The anti-microbial peptide LL-37 modulates immune responses in the palatine tonsils where it is exclusively expressed by neutrophils and a subset of dendritic cells.
Sigurdardottir. Sigrun L SL; Thorleifsdottir. Ragna H RH; Guzman. Andrew M AM; Gudmundsson. Gudmundur H GH; Valdimarsson. Helgi H; Johnston. Andrew A
Key Findings
- LL‑37 is produced in the tonsils primarily by infiltrating neutrophils and CD11c+CD13+HLA‑DR+ dendritic cells, not by the epithelium.
- In vitro exposure of tonsil mononuclear cells to LL‑37 triggers release of pro‑inflammatory cytokines CCL5 and CXCL9.
- LL‑37 exposure increases IFN‑γ and MX‑1 expression while lowering chemokine receptors CCR4 and CCR6, indicating a shift in T‑cell trafficking signals.
Practical Outcomes
- For most biohackers, the findings don’t translate into a direct supplement or protocol because the work is limited to tonsil tissue and uses lab‑based concentrations. It does highlight that LL‑37 can modulate immune signaling, which may be of interest for future research into immune‑boosting strategies, but no actionable dosing or safety guidance is provided.
Summary
The study shows that the antimicrobial peptide LL‑37 is made mainly by certain immune cells (neutrophils and a type of dendritic cell) in the tonsils, not by the lining cells. When tonsil cells are exposed to LL‑37 in the lab, they release inflammatory signals and change some receptors that guide immune cells, suggesting LL‑37 can tweak local immune responses.
Abstract
Antimicrobial peptides are essential elements of epithelial defense against invading micro-organisms. The palatine tonsils are positioned at the entry of the airway and the gut and as such are ideally situated to act as immune sentinels in the pharynx protecting against microbial invasion. Tonsils express a number of antimicrobial peptides including hCAP18/LL-37. Here we clearly define the expression of hCAP18/LL-37 in the tonsils showing unequivocally that hCAP18/LL-37 is mainly expressed by infiltrating neutrophils and follicular CD11c+CD13+HLA-DR+ dendritic cells, rarely by macrophages, and never by the epithelium itself. To explore possible functions for follicle-derived LL-37, we stimulated tonsil mononuclear cells with LL-37 in vitro and observed the secretion of the proinflammatory cytokines CCL5 and CXCL9, expression of IFN-γ and MX-1 and down-regulation of chemokine receptors CCR4 and CCR6 which are involved in tissue-selective T cell trafficking. Taken together, these data illustrate new potential immunoregulatory functions for hCAP18/LL-37 in the tonsils.
Study Information
pubmed
2011
2011-10-07T00:00:00.000Z
10.1016/j.clim.2011.09.013
16
64