Antimicrobial peptide LL-37 and its pro-form, hCAP18, in desquamated epithelial cells of human whole saliva

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Abstract

The antimicrobial peptide LL-37 is active against oral bacteria and has been demonstrated to be present in human saliva, but its distribution in different fractions of saliva is not known. LL-37 is formed from its intracellular pro-form, hCAP18, in an extracellular enzymatic reaction catalyzed by proteinase 3 and kallikrein 5. Here, we prepared cell-containing and cell-free fractions of unstimulated human whole saliva by centrifugation after depolymerization of mucins with dithiothreitol, and measured the levels of hCAP18/LL-37 in these fractions using ELISA. Cellular expression of hCAP18/LL-37 was determined by western blotting and immunocytochemistry. The ELISA analyses demonstrated that both cells and cell-free saliva contained hCAP18/LL-37. Western blot analysis of cell-pellet homogenates showed a strong band corresponding to hCAP18 at the correct molecular weight and a weak band corresponding to LL-37. Phase-contrast and light microscopy revealed that the cells consisted of desquamated epithelial cells. These cells expressed cytoplasmic immunoreactivity for hCAP18/LL-37. The peripheral part of the cytoplasm, corresponding to the plasma membrane, was particularly rich in hCAP18/LL-37 immunoreactivity. No immunoreactivity was observed after omission of the primary antibody. We conclude that desquamated epithelial cells of human whole saliva contain antimicrobial hCAP18/LL-37, suggesting that these cells may take part in the innate immune system by harboring and releasing these peptides.

Details

Authors
Organisations
External organisations
  • Swedish Dental Service of Skåne
  • Lund University
  • Karolinska Institutet
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell Biology
  • Cell and Molecular Biology
Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalEuropean Journal of Oral Sciences
Volume128
Issue number1
Early online date2019 Dec 11
Publication statusPublished - 2020 Feb
Publication categoryResearch
Peer-reviewedYes