Antimicrobial peptides in elderly patients with community-acquired pneumonia

Atypical pneumonia is a disease caused by intracelular, bacterial and viral, pathogens that clinically differs compared to the typical pneumonia clinical presentation and response to common antibiotic treatment. Both types of community acquired pneumonia accounts for the considerable mortality in the elderly population, and rapid initiation of antibiotic therapy is therefore critical. Moreover, due to present comorbidities in elderly population clear differentiation between two diseases prerequisites the new molecular markers, able to clearly distinguish types of pneumonia. Antimicrobial peptides, alpha (hNP1-3) and beta (hBD1 and 2) defensins, are innate immune mediators able to directly affect different microorganisms. They also exhibit potent immunomodulatory activity as potent chemokines, orchestrating inflammatory cell influx and downstream pathology. We measured hNP1- 3, hBD1 and hBD2 levels in sera from elderly patients with typical pneumonia (N=20), elderly patients with atypical pneumonia (N=30) and age- matched healthy controls (N=18). Quantitative ELISA showed increased hBD2 whereas hNP1-3 levels were statistically lower in patients with typical pneumonia compared to healthy adults and patients with atypical pneumonia. Although patients with both types of pneumonia and healthy adults had comparable levels of hBD1, somewhat higher median in typical and lower in atypical patient group accounted for the statistically significant difference. Increased levels of hBD2 and lower hNP1-3 detected in sera of patients with typical pneumonia could be useful diversification biomarkers from healthy adults and patients with atypical pneumonia. Further analysis of hBD1 levels in atypical pneumonia subgroups, regarding pathogen identity, possibly could enable to clearly distinguish viral from bacterial atypical pneumonia.