Antibacterial components in bronchoalveolar lavage fluid from healthy individuals and sarcoidosis patients.
Agerberth. B B; Grunewald. J J; Castaños-Velez. E E; Olsson. B B; Jörnvall. H H; Wigzell. H H; Eklund. A A; Gudmundsson. G H GH
Key Findings
- LL‑37 is present in bronchoalveolar lavage fluid from both healthy people and sarcoidosis patients.
- Bronchoalveolar lavage fluid from sarcoidosis patients shows stronger overall antibacterial activity, linked to higher levels of LL‑37 and other antimicrobial proteins.
- LL‑37 is located inside alveolar macrophages, bronchial epithelial cells, and bronchial glands, indicating a direct defensive role in the airway lining.
Practical Outcomes
- For biohackers, the main takeaway is that LL‑37 contributes to airway immunity. While the paper doesn’t provide dosing or supplementation guidance, it suggests that strategies that naturally boost LL‑37 (e.g., vitamin D optimization) might support lung health, though further evidence is needed.
Summary
The study shows that the natural antimicrobial peptide LL‑37 is part of the lung’s defense system and is found in higher amounts in people with sarcoidosis, which may help explain why these patients rarely get serious lung infections.
Abstract
Antibacterial peptides and proteins are an integral part of the epithelial defense barrier that provides immediate protection against bacterial invasion. In humans, alpha-defensins are mainly bactericidal effectors in circulating granulocytes, beta-defensin-1 is synthesized in epithelial cells, and LL-37 is produced in granulocytes but is also induced in skin epithelia during inflammation. To investigate the importance of these defense effectors in disease, we analyzed bronchoalveolar lavage fluid (BALF) for bactericidal activity. Antibacterial activity was found in BALF material from healthy individuals and sarcoidosis patients, with enhanced activity in BALF from the patients. The activity was present as several antibacterial components, of which we have so far characterized LL-37, lysozyme, alpha-defensins, and antileukoprotease. In addition, the antibacterial peptide LL-37 was located in alveolar macrophages, bronchial epithelial cells, and bronchial glands, suggesting that it has a defensive role in airway mucosa. In conclusion, the airway epithelium is protected by a complex antibacterial defense system. This is activated in sarcoidosis, and may explain why these patients seldom develop severe respiratory tract infections.
Study Information
pubmed
1999
10.1164/ajrccm.160.1.9807041