The role of immunity in susceptibility to respiratory infection in the aging lung

Abstract

Respiratory tract infections, particularly pneumonia, are a leading cause of death in persons 65 years or older in both developed and developing countries. Because many attributes of immunity wane with advancing age, the elderly may be more susceptible to respiratory infections, even if they appear to be in good health. A decline in the ability of lymphoid tissues to mount an antigen-specific response (adaptive immunity) to specific microorganisms such as influenza virus or Streptococcus pneumoniae is thought to be an important factor in increasing susceptibility to respiratory tract infection with advancing age. However, abnormalities in innate immunity may also contribute to increased susceptibility to respiratory infections and have been poorly characterized in the elderly. Although changes in immune parameters such as T cell subsets and immunoglobulin concentrations have been observed in respiratory secretions from older healthy individuals compared to younger subjects, the significance of these changes for protective immunity in the lung is unknown. The incidence of pneumonia may be lessened by measures such as optimizing treatment of comorbid conditions, optimizing nutrition, and addressing swallowing disorders. The use of vaccines directed against the influenza virus and S. pneumoniae appears to have made an impact on the degree of morbidity and mortality, and perhaps, the incidence, of community-acquired pneumonia. However, better stimulation of specific immune responses with improved vaccines and more widespread use of these vaccines for protection of elderly individuals are needed.

Towards an Epitope-Based Human Vaccine for Influenza

“…52 In this population there is a decline in the activity of the immune system, the production of naive lymphocytes by the central lymphoid organs, the thymus Towards an Epitope-Based Human Vaccine for Influenza and bone marrow, is reduced and these individuals are more susceptible to various diseases and infections. 53 In addition, this group is under particular risk of rapid spread of infection in retirement homes where a large numbers of aged people are living in close proximity.…”

Innate immunity in aging: impact on macrophage function

“…Older individuals also have an increased incidence of bacterial infections in the lungs, urinary tract, skin and soft tissues in addition to a higher incidence of tuberculosis and herpes zoster reactivation. Infections in the elderly often are more severe and are likely to result in fatalities (Ginaldi et al ., 2001;Meyer, 2001). The increased incidence of infections and bacterial colonization suggest possible defects in the ability of epithelial cells and macrophages to function as effective barriers, to detect PAMPs and to establish effective antibacterial responses.…”

Cutting Edge: Impaired Toll-Like Receptor Expression and Function in Aging

“…1 and 2). There is an increased severity of pneumococcal, influenza, and respiratory syncytial viral infections in the elderly population (3)(4)(5)(6). For example, an estimated 90% of the 20,000 deaths that are attributed to influenza annually in the U.S. occur in persons aged Ն65 years (7).…”