Evaluation of the innate pulmonary immune response in invasive pneumococcal disease: immunological challenges and implications for occupational health and built environments

Abstract

Invasive pneumococcal disease (IPD) is a severe condition with high mortality, characterized by an intense pulmonary inflammatory process. This study investigated the innate immune response in situ in the lungs of patients who died from IPD, comparing 22 necropsy cases with 26 controls. Results showed a significant increase in macrophages and polymorphonuclear cells, as well as in exudative phenomena such as edema and intra-alveolar hemorrhage. A prominent inflammatory response was observed, with reduced apoptosis and significant increases in pro-inflammatory cytokines (except IL-6 and IL-8), Toll-2, complement activation, and ICAM-1 and CD14 expression. There was a significant decrease in natural killer (NK) and Langerhans cells, along with low levels of IL-6 and IL-8, reflecting impaired innate immunity. It was concluded that severe tissue damage in IPD results from partial compromise of innate immunity and reduced apoptosis, possibly as an immune evasion strategy of the pneumococcus. Understanding this pathogenesis is crucial for developing better prevention and management strategies, especially for vulnerable populations in built and occupational environments.