation. Key findings were the importance of a dysbiosis within the airway microbiome, and the critical role of an interdependence between the bronchus and the gut, with a Peyer’s patch-dependent extra-bronchus “loop” controlling the composition of the bronchus microbiome. Within this context, intercurrent virus infections initiate a microbiome-dependant hypersensitivity reaction involving Peyer’s patch-derived Th17 cells. We conclude that whole-cell killed NTHi immunotherapy has consistent and significant benefits when examined in the context of changing clinical disease definitions, age and gender, and has the potential to change the natural history of chronic airway disease.

Nontypeable Haemophilus influenzae and chronic obstructive pulmonary disease: a review for clinicians

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of morbidity and mortality worldwide. In the lower airways of COPD patients, bacterial infection is a common phenomenon and Haemophilus influenzae is the most commonly identified bacteria. Haemophilus influenzae is divided into typeable and nontypeable (NTHi) strains based on the presence or absence of a polysaccharide capsule. While NTHi is a common commensal in the human nasopharynx, it is associated with considerable inflammation when it is present in the lower airways of COPD patients, resulting in morbidity due to worsening symptoms and increased frequency of COPD exacerbations. Treatment of lower airway NTHi infection with antibiotics, though successful in the short term, does not offer long-term protection against reinfection, nor does it change the course of the disease. Hence, there has been much interest in the development of an effective NTHi vaccine. This review will summarize the current literature concerning the role of NTHi infections in COPD patients and the consequences of using prophylactic antibiotics in patients with COPD. There is particular focus on the rationale, findings of clinical studies and possible future directions of NTHi vaccines in patients with COPD.

Understanding nontypeable Haemophilus influenzae and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Bacteria are frequently implicated in acute exacerbations of chronic obstructive pulmonary disease (COPD), but their influence on airway inflammation remains unclear. This review will focus on nontypeable Haemophilus influenzae (NTHi), its impact on host immune responses, and the potential for vaccination strategies in COPD.

RECENT FINDINGS

NTHi is associated with impaired immune function in patients with COPD. Features of the bacterium itself potentiate its ability to colonize the lower airways. An imbalance between bacterial load and host immunity may lend itself to the development of exacerbations. Oral immunotherapy may be a method of augmenting the host immune response and could provide protection from exacerbations.

SUMMARY

A causal link between NTHi and COPD exacerbations has not been clearly established. However, colonization of the lower airways by NTHi likely plays a significant role in the inflammatory state of COPD.